414 files changed, 43749 insertions, 11094 deletions

diff --git a/vendor/tokio/.cargo-checksum.json b/vendor/tokio/.cargo-checksum.json
index 425c792f2..9ebc8be4d 100644
--- a/vendor/tokio/.cargo-checksum.json
+++ b/vendor/tokio/.cargo-checksum.json
@@ -1 +1 @@
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\ No newline at end of file
diff --git a/vendor/tokio/CHANGELOG.md b/vendor/tokio/CHANGELOG.md
index 806d44076..aea22c6d9 100644
--- a/vendor/tokio/CHANGELOG.md
+++ b/vendor/tokio/CHANGELOG.md
@@ -1,6 +1,1093 @@
-# 1.8.4 (November 15, 2021)
+# 1.29.1 (June 29, 2023)
 
-This release backports a bug fix from 1.13.1.
+### Fixed
+
+- rt: fix nesting two `block_in_place` with a `block_on` between ([#5837])
+
+[#5837]: https://github.com/tokio-rs/tokio/pull/5837
+
+# 1.29.0 (June 27, 2023)
+
+Technically a breaking change, the `Send` implementation is removed from
+`runtime::EnterGuard`. This change fixes a bug and should not impact most users.
+
+### Breaking
+
+- rt: `EnterGuard` should not be `Send` ([#5766])
+
+### Fixed
+
+- fs: reduce blocking ops in `fs::read_dir` ([#5653])
+- rt: fix possible starvation ([#5686], [#5712])
+- rt: fix stacked borrows issue in `JoinSet` ([#5693])
+- rt: panic if `EnterGuard` dropped incorrect order ([#5772])
+- time: do not overflow to signal value ([#5710])
+- fs: wait for in-flight ops before cloning `File` ([#5803])
+
+### Changed
+
+- rt: reduce time to poll tasks scheduled from outside the runtime ([#5705], [#5720])
+
+### Added
+
+- net: add uds doc alias for unix sockets ([#5659])
+- rt: add metric for number of tasks ([#5628])
+- sync: implement more traits for channel errors ([#5666])
+- net: add nodelay methods on TcpSocket ([#5672])
+- sync: add `broadcast::Receiver::blocking_recv` ([#5690])
+- process: add `raw_arg` method to `Command` ([#5704])
+- io: support PRIORITY epoll events ([#5566])
+- task: add `JoinSet::poll_join_next` ([#5721])
+- net: add support for Redox OS ([#5790])
+
+
+### Unstable
+
+- rt: add the ability to dump task backtraces ([#5608], [#5676], [#5708], [#5717])
+- rt: instrument task poll times with a histogram ([#5685])
+
+[#5766]: https://github.com/tokio-rs/tokio/pull/5766
+[#5653]: https://github.com/tokio-rs/tokio/pull/5653
+[#5686]: https://github.com/tokio-rs/tokio/pull/5686
+[#5712]: https://github.com/tokio-rs/tokio/pull/5712
+[#5693]: https://github.com/tokio-rs/tokio/pull/5693
+[#5772]: https://github.com/tokio-rs/tokio/pull/5772
+[#5710]: https://github.com/tokio-rs/tokio/pull/5710
+[#5803]: https://github.com/tokio-rs/tokio/pull/5803
+[#5705]: https://github.com/tokio-rs/tokio/pull/5705
+[#5720]: https://github.com/tokio-rs/tokio/pull/5720
+[#5659]: https://github.com/tokio-rs/tokio/pull/5659
+[#5628]: https://github.com/tokio-rs/tokio/pull/5628
+[#5666]: https://github.com/tokio-rs/tokio/pull/5666
+[#5672]: https://github.com/tokio-rs/tokio/pull/5672
+[#5690]: https://github.com/tokio-rs/tokio/pull/5690
+[#5704]: https://github.com/tokio-rs/tokio/pull/5704
+[#5566]: https://github.com/tokio-rs/tokio/pull/5566
+[#5721]: https://github.com/tokio-rs/tokio/pull/5721
+[#5790]: https://github.com/tokio-rs/tokio/pull/5790
+[#5608]: https://github.com/tokio-rs/tokio/pull/5608
+[#5676]: https://github.com/tokio-rs/tokio/pull/5676
+[#5708]: https://github.com/tokio-rs/tokio/pull/5708
+[#5717]: https://github.com/tokio-rs/tokio/pull/5717
+[#5685]: https://github.com/tokio-rs/tokio/pull/5685
+
+# 1.28.2 (May 28, 2023)
+
+Forward ports 1.18.6 changes.
+
+### Fixed
+
+- deps: disable default features for mio ([#5728])
+
+[#5728]: https://github.com/tokio-rs/tokio/pull/5728
+
+# 1.28.1 (May 10th, 2023)
+
+This release fixes a mistake in the build script that makes `AsFd`
+implementations unavailable on Rust 1.63. ([#5677])
+
+[#5677]: https://github.com/tokio-rs/tokio/pull/5677
+
+# 1.28.0 (April 25th, 2023)
+
+### Added
+
+- io: add `AsyncFd::async_io` ([#5542])
+- io: impl BufMut for ReadBuf ([#5590])
+- net: add `recv_buf` for `UdpSocket` and `UnixDatagram` ([#5583])
+- sync: add `OwnedSemaphorePermit::semaphore` ([#5618])
+- sync: add `same_channel` to broadcast channel ([#5607])
+- sync: add `watch::Receiver::wait_for` ([#5611])
+- task: add `JoinSet::spawn_blocking` and `JoinSet::spawn_blocking_on` ([#5612])
+
+### Changed
+
+- deps: update windows-sys to 0.48 ([#5591])
+- io: make `read_to_end` not grow unnecessarily ([#5610])
+- macros: make entrypoints more efficient ([#5621])
+- sync: improve Debug impl for `RwLock` ([#5647])
+- sync: reduce contention in `Notify` ([#5503])
+
+### Fixed
+
+- net: support `get_peer_cred` on AIX ([#5065])
+- sync: avoid deadlocks in `broadcast` with custom wakers ([#5578])
+
+### Documented
+
+- sync: fix typo in `Semaphore::MAX_PERMITS` ([#5645])
+- sync: fix typo in `tokio::sync::watch::Sender` docs ([#5587])
+
+[#5065]: https://github.com/tokio-rs/tokio/pull/5065
+[#5503]: https://github.com/tokio-rs/tokio/pull/5503
+[#5542]: https://github.com/tokio-rs/tokio/pull/5542
+[#5578]: https://github.com/tokio-rs/tokio/pull/5578
+[#5583]: https://github.com/tokio-rs/tokio/pull/5583
+[#5587]: https://github.com/tokio-rs/tokio/pull/5587
+[#5590]: https://github.com/tokio-rs/tokio/pull/5590
+[#5591]: https://github.com/tokio-rs/tokio/pull/5591
+[#5607]: https://github.com/tokio-rs/tokio/pull/5607
+[#5610]: https://github.com/tokio-rs/tokio/pull/5610
+[#5611]: https://github.com/tokio-rs/tokio/pull/5611
+[#5612]: https://github.com/tokio-rs/tokio/pull/5612
+[#5618]: https://github.com/tokio-rs/tokio/pull/5618
+[#5621]: https://github.com/tokio-rs/tokio/pull/5621
+[#5645]: https://github.com/tokio-rs/tokio/pull/5645
+[#5647]: https://github.com/tokio-rs/tokio/pull/5647
+
+# 1.27.0 (March 27th, 2023)
+
+This release bumps the MSRV of Tokio to 1.56. ([#5559])
+
+### Added
+
+- io: add `async_io` helper method to sockets ([#5512])
+- io: add implementations of `AsFd`/`AsHandle`/`AsSocket` ([#5514], [#5540])
+- net: add `UdpSocket::peek_sender()` ([#5520])
+- sync: add `RwLockWriteGuard::{downgrade_map, try_downgrade_map}` ([#5527])
+- task: add `JoinHandle::abort_handle` ([#5543])
+
+### Changed
+
+- io: use `memchr` from `libc` ([#5558])
+- macros: accept path as crate rename in `#[tokio::main]` ([#5557])
+- macros: update to syn 2.0.0 ([#5572])
+- time: don't register for a wakeup when `Interval` returns `Ready` ([#5553])
+
+### Fixed
+
+- fs: fuse std iterator in `ReadDir` ([#5555])
+- tracing: fix `spawn_blocking` location fields ([#5573])
+- time: clean up redundant check in `Wheel::poll()` ([#5574])
+
+### Documented
+
+- macros: define cancellation safety ([#5525])
+- io: add details to docs of `tokio::io::copy[_buf]` ([#5575])
+- io: refer to `ReaderStream` and `StreamReader` in module docs ([#5576])
+
+[#5512]: https://github.com/tokio-rs/tokio/pull/5512
+[#5514]: https://github.com/tokio-rs/tokio/pull/5514
+[#5520]: https://github.com/tokio-rs/tokio/pull/5520
+[#5525]: https://github.com/tokio-rs/tokio/pull/5525
+[#5527]: https://github.com/tokio-rs/tokio/pull/5527
+[#5540]: https://github.com/tokio-rs/tokio/pull/5540
+[#5543]: https://github.com/tokio-rs/tokio/pull/5543
+[#5553]: https://github.com/tokio-rs/tokio/pull/5553
+[#5555]: https://github.com/tokio-rs/tokio/pull/5555
+[#5557]: https://github.com/tokio-rs/tokio/pull/5557
+[#5558]: https://github.com/tokio-rs/tokio/pull/5558
+[#5559]: https://github.com/tokio-rs/tokio/pull/5559
+[#5572]: https://github.com/tokio-rs/tokio/pull/5572
+[#5573]: https://github.com/tokio-rs/tokio/pull/5573
+[#5574]: https://github.com/tokio-rs/tokio/pull/5574
+[#5575]: https://github.com/tokio-rs/tokio/pull/5575
+[#5576]: https://github.com/tokio-rs/tokio/pull/5576
+
+# 1.26.0 (March 1st, 2023)
+
+### Fixed
+
+- macros: fix empty `join!` and `try_join!` ([#5504])
+- sync: don't leak tracing spans in mutex guards ([#5469])
+- sync: drop wakers after unlocking the mutex in Notify ([#5471])
+- sync: drop wakers outside lock in semaphore ([#5475])
+
+### Added
+
+- fs: add `fs::try_exists` ([#4299])
+- net: add types for named unix pipes ([#5351])
+- sync: add `MappedOwnedMutexGuard` ([#5474])
+
+### Changed
+
+- chore: update windows-sys to 0.45 ([#5386])
+- net: use Message Read Mode for named pipes ([#5350])
+- sync: mark lock guards with `#[clippy::has_significant_drop]` ([#5422])
+- sync: reduce contention in watch channel ([#5464])
+- time: remove cache padding in timer entries ([#5468])
+- time: Improve `Instant::now()` perf with test-util ([#5513])
+
+### Internal Changes
+
+- io: use `poll_fn` in `copy_bidirectional` ([#5486])
+- net: refactor named pipe builders to not use bitfields ([#5477])
+- rt: remove Arc from Clock ([#5434])
+- sync: make `notify_waiters` calls atomic ([#5458])
+- time: don't store deadline twice in sleep entries ([#5410])
+
+### Unstable
+
+- metrics: add a new metric for budget exhaustion yields ([#5517])
+
+### Documented
+
+- io: improve AsyncFd example ([#5481])
+- runtime: document the nature of the main future ([#5494])
+- runtime: remove extra period in docs ([#5511])
+- signal: updated Documentation for Signals ([#5459])
+- sync: add doc aliases for `blocking_*` methods ([#5448])
+- sync: fix docs for Send/Sync bounds in broadcast ([#5480])
+- sync: document drop behavior for channels ([#5497])
+- task: clarify what happens to spawned work during runtime shutdown ([#5394])
+- task: clarify `process::Command` docs ([#5413])
+- task: fix wording with 'unsend' ([#5452])
+- time: document immediate completion guarantee for timeouts ([#5509])
+- tokio: document supported platforms ([#5483])
+
+[#4299]: https://github.com/tokio-rs/tokio/pull/4299
+[#5350]: https://github.com/tokio-rs/tokio/pull/5350
+[#5351]: https://github.com/tokio-rs/tokio/pull/5351
+[#5386]: https://github.com/tokio-rs/tokio/pull/5386
+[#5394]: https://github.com/tokio-rs/tokio/pull/5394
+[#5410]: https://github.com/tokio-rs/tokio/pull/5410
+[#5413]: https://github.com/tokio-rs/tokio/pull/5413
+[#5422]: https://github.com/tokio-rs/tokio/pull/5422
+[#5434]: https://github.com/tokio-rs/tokio/pull/5434
+[#5448]: https://github.com/tokio-rs/tokio/pull/5448
+[#5452]: https://github.com/tokio-rs/tokio/pull/5452
+[#5458]: https://github.com/tokio-rs/tokio/pull/5458
+[#5459]: https://github.com/tokio-rs/tokio/pull/5459
+[#5464]: https://github.com/tokio-rs/tokio/pull/5464
+[#5468]: https://github.com/tokio-rs/tokio/pull/5468
+[#5469]: https://github.com/tokio-rs/tokio/pull/5469
+[#5471]: https://github.com/tokio-rs/tokio/pull/5471
+[#5474]: https://github.com/tokio-rs/tokio/pull/5474
+[#5475]: https://github.com/tokio-rs/tokio/pull/5475
+[#5477]: https://github.com/tokio-rs/tokio/pull/5477
+[#5480]: https://github.com/tokio-rs/tokio/pull/5480
+[#5481]: https://github.com/tokio-rs/tokio/pull/5481
+[#5483]: https://github.com/tokio-rs/tokio/pull/5483
+[#5486]: https://github.com/tokio-rs/tokio/pull/5486
+[#5494]: https://github.com/tokio-rs/tokio/pull/5494
+[#5497]: https://github.com/tokio-rs/tokio/pull/5497
+[#5504]: https://github.com/tokio-rs/tokio/pull/5504
+[#5509]: https://github.com/tokio-rs/tokio/pull/5509
+[#5511]: https://github.com/tokio-rs/tokio/pull/5511
+[#5513]: https://github.com/tokio-rs/tokio/pull/5513
+[#5517]: https://github.com/tokio-rs/tokio/pull/5517
+
+# 1.25.1 (May 28, 2023)
+
+Forward ports 1.18.6 changes.
+
+### Fixed
+
+- deps: disable default features for mio ([#5728])
+
+[#5728]: https://github.com/tokio-rs/tokio/pull/5728
+
+# 1.25.0 (January 28, 2023)
+
+### Fixed
+
+- rt: fix runtime metrics reporting ([#5330])
+
+### Added
+
+- sync: add `broadcast::Sender::len` ([#5343])
+
+### Changed
+
+- fs: increase maximum read buffer size to 2MiB ([#5397])
+
+[#5330]: https://github.com/tokio-rs/tokio/pull/5330
+[#5343]: https://github.com/tokio-rs/tokio/pull/5343
+[#5397]: https://github.com/tokio-rs/tokio/pull/5397
+
+# 1.24.2 (January 17, 2023)
+
+Forward ports 1.18.5 changes.
+
+### Fixed
+
+- io: fix unsoundness in `ReadHalf::unsplit` ([#5375])
+
+[#5375]: https://github.com/tokio-rs/tokio/pull/5375
+
+# 1.24.1 (January 6, 2022)
+
+This release fixes a compilation failure on targets without `AtomicU64` when using rustc older than 1.63. ([#5356])
+
+[#5356]: https://github.com/tokio-rs/tokio/pull/5356
+
+# 1.24.0 (January 5, 2022)
+
+### Fixed
+ - rt: improve native `AtomicU64` support detection ([#5284])
+
+### Added
+ - rt: add configuration option for max number of I/O events polled from the OS
+   per tick ([#5186])
+ - rt: add an environment variable for configuring the default number of worker
+   threads per runtime instance ([#4250])
+
+### Changed
+ - sync: reduce MPSC channel stack usage ([#5294])
+ - io: reduce lock contention in I/O operations  ([#5300])
+ - fs: speed up `read_dir()` by chunking operations ([#5309])
+ - rt: use internal `ThreadId` implementation ([#5329])
+ - test: don't auto-advance time when a `spawn_blocking` task is running ([#5115])
+
+[#5186]: https://github.com/tokio-rs/tokio/pull/5186
+[#5294]: https://github.com/tokio-rs/tokio/pull/5294
+[#5284]: https://github.com/tokio-rs/tokio/pull/5284
+[#4250]: https://github.com/tokio-rs/tokio/pull/4250
+[#5300]: https://github.com/tokio-rs/tokio/pull/5300
+[#5329]: https://github.com/tokio-rs/tokio/pull/5329
+[#5115]: https://github.com/tokio-rs/tokio/pull/5115
+[#5309]: https://github.com/tokio-rs/tokio/pull/5309
+
+# 1.23.1 (January 4, 2022)
+
+This release forward ports changes from 1.18.4.
+
+### Fixed
+
+- net: fix Windows named pipe server builder to maintain option when toggling
+  pipe mode ([#5336]).
+
+[#5336]: https://github.com/tokio-rs/tokio/pull/5336
+
+# 1.23.0 (December 5, 2022)
+
+### Fixed
+
+ - net: fix Windows named pipe connect ([#5208])
+ - io: support vectored writes for `ChildStdin` ([#5216])
+ - io: fix `async fn ready()` false positive for OS-specific events ([#5231])
+
+ ### Changed
+ - runtime: `yield_now` defers task until after driver poll ([#5223])
+ - runtime: reduce amount of codegen needed per spawned task ([#5213])
+ - windows: replace `winapi` dependency with `windows-sys` ([#5204])
+
+ [#5208]: https://github.com/tokio-rs/tokio/pull/5208
+ [#5216]: https://github.com/tokio-rs/tokio/pull/5216
+ [#5213]: https://github.com/tokio-rs/tokio/pull/5213
+ [#5204]: https://github.com/tokio-rs/tokio/pull/5204
+ [#5223]: https://github.com/tokio-rs/tokio/pull/5223
+ [#5231]: https://github.com/tokio-rs/tokio/pull/5231
+
+# 1.22.0 (November 17, 2022)
+
+### Added
+ - runtime: add `Handle::runtime_flavor` ([#5138])
+ - sync: add `Mutex::blocking_lock_owned` ([#5130])
+ - sync: add `Semaphore::MAX_PERMITS` ([#5144])
+ - sync: add `merge()` to semaphore permits ([#4948])
+ - sync: add `mpsc::WeakUnboundedSender` ([#5189])
+
+### Added (unstable)
+
+ - process: add `Command::process_group` ([#5114])
+ - runtime: export metrics about the blocking thread pool ([#5161])
+ - task: add `task::id()` and `task::try_id()` ([#5171])
+
+### Fixed
+ - macros: don't take ownership of futures in macros ([#5087])
+ - runtime: fix Stacked Borrows violation in `LocalOwnedTasks` ([#5099])
+ - runtime: mitigate ABA with 32-bit queue indices when possible ([#5042])
+ - task: wake local tasks to the local queue when woken by the same thread ([#5095])
+ - time: panic in release mode when `mark_pending` called illegally ([#5093])
+ - runtime: fix typo in expect message ([#5169])
+ - runtime: fix `unsync_load` on atomic types ([#5175])
+ - task: elaborate safety comments in task deallocation ([#5172])
+ - runtime: fix `LocalSet` drop in thread local ([#5179])
+ - net: remove libc type leakage in a public API ([#5191])
+ - runtime: update the alignment of `CachePadded` ([#5106])
+
+### Changed
+ - io: make `tokio::io::copy` continue filling the buffer when writer stalls ([#5066])
+ - runtime: remove `coop::budget` from `LocalSet::run_until` ([#5155])
+ - sync: make `Notify` panic safe ([#5154])
+
+### Documented
+ - io: fix doc for `write_i8` to use signed integers ([#5040])
+ - net: fix doc typos for TCP and UDP `set_tos` methods ([#5073])
+ - net: fix function name in `UdpSocket::recv` documentation ([#5150])
+ - sync: typo in `TryLockError` for `RwLock::try_write` ([#5160])
+ - task: document that spawned tasks execute immediately ([#5117])
+ - time: document return type of `timeout` ([#5118])
+ - time: document that `timeout` checks only before poll ([#5126])
+ - sync: specify return type of `oneshot::Receiver` in docs ([#5198])
+
+### Internal changes
+ - runtime: use const `Mutex::new` for globals ([#5061])
+ - runtime: remove `Option` around `mio::Events` in io driver ([#5078])
+ - runtime: remove a conditional compilation clause ([#5104])
+ - runtime: remove a reference to internal time handle ([#5107])
+ - runtime: misc time driver cleanup ([#5120])
+ - runtime: move signal driver to runtime module ([#5121])
+ - runtime: signal driver now uses I/O driver directly ([#5125])
+ - runtime: start decoupling I/O driver and I/O handle ([#5127])
+ - runtime: switch `io::handle` refs with scheduler:Handle ([#5128])
+ - runtime: remove Arc from I/O driver ([#5134])
+ - runtime: use signal driver handle via `scheduler::Handle` ([#5135])
+ - runtime: move internal clock fns out of context ([#5139])
+ - runtime: remove `runtime::context` module ([#5140])
+ - runtime: keep driver cfgs in `driver.rs` ([#5141])
+ - runtime: add `runtime::context` to unify thread-locals ([#5143])
+ - runtime: rename some confusing internal variables/fns ([#5151])
+ - runtime: move `coop` mod into `runtime` ([#5152])
+ - runtime: move budget state to context thread-local ([#5157])
+ - runtime: move park logic into runtime module ([#5158])
+ - runtime: move `Runtime` into its own file ([#5159])
+ - runtime: unify entering a runtime with `Handle::enter` ([#5163])
+ - runtime: remove handle reference from each scheduler ([#5166])
+ - runtime: move `enter` into `context` ([#5167])
+ - runtime: combine context and entered thread-locals ([#5168])
+ - runtime: fix accidental unsetting of current handle ([#5178])
+ - runtime: move `CoreStage` methods to `Core` ([#5182])
+ - sync: name mpsc semaphore types ([#5146])
+
+[#4948]: https://github.com/tokio-rs/tokio/pull/4948
+[#5040]: https://github.com/tokio-rs/tokio/pull/5040
+[#5042]: https://github.com/tokio-rs/tokio/pull/5042
+[#5061]: https://github.com/tokio-rs/tokio/pull/5061
+[#5066]: https://github.com/tokio-rs/tokio/pull/5066
+[#5073]: https://github.com/tokio-rs/tokio/pull/5073
+[#5078]: https://github.com/tokio-rs/tokio/pull/5078
+[#5087]: https://github.com/tokio-rs/tokio/pull/5087
+[#5093]: https://github.com/tokio-rs/tokio/pull/5093
+[#5095]: https://github.com/tokio-rs/tokio/pull/5095
+[#5099]: https://github.com/tokio-rs/tokio/pull/5099
+[#5104]: https://github.com/tokio-rs/tokio/pull/5104
+[#5106]: https://github.com/tokio-rs/tokio/pull/5106
+[#5107]: https://github.com/tokio-rs/tokio/pull/5107
+[#5114]: https://github.com/tokio-rs/tokio/pull/5114
+[#5117]: https://github.com/tokio-rs/tokio/pull/5117
+[#5118]: https://github.com/tokio-rs/tokio/pull/5118
+[#5120]: https://github.com/tokio-rs/tokio/pull/5120
+[#5121]: https://github.com/tokio-rs/tokio/pull/5121
+[#5125]: https://github.com/tokio-rs/tokio/pull/5125
+[#5126]: https://github.com/tokio-rs/tokio/pull/5126
+[#5127]: https://github.com/tokio-rs/tokio/pull/5127
+[#5128]: https://github.com/tokio-rs/tokio/pull/5128
+[#5130]: https://github.com/tokio-rs/tokio/pull/5130
+[#5134]: https://github.com/tokio-rs/tokio/pull/5134
+[#5135]: https://github.com/tokio-rs/tokio/pull/5135
+[#5138]: https://github.com/tokio-rs/tokio/pull/5138
+[#5138]: https://github.com/tokio-rs/tokio/pull/5138
+[#5139]: https://github.com/tokio-rs/tokio/pull/5139
+[#5140]: https://github.com/tokio-rs/tokio/pull/5140
+[#5141]: https://github.com/tokio-rs/tokio/pull/5141
+[#5143]: https://github.com/tokio-rs/tokio/pull/5143
+[#5144]: https://github.com/tokio-rs/tokio/pull/5144
+[#5144]: https://github.com/tokio-rs/tokio/pull/5144
+[#5146]: https://github.com/tokio-rs/tokio/pull/5146
+[#5150]: https://github.com/tokio-rs/tokio/pull/5150
+[#5151]: https://github.com/tokio-rs/tokio/pull/5151
+[#5152]: https://github.com/tokio-rs/tokio/pull/5152
+[#5154]: https://github.com/tokio-rs/tokio/pull/5154
+[#5155]: https://github.com/tokio-rs/tokio/pull/5155
+[#5157]: https://github.com/tokio-rs/tokio/pull/5157
+[#5158]: https://github.com/tokio-rs/tokio/pull/5158
+[#5159]: https://github.com/tokio-rs/tokio/pull/5159
+[#5160]: https://github.com/tokio-rs/tokio/pull/5160
+[#5161]: https://github.com/tokio-rs/tokio/pull/5161
+[#5163]: https://github.com/tokio-rs/tokio/pull/5163
+[#5166]: https://github.com/tokio-rs/tokio/pull/5166
+[#5167]: https://github.com/tokio-rs/tokio/pull/5167
+[#5168]: https://github.com/tokio-rs/tokio/pull/5168
+[#5169]: https://github.com/tokio-rs/tokio/pull/5169
+[#5171]: https://github.com/tokio-rs/tokio/pull/5171
+[#5172]: https://github.com/tokio-rs/tokio/pull/5172
+[#5175]: https://github.com/tokio-rs/tokio/pull/5175
+[#5178]: https://github.com/tokio-rs/tokio/pull/5178
+[#5179]: https://github.com/tokio-rs/tokio/pull/5179
+[#5182]: https://github.com/tokio-rs/tokio/pull/5182
+[#5189]: https://github.com/tokio-rs/tokio/pull/5189
+[#5191]: https://github.com/tokio-rs/tokio/pull/5191
+[#5198]: https://github.com/tokio-rs/tokio/pull/5198
+
+# 1.21.2 (September 27, 2022)
+
+This release removes the dependency on the `once_cell` crate to restore the MSRV
+of 1.21.x, which is the latest minor version at the time of release. ([#5048])
+
+[#5048]: https://github.com/tokio-rs/tokio/pull/5048
+
+# 1.21.1 (September 13, 2022)
+
+### Fixed
+
+- net: fix dependency resolution for socket2 ([#5000])
+- task: ignore failure to set TLS in `LocalSet` Drop ([#4976])
+
+[#4976]: https://github.com/tokio-rs/tokio/pull/4976
+[#5000]: https://github.com/tokio-rs/tokio/pull/5000
+
+# 1.21.0 (September 2, 2022)
+
+This release is the first release of Tokio to intentionally support WASM. The
+`sync,macros,io-util,rt,time` features are stabilized on WASM. Additionally the
+wasm32-wasi target is given unstable support for the `net` feature.
+
+### Added
+
+- net: add `device` and `bind_device` methods to TCP/UDP sockets ([#4882])
+- net: add `tos` and `set_tos` methods to TCP and UDP sockets ([#4877])
+- net: add security flags to named pipe `ServerOptions` ([#4845])
+- signal: add more windows signal handlers ([#4924])
+- sync: add `mpsc::Sender::max_capacity` method ([#4904])
+- sync: implement Weak version of `mpsc::Sender` ([#4595])
+- task: add `LocalSet::enter` ([#4765])
+- task: stabilize `JoinSet` and `AbortHandle` ([#4920])
+- tokio: add `track_caller` to public APIs ([#4805], [#4848], [#4852])
+- wasm: initial support for `wasm32-wasi` target ([#4716])
+
+### Fixed
+
+- miri: improve miri compatibility by avoiding temporary references in `linked_list::Link` impls ([#4841])
+- signal: don't register write interest on signal pipe ([#4898])
+- sync: add `#[must_use]` to lock guards ([#4886])
+- sync: fix hang when calling `recv` on closed and reopened broadcast channel ([#4867])
+- task: propagate attributes on task-locals ([#4837])
+
+### Changed
+
+- fs: change panic to error in `File::start_seek` ([#4897])
+- io: reduce syscalls in `poll_read` ([#4840])
+- process: use blocking threadpool for child stdio I/O ([#4824])
+- signal: make `SignalKind` methods const ([#4956])
+
+### Internal changes
+
+- rt: extract `basic_scheduler::Config` ([#4935])
+- rt: move I/O driver into `runtime` module ([#4942])
+- rt: rename internal scheduler types ([#4945])
+
+### Documented
+
+- chore: fix typos and grammar ([#4858], [#4894], [#4928])
+- io: fix typo in `AsyncSeekExt::rewind` docs ([#4893])
+- net: add documentation to `try_read()` for zero-length buffers ([#4937])
+- runtime: remove incorrect panic section for `Builder::worker_threads` ([#4849])
+- sync: doc of `watch::Sender::send` improved ([#4959])
+- task: add cancel safety docs to `JoinHandle` ([#4901])
+- task: expand on cancellation of `spawn_blocking` ([#4811])
+- time: clarify that the first tick of `Interval::tick` happens immediately ([#4951])
+
+### Unstable
+
+- rt: add unstable option to disable the LIFO slot ([#4936])
+- task: fix incorrect signature in `Builder::spawn_on` ([#4953])
+- task: make `task::Builder::spawn*` methods fallible ([#4823])
+
+[#4595]: https://github.com/tokio-rs/tokio/pull/4595
+[#4716]: https://github.com/tokio-rs/tokio/pull/4716
+[#4765]: https://github.com/tokio-rs/tokio/pull/4765
+[#4805]: https://github.com/tokio-rs/tokio/pull/4805
+[#4811]: https://github.com/tokio-rs/tokio/pull/4811
+[#4823]: https://github.com/tokio-rs/tokio/pull/4823
+[#4824]: https://github.com/tokio-rs/tokio/pull/4824
+[#4837]: https://github.com/tokio-rs/tokio/pull/4837
+[#4840]: https://github.com/tokio-rs/tokio/pull/4840
+[#4841]: https://github.com/tokio-rs/tokio/pull/4841
+[#4845]: https://github.com/tokio-rs/tokio/pull/4845
+[#4848]: https://github.com/tokio-rs/tokio/pull/4848
+[#4849]: https://github.com/tokio-rs/tokio/pull/4849
+[#4852]: https://github.com/tokio-rs/tokio/pull/4852
+[#4858]: https://github.com/tokio-rs/tokio/pull/4858
+[#4867]: https://github.com/tokio-rs/tokio/pull/4867
+[#4877]: https://github.com/tokio-rs/tokio/pull/4877
+[#4882]: https://github.com/tokio-rs/tokio/pull/4882
+[#4886]: https://github.com/tokio-rs/tokio/pull/4886
+[#4893]: https://github.com/tokio-rs/tokio/pull/4893
+[#4894]: https://github.com/tokio-rs/tokio/pull/4894
+[#4897]: https://github.com/tokio-rs/tokio/pull/4897
+[#4898]: https://github.com/tokio-rs/tokio/pull/4898
+[#4901]: https://github.com/tokio-rs/tokio/pull/4901
+[#4904]: https://github.com/tokio-rs/tokio/pull/4904
+[#4920]: https://github.com/tokio-rs/tokio/pull/4920
+[#4924]: https://github.com/tokio-rs/tokio/pull/4924
+[#4928]: https://github.com/tokio-rs/tokio/pull/4928
+[#4935]: https://github.com/tokio-rs/tokio/pull/4935
+[#4936]: https://github.com/tokio-rs/tokio/pull/4936
+[#4937]: https://github.com/tokio-rs/tokio/pull/4937
+[#4942]: https://github.com/tokio-rs/tokio/pull/4942
+[#4945]: https://github.com/tokio-rs/tokio/pull/4945
+[#4951]: https://github.com/tokio-rs/tokio/pull/4951
+[#4953]: https://github.com/tokio-rs/tokio/pull/4953
+[#4956]: https://github.com/tokio-rs/tokio/pull/4956
+[#4959]: https://github.com/tokio-rs/tokio/pull/4959
+
+# 1.20.5 (May 28, 2023)
+
+Forward ports 1.18.6 changes.
+
+### Fixed
+
+- deps: disable default features for mio ([#5728])
+
+[#5728]: https://github.com/tokio-rs/tokio/pull/5728
+
+# 1.20.4 (January 17, 2023)
+
+Forward ports 1.18.5 changes.
+
+### Fixed
+
+- io: fix unsoundness in `ReadHalf::unsplit` ([#5375])
+
+[#5375]: https://github.com/tokio-rs/tokio/pull/5375
+
+# 1.20.3 (January 3, 2022)
+
+This release forward ports changes from 1.18.4.
+
+### Fixed
+
+- net: fix Windows named pipe server builder to maintain option when toggling
+  pipe mode ([#5336]).
+
+[#5336]: https://github.com/tokio-rs/tokio/pull/5336
+
+# 1.20.2 (September 27, 2022)
+
+This release removes the dependency on the `once_cell` crate to restore the MSRV
+of the 1.20.x LTS release. ([#5048])
+
+[#5048]: https://github.com/tokio-rs/tokio/pull/5048
+
+# 1.20.1 (July 25, 2022)
+
+### Fixed
+
+- chore: fix version detection in build script ([#4860])
+
+[#4860]: https://github.com/tokio-rs/tokio/pull/4860
+
+# 1.20.0 (July 12, 2022)
+
+### Added
+- tokio: add `track_caller` to public APIs ([#4772], [#4791], [#4793], [#4806], [#4808])
+- sync: Add `has_changed` method to `watch::Ref` ([#4758])
+
+### Changed
+
+- time: remove `src/time/driver/wheel/stack.rs` ([#4766])
+- rt: clean up arguments passed to basic scheduler ([#4767])
+- net: be more specific about winapi features ([#4764])
+- tokio: use const initialized thread locals where possible ([#4677])
+- task: various small improvements to LocalKey ([#4795])
+
+### Documented
+
+- fs: warn about performance pitfall ([#4762])
+- chore: fix spelling ([#4769])
+- sync: document spurious failures in oneshot ([#4777])
+- sync: add warning for watch in non-Send futures ([#4741])
+- chore: fix typo ([#4798])
+
+### Unstable
+
+- joinset: rename `join_one` to `join_next` ([#4755])
+- rt: unhandled panic config for current thread rt ([#4770])
+
+[#4677]: https://github.com/tokio-rs/tokio/pull/4677
+[#4741]: https://github.com/tokio-rs/tokio/pull/4741
+[#4755]: https://github.com/tokio-rs/tokio/pull/4755
+[#4758]: https://github.com/tokio-rs/tokio/pull/4758
+[#4762]: https://github.com/tokio-rs/tokio/pull/4762
+[#4764]: https://github.com/tokio-rs/tokio/pull/4764
+[#4766]: https://github.com/tokio-rs/tokio/pull/4766
+[#4767]: https://github.com/tokio-rs/tokio/pull/4767
+[#4769]: https://github.com/tokio-rs/tokio/pull/4769
+[#4770]: https://github.com/tokio-rs/tokio/pull/4770
+[#4772]: https://github.com/tokio-rs/tokio/pull/4772
+[#4777]: https://github.com/tokio-rs/tokio/pull/4777
+[#4791]: https://github.com/tokio-rs/tokio/pull/4791
+[#4793]: https://github.com/tokio-rs/tokio/pull/4793
+[#4795]: https://github.com/tokio-rs/tokio/pull/4795
+[#4798]: https://github.com/tokio-rs/tokio/pull/4798
+[#4806]: https://github.com/tokio-rs/tokio/pull/4806
+[#4808]: https://github.com/tokio-rs/tokio/pull/4808
+
+# 1.19.2 (June 6, 2022)
+
+This release fixes another bug in `Notified::enable`. ([#4751])
+
+[#4751]: https://github.com/tokio-rs/tokio/pull/4751
+
+# 1.19.1 (June 5, 2022)
+
+This release fixes a bug in `Notified::enable`. ([#4747])
+
+[#4747]: https://github.com/tokio-rs/tokio/pull/4747
+
+# 1.19.0 (June 3, 2022)
+
+### Added
+
+- runtime: add `is_finished` method for `JoinHandle` and `AbortHandle` ([#4709])
+- runtime: make global queue and event polling intervals configurable ([#4671])
+- sync: add `Notified::enable` ([#4705])
+- sync: add `watch::Sender::send_if_modified` ([#4591])
+- sync: add resubscribe method to broadcast::Receiver ([#4607])
+- net: add `take_error` to `TcpSocket` and `TcpStream` ([#4739])
+
+### Changed
+
+- io: refactor out usage of Weak in the io handle ([#4656])
+
+### Fixed
+
+- macros: avoid starvation in `join!` and `try_join!` ([#4624])
+
+### Documented
+
+- runtime: clarify semantics of tasks outliving `block_on` ([#4729])
+- time: fix example for `MissedTickBehavior::Burst` ([#4713])
+
+### Unstable
+
+- metrics: correctly update atomics in `IoDriverMetrics` ([#4725])
+- metrics: fix compilation with unstable, process, and rt, but without net ([#4682])
+- task: add `#[track_caller]` to `JoinSet`/`JoinMap` ([#4697])
+- task: add `Builder::{spawn_on, spawn_local_on, spawn_blocking_on}` ([#4683])
+- task: add `consume_budget` for cooperative scheduling ([#4498])
+- task: add `join_set::Builder` for configuring `JoinSet` tasks ([#4687])
+- task: update return value of `JoinSet::join_one` ([#4726])
+
+[#4498]: https://github.com/tokio-rs/tokio/pull/4498
+[#4591]: https://github.com/tokio-rs/tokio/pull/4591
+[#4607]: https://github.com/tokio-rs/tokio/pull/4607
+[#4624]: https://github.com/tokio-rs/tokio/pull/4624
+[#4656]: https://github.com/tokio-rs/tokio/pull/4656
+[#4671]: https://github.com/tokio-rs/tokio/pull/4671
+[#4682]: https://github.com/tokio-rs/tokio/pull/4682
+[#4683]: https://github.com/tokio-rs/tokio/pull/4683
+[#4687]: https://github.com/tokio-rs/tokio/pull/4687
+[#4697]: https://github.com/tokio-rs/tokio/pull/4697
+[#4705]: https://github.com/tokio-rs/tokio/pull/4705
+[#4709]: https://github.com/tokio-rs/tokio/pull/4709
+[#4713]: https://github.com/tokio-rs/tokio/pull/4713
+[#4725]: https://github.com/tokio-rs/tokio/pull/4725
+[#4726]: https://github.com/tokio-rs/tokio/pull/4726
+[#4729]: https://github.com/tokio-rs/tokio/pull/4729
+[#4739]: https://github.com/tokio-rs/tokio/pull/4739
+
+# 1.18.6 (May 28, 2023)
+
+### Fixed
+
+- deps: disable default features for mio ([#5728])
+
+[#5728]: https://github.com/tokio-rs/tokio/pull/5728
+
+# 1.18.5 (January 17, 2023)
+
+### Fixed
+
+- io: fix unsoundness in `ReadHalf::unsplit` ([#5375])
+
+[#5375]: https://github.com/tokio-rs/tokio/pull/5375
+
+# 1.18.4 (January 3, 2022)
+
+### Fixed
+
+- net: fix Windows named pipe server builder to maintain option when toggling
+  pipe mode ([#5336]).
+
+[#5336]: https://github.com/tokio-rs/tokio/pull/5336
+
+# 1.18.3 (September 27, 2022)
+
+This release removes the dependency on the `once_cell` crate to restore the MSRV
+of the 1.18.x LTS release. ([#5048])
+
+[#5048]: https://github.com/tokio-rs/tokio/pull/5048
+
+# 1.18.2 (May 5, 2022)
+
+Add missing features for the `winapi` dependency. ([#4663])
+
+[#4663]: https://github.com/tokio-rs/tokio/pull/4663
+
+# 1.18.1 (May 2, 2022)
+
+The 1.18.0 release broke the build for targets without 64-bit atomics when
+building with `tokio_unstable`. This release fixes that. ([#4649])
+
+[#4649]: https://github.com/tokio-rs/tokio/pull/4649
+
+# 1.18.0 (April 27, 2022)
+
+This release adds a number of new APIs in `tokio::net`, `tokio::signal`, and
+`tokio::sync`. In addition, it adds new unstable APIs to `tokio::task` (`Id`s
+for uniquely identifying a task, and `AbortHandle` for remotely cancelling a
+task), as well as a number of bugfixes.
+
+### Fixed
+
+- blocking: add missing `#[track_caller]` for `spawn_blocking` ([#4616])
+- macros: fix `select` macro to process 64 branches ([#4519])
+- net: fix `try_io` methods not calling Mio's `try_io` internally ([#4582])
+- runtime: recover when OS fails to spawn a new thread ([#4485])
+
+### Added
+
+- net: add `UdpSocket::peer_addr` ([#4611])
+- net: add `try_read_buf` method for named pipes ([#4626])
+- signal: add `SignalKind` `Hash`/`Eq` impls and `c_int` conversion ([#4540])
+- signal: add support for signals up to `SIGRTMAX` ([#4555])
+- sync: add `watch::Sender::send_modify` method ([#4310])
+- sync: add `broadcast::Receiver::len` method ([#4542])
+- sync: add `watch::Receiver::same_channel` method ([#4581])
+- sync: implement `Clone` for `RecvError` types ([#4560])
+
+### Changed
+
+- update `mio` to 0.8.1 ([#4582])
+- macros: rename `tokio::select!`'s internal `util` module ([#4543])
+- runtime: use `Vec::with_capacity` when building runtime ([#4553])
+
+### Documented
+
+- improve docs for `tokio_unstable` ([#4524])
+- runtime: include more documentation for thread_pool/worker ([#4511])
+- runtime: update `Handle::current`'s docs to mention `EnterGuard` ([#4567])
+- time: clarify platform specific timer resolution ([#4474])
+- signal: document that `Signal::recv` is cancel-safe ([#4634])
+- sync: `UnboundedReceiver` close docs ([#4548])
+
+### Unstable
+
+The following changes only apply when building with `--cfg tokio_unstable`:
+
+- task: add `task::Id` type ([#4630])
+- task: add `AbortHandle` type for cancelling tasks in a `JoinSet` ([#4530],
+  [#4640])
+- task: fix missing `doc(cfg(...))` attributes for `JoinSet` ([#4531])
+- task: fix broken link in `AbortHandle` RustDoc ([#4545])
+- metrics: add initial IO driver metrics ([#4507])
+
+
+[#4616]: https://github.com/tokio-rs/tokio/pull/4616
+[#4519]: https://github.com/tokio-rs/tokio/pull/4519
+[#4582]: https://github.com/tokio-rs/tokio/pull/4582
+[#4485]: https://github.com/tokio-rs/tokio/pull/4485
+[#4613]: https://github.com/tokio-rs/tokio/pull/4613
+[#4611]: https://github.com/tokio-rs/tokio/pull/4611
+[#4626]: https://github.com/tokio-rs/tokio/pull/4626
+[#4540]: https://github.com/tokio-rs/tokio/pull/4540
+[#4555]: https://github.com/tokio-rs/tokio/pull/4555
+[#4310]: https://github.com/tokio-rs/tokio/pull/4310
+[#4542]: https://github.com/tokio-rs/tokio/pull/4542
+[#4581]: https://github.com/tokio-rs/tokio/pull/4581
+[#4560]: https://github.com/tokio-rs/tokio/pull/4560
+[#4631]: https://github.com/tokio-rs/tokio/pull/4631
+[#4582]: https://github.com/tokio-rs/tokio/pull/4582
+[#4543]: https://github.com/tokio-rs/tokio/pull/4543
+[#4553]: https://github.com/tokio-rs/tokio/pull/4553
+[#4524]: https://github.com/tokio-rs/tokio/pull/4524
+[#4511]: https://github.com/tokio-rs/tokio/pull/4511
+[#4567]: https://github.com/tokio-rs/tokio/pull/4567
+[#4474]: https://github.com/tokio-rs/tokio/pull/4474
+[#4634]: https://github.com/tokio-rs/tokio/pull/4634
+[#4548]: https://github.com/tokio-rs/tokio/pull/4548
+[#4630]: https://github.com/tokio-rs/tokio/pull/4630
+[#4530]: https://github.com/tokio-rs/tokio/pull/4530
+[#4640]: https://github.com/tokio-rs/tokio/pull/4640
+[#4531]: https://github.com/tokio-rs/tokio/pull/4531
+[#4545]: https://github.com/tokio-rs/tokio/pull/4545
+[#4507]: https://github.com/tokio-rs/tokio/pull/4507
+
+# 1.17.0 (February 16, 2022)
+
+This release updates the minimum supported Rust version (MSRV) to 1.49, the
+`mio` dependency to v0.8, and the (optional) `parking_lot` dependency to v0.12.
+Additionally, it contains several bug fixes, as well as internal refactoring and
+performance improvements.
+
+### Fixed
+
+- time: prevent panicking in `sleep` with large durations ([#4495])
+- time: eliminate potential panics in `Instant` arithmetic on platforms where
+  `Instant::now` is not monotonic ([#4461])
+- io: fix `DuplexStream` not participating in cooperative yielding ([#4478])
+- rt: fix potential double panic when dropping a `JoinHandle` ([#4430])
+
+### Changed
+
+- update minimum supported Rust version to 1.49 ([#4457])
+- update `parking_lot` dependency to v0.12.0 ([#4459])
+- update `mio` dependency to v0.8 ([#4449])
+- rt: remove an unnecessary lock in the blocking pool ([#4436])
+- rt: remove an unnecessary enum in the basic scheduler ([#4462])
+- time: use bit manipulation instead of modulo to improve performance ([#4480])
+- net: use `std::future::Ready` instead of our own `Ready` future ([#4271])
+- replace deprecated `atomic::spin_loop_hint` with `hint::spin_loop` ([#4491])
+- fix miri failures in intrusive linked lists ([#4397])
+
+### Documented
+
+- io: add an example for `tokio::process::ChildStdin` ([#4479])
+
+### Unstable
+
+The following changes only apply when building with `--cfg tokio_unstable`:
+
+- task: fix missing location information in `tracing` spans generated by
+  `spawn_local` ([#4483])
+- task: add `JoinSet` for managing sets of tasks ([#4335])
+- metrics: fix compilation error on MIPS ([#4475])
+- metrics: fix compilation error on arm32v7 ([#4453])
+
+[#4495]: https://github.com/tokio-rs/tokio/pull/4495
+[#4461]: https://github.com/tokio-rs/tokio/pull/4461
+[#4478]: https://github.com/tokio-rs/tokio/pull/4478
+[#4430]: https://github.com/tokio-rs/tokio/pull/4430
+[#4457]: https://github.com/tokio-rs/tokio/pull/4457
+[#4459]: https://github.com/tokio-rs/tokio/pull/4459
+[#4449]: https://github.com/tokio-rs/tokio/pull/4449
+[#4462]: https://github.com/tokio-rs/tokio/pull/4462
+[#4436]: https://github.com/tokio-rs/tokio/pull/4436
+[#4480]: https://github.com/tokio-rs/tokio/pull/4480
+[#4271]: https://github.com/tokio-rs/tokio/pull/4271
+[#4491]: https://github.com/tokio-rs/tokio/pull/4491
+[#4397]: https://github.com/tokio-rs/tokio/pull/4397
+[#4479]: https://github.com/tokio-rs/tokio/pull/4479
+[#4483]: https://github.com/tokio-rs/tokio/pull/4483
+[#4335]: https://github.com/tokio-rs/tokio/pull/4335
+[#4475]: https://github.com/tokio-rs/tokio/pull/4475
+[#4453]: https://github.com/tokio-rs/tokio/pull/4453
+
+# 1.16.1 (January 28, 2022)
+
+This release fixes a bug in [#4428] with the change [#4437].
+
+[#4428]: https://github.com/tokio-rs/tokio/pull/4428
+[#4437]: https://github.com/tokio-rs/tokio/pull/4437
+
+# 1.16.0 (January 27, 2022)
+
+Fixes a soundness bug in `io::Take` ([#4428]). The unsoundness is exposed when
+leaking memory in the given `AsyncRead` implementation and then overwriting the
+supplied buffer:
+
+```rust
+impl AsyncRead for Buggy {
+    fn poll_read(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &mut ReadBuf<'_>
+    ) -> Poll<Result<()>> {
+      let new_buf = vec![0; 5].leak();
+      *buf = ReadBuf::new(new_buf);
+      buf.put_slice(b"hello");
+      Poll::Ready(Ok(()))
+    }
+}
+```
+
+Also, this release includes improvements to the multi-threaded scheduler that
+can increase throughput by up to 20% in some cases ([#4383]).
+
+### Fixed
+
+- io: **soundness** don't expose uninitialized memory when using `io::Take` in edge case ([#4428])
+- fs: ensure `File::write` results in a `write` syscall when the runtime shuts down ([#4316])
+- process: drop pipe after child exits in `wait_with_output` ([#4315])
+- rt: improve error message when spawning a thread fails ([#4398])
+- rt: reduce false-positive thread wakups in the multi-threaded scheduler ([#4383])
+- sync: don't inherit `Send` from `parking_lot::*Guard` ([#4359])
+
+### Added
+
+- net: `TcpSocket::linger()` and `set_linger()` ([#4324])
+- net: impl `UnwindSafe` for socket types ([#4384])
+- rt: impl `UnwindSafe` for `JoinHandle` ([#4418])
+- sync: `watch::Receiver::has_changed()` ([#4342])
+- sync: `oneshot::Receiver::blocking_recv()` ([#4334])
+- sync: `RwLock` blocking operations ([#4425])
+
+### Unstable
+
+The following changes only apply when building with `--cfg tokio_unstable`
+
+- rt: **breaking change** overhaul runtime metrics API ([#4373])
+
+[#4428]: https://github.com/tokio-rs/tokio/pull/4428
+[#4316]: https://github.com/tokio-rs/tokio/pull/4316
+[#4315]: https://github.com/tokio-rs/tokio/pull/4315
+[#4398]: https://github.com/tokio-rs/tokio/pull/4398
+[#4383]: https://github.com/tokio-rs/tokio/pull/4383
+[#4359]: https://github.com/tokio-rs/tokio/pull/4359
+[#4324]: https://github.com/tokio-rs/tokio/pull/4324
+[#4384]: https://github.com/tokio-rs/tokio/pull/4384
+[#4418]: https://github.com/tokio-rs/tokio/pull/4418
+[#4342]: https://github.com/tokio-rs/tokio/pull/4342
+[#4334]: https://github.com/tokio-rs/tokio/pull/4334
+[#4425]: https://github.com/tokio-rs/tokio/pull/4425
+[#4373]: https://github.com/tokio-rs/tokio/pull/4373
+
+# 1.15.0 (December 15, 2021)
+
+### Fixed
+
+- io: add cooperative yielding support to `io::empty()` ([#4300])
+- time: make timeout robust against budget-depleting tasks ([#4314])
+
+### Changed
+
+- update minimum supported Rust version to 1.46.
+
+### Added
+
+- time: add `Interval::reset()` ([#4248])
+- io: add explicit lifetimes to `AsyncFdReadyGuard` ([#4267])
+- process: add `Command::as_std()` ([#4295])
+
+### Added (unstable)
+
+- tracing: instrument `tokio::sync` types ([#4302])
+
+[#4302]: https://github.com/tokio-rs/tokio/pull/4302
+[#4300]: https://github.com/tokio-rs/tokio/pull/4300
+[#4295]: https://github.com/tokio-rs/tokio/pull/4295
+[#4267]: https://github.com/tokio-rs/tokio/pull/4267
+[#4248]: https://github.com/tokio-rs/tokio/pull/4248
+[#4314]: https://github.com/tokio-rs/tokio/pull/4314
+
+# 1.14.0 (November 15, 2021)
+
+### Fixed
+
+- macros: fix compiler errors when using `mut` patterns in `select!` ([#4211])
+- sync: fix a data race between `oneshot::Sender::send` and awaiting a
+  `oneshot::Receiver` when the oneshot has been closed ([#4226])
+- sync: make `AtomicWaker` panic safe ([#3689])
+- runtime: fix basic scheduler dropping tasks outside a runtime context
+  ([#4213])
+
+### Added
+
+- stats: add `RuntimeStats::busy_duration_total` ([#4179], [#4223])
+
+### Changed
+
+- io: updated `copy` buffer size to match `std::io::copy` ([#4209])
+
+### Documented
+
+-  io: rename buffer to file in doc-test ([#4230])
+-  sync: fix Notify example ([#4212])
+
+[#4211]: https://github.com/tokio-rs/tokio/pull/4211
+[#4226]: https://github.com/tokio-rs/tokio/pull/4226
+[#3689]: https://github.com/tokio-rs/tokio/pull/3689
+[#4213]: https://github.com/tokio-rs/tokio/pull/4213
+[#4179]: https://github.com/tokio-rs/tokio/pull/4179
+[#4223]: https://github.com/tokio-rs/tokio/pull/4223
+[#4209]: https://github.com/tokio-rs/tokio/pull/4209
+[#4230]: https://github.com/tokio-rs/tokio/pull/4230
+[#4212]: https://github.com/tokio-rs/tokio/pull/4212
+
+# 1.13.1 (November 15, 2021)
 
 ### Fixed
 
@@ -9,6 +1096,217 @@ This release backports a bug fix from 1.13.1.
 
 [#4226]: https://github.com/tokio-rs/tokio/pull/4226
 
+# 1.13.0 (October 29, 2021)
+
+### Fixed
+
+- sync: fix `Notify` to clone the waker before locking its waiter list ([#4129])
+- tokio: add riscv32 to non atomic64 architectures ([#4185])
+
+### Added
+
+- net: add `poll_{recv,send}_ready` methods to `udp` and `uds_datagram` ([#4131])
+- net: add `try_*`, `readable`, `writable`, `ready`, and `peer_addr` methods to split halves ([#4120])
+- sync: add `blocking_lock` to `Mutex` ([#4130])
+- sync: add `watch::Sender::send_replace` ([#3962], [#4195])
+- sync: expand `Debug` for `Mutex<T>` impl to unsized `T` ([#4134])
+- tracing: instrument time::Sleep ([#4072])
+- tracing: use structured location fields for spawned tasks ([#4128])
+
+### Changed
+
+- io: add assert in `copy_bidirectional` that `poll_write` is sensible ([#4125])
+- macros: use qualified syntax when polling in `select!` ([#4192])
+- runtime: handle `block_on` wakeups better ([#4157])
+- task: allocate callback on heap immediately in debug mode ([#4203])
+- tokio: assert platform-minimum requirements at build time ([#3797])
+
+### Documented
+
+- docs: conversion of doc comments to indicative mood ([#4174])
+- docs: add returning on the first error example for `try_join!` ([#4133])
+- docs: fixing broken links in `tokio/src/lib.rs` ([#4132])
+- signal: add example with background listener ([#4171])
+- sync: add more oneshot examples ([#4153])
+- time: document `Interval::tick` cancel safety ([#4152])
+
+[#3797]: https://github.com/tokio-rs/tokio/pull/3797
+[#3962]: https://github.com/tokio-rs/tokio/pull/3962
+[#4072]: https://github.com/tokio-rs/tokio/pull/4072
+[#4120]: https://github.com/tokio-rs/tokio/pull/4120
+[#4125]: https://github.com/tokio-rs/tokio/pull/4125
+[#4128]: https://github.com/tokio-rs/tokio/pull/4128
+[#4129]: https://github.com/tokio-rs/tokio/pull/4129
+[#4130]: https://github.com/tokio-rs/tokio/pull/4130
+[#4131]: https://github.com/tokio-rs/tokio/pull/4131
+[#4132]: https://github.com/tokio-rs/tokio/pull/4132
+[#4133]: https://github.com/tokio-rs/tokio/pull/4133
+[#4134]: https://github.com/tokio-rs/tokio/pull/4134
+[#4152]: https://github.com/tokio-rs/tokio/pull/4152
+[#4153]: https://github.com/tokio-rs/tokio/pull/4153
+[#4157]: https://github.com/tokio-rs/tokio/pull/4157
+[#4171]: https://github.com/tokio-rs/tokio/pull/4171
+[#4174]: https://github.com/tokio-rs/tokio/pull/4174
+[#4185]: https://github.com/tokio-rs/tokio/pull/4185
+[#4192]: https://github.com/tokio-rs/tokio/pull/4192
+[#4195]: https://github.com/tokio-rs/tokio/pull/4195
+[#4203]: https://github.com/tokio-rs/tokio/pull/4203
+
+# 1.12.0 (September 21, 2021)
+
+### Fixed
+
+- mpsc: ensure `try_reserve` error is consistent with `try_send` ([#4119])
+- mpsc: use `spin_loop_hint` instead of `yield_now` ([#4115])
+- sync: make `SendError` field public ([#4097])
+
+### Added
+
+- io: add POSIX AIO on FreeBSD ([#4054])
+- io: add convenience method `AsyncSeekExt::rewind` ([#4107])
+- runtime: add tracing span for `block_on` futures ([#4094])
+- runtime: callback when a worker parks and unparks ([#4070])
+- sync: implement `try_recv` for mpsc channels ([#4113])
+
+### Documented
+
+- docs: clarify CPU-bound tasks on Tokio ([#4105])
+- mpsc: document spurious failures on `poll_recv` ([#4117])
+- mpsc: document that `PollSender` impls `Sink` ([#4110])
+- task: document non-guarantees of `yield_now` ([#4091])
+- time: document paused time details better ([#4061], [#4103])
+
+[#4027]: https://github.com/tokio-rs/tokio/pull/4027
+[#4054]: https://github.com/tokio-rs/tokio/pull/4054
+[#4061]: https://github.com/tokio-rs/tokio/pull/4061
+[#4070]: https://github.com/tokio-rs/tokio/pull/4070
+[#4091]: https://github.com/tokio-rs/tokio/pull/4091
+[#4094]: https://github.com/tokio-rs/tokio/pull/4094
+[#4097]: https://github.com/tokio-rs/tokio/pull/4097
+[#4103]: https://github.com/tokio-rs/tokio/pull/4103
+[#4105]: https://github.com/tokio-rs/tokio/pull/4105
+[#4107]: https://github.com/tokio-rs/tokio/pull/4107
+[#4110]: https://github.com/tokio-rs/tokio/pull/4110
+[#4113]: https://github.com/tokio-rs/tokio/pull/4113
+[#4115]: https://github.com/tokio-rs/tokio/pull/4115
+[#4117]: https://github.com/tokio-rs/tokio/pull/4117
+[#4119]: https://github.com/tokio-rs/tokio/pull/4119
+
+# 1.11.0 (August 31, 2021)
+
+### Fixed
+
+ - time: don't panic when Instant is not monotonic ([#4044])
+ - io: fix panic in `fill_buf` by not calling `poll_fill_buf` twice ([#4084])
+
+### Added
+
+ - watch: add `watch::Sender::subscribe` ([#3800])
+ - process: add `from_std` to `ChildStd*` ([#4045])
+ - stats: initial work on runtime stats ([#4043])
+
+### Changed
+
+ - tracing: change span naming to new console convention ([#4042])
+ - io: speed-up waking by using uninitialized array ([#4055], [#4071], [#4075])
+
+### Documented
+
+ - time: make Sleep examples easier to find ([#4040])
+
+[#3800]: https://github.com/tokio-rs/tokio/pull/3800
+[#4040]: https://github.com/tokio-rs/tokio/pull/4040
+[#4042]: https://github.com/tokio-rs/tokio/pull/4042
+[#4043]: https://github.com/tokio-rs/tokio/pull/4043
+[#4044]: https://github.com/tokio-rs/tokio/pull/4044
+[#4045]: https://github.com/tokio-rs/tokio/pull/4045
+[#4055]: https://github.com/tokio-rs/tokio/pull/4055
+[#4071]: https://github.com/tokio-rs/tokio/pull/4071
+[#4075]: https://github.com/tokio-rs/tokio/pull/4075
+[#4084]: https://github.com/tokio-rs/tokio/pull/4084
+
+# 1.10.1 (August 24, 2021)
+
+### Fixed
+
+ - runtime: fix leak in UnownedTask ([#4063])
+
+[#4063]: https://github.com/tokio-rs/tokio/pull/4063
+
+# 1.10.0 (August 12, 2021)
+
+### Added
+
+ - io: add `(read|write)_f(32|64)[_le]` methods ([#4022])
+ - io: add `fill_buf` and `consume` to `AsyncBufReadExt` ([#3991])
+ - process: add `Child::raw_handle()` on windows ([#3998])
+
+### Fixed
+
+ - doc: fix non-doc builds with `--cfg docsrs` ([#4020])
+ - io: flush eagerly in `io::copy` ([#4001])
+ - runtime: a debug assert was sometimes triggered during shutdown ([#4005])
+ - sync: use `spin_loop_hint` instead of `yield_now` in mpsc ([#4037])
+ - tokio: the test-util feature depends on rt, sync, and time ([#4036])
+
+### Changes
+
+ - runtime: reorganize parts of the runtime ([#3979], [#4005])
+ - signal: make windows docs for signal module show up on unix builds ([#3770])
+ - task: quickly send task to heap on debug mode ([#4009])
+
+### Documented
+
+ - io: document cancellation safety of `AsyncBufReadExt` ([#3997])
+ - sync: document when `watch::send` fails ([#4021])
+
+[#3770]: https://github.com/tokio-rs/tokio/pull/3770
+[#3979]: https://github.com/tokio-rs/tokio/pull/3979
+[#3991]: https://github.com/tokio-rs/tokio/pull/3991
+[#3997]: https://github.com/tokio-rs/tokio/pull/3997
+[#3998]: https://github.com/tokio-rs/tokio/pull/3998
+[#4001]: https://github.com/tokio-rs/tokio/pull/4001
+[#4005]: https://github.com/tokio-rs/tokio/pull/4005
+[#4009]: https://github.com/tokio-rs/tokio/pull/4009
+[#4020]: https://github.com/tokio-rs/tokio/pull/4020
+[#4021]: https://github.com/tokio-rs/tokio/pull/4021
+[#4022]: https://github.com/tokio-rs/tokio/pull/4022
+[#4036]: https://github.com/tokio-rs/tokio/pull/4036
+[#4037]: https://github.com/tokio-rs/tokio/pull/4037
+
+# 1.9.0 (July 22, 2021)
+
+### Added
+
+ - net: allow customized I/O operations for `TcpStream` ([#3888])
+ - sync: add getter for the mutex from a guard ([#3928])
+ - task: expose nameable future for `TaskLocal::scope` ([#3273])
+
+### Fixed
+
+ - Fix leak if output of future panics on drop ([#3967])
+ - Fix leak in `LocalSet` ([#3978])
+
+### Changes
+
+ - runtime: reorganize parts of the runtime ([#3909], [#3939], [#3950], [#3955], [#3980])
+ - sync: clean up `OnceCell` ([#3945])
+ - task: remove mutex in `JoinError` ([#3959])
+
+[#3273]: https://github.com/tokio-rs/tokio/pull/3273
+[#3888]: https://github.com/tokio-rs/tokio/pull/3888
+[#3909]: https://github.com/tokio-rs/tokio/pull/3909
+[#3928]: https://github.com/tokio-rs/tokio/pull/3928
+[#3934]: https://github.com/tokio-rs/tokio/pull/3934
+[#3939]: https://github.com/tokio-rs/tokio/pull/3939
+[#3945]: https://github.com/tokio-rs/tokio/pull/3945
+[#3950]: https://github.com/tokio-rs/tokio/pull/3950
+[#3955]: https://github.com/tokio-rs/tokio/pull/3955
+[#3959]: https://github.com/tokio-rs/tokio/pull/3959
+[#3967]: https://github.com/tokio-rs/tokio/pull/3967
+[#3978]: https://github.com/tokio-rs/tokio/pull/3978
+[#3980]: https://github.com/tokio-rs/tokio/pull/3980
+
 # 1.8.3 (July 26, 2021)
 
 This release backports two fixes from 1.9.0
@@ -676,7 +1974,7 @@ Biggest changes are:
 - Feature flags are simplified
   - `rt-core` and `rt-util` are combined to `rt`
   - `rt-threaded` is renamed to `rt-multi-thread` to match builder API
-  - `tcp`, `udp`, `uds`, `dns` are combied to `net`.
+  - `tcp`, `udp`, `uds`, `dns` are combined to `net`.
   - `parking_lot` is included with `full`
 
 ### Changes
@@ -1174,7 +2472,7 @@ Biggest changes are:
 - `net::lookup_host` maps a `T: ToSocketAddrs` to a stream of `SocketAddrs` ([#1870]).
 - `process::Child` fields are made public to match `std` ([#2014]).
 - impl `Stream` for `sync::broadcast::Receiver` ([#2012]).
-- `sync::RwLock` provides an asynchonous read-write lock ([#1699]).
+- `sync::RwLock` provides an asynchronous read-write lock ([#1699]).
 - `runtime::Handle::current` returns the handle for the current runtime ([#2040]).
 - `StreamExt::filter` filters stream values according to a predicate ([#2001]).
 - `StreamExt::filter_map` simultaneously filter and map stream values ([#2001]).
@@ -1283,7 +2581,7 @@ Biggest changes are:
 ### Fixes
 
 - calling `spawn_blocking` after runtime shutdown ([#1875]).
-- `LocalSet` drop inifinite loop ([#1892]).
+- `LocalSet` drop infinite loop ([#1892]).
 - `LocalSet` hang under load ([#1905]).
 - improved documentation ([#1865], [#1866], [#1868], [#1874], [#1876], [#1911]).
 
diff --git a/vendor/tokio/Cargo.toml b/vendor/tokio/Cargo.toml
index 11ec0c0bd..da1e4d12c 100644
--- a/vendor/tokio/Cargo.toml
+++ b/vendor/tokio/Cargo.toml
@@ -10,54 +10,73 @@
 # See Cargo.toml.orig for the original contents.
 
 [package]
-edition = "2018"
+edition = "2021"
+rust-version = "1.56"
 name = "tokio"
-version = "1.8.4"
+version = "1.29.1"
 authors = ["Tokio Contributors <team@tokio.rs>"]
-description = "An event-driven, non-blocking I/O platform for writing asynchronous I/O\nbacked applications.\n"
+description = """
+An event-driven, non-blocking I/O platform for writing asynchronous I/O
+backed applications.
+"""
 homepage = "https://tokio.rs"
-documentation = "https://docs.rs/tokio/1.8.4/tokio/"
 readme = "README.md"
-keywords = ["io", "async", "non-blocking", "futures"]
-categories = ["asynchronous", "network-programming"]
+keywords = [
+    "io",
+    "async",
+    "non-blocking",
+    "futures",
+]
+categories = [
+    "asynchronous",
+    "network-programming",
+]
 license = "MIT"
 repository = "https://github.com/tokio-rs/tokio"
+
 [package.metadata.docs.rs]
 all-features = true
-rustdoc-args = ["--cfg", "docsrs"]
+rustc-args = [
+    "--cfg",
+    "tokio_unstable",
+]
+rustdoc-args = [
+    "--cfg",
+    "docsrs",
+    "--cfg",
+    "tokio_unstable",
+]
 
 [package.metadata.playground]
-features = ["full", "test-util"]
+features = [
+    "full",
+    "test-util",
+]
+
 [dependencies.bytes]
 version = "1.0.0"
 optional = true
 
-[dependencies.memchr]
-version = "2.2"
-optional = true
-
 [dependencies.mio]
-version = "0.7.6"
+version = "0.8.6"
 optional = true
+default-features = false
 
 [dependencies.num_cpus]
 version = "1.8.0"
 optional = true
 
-[dependencies.once_cell]
-version = "1.5.2"
-optional = true
-
 [dependencies.parking_lot]
-version = "0.11.0"
+version = "0.12.0"
 optional = true
 
 [dependencies.pin-project-lite]
-version = "0.2.0"
+version = "0.2.7"
 
 [dependencies.tokio-macros]
-version = "1.1.0"
+version = "~2.1.0"
 optional = true
+
 [dev-dependencies.async-stream]
 version = "0.3"
 
@@ -66,66 +85,146 @@ version = "0.3.0"
 features = ["async-await"]
 
 [dev-dependencies.mockall]
-version = "0.10.2"
-
-[dev-dependencies.proptest]
-version = "1"
-
-[dev-dependencies.rand]
-version = "0.8.0"
-
-[dev-dependencies.socket2]
-version = "0.4"
-
-[dev-dependencies.tempfile]
-version = "3.1.0"
+version = "0.11.1"
 
 [dev-dependencies.tokio-stream]
 version = "0.1"
 
 [dev-dependencies.tokio-test]
 version = "0.4.0"
+
 [build-dependencies.autocfg]
-version = "1"
+version = "1.1"
 
 [features]
 default = []
 fs = []
-full = ["fs", "io-util", "io-std", "macros", "net", "parking_lot", "process", "rt", "rt-multi-thread", "signal", "sync", "time"]
+full = [
+    "fs",
+    "io-util",
+    "io-std",
+    "macros",
+    "net",
+    "parking_lot",
+    "process",
+    "rt",
+    "rt-multi-thread",
+    "signal",
+    "sync",
+    "time",
+]
 io-std = []
-io-util = ["memchr", "bytes"]
+io-util = ["bytes"]
 macros = ["tokio-macros"]
-net = ["libc", "mio/os-poll", "mio/os-util", "mio/tcp", "mio/udp", "mio/uds", "winapi/namedpipeapi"]
-process = ["bytes", "once_cell", "libc", "mio/os-poll", "mio/os-util", "mio/uds", "signal-hook-registry", "winapi/threadpoollegacyapiset"]
+net = [
+    "libc",
+    "mio/os-poll",
+    "mio/os-ext",
+    "mio/net",
+    "socket2",
+    "windows-sys/Win32_Foundation",
+    "windows-sys/Win32_Security",
+    "windows-sys/Win32_Storage_FileSystem",
+    "windows-sys/Win32_System_Pipes",
+    "windows-sys/Win32_System_SystemServices",
+]
+process = [
+    "bytes",
+    "libc",
+    "mio/os-poll",
+    "mio/os-ext",
+    "mio/net",
+    "signal-hook-registry",
+    "windows-sys/Win32_Foundation",
+    "windows-sys/Win32_System_Threading",
+    "windows-sys/Win32_System_WindowsProgramming",
+]
 rt = []
-rt-multi-thread = ["num_cpus", "rt"]
-signal = ["once_cell", "libc", "mio/os-poll", "mio/uds", "mio/os-util", "signal-hook-registry", "winapi/consoleapi"]
+rt-multi-thread = [
+    "num_cpus",
+    "rt",
+]
+signal = [
+    "libc",
+    "mio/os-poll",
+    "mio/net",
+    "mio/os-ext",
+    "signal-hook-registry",
+    "windows-sys/Win32_Foundation",
+    "windows-sys/Win32_System_Console",
+]
+stats = []
 sync = []
-test-util = []
+test-util = [
+    "rt",
+    "sync",
+    "time",
+]
 time = []
+
+[target."cfg(all(any(target_arch = \"wasm32\", target_arch = \"wasm64\"), not(target_os = \"wasi\")))".dev-dependencies.wasm-bindgen-test]
+version = "0.3.0"
+
 [target."cfg(loom)".dev-dependencies.loom]
-version = "0.5"
-features = ["futures", "checkpoint"]
+version = "0.5.2"
+features = [
+    "futures",
+    "checkpoint",
+]
+
+[target."cfg(not(all(any(target_arch = \"wasm32\", target_arch = \"wasm64\"), target_os = \"unknown\")))".dev-dependencies.rand]
+version = "0.8.0"
+
+[target."cfg(not(any(target_arch = \"wasm32\", target_arch = \"wasm64\")))".dependencies.socket2]
+version = "0.4.9"
+features = ["all"]
+optional = true
+
+[target."cfg(not(any(target_arch = \"wasm32\", target_arch = \"wasm64\")))".dev-dependencies.socket2]
+version = "0.4.9"
+
+[target."cfg(not(any(target_arch = \"wasm32\", target_arch = \"wasm64\")))".dev-dependencies.tempfile]
+version = "3.1.0"
+
+[target."cfg(target_os = \"freebsd\")".dev-dependencies.mio-aio]
+version = "0.7.0"
+features = ["tokio"]
+
+[target."cfg(tokio_taskdump)".dependencies.backtrace]
+version = "0.3.58"
+
 [target."cfg(tokio_unstable)".dependencies.tracing]
-version = "0.1.21"
+version = "0.1.25"
 features = ["std"]
 optional = true
 default-features = false
+
 [target."cfg(unix)".dependencies.libc]
-version = "0.2.42"
+version = "0.2.145"
 optional = true
 
 [target."cfg(unix)".dependencies.signal-hook-registry]
 version = "1.1.1"
 optional = true
+
 [target."cfg(unix)".dev-dependencies.libc]
-version = "0.2.42"
+version = "0.2.145"
 
 [target."cfg(unix)".dev-dependencies.nix]
-version = "0.22.0"
-[target."cfg(windows)".dependencies.winapi]
-version = "0.3.8"
-optional = true
+version = "0.26"
+features = [
+    "fs",
+    "socket",
+]
 default-features = false
-[target."cfg(windows)".dev-dependencies.ntapi]
-version = "0.3.6"
+
+[target."cfg(windows)".dependencies.windows-sys]
+version = "0.48"
+optional = true
+
+[target."cfg(windows)".dev-dependencies.windows-sys]
+version = "0.48"
+features = [
+    "Win32_Foundation",
+    "Win32_Security_Authorization",
+]
diff --git a/vendor/tokio/LICENSE b/vendor/tokio/LICENSE
index ffa38bb61..8bdf6bd60 100644
--- a/vendor/tokio/LICENSE
+++ b/vendor/tokio/LICENSE
@@ -1,4 +1,4 @@
-Copyright (c) 2021 Tokio Contributors
+Copyright (c) 2023 Tokio Contributors
 
 Permission is hereby granted, free of charge, to any
 person obtaining a copy of this software and associated
diff --git a/vendor/tokio/README.md b/vendor/tokio/README.md
index 8ee7bbda1..fb2c149ab 100644
--- a/vendor/tokio/README.md
+++ b/vendor/tokio/README.md
@@ -50,7 +50,15 @@ an asynchronous application.
 
 ## Example
 
-A basic TCP echo server with Tokio:
+A basic TCP echo server with Tokio.
+
+Make sure you activated the full features of the tokio crate on Cargo.toml:
+
+```toml
+[dependencies]
+tokio = { version = "1.29.1", features = ["full"] }
+```
+Then, on your main.rs:
 
 ```rust,no_run
 use tokio::net::TcpListener;
@@ -58,7 +66,7 @@ use tokio::io::{AsyncReadExt, AsyncWriteExt};
 
 #[tokio::main]
 async fn main() -> Result<(), Box<dyn std::error::Error>> {
-    let mut listener = TcpListener::bind("127.0.0.1:8080").await?;
+    let listener = TcpListener::bind("127.0.0.1:8080").await?;
 
     loop {
         let (mut socket, _) = listener.accept().await?;
@@ -132,7 +140,7 @@ several other libraries, including:
 
 * [`tower`]: A library of modular and reusable components for building robust networking clients and servers.
 
-* [`tracing`]: A framework for application-level tracing and async-aware diagnostics.
+* [`tracing`] (formerly `tokio-trace`): A framework for application-level tracing and async-aware diagnostics.
 
 * [`rdbc`]: A Rust database connectivity library for MySQL, Postgres and SQLite.
 
@@ -153,11 +161,74 @@ several other libraries, including:
 [`mio`]: https://github.com/tokio-rs/mio
 [`bytes`]: https://github.com/tokio-rs/bytes
 
+## Changelog
+
+The Tokio repository contains multiple crates. Each crate has its own changelog.
+
+ * `tokio` - [view changelog](https://github.com/tokio-rs/tokio/blob/master/tokio/CHANGELOG.md)
+ * `tokio-util` - [view changelog](https://github.com/tokio-rs/tokio/blob/master/tokio-util/CHANGELOG.md)
+ * `tokio-stream` - [view changelog](https://github.com/tokio-rs/tokio/blob/master/tokio-stream/CHANGELOG.md)
+ * `tokio-macros` - [view changelog](https://github.com/tokio-rs/tokio/blob/master/tokio-macros/CHANGELOG.md)
+ * `tokio-test` - [view changelog](https://github.com/tokio-rs/tokio/blob/master/tokio-test/CHANGELOG.md)
+
 ## Supported Rust Versions
 
-Tokio is built against the latest stable release. The minimum supported version is 1.45.
-The current Tokio version is not guaranteed to build on Rust versions earlier than the
-minimum supported version.
+<!--
+When updating this, also update:
+- .github/workflows/ci.yml
+- CONTRIBUTING.md
+- README.md
+- tokio/README.md
+- tokio/Cargo.toml
+- tokio-util/Cargo.toml
+- tokio-test/Cargo.toml
+- tokio-stream/Cargo.toml
+-->
+
+Tokio will keep a rolling MSRV (minimum supported rust version) policy of **at
+least** 6 months. When increasing the MSRV, the new Rust version must have been
+released at least six months ago. The current MSRV is 1.56.0.
+
+Note that the MSRV is not increased automatically, and only as part of a minor
+release. The MSRV history for past minor releases can be found below:
+
+ * 1.27 to now - Rust 1.56
+ * 1.17 to 1.26 - Rust 1.49
+ * 1.15 to 1.16 - Rust 1.46
+ * 1.0 to 1.14 - Rust 1.45
+
+Note that although we try to avoid the situation where a dependency transitively
+increases the MSRV of Tokio, we do not guarantee that this does not happen.
+However, every minor release will have some set of versions of dependencies that
+works with the MSRV of that minor release.
+
+## Release schedule
+
+Tokio doesn't follow a fixed release schedule, but we typically make one to two
+new minor releases each month. We make patch releases for bugfixes as necessary.
+
+## Bug patching policy
+
+For the purposes of making patch releases with bugfixes, we have designated
+certain minor releases as LTS (long term support) releases. Whenever a bug
+warrants a patch release with a fix for the bug, it will be backported and
+released as a new patch release for each LTS minor version. Our current LTS
+releases are:
+
+ * `1.18.x` - LTS release until June 2023. (MSRV 1.49)
+ * `1.20.x` - LTS release until September 2023. (MSRV 1.49)
+ * `1.25.x` - LTS release until March 2024. (MSRV 1.49)
+
+Each LTS release will continue to receive backported fixes for at least a year.
+If you wish to use a fixed minor release in your project, we recommend that you
+use an LTS release.
+
+To use a fixed minor version, you can specify the version with a tilde. For
+example, to specify that you wish to use the newest `1.18.x` patch release, you
+can use the following dependency specification:
+```text
+tokio = { version = "~1.18", features = [...] }
+```
 
 ## License
 
diff --git a/vendor/tokio/build.rs b/vendor/tokio/build.rs
index fe5c83005..b8234dde9 100644
--- a/vendor/tokio/build.rs
+++ b/vendor/tokio/build.rs
@@ -1,11 +1,128 @@
 use autocfg::AutoCfg;
 
+const CONST_THREAD_LOCAL_PROBE: &str = r#"
+{
+    thread_local! {
+        static MY_PROBE: usize = const { 10 };
+    }
+
+    MY_PROBE.with(|val| *val)
+}
+"#;
+
+const CONST_MUTEX_NEW_PROBE: &str = r#"
+{
+    static MY_MUTEX: ::std::sync::Mutex<i32> = ::std::sync::Mutex::new(1);
+    *MY_MUTEX.lock().unwrap()
+}
+"#;
+
+const AS_FD_PROBE: &str = r#"
+{
+    #[allow(unused_imports)]
+    #[cfg(unix)]
+    use std::os::unix::prelude::AsFd as _;
+    #[allow(unused_imports)]
+    #[cfg(windows)]
+    use std::os::windows::prelude::AsSocket as _;
+    #[allow(unused_imports)]
+    #[cfg(target_os = "wasi")]
+    use std::os::wasi::prelude::AsFd as _;
+}
+"#;
+
+const TARGET_HAS_ATOMIC_PROBE: &str = r#"
+{
+    #[cfg(target_has_atomic = "ptr")]
+    let _ = ();
+}
+"#;
+
+const TARGET_ATOMIC_U64_PROBE: &str = r#"
+{
+    #[allow(unused_imports)]
+    use std::sync::atomic::AtomicU64 as _;
+}
+"#;
+
 fn main() {
+    let mut enable_const_thread_local = false;
+    let mut enable_target_has_atomic = false;
+    let mut enable_const_mutex_new = false;
+    let mut enable_as_fd = false;
+    let mut target_needs_atomic_u64_fallback = false;
+
     match AutoCfg::new() {
         Ok(ac) => {
-            // The #[track_caller] attribute was stabilized in rustc 1.46.0.
-            if ac.probe_rustc_version(1, 46) {
-                autocfg::emit("tokio_track_caller")
+            // These checks prefer to call only `probe_rustc_version` if that is
+            // enough to determine whether the feature is supported. This is
+            // because the `probe_expression` call involves a call to rustc,
+            // which the `probe_rustc_version` call avoids.
+
+            // Const-initialized thread locals were stabilized in 1.59.
+            if ac.probe_rustc_version(1, 60) {
+                enable_const_thread_local = true;
+            } else if ac.probe_rustc_version(1, 59) {
+                // This compiler claims to be 1.59, but there are some nightly
+                // compilers that claim to be 1.59 without supporting the
+                // feature. Explicitly probe to check if code using them
+                // compiles.
+                //
+                // The oldest nightly that supports the feature is 2021-12-06.
+                if ac.probe_expression(CONST_THREAD_LOCAL_PROBE) {
+                    enable_const_thread_local = true;
+                }
+            }
+
+            // The `target_has_atomic` cfg was stabilized in 1.60.
+            if ac.probe_rustc_version(1, 61) {
+                enable_target_has_atomic = true;
+            } else if ac.probe_rustc_version(1, 60) {
+                // This compiler claims to be 1.60, but there are some nightly
+                // compilers that claim to be 1.60 without supporting the
+                // feature. Explicitly probe to check if code using them
+                // compiles.
+                //
+                // The oldest nightly that supports the feature is 2022-02-11.
+                if ac.probe_expression(TARGET_HAS_ATOMIC_PROBE) {
+                    enable_target_has_atomic = true;
+                }
+            }
+
+            // If we can't tell using `target_has_atomic`, tell if the target
+            // has `AtomicU64` by trying to use it.
+            if !enable_target_has_atomic && !ac.probe_expression(TARGET_ATOMIC_U64_PROBE) {
+                target_needs_atomic_u64_fallback = true;
+            }
+
+            // The `Mutex::new` method was made const in 1.63.
+            if ac.probe_rustc_version(1, 64) {
+                enable_const_mutex_new = true;
+            } else if ac.probe_rustc_version(1, 63) {
+                // This compiler claims to be 1.63, but there are some nightly
+                // compilers that claim to be 1.63 without supporting the
+                // feature. Explicitly probe to check if code using them
+                // compiles.
+                //
+                // The oldest nightly that supports the feature is 2022-06-20.
+                if ac.probe_expression(CONST_MUTEX_NEW_PROBE) {
+                    enable_const_mutex_new = true;
+                }
+            }
+
+            // The `AsFd` family of traits were made stable in 1.63.
+            if ac.probe_rustc_version(1, 64) {
+                enable_as_fd = true;
+            } else if ac.probe_rustc_version(1, 63) {
+                // This compiler claims to be 1.63, but there are some nightly
+                // compilers that claim to be 1.63 without supporting the
+                // feature. Explicitly probe to check if code using them
+                // compiles.
+                //
+                // The oldest nightly that supports the feature is 2022-06-16.
+                if ac.probe_expression(AS_FD_PROBE) {
+                    enable_as_fd = true;
+                }
             }
         }
 
@@ -19,4 +136,57 @@ fn main() {
             );
         }
     }
+
+    if !enable_const_thread_local {
+        // To disable this feature on compilers that support it, you can
+        // explicitly pass this flag with the following environment variable:
+        //
+        // RUSTFLAGS="--cfg tokio_no_const_thread_local"
+        autocfg::emit("tokio_no_const_thread_local")
+    }
+
+    if !enable_target_has_atomic {
+        // To disable this feature on compilers that support it, you can
+        // explicitly pass this flag with the following environment variable:
+        //
+        // RUSTFLAGS="--cfg tokio_no_target_has_atomic"
+        autocfg::emit("tokio_no_target_has_atomic")
+    }
+
+    if !enable_const_mutex_new {
+        // To disable this feature on compilers that support it, you can
+        // explicitly pass this flag with the following environment variable:
+        //
+        // RUSTFLAGS="--cfg tokio_no_const_mutex_new"
+        autocfg::emit("tokio_no_const_mutex_new")
+    }
+
+    if !enable_as_fd {
+        // To disable this feature on compilers that support it, you can
+        // explicitly pass this flag with the following environment variable:
+        //
+        // RUSTFLAGS="--cfg tokio_no_as_fd"
+        autocfg::emit("tokio_no_as_fd");
+    }
+
+    if target_needs_atomic_u64_fallback {
+        // To disable this feature on compilers that support it, you can
+        // explicitly pass this flag with the following environment variable:
+        //
+        // RUSTFLAGS="--cfg tokio_no_atomic_u64"
+        autocfg::emit("tokio_no_atomic_u64")
+    }
+
+    let target = ::std::env::var("TARGET").unwrap_or_default();
+
+    // We emit cfgs instead of using `target_family = "wasm"` that requires Rust 1.54.
+    // Note that these cfgs are unavailable in `Cargo.toml`.
+    if target.starts_with("wasm") {
+        autocfg::emit("tokio_wasm");
+        if target.contains("wasi") {
+            autocfg::emit("tokio_wasi");
+        } else {
+            autocfg::emit("tokio_wasm_not_wasi");
+        }
+    }
 }
diff --git a/vendor/tokio/docs/reactor-refactor.md b/vendor/tokio/docs/reactor-refactor.md
index 1c9ace15a..77e64f4df 100644
--- a/vendor/tokio/docs/reactor-refactor.md
+++ b/vendor/tokio/docs/reactor-refactor.md
@@ -188,12 +188,12 @@ readiness, the driver's tick is packed into the atomic `usize`.
 The `ScheduledIo` readiness `AtomicUsize` is structured as:
 
 ```
-| reserved | generation |  driver tick | readinesss |
-|----------+------------+--------------+------------|
-|   1 bit  |   7 bits   +    8 bits    +   16 bits  |
+| shutdown | generation |  driver tick | readiness |
+|----------+------------+--------------+-----------|
+|   1 bit  |   7 bits   +    8 bits    +  16 bits  |
 ```
 
-The `reserved` and `generation` components exist today.
+The `shutdown` and `generation` components exist today.
 
 The `readiness()` function returns a `ReadyEvent` value. This value includes the
 `tick` component read with the resource's readiness value. When
diff --git a/vendor/tokio/external-types.toml b/vendor/tokio/external-types.toml
new file mode 100644
index 000000000..a5bde8ed1
--- /dev/null
+++ b/vendor/tokio/external-types.toml
@@ -0,0 +1,11 @@
+# This config file is for the `cargo-check-external-types` tool that is run in CI.
+
+# The following are types that are allowed to be exposed in Tokio's public API.
+# The standard library is allowed by default.
+allowed_external_types = [
+   "bytes::buf::buf_impl::Buf",
+   "bytes::buf::buf_mut::BufMut",
+
+   "tokio_macros::*",
+]
+
diff --git a/vendor/tokio/src/blocking.rs b/vendor/tokio/src/blocking.rs
index f88b1db11..f172399d5 100644
--- a/vendor/tokio/src/blocking.rs
+++ b/vendor/tokio/src/blocking.rs
@@ -1,5 +1,11 @@
 cfg_rt! {
     pub(crate) use crate::runtime::spawn_blocking;
+
+    cfg_fs! {
+        #[allow(unused_imports)]
+        pub(crate) use crate::runtime::spawn_mandatory_blocking;
+    }
+
     pub(crate) use crate::task::JoinHandle;
 }
 
@@ -16,7 +22,16 @@ cfg_not_rt! {
     {
         assert_send_sync::<JoinHandle<std::cell::Cell<()>>>();
         panic!("requires the `rt` Tokio feature flag")
+    }
 
+    cfg_fs! {
+        pub(crate) fn spawn_mandatory_blocking<F, R>(_f: F) -> Option<JoinHandle<R>>
+        where
+            F: FnOnce() -> R + Send + 'static,
+            R: Send + 'static,
+        {
+            panic!("requires the `rt` Tokio feature flag")
+        }
     }
 
     pub(crate) struct JoinHandle<R> {
diff --git a/vendor/tokio/src/doc/mod.rs b/vendor/tokio/src/doc/mod.rs
index 12c224702..7992fc6bc 100644
--- a/vendor/tokio/src/doc/mod.rs
+++ b/vendor/tokio/src/doc/mod.rs
@@ -17,7 +17,7 @@
 /// will ever accidentally use it.
 ///
 /// [`never` type]: https://doc.rust-lang.org/std/primitive.never.html
+#[derive(Debug)]
 pub enum NotDefinedHere {}
 
 pub mod os;
-pub mod winapi;
diff --git a/vendor/tokio/src/doc/os.rs b/vendor/tokio/src/doc/os.rs
index 0ddf86959..9404d4491 100644
--- a/vendor/tokio/src/doc/os.rs
+++ b/vendor/tokio/src/doc/os.rs
@@ -13,7 +13,7 @@ pub mod windows {
 
         /// See [std::os::windows::io::AsRawHandle](https://doc.rust-lang.org/std/os/windows/io/trait.AsRawHandle.html)
         pub trait AsRawHandle {
-            /// See [std::os::windows::io::FromRawHandle::from_raw_handle](https://doc.rust-lang.org/std/os/windows/io/trait.AsRawHandle.html#tymethod.as_raw_handle)
+            /// See [std::os::windows::io::AsRawHandle::as_raw_handle](https://doc.rust-lang.org/std/os/windows/io/trait.AsRawHandle.html#tymethod.as_raw_handle)
             fn as_raw_handle(&self) -> RawHandle;
         }
 
@@ -22,5 +22,44 @@ pub mod windows {
             /// See [std::os::windows::io::FromRawHandle::from_raw_handle](https://doc.rust-lang.org/std/os/windows/io/trait.FromRawHandle.html#tymethod.from_raw_handle)
             unsafe fn from_raw_handle(handle: RawHandle) -> Self;
         }
+
+        /// See [std::os::windows::io::RawSocket](https://doc.rust-lang.org/std/os/windows/io/type.RawSocket.html)
+        pub type RawSocket = crate::doc::NotDefinedHere;
+
+        /// See [std::os::windows::io::AsRawSocket](https://doc.rust-lang.org/std/os/windows/io/trait.AsRawSocket.html)
+        pub trait AsRawSocket {
+            /// See [std::os::windows::io::AsRawSocket::as_raw_socket](https://doc.rust-lang.org/std/os/windows/io/trait.AsRawSocket.html#tymethod.as_raw_socket)
+            fn as_raw_socket(&self) -> RawSocket;
+        }
+
+        /// See [std::os::windows::io::FromRawSocket](https://doc.rust-lang.org/std/os/windows/io/trait.FromRawSocket.html)
+        pub trait FromRawSocket {
+            /// See [std::os::windows::io::FromRawSocket::from_raw_socket](https://doc.rust-lang.org/std/os/windows/io/trait.FromRawSocket.html#tymethod.from_raw_socket)
+            unsafe fn from_raw_socket(sock: RawSocket) -> Self;
+        }
+
+        /// See [std::os::windows::io::IntoRawSocket](https://doc.rust-lang.org/std/os/windows/io/trait.IntoRawSocket.html)
+        pub trait IntoRawSocket {
+            /// See [std::os::windows::io::IntoRawSocket::into_raw_socket](https://doc.rust-lang.org/std/os/windows/io/trait.IntoRawSocket.html#tymethod.into_raw_socket)
+            fn into_raw_socket(self) -> RawSocket;
+        }
+
+        /// See [std::os::windows::io::BorrowedHandle](https://doc.rust-lang.org/std/os/windows/io/struct.BorrowedHandle.html)
+        pub type BorrowedHandle<'handle> = crate::doc::NotDefinedHere;
+
+        /// See [std::os::windows::io::AsHandle](https://doc.rust-lang.org/std/os/windows/io/trait.AsHandle.html)
+        pub trait AsHandle {
+            /// See [std::os::windows::io::AsHandle::as_handle](https://doc.rust-lang.org/std/os/windows/io/trait.AsHandle.html#tymethod.as_handle)
+            fn as_handle(&self) -> BorrowedHandle<'_>;
+        }
+
+        /// See [std::os::windows::io::BorrowedSocket](https://doc.rust-lang.org/std/os/windows/io/struct.BorrowedSocket.html)
+        pub type BorrowedSocket<'socket> = crate::doc::NotDefinedHere;
+
+        /// See [std::os::windows::io::AsSocket](https://doc.rust-lang.org/std/os/windows/io/trait.AsSocket.html)
+        pub trait AsSocket {
+            /// See [std::os::windows::io::AsSocket::as_socket](https://doc.rust-lang.org/std/os/windows/io/trait.AsSocket.html#tymethod.as_socket)
+            fn as_socket(&self) -> BorrowedSocket<'_>;
+        }
     }
 }
diff --git a/vendor/tokio/src/doc/winapi.rs b/vendor/tokio/src/doc/winapi.rs
deleted file mode 100644
index be68749e0..000000000
--- a/vendor/tokio/src/doc/winapi.rs
+++ /dev/null
@@ -1,66 +0,0 @@
-//! See [winapi].
-//!
-//! [winapi]: https://docs.rs/winapi
-
-/// See [winapi::shared](https://docs.rs/winapi/*/winapi/shared/index.html).
-pub mod shared {
-    /// See [winapi::shared::winerror](https://docs.rs/winapi/*/winapi/shared/winerror/index.html).
-    #[allow(non_camel_case_types)]
-    pub mod winerror {
-        /// See [winapi::shared::winerror::ERROR_ACCESS_DENIED][winapi]
-        ///
-        /// [winapi]: https://docs.rs/winapi/*/winapi/shared/winerror/constant.ERROR_ACCESS_DENIED.html
-        pub type ERROR_ACCESS_DENIED = crate::doc::NotDefinedHere;
-
-        /// See [winapi::shared::winerror::ERROR_PIPE_BUSY][winapi]
-        ///
-        /// [winapi]: https://docs.rs/winapi/*/winapi/shared/winerror/constant.ERROR_PIPE_BUSY.html
-        pub type ERROR_PIPE_BUSY = crate::doc::NotDefinedHere;
-
-        /// See [winapi::shared::winerror::ERROR_MORE_DATA][winapi]
-        ///
-        /// [winapi]: https://docs.rs/winapi/*/winapi/shared/winerror/constant.ERROR_MORE_DATA.html
-        pub type ERROR_MORE_DATA = crate::doc::NotDefinedHere;
-    }
-}
-
-/// See [winapi::um](https://docs.rs/winapi/*/winapi/um/index.html).
-pub mod um {
-    /// See [winapi::um::winbase](https://docs.rs/winapi/*/winapi/um/winbase/index.html).
-    #[allow(non_camel_case_types)]
-    pub mod winbase {
-        /// See [winapi::um::winbase::PIPE_TYPE_MESSAGE][winapi]
-        ///
-        /// [winapi]: https://docs.rs/winapi/*/winapi/um/winbase/constant.PIPE_TYPE_MESSAGE.html
-        pub type PIPE_TYPE_MESSAGE = crate::doc::NotDefinedHere;
-
-        /// See [winapi::um::winbase::PIPE_TYPE_BYTE][winapi]
-        ///
-        /// [winapi]: https://docs.rs/winapi/*/winapi/um/winbase/constant.PIPE_TYPE_BYTE.html
-        pub type PIPE_TYPE_BYTE = crate::doc::NotDefinedHere;
-
-        /// See [winapi::um::winbase::PIPE_CLIENT_END][winapi]
-        ///
-        /// [winapi]: https://docs.rs/winapi/*/winapi/um/winbase/constant.PIPE_CLIENT_END.html
-        pub type PIPE_CLIENT_END = crate::doc::NotDefinedHere;
-
-        /// See [winapi::um::winbase::PIPE_SERVER_END][winapi]
-        ///
-        /// [winapi]: https://docs.rs/winapi/*/winapi/um/winbase/constant.PIPE_SERVER_END.html
-        pub type PIPE_SERVER_END = crate::doc::NotDefinedHere;
-
-        /// See [winapi::um::winbase::SECURITY_IDENTIFICATION][winapi]
-        ///
-        /// [winapi]: https://docs.rs/winapi/*/winapi/um/winbase/constant.SECURITY_IDENTIFICATION.html
-        pub type SECURITY_IDENTIFICATION = crate::doc::NotDefinedHere;
-    }
-
-    /// See [winapi::um::minwinbase](https://docs.rs/winapi/*/winapi/um/minwinbase/index.html).
-    #[allow(non_camel_case_types)]
-    pub mod minwinbase {
-        /// See [winapi::um::minwinbase::SECURITY_ATTRIBUTES][winapi]
-        ///
-        /// [winapi]: https://docs.rs/winapi/*/winapi/um/minwinbase/constant.SECURITY_ATTRIBUTES.html
-        pub type SECURITY_ATTRIBUTES = crate::doc::NotDefinedHere;
-    }
-}
diff --git a/vendor/tokio/src/fs/create_dir.rs b/vendor/tokio/src/fs/create_dir.rs
index e03b04dc4..411969500 100644
--- a/vendor/tokio/src/fs/create_dir.rs
+++ b/vendor/tokio/src/fs/create_dir.rs
@@ -3,7 +3,7 @@ use crate::fs::asyncify;
 use std::io;
 use std::path::Path;
 
-/// Creates a new, empty directory at the provided path
+/// Creates a new, empty directory at the provided path.
 ///
 /// This is an async version of [`std::fs::create_dir`][std]
 ///
diff --git a/vendor/tokio/src/fs/dir_builder.rs b/vendor/tokio/src/fs/dir_builder.rs
index b1849344b..97168bff7 100644
--- a/vendor/tokio/src/fs/dir_builder.rs
+++ b/vendor/tokio/src/fs/dir_builder.rs
@@ -14,7 +14,7 @@ pub struct DirBuilder {
     /// Indicates whether to create parent directories if they are missing.
     recursive: bool,
 
-    /// Set the Unix mode for newly created directories.
+    /// Sets the Unix mode for newly created directories.
     #[cfg(unix)]
     pub(super) mode: Option<u32>,
 }
diff --git a/vendor/tokio/src/fs/file.rs b/vendor/tokio/src/fs/file.rs
index 5286e6c5c..74f91958d 100644
--- a/vendor/tokio/src/fs/file.rs
+++ b/vendor/tokio/src/fs/file.rs
@@ -20,16 +20,16 @@ use std::task::Poll;
 use std::task::Poll::*;
 
 #[cfg(test)]
-use super::mocks::spawn_blocking;
-#[cfg(test)]
 use super::mocks::JoinHandle;
 #[cfg(test)]
 use super::mocks::MockFile as StdFile;
-#[cfg(not(test))]
-use crate::blocking::spawn_blocking;
+#[cfg(test)]
+use super::mocks::{spawn_blocking, spawn_mandatory_blocking};
 #[cfg(not(test))]
 use crate::blocking::JoinHandle;
 #[cfg(not(test))]
+use crate::blocking::{spawn_blocking, spawn_mandatory_blocking};
+#[cfg(not(test))]
 use std::fs::File as StdFile;
 
 /// A reference to an open file on the filesystem.
@@ -74,7 +74,7 @@ use std::fs::File as StdFile;
 /// # }
 /// ```
 ///
-/// Read the contents of a file into a buffer
+/// Read the contents of a file into a buffer:
 ///
 /// ```no_run
 /// use tokio::fs::File;
@@ -383,7 +383,7 @@ impl File {
         asyncify(move || std.metadata()).await
     }
 
-    /// Create a new `File` instance that shares the same underlying file handle
+    /// Creates a new `File` instance that shares the same underlying file handle
     /// as the existing `File` instance. Reads, writes, and seeks will affect both
     /// File instances simultaneously.
     ///
@@ -399,6 +399,7 @@ impl File {
     /// # }
     /// ```
     pub async fn try_clone(&self) -> io::Result<File> {
+        self.inner.lock().await.complete_inflight().await;
         let std = self.std.clone();
         let std_file = asyncify(move || std.try_clone()).await?;
         Ok(File::from_std(std_file))
@@ -498,6 +499,7 @@ impl AsyncRead for File {
         cx: &mut Context<'_>,
         dst: &mut ReadBuf<'_>,
     ) -> Poll<io::Result<()>> {
+        ready!(crate::trace::trace_leaf(cx));
         let me = self.get_mut();
         let inner = me.inner.get_mut();
 
@@ -565,34 +567,36 @@ impl AsyncSeek for File {
         let me = self.get_mut();
         let inner = me.inner.get_mut();
 
-        loop {
-            match inner.state {
-                Busy(_) => panic!("must wait for poll_complete before calling start_seek"),
-                Idle(ref mut buf_cell) => {
-                    let mut buf = buf_cell.take().unwrap();
+        match inner.state {
+            Busy(_) => Err(io::Error::new(
+                io::ErrorKind::Other,
+                "other file operation is pending, call poll_complete before start_seek",
+            )),
+            Idle(ref mut buf_cell) => {
+                let mut buf = buf_cell.take().unwrap();
 
-                    // Factor in any unread data from the buf
-                    if !buf.is_empty() {
-                        let n = buf.discard_read();
+                // Factor in any unread data from the buf
+                if !buf.is_empty() {
+                    let n = buf.discard_read();
 
-                        if let SeekFrom::Current(ref mut offset) = pos {
-                            *offset += n;
-                        }
+                    if let SeekFrom::Current(ref mut offset) = pos {
+                        *offset += n;
                     }
+                }
 
-                    let std = me.std.clone();
+                let std = me.std.clone();
 
-                    inner.state = Busy(spawn_blocking(move || {
-                        let res = (&*std).seek(pos);
-                        (Operation::Seek(res), buf)
-                    }));
-                    return Ok(());
-                }
+                inner.state = Busy(spawn_blocking(move || {
+                    let res = (&*std).seek(pos);
+                    (Operation::Seek(res), buf)
+                }));
+                Ok(())
             }
         }
     }
 
     fn poll_complete(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<u64>> {
+        ready!(crate::trace::trace_leaf(cx));
         let inner = self.inner.get_mut();
 
         loop {
@@ -628,6 +632,7 @@ impl AsyncWrite for File {
         cx: &mut Context<'_>,
         src: &[u8],
     ) -> Poll<io::Result<usize>> {
+        ready!(crate::trace::trace_leaf(cx));
         let me = self.get_mut();
         let inner = me.inner.get_mut();
 
@@ -649,7 +654,7 @@ impl AsyncWrite for File {
                     let n = buf.copy_from(src);
                     let std = me.std.clone();
 
-                    inner.state = Busy(spawn_blocking(move || {
+                    let blocking_task_join_handle = spawn_mandatory_blocking(move || {
                         let res = if let Some(seek) = seek {
                             (&*std).seek(seek).and_then(|_| buf.write_to(&mut &*std))
                         } else {
@@ -657,7 +662,12 @@ impl AsyncWrite for File {
                         };
 
                         (Operation::Write(res), buf)
-                    }));
+                    })
+                    .ok_or_else(|| {
+                        io::Error::new(io::ErrorKind::Other, "background task failed")
+                    })?;
+
+                    inner.state = Busy(blocking_task_join_handle);
 
                     return Ready(Ok(n));
                 }
@@ -689,11 +699,13 @@ impl AsyncWrite for File {
     }
 
     fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), io::Error>> {
+        ready!(crate::trace::trace_leaf(cx));
         let inner = self.inner.get_mut();
         inner.poll_flush(cx)
     }
 
     fn poll_shutdown(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), io::Error>> {
+        ready!(crate::trace::trace_leaf(cx));
         self.poll_flush(cx)
     }
 }
@@ -719,6 +731,15 @@ impl std::os::unix::io::AsRawFd for File {
     }
 }
 
+#[cfg(all(unix, not(tokio_no_as_fd)))]
+impl std::os::unix::io::AsFd for File {
+    fn as_fd(&self) -> std::os::unix::io::BorrowedFd<'_> {
+        unsafe {
+            std::os::unix::io::BorrowedFd::borrow_raw(std::os::unix::io::AsRawFd::as_raw_fd(self))
+        }
+    }
+}
+
 #[cfg(unix)]
 impl std::os::unix::io::FromRawFd for File {
     unsafe fn from_raw_fd(fd: std::os::unix::io::RawFd) -> Self {
@@ -726,17 +747,32 @@ impl std::os::unix::io::FromRawFd for File {
     }
 }
 
-#[cfg(windows)]
-impl std::os::windows::io::AsRawHandle for File {
-    fn as_raw_handle(&self) -> std::os::windows::io::RawHandle {
-        self.std.as_raw_handle()
+cfg_windows! {
+    use crate::os::windows::io::{AsRawHandle, FromRawHandle, RawHandle};
+    #[cfg(not(tokio_no_as_fd))]
+    use crate::os::windows::io::{AsHandle, BorrowedHandle};
+
+    impl AsRawHandle for File {
+        fn as_raw_handle(&self) -> RawHandle {
+            self.std.as_raw_handle()
+        }
     }
-}
 
-#[cfg(windows)]
-impl std::os::windows::io::FromRawHandle for File {
-    unsafe fn from_raw_handle(handle: std::os::windows::io::RawHandle) -> Self {
-        StdFile::from_raw_handle(handle).into()
+    #[cfg(not(tokio_no_as_fd))]
+    impl AsHandle for File {
+        fn as_handle(&self) -> BorrowedHandle<'_> {
+            unsafe {
+                BorrowedHandle::borrow_raw(
+                    AsRawHandle::as_raw_handle(self),
+                )
+            }
+        }
+    }
+
+    impl FromRawHandle for File {
+        unsafe fn from_raw_handle(handle: RawHandle) -> Self {
+            StdFile::from_raw_handle(handle).into()
+        }
     }
 }
 
@@ -744,8 +780,18 @@ impl Inner {
     async fn complete_inflight(&mut self) {
         use crate::future::poll_fn;
 
-        if let Err(e) = poll_fn(|cx| Pin::new(&mut *self).poll_flush(cx)).await {
-            self.last_write_err = Some(e.kind());
+        poll_fn(|cx| self.poll_complete_inflight(cx)).await
+    }
+
+    fn poll_complete_inflight(&mut self, cx: &mut Context<'_>) -> Poll<()> {
+        ready!(crate::trace::trace_leaf(cx));
+        match self.poll_flush(cx) {
+            Poll::Ready(Err(e)) => {
+                self.last_write_err = Some(e.kind());
+                Poll::Ready(())
+            }
+            Poll::Ready(Ok(())) => Poll::Ready(()),
+            Poll::Pending => Poll::Pending,
         }
     }
 
diff --git a/vendor/tokio/src/fs/file/tests.rs b/vendor/tokio/src/fs/file/tests.rs
index 28b5ffe77..7c61b3c4b 100644
--- a/vendor/tokio/src/fs/file/tests.rs
+++ b/vendor/tokio/src/fs/file/tests.rs
@@ -228,14 +228,15 @@ fn flush_while_idle() {
 }
 
 #[test]
+#[cfg_attr(miri, ignore)] // takes a really long time with miri
 fn read_with_buffer_larger_than_max() {
     // Chunks
-    let chunk_a = 16 * 1024;
+    let chunk_a = crate::io::blocking::MAX_BUF;
     let chunk_b = chunk_a * 2;
     let chunk_c = chunk_a * 3;
     let chunk_d = chunk_a * 4;
 
-    assert_eq!(chunk_d / 1024, 64);
+    assert_eq!(chunk_d / 1024 / 1024, 8);
 
     let mut data = vec![];
     for i in 0..(chunk_d - 1) {
@@ -299,14 +300,15 @@ fn read_with_buffer_larger_than_max() {
 }
 
 #[test]
+#[cfg_attr(miri, ignore)] // takes a really long time with miri
 fn write_with_buffer_larger_than_max() {
     // Chunks
-    let chunk_a = 16 * 1024;
+    let chunk_a = crate::io::blocking::MAX_BUF;
     let chunk_b = chunk_a * 2;
     let chunk_c = chunk_a * 3;
     let chunk_d = chunk_a * 4;
 
-    assert_eq!(chunk_d / 1024, 64);
+    assert_eq!(chunk_d / 1024 / 1024, 8);
 
     let mut data = vec![];
     for i in 0..(chunk_d - 1) {
@@ -953,3 +955,24 @@ fn partial_read_set_len_ok() {
     assert_eq!(n, FOO.len());
     assert_eq!(&buf[..n], FOO);
 }
+
+#[test]
+fn busy_file_seek_error() {
+    let mut file = MockFile::default();
+    let mut seq = Sequence::new();
+    file.expect_inner_write()
+        .once()
+        .in_sequence(&mut seq)
+        .returning(|_| Err(io::ErrorKind::Other.into()));
+
+    let mut file = crate::io::BufReader::new(File::from_std(file));
+    {
+        let mut t = task::spawn(file.write(HELLO));
+        assert_ready_ok!(t.poll());
+    }
+
+    pool::run_one();
+
+    let mut t = task::spawn(file.seek(SeekFrom::Start(0)));
+    assert_ready_err!(t.poll());
+}
diff --git a/vendor/tokio/src/fs/mocks.rs b/vendor/tokio/src/fs/mocks.rs
index 68ef4f3a7..aa01e2471 100644
--- a/vendor/tokio/src/fs/mocks.rs
+++ b/vendor/tokio/src/fs/mocks.rs
@@ -81,7 +81,7 @@ impl Write for &'_ MockFile {
     }
 }
 
-thread_local! {
+tokio_thread_local! {
     static QUEUE: RefCell<VecDeque<Box<dyn FnOnce() + Send>>> = RefCell::new(VecDeque::new())
 }
 
@@ -105,6 +105,21 @@ where
     JoinHandle { rx }
 }
 
+pub(super) fn spawn_mandatory_blocking<F, R>(f: F) -> Option<JoinHandle<R>>
+where
+    F: FnOnce() -> R + Send + 'static,
+    R: Send + 'static,
+{
+    let (tx, rx) = oneshot::channel();
+    let task = Box::new(move || {
+        let _ = tx.send(f());
+    });
+
+    QUEUE.with(|cell| cell.borrow_mut().push_back(task));
+
+    Some(JoinHandle { rx })
+}
+
 impl<T> Future for JoinHandle<T> {
     type Output = Result<T, io::Error>;
 
diff --git a/vendor/tokio/src/fs/mod.rs b/vendor/tokio/src/fs/mod.rs
index ca0264b36..f6d9605fe 100644
--- a/vendor/tokio/src/fs/mod.rs
+++ b/vendor/tokio/src/fs/mod.rs
@@ -22,6 +22,24 @@
 //! `std::io::ErrorKind::WouldBlock` if a *worker* thread can not be converted
 //! to a *backup* thread immediately.
 //!
+//! **Warning**: These adapters may create a large number of temporary tasks,
+//! especially when reading large files. When performing a lot of operations
+//! in one batch, it may be significantly faster to use [`spawn_blocking`]
+//! directly:
+//!
+//! ```
+//! use tokio::fs::File;
+//! use std::io::{BufReader, BufRead};
+//! async fn count_lines(file: File) -> Result<usize, std::io::Error> {
+//!     let file = file.into_std().await;
+//!     tokio::task::spawn_blocking(move || {
+//!         let line_count = BufReader::new(file).lines().count();
+//!         Ok(line_count)
+//!     }).await?
+//! }
+//! ```
+//!
+//! [`spawn_blocking`]: fn@crate::task::spawn_blocking
 //! [`AsyncRead`]: trait@crate::io::AsyncRead
 
 mod canonicalize;
@@ -84,6 +102,9 @@ pub use self::write::write;
 mod copy;
 pub use self::copy::copy;
 
+mod try_exists;
+pub use self::try_exists::try_exists;
+
 #[cfg(test)]
 mod mocks;
 
@@ -94,9 +115,7 @@ feature! {
     pub use self::symlink::symlink;
 }
 
-feature! {
-    #![windows]
-
+cfg_windows! {
     mod symlink_dir;
     pub use self::symlink_dir::symlink_dir;
 
diff --git a/vendor/tokio/src/fs/open_options.rs b/vendor/tokio/src/fs/open_options.rs
index 3e73529ec..103510250 100644
--- a/vendor/tokio/src/fs/open_options.rs
+++ b/vendor/tokio/src/fs/open_options.rs
@@ -10,6 +10,11 @@ use mock_open_options::MockOpenOptions as StdOpenOptions;
 #[cfg(not(test))]
 use std::fs::OpenOptions as StdOpenOptions;
 
+#[cfg(unix)]
+use std::os::unix::fs::OpenOptionsExt;
+#[cfg(windows)]
+use std::os::windows::fs::OpenOptionsExt;
+
 /// Options and flags which can be used to configure how a file is opened.
 ///
 /// This builder exposes the ability to configure how a [`File`] is opened and
@@ -399,8 +404,6 @@ impl OpenOptions {
 feature! {
     #![unix]
 
-    use std::os::unix::fs::OpenOptionsExt;
-
     impl OpenOptions {
         /// Sets the mode bits that a new file will be created with.
         ///
@@ -430,7 +433,7 @@ feature! {
             self
         }
 
-        /// Pass custom flags to the `flags` argument of `open`.
+        /// Passes custom flags to the `flags` argument of `open`.
         ///
         /// The bits that define the access mode are masked out with `O_ACCMODE`, to
         /// ensure they do not interfere with the access mode set by Rusts options.
@@ -464,11 +467,7 @@ feature! {
     }
 }
 
-feature! {
-    #![windows]
-
-    use std::os::windows::fs::OpenOptionsExt;
-
+cfg_windows! {
     impl OpenOptions {
         /// Overrides the `dwDesiredAccess` argument to the call to [`CreateFile`]
         /// with the specified value.
@@ -542,7 +541,7 @@ feature! {
         /// # Examples
         ///
         /// ```no_run
-        /// use winapi::um::winbase::FILE_FLAG_DELETE_ON_CLOSE;
+        /// use windows_sys::Win32::Storage::FileSystem::FILE_FLAG_DELETE_ON_CLOSE;
         /// use tokio::fs::OpenOptions;
         ///
         /// # #[tokio::main]
@@ -581,7 +580,7 @@ feature! {
         /// # Examples
         ///
         /// ```no_run
-        /// use winapi::um::winnt::FILE_ATTRIBUTE_HIDDEN;
+        /// use windows_sys::Win32::Storage::FileSystem::FILE_ATTRIBUTE_HIDDEN;
         /// use tokio::fs::OpenOptions;
         ///
         /// # #[tokio::main]
@@ -624,7 +623,7 @@ feature! {
         /// # Examples
         ///
         /// ```no_run
-        /// use winapi::um::winbase::SECURITY_IDENTIFICATION;
+        /// use windows_sys::Win32::Storage::FileSystem::SECURITY_IDENTIFICATION;
         /// use tokio::fs::OpenOptions;
         ///
         /// # #[tokio::main]
diff --git a/vendor/tokio/src/fs/open_options/mock_open_options.rs b/vendor/tokio/src/fs/open_options/mock_open_options.rs
index cbbda0ec2..17b4a4864 100644
--- a/vendor/tokio/src/fs/open_options/mock_open_options.rs
+++ b/vendor/tokio/src/fs/open_options/mock_open_options.rs
@@ -1,3 +1,4 @@
+#![allow(unreachable_pub)]
 //! Mock version of std::fs::OpenOptions;
 use mockall::mock;
 
diff --git a/vendor/tokio/src/fs/read.rs b/vendor/tokio/src/fs/read.rs
index 2d80eb5bd..ada5ba391 100644
--- a/vendor/tokio/src/fs/read.rs
+++ b/vendor/tokio/src/fs/read.rs
@@ -13,8 +13,12 @@ use std::{io, path::Path};
 /// buffer based on the file size when available, so it is generally faster than
 /// reading into a vector created with `Vec::new()`.
 ///
+/// This operation is implemented by running the equivalent blocking operation
+/// on a separate thread pool using [`spawn_blocking`].
+///
 /// [`File::open`]: super::File::open
 /// [`read_to_end`]: crate::io::AsyncReadExt::read_to_end
+/// [`spawn_blocking`]: crate::task::spawn_blocking
 ///
 /// # Errors
 ///
diff --git a/vendor/tokio/src/fs/read_dir.rs b/vendor/tokio/src/fs/read_dir.rs
index c1cb665de..def735b3c 100644
--- a/vendor/tokio/src/fs/read_dir.rs
+++ b/vendor/tokio/src/fs/read_dir.rs
@@ -1,5 +1,6 @@
 use crate::fs::asyncify;
 
+use std::collections::VecDeque;
 use std::ffi::OsString;
 use std::fs::{FileType, Metadata};
 use std::future::Future;
@@ -19,17 +20,29 @@ use crate::blocking::spawn_blocking;
 #[cfg(not(test))]
 use crate::blocking::JoinHandle;
 
+const CHUNK_SIZE: usize = 32;
+
 /// Returns a stream over the entries within a directory.
 ///
 /// This is an async version of [`std::fs::read_dir`](std::fs::read_dir)
+///
+/// This operation is implemented by running the equivalent blocking
+/// operation on a separate thread pool using [`spawn_blocking`].
+///
+/// [`spawn_blocking`]: crate::task::spawn_blocking
 pub async fn read_dir(path: impl AsRef<Path>) -> io::Result<ReadDir> {
     let path = path.as_ref().to_owned();
-    let std = asyncify(|| std::fs::read_dir(path)).await?;
+    asyncify(|| -> io::Result<ReadDir> {
+        let mut std = std::fs::read_dir(path)?;
+        let mut buf = VecDeque::with_capacity(CHUNK_SIZE);
+        let remain = ReadDir::next_chunk(&mut buf, &mut std);
 
-    Ok(ReadDir(State::Idle(Some(std))))
+        Ok(ReadDir(State::Idle(Some((buf, std, remain)))))
+    })
+    .await
 }
 
-/// Read the the entries in a directory.
+/// Reads the entries in a directory.
 ///
 /// This struct is returned from the [`read_dir`] function of this module and
 /// will yield instances of [`DirEntry`]. Through a [`DirEntry`] information
@@ -53,12 +66,16 @@ pub struct ReadDir(State);
 
 #[derive(Debug)]
 enum State {
-    Idle(Option<std::fs::ReadDir>),
-    Pending(JoinHandle<(Option<io::Result<std::fs::DirEntry>>, std::fs::ReadDir)>),
+    Idle(Option<(VecDeque<io::Result<DirEntry>>, std::fs::ReadDir, bool)>),
+    Pending(JoinHandle<(VecDeque<io::Result<DirEntry>>, std::fs::ReadDir, bool)>),
 }
 
 impl ReadDir {
     /// Returns the next entry in the directory stream.
+    ///
+    /// # Cancel safety
+    ///
+    /// This method is cancellation safe.
     pub async fn next_entry(&mut self) -> io::Result<Option<DirEntry>> {
         use crate::future::poll_fn;
         poll_fn(|cx| self.poll_next_entry(cx)).await
@@ -85,28 +102,57 @@ impl ReadDir {
     pub fn poll_next_entry(&mut self, cx: &mut Context<'_>) -> Poll<io::Result<Option<DirEntry>>> {
         loop {
             match self.0 {
-                State::Idle(ref mut std) => {
-                    let mut std = std.take().unwrap();
+                State::Idle(ref mut data) => {
+                    let (buf, _, ref remain) = data.as_mut().unwrap();
+
+                    if let Some(ent) = buf.pop_front() {
+                        return Poll::Ready(ent.map(Some));
+                    } else if !remain {
+                        return Poll::Ready(Ok(None));
+                    }
+
+                    let (mut buf, mut std, _) = data.take().unwrap();
 
                     self.0 = State::Pending(spawn_blocking(move || {
-                        let ret = std.next();
-                        (ret, std)
+                        let remain = ReadDir::next_chunk(&mut buf, &mut std);
+                        (buf, std, remain)
                     }));
                 }
                 State::Pending(ref mut rx) => {
-                    let (ret, std) = ready!(Pin::new(rx).poll(cx))?;
-                    self.0 = State::Idle(Some(std));
+                    self.0 = State::Idle(Some(ready!(Pin::new(rx).poll(cx))?));
+                }
+            }
+        }
+    }
 
-                    let ret = match ret {
-                        Some(Ok(std)) => Ok(Some(DirEntry(Arc::new(std)))),
-                        Some(Err(e)) => Err(e),
-                        None => Ok(None),
-                    };
+    fn next_chunk(buf: &mut VecDeque<io::Result<DirEntry>>, std: &mut std::fs::ReadDir) -> bool {
+        for _ in 0..CHUNK_SIZE {
+            let ret = match std.next() {
+                Some(ret) => ret,
+                None => return false,
+            };
 
-                    return Poll::Ready(ret);
-                }
+            let success = ret.is_ok();
+
+            buf.push_back(ret.map(|std| DirEntry {
+                #[cfg(not(any(
+                    target_os = "solaris",
+                    target_os = "illumos",
+                    target_os = "haiku",
+                    target_os = "vxworks",
+                    target_os = "nto",
+                    target_os = "vita",
+                )))]
+                file_type: std.file_type().ok(),
+                std: Arc::new(std),
+            }));
+
+            if !success {
+                break;
             }
         }
+
+        true
     }
 }
 
@@ -151,7 +197,18 @@ feature! {
 /// filesystem. Each entry can be inspected via methods to learn about the full
 /// path or possibly other metadata through per-platform extension traits.
 #[derive(Debug)]
-pub struct DirEntry(Arc<std::fs::DirEntry>);
+pub struct DirEntry {
+    #[cfg(not(any(
+        target_os = "solaris",
+        target_os = "illumos",
+        target_os = "haiku",
+        target_os = "vxworks",
+        target_os = "nto",
+        target_os = "vita",
+    )))]
+    file_type: Option<FileType>,
+    std: Arc<std::fs::DirEntry>,
+}
 
 impl DirEntry {
     /// Returns the full path to the file that this entry represents.
@@ -184,7 +241,7 @@ impl DirEntry {
     ///
     /// The exact text, of course, depends on what files you have in `.`.
     pub fn path(&self) -> PathBuf {
-        self.0.path()
+        self.std.path()
     }
 
     /// Returns the bare file name of this directory entry without any other
@@ -205,7 +262,7 @@ impl DirEntry {
     /// # }
     /// ```
     pub fn file_name(&self) -> OsString {
-        self.0.file_name()
+        self.std.file_name()
     }
 
     /// Returns the metadata for the file that this entry points at.
@@ -239,7 +296,7 @@ impl DirEntry {
     /// # }
     /// ```
     pub async fn metadata(&self) -> io::Result<Metadata> {
-        let std = self.0.clone();
+        let std = self.std.clone();
         asyncify(move || std.metadata()).await
     }
 
@@ -274,13 +331,25 @@ impl DirEntry {
     /// # }
     /// ```
     pub async fn file_type(&self) -> io::Result<FileType> {
-        let std = self.0.clone();
+        #[cfg(not(any(
+            target_os = "solaris",
+            target_os = "illumos",
+            target_os = "haiku",
+            target_os = "vxworks",
+            target_os = "nto",
+            target_os = "vita",
+        )))]
+        if let Some(file_type) = self.file_type {
+            return Ok(file_type);
+        }
+
+        let std = self.std.clone();
         asyncify(move || std.file_type()).await
     }
 
-    /// Returns a reference to the underlying `std::fs::DirEntry`
+    /// Returns a reference to the underlying `std::fs::DirEntry`.
     #[cfg(unix)]
     pub(super) fn as_inner(&self) -> &std::fs::DirEntry {
-        &self.0
+        &self.std
     }
 }
diff --git a/vendor/tokio/src/fs/read_to_string.rs b/vendor/tokio/src/fs/read_to_string.rs
index 4f37986d6..26228d98c 100644
--- a/vendor/tokio/src/fs/read_to_string.rs
+++ b/vendor/tokio/src/fs/read_to_string.rs
@@ -7,6 +7,10 @@ use std::{io, path::Path};
 ///
 /// This is the async equivalent of [`std::fs::read_to_string`][std].
 ///
+/// This operation is implemented by running the equivalent blocking operation
+/// on a separate thread pool using [`spawn_blocking`].
+///
+/// [`spawn_blocking`]: crate::task::spawn_blocking
 /// [std]: fn@std::fs::read_to_string
 ///
 /// # Examples
diff --git a/vendor/tokio/src/fs/symlink_dir.rs b/vendor/tokio/src/fs/symlink_dir.rs
index 736e762b4..6753c25eb 100644
--- a/vendor/tokio/src/fs/symlink_dir.rs
+++ b/vendor/tokio/src/fs/symlink_dir.rs
@@ -10,7 +10,7 @@ use std::path::Path;
 ///
 /// This is an async version of [`std::os::windows::fs::symlink_dir`][std]
 ///
-/// [std]: std::os::windows::fs::symlink_dir
+/// [std]: https://doc.rust-lang.org/std/os/windows/fs/fn.symlink_dir.html
 pub async fn symlink_dir(src: impl AsRef<Path>, dst: impl AsRef<Path>) -> io::Result<()> {
     let src = src.as_ref().to_owned();
     let dst = dst.as_ref().to_owned();
diff --git a/vendor/tokio/src/fs/symlink_file.rs b/vendor/tokio/src/fs/symlink_file.rs
index 07d8e6041..623352a1b 100644
--- a/vendor/tokio/src/fs/symlink_file.rs
+++ b/vendor/tokio/src/fs/symlink_file.rs
@@ -10,7 +10,7 @@ use std::path::Path;
 ///
 /// This is an async version of [`std::os::windows::fs::symlink_file`][std]
 ///
-/// [std]: std::os::windows::fs::symlink_file
+/// [std]: https://doc.rust-lang.org/std/os/windows/fs/fn.symlink_file.html
 pub async fn symlink_file(src: impl AsRef<Path>, dst: impl AsRef<Path>) -> io::Result<()> {
     let src = src.as_ref().to_owned();
     let dst = dst.as_ref().to_owned();
diff --git a/vendor/tokio/src/fs/try_exists.rs b/vendor/tokio/src/fs/try_exists.rs
new file mode 100644
index 000000000..069518bf9
--- /dev/null
+++ b/vendor/tokio/src/fs/try_exists.rs
@@ -0,0 +1,34 @@
+use crate::fs::asyncify;
+
+use std::io;
+use std::path::Path;
+
+/// Returns `Ok(true)` if the path points at an existing entity.
+///
+/// This function will traverse symbolic links to query information about the
+/// destination file. In case of broken symbolic links this will return `Ok(false)`.
+///
+/// This is the async equivalent of [`std::path::Path::try_exists`][std].
+///
+/// [std]: fn@std::path::Path::try_exists
+///
+/// # Examples
+///
+/// ```no_run
+/// use tokio::fs;
+///
+/// # async fn dox() -> std::io::Result<()> {
+/// fs::try_exists("foo.txt").await?;
+/// # Ok(())
+/// # }
+/// ```
+pub async fn try_exists(path: impl AsRef<Path>) -> io::Result<bool> {
+    let path = path.as_ref().to_owned();
+    // std's Path::try_exists is not available for current Rust min supported version.
+    // Current implementation is based on its internal implementation instead.
+    match asyncify(move || std::fs::metadata(path)).await {
+        Ok(_) => Ok(true),
+        Err(error) if error.kind() == std::io::ErrorKind::NotFound => Ok(false),
+        Err(error) => Err(error),
+    }
+}
diff --git a/vendor/tokio/src/fs/write.rs b/vendor/tokio/src/fs/write.rs
index 0ed908271..28606fb36 100644
--- a/vendor/tokio/src/fs/write.rs
+++ b/vendor/tokio/src/fs/write.rs
@@ -7,6 +7,10 @@ use std::{io, path::Path};
 ///
 /// This is the async equivalent of [`std::fs::write`][std].
 ///
+/// This operation is implemented by running the equivalent blocking operation
+/// on a separate thread pool using [`spawn_blocking`].
+///
+/// [`spawn_blocking`]: crate::task::spawn_blocking
 /// [std]: fn@std::fs::write
 ///
 /// # Examples
diff --git a/vendor/tokio/src/future/block_on.rs b/vendor/tokio/src/future/block_on.rs
index 91f9cc005..2c2ab3736 100644
--- a/vendor/tokio/src/future/block_on.rs
+++ b/vendor/tokio/src/future/block_on.rs
@@ -1,15 +1,22 @@
 use std::future::Future;
 
 cfg_rt! {
+    #[track_caller]
     pub(crate) fn block_on<F: Future>(f: F) -> F::Output {
-        let mut e = crate::runtime::enter::enter(false);
+        let mut e = crate::runtime::context::try_enter_blocking_region().expect(
+            "Cannot block the current thread from within a runtime. This \
+            happens because a function attempted to block the current \
+            thread while the thread is being used to drive asynchronous \
+            tasks."
+        );
         e.block_on(f).unwrap()
     }
 }
 
 cfg_not_rt! {
+    #[track_caller]
     pub(crate) fn block_on<F: Future>(f: F) -> F::Output {
-        let mut park = crate::park::thread::CachedParkThread::new();
+        let mut park = crate::runtime::park::CachedParkThread::new();
         park.block_on(f).unwrap()
     }
 }
diff --git a/vendor/tokio/src/future/maybe_done.rs b/vendor/tokio/src/future/maybe_done.rs
index 1e083ad7f..486efbe01 100644
--- a/vendor/tokio/src/future/maybe_done.rs
+++ b/vendor/tokio/src/future/maybe_done.rs
@@ -1,4 +1,4 @@
-//! Definition of the MaybeDone combinator
+//! Definition of the MaybeDone combinator.
 
 use std::future::Future;
 use std::mem;
@@ -8,9 +8,9 @@ use std::task::{Context, Poll};
 /// A future that may have completed.
 #[derive(Debug)]
 pub enum MaybeDone<Fut: Future> {
-    /// A not-yet-completed future
+    /// A not-yet-completed future.
     Future(Fut),
-    /// The output of the completed future
+    /// The output of the completed future.
     Done(Fut::Output),
     /// The empty variant after the result of a [`MaybeDone`] has been
     /// taken using the [`take_output`](MaybeDone::take_output) method.
@@ -20,7 +20,7 @@ pub enum MaybeDone<Fut: Future> {
 // Safe because we never generate `Pin<&mut Fut::Output>`
 impl<Fut: Future + Unpin> Unpin for MaybeDone<Fut> {}
 
-/// Wraps a future into a `MaybeDone`
+/// Wraps a future into a `MaybeDone`.
 pub fn maybe_done<Fut: Future>(future: Fut) -> MaybeDone<Fut> {
     MaybeDone::Future(future)
 }
diff --git a/vendor/tokio/src/future/mod.rs b/vendor/tokio/src/future/mod.rs
index 96483acd7..084ddc571 100644
--- a/vendor/tokio/src/future/mod.rs
+++ b/vendor/tokio/src/future/mod.rs
@@ -8,11 +8,6 @@ pub(crate) mod maybe_done;
 mod poll_fn;
 pub use poll_fn::poll_fn;
 
-cfg_not_loom! {
-    mod ready;
-    pub(crate) use ready::{ok, Ready};
-}
-
 cfg_process! {
     mod try_join;
     pub(crate) use try_join::try_join3;
diff --git a/vendor/tokio/src/future/poll_fn.rs b/vendor/tokio/src/future/poll_fn.rs
index 0169bd5fc..074d9438e 100644
--- a/vendor/tokio/src/future/poll_fn.rs
+++ b/vendor/tokio/src/future/poll_fn.rs
@@ -1,19 +1,29 @@
 #![allow(dead_code)]
 
-//! Definition of the `PollFn` adapter combinator
+//! Definition of the `PollFn` adapter combinator.
 
 use std::fmt;
 use std::future::Future;
 use std::pin::Pin;
 use std::task::{Context, Poll};
 
+// This struct is intentionally `!Unpin` when `F` is `!Unpin`. This is to
+// mitigate the issue where rust puts noalias on mutable references to the
+// `PollFn` type if it is `Unpin`. If the closure has ownership of a future,
+// then this "leaks" and the future is affected by noalias too, which we don't
+// want.
+//
+// See this thread for more information:
+// <https://internals.rust-lang.org/t/surprising-soundness-trouble-around-pollfn/17484>
+//
+// The fact that `PollFn` is not `Unpin` when it shouldn't be is tested in
+// `tests/async_send_sync.rs`.
+
 /// Future for the [`poll_fn`] function.
 pub struct PollFn<F> {
     f: F,
 }
 
-impl<F> Unpin for PollFn<F> {}
-
 /// Creates a new future wrapping around a function returning [`Poll`].
 pub fn poll_fn<T, F>(f: F) -> PollFn<F>
 where
@@ -34,7 +44,17 @@ where
 {
     type Output = T;
 
-    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<T> {
-        (&mut self.f)(cx)
+    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<T> {
+        // Safety: We never construct a `Pin<&mut F>` anywhere, so accessing `f`
+        // mutably in an unpinned way is sound.
+        //
+        // This use of unsafe cannot be replaced with the pin-project macro
+        // because:
+        //  * If we put `#[pin]` on the field, then it gives us a `Pin<&mut F>`,
+        //    which we can't use to call the closure.
+        //  * If we don't put `#[pin]` on the field, then it makes `PollFn` be
+        //    unconditionally `Unpin`, which we also don't want.
+        let me = unsafe { Pin::into_inner_unchecked(self) };
+        (me.f)(cx)
     }
 }
diff --git a/vendor/tokio/src/future/ready.rs b/vendor/tokio/src/future/ready.rs
deleted file mode 100644
index de2d60c13..000000000
--- a/vendor/tokio/src/future/ready.rs
+++ /dev/null
@@ -1,27 +0,0 @@
-use std::future::Future;
-use std::pin::Pin;
-use std::task::{Context, Poll};
-
-/// Future for the [`ok`](ok()) function.
-///
-/// `pub` in order to use the future as an associated type in a sealed trait.
-#[derive(Debug)]
-// Used as an associated type in a "sealed" trait.
-#[allow(unreachable_pub)]
-pub struct Ready<T>(Option<T>);
-
-impl<T> Unpin for Ready<T> {}
-
-impl<T> Future for Ready<T> {
-    type Output = T;
-
-    #[inline]
-    fn poll(mut self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<T> {
-        Poll::Ready(self.0.take().unwrap())
-    }
-}
-
-/// Creates a future that is immediately ready with a success value.
-pub(crate) fn ok<T, E>(t: T) -> Ready<Result<T, E>> {
-    Ready(Some(Ok(t)))
-}
diff --git a/vendor/tokio/src/fuzz.rs b/vendor/tokio/src/fuzz.rs
new file mode 100644
index 000000000..d89718f0e
--- /dev/null
+++ b/vendor/tokio/src/fuzz.rs
@@ -0,0 +1 @@
+pub use crate::util::linked_list::tests::fuzz_linked_list;
diff --git a/vendor/tokio/src/io/async_fd.rs b/vendor/tokio/src/io/async_fd.rs
index fa5bec530..0cde5a407 100644
--- a/vendor/tokio/src/io/async_fd.rs
+++ b/vendor/tokio/src/io/async_fd.rs
@@ -1,4 +1,6 @@
-use crate::io::driver::{Handle, Interest, ReadyEvent, Registration};
+use crate::io::{Interest, Ready};
+use crate::runtime::io::{ReadyEvent, Registration};
+use crate::runtime::scheduler;
 
 use mio::unix::SourceFd;
 use std::io;
@@ -63,8 +65,8 @@ use std::{task::Context, task::Poll};
 /// # Examples
 ///
 /// This example shows how to turn [`std::net::TcpStream`] asynchronous using
-/// `AsyncFd`.  It implements `read` as an async fn, and `AsyncWrite` as a trait
-/// to show how to implement both approaches.
+/// `AsyncFd`.  It implements the read/write operations both as an `async fn`
+/// and using the IO traits [`AsyncRead`] and [`AsyncWrite`].
 ///
 /// ```no_run
 /// use futures::ready;
@@ -72,7 +74,7 @@ use std::{task::Context, task::Poll};
 /// use std::net::TcpStream;
 /// use std::pin::Pin;
 /// use std::task::{Context, Poll};
-/// use tokio::io::AsyncWrite;
+/// use tokio::io::{AsyncRead, AsyncWrite, ReadBuf};
 /// use tokio::io::unix::AsyncFd;
 ///
 /// pub struct AsyncTcpStream {
@@ -81,6 +83,7 @@ use std::{task::Context, task::Poll};
 ///
 /// impl AsyncTcpStream {
 ///     pub fn new(tcp: TcpStream) -> io::Result<Self> {
+///         tcp.set_nonblocking(true)?;
 ///         Ok(Self {
 ///             inner: AsyncFd::new(tcp)?,
 ///         })
@@ -96,6 +99,39 @@ use std::{task::Context, task::Poll};
 ///             }
 ///         }
 ///     }
+///
+///     pub async fn write(&self, buf: &[u8]) -> io::Result<usize> {
+///         loop {
+///             let mut guard = self.inner.writable().await?;
+///
+///             match guard.try_io(|inner| inner.get_ref().write(buf)) {
+///                 Ok(result) => return result,
+///                 Err(_would_block) => continue,
+///             }
+///         }
+///     }
+/// }
+///
+/// impl AsyncRead for AsyncTcpStream {
+///     fn poll_read(
+///         self: Pin<&mut Self>,
+///         cx: &mut Context<'_>,
+///         buf: &mut ReadBuf<'_>
+///     ) -> Poll<io::Result<()>> {
+///         loop {
+///             let mut guard = ready!(self.inner.poll_read_ready(cx))?;
+///
+///             let unfilled = buf.initialize_unfilled();
+///             match guard.try_io(|inner| inner.get_ref().read(unfilled)) {
+///                 Ok(Ok(len)) => {
+///                     buf.advance(len);
+///                     return Poll::Ready(Ok(()));
+///                 },
+///                 Ok(Err(err)) => return Poll::Ready(Err(err)),
+///                 Err(_would_block) => continue,
+///             }
+///         }
+///     }
 /// }
 ///
 /// impl AsyncWrite for AsyncTcpStream {
@@ -136,6 +172,8 @@ use std::{task::Context, task::Poll};
 /// [`writable`]: method@Self::writable
 /// [`AsyncFdReadyGuard`]: struct@self::AsyncFdReadyGuard
 /// [`TcpStream::poll_read_ready`]: struct@crate::net::TcpStream
+/// [`AsyncRead`]: trait@crate::io::AsyncRead
+/// [`AsyncWrite`]: trait@crate::io::AsyncWrite
 pub struct AsyncFd<T: AsRawFd> {
     registration: Registration,
     inner: Option<T>,
@@ -163,35 +201,50 @@ pub struct AsyncFdReadyMutGuard<'a, T: AsRawFd> {
     event: Option<ReadyEvent>,
 }
 
-const ALL_INTEREST: Interest = Interest::READABLE.add(Interest::WRITABLE);
-
 impl<T: AsRawFd> AsyncFd<T> {
-    #[inline]
     /// Creates an AsyncFd backed by (and taking ownership of) an object
     /// implementing [`AsRawFd`]. The backing file descriptor is cached at the
     /// time of creation.
     ///
+    /// Only configures the [`Interest::READABLE`] and [`Interest::WRITABLE`] interests. For more
+    /// control, use [`AsyncFd::with_interest`].
+    ///
     /// This method must be called in the context of a tokio runtime.
+    ///
+    /// # Panics
+    ///
+    /// This function panics if there is no current reactor set, or if the `rt`
+    /// feature flag is not enabled.
+    #[inline]
+    #[track_caller]
     pub fn new(inner: T) -> io::Result<Self>
     where
         T: AsRawFd,
     {
-        Self::with_interest(inner, ALL_INTEREST)
+        Self::with_interest(inner, Interest::READABLE | Interest::WRITABLE)
     }
 
+    /// Creates an AsyncFd backed by (and taking ownership of) an object
+    /// implementing [`AsRawFd`], with a specific [`Interest`]. The backing
+    /// file descriptor is cached at the time of creation.
+    ///
+    /// # Panics
+    ///
+    /// This function panics if there is no current reactor set, or if the `rt`
+    /// feature flag is not enabled.
     #[inline]
-    /// Creates new instance as `new` with additional ability to customize interest,
-    /// allowing to specify whether file descriptor will be polled for read, write or both.
+    #[track_caller]
     pub fn with_interest(inner: T, interest: Interest) -> io::Result<Self>
     where
         T: AsRawFd,
     {
-        Self::new_with_handle_and_interest(inner, Handle::current(), interest)
+        Self::new_with_handle_and_interest(inner, scheduler::Handle::current(), interest)
     }
 
+    #[track_caller]
     pub(crate) fn new_with_handle_and_interest(
         inner: T,
-        handle: Handle,
+        handle: scheduler::Handle,
         interest: Interest,
     ) -> io::Result<Self> {
         let fd = inner.as_raw_fd();
@@ -205,13 +258,13 @@ impl<T: AsRawFd> AsyncFd<T> {
         })
     }
 
-    /// Returns a shared reference to the backing object of this [`AsyncFd`]
+    /// Returns a shared reference to the backing object of this [`AsyncFd`].
     #[inline]
     pub fn get_ref(&self) -> &T {
         self.inner.as_ref().unwrap()
     }
 
-    /// Returns a mutable reference to the backing object of this [`AsyncFd`]
+    /// Returns a mutable reference to the backing object of this [`AsyncFd`].
     #[inline]
     pub fn get_mut(&mut self) -> &mut T {
         self.inner.as_mut().unwrap()
@@ -389,7 +442,96 @@ impl<T: AsRawFd> AsyncFd<T> {
         .into()
     }
 
-    async fn readiness(&self, interest: Interest) -> io::Result<AsyncFdReadyGuard<'_, T>> {
+    /// Waits for any of the requested ready states, returning a
+    /// [`AsyncFdReadyGuard`] that must be dropped to resume
+    /// polling for the requested ready states.
+    ///
+    /// The function may complete without the file descriptor being ready. This is a
+    /// false-positive and attempting an operation will return with
+    /// `io::ErrorKind::WouldBlock`. The function can also return with an empty
+    /// [`Ready`] set, so you should always check the returned value and possibly
+    /// wait again if the requested states are not set.
+    ///
+    /// When an IO operation does return `io::ErrorKind::WouldBlock`, the readiness must be cleared.
+    /// When a combined interest is used, it is important to clear only the readiness
+    /// that is actually observed to block. For instance when the combined
+    /// interest `Interest::READABLE | Interest::WRITABLE` is used, and a read blocks, only
+    /// read readiness should be cleared using the [`AsyncFdReadyGuard::clear_ready_matching`] method:
+    /// `guard.clear_ready_matching(Ready::READABLE)`.
+    /// Also clearing the write readiness in this case would be incorrect. The [`AsyncFdReadyGuard::clear_ready`]
+    /// method clears all readiness flags.
+    ///
+    /// This method takes `&self`, so it is possible to call this method
+    /// concurrently with other methods on this struct. This method only
+    /// provides shared access to the inner IO resource when handling the
+    /// [`AsyncFdReadyGuard`].
+    ///
+    /// # Examples
+    ///
+    /// Concurrently read and write to a [`std::net::TcpStream`] on the same task without
+    /// splitting.
+    ///
+    /// ```no_run
+    /// use std::error::Error;
+    /// use std::io;
+    /// use std::io::{Read, Write};
+    /// use std::net::TcpStream;
+    /// use tokio::io::unix::AsyncFd;
+    /// use tokio::io::{Interest, Ready};
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> Result<(), Box<dyn Error>> {
+    ///     let stream = TcpStream::connect("127.0.0.1:8080")?;
+    ///     stream.set_nonblocking(true)?;
+    ///     let stream = AsyncFd::new(stream)?;
+    ///
+    ///     loop {
+    ///         let mut guard = stream
+    ///             .ready(Interest::READABLE | Interest::WRITABLE)
+    ///             .await?;
+    ///
+    ///         if guard.ready().is_readable() {
+    ///             let mut data = vec![0; 1024];
+    ///             // Try to read data, this may still fail with `WouldBlock`
+    ///             // if the readiness event is a false positive.
+    ///             match stream.get_ref().read(&mut data) {
+    ///                 Ok(n) => {
+    ///                     println!("read {} bytes", n);
+    ///                 }
+    ///                 Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
+    ///                     // a read has blocked, but a write might still succeed.
+    ///                     // clear only the read readiness.
+    ///                     guard.clear_ready_matching(Ready::READABLE);
+    ///                     continue;
+    ///                 }
+    ///                 Err(e) => {
+    ///                     return Err(e.into());
+    ///                 }
+    ///             }
+    ///         }
+    ///
+    ///         if guard.ready().is_writable() {
+    ///             // Try to write data, this may still fail with `WouldBlock`
+    ///             // if the readiness event is a false positive.
+    ///             match stream.get_ref().write(b"hello world") {
+    ///                 Ok(n) => {
+    ///                     println!("write {} bytes", n);
+    ///                 }
+    ///                 Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
+    ///                     // a write has blocked, but a read might still succeed.
+    ///                     // clear only the write readiness.
+    ///                     guard.clear_ready_matching(Ready::WRITABLE);
+    ///                     continue;
+    ///                 }
+    ///                 Err(e) => {
+    ///                     return Err(e.into());
+    ///                 }
+    ///             }
+    ///         }
+    ///     }
+    /// }
+    /// ```
+    pub async fn ready(&self, interest: Interest) -> io::Result<AsyncFdReadyGuard<'_, T>> {
         let event = self.registration.readiness(interest).await?;
 
         Ok(AsyncFdReadyGuard {
@@ -398,7 +540,94 @@ impl<T: AsRawFd> AsyncFd<T> {
         })
     }
 
-    async fn readiness_mut(
+    /// Waits for any of the requested ready states, returning a
+    /// [`AsyncFdReadyMutGuard`] that must be dropped to resume
+    /// polling for the requested ready states.
+    ///
+    /// The function may complete without the file descriptor being ready. This is a
+    /// false-positive and attempting an operation will return with
+    /// `io::ErrorKind::WouldBlock`. The function can also return with an empty
+    /// [`Ready`] set, so you should always check the returned value and possibly
+    /// wait again if the requested states are not set.
+    ///
+    /// When an IO operation does return `io::ErrorKind::WouldBlock`, the readiness must be cleared.
+    /// When a combined interest is used, it is important to clear only the readiness
+    /// that is actually observed to block. For instance when the combined
+    /// interest `Interest::READABLE | Interest::WRITABLE` is used, and a read blocks, only
+    /// read readiness should be cleared using the [`AsyncFdReadyMutGuard::clear_ready_matching`] method:
+    /// `guard.clear_ready_matching(Ready::READABLE)`.
+    /// Also clearing the write readiness in this case would be incorrect.
+    /// The [`AsyncFdReadyMutGuard::clear_ready`] method clears all readiness flags.
+    ///
+    /// This method takes `&mut self`, so it is possible to access the inner IO
+    /// resource mutably when handling the [`AsyncFdReadyMutGuard`].
+    ///
+    /// # Examples
+    ///
+    /// Concurrently read and write to a [`std::net::TcpStream`] on the same task without
+    /// splitting.
+    ///
+    /// ```no_run
+    /// use std::error::Error;
+    /// use std::io;
+    /// use std::io::{Read, Write};
+    /// use std::net::TcpStream;
+    /// use tokio::io::unix::AsyncFd;
+    /// use tokio::io::{Interest, Ready};
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> Result<(), Box<dyn Error>> {
+    ///     let stream = TcpStream::connect("127.0.0.1:8080")?;
+    ///     stream.set_nonblocking(true)?;
+    ///     let mut stream = AsyncFd::new(stream)?;
+    ///
+    ///     loop {
+    ///         let mut guard = stream
+    ///             .ready_mut(Interest::READABLE | Interest::WRITABLE)
+    ///             .await?;
+    ///
+    ///         if guard.ready().is_readable() {
+    ///             let mut data = vec![0; 1024];
+    ///             // Try to read data, this may still fail with `WouldBlock`
+    ///             // if the readiness event is a false positive.
+    ///             match guard.get_inner_mut().read(&mut data) {
+    ///                 Ok(n) => {
+    ///                     println!("read {} bytes", n);
+    ///                 }
+    ///                 Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
+    ///                     // a read has blocked, but a write might still succeed.
+    ///                     // clear only the read readiness.
+    ///                     guard.clear_ready_matching(Ready::READABLE);
+    ///                     continue;
+    ///                 }
+    ///                 Err(e) => {
+    ///                     return Err(e.into());
+    ///                 }
+    ///             }
+    ///         }
+    ///
+    ///         if guard.ready().is_writable() {
+    ///             // Try to write data, this may still fail with `WouldBlock`
+    ///             // if the readiness event is a false positive.
+    ///             match guard.get_inner_mut().write(b"hello world") {
+    ///                 Ok(n) => {
+    ///                     println!("write {} bytes", n);
+    ///                 }
+    ///                 Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
+    ///                     // a write has blocked, but a read might still succeed.
+    ///                     // clear only the write readiness.
+    ///                     guard.clear_ready_matching(Ready::WRITABLE);
+    ///                     continue;
+    ///                 }
+    ///                 Err(e) => {
+    ///                     return Err(e.into());
+    ///                 }
+    ///             }
+    ///         }
+    ///     }
+    /// }
+    /// ```
+    pub async fn ready_mut(
         &mut self,
         interest: Interest,
     ) -> io::Result<AsyncFdReadyMutGuard<'_, T>> {
@@ -420,7 +649,7 @@ impl<T: AsRawFd> AsyncFd<T> {
     /// [`AsyncFdReadyGuard`].
     #[allow(clippy::needless_lifetimes)] // The lifetime improves rustdoc rendering.
     pub async fn readable<'a>(&'a self) -> io::Result<AsyncFdReadyGuard<'a, T>> {
-        self.readiness(Interest::READABLE).await
+        self.ready(Interest::READABLE).await
     }
 
     /// Waits for the file descriptor to become readable, returning a
@@ -431,7 +660,7 @@ impl<T: AsRawFd> AsyncFd<T> {
     /// resource mutably when handling the [`AsyncFdReadyMutGuard`].
     #[allow(clippy::needless_lifetimes)] // The lifetime improves rustdoc rendering.
     pub async fn readable_mut<'a>(&'a mut self) -> io::Result<AsyncFdReadyMutGuard<'a, T>> {
-        self.readiness_mut(Interest::READABLE).await
+        self.ready_mut(Interest::READABLE).await
     }
 
     /// Waits for the file descriptor to become writable, returning a
@@ -444,7 +673,7 @@ impl<T: AsRawFd> AsyncFd<T> {
     /// [`AsyncFdReadyGuard`].
     #[allow(clippy::needless_lifetimes)] // The lifetime improves rustdoc rendering.
     pub async fn writable<'a>(&'a self) -> io::Result<AsyncFdReadyGuard<'a, T>> {
-        self.readiness(Interest::WRITABLE).await
+        self.ready(Interest::WRITABLE).await
     }
 
     /// Waits for the file descriptor to become writable, returning a
@@ -455,7 +684,110 @@ impl<T: AsRawFd> AsyncFd<T> {
     /// resource mutably when handling the [`AsyncFdReadyMutGuard`].
     #[allow(clippy::needless_lifetimes)] // The lifetime improves rustdoc rendering.
     pub async fn writable_mut<'a>(&'a mut self) -> io::Result<AsyncFdReadyMutGuard<'a, T>> {
-        self.readiness_mut(Interest::WRITABLE).await
+        self.ready_mut(Interest::WRITABLE).await
+    }
+
+    /// Reads or writes from the file descriptor using a user-provided IO operation.
+    ///
+    /// The `async_io` method is a convenience utility that waits for the file
+    /// descriptor to become ready, and then executes the provided IO operation.
+    /// Since file descriptors may be marked ready spuriously, the closure will
+    /// be called repeatedly until it returns something other than a
+    /// [`WouldBlock`] error. This is done using the following loop:
+    ///
+    /// ```no_run
+    /// # use std::io::{self, Result};
+    /// # struct Dox<T> { inner: T }
+    /// # impl<T> Dox<T> {
+    /// #     async fn writable(&self) -> Result<&Self> {
+    /// #         Ok(self)
+    /// #     }
+    /// #     fn try_io<R>(&self, _: impl FnMut(&T) -> Result<R>) -> Result<Result<R>> {
+    /// #         panic!()
+    /// #     }
+    /// async fn async_io<R>(&self, mut f: impl FnMut(&T) -> io::Result<R>) -> io::Result<R> {
+    ///     loop {
+    ///         // or `readable` if called with the read interest.
+    ///         let guard = self.writable().await?;
+    ///
+    ///         match guard.try_io(&mut f) {
+    ///             Ok(result) => return result,
+    ///             Err(_would_block) => continue,
+    ///         }
+    ///     }
+    /// }
+    /// # }
+    /// ```
+    ///
+    /// The closure should only return a [`WouldBlock`] error if it has performed
+    /// an IO operation on the file descriptor that failed due to the file descriptor not being
+    /// ready. Returning a [`WouldBlock`] error in any other situation will
+    /// incorrectly clear the readiness flag, which can cause the file descriptor to
+    /// behave incorrectly.
+    ///
+    /// The closure should not perform the IO operation using any of the methods
+    /// defined on the Tokio [`AsyncFd`] type, as this will mess with the
+    /// readiness flag and can cause the file descriptor to behave incorrectly.
+    ///
+    /// This method is not intended to be used with combined interests.
+    /// The closure should perform only one type of IO operation, so it should not
+    /// require more than one ready state. This method may panic or sleep forever
+    /// if it is called with a combined interest.
+    ///
+    /// # Examples
+    ///
+    /// This example sends some bytes on the inner [`std::net::UdpSocket`]. The `async_io`
+    /// method waits for readiness, and retries if the send operation does block. This example
+    /// is equivalent to the one given for [`try_io`].
+    ///
+    /// ```no_run
+    /// use tokio::io::{Interest, unix::AsyncFd};
+    ///
+    /// use std::io;
+    /// use std::net::UdpSocket;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> io::Result<()> {
+    ///     let socket = UdpSocket::bind("0.0.0.0:8080")?;
+    ///     socket.set_nonblocking(true)?;
+    ///     let async_fd = AsyncFd::new(socket)?;
+    ///
+    ///     let written = async_fd
+    ///         .async_io(Interest::WRITABLE, |inner| inner.send(&[1, 2]))
+    ///         .await?;
+    ///
+    ///     println!("wrote {written} bytes");
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    ///
+    /// [`try_io`]: AsyncFdReadyGuard::try_io
+    /// [`WouldBlock`]: std::io::ErrorKind::WouldBlock
+    pub async fn async_io<R>(
+        &self,
+        interest: Interest,
+        mut f: impl FnMut(&T) -> io::Result<R>,
+    ) -> io::Result<R> {
+        self.registration
+            .async_io(interest, || f(self.get_ref()))
+            .await
+    }
+
+    /// Reads or writes from the file descriptor using a user-provided IO operation.
+    ///
+    /// The behavior is the same as [`async_io`], except that the closure can mutate the inner
+    /// value of the [`AsyncFd`].
+    ///
+    /// [`async_io`]: AsyncFd::async_io
+    pub async fn async_io_mut<R>(
+        &mut self,
+        interest: Interest,
+        mut f: impl FnMut(&mut T) -> io::Result<R>,
+    ) -> io::Result<R> {
+        self.registration
+            .async_io(interest, || f(self.inner.as_mut().unwrap()))
+            .await
     }
 }
 
@@ -465,6 +797,13 @@ impl<T: AsRawFd> AsRawFd for AsyncFd<T> {
     }
 }
 
+#[cfg(not(tokio_no_as_fd))]
+impl<T: AsRawFd> std::os::unix::io::AsFd for AsyncFd<T> {
+    fn as_fd(&self) -> std::os::unix::io::BorrowedFd<'_> {
+        unsafe { std::os::unix::io::BorrowedFd::borrow_raw(self.as_raw_fd()) }
+    }
+}
+
 impl<T: std::fmt::Debug + AsRawFd> std::fmt::Debug for AsyncFd<T> {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         f.debug_struct("AsyncFd")
@@ -480,22 +819,117 @@ impl<T: AsRawFd> Drop for AsyncFd<T> {
 }
 
 impl<'a, Inner: AsRawFd> AsyncFdReadyGuard<'a, Inner> {
-    /// Indicates to tokio that the file descriptor is no longer ready. The
-    /// internal readiness flag will be cleared, and tokio will wait for the
+    /// Indicates to tokio that the file descriptor is no longer ready. All
+    /// internal readiness flags will be cleared, and tokio will wait for the
     /// next edge-triggered readiness notification from the OS.
     ///
+    /// This function is commonly used with guards returned by [`AsyncFd::readable`] and
+    /// [`AsyncFd::writable`].
+    ///
     /// It is critical that this function not be called unless your code
     /// _actually observes_ that the file descriptor is _not_ ready. Do not call
     /// it simply because, for example, a read succeeded; it should be called
     /// when a read is observed to block.
-    ///
-    /// [`drop`]: method@std::mem::drop
     pub fn clear_ready(&mut self) {
         if let Some(event) = self.event.take() {
             self.async_fd.registration.clear_readiness(event);
         }
     }
 
+    /// Indicates to tokio that the file descriptor no longer has a specific readiness.
+    /// The internal readiness flag will be cleared, and tokio will wait for the
+    /// next edge-triggered readiness notification from the OS.
+    ///
+    /// This function is useful in combination with the [`AsyncFd::ready`] method when a
+    /// combined interest like `Interest::READABLE | Interest::WRITABLE` is used.
+    ///
+    /// It is critical that this function not be called unless your code
+    /// _actually observes_ that the file descriptor is _not_ ready for the provided `Ready`.
+    /// Do not call it simply because, for example, a read succeeded; it should be called
+    /// when a read is observed to block. Only clear the specific readiness that is observed to
+    /// block. For example when a read blocks when using a combined interest,
+    /// only clear `Ready::READABLE`.
+    ///
+    /// # Examples
+    ///
+    /// Concurrently read and write to a [`std::net::TcpStream`] on the same task without
+    /// splitting.
+    ///
+    /// ```no_run
+    /// use std::error::Error;
+    /// use std::io;
+    /// use std::io::{Read, Write};
+    /// use std::net::TcpStream;
+    /// use tokio::io::unix::AsyncFd;
+    /// use tokio::io::{Interest, Ready};
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> Result<(), Box<dyn Error>> {
+    ///     let stream = TcpStream::connect("127.0.0.1:8080")?;
+    ///     stream.set_nonblocking(true)?;
+    ///     let stream = AsyncFd::new(stream)?;
+    ///
+    ///     loop {
+    ///         let mut guard = stream
+    ///             .ready(Interest::READABLE | Interest::WRITABLE)
+    ///             .await?;
+    ///
+    ///         if guard.ready().is_readable() {
+    ///             let mut data = vec![0; 1024];
+    ///             // Try to read data, this may still fail with `WouldBlock`
+    ///             // if the readiness event is a false positive.
+    ///             match stream.get_ref().read(&mut data) {
+    ///                 Ok(n) => {
+    ///                     println!("read {} bytes", n);
+    ///                 }
+    ///                 Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
+    ///                     // a read has blocked, but a write might still succeed.
+    ///                     // clear only the read readiness.
+    ///                     guard.clear_ready_matching(Ready::READABLE);
+    ///                     continue;
+    ///                 }
+    ///                 Err(e) => {
+    ///                     return Err(e.into());
+    ///                 }
+    ///             }
+    ///         }
+    ///
+    ///         if guard.ready().is_writable() {
+    ///             // Try to write data, this may still fail with `WouldBlock`
+    ///             // if the readiness event is a false positive.
+    ///             match stream.get_ref().write(b"hello world") {
+    ///                 Ok(n) => {
+    ///                     println!("write {} bytes", n);
+    ///                 }
+    ///                 Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
+    ///                     // a write has blocked, but a read might still succeed.
+    ///                     // clear only the write readiness.
+    ///                     guard.clear_ready_matching(Ready::WRITABLE);
+    ///                     continue;
+    ///                 }
+    ///                 Err(e) => {
+    ///                     return Err(e.into());
+    ///                 }
+    ///             }
+    ///         }
+    ///     }
+    /// }
+    /// ```
+    pub fn clear_ready_matching(&mut self, ready: Ready) {
+        if let Some(mut event) = self.event.take() {
+            self.async_fd
+                .registration
+                .clear_readiness(event.with_ready(ready));
+
+            // the event is no longer ready for the readiness that was just cleared
+            event.ready = event.ready - ready;
+
+            if !event.ready.is_empty() {
+                self.event = Some(event);
+            }
+        }
+    }
+
     /// This method should be invoked when you intentionally want to keep the
     /// ready flag asserted.
     ///
@@ -505,6 +939,20 @@ impl<'a, Inner: AsRawFd> AsyncFdReadyGuard<'a, Inner> {
         // no-op
     }
 
+    /// Get the [`Ready`] value associated with this guard.
+    ///
+    /// This method will return the empty readiness state if
+    /// [`AsyncFdReadyGuard::clear_ready`] has been called on
+    /// the guard.
+    ///
+    /// [`Ready`]: crate::io::Ready
+    pub fn ready(&self) -> Ready {
+        match &self.event {
+            Some(event) => event.ready,
+            None => Ready::EMPTY,
+        }
+    }
+
     /// Performs the provided IO operation.
     ///
     /// If `f` returns a [`WouldBlock`] error, the readiness state associated
@@ -520,12 +968,49 @@ impl<'a, Inner: AsRawFd> AsyncFdReadyGuard<'a, Inner> {
     /// `AsyncFdReadyGuard` no longer expresses the readiness state that was queried to
     /// create this `AsyncFdReadyGuard`.
     ///
+    /// # Examples
+    ///
+    /// This example sends some bytes to the inner [`std::net::UdpSocket`]. Waiting
+    /// for write-readiness and retrying when the send operation does block are explicit.
+    /// This example can be written more succinctly using [`AsyncFd::async_io`].
+    ///
+    /// ```no_run
+    /// use tokio::io::unix::AsyncFd;
+    ///
+    /// use std::io;
+    /// use std::net::UdpSocket;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> io::Result<()> {
+    ///     let socket = UdpSocket::bind("0.0.0.0:8080")?;
+    ///     socket.set_nonblocking(true)?;
+    ///     let async_fd = AsyncFd::new(socket)?;
+    ///
+    ///     let written = loop {
+    ///         let mut guard = async_fd.writable().await?;
+    ///         match guard.try_io(|inner| inner.get_ref().send(&[1, 2])) {
+    ///             Ok(result) => {
+    ///                 break result?;
+    ///             }
+    ///             Err(_would_block) => {
+    ///                 // try_io already cleared the file descriptor's readiness state
+    ///                 continue;
+    ///             }
+    ///         }
+    ///     };
+    ///
+    ///     println!("wrote {written} bytes");
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    ///
     /// [`WouldBlock`]: std::io::ErrorKind::WouldBlock
     // Alias for old name in 0.x
     #[cfg_attr(docsrs, doc(alias = "with_io"))]
     pub fn try_io<R>(
         &mut self,
-        f: impl FnOnce(&AsyncFd<Inner>) -> io::Result<R>,
+        f: impl FnOnce(&'a AsyncFd<Inner>) -> io::Result<R>,
     ) -> Result<io::Result<R>, TryIoError> {
         let result = f(self.async_fd);
 
@@ -542,33 +1027,128 @@ impl<'a, Inner: AsRawFd> AsyncFdReadyGuard<'a, Inner> {
     }
 
     /// Returns a shared reference to the inner [`AsyncFd`].
-    pub fn get_ref(&self) -> &AsyncFd<Inner> {
+    pub fn get_ref(&self) -> &'a AsyncFd<Inner> {
         self.async_fd
     }
 
     /// Returns a shared reference to the backing object of the inner [`AsyncFd`].
-    pub fn get_inner(&self) -> &Inner {
+    pub fn get_inner(&self) -> &'a Inner {
         self.get_ref().get_ref()
     }
 }
 
 impl<'a, Inner: AsRawFd> AsyncFdReadyMutGuard<'a, Inner> {
-    /// Indicates to tokio that the file descriptor is no longer ready. The
-    /// internal readiness flag will be cleared, and tokio will wait for the
+    /// Indicates to tokio that the file descriptor is no longer ready. All
+    /// internal readiness flags will be cleared, and tokio will wait for the
     /// next edge-triggered readiness notification from the OS.
     ///
+    /// This function is commonly used with guards returned by [`AsyncFd::readable_mut`] and
+    /// [`AsyncFd::writable_mut`].
+    ///
     /// It is critical that this function not be called unless your code
     /// _actually observes_ that the file descriptor is _not_ ready. Do not call
     /// it simply because, for example, a read succeeded; it should be called
     /// when a read is observed to block.
-    ///
-    /// [`drop`]: method@std::mem::drop
     pub fn clear_ready(&mut self) {
         if let Some(event) = self.event.take() {
             self.async_fd.registration.clear_readiness(event);
         }
     }
 
+    /// Indicates to tokio that the file descriptor no longer has a specific readiness.
+    /// The internal readiness flag will be cleared, and tokio will wait for the
+    /// next edge-triggered readiness notification from the OS.
+    ///
+    /// This function is useful in combination with the [`AsyncFd::ready_mut`] method when a
+    /// combined interest like `Interest::READABLE | Interest::WRITABLE` is used.
+    ///
+    /// It is critical that this function not be called unless your code
+    /// _actually observes_ that the file descriptor is _not_ ready for the provided `Ready`.
+    /// Do not call it simply because, for example, a read succeeded; it should be called
+    /// when a read is observed to block. Only clear the specific readiness that is observed to
+    /// block. For example when a read blocks when using a combined interest,
+    /// only clear `Ready::READABLE`.
+    ///
+    /// # Examples
+    ///
+    /// Concurrently read and write to a [`std::net::TcpStream`] on the same task without
+    /// splitting.
+    ///
+    /// ```no_run
+    /// use std::error::Error;
+    /// use std::io;
+    /// use std::io::{Read, Write};
+    /// use std::net::TcpStream;
+    /// use tokio::io::unix::AsyncFd;
+    /// use tokio::io::{Interest, Ready};
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> Result<(), Box<dyn Error>> {
+    ///     let stream = TcpStream::connect("127.0.0.1:8080")?;
+    ///     stream.set_nonblocking(true)?;
+    ///     let mut stream = AsyncFd::new(stream)?;
+    ///
+    ///     loop {
+    ///         let mut guard = stream
+    ///             .ready_mut(Interest::READABLE | Interest::WRITABLE)
+    ///             .await?;
+    ///
+    ///         if guard.ready().is_readable() {
+    ///             let mut data = vec![0; 1024];
+    ///             // Try to read data, this may still fail with `WouldBlock`
+    ///             // if the readiness event is a false positive.
+    ///             match guard.get_inner_mut().read(&mut data) {
+    ///                 Ok(n) => {
+    ///                     println!("read {} bytes", n);
+    ///                 }
+    ///                 Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
+    ///                     // a read has blocked, but a write might still succeed.
+    ///                     // clear only the read readiness.
+    ///                     guard.clear_ready_matching(Ready::READABLE);
+    ///                     continue;
+    ///                 }
+    ///                 Err(e) => {
+    ///                     return Err(e.into());
+    ///                 }
+    ///             }
+    ///         }
+    ///
+    ///         if guard.ready().is_writable() {
+    ///             // Try to write data, this may still fail with `WouldBlock`
+    ///             // if the readiness event is a false positive.
+    ///             match guard.get_inner_mut().write(b"hello world") {
+    ///                 Ok(n) => {
+    ///                     println!("write {} bytes", n);
+    ///                 }
+    ///                 Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
+    ///                     // a write has blocked, but a read might still succeed.
+    ///                     // clear only the write readiness.
+    ///                     guard.clear_ready_matching(Ready::WRITABLE);
+    ///                     continue;
+    ///                 }
+    ///                 Err(e) => {
+    ///                     return Err(e.into());
+    ///                 }
+    ///             }
+    ///         }
+    ///     }
+    /// }
+    /// ```
+    pub fn clear_ready_matching(&mut self, ready: Ready) {
+        if let Some(mut event) = self.event.take() {
+            self.async_fd
+                .registration
+                .clear_readiness(event.with_ready(ready));
+
+            // the event is no longer ready for the readiness that was just cleared
+            event.ready = event.ready - ready;
+
+            if !event.ready.is_empty() {
+                self.event = Some(event);
+            }
+        }
+    }
+
     /// This method should be invoked when you intentionally want to keep the
     /// ready flag asserted.
     ///
@@ -578,6 +1158,20 @@ impl<'a, Inner: AsRawFd> AsyncFdReadyMutGuard<'a, Inner> {
         // no-op
     }
 
+    /// Get the [`Ready`] value associated with this guard.
+    ///
+    /// This method will return the empty readiness state if
+    /// [`AsyncFdReadyGuard::clear_ready`] has been called on
+    /// the guard.
+    ///
+    /// [`Ready`]: super::Ready
+    pub fn ready(&self) -> Ready {
+        match &self.event {
+            Some(event) => event.ready,
+            None => Ready::EMPTY,
+        }
+    }
+
     /// Performs the provided IO operation.
     ///
     /// If `f` returns a [`WouldBlock`] error, the readiness state associated
@@ -598,7 +1192,7 @@ impl<'a, Inner: AsRawFd> AsyncFdReadyMutGuard<'a, Inner> {
         &mut self,
         f: impl FnOnce(&mut AsyncFd<Inner>) -> io::Result<R>,
     ) -> Result<io::Result<R>, TryIoError> {
-        let result = f(&mut self.async_fd);
+        let result = f(self.async_fd);
 
         if let Err(e) = result.as_ref() {
             if e.kind() == io::ErrorKind::WouldBlock {
diff --git a/vendor/tokio/src/io/blocking.rs b/vendor/tokio/src/io/blocking.rs
index 94a3484ff..416573e97 100644
--- a/vendor/tokio/src/io/blocking.rs
+++ b/vendor/tokio/src/io/blocking.rs
@@ -16,7 +16,7 @@ use self::State::*;
 pub(crate) struct Blocking<T> {
     inner: Option<T>,
     state: State<T>,
-    /// `true` if the lower IO layer needs flushing
+    /// `true` if the lower IO layer needs flushing.
     need_flush: bool,
 }
 
@@ -26,7 +26,7 @@ pub(crate) struct Buf {
     pos: usize,
 }
 
-pub(crate) const MAX_BUF: usize = 16 * 1024;
+pub(crate) const MAX_BUF: usize = 2 * 1024 * 1024;
 
 #[derive(Debug)]
 enum State<T> {
@@ -34,8 +34,9 @@ enum State<T> {
     Busy(sys::Blocking<(io::Result<usize>, Buf, T)>),
 }
 
-cfg_io_std! {
+cfg_io_blocking! {
     impl<T> Blocking<T> {
+        #[cfg_attr(feature = "fs", allow(dead_code))]
         pub(crate) fn new(inner: T) -> Blocking<T> {
             Blocking {
                 inner: Some(inner),
@@ -175,7 +176,7 @@ where
     }
 }
 
-/// Repeats operations that are interrupted
+/// Repeats operations that are interrupted.
 macro_rules! uninterruptibly {
     ($e:expr) => {{
         loop {
diff --git a/vendor/tokio/src/io/bsd/poll_aio.rs b/vendor/tokio/src/io/bsd/poll_aio.rs
new file mode 100644
index 000000000..6ac9e2880
--- /dev/null
+++ b/vendor/tokio/src/io/bsd/poll_aio.rs
@@ -0,0 +1,197 @@
+//! Use POSIX AIO futures with Tokio.
+
+use crate::io::interest::Interest;
+use crate::runtime::io::{ReadyEvent, Registration};
+use crate::runtime::scheduler;
+use mio::event::Source;
+use mio::Registry;
+use mio::Token;
+use std::fmt;
+use std::io;
+use std::ops::{Deref, DerefMut};
+use std::os::unix::io::AsRawFd;
+use std::os::unix::prelude::RawFd;
+use std::task::{Context, Poll};
+
+/// Like [`mio::event::Source`], but for POSIX AIO only.
+///
+/// Tokio's consumer must pass an implementor of this trait to create a
+/// [`Aio`] object.
+pub trait AioSource {
+    /// Registers this AIO event source with Tokio's reactor.
+    fn register(&mut self, kq: RawFd, token: usize);
+
+    /// Deregisters this AIO event source with Tokio's reactor.
+    fn deregister(&mut self);
+}
+
+/// Wraps the user's AioSource in order to implement mio::event::Source, which
+/// is what the rest of the crate wants.
+struct MioSource<T>(T);
+
+impl<T: AioSource> Source for MioSource<T> {
+    fn register(
+        &mut self,
+        registry: &Registry,
+        token: Token,
+        interests: mio::Interest,
+    ) -> io::Result<()> {
+        assert!(interests.is_aio() || interests.is_lio());
+        self.0.register(registry.as_raw_fd(), usize::from(token));
+        Ok(())
+    }
+
+    fn deregister(&mut self, _registry: &Registry) -> io::Result<()> {
+        self.0.deregister();
+        Ok(())
+    }
+
+    fn reregister(
+        &mut self,
+        registry: &Registry,
+        token: Token,
+        interests: mio::Interest,
+    ) -> io::Result<()> {
+        assert!(interests.is_aio() || interests.is_lio());
+        self.0.register(registry.as_raw_fd(), usize::from(token));
+        Ok(())
+    }
+}
+
+/// Associates a POSIX AIO control block with the reactor that drives it.
+///
+/// `Aio`'s wrapped type must implement [`AioSource`] to be driven
+/// by the reactor.
+///
+/// The wrapped source may be accessed through the `Aio` via the `Deref` and
+/// `DerefMut` traits.
+///
+/// ## Clearing readiness
+///
+/// If [`Aio::poll_ready`] returns ready, but the consumer determines that the
+/// Source is not completely ready and must return to the Pending state,
+/// [`Aio::clear_ready`] may be used.  This can be useful with
+/// [`lio_listio`], which may generate a kevent when only a portion of the
+/// operations have completed.
+///
+/// ## Platforms
+///
+/// Only FreeBSD implements POSIX AIO with kqueue notification, so
+/// `Aio` is only available for that operating system.
+///
+/// [`lio_listio`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/lio_listio.html
+// Note: Unlike every other kqueue event source, POSIX AIO registers events not
+// via kevent(2) but when the aiocb is submitted to the kernel via aio_read,
+// aio_write, etc.  It needs the kqueue's file descriptor to do that.  So
+// AsyncFd can't be used for POSIX AIO.
+//
+// Note that Aio doesn't implement Drop.  There's no need.  Unlike other
+// kqueue sources, simply dropping the object effectively deregisters it.
+pub struct Aio<E> {
+    io: MioSource<E>,
+    registration: Registration,
+}
+
+// ===== impl Aio =====
+
+impl<E: AioSource> Aio<E> {
+    /// Creates a new `Aio` suitable for use with POSIX AIO functions.
+    ///
+    /// It will be associated with the default reactor.  The runtime is usually
+    /// set implicitly when this function is called from a future driven by a
+    /// Tokio runtime, otherwise runtime can be set explicitly with
+    /// [`Runtime::enter`](crate::runtime::Runtime::enter) function.
+    pub fn new_for_aio(io: E) -> io::Result<Self> {
+        Self::new_with_interest(io, Interest::AIO)
+    }
+
+    /// Creates a new `Aio` suitable for use with [`lio_listio`].
+    ///
+    /// It will be associated with the default reactor.  The runtime is usually
+    /// set implicitly when this function is called from a future driven by a
+    /// Tokio runtime, otherwise runtime can be set explicitly with
+    /// [`Runtime::enter`](crate::runtime::Runtime::enter) function.
+    ///
+    /// [`lio_listio`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/lio_listio.html
+    pub fn new_for_lio(io: E) -> io::Result<Self> {
+        Self::new_with_interest(io, Interest::LIO)
+    }
+
+    fn new_with_interest(io: E, interest: Interest) -> io::Result<Self> {
+        let mut io = MioSource(io);
+        let handle = scheduler::Handle::current();
+        let registration = Registration::new_with_interest_and_handle(&mut io, interest, handle)?;
+        Ok(Self { io, registration })
+    }
+
+    /// Indicates to Tokio that the source is no longer ready.  The internal
+    /// readiness flag will be cleared, and tokio will wait for the next
+    /// edge-triggered readiness notification from the OS.
+    ///
+    /// It is critical that this method not be called unless your code
+    /// _actually observes_ that the source is _not_ ready.  The OS must
+    /// deliver a subsequent notification, or this source will block
+    /// forever.  It is equally critical that you `do` call this method if you
+    /// resubmit the same structure to the kernel and poll it again.
+    ///
+    /// This method is not very useful with AIO readiness, since each `aiocb`
+    /// structure is typically only used once.  It's main use with
+    /// [`lio_listio`], which will sometimes send notification when only a
+    /// portion of its elements are complete.  In that case, the caller must
+    /// call `clear_ready` before resubmitting it.
+    ///
+    /// [`lio_listio`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/lio_listio.html
+    pub fn clear_ready(&self, ev: AioEvent) {
+        self.registration.clear_readiness(ev.0)
+    }
+
+    /// Destroy the [`Aio`] and return its inner source.
+    pub fn into_inner(self) -> E {
+        self.io.0
+    }
+
+    /// Polls for readiness.  Either AIO or LIO counts.
+    ///
+    /// This method returns:
+    ///  * `Poll::Pending` if the underlying operation is not complete, whether
+    ///     or not it completed successfully.  This will be true if the OS is
+    ///     still processing it, or if it has not yet been submitted to the OS.
+    ///  * `Poll::Ready(Ok(_))` if the underlying operation is complete.
+    ///  * `Poll::Ready(Err(_))` if the reactor has been shutdown.  This does
+    ///     _not_ indicate that the underlying operation encountered an error.
+    ///
+    /// When the method returns `Poll::Pending`, the `Waker` in the provided `Context`
+    /// is scheduled to receive a wakeup when the underlying operation
+    /// completes. Note that on multiple calls to `poll_ready`, only the `Waker` from the
+    /// `Context` passed to the most recent call is scheduled to receive a wakeup.
+    pub fn poll_ready<'a>(&'a self, cx: &mut Context<'_>) -> Poll<io::Result<AioEvent>> {
+        let ev = ready!(self.registration.poll_read_ready(cx))?;
+        Poll::Ready(Ok(AioEvent(ev)))
+    }
+}
+
+impl<E: AioSource> Deref for Aio<E> {
+    type Target = E;
+
+    fn deref(&self) -> &E {
+        &self.io.0
+    }
+}
+
+impl<E: AioSource> DerefMut for Aio<E> {
+    fn deref_mut(&mut self) -> &mut E {
+        &mut self.io.0
+    }
+}
+
+impl<E: AioSource + fmt::Debug> fmt::Debug for Aio<E> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("Aio").field("io", &self.io.0).finish()
+    }
+}
+
+/// Opaque data returned by [`Aio::poll_ready`].
+///
+/// It can be fed back to [`Aio::clear_ready`].
+#[derive(Debug)]
+pub struct AioEvent(ReadyEvent);
diff --git a/vendor/tokio/src/io/driver/mod.rs b/vendor/tokio/src/io/driver/mod.rs
deleted file mode 100644
index 3aa0cfbb2..000000000
--- a/vendor/tokio/src/io/driver/mod.rs
+++ /dev/null
@@ -1,353 +0,0 @@
-#![cfg_attr(not(feature = "rt"), allow(dead_code))]
-
-mod interest;
-#[allow(unreachable_pub)]
-pub use interest::Interest;
-
-mod ready;
-#[allow(unreachable_pub)]
-pub use ready::Ready;
-
-mod registration;
-pub(crate) use registration::Registration;
-
-mod scheduled_io;
-use scheduled_io::ScheduledIo;
-
-use crate::park::{Park, Unpark};
-use crate::util::slab::{self, Slab};
-use crate::{loom::sync::Mutex, util::bit};
-
-use std::fmt;
-use std::io;
-use std::sync::{Arc, Weak};
-use std::time::Duration;
-
-/// I/O driver, backed by Mio
-pub(crate) struct Driver {
-    /// Tracks the number of times `turn` is called. It is safe for this to wrap
-    /// as it is mostly used to determine when to call `compact()`
-    tick: u8,
-
-    /// Reuse the `mio::Events` value across calls to poll.
-    events: Option<mio::Events>,
-
-    /// Primary slab handle containing the state for each resource registered
-    /// with this driver. During Drop this is moved into the Inner structure, so
-    /// this is an Option to allow it to be vacated (until Drop this is always
-    /// Some)
-    resources: Option<Slab<ScheduledIo>>,
-
-    /// The system event queue
-    poll: mio::Poll,
-
-    /// State shared between the reactor and the handles.
-    inner: Arc<Inner>,
-}
-
-/// A reference to an I/O driver
-#[derive(Clone)]
-pub(crate) struct Handle {
-    inner: Weak<Inner>,
-}
-
-pub(crate) struct ReadyEvent {
-    tick: u8,
-    pub(crate) ready: Ready,
-}
-
-pub(super) struct Inner {
-    /// Primary slab handle containing the state for each resource registered
-    /// with this driver.
-    ///
-    /// The ownership of this slab is moved into this structure during
-    /// `Driver::drop`, so that `Inner::drop` can notify all outstanding handles
-    /// without risking new ones being registered in the meantime.
-    resources: Mutex<Option<Slab<ScheduledIo>>>,
-
-    /// Registers I/O resources
-    registry: mio::Registry,
-
-    /// Allocates `ScheduledIo` handles when creating new resources.
-    pub(super) io_dispatch: slab::Allocator<ScheduledIo>,
-
-    /// Used to wake up the reactor from a call to `turn`
-    waker: mio::Waker,
-}
-
-#[derive(Debug, Eq, PartialEq, Clone, Copy)]
-enum Direction {
-    Read,
-    Write,
-}
-
-enum Tick {
-    Set(u8),
-    Clear(u8),
-}
-
-// TODO: Don't use a fake token. Instead, reserve a slot entry for the wakeup
-// token.
-const TOKEN_WAKEUP: mio::Token = mio::Token(1 << 31);
-
-const ADDRESS: bit::Pack = bit::Pack::least_significant(24);
-
-// Packs the generation value in the `readiness` field.
-//
-// The generation prevents a race condition where a slab slot is reused for a
-// new socket while the I/O driver is about to apply a readiness event. The
-// generation value is checked when setting new readiness. If the generation do
-// not match, then the readiness event is discarded.
-const GENERATION: bit::Pack = ADDRESS.then(7);
-
-fn _assert_kinds() {
-    fn _assert<T: Send + Sync>() {}
-
-    _assert::<Handle>();
-}
-
-// ===== impl Driver =====
-
-impl Driver {
-    /// Creates a new event loop, returning any error that happened during the
-    /// creation.
-    pub(crate) fn new() -> io::Result<Driver> {
-        let poll = mio::Poll::new()?;
-        let waker = mio::Waker::new(poll.registry(), TOKEN_WAKEUP)?;
-        let registry = poll.registry().try_clone()?;
-
-        let slab = Slab::new();
-        let allocator = slab.allocator();
-
-        Ok(Driver {
-            tick: 0,
-            events: Some(mio::Events::with_capacity(1024)),
-            poll,
-            resources: Some(slab),
-            inner: Arc::new(Inner {
-                resources: Mutex::new(None),
-                registry,
-                io_dispatch: allocator,
-                waker,
-            }),
-        })
-    }
-
-    /// Returns a handle to this event loop which can be sent across threads
-    /// and can be used as a proxy to the event loop itself.
-    ///
-    /// Handles are cloneable and clones always refer to the same event loop.
-    /// This handle is typically passed into functions that create I/O objects
-    /// to bind them to this event loop.
-    pub(crate) fn handle(&self) -> Handle {
-        Handle {
-            inner: Arc::downgrade(&self.inner),
-        }
-    }
-
-    fn turn(&mut self, max_wait: Option<Duration>) -> io::Result<()> {
-        // How often to call `compact()` on the resource slab
-        const COMPACT_INTERVAL: u8 = 255;
-
-        self.tick = self.tick.wrapping_add(1);
-
-        if self.tick == COMPACT_INTERVAL {
-            self.resources.as_mut().unwrap().compact()
-        }
-
-        let mut events = self.events.take().expect("i/o driver event store missing");
-
-        // Block waiting for an event to happen, peeling out how many events
-        // happened.
-        match self.poll.poll(&mut events, max_wait) {
-            Ok(_) => {}
-            Err(ref e) if e.kind() == io::ErrorKind::Interrupted => {}
-            Err(e) => return Err(e),
-        }
-
-        // Process all the events that came in, dispatching appropriately
-        for event in events.iter() {
-            let token = event.token();
-
-            if token != TOKEN_WAKEUP {
-                self.dispatch(token, Ready::from_mio(event));
-            }
-        }
-
-        self.events = Some(events);
-
-        Ok(())
-    }
-
-    fn dispatch(&mut self, token: mio::Token, ready: Ready) {
-        let addr = slab::Address::from_usize(ADDRESS.unpack(token.0));
-
-        let resources = self.resources.as_mut().unwrap();
-
-        let io = match resources.get(addr) {
-            Some(io) => io,
-            None => return,
-        };
-
-        let res = io.set_readiness(Some(token.0), Tick::Set(self.tick), |curr| curr | ready);
-
-        if res.is_err() {
-            // token no longer valid!
-            return;
-        }
-
-        io.wake(ready);
-    }
-}
-
-impl Drop for Driver {
-    fn drop(&mut self) {
-        (*self.inner.resources.lock()) = self.resources.take();
-    }
-}
-
-impl Drop for Inner {
-    fn drop(&mut self) {
-        let resources = self.resources.lock().take();
-
-        if let Some(mut slab) = resources {
-            slab.for_each(|io| {
-                // If a task is waiting on the I/O resource, notify it. The task
-                // will then attempt to use the I/O resource and fail due to the
-                // driver being shutdown.
-                io.shutdown();
-            });
-        }
-    }
-}
-
-impl Park for Driver {
-    type Unpark = Handle;
-    type Error = io::Error;
-
-    fn unpark(&self) -> Self::Unpark {
-        self.handle()
-    }
-
-    fn park(&mut self) -> io::Result<()> {
-        self.turn(None)?;
-        Ok(())
-    }
-
-    fn park_timeout(&mut self, duration: Duration) -> io::Result<()> {
-        self.turn(Some(duration))?;
-        Ok(())
-    }
-
-    fn shutdown(&mut self) {}
-}
-
-impl fmt::Debug for Driver {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "Driver")
-    }
-}
-
-// ===== impl Handle =====
-
-cfg_rt! {
-    impl Handle {
-        /// Returns a handle to the current reactor
-        ///
-        /// # Panics
-        ///
-        /// This function panics if there is no current reactor set and `rt` feature
-        /// flag is not enabled.
-        pub(super) fn current() -> Self {
-            crate::runtime::context::io_handle().expect("A Tokio 1.x context was found, but IO is disabled. Call `enable_io` on the runtime builder to enable IO.")
-        }
-    }
-}
-
-cfg_not_rt! {
-    impl Handle {
-        /// Returns a handle to the current reactor
-        ///
-        /// # Panics
-        ///
-        /// This function panics if there is no current reactor set, or if the `rt`
-        /// feature flag is not enabled.
-        pub(super) fn current() -> Self {
-            panic!("{}", crate::util::error::CONTEXT_MISSING_ERROR)
-        }
-    }
-}
-
-impl Handle {
-    /// Forces a reactor blocked in a call to `turn` to wakeup, or otherwise
-    /// makes the next call to `turn` return immediately.
-    ///
-    /// This method is intended to be used in situations where a notification
-    /// needs to otherwise be sent to the main reactor. If the reactor is
-    /// currently blocked inside of `turn` then it will wake up and soon return
-    /// after this method has been called. If the reactor is not currently
-    /// blocked in `turn`, then the next call to `turn` will not block and
-    /// return immediately.
-    fn wakeup(&self) {
-        if let Some(inner) = self.inner() {
-            inner.waker.wake().expect("failed to wake I/O driver");
-        }
-    }
-
-    pub(super) fn inner(&self) -> Option<Arc<Inner>> {
-        self.inner.upgrade()
-    }
-}
-
-impl Unpark for Handle {
-    fn unpark(&self) {
-        self.wakeup();
-    }
-}
-
-impl fmt::Debug for Handle {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "Handle")
-    }
-}
-
-// ===== impl Inner =====
-
-impl Inner {
-    /// Registers an I/O resource with the reactor for a given `mio::Ready` state.
-    ///
-    /// The registration token is returned.
-    pub(super) fn add_source(
-        &self,
-        source: &mut impl mio::event::Source,
-        interest: Interest,
-    ) -> io::Result<slab::Ref<ScheduledIo>> {
-        let (address, shared) = self.io_dispatch.allocate().ok_or_else(|| {
-            io::Error::new(
-                io::ErrorKind::Other,
-                "reactor at max registered I/O resources",
-            )
-        })?;
-
-        let token = GENERATION.pack(shared.generation(), ADDRESS.pack(address.as_usize(), 0));
-
-        self.registry
-            .register(source, mio::Token(token), interest.to_mio())?;
-
-        Ok(shared)
-    }
-
-    /// Deregisters an I/O resource from the reactor.
-    pub(super) fn deregister_source(&self, source: &mut impl mio::event::Source) -> io::Result<()> {
-        self.registry.deregister(source)
-    }
-}
-
-impl Direction {
-    pub(super) fn mask(self) -> Ready {
-        match self {
-            Direction::Read => Ready::READABLE | Ready::READ_CLOSED,
-            Direction::Write => Ready::WRITABLE | Ready::WRITE_CLOSED,
-        }
-    }
-}
diff --git a/vendor/tokio/src/io/driver/platform.rs b/vendor/tokio/src/io/driver/platform.rs
deleted file mode 100644
index 6b27988ce..000000000
--- a/vendor/tokio/src/io/driver/platform.rs
+++ /dev/null
@@ -1,44 +0,0 @@
-pub(crate) use self::sys::*;
-
-#[cfg(unix)]
-mod sys {
-    use mio::unix::UnixReady;
-    use mio::Ready;
-
-    pub(crate) fn hup() -> Ready {
-        UnixReady::hup().into()
-    }
-
-    pub(crate) fn is_hup(ready: Ready) -> bool {
-        UnixReady::from(ready).is_hup()
-    }
-
-    pub(crate) fn error() -> Ready {
-        UnixReady::error().into()
-    }
-
-    pub(crate) fn is_error(ready: Ready) -> bool {
-        UnixReady::from(ready).is_error()
-    }
-}
-
-#[cfg(windows)]
-mod sys {
-    use mio::Ready;
-
-    pub(crate) fn hup() -> Ready {
-        Ready::empty()
-    }
-
-    pub(crate) fn is_hup(_: Ready) -> bool {
-        false
-    }
-
-    pub(crate) fn error() -> Ready {
-        Ready::empty()
-    }
-
-    pub(crate) fn is_error(_: Ready) -> bool {
-        false
-    }
-}
diff --git a/vendor/tokio/src/io/driver/interest.rs b/vendor/tokio/src/io/interest.rs
index 36951cf5a..3a39cf761 100644
--- a/vendor/tokio/src/io/driver/interest.rs
+++ b/vendor/tokio/src/io/interest.rs
@@ -1,11 +1,11 @@
 #![cfg_attr(not(feature = "net"), allow(dead_code, unreachable_pub))]
 
-use crate::io::driver::Ready;
+use crate::io::ready::Ready;
 
 use std::fmt;
 use std::ops;
 
-/// Readiness event interest
+/// Readiness event interest.
 ///
 /// Specifies the readiness events the caller is interested in when awaiting on
 /// I/O resource readiness states.
@@ -14,16 +14,41 @@ use std::ops;
 pub struct Interest(mio::Interest);
 
 impl Interest {
+    // The non-FreeBSD definitions in this block are active only when
+    // building documentation.
+    cfg_aio! {
+        /// Interest for POSIX AIO.
+        #[cfg(target_os = "freebsd")]
+        pub const AIO: Interest = Interest(mio::Interest::AIO);
+
+        /// Interest for POSIX AIO.
+        #[cfg(not(target_os = "freebsd"))]
+        pub const AIO: Interest = Interest(mio::Interest::READABLE);
+
+        /// Interest for POSIX AIO lio_listio events.
+        #[cfg(target_os = "freebsd")]
+        pub const LIO: Interest = Interest(mio::Interest::LIO);
+
+        /// Interest for POSIX AIO lio_listio events.
+        #[cfg(not(target_os = "freebsd"))]
+        pub const LIO: Interest = Interest(mio::Interest::READABLE);
+    }
+
     /// Interest in all readable events.
     ///
     /// Readable interest includes read-closed events.
     pub const READABLE: Interest = Interest(mio::Interest::READABLE);
 
-    /// Interest in all writable events
+    /// Interest in all writable events.
     ///
     /// Writable interest includes write-closed events.
     pub const WRITABLE: Interest = Interest(mio::Interest::WRITABLE);
 
+    /// Returns a `Interest` set representing priority completion interests.
+    #[cfg(any(target_os = "linux", target_os = "android"))]
+    #[cfg_attr(docsrs, doc(cfg(any(target_os = "linux", target_os = "android"))))]
+    pub const PRIORITY: Interest = Interest(mio::Interest::PRIORITY);
+
     /// Returns true if the value includes readable interest.
     ///
     /// # Examples
@@ -58,6 +83,25 @@ impl Interest {
         self.0.is_writable()
     }
 
+    /// Returns true if the value includes priority interest.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::io::Interest;
+    ///
+    /// assert!(!Interest::READABLE.is_priority());
+    /// assert!(Interest::PRIORITY.is_priority());
+    ///
+    /// let both = Interest::READABLE | Interest::PRIORITY;
+    /// assert!(both.is_priority());
+    /// ```
+    #[cfg(any(target_os = "linux", target_os = "android"))]
+    #[cfg_attr(docsrs, doc(cfg(any(target_os = "linux", target_os = "android"))))]
+    pub const fn is_priority(self) -> bool {
+        self.0.is_priority()
+    }
+
     /// Add together two `Interest` values.
     ///
     /// This function works from a `const` context.
@@ -80,10 +124,12 @@ impl Interest {
         self.0
     }
 
-    pub(super) fn mask(self) -> Ready {
+    pub(crate) fn mask(self) -> Ready {
         match self {
             Interest::READABLE => Ready::READABLE | Ready::READ_CLOSED,
             Interest::WRITABLE => Ready::WRITABLE | Ready::WRITE_CLOSED,
+            #[cfg(any(target_os = "linux", target_os = "android"))]
+            Interest::PRIORITY => Ready::PRIORITY | Ready::READ_CLOSED,
             _ => Ready::EMPTY,
         }
     }
diff --git a/vendor/tokio/src/io/mod.rs b/vendor/tokio/src/io/mod.rs
index 14a4a6304..666d69cb4 100644
--- a/vendor/tokio/src/io/mod.rs
+++ b/vendor/tokio/src/io/mod.rs
@@ -1,5 +1,3 @@
-#![cfg_attr(loom, allow(dead_code, unreachable_pub))]
-
 //! Traits, helpers, and type definitions for asynchronous I/O functionality.
 //!
 //! This module is the asynchronous version of `std::io`. Primarily, it
@@ -132,19 +130,23 @@
 //! other words, these types must never block the thread, and instead the
 //! current task is notified when the I/O resource is ready.
 //!
-//! ## Conversion to and from Sink/Stream
+//! ## Conversion to and from Stream/Sink
+//!
+//! It is often convenient to encapsulate the reading and writing of bytes in a
+//! [`Stream`] or [`Sink`] of data.
+//!
+//! Tokio provides simple wrappers for converting [`AsyncRead`] to [`Stream`]
+//! and vice-versa in the [tokio-util] crate, see [`ReaderStream`] and
+//! [`StreamReader`].
 //!
-//! It is often convenient to encapsulate the reading and writing of
-//! bytes and instead work with a [`Sink`] or [`Stream`] of some data
-//! type that is encoded as bytes and/or decoded from bytes. Tokio
-//! provides some utility traits in the [tokio-util] crate that
-//! abstract the asynchronous buffering that is required and allows
-//! you to write [`Encoder`] and [`Decoder`] functions working with a
-//! buffer of bytes, and then use that ["codec"] to transform anything
-//! that implements [`AsyncRead`] and [`AsyncWrite`] into a `Sink`/`Stream` of
-//! your structured data.
+//! There are also utility traits that abstract the asynchronous buffering
+//! necessary to write your own adaptors for encoding and decoding bytes to/from
+//! your structured data, allowing to transform something that implements
+//! [`AsyncRead`]/[`AsyncWrite`] into a [`Stream`]/[`Sink`], see [`Decoder`] and
+//! [`Encoder`] in the [tokio-util::codec] module.
 //!
-//! [tokio-util]: https://docs.rs/tokio-util/0.6/tokio_util/codec/index.html
+//! [tokio-util]: https://docs.rs/tokio-util
+//! [tokio-util::codec]: https://docs.rs/tokio-util/latest/tokio_util/codec/index.html
 //!
 //! # Standard input and output
 //!
@@ -169,9 +171,11 @@
 //! [`AsyncWrite`]: trait@AsyncWrite
 //! [`AsyncReadExt`]: trait@AsyncReadExt
 //! [`AsyncWriteExt`]: trait@AsyncWriteExt
-//! ["codec"]: https://docs.rs/tokio-util/0.6/tokio_util/codec/index.html
-//! [`Encoder`]: https://docs.rs/tokio-util/0.6/tokio_util/codec/trait.Encoder.html
-//! [`Decoder`]: https://docs.rs/tokio-util/0.6/tokio_util/codec/trait.Decoder.html
+//! ["codec"]: https://docs.rs/tokio-util/latest/tokio_util/codec/index.html
+//! [`Encoder`]: https://docs.rs/tokio-util/latest/tokio_util/codec/trait.Encoder.html
+//! [`Decoder`]: https://docs.rs/tokio-util/latest/tokio_util/codec/trait.Decoder.html
+//! [`ReaderStream`]: https://docs.rs/tokio-util/latest/tokio_util/io/struct.ReaderStream.html
+//! [`StreamReader`]: https://docs.rs/tokio-util/latest/tokio_util/io/struct.StreamReader.html
 //! [`Error`]: struct@Error
 //! [`ErrorKind`]: enum@ErrorKind
 //! [`Result`]: type@Result
@@ -180,6 +184,12 @@
 //! [`Sink`]: https://docs.rs/futures/0.3/futures/sink/trait.Sink.html
 //! [`Stream`]: https://docs.rs/futures/0.3/futures/stream/trait.Stream.html
 //! [`Write`]: std::io::Write
+
+#![cfg_attr(
+    not(all(feature = "rt", feature = "net")),
+    allow(dead_code, unused_imports)
+)]
+
 cfg_io_blocking! {
     pub(crate) mod blocking;
 }
@@ -205,18 +215,31 @@ pub use self::read_buf::ReadBuf;
 pub use std::io::{Error, ErrorKind, Result, SeekFrom};
 
 cfg_io_driver_impl! {
-    pub(crate) mod driver;
+    pub(crate) mod interest;
+    pub(crate) mod ready;
 
     cfg_net! {
-        pub use driver::{Interest, Ready};
+        pub use interest::Interest;
+        pub use ready::Ready;
     }
 
+    #[cfg_attr(tokio_wasi, allow(unused_imports))]
     mod poll_evented;
 
     #[cfg(not(loom))]
+    #[cfg_attr(tokio_wasi, allow(unused_imports))]
     pub(crate) use poll_evented::PollEvented;
 }
 
+cfg_aio! {
+    /// BSD-specific I/O types.
+    pub mod bsd {
+        mod poll_aio;
+
+        pub use poll_aio::{Aio, AioEvent, AioSource};
+    }
+}
+
 cfg_net_unix! {
     mod async_fd;
 
diff --git a/vendor/tokio/src/io/poll_evented.rs b/vendor/tokio/src/io/poll_evented.rs
index a31e6db7b..875ad7e0d 100644
--- a/vendor/tokio/src/io/poll_evented.rs
+++ b/vendor/tokio/src/io/poll_evented.rs
@@ -1,16 +1,19 @@
-use crate::io::driver::{Handle, Interest, Registration};
+use crate::io::interest::Interest;
+use crate::runtime::io::Registration;
+use crate::runtime::scheduler;
 
 use mio::event::Source;
 use std::fmt;
 use std::io;
 use std::ops::Deref;
+use std::panic::{RefUnwindSafe, UnwindSafe};
 
 cfg_io_driver! {
     /// Associates an I/O resource that implements the [`std::io::Read`] and/or
     /// [`std::io::Write`] traits with the reactor that drives it.
     ///
     /// `PollEvented` uses [`Registration`] internally to take a type that
-    /// implements [`mio::event::Source`] as well as [`std::io::Read`] and or
+    /// implements [`mio::event::Source`] as well as [`std::io::Read`] and/or
     /// [`std::io::Write`] and associate it with a reactor that will drive it.
     ///
     /// Once the [`mio::event::Source`] type is wrapped by `PollEvented`, it can be
@@ -40,13 +43,12 @@ cfg_io_driver! {
     /// [`poll_read_ready`] again will also indicate read readiness.
     ///
     /// When the operation is attempted and is unable to succeed due to the I/O
-    /// resource not being ready, the caller must call `clear_read_ready` or
-    /// `clear_write_ready`. This clears the readiness state until a new
-    /// readiness event is received.
+    /// resource not being ready, the caller must call [`clear_readiness`].
+    /// This clears the readiness state until a new readiness event is received.
     ///
     /// This allows the caller to implement additional functions. For example,
     /// [`TcpListener`] implements poll_accept by using [`poll_read_ready`] and
-    /// `clear_read_ready`.
+    /// [`clear_readiness`].
     ///
     /// ## Platform-specific events
     ///
@@ -57,6 +59,7 @@ cfg_io_driver! {
     /// [`AsyncRead`]: crate::io::AsyncRead
     /// [`AsyncWrite`]: crate::io::AsyncWrite
     /// [`TcpListener`]: crate::net::TcpListener
+    /// [`clear_readiness`]: Registration::clear_readiness
     /// [`poll_read_ready`]: Registration::poll_read_ready
     /// [`poll_write_ready`]: Registration::poll_write_ready
     pub(crate) struct PollEvented<E: Source> {
@@ -70,6 +73,9 @@ cfg_io_driver! {
 impl<E: Source> PollEvented<E> {
     /// Creates a new `PollEvented` associated with the default reactor.
     ///
+    /// The returned `PollEvented` has readable and writable interests. For more control, use
+    /// [`Self::new_with_interest`].
+    ///
     /// # Panics
     ///
     /// This function panics if thread-local runtime is not set.
@@ -77,6 +83,7 @@ impl<E: Source> PollEvented<E> {
     /// The runtime is usually set implicitly when this function is called
     /// from a future driven by a tokio runtime, otherwise runtime can be set
     /// explicitly with [`Runtime::enter`](crate::runtime::Runtime::enter) function.
+    #[track_caller]
     #[cfg_attr(feature = "signal", allow(unused))]
     pub(crate) fn new(io: E) -> io::Result<Self> {
         PollEvented::new_with_interest(io, Interest::READABLE | Interest::WRITABLE)
@@ -97,15 +104,17 @@ impl<E: Source> PollEvented<E> {
     /// a future driven by a tokio runtime, otherwise runtime can be set
     /// explicitly with [`Runtime::enter`](crate::runtime::Runtime::enter)
     /// function.
+    #[track_caller]
     #[cfg_attr(feature = "signal", allow(unused))]
     pub(crate) fn new_with_interest(io: E, interest: Interest) -> io::Result<Self> {
-        Self::new_with_interest_and_handle(io, interest, Handle::current())
+        Self::new_with_interest_and_handle(io, interest, scheduler::Handle::current())
     }
 
+    #[track_caller]
     pub(crate) fn new_with_interest_and_handle(
         mut io: E,
         interest: Interest,
-        handle: Handle,
+        handle: scheduler::Handle,
     ) -> io::Result<Self> {
         let registration = Registration::new_with_interest_and_handle(&mut io, interest, handle)?;
         Ok(Self {
@@ -114,17 +123,13 @@ impl<E: Source> PollEvented<E> {
         })
     }
 
-    /// Returns a reference to the registration
-    #[cfg(any(
-        feature = "net",
-        all(unix, feature = "process"),
-        all(unix, feature = "signal"),
-    ))]
+    /// Returns a reference to the registration.
+    #[cfg(any(feature = "net"))]
     pub(crate) fn registration(&self) -> &Registration {
         &self.registration
     }
 
-    /// Deregister the inner io from the registration and returns a Result containing the inner io
+    /// Deregisters the inner io from the registration and returns a Result containing the inner io.
     #[cfg(any(feature = "net", feature = "process"))]
     pub(crate) fn into_inner(mut self) -> io::Result<E> {
         let mut inner = self.io.take().unwrap(); // As io shouldn't ever be None, just unwrap here.
@@ -134,7 +139,7 @@ impl<E: Source> PollEvented<E> {
 }
 
 feature! {
-    #![any(feature = "net", feature = "process")]
+    #![any(feature = "net", all(unix, feature = "process"))]
 
     use crate::io::ReadBuf;
     use std::task::{Context, Poll};
@@ -151,16 +156,32 @@ feature! {
         {
             use std::io::Read;
 
-            let n = ready!(self.registration.poll_read_io(cx, || {
+            loop {
+                let evt = ready!(self.registration.poll_read_ready(cx))?;
+
                 let b = &mut *(buf.unfilled_mut() as *mut [std::mem::MaybeUninit<u8>] as *mut [u8]);
-                self.io.as_ref().unwrap().read(b)
-            }))?;
-
-            // Safety: We trust `TcpStream::read` to have filled up `n` bytes in the
-            // buffer.
-            buf.assume_init(n);
-            buf.advance(n);
-            Poll::Ready(Ok(()))
+                let len = b.len();
+
+                match self.io.as_ref().unwrap().read(b) {
+                    Ok(n) => {
+                        // if we read a partially full buffer, this is sufficient on unix to show
+                        // that the socket buffer has been drained
+                        if n > 0 && (!cfg!(windows) && n < len) {
+                            self.registration.clear_readiness(evt);
+                        }
+
+                        // Safety: We trust `TcpStream::read` to have filled up `n` bytes in the
+                        // buffer.
+                        buf.assume_init(n);
+                        buf.advance(n);
+                        return Poll::Ready(Ok(()));
+                    },
+                    Err(e) if e.kind() == io::ErrorKind::WouldBlock => {
+                        self.registration.clear_readiness(evt);
+                    }
+                    Err(e) => return Poll::Ready(Err(e)),
+                }
+            }
         }
 
         pub(crate) fn poll_write<'a>(&'a self, cx: &mut Context<'_>, buf: &[u8]) -> Poll<io::Result<usize>>
@@ -168,10 +189,29 @@ feature! {
             &'a E: io::Write + 'a,
         {
             use std::io::Write;
-            self.registration.poll_write_io(cx, || self.io.as_ref().unwrap().write(buf))
+
+            loop {
+                let evt = ready!(self.registration.poll_write_ready(cx))?;
+
+                match self.io.as_ref().unwrap().write(buf) {
+                    Ok(n) => {
+                        // if we write only part of our buffer, this is sufficient on unix to show
+                        // that the socket buffer is full
+                        if n > 0 && (!cfg!(windows) && n < buf.len()) {
+                            self.registration.clear_readiness(evt);
+                        }
+
+                        return Poll::Ready(Ok(n));
+                    },
+                    Err(e) if e.kind() == io::ErrorKind::WouldBlock => {
+                        self.registration.clear_readiness(evt);
+                    }
+                    Err(e) => return Poll::Ready(Err(e)),
+                }
+            }
         }
 
-        #[cfg(feature = "net")]
+        #[cfg(any(feature = "net", feature = "process"))]
         pub(crate) fn poll_write_vectored<'a>(
             &'a self,
             cx: &mut Context<'_>,
@@ -186,6 +226,10 @@ feature! {
     }
 }
 
+impl<E: Source> UnwindSafe for PollEvented<E> {}
+
+impl<E: Source> RefUnwindSafe for PollEvented<E> {}
+
 impl<E: Source> Deref for PollEvented<E> {
     type Target = E;
 
diff --git a/vendor/tokio/src/io/read_buf.rs b/vendor/tokio/src/io/read_buf.rs
index ad58cbe75..283d96e30 100644
--- a/vendor/tokio/src/io/read_buf.rs
+++ b/vendor/tokio/src/io/read_buf.rs
@@ -1,9 +1,5 @@
-// This lint claims ugly casting is somehow safer than transmute, but there's
-// no evidence that is the case. Shush.
-#![allow(clippy::transmute_ptr_to_ptr)]
-
 use std::fmt;
-use std::mem::{self, MaybeUninit};
+use std::mem::MaybeUninit;
 
 /// A wrapper around a byte buffer that is incrementally filled and initialized.
 ///
@@ -35,7 +31,7 @@ impl<'a> ReadBuf<'a> {
     #[inline]
     pub fn new(buf: &'a mut [u8]) -> ReadBuf<'a> {
         let initialized = buf.len();
-        let buf = unsafe { mem::transmute::<&mut [u8], &mut [MaybeUninit<u8>]>(buf) };
+        let buf = unsafe { slice_to_uninit_mut(buf) };
         ReadBuf {
             buf,
             filled: 0,
@@ -67,8 +63,7 @@ impl<'a> ReadBuf<'a> {
         let slice = &self.buf[..self.filled];
         // safety: filled describes how far into the buffer that the
         // user has filled with bytes, so it's been initialized.
-        // TODO: This could use `MaybeUninit::slice_get_ref` when it is stable.
-        unsafe { mem::transmute::<&[MaybeUninit<u8>], &[u8]>(slice) }
+        unsafe { slice_assume_init(slice) }
     }
 
     /// Returns a mutable reference to the filled portion of the buffer.
@@ -77,8 +72,7 @@ impl<'a> ReadBuf<'a> {
         let slice = &mut self.buf[..self.filled];
         // safety: filled describes how far into the buffer that the
         // user has filled with bytes, so it's been initialized.
-        // TODO: This could use `MaybeUninit::slice_get_mut` when it is stable.
-        unsafe { mem::transmute::<&mut [MaybeUninit<u8>], &mut [u8]>(slice) }
+        unsafe { slice_assume_init_mut(slice) }
     }
 
     /// Returns a new `ReadBuf` comprised of the unfilled section up to `n`.
@@ -97,8 +91,7 @@ impl<'a> ReadBuf<'a> {
         let slice = &self.buf[..self.initialized];
         // safety: initialized describes how far into the buffer that the
         // user has at some point initialized with bytes.
-        // TODO: This could use `MaybeUninit::slice_get_ref` when it is stable.
-        unsafe { mem::transmute::<&[MaybeUninit<u8>], &[u8]>(slice) }
+        unsafe { slice_assume_init(slice) }
     }
 
     /// Returns a mutable reference to the initialized portion of the buffer.
@@ -109,15 +102,14 @@ impl<'a> ReadBuf<'a> {
         let slice = &mut self.buf[..self.initialized];
         // safety: initialized describes how far into the buffer that the
         // user has at some point initialized with bytes.
-        // TODO: This could use `MaybeUninit::slice_get_mut` when it is stable.
-        unsafe { mem::transmute::<&mut [MaybeUninit<u8>], &mut [u8]>(slice) }
+        unsafe { slice_assume_init_mut(slice) }
     }
 
     /// Returns a mutable reference to the entire buffer, without ensuring that it has been fully
     /// initialized.
     ///
     /// The elements between 0 and `self.filled().len()` are filled, and those between 0 and
-    /// `self.initialized().len()` are initialized (and so can be transmuted to a `&mut [u8]`).
+    /// `self.initialized().len()` are initialized (and so can be converted to a `&mut [u8]`).
     ///
     /// The caller of this method must ensure that these invariants are upheld. For example, if the
     /// caller initializes some of the uninitialized section of the buffer, it must call
@@ -160,6 +152,7 @@ impl<'a> ReadBuf<'a> {
     ///
     /// Panics if `self.remaining()` is less than `n`.
     #[inline]
+    #[track_caller]
     pub fn initialize_unfilled_to(&mut self, n: usize) -> &mut [u8] {
         assert!(self.remaining() >= n, "n overflows remaining");
 
@@ -178,7 +171,7 @@ impl<'a> ReadBuf<'a> {
         let slice = &mut self.buf[self.filled..end];
         // safety: just above, we checked that the end of the buf has
         // been initialized to some value.
-        unsafe { mem::transmute::<&mut [MaybeUninit<u8>], &mut [u8]>(slice) }
+        unsafe { slice_assume_init_mut(slice) }
     }
 
     /// Returns the number of bytes at the end of the slice that have not yet been filled.
@@ -203,6 +196,7 @@ impl<'a> ReadBuf<'a> {
     ///
     /// Panics if the filled region of the buffer would become larger than the initialized region.
     #[inline]
+    #[track_caller]
     pub fn advance(&mut self, n: usize) {
         let new = self.filled.checked_add(n).expect("filled overflow");
         self.set_filled(new);
@@ -219,6 +213,7 @@ impl<'a> ReadBuf<'a> {
     ///
     /// Panics if the filled region of the buffer would become larger than the initialized region.
     #[inline]
+    #[track_caller]
     pub fn set_filled(&mut self, n: usize) {
         assert!(
             n <= self.initialized,
@@ -249,6 +244,7 @@ impl<'a> ReadBuf<'a> {
     ///
     /// Panics if `self.remaining()` is less than `buf.len()`.
     #[inline]
+    #[track_caller]
     pub fn put_slice(&mut self, buf: &[u8]) {
         assert!(
             self.remaining() >= buf.len(),
@@ -274,6 +270,33 @@ impl<'a> ReadBuf<'a> {
     }
 }
 
+#[cfg(feature = "io-util")]
+#[cfg_attr(docsrs, doc(cfg(feature = "io-util")))]
+unsafe impl<'a> bytes::BufMut for ReadBuf<'a> {
+    fn remaining_mut(&self) -> usize {
+        self.remaining()
+    }
+
+    // SAFETY: The caller guarantees that at least `cnt` unfilled bytes have been initialized.
+    unsafe fn advance_mut(&mut self, cnt: usize) {
+        self.assume_init(cnt);
+        self.advance(cnt);
+    }
+
+    fn chunk_mut(&mut self) -> &mut bytes::buf::UninitSlice {
+        // SAFETY: No region of `unfilled` will be deinitialized because it is
+        // exposed as an `UninitSlice`, whose API guarantees that the memory is
+        // never deinitialized.
+        let unfilled = unsafe { self.unfilled_mut() };
+        let len = unfilled.len();
+        let ptr = unfilled.as_mut_ptr() as *mut u8;
+
+        // SAFETY: The pointer is valid for `len` bytes because it comes from a
+        // slice of that length.
+        unsafe { bytes::buf::UninitSlice::from_raw_parts_mut(ptr, len) }
+    }
+}
+
 impl fmt::Debug for ReadBuf<'_> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_struct("ReadBuf")
@@ -283,3 +306,17 @@ impl fmt::Debug for ReadBuf<'_> {
             .finish()
     }
 }
+
+unsafe fn slice_to_uninit_mut(slice: &mut [u8]) -> &mut [MaybeUninit<u8>] {
+    &mut *(slice as *mut [u8] as *mut [MaybeUninit<u8>])
+}
+
+// TODO: This could use `MaybeUninit::slice_assume_init` when it is stable.
+unsafe fn slice_assume_init(slice: &[MaybeUninit<u8>]) -> &[u8] {
+    &*(slice as *const [MaybeUninit<u8>] as *const [u8])
+}
+
+// TODO: This could use `MaybeUninit::slice_assume_init_mut` when it is stable.
+unsafe fn slice_assume_init_mut(slice: &mut [MaybeUninit<u8>]) -> &mut [u8] {
+    &mut *(slice as *mut [MaybeUninit<u8>] as *mut [u8])
+}
diff --git a/vendor/tokio/src/io/driver/ready.rs b/vendor/tokio/src/io/ready.rs
index 2ac01bdbe..33e2ef0b6 100644
--- a/vendor/tokio/src/io/driver/ready.rs
+++ b/vendor/tokio/src/io/ready.rs
@@ -7,12 +7,14 @@ const READABLE: usize = 0b0_01;
 const WRITABLE: usize = 0b0_10;
 const READ_CLOSED: usize = 0b0_0100;
 const WRITE_CLOSED: usize = 0b0_1000;
+#[cfg(any(target_os = "linux", target_os = "android"))]
+const PRIORITY: usize = 0b1_0000;
 
 /// Describes the readiness state of an I/O resources.
 ///
 /// `Ready` tracks which operation an I/O resource is ready to perform.
 #[cfg_attr(docsrs, doc(cfg(feature = "net")))]
-#[derive(Clone, Copy, PartialEq, PartialOrd)]
+#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
 pub struct Ready(usize);
 
 impl Ready {
@@ -31,13 +33,34 @@ impl Ready {
     /// Returns a `Ready` representing write closed readiness.
     pub const WRITE_CLOSED: Ready = Ready(WRITE_CLOSED);
 
+    /// Returns a `Ready` representing priority readiness.
+    #[cfg(any(target_os = "linux", target_os = "android"))]
+    #[cfg_attr(docsrs, doc(cfg(any(target_os = "linux", target_os = "android"))))]
+    pub const PRIORITY: Ready = Ready(PRIORITY);
+
+    /// Returns a `Ready` representing readiness for all operations.
+    #[cfg(any(target_os = "linux", target_os = "android"))]
+    pub const ALL: Ready = Ready(READABLE | WRITABLE | READ_CLOSED | WRITE_CLOSED | PRIORITY);
+
     /// Returns a `Ready` representing readiness for all operations.
+    #[cfg(not(any(target_os = "linux", target_os = "android")))]
     pub const ALL: Ready = Ready(READABLE | WRITABLE | READ_CLOSED | WRITE_CLOSED);
 
     // Must remain crate-private to avoid adding a public dependency on Mio.
     pub(crate) fn from_mio(event: &mio::event::Event) -> Ready {
         let mut ready = Ready::EMPTY;
 
+        #[cfg(all(target_os = "freebsd", feature = "net"))]
+        {
+            if event.is_aio() {
+                ready |= Ready::READABLE;
+            }
+
+            if event.is_lio() {
+                ready |= Ready::READABLE;
+            }
+        }
+
         if event.is_readable() {
             ready |= Ready::READABLE;
         }
@@ -54,10 +77,17 @@ impl Ready {
             ready |= Ready::WRITE_CLOSED;
         }
 
+        #[cfg(any(target_os = "linux", target_os = "android"))]
+        {
+            if event.is_priority() {
+                ready |= Ready::PRIORITY;
+            }
+        }
+
         ready
     }
 
-    /// Returns true if `Ready` is the empty set
+    /// Returns true if `Ready` is the empty set.
     ///
     /// # Examples
     ///
@@ -71,7 +101,7 @@ impl Ready {
         self == Ready::EMPTY
     }
 
-    /// Returns `true` if the value includes `readable`
+    /// Returns `true` if the value includes `readable`.
     ///
     /// # Examples
     ///
@@ -87,7 +117,7 @@ impl Ready {
         self.contains(Ready::READABLE) || self.is_read_closed()
     }
 
-    /// Returns `true` if the value includes writable `readiness`
+    /// Returns `true` if the value includes writable `readiness`.
     ///
     /// # Examples
     ///
@@ -103,7 +133,7 @@ impl Ready {
         self.contains(Ready::WRITABLE) || self.is_write_closed()
     }
 
-    /// Returns `true` if the value includes read-closed `readiness`
+    /// Returns `true` if the value includes read-closed `readiness`.
     ///
     /// # Examples
     ///
@@ -118,7 +148,7 @@ impl Ready {
         self.contains(Ready::READ_CLOSED)
     }
 
-    /// Returns `true` if the value includes write-closed `readiness`
+    /// Returns `true` if the value includes write-closed `readiness`.
     ///
     /// # Examples
     ///
@@ -133,6 +163,23 @@ impl Ready {
         self.contains(Ready::WRITE_CLOSED)
     }
 
+    /// Returns `true` if the value includes priority `readiness`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::io::Ready;
+    ///
+    /// assert!(!Ready::EMPTY.is_priority());
+    /// assert!(!Ready::WRITABLE.is_priority());
+    /// assert!(Ready::PRIORITY.is_priority());
+    /// ```
+    #[cfg(any(target_os = "linux", target_os = "android"))]
+    #[cfg_attr(docsrs, doc(cfg(any(target_os = "linux", target_os = "android"))))]
+    pub fn is_priority(self) -> bool {
+        self.contains(Ready::PRIORITY)
+    }
+
     /// Returns true if `self` is a superset of `other`.
     ///
     /// `other` may represent more than one readiness operations, in which case
@@ -143,7 +190,7 @@ impl Ready {
         (self & other) == other
     }
 
-    /// Create a `Ready` instance using the given `usize` representation.
+    /// Creates a `Ready` instance using the given `usize` representation.
     ///
     /// The `usize` representation must have been obtained from a call to
     /// `Readiness::as_usize`.
@@ -180,6 +227,12 @@ cfg_io_readiness! {
                 ready |= Ready::WRITE_CLOSED;
             }
 
+            #[cfg(any(target_os = "linux", target_os = "android"))]
+            if interest.is_priority() {
+                ready |= Ready::PRIORITY;
+                ready |= Ready::READ_CLOSED;
+            }
+
             ready
         }
 
@@ -229,11 +282,16 @@ impl ops::Sub<Ready> for Ready {
 
 impl fmt::Debug for Ready {
     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt.debug_struct("Ready")
-            .field("is_readable", &self.is_readable())
+        let mut fmt = fmt.debug_struct("Ready");
+
+        fmt.field("is_readable", &self.is_readable())
             .field("is_writable", &self.is_writable())
             .field("is_read_closed", &self.is_read_closed())
-            .field("is_write_closed", &self.is_write_closed())
-            .finish()
+            .field("is_write_closed", &self.is_write_closed());
+
+        #[cfg(any(target_os = "linux", target_os = "android"))]
+        fmt.field("is_priority", &self.is_priority());
+
+        fmt.finish()
     }
 }
diff --git a/vendor/tokio/src/io/split.rs b/vendor/tokio/src/io/split.rs
index 732eb3b3a..f067b65a8 100644
--- a/vendor/tokio/src/io/split.rs
+++ b/vendor/tokio/src/io/split.rs
@@ -63,7 +63,7 @@ impl<T> ReadHalf<T> {
     /// Checks if this `ReadHalf` and some `WriteHalf` were split from the same
     /// stream.
     pub fn is_pair_of(&self, other: &WriteHalf<T>) -> bool {
-        other.is_pair_of(&self)
+        other.is_pair_of(self)
     }
 
     /// Reunites with a previously split `WriteHalf`.
@@ -74,7 +74,11 @@ impl<T> ReadHalf<T> {
     /// same `split` operation this method will panic.
     /// This can be checked ahead of time by comparing the stream ID
     /// of the two halves.
-    pub fn unsplit(self, wr: WriteHalf<T>) -> T {
+    #[track_caller]
+    pub fn unsplit(self, wr: WriteHalf<T>) -> T
+    where
+        T: Unpin,
+    {
         if self.is_pair_of(&wr) {
             drop(wr);
 
@@ -90,7 +94,7 @@ impl<T> ReadHalf<T> {
 }
 
 impl<T> WriteHalf<T> {
-    /// Check if this `WriteHalf` and some `ReadHalf` were split from the same
+    /// Checks if this `WriteHalf` and some `ReadHalf` were split from the same
     /// stream.
     pub fn is_pair_of(&self, other: &ReadHalf<T>) -> bool {
         Arc::ptr_eq(&self.inner, &other.inner)
diff --git a/vendor/tokio/src/io/stderr.rs b/vendor/tokio/src/io/stderr.rs
index 2f624fba9..2119c6d6c 100644
--- a/vendor/tokio/src/io/stderr.rs
+++ b/vendor/tokio/src/io/stderr.rs
@@ -74,16 +74,43 @@ cfg_io_std! {
 }
 
 #[cfg(unix)]
-impl std::os::unix::io::AsRawFd for Stderr {
-    fn as_raw_fd(&self) -> std::os::unix::io::RawFd {
-        std::io::stderr().as_raw_fd()
+mod sys {
+    #[cfg(not(tokio_no_as_fd))]
+    use std::os::unix::io::{AsFd, BorrowedFd};
+    use std::os::unix::io::{AsRawFd, RawFd};
+
+    use super::Stderr;
+
+    impl AsRawFd for Stderr {
+        fn as_raw_fd(&self) -> RawFd {
+            std::io::stderr().as_raw_fd()
+        }
+    }
+
+    #[cfg(not(tokio_no_as_fd))]
+    impl AsFd for Stderr {
+        fn as_fd(&self) -> BorrowedFd<'_> {
+            unsafe { BorrowedFd::borrow_raw(self.as_raw_fd()) }
+        }
     }
 }
 
-#[cfg(windows)]
-impl std::os::windows::io::AsRawHandle for Stderr {
-    fn as_raw_handle(&self) -> std::os::windows::io::RawHandle {
-        std::io::stderr().as_raw_handle()
+cfg_windows! {
+    #[cfg(not(tokio_no_as_fd))]
+    use crate::os::windows::io::{AsHandle, BorrowedHandle};
+    use crate::os::windows::io::{AsRawHandle, RawHandle};
+
+    impl AsRawHandle for Stderr {
+        fn as_raw_handle(&self) -> RawHandle {
+            std::io::stderr().as_raw_handle()
+        }
+    }
+
+    #[cfg(not(tokio_no_as_fd))]
+    impl AsHandle for Stderr {
+        fn as_handle(&self) -> BorrowedHandle<'_> {
+            unsafe { BorrowedHandle::borrow_raw(self.as_raw_handle()) }
+        }
     }
 }
 
diff --git a/vendor/tokio/src/io/stdin.rs b/vendor/tokio/src/io/stdin.rs
index c9578f17b..04cced425 100644
--- a/vendor/tokio/src/io/stdin.rs
+++ b/vendor/tokio/src/io/stdin.rs
@@ -49,16 +49,43 @@ cfg_io_std! {
 }
 
 #[cfg(unix)]
-impl std::os::unix::io::AsRawFd for Stdin {
-    fn as_raw_fd(&self) -> std::os::unix::io::RawFd {
-        std::io::stdin().as_raw_fd()
+mod sys {
+    #[cfg(not(tokio_no_as_fd))]
+    use std::os::unix::io::{AsFd, BorrowedFd};
+    use std::os::unix::io::{AsRawFd, RawFd};
+
+    use super::Stdin;
+
+    impl AsRawFd for Stdin {
+        fn as_raw_fd(&self) -> RawFd {
+            std::io::stdin().as_raw_fd()
+        }
+    }
+
+    #[cfg(not(tokio_no_as_fd))]
+    impl AsFd for Stdin {
+        fn as_fd(&self) -> BorrowedFd<'_> {
+            unsafe { BorrowedFd::borrow_raw(self.as_raw_fd()) }
+        }
     }
 }
 
-#[cfg(windows)]
-impl std::os::windows::io::AsRawHandle for Stdin {
-    fn as_raw_handle(&self) -> std::os::windows::io::RawHandle {
-        std::io::stdin().as_raw_handle()
+cfg_windows! {
+    #[cfg(not(tokio_no_as_fd))]
+    use crate::os::windows::io::{AsHandle, BorrowedHandle};
+    use crate::os::windows::io::{AsRawHandle, RawHandle};
+
+    impl AsRawHandle for Stdin {
+        fn as_raw_handle(&self) -> RawHandle {
+            std::io::stdin().as_raw_handle()
+        }
+    }
+
+    #[cfg(not(tokio_no_as_fd))]
+    impl AsHandle for Stdin {
+        fn as_handle(&self) -> BorrowedHandle<'_> {
+            unsafe { BorrowedHandle::borrow_raw(self.as_raw_handle()) }
+        }
     }
 }
 
diff --git a/vendor/tokio/src/io/stdio_common.rs b/vendor/tokio/src/io/stdio_common.rs
index 56c4520c6..06da761b8 100644
--- a/vendor/tokio/src/io/stdio_common.rs
+++ b/vendor/tokio/src/io/stdio_common.rs
@@ -7,7 +7,7 @@ use std::task::{Context, Poll};
 /// if buffer contents seems to be utf8. Otherwise it only trims buffer down to MAX_BUF.
 /// That's why, wrapped writer will always receive well-formed utf-8 bytes.
 /// # Other platforms
-/// passes data to `inner` as is
+/// Passes data to `inner` as is.
 #[derive(Debug)]
 pub(crate) struct SplitByUtf8BoundaryIfWindows<W> {
     inner: W,
@@ -42,7 +42,7 @@ where
         // for further code. Since `AsyncWrite` can always shrink
         // buffer at its discretion, excessive (i.e. in tests) shrinking
         // does not break correctness.
-        // 2. If buffer is small, it will not be shrinked.
+        // 2. If buffer is small, it will not be shrunk.
         // That's why, it's "textness" will not change, so we don't have
         // to fixup it.
         if cfg!(not(any(target_os = "windows", test))) || buf.len() <= crate::io::blocking::MAX_BUF
@@ -108,14 +108,13 @@ where
 #[cfg(test)]
 #[cfg(not(loom))]
 mod tests {
+    use crate::io::blocking::MAX_BUF;
     use crate::io::AsyncWriteExt;
     use std::io;
     use std::pin::Pin;
     use std::task::Context;
     use std::task::Poll;
 
-    const MAX_BUF: usize = 16 * 1024;
-
     struct TextMockWriter;
 
     impl crate::io::AsyncWrite for TextMockWriter {
@@ -177,6 +176,7 @@ mod tests {
     }
 
     #[test]
+    #[cfg_attr(miri, ignore)]
     fn test_splitter() {
         let data = str::repeat("█", MAX_BUF);
         let mut wr = super::SplitByUtf8BoundaryIfWindows::new(TextMockWriter);
@@ -190,10 +190,11 @@ mod tests {
     }
 
     #[test]
+    #[cfg_attr(miri, ignore)]
     fn test_pseudo_text() {
         // In this test we write a piece of binary data, whose beginning is
         // text though. We then validate that even in this corner case buffer
-        // was not shrinked too much.
+        // was not shrunk too much.
         let checked_count = super::MAGIC_CONST * super::MAX_BYTES_PER_CHAR;
         let mut data: Vec<u8> = str::repeat("a", checked_count).into();
         data.extend(std::iter::repeat(0b1010_1010).take(MAX_BUF - checked_count + 1));
@@ -212,7 +213,7 @@ mod tests {
             writer.write_history.iter().copied().sum::<usize>(),
             data.len()
         );
-        // Check that at most MAX_BYTES_PER_CHAR + 1 (i.e. 5) bytes were shrinked
+        // Check that at most MAX_BYTES_PER_CHAR + 1 (i.e. 5) bytes were shrunk
         // from the buffer: one because it was outside of MAX_BUF boundary, and
         // up to one "utf8 code point".
         assert!(data.len() - writer.write_history[0] <= super::MAX_BYTES_PER_CHAR + 1);
diff --git a/vendor/tokio/src/io/stdout.rs b/vendor/tokio/src/io/stdout.rs
index a08ed01ee..f52bf5a4b 100644
--- a/vendor/tokio/src/io/stdout.rs
+++ b/vendor/tokio/src/io/stdout.rs
@@ -73,16 +73,43 @@ cfg_io_std! {
 }
 
 #[cfg(unix)]
-impl std::os::unix::io::AsRawFd for Stdout {
-    fn as_raw_fd(&self) -> std::os::unix::io::RawFd {
-        std::io::stdout().as_raw_fd()
+mod sys {
+    #[cfg(not(tokio_no_as_fd))]
+    use std::os::unix::io::{AsFd, BorrowedFd};
+    use std::os::unix::io::{AsRawFd, RawFd};
+
+    use super::Stdout;
+
+    impl AsRawFd for Stdout {
+        fn as_raw_fd(&self) -> RawFd {
+            std::io::stdout().as_raw_fd()
+        }
+    }
+
+    #[cfg(not(tokio_no_as_fd))]
+    impl AsFd for Stdout {
+        fn as_fd(&self) -> BorrowedFd<'_> {
+            unsafe { BorrowedFd::borrow_raw(self.as_raw_fd()) }
+        }
     }
 }
 
-#[cfg(windows)]
-impl std::os::windows::io::AsRawHandle for Stdout {
-    fn as_raw_handle(&self) -> std::os::windows::io::RawHandle {
-        std::io::stdout().as_raw_handle()
+cfg_windows! {
+    #[cfg(not(tokio_no_as_fd))]
+    use crate::os::windows::io::{AsHandle, BorrowedHandle};
+    use crate::os::windows::io::{AsRawHandle, RawHandle};
+
+    impl AsRawHandle for Stdout {
+        fn as_raw_handle(&self) -> RawHandle {
+            std::io::stdout().as_raw_handle()
+        }
+    }
+
+    #[cfg(not(tokio_no_as_fd))]
+    impl AsHandle for Stdout {
+        fn as_handle(&self) -> BorrowedHandle<'_> {
+            unsafe { BorrowedHandle::borrow_raw(self.as_raw_handle()) }
+        }
     }
 }
 
diff --git a/vendor/tokio/src/io/util/async_buf_read_ext.rs b/vendor/tokio/src/io/util/async_buf_read_ext.rs
index 233ac31c4..50ea2d91a 100644
--- a/vendor/tokio/src/io/util/async_buf_read_ext.rs
+++ b/vendor/tokio/src/io/util/async_buf_read_ext.rs
@@ -1,3 +1,4 @@
+use crate::io::util::fill_buf::{fill_buf, FillBuf};
 use crate::io::util::lines::{lines, Lines};
 use crate::io::util::read_line::{read_line, ReadLine};
 use crate::io::util::read_until::{read_until, ReadUntil};
@@ -36,6 +37,18 @@ cfg_io_util! {
         /// [`fill_buf`]: AsyncBufRead::poll_fill_buf
         /// [`ErrorKind::Interrupted`]: std::io::ErrorKind::Interrupted
         ///
+        /// # Cancel safety
+        ///
+        /// If the method is used as the event in a
+        /// [`tokio::select!`](crate::select) statement and some other branch
+        /// completes first, then some data may have been partially read. Any
+        /// partially read bytes are appended to `buf`, and the method can be
+        /// called again to continue reading until `byte`.
+        ///
+        /// This method returns the total number of bytes read. If you cancel
+        /// the call to `read_until` and then call it again to continue reading,
+        /// the counter is reset.
+        ///
         /// # Examples
         ///
         /// [`std::io::Cursor`][`Cursor`] is a type that implements `BufRead`. In
@@ -114,6 +127,30 @@ cfg_io_util! {
         ///
         /// [`read_until`]: AsyncBufReadExt::read_until
         ///
+        /// # Cancel safety
+        ///
+        /// This method is not cancellation safe. If the method is used as the
+        /// event in a [`tokio::select!`](crate::select) statement and some
+        /// other branch completes first, then some data may have been partially
+        /// read, and this data is lost. There are no guarantees regarding the
+        /// contents of `buf` when the call is cancelled. The current
+        /// implementation replaces `buf` with the empty string, but this may
+        /// change in the future.
+        ///
+        /// This function does not behave like [`read_until`] because of the
+        /// requirement that a string contains only valid utf-8. If you need a
+        /// cancellation safe `read_line`, there are three options:
+        ///
+        ///  * Call [`read_until`] with a newline character and manually perform the utf-8 check.
+        ///  * The stream returned by [`lines`] has a cancellation safe
+        ///    [`next_line`] method.
+        ///  * Use [`tokio_util::codec::LinesCodec`][LinesCodec].
+        ///
+        /// [LinesCodec]: https://docs.rs/tokio-util/latest/tokio_util/codec/struct.LinesCodec.html
+        /// [`read_until`]: Self::read_until
+        /// [`lines`]: Self::lines
+        /// [`next_line`]: crate::io::Lines::next_line
+        ///
         /// # Examples
         ///
         /// [`std::io::Cursor`][`Cursor`] is a type that implements
@@ -173,10 +210,11 @@ cfg_io_util! {
         /// [`BufRead::split`](std::io::BufRead::split).
         ///
         /// The stream returned from this function will yield instances of
-        /// [`io::Result`]`<`[`Vec<u8>`]`>`. Each vector returned will *not* have
+        /// [`io::Result`]`<`[`Option`]`<`[`Vec<u8>`]`>>`. Each vector returned will *not* have
         /// the delimiter byte at the end.
         ///
         /// [`io::Result`]: std::io::Result
+        /// [`Option`]: core::option::Option
         /// [`Vec<u8>`]: std::vec::Vec
         ///
         /// # Errors
@@ -206,14 +244,68 @@ cfg_io_util! {
             split(self, byte)
         }
 
+        /// Returns the contents of the internal buffer, filling it with more
+        /// data from the inner reader if it is empty.
+        ///
+        /// This function is a lower-level call. It needs to be paired with the
+        /// [`consume`] method to function properly. When calling this method,
+        /// none of the contents will be "read" in the sense that later calling
+        /// `read` may return the same contents. As such, [`consume`] must be
+        /// called with the number of bytes that are consumed from this buffer
+        /// to ensure that the bytes are never returned twice.
+        ///
+        /// An empty buffer returned indicates that the stream has reached EOF.
+        ///
+        /// Equivalent to:
+        ///
+        /// ```ignore
+        /// async fn fill_buf(&mut self) -> io::Result<&[u8]>;
+        /// ```
+        ///
+        /// # Errors
+        ///
+        /// This function will return an I/O error if the underlying reader was
+        /// read, but returned an error.
+        ///
+        /// [`consume`]: crate::io::AsyncBufReadExt::consume
+        fn fill_buf(&mut self) -> FillBuf<'_, Self>
+        where
+            Self: Unpin,
+        {
+            fill_buf(self)
+        }
+
+        /// Tells this buffer that `amt` bytes have been consumed from the
+        /// buffer, so they should no longer be returned in calls to [`read`].
+        ///
+        /// This function is a lower-level call. It needs to be paired with the
+        /// [`fill_buf`] method to function properly. This function does not
+        /// perform any I/O, it simply informs this object that some amount of
+        /// its buffer, returned from [`fill_buf`], has been consumed and should
+        /// no longer be returned. As such, this function may do odd things if
+        /// [`fill_buf`] isn't called before calling it.
+        ///
+        /// The `amt` must be less than the number of bytes in the buffer
+        /// returned by [`fill_buf`].
+        ///
+        /// [`read`]: crate::io::AsyncReadExt::read
+        /// [`fill_buf`]: crate::io::AsyncBufReadExt::fill_buf
+        fn consume(&mut self, amt: usize)
+        where
+            Self: Unpin,
+        {
+            std::pin::Pin::new(self).consume(amt)
+        }
+
         /// Returns a stream over the lines of this reader.
         /// This method is the async equivalent to [`BufRead::lines`](std::io::BufRead::lines).
         ///
         /// The stream returned from this function will yield instances of
-        /// [`io::Result`]`<`[`String`]`>`. Each string returned will *not* have a newline
+        /// [`io::Result`]`<`[`Option`]`<`[`String`]`>>`. Each string returned will *not* have a newline
         /// byte (the 0xA byte) or CRLF (0xD, 0xA bytes) at the end.
         ///
         /// [`io::Result`]: std::io::Result
+        /// [`Option`]: core::option::Option
         /// [`String`]: String
         ///
         /// # Errors
diff --git a/vendor/tokio/src/io/util/async_read_ext.rs b/vendor/tokio/src/io/util/async_read_ext.rs
index 10f641744..df5445c2c 100644
--- a/vendor/tokio/src/io/util/async_read_ext.rs
+++ b/vendor/tokio/src/io/util/async_read_ext.rs
@@ -2,6 +2,7 @@ use crate::io::util::chain::{chain, Chain};
 use crate::io::util::read::{read, Read};
 use crate::io::util::read_buf::{read_buf, ReadBuf};
 use crate::io::util::read_exact::{read_exact, ReadExact};
+use crate::io::util::read_int::{ReadF32, ReadF32Le, ReadF64, ReadF64Le};
 use crate::io::util::read_int::{
     ReadI128, ReadI128Le, ReadI16, ReadI16Le, ReadI32, ReadI32Le, ReadI64, ReadI64Le, ReadI8,
 };
@@ -691,6 +692,82 @@ cfg_io_util! {
             /// ```
             fn read_i128(&mut self) -> ReadI128;
 
+            /// Reads an 32-bit floating point type in big-endian order from the
+            /// underlying reader.
+            ///
+            /// Equivalent to:
+            ///
+            /// ```ignore
+            /// async fn read_f32(&mut self) -> io::Result<f32>;
+            /// ```
+            ///
+            /// It is recommended to use a buffered reader to avoid excessive
+            /// syscalls.
+            ///
+            /// # Errors
+            ///
+            /// This method returns the same errors as [`AsyncReadExt::read_exact`].
+            ///
+            /// [`AsyncReadExt::read_exact`]: AsyncReadExt::read_exact
+            ///
+            /// # Examples
+            ///
+            /// Read 32-bit floating point type from a `AsyncRead`:
+            ///
+            /// ```rust
+            /// use tokio::io::{self, AsyncReadExt};
+            ///
+            /// use std::io::Cursor;
+            ///
+            /// #[tokio::main]
+            /// async fn main() -> io::Result<()> {
+            ///     let mut reader = Cursor::new(vec![0xff, 0x7f, 0xff, 0xff]);
+            ///
+            ///     assert_eq!(f32::MIN, reader.read_f32().await?);
+            ///     Ok(())
+            /// }
+            /// ```
+            fn read_f32(&mut self) -> ReadF32;
+
+            /// Reads an 64-bit floating point type in big-endian order from the
+            /// underlying reader.
+            ///
+            /// Equivalent to:
+            ///
+            /// ```ignore
+            /// async fn read_f64(&mut self) -> io::Result<f64>;
+            /// ```
+            ///
+            /// It is recommended to use a buffered reader to avoid excessive
+            /// syscalls.
+            ///
+            /// # Errors
+            ///
+            /// This method returns the same errors as [`AsyncReadExt::read_exact`].
+            ///
+            /// [`AsyncReadExt::read_exact`]: AsyncReadExt::read_exact
+            ///
+            /// # Examples
+            ///
+            /// Read 64-bit floating point type from a `AsyncRead`:
+            ///
+            /// ```rust
+            /// use tokio::io::{self, AsyncReadExt};
+            ///
+            /// use std::io::Cursor;
+            ///
+            /// #[tokio::main]
+            /// async fn main() -> io::Result<()> {
+            ///     let mut reader = Cursor::new(vec![
+            ///         0xff, 0xef, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
+            ///     ]);
+            ///
+            ///     assert_eq!(f64::MIN, reader.read_f64().await?);
+            ///     Ok(())
+            /// }
+            /// ```
+            fn read_f64(&mut self) -> ReadF64;
+
             /// Reads an unsigned 16-bit integer in little-endian order from the
             /// underlying reader.
             ///
@@ -997,6 +1074,82 @@ cfg_io_util! {
             /// }
             /// ```
             fn read_i128_le(&mut self) -> ReadI128Le;
+
+            /// Reads an 32-bit floating point type in little-endian order from the
+            /// underlying reader.
+            ///
+            /// Equivalent to:
+            ///
+            /// ```ignore
+            /// async fn read_f32_le(&mut self) -> io::Result<f32>;
+            /// ```
+            ///
+            /// It is recommended to use a buffered reader to avoid excessive
+            /// syscalls.
+            ///
+            /// # Errors
+            ///
+            /// This method returns the same errors as [`AsyncReadExt::read_exact`].
+            ///
+            /// [`AsyncReadExt::read_exact`]: AsyncReadExt::read_exact
+            ///
+            /// # Examples
+            ///
+            /// Read 32-bit floating point type from a `AsyncRead`:
+            ///
+            /// ```rust
+            /// use tokio::io::{self, AsyncReadExt};
+            ///
+            /// use std::io::Cursor;
+            ///
+            /// #[tokio::main]
+            /// async fn main() -> io::Result<()> {
+            ///     let mut reader = Cursor::new(vec![0xff, 0xff, 0x7f, 0xff]);
+            ///
+            ///     assert_eq!(f32::MIN, reader.read_f32_le().await?);
+            ///     Ok(())
+            /// }
+            /// ```
+            fn read_f32_le(&mut self) -> ReadF32Le;
+
+            /// Reads an 64-bit floating point type in little-endian order from the
+            /// underlying reader.
+            ///
+            /// Equivalent to:
+            ///
+            /// ```ignore
+            /// async fn read_f64_le(&mut self) -> io::Result<f64>;
+            /// ```
+            ///
+            /// It is recommended to use a buffered reader to avoid excessive
+            /// syscalls.
+            ///
+            /// # Errors
+            ///
+            /// This method returns the same errors as [`AsyncReadExt::read_exact`].
+            ///
+            /// [`AsyncReadExt::read_exact`]: AsyncReadExt::read_exact
+            ///
+            /// # Examples
+            ///
+            /// Read 64-bit floating point type from a `AsyncRead`:
+            ///
+            /// ```rust
+            /// use tokio::io::{self, AsyncReadExt};
+            ///
+            /// use std::io::Cursor;
+            ///
+            /// #[tokio::main]
+            /// async fn main() -> io::Result<()> {
+            ///     let mut reader = Cursor::new(vec![
+            ///         0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xef, 0xff
+            ///     ]);
+            ///
+            ///     assert_eq!(f64::MIN, reader.read_f64_le().await?);
+            ///     Ok(())
+            /// }
+            /// ```
+            fn read_f64_le(&mut self) -> ReadF64Le;
         }
 
         /// Reads all bytes until EOF in this source, placing them into `buf`.
diff --git a/vendor/tokio/src/io/util/async_seek_ext.rs b/vendor/tokio/src/io/util/async_seek_ext.rs
index 297a4a61a..aadf3a76a 100644
--- a/vendor/tokio/src/io/util/async_seek_ext.rs
+++ b/vendor/tokio/src/io/util/async_seek_ext.rs
@@ -67,6 +67,16 @@ cfg_io_util! {
             seek(self, pos)
         }
 
+        /// Creates a future which will rewind to the beginning of the stream.
+        ///
+        /// This is convenience method, equivalent to `self.seek(SeekFrom::Start(0))`.
+        fn rewind(&mut self) -> Seek<'_, Self>
+        where
+            Self: Unpin,
+        {
+            self.seek(SeekFrom::Start(0))
+        }
+
         /// Creates a future which will return the current seek position from the
         /// start of the stream.
         ///
diff --git a/vendor/tokio/src/io/util/async_write_ext.rs b/vendor/tokio/src/io/util/async_write_ext.rs
index e214321b7..dfdde82f3 100644
--- a/vendor/tokio/src/io/util/async_write_ext.rs
+++ b/vendor/tokio/src/io/util/async_write_ext.rs
@@ -4,6 +4,7 @@ use crate::io::util::write::{write, Write};
 use crate::io::util::write_all::{write_all, WriteAll};
 use crate::io::util::write_all_buf::{write_all_buf, WriteAllBuf};
 use crate::io::util::write_buf::{write_buf, WriteBuf};
+use crate::io::util::write_int::{WriteF32, WriteF32Le, WriteF64, WriteF64Le};
 use crate::io::util::write_int::{
     WriteI128, WriteI128Le, WriteI16, WriteI16Le, WriteI32, WriteI32Le, WriteI64, WriteI64Le,
     WriteI8,
@@ -19,7 +20,7 @@ use std::io::IoSlice;
 use bytes::Buf;
 
 cfg_io_util! {
-    /// Defines numeric writer
+    /// Defines numeric writer.
     macro_rules! write_impl {
         (
             $(
@@ -255,7 +256,7 @@ cfg_io_util! {
             write_buf(self, src)
         }
 
-        /// Attempts to write an entire buffer into this writer
+        /// Attempts to write an entire buffer into this writer.
         ///
         /// Equivalent to:
         ///
@@ -352,9 +353,9 @@ cfg_io_util! {
         ///
         /// #[tokio::main]
         /// async fn main() -> io::Result<()> {
-        ///     let mut buffer = File::create("foo.txt").await?;
+        ///     let mut file = File::create("foo.txt").await?;
         ///
-        ///     buffer.write_all(b"some bytes").await?;
+        ///     file.write_all(b"some bytes").await?;
         ///     Ok(())
         /// }
         /// ```
@@ -405,7 +406,7 @@ cfg_io_util! {
             /// ```
             fn write_u8(&mut self, n: u8) -> WriteU8;
 
-            /// Writes an unsigned 8-bit integer to the underlying writer.
+            /// Writes a signed 8-bit integer to the underlying writer.
             ///
             /// Equivalent to:
             ///
@@ -424,7 +425,7 @@ cfg_io_util! {
             ///
             /// # Examples
             ///
-            /// Write unsigned 8 bit integers to a `AsyncWrite`:
+            /// Write signed 8 bit integers to a `AsyncWrite`:
             ///
             /// ```rust
             /// use tokio::io::{self, AsyncWriteExt};
@@ -433,10 +434,10 @@ cfg_io_util! {
             /// async fn main() -> io::Result<()> {
             ///     let mut writer = Vec::new();
             ///
-            ///     writer.write_u8(2).await?;
-            ///     writer.write_u8(5).await?;
+            ///     writer.write_i8(-2).await?;
+            ///     writer.write_i8(126).await?;
             ///
-            ///     assert_eq!(writer, b"\x02\x05");
+            ///     assert_eq!(writer, b"\xFE\x7E");
             ///     Ok(())
             /// }
             /// ```
@@ -750,6 +751,81 @@ cfg_io_util! {
             /// ```
             fn write_i128(&mut self, n: i128) -> WriteI128;
 
+            /// Writes an 32-bit floating point type in big-endian order to the
+            /// underlying writer.
+            ///
+            /// Equivalent to:
+            ///
+            /// ```ignore
+            /// async fn write_f32(&mut self, n: f32) -> io::Result<()>;
+            /// ```
+            ///
+            /// It is recommended to use a buffered writer to avoid excessive
+            /// syscalls.
+            ///
+            /// # Errors
+            ///
+            /// This method returns the same errors as [`AsyncWriteExt::write_all`].
+            ///
+            /// [`AsyncWriteExt::write_all`]: AsyncWriteExt::write_all
+            ///
+            /// # Examples
+            ///
+            /// Write 32-bit floating point type to a `AsyncWrite`:
+            ///
+            /// ```rust
+            /// use tokio::io::{self, AsyncWriteExt};
+            ///
+            /// #[tokio::main]
+            /// async fn main() -> io::Result<()> {
+            ///     let mut writer = Vec::new();
+            ///
+            ///     writer.write_f32(f32::MIN).await?;
+            ///
+            ///     assert_eq!(writer, vec![0xff, 0x7f, 0xff, 0xff]);
+            ///     Ok(())
+            /// }
+            /// ```
+            fn write_f32(&mut self, n: f32) -> WriteF32;
+
+            /// Writes an 64-bit floating point type in big-endian order to the
+            /// underlying writer.
+            ///
+            /// Equivalent to:
+            ///
+            /// ```ignore
+            /// async fn write_f64(&mut self, n: f64) -> io::Result<()>;
+            /// ```
+            ///
+            /// It is recommended to use a buffered writer to avoid excessive
+            /// syscalls.
+            ///
+            /// # Errors
+            ///
+            /// This method returns the same errors as [`AsyncWriteExt::write_all`].
+            ///
+            /// [`AsyncWriteExt::write_all`]: AsyncWriteExt::write_all
+            ///
+            /// # Examples
+            ///
+            /// Write 64-bit floating point type to a `AsyncWrite`:
+            ///
+            /// ```rust
+            /// use tokio::io::{self, AsyncWriteExt};
+            ///
+            /// #[tokio::main]
+            /// async fn main() -> io::Result<()> {
+            ///     let mut writer = Vec::new();
+            ///
+            ///     writer.write_f64(f64::MIN).await?;
+            ///
+            ///     assert_eq!(writer, vec![
+            ///         0xff, 0xef, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
+            ///     ]);
+            ///     Ok(())
+            /// }
+            /// ```
+            fn write_f64(&mut self, n: f64) -> WriteF64;
 
             /// Writes an unsigned 16-bit integer in little-endian order to the
             /// underlying writer.
@@ -1058,6 +1134,82 @@ cfg_io_util! {
             /// }
             /// ```
             fn write_i128_le(&mut self, n: i128) -> WriteI128Le;
+
+            /// Writes an 32-bit floating point type in little-endian order to the
+            /// underlying writer.
+            ///
+            /// Equivalent to:
+            ///
+            /// ```ignore
+            /// async fn write_f32_le(&mut self, n: f32) -> io::Result<()>;
+            /// ```
+            ///
+            /// It is recommended to use a buffered writer to avoid excessive
+            /// syscalls.
+            ///
+            /// # Errors
+            ///
+            /// This method returns the same errors as [`AsyncWriteExt::write_all`].
+            ///
+            /// [`AsyncWriteExt::write_all`]: AsyncWriteExt::write_all
+            ///
+            /// # Examples
+            ///
+            /// Write 32-bit floating point type to a `AsyncWrite`:
+            ///
+            /// ```rust
+            /// use tokio::io::{self, AsyncWriteExt};
+            ///
+            /// #[tokio::main]
+            /// async fn main() -> io::Result<()> {
+            ///     let mut writer = Vec::new();
+            ///
+            ///     writer.write_f32_le(f32::MIN).await?;
+            ///
+            ///     assert_eq!(writer, vec![0xff, 0xff, 0x7f, 0xff]);
+            ///     Ok(())
+            /// }
+            /// ```
+            fn write_f32_le(&mut self, n: f32) -> WriteF32Le;
+
+            /// Writes an 64-bit floating point type in little-endian order to the
+            /// underlying writer.
+            ///
+            /// Equivalent to:
+            ///
+            /// ```ignore
+            /// async fn write_f64_le(&mut self, n: f64) -> io::Result<()>;
+            /// ```
+            ///
+            /// It is recommended to use a buffered writer to avoid excessive
+            /// syscalls.
+            ///
+            /// # Errors
+            ///
+            /// This method returns the same errors as [`AsyncWriteExt::write_all`].
+            ///
+            /// [`AsyncWriteExt::write_all`]: AsyncWriteExt::write_all
+            ///
+            /// # Examples
+            ///
+            /// Write 64-bit floating point type to a `AsyncWrite`:
+            ///
+            /// ```rust
+            /// use tokio::io::{self, AsyncWriteExt};
+            ///
+            /// #[tokio::main]
+            /// async fn main() -> io::Result<()> {
+            ///     let mut writer = Vec::new();
+            ///
+            ///     writer.write_f64_le(f64::MIN).await?;
+            ///
+            ///     assert_eq!(writer, vec![
+            ///         0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xef, 0xff
+            ///     ]);
+            ///     Ok(())
+            /// }
+            /// ```
+            fn write_f64_le(&mut self, n: f64) -> WriteF64Le;
         }
 
         /// Flushes this output stream, ensuring that all intermediately buffered
diff --git a/vendor/tokio/src/io/util/buf_reader.rs b/vendor/tokio/src/io/util/buf_reader.rs
index 7cfd46ce0..60879c0fd 100644
--- a/vendor/tokio/src/io/util/buf_reader.rs
+++ b/vendor/tokio/src/io/util/buf_reader.rs
@@ -155,7 +155,7 @@ pub(super) enum SeekState {
     Pending,
 }
 
-/// Seek to an offset, in bytes, in the underlying reader.
+/// Seeks to an offset, in bytes, in the underlying reader.
 ///
 /// The position used for seeking with `SeekFrom::Current(_)` is the
 /// position the underlying reader would be at if the `BufReader` had no
@@ -204,7 +204,6 @@ impl<R: AsyncRead + AsyncSeek> AsyncSeek for BufReader<R> {
                     self.as_mut()
                         .get_pin_mut()
                         .start_seek(SeekFrom::Current(offset))?;
-                    self.as_mut().get_pin_mut().poll_complete(cx)?
                 } else {
                     // seek backwards by our remainder, and then by the offset
                     self.as_mut()
@@ -221,8 +220,8 @@ impl<R: AsyncRead + AsyncSeek> AsyncSeek for BufReader<R> {
                     self.as_mut()
                         .get_pin_mut()
                         .start_seek(SeekFrom::Current(n))?;
-                    self.as_mut().get_pin_mut().poll_complete(cx)?
                 }
+                self.as_mut().get_pin_mut().poll_complete(cx)?
             }
             SeekState::PendingOverflowed(n) => {
                 if self.as_mut().get_pin_mut().poll_complete(cx)?.is_pending() {
diff --git a/vendor/tokio/src/io/util/copy.rs b/vendor/tokio/src/io/util/copy.rs
index 3cd425b34..55861244f 100644
--- a/vendor/tokio/src/io/util/copy.rs
+++ b/vendor/tokio/src/io/util/copy.rs
@@ -8,6 +8,7 @@ use std::task::{Context, Poll};
 #[derive(Debug)]
 pub(super) struct CopyBuffer {
     read_done: bool,
+    need_flush: bool,
     pos: usize,
     cap: usize,
     amt: u64,
@@ -18,10 +19,56 @@ impl CopyBuffer {
     pub(super) fn new() -> Self {
         Self {
             read_done: false,
+            need_flush: false,
             pos: 0,
             cap: 0,
             amt: 0,
-            buf: vec![0; 2048].into_boxed_slice(),
+            buf: vec![0; super::DEFAULT_BUF_SIZE].into_boxed_slice(),
+        }
+    }
+
+    fn poll_fill_buf<R>(
+        &mut self,
+        cx: &mut Context<'_>,
+        reader: Pin<&mut R>,
+    ) -> Poll<io::Result<()>>
+    where
+        R: AsyncRead + ?Sized,
+    {
+        let me = &mut *self;
+        let mut buf = ReadBuf::new(&mut me.buf);
+        buf.set_filled(me.cap);
+
+        let res = reader.poll_read(cx, &mut buf);
+        if let Poll::Ready(Ok(_)) = res {
+            let filled_len = buf.filled().len();
+            me.read_done = me.cap == filled_len;
+            me.cap = filled_len;
+        }
+        res
+    }
+
+    fn poll_write_buf<R, W>(
+        &mut self,
+        cx: &mut Context<'_>,
+        mut reader: Pin<&mut R>,
+        mut writer: Pin<&mut W>,
+    ) -> Poll<io::Result<usize>>
+    where
+        R: AsyncRead + ?Sized,
+        W: AsyncWrite + ?Sized,
+    {
+        let me = &mut *self;
+        match writer.as_mut().poll_write(cx, &me.buf[me.pos..me.cap]) {
+            Poll::Pending => {
+                // Top up the buffer towards full if we can read a bit more
+                // data - this should improve the chances of a large write
+                if !me.read_done && me.cap < me.buf.len() {
+                    ready!(me.poll_fill_buf(cx, reader.as_mut()))?;
+                }
+                Poll::Pending
+            }
+            res => res,
         }
     }
 
@@ -39,22 +86,28 @@ impl CopyBuffer {
             // If our buffer is empty, then we need to read some data to
             // continue.
             if self.pos == self.cap && !self.read_done {
-                let me = &mut *self;
-                let mut buf = ReadBuf::new(&mut me.buf);
-                ready!(reader.as_mut().poll_read(cx, &mut buf))?;
-                let n = buf.filled().len();
-                if n == 0 {
-                    self.read_done = true;
-                } else {
-                    self.pos = 0;
-                    self.cap = n;
+                self.pos = 0;
+                self.cap = 0;
+
+                match self.poll_fill_buf(cx, reader.as_mut()) {
+                    Poll::Ready(Ok(_)) => (),
+                    Poll::Ready(Err(err)) => return Poll::Ready(Err(err)),
+                    Poll::Pending => {
+                        // Try flushing when the reader has no progress to avoid deadlock
+                        // when the reader depends on buffered writer.
+                        if self.need_flush {
+                            ready!(writer.as_mut().poll_flush(cx))?;
+                            self.need_flush = false;
+                        }
+
+                        return Poll::Pending;
+                    }
                 }
             }
 
             // If our buffer has some data, let's write it out!
             while self.pos < self.cap {
-                let me = &mut *self;
-                let i = ready!(writer.as_mut().poll_write(cx, &me.buf[me.pos..me.cap]))?;
+                let i = ready!(self.poll_write_buf(cx, reader.as_mut(), writer.as_mut()))?;
                 if i == 0 {
                     return Poll::Ready(Err(io::Error::new(
                         io::ErrorKind::WriteZero,
@@ -63,9 +116,18 @@ impl CopyBuffer {
                 } else {
                     self.pos += i;
                     self.amt += i as u64;
+                    self.need_flush = true;
                 }
             }
 
+            // If pos larger than cap, this loop will never stop.
+            // In particular, user's wrong poll_write implementation returning
+            // incorrect written length may lead to thread blocking.
+            debug_assert!(
+                self.pos <= self.cap,
+                "writer returned length larger than input slice"
+            );
+
             // If we've written all the data and we've seen EOF, flush out the
             // data and finish the transfer.
             if self.pos == self.cap && self.read_done {
@@ -91,14 +153,22 @@ cfg_io_util! {
     ///
     /// This function returns a future that will continuously read data from
     /// `reader` and then write it into `writer` in a streaming fashion until
-    /// `reader` returns EOF.
+    /// `reader` returns EOF or fails.
     ///
     /// On success, the total number of bytes that were copied from `reader` to
     /// `writer` is returned.
     ///
     /// This is an asynchronous version of [`std::io::copy`][std].
     ///
+    /// A heap-allocated copy buffer with 8 KB is created to take data from the
+    /// reader to the writer, check [`copy_buf`] if you want an alternative for
+    /// [`AsyncBufRead`]. You can use `copy_buf` with [`BufReader`] to change the
+    /// buffer capacity.
+    ///
     /// [std]: std::io::copy
+    /// [`copy_buf`]: crate::io::copy_buf
+    /// [`AsyncBufRead`]: crate::io::AsyncBufRead
+    /// [`BufReader`]: crate::io::BufReader
     ///
     /// # Errors
     ///
diff --git a/vendor/tokio/src/io/util/copy_bidirectional.rs b/vendor/tokio/src/io/util/copy_bidirectional.rs
index c93060b36..e1a7db127 100644
--- a/vendor/tokio/src/io/util/copy_bidirectional.rs
+++ b/vendor/tokio/src/io/util/copy_bidirectional.rs
@@ -1,8 +1,8 @@
 use super::copy::CopyBuffer;
 
+use crate::future::poll_fn;
 use crate::io::{AsyncRead, AsyncWrite};
 
-use std::future::Future;
 use std::io;
 use std::pin::Pin;
 use std::task::{Context, Poll};
@@ -13,13 +13,6 @@ enum TransferState {
     Done(u64),
 }
 
-struct CopyBidirectional<'a, A: ?Sized, B: ?Sized> {
-    a: &'a mut A,
-    b: &'a mut B,
-    a_to_b: TransferState,
-    b_to_a: TransferState,
-}
-
 fn transfer_one_direction<A, B>(
     cx: &mut Context<'_>,
     state: &mut TransferState,
@@ -48,35 +41,6 @@ where
         }
     }
 }
-
-impl<'a, A, B> Future for CopyBidirectional<'a, A, B>
-where
-    A: AsyncRead + AsyncWrite + Unpin + ?Sized,
-    B: AsyncRead + AsyncWrite + Unpin + ?Sized,
-{
-    type Output = io::Result<(u64, u64)>;
-
-    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
-        // Unpack self into mut refs to each field to avoid borrow check issues.
-        let CopyBidirectional {
-            a,
-            b,
-            a_to_b,
-            b_to_a,
-        } = &mut *self;
-
-        let a_to_b = transfer_one_direction(cx, a_to_b, &mut *a, &mut *b)?;
-        let b_to_a = transfer_one_direction(cx, b_to_a, &mut *b, &mut *a)?;
-
-        // It is not a problem if ready! returns early because transfer_one_direction for the
-        // other direction will keep returning TransferState::Done(count) in future calls to poll
-        let a_to_b = ready!(a_to_b);
-        let b_to_a = ready!(b_to_a);
-
-        Poll::Ready(Ok((a_to_b, b_to_a)))
-    }
-}
-
 /// Copies data in both directions between `a` and `b`.
 ///
 /// This function returns a future that will read from both streams,
@@ -110,11 +74,18 @@ where
     A: AsyncRead + AsyncWrite + Unpin + ?Sized,
     B: AsyncRead + AsyncWrite + Unpin + ?Sized,
 {
-    CopyBidirectional {
-        a,
-        b,
-        a_to_b: TransferState::Running(CopyBuffer::new()),
-        b_to_a: TransferState::Running(CopyBuffer::new()),
-    }
+    let mut a_to_b = TransferState::Running(CopyBuffer::new());
+    let mut b_to_a = TransferState::Running(CopyBuffer::new());
+    poll_fn(|cx| {
+        let a_to_b = transfer_one_direction(cx, &mut a_to_b, a, b)?;
+        let b_to_a = transfer_one_direction(cx, &mut b_to_a, b, a)?;
+
+        // It is not a problem if ready! returns early because transfer_one_direction for the
+        // other direction will keep returning TransferState::Done(count) in future calls to poll
+        let a_to_b = ready!(a_to_b);
+        let b_to_a = ready!(b_to_a);
+
+        Poll::Ready(Ok((a_to_b, b_to_a)))
+    })
     .await
 }
diff --git a/vendor/tokio/src/io/util/copy_buf.rs b/vendor/tokio/src/io/util/copy_buf.rs
index 6831580b4..c23fc9a2b 100644
--- a/vendor/tokio/src/io/util/copy_buf.rs
+++ b/vendor/tokio/src/io/util/copy_buf.rs
@@ -24,11 +24,17 @@ cfg_io_util! {
     ///
     /// This function returns a future that will continuously read data from
     /// `reader` and then write it into `writer` in a streaming fashion until
-    /// `reader` returns EOF.
+    /// `reader` returns EOF or fails.
     ///
     /// On success, the total number of bytes that were copied from `reader` to
     /// `writer` is returned.
     ///
+    /// This is a [`tokio::io::copy`] alternative for [`AsyncBufRead`] readers
+    /// with no extra buffer allocation, since [`AsyncBufRead`] allow access
+    /// to the reader's inner buffer.
+    ///
+    /// [`tokio::io::copy`]: crate::io::copy
+    /// [`AsyncBufRead`]: crate::io::AsyncBufRead
     ///
     /// # Errors
     ///
diff --git a/vendor/tokio/src/io/util/empty.rs b/vendor/tokio/src/io/util/empty.rs
index f964d18e6..b96fabbaa 100644
--- a/vendor/tokio/src/io/util/empty.rs
+++ b/vendor/tokio/src/io/util/empty.rs
@@ -50,16 +50,20 @@ impl AsyncRead for Empty {
     #[inline]
     fn poll_read(
         self: Pin<&mut Self>,
-        _: &mut Context<'_>,
+        cx: &mut Context<'_>,
         _: &mut ReadBuf<'_>,
     ) -> Poll<io::Result<()>> {
+        ready!(crate::trace::trace_leaf(cx));
+        ready!(poll_proceed_and_make_progress(cx));
         Poll::Ready(Ok(()))
     }
 }
 
 impl AsyncBufRead for Empty {
     #[inline]
-    fn poll_fill_buf(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<io::Result<&[u8]>> {
+    fn poll_fill_buf(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<&[u8]>> {
+        ready!(crate::trace::trace_leaf(cx));
+        ready!(poll_proceed_and_make_progress(cx));
         Poll::Ready(Ok(&[]))
     }
 
@@ -73,6 +77,20 @@ impl fmt::Debug for Empty {
     }
 }
 
+cfg_coop! {
+    fn poll_proceed_and_make_progress(cx: &mut Context<'_>) -> Poll<()> {
+        let coop = ready!(crate::runtime::coop::poll_proceed(cx));
+        coop.made_progress();
+        Poll::Ready(())
+    }
+}
+
+cfg_not_coop! {
+    fn poll_proceed_and_make_progress(_: &mut Context<'_>) -> Poll<()> {
+        Poll::Ready(())
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
diff --git a/vendor/tokio/src/io/util/fill_buf.rs b/vendor/tokio/src/io/util/fill_buf.rs
new file mode 100644
index 000000000..bb07c766e
--- /dev/null
+++ b/vendor/tokio/src/io/util/fill_buf.rs
@@ -0,0 +1,59 @@
+use crate::io::AsyncBufRead;
+
+use pin_project_lite::pin_project;
+use std::future::Future;
+use std::io;
+use std::marker::PhantomPinned;
+use std::pin::Pin;
+use std::task::{Context, Poll};
+
+pin_project! {
+    /// Future for the [`fill_buf`](crate::io::AsyncBufReadExt::fill_buf) method.
+    #[derive(Debug)]
+    #[must_use = "futures do nothing unless you `.await` or poll them"]
+    pub struct FillBuf<'a, R: ?Sized> {
+        reader: Option<&'a mut R>,
+        #[pin]
+        _pin: PhantomPinned,
+    }
+}
+
+pub(crate) fn fill_buf<R>(reader: &mut R) -> FillBuf<'_, R>
+where
+    R: AsyncBufRead + ?Sized + Unpin,
+{
+    FillBuf {
+        reader: Some(reader),
+        _pin: PhantomPinned,
+    }
+}
+
+impl<'a, R: AsyncBufRead + ?Sized + Unpin> Future for FillBuf<'a, R> {
+    type Output = io::Result<&'a [u8]>;
+
+    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        let me = self.project();
+
+        let reader = me.reader.take().expect("Polled after completion.");
+        match Pin::new(&mut *reader).poll_fill_buf(cx) {
+            Poll::Ready(Ok(slice)) => unsafe {
+                // Safety: This is necessary only due to a limitation in the
+                // borrow checker. Once Rust starts using the polonius borrow
+                // checker, this can be simplified.
+                //
+                // The safety of this transmute relies on the fact that the
+                // value of `reader` is `None` when we return in this branch.
+                // Otherwise the caller could poll us again after
+                // completion, and access the mutable reference while the
+                // returned immutable reference still exists.
+                let slice = std::mem::transmute::<&[u8], &'a [u8]>(slice);
+                Poll::Ready(Ok(slice))
+            },
+            Poll::Ready(Err(err)) => Poll::Ready(Err(err)),
+            Poll::Pending => {
+                *me.reader = Some(reader);
+                Poll::Pending
+            }
+        }
+    }
+}
diff --git a/vendor/tokio/src/io/util/lines.rs b/vendor/tokio/src/io/util/lines.rs
index d02a4538a..717f633f9 100644
--- a/vendor/tokio/src/io/util/lines.rs
+++ b/vendor/tokio/src/io/util/lines.rs
@@ -8,7 +8,7 @@ use std::pin::Pin;
 use std::task::{Context, Poll};
 
 pin_project! {
-    /// Read lines from an [`AsyncBufRead`].
+    /// Reads lines from an [`AsyncBufRead`].
     ///
     /// A `Lines` can be turned into a `Stream` with [`LinesStream`].
     ///
@@ -47,6 +47,10 @@ where
 {
     /// Returns the next line in the stream.
     ///
+    /// # Cancel safety
+    ///
+    /// This method is cancellation safe.
+    ///
     /// # Examples
     ///
     /// ```
@@ -68,12 +72,12 @@ where
         poll_fn(|cx| Pin::new(&mut *self).poll_next_line(cx)).await
     }
 
-    /// Obtain a mutable reference to the underlying reader
+    /// Obtains a mutable reference to the underlying reader.
     pub fn get_mut(&mut self) -> &mut R {
         &mut self.reader
     }
 
-    /// Obtain a reference to the underlying reader
+    /// Obtains a reference to the underlying reader.
     pub fn get_ref(&mut self) -> &R {
         &self.reader
     }
@@ -102,11 +106,9 @@ where
     ///
     /// When the method returns `Poll::Pending`, the `Waker` in the provided
     /// `Context` is scheduled to receive a wakeup when more bytes become
-    /// available on the underlying IO resource.
-    ///
-    /// Note that on multiple calls to `poll_next_line`, only the `Waker` from
-    /// the `Context` passed to the most recent call is scheduled to receive a
-    /// wakeup.
+    /// available on the underlying IO resource.  Note that on multiple calls to
+    /// `poll_next_line`, only the `Waker` from the `Context` passed to the most
+    /// recent call is scheduled to receive a wakeup.
     pub fn poll_next_line(
         self: Pin<&mut Self>,
         cx: &mut Context<'_>,
diff --git a/vendor/tokio/src/io/util/mem.rs b/vendor/tokio/src/io/util/mem.rs
index 4eefe7b26..5b404c219 100644
--- a/vendor/tokio/src/io/util/mem.rs
+++ b/vendor/tokio/src/io/util/mem.rs
@@ -177,10 +177,8 @@ impl Pipe {
             waker.wake();
         }
     }
-}
 
-impl AsyncRead for Pipe {
-    fn poll_read(
+    fn poll_read_internal(
         mut self: Pin<&mut Self>,
         cx: &mut task::Context<'_>,
         buf: &mut ReadBuf<'_>,
@@ -204,10 +202,8 @@ impl AsyncRead for Pipe {
             Poll::Pending
         }
     }
-}
 
-impl AsyncWrite for Pipe {
-    fn poll_write(
+    fn poll_write_internal(
         mut self: Pin<&mut Self>,
         cx: &mut task::Context<'_>,
         buf: &[u8],
@@ -228,6 +224,66 @@ impl AsyncWrite for Pipe {
         }
         Poll::Ready(Ok(len))
     }
+}
+
+impl AsyncRead for Pipe {
+    cfg_coop! {
+        fn poll_read(
+            self: Pin<&mut Self>,
+            cx: &mut task::Context<'_>,
+            buf: &mut ReadBuf<'_>,
+        ) -> Poll<std::io::Result<()>> {
+            ready!(crate::trace::trace_leaf(cx));
+            let coop = ready!(crate::runtime::coop::poll_proceed(cx));
+
+            let ret = self.poll_read_internal(cx, buf);
+            if ret.is_ready() {
+                coop.made_progress();
+            }
+            ret
+        }
+    }
+
+    cfg_not_coop! {
+        fn poll_read(
+            self: Pin<&mut Self>,
+            cx: &mut task::Context<'_>,
+            buf: &mut ReadBuf<'_>,
+        ) -> Poll<std::io::Result<()>> {
+            ready!(crate::trace::trace_leaf(cx));
+            self.poll_read_internal(cx, buf)
+        }
+    }
+}
+
+impl AsyncWrite for Pipe {
+    cfg_coop! {
+        fn poll_write(
+            self: Pin<&mut Self>,
+            cx: &mut task::Context<'_>,
+            buf: &[u8],
+        ) -> Poll<std::io::Result<usize>> {
+            ready!(crate::trace::trace_leaf(cx));
+            let coop = ready!(crate::runtime::coop::poll_proceed(cx));
+
+            let ret = self.poll_write_internal(cx, buf);
+            if ret.is_ready() {
+                coop.made_progress();
+            }
+            ret
+        }
+    }
+
+    cfg_not_coop! {
+        fn poll_write(
+            self: Pin<&mut Self>,
+            cx: &mut task::Context<'_>,
+            buf: &[u8],
+        ) -> Poll<std::io::Result<usize>> {
+            ready!(crate::trace::trace_leaf(cx));
+            self.poll_write_internal(cx, buf)
+        }
+    }
 
     fn poll_flush(self: Pin<&mut Self>, _: &mut task::Context<'_>) -> Poll<std::io::Result<()>> {
         Poll::Ready(Ok(()))
diff --git a/vendor/tokio/src/io/util/mod.rs b/vendor/tokio/src/io/util/mod.rs
index fd3dd0dfc..21199d0be 100644
--- a/vendor/tokio/src/io/util/mod.rs
+++ b/vendor/tokio/src/io/util/mod.rs
@@ -49,6 +49,7 @@ cfg_io_util! {
     mod read_exact;
     mod read_int;
     mod read_line;
+    mod fill_buf;
 
     mod read_to_end;
     mod vec_with_initialized;
diff --git a/vendor/tokio/src/io/util/read.rs b/vendor/tokio/src/io/util/read.rs
index edc9d5a9e..a1f9c8a05 100644
--- a/vendor/tokio/src/io/util/read.rs
+++ b/vendor/tokio/src/io/util/read.rs
@@ -48,7 +48,7 @@ where
 
     fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<usize>> {
         let me = self.project();
-        let mut buf = ReadBuf::new(*me.buf);
+        let mut buf = ReadBuf::new(me.buf);
         ready!(Pin::new(me.reader).poll_read(cx, &mut buf))?;
         Poll::Ready(Ok(buf.filled().len()))
     }
diff --git a/vendor/tokio/src/io/util/read_exact.rs b/vendor/tokio/src/io/util/read_exact.rs
index 1e8150eb2..dbdd58bae 100644
--- a/vendor/tokio/src/io/util/read_exact.rs
+++ b/vendor/tokio/src/io/util/read_exact.rs
@@ -51,13 +51,13 @@ where
     type Output = io::Result<usize>;
 
     fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<usize>> {
-        let mut me = self.project();
+        let me = self.project();
 
         loop {
             // if our buffer is empty, then we need to read some data to continue.
             let rem = me.buf.remaining();
             if rem != 0 {
-                ready!(Pin::new(&mut *me.reader).poll_read(cx, &mut me.buf))?;
+                ready!(Pin::new(&mut *me.reader).poll_read(cx, me.buf))?;
                 if me.buf.remaining() == rem {
                     return Err(eof()).into();
                 }
diff --git a/vendor/tokio/src/io/util/read_int.rs b/vendor/tokio/src/io/util/read_int.rs
index 5b9fb7bf7..164dcf596 100644
--- a/vendor/tokio/src/io/util/read_int.rs
+++ b/vendor/tokio/src/io/util/read_int.rs
@@ -142,6 +142,9 @@ reader!(ReadI32, i32, get_i32);
 reader!(ReadI64, i64, get_i64);
 reader!(ReadI128, i128, get_i128);
 
+reader!(ReadF32, f32, get_f32);
+reader!(ReadF64, f64, get_f64);
+
 reader!(ReadU16Le, u16, get_u16_le);
 reader!(ReadU32Le, u32, get_u32_le);
 reader!(ReadU64Le, u64, get_u64_le);
@@ -151,3 +154,6 @@ reader!(ReadI16Le, i16, get_i16_le);
 reader!(ReadI32Le, i32, get_i32_le);
 reader!(ReadI64Le, i64, get_i64_le);
 reader!(ReadI128Le, i128, get_i128_le);
+
+reader!(ReadF32Le, f32, get_f32_le);
+reader!(ReadF64Le, f64, get_f64_le);
diff --git a/vendor/tokio/src/io/util/read_to_end.rs b/vendor/tokio/src/io/util/read_to_end.rs
index f4a564d7d..8edba2a17 100644
--- a/vendor/tokio/src/io/util/read_to_end.rs
+++ b/vendor/tokio/src/io/util/read_to_end.rs
@@ -1,11 +1,11 @@
 use crate::io::util::vec_with_initialized::{into_read_buf_parts, VecU8, VecWithInitialized};
-use crate::io::AsyncRead;
+use crate::io::{AsyncRead, ReadBuf};
 
 use pin_project_lite::pin_project;
 use std::future::Future;
 use std::io;
 use std::marker::PhantomPinned;
-use std::mem;
+use std::mem::{self, MaybeUninit};
 use std::pin::Pin;
 use std::task::{Context, Poll};
 
@@ -67,16 +67,47 @@ fn poll_read_to_end<V: VecU8, R: AsyncRead + ?Sized>(
     // has 4 bytes while still making large reads if the reader does have a ton
     // of data to return. Simply tacking on an extra DEFAULT_BUF_SIZE space every
     // time is 4,500 times (!) slower than this if the reader has a very small
-    // amount of data to return.
-    buf.reserve(32);
+    // amount of data to return. When the vector is full with its starting
+    // capacity, we first try to read into a small buffer to see if we reached
+    // an EOF. This only happens when the starting capacity is >= NUM_BYTES, since
+    // we allocate at least NUM_BYTES each time. This avoids the unnecessary
+    // allocation that we attempt before reading into the vector.
+
+    const NUM_BYTES: usize = 32;
+    let try_small_read = buf.try_small_read_first(NUM_BYTES);
 
     // Get a ReadBuf into the vector.
-    let mut read_buf = buf.get_read_buf();
+    let mut read_buf;
+    let poll_result;
+
+    let n = if try_small_read {
+        // Read some bytes using a small read.
+        let mut small_buf: [MaybeUninit<u8>; NUM_BYTES] = [MaybeUninit::uninit(); NUM_BYTES];
+        let mut small_read_buf = ReadBuf::uninit(&mut small_buf);
+        poll_result = read.poll_read(cx, &mut small_read_buf);
+        let to_write = small_read_buf.filled();
+
+        // Ensure we have enough space to fill our vector with what we read.
+        read_buf = buf.get_read_buf();
+        if to_write.len() > read_buf.remaining() {
+            buf.reserve(NUM_BYTES);
+            read_buf = buf.get_read_buf();
+        }
+        read_buf.put_slice(to_write);
+
+        to_write.len()
+    } else {
+        // Ensure we have enough space for reading.
+        buf.reserve(NUM_BYTES);
+        read_buf = buf.get_read_buf();
+
+        // Read data directly into vector.
+        let filled_before = read_buf.filled().len();
+        poll_result = read.poll_read(cx, &mut read_buf);
 
-    let filled_before = read_buf.filled().len();
-    let poll_result = read.poll_read(cx, &mut read_buf);
-    let filled_after = read_buf.filled().len();
-    let n = filled_after - filled_before;
+        // Compute the number of bytes read.
+        read_buf.filled().len() - filled_before
+    };
 
     // Update the length of the vector using the result of poll_read.
     let read_buf_parts = into_read_buf_parts(read_buf);
@@ -87,11 +118,11 @@ fn poll_read_to_end<V: VecU8, R: AsyncRead + ?Sized>(
             // In this case, nothing should have been read. However we still
             // update the vector in case the poll_read call initialized parts of
             // the vector's unused capacity.
-            debug_assert_eq!(filled_before, filled_after);
+            debug_assert_eq!(n, 0);
             Poll::Pending
         }
         Poll::Ready(Err(err)) => {
-            debug_assert_eq!(filled_before, filled_after);
+            debug_assert_eq!(n, 0);
             Poll::Ready(Err(err))
         }
         Poll::Ready(Ok(())) => Poll::Ready(Ok(n)),
diff --git a/vendor/tokio/src/io/util/read_until.rs b/vendor/tokio/src/io/util/read_until.rs
index 90a0e8a18..fb6fb22d9 100644
--- a/vendor/tokio/src/io/util/read_until.rs
+++ b/vendor/tokio/src/io/util/read_until.rs
@@ -1,4 +1,5 @@
 use crate::io::AsyncBufRead;
+use crate::util::memchr;
 
 use pin_project_lite::pin_project;
 use std::future::Future;
diff --git a/vendor/tokio/src/io/util/take.rs b/vendor/tokio/src/io/util/take.rs
index b5e90c936..df2f61b9e 100644
--- a/vendor/tokio/src/io/util/take.rs
+++ b/vendor/tokio/src/io/util/take.rs
@@ -86,7 +86,11 @@ impl<R: AsyncRead> AsyncRead for Take<R> {
 
         let me = self.project();
         let mut b = buf.take(*me.limit_ as usize);
+
+        let buf_ptr = b.filled().as_ptr();
         ready!(me.inner.poll_read(cx, &mut b))?;
+        assert_eq!(b.filled().as_ptr(), buf_ptr);
+
         let n = b.filled().len();
 
         // We need to update the original ReadBuf
diff --git a/vendor/tokio/src/io/util/vec_with_initialized.rs b/vendor/tokio/src/io/util/vec_with_initialized.rs
index 208cc939c..f527492dc 100644
--- a/vendor/tokio/src/io/util/vec_with_initialized.rs
+++ b/vendor/tokio/src/io/util/vec_with_initialized.rs
@@ -1,19 +1,18 @@
 use crate::io::ReadBuf;
 use std::mem::MaybeUninit;
 
-mod private {
-    pub trait Sealed {}
-
-    impl Sealed for Vec<u8> {}
-    impl Sealed for &mut Vec<u8> {}
-}
+/// Something that looks like a `Vec<u8>`.
+///
+/// # Safety
+///
+/// The implementor must guarantee that the vector returned by the
+/// `as_mut` and `as_mut` methods do not change from one call to
+/// another.
+pub(crate) unsafe trait VecU8: AsRef<Vec<u8>> + AsMut<Vec<u8>> {}
 
-/// A sealed trait that constrains the generic type parameter in `VecWithInitialized<V>`.  That struct's safety relies
-/// on certain invariants upheld by `Vec<u8>`.
-pub(crate) trait VecU8: AsMut<Vec<u8>> + private::Sealed {}
+unsafe impl VecU8 for Vec<u8> {}
+unsafe impl VecU8 for &mut Vec<u8> {}
 
-impl VecU8 for Vec<u8> {}
-impl VecU8 for &mut Vec<u8> {}
 /// This struct wraps a `Vec<u8>` or `&mut Vec<u8>`, combining it with a
 /// `num_initialized`, which keeps track of the number of initialized bytes
 /// in the unused capacity.
@@ -29,6 +28,7 @@ pub(crate) struct VecWithInitialized<V> {
     // The number of initialized bytes in the vector.
     // Always between `vec.len()` and `vec.capacity()`.
     num_initialized: usize,
+    starting_capacity: usize,
 }
 
 impl VecWithInitialized<Vec<u8>> {
@@ -48,6 +48,7 @@ where
         // to its length are initialized.
         Self {
             num_initialized: vec.as_mut().len(),
+            starting_capacity: vec.as_ref().capacity(),
             vec,
         }
     }
@@ -64,8 +65,8 @@ where
     }
 
     #[cfg(feature = "io-util")]
-    pub(crate) fn is_empty(&mut self) -> bool {
-        self.vec.as_mut().is_empty()
+    pub(crate) fn is_empty(&self) -> bool {
+        self.vec.as_ref().is_empty()
     }
 
     pub(crate) fn get_read_buf<'a>(&'a mut self) -> ReadBuf<'a> {
@@ -112,6 +113,15 @@ where
             vec.set_len(parts.len);
         }
     }
+
+    // Returns a boolean telling the caller to try reading into a small local buffer first if true.
+    // Doing so would avoid overallocating when vec is filled to capacity and we reached EOF.
+    pub(crate) fn try_small_read_first(&self, num_bytes: usize) -> bool {
+        let vec = self.vec.as_ref();
+        vec.capacity() - vec.len() < num_bytes
+            && self.starting_capacity == vec.capacity()
+            && self.starting_capacity >= num_bytes
+    }
 }
 
 pub(crate) struct ReadBufParts {
diff --git a/vendor/tokio/src/io/util/write_all.rs b/vendor/tokio/src/io/util/write_all.rs
index e59d41e4d..abd3e39d3 100644
--- a/vendor/tokio/src/io/util/write_all.rs
+++ b/vendor/tokio/src/io/util/write_all.rs
@@ -42,7 +42,7 @@ where
         while !me.buf.is_empty() {
             let n = ready!(Pin::new(&mut *me.writer).poll_write(cx, me.buf))?;
             {
-                let (_, rest) = mem::replace(&mut *me.buf, &[]).split_at(n);
+                let (_, rest) = mem::take(&mut *me.buf).split_at(n);
                 *me.buf = rest;
             }
             if n == 0 {
diff --git a/vendor/tokio/src/io/util/write_int.rs b/vendor/tokio/src/io/util/write_int.rs
index 13bc191ed..63cd49126 100644
--- a/vendor/tokio/src/io/util/write_int.rs
+++ b/vendor/tokio/src/io/util/write_int.rs
@@ -135,6 +135,9 @@ writer!(WriteI32, i32, put_i32);
 writer!(WriteI64, i64, put_i64);
 writer!(WriteI128, i128, put_i128);
 
+writer!(WriteF32, f32, put_f32);
+writer!(WriteF64, f64, put_f64);
+
 writer!(WriteU16Le, u16, put_u16_le);
 writer!(WriteU32Le, u32, put_u32_le);
 writer!(WriteU64Le, u64, put_u64_le);
@@ -144,3 +147,6 @@ writer!(WriteI16Le, i16, put_i16_le);
 writer!(WriteI32Le, i32, put_i32_le);
 writer!(WriteI64Le, i64, put_i64_le);
 writer!(WriteI128Le, i128, put_i128_le);
+
+writer!(WriteF32Le, f32, put_f32_le);
+writer!(WriteF64Le, f64, put_f64_le);
diff --git a/vendor/tokio/src/lib.rs b/vendor/tokio/src/lib.rs
index c74b9643f..c712945a4 100644
--- a/vendor/tokio/src/lib.rs
+++ b/vendor/tokio/src/lib.rs
@@ -1,7 +1,9 @@
 #![allow(
     clippy::cognitive_complexity,
     clippy::large_enum_variant,
-    clippy::needless_doctest_main
+    clippy::module_inception,
+    clippy::needless_doctest_main,
+    clippy::declare_interior_mutable_const
 )]
 #![warn(
     missing_debug_implementations,
@@ -10,12 +12,13 @@
     unreachable_pub
 )]
 #![deny(unused_must_use)]
-#![cfg_attr(docsrs, deny(broken_intra_doc_links))]
 #![doc(test(
     no_crate_inject,
     attr(deny(warnings, rust_2018_idioms), allow(dead_code, unused_variables))
 ))]
 #![cfg_attr(docsrs, feature(doc_cfg))]
+#![cfg_attr(docsrs, allow(unused_attributes))]
+#![cfg_attr(loom, allow(dead_code, unreachable_pub))]
 
 //! A runtime for writing reliable network applications without compromising speed.
 //!
@@ -114,7 +117,7 @@
 //! The [`tokio::sync`] module contains synchronization primitives to use when
 //! needing to communicate or share data. These include:
 //!
-//! * channels ([`oneshot`], [`mpsc`], and [`watch`]), for sending values
+//! * channels ([`oneshot`], [`mpsc`], [`watch`], and [`broadcast`]), for sending values
 //!   between tasks,
 //! * a non-blocking [`Mutex`], for controlling access to a shared, mutable
 //!   value,
@@ -130,6 +133,7 @@
 //! [`oneshot`]: crate::sync::oneshot
 //! [`mpsc`]: crate::sync::mpsc
 //! [`watch`]: crate::sync::watch
+//! [`broadcast`]: crate::sync::broadcast
 //!
 //! The [`tokio::time`] module provides utilities for tracking time and
 //! scheduling work. This includes functions for setting [timeouts][timeout] for
@@ -151,7 +155,7 @@
 //! provide the functionality you need.
 //!
 //! Using the runtime requires the "rt" or "rt-multi-thread" feature flags, to
-//! enable the basic [single-threaded scheduler][rt] and the [thread-pool
+//! enable the current-thread [single-threaded scheduler][rt] and the [multi-thread
 //! scheduler][rt-multi-thread], respectively. See the [`runtime` module
 //! documentation][rt-features] for details. In addition, the "macros" feature
 //! flag enables the `#[tokio::main]` and `#[tokio::test]` attributes.
@@ -160,8 +164,8 @@
 //! [`tokio::runtime`]: crate::runtime
 //! [`Builder`]: crate::runtime::Builder
 //! [`Runtime`]: crate::runtime::Runtime
-//! [rt]: runtime/index.html#basic-scheduler
-//! [rt-multi-thread]: runtime/index.html#threaded-scheduler
+//! [rt]: runtime/index.html#current-thread-scheduler
+//! [rt-multi-thread]: runtime/index.html#multi-thread-scheduler
 //! [rt-features]: runtime/index.html#runtime-scheduler
 //!
 //! ## CPU-bound tasks and blocking code
@@ -170,12 +174,15 @@
 //! swapping the currently running task on each thread. However, this kind of
 //! swapping can only happen at `.await` points, so code that spends a long time
 //! without reaching an `.await` will prevent other tasks from running. To
-//! combat this, Tokio provides two kinds of threads: Core threads and blocking
-//! threads. The core threads are where all asynchronous code runs, and Tokio
-//! will by default spawn one for each CPU core. The blocking threads are
-//! spawned on demand, can be used to run blocking code that would otherwise
-//! block other tasks from running and are kept alive when not used for a certain
-//! amount of time which can be configured with [`thread_keep_alive`].
+//! combat this, Tokio provides two kinds of threads: Core threads and blocking threads.
+//!
+//! The core threads are where all asynchronous code runs, and Tokio will by default
+//! spawn one for each CPU core. You can use the environment variable `TOKIO_WORKER_THREADS`
+//! to override the default value.
+//!
+//! The blocking threads are spawned on demand, can be used to run blocking code
+//! that would otherwise block other tasks from running and are kept alive when
+//! not used for a certain amount of time which can be configured with [`thread_keep_alive`].
 //! Since it is not possible for Tokio to swap out blocking tasks, like it
 //! can do with asynchronous code, the upper limit on the number of blocking
 //! threads is very large. These limits can be configured on the [`Builder`].
@@ -204,9 +211,15 @@
 //! ```
 //!
 //! If your code is CPU-bound and you wish to limit the number of threads used
-//! to run it, you should run it on another thread pool such as [rayon]. You
-//! can use an [`oneshot`] channel to send the result back to Tokio when the
-//! rayon task finishes.
+//! to run it, you should use a separate thread pool dedicated to CPU bound tasks.
+//! For example, you could consider using the [rayon] library for CPU-bound
+//! tasks. It is also possible to create an extra Tokio runtime dedicated to
+//! CPU-bound tasks, but if you do this, you should be careful that the extra
+//! runtime runs _only_ CPU-bound tasks, as IO-bound tasks on that runtime
+//! will behave poorly.
+//!
+//! Hint: If using rayon, you can use a [`oneshot`] channel to send the result back
+//! to Tokio when the rayon task finishes.
 //!
 //! [rayon]: https://docs.rs/rayon
 //! [`oneshot`]: crate::sync::oneshot
@@ -301,14 +314,15 @@
 //! Beware though that this will pull in many extra dependencies that you may not
 //! need.
 //!
-//! - `full`: Enables all Tokio public API features listed below except `test-util`.
-//! - `rt`: Enables `tokio::spawn`, the basic (current thread) scheduler,
+//! - `full`: Enables all features listed below except `test-util` and `tracing`.
+//! - `rt`: Enables `tokio::spawn`, the current-thread scheduler,
 //!         and non-scheduler utilities.
 //! - `rt-multi-thread`: Enables the heavier, multi-threaded, work-stealing scheduler.
 //! - `io-util`: Enables the IO based `Ext` traits.
 //! - `io-std`: Enable `Stdout`, `Stdin` and `Stderr` types.
-//! - `net`: Enables `tokio::net` types such as `TcpStream`, `UnixStream` and `UdpSocket`,
-//!          as well as (on Unix-like systems) `AsyncFd`
+//! - `net`: Enables `tokio::net` types such as `TcpStream`, `UnixStream` and
+//!          `UdpSocket`, as well as (on Unix-like systems) `AsyncFd` and (on
+//!          FreeBSD) `PollAio`.
 //! - `time`: Enables `tokio::time` types and allows the schedulers to enable
 //!           the built in timer.
 //! - `process`: Enables `tokio::process` types.
@@ -317,30 +331,176 @@
 //! - `signal`: Enables all `tokio::signal` types.
 //! - `fs`: Enables `tokio::fs` types.
 //! - `test-util`: Enables testing based infrastructure for the Tokio runtime.
+//! - `parking_lot`: As a potential optimization, use the _parking_lot_ crate's
+//!                  synchronization primitives internally. Also, this
+//!                  dependency is necessary to construct some of our primitives
+//!                  in a const context. MSRV may increase according to the
+//!                  _parking_lot_ release in use.
 //!
 //! _Note: `AsyncRead` and `AsyncWrite` traits do not require any features and are
 //! always available._
 //!
-//! ### Internal features
+//! ### Unstable features
 //!
-//! These features do not expose any new API, but influence internal
-//! implementation aspects of Tokio, and can pull in additional
-//! dependencies.
+//! Some feature flags are only available when specifying the `tokio_unstable` flag:
 //!
-//! - `parking_lot`: As a potential optimization, use the _parking_lot_ crate's
-//! synchronization primitives internally. MSRV may increase according to the
-//! _parking_lot_ release in use.
+//! - `tracing`: Enables tracing events.
 //!
-//! ### Unstable features
+//! Likewise, some parts of the API are only available with the same flag:
 //!
-//! These feature flags enable **unstable** features. The public API may break in 1.x
-//! releases. To enable these features, the `--cfg tokio_unstable` must be passed to
-//! `rustc` when compiling. This is easiest done using the `RUSTFLAGS` env variable:
-//! `RUSTFLAGS="--cfg tokio_unstable"`.
+//! - [`task::Builder`]
+//! - Some methods on [`task::JoinSet`]
+//! - [`runtime::RuntimeMetrics`]
+//! - [`runtime::Builder::unhandled_panic`]
+//! - [`task::Id`]
 //!
-//! - `tracing`: Enables tracing events.
+//! This flag enables **unstable** features. The public API of these features
+//! may break in 1.x releases. To enable these features, the `--cfg
+//! tokio_unstable` argument must be passed to `rustc` when compiling. This
+//! serves to explicitly opt-in to features which may break semver conventions,
+//! since Cargo [does not yet directly support such opt-ins][unstable features].
+//!
+//! You can specify it in your project's `.cargo/config.toml` file:
+//!
+//! ```toml
+//! [build]
+//! rustflags = ["--cfg", "tokio_unstable"]
+//! ```
+//!
+//! Alternatively, you can specify it with an environment variable:
+//!
+//! ```sh
+//! ## Many *nix shells:
+//! export RUSTFLAGS="--cfg tokio_unstable"
+//! cargo build
+//! ```
+//!
+//! ```powershell
+//! ## Windows PowerShell:
+//! $Env:RUSTFLAGS="--cfg tokio_unstable"
+//! cargo build
+//! ```
 //!
+//! [unstable features]: https://internals.rust-lang.org/t/feature-request-unstable-opt-in-non-transitive-crate-features/16193#why-not-a-crate-feature-2
 //! [feature flags]: https://doc.rust-lang.org/cargo/reference/manifest.html#the-features-section
+//!
+//! ## Supported platforms
+//!
+//! Tokio currently guarantees support for the following platforms:
+//!
+//!  * Linux
+//!  * Windows
+//!  * Android (API level 21)
+//!  * macOS
+//!  * iOS
+//!  * FreeBSD
+//!
+//! Tokio will continue to support these platforms in the future. However,
+//! future releases may change requirements such as the minimum required libc
+//! version on Linux, the API level on Android, or the supported FreeBSD
+//! release.
+//!
+//! Beyond the above platforms, Tokio is intended to work on all platforms
+//! supported by the mio crate. You can find a longer list [in mio's
+//! documentation][mio-supported]. However, these additional platforms may
+//! become unsupported in the future.
+//!
+//! Note that Wine is considered to be a different platform from Windows. See
+//! mio's documentation for more information on Wine support.
+//!
+//! [mio-supported]: https://crates.io/crates/mio#platforms
+//!
+//! ### WASM support
+//!
+//! Tokio has some limited support for the WASM platform. Without the
+//! `tokio_unstable` flag, the following features are supported:
+//!
+//!  * `sync`
+//!  * `macros`
+//!  * `io-util`
+//!  * `rt`
+//!  * `time`
+//!
+//! Enabling any other feature (including `full`) will cause a compilation
+//! failure.
+//!
+//! The `time` module will only work on WASM platforms that have support for
+//! timers (e.g. wasm32-wasi). The timing functions will panic if used on a WASM
+//! platform that does not support timers.
+//!
+//! Note also that if the runtime becomes indefinitely idle, it will panic
+//! immediately instead of blocking forever. On platforms that don't support
+//! time, this means that the runtime can never be idle in any way.
+//!
+//! ### Unstable WASM support
+//!
+//! Tokio also has unstable support for some additional WASM features. This
+//! requires the use of the `tokio_unstable` flag.
+//!
+//! Using this flag enables the use of `tokio::net` on the wasm32-wasi target.
+//! However, not all methods are available on the networking types as WASI
+//! currently does not support the creation of new sockets from within WASM.
+//! Because of this, sockets must currently be created via the `FromRawFd`
+//! trait.
+
+// Test that pointer width is compatible. This asserts that e.g. usize is at
+// least 32 bits, which a lot of components in Tokio currently assumes.
+//
+// TODO: improve once we have MSRV access to const eval to make more flexible.
+#[cfg(not(any(
+    target_pointer_width = "32",
+    target_pointer_width = "64",
+    target_pointer_width = "128"
+)))]
+compile_error! {
+    "Tokio requires the platform pointer width to be 32, 64, or 128 bits"
+}
+
+// Ensure that our build script has correctly set cfg flags for wasm.
+//
+// Each condition is written all(a, not(b)). This should be read as
+// "if a, then we must also have b".
+#[cfg(any(
+    all(target_arch = "wasm32", not(tokio_wasm)),
+    all(target_arch = "wasm64", not(tokio_wasm)),
+    all(target_family = "wasm", not(tokio_wasm)),
+    all(target_os = "wasi", not(tokio_wasm)),
+    all(target_os = "wasi", not(tokio_wasi)),
+    all(target_os = "wasi", tokio_wasm_not_wasi),
+    all(tokio_wasm, not(any(target_arch = "wasm32", target_arch = "wasm64"))),
+    all(tokio_wasm_not_wasi, not(tokio_wasm)),
+    all(tokio_wasi, not(tokio_wasm))
+))]
+compile_error!("Tokio's build script has incorrectly detected wasm.");
+
+#[cfg(all(
+    not(tokio_unstable),
+    tokio_wasm,
+    any(
+        feature = "fs",
+        feature = "io-std",
+        feature = "net",
+        feature = "process",
+        feature = "rt-multi-thread",
+        feature = "signal"
+    )
+))]
+compile_error!("Only features sync,macros,io-util,rt,time are supported on wasm.");
+
+#[cfg(all(not(tokio_unstable), tokio_taskdump))]
+compile_error!("The `tokio_taskdump` feature requires `--cfg tokio_unstable`.");
+
+#[cfg(all(
+    tokio_taskdump,
+    not(all(
+        target_os = "linux",
+        any(target_arch = "aarch64", target_arch = "x86", target_arch = "x86_64")
+    ))
+))]
+compile_error!(
+    "The `tokio_taskdump` feature is only currently supported on \
+linux, on `aarch64`, `x86` and `x86_64`."
+);
 
 // Includes re-exports used by macros.
 //
@@ -360,20 +520,25 @@ pub mod io;
 pub mod net;
 
 mod loom;
-mod park;
 
 cfg_process! {
     pub mod process;
 }
 
-#[cfg(any(feature = "net", feature = "fs", feature = "io-std"))]
+#[cfg(any(
+    feature = "fs",
+    feature = "io-std",
+    feature = "net",
+    all(windows, feature = "process"),
+))]
 mod blocking;
 
 cfg_rt! {
     pub mod runtime;
 }
-
-pub(crate) mod coop;
+cfg_not_rt! {
+    pub(crate) mod runtime;
+}
 
 cfg_signal! {
     pub mod signal;
@@ -402,6 +567,40 @@ cfg_time! {
     pub mod time;
 }
 
+mod trace {
+    use std::future::Future;
+    use std::pin::Pin;
+    use std::task::{Context, Poll};
+
+    cfg_taskdump! {
+        pub(crate) use crate::runtime::task::trace::trace_leaf;
+    }
+
+    cfg_not_taskdump! {
+        #[inline(always)]
+        #[allow(dead_code)]
+        pub(crate) fn trace_leaf(_: &mut std::task::Context<'_>) -> std::task::Poll<()> {
+            std::task::Poll::Ready(())
+        }
+    }
+
+    #[cfg_attr(not(feature = "sync"), allow(dead_code))]
+    pub(crate) fn async_trace_leaf() -> impl Future<Output = ()> {
+        struct Trace;
+
+        impl Future for Trace {
+            type Output = ();
+
+            #[inline(always)]
+            fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<()> {
+                trace_leaf(cx)
+            }
+        }
+
+        Trace
+    }
+}
+
 mod util;
 
 /// Due to the `Stream` trait's inclusion in `std` landing later than Tokio's 1.0
@@ -457,14 +656,6 @@ pub(crate) use self::doc::os;
 #[allow(unused)]
 pub(crate) use std::os;
 
-#[cfg(docsrs)]
-#[allow(unused)]
-pub(crate) use self::doc::winapi;
-
-#[cfg(all(not(docsrs), windows, feature = "net"))]
-#[allow(unused)]
-pub(crate) use ::winapi;
-
 cfg_macros! {
     /// Implementation detail of the `select!` macro. This macro is **not**
     /// intended to be used as part of the public API and is permitted to
@@ -472,6 +663,12 @@ cfg_macros! {
     #[doc(hidden)]
     pub use tokio_macros::select_priv_declare_output_enum;
 
+    /// Implementation detail of the `select!` macro. This macro is **not**
+    /// intended to be used as part of the public API and is permitted to
+    /// change.
+    #[doc(hidden)]
+    pub use tokio_macros::select_priv_clean_pattern;
+
     cfg_rt! {
         #[cfg(feature = "rt-multi-thread")]
         #[cfg(not(test))] // Work around for rust-lang/rust#62127
@@ -509,3 +706,7 @@ cfg_macros! {
 #[cfg(feature = "io-util")]
 #[cfg(test)]
 fn is_unpin<T: Unpin>() {}
+
+/// fuzz test (fuzz_linked_list)
+#[cfg(fuzzing)]
+pub mod fuzz;
diff --git a/vendor/tokio/src/loom/mocked.rs b/vendor/tokio/src/loom/mocked.rs
index 367d59b43..56dc1a063 100644
--- a/vendor/tokio/src/loom/mocked.rs
+++ b/vendor/tokio/src/loom/mocked.rs
@@ -25,6 +25,13 @@ pub(crate) mod sync {
         }
     }
     pub(crate) use loom::sync::*;
+
+    pub(crate) mod atomic {
+        pub(crate) use loom::sync::atomic::*;
+
+        // TODO: implement a loom version
+        pub(crate) type StaticAtomicU64 = std::sync::atomic::AtomicU64;
+    }
 }
 
 pub(crate) mod rand {
@@ -38,3 +45,8 @@ pub(crate) mod sys {
         2
     }
 }
+
+pub(crate) mod thread {
+    pub use loom::lazy_static::AccessError;
+    pub use loom::thread::*;
+}
diff --git a/vendor/tokio/src/loom/std/atomic_ptr.rs b/vendor/tokio/src/loom/std/atomic_ptr.rs
deleted file mode 100644
index 236645f03..000000000
--- a/vendor/tokio/src/loom/std/atomic_ptr.rs
+++ /dev/null
@@ -1,34 +0,0 @@
-use std::fmt;
-use std::ops::{Deref, DerefMut};
-
-/// `AtomicPtr` providing an additional `load_unsync` function.
-pub(crate) struct AtomicPtr<T> {
-    inner: std::sync::atomic::AtomicPtr<T>,
-}
-
-impl<T> AtomicPtr<T> {
-    pub(crate) fn new(ptr: *mut T) -> AtomicPtr<T> {
-        let inner = std::sync::atomic::AtomicPtr::new(ptr);
-        AtomicPtr { inner }
-    }
-}
-
-impl<T> Deref for AtomicPtr<T> {
-    type Target = std::sync::atomic::AtomicPtr<T>;
-
-    fn deref(&self) -> &Self::Target {
-        &self.inner
-    }
-}
-
-impl<T> DerefMut for AtomicPtr<T> {
-    fn deref_mut(&mut self) -> &mut Self::Target {
-        &mut self.inner
-    }
-}
-
-impl<T> fmt::Debug for AtomicPtr<T> {
-    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
-        self.deref().fmt(fmt)
-    }
-}
diff --git a/vendor/tokio/src/loom/std/atomic_u16.rs b/vendor/tokio/src/loom/std/atomic_u16.rs
index c1c531208..c9e105c19 100644
--- a/vendor/tokio/src/loom/std/atomic_u16.rs
+++ b/vendor/tokio/src/loom/std/atomic_u16.rs
@@ -2,7 +2,7 @@ use std::cell::UnsafeCell;
 use std::fmt;
 use std::ops::Deref;
 
-/// `AtomicU16` providing an additional `load_unsync` function.
+/// `AtomicU16` providing an additional `unsync_load` function.
 pub(crate) struct AtomicU16 {
     inner: UnsafeCell<std::sync::atomic::AtomicU16>,
 }
@@ -23,7 +23,7 @@ impl AtomicU16 {
     /// All mutations must have happened before the unsynchronized load.
     /// Additionally, there must be no concurrent mutations.
     pub(crate) unsafe fn unsync_load(&self) -> u16 {
-        *(*self.inner.get()).get_mut()
+        core::ptr::read(self.inner.get() as *const u16)
     }
 }
 
diff --git a/vendor/tokio/src/loom/std/atomic_u32.rs b/vendor/tokio/src/loom/std/atomic_u32.rs
index 61f95fb30..ee0d2d380 100644
--- a/vendor/tokio/src/loom/std/atomic_u32.rs
+++ b/vendor/tokio/src/loom/std/atomic_u32.rs
@@ -2,7 +2,7 @@ use std::cell::UnsafeCell;
 use std::fmt;
 use std::ops::Deref;
 
-/// `AtomicU32` providing an additional `load_unsync` function.
+/// `AtomicU32` providing an additional `unsync_load` function.
 pub(crate) struct AtomicU32 {
     inner: UnsafeCell<std::sync::atomic::AtomicU32>,
 }
@@ -15,6 +15,16 @@ impl AtomicU32 {
         let inner = UnsafeCell::new(std::sync::atomic::AtomicU32::new(val));
         AtomicU32 { inner }
     }
+
+    /// Performs an unsynchronized load.
+    ///
+    /// # Safety
+    ///
+    /// All mutations must have happened before the unsynchronized load.
+    /// Additionally, there must be no concurrent mutations.
+    pub(crate) unsafe fn unsync_load(&self) -> u32 {
+        core::ptr::read(self.inner.get() as *const u32)
+    }
 }
 
 impl Deref for AtomicU32 {
diff --git a/vendor/tokio/src/loom/std/atomic_u64.rs b/vendor/tokio/src/loom/std/atomic_u64.rs
index 7eb457a24..ce391be3e 100644
--- a/vendor/tokio/src/loom/std/atomic_u64.rs
+++ b/vendor/tokio/src/loom/std/atomic_u64.rs
@@ -2,74 +2,18 @@
 //! re-export of `AtomicU64`. On 32 bit platforms, this is implemented using a
 //! `Mutex`.
 
-pub(crate) use self::imp::AtomicU64;
-
 // `AtomicU64` can only be used on targets with `target_has_atomic` is 64 or greater.
 // Once `cfg_target_has_atomic` feature is stable, we can replace it with
 // `#[cfg(target_has_atomic = "64")]`.
 // Refs: https://github.com/rust-lang/rust/tree/master/src/librustc_target
-#[cfg(not(any(target_arch = "arm", target_arch = "mips", target_arch = "powerpc")))]
-mod imp {
-    pub(crate) use std::sync::atomic::AtomicU64;
+cfg_has_atomic_u64! {
+    #[path = "atomic_u64_native.rs"]
+    mod imp;
 }
 
-#[cfg(any(target_arch = "arm", target_arch = "mips", target_arch = "powerpc"))]
-mod imp {
-    use crate::loom::sync::Mutex;
-    use std::sync::atomic::Ordering;
-
-    #[derive(Debug)]
-    pub(crate) struct AtomicU64 {
-        inner: Mutex<u64>,
-    }
-
-    impl AtomicU64 {
-        pub(crate) fn new(val: u64) -> Self {
-            Self {
-                inner: Mutex::new(val),
-            }
-        }
-
-        pub(crate) fn load(&self, _: Ordering) -> u64 {
-            *self.inner.lock()
-        }
-
-        pub(crate) fn store(&self, val: u64, _: Ordering) {
-            *self.inner.lock() = val;
-        }
-
-        pub(crate) fn fetch_or(&self, val: u64, _: Ordering) -> u64 {
-            let mut lock = self.inner.lock();
-            let prev = *lock;
-            *lock = prev | val;
-            prev
-        }
-
-        pub(crate) fn compare_exchange(
-            &self,
-            current: u64,
-            new: u64,
-            _success: Ordering,
-            _failure: Ordering,
-        ) -> Result<u64, u64> {
-            let mut lock = self.inner.lock();
-
-            if *lock == current {
-                *lock = new;
-                Ok(current)
-            } else {
-                Err(*lock)
-            }
-        }
-
-        pub(crate) fn compare_exchange_weak(
-            &self,
-            current: u64,
-            new: u64,
-            success: Ordering,
-            failure: Ordering,
-        ) -> Result<u64, u64> {
-            self.compare_exchange(current, new, success, failure)
-        }
-    }
+cfg_not_has_atomic_u64! {
+    #[path = "atomic_u64_as_mutex.rs"]
+    mod imp;
 }
+
+pub(crate) use imp::{AtomicU64, StaticAtomicU64};
diff --git a/vendor/tokio/src/loom/std/atomic_u64_as_mutex.rs b/vendor/tokio/src/loom/std/atomic_u64_as_mutex.rs
new file mode 100644
index 000000000..9b3b6fac6
--- /dev/null
+++ b/vendor/tokio/src/loom/std/atomic_u64_as_mutex.rs
@@ -0,0 +1,76 @@
+use crate::loom::sync::Mutex;
+use std::sync::atomic::Ordering;
+
+cfg_has_const_mutex_new! {
+    #[path = "atomic_u64_static_const_new.rs"]
+    mod static_macro;
+}
+
+cfg_not_has_const_mutex_new! {
+    #[path = "atomic_u64_static_once_cell.rs"]
+    mod static_macro;
+}
+
+pub(crate) use static_macro::StaticAtomicU64;
+
+#[derive(Debug)]
+pub(crate) struct AtomicU64 {
+    inner: Mutex<u64>,
+}
+
+impl AtomicU64 {
+    pub(crate) fn load(&self, _: Ordering) -> u64 {
+        *self.inner.lock()
+    }
+
+    pub(crate) fn store(&self, val: u64, _: Ordering) {
+        *self.inner.lock() = val;
+    }
+
+    pub(crate) fn fetch_add(&self, val: u64, _: Ordering) -> u64 {
+        let mut lock = self.inner.lock();
+        let prev = *lock;
+        *lock = prev + val;
+        prev
+    }
+
+    pub(crate) fn fetch_or(&self, val: u64, _: Ordering) -> u64 {
+        let mut lock = self.inner.lock();
+        let prev = *lock;
+        *lock = prev | val;
+        prev
+    }
+
+    pub(crate) fn compare_exchange(
+        &self,
+        current: u64,
+        new: u64,
+        _success: Ordering,
+        _failure: Ordering,
+    ) -> Result<u64, u64> {
+        let mut lock = self.inner.lock();
+
+        if *lock == current {
+            *lock = new;
+            Ok(current)
+        } else {
+            Err(*lock)
+        }
+    }
+
+    pub(crate) fn compare_exchange_weak(
+        &self,
+        current: u64,
+        new: u64,
+        success: Ordering,
+        failure: Ordering,
+    ) -> Result<u64, u64> {
+        self.compare_exchange(current, new, success, failure)
+    }
+}
+
+impl Default for AtomicU64 {
+    fn default() -> AtomicU64 {
+        AtomicU64::new(u64::default())
+    }
+}
diff --git a/vendor/tokio/src/loom/std/atomic_u64_native.rs b/vendor/tokio/src/loom/std/atomic_u64_native.rs
new file mode 100644
index 000000000..08adb2862
--- /dev/null
+++ b/vendor/tokio/src/loom/std/atomic_u64_native.rs
@@ -0,0 +1,4 @@
+pub(crate) use std::sync::atomic::{AtomicU64, Ordering};
+
+/// Alias `AtomicU64` to `StaticAtomicU64`
+pub(crate) type StaticAtomicU64 = AtomicU64;
diff --git a/vendor/tokio/src/loom/std/atomic_u64_static_const_new.rs b/vendor/tokio/src/loom/std/atomic_u64_static_const_new.rs
new file mode 100644
index 000000000..a4215342b
--- /dev/null
+++ b/vendor/tokio/src/loom/std/atomic_u64_static_const_new.rs
@@ -0,0 +1,12 @@
+use super::AtomicU64;
+use crate::loom::sync::Mutex;
+
+pub(crate) type StaticAtomicU64 = AtomicU64;
+
+impl AtomicU64 {
+    pub(crate) const fn new(val: u64) -> Self {
+        Self {
+            inner: Mutex::const_new(val),
+        }
+    }
+}
diff --git a/vendor/tokio/src/loom/std/atomic_u64_static_once_cell.rs b/vendor/tokio/src/loom/std/atomic_u64_static_once_cell.rs
new file mode 100644
index 000000000..40c6172a5
--- /dev/null
+++ b/vendor/tokio/src/loom/std/atomic_u64_static_once_cell.rs
@@ -0,0 +1,57 @@
+use super::AtomicU64;
+use crate::loom::sync::{atomic::Ordering, Mutex};
+use crate::util::once_cell::OnceCell;
+
+pub(crate) struct StaticAtomicU64 {
+    init: u64,
+    cell: OnceCell<Mutex<u64>>,
+}
+
+impl AtomicU64 {
+    pub(crate) fn new(val: u64) -> Self {
+        Self {
+            inner: Mutex::new(val),
+        }
+    }
+}
+
+impl StaticAtomicU64 {
+    pub(crate) const fn new(val: u64) -> StaticAtomicU64 {
+        StaticAtomicU64 {
+            init: val,
+            cell: OnceCell::new(),
+        }
+    }
+
+    pub(crate) fn load(&self, order: Ordering) -> u64 {
+        *self.inner().lock()
+    }
+
+    pub(crate) fn fetch_add(&self, val: u64, order: Ordering) -> u64 {
+        let mut lock = self.inner().lock();
+        let prev = *lock;
+        *lock = prev + val;
+        prev
+    }
+
+    pub(crate) fn compare_exchange_weak(
+        &self,
+        current: u64,
+        new: u64,
+        _success: Ordering,
+        _failure: Ordering,
+    ) -> Result<u64, u64> {
+        let mut lock = self.inner().lock();
+
+        if *lock == current {
+            *lock = new;
+            Ok(current)
+        } else {
+            Err(*lock)
+        }
+    }
+
+    fn inner(&self) -> &Mutex<u64> {
+        self.cell.get(|| Mutex::new(self.init))
+    }
+}
diff --git a/vendor/tokio/src/loom/std/atomic_u8.rs b/vendor/tokio/src/loom/std/atomic_u8.rs
deleted file mode 100644
index 408aea338..000000000
--- a/vendor/tokio/src/loom/std/atomic_u8.rs
+++ /dev/null
@@ -1,34 +0,0 @@
-use std::cell::UnsafeCell;
-use std::fmt;
-use std::ops::Deref;
-
-/// `AtomicU8` providing an additional `load_unsync` function.
-pub(crate) struct AtomicU8 {
-    inner: UnsafeCell<std::sync::atomic::AtomicU8>,
-}
-
-unsafe impl Send for AtomicU8 {}
-unsafe impl Sync for AtomicU8 {}
-
-impl AtomicU8 {
-    pub(crate) const fn new(val: u8) -> AtomicU8 {
-        let inner = UnsafeCell::new(std::sync::atomic::AtomicU8::new(val));
-        AtomicU8 { inner }
-    }
-}
-
-impl Deref for AtomicU8 {
-    type Target = std::sync::atomic::AtomicU8;
-
-    fn deref(&self) -> &Self::Target {
-        // safety: it is always safe to access `&self` fns on the inner value as
-        // we never perform unsafe mutations.
-        unsafe { &*self.inner.get() }
-    }
-}
-
-impl fmt::Debug for AtomicU8 {
-    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
-        self.deref().fmt(fmt)
-    }
-}
diff --git a/vendor/tokio/src/loom/std/atomic_usize.rs b/vendor/tokio/src/loom/std/atomic_usize.rs
index 0d5f36e43..c5503a2c1 100644
--- a/vendor/tokio/src/loom/std/atomic_usize.rs
+++ b/vendor/tokio/src/loom/std/atomic_usize.rs
@@ -2,7 +2,7 @@ use std::cell::UnsafeCell;
 use std::fmt;
 use std::ops;
 
-/// `AtomicUsize` providing an additional `load_unsync` function.
+/// `AtomicUsize` providing an additional `unsync_load` function.
 pub(crate) struct AtomicUsize {
     inner: UnsafeCell<std::sync::atomic::AtomicUsize>,
 }
@@ -23,7 +23,7 @@ impl AtomicUsize {
     /// All mutations must have happened before the unsynchronized load.
     /// Additionally, there must be no concurrent mutations.
     pub(crate) unsafe fn unsync_load(&self) -> usize {
-        *(*self.inner.get()).get_mut()
+        core::ptr::read(self.inner.get() as *const usize)
     }
 
     pub(crate) fn with_mut<R>(&mut self, f: impl FnOnce(&mut usize) -> R) -> R {
diff --git a/vendor/tokio/src/loom/std/barrier.rs b/vendor/tokio/src/loom/std/barrier.rs
new file mode 100644
index 000000000..a3f0ca0ab
--- /dev/null
+++ b/vendor/tokio/src/loom/std/barrier.rs
@@ -0,0 +1,217 @@
+//! A `Barrier` that provides `wait_timeout`.
+//!
+//! This implementation mirrors that of the Rust standard library.
+
+use crate::loom::sync::{Condvar, Mutex};
+use std::fmt;
+use std::time::{Duration, Instant};
+
+/// A barrier enables multiple threads to synchronize the beginning
+/// of some computation.
+///
+/// # Examples
+///
+/// ```
+/// use std::sync::{Arc, Barrier};
+/// use std::thread;
+///
+/// let mut handles = Vec::with_capacity(10);
+/// let barrier = Arc::new(Barrier::new(10));
+/// for _ in 0..10 {
+///     let c = Arc::clone(&barrier);
+///     // The same messages will be printed together.
+///     // You will NOT see any interleaving.
+///     handles.push(thread::spawn(move|| {
+///         println!("before wait");
+///         c.wait();
+///         println!("after wait");
+///     }));
+/// }
+/// // Wait for other threads to finish.
+/// for handle in handles {
+///     handle.join().unwrap();
+/// }
+/// ```
+pub(crate) struct Barrier {
+    lock: Mutex<BarrierState>,
+    cvar: Condvar,
+    num_threads: usize,
+}
+
+// The inner state of a double barrier
+struct BarrierState {
+    count: usize,
+    generation_id: usize,
+}
+
+/// A `BarrierWaitResult` is returned by [`Barrier::wait()`] when all threads
+/// in the [`Barrier`] have rendezvoused.
+///
+/// # Examples
+///
+/// ```
+/// use std::sync::Barrier;
+///
+/// let barrier = Barrier::new(1);
+/// let barrier_wait_result = barrier.wait();
+/// ```
+pub(crate) struct BarrierWaitResult(bool);
+
+impl fmt::Debug for Barrier {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("Barrier").finish_non_exhaustive()
+    }
+}
+
+impl Barrier {
+    /// Creates a new barrier that can block a given number of threads.
+    ///
+    /// A barrier will block `n`-1 threads which call [`wait()`] and then wake
+    /// up all threads at once when the `n`th thread calls [`wait()`].
+    ///
+    /// [`wait()`]: Barrier::wait
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::sync::Barrier;
+    ///
+    /// let barrier = Barrier::new(10);
+    /// ```
+    #[must_use]
+    pub(crate) fn new(n: usize) -> Barrier {
+        Barrier {
+            lock: Mutex::new(BarrierState {
+                count: 0,
+                generation_id: 0,
+            }),
+            cvar: Condvar::new(),
+            num_threads: n,
+        }
+    }
+
+    /// Blocks the current thread until all threads have rendezvoused here.
+    ///
+    /// Barriers are re-usable after all threads have rendezvoused once, and can
+    /// be used continuously.
+    ///
+    /// A single (arbitrary) thread will receive a [`BarrierWaitResult`] that
+    /// returns `true` from [`BarrierWaitResult::is_leader()`] when returning
+    /// from this function, and all other threads will receive a result that
+    /// will return `false` from [`BarrierWaitResult::is_leader()`].
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::sync::{Arc, Barrier};
+    /// use std::thread;
+    ///
+    /// let mut handles = Vec::with_capacity(10);
+    /// let barrier = Arc::new(Barrier::new(10));
+    /// for _ in 0..10 {
+    ///     let c = Arc::clone(&barrier);
+    ///     // The same messages will be printed together.
+    ///     // You will NOT see any interleaving.
+    ///     handles.push(thread::spawn(move|| {
+    ///         println!("before wait");
+    ///         c.wait();
+    ///         println!("after wait");
+    ///     }));
+    /// }
+    /// // Wait for other threads to finish.
+    /// for handle in handles {
+    ///     handle.join().unwrap();
+    /// }
+    /// ```
+    pub(crate) fn wait(&self) -> BarrierWaitResult {
+        let mut lock = self.lock.lock();
+        let local_gen = lock.generation_id;
+        lock.count += 1;
+        if lock.count < self.num_threads {
+            // We need a while loop to guard against spurious wakeups.
+            // https://en.wikipedia.org/wiki/Spurious_wakeup
+            while local_gen == lock.generation_id {
+                lock = self.cvar.wait(lock).unwrap();
+            }
+            BarrierWaitResult(false)
+        } else {
+            lock.count = 0;
+            lock.generation_id = lock.generation_id.wrapping_add(1);
+            self.cvar.notify_all();
+            BarrierWaitResult(true)
+        }
+    }
+
+    /// Blocks the current thread until all threads have rendezvoused here for
+    /// at most `timeout` duration.
+    pub(crate) fn wait_timeout(&self, timeout: Duration) -> Option<BarrierWaitResult> {
+        // This implementation mirrors `wait`, but with each blocking operation
+        // replaced by a timeout-amenable alternative.
+
+        let deadline = Instant::now() + timeout;
+
+        // Acquire `self.lock` with at most `timeout` duration.
+        let mut lock = loop {
+            if let Some(guard) = self.lock.try_lock() {
+                break guard;
+            } else if Instant::now() > deadline {
+                return None;
+            } else {
+                std::thread::yield_now();
+            }
+        };
+
+        // Shrink the `timeout` to account for the time taken to acquire `lock`.
+        let timeout = deadline.saturating_duration_since(Instant::now());
+
+        let local_gen = lock.generation_id;
+        lock.count += 1;
+        if lock.count < self.num_threads {
+            // We need a while loop to guard against spurious wakeups.
+            // https://en.wikipedia.org/wiki/Spurious_wakeup
+            while local_gen == lock.generation_id {
+                let (guard, timeout_result) = self.cvar.wait_timeout(lock, timeout).unwrap();
+                lock = guard;
+                if timeout_result.timed_out() {
+                    return None;
+                }
+            }
+            Some(BarrierWaitResult(false))
+        } else {
+            lock.count = 0;
+            lock.generation_id = lock.generation_id.wrapping_add(1);
+            self.cvar.notify_all();
+            Some(BarrierWaitResult(true))
+        }
+    }
+}
+
+impl fmt::Debug for BarrierWaitResult {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("BarrierWaitResult")
+            .field("is_leader", &self.is_leader())
+            .finish()
+    }
+}
+
+impl BarrierWaitResult {
+    /// Returns `true` if this thread is the "leader thread" for the call to
+    /// [`Barrier::wait()`].
+    ///
+    /// Only one thread will have `true` returned from their result, all other
+    /// threads will have `false` returned.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::sync::Barrier;
+    ///
+    /// let barrier = Barrier::new(1);
+    /// let barrier_wait_result = barrier.wait();
+    /// println!("{:?}", barrier_wait_result.is_leader());
+    /// ```
+    #[must_use]
+    pub(crate) fn is_leader(&self) -> bool {
+        self.0
+    }
+}
diff --git a/vendor/tokio/src/loom/std/mod.rs b/vendor/tokio/src/loom/std/mod.rs
index b29cbeeb8..0a732791f 100644
--- a/vendor/tokio/src/loom/std/mod.rs
+++ b/vendor/tokio/src/loom/std/mod.rs
@@ -1,11 +1,10 @@
 #![cfg_attr(any(not(feature = "full"), loom), allow(unused_imports, dead_code))]
 
-mod atomic_ptr;
 mod atomic_u16;
 mod atomic_u32;
 mod atomic_u64;
-mod atomic_u8;
 mod atomic_usize;
+mod barrier;
 mod mutex;
 #[cfg(feature = "parking_lot")]
 mod parking_lot;
@@ -25,6 +24,10 @@ pub(crate) mod future {
     pub(crate) use crate::sync::AtomicWaker;
 }
 
+pub(crate) mod hint {
+    pub(crate) use std::hint::spin_loop;
+}
+
 pub(crate) mod rand {
     use std::collections::hash_map::RandomState;
     use std::hash::{BuildHasher, Hash, Hasher};
@@ -67,24 +70,41 @@ pub(crate) mod sync {
     pub(crate) use crate::loom::std::mutex::Mutex;
 
     pub(crate) mod atomic {
-        pub(crate) use crate::loom::std::atomic_ptr::AtomicPtr;
         pub(crate) use crate::loom::std::atomic_u16::AtomicU16;
         pub(crate) use crate::loom::std::atomic_u32::AtomicU32;
-        pub(crate) use crate::loom::std::atomic_u64::AtomicU64;
-        pub(crate) use crate::loom::std::atomic_u8::AtomicU8;
+        pub(crate) use crate::loom::std::atomic_u64::{AtomicU64, StaticAtomicU64};
         pub(crate) use crate::loom::std::atomic_usize::AtomicUsize;
 
-        pub(crate) use std::sync::atomic::{fence, AtomicBool, Ordering};
-        // TODO: once we bump MSRV to 1.49+, use `hint::spin_loop` instead.
-        #[allow(deprecated)]
-        pub(crate) use std::sync::atomic::spin_loop_hint;
+        pub(crate) use std::sync::atomic::{fence, AtomicBool, AtomicPtr, AtomicU8, Ordering};
     }
+
+    pub(crate) use super::barrier::Barrier;
 }
 
 pub(crate) mod sys {
     #[cfg(feature = "rt-multi-thread")]
     pub(crate) fn num_cpus() -> usize {
-        usize::max(1, num_cpus::get())
+        const ENV_WORKER_THREADS: &str = "TOKIO_WORKER_THREADS";
+
+        match std::env::var(ENV_WORKER_THREADS) {
+            Ok(s) => {
+                let n = s.parse().unwrap_or_else(|e| {
+                    panic!(
+                        "\"{}\" must be usize, error: {}, value: {}",
+                        ENV_WORKER_THREADS, e, s
+                    )
+                });
+                assert!(n > 0, "\"{}\" cannot be set to 0", ENV_WORKER_THREADS);
+                n
+            }
+            Err(std::env::VarError::NotPresent) => usize::max(1, num_cpus::get()),
+            Err(std::env::VarError::NotUnicode(e)) => {
+                panic!(
+                    "\"{}\" must be valid unicode, error: {:?}",
+                    ENV_WORKER_THREADS, e
+                )
+            }
+        }
     }
 
     #[cfg(not(feature = "rt-multi-thread"))]
@@ -93,4 +113,15 @@ pub(crate) mod sys {
     }
 }
 
-pub(crate) use std::thread;
+pub(crate) mod thread {
+    #[inline]
+    pub(crate) fn yield_now() {
+        std::hint::spin_loop();
+    }
+
+    #[allow(unused_imports)]
+    pub(crate) use std::thread::{
+        current, panicking, park, park_timeout, sleep, spawn, AccessError, Builder, JoinHandle,
+        LocalKey, Result, Thread, ThreadId,
+    };
+}
diff --git a/vendor/tokio/src/loom/std/mutex.rs b/vendor/tokio/src/loom/std/mutex.rs
index bf14d6242..076f78611 100644
--- a/vendor/tokio/src/loom/std/mutex.rs
+++ b/vendor/tokio/src/loom/std/mutex.rs
@@ -1,7 +1,7 @@
 use std::sync::{self, MutexGuard, TryLockError};
 
 /// Adapter for `std::Mutex` that removes the poisoning aspects
-// from its api
+/// from its api.
 #[derive(Debug)]
 pub(crate) struct Mutex<T: ?Sized>(sync::Mutex<T>);
 
@@ -13,6 +13,12 @@ impl<T> Mutex<T> {
     }
 
     #[inline]
+    #[cfg(not(tokio_no_const_mutex_new))]
+    pub(crate) const fn const_new(t: T) -> Mutex<T> {
+        Mutex(sync::Mutex::new(t))
+    }
+
+    #[inline]
     pub(crate) fn lock(&self) -> MutexGuard<'_, T> {
         match self.0.lock() {
             Ok(guard) => guard,
diff --git a/vendor/tokio/src/loom/std/parking_lot.rs b/vendor/tokio/src/loom/std/parking_lot.rs
index 8448bed53..e3af258d1 100644
--- a/vendor/tokio/src/loom/std/parking_lot.rs
+++ b/vendor/tokio/src/loom/std/parking_lot.rs
@@ -3,83 +3,143 @@
 //!
 //! This can be extended to additional types/methods as required.
 
+use std::fmt;
+use std::marker::PhantomData;
+use std::ops::{Deref, DerefMut};
 use std::sync::LockResult;
 use std::time::Duration;
 
+// All types in this file are marked with PhantomData to ensure that
+// parking_lot's send_guard feature does not leak through and affect when Tokio
+// types are Send.
+//
+// See <https://github.com/tokio-rs/tokio/pull/4359> for more info.
+
 // Types that do not need wrapping
-pub(crate) use parking_lot::{MutexGuard, RwLockReadGuard, RwLockWriteGuard, WaitTimeoutResult};
+pub(crate) use parking_lot::WaitTimeoutResult;
+
+#[derive(Debug)]
+pub(crate) struct Mutex<T: ?Sized>(PhantomData<std::sync::Mutex<T>>, parking_lot::Mutex<T>);
+
+#[derive(Debug)]
+pub(crate) struct RwLock<T>(PhantomData<std::sync::RwLock<T>>, parking_lot::RwLock<T>);
+
+#[derive(Debug)]
+pub(crate) struct Condvar(PhantomData<std::sync::Condvar>, parking_lot::Condvar);
 
-/// Adapter for `parking_lot::Mutex` to the `std::sync::Mutex` interface.
 #[derive(Debug)]
-pub(crate) struct Mutex<T: ?Sized>(parking_lot::Mutex<T>);
+pub(crate) struct MutexGuard<'a, T: ?Sized>(
+    PhantomData<std::sync::MutexGuard<'a, T>>,
+    parking_lot::MutexGuard<'a, T>,
+);
 
 #[derive(Debug)]
-pub(crate) struct RwLock<T>(parking_lot::RwLock<T>);
+pub(crate) struct RwLockReadGuard<'a, T: ?Sized>(
+    PhantomData<std::sync::RwLockReadGuard<'a, T>>,
+    parking_lot::RwLockReadGuard<'a, T>,
+);
 
-/// Adapter for `parking_lot::Condvar` to the `std::sync::Condvar` interface.
 #[derive(Debug)]
-pub(crate) struct Condvar(parking_lot::Condvar);
+pub(crate) struct RwLockWriteGuard<'a, T: ?Sized>(
+    PhantomData<std::sync::RwLockWriteGuard<'a, T>>,
+    parking_lot::RwLockWriteGuard<'a, T>,
+);
 
 impl<T> Mutex<T> {
     #[inline]
     pub(crate) fn new(t: T) -> Mutex<T> {
-        Mutex(parking_lot::Mutex::new(t))
+        Mutex(PhantomData, parking_lot::Mutex::new(t))
     }
 
     #[inline]
-    #[cfg(all(feature = "parking_lot", not(all(loom, test)),))]
+    #[cfg(all(feature = "parking_lot", not(all(loom, test))))]
     #[cfg_attr(docsrs, doc(cfg(all(feature = "parking_lot",))))]
     pub(crate) const fn const_new(t: T) -> Mutex<T> {
-        Mutex(parking_lot::const_mutex(t))
+        Mutex(PhantomData, parking_lot::const_mutex(t))
     }
 
     #[inline]
     pub(crate) fn lock(&self) -> MutexGuard<'_, T> {
-        self.0.lock()
+        MutexGuard(PhantomData, self.1.lock())
     }
 
     #[inline]
     pub(crate) fn try_lock(&self) -> Option<MutexGuard<'_, T>> {
-        self.0.try_lock()
+        self.1
+            .try_lock()
+            .map(|guard| MutexGuard(PhantomData, guard))
     }
 
     #[inline]
     pub(crate) fn get_mut(&mut self) -> &mut T {
-        self.0.get_mut()
+        self.1.get_mut()
     }
 
     // Note: Additional methods `is_poisoned` and `into_inner`, can be
     // provided here as needed.
 }
 
+impl<'a, T: ?Sized> Deref for MutexGuard<'a, T> {
+    type Target = T;
+    fn deref(&self) -> &T {
+        self.1.deref()
+    }
+}
+
+impl<'a, T: ?Sized> DerefMut for MutexGuard<'a, T> {
+    fn deref_mut(&mut self) -> &mut T {
+        self.1.deref_mut()
+    }
+}
+
 impl<T> RwLock<T> {
     pub(crate) fn new(t: T) -> RwLock<T> {
-        RwLock(parking_lot::RwLock::new(t))
+        RwLock(PhantomData, parking_lot::RwLock::new(t))
     }
 
     pub(crate) fn read(&self) -> LockResult<RwLockReadGuard<'_, T>> {
-        Ok(self.0.read())
+        Ok(RwLockReadGuard(PhantomData, self.1.read()))
     }
 
     pub(crate) fn write(&self) -> LockResult<RwLockWriteGuard<'_, T>> {
-        Ok(self.0.write())
+        Ok(RwLockWriteGuard(PhantomData, self.1.write()))
+    }
+}
+
+impl<'a, T: ?Sized> Deref for RwLockReadGuard<'a, T> {
+    type Target = T;
+    fn deref(&self) -> &T {
+        self.1.deref()
+    }
+}
+
+impl<'a, T: ?Sized> Deref for RwLockWriteGuard<'a, T> {
+    type Target = T;
+    fn deref(&self) -> &T {
+        self.1.deref()
+    }
+}
+
+impl<'a, T: ?Sized> DerefMut for RwLockWriteGuard<'a, T> {
+    fn deref_mut(&mut self) -> &mut T {
+        self.1.deref_mut()
     }
 }
 
 impl Condvar {
     #[inline]
     pub(crate) fn new() -> Condvar {
-        Condvar(parking_lot::Condvar::new())
+        Condvar(PhantomData, parking_lot::Condvar::new())
     }
 
     #[inline]
     pub(crate) fn notify_one(&self) {
-        self.0.notify_one();
+        self.1.notify_one();
     }
 
     #[inline]
     pub(crate) fn notify_all(&self) {
-        self.0.notify_all();
+        self.1.notify_all();
     }
 
     #[inline]
@@ -87,7 +147,7 @@ impl Condvar {
         &self,
         mut guard: MutexGuard<'a, T>,
     ) -> LockResult<MutexGuard<'a, T>> {
-        self.0.wait(&mut guard);
+        self.1.wait(&mut guard.1);
         Ok(guard)
     }
 
@@ -97,10 +157,28 @@ impl Condvar {
         mut guard: MutexGuard<'a, T>,
         timeout: Duration,
     ) -> LockResult<(MutexGuard<'a, T>, WaitTimeoutResult)> {
-        let wtr = self.0.wait_for(&mut guard, timeout);
+        let wtr = self.1.wait_for(&mut guard.1, timeout);
         Ok((guard, wtr))
     }
 
     // Note: Additional methods `wait_timeout_ms`, `wait_timeout_until`,
     // `wait_until` can be provided here as needed.
 }
+
+impl<'a, T: ?Sized + fmt::Display> fmt::Display for MutexGuard<'a, T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt(&self.1, f)
+    }
+}
+
+impl<'a, T: ?Sized + fmt::Display> fmt::Display for RwLockReadGuard<'a, T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt(&self.1, f)
+    }
+}
+
+impl<'a, T: ?Sized + fmt::Display> fmt::Display for RwLockWriteGuard<'a, T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt(&self.1, f)
+    }
+}
diff --git a/vendor/tokio/src/macros/addr_of.rs b/vendor/tokio/src/macros/addr_of.rs
new file mode 100644
index 000000000..9d28158f2
--- /dev/null
+++ b/vendor/tokio/src/macros/addr_of.rs
@@ -0,0 +1,22 @@
+//! This module defines a macro that lets you go from a raw pointer to a struct
+//! to a raw pointer to a field of the struct.
+
+macro_rules! generate_addr_of_methods {
+    (
+    impl<$($gen:ident)*> $struct_name:ty {$(
+        $(#[$attrs:meta])*
+        $vis:vis unsafe fn $fn_name:ident(self: NonNull<Self>) -> NonNull<$field_type:ty> {
+            &self$(.$field_name:tt)+
+        }
+    )*}
+    ) => {
+        impl<$($gen)*> $struct_name {$(
+            $(#[$attrs])*
+            $vis unsafe fn $fn_name(me: ::core::ptr::NonNull<Self>) -> ::core::ptr::NonNull<$field_type> {
+                let me = me.as_ptr();
+                let field = ::std::ptr::addr_of_mut!((*me) $(.$field_name)+ );
+                ::core::ptr::NonNull::new_unchecked(field)
+            }
+        )*}
+    };
+}
diff --git a/vendor/tokio/src/macros/cfg.rs b/vendor/tokio/src/macros/cfg.rs
index 1e77556d8..52ffc102b 100644
--- a/vendor/tokio/src/macros/cfg.rs
+++ b/vendor/tokio/src/macros/cfg.rs
@@ -13,7 +13,19 @@ macro_rules! feature {
     }
 }
 
-/// Enables enter::block_on
+/// Enables Windows-specific code.
+/// Use this macro instead of `cfg(windows)` to generate docs properly.
+macro_rules! cfg_windows {
+    ($($item:item)*) => {
+        $(
+            #[cfg(any(all(doc, docsrs), windows))]
+            #[cfg_attr(docsrs, doc(cfg(windows)))]
+            $item
+        )*
+    }
+}
+
+/// Enables enter::block_on.
 macro_rules! cfg_block_on {
     ($($item:item)*) => {
         $(
@@ -28,7 +40,7 @@ macro_rules! cfg_block_on {
     }
 }
 
-/// Enables internal `AtomicWaker` impl
+/// Enables internal `AtomicWaker` impl.
 macro_rules! cfg_atomic_waker_impl {
     ($($item:item)*) => {
         $(
@@ -45,10 +57,23 @@ macro_rules! cfg_atomic_waker_impl {
     }
 }
 
+macro_rules! cfg_aio {
+    ($($item:item)*) => {
+        $(
+            #[cfg(all(any(docsrs, target_os = "freebsd"), feature = "net"))]
+            #[cfg_attr(docsrs,
+                doc(cfg(all(target_os = "freebsd", feature = "net")))
+            )]
+            $item
+        )*
+    }
+}
+
 macro_rules! cfg_fs {
     ($($item:item)*) => {
         $(
             #[cfg(feature = "fs")]
+            #[cfg(not(tokio_wasi))]
             #[cfg_attr(docsrs, doc(cfg(feature = "fs")))]
             $item
         )*
@@ -57,7 +82,11 @@ macro_rules! cfg_fs {
 
 macro_rules! cfg_io_blocking {
     ($($item:item)*) => {
-        $( #[cfg(any(feature = "io-std", feature = "fs"))] $item )*
+        $( #[cfg(any(
+                feature = "io-std",
+                feature = "fs",
+                all(windows, feature = "process"),
+        ))] $item )*
     }
 }
 
@@ -66,12 +95,12 @@ macro_rules! cfg_io_driver {
         $(
             #[cfg(any(
                 feature = "net",
-                feature = "process",
+                all(unix, feature = "process"),
                 all(unix, feature = "signal"),
             ))]
             #[cfg_attr(docsrs, doc(cfg(any(
                 feature = "net",
-                feature = "process",
+                all(unix, feature = "process"),
                 all(unix, feature = "signal"),
             ))))]
             $item
@@ -84,7 +113,7 @@ macro_rules! cfg_io_driver_impl {
         $(
             #[cfg(any(
                 feature = "net",
-                feature = "process",
+                all(unix, feature = "process"),
                 all(unix, feature = "signal"),
             ))]
             $item
@@ -97,7 +126,7 @@ macro_rules! cfg_not_io_driver {
         $(
             #[cfg(not(any(
                 feature = "net",
-                feature = "process",
+                all(unix, feature = "process"),
                 all(unix, feature = "signal"),
             )))]
             $item
@@ -162,6 +191,43 @@ macro_rules! cfg_macros {
     }
 }
 
+macro_rules! cfg_metrics {
+    ($($item:item)*) => {
+        $(
+            // For now, metrics is only disabled in loom tests.
+            // When stabilized, it might have a dedicated feature flag.
+            #[cfg(all(tokio_unstable, not(loom)))]
+            #[cfg_attr(docsrs, doc(cfg(tokio_unstable)))]
+            $item
+        )*
+    }
+}
+
+macro_rules! cfg_not_metrics {
+    ($($item:item)*) => {
+        $(
+            #[cfg(not(all(tokio_unstable, not(loom))))]
+            $item
+        )*
+    }
+}
+
+macro_rules! cfg_not_rt_and_metrics_and_net {
+    ($($item:item)*) => {
+        $( #[cfg(not(all(feature = "net", feature = "rt", all(tokio_unstable, not(loom)))))]$item )*
+    }
+}
+
+macro_rules! cfg_net_or_process {
+    ($($item:item)*) => {
+        $(
+            #[cfg(any(feature = "net", feature = "process"))]
+            #[cfg_attr(docsrs, doc(cfg(any(feature = "net", feature = "process"))))]
+            $item
+        )*
+    }
+}
+
 macro_rules! cfg_net {
     ($($item:item)*) => {
         $(
@@ -176,7 +242,7 @@ macro_rules! cfg_net_unix {
     ($($item:item)*) => {
         $(
             #[cfg(all(unix, feature = "net"))]
-            #[cfg_attr(docsrs, doc(cfg(feature = "net")))]
+            #[cfg_attr(docsrs, doc(cfg(all(unix, feature = "net"))))]
             $item
         )*
     }
@@ -185,7 +251,7 @@ macro_rules! cfg_net_unix {
 macro_rules! cfg_net_windows {
     ($($item:item)*) => {
         $(
-            #[cfg(all(any(docsrs, windows), feature = "net"))]
+            #[cfg(all(any(all(doc, docsrs), windows), feature = "net"))]
             #[cfg_attr(docsrs, doc(cfg(all(windows, feature = "net"))))]
             $item
         )*
@@ -198,6 +264,7 @@ macro_rules! cfg_process {
             #[cfg(feature = "process")]
             #[cfg_attr(docsrs, doc(cfg(feature = "process")))]
             #[cfg(not(loom))]
+            #[cfg(not(tokio_wasi))]
             $item
         )*
     }
@@ -226,6 +293,7 @@ macro_rules! cfg_signal {
             #[cfg(feature = "signal")]
             #[cfg_attr(docsrs, doc(cfg(feature = "signal")))]
             #[cfg(not(loom))]
+            #[cfg(not(tokio_wasi))]
             $item
         )*
     }
@@ -241,6 +309,13 @@ macro_rules! cfg_signal_internal {
     }
 }
 
+macro_rules! cfg_signal_internal_and_unix {
+    ($($item:item)*) => {
+        #[cfg(unix)]
+        cfg_signal_internal! { $($item)* }
+    }
+}
+
 macro_rules! cfg_not_signal_internal {
     ($($item:item)*) => {
         $(
@@ -285,7 +360,7 @@ macro_rules! cfg_not_rt {
 macro_rules! cfg_rt_multi_thread {
     ($($item:item)*) => {
         $(
-            #[cfg(feature = "rt-multi-thread")]
+            #[cfg(all(feature = "rt-multi-thread", not(tokio_wasi)))]
             #[cfg_attr(docsrs, doc(cfg(feature = "rt-multi-thread")))]
             $item
         )*
@@ -298,6 +373,44 @@ macro_rules! cfg_not_rt_multi_thread {
     }
 }
 
+macro_rules! cfg_taskdump {
+    ($($item:item)*) => {
+        $(
+            #[cfg(all(
+                tokio_unstable,
+                tokio_taskdump,
+                feature = "rt",
+                target_os = "linux",
+                any(
+                    target_arch = "aarch64",
+                    target_arch = "x86",
+                    target_arch = "x86_64"
+                )
+            ))]
+            $item
+        )*
+    };
+}
+
+macro_rules! cfg_not_taskdump {
+    ($($item:item)*) => {
+        $(
+            #[cfg(not(all(
+                tokio_unstable,
+                tokio_taskdump,
+                feature = "rt",
+                target_os = "linux",
+                any(
+                    target_arch = "aarch64",
+                    target_arch = "x86",
+                    target_arch = "x86_64"
+                )
+            )))]
+            $item
+        )*
+    };
+}
+
 macro_rules! cfg_test_util {
     ($($item:item)*) => {
         $(
@@ -334,10 +447,20 @@ macro_rules! cfg_trace {
     ($($item:item)*) => {
         $(
             #[cfg(all(tokio_unstable, feature = "tracing"))]
-            #[cfg_attr(docsrs, doc(cfg(feature = "tracing")))]
+            #[cfg_attr(docsrs, doc(cfg(all(tokio_unstable, feature = "tracing"))))]
             $item
         )*
-    }
+    };
+}
+
+macro_rules! cfg_unstable {
+    ($($item:item)*) => {
+        $(
+            #[cfg(tokio_unstable)]
+            #[cfg_attr(docsrs, doc(cfg(tokio_unstable)))]
+            $item
+        )*
+    };
 }
 
 macro_rules! cfg_not_trace {
@@ -384,3 +507,83 @@ macro_rules! cfg_not_coop {
         )*
     }
 }
+
+macro_rules! cfg_has_atomic_u64 {
+    ($($item:item)*) => {
+        $(
+            #[cfg_attr(
+                not(tokio_no_target_has_atomic),
+                cfg(all(target_has_atomic = "64", not(tokio_no_atomic_u64))
+            ))]
+            #[cfg_attr(
+                tokio_no_target_has_atomic,
+                cfg(not(tokio_no_atomic_u64))
+            )]
+            $item
+        )*
+    }
+}
+
+macro_rules! cfg_not_has_atomic_u64 {
+    ($($item:item)*) => {
+        $(
+            #[cfg_attr(
+                not(tokio_no_target_has_atomic),
+                cfg(any(not(target_has_atomic = "64"), tokio_no_atomic_u64)
+            ))]
+            #[cfg_attr(
+                tokio_no_target_has_atomic,
+                cfg(tokio_no_atomic_u64)
+            )]
+            $item
+        )*
+    }
+}
+
+macro_rules! cfg_has_const_mutex_new {
+    ($($item:item)*) => {
+        $(
+            #[cfg(all(
+                not(all(loom, test)),
+                any(
+                    feature = "parking_lot",
+                    not(tokio_no_const_mutex_new)
+                )
+            ))]
+            $item
+        )*
+    }
+}
+
+macro_rules! cfg_not_has_const_mutex_new {
+    ($($item:item)*) => {
+        $(
+            #[cfg(not(all(
+                not(all(loom, test)),
+                any(
+                    feature = "parking_lot",
+                    not(tokio_no_const_mutex_new)
+                )
+            )))]
+            $item
+        )*
+    }
+}
+
+macro_rules! cfg_not_wasi {
+    ($($item:item)*) => {
+        $(
+            #[cfg(not(tokio_wasi))]
+            $item
+        )*
+    }
+}
+
+macro_rules! cfg_is_wasm_not_wasi {
+    ($($item:item)*) => {
+        $(
+            #[cfg(tokio_wasm_not_wasi)]
+            $item
+        )*
+    }
+}
diff --git a/vendor/tokio/src/macros/join.rs b/vendor/tokio/src/macros/join.rs
index 5f37af510..8a0198600 100644
--- a/vendor/tokio/src/macros/join.rs
+++ b/vendor/tokio/src/macros/join.rs
@@ -1,4 +1,4 @@
-/// Wait on multiple concurrent branches, returning when **all** branches
+/// Waits on multiple concurrent branches, returning when **all** branches
 /// complete.
 ///
 /// The `join!` macro must be used inside of async functions, closures, and
@@ -12,7 +12,7 @@
 /// for **all** branches complete regardless if any complete with `Err`. Use
 /// [`try_join!`] to return early when `Err` is encountered.
 ///
-/// [`try_join!`]: macro@try_join
+/// [`try_join!`]: crate::try_join
 ///
 /// # Notes
 ///
@@ -60,6 +60,9 @@ macro_rules! join {
         // normalization is complete.
         ( $($count:tt)* )
 
+        // The expression `0+1+1+ ... +1` equal to the number of branches.
+        ( $($total:tt)* )
+
         // Normalized join! branches
         $( ( $($skip:tt)* ) $e:expr, )*
 
@@ -69,24 +72,66 @@ macro_rules! join {
 
         // Safety: nothing must be moved out of `futures`. This is to satisfy
         // the requirement of `Pin::new_unchecked` called below.
+        //
+        // We can't use the `pin!` macro for this because `futures` is a tuple
+        // and the standard library provides no way to pin-project to the fields
+        // of a tuple.
         let mut futures = ( $( maybe_done($e), )* );
 
+        // This assignment makes sure that the `poll_fn` closure only has a
+        // reference to the futures, instead of taking ownership of them. This
+        // mitigates the issue described in
+        // <https://internals.rust-lang.org/t/surprising-soundness-trouble-around-pollfn/17484>
+        let mut futures = &mut futures;
+
+        // Each time the future created by poll_fn is polled, a different future will be polled first
+        // to ensure every future passed to join! gets a chance to make progress even if
+        // one of the futures consumes the whole budget.
+        //
+        // This is number of futures that will be skipped in the first loop
+        // iteration the next time.
+        let mut skip_next_time: u32 = 0;
+
         poll_fn(move |cx| {
+            const COUNT: u32 = $($total)*;
+
             let mut is_pending = false;
 
+            let mut to_run = COUNT;
+
+            // The number of futures that will be skipped in the first loop iteration.
+            let mut skip = skip_next_time;
+
+            skip_next_time = if skip + 1 == COUNT { 0 } else { skip + 1 };
+
+            // This loop runs twice and the first `skip` futures
+            // are not polled in the first iteration.
+            loop {
             $(
-                // Extract the future for this branch from the tuple.
-                let ( $($skip,)* fut, .. ) = &mut futures;
+                if skip == 0 {
+                    if to_run == 0 {
+                        // Every future has been polled
+                        break;
+                    }
+                    to_run -= 1;
 
-                // Safety: future is stored on the stack above
-                // and never moved.
-                let mut fut = unsafe { Pin::new_unchecked(fut) };
+                    // Extract the future for this branch from the tuple.
+                    let ( $($skip,)* fut, .. ) = &mut *futures;
 
-                // Try polling
-                if fut.poll(cx).is_pending() {
-                    is_pending = true;
+                    // Safety: future is stored on the stack above
+                    // and never moved.
+                    let mut fut = unsafe { Pin::new_unchecked(fut) };
+
+                    // Try polling
+                    if fut.poll(cx).is_pending() {
+                        is_pending = true;
+                    }
+                } else {
+                    // Future skipped, one less future to skip in the next iteration
+                    skip -= 1;
                 }
             )*
+            }
 
             if is_pending {
                 Pending
@@ -107,13 +152,15 @@ macro_rules! join {
 
     // ===== Normalize =====
 
-    (@ { ( $($s:tt)* ) $($t:tt)* } $e:expr, $($r:tt)* ) => {
-        $crate::join!(@{ ($($s)* _) $($t)* ($($s)*) $e, } $($r)*)
+    (@ { ( $($s:tt)* ) ( $($n:tt)* ) $($t:tt)* } $e:expr, $($r:tt)* ) => {
+        $crate::join!(@{ ($($s)* _) ($($n)* + 1) $($t)* ($($s)*) $e, } $($r)*)
     };
 
     // ===== Entry point =====
 
-    ( $($e:expr),* $(,)?) => {
-        $crate::join!(@{ () } $($e,)*)
+    ( $($e:expr),+ $(,)?) => {
+        $crate::join!(@{ () (0) } $($e,)*)
     };
+
+    () => { async {}.await }
 }
diff --git a/vendor/tokio/src/macros/loom.rs b/vendor/tokio/src/macros/loom.rs
index d57d9fb0f..fa2653ce7 100644
--- a/vendor/tokio/src/macros/loom.rs
+++ b/vendor/tokio/src/macros/loom.rs
@@ -1,11 +1,7 @@
 macro_rules! if_loom {
     ($($t:tt)*) => {{
         #[cfg(loom)]
-        const LOOM: bool = true;
-        #[cfg(not(loom))]
-        const LOOM: bool = false;
-
-        if LOOM {
+        {
             $($t)*
         }
     }}
diff --git a/vendor/tokio/src/macros/mod.rs b/vendor/tokio/src/macros/mod.rs
index b0af52152..82f42dbff 100644
--- a/vendor/tokio/src/macros/mod.rs
+++ b/vendor/tokio/src/macros/mod.rs
@@ -16,8 +16,12 @@ mod ready;
 mod thread_local;
 
 #[macro_use]
-#[cfg(feature = "rt")]
-pub(crate) mod scoped_tls;
+mod addr_of;
+
+cfg_trace! {
+    #[macro_use]
+    mod trace;
+}
 
 cfg_macros! {
     #[macro_use]
diff --git a/vendor/tokio/src/macros/scoped_tls.rs b/vendor/tokio/src/macros/scoped_tls.rs
deleted file mode 100644
index a00aae2fb..000000000
--- a/vendor/tokio/src/macros/scoped_tls.rs
+++ /dev/null
@@ -1,77 +0,0 @@
-use crate::loom::thread::LocalKey;
-
-use std::cell::Cell;
-use std::marker;
-
-/// Set a reference as a thread-local
-macro_rules! scoped_thread_local {
-    ($(#[$attrs:meta])* $vis:vis static $name:ident: $ty:ty) => (
-        $(#[$attrs])*
-        $vis static $name: $crate::macros::scoped_tls::ScopedKey<$ty>
-            = $crate::macros::scoped_tls::ScopedKey {
-                inner: {
-                    thread_local!(static FOO: ::std::cell::Cell<*const ()> = {
-                        std::cell::Cell::new(::std::ptr::null())
-                    });
-                    &FOO
-                },
-                _marker: ::std::marker::PhantomData,
-            };
-    )
-}
-
-/// Type representing a thread local storage key corresponding to a reference
-/// to the type parameter `T`.
-pub(crate) struct ScopedKey<T> {
-    pub(crate) inner: &'static LocalKey<Cell<*const ()>>,
-    pub(crate) _marker: marker::PhantomData<T>,
-}
-
-unsafe impl<T> Sync for ScopedKey<T> {}
-
-impl<T> ScopedKey<T> {
-    /// Inserts a value into this scoped thread local storage slot for a
-    /// duration of a closure.
-    pub(crate) fn set<F, R>(&'static self, t: &T, f: F) -> R
-    where
-        F: FnOnce() -> R,
-    {
-        struct Reset {
-            key: &'static LocalKey<Cell<*const ()>>,
-            val: *const (),
-        }
-
-        impl Drop for Reset {
-            fn drop(&mut self) {
-                self.key.with(|c| c.set(self.val));
-            }
-        }
-
-        let prev = self.inner.with(|c| {
-            let prev = c.get();
-            c.set(t as *const _ as *const ());
-            prev
-        });
-
-        let _reset = Reset {
-            key: self.inner,
-            val: prev,
-        };
-
-        f()
-    }
-
-    /// Gets a value out of this scoped variable.
-    pub(crate) fn with<F, R>(&'static self, f: F) -> R
-    where
-        F: FnOnce(Option<&T>) -> R,
-    {
-        let val = self.inner.with(|c| c.get());
-
-        if val.is_null() {
-            f(None)
-        } else {
-            unsafe { f(Some(&*(val as *const T))) }
-        }
-    }
-}
diff --git a/vendor/tokio/src/macros/select.rs b/vendor/tokio/src/macros/select.rs
index a90ee9eb5..31c9b3ac2 100644
--- a/vendor/tokio/src/macros/select.rs
+++ b/vendor/tokio/src/macros/select.rs
@@ -1,4 +1,4 @@
-/// Wait on multiple concurrent branches, returning when the **first** branch
+/// Waits on multiple concurrent branches, returning when the **first** branch
 /// completes, cancelling the remaining branches.
 ///
 /// The `select!` macro must be used inside of async functions, closures, and
@@ -101,6 +101,7 @@
 ///  * [`tokio::sync::watch::Receiver::changed`](crate::sync::watch::Receiver::changed)
 ///  * [`tokio::net::TcpListener::accept`](crate::net::TcpListener::accept)
 ///  * [`tokio::net::UnixListener::accept`](crate::net::UnixListener::accept)
+///  * [`tokio::signal::unix::Signal::recv`](crate::signal::unix::Signal::recv)
 ///  * [`tokio::io::AsyncReadExt::read`](crate::io::AsyncReadExt::read) on any `AsyncRead`
 ///  * [`tokio::io::AsyncReadExt::read_buf`](crate::io::AsyncReadExt::read_buf) on any `AsyncRead`
 ///  * [`tokio::io::AsyncWriteExt::write`](crate::io::AsyncWriteExt::write) on any `AsyncWrite`
@@ -130,6 +131,13 @@
 /// correctly even if it is restarted while waiting at an `.await`, then it is
 /// cancellation safe.
 ///
+/// Cancellation safety can be defined in the following way: If you have a
+/// future that has not yet completed, then it must be a no-op to drop that
+/// future and recreate it. This definition is motivated by the situation where
+/// a `select!` is used in a loop. Without this guarantee, you would lose your
+/// progress when another branch completes and you restart the `select!` by
+/// going around the loop.
+///
 /// Be aware that cancelling something that is not cancellation safe is not
 /// necessarily wrong. For example, if you are cancelling a task because the
 /// application is shutting down, then you probably don't care that partially
@@ -429,7 +437,8 @@ macro_rules! select {
         //
         // This module is defined within a scope and should not leak out of this
         // macro.
-        mod util {
+        #[doc(hidden)]
+        mod __tokio_select_util {
             // Generate an enum with one variant per select branch
             $crate::select_priv_declare_output_enum!( ( $($count)* ) );
         }
@@ -442,13 +451,13 @@ macro_rules! select {
 
         const BRANCHES: u32 = $crate::count!( $($count)* );
 
-        let mut disabled: util::Mask = Default::default();
+        let mut disabled: __tokio_select_util::Mask = Default::default();
 
         // First, invoke all the pre-conditions. For any that return true,
         // set the appropriate bit in `disabled`.
         $(
             if !$c {
-                let mask: util::Mask = 1 << $crate::count!( $($skip)* );
+                let mask: __tokio_select_util::Mask = 1 << $crate::count!( $($skip)* );
                 disabled |= mask;
             }
         )*
@@ -458,8 +467,18 @@ macro_rules! select {
         let mut output = {
             // Safety: Nothing must be moved out of `futures`. This is to
             // satisfy the requirement of `Pin::new_unchecked` called below.
+            //
+            // We can't use the `pin!` macro for this because `futures` is a
+            // tuple and the standard library provides no way to pin-project to
+            // the fields of a tuple.
             let mut futures = ( $( $fut , )+ );
 
+            // This assignment makes sure that the `poll_fn` closure only has a
+            // reference to the futures, instead of taking ownership of them.
+            // This mitigates the issue described in
+            // <https://internals.rust-lang.org/t/surprising-soundness-trouble-around-pollfn/17484>
+            let mut futures = &mut futures;
+
             $crate::macros::support::poll_fn(|cx| {
                 // Track if any branch returns pending. If no branch completes
                 // **or** returns pending, this implies that all branches are
@@ -495,14 +514,14 @@ macro_rules! select {
 
                                 // Extract the future for this branch from the
                                 // tuple
-                                let ( $($skip,)* fut, .. ) = &mut futures;
+                                let ( $($skip,)* fut, .. ) = &mut *futures;
 
                                 // Safety: future is stored on the stack above
                                 // and never moved.
                                 let mut fut = unsafe { Pin::new_unchecked(fut) };
 
                                 // Try polling it
-                                let out = match fut.poll(cx) {
+                                let out = match Future::poll(fut, cx) {
                                     Ready(out) => out,
                                     Pending => {
                                         // Track that at least one future is
@@ -520,12 +539,12 @@ macro_rules! select {
                                 #[allow(unused_variables)]
                                 #[allow(unused_mut)]
                                 match &out {
-                                    $bind => {}
+                                    $crate::select_priv_clean_pattern!($bind) => {}
                                     _ => continue,
                                 }
 
                                 // The select is complete, return the value
-                                return Ready($crate::select_variant!(util::Out, ($($skip)*))(out));
+                                return Ready($crate::select_variant!(__tokio_select_util::Out, ($($skip)*))(out));
                             }
                         )*
                         _ => unreachable!("reaching this means there probably is an off by one bug"),
@@ -536,16 +555,16 @@ macro_rules! select {
                     Pending
                 } else {
                     // All branches have been disabled.
-                    Ready(util::Out::Disabled)
+                    Ready(__tokio_select_util::Out::Disabled)
                 }
             }).await
         };
 
         match output {
             $(
-                $crate::select_variant!(util::Out, ($($skip)*) ($bind)) => $handle,
+                $crate::select_variant!(__tokio_select_util::Out, ($($skip)*) ($bind)) => $handle,
             )*
-            util::Out::Disabled => $else,
+            __tokio_select_util::Out::Disabled => $else,
             _ => unreachable!("failed to match bind"),
         }
     }};
@@ -801,6 +820,9 @@ macro_rules! count {
     (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => {
         63
     };
+    (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => {
+        64
+    };
 }
 
 #[macro_export]
diff --git a/vendor/tokio/src/macros/support.rs b/vendor/tokio/src/macros/support.rs
index 7f11bc680..10526bcbc 100644
--- a/vendor/tokio/src/macros/support.rs
+++ b/vendor/tokio/src/macros/support.rs
@@ -1,7 +1,11 @@
 cfg_macros! {
     pub use crate::future::poll_fn;
     pub use crate::future::maybe_done::maybe_done;
-    pub use crate::util::thread_rng_n;
+
+    #[doc(hidden)]
+    pub fn thread_rng_n(n: u32) -> u32 {
+        crate::runtime::context::thread_rng_n(n)
+    }
 }
 
 pub use std::future::Future;
diff --git a/vendor/tokio/src/macros/thread_local.rs b/vendor/tokio/src/macros/thread_local.rs
index d84894735..74be99abf 100644
--- a/vendor/tokio/src/macros/thread_local.rs
+++ b/vendor/tokio/src/macros/thread_local.rs
@@ -1,4 +1,32 @@
 #[cfg(all(loom, test))]
-macro_rules! thread_local {
+macro_rules! tokio_thread_local {
+    ($(#[$attrs:meta])* $vis:vis static $name:ident: $ty:ty = const { $expr:expr } $(;)?) => {
+        loom::thread_local! {
+            $(#[$attrs])*
+            $vis static $name: $ty = $expr;
+        }
+    };
+
     ($($tts:tt)+) => { loom::thread_local!{ $($tts)+ } }
 }
+
+#[cfg(not(tokio_no_const_thread_local))]
+#[cfg(not(all(loom, test)))]
+macro_rules! tokio_thread_local {
+    ($($tts:tt)+) => {
+        ::std::thread_local!{ $($tts)+ }
+    }
+}
+
+#[cfg(tokio_no_const_thread_local)]
+#[cfg(not(all(loom, test)))]
+macro_rules! tokio_thread_local {
+    ($(#[$attrs:meta])* $vis:vis static $name:ident: $ty:ty = const { $expr:expr } $(;)?) => {
+        ::std::thread_local! {
+            $(#[$attrs])*
+            $vis static $name: $ty = $expr;
+        }
+    };
+
+    ($($tts:tt)+) => { ::std::thread_local!{ $($tts)+ } }
+}
diff --git a/vendor/tokio/src/macros/trace.rs b/vendor/tokio/src/macros/trace.rs
new file mode 100644
index 000000000..80a257e18
--- /dev/null
+++ b/vendor/tokio/src/macros/trace.rs
@@ -0,0 +1,26 @@
+cfg_trace! {
+    macro_rules! trace_op {
+        ($name:expr, $readiness:literal) => {
+            tracing::trace!(
+                target: "runtime::resource::poll_op",
+                op_name = $name,
+                is_ready = $readiness
+            );
+        }
+    }
+
+    macro_rules! trace_poll_op {
+        ($name:expr, $poll:expr $(,)*) => {
+            match $poll {
+                std::task::Poll::Ready(t) => {
+                    trace_op!($name, true);
+                    std::task::Poll::Ready(t)
+                }
+                std::task::Poll::Pending => {
+                    trace_op!($name, false);
+                    return std::task::Poll::Pending;
+                }
+            }
+        };
+    }
+}
diff --git a/vendor/tokio/src/macros/try_join.rs b/vendor/tokio/src/macros/try_join.rs
index fa5850ef0..7b1237092 100644
--- a/vendor/tokio/src/macros/try_join.rs
+++ b/vendor/tokio/src/macros/try_join.rs
@@ -1,4 +1,4 @@
-/// Wait on multiple concurrent branches, returning when **all** branches
+/// Waits on multiple concurrent branches, returning when **all** branches
 /// complete with `Ok(_)` or on the first `Err(_)`.
 ///
 /// The `try_join!` macro must be used inside of async functions, closures, and
@@ -59,6 +59,45 @@
 ///     }
 /// }
 /// ```
+///
+/// Using `try_join!` with spawned tasks.
+///
+/// ```
+/// use tokio::task::JoinHandle;
+///
+/// async fn do_stuff_async() -> Result<(), &'static str> {
+///     // async work
+/// # Err("failed")
+/// }
+///
+/// async fn more_async_work() -> Result<(), &'static str> {
+///     // more here
+/// # Ok(())
+/// }
+///
+/// async fn flatten<T>(handle: JoinHandle<Result<T, &'static str>>) -> Result<T, &'static str> {
+///     match handle.await {
+///         Ok(Ok(result)) => Ok(result),
+///         Ok(Err(err)) => Err(err),
+///         Err(err) => Err("handling failed"),
+///     }
+/// }
+///
+/// #[tokio::main]
+/// async fn main() {
+///     let handle1 = tokio::spawn(do_stuff_async());
+///     let handle2 = tokio::spawn(more_async_work());
+///     match tokio::try_join!(flatten(handle1), flatten(handle2)) {
+///         Ok(val) => {
+///             // do something with the values
+///         }
+///         Err(err) => {
+///             println!("Failed with {}.", err);
+///             # assert_eq!(err, "failed");
+///         }
+///     }
+/// }
+/// ```
 #[macro_export]
 #[cfg_attr(docsrs, doc(cfg(feature = "macros")))]
 macro_rules! try_join {
@@ -67,6 +106,9 @@ macro_rules! try_join {
         // normalization is complete.
         ( $($count:tt)* )
 
+        // The expression `0+1+1+ ... +1` equal to the number of branches.
+        ( $($total:tt)* )
+
         // Normalized try_join! branches
         $( ( $($skip:tt)* ) $e:expr, )*
 
@@ -76,26 +118,68 @@ macro_rules! try_join {
 
         // Safety: nothing must be moved out of `futures`. This is to satisfy
         // the requirement of `Pin::new_unchecked` called below.
+        //
+        // We can't use the `pin!` macro for this because `futures` is a tuple
+        // and the standard library provides no way to pin-project to the fields
+        // of a tuple.
         let mut futures = ( $( maybe_done($e), )* );
 
+        // This assignment makes sure that the `poll_fn` closure only has a
+        // reference to the futures, instead of taking ownership of them. This
+        // mitigates the issue described in
+        // <https://internals.rust-lang.org/t/surprising-soundness-trouble-around-pollfn/17484>
+        let mut futures = &mut futures;
+
+        // Each time the future created by poll_fn is polled, a different future will be polled first
+        // to ensure every future passed to join! gets a chance to make progress even if
+        // one of the futures consumes the whole budget.
+        //
+        // This is number of futures that will be skipped in the first loop
+        // iteration the next time.
+        let mut skip_next_time: u32 = 0;
+
         poll_fn(move |cx| {
+            const COUNT: u32 = $($total)*;
+
             let mut is_pending = false;
 
+            let mut to_run = COUNT;
+
+            // The number of futures that will be skipped in the first loop iteration
+            let mut skip = skip_next_time;
+
+            skip_next_time = if skip + 1 == COUNT { 0 } else { skip + 1 };
+
+            // This loop runs twice and the first `skip` futures
+            // are not polled in the first iteration.
+            loop {
             $(
-                // Extract the future for this branch from the tuple.
-                let ( $($skip,)* fut, .. ) = &mut futures;
-
-                // Safety: future is stored on the stack above
-                // and never moved.
-                let mut fut = unsafe { Pin::new_unchecked(fut) };
-
-                // Try polling
-                if fut.as_mut().poll(cx).is_pending() {
-                    is_pending = true;
-                } else if fut.as_mut().output_mut().expect("expected completed future").is_err() {
-                    return Ready(Err(fut.take_output().expect("expected completed future").err().unwrap()))
+                if skip == 0 {
+                    if to_run == 0 {
+                        // Every future has been polled
+                        break;
+                    }
+                    to_run -= 1;
+
+                    // Extract the future for this branch from the tuple.
+                    let ( $($skip,)* fut, .. ) = &mut *futures;
+
+                    // Safety: future is stored on the stack above
+                    // and never moved.
+                    let mut fut = unsafe { Pin::new_unchecked(fut) };
+
+                    // Try polling
+                    if fut.as_mut().poll(cx).is_pending() {
+                        is_pending = true;
+                    } else if fut.as_mut().output_mut().expect("expected completed future").is_err() {
+                        return Ready(Err(fut.take_output().expect("expected completed future").err().unwrap()))
+                    }
+                } else {
+                    // Future skipped, one less future to skip in the next iteration
+                    skip -= 1;
                 }
             )*
+            }
 
             if is_pending {
                 Pending
@@ -120,13 +204,15 @@ macro_rules! try_join {
 
     // ===== Normalize =====
 
-    (@ { ( $($s:tt)* ) $($t:tt)* } $e:expr, $($r:tt)* ) => {
-        $crate::try_join!(@{ ($($s)* _) $($t)* ($($s)*) $e, } $($r)*)
+    (@ { ( $($s:tt)* ) ( $($n:tt)* ) $($t:tt)* } $e:expr, $($r:tt)* ) => {
+      $crate::try_join!(@{ ($($s)* _) ($($n)* + 1) $($t)* ($($s)*) $e, } $($r)*)
     };
 
     // ===== Entry point =====
 
-    ( $($e:expr),* $(,)?) => {
-        $crate::try_join!(@{ () } $($e,)*)
+    ( $($e:expr),+ $(,)?) => {
+        $crate::try_join!(@{ () (0) } $($e,)*)
     };
+
+    () => { async { Ok(()) }.await }
 }
diff --git a/vendor/tokio/src/net/addr.rs b/vendor/tokio/src/net/addr.rs
index ec4fa198e..fb8248fb3 100644
--- a/vendor/tokio/src/net/addr.rs
+++ b/vendor/tokio/src/net/addr.rs
@@ -1,5 +1,4 @@
-use crate::future;
-
+use std::future;
 use std::io;
 use std::net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr, SocketAddrV4, SocketAddrV6};
 
@@ -56,7 +55,7 @@ impl sealed::ToSocketAddrsPriv for SocketAddr {
 
     fn to_socket_addrs(&self, _: sealed::Internal) -> Self::Future {
         let iter = Some(*self).into_iter();
-        future::ok(iter)
+        future::ready(Ok(iter))
     }
 }
 
@@ -96,7 +95,7 @@ impl sealed::ToSocketAddrsPriv for (IpAddr, u16) {
 
     fn to_socket_addrs(&self, _: sealed::Internal) -> Self::Future {
         let iter = Some(SocketAddr::from(*self)).into_iter();
-        future::ok(iter)
+        future::ready(Ok(iter))
     }
 }
 
@@ -137,8 +136,23 @@ impl sealed::ToSocketAddrsPriv for &[SocketAddr] {
     type Future = ReadyFuture<Self::Iter>;
 
     fn to_socket_addrs(&self, _: sealed::Internal) -> Self::Future {
-        let iter = self.to_vec().into_iter();
-        future::ok(iter)
+        #[inline]
+        fn slice_to_vec(addrs: &[SocketAddr]) -> Vec<SocketAddr> {
+            addrs.to_vec()
+        }
+
+        // This uses a helper method because clippy doesn't like the `to_vec()`
+        // call here (it will allocate, whereas `self.iter().copied()` would
+        // not), but it's actually necessary in order to ensure that the
+        // returned iterator is valid for the `'static` lifetime, which the
+        // borrowed `slice::Iter` iterator would not be.
+        //
+        // Note that we can't actually add an `allow` attribute for
+        // `clippy::unnecessary_to_owned` here, as Tokio's CI runs clippy lints
+        // on Rust 1.52 to avoid breaking LTS releases of Tokio. Users of newer
+        // Rust versions who see this lint should just ignore it.
+        let iter = slice_to_vec(self).into_iter();
+        future::ready(Ok(iter))
     }
 }
 
@@ -230,7 +244,7 @@ cfg_net! {
         type Future = <str as sealed::ToSocketAddrsPriv>::Future;
 
         fn to_socket_addrs(&self, _: sealed::Internal) -> Self::Future {
-            (&self[..]).to_socket_addrs(sealed::Internal)
+            self[..].to_socket_addrs(sealed::Internal)
         }
     }
 }
diff --git a/vendor/tokio/src/net/mod.rs b/vendor/tokio/src/net/mod.rs
index 0b8c1ecd1..2d317a8a2 100644
--- a/vendor/tokio/src/net/mod.rs
+++ b/vendor/tokio/src/net/mod.rs
@@ -23,8 +23,10 @@
 //! [`UnixDatagram`]: UnixDatagram
 
 mod addr;
-#[cfg(feature = "net")]
-pub(crate) use addr::to_socket_addrs;
+cfg_not_wasi! {
+    #[cfg(feature = "net")]
+    pub(crate) use addr::to_socket_addrs;
+}
 pub use addr::ToSocketAddrs;
 
 cfg_net! {
@@ -33,11 +35,13 @@ cfg_net! {
 
     pub mod tcp;
     pub use tcp::listener::TcpListener;
-    pub use tcp::socket::TcpSocket;
     pub use tcp::stream::TcpStream;
+    cfg_not_wasi! {
+        pub use tcp::socket::TcpSocket;
 
-    mod udp;
-    pub use udp::UdpSocket;
+        mod udp;
+        pub use udp::UdpSocket;
+    }
 }
 
 cfg_net_unix! {
diff --git a/vendor/tokio/src/net/tcp/listener.rs b/vendor/tokio/src/net/tcp/listener.rs
index 86f0ec1d2..34e393c89 100644
--- a/vendor/tokio/src/net/tcp/listener.rs
+++ b/vendor/tokio/src/net/tcp/listener.rs
@@ -1,8 +1,10 @@
 use crate::io::{Interest, PollEvented};
 use crate::net::tcp::TcpStream;
-use crate::net::{to_socket_addrs, ToSocketAddrs};
 
-use std::convert::TryFrom;
+cfg_not_wasi! {
+    use crate::net::{to_socket_addrs, ToSocketAddrs};
+}
+
 use std::fmt;
 use std::io;
 use std::net::{self, SocketAddr};
@@ -55,68 +57,70 @@ cfg_net! {
 }
 
 impl TcpListener {
-    /// Creates a new TcpListener, which will be bound to the specified address.
-    ///
-    /// The returned listener is ready for accepting connections.
-    ///
-    /// Binding with a port number of 0 will request that the OS assigns a port
-    /// to this listener. The port allocated can be queried via the `local_addr`
-    /// method.
-    ///
-    /// The address type can be any implementor of the [`ToSocketAddrs`] trait.
-    /// If `addr` yields multiple addresses, bind will be attempted with each of
-    /// the addresses until one succeeds and returns the listener. If none of
-    /// the addresses succeed in creating a listener, the error returned from
-    /// the last attempt (the last address) is returned.
-    ///
-    /// This function sets the `SO_REUSEADDR` option on the socket.
-    ///
-    /// To configure the socket before binding, you can use the [`TcpSocket`]
-    /// type.
-    ///
-    /// [`ToSocketAddrs`]: trait@crate::net::ToSocketAddrs
-    /// [`TcpSocket`]: struct@crate::net::TcpSocket
-    ///
-    /// # Examples
-    ///
-    /// ```no_run
-    /// use tokio::net::TcpListener;
-    ///
-    /// use std::io;
-    ///
-    /// #[tokio::main]
-    /// async fn main() -> io::Result<()> {
-    ///     let listener = TcpListener::bind("127.0.0.1:2345").await?;
-    ///
-    ///     // use the listener
-    ///
-    ///     # let _ = listener;
-    ///     Ok(())
-    /// }
-    /// ```
-    pub async fn bind<A: ToSocketAddrs>(addr: A) -> io::Result<TcpListener> {
-        let addrs = to_socket_addrs(addr).await?;
+    cfg_not_wasi! {
+        /// Creates a new TcpListener, which will be bound to the specified address.
+        ///
+        /// The returned listener is ready for accepting connections.
+        ///
+        /// Binding with a port number of 0 will request that the OS assigns a port
+        /// to this listener. The port allocated can be queried via the `local_addr`
+        /// method.
+        ///
+        /// The address type can be any implementor of the [`ToSocketAddrs`] trait.
+        /// If `addr` yields multiple addresses, bind will be attempted with each of
+        /// the addresses until one succeeds and returns the listener. If none of
+        /// the addresses succeed in creating a listener, the error returned from
+        /// the last attempt (the last address) is returned.
+        ///
+        /// This function sets the `SO_REUSEADDR` option on the socket.
+        ///
+        /// To configure the socket before binding, you can use the [`TcpSocket`]
+        /// type.
+        ///
+        /// [`ToSocketAddrs`]: trait@crate::net::ToSocketAddrs
+        /// [`TcpSocket`]: struct@crate::net::TcpSocket
+        ///
+        /// # Examples
+        ///
+        /// ```no_run
+        /// use tokio::net::TcpListener;
+        ///
+        /// use std::io;
+        ///
+        /// #[tokio::main]
+        /// async fn main() -> io::Result<()> {
+        ///     let listener = TcpListener::bind("127.0.0.1:2345").await?;
+        ///
+        ///     // use the listener
+        ///
+        ///     # let _ = listener;
+        ///     Ok(())
+        /// }
+        /// ```
+        pub async fn bind<A: ToSocketAddrs>(addr: A) -> io::Result<TcpListener> {
+            let addrs = to_socket_addrs(addr).await?;
 
-        let mut last_err = None;
+            let mut last_err = None;
 
-        for addr in addrs {
-            match TcpListener::bind_addr(addr) {
-                Ok(listener) => return Ok(listener),
-                Err(e) => last_err = Some(e),
+            for addr in addrs {
+                match TcpListener::bind_addr(addr) {
+                    Ok(listener) => return Ok(listener),
+                    Err(e) => last_err = Some(e),
+                }
             }
-        }
 
-        Err(last_err.unwrap_or_else(|| {
-            io::Error::new(
-                io::ErrorKind::InvalidInput,
-                "could not resolve to any address",
-            )
-        }))
-    }
+            Err(last_err.unwrap_or_else(|| {
+                io::Error::new(
+                    io::ErrorKind::InvalidInput,
+                    "could not resolve to any address",
+                )
+            }))
+        }
 
-    fn bind_addr(addr: SocketAddr) -> io::Result<TcpListener> {
-        let listener = mio::net::TcpListener::bind(addr)?;
-        TcpListener::new(listener)
+        fn bind_addr(addr: SocketAddr) -> io::Result<TcpListener> {
+            let listener = mio::net::TcpListener::bind(addr)?;
+            TcpListener::new(listener)
+        }
     }
 
     /// Accepts a new incoming connection from this listener.
@@ -190,15 +194,22 @@ impl TcpListener {
     /// Creates new `TcpListener` from a `std::net::TcpListener`.
     ///
     /// This function is intended to be used to wrap a TCP listener from the
-    /// standard library in the Tokio equivalent. The conversion assumes nothing
-    /// about the underlying listener; it is left up to the user to set it in
-    /// non-blocking mode.
+    /// standard library in the Tokio equivalent.
     ///
     /// This API is typically paired with the `socket2` crate and the `Socket`
     /// type to build up and customize a listener before it's shipped off to the
     /// backing event loop. This allows configuration of options like
     /// `SO_REUSEPORT`, binding to multiple addresses, etc.
     ///
+    /// # Notes
+    ///
+    /// The caller is responsible for ensuring that the listener is in
+    /// non-blocking mode. Otherwise all I/O operations on the listener
+    /// will block the thread, which will cause unexpected behavior.
+    /// Non-blocking mode can be set using [`set_nonblocking`].
+    ///
+    /// [`set_nonblocking`]: std::net::TcpListener::set_nonblocking
+    ///
     /// # Examples
     ///
     /// ```rust,no_run
@@ -216,18 +227,20 @@ impl TcpListener {
     ///
     /// # Panics
     ///
-    /// This function panics if thread-local runtime is not set.
+    /// This function panics if it is not called from within a runtime with
+    /// IO enabled.
     ///
     /// The runtime is usually set implicitly when this function is called
     /// from a future driven by a tokio runtime, otherwise runtime can be set
     /// explicitly with [`Runtime::enter`](crate::runtime::Runtime::enter) function.
+    #[track_caller]
     pub fn from_std(listener: net::TcpListener) -> io::Result<TcpListener> {
         let io = mio::net::TcpListener::from_std(listener);
         let io = PollEvented::new(io)?;
         Ok(TcpListener { io })
     }
 
-    /// Turn a [`tokio::net::TcpListener`] into a [`std::net::TcpListener`].
+    /// Turns a [`tokio::net::TcpListener`] into a [`std::net::TcpListener`].
     ///
     /// The returned [`std::net::TcpListener`] will have nonblocking mode set as
     /// `true`.  Use [`set_nonblocking`] to change the blocking mode if needed.
@@ -267,11 +280,22 @@ impl TcpListener {
                 .map(|io| io.into_raw_socket())
                 .map(|raw_socket| unsafe { std::net::TcpListener::from_raw_socket(raw_socket) })
         }
+
+        #[cfg(tokio_wasi)]
+        {
+            use std::os::wasi::io::{FromRawFd, IntoRawFd};
+            self.io
+                .into_inner()
+                .map(|io| io.into_raw_fd())
+                .map(|raw_fd| unsafe { std::net::TcpListener::from_raw_fd(raw_fd) })
+        }
     }
 
-    pub(crate) fn new(listener: mio::net::TcpListener) -> io::Result<TcpListener> {
-        let io = PollEvented::new(listener)?;
-        Ok(TcpListener { io })
+    cfg_not_wasi! {
+        pub(crate) fn new(listener: mio::net::TcpListener) -> io::Result<TcpListener> {
+            let io = PollEvented::new(listener)?;
+            Ok(TcpListener { io })
+        }
     }
 
     /// Returns the local address that this listener is bound to.
@@ -382,16 +406,51 @@ mod sys {
             self.io.as_raw_fd()
         }
     }
+
+    #[cfg(not(tokio_no_as_fd))]
+    impl AsFd for TcpListener {
+        fn as_fd(&self) -> BorrowedFd<'_> {
+            unsafe { BorrowedFd::borrow_raw(self.as_raw_fd()) }
+        }
+    }
 }
 
-#[cfg(windows)]
-mod sys {
-    use super::TcpListener;
-    use std::os::windows::prelude::*;
+cfg_unstable! {
+    #[cfg(tokio_wasi)]
+    mod sys {
+        use super::TcpListener;
+        use std::os::wasi::prelude::*;
+
+        impl AsRawFd for TcpListener {
+            fn as_raw_fd(&self) -> RawFd {
+                self.io.as_raw_fd()
+            }
+        }
+
+        #[cfg(not(tokio_no_as_fd))]
+        impl AsFd for TcpListener {
+            fn as_fd(&self) -> BorrowedFd<'_> {
+                unsafe { BorrowedFd::borrow_raw(self.as_raw_fd()) }
+            }
+        }
+    }
+}
+
+cfg_windows! {
+    use crate::os::windows::io::{AsRawSocket, RawSocket};
+    #[cfg(not(tokio_no_as_fd))]
+    use crate::os::windows::io::{AsSocket, BorrowedSocket};
 
     impl AsRawSocket for TcpListener {
         fn as_raw_socket(&self) -> RawSocket {
             self.io.as_raw_socket()
         }
     }
+
+    #[cfg(not(tokio_no_as_fd))]
+    impl AsSocket for TcpListener {
+        fn as_socket(&self) -> BorrowedSocket<'_> {
+            unsafe { BorrowedSocket::borrow_raw(self.as_raw_socket()) }
+        }
+    }
 }
diff --git a/vendor/tokio/src/net/tcp/mod.rs b/vendor/tokio/src/net/tcp/mod.rs
index 7f0f6d914..734eabe6d 100644
--- a/vendor/tokio/src/net/tcp/mod.rs
+++ b/vendor/tokio/src/net/tcp/mod.rs
@@ -1,8 +1,10 @@
-//! TCP utility types
+//! TCP utility types.
 
 pub(crate) mod listener;
 
-pub(crate) mod socket;
+cfg_not_wasi! {
+    pub(crate) mod socket;
+}
 
 mod split;
 pub use split::{ReadHalf, WriteHalf};
diff --git a/vendor/tokio/src/net/tcp/socket.rs b/vendor/tokio/src/net/tcp/socket.rs
index 02cb6377e..df792f9a6 100644
--- a/vendor/tokio/src/net/tcp/socket.rs
+++ b/vendor/tokio/src/net/tcp/socket.rs
@@ -4,10 +4,17 @@ use std::fmt;
 use std::io;
 use std::net::SocketAddr;
 
+#[cfg(all(unix, not(tokio_no_as_fd)))]
+use std::os::unix::io::{AsFd, BorrowedFd};
 #[cfg(unix)]
 use std::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
-#[cfg(windows)]
-use std::os::windows::io::{AsRawSocket, FromRawSocket, IntoRawSocket, RawSocket};
+use std::time::Duration;
+
+cfg_windows! {
+    use crate::os::windows::io::{AsRawSocket, FromRawSocket, IntoRawSocket, RawSocket};
+    #[cfg(not(tokio_no_as_fd))]
+    use crate::os::windows::io::{AsSocket, BorrowedSocket};
+}
 
 cfg_net! {
     /// A TCP socket that has not yet been converted to a `TcpStream` or
@@ -81,13 +88,14 @@ cfg_net! {
     /// [`AsRawFd`]: https://doc.rust-lang.org/std/os/unix/io/trait.AsRawFd.html
     /// [`AsRawSocket`]: https://doc.rust-lang.org/std/os/windows/io/trait.AsRawSocket.html
     /// [`socket2`]: https://docs.rs/socket2/
+    #[cfg_attr(docsrs, doc(alias = "connect_std"))]
     pub struct TcpSocket {
-        inner: mio::net::TcpSocket,
+        inner: socket2::Socket,
     }
 }
 
 impl TcpSocket {
-    /// Create a new socket configured for IPv4.
+    /// Creates a new socket configured for IPv4.
     ///
     /// Calls `socket(2)` with `AF_INET` and `SOCK_STREAM`.
     ///
@@ -117,11 +125,10 @@ impl TcpSocket {
     /// }
     /// ```
     pub fn new_v4() -> io::Result<TcpSocket> {
-        let inner = mio::net::TcpSocket::new_v4()?;
-        Ok(TcpSocket { inner })
+        TcpSocket::new(socket2::Domain::IPV4)
     }
 
-    /// Create a new socket configured for IPv6.
+    /// Creates a new socket configured for IPv6.
     ///
     /// Calls `socket(2)` with `AF_INET6` and `SOCK_STREAM`.
     ///
@@ -151,11 +158,38 @@ impl TcpSocket {
     /// }
     /// ```
     pub fn new_v6() -> io::Result<TcpSocket> {
-        let inner = mio::net::TcpSocket::new_v6()?;
+        TcpSocket::new(socket2::Domain::IPV6)
+    }
+
+    fn new(domain: socket2::Domain) -> io::Result<TcpSocket> {
+        let ty = socket2::Type::STREAM;
+        #[cfg(any(
+            target_os = "android",
+            target_os = "dragonfly",
+            target_os = "freebsd",
+            target_os = "fuchsia",
+            target_os = "illumos",
+            target_os = "linux",
+            target_os = "netbsd",
+            target_os = "openbsd"
+        ))]
+        let ty = ty.nonblocking();
+        let inner = socket2::Socket::new(domain, ty, Some(socket2::Protocol::TCP))?;
+        #[cfg(not(any(
+            target_os = "android",
+            target_os = "dragonfly",
+            target_os = "freebsd",
+            target_os = "fuchsia",
+            target_os = "illumos",
+            target_os = "linux",
+            target_os = "netbsd",
+            target_os = "openbsd"
+        )))]
+        inner.set_nonblocking(true)?;
         Ok(TcpSocket { inner })
     }
 
-    /// Allow the socket to bind to an in-use address.
+    /// Allows the socket to bind to an in-use address.
     ///
     /// Behavior is platform specific. Refer to the target platform's
     /// documentation for more details.
@@ -182,10 +216,10 @@ impl TcpSocket {
     /// }
     /// ```
     pub fn set_reuseaddr(&self, reuseaddr: bool) -> io::Result<()> {
-        self.inner.set_reuseaddr(reuseaddr)
+        self.inner.set_reuse_address(reuseaddr)
     }
 
-    /// Retrieves the value set for `SO_REUSEADDR` on this socket
+    /// Retrieves the value set for `SO_REUSEADDR` on this socket.
     ///
     /// # Examples
     ///
@@ -208,10 +242,10 @@ impl TcpSocket {
     /// }
     /// ```
     pub fn reuseaddr(&self) -> io::Result<bool> {
-        self.inner.get_reuseaddr()
+        self.inner.reuse_address()
     }
 
-    /// Allow the socket to bind to an in-use port. Only available for unix systems
+    /// Allows the socket to bind to an in-use port. Only available for unix systems
     /// (excluding Solaris & Illumos).
     ///
     /// Behavior is platform specific. Refer to the target platform's
@@ -242,10 +276,10 @@ impl TcpSocket {
         doc(cfg(all(unix, not(target_os = "solaris"), not(target_os = "illumos"))))
     )]
     pub fn set_reuseport(&self, reuseport: bool) -> io::Result<()> {
-        self.inner.set_reuseport(reuseport)
+        self.inner.set_reuse_port(reuseport)
     }
 
-    /// Allow the socket to bind to an in-use port. Only available for unix systems
+    /// Allows the socket to bind to an in-use port. Only available for unix systems
     /// (excluding Solaris & Illumos).
     ///
     /// Behavior is platform specific. Refer to the target platform's
@@ -277,14 +311,14 @@ impl TcpSocket {
         doc(cfg(all(unix, not(target_os = "solaris"), not(target_os = "illumos"))))
     )]
     pub fn reuseport(&self) -> io::Result<bool> {
-        self.inner.get_reuseport()
+        self.inner.reuse_port()
     }
 
     /// Sets the size of the TCP send buffer on this socket.
     ///
     /// On most operating systems, this sets the `SO_SNDBUF` socket option.
     pub fn set_send_buffer_size(&self, size: u32) -> io::Result<()> {
-        self.inner.set_send_buffer_size(size)
+        self.inner.set_send_buffer_size(size as usize)
     }
 
     /// Returns the size of the TCP send buffer for this socket.
@@ -311,14 +345,14 @@ impl TcpSocket {
     ///
     /// [`set_send_buffer_size`]: #method.set_send_buffer_size
     pub fn send_buffer_size(&self) -> io::Result<u32> {
-        self.inner.get_send_buffer_size()
+        self.inner.send_buffer_size().map(|n| n as u32)
     }
 
     /// Sets the size of the TCP receive buffer on this socket.
     ///
     /// On most operating systems, this sets the `SO_RCVBUF` socket option.
     pub fn set_recv_buffer_size(&self, size: u32) -> io::Result<()> {
-        self.inner.set_recv_buffer_size(size)
+        self.inner.set_recv_buffer_size(size as usize)
     }
 
     /// Returns the size of the TCP receive buffer for this socket.
@@ -345,10 +379,160 @@ impl TcpSocket {
     ///
     /// [`set_recv_buffer_size`]: #method.set_recv_buffer_size
     pub fn recv_buffer_size(&self) -> io::Result<u32> {
-        self.inner.get_recv_buffer_size()
+        self.inner.recv_buffer_size().map(|n| n as u32)
+    }
+
+    /// Sets the linger duration of this socket by setting the SO_LINGER option.
+    ///
+    /// This option controls the action taken when a stream has unsent messages and the stream is
+    /// closed. If SO_LINGER is set, the system shall block the process until it can transmit the
+    /// data or until the time expires.
+    ///
+    /// If SO_LINGER is not specified, and the socket is closed, the system handles the call in a
+    /// way that allows the process to continue as quickly as possible.
+    pub fn set_linger(&self, dur: Option<Duration>) -> io::Result<()> {
+        self.inner.set_linger(dur)
+    }
+
+    /// Reads the linger duration for this socket by getting the `SO_LINGER`
+    /// option.
+    ///
+    /// For more information about this option, see [`set_linger`].
+    ///
+    /// [`set_linger`]: TcpSocket::set_linger
+    pub fn linger(&self) -> io::Result<Option<Duration>> {
+        self.inner.linger()
+    }
+
+    /// Sets the value of the `TCP_NODELAY` option on this socket.
+    ///
+    /// If set, this option disables the Nagle algorithm. This means that segments are always
+    /// sent as soon as possible, even if there is only a small amount of data. When not set,
+    /// data is buffered until there is a sufficient amount to send out, thereby avoiding
+    /// the frequent sending of small packets.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpSocket;
+    ///
+    /// # async fn dox() -> Result<(), Box<dyn std::error::Error>> {
+    /// let socket = TcpSocket::new_v4()?;
+    ///
+    /// println!("{:?}", socket.nodelay()?);
+    /// # Ok(())
+    /// # }
+    /// ```
+    pub fn set_nodelay(&self, nodelay: bool) -> io::Result<()> {
+        self.inner.set_nodelay(nodelay)
+    }
+
+    /// Gets the value of the `TCP_NODELAY` option on this socket.
+    ///
+    /// For more information about this option, see [`set_nodelay`].
+    ///
+    /// [`set_nodelay`]: TcpSocket::set_nodelay
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::TcpSocket;
+    ///
+    /// # async fn dox() -> Result<(), Box<dyn std::error::Error>> {
+    /// let stream = TcpSocket::new_v4()?;
+    ///
+    /// stream.set_nodelay(true)?;
+    /// # Ok(())
+    /// # }
+    /// ```
+    pub fn nodelay(&self) -> io::Result<bool> {
+        self.inner.nodelay()
     }
 
-    /// Get the local address of this socket.
+    /// Gets the value of the `IP_TOS` option for this socket.
+    ///
+    /// For more information about this option, see [`set_tos`].
+    ///
+    /// **NOTE:** On Windows, `IP_TOS` is only supported on [Windows 8+ or
+    /// Windows Server 2012+.](https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-ip-socket-options)
+    ///
+    /// [`set_tos`]: Self::set_tos
+    // https://docs.rs/socket2/0.4.2/src/socket2/socket.rs.html#1178
+    #[cfg(not(any(
+        target_os = "fuchsia",
+        target_os = "redox",
+        target_os = "solaris",
+        target_os = "illumos",
+    )))]
+    #[cfg_attr(
+        docsrs,
+        doc(cfg(not(any(
+            target_os = "fuchsia",
+            target_os = "redox",
+            target_os = "solaris",
+            target_os = "illumos",
+        ))))
+    )]
+    pub fn tos(&self) -> io::Result<u32> {
+        self.inner.tos()
+    }
+
+    /// Sets the value for the `IP_TOS` option on this socket.
+    ///
+    /// This value sets the type-of-service field that is used in every packet
+    /// sent from this socket.
+    ///
+    /// **NOTE:** On Windows, `IP_TOS` is only supported on [Windows 8+ or
+    /// Windows Server 2012+.](https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-ip-socket-options)
+    // https://docs.rs/socket2/0.4.2/src/socket2/socket.rs.html#1178
+    #[cfg(not(any(
+        target_os = "fuchsia",
+        target_os = "redox",
+        target_os = "solaris",
+        target_os = "illumos",
+    )))]
+    #[cfg_attr(
+        docsrs,
+        doc(cfg(not(any(
+            target_os = "fuchsia",
+            target_os = "redox",
+            target_os = "solaris",
+            target_os = "illumos",
+        ))))
+    )]
+    pub fn set_tos(&self, tos: u32) -> io::Result<()> {
+        self.inner.set_tos(tos)
+    }
+
+    /// Gets the value for the `SO_BINDTODEVICE` option on this socket
+    ///
+    /// This value gets the socket binded device's interface name.
+    #[cfg(any(target_os = "android", target_os = "fuchsia", target_os = "linux",))]
+    #[cfg_attr(
+        docsrs,
+        doc(cfg(any(target_os = "android", target_os = "fuchsia", target_os = "linux",)))
+    )]
+    pub fn device(&self) -> io::Result<Option<Vec<u8>>> {
+        self.inner.device()
+    }
+
+    /// Sets the value for the `SO_BINDTODEVICE` option on this socket
+    ///
+    /// If a socket is bound to an interface, only packets received from that
+    /// particular interface are processed by the socket. Note that this only
+    /// works for some socket types, particularly `AF_INET` sockets.
+    ///
+    /// If `interface` is `None` or an empty string it removes the binding.
+    #[cfg(all(any(target_os = "android", target_os = "fuchsia", target_os = "linux")))]
+    #[cfg_attr(
+        docsrs,
+        doc(cfg(all(any(target_os = "android", target_os = "fuchsia", target_os = "linux"))))
+    )]
+    pub fn bind_device(&self, interface: Option<&[u8]>) -> io::Result<()> {
+        self.inner.bind_device(interface)
+    }
+
+    /// Gets the local address of this socket.
     ///
     /// Will fail on windows if called before `bind`.
     ///
@@ -371,10 +555,15 @@ impl TcpSocket {
     /// }
     /// ```
     pub fn local_addr(&self) -> io::Result<SocketAddr> {
-        self.inner.get_localaddr()
+        self.inner.local_addr().and_then(convert_address)
+    }
+
+    /// Returns the value of the `SO_ERROR` option.
+    pub fn take_error(&self) -> io::Result<Option<io::Error>> {
+        self.inner.take_error()
     }
 
-    /// Bind the socket to the given address.
+    /// Binds the socket to the given address.
     ///
     /// This calls the `bind(2)` operating-system function. Behavior is
     /// platform specific. Refer to the target platform's documentation for more
@@ -403,10 +592,10 @@ impl TcpSocket {
     /// }
     /// ```
     pub fn bind(&self, addr: SocketAddr) -> io::Result<()> {
-        self.inner.bind(addr)
+        self.inner.bind(&addr.into())
     }
 
-    /// Establish a TCP connection with a peer at the specified socket address.
+    /// Establishes a TCP connection with a peer at the specified socket address.
     ///
     /// The `TcpSocket` is consumed. Once the connection is established, a
     /// connected [`TcpStream`] is returned. If the connection fails, the
@@ -439,11 +628,36 @@ impl TcpSocket {
     /// }
     /// ```
     pub async fn connect(self, addr: SocketAddr) -> io::Result<TcpStream> {
-        let mio = self.inner.connect(addr)?;
+        if let Err(err) = self.inner.connect(&addr.into()) {
+            #[cfg(unix)]
+            if err.raw_os_error() != Some(libc::EINPROGRESS) {
+                return Err(err);
+            }
+            #[cfg(windows)]
+            if err.kind() != io::ErrorKind::WouldBlock {
+                return Err(err);
+            }
+        }
+        #[cfg(unix)]
+        let mio = {
+            use std::os::unix::io::{FromRawFd, IntoRawFd};
+
+            let raw_fd = self.inner.into_raw_fd();
+            unsafe { mio::net::TcpStream::from_raw_fd(raw_fd) }
+        };
+
+        #[cfg(windows)]
+        let mio = {
+            use std::os::windows::io::{FromRawSocket, IntoRawSocket};
+
+            let raw_socket = self.inner.into_raw_socket();
+            unsafe { mio::net::TcpStream::from_raw_socket(raw_socket) }
+        };
+
         TcpStream::connect_mio(mio).await
     }
 
-    /// Convert the socket into a `TcpListener`.
+    /// Converts the socket into a `TcpListener`.
     ///
     /// `backlog` defines the maximum number of pending connections are queued
     /// by the operating system at any given time. Connection are removed from
@@ -479,7 +693,23 @@ impl TcpSocket {
     /// }
     /// ```
     pub fn listen(self, backlog: u32) -> io::Result<TcpListener> {
-        let mio = self.inner.listen(backlog)?;
+        self.inner.listen(backlog as i32)?;
+        #[cfg(unix)]
+        let mio = {
+            use std::os::unix::io::{FromRawFd, IntoRawFd};
+
+            let raw_fd = self.inner.into_raw_fd();
+            unsafe { mio::net::TcpListener::from_raw_fd(raw_fd) }
+        };
+
+        #[cfg(windows)]
+        let mio = {
+            use std::os::windows::io::{FromRawSocket, IntoRawSocket};
+
+            let raw_socket = self.inner.into_raw_socket();
+            unsafe { mio::net::TcpListener::from_raw_socket(raw_socket) }
+        };
+
         TcpListener::new(mio)
     }
 
@@ -491,6 +721,15 @@ impl TcpSocket {
     /// [`std::net::TcpStream`]: struct@std::net::TcpStream
     /// [`socket2`]: https://docs.rs/socket2/
     ///
+    /// # Notes
+    ///
+    /// The caller is responsible for ensuring that the socket is in
+    /// non-blocking mode. Otherwise all I/O operations on the socket
+    /// will block the thread, which will cause unexpected behavior.
+    /// Non-blocking mode can be set using [`set_nonblocking`].
+    ///
+    /// [`set_nonblocking`]: std::net::TcpStream::set_nonblocking
+    ///
     /// # Examples
     ///
     /// ```
@@ -499,8 +738,8 @@ impl TcpSocket {
     ///
     /// #[tokio::main]
     /// async fn main() -> std::io::Result<()> {
-    ///     
     ///     let socket2_socket = Socket::new(Domain::IPV4, Type::STREAM, None)?;
+    ///     socket2_socket.set_nonblocking(true)?;
     ///
     ///     let socket = TcpSocket::from_std_stream(socket2_socket.into());
     ///
@@ -526,6 +765,16 @@ impl TcpSocket {
     }
 }
 
+fn convert_address(address: socket2::SockAddr) -> io::Result<SocketAddr> {
+    match address.as_socket() {
+        Some(address) => Ok(address),
+        None => Err(io::Error::new(
+            io::ErrorKind::InvalidInput,
+            "invalid address family (not IPv4 or IPv6)",
+        )),
+    }
+}
+
 impl fmt::Debug for TcpSocket {
     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
         self.inner.fmt(fmt)
@@ -539,6 +788,13 @@ impl AsRawFd for TcpSocket {
     }
 }
 
+#[cfg(all(unix, not(tokio_no_as_fd)))]
+impl AsFd for TcpSocket {
+    fn as_fd(&self) -> BorrowedFd<'_> {
+        unsafe { BorrowedFd::borrow_raw(self.as_raw_fd()) }
+    }
+}
+
 #[cfg(unix)]
 impl FromRawFd for TcpSocket {
     /// Converts a `RawFd` to a `TcpSocket`.
@@ -548,7 +804,7 @@ impl FromRawFd for TcpSocket {
     /// The caller is responsible for ensuring that the socket is in
     /// non-blocking mode.
     unsafe fn from_raw_fd(fd: RawFd) -> TcpSocket {
-        let inner = mio::net::TcpSocket::from_raw_fd(fd);
+        let inner = socket2::Socket::from_raw_fd(fd);
         TcpSocket { inner }
     }
 }
@@ -560,30 +816,36 @@ impl IntoRawFd for TcpSocket {
     }
 }
 
-#[cfg(windows)]
-impl IntoRawSocket for TcpSocket {
-    fn into_raw_socket(self) -> RawSocket {
-        self.inner.into_raw_socket()
+cfg_windows! {
+    impl IntoRawSocket for TcpSocket {
+        fn into_raw_socket(self) -> RawSocket {
+            self.inner.into_raw_socket()
+        }
+    }
+
+    impl AsRawSocket for TcpSocket {
+        fn as_raw_socket(&self) -> RawSocket {
+            self.inner.as_raw_socket()
+        }
     }
-}
 
-#[cfg(windows)]
-impl AsRawSocket for TcpSocket {
-    fn as_raw_socket(&self) -> RawSocket {
-        self.inner.as_raw_socket()
+    #[cfg(not(tokio_no_as_fd))]
+    impl AsSocket for TcpSocket {
+        fn as_socket(&self) -> BorrowedSocket<'_> {
+            unsafe { BorrowedSocket::borrow_raw(self.as_raw_socket()) }
+        }
     }
-}
 
-#[cfg(windows)]
-impl FromRawSocket for TcpSocket {
-    /// Converts a `RawSocket` to a `TcpStream`.
-    ///
-    /// # Notes
-    ///
-    /// The caller is responsible for ensuring that the socket is in
-    /// non-blocking mode.
-    unsafe fn from_raw_socket(socket: RawSocket) -> TcpSocket {
-        let inner = mio::net::TcpSocket::from_raw_socket(socket);
-        TcpSocket { inner }
+    impl FromRawSocket for TcpSocket {
+        /// Converts a `RawSocket` to a `TcpStream`.
+        ///
+        /// # Notes
+        ///
+        /// The caller is responsible for ensuring that the socket is in
+        /// non-blocking mode.
+        unsafe fn from_raw_socket(socket: RawSocket) -> TcpSocket {
+            let inner = socket2::Socket::from_raw_socket(socket);
+            TcpSocket { inner }
+        }
     }
 }
diff --git a/vendor/tokio/src/net/tcp/split.rs b/vendor/tokio/src/net/tcp/split.rs
index 8ae70ce13..1a1e22253 100644
--- a/vendor/tokio/src/net/tcp/split.rs
+++ b/vendor/tokio/src/net/tcp/split.rs
@@ -9,14 +9,18 @@
 //! level.
 
 use crate::future::poll_fn;
-use crate::io::{AsyncRead, AsyncWrite, ReadBuf};
+use crate::io::{AsyncRead, AsyncWrite, Interest, ReadBuf, Ready};
 use crate::net::TcpStream;
 
 use std::io;
-use std::net::Shutdown;
+use std::net::{Shutdown, SocketAddr};
 use std::pin::Pin;
 use std::task::{Context, Poll};
 
+cfg_io_util! {
+    use bytes::BufMut;
+}
+
 /// Borrowed read half of a [`TcpStream`], created by [`split`].
 ///
 /// Reading from a `ReadHalf` is usually done using the convenience methods found on the
@@ -49,7 +53,7 @@ pub(crate) fn split(stream: &mut TcpStream) -> (ReadHalf<'_>, WriteHalf<'_>) {
 }
 
 impl ReadHalf<'_> {
-    /// Attempt to receive data on the socket, without removing that data from
+    /// Attempts to receive data on the socket, without removing that data from
     /// the queue, registering the current task for wakeup if data is not yet
     /// available.
     ///
@@ -134,6 +138,233 @@ impl ReadHalf<'_> {
         let mut buf = ReadBuf::new(buf);
         poll_fn(|cx| self.poll_peek(cx, &mut buf)).await
     }
+
+    /// Waits for any of the requested ready states.
+    ///
+    /// This function is usually paired with [`try_read()`]. It can be used instead
+    /// of [`readable()`] to check the returned ready set for [`Ready::READABLE`]
+    /// and [`Ready::READ_CLOSED`] events.
+    ///
+    /// The function may complete without the socket being ready. This is a
+    /// false-positive and attempting an operation will return with
+    /// `io::ErrorKind::WouldBlock`. The function can also return with an empty
+    /// [`Ready`] set, so you should always check the returned value and possibly
+    /// wait again if the requested states are not set.
+    ///
+    /// This function is equivalent to [`TcpStream::ready`].
+    ///
+    /// [`try_read()`]: Self::try_read
+    /// [`readable()`]: Self::readable
+    ///
+    /// # Cancel safety
+    ///
+    /// This method is cancel safe. Once a readiness event occurs, the method
+    /// will continue to return immediately until the readiness event is
+    /// consumed by an attempt to read or write that fails with `WouldBlock` or
+    /// `Poll::Pending`.
+    pub async fn ready(&self, interest: Interest) -> io::Result<Ready> {
+        self.0.ready(interest).await
+    }
+
+    /// Waits for the socket to become readable.
+    ///
+    /// This function is equivalent to `ready(Interest::READABLE)` and is usually
+    /// paired with `try_read()`.
+    ///
+    /// This function is also equivalent to [`TcpStream::ready`].
+    ///
+    /// # Cancel safety
+    ///
+    /// This method is cancel safe. Once a readiness event occurs, the method
+    /// will continue to return immediately until the readiness event is
+    /// consumed by an attempt to read that fails with `WouldBlock` or
+    /// `Poll::Pending`.
+    pub async fn readable(&self) -> io::Result<()> {
+        self.0.readable().await
+    }
+
+    /// Tries to read data from the stream into the provided buffer, returning how
+    /// many bytes were read.
+    ///
+    /// Receives any pending data from the socket but does not wait for new data
+    /// to arrive. On success, returns the number of bytes read. Because
+    /// `try_read()` is non-blocking, the buffer does not have to be stored by
+    /// the async task and can exist entirely on the stack.
+    ///
+    /// Usually, [`readable()`] or [`ready()`] is used with this function.
+    ///
+    /// [`readable()`]: Self::readable()
+    /// [`ready()`]: Self::ready()
+    ///
+    /// # Return
+    ///
+    /// If data is successfully read, `Ok(n)` is returned, where `n` is the
+    /// number of bytes read. If `n` is `0`, then it can indicate one of two scenarios:
+    ///
+    /// 1. The stream's read half is closed and will no longer yield data.
+    /// 2. The specified buffer was 0 bytes in length.
+    ///
+    /// If the stream is not ready to read data,
+    /// `Err(io::ErrorKind::WouldBlock)` is returned.
+    pub fn try_read(&self, buf: &mut [u8]) -> io::Result<usize> {
+        self.0.try_read(buf)
+    }
+
+    /// Tries to read data from the stream into the provided buffers, returning
+    /// how many bytes were read.
+    ///
+    /// Data is copied to fill each buffer in order, with the final buffer
+    /// written to possibly being only partially filled. This method behaves
+    /// equivalently to a single call to [`try_read()`] with concatenated
+    /// buffers.
+    ///
+    /// Receives any pending data from the socket but does not wait for new data
+    /// to arrive. On success, returns the number of bytes read. Because
+    /// `try_read_vectored()` is non-blocking, the buffer does not have to be
+    /// stored by the async task and can exist entirely on the stack.
+    ///
+    /// Usually, [`readable()`] or [`ready()`] is used with this function.
+    ///
+    /// [`try_read()`]: Self::try_read()
+    /// [`readable()`]: Self::readable()
+    /// [`ready()`]: Self::ready()
+    ///
+    /// # Return
+    ///
+    /// If data is successfully read, `Ok(n)` is returned, where `n` is the
+    /// number of bytes read. `Ok(0)` indicates the stream's read half is closed
+    /// and will no longer yield data. If the stream is not ready to read data
+    /// `Err(io::ErrorKind::WouldBlock)` is returned.
+    pub fn try_read_vectored(&self, bufs: &mut [io::IoSliceMut<'_>]) -> io::Result<usize> {
+        self.0.try_read_vectored(bufs)
+    }
+
+    cfg_io_util! {
+        /// Tries to read data from the stream into the provided buffer, advancing the
+        /// buffer's internal cursor, returning how many bytes were read.
+        ///
+        /// Receives any pending data from the socket but does not wait for new data
+        /// to arrive. On success, returns the number of bytes read. Because
+        /// `try_read_buf()` is non-blocking, the buffer does not have to be stored by
+        /// the async task and can exist entirely on the stack.
+        ///
+        /// Usually, [`readable()`] or [`ready()`] is used with this function.
+        ///
+        /// [`readable()`]: Self::readable()
+        /// [`ready()`]: Self::ready()
+        ///
+        /// # Return
+        ///
+        /// If data is successfully read, `Ok(n)` is returned, where `n` is the
+        /// number of bytes read. `Ok(0)` indicates the stream's read half is closed
+        /// and will no longer yield data. If the stream is not ready to read data
+        /// `Err(io::ErrorKind::WouldBlock)` is returned.
+        pub fn try_read_buf<B: BufMut>(&self, buf: &mut B) -> io::Result<usize> {
+            self.0.try_read_buf(buf)
+        }
+    }
+
+    /// Returns the remote address that this stream is connected to.
+    pub fn peer_addr(&self) -> io::Result<SocketAddr> {
+        self.0.peer_addr()
+    }
+
+    /// Returns the local address that this stream is bound to.
+    pub fn local_addr(&self) -> io::Result<SocketAddr> {
+        self.0.local_addr()
+    }
+}
+
+impl WriteHalf<'_> {
+    /// Waits for any of the requested ready states.
+    ///
+    /// This function is usually paired with [`try_write()`]. It can be used instead
+    /// of [`writable()`] to check the returned ready set for [`Ready::WRITABLE`]
+    /// and [`Ready::WRITE_CLOSED`] events.
+    ///
+    /// The function may complete without the socket being ready. This is a
+    /// false-positive and attempting an operation will return with
+    /// `io::ErrorKind::WouldBlock`. The function can also return with an empty
+    /// [`Ready`] set, so you should always check the returned value and possibly
+    /// wait again if the requested states are not set.
+    ///
+    /// This function is equivalent to [`TcpStream::ready`].
+    ///
+    /// [`try_write()`]: Self::try_write
+    /// [`writable()`]: Self::writable
+    ///
+    /// # Cancel safety
+    ///
+    /// This method is cancel safe. Once a readiness event occurs, the method
+    /// will continue to return immediately until the readiness event is
+    /// consumed by an attempt to read or write that fails with `WouldBlock` or
+    /// `Poll::Pending`.
+    pub async fn ready(&self, interest: Interest) -> io::Result<Ready> {
+        self.0.ready(interest).await
+    }
+
+    /// Waits for the socket to become writable.
+    ///
+    /// This function is equivalent to `ready(Interest::WRITABLE)` and is usually
+    /// paired with `try_write()`.
+    ///
+    /// # Cancel safety
+    ///
+    /// This method is cancel safe. Once a readiness event occurs, the method
+    /// will continue to return immediately until the readiness event is
+    /// consumed by an attempt to write that fails with `WouldBlock` or
+    /// `Poll::Pending`.
+    pub async fn writable(&self) -> io::Result<()> {
+        self.0.writable().await
+    }
+
+    /// Tries to write a buffer to the stream, returning how many bytes were
+    /// written.
+    ///
+    /// The function will attempt to write the entire contents of `buf`, but
+    /// only part of the buffer may be written.
+    ///
+    /// This function is usually paired with `writable()`.
+    ///
+    /// # Return
+    ///
+    /// If data is successfully written, `Ok(n)` is returned, where `n` is the
+    /// number of bytes written. If the stream is not ready to write data,
+    /// `Err(io::ErrorKind::WouldBlock)` is returned.
+    pub fn try_write(&self, buf: &[u8]) -> io::Result<usize> {
+        self.0.try_write(buf)
+    }
+
+    /// Tries to write several buffers to the stream, returning how many bytes
+    /// were written.
+    ///
+    /// Data is written from each buffer in order, with the final buffer read
+    /// from possible being only partially consumed. This method behaves
+    /// equivalently to a single call to [`try_write()`] with concatenated
+    /// buffers.
+    ///
+    /// This function is usually paired with `writable()`.
+    ///
+    /// [`try_write()`]: Self::try_write()
+    ///
+    /// # Return
+    ///
+    /// If data is successfully written, `Ok(n)` is returned, where `n` is the
+    /// number of bytes written. If the stream is not ready to write data,
+    /// `Err(io::ErrorKind::WouldBlock)` is returned.
+    pub fn try_write_vectored(&self, bufs: &[io::IoSlice<'_>]) -> io::Result<usize> {
+        self.0.try_write_vectored(bufs)
+    }
+
+    /// Returns the remote address that this stream is connected to.
+    pub fn peer_addr(&self) -> io::Result<SocketAddr> {
+        self.0.peer_addr()
+    }
+
+    /// Returns the local address that this stream is bound to.
+    pub fn local_addr(&self) -> io::Result<SocketAddr> {
+        self.0.local_addr()
+    }
 }
 
 impl AsyncRead for ReadHalf<'_> {
diff --git a/vendor/tokio/src/net/tcp/split_owned.rs b/vendor/tokio/src/net/tcp/split_owned.rs
index 1bcb4f2ea..6771d6497 100644
--- a/vendor/tokio/src/net/tcp/split_owned.rs
+++ b/vendor/tokio/src/net/tcp/split_owned.rs
@@ -9,16 +9,20 @@
 //! level.
 
 use crate::future::poll_fn;
-use crate::io::{AsyncRead, AsyncWrite, ReadBuf};
+use crate::io::{AsyncRead, AsyncWrite, Interest, ReadBuf, Ready};
 use crate::net::TcpStream;
 
 use std::error::Error;
-use std::net::Shutdown;
+use std::net::{Shutdown, SocketAddr};
 use std::pin::Pin;
 use std::sync::Arc;
 use std::task::{Context, Poll};
 use std::{fmt, io};
 
+cfg_io_util! {
+    use bytes::BufMut;
+}
+
 /// Owned read half of a [`TcpStream`], created by [`into_split`].
 ///
 /// Reading from an `OwnedReadHalf` is usually done using the convenience methods found
@@ -189,6 +193,141 @@ impl OwnedReadHalf {
         let mut buf = ReadBuf::new(buf);
         poll_fn(|cx| self.poll_peek(cx, &mut buf)).await
     }
+
+    /// Waits for any of the requested ready states.
+    ///
+    /// This function is usually paired with [`try_read()`]. It can be used instead
+    /// of [`readable()`] to check the returned ready set for [`Ready::READABLE`]
+    /// and [`Ready::READ_CLOSED`] events.
+    ///
+    /// The function may complete without the socket being ready. This is a
+    /// false-positive and attempting an operation will return with
+    /// `io::ErrorKind::WouldBlock`. The function can also return with an empty
+    /// [`Ready`] set, so you should always check the returned value and possibly
+    /// wait again if the requested states are not set.
+    ///
+    /// This function is equivalent to [`TcpStream::ready`].
+    ///
+    /// [`try_read()`]: Self::try_read
+    /// [`readable()`]: Self::readable
+    ///
+    /// # Cancel safety
+    ///
+    /// This method is cancel safe. Once a readiness event occurs, the method
+    /// will continue to return immediately until the readiness event is
+    /// consumed by an attempt to read or write that fails with `WouldBlock` or
+    /// `Poll::Pending`.
+    pub async fn ready(&self, interest: Interest) -> io::Result<Ready> {
+        self.inner.ready(interest).await
+    }
+
+    /// Waits for the socket to become readable.
+    ///
+    /// This function is equivalent to `ready(Interest::READABLE)` and is usually
+    /// paired with `try_read()`.
+    ///
+    /// This function is also equivalent to [`TcpStream::ready`].
+    ///
+    /// # Cancel safety
+    ///
+    /// This method is cancel safe. Once a readiness event occurs, the method
+    /// will continue to return immediately until the readiness event is
+    /// consumed by an attempt to read that fails with `WouldBlock` or
+    /// `Poll::Pending`.
+    pub async fn readable(&self) -> io::Result<()> {
+        self.inner.readable().await
+    }
+
+    /// Tries to read data from the stream into the provided buffer, returning how
+    /// many bytes were read.
+    ///
+    /// Receives any pending data from the socket but does not wait for new data
+    /// to arrive. On success, returns the number of bytes read. Because
+    /// `try_read()` is non-blocking, the buffer does not have to be stored by
+    /// the async task and can exist entirely on the stack.
+    ///
+    /// Usually, [`readable()`] or [`ready()`] is used with this function.
+    ///
+    /// [`readable()`]: Self::readable()
+    /// [`ready()`]: Self::ready()
+    ///
+    /// # Return
+    ///
+    /// If data is successfully read, `Ok(n)` is returned, where `n` is the
+    /// number of bytes read. If `n` is `0`, then it can indicate one of two scenarios:
+    ///
+    /// 1. The stream's read half is closed and will no longer yield data.
+    /// 2. The specified buffer was 0 bytes in length.
+    ///
+    /// If the stream is not ready to read data,
+    /// `Err(io::ErrorKind::WouldBlock)` is returned.
+    pub fn try_read(&self, buf: &mut [u8]) -> io::Result<usize> {
+        self.inner.try_read(buf)
+    }
+
+    /// Tries to read data from the stream into the provided buffers, returning
+    /// how many bytes were read.
+    ///
+    /// Data is copied to fill each buffer in order, with the final buffer
+    /// written to possibly being only partially filled. This method behaves
+    /// equivalently to a single call to [`try_read()`] with concatenated
+    /// buffers.
+    ///
+    /// Receives any pending data from the socket but does not wait for new data
+    /// to arrive. On success, returns the number of bytes read. Because
+    /// `try_read_vectored()` is non-blocking, the buffer does not have to be
+    /// stored by the async task and can exist entirely on the stack.
+    ///
+    /// Usually, [`readable()`] or [`ready()`] is used with this function.
+    ///
+    /// [`try_read()`]: Self::try_read()
+    /// [`readable()`]: Self::readable()
+    /// [`ready()`]: Self::ready()
+    ///
+    /// # Return
+    ///
+    /// If data is successfully read, `Ok(n)` is returned, where `n` is the
+    /// number of bytes read. `Ok(0)` indicates the stream's read half is closed
+    /// and will no longer yield data. If the stream is not ready to read data
+    /// `Err(io::ErrorKind::WouldBlock)` is returned.
+    pub fn try_read_vectored(&self, bufs: &mut [io::IoSliceMut<'_>]) -> io::Result<usize> {
+        self.inner.try_read_vectored(bufs)
+    }
+
+    cfg_io_util! {
+        /// Tries to read data from the stream into the provided buffer, advancing the
+        /// buffer's internal cursor, returning how many bytes were read.
+        ///
+        /// Receives any pending data from the socket but does not wait for new data
+        /// to arrive. On success, returns the number of bytes read. Because
+        /// `try_read_buf()` is non-blocking, the buffer does not have to be stored by
+        /// the async task and can exist entirely on the stack.
+        ///
+        /// Usually, [`readable()`] or [`ready()`] is used with this function.
+        ///
+        /// [`readable()`]: Self::readable()
+        /// [`ready()`]: Self::ready()
+        ///
+        /// # Return
+        ///
+        /// If data is successfully read, `Ok(n)` is returned, where `n` is the
+        /// number of bytes read. `Ok(0)` indicates the stream's read half is closed
+        /// and will no longer yield data. If the stream is not ready to read data
+        /// `Err(io::ErrorKind::WouldBlock)` is returned.
+        pub fn try_read_buf<B: BufMut>(&self, buf: &mut B) -> io::Result<usize> {
+            self.inner.try_read_buf(buf)
+        }
+    }
+
+    /// Returns the remote address that this stream is connected to.
+    pub fn peer_addr(&self) -> io::Result<SocketAddr> {
+        self.inner.peer_addr()
+    }
+
+    /// Returns the local address that this stream is bound to.
+    pub fn local_addr(&self) -> io::Result<SocketAddr> {
+        self.inner.local_addr()
+    }
 }
 
 impl AsyncRead for OwnedReadHalf {
@@ -211,13 +350,103 @@ impl OwnedWriteHalf {
         reunite(other, self)
     }
 
-    /// Destroy the write half, but don't close the write half of the stream
+    /// Destroys the write half, but don't close the write half of the stream
     /// until the read half is dropped. If the read half has already been
     /// dropped, this closes the stream.
     pub fn forget(mut self) {
         self.shutdown_on_drop = false;
         drop(self);
     }
+
+    /// Waits for any of the requested ready states.
+    ///
+    /// This function is usually paired with [`try_write()`]. It can be used instead
+    /// of [`writable()`] to check the returned ready set for [`Ready::WRITABLE`]
+    /// and [`Ready::WRITE_CLOSED`] events.
+    ///
+    /// The function may complete without the socket being ready. This is a
+    /// false-positive and attempting an operation will return with
+    /// `io::ErrorKind::WouldBlock`. The function can also return with an empty
+    /// [`Ready`] set, so you should always check the returned value and possibly
+    /// wait again if the requested states are not set.
+    ///
+    /// This function is equivalent to [`TcpStream::ready`].
+    ///
+    /// [`try_write()`]: Self::try_write
+    /// [`writable()`]: Self::writable
+    ///
+    /// # Cancel safety
+    ///
+    /// This method is cancel safe. Once a readiness event occurs, the method
+    /// will continue to return immediately until the readiness event is
+    /// consumed by an attempt to read or write that fails with `WouldBlock` or
+    /// `Poll::Pending`.
+    pub async fn ready(&self, interest: Interest) -> io::Result<Ready> {
+        self.inner.ready(interest).await
+    }
+
+    /// Waits for the socket to become writable.
+    ///
+    /// This function is equivalent to `ready(Interest::WRITABLE)` and is usually
+    /// paired with `try_write()`.
+    ///
+    /// # Cancel safety
+    ///
+    /// This method is cancel safe. Once a readiness event occurs, the method
+    /// will continue to return immediately until the readiness event is
+    /// consumed by an attempt to write that fails with `WouldBlock` or
+    /// `Poll::Pending`.
+    pub async fn writable(&self) -> io::Result<()> {
+        self.inner.writable().await
+    }
+
+    /// Tries to write a buffer to the stream, returning how many bytes were
+    /// written.
+    ///
+    /// The function will attempt to write the entire contents of `buf`, but
+    /// only part of the buffer may be written.
+    ///
+    /// This function is usually paired with `writable()`.
+    ///
+    /// # Return
+    ///
+    /// If data is successfully written, `Ok(n)` is returned, where `n` is the
+    /// number of bytes written. If the stream is not ready to write data,
+    /// `Err(io::ErrorKind::WouldBlock)` is returned.
+    pub fn try_write(&self, buf: &[u8]) -> io::Result<usize> {
+        self.inner.try_write(buf)
+    }
+
+    /// Tries to write several buffers to the stream, returning how many bytes
+    /// were written.
+    ///
+    /// Data is written from each buffer in order, with the final buffer read
+    /// from possible being only partially consumed. This method behaves
+    /// equivalently to a single call to [`try_write()`] with concatenated
+    /// buffers.
+    ///
+    /// This function is usually paired with `writable()`.
+    ///
+    /// [`try_write()`]: Self::try_write()
+    ///
+    /// # Return
+    ///
+    /// If data is successfully written, `Ok(n)` is returned, where `n` is the
+    /// number of bytes written. If the stream is not ready to write data,
+    /// `Err(io::ErrorKind::WouldBlock)` is returned.
+    pub fn try_write_vectored(&self, bufs: &[io::IoSlice<'_>]) -> io::Result<usize> {
+        self.inner.try_write_vectored(bufs)
+    }
+
+    /// Returns the remote address that this stream is connected to.
+    pub fn peer_addr(&self) -> io::Result<SocketAddr> {
+        self.inner.peer_addr()
+    }
+
+    /// Returns the local address that this stream is bound to.
+    pub fn local_addr(&self) -> io::Result<SocketAddr> {
+        self.inner.local_addr()
+    }
 }
 
 impl Drop for OwnedWriteHalf {
@@ -267,12 +496,12 @@ impl AsyncWrite for OwnedWriteHalf {
 
 impl AsRef<TcpStream> for OwnedReadHalf {
     fn as_ref(&self) -> &TcpStream {
-        &*self.inner
+        &self.inner
     }
 }
 
 impl AsRef<TcpStream> for OwnedWriteHalf {
     fn as_ref(&self) -> &TcpStream {
-        &*self.inner
+        &self.inner
     }
 }
diff --git a/vendor/tokio/src/net/tcp/stream.rs b/vendor/tokio/src/net/tcp/stream.rs
index 0277a360d..b7104d78b 100644
--- a/vendor/tokio/src/net/tcp/stream.rs
+++ b/vendor/tokio/src/net/tcp/stream.rs
@@ -1,16 +1,18 @@
-use crate::future::poll_fn;
+cfg_not_wasi! {
+    use crate::future::poll_fn;
+    use crate::net::{to_socket_addrs, ToSocketAddrs};
+    use std::time::Duration;
+}
+
 use crate::io::{AsyncRead, AsyncWrite, Interest, PollEvented, ReadBuf, Ready};
 use crate::net::tcp::split::{split, ReadHalf, WriteHalf};
 use crate::net::tcp::split_owned::{split_owned, OwnedReadHalf, OwnedWriteHalf};
-use crate::net::{to_socket_addrs, ToSocketAddrs};
 
-use std::convert::TryFrom;
 use std::fmt;
 use std::io;
 use std::net::{Shutdown, SocketAddr};
 use std::pin::Pin;
 use std::task::{Context, Poll};
-use std::time::Duration;
 
 cfg_io_util! {
     use bytes::BufMut;
@@ -70,86 +72,88 @@ cfg_net! {
 }
 
 impl TcpStream {
-    /// Opens a TCP connection to a remote host.
-    ///
-    /// `addr` is an address of the remote host. Anything which implements the
-    /// [`ToSocketAddrs`] trait can be supplied as the address.  If `addr`
-    /// yields multiple addresses, connect will be attempted with each of the
-    /// addresses until a connection is successful. If none of the addresses
-    /// result in a successful connection, the error returned from the last
-    /// connection attempt (the last address) is returned.
-    ///
-    /// To configure the socket before connecting, you can use the [`TcpSocket`]
-    /// type.
-    ///
-    /// [`ToSocketAddrs`]: trait@crate::net::ToSocketAddrs
-    /// [`TcpSocket`]: struct@crate::net::TcpSocket
-    ///
-    /// # Examples
-    ///
-    /// ```no_run
-    /// use tokio::net::TcpStream;
-    /// use tokio::io::AsyncWriteExt;
-    /// use std::error::Error;
-    ///
-    /// #[tokio::main]
-    /// async fn main() -> Result<(), Box<dyn Error>> {
-    ///     // Connect to a peer
-    ///     let mut stream = TcpStream::connect("127.0.0.1:8080").await?;
-    ///
-    ///     // Write some data.
-    ///     stream.write_all(b"hello world!").await?;
-    ///
-    ///     Ok(())
-    /// }
-    /// ```
-    ///
-    /// The [`write_all`] method is defined on the [`AsyncWriteExt`] trait.
-    ///
-    /// [`write_all`]: fn@crate::io::AsyncWriteExt::write_all
-    /// [`AsyncWriteExt`]: trait@crate::io::AsyncWriteExt
-    pub async fn connect<A: ToSocketAddrs>(addr: A) -> io::Result<TcpStream> {
-        let addrs = to_socket_addrs(addr).await?;
+    cfg_not_wasi! {
+        /// Opens a TCP connection to a remote host.
+        ///
+        /// `addr` is an address of the remote host. Anything which implements the
+        /// [`ToSocketAddrs`] trait can be supplied as the address.  If `addr`
+        /// yields multiple addresses, connect will be attempted with each of the
+        /// addresses until a connection is successful. If none of the addresses
+        /// result in a successful connection, the error returned from the last
+        /// connection attempt (the last address) is returned.
+        ///
+        /// To configure the socket before connecting, you can use the [`TcpSocket`]
+        /// type.
+        ///
+        /// [`ToSocketAddrs`]: trait@crate::net::ToSocketAddrs
+        /// [`TcpSocket`]: struct@crate::net::TcpSocket
+        ///
+        /// # Examples
+        ///
+        /// ```no_run
+        /// use tokio::net::TcpStream;
+        /// use tokio::io::AsyncWriteExt;
+        /// use std::error::Error;
+        ///
+        /// #[tokio::main]
+        /// async fn main() -> Result<(), Box<dyn Error>> {
+        ///     // Connect to a peer
+        ///     let mut stream = TcpStream::connect("127.0.0.1:8080").await?;
+        ///
+        ///     // Write some data.
+        ///     stream.write_all(b"hello world!").await?;
+        ///
+        ///     Ok(())
+        /// }
+        /// ```
+        ///
+        /// The [`write_all`] method is defined on the [`AsyncWriteExt`] trait.
+        ///
+        /// [`write_all`]: fn@crate::io::AsyncWriteExt::write_all
+        /// [`AsyncWriteExt`]: trait@crate::io::AsyncWriteExt
+        pub async fn connect<A: ToSocketAddrs>(addr: A) -> io::Result<TcpStream> {
+            let addrs = to_socket_addrs(addr).await?;
 
-        let mut last_err = None;
+            let mut last_err = None;
 
-        for addr in addrs {
-            match TcpStream::connect_addr(addr).await {
-                Ok(stream) => return Ok(stream),
-                Err(e) => last_err = Some(e),
+            for addr in addrs {
+                match TcpStream::connect_addr(addr).await {
+                    Ok(stream) => return Ok(stream),
+                    Err(e) => last_err = Some(e),
+                }
             }
+
+            Err(last_err.unwrap_or_else(|| {
+                io::Error::new(
+                    io::ErrorKind::InvalidInput,
+                    "could not resolve to any address",
+                )
+            }))
         }
 
-        Err(last_err.unwrap_or_else(|| {
-            io::Error::new(
-                io::ErrorKind::InvalidInput,
-                "could not resolve to any address",
-            )
-        }))
-    }
+        /// Establishes a connection to the specified `addr`.
+        async fn connect_addr(addr: SocketAddr) -> io::Result<TcpStream> {
+            let sys = mio::net::TcpStream::connect(addr)?;
+            TcpStream::connect_mio(sys).await
+        }
 
-    /// Establishes a connection to the specified `addr`.
-    async fn connect_addr(addr: SocketAddr) -> io::Result<TcpStream> {
-        let sys = mio::net::TcpStream::connect(addr)?;
-        TcpStream::connect_mio(sys).await
-    }
+        pub(crate) async fn connect_mio(sys: mio::net::TcpStream) -> io::Result<TcpStream> {
+            let stream = TcpStream::new(sys)?;
 
-    pub(crate) async fn connect_mio(sys: mio::net::TcpStream) -> io::Result<TcpStream> {
-        let stream = TcpStream::new(sys)?;
+            // Once we've connected, wait for the stream to be writable as
+            // that's when the actual connection has been initiated. Once we're
+            // writable we check for `take_socket_error` to see if the connect
+            // actually hit an error or not.
+            //
+            // If all that succeeded then we ship everything on up.
+            poll_fn(|cx| stream.io.registration().poll_write_ready(cx)).await?;
 
-        // Once we've connected, wait for the stream to be writable as
-        // that's when the actual connection has been initiated. Once we're
-        // writable we check for `take_socket_error` to see if the connect
-        // actually hit an error or not.
-        //
-        // If all that succeeded then we ship everything on up.
-        poll_fn(|cx| stream.io.registration().poll_write_ready(cx)).await?;
+            if let Some(e) = stream.io.take_error()? {
+                return Err(e);
+            }
 
-        if let Some(e) = stream.io.take_error()? {
-            return Err(e);
+            Ok(stream)
         }
-
-        Ok(stream)
     }
 
     pub(crate) fn new(connected: mio::net::TcpStream) -> io::Result<TcpStream> {
@@ -160,9 +164,16 @@ impl TcpStream {
     /// Creates new `TcpStream` from a `std::net::TcpStream`.
     ///
     /// This function is intended to be used to wrap a TCP stream from the
-    /// standard library in the Tokio equivalent. The conversion assumes nothing
-    /// about the underlying stream; it is left up to the user to set it in
-    /// non-blocking mode.
+    /// standard library in the Tokio equivalent.
+    ///
+    /// # Notes
+    ///
+    /// The caller is responsible for ensuring that the stream is in
+    /// non-blocking mode. Otherwise all I/O operations on the stream
+    /// will block the thread, which will cause unexpected behavior.
+    /// Non-blocking mode can be set using [`set_nonblocking`].
+    ///
+    /// [`set_nonblocking`]: std::net::TcpStream::set_nonblocking
     ///
     /// # Examples
     ///
@@ -181,18 +192,20 @@ impl TcpStream {
     ///
     /// # Panics
     ///
-    /// This function panics if thread-local runtime is not set.
+    /// This function panics if it is not called from within a runtime with
+    /// IO enabled.
     ///
     /// The runtime is usually set implicitly when this function is called
     /// from a future driven by a tokio runtime, otherwise runtime can be set
     /// explicitly with [`Runtime::enter`](crate::runtime::Runtime::enter) function.
+    #[track_caller]
     pub fn from_std(stream: std::net::TcpStream) -> io::Result<TcpStream> {
         let io = mio::net::TcpStream::from_std(stream);
         let io = PollEvented::new(io)?;
         Ok(TcpStream { io })
     }
 
-    /// Turn a [`tokio::net::TcpStream`] into a [`std::net::TcpStream`].
+    /// Turns a [`tokio::net::TcpStream`] into a [`std::net::TcpStream`].
     ///
     /// The returned [`std::net::TcpStream`] will have nonblocking mode set as `true`.
     /// Use [`set_nonblocking`] to change the blocking mode if needed.
@@ -244,6 +257,15 @@ impl TcpStream {
                 .map(|io| io.into_raw_socket())
                 .map(|raw_socket| unsafe { std::net::TcpStream::from_raw_socket(raw_socket) })
         }
+
+        #[cfg(tokio_wasi)]
+        {
+            use std::os::wasi::io::{FromRawFd, IntoRawFd};
+            self.io
+                .into_inner()
+                .map(|io| io.into_raw_fd())
+                .map(|raw_fd| unsafe { std::net::TcpStream::from_raw_fd(raw_fd) })
+        }
     }
 
     /// Returns the local address that this stream is bound to.
@@ -264,6 +286,11 @@ impl TcpStream {
         self.io.local_addr()
     }
 
+    /// Returns the value of the `SO_ERROR` option.
+    pub fn take_error(&self) -> io::Result<Option<io::Error>> {
+        self.io.take_error()
+    }
+
     /// Returns the remote address that this stream is connected to.
     ///
     /// # Examples
@@ -350,12 +377,18 @@ impl TcpStream {
         }
     }
 
-    /// Wait for any of the requested ready states.
+    /// Waits for any of the requested ready states.
     ///
     /// This function is usually paired with `try_read()` or `try_write()`. It
     /// can be used to concurrently read / write to the same socket on a single
     /// task without splitting the socket.
     ///
+    /// The function may complete without the socket being ready. This is a
+    /// false-positive and attempting an operation will return with
+    /// `io::ErrorKind::WouldBlock`. The function can also return with an empty
+    /// [`Ready`] set, so you should always check the returned value and possibly
+    /// wait again if the requested states are not set.
+    ///
     /// # Cancel safety
     ///
     /// This method is cancel safe. Once a readiness event occurs, the method
@@ -387,7 +420,7 @@ impl TcpStream {
     ///             // if the readiness event is a false positive.
     ///             match stream.try_read(&mut data) {
     ///                 Ok(n) => {
-    ///                     println!("read {} bytes", n);        
+    ///                     println!("read {} bytes", n);
     ///                 }
     ///                 Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
     ///                     continue;
@@ -422,7 +455,7 @@ impl TcpStream {
         Ok(event.ready)
     }
 
-    /// Wait for the socket to become readable.
+    /// Waits for the socket to become readable.
     ///
     /// This function is equivalent to `ready(Interest::READABLE)` and is usually
     /// paired with `try_read()`.
@@ -510,7 +543,7 @@ impl TcpStream {
         self.io.registration().poll_read_ready(cx).map_ok(|_| ())
     }
 
-    /// Try to read data from the stream into the provided buffer, returning how
+    /// Tries to read data from the stream into the provided buffer, returning how
     /// many bytes were read.
     ///
     /// Receives any pending data from the socket but does not wait for new data
@@ -526,8 +559,12 @@ impl TcpStream {
     /// # Return
     ///
     /// If data is successfully read, `Ok(n)` is returned, where `n` is the
-    /// number of bytes read. `Ok(0)` indicates the stream's read half is closed
-    /// and will no longer yield data. If the stream is not ready to read data
+    /// number of bytes read. If `n` is `0`, then it can indicate one of two scenarios:
+    ///
+    /// 1. The stream's read half is closed and will no longer yield data.
+    /// 2. The specified buffer was 0 bytes in length.
+    ///
+    /// If the stream is not ready to read data,
     /// `Err(io::ErrorKind::WouldBlock)` is returned.
     ///
     /// # Examples
@@ -577,7 +614,7 @@ impl TcpStream {
             .try_io(Interest::READABLE, || (&*self.io).read(buf))
     }
 
-    /// Try to read data from the stream into the provided buffers, returning
+    /// Tries to read data from the stream into the provided buffers, returning
     /// how many bytes were read.
     ///
     /// Data is copied to fill each buffer in order, with the final buffer
@@ -656,7 +693,7 @@ impl TcpStream {
     }
 
     cfg_io_util! {
-        /// Try to read data from the stream into the provided buffer, advancing the
+        /// Tries to read data from the stream into the provided buffer, advancing the
         /// buffer's internal cursor, returning how many bytes were read.
         ///
         /// Receives any pending data from the socket but does not wait for new data
@@ -734,7 +771,7 @@ impl TcpStream {
         }
     }
 
-    /// Wait for the socket to become writable.
+    /// Waits for the socket to become writable.
     ///
     /// This function is equivalent to `ready(Interest::WRITABLE)` and is usually
     /// paired with `try_write()`.
@@ -874,7 +911,7 @@ impl TcpStream {
             .try_io(Interest::WRITABLE, || (&*self.io).write(buf))
     }
 
-    /// Try to write several buffers to the stream, returning how many bytes
+    /// Tries to write several buffers to the stream, returning how many bytes
     /// were written.
     ///
     /// Data is written from each buffer in order, with the final buffer read
@@ -936,6 +973,84 @@ impl TcpStream {
             .try_io(Interest::WRITABLE, || (&*self.io).write_vectored(bufs))
     }
 
+    /// Tries to read or write from the socket using a user-provided IO operation.
+    ///
+    /// If the socket is ready, the provided closure is called. The closure
+    /// should attempt to perform IO operation on the socket by manually
+    /// calling the appropriate syscall. If the operation fails because the
+    /// socket is not actually ready, then the closure should return a
+    /// `WouldBlock` error and the readiness flag is cleared. The return value
+    /// of the closure is then returned by `try_io`.
+    ///
+    /// If the socket is not ready, then the closure is not called
+    /// and a `WouldBlock` error is returned.
+    ///
+    /// The closure should only return a `WouldBlock` error if it has performed
+    /// an IO operation on the socket that failed due to the socket not being
+    /// ready. Returning a `WouldBlock` error in any other situation will
+    /// incorrectly clear the readiness flag, which can cause the socket to
+    /// behave incorrectly.
+    ///
+    /// The closure should not perform the IO operation using any of the methods
+    /// defined on the Tokio `TcpStream` type, as this will mess with the
+    /// readiness flag and can cause the socket to behave incorrectly.
+    ///
+    /// This method is not intended to be used with combined interests.
+    /// The closure should perform only one type of IO operation, so it should not
+    /// require more than one ready state. This method may panic or sleep forever
+    /// if it is called with a combined interest.
+    ///
+    /// Usually, [`readable()`], [`writable()`] or [`ready()`] is used with this function.
+    ///
+    /// [`readable()`]: TcpStream::readable()
+    /// [`writable()`]: TcpStream::writable()
+    /// [`ready()`]: TcpStream::ready()
+    pub fn try_io<R>(
+        &self,
+        interest: Interest,
+        f: impl FnOnce() -> io::Result<R>,
+    ) -> io::Result<R> {
+        self.io
+            .registration()
+            .try_io(interest, || self.io.try_io(f))
+    }
+
+    /// Reads or writes from the socket using a user-provided IO operation.
+    ///
+    /// The readiness of the socket is awaited and when the socket is ready,
+    /// the provided closure is called. The closure should attempt to perform
+    /// IO operation on the socket by manually calling the appropriate syscall.
+    /// If the operation fails because the socket is not actually ready,
+    /// then the closure should return a `WouldBlock` error. In such case the
+    /// readiness flag is cleared and the socket readiness is awaited again.
+    /// This loop is repeated until the closure returns an `Ok` or an error
+    /// other than `WouldBlock`.
+    ///
+    /// The closure should only return a `WouldBlock` error if it has performed
+    /// an IO operation on the socket that failed due to the socket not being
+    /// ready. Returning a `WouldBlock` error in any other situation will
+    /// incorrectly clear the readiness flag, which can cause the socket to
+    /// behave incorrectly.
+    ///
+    /// The closure should not perform the IO operation using any of the methods
+    /// defined on the Tokio `TcpStream` type, as this will mess with the
+    /// readiness flag and can cause the socket to behave incorrectly.
+    ///
+    /// This method is not intended to be used with combined interests.
+    /// The closure should perform only one type of IO operation, so it should not
+    /// require more than one ready state. This method may panic or sleep forever
+    /// if it is called with a combined interest.
+    pub async fn async_io<R>(
+        &self,
+        interest: Interest,
+        mut f: impl FnMut() -> io::Result<R>,
+    ) -> io::Result<R> {
+        self.io
+            .registration()
+            .async_io(interest, || self.io.try_io(&mut f))
+            .await
+    }
+
     /// Receives data on the socket from the remote address to which it is
     /// connected, without removing that data from the queue. On success,
     /// returns the number of bytes peeked.
@@ -1035,69 +1150,53 @@ impl TcpStream {
         self.io.set_nodelay(nodelay)
     }
 
-    /// Reads the linger duration for this socket by getting the `SO_LINGER`
-    /// option.
-    ///
-    /// For more information about this option, see [`set_linger`].
-    ///
-    /// [`set_linger`]: TcpStream::set_linger
-    ///
-    /// # Examples
-    ///
-    /// ```no_run
-    /// use tokio::net::TcpStream;
-    ///
-    /// # async fn dox() -> Result<(), Box<dyn std::error::Error>> {
-    /// let stream = TcpStream::connect("127.0.0.1:8080").await?;
-    ///
-    /// println!("{:?}", stream.linger()?);
-    /// # Ok(())
-    /// # }
-    /// ```
-    pub fn linger(&self) -> io::Result<Option<Duration>> {
-        let mio_socket = std::mem::ManuallyDrop::new(self.to_mio());
-
-        mio_socket.get_linger()
-    }
-
-    /// Sets the linger duration of this socket by setting the SO_LINGER option.
-    ///
-    /// This option controls the action taken when a stream has unsent messages and the stream is
-    /// closed. If SO_LINGER is set, the system shall block the process until it can transmit the
-    /// data or until the time expires.
-    ///
-    /// If SO_LINGER is not specified, and the stream is closed, the system handles the call in a
-    /// way that allows the process to continue as quickly as possible.
-    ///
-    /// # Examples
-    ///
-    /// ```no_run
-    /// use tokio::net::TcpStream;
-    ///
-    /// # async fn dox() -> Result<(), Box<dyn std::error::Error>> {
-    /// let stream = TcpStream::connect("127.0.0.1:8080").await?;
-    ///
-    /// stream.set_linger(None)?;
-    /// # Ok(())
-    /// # }
-    /// ```
-    pub fn set_linger(&self, dur: Option<Duration>) -> io::Result<()> {
-        let mio_socket = std::mem::ManuallyDrop::new(self.to_mio());
-
-        mio_socket.set_linger(dur)
-    }
-
-    fn to_mio(&self) -> mio::net::TcpSocket {
-        #[cfg(windows)]
-        {
-            use std::os::windows::io::{AsRawSocket, FromRawSocket};
-            unsafe { mio::net::TcpSocket::from_raw_socket(self.as_raw_socket()) }
+    cfg_not_wasi! {
+        /// Reads the linger duration for this socket by getting the `SO_LINGER`
+        /// option.
+        ///
+        /// For more information about this option, see [`set_linger`].
+        ///
+        /// [`set_linger`]: TcpStream::set_linger
+        ///
+        /// # Examples
+        ///
+        /// ```no_run
+        /// use tokio::net::TcpStream;
+        ///
+        /// # async fn dox() -> Result<(), Box<dyn std::error::Error>> {
+        /// let stream = TcpStream::connect("127.0.0.1:8080").await?;
+        ///
+        /// println!("{:?}", stream.linger()?);
+        /// # Ok(())
+        /// # }
+        /// ```
+        pub fn linger(&self) -> io::Result<Option<Duration>> {
+            socket2::SockRef::from(self).linger()
         }
 
-        #[cfg(unix)]
-        {
-            use std::os::unix::io::{AsRawFd, FromRawFd};
-            unsafe { mio::net::TcpSocket::from_raw_fd(self.as_raw_fd()) }
+        /// Sets the linger duration of this socket by setting the SO_LINGER option.
+        ///
+        /// This option controls the action taken when a stream has unsent messages and the stream is
+        /// closed. If SO_LINGER is set, the system shall block the process until it can transmit the
+        /// data or until the time expires.
+        ///
+        /// If SO_LINGER is not specified, and the stream is closed, the system handles the call in a
+        /// way that allows the process to continue as quickly as possible.
+        ///
+        /// # Examples
+        ///
+        /// ```no_run
+        /// use tokio::net::TcpStream;
+        ///
+        /// # async fn dox() -> Result<(), Box<dyn std::error::Error>> {
+        /// let stream = TcpStream::connect("127.0.0.1:8080").await?;
+        ///
+        /// stream.set_linger(None)?;
+        /// # Ok(())
+        /// # }
+        /// ```
+        pub fn set_linger(&self, dur: Option<Duration>) -> io::Result<()> {
+            socket2::SockRef::from(self).set_linger(dur)
         }
     }
 
@@ -1278,16 +1377,49 @@ mod sys {
             self.io.as_raw_fd()
         }
     }
+
+    #[cfg(not(tokio_no_as_fd))]
+    impl AsFd for TcpStream {
+        fn as_fd(&self) -> BorrowedFd<'_> {
+            unsafe { BorrowedFd::borrow_raw(self.as_raw_fd()) }
+        }
+    }
 }
 
-#[cfg(windows)]
-mod sys {
-    use super::TcpStream;
-    use std::os::windows::prelude::*;
+cfg_windows! {
+    use crate::os::windows::io::{AsRawSocket, RawSocket};
+    #[cfg(not(tokio_no_as_fd))]
+    use crate::os::windows::io::{AsSocket, BorrowedSocket};
 
     impl AsRawSocket for TcpStream {
         fn as_raw_socket(&self) -> RawSocket {
             self.io.as_raw_socket()
         }
     }
+
+    #[cfg(not(tokio_no_as_fd))]
+    impl AsSocket for TcpStream {
+        fn as_socket(&self) -> BorrowedSocket<'_> {
+            unsafe { BorrowedSocket::borrow_raw(self.as_raw_socket()) }
+        }
+    }
+}
+
+#[cfg(all(tokio_unstable, tokio_wasi))]
+mod sys {
+    use super::TcpStream;
+    use std::os::wasi::prelude::*;
+
+    impl AsRawFd for TcpStream {
+        fn as_raw_fd(&self) -> RawFd {
+            self.io.as_raw_fd()
+        }
+    }
+
+    #[cfg(not(tokio_no_as_fd))]
+    impl AsFd for TcpStream {
+        fn as_fd(&self) -> BorrowedFd<'_> {
+            unsafe { BorrowedFd::borrow_raw(self.as_raw_fd()) }
+        }
+    }
 }
diff --git a/vendor/tokio/src/net/udp.rs b/vendor/tokio/src/net/udp.rs
index 301a85cc0..8da377e16 100644
--- a/vendor/tokio/src/net/udp.rs
+++ b/vendor/tokio/src/net/udp.rs
@@ -1,7 +1,6 @@
 use crate::io::{Interest, PollEvented, ReadBuf, Ready};
 use crate::net::{to_socket_addrs, ToSocketAddrs};
 
-use std::convert::TryFrom;
 use std::fmt;
 use std::io;
 use std::net::{self, Ipv4Addr, Ipv6Addr, SocketAddr};
@@ -12,7 +11,7 @@ cfg_io_util! {
 }
 
 cfg_net! {
-    /// A UDP socket
+    /// A UDP socket.
     ///
     /// UDP is "connectionless", unlike TCP. Meaning, regardless of what address you've bound to, a `UdpSocket`
     /// is free to communicate with many different remotes. In tokio there are basically two main ways to use `UdpSocket`:
@@ -128,6 +127,10 @@ impl UdpSocket {
     /// This function will create a new UDP socket and attempt to bind it to
     /// the `addr` provided.
     ///
+    /// Binding with a port number of 0 will request that the OS assigns a port
+    /// to this listener. The port allocated can be queried via the `local_addr`
+    /// method.
+    ///
     /// # Example
     ///
     /// ```no_run
@@ -166,6 +169,7 @@ impl UdpSocket {
         UdpSocket::new(sys)
     }
 
+    #[track_caller]
     fn new(socket: mio::net::UdpSocket) -> io::Result<UdpSocket> {
         let io = PollEvented::new(socket)?;
         Ok(UdpSocket { io })
@@ -174,14 +178,21 @@ impl UdpSocket {
     /// Creates new `UdpSocket` from a previously bound `std::net::UdpSocket`.
     ///
     /// This function is intended to be used to wrap a UDP socket from the
-    /// standard library in the Tokio equivalent. The conversion assumes nothing
-    /// about the underlying socket; it is left up to the user to set it in
-    /// non-blocking mode.
+    /// standard library in the Tokio equivalent.
     ///
     /// This can be used in conjunction with socket2's `Socket` interface to
     /// configure a socket before it's handed off, such as setting options like
     /// `reuse_address` or binding to multiple addresses.
     ///
+    /// # Notes
+    ///
+    /// The caller is responsible for ensuring that the socket is in
+    /// non-blocking mode. Otherwise all I/O operations on the socket
+    /// will block the thread, which will cause unexpected behavior.
+    /// Non-blocking mode can be set using [`set_nonblocking`].
+    ///
+    /// [`set_nonblocking`]: std::net::UdpSocket::set_nonblocking
+    ///
     /// # Panics
     ///
     /// This function panics if thread-local runtime is not set.
@@ -206,12 +217,13 @@ impl UdpSocket {
     /// # Ok(())
     /// # }
     /// ```
+    #[track_caller]
     pub fn from_std(socket: net::UdpSocket) -> io::Result<UdpSocket> {
         let io = mio::net::UdpSocket::from_std(socket);
         UdpSocket::new(io)
     }
 
-    /// Turn a [`tokio::net::UdpSocket`] into a [`std::net::UdpSocket`].
+    /// Turns a [`tokio::net::UdpSocket`] into a [`std::net::UdpSocket`].
     ///
     /// The returned [`std::net::UdpSocket`] will have nonblocking mode set as
     /// `true`.  Use [`set_nonblocking`] to change the blocking mode if needed.
@@ -253,6 +265,10 @@ impl UdpSocket {
         }
     }
 
+    fn as_socket(&self) -> socket2::SockRef<'_> {
+        socket2::SockRef::from(self)
+    }
+
     /// Returns the local address that this socket is bound to.
     ///
     /// # Example
@@ -274,6 +290,28 @@ impl UdpSocket {
         self.io.local_addr()
     }
 
+    /// Returns the socket address of the remote peer this socket was connected to.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use tokio::net::UdpSocket;
+    ///
+    /// # use std::{io, net::SocketAddr};
+    /// # #[tokio::main]
+    /// # async fn main() -> io::Result<()> {
+    /// let addr = "0.0.0.0:8080".parse::<SocketAddr>().unwrap();
+    /// let peer = "127.0.0.1:11100".parse::<SocketAddr>().unwrap();
+    /// let sock = UdpSocket::bind(addr).await?;
+    /// sock.connect(peer).await?;
+    /// assert_eq!(peer, sock.peer_addr()?);
+    /// #    Ok(())
+    /// # }
+    /// ```
+    pub fn peer_addr(&self) -> io::Result<SocketAddr> {
+        self.io.peer_addr()
+    }
+
     /// Connects the UDP socket setting the default destination for send() and
     /// limiting packets that are read via recv from the address specified in
     /// `addr`.
@@ -317,7 +355,7 @@ impl UdpSocket {
         }))
     }
 
-    /// Wait for any of the requested ready states.
+    /// Waits for any of the requested ready states.
     ///
     /// This function is usually paired with `try_recv()` or `try_send()`. It
     /// can be used to concurrently recv / send to the same socket on a single
@@ -325,7 +363,9 @@ impl UdpSocket {
     ///
     /// The function may complete without the socket being ready. This is a
     /// false-positive and attempting an operation will return with
-    /// `io::ErrorKind::WouldBlock`.
+    /// `io::ErrorKind::WouldBlock`. The function can also return with an empty
+    /// [`Ready`] set, so you should always check the returned value and possibly
+    /// wait again if the requested states are not set.
     ///
     /// # Cancel safety
     ///
@@ -388,7 +428,7 @@ impl UdpSocket {
         Ok(event.ready)
     }
 
-    /// Wait for the socket to become writable.
+    /// Waits for the socket to become writable.
     ///
     /// This function is equivalent to `ready(Interest::WRITABLE)` and is
     /// usually paired with `try_send()` or `try_send_to()`.
@@ -443,6 +483,39 @@ impl UdpSocket {
         Ok(())
     }
 
+    /// Polls for write/send readiness.
+    ///
+    /// If the udp stream is not currently ready for sending, this method will
+    /// store a clone of the `Waker` from the provided `Context`. When the udp
+    /// stream becomes ready for sending, `Waker::wake` will be called on the
+    /// waker.
+    ///
+    /// Note that on multiple calls to `poll_send_ready` or `poll_send`, only
+    /// the `Waker` from the `Context` passed to the most recent call is
+    /// scheduled to receive a wakeup. (However, `poll_recv_ready` retains a
+    /// second, independent waker.)
+    ///
+    /// This function is intended for cases where creating and pinning a future
+    /// via [`writable`] is not feasible. Where possible, using [`writable`] is
+    /// preferred, as this supports polling from multiple tasks at once.
+    ///
+    /// # Return value
+    ///
+    /// The function returns:
+    ///
+    /// * `Poll::Pending` if the udp stream is not ready for writing.
+    /// * `Poll::Ready(Ok(()))` if the udp stream is ready for writing.
+    /// * `Poll::Ready(Err(e))` if an error is encountered.
+    ///
+    /// # Errors
+    ///
+    /// This function may encounter any standard I/O error except `WouldBlock`.
+    ///
+    /// [`writable`]: method@Self::writable
+    pub fn poll_send_ready(&self, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+        self.io.registration().poll_write_ready(cx).map_ok(|_| ())
+    }
+
     /// Sends data on the socket to the remote address that the socket is
     /// connected to.
     ///
@@ -516,7 +589,7 @@ impl UdpSocket {
             .poll_write_io(cx, || self.io.send(buf))
     }
 
-    /// Try to send data on the socket to the remote address to which it is
+    /// Tries to send data on the socket to the remote address to which it is
     /// connected.
     ///
     /// When the socket buffer is full, `Err(io::ErrorKind::WouldBlock)` is
@@ -570,7 +643,7 @@ impl UdpSocket {
             .try_io(Interest::WRITABLE, || self.io.send(buf))
     }
 
-    /// Wait for the socket to become readable.
+    /// Waits for the socket to become readable.
     ///
     /// This function is equivalent to `ready(Interest::READABLE)` and is usually
     /// paired with `try_recv()`.
@@ -630,6 +703,39 @@ impl UdpSocket {
         Ok(())
     }
 
+    /// Polls for read/receive readiness.
+    ///
+    /// If the udp stream is not currently ready for receiving, this method will
+    /// store a clone of the `Waker` from the provided `Context`. When the udp
+    /// socket becomes ready for reading, `Waker::wake` will be called on the
+    /// waker.
+    ///
+    /// Note that on multiple calls to `poll_recv_ready`, `poll_recv` or
+    /// `poll_peek`, only the `Waker` from the `Context` passed to the most
+    /// recent call is scheduled to receive a wakeup. (However,
+    /// `poll_send_ready` retains a second, independent waker.)
+    ///
+    /// This function is intended for cases where creating and pinning a future
+    /// via [`readable`] is not feasible. Where possible, using [`readable`] is
+    /// preferred, as this supports polling from multiple tasks at once.
+    ///
+    /// # Return value
+    ///
+    /// The function returns:
+    ///
+    /// * `Poll::Pending` if the udp stream is not ready for reading.
+    /// * `Poll::Ready(Ok(()))` if the udp stream is ready for reading.
+    /// * `Poll::Ready(Err(e))` if an error is encountered.
+    ///
+    /// # Errors
+    ///
+    /// This function may encounter any standard I/O error except `WouldBlock`.
+    ///
+    /// [`readable`]: method@Self::readable
+    pub fn poll_recv_ready(&self, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+        self.io.registration().poll_read_ready(cx).map_ok(|_| ())
+    }
+
     /// Receives a single datagram message on the socket from the remote address
     /// to which it is connected. On success, returns the number of bytes read.
     ///
@@ -642,7 +748,7 @@ impl UdpSocket {
     ///
     /// # Cancel safety
     ///
-    /// This method is cancel safe. If `recv_from` is used as the event in a
+    /// This method is cancel safe. If `recv` is used as the event in a
     /// [`tokio::select!`](crate::select) statement and some other branch
     /// completes first, it is guaranteed that no messages were received on this
     /// socket.
@@ -715,11 +821,11 @@ impl UdpSocket {
         Poll::Ready(Ok(()))
     }
 
-    /// Try to receive a single datagram message on the socket from the remote
+    /// Tries to receive a single datagram message on the socket from the remote
     /// address to which it is connected. On success, returns the number of
     /// bytes read.
     ///
-    /// The function must be called with valid byte array buf of sufficient size
+    /// This method must be called with valid byte array buf of sufficient size
     /// to hold the message bytes. If a message is too long to fit in the
     /// supplied buffer, excess bytes may be discarded.
     ///
@@ -772,13 +878,15 @@ impl UdpSocket {
     }
 
     cfg_io_util! {
-        /// Try to receive data from the stream into the provided buffer, advancing the
+        /// Tries to receive data from the stream into the provided buffer, advancing the
         /// buffer's internal cursor, returning how many bytes were read.
         ///
-        /// The function must be called with valid byte array buf of sufficient size
+        /// This method must be called with valid byte array buf of sufficient size
         /// to hold the message bytes. If a message is too long to fit in the
         /// supplied buffer, excess bytes may be discarded.
         ///
+        /// This method can be used even if `buf` is uninitialized.
+        ///
         /// When there is no pending data, `Err(io::ErrorKind::WouldBlock)` is
         /// returned. This function is usually paired with `readable()`.
         ///
@@ -825,10 +933,10 @@ impl UdpSocket {
                 let dst =
                     unsafe { &mut *(dst as *mut _ as *mut [std::mem::MaybeUninit<u8>] as *mut [u8]) };
 
+                let n = (*self.io).recv(dst)?;
+
                 // Safety: We trust `UdpSocket::recv` to have filled up `n` bytes in the
                 // buffer.
-                let n = (&*self.io).recv(dst)?;
-
                 unsafe {
                     buf.advance_mut(n);
                 }
@@ -837,16 +945,75 @@ impl UdpSocket {
             })
         }
 
-        /// Try to receive a single datagram message on the socket. On success,
+        /// Receives a single datagram message on the socket from the remote address
+        /// to which it is connected, advancing the buffer's internal cursor,
+        /// returning how many bytes were read.
+        ///
+        /// This method must be called with valid byte array buf of sufficient size
+        /// to hold the message bytes. If a message is too long to fit in the
+        /// supplied buffer, excess bytes may be discarded.
+        ///
+        /// This method can be used even if `buf` is uninitialized.
+        ///
+        /// # Examples
+        ///
+        /// ```no_run
+        /// use tokio::net::UdpSocket;
+        /// use std::io;
+        ///
+        /// #[tokio::main]
+        /// async fn main() -> io::Result<()> {
+        ///     // Connect to a peer
+        ///     let socket = UdpSocket::bind("127.0.0.1:8080").await?;
+        ///     socket.connect("127.0.0.1:8081").await?;
+        ///
+        ///     let mut buf = Vec::with_capacity(512);
+        ///     let len = socket.recv_buf(&mut buf).await?;
+        ///
+        ///     println!("received {} bytes {:?}", len, &buf[..len]);
+        ///
+        ///     Ok(())
+        /// }
+        /// ```
+        pub async fn recv_buf<B: BufMut>(&self, buf: &mut B) -> io::Result<usize> {
+            self.io.registration().async_io(Interest::READABLE, || {
+                let dst = buf.chunk_mut();
+                let dst =
+                    unsafe { &mut *(dst as *mut _ as *mut [std::mem::MaybeUninit<u8>] as *mut [u8]) };
+
+                let n = (*self.io).recv(dst)?;
+
+                // Safety: We trust `UdpSocket::recv` to have filled up `n` bytes in the
+                // buffer.
+                unsafe {
+                    buf.advance_mut(n);
+                }
+
+                Ok(n)
+            }).await
+        }
+
+        /// Tries to receive a single datagram message on the socket. On success,
         /// returns the number of bytes read and the origin.
         ///
-        /// The function must be called with valid byte array buf of sufficient size
+        /// This method must be called with valid byte array buf of sufficient size
         /// to hold the message bytes. If a message is too long to fit in the
         /// supplied buffer, excess bytes may be discarded.
         ///
+        /// This method can be used even if `buf` is uninitialized.
+        ///
         /// When there is no pending data, `Err(io::ErrorKind::WouldBlock)` is
         /// returned. This function is usually paired with `readable()`.
         ///
+        /// # Notes
+        /// Note that the socket address **cannot** be implicitly trusted, because it is relatively
+        /// trivial to send a UDP datagram with a spoofed origin in a [packet injection attack].
+        /// Because UDP is stateless and does not validate the origin of a packet,
+        /// the attacker does not need to be able to intercept traffic in order to interfere.
+        /// It is important to be aware of this when designing your application-level protocol.
+        ///
+        /// [packet injection attack]: https://en.wikipedia.org/wiki/Packet_injection
+        ///
         /// # Examples
         ///
         /// ```no_run
@@ -889,10 +1056,10 @@ impl UdpSocket {
                 let dst =
                     unsafe { &mut *(dst as *mut _ as *mut [std::mem::MaybeUninit<u8>] as *mut [u8]) };
 
+                let (n, addr) = (*self.io).recv_from(dst)?;
+
                 // Safety: We trust `UdpSocket::recv_from` to have filled up `n` bytes in the
                 // buffer.
-                let (n, addr) = (&*self.io).recv_from(dst)?;
-
                 unsafe {
                     buf.advance_mut(n);
                 }
@@ -900,6 +1067,62 @@ impl UdpSocket {
                 Ok((n, addr))
             })
         }
+
+        /// Receives a single datagram message on the socket, advancing the
+        /// buffer's internal cursor, returning how many bytes were read and the origin.
+        ///
+        /// This method must be called with valid byte array buf of sufficient size
+        /// to hold the message bytes. If a message is too long to fit in the
+        /// supplied buffer, excess bytes may be discarded.
+        ///
+        /// This method can be used even if `buf` is uninitialized.
+        ///
+        /// # Notes
+        /// Note that the socket address **cannot** be implicitly trusted, because it is relatively
+        /// trivial to send a UDP datagram with a spoofed origin in a [packet injection attack].
+        /// Because UDP is stateless and does not validate the origin of a packet,
+        /// the attacker does not need to be able to intercept traffic in order to interfere.
+        /// It is important to be aware of this when designing your application-level protocol.
+        ///
+        /// [packet injection attack]: https://en.wikipedia.org/wiki/Packet_injection
+        ///
+        /// # Examples
+        ///
+        /// ```no_run
+        /// use tokio::net::UdpSocket;
+        /// use std::io;
+        ///
+        /// #[tokio::main]
+        /// async fn main() -> io::Result<()> {
+        ///     // Connect to a peer
+        ///     let socket = UdpSocket::bind("127.0.0.1:8080").await?;
+        ///     socket.connect("127.0.0.1:8081").await?;
+        ///
+        ///     let mut buf = Vec::with_capacity(512);
+        ///     let (len, addr) = socket.recv_buf_from(&mut buf).await?;
+        ///
+        ///     println!("received {:?} bytes from {:?}", len, addr);
+        ///
+        ///     Ok(())
+        /// }
+        /// ```
+        pub async fn recv_buf_from<B: BufMut>(&self, buf: &mut B) -> io::Result<(usize, SocketAddr)> {
+            self.io.registration().async_io(Interest::READABLE, || {
+                let dst = buf.chunk_mut();
+                let dst =
+                    unsafe { &mut *(dst as *mut _ as *mut [std::mem::MaybeUninit<u8>] as *mut [u8]) };
+
+                let (n, addr) = (*self.io).recv_from(dst)?;
+
+                // Safety: We trust `UdpSocket::recv_from` to have filled up `n` bytes in the
+                // buffer.
+                unsafe {
+                    buf.advance_mut(n);
+                }
+
+                Ok((n,addr))
+            }).await
+        }
     }
 
     /// Sends data on the socket to the given address. On success, returns the
@@ -978,7 +1201,7 @@ impl UdpSocket {
             .poll_write_io(cx, || self.io.send_to(buf, target))
     }
 
-    /// Try to send data on the socket to the given address, but if the send is
+    /// Tries to send data on the socket to the given address, but if the send is
     /// blocked this will return right away.
     ///
     /// This function is usually paired with `writable()`.
@@ -1070,6 +1293,15 @@ impl UdpSocket {
     ///     Ok(())
     /// }
     /// ```
+    ///
+    /// # Notes
+    /// Note that the socket address **cannot** be implicitly trusted, because it is relatively
+    /// trivial to send a UDP datagram with a spoofed origin in a [packet injection attack].
+    /// Because UDP is stateless and does not validate the origin of a packet,
+    /// the attacker does not need to be able to intercept traffic in order to interfere.
+    /// It is important to be aware of this when designing your application-level protocol.
+    ///
+    /// [packet injection attack]: https://en.wikipedia.org/wiki/Packet_injection
     pub async fn recv_from(&self, buf: &mut [u8]) -> io::Result<(usize, SocketAddr)> {
         self.io
             .registration()
@@ -1094,6 +1326,15 @@ impl UdpSocket {
     /// # Errors
     ///
     /// This function may encounter any standard I/O error except `WouldBlock`.
+    ///
+    /// # Notes
+    /// Note that the socket address **cannot** be implicitly trusted, because it is relatively
+    /// trivial to send a UDP datagram with a spoofed origin in a [packet injection attack].
+    /// Because UDP is stateless and does not validate the origin of a packet,
+    /// the attacker does not need to be able to intercept traffic in order to interfere.
+    /// It is important to be aware of this when designing your application-level protocol.
+    ///
+    /// [packet injection attack]: https://en.wikipedia.org/wiki/Packet_injection
     pub fn poll_recv_from(
         &self,
         cx: &mut Context<'_>,
@@ -1116,16 +1357,26 @@ impl UdpSocket {
         Poll::Ready(Ok(addr))
     }
 
-    /// Try to receive a single datagram message on the socket. On success,
+    /// Tries to receive a single datagram message on the socket. On success,
     /// returns the number of bytes read and the origin.
     ///
-    /// The function must be called with valid byte array buf of sufficient size
+    /// This method must be called with valid byte array buf of sufficient size
     /// to hold the message bytes. If a message is too long to fit in the
     /// supplied buffer, excess bytes may be discarded.
     ///
     /// When there is no pending data, `Err(io::ErrorKind::WouldBlock)` is
     /// returned. This function is usually paired with `readable()`.
     ///
+    /// # Notes
+    ///
+    /// Note that the socket address **cannot** be implicitly trusted, because it is relatively
+    /// trivial to send a UDP datagram with a spoofed origin in a [packet injection attack].
+    /// Because UDP is stateless and does not validate the origin of a packet,
+    /// the attacker does not need to be able to intercept traffic in order to interfere.
+    /// It is important to be aware of this when designing your application-level protocol.
+    ///
+    /// [packet injection attack]: https://en.wikipedia.org/wiki/Packet_injection
+    ///
     /// # Examples
     ///
     /// ```no_run
@@ -1170,6 +1421,84 @@ impl UdpSocket {
             .try_io(Interest::READABLE, || self.io.recv_from(buf))
     }
 
+    /// Tries to read or write from the socket using a user-provided IO operation.
+    ///
+    /// If the socket is ready, the provided closure is called. The closure
+    /// should attempt to perform IO operation on the socket by manually
+    /// calling the appropriate syscall. If the operation fails because the
+    /// socket is not actually ready, then the closure should return a
+    /// `WouldBlock` error and the readiness flag is cleared. The return value
+    /// of the closure is then returned by `try_io`.
+    ///
+    /// If the socket is not ready, then the closure is not called
+    /// and a `WouldBlock` error is returned.
+    ///
+    /// The closure should only return a `WouldBlock` error if it has performed
+    /// an IO operation on the socket that failed due to the socket not being
+    /// ready. Returning a `WouldBlock` error in any other situation will
+    /// incorrectly clear the readiness flag, which can cause the socket to
+    /// behave incorrectly.
+    ///
+    /// The closure should not perform the IO operation using any of the methods
+    /// defined on the Tokio `UdpSocket` type, as this will mess with the
+    /// readiness flag and can cause the socket to behave incorrectly.
+    ///
+    /// This method is not intended to be used with combined interests.
+    /// The closure should perform only one type of IO operation, so it should not
+    /// require more than one ready state. This method may panic or sleep forever
+    /// if it is called with a combined interest.
+    ///
+    /// Usually, [`readable()`], [`writable()`] or [`ready()`] is used with this function.
+    ///
+    /// [`readable()`]: UdpSocket::readable()
+    /// [`writable()`]: UdpSocket::writable()
+    /// [`ready()`]: UdpSocket::ready()
+    pub fn try_io<R>(
+        &self,
+        interest: Interest,
+        f: impl FnOnce() -> io::Result<R>,
+    ) -> io::Result<R> {
+        self.io
+            .registration()
+            .try_io(interest, || self.io.try_io(f))
+    }
+
+    /// Reads or writes from the socket using a user-provided IO operation.
+    ///
+    /// The readiness of the socket is awaited and when the socket is ready,
+    /// the provided closure is called. The closure should attempt to perform
+    /// IO operation on the socket by manually calling the appropriate syscall.
+    /// If the operation fails because the socket is not actually ready,
+    /// then the closure should return a `WouldBlock` error. In such case the
+    /// readiness flag is cleared and the socket readiness is awaited again.
+    /// This loop is repeated until the closure returns an `Ok` or an error
+    /// other than `WouldBlock`.
+    ///
+    /// The closure should only return a `WouldBlock` error if it has performed
+    /// an IO operation on the socket that failed due to the socket not being
+    /// ready. Returning a `WouldBlock` error in any other situation will
+    /// incorrectly clear the readiness flag, which can cause the socket to
+    /// behave incorrectly.
+    ///
+    /// The closure should not perform the IO operation using any of the methods
+    /// defined on the Tokio `UdpSocket` type, as this will mess with the
+    /// readiness flag and can cause the socket to behave incorrectly.
+    ///
+    /// This method is not intended to be used with combined interests.
+    /// The closure should perform only one type of IO operation, so it should not
+    /// require more than one ready state. This method may panic or sleep forever
+    /// if it is called with a combined interest.
+    pub async fn async_io<R>(
+        &self,
+        interest: Interest,
+        mut f: impl FnMut() -> io::Result<R>,
+    ) -> io::Result<R> {
+        self.io
+            .registration()
+            .async_io(interest, || self.io.try_io(&mut f))
+            .await
+    }
+
     /// Receives data from the socket, without removing it from the input queue.
     /// On success, returns the number of bytes read and the address from whence
     /// the data came.
@@ -1182,6 +1511,17 @@ impl UdpSocket {
     /// Make sure to always use a sufficiently large buffer to hold the
     /// maximum UDP packet size, which can be up to 65536 bytes in size.
     ///
+    /// MacOS will return an error if you pass a zero-sized buffer.
+    ///
+    /// If you're merely interested in learning the sender of the data at the head of the queue,
+    /// try [`peek_sender`].
+    ///
+    /// Note that the socket address **cannot** be implicitly trusted, because it is relatively
+    /// trivial to send a UDP datagram with a spoofed origin in a [packet injection attack].
+    /// Because UDP is stateless and does not validate the origin of a packet,
+    /// the attacker does not need to be able to intercept traffic in order to interfere.
+    /// It is important to be aware of this when designing your application-level protocol.
+    ///
     /// # Examples
     ///
     /// ```no_run
@@ -1200,6 +1540,9 @@ impl UdpSocket {
     ///     Ok(())
     /// }
     /// ```
+    ///
+    /// [`peek_sender`]: method@Self::peek_sender
+    /// [packet injection attack]: https://en.wikipedia.org/wiki/Packet_injection
     pub async fn peek_from(&self, buf: &mut [u8]) -> io::Result<(usize, SocketAddr)> {
         self.io
             .registration()
@@ -1208,7 +1551,7 @@ impl UdpSocket {
     }
 
     /// Receives data from the socket, without removing it from the input queue.
-    /// On success, returns the number of bytes read.
+    /// On success, returns the sending address of the datagram.
     ///
     /// # Notes
     ///
@@ -1222,6 +1565,17 @@ impl UdpSocket {
     /// Make sure to always use a sufficiently large buffer to hold the
     /// maximum UDP packet size, which can be up to 65536 bytes in size.
     ///
+    /// MacOS will return an error if you pass a zero-sized buffer.
+    ///
+    /// If you're merely interested in learning the sender of the data at the head of the queue,
+    /// try [`poll_peek_sender`].
+    ///
+    /// Note that the socket address **cannot** be implicitly trusted, because it is relatively
+    /// trivial to send a UDP datagram with a spoofed origin in a [packet injection attack].
+    /// Because UDP is stateless and does not validate the origin of a packet,
+    /// the attacker does not need to be able to intercept traffic in order to interfere.
+    /// It is important to be aware of this when designing your application-level protocol.
+    ///
     /// # Return value
     ///
     /// The function returns:
@@ -1233,6 +1587,9 @@ impl UdpSocket {
     /// # Errors
     ///
     /// This function may encounter any standard I/O error except `WouldBlock`.
+    ///
+    /// [`poll_peek_sender`]: method@Self::poll_peek_sender
+    /// [packet injection attack]: https://en.wikipedia.org/wiki/Packet_injection
     pub fn poll_peek_from(
         &self,
         cx: &mut Context<'_>,
@@ -1255,6 +1612,117 @@ impl UdpSocket {
         Poll::Ready(Ok(addr))
     }
 
+    /// Tries to receive data on the socket without removing it from the input queue.
+    /// On success, returns the number of bytes read and the sending address of the
+    /// datagram.
+    ///
+    /// When there is no pending data, `Err(io::ErrorKind::WouldBlock)` is
+    /// returned. This function is usually paired with `readable()`.
+    ///
+    /// # Notes
+    ///
+    /// On Windows, if the data is larger than the buffer specified, the buffer
+    /// is filled with the first part of the data, and peek returns the error
+    /// WSAEMSGSIZE(10040). The excess data is lost.
+    /// Make sure to always use a sufficiently large buffer to hold the
+    /// maximum UDP packet size, which can be up to 65536 bytes in size.
+    ///
+    /// MacOS will return an error if you pass a zero-sized buffer.
+    ///
+    /// If you're merely interested in learning the sender of the data at the head of the queue,
+    /// try [`try_peek_sender`].
+    ///
+    /// Note that the socket address **cannot** be implicitly trusted, because it is relatively
+    /// trivial to send a UDP datagram with a spoofed origin in a [packet injection attack].
+    /// Because UDP is stateless and does not validate the origin of a packet,
+    /// the attacker does not need to be able to intercept traffic in order to interfere.
+    /// It is important to be aware of this when designing your application-level protocol.
+    ///
+    /// [`try_peek_sender`]: method@Self::try_peek_sender
+    /// [packet injection attack]: https://en.wikipedia.org/wiki/Packet_injection
+    pub fn try_peek_from(&self, buf: &mut [u8]) -> io::Result<(usize, SocketAddr)> {
+        self.io
+            .registration()
+            .try_io(Interest::READABLE, || self.io.peek_from(buf))
+    }
+
+    /// Retrieve the sender of the data at the head of the input queue, waiting if empty.
+    ///
+    /// This is equivalent to calling [`peek_from`] with a zero-sized buffer,
+    /// but suppresses the `WSAEMSGSIZE` error on Windows and the "invalid argument" error on macOS.
+    ///
+    /// Note that the socket address **cannot** be implicitly trusted, because it is relatively
+    /// trivial to send a UDP datagram with a spoofed origin in a [packet injection attack].
+    /// Because UDP is stateless and does not validate the origin of a packet,
+    /// the attacker does not need to be able to intercept traffic in order to interfere.
+    /// It is important to be aware of this when designing your application-level protocol.
+    ///
+    /// [`peek_from`]: method@Self::peek_from
+    /// [packet injection attack]: https://en.wikipedia.org/wiki/Packet_injection
+    pub async fn peek_sender(&self) -> io::Result<SocketAddr> {
+        self.io
+            .registration()
+            .async_io(Interest::READABLE, || self.peek_sender_inner())
+            .await
+    }
+
+    /// Retrieve the sender of the data at the head of the input queue,
+    /// scheduling a wakeup if empty.
+    ///
+    /// This is equivalent to calling [`poll_peek_from`] with a zero-sized buffer,
+    /// but suppresses the `WSAEMSGSIZE` error on Windows and the "invalid argument" error on macOS.
+    ///
+    /// # Notes
+    ///
+    /// Note that on multiple calls to a `poll_*` method in the recv direction, only the
+    /// `Waker` from the `Context` passed to the most recent call will be scheduled to
+    /// receive a wakeup.
+    ///
+    /// Note that the socket address **cannot** be implicitly trusted, because it is relatively
+    /// trivial to send a UDP datagram with a spoofed origin in a [packet injection attack].
+    /// Because UDP is stateless and does not validate the origin of a packet,
+    /// the attacker does not need to be able to intercept traffic in order to interfere.
+    /// It is important to be aware of this when designing your application-level protocol.
+    ///
+    /// [`poll_peek_from`]: method@Self::poll_peek_from
+    /// [packet injection attack]: https://en.wikipedia.org/wiki/Packet_injection
+    pub fn poll_peek_sender(&self, cx: &mut Context<'_>) -> Poll<io::Result<SocketAddr>> {
+        self.io
+            .registration()
+            .poll_read_io(cx, || self.peek_sender_inner())
+    }
+
+    /// Try to retrieve the sender of the data at the head of the input queue.
+    ///
+    /// When there is no pending data, `Err(io::ErrorKind::WouldBlock)` is
+    /// returned. This function is usually paired with `readable()`.
+    ///
+    /// Note that the socket address **cannot** be implicitly trusted, because it is relatively
+    /// trivial to send a UDP datagram with a spoofed origin in a [packet injection attack].
+    /// Because UDP is stateless and does not validate the origin of a packet,
+    /// the attacker does not need to be able to intercept traffic in order to interfere.
+    /// It is important to be aware of this when designing your application-level protocol.
+    ///
+    /// [packet injection attack]: https://en.wikipedia.org/wiki/Packet_injection
+    pub fn try_peek_sender(&self) -> io::Result<SocketAddr> {
+        self.io
+            .registration()
+            .try_io(Interest::READABLE, || self.peek_sender_inner())
+    }
+
+    #[inline]
+    fn peek_sender_inner(&self) -> io::Result<SocketAddr> {
+        self.io.try_io(|| {
+            self.as_socket()
+                .peek_sender()?
+                // May be `None` if the platform doesn't populate the sender for some reason.
+                // In testing, that only occurred on macOS if you pass a zero-sized buffer,
+                // but the implementation of `Socket::peek_sender()` covers that.
+                .as_socket()
+                .ok_or_else(|| io::Error::new(io::ErrorKind::Other, "sender not available"))
+        })
+    }
+
     /// Gets the value of the `SO_BROADCAST` option for this socket.
     ///
     /// For more information about this option, see [`set_broadcast`].
@@ -1379,6 +1847,89 @@ impl UdpSocket {
         self.io.set_ttl(ttl)
     }
 
+    /// Gets the value of the `IP_TOS` option for this socket.
+    ///
+    /// For more information about this option, see [`set_tos`].
+    ///
+    /// **NOTE:** On Windows, `IP_TOS` is only supported on [Windows 8+ or
+    /// Windows Server 2012+.](https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-ip-socket-options)
+    ///
+    /// [`set_tos`]: Self::set_tos
+    // https://docs.rs/socket2/0.4.2/src/socket2/socket.rs.html#1178
+    #[cfg(not(any(
+        target_os = "fuchsia",
+        target_os = "redox",
+        target_os = "solaris",
+        target_os = "illumos",
+    )))]
+    #[cfg_attr(
+        docsrs,
+        doc(cfg(not(any(
+            target_os = "fuchsia",
+            target_os = "redox",
+            target_os = "solaris",
+            target_os = "illumos",
+        ))))
+    )]
+    pub fn tos(&self) -> io::Result<u32> {
+        self.as_socket().tos()
+    }
+
+    /// Sets the value for the `IP_TOS` option on this socket.
+    ///
+    /// This value sets the type-of-service field that is used in every packet
+    /// sent from this socket.
+    ///
+    /// **NOTE:** On Windows, `IP_TOS` is only supported on [Windows 8+ or
+    /// Windows Server 2012+.](https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-ip-socket-options)
+    // https://docs.rs/socket2/0.4.2/src/socket2/socket.rs.html#1178
+    #[cfg(not(any(
+        target_os = "fuchsia",
+        target_os = "redox",
+        target_os = "solaris",
+        target_os = "illumos",
+    )))]
+    #[cfg_attr(
+        docsrs,
+        doc(cfg(not(any(
+            target_os = "fuchsia",
+            target_os = "redox",
+            target_os = "solaris",
+            target_os = "illumos",
+        ))))
+    )]
+    pub fn set_tos(&self, tos: u32) -> io::Result<()> {
+        self.as_socket().set_tos(tos)
+    }
+
+    /// Gets the value for the `SO_BINDTODEVICE` option on this socket
+    ///
+    /// This value gets the socket-bound device's interface name.
+    #[cfg(any(target_os = "android", target_os = "fuchsia", target_os = "linux",))]
+    #[cfg_attr(
+        docsrs,
+        doc(cfg(any(target_os = "android", target_os = "fuchsia", target_os = "linux",)))
+    )]
+    pub fn device(&self) -> io::Result<Option<Vec<u8>>> {
+        self.as_socket().device()
+    }
+
+    /// Sets the value for the `SO_BINDTODEVICE` option on this socket
+    ///
+    /// If a socket is bound to an interface, only packets received from that
+    /// particular interface are processed by the socket. Note that this only
+    /// works for some socket types, particularly `AF_INET` sockets.
+    ///
+    /// If `interface` is `None` or an empty string it removes the binding.
+    #[cfg(all(any(target_os = "android", target_os = "fuchsia", target_os = "linux")))]
+    #[cfg_attr(
+        docsrs,
+        doc(cfg(all(any(target_os = "android", target_os = "fuchsia", target_os = "linux"))))
+    )]
+    pub fn bind_device(&self, interface: Option<&[u8]>) -> io::Result<()> {
+        self.as_socket().bind_device(interface)
+    }
+
     /// Executes an operation of the `IP_ADD_MEMBERSHIP` type.
     ///
     /// This function specifies a new multicast group for this socket to join.
@@ -1459,7 +2010,7 @@ impl fmt::Debug for UdpSocket {
     }
 }
 
-#[cfg(all(unix))]
+#[cfg(unix)]
 mod sys {
     use super::UdpSocket;
     use std::os::unix::prelude::*;
@@ -1469,16 +2020,30 @@ mod sys {
             self.io.as_raw_fd()
         }
     }
+
+    #[cfg(not(tokio_no_as_fd))]
+    impl AsFd for UdpSocket {
+        fn as_fd(&self) -> BorrowedFd<'_> {
+            unsafe { BorrowedFd::borrow_raw(self.as_raw_fd()) }
+        }
+    }
 }
 
-#[cfg(windows)]
-mod sys {
-    use super::UdpSocket;
-    use std::os::windows::prelude::*;
+cfg_windows! {
+    use crate::os::windows::io::{AsRawSocket, RawSocket};
+    #[cfg(not(tokio_no_as_fd))]
+    use crate::os::windows::io::{AsSocket, BorrowedSocket};
 
     impl AsRawSocket for UdpSocket {
         fn as_raw_socket(&self) -> RawSocket {
             self.io.as_raw_socket()
         }
     }
+
+    #[cfg(not(tokio_no_as_fd))]
+    impl AsSocket for UdpSocket {
+        fn as_socket(&self) -> BorrowedSocket<'_> {
+            unsafe { BorrowedSocket::borrow_raw(self.as_raw_socket()) }
+        }
+    }
 }
diff --git a/vendor/tokio/src/net/unix/datagram/socket.rs b/vendor/tokio/src/net/unix/datagram/socket.rs
index 2d2177803..c97d101aa 100644
--- a/vendor/tokio/src/net/unix/datagram/socket.rs
+++ b/vendor/tokio/src/net/unix/datagram/socket.rs
@@ -1,10 +1,11 @@
 use crate::io::{Interest, PollEvented, ReadBuf, Ready};
 use crate::net::unix::SocketAddr;
 
-use std::convert::TryFrom;
 use std::fmt;
 use std::io;
 use std::net::Shutdown;
+#[cfg(not(tokio_no_as_fd))]
+use std::os::unix::io::{AsFd, BorrowedFd};
 use std::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
 use std::os::unix::net;
 use std::path::Path;
@@ -90,13 +91,14 @@ cfg_net_unix! {
     /// # Ok(())
     /// # }
     /// ```
+    #[cfg_attr(docsrs, doc(alias = "uds"))]
     pub struct UnixDatagram {
         io: PollEvented<mio::net::UnixDatagram>,
     }
 }
 
 impl UnixDatagram {
-    /// Wait for any of the requested ready states.
+    /// Waits for any of the requested ready states.
     ///
     /// This function is usually paired with `try_recv()` or `try_send()`. It
     /// can be used to concurrently recv / send to the same socket on a single
@@ -104,7 +106,9 @@ impl UnixDatagram {
     ///
     /// The function may complete without the socket being ready. This is a
     /// false-positive and attempting an operation will return with
-    /// `io::ErrorKind::WouldBlock`.
+    /// `io::ErrorKind::WouldBlock`. The function can also return with an empty
+    /// [`Ready`] set, so you should always check the returned value and possibly
+    /// wait again if the requested states are not set.
     ///
     /// # Cancel safety
     ///
@@ -169,7 +173,7 @@ impl UnixDatagram {
         Ok(event.ready)
     }
 
-    /// Wait for the socket to become writable.
+    /// Waits for the socket to become writable.
     ///
     /// This function is equivalent to `ready(Interest::WRITABLE)` and is
     /// usually paired with `try_send()` or `try_send_to()`.
@@ -226,7 +230,40 @@ impl UnixDatagram {
         Ok(())
     }
 
-    /// Wait for the socket to become readable.
+    /// Polls for write/send readiness.
+    ///
+    /// If the socket is not currently ready for sending, this method will
+    /// store a clone of the `Waker` from the provided `Context`. When the socket
+    /// becomes ready for sending, `Waker::wake` will be called on the
+    /// waker.
+    ///
+    /// Note that on multiple calls to `poll_send_ready` or `poll_send`, only
+    /// the `Waker` from the `Context` passed to the most recent call is
+    /// scheduled to receive a wakeup. (However, `poll_recv_ready` retains a
+    /// second, independent waker.)
+    ///
+    /// This function is intended for cases where creating and pinning a future
+    /// via [`writable`] is not feasible. Where possible, using [`writable`] is
+    /// preferred, as this supports polling from multiple tasks at once.
+    ///
+    /// # Return value
+    ///
+    /// The function returns:
+    ///
+    /// * `Poll::Pending` if the socket is not ready for writing.
+    /// * `Poll::Ready(Ok(()))` if the socket is ready for writing.
+    /// * `Poll::Ready(Err(e))` if an error is encountered.
+    ///
+    /// # Errors
+    ///
+    /// This function may encounter any standard I/O error except `WouldBlock`.
+    ///
+    /// [`writable`]: method@Self::writable
+    pub fn poll_send_ready(&self, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+        self.io.registration().poll_write_ready(cx).map_ok(|_| ())
+    }
+
+    /// Waits for the socket to become readable.
     ///
     /// This function is equivalent to `ready(Interest::READABLE)` and is usually
     /// paired with `try_recv()`.
@@ -289,6 +326,39 @@ impl UnixDatagram {
         Ok(())
     }
 
+    /// Polls for read/receive readiness.
+    ///
+    /// If the socket is not currently ready for receiving, this method will
+    /// store a clone of the `Waker` from the provided `Context`. When the
+    /// socket becomes ready for reading, `Waker::wake` will be called on the
+    /// waker.
+    ///
+    /// Note that on multiple calls to `poll_recv_ready`, `poll_recv` or
+    /// `poll_peek`, only the `Waker` from the `Context` passed to the most
+    /// recent call is scheduled to receive a wakeup. (However,
+    /// `poll_send_ready` retains a second, independent waker.)
+    ///
+    /// This function is intended for cases where creating and pinning a future
+    /// via [`readable`] is not feasible. Where possible, using [`readable`] is
+    /// preferred, as this supports polling from multiple tasks at once.
+    ///
+    /// # Return value
+    ///
+    /// The function returns:
+    ///
+    /// * `Poll::Pending` if the socket is not ready for reading.
+    /// * `Poll::Ready(Ok(()))` if the socket is ready for reading.
+    /// * `Poll::Ready(Err(e))` if an error is encountered.
+    ///
+    /// # Errors
+    ///
+    /// This function may encounter any standard I/O error except `WouldBlock`.
+    ///
+    /// [`readable`]: method@Self::readable
+    pub fn poll_recv_ready(&self, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+        self.io.registration().poll_read_ready(cx).map_ok(|_| ())
+    }
+
     /// Creates a new `UnixDatagram` bound to the specified path.
     ///
     /// # Examples
@@ -358,13 +428,21 @@ impl UnixDatagram {
     /// Creates new `UnixDatagram` from a `std::os::unix::net::UnixDatagram`.
     ///
     /// This function is intended to be used to wrap a UnixDatagram from the
-    /// standard library in the Tokio equivalent. The conversion assumes
-    /// nothing about the underlying datagram; it is left up to the user to set
-    /// it in non-blocking mode.
+    /// standard library in the Tokio equivalent.
+    ///
+    /// # Notes
+    ///
+    /// The caller is responsible for ensuring that the socker is in
+    /// non-blocking mode. Otherwise all I/O operations on the socket
+    /// will block the thread, which will cause unexpected behavior.
+    /// Non-blocking mode can be set using [`set_nonblocking`].
+    ///
+    /// [`set_nonblocking`]: std::os::unix::net::UnixDatagram::set_nonblocking
     ///
     /// # Panics
     ///
-    /// This function panics if thread-local runtime is not set.
+    /// This function panics if it is not called from within a runtime with
+    /// IO enabled.
     ///
     /// The runtime is usually set implicitly when this function is called
     /// from a future driven by a Tokio runtime, otherwise runtime can be set
@@ -391,30 +469,29 @@ impl UnixDatagram {
     /// # Ok(())
     /// # }
     /// ```
+    #[track_caller]
     pub fn from_std(datagram: net::UnixDatagram) -> io::Result<UnixDatagram> {
         let socket = mio::net::UnixDatagram::from_std(datagram);
         let io = PollEvented::new(socket)?;
         Ok(UnixDatagram { io })
     }
 
-    /// Turn a [`tokio::net::UnixDatagram`] into a [`std::os::unix::net::UnixDatagram`].
+    /// Turns a [`tokio::net::UnixDatagram`] into a [`std::os::unix::net::UnixDatagram`].
     ///
     /// The returned [`std::os::unix::net::UnixDatagram`] will have nonblocking
-    /// mode set as `true`.  Use [`set_nonblocking`] to change the blocking mode
+    /// mode set as `true`. Use [`set_nonblocking`] to change the blocking mode
     /// if needed.
     ///
     /// # Examples
     ///
     /// ```rust,no_run
-    /// use std::error::Error;
-    ///
-    /// #[tokio::main]
-    /// async fn main() -> Result<(), Box<dyn Error>> {
-    ///     let tokio_socket = tokio::net::UnixDatagram::bind("127.0.0.1:0")?;
-    ///     let std_socket = tokio_socket.into_std()?;
-    ///     std_socket.set_nonblocking(false)?;
-    ///     Ok(())
-    /// }
+    /// # use std::error::Error;
+    /// # async fn dox() -> Result<(), Box<dyn Error>> {
+    /// let tokio_socket = tokio::net::UnixDatagram::bind("/path/to/the/socket")?;
+    /// let std_socket = tokio_socket.into_std()?;
+    /// std_socket.set_nonblocking(false)?;
+    /// # Ok(())
+    /// # }
     /// ```
     ///
     /// [`tokio::net::UnixDatagram`]: UnixDatagram
@@ -548,7 +625,7 @@ impl UnixDatagram {
             .await
     }
 
-    /// Try to send a datagram to the peer without waiting.
+    /// Tries to send a datagram to the peer without waiting.
     ///
     /// # Examples
     ///
@@ -592,7 +669,7 @@ impl UnixDatagram {
             .try_io(Interest::WRITABLE, || self.io.send(buf))
     }
 
-    /// Try to send a datagram to the peer without waiting.
+    /// Tries to send a datagram to the peer without waiting.
     ///
     /// # Examples
     ///
@@ -678,7 +755,7 @@ impl UnixDatagram {
             .await
     }
 
-    /// Try to receive a datagram from the peer without waiting.
+    /// Tries to receive a datagram from the peer without waiting.
     ///
     /// # Examples
     ///
@@ -729,7 +806,9 @@ impl UnixDatagram {
     }
 
     cfg_io_util! {
-        /// Try to receive data from the socket without waiting.
+        /// Tries to receive data from the socket without waiting.
+        ///
+        /// This method can be used even if `buf` is uninitialized.
         ///
         /// # Examples
         ///
@@ -778,7 +857,7 @@ impl UnixDatagram {
 
                 // Safety: We trust `UnixDatagram::recv_from` to have filled up `n` bytes in the
                 // buffer.
-                let (n, addr) = (&*self.io).recv_from(dst)?;
+                let (n, addr) = (*self.io).recv_from(dst)?;
 
                 unsafe {
                     buf.advance_mut(n);
@@ -790,9 +869,64 @@ impl UnixDatagram {
             Ok((n, SocketAddr(addr)))
         }
 
-        /// Try to read data from the stream into the provided buffer, advancing the
+        /// Receives from the socket, advances the
+        /// buffer's internal cursor and returns how many bytes were read and the origin.
+        ///
+        /// This method can be used even if `buf` is uninitialized.
+        ///
+        /// # Examples
+        /// ```
+        /// # use std::error::Error;
+        /// # #[tokio::main]
+        /// # async fn main() -> Result<(), Box<dyn Error>> {
+        /// use tokio::net::UnixDatagram;
+        /// use tempfile::tempdir;
+        ///
+        /// // We use a temporary directory so that the socket
+        /// // files left by the bound sockets will get cleaned up.
+        /// let tmp = tempdir()?;
+        ///
+        /// // Bind each socket to a filesystem path
+        /// let tx_path = tmp.path().join("tx");
+        /// let tx = UnixDatagram::bind(&tx_path)?;
+        /// let rx_path = tmp.path().join("rx");
+        /// let rx = UnixDatagram::bind(&rx_path)?;
+        ///
+        /// let bytes = b"hello world";
+        /// tx.send_to(bytes, &rx_path).await?;
+        ///
+        /// let mut buf = Vec::with_capacity(24);
+        /// let (size, addr) = rx.recv_buf_from(&mut buf).await?;
+        ///
+        /// let dgram = &buf[..size];
+        /// assert_eq!(dgram, bytes);
+        /// assert_eq!(addr.as_pathname().unwrap(), &tx_path);
+        ///
+        /// # Ok(())
+        /// # }
+        /// ```
+        pub async fn recv_buf_from<B: BufMut>(&self, buf: &mut B) -> io::Result<(usize, SocketAddr)> {
+            self.io.registration().async_io(Interest::READABLE, || {
+                let dst = buf.chunk_mut();
+                let dst =
+                    unsafe { &mut *(dst as *mut _ as *mut [std::mem::MaybeUninit<u8>] as *mut [u8]) };
+
+                // Safety: We trust `UnixDatagram::recv_from` to have filled up `n` bytes in the
+                // buffer.
+                let (n, addr) = (*self.io).recv_from(dst)?;
+
+                unsafe {
+                    buf.advance_mut(n);
+                }
+                Ok((n,SocketAddr(addr)))
+            }).await
+        }
+
+        /// Tries to read data from the stream into the provided buffer, advancing the
         /// buffer's internal cursor, returning how many bytes were read.
         ///
+        /// This method can be used even if `buf` is uninitialized.
+        ///
         /// # Examples
         ///
         /// ```no_run
@@ -841,7 +975,7 @@ impl UnixDatagram {
 
                 // Safety: We trust `UnixDatagram::recv` to have filled up `n` bytes in the
                 // buffer.
-                let n = (&*self.io).recv(dst)?;
+                let n = (*self.io).recv(dst)?;
 
                 unsafe {
                     buf.advance_mut(n);
@@ -850,6 +984,52 @@ impl UnixDatagram {
                 Ok(n)
             })
         }
+
+        /// Receives data from the socket from the address to which it is connected,
+        /// advancing the buffer's internal cursor, returning how many bytes were read.
+        ///
+        /// This method can be used even if `buf` is uninitialized.
+        ///
+        /// # Examples
+        /// ```
+        /// # use std::error::Error;
+        /// # #[tokio::main]
+        /// # async fn main() -> Result<(), Box<dyn Error>> {
+        /// use tokio::net::UnixDatagram;
+        ///
+        /// // Create the pair of sockets
+        /// let (sock1, sock2) = UnixDatagram::pair()?;
+        ///
+        /// // Since the sockets are paired, the paired send/recv
+        /// // functions can be used
+        /// let bytes = b"hello world";
+        /// sock1.send(bytes).await?;
+        ///
+        /// let mut buff = Vec::with_capacity(24);
+        /// let size = sock2.recv_buf(&mut buff).await?;
+        ///
+        /// let dgram = &buff[..size];
+        /// assert_eq!(dgram, bytes);
+        ///
+        /// # Ok(())
+        /// # }
+        /// ```
+        pub async fn recv_buf<B: BufMut>(&self, buf: &mut B) -> io::Result<usize> {
+            self.io.registration().async_io(Interest::READABLE, || {
+                let dst = buf.chunk_mut();
+                let dst =
+                    unsafe { &mut *(dst as *mut _ as *mut [std::mem::MaybeUninit<u8>] as *mut [u8]) };
+
+                // Safety: We trust `UnixDatagram::recv_from` to have filled up `n` bytes in the
+                // buffer.
+                let n = (*self.io).recv(dst)?;
+
+                unsafe {
+                    buf.advance_mut(n);
+                }
+                Ok(n)
+            }).await
+        }
     }
 
     /// Sends data on the socket to the specified address.
@@ -1091,7 +1271,7 @@ impl UnixDatagram {
         Poll::Ready(Ok(()))
     }
 
-    /// Try to receive data from the socket without waiting.
+    /// Tries to receive data from the socket without waiting.
     ///
     /// # Examples
     ///
@@ -1143,6 +1323,84 @@ impl UnixDatagram {
         Ok((n, SocketAddr(addr)))
     }
 
+    /// Tries to read or write from the socket using a user-provided IO operation.
+    ///
+    /// If the socket is ready, the provided closure is called. The closure
+    /// should attempt to perform IO operation on the socket by manually
+    /// calling the appropriate syscall. If the operation fails because the
+    /// socket is not actually ready, then the closure should return a
+    /// `WouldBlock` error and the readiness flag is cleared. The return value
+    /// of the closure is then returned by `try_io`.
+    ///
+    /// If the socket is not ready, then the closure is not called
+    /// and a `WouldBlock` error is returned.
+    ///
+    /// The closure should only return a `WouldBlock` error if it has performed
+    /// an IO operation on the socket that failed due to the socket not being
+    /// ready. Returning a `WouldBlock` error in any other situation will
+    /// incorrectly clear the readiness flag, which can cause the socket to
+    /// behave incorrectly.
+    ///
+    /// The closure should not perform the IO operation using any of the methods
+    /// defined on the Tokio `UnixDatagram` type, as this will mess with the
+    /// readiness flag and can cause the socket to behave incorrectly.
+    ///
+    /// This method is not intended to be used with combined interests.
+    /// The closure should perform only one type of IO operation, so it should not
+    /// require more than one ready state. This method may panic or sleep forever
+    /// if it is called with a combined interest.
+    ///
+    /// Usually, [`readable()`], [`writable()`] or [`ready()`] is used with this function.
+    ///
+    /// [`readable()`]: UnixDatagram::readable()
+    /// [`writable()`]: UnixDatagram::writable()
+    /// [`ready()`]: UnixDatagram::ready()
+    pub fn try_io<R>(
+        &self,
+        interest: Interest,
+        f: impl FnOnce() -> io::Result<R>,
+    ) -> io::Result<R> {
+        self.io
+            .registration()
+            .try_io(interest, || self.io.try_io(f))
+    }
+
+    /// Reads or writes from the socket using a user-provided IO operation.
+    ///
+    /// The readiness of the socket is awaited and when the socket is ready,
+    /// the provided closure is called. The closure should attempt to perform
+    /// IO operation on the socket by manually calling the appropriate syscall.
+    /// If the operation fails because the socket is not actually ready,
+    /// then the closure should return a `WouldBlock` error. In such case the
+    /// readiness flag is cleared and the socket readiness is awaited again.
+    /// This loop is repeated until the closure returns an `Ok` or an error
+    /// other than `WouldBlock`.
+    ///
+    /// The closure should only return a `WouldBlock` error if it has performed
+    /// an IO operation on the socket that failed due to the socket not being
+    /// ready. Returning a `WouldBlock` error in any other situation will
+    /// incorrectly clear the readiness flag, which can cause the socket to
+    /// behave incorrectly.
+    ///
+    /// The closure should not perform the IO operation using any of the methods
+    /// defined on the Tokio `UnixDatagram` type, as this will mess with the
+    /// readiness flag and can cause the socket to behave incorrectly.
+    ///
+    /// This method is not intended to be used with combined interests.
+    /// The closure should perform only one type of IO operation, so it should not
+    /// require more than one ready state. This method may panic or sleep forever
+    /// if it is called with a combined interest.
+    pub async fn async_io<R>(
+        &self,
+        interest: Interest,
+        mut f: impl FnMut() -> io::Result<R>,
+    ) -> io::Result<R> {
+        self.io
+            .registration()
+            .async_io(interest, || self.io.try_io(&mut f))
+            .await
+    }
+
     /// Returns the local address that this socket is bound to.
     ///
     /// # Examples
@@ -1319,3 +1577,10 @@ impl AsRawFd for UnixDatagram {
         self.io.as_raw_fd()
     }
 }
+
+#[cfg(not(tokio_no_as_fd))]
+impl AsFd for UnixDatagram {
+    fn as_fd(&self) -> BorrowedFd<'_> {
+        unsafe { BorrowedFd::borrow_raw(self.as_raw_fd()) }
+    }
+}
diff --git a/vendor/tokio/src/net/unix/listener.rs b/vendor/tokio/src/net/unix/listener.rs
index efb9503d4..37a5a4ae4 100644
--- a/vendor/tokio/src/net/unix/listener.rs
+++ b/vendor/tokio/src/net/unix/listener.rs
@@ -1,9 +1,10 @@
 use crate::io::{Interest, PollEvented};
 use crate::net::unix::{SocketAddr, UnixStream};
 
-use std::convert::TryFrom;
 use std::fmt;
 use std::io;
+#[cfg(not(tokio_no_as_fd))]
+use std::os::unix::io::{AsFd, BorrowedFd};
 use std::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
 use std::os::unix::net;
 use std::path::Path;
@@ -44,6 +45,7 @@ cfg_net_unix! {
     ///     }
     /// }
     /// ```
+    #[cfg_attr(docsrs, doc(alias = "uds"))]
     pub struct UnixListener {
         io: PollEvented<mio::net::UnixListener>,
     }
@@ -54,11 +56,13 @@ impl UnixListener {
     ///
     /// # Panics
     ///
-    /// This function panics if thread-local runtime is not set.
+    /// This function panics if it is not called from within a runtime with
+    /// IO enabled.
     ///
     /// The runtime is usually set implicitly when this function is called
     /// from a future driven by a tokio runtime, otherwise runtime can be set
     /// explicitly with [`Runtime::enter`](crate::runtime::Runtime::enter) function.
+    #[track_caller]
     pub fn bind<P>(path: P) -> io::Result<UnixListener>
     where
         P: AsRef<Path>,
@@ -71,40 +75,62 @@ impl UnixListener {
     /// Creates new `UnixListener` from a `std::os::unix::net::UnixListener `.
     ///
     /// This function is intended to be used to wrap a UnixListener from the
-    /// standard library in the Tokio equivalent. The conversion assumes
-    /// nothing about the underlying listener; it is left up to the user to set
-    /// it in non-blocking mode.
+    /// standard library in the Tokio equivalent.
+    ///
+    /// # Notes
+    ///
+    /// The caller is responsible for ensuring that the listener is in
+    /// non-blocking mode. Otherwise all I/O operations on the listener
+    /// will block the thread, which will cause unexpected behavior.
+    /// Non-blocking mode can be set using [`set_nonblocking`].
+    ///
+    /// [`set_nonblocking`]: std::os::unix::net::UnixListener::set_nonblocking
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::UnixListener;
+    /// use std::os::unix::net::UnixListener as StdUnixListener;
+    /// # use std::error::Error;
+    ///
+    /// # async fn dox() -> Result<(), Box<dyn Error>> {
+    /// let std_listener = StdUnixListener::bind("/path/to/the/socket")?;
+    /// std_listener.set_nonblocking(true)?;
+    /// let listener = UnixListener::from_std(std_listener)?;
+    /// # Ok(())
+    /// # }
+    /// ```
     ///
     /// # Panics
     ///
-    /// This function panics if thread-local runtime is not set.
+    /// This function panics if it is not called from within a runtime with
+    /// IO enabled.
     ///
     /// The runtime is usually set implicitly when this function is called
     /// from a future driven by a tokio runtime, otherwise runtime can be set
     /// explicitly with [`Runtime::enter`](crate::runtime::Runtime::enter) function.
+    #[track_caller]
     pub fn from_std(listener: net::UnixListener) -> io::Result<UnixListener> {
         let listener = mio::net::UnixListener::from_std(listener);
         let io = PollEvented::new(listener)?;
         Ok(UnixListener { io })
     }
 
-    /// Turn a [`tokio::net::UnixListener`] into a [`std::os::unix::net::UnixListener`].
+    /// Turns a [`tokio::net::UnixListener`] into a [`std::os::unix::net::UnixListener`].
     ///
     /// The returned [`std::os::unix::net::UnixListener`] will have nonblocking mode
-    /// set as `true`.  Use [`set_nonblocking`] to change the blocking mode if needed.
+    /// set as `true`. Use [`set_nonblocking`] to change the blocking mode if needed.
     ///
     /// # Examples
     ///
     /// ```rust,no_run
-    /// use std::error::Error;
-    ///
-    /// #[tokio::main]
-    /// async fn main() -> Result<(), Box<dyn Error>> {
-    ///     let tokio_listener = tokio::net::UnixListener::bind("127.0.0.1:0")?;
-    ///     let std_listener = tokio_listener.into_std()?;
-    ///     std_listener.set_nonblocking(false)?;
-    ///     Ok(())
-    /// }
+    /// # use std::error::Error;
+    /// # async fn dox() -> Result<(), Box<dyn Error>> {
+    /// let tokio_listener = tokio::net::UnixListener::bind("/path/to/the/socket")?;
+    /// let std_listener = tokio_listener.into_std()?;
+    /// std_listener.set_nonblocking(false)?;
+    /// # Ok(())
+    /// # }
     /// ```
     ///
     /// [`tokio::net::UnixListener`]: UnixListener
@@ -184,3 +210,10 @@ impl AsRawFd for UnixListener {
         self.io.as_raw_fd()
     }
 }
+
+#[cfg(not(tokio_no_as_fd))]
+impl AsFd for UnixListener {
+    fn as_fd(&self) -> BorrowedFd<'_> {
+        unsafe { BorrowedFd::borrow_raw(self.as_raw_fd()) }
+    }
+}
diff --git a/vendor/tokio/src/net/unix/mod.rs b/vendor/tokio/src/net/unix/mod.rs
index c3046f17e..a49b70af3 100644
--- a/vendor/tokio/src/net/unix/mod.rs
+++ b/vendor/tokio/src/net/unix/mod.rs
@@ -1,5 +1,4 @@
-//! Unix domain socket utility types
-
+//! Unix specific network types.
 // This module does not currently provide any public API, but it was
 // unintentionally defined as a public module. Hide it from the documentation
 // instead of changing it to a private module to avoid breakage.
@@ -22,3 +21,17 @@ pub(crate) use stream::UnixStream;
 
 mod ucred;
 pub use ucred::UCred;
+
+pub mod pipe;
+
+/// A type representing process and process group IDs.
+#[allow(non_camel_case_types)]
+pub type uid_t = u32;
+
+/// A type representing user ID.
+#[allow(non_camel_case_types)]
+pub type gid_t = u32;
+
+/// A type representing group ID.
+#[allow(non_camel_case_types)]
+pub type pid_t = i32;
diff --git a/vendor/tokio/src/net/unix/pipe.rs b/vendor/tokio/src/net/unix/pipe.rs
new file mode 100644
index 000000000..188ac68b1
--- /dev/null
+++ b/vendor/tokio/src/net/unix/pipe.rs
@@ -0,0 +1,1222 @@
+//! Unix pipe types.
+
+use crate::io::interest::Interest;
+use crate::io::{AsyncRead, AsyncWrite, PollEvented, ReadBuf, Ready};
+
+use mio::unix::pipe as mio_pipe;
+use std::fs::File;
+use std::io::{self, Read, Write};
+use std::os::unix::fs::{FileTypeExt, OpenOptionsExt};
+#[cfg(not(tokio_no_as_fd))]
+use std::os::unix::io::{AsFd, BorrowedFd};
+use std::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
+use std::path::Path;
+use std::pin::Pin;
+use std::task::{Context, Poll};
+
+cfg_io_util! {
+    use bytes::BufMut;
+}
+
+/// Options and flags which can be used to configure how a FIFO file is opened.
+///
+/// This builder allows configuring how to create a pipe end from a FIFO file.
+/// Generally speaking, when using `OpenOptions`, you'll first call [`new`],
+/// then chain calls to methods to set each option, then call either
+/// [`open_receiver`] or [`open_sender`], passing the path of the FIFO file you
+/// are trying to open. This will give you a [`io::Result`][result] with a pipe
+/// end inside that you can further operate on.
+///
+/// [`new`]: OpenOptions::new
+/// [`open_receiver`]: OpenOptions::open_receiver
+/// [`open_sender`]: OpenOptions::open_sender
+/// [result]: std::io::Result
+///
+/// # Examples
+///
+/// Opening a pair of pipe ends from a FIFO file:
+///
+/// ```no_run
+/// use tokio::net::unix::pipe;
+/// # use std::error::Error;
+///
+/// const FIFO_NAME: &str = "path/to/a/fifo";
+///
+/// # async fn dox() -> Result<(), Box<dyn Error>> {
+/// let rx = pipe::OpenOptions::new().open_receiver(FIFO_NAME)?;
+/// let tx = pipe::OpenOptions::new().open_sender(FIFO_NAME)?;
+/// # Ok(())
+/// # }
+/// ```
+///
+/// Opening a [`Sender`] on Linux when you are sure the file is a FIFO:
+///
+/// ```ignore
+/// use tokio::net::unix::pipe;
+/// use nix::{unistd::mkfifo, sys::stat::Mode};
+/// # use std::error::Error;
+///
+/// // Our program has exclusive access to this path.
+/// const FIFO_NAME: &str = "path/to/a/new/fifo";
+///
+/// # async fn dox() -> Result<(), Box<dyn Error>> {
+/// mkfifo(FIFO_NAME, Mode::S_IRWXU)?;
+/// let tx = pipe::OpenOptions::new()
+///     .read_write(true)
+///     .unchecked(true)
+///     .open_sender(FIFO_NAME)?;
+/// # Ok(())
+/// # }
+/// ```
+#[derive(Clone, Debug)]
+pub struct OpenOptions {
+    #[cfg(target_os = "linux")]
+    read_write: bool,
+    unchecked: bool,
+}
+
+impl OpenOptions {
+    /// Creates a blank new set of options ready for configuration.
+    ///
+    /// All options are initially set to `false`.
+    pub fn new() -> OpenOptions {
+        OpenOptions {
+            #[cfg(target_os = "linux")]
+            read_write: false,
+            unchecked: false,
+        }
+    }
+
+    /// Sets the option for read-write access.
+    ///
+    /// This option, when true, will indicate that a FIFO file will be opened
+    /// in read-write access mode. This operation is not defined by the POSIX
+    /// standard and is only guaranteed to work on Linux.
+    ///
+    /// # Examples
+    ///
+    /// Opening a [`Sender`] even if there are no open reading ends:
+    ///
+    /// ```ignore
+    /// use tokio::net::unix::pipe;
+    ///
+    /// let tx = pipe::OpenOptions::new()
+    ///     .read_write(true)
+    ///     .open_sender("path/to/a/fifo");
+    /// ```
+    ///
+    /// Opening a resilient [`Receiver`] i.e. a reading pipe end which will not
+    /// fail with [`UnexpectedEof`] during reading if all writing ends of the
+    /// pipe close the FIFO file.
+    ///
+    /// [`UnexpectedEof`]: std::io::ErrorKind::UnexpectedEof
+    ///
+    /// ```ignore
+    /// use tokio::net::unix::pipe;
+    ///
+    /// let tx = pipe::OpenOptions::new()
+    ///     .read_write(true)
+    ///     .open_receiver("path/to/a/fifo");
+    /// ```
+    #[cfg(target_os = "linux")]
+    #[cfg_attr(docsrs, doc(cfg(target_os = "linux")))]
+    pub fn read_write(&mut self, value: bool) -> &mut Self {
+        self.read_write = value;
+        self
+    }
+
+    /// Sets the option to skip the check for FIFO file type.
+    ///
+    /// By default, [`open_receiver`] and [`open_sender`] functions will check
+    /// if the opened file is a FIFO file. Set this option to `true` if you are
+    /// sure the file is a FIFO file.
+    ///
+    /// [`open_receiver`]: OpenOptions::open_receiver
+    /// [`open_sender`]: OpenOptions::open_sender
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::unix::pipe;
+    /// use nix::{unistd::mkfifo, sys::stat::Mode};
+    /// # use std::error::Error;
+    ///
+    /// // Our program has exclusive access to this path.
+    /// const FIFO_NAME: &str = "path/to/a/new/fifo";
+    ///
+    /// # async fn dox() -> Result<(), Box<dyn Error>> {
+    /// mkfifo(FIFO_NAME, Mode::S_IRWXU)?;
+    /// let rx = pipe::OpenOptions::new()
+    ///     .unchecked(true)
+    ///     .open_receiver(FIFO_NAME)?;
+    /// # Ok(())
+    /// # }
+    /// ```
+    pub fn unchecked(&mut self, value: bool) -> &mut Self {
+        self.unchecked = value;
+        self
+    }
+
+    /// Creates a [`Receiver`] from a FIFO file with the options specified by `self`.
+    ///
+    /// This function will open the FIFO file at the specified path, possibly
+    /// check if it is a pipe, and associate the pipe with the default event
+    /// loop for reading.
+    ///
+    /// # Errors
+    ///
+    /// If the file type check fails, this function will fail with `io::ErrorKind::InvalidInput`.
+    /// This function may also fail with other standard OS errors.
+    ///
+    /// # Panics
+    ///
+    /// This function panics if it is not called from within a runtime with
+    /// IO enabled.
+    ///
+    /// The runtime is usually set implicitly when this function is called
+    /// from a future driven by a tokio runtime, otherwise runtime can be set
+    /// explicitly with [`Runtime::enter`](crate::runtime::Runtime::enter) function.
+    pub fn open_receiver<P: AsRef<Path>>(&self, path: P) -> io::Result<Receiver> {
+        let file = self.open(path.as_ref(), PipeEnd::Receiver)?;
+        Receiver::from_file_unchecked(file)
+    }
+
+    /// Creates a [`Sender`] from a FIFO file with the options specified by `self`.
+    ///
+    /// This function will open the FIFO file at the specified path, possibly
+    /// check if it is a pipe, and associate the pipe with the default event
+    /// loop for writing.
+    ///
+    /// # Errors
+    ///
+    /// If the file type check fails, this function will fail with `io::ErrorKind::InvalidInput`.
+    /// If the file is not opened in read-write access mode and the file is not
+    /// currently open for reading, this function will fail with `ENXIO`.
+    /// This function may also fail with other standard OS errors.
+    ///
+    /// # Panics
+    ///
+    /// This function panics if it is not called from within a runtime with
+    /// IO enabled.
+    ///
+    /// The runtime is usually set implicitly when this function is called
+    /// from a future driven by a tokio runtime, otherwise runtime can be set
+    /// explicitly with [`Runtime::enter`](crate::runtime::Runtime::enter) function.
+    pub fn open_sender<P: AsRef<Path>>(&self, path: P) -> io::Result<Sender> {
+        let file = self.open(path.as_ref(), PipeEnd::Sender)?;
+        Sender::from_file_unchecked(file)
+    }
+
+    fn open(&self, path: &Path, pipe_end: PipeEnd) -> io::Result<File> {
+        let mut options = std::fs::OpenOptions::new();
+        options
+            .read(pipe_end == PipeEnd::Receiver)
+            .write(pipe_end == PipeEnd::Sender)
+            .custom_flags(libc::O_NONBLOCK);
+
+        #[cfg(target_os = "linux")]
+        if self.read_write {
+            options.read(true).write(true);
+        }
+
+        let file = options.open(path)?;
+
+        if !self.unchecked && !is_fifo(&file)? {
+            return Err(io::Error::new(io::ErrorKind::InvalidInput, "not a pipe"));
+        }
+
+        Ok(file)
+    }
+}
+
+impl Default for OpenOptions {
+    fn default() -> OpenOptions {
+        OpenOptions::new()
+    }
+}
+
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
+enum PipeEnd {
+    Sender,
+    Receiver,
+}
+
+/// Writing end of a Unix pipe.
+///
+/// It can be constructed from a FIFO file with [`OpenOptions::open_sender`].
+///
+/// Opening a named pipe for writing involves a few steps.
+/// Call to [`OpenOptions::open_sender`] might fail with an error indicating
+/// different things:
+///
+/// * [`io::ErrorKind::NotFound`] - There is no file at the specified path.
+/// * [`io::ErrorKind::InvalidInput`] - The file exists, but it is not a FIFO.
+/// * [`ENXIO`] - The file is a FIFO, but no process has it open for reading.
+///   Sleep for a while and try again.
+/// * Other OS errors not specific to opening FIFO files.
+///
+/// Opening a `Sender` from a FIFO file should look like this:
+///
+/// ```no_run
+/// use tokio::net::unix::pipe;
+/// use tokio::time::{self, Duration};
+///
+/// const FIFO_NAME: &str = "path/to/a/fifo";
+///
+/// # async fn dox() -> Result<(), Box<dyn std::error::Error>> {
+/// // Wait for a reader to open the file.
+/// let tx = loop {
+///     match pipe::OpenOptions::new().open_sender(FIFO_NAME) {
+///         Ok(tx) => break tx,
+///         Err(e) if e.raw_os_error() == Some(libc::ENXIO) => {},
+///         Err(e) => return Err(e.into()),
+///     }
+///
+///     time::sleep(Duration::from_millis(50)).await;
+/// };
+/// # Ok(())
+/// # }
+/// ```
+///
+/// On Linux, it is possible to create a `Sender` without waiting in a sleeping
+/// loop. This is done by opening a named pipe in read-write access mode with
+/// `OpenOptions::read_write`. This way, a `Sender` can at the same time hold
+/// both a writing end and a reading end, and the latter allows to open a FIFO
+/// without [`ENXIO`] error since the pipe is open for reading as well.
+///
+/// `Sender` cannot be used to read from a pipe, so in practice the read access
+/// is only used when a FIFO is opened. However, using a `Sender` in read-write
+/// mode **may lead to lost data**, because written data will be dropped by the
+/// system as soon as all pipe ends are closed. To avoid lost data you have to
+/// make sure that a reading end has been opened before dropping a `Sender`.
+///
+/// Note that using read-write access mode with FIFO files is not defined by
+/// the POSIX standard and it is only guaranteed to work on Linux.
+///
+/// ```ignore
+/// use tokio::io::AsyncWriteExt;
+/// use tokio::net::unix::pipe;
+///
+/// const FIFO_NAME: &str = "path/to/a/fifo";
+///
+/// # async fn dox() -> Result<(), Box<dyn std::error::Error>> {
+/// let mut tx = pipe::OpenOptions::new()
+///     .read_write(true)
+///     .open_sender(FIFO_NAME)?;
+///
+/// // Asynchronously write to the pipe before a reader.
+/// tx.write_all(b"hello world").await?;
+/// # Ok(())
+/// # }
+/// ```
+///
+/// [`ENXIO`]: https://docs.rs/libc/latest/libc/constant.ENXIO.html
+#[derive(Debug)]
+pub struct Sender {
+    io: PollEvented<mio_pipe::Sender>,
+}
+
+impl Sender {
+    fn from_mio(mio_tx: mio_pipe::Sender) -> io::Result<Sender> {
+        let io = PollEvented::new_with_interest(mio_tx, Interest::WRITABLE)?;
+        Ok(Sender { io })
+    }
+
+    /// Creates a new `Sender` from a [`File`].
+    ///
+    /// This function is intended to construct a pipe from a [`File`] representing
+    /// a special FIFO file. It will check if the file is a pipe and has write access,
+    /// set it in non-blocking mode and perform the conversion.
+    ///
+    /// # Errors
+    ///
+    /// Fails with `io::ErrorKind::InvalidInput` if the file is not a pipe or it
+    /// does not have write access. Also fails with any standard OS error if it occurs.
+    ///
+    /// # Panics
+    ///
+    /// This function panics if it is not called from within a runtime with
+    /// IO enabled.
+    ///
+    /// The runtime is usually set implicitly when this function is called
+    /// from a future driven by a tokio runtime, otherwise runtime can be set
+    /// explicitly with [`Runtime::enter`](crate::runtime::Runtime::enter) function.
+    pub fn from_file(mut file: File) -> io::Result<Sender> {
+        if !is_fifo(&file)? {
+            return Err(io::Error::new(io::ErrorKind::InvalidInput, "not a pipe"));
+        }
+
+        let flags = get_file_flags(&file)?;
+        if has_write_access(flags) {
+            set_nonblocking(&mut file, flags)?;
+            Sender::from_file_unchecked(file)
+        } else {
+            Err(io::Error::new(
+                io::ErrorKind::InvalidInput,
+                "not in O_WRONLY or O_RDWR access mode",
+            ))
+        }
+    }
+
+    /// Creates a new `Sender` from a [`File`] without checking pipe properties.
+    ///
+    /// This function is intended to construct a pipe from a File representing
+    /// a special FIFO file. The conversion assumes nothing about the underlying
+    /// file; it is left up to the user to make sure it is opened with write access,
+    /// represents a pipe and is set in non-blocking mode.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::unix::pipe;
+    /// use std::fs::OpenOptions;
+    /// use std::os::unix::fs::{FileTypeExt, OpenOptionsExt};
+    /// # use std::error::Error;
+    ///
+    /// const FIFO_NAME: &str = "path/to/a/fifo";
+    ///
+    /// # async fn dox() -> Result<(), Box<dyn Error>> {
+    /// let file = OpenOptions::new()
+    ///     .write(true)
+    ///     .custom_flags(libc::O_NONBLOCK)
+    ///     .open(FIFO_NAME)?;
+    /// if file.metadata()?.file_type().is_fifo() {
+    ///     let tx = pipe::Sender::from_file_unchecked(file)?;
+    ///     /* use the Sender */
+    /// }
+    /// # Ok(())
+    /// # }
+    /// ```
+    ///
+    /// # Panics
+    ///
+    /// This function panics if it is not called from within a runtime with
+    /// IO enabled.
+    ///
+    /// The runtime is usually set implicitly when this function is called
+    /// from a future driven by a tokio runtime, otherwise runtime can be set
+    /// explicitly with [`Runtime::enter`](crate::runtime::Runtime::enter) function.
+    pub fn from_file_unchecked(file: File) -> io::Result<Sender> {
+        let raw_fd = file.into_raw_fd();
+        let mio_tx = unsafe { mio_pipe::Sender::from_raw_fd(raw_fd) };
+        Sender::from_mio(mio_tx)
+    }
+
+    /// Waits for any of the requested ready states.
+    ///
+    /// This function can be used instead of [`writable()`] to check the returned
+    /// ready set for [`Ready::WRITABLE`] and [`Ready::WRITE_CLOSED`] events.
+    ///
+    /// The function may complete without the pipe being ready. This is a
+    /// false-positive and attempting an operation will return with
+    /// `io::ErrorKind::WouldBlock`. The function can also return with an empty
+    /// [`Ready`] set, so you should always check the returned value and possibly
+    /// wait again if the requested states are not set.
+    ///
+    /// [`writable()`]: Self::writable
+    ///
+    /// # Cancel safety
+    ///
+    /// This method is cancel safe. Once a readiness event occurs, the method
+    /// will continue to return immediately until the readiness event is
+    /// consumed by an attempt to write that fails with `WouldBlock` or
+    /// `Poll::Pending`.
+    pub async fn ready(&self, interest: Interest) -> io::Result<Ready> {
+        let event = self.io.registration().readiness(interest).await?;
+        Ok(event.ready)
+    }
+
+    /// Waits for the pipe to become writable.
+    ///
+    /// This function is equivalent to `ready(Interest::WRITABLE)` and is usually
+    /// paired with [`try_write()`].
+    ///
+    /// [`try_write()`]: Self::try_write
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::unix::pipe;
+    /// use std::io;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> io::Result<()> {
+    ///     // Open a writing end of a fifo
+    ///     let tx = pipe::OpenOptions::new().open_sender("path/to/a/fifo")?;
+    ///
+    ///     loop {
+    ///         // Wait for the pipe to be writable
+    ///         tx.writable().await?;
+    ///
+    ///         // Try to write data, this may still fail with `WouldBlock`
+    ///         // if the readiness event is a false positive.
+    ///         match tx.try_write(b"hello world") {
+    ///             Ok(n) => {
+    ///                 break;
+    ///             }
+    ///             Err(e) if e.kind() == io::ErrorKind::WouldBlock => {
+    ///                 continue;
+    ///             }
+    ///             Err(e) => {
+    ///                 return Err(e.into());
+    ///             }
+    ///         }
+    ///     }
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    pub async fn writable(&self) -> io::Result<()> {
+        self.ready(Interest::WRITABLE).await?;
+        Ok(())
+    }
+
+    /// Polls for write readiness.
+    ///
+    /// If the pipe is not currently ready for writing, this method will
+    /// store a clone of the `Waker` from the provided `Context`. When the pipe
+    /// becomes ready for writing, `Waker::wake` will be called on the waker.
+    ///
+    /// Note that on multiple calls to `poll_write_ready` or `poll_write`, only
+    /// the `Waker` from the `Context` passed to the most recent call is
+    /// scheduled to receive a wakeup.
+    ///
+    /// This function is intended for cases where creating and pinning a future
+    /// via [`writable`] is not feasible. Where possible, using [`writable`] is
+    /// preferred, as this supports polling from multiple tasks at once.
+    ///
+    /// [`writable`]: Self::writable
+    ///
+    /// # Return value
+    ///
+    /// The function returns:
+    ///
+    /// * `Poll::Pending` if the pipe is not ready for writing.
+    /// * `Poll::Ready(Ok(()))` if the pipe is ready for writing.
+    /// * `Poll::Ready(Err(e))` if an error is encountered.
+    ///
+    /// # Errors
+    ///
+    /// This function may encounter any standard I/O error except `WouldBlock`.
+    pub fn poll_write_ready(&self, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+        self.io.registration().poll_write_ready(cx).map_ok(|_| ())
+    }
+
+    /// Tries to write a buffer to the pipe, returning how many bytes were
+    /// written.
+    ///
+    /// The function will attempt to write the entire contents of `buf`, but
+    /// only part of the buffer may be written. If the length of `buf` is not
+    /// greater than `PIPE_BUF` (an OS constant, 4096 under Linux), then the
+    /// write is guaranteed to be atomic, i.e. either the entire content of
+    /// `buf` will be written or this method will fail with `WouldBlock`. There
+    /// is no such guarantee if `buf` is larger than `PIPE_BUF`.
+    ///
+    /// This function is usually paired with [`writable`].
+    ///
+    /// [`writable`]: Self::writable
+    ///
+    /// # Return
+    ///
+    /// If data is successfully written, `Ok(n)` is returned, where `n` is the
+    /// number of bytes written. If the pipe is not ready to write data,
+    /// `Err(io::ErrorKind::WouldBlock)` is returned.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::unix::pipe;
+    /// use std::io;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> io::Result<()> {
+    ///     // Open a writing end of a fifo
+    ///     let tx = pipe::OpenOptions::new().open_sender("path/to/a/fifo")?;
+    ///
+    ///     loop {
+    ///         // Wait for the pipe to be writable
+    ///         tx.writable().await?;
+    ///
+    ///         // Try to write data, this may still fail with `WouldBlock`
+    ///         // if the readiness event is a false positive.
+    ///         match tx.try_write(b"hello world") {
+    ///             Ok(n) => {
+    ///                 break;
+    ///             }
+    ///             Err(e) if e.kind() == io::ErrorKind::WouldBlock => {
+    ///                 continue;
+    ///             }
+    ///             Err(e) => {
+    ///                 return Err(e.into());
+    ///             }
+    ///         }
+    ///     }
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    pub fn try_write(&self, buf: &[u8]) -> io::Result<usize> {
+        self.io
+            .registration()
+            .try_io(Interest::WRITABLE, || (&*self.io).write(buf))
+    }
+
+    /// Tries to write several buffers to the pipe, returning how many bytes
+    /// were written.
+    ///
+    /// Data is written from each buffer in order, with the final buffer read
+    /// from possible being only partially consumed. This method behaves
+    /// equivalently to a single call to [`try_write()`] with concatenated
+    /// buffers.
+    ///
+    /// If the total length of buffers is not greater than `PIPE_BUF` (an OS
+    /// constant, 4096 under Linux), then the write is guaranteed to be atomic,
+    /// i.e. either the entire contents of buffers will be written or this
+    /// method will fail with `WouldBlock`. There is no such guarantee if the
+    /// total length of buffers is greater than `PIPE_BUF`.
+    ///
+    /// This function is usually paired with [`writable`].
+    ///
+    /// [`try_write()`]: Self::try_write()
+    /// [`writable`]: Self::writable
+    ///
+    /// # Return
+    ///
+    /// If data is successfully written, `Ok(n)` is returned, where `n` is the
+    /// number of bytes written. If the pipe is not ready to write data,
+    /// `Err(io::ErrorKind::WouldBlock)` is returned.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::unix::pipe;
+    /// use std::io;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> io::Result<()> {
+    ///     // Open a writing end of a fifo
+    ///     let tx = pipe::OpenOptions::new().open_sender("path/to/a/fifo")?;
+    ///
+    ///     let bufs = [io::IoSlice::new(b"hello "), io::IoSlice::new(b"world")];
+    ///
+    ///     loop {
+    ///         // Wait for the pipe to be writable
+    ///         tx.writable().await?;
+    ///
+    ///         // Try to write data, this may still fail with `WouldBlock`
+    ///         // if the readiness event is a false positive.
+    ///         match tx.try_write_vectored(&bufs) {
+    ///             Ok(n) => {
+    ///                 break;
+    ///             }
+    ///             Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
+    ///                 continue;
+    ///             }
+    ///             Err(e) => {
+    ///                 return Err(e.into());
+    ///             }
+    ///         }
+    ///     }
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    pub fn try_write_vectored(&self, buf: &[io::IoSlice<'_>]) -> io::Result<usize> {
+        self.io
+            .registration()
+            .try_io(Interest::WRITABLE, || (&*self.io).write_vectored(buf))
+    }
+}
+
+impl AsyncWrite for Sender {
+    fn poll_write(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &[u8],
+    ) -> Poll<io::Result<usize>> {
+        self.io.poll_write(cx, buf)
+    }
+
+    fn poll_write_vectored(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        bufs: &[io::IoSlice<'_>],
+    ) -> Poll<io::Result<usize>> {
+        self.io.poll_write_vectored(cx, bufs)
+    }
+
+    fn is_write_vectored(&self) -> bool {
+        true
+    }
+
+    fn poll_flush(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<io::Result<()>> {
+        Poll::Ready(Ok(()))
+    }
+
+    fn poll_shutdown(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<io::Result<()>> {
+        Poll::Ready(Ok(()))
+    }
+}
+
+impl AsRawFd for Sender {
+    fn as_raw_fd(&self) -> RawFd {
+        self.io.as_raw_fd()
+    }
+}
+
+#[cfg(not(tokio_no_as_fd))]
+impl AsFd for Sender {
+    fn as_fd(&self) -> BorrowedFd<'_> {
+        unsafe { BorrowedFd::borrow_raw(self.as_raw_fd()) }
+    }
+}
+
+/// Reading end of a Unix pipe.
+///
+/// It can be constructed from a FIFO file with [`OpenOptions::open_receiver`].
+///
+/// # Examples
+///
+/// Receiving messages from a named pipe in a loop:
+///
+/// ```no_run
+/// use tokio::net::unix::pipe;
+/// use tokio::io::{self, AsyncReadExt};
+///
+/// const FIFO_NAME: &str = "path/to/a/fifo";
+///
+/// # async fn dox() -> Result<(), Box<dyn std::error::Error>> {
+/// let mut rx = pipe::OpenOptions::new().open_receiver(FIFO_NAME)?;
+/// loop {
+///     let mut msg = vec![0; 256];
+///     match rx.read_exact(&mut msg).await {
+///         Ok(_) => {
+///             /* handle the message */
+///         }
+///         Err(e) if e.kind() == io::ErrorKind::UnexpectedEof => {
+///             // Writing end has been closed, we should reopen the pipe.
+///             rx = pipe::OpenOptions::new().open_receiver(FIFO_NAME)?;
+///         }
+///         Err(e) => return Err(e.into()),
+///     }
+/// }
+/// # }
+/// ```
+///
+/// On Linux, you can use a `Receiver` in read-write access mode to implement
+/// resilient reading from a named pipe. Unlike `Receiver` opened in read-only
+/// mode, read from a pipe in read-write mode will not fail with `UnexpectedEof`
+/// when the writing end is closed. This way, a `Receiver` can asynchronously
+/// wait for the next writer to open the pipe.
+///
+/// You should not use functions waiting for EOF such as [`read_to_end`] with
+/// a `Receiver` in read-write access mode, since it **may wait forever**.
+/// `Receiver` in this mode also holds an open writing end, which prevents
+/// receiving EOF.
+///
+/// To set the read-write access mode you can use `OpenOptions::read_write`.
+/// Note that using read-write access mode with FIFO files is not defined by
+/// the POSIX standard and it is only guaranteed to work on Linux.
+///
+/// ```ignore
+/// use tokio::net::unix::pipe;
+/// use tokio::io::AsyncReadExt;
+/// # use std::error::Error;
+///
+/// const FIFO_NAME: &str = "path/to/a/fifo";
+///
+/// # async fn dox() -> Result<(), Box<dyn Error>> {
+/// let mut rx = pipe::OpenOptions::new()
+///     .read_write(true)
+///     .open_receiver(FIFO_NAME)?;
+/// loop {
+///     let mut msg = vec![0; 256];
+///     rx.read_exact(&mut msg).await?;
+///     /* handle the message */
+/// }
+/// # }
+/// ```
+///
+/// [`read_to_end`]: crate::io::AsyncReadExt::read_to_end
+#[derive(Debug)]
+pub struct Receiver {
+    io: PollEvented<mio_pipe::Receiver>,
+}
+
+impl Receiver {
+    fn from_mio(mio_rx: mio_pipe::Receiver) -> io::Result<Receiver> {
+        let io = PollEvented::new_with_interest(mio_rx, Interest::READABLE)?;
+        Ok(Receiver { io })
+    }
+
+    /// Creates a new `Receiver` from a [`File`].
+    ///
+    /// This function is intended to construct a pipe from a [`File`] representing
+    /// a special FIFO file. It will check if the file is a pipe and has read access,
+    /// set it in non-blocking mode and perform the conversion.
+    ///
+    /// # Errors
+    ///
+    /// Fails with `io::ErrorKind::InvalidInput` if the file is not a pipe or it
+    /// does not have read access. Also fails with any standard OS error if it occurs.
+    ///
+    /// # Panics
+    ///
+    /// This function panics if it is not called from within a runtime with
+    /// IO enabled.
+    ///
+    /// The runtime is usually set implicitly when this function is called
+    /// from a future driven by a tokio runtime, otherwise runtime can be set
+    /// explicitly with [`Runtime::enter`](crate::runtime::Runtime::enter) function.
+    pub fn from_file(mut file: File) -> io::Result<Receiver> {
+        if !is_fifo(&file)? {
+            return Err(io::Error::new(io::ErrorKind::InvalidInput, "not a pipe"));
+        }
+
+        let flags = get_file_flags(&file)?;
+        if has_read_access(flags) {
+            set_nonblocking(&mut file, flags)?;
+            Receiver::from_file_unchecked(file)
+        } else {
+            Err(io::Error::new(
+                io::ErrorKind::InvalidInput,
+                "not in O_RDONLY or O_RDWR access mode",
+            ))
+        }
+    }
+
+    /// Creates a new `Receiver` from a [`File`] without checking pipe properties.
+    ///
+    /// This function is intended to construct a pipe from a File representing
+    /// a special FIFO file. The conversion assumes nothing about the underlying
+    /// file; it is left up to the user to make sure it is opened with read access,
+    /// represents a pipe and is set in non-blocking mode.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::unix::pipe;
+    /// use std::fs::OpenOptions;
+    /// use std::os::unix::fs::{FileTypeExt, OpenOptionsExt};
+    /// # use std::error::Error;
+    ///
+    /// const FIFO_NAME: &str = "path/to/a/fifo";
+    ///
+    /// # async fn dox() -> Result<(), Box<dyn Error>> {
+    /// let file = OpenOptions::new()
+    ///     .read(true)
+    ///     .custom_flags(libc::O_NONBLOCK)
+    ///     .open(FIFO_NAME)?;
+    /// if file.metadata()?.file_type().is_fifo() {
+    ///     let rx = pipe::Receiver::from_file_unchecked(file)?;
+    ///     /* use the Receiver */
+    /// }
+    /// # Ok(())
+    /// # }
+    /// ```
+    ///
+    /// # Panics
+    ///
+    /// This function panics if it is not called from within a runtime with
+    /// IO enabled.
+    ///
+    /// The runtime is usually set implicitly when this function is called
+    /// from a future driven by a tokio runtime, otherwise runtime can be set
+    /// explicitly with [`Runtime::enter`](crate::runtime::Runtime::enter) function.
+    pub fn from_file_unchecked(file: File) -> io::Result<Receiver> {
+        let raw_fd = file.into_raw_fd();
+        let mio_rx = unsafe { mio_pipe::Receiver::from_raw_fd(raw_fd) };
+        Receiver::from_mio(mio_rx)
+    }
+
+    /// Waits for any of the requested ready states.
+    ///
+    /// This function can be used instead of [`readable()`] to check the returned
+    /// ready set for [`Ready::READABLE`] and [`Ready::READ_CLOSED`] events.
+    ///
+    /// The function may complete without the pipe being ready. This is a
+    /// false-positive and attempting an operation will return with
+    /// `io::ErrorKind::WouldBlock`. The function can also return with an empty
+    /// [`Ready`] set, so you should always check the returned value and possibly
+    /// wait again if the requested states are not set.
+    ///
+    /// [`readable()`]: Self::readable
+    ///
+    /// # Cancel safety
+    ///
+    /// This method is cancel safe. Once a readiness event occurs, the method
+    /// will continue to return immediately until the readiness event is
+    /// consumed by an attempt to read that fails with `WouldBlock` or
+    /// `Poll::Pending`.
+    pub async fn ready(&self, interest: Interest) -> io::Result<Ready> {
+        let event = self.io.registration().readiness(interest).await?;
+        Ok(event.ready)
+    }
+
+    /// Waits for the pipe to become readable.
+    ///
+    /// This function is equivalent to `ready(Interest::READABLE)` and is usually
+    /// paired with [`try_read()`].
+    ///
+    /// [`try_read()`]: Self::try_read()
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::unix::pipe;
+    /// use std::io;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> io::Result<()> {
+    ///     // Open a reading end of a fifo
+    ///     let rx = pipe::OpenOptions::new().open_receiver("path/to/a/fifo")?;
+    ///
+    ///     let mut msg = vec![0; 1024];
+    ///
+    ///     loop {
+    ///         // Wait for the pipe to be readable
+    ///         rx.readable().await?;
+    ///
+    ///         // Try to read data, this may still fail with `WouldBlock`
+    ///         // if the readiness event is a false positive.
+    ///         match rx.try_read(&mut msg) {
+    ///             Ok(n) => {
+    ///                 msg.truncate(n);
+    ///                 break;
+    ///             }
+    ///             Err(e) if e.kind() == io::ErrorKind::WouldBlock => {
+    ///                 continue;
+    ///             }
+    ///             Err(e) => {
+    ///                 return Err(e.into());
+    ///             }
+    ///         }
+    ///     }
+    ///
+    ///     println!("GOT = {:?}", msg);
+    ///     Ok(())
+    /// }
+    /// ```
+    pub async fn readable(&self) -> io::Result<()> {
+        self.ready(Interest::READABLE).await?;
+        Ok(())
+    }
+
+    /// Polls for read readiness.
+    ///
+    /// If the pipe is not currently ready for reading, this method will
+    /// store a clone of the `Waker` from the provided `Context`. When the pipe
+    /// becomes ready for reading, `Waker::wake` will be called on the waker.
+    ///
+    /// Note that on multiple calls to `poll_read_ready` or `poll_read`, only
+    /// the `Waker` from the `Context` passed to the most recent call is
+    /// scheduled to receive a wakeup.
+    ///
+    /// This function is intended for cases where creating and pinning a future
+    /// via [`readable`] is not feasible. Where possible, using [`readable`] is
+    /// preferred, as this supports polling from multiple tasks at once.
+    ///
+    /// [`readable`]: Self::readable
+    ///
+    /// # Return value
+    ///
+    /// The function returns:
+    ///
+    /// * `Poll::Pending` if the pipe is not ready for reading.
+    /// * `Poll::Ready(Ok(()))` if the pipe is ready for reading.
+    /// * `Poll::Ready(Err(e))` if an error is encountered.
+    ///
+    /// # Errors
+    ///
+    /// This function may encounter any standard I/O error except `WouldBlock`.
+    pub fn poll_read_ready(&self, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+        self.io.registration().poll_read_ready(cx).map_ok(|_| ())
+    }
+
+    /// Tries to read data from the pipe into the provided buffer, returning how
+    /// many bytes were read.
+    ///
+    /// Reads any pending data from the pipe but does not wait for new data
+    /// to arrive. On success, returns the number of bytes read. Because
+    /// `try_read()` is non-blocking, the buffer does not have to be stored by
+    /// the async task and can exist entirely on the stack.
+    ///
+    /// Usually [`readable()`] is used with this function.
+    ///
+    /// [`readable()`]: Self::readable()
+    ///
+    /// # Return
+    ///
+    /// If data is successfully read, `Ok(n)` is returned, where `n` is the
+    /// number of bytes read. If `n` is `0`, then it can indicate one of two scenarios:
+    ///
+    /// 1. The pipe's writing end is closed and will no longer write data.
+    /// 2. The specified buffer was 0 bytes in length.
+    ///
+    /// If the pipe is not ready to read data,
+    /// `Err(io::ErrorKind::WouldBlock)` is returned.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::unix::pipe;
+    /// use std::io;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> io::Result<()> {
+    ///     // Open a reading end of a fifo
+    ///     let rx = pipe::OpenOptions::new().open_receiver("path/to/a/fifo")?;
+    ///
+    ///     let mut msg = vec![0; 1024];
+    ///
+    ///     loop {
+    ///         // Wait for the pipe to be readable
+    ///         rx.readable().await?;
+    ///
+    ///         // Try to read data, this may still fail with `WouldBlock`
+    ///         // if the readiness event is a false positive.
+    ///         match rx.try_read(&mut msg) {
+    ///             Ok(n) => {
+    ///                 msg.truncate(n);
+    ///                 break;
+    ///             }
+    ///             Err(e) if e.kind() == io::ErrorKind::WouldBlock => {
+    ///                 continue;
+    ///             }
+    ///             Err(e) => {
+    ///                 return Err(e.into());
+    ///             }
+    ///         }
+    ///     }
+    ///
+    ///     println!("GOT = {:?}", msg);
+    ///     Ok(())
+    /// }
+    /// ```
+    pub fn try_read(&self, buf: &mut [u8]) -> io::Result<usize> {
+        self.io
+            .registration()
+            .try_io(Interest::READABLE, || (&*self.io).read(buf))
+    }
+
+    /// Tries to read data from the pipe into the provided buffers, returning
+    /// how many bytes were read.
+    ///
+    /// Data is copied to fill each buffer in order, with the final buffer
+    /// written to possibly being only partially filled. This method behaves
+    /// equivalently to a single call to [`try_read()`] with concatenated
+    /// buffers.
+    ///
+    /// Reads any pending data from the pipe but does not wait for new data
+    /// to arrive. On success, returns the number of bytes read. Because
+    /// `try_read_vectored()` is non-blocking, the buffer does not have to be
+    /// stored by the async task and can exist entirely on the stack.
+    ///
+    /// Usually, [`readable()`] is used with this function.
+    ///
+    /// [`try_read()`]: Self::try_read()
+    /// [`readable()`]: Self::readable()
+    ///
+    /// # Return
+    ///
+    /// If data is successfully read, `Ok(n)` is returned, where `n` is the
+    /// number of bytes read. `Ok(0)` indicates the pipe's writing end is
+    /// closed and will no longer write data. If the pipe is not ready to read
+    /// data `Err(io::ErrorKind::WouldBlock)` is returned.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::unix::pipe;
+    /// use std::io;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> io::Result<()> {
+    ///     // Open a reading end of a fifo
+    ///     let rx = pipe::OpenOptions::new().open_receiver("path/to/a/fifo")?;
+    ///
+    ///     loop {
+    ///         // Wait for the pipe to be readable
+    ///         rx.readable().await?;
+    ///
+    ///         // Creating the buffer **after** the `await` prevents it from
+    ///         // being stored in the async task.
+    ///         let mut buf_a = [0; 512];
+    ///         let mut buf_b = [0; 1024];
+    ///         let mut bufs = [
+    ///             io::IoSliceMut::new(&mut buf_a),
+    ///             io::IoSliceMut::new(&mut buf_b),
+    ///         ];
+    ///
+    ///         // Try to read data, this may still fail with `WouldBlock`
+    ///         // if the readiness event is a false positive.
+    ///         match rx.try_read_vectored(&mut bufs) {
+    ///             Ok(0) => break,
+    ///             Ok(n) => {
+    ///                 println!("read {} bytes", n);
+    ///             }
+    ///             Err(e) if e.kind() == io::ErrorKind::WouldBlock => {
+    ///                 continue;
+    ///             }
+    ///             Err(e) => {
+    ///                 return Err(e.into());
+    ///             }
+    ///         }
+    ///     }
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    pub fn try_read_vectored(&self, bufs: &mut [io::IoSliceMut<'_>]) -> io::Result<usize> {
+        self.io
+            .registration()
+            .try_io(Interest::READABLE, || (&*self.io).read_vectored(bufs))
+    }
+
+    cfg_io_util! {
+        /// Tries to read data from the pipe into the provided buffer, advancing the
+        /// buffer's internal cursor, returning how many bytes were read.
+        ///
+        /// Reads any pending data from the pipe but does not wait for new data
+        /// to arrive. On success, returns the number of bytes read. Because
+        /// `try_read_buf()` is non-blocking, the buffer does not have to be stored by
+        /// the async task and can exist entirely on the stack.
+        ///
+        /// Usually, [`readable()`] or [`ready()`] is used with this function.
+        ///
+        /// [`readable()`]: Self::readable
+        /// [`ready()`]: Self::ready
+        ///
+        /// # Return
+        ///
+        /// If data is successfully read, `Ok(n)` is returned, where `n` is the
+        /// number of bytes read. `Ok(0)` indicates the pipe's writing end is
+        /// closed and will no longer write data. If the pipe is not ready to read
+        /// data `Err(io::ErrorKind::WouldBlock)` is returned.
+        ///
+        /// # Examples
+        ///
+        /// ```no_run
+        /// use tokio::net::unix::pipe;
+        /// use std::io;
+        ///
+        /// #[tokio::main]
+        /// async fn main() -> io::Result<()> {
+        ///     // Open a reading end of a fifo
+        ///     let rx = pipe::OpenOptions::new().open_receiver("path/to/a/fifo")?;
+        ///
+        ///     loop {
+        ///         // Wait for the pipe to be readable
+        ///         rx.readable().await?;
+        ///
+        ///         let mut buf = Vec::with_capacity(4096);
+        ///
+        ///         // Try to read data, this may still fail with `WouldBlock`
+        ///         // if the readiness event is a false positive.
+        ///         match rx.try_read_buf(&mut buf) {
+        ///             Ok(0) => break,
+        ///             Ok(n) => {
+        ///                 println!("read {} bytes", n);
+        ///             }
+        ///             Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
+        ///                 continue;
+        ///             }
+        ///             Err(e) => {
+        ///                 return Err(e.into());
+        ///             }
+        ///         }
+        ///     }
+        ///
+        ///     Ok(())
+        /// }
+        /// ```
+        pub fn try_read_buf<B: BufMut>(&self, buf: &mut B) -> io::Result<usize> {
+            self.io.registration().try_io(Interest::READABLE, || {
+                use std::io::Read;
+
+                let dst = buf.chunk_mut();
+                let dst =
+                    unsafe { &mut *(dst as *mut _ as *mut [std::mem::MaybeUninit<u8>] as *mut [u8]) };
+
+                // Safety: `mio_pipe::Receiver` uses a `std::fs::File` underneath,
+                // which correctly handles reads into uninitialized memory.
+                let n = (&*self.io).read(dst)?;
+
+                unsafe {
+                    buf.advance_mut(n);
+                }
+
+                Ok(n)
+            })
+        }
+    }
+}
+
+impl AsyncRead for Receiver {
+    fn poll_read(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &mut ReadBuf<'_>,
+    ) -> Poll<io::Result<()>> {
+        // Safety: `mio_pipe::Receiver` uses a `std::fs::File` underneath,
+        // which correctly handles reads into uninitialized memory.
+        unsafe { self.io.poll_read(cx, buf) }
+    }
+}
+
+impl AsRawFd for Receiver {
+    fn as_raw_fd(&self) -> RawFd {
+        self.io.as_raw_fd()
+    }
+}
+
+#[cfg(not(tokio_no_as_fd))]
+impl AsFd for Receiver {
+    fn as_fd(&self) -> BorrowedFd<'_> {
+        unsafe { BorrowedFd::borrow_raw(self.as_raw_fd()) }
+    }
+}
+
+/// Checks if file is a FIFO
+fn is_fifo(file: &File) -> io::Result<bool> {
+    Ok(file.metadata()?.file_type().is_fifo())
+}
+
+/// Gets file descriptor's flags by fcntl.
+fn get_file_flags(file: &File) -> io::Result<libc::c_int> {
+    let fd = file.as_raw_fd();
+    let flags = unsafe { libc::fcntl(fd, libc::F_GETFL) };
+    if flags < 0 {
+        Err(io::Error::last_os_error())
+    } else {
+        Ok(flags)
+    }
+}
+
+/// Checks for O_RDONLY or O_RDWR access mode.
+fn has_read_access(flags: libc::c_int) -> bool {
+    let mode = flags & libc::O_ACCMODE;
+    mode == libc::O_RDONLY || mode == libc::O_RDWR
+}
+
+/// Checks for O_WRONLY or O_RDWR access mode.
+fn has_write_access(flags: libc::c_int) -> bool {
+    let mode = flags & libc::O_ACCMODE;
+    mode == libc::O_WRONLY || mode == libc::O_RDWR
+}
+
+/// Sets file's flags with O_NONBLOCK by fcntl.
+fn set_nonblocking(file: &mut File, current_flags: libc::c_int) -> io::Result<()> {
+    let fd = file.as_raw_fd();
+
+    let flags = current_flags | libc::O_NONBLOCK;
+
+    if flags != current_flags {
+        let ret = unsafe { libc::fcntl(fd, libc::F_SETFL, flags) };
+        if ret < 0 {
+            return Err(io::Error::last_os_error());
+        }
+    }
+
+    Ok(())
+}
diff --git a/vendor/tokio/src/net/unix/split.rs b/vendor/tokio/src/net/unix/split.rs
index 97214f7a7..6fc7067a7 100644
--- a/vendor/tokio/src/net/unix/split.rs
+++ b/vendor/tokio/src/net/unix/split.rs
@@ -8,14 +8,19 @@
 //! split has no associated overhead and enforces all invariants at the type
 //! level.
 
-use crate::io::{AsyncRead, AsyncWrite, ReadBuf};
+use crate::io::{AsyncRead, AsyncWrite, Interest, ReadBuf, Ready};
 use crate::net::UnixStream;
 
+use crate::net::unix::SocketAddr;
 use std::io;
 use std::net::Shutdown;
 use std::pin::Pin;
 use std::task::{Context, Poll};
 
+cfg_io_util! {
+    use bytes::BufMut;
+}
+
 /// Borrowed read half of a [`UnixStream`], created by [`split`].
 ///
 /// Reading from a `ReadHalf` is usually done using the convenience methods found on the
@@ -47,6 +52,232 @@ pub(crate) fn split(stream: &mut UnixStream) -> (ReadHalf<'_>, WriteHalf<'_>) {
     (ReadHalf(stream), WriteHalf(stream))
 }
 
+impl ReadHalf<'_> {
+    /// Wait for any of the requested ready states.
+    ///
+    /// This function is usually paired with [`try_read()`]. It can be used instead
+    /// of [`readable()`] to check the returned ready set for [`Ready::READABLE`]
+    /// and [`Ready::READ_CLOSED`] events.
+    ///
+    /// The function may complete without the socket being ready. This is a
+    /// false-positive and attempting an operation will return with
+    /// `io::ErrorKind::WouldBlock`. The function can also return with an empty
+    /// [`Ready`] set, so you should always check the returned value and possibly
+    /// wait again if the requested states are not set.
+    ///
+    /// This function is equivalent to [`UnixStream::ready`].
+    ///
+    /// [`try_read()`]: Self::try_read
+    /// [`readable()`]: Self::readable
+    ///
+    /// # Cancel safety
+    ///
+    /// This method is cancel safe. Once a readiness event occurs, the method
+    /// will continue to return immediately until the readiness event is
+    /// consumed by an attempt to read or write that fails with `WouldBlock` or
+    /// `Poll::Pending`.
+    pub async fn ready(&self, interest: Interest) -> io::Result<Ready> {
+        self.0.ready(interest).await
+    }
+
+    /// Waits for the socket to become readable.
+    ///
+    /// This function is equivalent to `ready(Interest::READABLE)` and is usually
+    /// paired with `try_read()`.
+    ///
+    /// # Cancel safety
+    ///
+    /// This method is cancel safe. Once a readiness event occurs, the method
+    /// will continue to return immediately until the readiness event is
+    /// consumed by an attempt to read that fails with `WouldBlock` or
+    /// `Poll::Pending`.
+    pub async fn readable(&self) -> io::Result<()> {
+        self.0.readable().await
+    }
+
+    /// Tries to read data from the stream into the provided buffer, returning how
+    /// many bytes were read.
+    ///
+    /// Receives any pending data from the socket but does not wait for new data
+    /// to arrive. On success, returns the number of bytes read. Because
+    /// `try_read()` is non-blocking, the buffer does not have to be stored by
+    /// the async task and can exist entirely on the stack.
+    ///
+    /// Usually, [`readable()`] or [`ready()`] is used with this function.
+    ///
+    /// [`readable()`]: Self::readable()
+    /// [`ready()`]: Self::ready()
+    ///
+    /// # Return
+    ///
+    /// If data is successfully read, `Ok(n)` is returned, where `n` is the
+    /// number of bytes read. If `n` is `0`, then it can indicate one of two scenarios:
+    ///
+    /// 1. The stream's read half is closed and will no longer yield data.
+    /// 2. The specified buffer was 0 bytes in length.
+    ///
+    /// If the stream is not ready to read data,
+    /// `Err(io::ErrorKind::WouldBlock)` is returned.
+    pub fn try_read(&self, buf: &mut [u8]) -> io::Result<usize> {
+        self.0.try_read(buf)
+    }
+
+    cfg_io_util! {
+        /// Tries to read data from the stream into the provided buffer, advancing the
+        /// buffer's internal cursor, returning how many bytes were read.
+        ///
+        /// Receives any pending data from the socket but does not wait for new data
+        /// to arrive. On success, returns the number of bytes read. Because
+        /// `try_read_buf()` is non-blocking, the buffer does not have to be stored by
+        /// the async task and can exist entirely on the stack.
+        ///
+        /// Usually, [`readable()`] or [`ready()`] is used with this function.
+        ///
+        /// [`readable()`]: Self::readable()
+        /// [`ready()`]: Self::ready()
+        ///
+        /// # Return
+        ///
+        /// If data is successfully read, `Ok(n)` is returned, where `n` is the
+        /// number of bytes read. `Ok(0)` indicates the stream's read half is closed
+        /// and will no longer yield data. If the stream is not ready to read data
+        pub fn try_read_buf<B: BufMut>(&self, buf: &mut B) -> io::Result<usize> {
+            self.0.try_read_buf(buf)
+        }
+    }
+
+    /// Tries to read data from the stream into the provided buffers, returning
+    /// how many bytes were read.
+    ///
+    /// Data is copied to fill each buffer in order, with the final buffer
+    /// written to possibly being only partially filled. This method behaves
+    /// equivalently to a single call to [`try_read()`] with concatenated
+    /// buffers.
+    ///
+    /// Receives any pending data from the socket but does not wait for new data
+    /// to arrive. On success, returns the number of bytes read. Because
+    /// `try_read_vectored()` is non-blocking, the buffer does not have to be
+    /// stored by the async task and can exist entirely on the stack.
+    ///
+    /// Usually, [`readable()`] or [`ready()`] is used with this function.
+    ///
+    /// [`try_read()`]: Self::try_read()
+    /// [`readable()`]: Self::readable()
+    /// [`ready()`]: Self::ready()
+    ///
+    /// # Return
+    ///
+    /// If data is successfully read, `Ok(n)` is returned, where `n` is the
+    /// number of bytes read. `Ok(0)` indicates the stream's read half is closed
+    /// and will no longer yield data. If the stream is not ready to read data
+    /// `Err(io::ErrorKind::WouldBlock)` is returned.
+    pub fn try_read_vectored(&self, bufs: &mut [io::IoSliceMut<'_>]) -> io::Result<usize> {
+        self.0.try_read_vectored(bufs)
+    }
+
+    /// Returns the socket address of the remote half of this connection.
+    pub fn peer_addr(&self) -> io::Result<SocketAddr> {
+        self.0.peer_addr()
+    }
+
+    /// Returns the socket address of the local half of this connection.
+    pub fn local_addr(&self) -> io::Result<SocketAddr> {
+        self.0.local_addr()
+    }
+}
+
+impl WriteHalf<'_> {
+    /// Waits for any of the requested ready states.
+    ///
+    /// This function is usually paired with [`try_write()`]. It can be used instead
+    /// of [`writable()`] to check the returned ready set for [`Ready::WRITABLE`]
+    /// and [`Ready::WRITE_CLOSED`] events.
+    ///
+    /// The function may complete without the socket being ready. This is a
+    /// false-positive and attempting an operation will return with
+    /// `io::ErrorKind::WouldBlock`. The function can also return with an empty
+    /// [`Ready`] set, so you should always check the returned value and possibly
+    /// wait again if the requested states are not set.
+    ///
+    /// This function is equivalent to [`UnixStream::ready`].
+    ///
+    /// [`try_write()`]: Self::try_write
+    /// [`writable()`]: Self::writable
+    ///
+    /// # Cancel safety
+    ///
+    /// This method is cancel safe. Once a readiness event occurs, the method
+    /// will continue to return immediately until the readiness event is
+    /// consumed by an attempt to read or write that fails with `WouldBlock` or
+    /// `Poll::Pending`.
+    pub async fn ready(&self, interest: Interest) -> io::Result<Ready> {
+        self.0.ready(interest).await
+    }
+
+    /// Waits for the socket to become writable.
+    ///
+    /// This function is equivalent to `ready(Interest::WRITABLE)` and is usually
+    /// paired with `try_write()`.
+    ///
+    /// # Cancel safety
+    ///
+    /// This method is cancel safe. Once a readiness event occurs, the method
+    /// will continue to return immediately until the readiness event is
+    /// consumed by an attempt to write that fails with `WouldBlock` or
+    /// `Poll::Pending`.
+    pub async fn writable(&self) -> io::Result<()> {
+        self.0.writable().await
+    }
+
+    /// Tries to write a buffer to the stream, returning how many bytes were
+    /// written.
+    ///
+    /// The function will attempt to write the entire contents of `buf`, but
+    /// only part of the buffer may be written.
+    ///
+    /// This function is usually paired with `writable()`.
+    ///
+    /// # Return
+    ///
+    /// If data is successfully written, `Ok(n)` is returned, where `n` is the
+    /// number of bytes written. If the stream is not ready to write data,
+    /// `Err(io::ErrorKind::WouldBlock)` is returned.
+    pub fn try_write(&self, buf: &[u8]) -> io::Result<usize> {
+        self.0.try_write(buf)
+    }
+
+    /// Tries to write several buffers to the stream, returning how many bytes
+    /// were written.
+    ///
+    /// Data is written from each buffer in order, with the final buffer read
+    /// from possible being only partially consumed. This method behaves
+    /// equivalently to a single call to [`try_write()`] with concatenated
+    /// buffers.
+    ///
+    /// This function is usually paired with `writable()`.
+    ///
+    /// [`try_write()`]: Self::try_write()
+    ///
+    /// # Return
+    ///
+    /// If data is successfully written, `Ok(n)` is returned, where `n` is the
+    /// number of bytes written. If the stream is not ready to write data,
+    /// `Err(io::ErrorKind::WouldBlock)` is returned.
+    pub fn try_write_vectored(&self, buf: &[io::IoSlice<'_>]) -> io::Result<usize> {
+        self.0.try_write_vectored(buf)
+    }
+
+    /// Returns the socket address of the remote half of this connection.
+    pub fn peer_addr(&self) -> io::Result<SocketAddr> {
+        self.0.peer_addr()
+    }
+
+    /// Returns the socket address of the local half of this connection.
+    pub fn local_addr(&self) -> io::Result<SocketAddr> {
+        self.0.local_addr()
+    }
+}
+
 impl AsyncRead for ReadHalf<'_> {
     fn poll_read(
         self: Pin<&mut Self>,
diff --git a/vendor/tokio/src/net/unix/split_owned.rs b/vendor/tokio/src/net/unix/split_owned.rs
index 3d6ac6a7e..d1c6f93de 100644
--- a/vendor/tokio/src/net/unix/split_owned.rs
+++ b/vendor/tokio/src/net/unix/split_owned.rs
@@ -8,9 +8,10 @@
 //! split has no associated overhead and enforces all invariants at the type
 //! level.
 
-use crate::io::{AsyncRead, AsyncWrite, ReadBuf};
+use crate::io::{AsyncRead, AsyncWrite, Interest, ReadBuf, Ready};
 use crate::net::UnixStream;
 
+use crate::net::unix::SocketAddr;
 use std::error::Error;
 use std::net::Shutdown;
 use std::pin::Pin;
@@ -18,6 +19,10 @@ use std::sync::Arc;
 use std::task::{Context, Poll};
 use std::{fmt, io};
 
+cfg_io_util! {
+    use bytes::BufMut;
+}
+
 /// Owned read half of a [`UnixStream`], created by [`into_split`].
 ///
 /// Reading from an `OwnedReadHalf` is usually done using the convenience methods found
@@ -102,6 +107,139 @@ impl OwnedReadHalf {
     pub fn reunite(self, other: OwnedWriteHalf) -> Result<UnixStream, ReuniteError> {
         reunite(self, other)
     }
+
+    /// Waits for any of the requested ready states.
+    ///
+    /// This function is usually paired with [`try_read()`]. It can be used instead
+    /// of [`readable()`] to check the returned ready set for [`Ready::READABLE`]
+    /// and [`Ready::READ_CLOSED`] events.
+    ///
+    /// The function may complete without the socket being ready. This is a
+    /// false-positive and attempting an operation will return with
+    /// `io::ErrorKind::WouldBlock`. The function can also return with an empty
+    /// [`Ready`] set, so you should always check the returned value and possibly
+    /// wait again if the requested states are not set.
+    ///
+    /// This function is equivalent to [`UnixStream::ready`].
+    ///
+    /// [`try_read()`]: Self::try_read
+    /// [`readable()`]: Self::readable
+    ///
+    /// # Cancel safety
+    ///
+    /// This method is cancel safe. Once a readiness event occurs, the method
+    /// will continue to return immediately until the readiness event is
+    /// consumed by an attempt to read or write that fails with `WouldBlock` or
+    /// `Poll::Pending`.
+    pub async fn ready(&self, interest: Interest) -> io::Result<Ready> {
+        self.inner.ready(interest).await
+    }
+
+    /// Waits for the socket to become readable.
+    ///
+    /// This function is equivalent to `ready(Interest::READABLE)` and is usually
+    /// paired with `try_read()`.
+    ///
+    /// # Cancel safety
+    ///
+    /// This method is cancel safe. Once a readiness event occurs, the method
+    /// will continue to return immediately until the readiness event is
+    /// consumed by an attempt to read that fails with `WouldBlock` or
+    /// `Poll::Pending`.
+    pub async fn readable(&self) -> io::Result<()> {
+        self.inner.readable().await
+    }
+
+    /// Tries to read data from the stream into the provided buffer, returning how
+    /// many bytes were read.
+    ///
+    /// Receives any pending data from the socket but does not wait for new data
+    /// to arrive. On success, returns the number of bytes read. Because
+    /// `try_read()` is non-blocking, the buffer does not have to be stored by
+    /// the async task and can exist entirely on the stack.
+    ///
+    /// Usually, [`readable()`] or [`ready()`] is used with this function.
+    ///
+    /// [`readable()`]: Self::readable()
+    /// [`ready()`]: Self::ready()
+    ///
+    /// # Return
+    ///
+    /// If data is successfully read, `Ok(n)` is returned, where `n` is the
+    /// number of bytes read. If `n` is `0`, then it can indicate one of two scenarios:
+    ///
+    /// 1. The stream's read half is closed and will no longer yield data.
+    /// 2. The specified buffer was 0 bytes in length.
+    ///
+    /// If the stream is not ready to read data,
+    /// `Err(io::ErrorKind::WouldBlock)` is returned.
+    pub fn try_read(&self, buf: &mut [u8]) -> io::Result<usize> {
+        self.inner.try_read(buf)
+    }
+
+    cfg_io_util! {
+        /// Tries to read data from the stream into the provided buffer, advancing the
+        /// buffer's internal cursor, returning how many bytes were read.
+        ///
+        /// Receives any pending data from the socket but does not wait for new data
+        /// to arrive. On success, returns the number of bytes read. Because
+        /// `try_read_buf()` is non-blocking, the buffer does not have to be stored by
+        /// the async task and can exist entirely on the stack.
+        ///
+        /// Usually, [`readable()`] or [`ready()`] is used with this function.
+        ///
+        /// [`readable()`]: Self::readable()
+        /// [`ready()`]: Self::ready()
+        ///
+        /// # Return
+        ///
+        /// If data is successfully read, `Ok(n)` is returned, where `n` is the
+        /// number of bytes read. `Ok(0)` indicates the stream's read half is closed
+        /// and will no longer yield data. If the stream is not ready to read data
+        /// `Err(io::ErrorKind::WouldBlock)` is returned.
+        pub fn try_read_buf<B: BufMut>(&self, buf: &mut B) -> io::Result<usize> {
+            self.inner.try_read_buf(buf)
+        }
+    }
+
+    /// Tries to read data from the stream into the provided buffers, returning
+    /// how many bytes were read.
+    ///
+    /// Data is copied to fill each buffer in order, with the final buffer
+    /// written to possibly being only partially filled. This method behaves
+    /// equivalently to a single call to [`try_read()`] with concatenated
+    /// buffers.
+    ///
+    /// Receives any pending data from the socket but does not wait for new data
+    /// to arrive. On success, returns the number of bytes read. Because
+    /// `try_read_vectored()` is non-blocking, the buffer does not have to be
+    /// stored by the async task and can exist entirely on the stack.
+    ///
+    /// Usually, [`readable()`] or [`ready()`] is used with this function.
+    ///
+    /// [`try_read()`]: Self::try_read()
+    /// [`readable()`]: Self::readable()
+    /// [`ready()`]: Self::ready()
+    ///
+    /// # Return
+    ///
+    /// If data is successfully read, `Ok(n)` is returned, where `n` is the
+    /// number of bytes read. `Ok(0)` indicates the stream's read half is closed
+    /// and will no longer yield data. If the stream is not ready to read data
+    /// `Err(io::ErrorKind::WouldBlock)` is returned.
+    pub fn try_read_vectored(&self, bufs: &mut [io::IoSliceMut<'_>]) -> io::Result<usize> {
+        self.inner.try_read_vectored(bufs)
+    }
+
+    /// Returns the socket address of the remote half of this connection.
+    pub fn peer_addr(&self) -> io::Result<SocketAddr> {
+        self.inner.peer_addr()
+    }
+
+    /// Returns the socket address of the local half of this connection.
+    pub fn local_addr(&self) -> io::Result<SocketAddr> {
+        self.inner.local_addr()
+    }
 }
 
 impl AsyncRead for OwnedReadHalf {
@@ -124,13 +262,103 @@ impl OwnedWriteHalf {
         reunite(other, self)
     }
 
-    /// Destroy the write half, but don't close the write half of the stream
+    /// Destroys the write half, but don't close the write half of the stream
     /// until the read half is dropped. If the read half has already been
     /// dropped, this closes the stream.
     pub fn forget(mut self) {
         self.shutdown_on_drop = false;
         drop(self);
     }
+
+    /// Waits for any of the requested ready states.
+    ///
+    /// This function is usually paired with [`try_write()`]. It can be used instead
+    /// of [`writable()`] to check the returned ready set for [`Ready::WRITABLE`]
+    /// and [`Ready::WRITE_CLOSED`] events.
+    ///
+    /// The function may complete without the socket being ready. This is a
+    /// false-positive and attempting an operation will return with
+    /// `io::ErrorKind::WouldBlock`. The function can also return with an empty
+    /// [`Ready`] set, so you should always check the returned value and possibly
+    /// wait again if the requested states are not set.
+    ///
+    /// This function is equivalent to [`UnixStream::ready`].
+    ///
+    /// [`try_write()`]: Self::try_write
+    /// [`writable()`]: Self::writable
+    ///
+    /// # Cancel safety
+    ///
+    /// This method is cancel safe. Once a readiness event occurs, the method
+    /// will continue to return immediately until the readiness event is
+    /// consumed by an attempt to read or write that fails with `WouldBlock` or
+    /// `Poll::Pending`.
+    pub async fn ready(&self, interest: Interest) -> io::Result<Ready> {
+        self.inner.ready(interest).await
+    }
+
+    /// Waits for the socket to become writable.
+    ///
+    /// This function is equivalent to `ready(Interest::WRITABLE)` and is usually
+    /// paired with `try_write()`.
+    ///
+    /// # Cancel safety
+    ///
+    /// This method is cancel safe. Once a readiness event occurs, the method
+    /// will continue to return immediately until the readiness event is
+    /// consumed by an attempt to write that fails with `WouldBlock` or
+    /// `Poll::Pending`.
+    pub async fn writable(&self) -> io::Result<()> {
+        self.inner.writable().await
+    }
+
+    /// Tries to write a buffer to the stream, returning how many bytes were
+    /// written.
+    ///
+    /// The function will attempt to write the entire contents of `buf`, but
+    /// only part of the buffer may be written.
+    ///
+    /// This function is usually paired with `writable()`.
+    ///
+    /// # Return
+    ///
+    /// If data is successfully written, `Ok(n)` is returned, where `n` is the
+    /// number of bytes written. If the stream is not ready to write data,
+    /// `Err(io::ErrorKind::WouldBlock)` is returned.
+    pub fn try_write(&self, buf: &[u8]) -> io::Result<usize> {
+        self.inner.try_write(buf)
+    }
+
+    /// Tries to write several buffers to the stream, returning how many bytes
+    /// were written.
+    ///
+    /// Data is written from each buffer in order, with the final buffer read
+    /// from possible being only partially consumed. This method behaves
+    /// equivalently to a single call to [`try_write()`] with concatenated
+    /// buffers.
+    ///
+    /// This function is usually paired with `writable()`.
+    ///
+    /// [`try_write()`]: Self::try_write()
+    ///
+    /// # Return
+    ///
+    /// If data is successfully written, `Ok(n)` is returned, where `n` is the
+    /// number of bytes written. If the stream is not ready to write data,
+    /// `Err(io::ErrorKind::WouldBlock)` is returned.
+    pub fn try_write_vectored(&self, buf: &[io::IoSlice<'_>]) -> io::Result<usize> {
+        self.inner.try_write_vectored(buf)
+    }
+
+    /// Returns the socket address of the remote half of this connection.
+    pub fn peer_addr(&self) -> io::Result<SocketAddr> {
+        self.inner.peer_addr()
+    }
+
+    /// Returns the socket address of the local half of this connection.
+    pub fn local_addr(&self) -> io::Result<SocketAddr> {
+        self.inner.local_addr()
+    }
 }
 
 impl Drop for OwnedWriteHalf {
@@ -180,12 +408,12 @@ impl AsyncWrite for OwnedWriteHalf {
 
 impl AsRef<UnixStream> for OwnedReadHalf {
     fn as_ref(&self) -> &UnixStream {
-        &*self.inner
+        &self.inner
     }
 }
 
 impl AsRef<UnixStream> for OwnedWriteHalf {
     fn as_ref(&self) -> &UnixStream {
-        &*self.inner
+        &self.inner
     }
 }
diff --git a/vendor/tokio/src/net/unix/stream.rs b/vendor/tokio/src/net/unix/stream.rs
index 4baac6062..201645ba1 100644
--- a/vendor/tokio/src/net/unix/stream.rs
+++ b/vendor/tokio/src/net/unix/stream.rs
@@ -5,10 +5,11 @@ use crate::net::unix::split_owned::{split_owned, OwnedReadHalf, OwnedWriteHalf};
 use crate::net::unix::ucred::{self, UCred};
 use crate::net::unix::SocketAddr;
 
-use std::convert::TryFrom;
 use std::fmt;
 use std::io::{self, Read, Write};
 use std::net::Shutdown;
+#[cfg(not(tokio_no_as_fd))]
+use std::os::unix::io::{AsFd, BorrowedFd};
 use std::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
 use std::os::unix::net;
 use std::path::Path;
@@ -22,8 +23,8 @@ cfg_io_util! {
 cfg_net_unix! {
     /// A structure representing a connected Unix socket.
     ///
-    /// This socket can be connected directly with `UnixStream::connect` or accepted
-    /// from a listener with `UnixListener::incoming`. Additionally, a pair of
+    /// This socket can be connected directly with [`UnixStream::connect`] or accepted
+    /// from a listener with [`UnixListener::accept`]. Additionally, a pair of
     /// anonymous Unix sockets can be created with `UnixStream::pair`.
     ///
     /// To shut down the stream in the write direction, you can call the
@@ -32,6 +33,8 @@ cfg_net_unix! {
     /// the stream in one direction.
     ///
     /// [`shutdown()`]: fn@crate::io::AsyncWriteExt::shutdown
+    /// [`UnixListener::accept`]: crate::net::UnixListener::accept
+    #[cfg_attr(docsrs, doc(alias = "uds"))]
     pub struct UnixStream {
         io: PollEvented<mio::net::UnixStream>,
     }
@@ -59,12 +62,18 @@ impl UnixStream {
         Ok(stream)
     }
 
-    /// Wait for any of the requested ready states.
+    /// Waits for any of the requested ready states.
     ///
     /// This function is usually paired with `try_read()` or `try_write()`. It
     /// can be used to concurrently read / write to the same socket on a single
     /// task without splitting the socket.
     ///
+    /// The function may complete without the socket being ready. This is a
+    /// false-positive and attempting an operation will return with
+    /// `io::ErrorKind::WouldBlock`. The function can also return with an empty
+    /// [`Ready`] set, so you should always check the returned value and possibly
+    /// wait again if the requested states are not set.
+    ///
     /// # Cancel safety
     ///
     /// This method is cancel safe. Once a readiness event occurs, the method
@@ -133,7 +142,7 @@ impl UnixStream {
         Ok(event.ready)
     }
 
-    /// Wait for the socket to become readable.
+    /// Waits for the socket to become readable.
     ///
     /// This function is equivalent to `ready(Interest::READABLE)` and is usually
     /// paired with `try_read()`.
@@ -239,8 +248,12 @@ impl UnixStream {
     /// # Return
     ///
     /// If data is successfully read, `Ok(n)` is returned, where `n` is the
-    /// number of bytes read. `Ok(0)` indicates the stream's read half is closed
-    /// and will no longer yield data. If the stream is not ready to read data
+    /// number of bytes read. If `n` is `0`, then it can indicate one of two scenarios:
+    ///
+    /// 1. The stream's read half is closed and will no longer yield data.
+    /// 2. The specified buffer was 0 bytes in length.
+    ///
+    /// If the stream is not ready to read data,
     /// `Err(io::ErrorKind::WouldBlock)` is returned.
     ///
     /// # Examples
@@ -290,7 +303,7 @@ impl UnixStream {
             .try_io(Interest::READABLE, || (&*self.io).read(buf))
     }
 
-    /// Try to read data from the stream into the provided buffers, returning
+    /// Tries to read data from the stream into the provided buffers, returning
     /// how many bytes were read.
     ///
     /// Data is copied to fill each buffer in order, with the final buffer
@@ -369,7 +382,7 @@ impl UnixStream {
     }
 
     cfg_io_util! {
-        /// Try to read data from the stream into the provided buffer, advancing the
+        /// Tries to read data from the stream into the provided buffer, advancing the
         /// buffer's internal cursor, returning how many bytes were read.
         ///
         /// Receives any pending data from the socket but does not wait for new data
@@ -449,7 +462,7 @@ impl UnixStream {
         }
     }
 
-    /// Wait for the socket to become writable.
+    /// Waits for the socket to become writable.
     ///
     /// This function is equivalent to `ready(Interest::WRITABLE)` and is usually
     /// paired with `try_write()`.
@@ -535,7 +548,7 @@ impl UnixStream {
         self.io.registration().poll_write_ready(cx).map_ok(|_| ())
     }
 
-    /// Try to write a buffer to the stream, returning how many bytes were
+    /// Tries to write a buffer to the stream, returning how many bytes were
     /// written.
     ///
     /// The function will attempt to write the entire contents of `buf`, but
@@ -591,7 +604,7 @@ impl UnixStream {
             .try_io(Interest::WRITABLE, || (&*self.io).write(buf))
     }
 
-    /// Try to write several buffers to the stream, returning how many bytes
+    /// Tries to write several buffers to the stream, returning how many bytes
     /// were written.
     ///
     /// Data is written from each buffer in order, with the final buffer read
@@ -653,20 +666,122 @@ impl UnixStream {
             .try_io(Interest::WRITABLE, || (&*self.io).write_vectored(buf))
     }
 
+    /// Tries to read or write from the socket using a user-provided IO operation.
+    ///
+    /// If the socket is ready, the provided closure is called. The closure
+    /// should attempt to perform IO operation on the socket by manually
+    /// calling the appropriate syscall. If the operation fails because the
+    /// socket is not actually ready, then the closure should return a
+    /// `WouldBlock` error and the readiness flag is cleared. The return value
+    /// of the closure is then returned by `try_io`.
+    ///
+    /// If the socket is not ready, then the closure is not called
+    /// and a `WouldBlock` error is returned.
+    ///
+    /// The closure should only return a `WouldBlock` error if it has performed
+    /// an IO operation on the socket that failed due to the socket not being
+    /// ready. Returning a `WouldBlock` error in any other situation will
+    /// incorrectly clear the readiness flag, which can cause the socket to
+    /// behave incorrectly.
+    ///
+    /// The closure should not perform the IO operation using any of the methods
+    /// defined on the Tokio `UnixStream` type, as this will mess with the
+    /// readiness flag and can cause the socket to behave incorrectly.
+    ///
+    /// This method is not intended to be used with combined interests.
+    /// The closure should perform only one type of IO operation, so it should not
+    /// require more than one ready state. This method may panic or sleep forever
+    /// if it is called with a combined interest.
+    ///
+    /// Usually, [`readable()`], [`writable()`] or [`ready()`] is used with this function.
+    ///
+    /// [`readable()`]: UnixStream::readable()
+    /// [`writable()`]: UnixStream::writable()
+    /// [`ready()`]: UnixStream::ready()
+    pub fn try_io<R>(
+        &self,
+        interest: Interest,
+        f: impl FnOnce() -> io::Result<R>,
+    ) -> io::Result<R> {
+        self.io
+            .registration()
+            .try_io(interest, || self.io.try_io(f))
+    }
+
+    /// Reads or writes from the socket using a user-provided IO operation.
+    ///
+    /// The readiness of the socket is awaited and when the socket is ready,
+    /// the provided closure is called. The closure should attempt to perform
+    /// IO operation on the socket by manually calling the appropriate syscall.
+    /// If the operation fails because the socket is not actually ready,
+    /// then the closure should return a `WouldBlock` error. In such case the
+    /// readiness flag is cleared and the socket readiness is awaited again.
+    /// This loop is repeated until the closure returns an `Ok` or an error
+    /// other than `WouldBlock`.
+    ///
+    /// The closure should only return a `WouldBlock` error if it has performed
+    /// an IO operation on the socket that failed due to the socket not being
+    /// ready. Returning a `WouldBlock` error in any other situation will
+    /// incorrectly clear the readiness flag, which can cause the socket to
+    /// behave incorrectly.
+    ///
+    /// The closure should not perform the IO operation using any of the methods
+    /// defined on the Tokio `UnixStream` type, as this will mess with the
+    /// readiness flag and can cause the socket to behave incorrectly.
+    ///
+    /// This method is not intended to be used with combined interests.
+    /// The closure should perform only one type of IO operation, so it should not
+    /// require more than one ready state. This method may panic or sleep forever
+    /// if it is called with a combined interest.
+    pub async fn async_io<R>(
+        &self,
+        interest: Interest,
+        mut f: impl FnMut() -> io::Result<R>,
+    ) -> io::Result<R> {
+        self.io
+            .registration()
+            .async_io(interest, || self.io.try_io(&mut f))
+            .await
+    }
+
     /// Creates new `UnixStream` from a `std::os::unix::net::UnixStream`.
     ///
     /// This function is intended to be used to wrap a UnixStream from the
-    /// standard library in the Tokio equivalent. The conversion assumes
-    /// nothing about the underlying stream; it is left up to the user to set
-    /// it in non-blocking mode.
+    /// standard library in the Tokio equivalent.
+    ///
+    /// # Notes
+    ///
+    /// The caller is responsible for ensuring that the stream is in
+    /// non-blocking mode. Otherwise all I/O operations on the stream
+    /// will block the thread, which will cause unexpected behavior.
+    /// Non-blocking mode can be set using [`set_nonblocking`].
+    ///
+    /// [`set_nonblocking`]: std::os::unix::net::UnixStream::set_nonblocking
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::UnixStream;
+    /// use std::os::unix::net::UnixStream as StdUnixStream;
+    /// # use std::error::Error;
+    ///
+    /// # async fn dox() -> Result<(), Box<dyn Error>> {
+    /// let std_stream = StdUnixStream::connect("/path/to/the/socket")?;
+    /// std_stream.set_nonblocking(true)?;
+    /// let stream = UnixStream::from_std(std_stream)?;
+    /// # Ok(())
+    /// # }
+    /// ```
     ///
     /// # Panics
     ///
-    /// This function panics if thread-local runtime is not set.
+    /// This function panics if it is not called from within a runtime with
+    /// IO enabled.
     ///
     /// The runtime is usually set implicitly when this function is called
     /// from a future driven by a tokio runtime, otherwise runtime can be set
     /// explicitly with [`Runtime::enter`](crate::runtime::Runtime::enter) function.
+    #[track_caller]
     pub fn from_std(stream: net::UnixStream) -> io::Result<UnixStream> {
         let stream = mio::net::UnixStream::from_std(stream);
         let io = PollEvented::new(stream)?;
@@ -674,7 +789,7 @@ impl UnixStream {
         Ok(UnixStream { io })
     }
 
-    /// Turn a [`tokio::net::UnixStream`] into a [`std::os::unix::net::UnixStream`].
+    /// Turns a [`tokio::net::UnixStream`] into a [`std::os::unix::net::UnixStream`].
     ///
     /// The returned [`std::os::unix::net::UnixStream`] will have nonblocking
     /// mode set as `true`.  Use [`set_nonblocking`] to change the blocking
@@ -738,11 +853,41 @@ impl UnixStream {
     }
 
     /// Returns the socket address of the local half of this connection.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::UnixStream;
+    ///
+    /// # async fn dox() -> Result<(), Box<dyn std::error::Error>> {
+    /// let dir = tempfile::tempdir().unwrap();
+    /// let bind_path = dir.path().join("bind_path");
+    /// let stream = UnixStream::connect(bind_path).await?;
+    ///
+    /// println!("{:?}", stream.local_addr()?);
+    /// # Ok(())
+    /// # }
+    /// ```
     pub fn local_addr(&self) -> io::Result<SocketAddr> {
         self.io.local_addr().map(SocketAddr)
     }
 
     /// Returns the socket address of the remote half of this connection.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::UnixStream;
+    ///
+    /// # async fn dox() -> Result<(), Box<dyn std::error::Error>> {
+    /// let dir = tempfile::tempdir().unwrap();
+    /// let bind_path = dir.path().join("bind_path");
+    /// let stream = UnixStream::connect(bind_path).await?;
+    ///
+    /// println!("{:?}", stream.peer_addr()?);
+    /// # Ok(())
+    /// # }
+    /// ```
     pub fn peer_addr(&self) -> io::Result<SocketAddr> {
         self.io.peer_addr().map(SocketAddr)
     }
@@ -769,7 +914,7 @@ impl UnixStream {
     // These lifetime markers also appear in the generated documentation, and make
     // it more clear that this is a *borrowed* split.
     #[allow(clippy::needless_lifetimes)]
-    /// Split a `UnixStream` into a read half and a write half, which can be used
+    /// Splits a `UnixStream` into a read half and a write half, which can be used
     /// to read and write the stream concurrently.
     ///
     /// This method is more efficient than [`into_split`], but the halves cannot be
@@ -893,3 +1038,10 @@ impl AsRawFd for UnixStream {
         self.io.as_raw_fd()
     }
 }
+
+#[cfg(not(tokio_no_as_fd))]
+impl AsFd for UnixStream {
+    fn as_fd(&self) -> BorrowedFd<'_> {
+        unsafe { BorrowedFd::borrow_raw(self.as_raw_fd()) }
+    }
+}
diff --git a/vendor/tokio/src/net/unix/ucred.rs b/vendor/tokio/src/net/unix/ucred.rs
index 6310183d7..edfab08ab 100644
--- a/vendor/tokio/src/net/unix/ucred.rs
+++ b/vendor/tokio/src/net/unix/ucred.rs
@@ -1,24 +1,24 @@
-use libc::{gid_t, pid_t, uid_t};
+use crate::net::unix;
 
-/// Credentials of a process
+/// Credentials of a process.
 #[derive(Copy, Clone, Eq, PartialEq, Hash, Debug)]
 pub struct UCred {
-    /// PID (process ID) of the process
-    pid: Option<pid_t>,
-    /// UID (user ID) of the process
-    uid: uid_t,
-    /// GID (group ID) of the process
-    gid: gid_t,
+    /// PID (process ID) of the process.
+    pid: Option<unix::pid_t>,
+    /// UID (user ID) of the process.
+    uid: unix::uid_t,
+    /// GID (group ID) of the process.
+    gid: unix::gid_t,
 }
 
 impl UCred {
     /// Gets UID (user ID) of the process.
-    pub fn uid(&self) -> uid_t {
+    pub fn uid(&self) -> unix::uid_t {
         self.uid
     }
 
     /// Gets GID (group ID) of the process.
-    pub fn gid(&self) -> gid_t {
+    pub fn gid(&self) -> unix::gid_t {
         self.gid
     }
 
@@ -26,20 +26,23 @@ impl UCred {
     ///
     /// This is only implemented under Linux, Android, iOS, macOS, Solaris and
     /// Illumos. On other platforms this will always return `None`.
-    pub fn pid(&self) -> Option<pid_t> {
+    pub fn pid(&self) -> Option<unix::pid_t> {
         self.pid
     }
 }
 
-#[cfg(any(target_os = "linux", target_os = "android"))]
-pub(crate) use self::impl_linux::get_peer_cred;
-
 #[cfg(any(
-    target_os = "dragonfly",
-    target_os = "freebsd",
-    target_os = "netbsd",
+    target_os = "linux",
+    target_os = "redox",
+    target_os = "android",
     target_os = "openbsd"
 ))]
+pub(crate) use self::impl_linux::get_peer_cred;
+
+#[cfg(any(target_os = "netbsd"))]
+pub(crate) use self::impl_netbsd::get_peer_cred;
+
+#[cfg(any(target_os = "dragonfly", target_os = "freebsd"))]
 pub(crate) use self::impl_bsd::get_peer_cred;
 
 #[cfg(any(target_os = "macos", target_os = "ios"))]
@@ -48,13 +51,24 @@ pub(crate) use self::impl_macos::get_peer_cred;
 #[cfg(any(target_os = "solaris", target_os = "illumos"))]
 pub(crate) use self::impl_solaris::get_peer_cred;
 
-#[cfg(any(target_os = "linux", target_os = "android"))]
+#[cfg(target_os = "aix")]
+pub(crate) use self::impl_aix::get_peer_cred;
+
+#[cfg(any(
+    target_os = "linux",
+    target_os = "redox",
+    target_os = "android",
+    target_os = "openbsd"
+))]
 pub(crate) mod impl_linux {
-    use crate::net::unix::UnixStream;
+    use crate::net::unix::{self, UnixStream};
 
     use libc::{c_void, getsockopt, socklen_t, SOL_SOCKET, SO_PEERCRED};
     use std::{io, mem};
 
+    #[cfg(target_os = "openbsd")]
+    use libc::sockpeercred as ucred;
+    #[cfg(any(target_os = "linux", target_os = "redox", target_os = "android"))]
     use libc::ucred;
 
     pub(crate) fn get_peer_cred(sock: &UnixStream) -> io::Result<super::UCred> {
@@ -86,9 +100,9 @@ pub(crate) mod impl_linux {
             );
             if ret == 0 && ucred_size as usize == mem::size_of::<ucred>() {
                 Ok(super::UCred {
-                    uid: ucred.uid,
-                    gid: ucred.gid,
-                    pid: Some(ucred.pid),
+                    uid: ucred.uid as unix::uid_t,
+                    gid: ucred.gid as unix::gid_t,
+                    pid: Some(ucred.pid as unix::pid_t),
                 })
             } else {
                 Err(io::Error::last_os_error())
@@ -97,14 +111,51 @@ pub(crate) mod impl_linux {
     }
 }
 
-#[cfg(any(
-    target_os = "dragonfly",
-    target_os = "freebsd",
-    target_os = "netbsd",
-    target_os = "openbsd"
-))]
+#[cfg(any(target_os = "netbsd"))]
+pub(crate) mod impl_netbsd {
+    use crate::net::unix::{self, UnixStream};
+
+    use libc::{c_void, getsockopt, socklen_t, unpcbid, LOCAL_PEEREID, SOL_SOCKET};
+    use std::io;
+    use std::mem::size_of;
+    use std::os::unix::io::AsRawFd;
+
+    pub(crate) fn get_peer_cred(sock: &UnixStream) -> io::Result<super::UCred> {
+        unsafe {
+            let raw_fd = sock.as_raw_fd();
+
+            let mut unpcbid = unpcbid {
+                unp_pid: 0,
+                unp_euid: 0,
+                unp_egid: 0,
+            };
+
+            let unpcbid_size = size_of::<unpcbid>();
+            let mut unpcbid_size = unpcbid_size as socklen_t;
+
+            let ret = getsockopt(
+                raw_fd,
+                SOL_SOCKET,
+                LOCAL_PEEREID,
+                &mut unpcbid as *mut unpcbid as *mut c_void,
+                &mut unpcbid_size,
+            );
+            if ret == 0 && unpcbid_size as usize == size_of::<unpcbid>() {
+                Ok(super::UCred {
+                    uid: unpcbid.unp_euid as unix::uid_t,
+                    gid: unpcbid.unp_egid as unix::gid_t,
+                    pid: Some(unpcbid.unp_pid as unix::pid_t),
+                })
+            } else {
+                Err(io::Error::last_os_error())
+            }
+        }
+    }
+}
+
+#[cfg(any(target_os = "dragonfly", target_os = "freebsd"))]
 pub(crate) mod impl_bsd {
-    use crate::net::unix::UnixStream;
+    use crate::net::unix::{self, UnixStream};
 
     use libc::getpeereid;
     use std::io;
@@ -122,8 +173,8 @@ pub(crate) mod impl_bsd {
 
             if ret == 0 {
                 Ok(super::UCred {
-                    uid: uid.assume_init(),
-                    gid: gid.assume_init(),
+                    uid: uid.assume_init() as unix::uid_t,
+                    gid: gid.assume_init() as unix::gid_t,
                     pid: None,
                 })
             } else {
@@ -135,7 +186,7 @@ pub(crate) mod impl_bsd {
 
 #[cfg(any(target_os = "macos", target_os = "ios"))]
 pub(crate) mod impl_macos {
-    use crate::net::unix::UnixStream;
+    use crate::net::unix::{self, UnixStream};
 
     use libc::{c_void, getpeereid, getsockopt, pid_t, LOCAL_PEEREPID, SOL_LOCAL};
     use std::io;
@@ -169,9 +220,9 @@ pub(crate) mod impl_macos {
 
             if ret == 0 {
                 Ok(super::UCred {
-                    uid: uid.assume_init(),
-                    gid: gid.assume_init(),
-                    pid: Some(pid.assume_init()),
+                    uid: uid.assume_init() as unix::uid_t,
+                    gid: gid.assume_init() as unix::gid_t,
+                    pid: Some(pid.assume_init() as unix::pid_t),
                 })
             } else {
                 Err(io::Error::last_os_error())
@@ -182,7 +233,7 @@ pub(crate) mod impl_macos {
 
 #[cfg(any(target_os = "solaris", target_os = "illumos"))]
 pub(crate) mod impl_solaris {
-    use crate::net::unix::UnixStream;
+    use crate::net::unix::{self, UnixStream};
     use std::io;
     use std::os::unix::io::AsRawFd;
     use std::ptr;
@@ -202,9 +253,37 @@ pub(crate) mod impl_solaris {
                 libc::ucred_free(cred);
 
                 Ok(super::UCred {
-                    uid,
-                    gid,
-                    pid: Some(pid),
+                    uid: uid as unix::uid_t,
+                    gid: gid as unix::gid_t,
+                    pid: Some(pid as unix::pid_t),
+                })
+            } else {
+                Err(io::Error::last_os_error())
+            }
+        }
+    }
+}
+
+#[cfg(target_os = "aix")]
+pub(crate) mod impl_aix {
+    use crate::net::unix::UnixStream;
+    use std::io;
+    use std::os::unix::io::AsRawFd;
+
+    pub(crate) fn get_peer_cred(sock: &UnixStream) -> io::Result<super::UCred> {
+        unsafe {
+            let raw_fd = sock.as_raw_fd();
+
+            let mut uid = std::mem::MaybeUninit::uninit();
+            let mut gid = std::mem::MaybeUninit::uninit();
+
+            let ret = libc::getpeereid(raw_fd, uid.as_mut_ptr(), gid.as_mut_ptr());
+
+            if ret == 0 {
+                Ok(super::UCred {
+                    uid: uid.assume_init(),
+                    gid: gid.assume_init(),
+                    pid: None,
                 })
             } else {
                 Err(io::Error::last_os_error())
diff --git a/vendor/tokio/src/net/windows/named_pipe.rs b/vendor/tokio/src/net/windows/named_pipe.rs
index b9f7d49d7..91f016267 100644
--- a/vendor/tokio/src/net/windows/named_pipe.rs
+++ b/vendor/tokio/src/net/windows/named_pipe.rs
@@ -10,27 +10,30 @@ use std::ptr;
 use std::task::{Context, Poll};
 
 use crate::io::{AsyncRead, AsyncWrite, Interest, PollEvented, ReadBuf, Ready};
+#[cfg(not(tokio_no_as_fd))]
+use crate::os::windows::io::{AsHandle, BorrowedHandle};
 use crate::os::windows::io::{AsRawHandle, FromRawHandle, RawHandle};
 
+cfg_io_util! {
+    use bytes::BufMut;
+}
+
 // Hide imports which are not used when generating documentation.
 #[cfg(not(docsrs))]
 mod doc {
     pub(super) use crate::os::windows::ffi::OsStrExt;
-    pub(super) use crate::winapi::shared::minwindef::{DWORD, FALSE};
-    pub(super) use crate::winapi::um::fileapi;
-    pub(super) use crate::winapi::um::handleapi;
-    pub(super) use crate::winapi::um::namedpipeapi;
-    pub(super) use crate::winapi::um::winbase;
-    pub(super) use crate::winapi::um::winnt;
-
+    pub(super) mod windows_sys {
+        pub(crate) use windows_sys::{
+            Win32::Foundation::*, Win32::Storage::FileSystem::*, Win32::System::Pipes::*,
+            Win32::System::SystemServices::*,
+        };
+    }
     pub(super) use mio::windows as mio_windows;
 }
 
 // NB: none of these shows up in public API, so don't document them.
 #[cfg(docsrs)]
 mod doc {
-    pub type DWORD = crate::doc::NotDefinedHere;
-
     pub(super) mod mio_windows {
         pub type NamedPipe = crate::doc::NotDefinedHere;
     }
@@ -97,7 +100,6 @@ use self::doc::*;
 /// # Ok(()) }
 /// ```
 ///
-/// [`ERROR_PIPE_BUSY`]: crate::winapi::shared::winerror::ERROR_PIPE_BUSY
 /// [Windows named pipe]: https://docs.microsoft.com/en-us/windows/win32/ipc/named-pipes
 #[derive(Debug)]
 pub struct NamedPipeServer {
@@ -105,7 +107,7 @@ pub struct NamedPipeServer {
 }
 
 impl NamedPipeServer {
-    /// Construct a new named pipe server from the specified raw handle.
+    /// Constructs a new named pipe server from the specified raw handle.
     ///
     /// This function will consume ownership of the handle given, passing
     /// responsibility for closing the handle to the returned object.
@@ -188,17 +190,15 @@ impl NamedPipeServer {
     /// # Ok(()) }
     /// ```
     pub async fn connect(&self) -> io::Result<()> {
-        loop {
-            match self.io.connect() {
-                Ok(()) => break,
-                Err(e) if e.kind() == io::ErrorKind::WouldBlock => {
-                    self.io.registration().readiness(Interest::WRITABLE).await?;
-                }
-                Err(e) => return Err(e),
+        match self.io.connect() {
+            Err(e) if e.kind() == io::ErrorKind::WouldBlock => {
+                self.io
+                    .registration()
+                    .async_io(Interest::WRITABLE, || self.io.connect())
+                    .await
             }
+            x => x,
         }
-
-        Ok(())
     }
 
     /// Disconnects the server end of a named pipe instance from a client
@@ -207,7 +207,7 @@ impl NamedPipeServer {
     /// ```
     /// use tokio::io::AsyncWriteExt;
     /// use tokio::net::windows::named_pipe::{ClientOptions, ServerOptions};
-    /// use winapi::shared::winerror;
+    /// use windows_sys::Win32::Foundation::ERROR_PIPE_NOT_CONNECTED;
     ///
     /// const PIPE_NAME: &str = r"\\.\pipe\tokio-named-pipe-disconnect";
     ///
@@ -227,19 +227,25 @@ impl NamedPipeServer {
     /// // Write fails with an OS-specific error after client has been
     /// // disconnected.
     /// let e = client.write(b"ping").await.unwrap_err();
-    /// assert_eq!(e.raw_os_error(), Some(winerror::ERROR_PIPE_NOT_CONNECTED as i32));
+    /// assert_eq!(e.raw_os_error(), Some(ERROR_PIPE_NOT_CONNECTED as i32));
     /// # Ok(()) }
     /// ```
     pub fn disconnect(&self) -> io::Result<()> {
         self.io.disconnect()
     }
 
-    /// Wait for any of the requested ready states.
+    /// Waits for any of the requested ready states.
     ///
     /// This function is usually paired with `try_read()` or `try_write()`. It
     /// can be used to concurrently read / write to the same pipe on a single
     /// task without splitting the pipe.
     ///
+    /// The function may complete without the pipe being ready. This is a
+    /// false-positive and attempting an operation will return with
+    /// `io::ErrorKind::WouldBlock`. The function can also return with an empty
+    /// [`Ready`] set, so you should always check the returned value and possibly
+    /// wait again if the requested states are not set.
+    ///
     /// # Examples
     ///
     /// Concurrently read and write to the pipe on the same task without
@@ -301,7 +307,7 @@ impl NamedPipeServer {
         Ok(event.ready)
     }
 
-    /// Wait for the pipe to become readable.
+    /// Waits for the pipe to become readable.
     ///
     /// This function is equivalent to `ready(Interest::READABLE)` and is usually
     /// paired with `try_read()`.
@@ -383,7 +389,7 @@ impl NamedPipeServer {
         self.io.registration().poll_read_ready(cx).map_ok(|_| ())
     }
 
-    /// Try to read data from the pipe into the provided buffer, returning how
+    /// Tries to read data from the pipe into the provided buffer, returning how
     /// many bytes were read.
     ///
     /// Receives any pending data from the pipe but does not wait for new data
@@ -399,8 +405,12 @@ impl NamedPipeServer {
     /// # Return
     ///
     /// If data is successfully read, `Ok(n)` is returned, where `n` is the
-    /// number of bytes read. `Ok(0)` indicates the pipe's read half is closed
-    /// and will no longer yield data. If the pipe is not ready to read data
+    /// number of bytes read. If `n` is `0`, then it can indicate one of two scenarios:
+    ///
+    /// 1. The pipe's read half is closed and will no longer yield data.
+    /// 2. The specified buffer was 0 bytes in length.
+    ///
+    /// If the pipe is not ready to read data,
     /// `Err(io::ErrorKind::WouldBlock)` is returned.
     ///
     /// # Examples
@@ -450,7 +460,7 @@ impl NamedPipeServer {
             .try_io(Interest::READABLE, || (&*self.io).read(buf))
     }
 
-    /// Try to read data from the pipe into the provided buffers, returning
+    /// Tries to read data from the pipe into the provided buffers, returning
     /// how many bytes were read.
     ///
     /// Data is copied to fill each buffer in order, with the final buffer
@@ -528,7 +538,87 @@ impl NamedPipeServer {
             .try_io(Interest::READABLE, || (&*self.io).read_vectored(bufs))
     }
 
-    /// Wait for the pipe to become writable.
+    cfg_io_util! {
+        /// Tries to read data from the stream into the provided buffer, advancing the
+        /// buffer's internal cursor, returning how many bytes were read.
+        ///
+        /// Receives any pending data from the pipe but does not wait for new data
+        /// to arrive. On success, returns the number of bytes read. Because
+        /// `try_read_buf()` is non-blocking, the buffer does not have to be stored by
+        /// the async task and can exist entirely on the stack.
+        ///
+        /// Usually, [`readable()`] or [`ready()`] is used with this function.
+        ///
+        /// [`readable()`]: NamedPipeServer::readable()
+        /// [`ready()`]: NamedPipeServer::ready()
+        ///
+        /// # Return
+        ///
+        /// If data is successfully read, `Ok(n)` is returned, where `n` is the
+        /// number of bytes read. `Ok(0)` indicates the stream's read half is closed
+        /// and will no longer yield data. If the stream is not ready to read data
+        /// `Err(io::ErrorKind::WouldBlock)` is returned.
+        ///
+        /// # Examples
+        ///
+        /// ```no_run
+        /// use tokio::net::windows::named_pipe;
+        /// use std::error::Error;
+        /// use std::io;
+        ///
+        /// const PIPE_NAME: &str = r"\\.\pipe\tokio-named-pipe-client-readable";
+        ///
+        /// #[tokio::main]
+        /// async fn main() -> Result<(), Box<dyn Error>> {
+        ///     let server = named_pipe::ServerOptions::new().create(PIPE_NAME)?;
+        ///
+        ///     loop {
+        ///         // Wait for the pipe to be readable
+        ///         server.readable().await?;
+        ///
+        ///         let mut buf = Vec::with_capacity(4096);
+        ///
+        ///         // Try to read data, this may still fail with `WouldBlock`
+        ///         // if the readiness event is a false positive.
+        ///         match server.try_read_buf(&mut buf) {
+        ///             Ok(0) => break,
+        ///             Ok(n) => {
+        ///                 println!("read {} bytes", n);
+        ///             }
+        ///             Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
+        ///                 continue;
+        ///             }
+        ///             Err(e) => {
+        ///                 return Err(e.into());
+        ///             }
+        ///         }
+        ///     }
+        ///
+        ///     Ok(())
+        /// }
+        /// ```
+        pub fn try_read_buf<B: BufMut>(&self, buf: &mut B) -> io::Result<usize> {
+            self.io.registration().try_io(Interest::READABLE, || {
+                use std::io::Read;
+
+                let dst = buf.chunk_mut();
+                let dst =
+                    unsafe { &mut *(dst as *mut _ as *mut [std::mem::MaybeUninit<u8>] as *mut [u8]) };
+
+                // Safety: We trust `NamedPipeServer::read` to have filled up `n` bytes in the
+                // buffer.
+                let n = (&*self.io).read(dst)?;
+
+                unsafe {
+                    buf.advance_mut(n);
+                }
+
+                Ok(n)
+            })
+        }
+    }
+
+    /// Waits for the pipe to become writable.
     ///
     /// This function is equivalent to `ready(Interest::WRITABLE)` and is usually
     /// paired with `try_write()`.
@@ -606,7 +696,7 @@ impl NamedPipeServer {
         self.io.registration().poll_write_ready(cx).map_ok(|_| ())
     }
 
-    /// Try to write a buffer to the pipe, returning how many bytes were
+    /// Tries to write a buffer to the pipe, returning how many bytes were
     /// written.
     ///
     /// The function will attempt to write the entire contents of `buf`, but
@@ -662,7 +752,7 @@ impl NamedPipeServer {
             .try_io(Interest::WRITABLE, || (&*self.io).write(buf))
     }
 
-    /// Try to write several buffers to the pipe, returning how many bytes
+    /// Tries to write several buffers to the pipe, returning how many bytes
     /// were written.
     ///
     /// Data is written from each buffer in order, with the final buffer read
@@ -723,6 +813,79 @@ impl NamedPipeServer {
             .registration()
             .try_io(Interest::WRITABLE, || (&*self.io).write_vectored(buf))
     }
+
+    /// Tries to read or write from the pipe using a user-provided IO operation.
+    ///
+    /// If the pipe is ready, the provided closure is called. The closure
+    /// should attempt to perform IO operation from the pipe by manually
+    /// calling the appropriate syscall. If the operation fails because the
+    /// pipe is not actually ready, then the closure should return a
+    /// `WouldBlock` error and the readiness flag is cleared. The return value
+    /// of the closure is then returned by `try_io`.
+    ///
+    /// If the pipe is not ready, then the closure is not called
+    /// and a `WouldBlock` error is returned.
+    ///
+    /// The closure should only return a `WouldBlock` error if it has performed
+    /// an IO operation on the pipe that failed due to the pipe not being
+    /// ready. Returning a `WouldBlock` error in any other situation will
+    /// incorrectly clear the readiness flag, which can cause the pipe to
+    /// behave incorrectly.
+    ///
+    /// The closure should not perform the IO operation using any of the
+    /// methods defined on the Tokio `NamedPipeServer` type, as this will mess with
+    /// the readiness flag and can cause the pipe to behave incorrectly.
+    ///
+    /// This method is not intended to be used with combined interests.
+    /// The closure should perform only one type of IO operation, so it should not
+    /// require more than one ready state. This method may panic or sleep forever
+    /// if it is called with a combined interest.
+    ///
+    /// Usually, [`readable()`], [`writable()`] or [`ready()`] is used with this function.
+    ///
+    /// [`readable()`]: NamedPipeServer::readable()
+    /// [`writable()`]: NamedPipeServer::writable()
+    /// [`ready()`]: NamedPipeServer::ready()
+    pub fn try_io<R>(
+        &self,
+        interest: Interest,
+        f: impl FnOnce() -> io::Result<R>,
+    ) -> io::Result<R> {
+        self.io.registration().try_io(interest, f)
+    }
+
+    /// Reads or writes from the pipe using a user-provided IO operation.
+    ///
+    /// The readiness of the pipe is awaited and when the pipe is ready,
+    /// the provided closure is called. The closure should attempt to perform
+    /// IO operation on the pipe by manually calling the appropriate syscall.
+    /// If the operation fails because the pipe is not actually ready,
+    /// then the closure should return a `WouldBlock` error. In such case the
+    /// readiness flag is cleared and the pipe readiness is awaited again.
+    /// This loop is repeated until the closure returns an `Ok` or an error
+    /// other than `WouldBlock`.
+    ///
+    /// The closure should only return a `WouldBlock` error if it has performed
+    /// an IO operation on the pipe that failed due to the pipe not being
+    /// ready. Returning a `WouldBlock` error in any other situation will
+    /// incorrectly clear the readiness flag, which can cause the pipe to
+    /// behave incorrectly.
+    ///
+    /// The closure should not perform the IO operation using any of the methods
+    /// defined on the Tokio `NamedPipeServer` type, as this will mess with the
+    /// readiness flag and can cause the pipe to behave incorrectly.
+    ///
+    /// This method is not intended to be used with combined interests.
+    /// The closure should perform only one type of IO operation, so it should not
+    /// require more than one ready state. This method may panic or sleep forever
+    /// if it is called with a combined interest.
+    pub async fn async_io<R>(
+        &self,
+        interest: Interest,
+        f: impl FnMut() -> io::Result<R>,
+    ) -> io::Result<R> {
+        self.io.registration().async_io(interest, f).await
+    }
 }
 
 impl AsyncRead for NamedPipeServer {
@@ -767,6 +930,13 @@ impl AsRawHandle for NamedPipeServer {
     }
 }
 
+#[cfg(not(tokio_no_as_fd))]
+impl AsHandle for NamedPipeServer {
+    fn as_handle(&self) -> BorrowedHandle<'_> {
+        unsafe { BorrowedHandle::borrow_raw(self.as_raw_handle()) }
+    }
+}
+
 /// A [Windows named pipe] client.
 ///
 /// Constructed using [`ClientOptions::open`].
@@ -784,7 +954,7 @@ impl AsRawHandle for NamedPipeServer {
 /// use std::time::Duration;
 /// use tokio::net::windows::named_pipe::ClientOptions;
 /// use tokio::time;
-/// use winapi::shared::winerror;
+/// use windows_sys::Win32::Foundation::ERROR_PIPE_BUSY;
 ///
 /// const PIPE_NAME: &str = r"\\.\pipe\named-pipe-idiomatic-client";
 ///
@@ -792,7 +962,7 @@ impl AsRawHandle for NamedPipeServer {
 /// let client = loop {
 ///     match ClientOptions::new().open(PIPE_NAME) {
 ///         Ok(client) => break client,
-///         Err(e) if e.raw_os_error() == Some(winerror::ERROR_PIPE_BUSY as i32) => (),
+///         Err(e) if e.raw_os_error() == Some(ERROR_PIPE_BUSY as i32) => (),
 ///         Err(e) => return Err(e),
 ///     }
 ///
@@ -803,7 +973,7 @@ impl AsRawHandle for NamedPipeServer {
 /// # Ok(()) }
 /// ```
 ///
-/// [`ERROR_PIPE_BUSY`]: crate::winapi::shared::winerror::ERROR_PIPE_BUSY
+/// [`ERROR_PIPE_BUSY`]: https://docs.rs/windows-sys/latest/windows_sys/Win32/Foundation/constant.ERROR_PIPE_BUSY.html
 /// [Windows named pipe]: https://docs.microsoft.com/en-us/windows/win32/ipc/named-pipes
 #[derive(Debug)]
 pub struct NamedPipeClient {
@@ -811,7 +981,7 @@ pub struct NamedPipeClient {
 }
 
 impl NamedPipeClient {
-    /// Construct a new named pipe client from the specified raw handle.
+    /// Constructs a new named pipe client from the specified raw handle.
     ///
     /// This function will consume ownership of the handle given, passing
     /// responsibility for closing the handle to the returned object.
@@ -861,12 +1031,18 @@ impl NamedPipeClient {
         unsafe { named_pipe_info(self.io.as_raw_handle()) }
     }
 
-    /// Wait for any of the requested ready states.
+    /// Waits for any of the requested ready states.
     ///
     /// This function is usually paired with `try_read()` or `try_write()`. It
     /// can be used to concurrently read / write to the same pipe on a single
     /// task without splitting the pipe.
     ///
+    /// The function may complete without the pipe being ready. This is a
+    /// false-positive and attempting an operation will return with
+    /// `io::ErrorKind::WouldBlock`. The function can also return with an empty
+    /// [`Ready`] set, so you should always check the returned value and possibly
+    /// wait again if the requested states are not set.
+    ///
     /// # Examples
     ///
     /// Concurrently read and write to the pipe on the same task without
@@ -927,7 +1103,7 @@ impl NamedPipeClient {
         Ok(event.ready)
     }
 
-    /// Wait for the pipe to become readable.
+    /// Waits for the pipe to become readable.
     ///
     /// This function is equivalent to `ready(Interest::READABLE)` and is usually
     /// paired with `try_read()`.
@@ -1008,7 +1184,7 @@ impl NamedPipeClient {
         self.io.registration().poll_read_ready(cx).map_ok(|_| ())
     }
 
-    /// Try to read data from the pipe into the provided buffer, returning how
+    /// Tries to read data from the pipe into the provided buffer, returning how
     /// many bytes were read.
     ///
     /// Receives any pending data from the pipe but does not wait for new data
@@ -1024,8 +1200,12 @@ impl NamedPipeClient {
     /// # Return
     ///
     /// If data is successfully read, `Ok(n)` is returned, where `n` is the
-    /// number of bytes read. `Ok(0)` indicates the pipe's read half is closed
-    /// and will no longer yield data. If the pipe is not ready to read data
+    /// number of bytes read. If `n` is `0`, then it can indicate one of two scenarios:
+    ///
+    /// 1. The pipe's read half is closed and will no longer yield data.
+    /// 2. The specified buffer was 0 bytes in length.
+    ///
+    /// If the pipe is not ready to read data,
     /// `Err(io::ErrorKind::WouldBlock)` is returned.
     ///
     /// # Examples
@@ -1074,7 +1254,7 @@ impl NamedPipeClient {
             .try_io(Interest::READABLE, || (&*self.io).read(buf))
     }
 
-    /// Try to read data from the pipe into the provided buffers, returning
+    /// Tries to read data from the pipe into the provided buffers, returning
     /// how many bytes were read.
     ///
     /// Data is copied to fill each buffer in order, with the final buffer
@@ -1151,7 +1331,87 @@ impl NamedPipeClient {
             .try_io(Interest::READABLE, || (&*self.io).read_vectored(bufs))
     }
 
-    /// Wait for the pipe to become writable.
+    cfg_io_util! {
+        /// Tries to read data from the stream into the provided buffer, advancing the
+        /// buffer's internal cursor, returning how many bytes were read.
+        ///
+        /// Receives any pending data from the pipe but does not wait for new data
+        /// to arrive. On success, returns the number of bytes read. Because
+        /// `try_read_buf()` is non-blocking, the buffer does not have to be stored by
+        /// the async task and can exist entirely on the stack.
+        ///
+        /// Usually, [`readable()`] or [`ready()`] is used with this function.
+        ///
+        /// [`readable()`]: NamedPipeClient::readable()
+        /// [`ready()`]: NamedPipeClient::ready()
+        ///
+        /// # Return
+        ///
+        /// If data is successfully read, `Ok(n)` is returned, where `n` is the
+        /// number of bytes read. `Ok(0)` indicates the stream's read half is closed
+        /// and will no longer yield data. If the stream is not ready to read data
+        /// `Err(io::ErrorKind::WouldBlock)` is returned.
+        ///
+        /// # Examples
+        ///
+        /// ```no_run
+        /// use tokio::net::windows::named_pipe;
+        /// use std::error::Error;
+        /// use std::io;
+        ///
+        /// const PIPE_NAME: &str = r"\\.\pipe\tokio-named-pipe-client-readable";
+        ///
+        /// #[tokio::main]
+        /// async fn main() -> Result<(), Box<dyn Error>> {
+        ///     let client = named_pipe::ClientOptions::new().open(PIPE_NAME)?;
+        ///
+        ///     loop {
+        ///         // Wait for the pipe to be readable
+        ///         client.readable().await?;
+        ///
+        ///         let mut buf = Vec::with_capacity(4096);
+        ///
+        ///         // Try to read data, this may still fail with `WouldBlock`
+        ///         // if the readiness event is a false positive.
+        ///         match client.try_read_buf(&mut buf) {
+        ///             Ok(0) => break,
+        ///             Ok(n) => {
+        ///                 println!("read {} bytes", n);
+        ///             }
+        ///             Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
+        ///                 continue;
+        ///             }
+        ///             Err(e) => {
+        ///                 return Err(e.into());
+        ///             }
+        ///         }
+        ///     }
+        ///
+        ///     Ok(())
+        /// }
+        /// ```
+        pub fn try_read_buf<B: BufMut>(&self, buf: &mut B) -> io::Result<usize> {
+            self.io.registration().try_io(Interest::READABLE, || {
+                use std::io::Read;
+
+                let dst = buf.chunk_mut();
+                let dst =
+                    unsafe { &mut *(dst as *mut _ as *mut [std::mem::MaybeUninit<u8>] as *mut [u8]) };
+
+                // Safety: We trust `NamedPipeClient::read` to have filled up `n` bytes in the
+                // buffer.
+                let n = (&*self.io).read(dst)?;
+
+                unsafe {
+                    buf.advance_mut(n);
+                }
+
+                Ok(n)
+            })
+        }
+    }
+
+    /// Waits for the pipe to become writable.
     ///
     /// This function is equivalent to `ready(Interest::WRITABLE)` and is usually
     /// paired with `try_write()`.
@@ -1228,7 +1488,7 @@ impl NamedPipeClient {
         self.io.registration().poll_write_ready(cx).map_ok(|_| ())
     }
 
-    /// Try to write a buffer to the pipe, returning how many bytes were
+    /// Tries to write a buffer to the pipe, returning how many bytes were
     /// written.
     ///
     /// The function will attempt to write the entire contents of `buf`, but
@@ -1283,7 +1543,7 @@ impl NamedPipeClient {
             .try_io(Interest::WRITABLE, || (&*self.io).write(buf))
     }
 
-    /// Try to write several buffers to the pipe, returning how many bytes
+    /// Tries to write several buffers to the pipe, returning how many bytes
     /// were written.
     ///
     /// Data is written from each buffer in order, with the final buffer read
@@ -1343,6 +1603,79 @@ impl NamedPipeClient {
             .registration()
             .try_io(Interest::WRITABLE, || (&*self.io).write_vectored(buf))
     }
+
+    /// Tries to read or write from the pipe using a user-provided IO operation.
+    ///
+    /// If the pipe is ready, the provided closure is called. The closure
+    /// should attempt to perform IO operation from the pipe by manually
+    /// calling the appropriate syscall. If the operation fails because the
+    /// pipe is not actually ready, then the closure should return a
+    /// `WouldBlock` error and the readiness flag is cleared. The return value
+    /// of the closure is then returned by `try_io`.
+    ///
+    /// If the pipe is not ready, then the closure is not called
+    /// and a `WouldBlock` error is returned.
+    ///
+    /// The closure should only return a `WouldBlock` error if it has performed
+    /// an IO operation on the pipe that failed due to the pipe not being
+    /// ready. Returning a `WouldBlock` error in any other situation will
+    /// incorrectly clear the readiness flag, which can cause the pipe to
+    /// behave incorrectly.
+    ///
+    /// The closure should not perform the IO operation using any of the methods
+    /// defined on the Tokio `NamedPipeClient` type, as this will mess with the
+    /// readiness flag and can cause the pipe to behave incorrectly.
+    ///
+    /// This method is not intended to be used with combined interests.
+    /// The closure should perform only one type of IO operation, so it should not
+    /// require more than one ready state. This method may panic or sleep forever
+    /// if it is called with a combined interest.
+    ///
+    /// Usually, [`readable()`], [`writable()`] or [`ready()`] is used with this function.
+    ///
+    /// [`readable()`]: NamedPipeClient::readable()
+    /// [`writable()`]: NamedPipeClient::writable()
+    /// [`ready()`]: NamedPipeClient::ready()
+    pub fn try_io<R>(
+        &self,
+        interest: Interest,
+        f: impl FnOnce() -> io::Result<R>,
+    ) -> io::Result<R> {
+        self.io.registration().try_io(interest, f)
+    }
+
+    /// Reads or writes from the pipe using a user-provided IO operation.
+    ///
+    /// The readiness of the pipe is awaited and when the pipe is ready,
+    /// the provided closure is called. The closure should attempt to perform
+    /// IO operation on the pipe by manually calling the appropriate syscall.
+    /// If the operation fails because the pipe is not actually ready,
+    /// then the closure should return a `WouldBlock` error. In such case the
+    /// readiness flag is cleared and the pipe readiness is awaited again.
+    /// This loop is repeated until the closure returns an `Ok` or an error
+    /// other than `WouldBlock`.
+    ///
+    /// The closure should only return a `WouldBlock` error if it has performed
+    /// an IO operation on the pipe that failed due to the pipe not being
+    /// ready. Returning a `WouldBlock` error in any other situation will
+    /// incorrectly clear the readiness flag, which can cause the pipe to
+    /// behave incorrectly.
+    ///
+    /// The closure should not perform the IO operation using any of the methods
+    /// defined on the Tokio `NamedPipeClient` type, as this will mess with the
+    /// readiness flag and can cause the pipe to behave incorrectly.
+    ///
+    /// This method is not intended to be used with combined interests.
+    /// The closure should perform only one type of IO operation, so it should not
+    /// require more than one ready state. This method may panic or sleep forever
+    /// if it is called with a combined interest.
+    pub async fn async_io<R>(
+        &self,
+        interest: Interest,
+        f: impl FnMut() -> io::Result<R>,
+    ) -> io::Result<R> {
+        self.io.registration().async_io(interest, f).await
+    }
 }
 
 impl AsyncRead for NamedPipeClient {
@@ -1387,17 +1720,11 @@ impl AsRawHandle for NamedPipeClient {
     }
 }
 
-// Helper to set a boolean flag as a bitfield.
-macro_rules! bool_flag {
-    ($f:expr, $t:expr, $flag:expr) => {{
-        let current = $f;
-
-        if $t {
-            $f = current | $flag;
-        } else {
-            $f = current & !$flag;
-        };
-    }};
+#[cfg(not(tokio_no_as_fd))]
+impl AsHandle for NamedPipeClient {
+    fn as_handle(&self) -> BorrowedHandle<'_> {
+        unsafe { BorrowedHandle::borrow_raw(self.as_raw_handle()) }
+    }
 }
 
 /// A builder structure for construct a named pipe with named pipe-specific
@@ -1407,12 +1734,21 @@ macro_rules! bool_flag {
 /// See [`ServerOptions::create`].
 #[derive(Debug, Clone)]
 pub struct ServerOptions {
-    open_mode: DWORD,
-    pipe_mode: DWORD,
-    max_instances: DWORD,
-    out_buffer_size: DWORD,
-    in_buffer_size: DWORD,
-    default_timeout: DWORD,
+    // dwOpenMode
+    access_inbound: bool,
+    access_outbound: bool,
+    first_pipe_instance: bool,
+    write_dac: bool,
+    write_owner: bool,
+    access_system_security: bool,
+    // dwPipeMode
+    pipe_mode: PipeMode,
+    reject_remote_clients: bool,
+    // other options
+    max_instances: u32,
+    out_buffer_size: u32,
+    in_buffer_size: u32,
+    default_timeout: u32,
 }
 
 impl ServerOptions {
@@ -1429,9 +1765,15 @@ impl ServerOptions {
     /// ```
     pub fn new() -> ServerOptions {
         ServerOptions {
-            open_mode: winbase::PIPE_ACCESS_DUPLEX | winbase::FILE_FLAG_OVERLAPPED,
-            pipe_mode: winbase::PIPE_TYPE_BYTE | winbase::PIPE_REJECT_REMOTE_CLIENTS,
-            max_instances: winbase::PIPE_UNLIMITED_INSTANCES,
+            access_inbound: true,
+            access_outbound: true,
+            first_pipe_instance: false,
+            write_dac: false,
+            write_owner: false,
+            access_system_security: false,
+            pipe_mode: PipeMode::Byte,
+            reject_remote_clients: true,
+            max_instances: windows_sys::PIPE_UNLIMITED_INSTANCES,
             out_buffer_size: 65536,
             in_buffer_size: 65536,
             default_timeout: 0,
@@ -1443,15 +1785,11 @@ impl ServerOptions {
     /// The default pipe mode is [`PipeMode::Byte`]. See [`PipeMode`] for
     /// documentation of what each mode means.
     ///
-    /// This corresponding to specifying [`dwPipeMode`].
+    /// This corresponds to specifying `PIPE_TYPE_` and `PIPE_READMODE_` in  [`dwPipeMode`].
     ///
     /// [`dwPipeMode`]: https://docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-createnamedpipea
     pub fn pipe_mode(&mut self, pipe_mode: PipeMode) -> &mut Self {
-        self.pipe_mode = match pipe_mode {
-            PipeMode::Byte => winbase::PIPE_TYPE_BYTE,
-            PipeMode::Message => winbase::PIPE_TYPE_MESSAGE,
-        };
-
+        self.pipe_mode = pipe_mode;
         self
     }
 
@@ -1547,7 +1885,7 @@ impl ServerOptions {
     /// # Ok(()) }
     /// ```
     pub fn access_inbound(&mut self, allowed: bool) -> &mut Self {
-        bool_flag!(self.open_mode, allowed, winbase::PIPE_ACCESS_INBOUND);
+        self.access_inbound = allowed;
         self
     }
 
@@ -1645,7 +1983,7 @@ impl ServerOptions {
     /// # Ok(()) }
     /// ```
     pub fn access_outbound(&mut self, allowed: bool) -> &mut Self {
-        bool_flag!(self.open_mode, allowed, winbase::PIPE_ACCESS_OUTBOUND);
+        self.access_outbound = allowed;
         self
     }
 
@@ -1713,11 +2051,109 @@ impl ServerOptions {
     /// [`create`]: ServerOptions::create
     /// [`FILE_FLAG_FIRST_PIPE_INSTANCE`]: https://docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-createnamedpipea#pipe_first_pipe_instance
     pub fn first_pipe_instance(&mut self, first: bool) -> &mut Self {
-        bool_flag!(
-            self.open_mode,
-            first,
-            winbase::FILE_FLAG_FIRST_PIPE_INSTANCE
-        );
+        self.first_pipe_instance = first;
+        self
+    }
+
+    /// Requests permission to modify the pipe's discretionary access control list.
+    ///
+    /// This corresponds to setting [`WRITE_DAC`] in dwOpenMode.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::{io, os::windows::prelude::AsRawHandle, ptr};
+    //
+    /// use tokio::net::windows::named_pipe::ServerOptions;
+    /// use windows_sys::{
+    ///     Win32::Foundation::ERROR_SUCCESS,
+    ///     Win32::Security::DACL_SECURITY_INFORMATION,
+    ///     Win32::Security::Authorization::{SetSecurityInfo, SE_KERNEL_OBJECT},
+    /// };
+    ///
+    /// const PIPE_NAME: &str = r"\\.\pipe\write_dac_pipe";
+    ///
+    /// # #[tokio::main] async fn main() -> io::Result<()> {
+    /// let mut pipe_template = ServerOptions::new();
+    /// pipe_template.write_dac(true);
+    /// let pipe = pipe_template.create(PIPE_NAME)?;
+    ///
+    /// unsafe {
+    ///     assert_eq!(
+    ///         ERROR_SUCCESS,
+    ///         SetSecurityInfo(
+    ///             pipe.as_raw_handle() as _,
+    ///             SE_KERNEL_OBJECT,
+    ///             DACL_SECURITY_INFORMATION,
+    ///             ptr::null_mut(),
+    ///             ptr::null_mut(),
+    ///             ptr::null_mut(),
+    ///             ptr::null_mut(),
+    ///         )
+    ///     );
+    /// }
+    ///
+    /// # Ok(()) }
+    /// ```
+    ///
+    /// ```
+    /// use std::{io, os::windows::prelude::AsRawHandle, ptr};
+    //
+    /// use tokio::net::windows::named_pipe::ServerOptions;
+    /// use windows_sys::{
+    ///     Win32::Foundation::ERROR_ACCESS_DENIED,
+    ///     Win32::Security::DACL_SECURITY_INFORMATION,
+    ///     Win32::Security::Authorization::{SetSecurityInfo, SE_KERNEL_OBJECT},
+    /// };
+    ///
+    /// const PIPE_NAME: &str = r"\\.\pipe\write_dac_pipe_fail";
+    ///
+    /// # #[tokio::main] async fn main() -> io::Result<()> {
+    /// let mut pipe_template = ServerOptions::new();
+    /// pipe_template.write_dac(false);
+    /// let pipe = pipe_template.create(PIPE_NAME)?;
+    ///
+    /// unsafe {
+    ///     assert_eq!(
+    ///         ERROR_ACCESS_DENIED,
+    ///         SetSecurityInfo(
+    ///             pipe.as_raw_handle() as _,
+    ///             SE_KERNEL_OBJECT,
+    ///             DACL_SECURITY_INFORMATION,
+    ///             ptr::null_mut(),
+    ///             ptr::null_mut(),
+    ///             ptr::null_mut(),
+    ///             ptr::null_mut(),
+    ///         )
+    ///     );
+    /// }
+    ///
+    /// # Ok(()) }
+    /// ```
+    ///
+    /// [`WRITE_DAC`]: https://docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-createnamedpipea
+    pub fn write_dac(&mut self, requested: bool) -> &mut Self {
+        self.write_dac = requested;
+        self
+    }
+
+    /// Requests permission to modify the pipe's owner.
+    ///
+    /// This corresponds to setting [`WRITE_OWNER`] in dwOpenMode.
+    ///
+    /// [`WRITE_OWNER`]: https://docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-createnamedpipea
+    pub fn write_owner(&mut self, requested: bool) -> &mut Self {
+        self.write_owner = requested;
+        self
+    }
+
+    /// Requests permission to modify the pipe's system access control list.
+    ///
+    /// This corresponds to setting [`ACCESS_SYSTEM_SECURITY`] in dwOpenMode.
+    ///
+    /// [`ACCESS_SYSTEM_SECURITY`]: https://docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-createnamedpipea
+    pub fn access_system_security(&mut self, requested: bool) -> &mut Self {
+        self.access_system_security = requested;
         self
     }
 
@@ -1728,7 +2164,7 @@ impl ServerOptions {
     ///
     /// [`PIPE_REJECT_REMOTE_CLIENTS`]: https://docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-createnamedpipea#pipe_reject_remote_clients
     pub fn reject_remote_clients(&mut self, reject: bool) -> &mut Self {
-        bool_flag!(self.pipe_mode, reject, winbase::PIPE_REJECT_REMOTE_CLIENTS);
+        self.reject_remote_clients = reject;
         self
     }
 
@@ -1750,7 +2186,7 @@ impl ServerOptions {
     /// ```
     /// use std::io;
     /// use tokio::net::windows::named_pipe::{ServerOptions, ClientOptions};
-    /// use winapi::shared::winerror;
+    /// use windows_sys::Win32::Foundation::ERROR_PIPE_BUSY;
     ///
     /// const PIPE_NAME: &str = r"\\.\pipe\tokio-named-pipe-max-instances";
     ///
@@ -1766,11 +2202,11 @@ impl ServerOptions {
     ///
     /// // Too many servers!
     /// let e = server.create(PIPE_NAME).unwrap_err();
-    /// assert_eq!(e.raw_os_error(), Some(winerror::ERROR_PIPE_BUSY as i32));
+    /// assert_eq!(e.raw_os_error(), Some(ERROR_PIPE_BUSY as i32));
     ///
     /// // Still too many servers even if we specify a higher value!
     /// let e = server.max_instances(100).create(PIPE_NAME).unwrap_err();
-    /// assert_eq!(e.raw_os_error(), Some(winerror::ERROR_PIPE_BUSY as i32));
+    /// assert_eq!(e.raw_os_error(), Some(ERROR_PIPE_BUSY as i32));
     /// # Ok(()) }
     /// ```
     ///
@@ -1786,9 +2222,10 @@ impl ServerOptions {
     /// let builder = ServerOptions::new().max_instances(255);
     /// # Ok(()) }
     /// ```
+    #[track_caller]
     pub fn max_instances(&mut self, instances: usize) -> &mut Self {
         assert!(instances < 255, "cannot specify more than 254 instances");
-        self.max_instances = instances as DWORD;
+        self.max_instances = instances as u32;
         self
     }
 
@@ -1798,7 +2235,7 @@ impl ServerOptions {
     ///
     /// [`nOutBufferSize`]: https://docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-createnamedpipea
     pub fn out_buffer_size(&mut self, buffer: u32) -> &mut Self {
-        self.out_buffer_size = buffer as DWORD;
+        self.out_buffer_size = buffer;
         self
     }
 
@@ -1808,11 +2245,11 @@ impl ServerOptions {
     ///
     /// [`nInBufferSize`]: https://docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-createnamedpipea
     pub fn in_buffer_size(&mut self, buffer: u32) -> &mut Self {
-        self.in_buffer_size = buffer as DWORD;
+        self.in_buffer_size = buffer;
         self
     }
 
-    /// Create the named pipe identified by `addr` for use as a server.
+    /// Creates the named pipe identified by `addr` for use as a server.
     ///
     /// This uses the [`CreateNamedPipe`] function.
     ///
@@ -1843,7 +2280,7 @@ impl ServerOptions {
         unsafe { self.create_with_security_attributes_raw(addr, ptr::null_mut()) }
     }
 
-    /// Create the named pipe identified by `addr` for use as a server.
+    /// Creates the named pipe identified by `addr` for use as a server.
     ///
     /// This is the same as [`create`] except that it supports providing the raw
     /// pointer to a structure of [`SECURITY_ATTRIBUTES`] which will be passed
@@ -1865,7 +2302,7 @@ impl ServerOptions {
     ///
     /// [`create`]: ServerOptions::create
     /// [`CreateFile`]: https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-createfilew
-    /// [`SECURITY_ATTRIBUTES`]: crate::winapi::um::minwinbase::SECURITY_ATTRIBUTES
+    /// [`SECURITY_ATTRIBUTES`]: https://docs.rs/windows-sys/latest/windows_sys/Win32/Security/struct.SECURITY_ATTRIBUTES.html
     pub unsafe fn create_with_security_attributes_raw(
         &self,
         addr: impl AsRef<OsStr>,
@@ -1873,10 +2310,46 @@ impl ServerOptions {
     ) -> io::Result<NamedPipeServer> {
         let addr = encode_addr(addr);
 
-        let h = namedpipeapi::CreateNamedPipeW(
+        let pipe_mode = {
+            let mut mode = if matches!(self.pipe_mode, PipeMode::Message) {
+                windows_sys::PIPE_TYPE_MESSAGE | windows_sys::PIPE_READMODE_MESSAGE
+            } else {
+                windows_sys::PIPE_TYPE_BYTE | windows_sys::PIPE_READMODE_BYTE
+            };
+            if self.reject_remote_clients {
+                mode |= windows_sys::PIPE_REJECT_REMOTE_CLIENTS;
+            } else {
+                mode |= windows_sys::PIPE_ACCEPT_REMOTE_CLIENTS;
+            }
+            mode
+        };
+        let open_mode = {
+            let mut mode = windows_sys::FILE_FLAG_OVERLAPPED;
+            if self.access_inbound {
+                mode |= windows_sys::PIPE_ACCESS_INBOUND;
+            }
+            if self.access_outbound {
+                mode |= windows_sys::PIPE_ACCESS_OUTBOUND;
+            }
+            if self.first_pipe_instance {
+                mode |= windows_sys::FILE_FLAG_FIRST_PIPE_INSTANCE;
+            }
+            if self.write_dac {
+                mode |= windows_sys::WRITE_DAC;
+            }
+            if self.write_owner {
+                mode |= windows_sys::WRITE_OWNER;
+            }
+            if self.access_system_security {
+                mode |= windows_sys::ACCESS_SYSTEM_SECURITY;
+            }
+            mode
+        };
+
+        let h = windows_sys::CreateNamedPipeW(
             addr.as_ptr(),
-            self.open_mode,
-            self.pipe_mode,
+            open_mode,
+            pipe_mode,
             self.max_instances,
             self.out_buffer_size,
             self.in_buffer_size,
@@ -1884,11 +2357,11 @@ impl ServerOptions {
             attrs as *mut _,
         );
 
-        if h == handleapi::INVALID_HANDLE_VALUE {
+        if h == windows_sys::INVALID_HANDLE_VALUE {
             return Err(io::Error::last_os_error());
         }
 
-        NamedPipeServer::from_raw_handle(h)
+        NamedPipeServer::from_raw_handle(h as _)
     }
 }
 
@@ -1898,8 +2371,10 @@ impl ServerOptions {
 /// See [`ClientOptions::open`].
 #[derive(Debug, Clone)]
 pub struct ClientOptions {
-    desired_access: DWORD,
-    security_qos_flags: DWORD,
+    generic_read: bool,
+    generic_write: bool,
+    security_qos_flags: u32,
+    pipe_mode: PipeMode,
 }
 
 impl ClientOptions {
@@ -1918,8 +2393,11 @@ impl ClientOptions {
     /// ```
     pub fn new() -> Self {
         Self {
-            desired_access: winnt::GENERIC_READ | winnt::GENERIC_WRITE,
-            security_qos_flags: winbase::SECURITY_IDENTIFICATION | winbase::SECURITY_SQOS_PRESENT,
+            generic_read: true,
+            generic_write: true,
+            security_qos_flags: windows_sys::SECURITY_IDENTIFICATION
+                | windows_sys::SECURITY_SQOS_PRESENT,
+            pipe_mode: PipeMode::Byte,
         }
     }
 
@@ -1930,7 +2408,7 @@ impl ClientOptions {
     /// [`GENERIC_READ`]: https://docs.microsoft.com/en-us/windows/win32/secauthz/generic-access-rights
     /// [`CreateFile`]: https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-createfilew
     pub fn read(&mut self, allowed: bool) -> &mut Self {
-        bool_flag!(self.desired_access, allowed, winnt::GENERIC_READ);
+        self.generic_read = allowed;
         self
     }
 
@@ -1941,7 +2419,7 @@ impl ClientOptions {
     /// [`GENERIC_WRITE`]: https://docs.microsoft.com/en-us/windows/win32/secauthz/generic-access-rights
     /// [`CreateFile`]: https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-createfilew
     pub fn write(&mut self, allowed: bool) -> &mut Self {
-        bool_flag!(self.desired_access, allowed, winnt::GENERIC_WRITE);
+        self.generic_write = allowed;
         self
     }
 
@@ -1964,15 +2442,24 @@ impl ClientOptions {
     /// automatically when using this method.
     ///
     /// [`CreateFile`]: https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-createfilea
-    /// [`SECURITY_IDENTIFICATION`]: crate::winapi::um::winbase::SECURITY_IDENTIFICATION
+    /// [`SECURITY_IDENTIFICATION`]: https://docs.rs/windows-sys/latest/windows_sys/Win32/Storage/FileSystem/constant.SECURITY_IDENTIFICATION.html
     /// [Impersonation Levels]: https://docs.microsoft.com/en-us/windows/win32/api/winnt/ne-winnt-security_impersonation_level
     pub fn security_qos_flags(&mut self, flags: u32) -> &mut Self {
         // See: https://github.com/rust-lang/rust/pull/58216
-        self.security_qos_flags = flags | winbase::SECURITY_SQOS_PRESENT;
+        self.security_qos_flags = flags | windows_sys::SECURITY_SQOS_PRESENT;
+        self
+    }
+
+    /// The pipe mode.
+    ///
+    /// The default pipe mode is [`PipeMode::Byte`]. See [`PipeMode`] for
+    /// documentation of what each mode means.
+    pub fn pipe_mode(&mut self, pipe_mode: PipeMode) -> &mut Self {
+        self.pipe_mode = pipe_mode;
         self
     }
 
-    /// Open the named pipe identified by `addr`.
+    /// Opens the named pipe identified by `addr`.
     ///
     /// This opens the client using [`CreateFile`] with the
     /// `dwCreationDisposition` option set to `OPEN_EXISTING`.
@@ -1993,8 +2480,7 @@ impl ClientOptions {
     ///   but the server is not currently waiting for a connection. Please see the
     ///   examples for how to check for this error.
     ///
-    /// [`ERROR_PIPE_BUSY`]: crate::winapi::shared::winerror::ERROR_PIPE_BUSY
-    /// [`winapi`]: crate::winapi
+    /// [`ERROR_PIPE_BUSY`]: https://docs.rs/windows-sys/latest/windows_sys/Win32/Foundation/constant.ERROR_PIPE_BUSY.html
     /// [enabled I/O]: crate::runtime::Builder::enable_io
     /// [Tokio Runtime]: crate::runtime::Runtime
     ///
@@ -2005,7 +2491,7 @@ impl ClientOptions {
     /// use std::time::Duration;
     /// use tokio::net::windows::named_pipe::ClientOptions;
     /// use tokio::time;
-    /// use winapi::shared::winerror;
+    /// use windows_sys::Win32::Foundation::ERROR_PIPE_BUSY;
     ///
     /// const PIPE_NAME: &str = r"\\.\pipe\mynamedpipe";
     ///
@@ -2013,7 +2499,7 @@ impl ClientOptions {
     /// let client = loop {
     ///     match ClientOptions::new().open(PIPE_NAME) {
     ///         Ok(client) => break client,
-    ///         Err(e) if e.raw_os_error() == Some(winerror::ERROR_PIPE_BUSY as i32) => (),
+    ///         Err(e) if e.raw_os_error() == Some(ERROR_PIPE_BUSY as i32) => (),
     ///         Err(e) => return Err(e),
     ///     }
     ///
@@ -2029,7 +2515,7 @@ impl ClientOptions {
         unsafe { self.open_with_security_attributes_raw(addr, ptr::null_mut()) }
     }
 
-    /// Open the named pipe identified by `addr`.
+    /// Opens the named pipe identified by `addr`.
     ///
     /// This is the same as [`open`] except that it supports providing the raw
     /// pointer to a structure of [`SECURITY_ATTRIBUTES`] which will be passed
@@ -2043,7 +2529,7 @@ impl ClientOptions {
     ///
     /// [`open`]: ClientOptions::open
     /// [`CreateFile`]: https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-createfilew
-    /// [`SECURITY_ATTRIBUTES`]: crate::winapi::um::minwinbase::SECURITY_ATTRIBUTES
+    /// [`SECURITY_ATTRIBUTES`]: https://docs.rs/windows-sys/latest/windows_sys/Win32/Security/struct.SECURITY_ATTRIBUTES.html
     pub unsafe fn open_with_security_attributes_raw(
         &self,
         addr: impl AsRef<OsStr>,
@@ -2051,29 +2537,50 @@ impl ClientOptions {
     ) -> io::Result<NamedPipeClient> {
         let addr = encode_addr(addr);
 
+        let desired_access = {
+            let mut access = 0;
+            if self.generic_read {
+                access |= windows_sys::GENERIC_READ;
+            }
+            if self.generic_write {
+                access |= windows_sys::GENERIC_WRITE;
+            }
+            access
+        };
+
         // NB: We could use a platform specialized `OpenOptions` here, but since
-        // we have access to winapi it ultimately doesn't hurt to use
+        // we have access to windows_sys it ultimately doesn't hurt to use
         // `CreateFile` explicitly since it allows the use of our already
         // well-structured wide `addr` to pass into CreateFileW.
-        let h = fileapi::CreateFileW(
+        let h = windows_sys::CreateFileW(
             addr.as_ptr(),
-            self.desired_access,
+            desired_access,
             0,
             attrs as *mut _,
-            fileapi::OPEN_EXISTING,
+            windows_sys::OPEN_EXISTING,
             self.get_flags(),
-            ptr::null_mut(),
+            0,
         );
 
-        if h == handleapi::INVALID_HANDLE_VALUE {
+        if h == windows_sys::INVALID_HANDLE_VALUE {
             return Err(io::Error::last_os_error());
         }
 
-        NamedPipeClient::from_raw_handle(h)
+        if matches!(self.pipe_mode, PipeMode::Message) {
+            let mode = windows_sys::PIPE_READMODE_MESSAGE;
+            let result =
+                windows_sys::SetNamedPipeHandleState(h, &mode, ptr::null_mut(), ptr::null_mut());
+
+            if result == 0 {
+                return Err(io::Error::last_os_error());
+            }
+        }
+
+        NamedPipeClient::from_raw_handle(h as _)
     }
 
     fn get_flags(&self) -> u32 {
-        self.security_qos_flags | winbase::FILE_FLAG_OVERLAPPED
+        self.security_qos_flags | windows_sys::FILE_FLAG_OVERLAPPED
     }
 }
 
@@ -2086,16 +2593,19 @@ pub enum PipeMode {
     /// Data is written to the pipe as a stream of bytes. The pipe does not
     /// distinguish bytes written during different write operations.
     ///
-    /// Corresponds to [`PIPE_TYPE_BYTE`][crate::winapi::um::winbase::PIPE_TYPE_BYTE].
+    /// Corresponds to [`PIPE_TYPE_BYTE`].
+    ///
+    /// [`PIPE_TYPE_BYTE`]: https://docs.rs/windows-sys/latest/windows_sys/Win32/System/Pipes/constant.PIPE_TYPE_BYTE.html
     Byte,
     /// Data is written to the pipe as a stream of messages. The pipe treats the
     /// bytes written during each write operation as a message unit. Any reading
     /// on a named pipe returns [`ERROR_MORE_DATA`] when a message is not read
     /// completely.
     ///
-    /// Corresponds to [`PIPE_TYPE_MESSAGE`][crate::winapi::um::winbase::PIPE_TYPE_MESSAGE].
+    /// Corresponds to [`PIPE_TYPE_MESSAGE`].
     ///
-    /// [`ERROR_MORE_DATA`]: crate::winapi::shared::winerror::ERROR_MORE_DATA
+    /// [`ERROR_MORE_DATA`]: https://docs.rs/windows-sys/latest/windows_sys/Win32/Foundation/constant.ERROR_MORE_DATA.html
+    /// [`PIPE_TYPE_MESSAGE`]: https://docs.rs/windows-sys/latest/windows_sys/Win32/System/Pipes/constant.PIPE_TYPE_MESSAGE.html
     Message,
 }
 
@@ -2105,11 +2615,15 @@ pub enum PipeMode {
 pub enum PipeEnd {
     /// The named pipe refers to the client end of a named pipe instance.
     ///
-    /// Corresponds to [`PIPE_CLIENT_END`][crate::winapi::um::winbase::PIPE_CLIENT_END].
+    /// Corresponds to [`PIPE_CLIENT_END`].
+    ///
+    /// [`PIPE_CLIENT_END`]: https://docs.rs/windows-sys/latest/windows_sys/Win32/System/Pipes/constant.PIPE_CLIENT_END.html
     Client,
     /// The named pipe refers to the server end of a named pipe instance.
     ///
-    /// Corresponds to [`PIPE_SERVER_END`][crate::winapi::um::winbase::PIPE_SERVER_END].
+    /// Corresponds to [`PIPE_SERVER_END`].
+    ///
+    /// [`PIPE_SERVER_END`]: https://docs.rs/windows-sys/latest/windows_sys/Win32/System/Pipes/constant.PIPE_SERVER_END.html
     Server,
 }
 
@@ -2131,7 +2645,7 @@ pub struct PipeInfo {
     pub in_buffer_size: u32,
 }
 
-/// Encode an address so that it is a null-terminated wide string.
+/// Encodes an address so that it is a null-terminated wide string.
 fn encode_addr(addr: impl AsRef<OsStr>) -> Box<[u16]> {
     let len = addr.as_ref().encode_wide().count();
     let mut vec = Vec::with_capacity(len + 1);
@@ -2147,26 +2661,26 @@ unsafe fn named_pipe_info(handle: RawHandle) -> io::Result<PipeInfo> {
     let mut in_buffer_size = 0;
     let mut max_instances = 0;
 
-    let result = namedpipeapi::GetNamedPipeInfo(
-        handle,
+    let result = windows_sys::GetNamedPipeInfo(
+        handle as _,
         &mut flags,
         &mut out_buffer_size,
         &mut in_buffer_size,
         &mut max_instances,
     );
 
-    if result == FALSE {
+    if result == 0 {
         return Err(io::Error::last_os_error());
     }
 
     let mut end = PipeEnd::Client;
     let mut mode = PipeMode::Byte;
 
-    if flags & winbase::PIPE_SERVER_END != 0 {
+    if flags & windows_sys::PIPE_SERVER_END != 0 {
         end = PipeEnd::Server;
     }
 
-    if flags & winbase::PIPE_TYPE_MESSAGE != 0 {
+    if flags & windows_sys::PIPE_TYPE_MESSAGE != 0 {
         mode = PipeMode::Message;
     }
 
diff --git a/vendor/tokio/src/park/either.rs b/vendor/tokio/src/park/either.rs
deleted file mode 100644
index ee02ec158..000000000
--- a/vendor/tokio/src/park/either.rs
+++ /dev/null
@@ -1,74 +0,0 @@
-#![cfg_attr(not(feature = "full"), allow(dead_code))]
-
-use crate::park::{Park, Unpark};
-
-use std::fmt;
-use std::time::Duration;
-
-pub(crate) enum Either<A, B> {
-    A(A),
-    B(B),
-}
-
-impl<A, B> Park for Either<A, B>
-where
-    A: Park,
-    B: Park,
-{
-    type Unpark = Either<A::Unpark, B::Unpark>;
-    type Error = Either<A::Error, B::Error>;
-
-    fn unpark(&self) -> Self::Unpark {
-        match self {
-            Either::A(a) => Either::A(a.unpark()),
-            Either::B(b) => Either::B(b.unpark()),
-        }
-    }
-
-    fn park(&mut self) -> Result<(), Self::Error> {
-        match self {
-            Either::A(a) => a.park().map_err(Either::A),
-            Either::B(b) => b.park().map_err(Either::B),
-        }
-    }
-
-    fn park_timeout(&mut self, duration: Duration) -> Result<(), Self::Error> {
-        match self {
-            Either::A(a) => a.park_timeout(duration).map_err(Either::A),
-            Either::B(b) => b.park_timeout(duration).map_err(Either::B),
-        }
-    }
-
-    fn shutdown(&mut self) {
-        match self {
-            Either::A(a) => a.shutdown(),
-            Either::B(b) => b.shutdown(),
-        }
-    }
-}
-
-impl<A, B> Unpark for Either<A, B>
-where
-    A: Unpark,
-    B: Unpark,
-{
-    fn unpark(&self) {
-        match self {
-            Either::A(a) => a.unpark(),
-            Either::B(b) => b.unpark(),
-        }
-    }
-}
-
-impl<A, B> fmt::Debug for Either<A, B>
-where
-    A: fmt::Debug,
-    B: fmt::Debug,
-{
-    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
-        match self {
-            Either::A(a) => a.fmt(fmt),
-            Either::B(b) => b.fmt(fmt),
-        }
-    }
-}
diff --git a/vendor/tokio/src/park/mod.rs b/vendor/tokio/src/park/mod.rs
deleted file mode 100644
index edd937100..000000000
--- a/vendor/tokio/src/park/mod.rs
+++ /dev/null
@@ -1,117 +0,0 @@
-//! Abstraction over blocking and unblocking the current thread.
-//!
-//! Provides an abstraction over blocking the current thread. This is similar to
-//! the park / unpark constructs provided by `std` but made generic. This allows
-//! embedding custom functionality to perform when the thread is blocked.
-//!
-//! A blocked `Park` instance is unblocked by calling `unpark` on its
-//! `Unpark` handle.
-//!
-//! The `ParkThread` struct implements `Park` using `thread::park` to put the
-//! thread to sleep. The Tokio reactor also implements park, but uses
-//! `mio::Poll` to block the thread instead.
-//!
-//! The `Park` trait is composable. A timer implementation might decorate a
-//! `Park` implementation by checking if any timeouts have elapsed after the
-//! inner `Park` implementation unblocks.
-//!
-//! # Model
-//!
-//! Conceptually, each `Park` instance has an associated token, which is
-//! initially not present:
-//!
-//! * The `park` method blocks the current thread unless or until the token is
-//!   available, at which point it atomically consumes the token.
-//! * The `unpark` method atomically makes the token available if it wasn't
-//!   already.
-//!
-//! Some things to note:
-//!
-//! * If `unpark` is called before `park`, the next call to `park` will
-//!   **not** block the thread.
-//! * **Spurious** wakeups are permitted, i.e., the `park` method may unblock
-//!   even if `unpark` was not called.
-//! * `park_timeout` does the same as `park` but allows specifying a maximum
-//!   time to block the thread for.
-
-cfg_rt! {
-    pub(crate) mod either;
-}
-
-#[cfg(any(feature = "rt", feature = "sync"))]
-pub(crate) mod thread;
-
-use std::fmt::Debug;
-use std::sync::Arc;
-use std::time::Duration;
-
-/// Block the current thread.
-pub(crate) trait Park {
-    /// Unpark handle type for the `Park` implementation.
-    type Unpark: Unpark;
-
-    /// Error returned by `park`
-    type Error: Debug;
-
-    /// Gets a new `Unpark` handle associated with this `Park` instance.
-    fn unpark(&self) -> Self::Unpark;
-
-    /// Blocks the current thread unless or until the token is available.
-    ///
-    /// A call to `park` does not guarantee that the thread will remain blocked
-    /// forever, and callers should be prepared for this possibility. This
-    /// function may wakeup spuriously for any reason.
-    ///
-    /// # Panics
-    ///
-    /// This function **should** not panic, but ultimately, panics are left as
-    /// an implementation detail. Refer to the documentation for the specific
-    /// `Park` implementation
-    fn park(&mut self) -> Result<(), Self::Error>;
-
-    /// Parks the current thread for at most `duration`.
-    ///
-    /// This function is the same as `park` but allows specifying a maximum time
-    /// to block the thread for.
-    ///
-    /// Same as `park`, there is no guarantee that the thread will remain
-    /// blocked for any amount of time. Spurious wakeups are permitted for any
-    /// reason.
-    ///
-    /// # Panics
-    ///
-    /// This function **should** not panic, but ultimately, panics are left as
-    /// an implementation detail. Refer to the documentation for the specific
-    /// `Park` implementation
-    fn park_timeout(&mut self, duration: Duration) -> Result<(), Self::Error>;
-
-    /// Release all resources holded by the parker for proper leak-free shutdown
-    fn shutdown(&mut self);
-}
-
-/// Unblock a thread blocked by the associated `Park` instance.
-pub(crate) trait Unpark: Sync + Send + 'static {
-    /// Unblocks a thread that is blocked by the associated `Park` handle.
-    ///
-    /// Calling `unpark` atomically makes available the unpark token, if it is
-    /// not already available.
-    ///
-    /// # Panics
-    ///
-    /// This function **should** not panic, but ultimately, panics are left as
-    /// an implementation detail. Refer to the documentation for the specific
-    /// `Unpark` implementation
-    fn unpark(&self);
-}
-
-impl Unpark for Box<dyn Unpark> {
-    fn unpark(&self) {
-        (**self).unpark()
-    }
-}
-
-impl Unpark for Arc<dyn Unpark> {
-    fn unpark(&self) {
-        (**self).unpark()
-    }
-}
diff --git a/vendor/tokio/src/park/thread.rs b/vendor/tokio/src/park/thread.rs
deleted file mode 100644
index 2725e4563..000000000
--- a/vendor/tokio/src/park/thread.rs
+++ /dev/null
@@ -1,346 +0,0 @@
-#![cfg_attr(not(feature = "full"), allow(dead_code))]
-
-use crate::loom::sync::atomic::AtomicUsize;
-use crate::loom::sync::{Arc, Condvar, Mutex};
-use crate::park::{Park, Unpark};
-
-use std::sync::atomic::Ordering::SeqCst;
-use std::time::Duration;
-
-#[derive(Debug)]
-pub(crate) struct ParkThread {
-    inner: Arc<Inner>,
-}
-
-pub(crate) type ParkError = ();
-
-/// Unblocks a thread that was blocked by `ParkThread`.
-#[derive(Clone, Debug)]
-pub(crate) struct UnparkThread {
-    inner: Arc<Inner>,
-}
-
-#[derive(Debug)]
-struct Inner {
-    state: AtomicUsize,
-    mutex: Mutex<()>,
-    condvar: Condvar,
-}
-
-const EMPTY: usize = 0;
-const PARKED: usize = 1;
-const NOTIFIED: usize = 2;
-
-thread_local! {
-    static CURRENT_PARKER: ParkThread = ParkThread::new();
-}
-
-// ==== impl ParkThread ====
-
-impl ParkThread {
-    pub(crate) fn new() -> Self {
-        Self {
-            inner: Arc::new(Inner {
-                state: AtomicUsize::new(EMPTY),
-                mutex: Mutex::new(()),
-                condvar: Condvar::new(),
-            }),
-        }
-    }
-}
-
-impl Park for ParkThread {
-    type Unpark = UnparkThread;
-    type Error = ParkError;
-
-    fn unpark(&self) -> Self::Unpark {
-        let inner = self.inner.clone();
-        UnparkThread { inner }
-    }
-
-    fn park(&mut self) -> Result<(), Self::Error> {
-        self.inner.park();
-        Ok(())
-    }
-
-    fn park_timeout(&mut self, duration: Duration) -> Result<(), Self::Error> {
-        self.inner.park_timeout(duration);
-        Ok(())
-    }
-
-    fn shutdown(&mut self) {
-        self.inner.shutdown();
-    }
-}
-
-// ==== impl Inner ====
-
-impl Inner {
-    /// Park the current thread for at most `dur`.
-    fn park(&self) {
-        // If we were previously notified then we consume this notification and
-        // return quickly.
-        if self
-            .state
-            .compare_exchange(NOTIFIED, EMPTY, SeqCst, SeqCst)
-            .is_ok()
-        {
-            return;
-        }
-
-        // Otherwise we need to coordinate going to sleep
-        let mut m = self.mutex.lock();
-
-        match self.state.compare_exchange(EMPTY, PARKED, SeqCst, SeqCst) {
-            Ok(_) => {}
-            Err(NOTIFIED) => {
-                // We must read here, even though we know it will be `NOTIFIED`.
-                // This is because `unpark` may have been called again since we read
-                // `NOTIFIED` in the `compare_exchange` above. We must perform an
-                // acquire operation that synchronizes with that `unpark` to observe
-                // any writes it made before the call to unpark. To do that we must
-                // read from the write it made to `state`.
-                let old = self.state.swap(EMPTY, SeqCst);
-                debug_assert_eq!(old, NOTIFIED, "park state changed unexpectedly");
-
-                return;
-            }
-            Err(actual) => panic!("inconsistent park state; actual = {}", actual),
-        }
-
-        loop {
-            m = self.condvar.wait(m).unwrap();
-
-            if self
-                .state
-                .compare_exchange(NOTIFIED, EMPTY, SeqCst, SeqCst)
-                .is_ok()
-            {
-                // got a notification
-                return;
-            }
-
-            // spurious wakeup, go back to sleep
-        }
-    }
-
-    fn park_timeout(&self, dur: Duration) {
-        // Like `park` above we have a fast path for an already-notified thread,
-        // and afterwards we start coordinating for a sleep. Return quickly.
-        if self
-            .state
-            .compare_exchange(NOTIFIED, EMPTY, SeqCst, SeqCst)
-            .is_ok()
-        {
-            return;
-        }
-
-        if dur == Duration::from_millis(0) {
-            return;
-        }
-
-        let m = self.mutex.lock();
-
-        match self.state.compare_exchange(EMPTY, PARKED, SeqCst, SeqCst) {
-            Ok(_) => {}
-            Err(NOTIFIED) => {
-                // We must read again here, see `park`.
-                let old = self.state.swap(EMPTY, SeqCst);
-                debug_assert_eq!(old, NOTIFIED, "park state changed unexpectedly");
-
-                return;
-            }
-            Err(actual) => panic!("inconsistent park_timeout state; actual = {}", actual),
-        }
-
-        // Wait with a timeout, and if we spuriously wake up or otherwise wake up
-        // from a notification, we just want to unconditionally set the state back to
-        // empty, either consuming a notification or un-flagging ourselves as
-        // parked.
-        let (_m, _result) = self.condvar.wait_timeout(m, dur).unwrap();
-
-        match self.state.swap(EMPTY, SeqCst) {
-            NOTIFIED => {} // got a notification, hurray!
-            PARKED => {}   // no notification, alas
-            n => panic!("inconsistent park_timeout state: {}", n),
-        }
-    }
-
-    fn unpark(&self) {
-        // To ensure the unparked thread will observe any writes we made before
-        // this call, we must perform a release operation that `park` can
-        // synchronize with. To do that we must write `NOTIFIED` even if `state`
-        // is already `NOTIFIED`. That is why this must be a swap rather than a
-        // compare-and-swap that returns if it reads `NOTIFIED` on failure.
-        match self.state.swap(NOTIFIED, SeqCst) {
-            EMPTY => return,    // no one was waiting
-            NOTIFIED => return, // already unparked
-            PARKED => {}        // gotta go wake someone up
-            _ => panic!("inconsistent state in unpark"),
-        }
-
-        // There is a period between when the parked thread sets `state` to
-        // `PARKED` (or last checked `state` in the case of a spurious wake
-        // up) and when it actually waits on `cvar`. If we were to notify
-        // during this period it would be ignored and then when the parked
-        // thread went to sleep it would never wake up. Fortunately, it has
-        // `lock` locked at this stage so we can acquire `lock` to wait until
-        // it is ready to receive the notification.
-        //
-        // Releasing `lock` before the call to `notify_one` means that when the
-        // parked thread wakes it doesn't get woken only to have to wait for us
-        // to release `lock`.
-        drop(self.mutex.lock());
-
-        self.condvar.notify_one()
-    }
-
-    fn shutdown(&self) {
-        self.condvar.notify_all();
-    }
-}
-
-impl Default for ParkThread {
-    fn default() -> Self {
-        Self::new()
-    }
-}
-
-// ===== impl UnparkThread =====
-
-impl Unpark for UnparkThread {
-    fn unpark(&self) {
-        self.inner.unpark();
-    }
-}
-
-use std::future::Future;
-use std::marker::PhantomData;
-use std::mem;
-use std::rc::Rc;
-use std::task::{RawWaker, RawWakerVTable, Waker};
-
-/// Blocks the current thread using a condition variable.
-#[derive(Debug)]
-pub(crate) struct CachedParkThread {
-    _anchor: PhantomData<Rc<()>>,
-}
-
-impl CachedParkThread {
-    /// Create a new `ParkThread` handle for the current thread.
-    ///
-    /// This type cannot be moved to other threads, so it should be created on
-    /// the thread that the caller intends to park.
-    pub(crate) fn new() -> CachedParkThread {
-        CachedParkThread {
-            _anchor: PhantomData,
-        }
-    }
-
-    pub(crate) fn get_unpark(&self) -> Result<UnparkThread, ParkError> {
-        self.with_current(|park_thread| park_thread.unpark())
-    }
-
-    /// Get a reference to the `ParkThread` handle for this thread.
-    fn with_current<F, R>(&self, f: F) -> Result<R, ParkError>
-    where
-        F: FnOnce(&ParkThread) -> R,
-    {
-        CURRENT_PARKER.try_with(|inner| f(inner)).map_err(|_| ())
-    }
-
-    pub(crate) fn block_on<F: Future>(&mut self, f: F) -> Result<F::Output, ParkError> {
-        use std::task::Context;
-        use std::task::Poll::Ready;
-
-        // `get_unpark()` should not return a Result
-        let waker = self.get_unpark()?.into_waker();
-        let mut cx = Context::from_waker(&waker);
-
-        pin!(f);
-
-        loop {
-            if let Ready(v) = crate::coop::budget(|| f.as_mut().poll(&mut cx)) {
-                return Ok(v);
-            }
-
-            self.park()?;
-        }
-    }
-}
-
-impl Park for CachedParkThread {
-    type Unpark = UnparkThread;
-    type Error = ParkError;
-
-    fn unpark(&self) -> Self::Unpark {
-        self.get_unpark().unwrap()
-    }
-
-    fn park(&mut self) -> Result<(), Self::Error> {
-        self.with_current(|park_thread| park_thread.inner.park())?;
-        Ok(())
-    }
-
-    fn park_timeout(&mut self, duration: Duration) -> Result<(), Self::Error> {
-        self.with_current(|park_thread| park_thread.inner.park_timeout(duration))?;
-        Ok(())
-    }
-
-    fn shutdown(&mut self) {
-        let _ = self.with_current(|park_thread| park_thread.inner.shutdown());
-    }
-}
-
-impl UnparkThread {
-    pub(crate) fn into_waker(self) -> Waker {
-        unsafe {
-            let raw = unparker_to_raw_waker(self.inner);
-            Waker::from_raw(raw)
-        }
-    }
-}
-
-impl Inner {
-    #[allow(clippy::wrong_self_convention)]
-    fn into_raw(this: Arc<Inner>) -> *const () {
-        Arc::into_raw(this) as *const ()
-    }
-
-    unsafe fn from_raw(ptr: *const ()) -> Arc<Inner> {
-        Arc::from_raw(ptr as *const Inner)
-    }
-}
-
-unsafe fn unparker_to_raw_waker(unparker: Arc<Inner>) -> RawWaker {
-    RawWaker::new(
-        Inner::into_raw(unparker),
-        &RawWakerVTable::new(clone, wake, wake_by_ref, drop_waker),
-    )
-}
-
-unsafe fn clone(raw: *const ()) -> RawWaker {
-    let unparker = Inner::from_raw(raw);
-
-    // Increment the ref count
-    mem::forget(unparker.clone());
-
-    unparker_to_raw_waker(unparker)
-}
-
-unsafe fn drop_waker(raw: *const ()) {
-    let _ = Inner::from_raw(raw);
-}
-
-unsafe fn wake(raw: *const ()) {
-    let unparker = Inner::from_raw(raw);
-    unparker.unpark();
-}
-
-unsafe fn wake_by_ref(raw: *const ()) {
-    let unparker = Inner::from_raw(raw);
-    unparker.unpark();
-
-    // We don't actually own a reference to the unparker
-    mem::forget(unparker);
-}
diff --git a/vendor/tokio/src/process/mod.rs b/vendor/tokio/src/process/mod.rs
index 96ceb6d8d..d68a68995 100644
--- a/vendor/tokio/src/process/mod.rs
+++ b/vendor/tokio/src/process/mod.rs
@@ -97,13 +97,65 @@
 //! }
 //! ```
 //!
+//! Here is another example using `sort` writing into the child process
+//! standard input, capturing the output of the sorted text.
+//!
+//! ```no_run
+//! use tokio::io::AsyncWriteExt;
+//! use tokio::process::Command;
+//!
+//! use std::process::Stdio;
+//!
+//! #[tokio::main]
+//! async fn main() -> Result<(), Box<dyn std::error::Error>> {
+//!     let mut cmd = Command::new("sort");
+//!
+//!     // Specifying that we want pipe both the output and the input.
+//!     // Similarly to capturing the output, by configuring the pipe
+//!     // to stdin it can now be used as an asynchronous writer.
+//!     cmd.stdout(Stdio::piped());
+//!     cmd.stdin(Stdio::piped());
+//!
+//!     let mut child = cmd.spawn().expect("failed to spawn command");
+//!
+//!     // These are the animals we want to sort
+//!     let animals: &[&str] = &["dog", "bird", "frog", "cat", "fish"];
+//!
+//!     let mut stdin = child
+//!         .stdin
+//!         .take()
+//!         .expect("child did not have a handle to stdin");
+//!
+//!     // Write our animals to the child process
+//!     // Note that the behavior of `sort` is to buffer _all input_ before writing any output.
+//!     // In the general sense, it is recommended to write to the child in a separate task as
+//!     // awaiting its exit (or output) to avoid deadlocks (for example, the child tries to write
+//!     // some output but gets stuck waiting on the parent to read from it, meanwhile the parent
+//!     // is stuck waiting to write its input completely before reading the output).
+//!     stdin
+//!         .write(animals.join("\n").as_bytes())
+//!         .await
+//!         .expect("could not write to stdin");
+//!
+//!     // We drop the handle here which signals EOF to the child process.
+//!     // This tells the child process that it there is no more data on the pipe.
+//!     drop(stdin);
+//!
+//!     let op = child.wait_with_output().await?;
+//!
+//!     // Results should come back in sorted order
+//!     assert_eq!(op.stdout, "bird\ncat\ndog\nfish\nfrog\n".as_bytes());
+//!
+//!     Ok(())
+//! }
+//! ```
+//!
 //! With some coordination, we can also pipe the output of one command into
 //! another.
 //!
 //! ```no_run
 //! use tokio::join;
 //! use tokio::process::Command;
-//! use std::convert::TryInto;
 //! use std::process::Stdio;
 //!
 //! #[tokio::main]
@@ -164,7 +216,7 @@
 //! from being spawned.
 //!
 //! The tokio runtime will, on a best-effort basis, attempt to reap and clean up
-//! any process which it has spawned. No additional guarantees are made with regards
+//! any process which it has spawned. No additional guarantees are made with regard to
 //! how quickly or how often this procedure will take place.
 //!
 //! It is recommended to avoid dropping a [`Child`] process handle before it has been
@@ -192,20 +244,26 @@ mod kill;
 use crate::io::{AsyncRead, AsyncWrite, ReadBuf};
 use crate::process::kill::Kill;
 
-use std::convert::TryInto;
 use std::ffi::OsStr;
 use std::future::Future;
 use std::io;
-#[cfg(unix)]
-use std::os::unix::process::CommandExt;
-#[cfg(windows)]
-use std::os::windows::process::CommandExt;
 use std::path::Path;
 use std::pin::Pin;
 use std::process::{Command as StdCommand, ExitStatus, Output, Stdio};
 use std::task::Context;
 use std::task::Poll;
 
+#[cfg(unix)]
+use std::os::unix::process::CommandExt;
+#[cfg(windows)]
+use std::os::windows::process::CommandExt;
+
+cfg_windows! {
+    use crate::os::windows::io::{AsRawHandle, RawHandle};
+    #[cfg(not(tokio_no_as_fd))]
+    use crate::os::windows::io::{AsHandle, BorrowedHandle};
+}
+
 /// This structure mimics the API of [`std::process::Command`] found in the standard library, but
 /// replaces functions that create a process with an asynchronous variant. The main provided
 /// asynchronous functions are [spawn](Command::spawn), [status](Command::status), and
@@ -223,9 +281,9 @@ pub struct Command {
 
 pub(crate) struct SpawnedChild {
     child: imp::Child,
-    stdin: Option<imp::ChildStdin>,
-    stdout: Option<imp::ChildStdout>,
-    stderr: Option<imp::ChildStderr>,
+    stdin: Option<imp::ChildStdio>,
+    stdout: Option<imp::ChildStdio>,
+    stderr: Option<imp::ChildStdio>,
 }
 
 impl Command {
@@ -254,7 +312,8 @@ impl Command {
     ///
     /// ```no_run
     /// use tokio::process::Command;
-    /// let command = Command::new("sh");
+    /// let mut command = Command::new("sh");
+    /// # let _ = command.output(); // assert borrow checker
     /// ```
     ///
     /// [rust-lang/rust#37519]: https://github.com/rust-lang/rust/issues/37519
@@ -262,21 +321,31 @@ impl Command {
         Self::from(StdCommand::new(program))
     }
 
+    /// Cheaply convert to a `&std::process::Command` for places where the type from the standard
+    /// library is expected.
+    pub fn as_std(&self) -> &StdCommand {
+        &self.std
+    }
+
     /// Adds an argument to pass to the program.
     ///
     /// Only one argument can be passed per use. So instead of:
     ///
     /// ```no_run
-    /// tokio::process::Command::new("sh")
-    ///   .arg("-C /path/to/repo");
+    /// let mut command = tokio::process::Command::new("sh");
+    /// command.arg("-C /path/to/repo");
+    ///
+    /// # let _ = command.output(); // assert borrow checker
     /// ```
     ///
     /// usage would be:
     ///
     /// ```no_run
-    /// tokio::process::Command::new("sh")
-    ///   .arg("-C")
-    ///   .arg("/path/to/repo");
+    /// let mut command = tokio::process::Command::new("sh");
+    /// command.arg("-C");
+    /// command.arg("/path/to/repo");
+    ///
+    /// # let _ = command.output(); // assert borrow checker
     /// ```
     ///
     /// To pass multiple arguments see [`args`].
@@ -288,11 +357,15 @@ impl Command {
     /// Basic usage:
     ///
     /// ```no_run
+    /// # async fn test() { // allow using await
     /// use tokio::process::Command;
     ///
-    /// let command = Command::new("ls")
+    /// let output = Command::new("ls")
     ///         .arg("-l")
-    ///         .arg("-a");
+    ///         .arg("-a")
+    ///         .output().await.unwrap();
+    /// # }
+    ///
     /// ```
     pub fn arg<S: AsRef<OsStr>>(&mut self, arg: S) -> &mut Command {
         self.std.arg(arg);
@@ -310,10 +383,13 @@ impl Command {
     /// Basic usage:
     ///
     /// ```no_run
+    /// # async fn test() { // allow using await
     /// use tokio::process::Command;
     ///
-    /// let command = Command::new("ls")
-    ///         .args(&["-l", "-a"]);
+    /// let output = Command::new("ls")
+    ///         .args(&["-l", "-a"])
+    ///         .output().await.unwrap();
+    /// # }
     /// ```
     pub fn args<I, S>(&mut self, args: I) -> &mut Command
     where
@@ -324,6 +400,22 @@ impl Command {
         self
     }
 
+    /// Append literal text to the command line without any quoting or escaping.
+    ///
+    /// This is useful for passing arguments to `cmd.exe /c`, which doesn't follow
+    /// `CommandLineToArgvW` escaping rules.
+    ///
+    /// **Note**: This is an [unstable API][unstable] but will be stabilised once
+    /// tokio's MSRV is sufficiently new. See [the documentation on
+    /// unstable features][unstable] for details about using unstable features.
+    #[cfg(windows)]
+    #[cfg(tokio_unstable)]
+    #[cfg_attr(docsrs, doc(cfg(all(windows, tokio_unstable))))]
+    pub fn raw_arg<S: AsRef<OsStr>>(&mut self, text_to_append_as_is: S) -> &mut Command {
+        self.std.raw_arg(text_to_append_as_is);
+        self
+    }
+
     /// Inserts or updates an environment variable mapping.
     ///
     /// Note that environment variable names are case-insensitive (but case-preserving) on Windows,
@@ -334,10 +426,13 @@ impl Command {
     /// Basic usage:
     ///
     /// ```no_run
+    /// # async fn test() { // allow using await
     /// use tokio::process::Command;
     ///
-    /// let command = Command::new("ls")
-    ///         .env("PATH", "/bin");
+    /// let output = Command::new("ls")
+    ///         .env("PATH", "/bin")
+    ///         .output().await.unwrap();
+    /// # }
     /// ```
     pub fn env<K, V>(&mut self, key: K, val: V) -> &mut Command
     where
@@ -355,6 +450,7 @@ impl Command {
     /// Basic usage:
     ///
     /// ```no_run
+    /// # async fn test() { // allow using await
     /// use tokio::process::Command;
     /// use std::process::{Stdio};
     /// use std::env;
@@ -365,11 +461,13 @@ impl Command {
     ///         k == "TERM" || k == "TZ" || k == "LANG" || k == "PATH"
     ///     ).collect();
     ///
-    /// let command = Command::new("printenv")
+    /// let output = Command::new("printenv")
     ///         .stdin(Stdio::null())
     ///         .stdout(Stdio::inherit())
     ///         .env_clear()
-    ///         .envs(&filtered_env);
+    ///         .envs(&filtered_env)
+    ///         .output().await.unwrap();
+    /// # }
     /// ```
     pub fn envs<I, K, V>(&mut self, vars: I) -> &mut Command
     where
@@ -388,10 +486,13 @@ impl Command {
     /// Basic usage:
     ///
     /// ```no_run
+    /// # async fn test() { // allow using await
     /// use tokio::process::Command;
     ///
-    /// let command = Command::new("ls")
-    ///         .env_remove("PATH");
+    /// let output = Command::new("ls")
+    ///         .env_remove("PATH")
+    ///         .output().await.unwrap();
+    /// # }
     /// ```
     pub fn env_remove<K: AsRef<OsStr>>(&mut self, key: K) -> &mut Command {
         self.std.env_remove(key);
@@ -405,10 +506,13 @@ impl Command {
     /// Basic usage:
     ///
     /// ```no_run
+    /// # async fn test() { // allow using await
     /// use tokio::process::Command;
     ///
-    /// let command = Command::new("ls")
-    ///         .env_clear();
+    /// let output = Command::new("ls")
+    ///         .env_clear()
+    ///         .output().await.unwrap();
+    /// # }
     /// ```
     pub fn env_clear(&mut self) -> &mut Command {
         self.std.env_clear();
@@ -432,10 +536,13 @@ impl Command {
     /// Basic usage:
     ///
     /// ```no_run
+    /// # async fn test() { // allow using await
     /// use tokio::process::Command;
     ///
-    /// let command = Command::new("ls")
-    ///         .current_dir("/bin");
+    /// let output = Command::new("ls")
+    ///         .current_dir("/bin")
+    ///         .output().await.unwrap();
+    /// # }
     /// ```
     pub fn current_dir<P: AsRef<Path>>(&mut self, dir: P) -> &mut Command {
         self.std.current_dir(dir);
@@ -455,11 +562,14 @@ impl Command {
     /// Basic usage:
     ///
     /// ```no_run
+    /// # async fn test() { // allow using await
     /// use std::process::{Stdio};
     /// use tokio::process::Command;
     ///
-    /// let command = Command::new("ls")
-    ///         .stdin(Stdio::null());
+    /// let output = Command::new("ls")
+    ///         .stdin(Stdio::null())
+    ///         .output().await.unwrap();
+    /// # }
     /// ```
     pub fn stdin<T: Into<Stdio>>(&mut self, cfg: T) -> &mut Command {
         self.std.stdin(cfg);
@@ -479,11 +589,14 @@ impl Command {
     /// Basic usage:
     ///
     /// ```no_run
+    /// # async fn test() { // allow using await
     /// use tokio::process::Command;
     /// use std::process::Stdio;
     ///
-    /// let command = Command::new("ls")
-    ///         .stdout(Stdio::null());
+    /// let output = Command::new("ls")
+    ///         .stdout(Stdio::null())
+    ///         .output().await.unwrap();
+    /// # }
     /// ```
     pub fn stdout<T: Into<Stdio>>(&mut self, cfg: T) -> &mut Command {
         self.std.stdout(cfg);
@@ -503,11 +616,14 @@ impl Command {
     /// Basic usage:
     ///
     /// ```no_run
+    /// # async fn test() { // allow using await
     /// use tokio::process::Command;
     /// use std::process::{Stdio};
     ///
-    /// let command = Command::new("ls")
-    ///         .stderr(Stdio::null());
+    /// let output = Command::new("ls")
+    ///         .stderr(Stdio::null())
+    ///         .output().await.unwrap();
+    /// # }
     /// ```
     pub fn stderr<T: Into<Stdio>>(&mut self, cfg: T) -> &mut Command {
         self.std.stderr(cfg);
@@ -534,7 +650,7 @@ impl Command {
     /// operation, the resulting zombie process cannot be `.await`ed inside of the
     /// destructor to avoid blocking other tasks. The tokio runtime will, on a
     /// best-effort basis, attempt to reap and clean up such processes in the
-    /// background, but makes no additional guarantees are made with regards
+    /// background, but no additional guarantees are made with regard to
     /// how quickly or how often this procedure will take place.
     ///
     /// If stronger guarantees are required, it is recommended to avoid dropping
@@ -545,21 +661,23 @@ impl Command {
         self
     }
 
-    /// Sets the [process creation flags][1] to be passed to `CreateProcess`.
-    ///
-    /// These will always be ORed with `CREATE_UNICODE_ENVIRONMENT`.
-    ///
-    /// [1]: https://msdn.microsoft.com/en-us/library/windows/desktop/ms684863(v=vs.85).aspx
-    #[cfg(windows)]
-    pub fn creation_flags(&mut self, flags: u32) -> &mut Command {
-        self.std.creation_flags(flags);
-        self
+    cfg_windows! {
+        /// Sets the [process creation flags][1] to be passed to `CreateProcess`.
+        ///
+        /// These will always be ORed with `CREATE_UNICODE_ENVIRONMENT`.
+        ///
+        /// [1]: https://msdn.microsoft.com/en-us/library/windows/desktop/ms684863(v=vs.85).aspx
+        pub fn creation_flags(&mut self, flags: u32) -> &mut Command {
+            self.std.creation_flags(flags);
+            self
+        }
     }
 
     /// Sets the child process's user ID. This translates to a
     /// `setuid` call in the child process. Failure in the `setuid`
     /// call will cause the spawn to fail.
     #[cfg(unix)]
+    #[cfg_attr(docsrs, doc(cfg(unix)))]
     pub fn uid(&mut self, id: u32) -> &mut Command {
         self.std.uid(id);
         self
@@ -568,11 +686,26 @@ impl Command {
     /// Similar to `uid` but sets the group ID of the child process. This has
     /// the same semantics as the `uid` field.
     #[cfg(unix)]
+    #[cfg_attr(docsrs, doc(cfg(unix)))]
     pub fn gid(&mut self, id: u32) -> &mut Command {
         self.std.gid(id);
         self
     }
 
+    /// Sets executable argument.
+    ///
+    /// Set the first process argument, `argv[0]`, to something other than the
+    /// default executable path.
+    #[cfg(unix)]
+    #[cfg_attr(docsrs, doc(cfg(unix)))]
+    pub fn arg0<S>(&mut self, arg: S) -> &mut Command
+    where
+        S: AsRef<OsStr>,
+    {
+        self.std.arg0(arg);
+        self
+    }
+
     /// Schedules a closure to be run just before the `exec` function is
     /// invoked.
     ///
@@ -603,6 +736,7 @@ impl Command {
     /// working directory have successfully been changed, so output to these
     /// locations may not appear where intended.
     #[cfg(unix)]
+    #[cfg_attr(docsrs, doc(cfg(unix)))]
     pub unsafe fn pre_exec<F>(&mut self, f: F) -> &mut Command
     where
         F: FnMut() -> io::Result<()> + Send + Sync + 'static,
@@ -611,6 +745,39 @@ impl Command {
         self
     }
 
+    /// Sets the process group ID (PGID) of the child process. Equivalent to a
+    /// setpgid call in the child process, but may be more efficient.
+    ///
+    /// Process groups determine which processes receive signals.
+    ///
+    /// **Note**: This is an [unstable API][unstable] but will be stabilised once
+    /// tokio's MSRV is sufficiently new. See [the documentation on
+    /// unstable features][unstable] for details about using unstable features.
+    ///
+    /// If you want similar behaviour without using this unstable feature you can
+    /// create a [`std::process::Command`] and convert that into a
+    /// [`tokio::process::Command`] using the `From` trait.
+    ///
+    /// [unstable]: crate#unstable-features
+    /// [`tokio::process::Command`]: crate::process::Command
+    ///
+    /// ```no_run
+    /// # async fn test() { // allow using await
+    /// use tokio::process::Command;
+    ///
+    /// let output = Command::new("ls")
+    ///         .process_group(0)
+    ///         .output().await.unwrap();
+    /// # }
+    /// ```
+    #[cfg(unix)]
+    #[cfg(tokio_unstable)]
+    #[cfg_attr(docsrs, doc(cfg(all(unix, tokio_unstable))))]
+    pub fn process_group(&mut self, pgroup: i32) -> &mut Command {
+        self.std.process_group(pgroup);
+        self
+    }
+
     /// Executes the command as a child process, returning a handle to it.
     ///
     /// By default, stdin, stdout and stderr are inherited from the parent.
@@ -663,7 +830,7 @@ impl Command {
     /// from being spawned.
     ///
     /// The tokio runtime will, on a best-effort basis, attempt to reap and clean up
-    /// any process which it has spawned. No additional guarantees are made with regards
+    /// any process which it has spawned. No additional guarantees are made with regard to
     /// how quickly or how often this procedure will take place.
     ///
     /// It is recommended to avoid dropping a [`Child`] process handle before it has been
@@ -844,8 +1011,9 @@ where
     type Output = Result<T, E>;
 
     fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        ready!(crate::trace::trace_leaf(cx));
         // Keep track of task budget
-        let coop = ready!(crate::coop::poll_proceed(cx));
+        let coop = ready!(crate::runtime::coop::poll_proceed(cx));
 
         let ret = Pin::new(&mut self.inner).poll(cx);
 
@@ -934,6 +1102,17 @@ impl Child {
         }
     }
 
+    cfg_windows! {
+        /// Extracts the raw handle of the process associated with this child while
+        /// it is still running. Returns `None` if the child has exited.
+        pub fn raw_handle(&self) -> Option<RawHandle> {
+            match &self.child {
+                FusedChild::Child(c) => Some(c.inner.as_raw_handle()),
+                FusedChild::Done(_) => None,
+            }
+        }
+    }
+
     /// Attempts to force the child to exit, but does not wait for the request
     /// to take effect.
     ///
@@ -1094,19 +1273,26 @@ impl Child {
     pub async fn wait_with_output(mut self) -> io::Result<Output> {
         use crate::future::try_join3;
 
-        async fn read_to_end<A: AsyncRead + Unpin>(io: Option<A>) -> io::Result<Vec<u8>> {
+        async fn read_to_end<A: AsyncRead + Unpin>(io: &mut Option<A>) -> io::Result<Vec<u8>> {
             let mut vec = Vec::new();
-            if let Some(mut io) = io {
-                crate::io::util::read_to_end(&mut io, &mut vec).await?;
+            if let Some(io) = io.as_mut() {
+                crate::io::util::read_to_end(io, &mut vec).await?;
             }
             Ok(vec)
         }
 
-        let stdout_fut = read_to_end(self.stdout.take());
-        let stderr_fut = read_to_end(self.stderr.take());
+        let mut stdout_pipe = self.stdout.take();
+        let mut stderr_pipe = self.stderr.take();
+
+        let stdout_fut = read_to_end(&mut stdout_pipe);
+        let stderr_fut = read_to_end(&mut stderr_pipe);
 
         let (status, stdout, stderr) = try_join3(self.wait(), stdout_fut, stderr_fut).await?;
 
+        // Drop happens after `try_join` due to <https://github.com/tokio-rs/tokio/issues/4309>
+        drop(stdout_pipe);
+        drop(stderr_pipe);
+
         Ok(Output {
             status,
             stdout,
@@ -1121,7 +1307,7 @@ impl Child {
 /// handle of a child process asynchronously.
 #[derive(Debug)]
 pub struct ChildStdin {
-    inner: imp::ChildStdin,
+    inner: imp::ChildStdio,
 }
 
 /// The standard output stream for spawned children.
@@ -1130,7 +1316,7 @@ pub struct ChildStdin {
 /// handle of a child process asynchronously.
 #[derive(Debug)]
 pub struct ChildStdout {
-    inner: imp::ChildStdout,
+    inner: imp::ChildStdio,
 }
 
 /// The standard error stream for spawned children.
@@ -1139,46 +1325,101 @@ pub struct ChildStdout {
 /// handle of a child process asynchronously.
 #[derive(Debug)]
 pub struct ChildStderr {
-    inner: imp::ChildStderr,
+    inner: imp::ChildStdio,
+}
+
+impl ChildStdin {
+    /// Creates an asynchronous `ChildStdin` from a synchronous one.
+    ///
+    /// # Errors
+    ///
+    /// This method may fail if an error is encountered when setting the pipe to
+    /// non-blocking mode, or when registering the pipe with the runtime's IO
+    /// driver.
+    pub fn from_std(inner: std::process::ChildStdin) -> io::Result<Self> {
+        Ok(Self {
+            inner: imp::stdio(inner)?,
+        })
+    }
+}
+
+impl ChildStdout {
+    /// Creates an asynchronous `ChildStdout` from a synchronous one.
+    ///
+    /// # Errors
+    ///
+    /// This method may fail if an error is encountered when setting the pipe to
+    /// non-blocking mode, or when registering the pipe with the runtime's IO
+    /// driver.
+    pub fn from_std(inner: std::process::ChildStdout) -> io::Result<Self> {
+        Ok(Self {
+            inner: imp::stdio(inner)?,
+        })
+    }
+}
+
+impl ChildStderr {
+    /// Creates an asynchronous `ChildStderr` from a synchronous one.
+    ///
+    /// # Errors
+    ///
+    /// This method may fail if an error is encountered when setting the pipe to
+    /// non-blocking mode, or when registering the pipe with the runtime's IO
+    /// driver.
+    pub fn from_std(inner: std::process::ChildStderr) -> io::Result<Self> {
+        Ok(Self {
+            inner: imp::stdio(inner)?,
+        })
+    }
 }
 
 impl AsyncWrite for ChildStdin {
     fn poll_write(
-        self: Pin<&mut Self>,
+        mut self: Pin<&mut Self>,
         cx: &mut Context<'_>,
         buf: &[u8],
     ) -> Poll<io::Result<usize>> {
-        self.inner.poll_write(cx, buf)
+        Pin::new(&mut self.inner).poll_write(cx, buf)
+    }
+
+    fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+        Pin::new(&mut self.inner).poll_flush(cx)
+    }
+
+    fn poll_shutdown(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+        Pin::new(&mut self.inner).poll_shutdown(cx)
     }
 
-    fn poll_flush(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<io::Result<()>> {
-        Poll::Ready(Ok(()))
+    fn poll_write_vectored(
+        mut self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        bufs: &[io::IoSlice<'_>],
+    ) -> Poll<Result<usize, io::Error>> {
+        Pin::new(&mut self.inner).poll_write_vectored(cx, bufs)
     }
 
-    fn poll_shutdown(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<io::Result<()>> {
-        Poll::Ready(Ok(()))
+    fn is_write_vectored(&self) -> bool {
+        self.inner.is_write_vectored()
     }
 }
 
 impl AsyncRead for ChildStdout {
     fn poll_read(
-        self: Pin<&mut Self>,
+        mut self: Pin<&mut Self>,
         cx: &mut Context<'_>,
         buf: &mut ReadBuf<'_>,
     ) -> Poll<io::Result<()>> {
-        // Safety: pipes support reading into uninitialized memory
-        unsafe { self.inner.poll_read(cx, buf) }
+        Pin::new(&mut self.inner).poll_read(cx, buf)
     }
 }
 
 impl AsyncRead for ChildStderr {
     fn poll_read(
-        self: Pin<&mut Self>,
+        mut self: Pin<&mut Self>,
         cx: &mut Context<'_>,
         buf: &mut ReadBuf<'_>,
     ) -> Poll<io::Result<()>> {
-        // Safety: pipes support reading into uninitialized memory
-        unsafe { self.inner.poll_read(cx, buf) }
+        Pin::new(&mut self.inner).poll_read(cx, buf)
     }
 }
 
@@ -1208,6 +1449,8 @@ impl TryInto<Stdio> for ChildStderr {
 
 #[cfg(unix)]
 mod sys {
+    #[cfg(not(tokio_no_as_fd))]
+    use std::os::unix::io::{AsFd, BorrowedFd};
     use std::os::unix::io::{AsRawFd, RawFd};
 
     use super::{ChildStderr, ChildStdin, ChildStdout};
@@ -1218,42 +1461,79 @@ mod sys {
         }
     }
 
+    #[cfg(not(tokio_no_as_fd))]
+    impl AsFd for ChildStdin {
+        fn as_fd(&self) -> BorrowedFd<'_> {
+            unsafe { BorrowedFd::borrow_raw(self.as_raw_fd()) }
+        }
+    }
+
     impl AsRawFd for ChildStdout {
         fn as_raw_fd(&self) -> RawFd {
             self.inner.as_raw_fd()
         }
     }
 
+    #[cfg(not(tokio_no_as_fd))]
+    impl AsFd for ChildStdout {
+        fn as_fd(&self) -> BorrowedFd<'_> {
+            unsafe { BorrowedFd::borrow_raw(self.as_raw_fd()) }
+        }
+    }
+
     impl AsRawFd for ChildStderr {
         fn as_raw_fd(&self) -> RawFd {
             self.inner.as_raw_fd()
         }
     }
-}
 
-#[cfg(windows)]
-mod sys {
-    use std::os::windows::io::{AsRawHandle, RawHandle};
-
-    use super::{ChildStderr, ChildStdin, ChildStdout};
+    #[cfg(not(tokio_no_as_fd))]
+    impl AsFd for ChildStderr {
+        fn as_fd(&self) -> BorrowedFd<'_> {
+            unsafe { BorrowedFd::borrow_raw(self.as_raw_fd()) }
+        }
+    }
+}
 
+cfg_windows! {
     impl AsRawHandle for ChildStdin {
         fn as_raw_handle(&self) -> RawHandle {
             self.inner.as_raw_handle()
         }
     }
 
+    #[cfg(not(tokio_no_as_fd))]
+    impl AsHandle for ChildStdin {
+        fn as_handle(&self) -> BorrowedHandle<'_> {
+            unsafe { BorrowedHandle::borrow_raw(self.as_raw_handle()) }
+        }
+    }
+
     impl AsRawHandle for ChildStdout {
         fn as_raw_handle(&self) -> RawHandle {
             self.inner.as_raw_handle()
         }
     }
 
+    #[cfg(not(tokio_no_as_fd))]
+    impl AsHandle for ChildStdout {
+        fn as_handle(&self) -> BorrowedHandle<'_> {
+            unsafe { BorrowedHandle::borrow_raw(self.as_raw_handle()) }
+        }
+    }
+
     impl AsRawHandle for ChildStderr {
         fn as_raw_handle(&self) -> RawHandle {
             self.inner.as_raw_handle()
         }
     }
+
+    #[cfg(not(tokio_no_as_fd))]
+    impl AsHandle for ChildStderr {
+        fn as_handle(&self) -> BorrowedHandle<'_> {
+            unsafe { BorrowedHandle::borrow_raw(self.as_raw_handle()) }
+        }
+    }
 }
 
 #[cfg(all(test, not(loom)))]
diff --git a/vendor/tokio/src/process/unix/mod.rs b/vendor/tokio/src/process/unix/mod.rs
index fab63dd3d..41857f49c 100644
--- a/vendor/tokio/src/process/unix/mod.rs
+++ b/vendor/tokio/src/process/unix/mod.rs
@@ -1,4 +1,4 @@
-//! Unix handling of child processes
+//! Unix handling of child processes.
 //!
 //! Right now the only "fancy" thing about this is how we implement the
 //! `Future` implementation on `Child` to get the exit status. Unix offers
@@ -21,27 +21,26 @@
 //! processes in general aren't scalable (e.g. millions) so it shouldn't be that
 //! bad in theory...
 
-pub(crate) mod driver;
-
 pub(crate) mod orphan;
 use orphan::{OrphanQueue, OrphanQueueImpl, Wait};
 
 mod reap;
 use reap::Reaper;
 
-use crate::io::PollEvented;
+use crate::io::{AsyncRead, AsyncWrite, PollEvented, ReadBuf};
 use crate::process::kill::Kill;
 use crate::process::SpawnedChild;
-use crate::signal::unix::driver::Handle as SignalHandle;
+use crate::runtime::signal::Handle as SignalHandle;
 use crate::signal::unix::{signal, Signal, SignalKind};
 
 use mio::event::Source;
 use mio::unix::SourceFd;
-use once_cell::sync::Lazy;
 use std::fmt;
 use std::fs::File;
 use std::future::Future;
 use std::io;
+#[cfg(not(tokio_no_as_fd))]
+use std::os::unix::io::{AsFd, BorrowedFd};
 use std::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
 use std::pin::Pin;
 use std::process::{Child as StdChild, ExitStatus, Stdio};
@@ -64,25 +63,41 @@ impl Kill for StdChild {
     }
 }
 
-static ORPHAN_QUEUE: Lazy<OrphanQueueImpl<StdChild>> = Lazy::new(OrphanQueueImpl::new);
+cfg_not_has_const_mutex_new! {
+    fn get_orphan_queue() -> &'static OrphanQueueImpl<StdChild> {
+        use crate::util::once_cell::OnceCell;
+
+        static ORPHAN_QUEUE: OnceCell<OrphanQueueImpl<StdChild>> = OnceCell::new();
+
+        ORPHAN_QUEUE.get(OrphanQueueImpl::new)
+    }
+}
+
+cfg_has_const_mutex_new! {
+    fn get_orphan_queue() -> &'static OrphanQueueImpl<StdChild> {
+        static ORPHAN_QUEUE: OrphanQueueImpl<StdChild> = OrphanQueueImpl::new();
+
+        &ORPHAN_QUEUE
+    }
+}
 
 pub(crate) struct GlobalOrphanQueue;
 
 impl fmt::Debug for GlobalOrphanQueue {
     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
-        ORPHAN_QUEUE.fmt(fmt)
+        get_orphan_queue().fmt(fmt)
     }
 }
 
 impl GlobalOrphanQueue {
-    fn reap_orphans(handle: &SignalHandle) {
-        ORPHAN_QUEUE.reap_orphans(handle)
+    pub(crate) fn reap_orphans(handle: &SignalHandle) {
+        get_orphan_queue().reap_orphans(handle)
     }
 }
 
 impl OrphanQueue<StdChild> for GlobalOrphanQueue {
     fn push_orphan(&self, orphan: StdChild) {
-        ORPHAN_QUEUE.push_orphan(orphan)
+        get_orphan_queue().push_orphan(orphan)
     }
 }
 
@@ -101,9 +116,9 @@ impl fmt::Debug for Child {
 
 pub(crate) fn spawn_child(cmd: &mut std::process::Command) -> io::Result<SpawnedChild> {
     let mut child = cmd.spawn()?;
-    let stdin = stdio(child.stdin.take())?;
-    let stdout = stdio(child.stdout.take())?;
-    let stderr = stdio(child.stderr.take())?;
+    let stdin = child.stdin.take().map(stdio).transpose()?;
+    let stdout = child.stdout.take().map(stdio).transpose()?;
+    let stderr = child.stderr.take().map(stdio).transpose()?;
 
     let signal = signal(SignalKind::child())?;
 
@@ -143,7 +158,7 @@ impl Future for Child {
 
 #[derive(Debug)]
 pub(crate) struct Pipe {
-    // Actually a pipe and not a File. However, we are reusing `File` to get
+    // Actually a pipe is not a File. However, we are reusing `File` to get
     // close on drop. This is a similar trick as `mio`.
     fd: File,
 }
@@ -169,6 +184,10 @@ impl<'a> io::Write for &'a Pipe {
     fn flush(&mut self) -> io::Result<()> {
         (&self.fd).flush()
     }
+
+    fn write_vectored(&mut self, bufs: &[io::IoSlice<'_>]) -> io::Result<usize> {
+        (&self.fd).write_vectored(bufs)
+    }
 }
 
 impl AsRawFd for Pipe {
@@ -177,8 +196,15 @@ impl AsRawFd for Pipe {
     }
 }
 
-pub(crate) fn convert_to_stdio(io: PollEvented<Pipe>) -> io::Result<Stdio> {
-    let mut fd = io.into_inner()?.fd;
+#[cfg(not(tokio_no_as_fd))]
+impl AsFd for Pipe {
+    fn as_fd(&self) -> BorrowedFd<'_> {
+        unsafe { BorrowedFd::borrow_raw(self.as_raw_fd()) }
+    }
+}
+
+pub(crate) fn convert_to_stdio(io: ChildStdio) -> io::Result<Stdio> {
+    let mut fd = io.inner.into_inner()?.fd;
 
     // Ensure that the fd to be inherited is set to *blocking* mode, as this
     // is the default that virtually all programs expect to have. Those
@@ -213,9 +239,69 @@ impl Source for Pipe {
     }
 }
 
-pub(crate) type ChildStdin = PollEvented<Pipe>;
-pub(crate) type ChildStdout = PollEvented<Pipe>;
-pub(crate) type ChildStderr = PollEvented<Pipe>;
+pub(crate) struct ChildStdio {
+    inner: PollEvented<Pipe>,
+}
+
+impl fmt::Debug for ChildStdio {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.inner.fmt(fmt)
+    }
+}
+
+impl AsRawFd for ChildStdio {
+    fn as_raw_fd(&self) -> RawFd {
+        self.inner.as_raw_fd()
+    }
+}
+
+#[cfg(not(tokio_no_as_fd))]
+impl AsFd for ChildStdio {
+    fn as_fd(&self) -> BorrowedFd<'_> {
+        unsafe { BorrowedFd::borrow_raw(self.as_raw_fd()) }
+    }
+}
+
+impl AsyncWrite for ChildStdio {
+    fn poll_write(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &[u8],
+    ) -> Poll<io::Result<usize>> {
+        self.inner.poll_write(cx, buf)
+    }
+
+    fn poll_flush(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+        Poll::Ready(Ok(()))
+    }
+
+    fn poll_shutdown(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+        Poll::Ready(Ok(()))
+    }
+
+    fn poll_write_vectored(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        bufs: &[io::IoSlice<'_>],
+    ) -> Poll<Result<usize, io::Error>> {
+        self.inner.poll_write_vectored(cx, bufs)
+    }
+
+    fn is_write_vectored(&self) -> bool {
+        true
+    }
+}
+
+impl AsyncRead for ChildStdio {
+    fn poll_read(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &mut ReadBuf<'_>,
+    ) -> Poll<io::Result<()>> {
+        // Safety: pipes support reading into uninitialized memory
+        unsafe { self.inner.poll_read(cx, buf) }
+    }
+}
 
 fn set_nonblocking<T: AsRawFd>(fd: &mut T, nonblocking: bool) -> io::Result<()> {
     unsafe {
@@ -240,18 +326,13 @@ fn set_nonblocking<T: AsRawFd>(fd: &mut T, nonblocking: bool) -> io::Result<()>
     Ok(())
 }
 
-fn stdio<T>(option: Option<T>) -> io::Result<Option<PollEvented<Pipe>>>
+pub(super) fn stdio<T>(io: T) -> io::Result<ChildStdio>
 where
     T: IntoRawFd,
 {
-    let io = match option {
-        Some(io) => io,
-        None => return Ok(None),
-    };
-
     // Set the fd to nonblocking before we pass it to the event loop
     let mut pipe = Pipe::from(io);
     set_nonblocking(&mut pipe, true)?;
 
-    Ok(Some(PollEvented::new(pipe)?))
+    PollEvented::new(pipe).map(|inner| ChildStdio { inner })
 }
diff --git a/vendor/tokio/src/process/unix/orphan.rs b/vendor/tokio/src/process/unix/orphan.rs
index 07f0dcfe4..340719603 100644
--- a/vendor/tokio/src/process/unix/orphan.rs
+++ b/vendor/tokio/src/process/unix/orphan.rs
@@ -1,5 +1,5 @@
 use crate::loom::sync::{Mutex, MutexGuard};
-use crate::signal::unix::driver::Handle as SignalHandle;
+use crate::runtime::signal::Handle as SignalHandle;
 use crate::signal::unix::{signal_with_handle, SignalKind};
 use crate::sync::watch;
 use std::io;
@@ -43,10 +43,21 @@ pub(crate) struct OrphanQueueImpl<T> {
 }
 
 impl<T> OrphanQueueImpl<T> {
-    pub(crate) fn new() -> Self {
-        Self {
-            sigchild: Mutex::new(None),
-            queue: Mutex::new(Vec::new()),
+    cfg_not_has_const_mutex_new! {
+        pub(crate) fn new() -> Self {
+            Self {
+                sigchild: Mutex::new(None),
+                queue: Mutex::new(Vec::new()),
+            }
+        }
+    }
+
+    cfg_has_const_mutex_new! {
+        pub(crate) const fn new() -> Self {
+            Self {
+                sigchild: Mutex::const_new(None),
+                queue: Mutex::const_new(Vec::new()),
+            }
         }
     }
 
@@ -87,7 +98,7 @@ impl<T> OrphanQueueImpl<T> {
                         // means that the signal driver isn't running, in
                         // which case there isn't anything we can
                         // register/initialize here, so we can try again later
-                        if let Ok(sigchild) = signal_with_handle(SignalKind::child(), &handle) {
+                        if let Ok(sigchild) = signal_with_handle(SignalKind::child(), handle) {
                             *sigchild_guard = Some(sigchild);
                             drain_orphan_queue(queue);
                         }
@@ -120,8 +131,8 @@ where
 #[cfg(all(test, not(loom)))]
 pub(crate) mod test {
     use super::*;
-    use crate::io::driver::Driver as IoDriver;
-    use crate::signal::unix::driver::{Driver as SignalDriver, Handle as SignalHandle};
+    use crate::runtime::io::Driver as IoDriver;
+    use crate::runtime::signal::{Driver as SignalDriver, Handle as SignalHandle};
     use crate::sync::watch;
     use std::cell::{Cell, RefCell};
     use std::io;
@@ -280,9 +291,11 @@ pub(crate) mod test {
         drop(signal_guard);
     }
 
+    #[cfg_attr(miri, ignore)] // Miri does not support epoll.
     #[test]
     fn does_not_register_signal_if_queue_empty() {
-        let signal_driver = IoDriver::new().and_then(SignalDriver::new).unwrap();
+        let (io_driver, io_handle) = IoDriver::new(1024).unwrap();
+        let signal_driver = SignalDriver::new(io_driver, &io_handle).unwrap();
         let handle = signal_driver.handle();
 
         let orphanage = OrphanQueueImpl::new();
diff --git a/vendor/tokio/src/process/windows.rs b/vendor/tokio/src/process/windows.rs
index 7237525da..eb412cdc5 100644
--- a/vendor/tokio/src/process/windows.rs
+++ b/vendor/tokio/src/process/windows.rs
@@ -15,29 +15,30 @@
 //! `RegisterWaitForSingleObject` and then wait on the other end of the oneshot
 //! from then on out.
 
-use crate::io::PollEvented;
+use crate::io::{blocking::Blocking, AsyncRead, AsyncWrite, ReadBuf};
 use crate::process::kill::Kill;
 use crate::process::SpawnedChild;
 use crate::sync::oneshot;
 
-use mio::windows::NamedPipe;
 use std::fmt;
+use std::fs::File as StdFile;
 use std::future::Future;
 use std::io;
-use std::os::windows::prelude::{AsRawHandle, FromRawHandle, IntoRawHandle};
+use std::os::windows::prelude::{AsRawHandle, IntoRawHandle, RawHandle};
 use std::pin::Pin;
 use std::process::Stdio;
 use std::process::{Child as StdChild, Command as StdCommand, ExitStatus};
-use std::ptr;
-use std::task::Context;
-use std::task::Poll;
-use winapi::shared::minwindef::{DWORD, FALSE};
-use winapi::um::handleapi::{DuplicateHandle, INVALID_HANDLE_VALUE};
-use winapi::um::processthreadsapi::GetCurrentProcess;
-use winapi::um::threadpoollegacyapiset::UnregisterWaitEx;
-use winapi::um::winbase::{RegisterWaitForSingleObject, INFINITE};
-use winapi::um::winnt::{
-    BOOLEAN, DUPLICATE_SAME_ACCESS, HANDLE, PVOID, WT_EXECUTEINWAITTHREAD, WT_EXECUTEONLYONCE,
+use std::sync::Arc;
+use std::task::{Context, Poll};
+
+use windows_sys::{
+    Win32::Foundation::{
+        DuplicateHandle, BOOLEAN, DUPLICATE_SAME_ACCESS, HANDLE, INVALID_HANDLE_VALUE,
+    },
+    Win32::System::Threading::{
+        GetCurrentProcess, RegisterWaitForSingleObject, UnregisterWaitEx, INFINITE,
+        WT_EXECUTEINWAITTHREAD, WT_EXECUTEONLYONCE,
+    },
 };
 
 #[must_use = "futures do nothing unless polled"]
@@ -67,9 +68,9 @@ unsafe impl Send for Waiting {}
 
 pub(crate) fn spawn_child(cmd: &mut StdCommand) -> io::Result<SpawnedChild> {
     let mut child = cmd.spawn()?;
-    let stdin = stdio(child.stdin.take());
-    let stdout = stdio(child.stdout.take());
-    let stderr = stdio(child.stderr.take());
+    let stdin = child.stdin.take().map(stdio).transpose()?;
+    let stdout = child.stdout.take().map(stdio).transpose()?;
+    let stderr = child.stderr.take().map(stdio).transpose()?;
 
     Ok(SpawnedChild {
         child: Child {
@@ -119,11 +120,11 @@ impl Future for Child {
             }
             let (tx, rx) = oneshot::channel();
             let ptr = Box::into_raw(Box::new(Some(tx)));
-            let mut wait_object = ptr::null_mut();
+            let mut wait_object = 0;
             let rc = unsafe {
                 RegisterWaitForSingleObject(
                     &mut wait_object,
-                    inner.child.as_raw_handle(),
+                    inner.child.as_raw_handle() as _,
                     Some(callback),
                     ptr as *mut _,
                     INFINITE,
@@ -144,6 +145,12 @@ impl Future for Child {
     }
 }
 
+impl AsRawHandle for Child {
+    fn as_raw_handle(&self) -> RawHandle {
+        self.child.as_raw_handle()
+    }
+}
+
 impl Drop for Waiting {
     fn drop(&mut self) {
         unsafe {
@@ -156,43 +163,106 @@ impl Drop for Waiting {
     }
 }
 
-unsafe extern "system" fn callback(ptr: PVOID, _timer_fired: BOOLEAN) {
+unsafe extern "system" fn callback(ptr: *mut std::ffi::c_void, _timer_fired: BOOLEAN) {
     let complete = &mut *(ptr as *mut Option<oneshot::Sender<()>>);
     let _ = complete.take().unwrap().send(());
 }
 
-pub(crate) type ChildStdin = PollEvented<NamedPipe>;
-pub(crate) type ChildStdout = PollEvented<NamedPipe>;
-pub(crate) type ChildStderr = PollEvented<NamedPipe>;
+#[derive(Debug)]
+struct ArcFile(Arc<StdFile>);
+
+impl io::Read for ArcFile {
+    fn read(&mut self, bytes: &mut [u8]) -> io::Result<usize> {
+        (&*self.0).read(bytes)
+    }
+}
+
+impl io::Write for ArcFile {
+    fn write(&mut self, bytes: &[u8]) -> io::Result<usize> {
+        (&*self.0).write(bytes)
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        (&*self.0).flush()
+    }
+}
 
-fn stdio<T>(option: Option<T>) -> Option<PollEvented<NamedPipe>>
+#[derive(Debug)]
+pub(crate) struct ChildStdio {
+    // Used for accessing the raw handle, even if the io version is busy
+    raw: Arc<StdFile>,
+    // For doing I/O operations asynchronously
+    io: Blocking<ArcFile>,
+}
+
+impl AsRawHandle for ChildStdio {
+    fn as_raw_handle(&self) -> RawHandle {
+        self.raw.as_raw_handle()
+    }
+}
+
+impl AsyncRead for ChildStdio {
+    fn poll_read(
+        mut self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &mut ReadBuf<'_>,
+    ) -> Poll<io::Result<()>> {
+        Pin::new(&mut self.io).poll_read(cx, buf)
+    }
+}
+
+impl AsyncWrite for ChildStdio {
+    fn poll_write(
+        mut self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &[u8],
+    ) -> Poll<io::Result<usize>> {
+        Pin::new(&mut self.io).poll_write(cx, buf)
+    }
+
+    fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+        Pin::new(&mut self.io).poll_flush(cx)
+    }
+
+    fn poll_shutdown(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+        Pin::new(&mut self.io).poll_shutdown(cx)
+    }
+}
+
+pub(super) fn stdio<T>(io: T) -> io::Result<ChildStdio>
 where
     T: IntoRawHandle,
 {
-    let io = match option {
-        Some(io) => io,
-        None => return None,
-    };
-    let pipe = unsafe { NamedPipe::from_raw_handle(io.into_raw_handle()) };
-    PollEvented::new(pipe).ok()
+    use std::os::windows::prelude::FromRawHandle;
+
+    let raw = Arc::new(unsafe { StdFile::from_raw_handle(io.into_raw_handle()) });
+    let io = Blocking::new(ArcFile(raw.clone()));
+    Ok(ChildStdio { raw, io })
+}
+
+pub(crate) fn convert_to_stdio(child_stdio: ChildStdio) -> io::Result<Stdio> {
+    let ChildStdio { raw, io } = child_stdio;
+    drop(io); // Try to drop the Arc count here
+
+    Arc::try_unwrap(raw)
+        .or_else(|raw| duplicate_handle(&*raw))
+        .map(Stdio::from)
 }
 
-pub(crate) fn convert_to_stdio(io: PollEvented<NamedPipe>) -> io::Result<Stdio> {
-    let named_pipe = io.into_inner()?;
+fn duplicate_handle<T: AsRawHandle>(io: &T) -> io::Result<StdFile> {
+    use std::os::windows::prelude::FromRawHandle;
 
-    // Mio does not implement `IntoRawHandle` for `NamedPipe`, so we'll manually
-    // duplicate the handle here...
     unsafe {
         let mut dup_handle = INVALID_HANDLE_VALUE;
         let cur_proc = GetCurrentProcess();
 
         let status = DuplicateHandle(
             cur_proc,
-            named_pipe.as_raw_handle(),
+            io.as_raw_handle() as _,
             cur_proc,
             &mut dup_handle,
-            0 as DWORD,
-            FALSE,
+            0,
+            0,
             DUPLICATE_SAME_ACCESS,
         );
 
@@ -200,6 +270,6 @@ pub(crate) fn convert_to_stdio(io: PollEvented<NamedPipe>) -> io::Result<Stdio>
             return Err(io::Error::last_os_error());
         }
 
-        Ok(Stdio::from_raw_handle(dup_handle))
+        Ok(StdFile::from_raw_handle(dup_handle as _))
     }
 }
diff --git a/vendor/tokio/src/runtime/basic_scheduler.rs b/vendor/tokio/src/runtime/basic_scheduler.rs
deleted file mode 100644
index 13dfb6973..000000000
--- a/vendor/tokio/src/runtime/basic_scheduler.rs
+++ /dev/null
@@ -1,534 +0,0 @@
-use crate::future::poll_fn;
-use crate::loom::sync::atomic::AtomicBool;
-use crate::loom::sync::Mutex;
-use crate::park::{Park, Unpark};
-use crate::runtime::task::{self, JoinHandle, Schedule, Task};
-use crate::sync::notify::Notify;
-use crate::util::linked_list::{Link, LinkedList};
-use crate::util::{waker_ref, Wake, WakerRef};
-
-use std::cell::RefCell;
-use std::collections::VecDeque;
-use std::fmt;
-use std::future::Future;
-use std::ptr::NonNull;
-use std::sync::atomic::Ordering::{AcqRel, Acquire, Release};
-use std::sync::Arc;
-use std::task::Poll::{Pending, Ready};
-use std::time::Duration;
-
-/// Executes tasks on the current thread
-pub(crate) struct BasicScheduler<P: Park> {
-    /// Inner state guarded by a mutex that is shared
-    /// between all `block_on` calls.
-    inner: Mutex<Option<Inner<P>>>,
-
-    /// Notifier for waking up other threads to steal the
-    /// parker.
-    notify: Notify,
-
-    /// Sendable task spawner
-    spawner: Spawner,
-}
-
-/// The inner scheduler that owns the task queue and the main parker P.
-struct Inner<P: Park> {
-    /// Scheduler run queue
-    ///
-    /// When the scheduler is executed, the queue is removed from `self` and
-    /// moved into `Context`.
-    ///
-    /// This indirection is to allow `BasicScheduler` to be `Send`.
-    tasks: Option<Tasks>,
-
-    /// Sendable task spawner
-    spawner: Spawner,
-
-    /// Current tick
-    tick: u8,
-
-    /// Thread park handle
-    park: P,
-}
-
-#[derive(Clone)]
-pub(crate) struct Spawner {
-    shared: Arc<Shared>,
-}
-
-struct Tasks {
-    /// Collection of all active tasks spawned onto this executor.
-    owned: LinkedList<Task<Arc<Shared>>, <Task<Arc<Shared>> as Link>::Target>,
-
-    /// Local run queue.
-    ///
-    /// Tasks notified from the current thread are pushed into this queue.
-    queue: VecDeque<task::Notified<Arc<Shared>>>,
-}
-
-/// A remote scheduler entry.
-///
-/// These are filled in by remote threads sending instructions to the scheduler.
-enum Entry {
-    /// A remote thread wants to spawn a task.
-    Schedule(task::Notified<Arc<Shared>>),
-    /// A remote thread wants a task to be released by the scheduler. We only
-    /// have access to its header.
-    Release(NonNull<task::Header>),
-}
-
-// Safety: Used correctly, the task header is "thread safe". Ultimately the task
-// is owned by the current thread executor, for which this instruction is being
-// sent.
-unsafe impl Send for Entry {}
-
-/// Scheduler state shared between threads.
-struct Shared {
-    /// Remote run queue. None if the `Runtime` has been dropped.
-    queue: Mutex<Option<VecDeque<Entry>>>,
-
-    /// Unpark the blocked thread.
-    unpark: Box<dyn Unpark>,
-
-    /// Indicates whether the blocked on thread was woken.
-    woken: AtomicBool,
-}
-
-/// Thread-local context.
-struct Context {
-    /// Shared scheduler state
-    shared: Arc<Shared>,
-
-    /// Local queue
-    tasks: RefCell<Tasks>,
-}
-
-/// Initial queue capacity.
-const INITIAL_CAPACITY: usize = 64;
-
-/// Max number of tasks to poll per tick.
-#[cfg(loom)]
-const MAX_TASKS_PER_TICK: usize = 4;
-#[cfg(not(loom))]
-const MAX_TASKS_PER_TICK: usize = 61;
-
-/// How often to check the remote queue first.
-const REMOTE_FIRST_INTERVAL: u8 = 31;
-
-// Tracks the current BasicScheduler.
-scoped_thread_local!(static CURRENT: Context);
-
-impl<P: Park> BasicScheduler<P> {
-    pub(crate) fn new(park: P) -> BasicScheduler<P> {
-        let unpark = Box::new(park.unpark());
-
-        let spawner = Spawner {
-            shared: Arc::new(Shared {
-                queue: Mutex::new(Some(VecDeque::with_capacity(INITIAL_CAPACITY))),
-                unpark: unpark as Box<dyn Unpark>,
-                woken: AtomicBool::new(false),
-            }),
-        };
-
-        let inner = Mutex::new(Some(Inner {
-            tasks: Some(Tasks {
-                owned: LinkedList::new(),
-                queue: VecDeque::with_capacity(INITIAL_CAPACITY),
-            }),
-            spawner: spawner.clone(),
-            tick: 0,
-            park,
-        }));
-
-        BasicScheduler {
-            inner,
-            notify: Notify::new(),
-            spawner,
-        }
-    }
-
-    pub(crate) fn spawner(&self) -> &Spawner {
-        &self.spawner
-    }
-
-    pub(crate) fn block_on<F: Future>(&self, future: F) -> F::Output {
-        pin!(future);
-
-        // Attempt to steal the dedicated parker and block_on the future if we can there,
-        // otherwise, lets select on a notification that the parker is available
-        // or the future is complete.
-        loop {
-            if let Some(inner) = &mut self.take_inner() {
-                return inner.block_on(future);
-            } else {
-                let mut enter = crate::runtime::enter(false);
-
-                let notified = self.notify.notified();
-                pin!(notified);
-
-                if let Some(out) = enter
-                    .block_on(poll_fn(|cx| {
-                        if notified.as_mut().poll(cx).is_ready() {
-                            return Ready(None);
-                        }
-
-                        if let Ready(out) = future.as_mut().poll(cx) {
-                            return Ready(Some(out));
-                        }
-
-                        Pending
-                    }))
-                    .expect("Failed to `Enter::block_on`")
-                {
-                    return out;
-                }
-            }
-        }
-    }
-
-    fn take_inner(&self) -> Option<InnerGuard<'_, P>> {
-        let inner = self.inner.lock().take()?;
-
-        Some(InnerGuard {
-            inner: Some(inner),
-            basic_scheduler: &self,
-        })
-    }
-}
-
-impl<P: Park> Inner<P> {
-    /// Block on the future provided and drive the runtime's driver.
-    fn block_on<F: Future>(&mut self, future: F) -> F::Output {
-        enter(self, |scheduler, context| {
-            let _enter = crate::runtime::enter(false);
-            let waker = scheduler.spawner.waker_ref();
-            let mut cx = std::task::Context::from_waker(&waker);
-            let mut polled = false;
-
-            pin!(future);
-
-            'outer: loop {
-                if scheduler.spawner.was_woken() || !polled {
-                    polled = true;
-                    if let Ready(v) = crate::coop::budget(|| future.as_mut().poll(&mut cx)) {
-                        return v;
-                    }
-                }
-
-                for _ in 0..MAX_TASKS_PER_TICK {
-                    // Get and increment the current tick
-                    let tick = scheduler.tick;
-                    scheduler.tick = scheduler.tick.wrapping_add(1);
-
-                    let entry = if tick % REMOTE_FIRST_INTERVAL == 0 {
-                        scheduler.spawner.pop().or_else(|| {
-                            context
-                                .tasks
-                                .borrow_mut()
-                                .queue
-                                .pop_front()
-                                .map(Entry::Schedule)
-                        })
-                    } else {
-                        context
-                            .tasks
-                            .borrow_mut()
-                            .queue
-                            .pop_front()
-                            .map(Entry::Schedule)
-                            .or_else(|| scheduler.spawner.pop())
-                    };
-
-                    let entry = match entry {
-                        Some(entry) => entry,
-                        None => {
-                            // Park until the thread is signaled
-                            scheduler.park.park().expect("failed to park");
-
-                            // Try polling the `block_on` future next
-                            continue 'outer;
-                        }
-                    };
-
-                    match entry {
-                        Entry::Schedule(task) => crate::coop::budget(|| task.run()),
-                        Entry::Release(ptr) => {
-                            // Safety: the task header is only legally provided
-                            // internally in the header, so we know that it is a
-                            // valid (or in particular *allocated*) header that
-                            // is part of the linked list.
-                            unsafe {
-                                let removed = context.tasks.borrow_mut().owned.remove(ptr);
-
-                                // TODO: This seems like it should hold, because
-                                // there doesn't seem to be an avenue for anyone
-                                // else to fiddle with the owned tasks
-                                // collection *after* a remote thread has marked
-                                // it as released, and at that point, the only
-                                // location at which it can be removed is here
-                                // or in the Drop implementation of the
-                                // scheduler.
-                                debug_assert!(removed.is_some());
-                            }
-                        }
-                    }
-                }
-
-                // Yield to the park, this drives the timer and pulls any pending
-                // I/O events.
-                scheduler
-                    .park
-                    .park_timeout(Duration::from_millis(0))
-                    .expect("failed to park");
-            }
-        })
-    }
-}
-
-/// Enter the scheduler context. This sets the queue and other necessary
-/// scheduler state in the thread-local
-fn enter<F, R, P>(scheduler: &mut Inner<P>, f: F) -> R
-where
-    F: FnOnce(&mut Inner<P>, &Context) -> R,
-    P: Park,
-{
-    // Ensures the run queue is placed back in the `BasicScheduler` instance
-    // once `block_on` returns.`
-    struct Guard<'a, P: Park> {
-        context: Option<Context>,
-        scheduler: &'a mut Inner<P>,
-    }
-
-    impl<P: Park> Drop for Guard<'_, P> {
-        fn drop(&mut self) {
-            let Context { tasks, .. } = self.context.take().expect("context missing");
-            self.scheduler.tasks = Some(tasks.into_inner());
-        }
-    }
-
-    // Remove `tasks` from `self` and place it in a `Context`.
-    let tasks = scheduler.tasks.take().expect("invalid state");
-
-    let guard = Guard {
-        context: Some(Context {
-            shared: scheduler.spawner.shared.clone(),
-            tasks: RefCell::new(tasks),
-        }),
-        scheduler,
-    };
-
-    let context = guard.context.as_ref().unwrap();
-    let scheduler = &mut *guard.scheduler;
-
-    CURRENT.set(context, || f(scheduler, context))
-}
-
-impl<P: Park> Drop for BasicScheduler<P> {
-    fn drop(&mut self) {
-        // Avoid a double panic if we are currently panicking and
-        // the lock may be poisoned.
-
-        let mut inner = match self.inner.lock().take() {
-            Some(inner) => inner,
-            None if std::thread::panicking() => return,
-            None => panic!("Oh no! We never placed the Inner state back, this is a bug!"),
-        };
-
-        enter(&mut inner, |scheduler, context| {
-            // Loop required here to ensure borrow is dropped between iterations
-            #[allow(clippy::while_let_loop)]
-            loop {
-                let task = match context.tasks.borrow_mut().owned.pop_back() {
-                    Some(task) => task,
-                    None => break,
-                };
-
-                task.shutdown();
-            }
-
-            // Drain local queue
-            for task in context.tasks.borrow_mut().queue.drain(..) {
-                task.shutdown();
-            }
-
-            // Drain remote queue and set it to None
-            let mut remote_queue = scheduler.spawner.shared.queue.lock();
-
-            // Using `Option::take` to replace the shared queue with `None`.
-            if let Some(remote_queue) = remote_queue.take() {
-                for entry in remote_queue {
-                    match entry {
-                        Entry::Schedule(task) => {
-                            task.shutdown();
-                        }
-                        Entry::Release(..) => {
-                            // Do nothing, each entry in the linked list was *just*
-                            // dropped by the scheduler above.
-                        }
-                    }
-                }
-            }
-            // By dropping the mutex lock after the full duration of the above loop,
-            // any thread that sees the queue in the `None` state is guaranteed that
-            // the runtime has fully shut down.
-            //
-            // The assert below is unrelated to this mutex.
-            drop(remote_queue);
-
-            assert!(context.tasks.borrow().owned.is_empty());
-        });
-    }
-}
-
-impl<P: Park> fmt::Debug for BasicScheduler<P> {
-    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt.debug_struct("BasicScheduler").finish()
-    }
-}
-
-// ===== impl Spawner =====
-
-impl Spawner {
-    /// Spawns a future onto the thread pool
-    pub(crate) fn spawn<F>(&self, future: F) -> JoinHandle<F::Output>
-    where
-        F: crate::future::Future + Send + 'static,
-        F::Output: Send + 'static,
-    {
-        let (task, handle) = task::joinable(future);
-        self.shared.schedule(task);
-        handle
-    }
-
-    fn pop(&self) -> Option<Entry> {
-        match self.shared.queue.lock().as_mut() {
-            Some(queue) => queue.pop_front(),
-            None => None,
-        }
-    }
-
-    fn waker_ref(&self) -> WakerRef<'_> {
-        // clear the woken bit
-        self.shared.woken.swap(false, AcqRel);
-        waker_ref(&self.shared)
-    }
-
-    fn was_woken(&self) -> bool {
-        self.shared.woken.load(Acquire)
-    }
-}
-
-impl fmt::Debug for Spawner {
-    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt.debug_struct("Spawner").finish()
-    }
-}
-
-// ===== impl Shared =====
-
-impl Schedule for Arc<Shared> {
-    fn bind(task: Task<Self>) -> Arc<Shared> {
-        CURRENT.with(|maybe_cx| {
-            let cx = maybe_cx.expect("scheduler context missing");
-            cx.tasks.borrow_mut().owned.push_front(task);
-            cx.shared.clone()
-        })
-    }
-
-    fn release(&self, task: &Task<Self>) -> Option<Task<Self>> {
-        CURRENT.with(|maybe_cx| {
-            let ptr = NonNull::from(task.header());
-
-            if let Some(cx) = maybe_cx {
-                // safety: the task is inserted in the list in `bind`.
-                unsafe { cx.tasks.borrow_mut().owned.remove(ptr) }
-            } else {
-                // By sending an `Entry::Release` to the runtime, we ask the
-                // runtime to remove this task from the linked list in
-                // `Tasks::owned`.
-                //
-                // If the queue is `None`, then the task was already removed
-                // from that list in the destructor of `BasicScheduler`. We do
-                // not do anything in this case for the same reason that
-                // `Entry::Release` messages are ignored in the remote queue
-                // drain loop of `BasicScheduler`'s destructor.
-                if let Some(queue) = self.queue.lock().as_mut() {
-                    queue.push_back(Entry::Release(ptr));
-                }
-
-                self.unpark.unpark();
-                // Returning `None` here prevents the task plumbing from being
-                // freed. It is then up to the scheduler through the queue we
-                // just added to, or its Drop impl to free the task.
-                None
-            }
-        })
-    }
-
-    fn schedule(&self, task: task::Notified<Self>) {
-        CURRENT.with(|maybe_cx| match maybe_cx {
-            Some(cx) if Arc::ptr_eq(self, &cx.shared) => {
-                cx.tasks.borrow_mut().queue.push_back(task);
-            }
-            _ => {
-                let mut guard = self.queue.lock();
-                if let Some(queue) = guard.as_mut() {
-                    queue.push_back(Entry::Schedule(task));
-                    drop(guard);
-                    self.unpark.unpark();
-                } else {
-                    // The runtime has shut down. We drop the new task
-                    // immediately.
-                    drop(guard);
-                    task.shutdown();
-                }
-            }
-        });
-    }
-}
-
-impl Wake for Shared {
-    fn wake(self: Arc<Self>) {
-        Wake::wake_by_ref(&self)
-    }
-
-    /// Wake by reference
-    fn wake_by_ref(arc_self: &Arc<Self>) {
-        arc_self.woken.store(true, Release);
-        arc_self.unpark.unpark();
-    }
-}
-
-// ===== InnerGuard =====
-
-/// Used to ensure we always place the Inner value
-/// back into its slot in `BasicScheduler`, even if the
-/// future panics.
-struct InnerGuard<'a, P: Park> {
-    inner: Option<Inner<P>>,
-    basic_scheduler: &'a BasicScheduler<P>,
-}
-
-impl<P: Park> InnerGuard<'_, P> {
-    fn block_on<F: Future>(&mut self, future: F) -> F::Output {
-        // The only time inner gets set to `None` is if we have dropped
-        // already so this unwrap is safe.
-        self.inner.as_mut().unwrap().block_on(future)
-    }
-}
-
-impl<P: Park> Drop for InnerGuard<'_, P> {
-    fn drop(&mut self) {
-        if let Some(scheduler) = self.inner.take() {
-            let mut lock = self.basic_scheduler.inner.lock();
-
-            // Replace old scheduler back into the state to allow
-            // other threads to pick it up and drive it.
-            lock.replace(scheduler);
-
-            // Wake up other possible threads that could steal
-            // the dedicated parker P.
-            self.basic_scheduler.notify.notify_one()
-        }
-    }
-}
diff --git a/vendor/tokio/src/runtime/blocking/mod.rs b/vendor/tokio/src/runtime/blocking/mod.rs
index fece3c279..c42924be7 100644
--- a/vendor/tokio/src/runtime/blocking/mod.rs
+++ b/vendor/tokio/src/runtime/blocking/mod.rs
@@ -6,37 +6,21 @@
 mod pool;
 pub(crate) use pool::{spawn_blocking, BlockingPool, Spawner};
 
+cfg_fs! {
+    pub(crate) use pool::spawn_mandatory_blocking;
+}
+
+cfg_trace! {
+    pub(crate) use pool::Mandatory;
+}
+
 mod schedule;
 mod shutdown;
-pub(crate) mod task;
+mod task;
+pub(crate) use task::BlockingTask;
 
 use crate::runtime::Builder;
 
 pub(crate) fn create_blocking_pool(builder: &Builder, thread_cap: usize) -> BlockingPool {
     BlockingPool::new(builder, thread_cap)
 }
-
-/*
-cfg_not_blocking_impl! {
-    use crate::runtime::Builder;
-    use std::time::Duration;
-
-    #[derive(Debug, Clone)]
-    pub(crate) struct BlockingPool {}
-
-    pub(crate) use BlockingPool as Spawner;
-
-    pub(crate) fn create_blocking_pool(_builder: &Builder, _thread_cap: usize) -> BlockingPool {
-        BlockingPool {}
-    }
-
-    impl BlockingPool {
-        pub(crate) fn spawner(&self) -> &BlockingPool {
-            self
-        }
-
-        pub(crate) fn shutdown(&mut self, _duration: Option<Duration>) {
-        }
-    }
-}
-*/
diff --git a/vendor/tokio/src/runtime/blocking/pool.rs b/vendor/tokio/src/runtime/blocking/pool.rs
index b7d725128..a23b0a0d2 100644
--- a/vendor/tokio/src/runtime/blocking/pool.rs
+++ b/vendor/tokio/src/runtime/blocking/pool.rs
@@ -2,16 +2,16 @@
 
 use crate::loom::sync::{Arc, Condvar, Mutex};
 use crate::loom::thread;
-use crate::runtime::blocking::schedule::NoopSchedule;
-use crate::runtime::blocking::shutdown;
+use crate::runtime::blocking::schedule::BlockingSchedule;
+use crate::runtime::blocking::{shutdown, BlockingTask};
 use crate::runtime::builder::ThreadNameFn;
-use crate::runtime::context;
 use crate::runtime::task::{self, JoinHandle};
 use crate::runtime::{Builder, Callback, Handle};
-use crate::util::error::CONTEXT_MISSING_ERROR;
 
 use std::collections::{HashMap, VecDeque};
 use std::fmt;
+use std::io;
+use std::sync::atomic::{AtomicUsize, Ordering};
 use std::time::Duration;
 
 pub(crate) struct BlockingPool {
@@ -24,36 +24,84 @@ pub(crate) struct Spawner {
     inner: Arc<Inner>,
 }
 
+#[derive(Default)]
+pub(crate) struct SpawnerMetrics {
+    num_threads: AtomicUsize,
+    num_idle_threads: AtomicUsize,
+    queue_depth: AtomicUsize,
+}
+
+impl SpawnerMetrics {
+    fn num_threads(&self) -> usize {
+        self.num_threads.load(Ordering::Relaxed)
+    }
+
+    fn num_idle_threads(&self) -> usize {
+        self.num_idle_threads.load(Ordering::Relaxed)
+    }
+
+    cfg_metrics! {
+        fn queue_depth(&self) -> usize {
+            self.queue_depth.load(Ordering::Relaxed)
+        }
+    }
+
+    fn inc_num_threads(&self) {
+        self.num_threads.fetch_add(1, Ordering::Relaxed);
+    }
+
+    fn dec_num_threads(&self) {
+        self.num_threads.fetch_sub(1, Ordering::Relaxed);
+    }
+
+    fn inc_num_idle_threads(&self) {
+        self.num_idle_threads.fetch_add(1, Ordering::Relaxed);
+    }
+
+    fn dec_num_idle_threads(&self) -> usize {
+        self.num_idle_threads.fetch_sub(1, Ordering::Relaxed)
+    }
+
+    fn inc_queue_depth(&self) {
+        self.queue_depth.fetch_add(1, Ordering::Relaxed);
+    }
+
+    fn dec_queue_depth(&self) {
+        self.queue_depth.fetch_sub(1, Ordering::Relaxed);
+    }
+}
+
 struct Inner {
-    /// State shared between worker threads
+    /// State shared between worker threads.
     shared: Mutex<Shared>,
 
     /// Pool threads wait on this.
     condvar: Condvar,
 
-    /// Spawned threads use this name
+    /// Spawned threads use this name.
     thread_name: ThreadNameFn,
 
-    /// Spawned thread stack size
+    /// Spawned thread stack size.
     stack_size: Option<usize>,
 
-    /// Call after a thread starts
+    /// Call after a thread starts.
     after_start: Option<Callback>,
 
-    /// Call before a thread stops
+    /// Call before a thread stops.
     before_stop: Option<Callback>,
 
-    // Maximum number of threads
+    // Maximum number of threads.
     thread_cap: usize,
 
-    // Customizable wait timeout
+    // Customizable wait timeout.
     keep_alive: Duration,
+
+    // Metrics about the pool.
+    metrics: SpawnerMetrics,
 }
 
 struct Shared {
     queue: VecDeque<Task>,
-    num_th: usize,
-    num_idle: u32,
     num_notify: u32,
     shutdown: bool,
     shutdown_tx: Option<shutdown::Sender>,
@@ -67,24 +115,93 @@ struct Shared {
     /// calling shutdown handles joining on these.
     worker_threads: HashMap<usize, thread::JoinHandle<()>>,
     /// This is a counter used to iterate worker_threads in a consistent order (for loom's
-    /// benefit)
+    /// benefit).
     worker_thread_index: usize,
 }
 
-type Task = task::Notified<NoopSchedule>;
+pub(crate) struct Task {
+    task: task::UnownedTask<BlockingSchedule>,
+    mandatory: Mandatory,
+}
+
+#[derive(PartialEq, Eq)]
+pub(crate) enum Mandatory {
+    #[cfg_attr(not(fs), allow(dead_code))]
+    Mandatory,
+    NonMandatory,
+}
+
+pub(crate) enum SpawnError {
+    /// Pool is shutting down and the task was not scheduled
+    ShuttingDown,
+    /// There are no worker threads available to take the task
+    /// and the OS failed to spawn a new one
+    NoThreads(io::Error),
+}
+
+impl From<SpawnError> for io::Error {
+    fn from(e: SpawnError) -> Self {
+        match e {
+            SpawnError::ShuttingDown => {
+                io::Error::new(io::ErrorKind::Other, "blocking pool shutting down")
+            }
+            SpawnError::NoThreads(e) => e,
+        }
+    }
+}
+
+impl Task {
+    pub(crate) fn new(task: task::UnownedTask<BlockingSchedule>, mandatory: Mandatory) -> Task {
+        Task { task, mandatory }
+    }
+
+    fn run(self) {
+        self.task.run();
+    }
+
+    fn shutdown_or_run_if_mandatory(self) {
+        match self.mandatory {
+            Mandatory::NonMandatory => self.task.shutdown(),
+            Mandatory::Mandatory => self.task.run(),
+        }
+    }
+}
 
 const KEEP_ALIVE: Duration = Duration::from_secs(10);
 
-/// Run the provided function on an executor dedicated to blocking operations.
+/// Runs the provided function on an executor dedicated to blocking operations.
+/// Tasks will be scheduled as non-mandatory, meaning they may not get executed
+/// in case of runtime shutdown.
+#[track_caller]
+#[cfg_attr(tokio_wasi, allow(dead_code))]
 pub(crate) fn spawn_blocking<F, R>(func: F) -> JoinHandle<R>
 where
     F: FnOnce() -> R + Send + 'static,
     R: Send + 'static,
 {
-    let rt = context::current().expect(CONTEXT_MISSING_ERROR);
+    let rt = Handle::current();
     rt.spawn_blocking(func)
 }
 
+cfg_fs! {
+    #[cfg_attr(any(
+        all(loom, not(test)), // the function is covered by loom tests
+        test
+    ), allow(dead_code))]
+    /// Runs the provided function on an executor dedicated to blocking
+    /// operations. Tasks will be scheduled as mandatory, meaning they are
+    /// guaranteed to run unless a shutdown is already taking place. In case a
+    /// shutdown is already taking place, `None` will be returned.
+    pub(crate) fn spawn_mandatory_blocking<F, R>(func: F) -> Option<JoinHandle<R>>
+    where
+        F: FnOnce() -> R + Send + 'static,
+        R: Send + 'static,
+    {
+        let rt = Handle::current();
+        rt.inner.blocking_spawner().spawn_mandatory_blocking(&rt, func)
+    }
+}
+
 // ===== impl BlockingPool =====
 
 impl BlockingPool {
@@ -97,8 +214,6 @@ impl BlockingPool {
                 inner: Arc::new(Inner {
                     shared: Mutex::new(Shared {
                         queue: VecDeque::new(),
-                        num_th: 0,
-                        num_idle: 0,
                         num_notify: 0,
                         shutdown: false,
                         shutdown_tx: Some(shutdown_tx),
@@ -113,6 +228,7 @@ impl BlockingPool {
                     before_stop: builder.before_stop.clone(),
                     thread_cap,
                     keep_alive,
+                    metrics: Default::default(),
                 }),
             },
             shutdown_rx,
@@ -172,53 +288,164 @@ impl fmt::Debug for BlockingPool {
 // ===== impl Spawner =====
 
 impl Spawner {
-    pub(crate) fn spawn(&self, task: Task, rt: &Handle) -> Result<(), ()> {
-        let shutdown_tx = {
-            let mut shared = self.inner.shared.lock();
-
-            if shared.shutdown {
-                // Shutdown the task
-                task.shutdown();
-
-                // no need to even push this task; it would never get picked up
-                return Err(());
+    #[track_caller]
+    pub(crate) fn spawn_blocking<F, R>(&self, rt: &Handle, func: F) -> JoinHandle<R>
+    where
+        F: FnOnce() -> R + Send + 'static,
+        R: Send + 'static,
+    {
+        let (join_handle, spawn_result) =
+            if cfg!(debug_assertions) && std::mem::size_of::<F>() > 2048 {
+                self.spawn_blocking_inner(Box::new(func), Mandatory::NonMandatory, None, rt)
+            } else {
+                self.spawn_blocking_inner(func, Mandatory::NonMandatory, None, rt)
+            };
+
+        match spawn_result {
+            Ok(()) => join_handle,
+            // Compat: do not panic here, return the join_handle even though it will never resolve
+            Err(SpawnError::ShuttingDown) => join_handle,
+            Err(SpawnError::NoThreads(e)) => {
+                panic!("OS can't spawn worker thread: {}", e)
             }
+        }
+    }
 
-            shared.queue.push_back(task);
-
-            if shared.num_idle == 0 {
-                // No threads are able to process the task.
-
-                if shared.num_th == self.inner.thread_cap {
-                    // At max number of threads
-                    None
-                } else {
-                    shared.num_th += 1;
-                    assert!(shared.shutdown_tx.is_some());
-                    shared.shutdown_tx.clone()
-                }
+    cfg_fs! {
+        #[track_caller]
+        #[cfg_attr(any(
+            all(loom, not(test)), // the function is covered by loom tests
+            test
+        ), allow(dead_code))]
+        pub(crate) fn spawn_mandatory_blocking<F, R>(&self, rt: &Handle, func: F) -> Option<JoinHandle<R>>
+        where
+            F: FnOnce() -> R + Send + 'static,
+            R: Send + 'static,
+        {
+            let (join_handle, spawn_result) = if cfg!(debug_assertions) && std::mem::size_of::<F>() > 2048 {
+                self.spawn_blocking_inner(
+                    Box::new(func),
+                    Mandatory::Mandatory,
+                    None,
+                    rt,
+                )
+            } else {
+                self.spawn_blocking_inner(
+                    func,
+                    Mandatory::Mandatory,
+                    None,
+                    rt,
+                )
+            };
+
+            if spawn_result.is_ok() {
+                Some(join_handle)
             } else {
-                // Notify an idle worker thread. The notification counter
-                // is used to count the needed amount of notifications
-                // exactly. Thread libraries may generate spurious
-                // wakeups, this counter is used to keep us in a
-                // consistent state.
-                shared.num_idle -= 1;
-                shared.num_notify += 1;
-                self.inner.condvar.notify_one();
                 None
             }
+        }
+    }
+
+    #[track_caller]
+    pub(crate) fn spawn_blocking_inner<F, R>(
+        &self,
+        func: F,
+        is_mandatory: Mandatory,
+        name: Option<&str>,
+        rt: &Handle,
+    ) -> (JoinHandle<R>, Result<(), SpawnError>)
+    where
+        F: FnOnce() -> R + Send + 'static,
+        R: Send + 'static,
+    {
+        let fut = BlockingTask::new(func);
+        let id = task::Id::next();
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let fut = {
+            use tracing::Instrument;
+            let location = std::panic::Location::caller();
+            let span = tracing::trace_span!(
+                target: "tokio::task::blocking",
+                "runtime.spawn",
+                kind = %"blocking",
+                task.name = %name.unwrap_or_default(),
+                task.id = id.as_u64(),
+                "fn" = %std::any::type_name::<F>(),
+                loc.file = location.file(),
+                loc.line = location.line(),
+                loc.col = location.column(),
+            );
+            fut.instrument(span)
         };
 
-        if let Some(shutdown_tx) = shutdown_tx {
-            let mut shared = self.inner.shared.lock();
+        #[cfg(not(all(tokio_unstable, feature = "tracing")))]
+        let _ = name;
 
-            let id = shared.worker_thread_index;
-            shared.worker_thread_index += 1;
+        let (task, handle) = task::unowned(fut, BlockingSchedule::new(rt), id);
 
-            let handle = self.spawn_thread(shutdown_tx, rt, id);
+        let spawned = self.spawn_task(Task::new(task, is_mandatory), rt);
+        (handle, spawned)
+    }
 
-            shared.worker_threads.insert(id, handle);
+    fn spawn_task(&self, task: Task, rt: &Handle) -> Result<(), SpawnError> {
+        let mut shared = self.inner.shared.lock();
+
+        if shared.shutdown {
+            // Shutdown the task: it's fine to shutdown this task (even if
+            // mandatory) because it was scheduled after the shutdown of the
+            // runtime began.
+            task.task.shutdown();
+
+            // no need to even push this task; it would never get picked up
+            return Err(SpawnError::ShuttingDown);
+        }
+
+        shared.queue.push_back(task);
+        self.inner.metrics.inc_queue_depth();
+
+        if self.inner.metrics.num_idle_threads() == 0 {
+            // No threads are able to process the task.
+
+            if self.inner.metrics.num_threads() == self.inner.thread_cap {
+                // At max number of threads
+            } else {
+                assert!(shared.shutdown_tx.is_some());
+                let shutdown_tx = shared.shutdown_tx.clone();
+
+                if let Some(shutdown_tx) = shutdown_tx {
+                    let id = shared.worker_thread_index;
+
+                    match self.spawn_thread(shutdown_tx, rt, id) {
+                        Ok(handle) => {
+                            self.inner.metrics.inc_num_threads();
+                            shared.worker_thread_index += 1;
+                            shared.worker_threads.insert(id, handle);
+                        }
+                        Err(ref e)
+                            if is_temporary_os_thread_error(e)
+                                && self.inner.metrics.num_threads() > 0 =>
+                        {
+                            // OS temporarily failed to spawn a new thread.
+                            // The task will be picked up eventually by a currently
+                            // busy thread.
+                        }
+                        Err(e) => {
+                            // The OS refused to spawn the thread and there is no thread
+                            // to pick up the task that has just been pushed to the queue.
+                            return Err(SpawnError::NoThreads(e));
+                        }
+                    }
+                }
+            }
+        } else {
+            // Notify an idle worker thread. The notification counter
+            // is used to count the needed amount of notifications
+            // exactly. Thread libraries may generate spurious
+            // wakeups, this counter is used to keep us in a
+            // consistent state.
+            self.inner.metrics.dec_num_idle_threads();
+            shared.num_notify += 1;
+            self.inner.condvar.notify_one();
         }
 
         Ok(())
@@ -229,7 +456,7 @@ impl Spawner {
         shutdown_tx: shutdown::Sender,
         rt: &Handle,
         id: usize,
-    ) -> thread::JoinHandle<()> {
+    ) -> std::io::Result<thread::JoinHandle<()>> {
         let mut builder = thread::Builder::new().name((self.inner.thread_name)());
 
         if let Some(stack_size) = self.inner.stack_size {
@@ -238,17 +465,37 @@ impl Spawner {
 
         let rt = rt.clone();
 
-        builder
-            .spawn(move || {
-                // Only the reference should be moved into the closure
-                let _enter = crate::runtime::context::enter(rt.clone());
-                rt.blocking_spawner.inner.run(id);
-                drop(shutdown_tx);
-            })
-            .unwrap()
+        builder.spawn(move || {
+            // Only the reference should be moved into the closure
+            let _enter = rt.enter();
+            rt.inner.blocking_spawner().inner.run(id);
+            drop(shutdown_tx);
+        })
+    }
+}
+
+cfg_metrics! {
+    impl Spawner {
+        pub(crate) fn num_threads(&self) -> usize {
+            self.inner.metrics.num_threads()
+        }
+
+        pub(crate) fn num_idle_threads(&self) -> usize {
+            self.inner.metrics.num_idle_threads()
+        }
+
+        pub(crate) fn queue_depth(&self) -> usize {
+            self.inner.metrics.queue_depth()
+        }
     }
 }
 
+// Tells whether the error when spawning a thread is temporary.
+#[inline]
+fn is_temporary_os_thread_error(error: &std::io::Error) -> bool {
+    matches!(error.kind(), std::io::ErrorKind::WouldBlock)
+}
+
 impl Inner {
     fn run(&self, worker_thread_id: usize) {
         if let Some(f) = &self.after_start {
@@ -261,6 +508,7 @@ impl Inner {
         'main: loop {
             // BUSY
             while let Some(task) = shared.queue.pop_front() {
+                self.metrics.dec_queue_depth();
                 drop(shared);
                 task.run();
 
@@ -268,7 +516,7 @@ impl Inner {
             }
 
             // IDLE
-            shared.num_idle += 1;
+            self.metrics.inc_num_idle_threads();
 
             while !shared.shutdown {
                 let lock_result = self.condvar.wait_timeout(shared, self.keep_alive).unwrap();
@@ -302,8 +550,10 @@ impl Inner {
             if shared.shutdown {
                 // Drain the queue
                 while let Some(task) = shared.queue.pop_front() {
+                    self.metrics.dec_queue_depth();
                     drop(shared);
-                    task.shutdown();
+
+                    task.shutdown_or_run_if_mandatory();
 
                     shared = self.shared.lock();
                 }
@@ -311,7 +561,7 @@ impl Inner {
                 // Work was produced, and we "took" it (by decrementing num_notify).
                 // This means that num_idle was decremented once for our wakeup.
                 // But, since we are exiting, we need to "undo" that, as we'll stay idle.
-                shared.num_idle += 1;
+                self.metrics.inc_num_idle_threads();
                 // NOTE: Technically we should also do num_notify++ and notify again,
                 // but since we're shutting down anyway, that won't be necessary.
                 break;
@@ -319,17 +569,17 @@ impl Inner {
         }
 
         // Thread exit
-        shared.num_th -= 1;
+        self.metrics.dec_num_threads();
 
         // num_idle should now be tracked exactly, panic
         // with a descriptive message if it is not the
         // case.
-        shared.num_idle = shared
-            .num_idle
-            .checked_sub(1)
-            .expect("num_idle underflowed on thread exit");
+        let prev_idle = self.metrics.dec_num_idle_threads();
+        if prev_idle < self.metrics.num_idle_threads() {
+            panic!("num_idle_threads underflowed on thread exit")
+        }
 
-        if shared.shutdown && shared.num_th == 0 {
+        if shared.shutdown && self.metrics.num_threads() == 0 {
             self.condvar.notify_one();
         }
 
diff --git a/vendor/tokio/src/runtime/blocking/schedule.rs b/vendor/tokio/src/runtime/blocking/schedule.rs
index 4e044ab29..edf775be8 100644
--- a/vendor/tokio/src/runtime/blocking/schedule.rs
+++ b/vendor/tokio/src/runtime/blocking/schedule.rs
@@ -1,20 +1,52 @@
+#[cfg(feature = "test-util")]
+use crate::runtime::scheduler;
 use crate::runtime::task::{self, Task};
+use crate::runtime::Handle;
 
-/// `task::Schedule` implementation that does nothing. This is unique to the
-/// blocking scheduler as tasks scheduled are not really futures but blocking
-/// operations.
+/// `task::Schedule` implementation that does nothing (except some bookkeeping
+/// in test-util builds). This is unique to the blocking scheduler as tasks
+/// scheduled are not really futures but blocking operations.
 ///
 /// We avoid storing the task by forgetting it in `bind` and re-materializing it
-/// in `release.
-pub(crate) struct NoopSchedule;
+/// in `release`.
+pub(crate) struct BlockingSchedule {
+    #[cfg(feature = "test-util")]
+    handle: Handle,
+}
 
-impl task::Schedule for NoopSchedule {
-    fn bind(_task: Task<Self>) -> NoopSchedule {
-        // Do nothing w/ the task
-        NoopSchedule
+impl BlockingSchedule {
+    #[cfg_attr(not(feature = "test-util"), allow(unused_variables))]
+    pub(crate) fn new(handle: &Handle) -> Self {
+        #[cfg(feature = "test-util")]
+        {
+            match &handle.inner {
+                scheduler::Handle::CurrentThread(handle) => {
+                    handle.driver.clock.inhibit_auto_advance();
+                }
+                #[cfg(all(feature = "rt-multi-thread", not(tokio_wasi)))]
+                scheduler::Handle::MultiThread(_) => {}
+            }
+        }
+        BlockingSchedule {
+            #[cfg(feature = "test-util")]
+            handle: handle.clone(),
+        }
     }
+}
 
+impl task::Schedule for BlockingSchedule {
     fn release(&self, _task: &Task<Self>) -> Option<Task<Self>> {
+        #[cfg(feature = "test-util")]
+        {
+            match &self.handle.inner {
+                scheduler::Handle::CurrentThread(handle) => {
+                    handle.driver.clock.allow_auto_advance();
+                    handle.driver.unpark();
+                }
+                #[cfg(all(feature = "rt-multi-thread", not(tokio_wasi)))]
+                scheduler::Handle::MultiThread(_) => {}
+            }
+        }
         None
     }
 
diff --git a/vendor/tokio/src/runtime/blocking/shutdown.rs b/vendor/tokio/src/runtime/blocking/shutdown.rs
index 0cf22859b..fe5abae07 100644
--- a/vendor/tokio/src/runtime/blocking/shutdown.rs
+++ b/vendor/tokio/src/runtime/blocking/shutdown.rs
@@ -10,7 +10,7 @@ use std::time::Duration;
 
 #[derive(Debug, Clone)]
 pub(super) struct Sender {
-    tx: Arc<oneshot::Sender<()>>,
+    _tx: Arc<oneshot::Sender<()>>,
 }
 
 #[derive(Debug)]
@@ -20,7 +20,7 @@ pub(super) struct Receiver {
 
 pub(super) fn channel() -> (Sender, Receiver) {
     let (tx, rx) = oneshot::channel();
-    let tx = Sender { tx: Arc::new(tx) };
+    let tx = Sender { _tx: Arc::new(tx) };
     let rx = Receiver { rx };
 
     (tx, rx)
@@ -35,13 +35,13 @@ impl Receiver {
     ///
     /// If the timeout has elapsed, it returns `false`, otherwise it returns `true`.
     pub(crate) fn wait(&mut self, timeout: Option<Duration>) -> bool {
-        use crate::runtime::enter::try_enter;
+        use crate::runtime::context::try_enter_blocking_region;
 
         if timeout == Some(Duration::from_nanos(0)) {
             return false;
         }
 
-        let mut e = match try_enter(false) {
+        let mut e = match try_enter_blocking_region() {
             Some(enter) => enter,
             _ => {
                 if std::thread::panicking() {
diff --git a/vendor/tokio/src/runtime/blocking/task.rs b/vendor/tokio/src/runtime/blocking/task.rs
index ee2d8d6d6..c44617540 100644
--- a/vendor/tokio/src/runtime/blocking/task.rs
+++ b/vendor/tokio/src/runtime/blocking/task.rs
@@ -2,13 +2,13 @@ use std::future::Future;
 use std::pin::Pin;
 use std::task::{Context, Poll};
 
-/// Converts a function to a future that completes on poll
+/// Converts a function to a future that completes on poll.
 pub(crate) struct BlockingTask<T> {
     func: Option<T>,
 }
 
 impl<T> BlockingTask<T> {
-    /// Initializes a new blocking task from the given function
+    /// Initializes a new blocking task from the given function.
     pub(crate) fn new(func: T) -> BlockingTask<T> {
         BlockingTask { func: Some(func) }
     }
@@ -37,7 +37,7 @@ where
         // currently goes through Task::poll(), and so is subject to budgeting. That isn't really
         // what we want; a blocking task may itself want to run tasks (it might be a Worker!), so
         // we want it to start without any budgeting.
-        crate::coop::stop();
+        crate::runtime::coop::stop();
 
         Poll::Ready(func())
     }
diff --git a/vendor/tokio/src/runtime/builder.rs b/vendor/tokio/src/runtime/builder.rs
index 51bf8c843..af9e0e172 100644
--- a/vendor/tokio/src/runtime/builder.rs
+++ b/vendor/tokio/src/runtime/builder.rs
@@ -1,5 +1,6 @@
 use crate::runtime::handle::Handle;
-use crate::runtime::{blocking, driver, Callback, Runtime, Spawner};
+use crate::runtime::{blocking, driver, Callback, HistogramBuilder, Runtime};
+use crate::util::rand::{RngSeed, RngSeedGenerator};
 
 use std::fmt;
 use std::io;
@@ -43,6 +44,7 @@ pub struct Builder {
 
     /// Whether or not to enable the I/O driver
     enable_io: bool,
+    nevents: usize,
 
     /// Whether or not to enable the time driver
     enable_time: bool,
@@ -70,15 +72,132 @@ pub struct Builder {
     /// To run before each worker thread stops
     pub(super) before_stop: Option<Callback>,
 
+    /// To run before each worker thread is parked.
+    pub(super) before_park: Option<Callback>,
+
+    /// To run after each thread is unparked.
+    pub(super) after_unpark: Option<Callback>,
+
     /// Customizable keep alive timeout for BlockingPool
     pub(super) keep_alive: Option<Duration>,
+
+    /// How many ticks before pulling a task from the global/remote queue?
+    ///
+    /// When `None`, the value is unspecified and behavior details are left to
+    /// the scheduler. Each scheduler flavor could choose to either pick its own
+    /// default value or use some other strategy to decide when to poll from the
+    /// global queue. For example, the multi-threaded scheduler uses a
+    /// self-tuning strategy based on mean task poll times.
+    pub(super) global_queue_interval: Option<u32>,
+
+    /// How many ticks before yielding to the driver for timer and I/O events?
+    pub(super) event_interval: u32,
+
+    /// When true, the multi-threade scheduler LIFO slot should not be used.
+    ///
+    /// This option should only be exposed as unstable.
+    pub(super) disable_lifo_slot: bool,
+
+    /// Specify a random number generator seed to provide deterministic results
+    pub(super) seed_generator: RngSeedGenerator,
+
+    /// When true, enables task poll count histogram instrumentation.
+    pub(super) metrics_poll_count_histogram_enable: bool,
+
+    /// Configures the task poll count histogram
+    pub(super) metrics_poll_count_histogram: HistogramBuilder,
+
+    #[cfg(tokio_unstable)]
+    pub(super) unhandled_panic: UnhandledPanic,
+}
+
+cfg_unstable! {
+    /// How the runtime should respond to unhandled panics.
+    ///
+    /// Instances of `UnhandledPanic` are passed to `Builder::unhandled_panic`
+    /// to configure the runtime behavior when a spawned task panics.
+    ///
+    /// See [`Builder::unhandled_panic`] for more details.
+    #[derive(Debug, Clone)]
+    #[non_exhaustive]
+    pub enum UnhandledPanic {
+        /// The runtime should ignore panics on spawned tasks.
+        ///
+        /// The panic is forwarded to the task's [`JoinHandle`] and all spawned
+        /// tasks continue running normally.
+        ///
+        /// This is the default behavior.
+        ///
+        /// # Examples
+        ///
+        /// ```
+        /// use tokio::runtime::{self, UnhandledPanic};
+        ///
+        /// # pub fn main() {
+        /// let rt = runtime::Builder::new_current_thread()
+        ///     .unhandled_panic(UnhandledPanic::Ignore)
+        ///     .build()
+        ///     .unwrap();
+        ///
+        /// let task1 = rt.spawn(async { panic!("boom"); });
+        /// let task2 = rt.spawn(async {
+        ///     // This task completes normally
+        ///     "done"
+        /// });
+        ///
+        /// rt.block_on(async {
+        ///     // The panic on the first task is forwarded to the `JoinHandle`
+        ///     assert!(task1.await.is_err());
+        ///
+        ///     // The second task completes normally
+        ///     assert!(task2.await.is_ok());
+        /// })
+        /// # }
+        /// ```
+        ///
+        /// [`JoinHandle`]: struct@crate::task::JoinHandle
+        Ignore,
+
+        /// The runtime should immediately shutdown if a spawned task panics.
+        ///
+        /// The runtime will immediately shutdown even if the panicked task's
+        /// [`JoinHandle`] is still available. All further spawned tasks will be
+        /// immediately dropped and call to [`Runtime::block_on`] will panic.
+        ///
+        /// # Examples
+        ///
+        /// ```should_panic
+        /// use tokio::runtime::{self, UnhandledPanic};
+        ///
+        /// # pub fn main() {
+        /// let rt = runtime::Builder::new_current_thread()
+        ///     .unhandled_panic(UnhandledPanic::ShutdownRuntime)
+        ///     .build()
+        ///     .unwrap();
+        ///
+        /// rt.spawn(async { panic!("boom"); });
+        /// rt.spawn(async {
+        ///     // This task never completes.
+        /// });
+        ///
+        /// rt.block_on(async {
+        ///     // Do some work
+        /// # loop { tokio::task::yield_now().await; }
+        /// })
+        /// # }
+        /// ```
+        ///
+        /// [`JoinHandle`]: struct@crate::task::JoinHandle
+        ShutdownRuntime,
+    }
 }
 
 pub(crate) type ThreadNameFn = std::sync::Arc<dyn Fn() -> String + Send + Sync + 'static>;
 
+#[derive(Clone, Copy)]
 pub(crate) enum Kind {
     CurrentThread,
-    #[cfg(feature = "rt-multi-thread")]
+    #[cfg(all(feature = "rt-multi-thread", not(tokio_wasi)))]
     MultiThread,
 }
 
@@ -92,28 +211,38 @@ impl Builder {
     ///
     /// [`LocalSet`]: crate::task::LocalSet
     pub fn new_current_thread() -> Builder {
-        Builder::new(Kind::CurrentThread)
+        #[cfg(loom)]
+        const EVENT_INTERVAL: u32 = 4;
+        // The number `61` is fairly arbitrary. I believe this value was copied from golang.
+        #[cfg(not(loom))]
+        const EVENT_INTERVAL: u32 = 61;
+
+        Builder::new(Kind::CurrentThread, EVENT_INTERVAL)
     }
 
-    /// Returns a new builder with the multi thread scheduler selected.
-    ///
-    /// Configuration methods can be chained on the return value.
-    #[cfg(feature = "rt-multi-thread")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "rt-multi-thread")))]
-    pub fn new_multi_thread() -> Builder {
-        Builder::new(Kind::MultiThread)
+    cfg_not_wasi! {
+        /// Returns a new builder with the multi thread scheduler selected.
+        ///
+        /// Configuration methods can be chained on the return value.
+        #[cfg(feature = "rt-multi-thread")]
+        #[cfg_attr(docsrs, doc(cfg(feature = "rt-multi-thread")))]
+        pub fn new_multi_thread() -> Builder {
+            // The number `61` is fairly arbitrary. I believe this value was copied from golang.
+            Builder::new(Kind::MultiThread, 61)
+        }
     }
 
     /// Returns a new runtime builder initialized with default configuration
     /// values.
     ///
     /// Configuration methods can be chained on the return value.
-    pub(crate) fn new(kind: Kind) -> Builder {
+    pub(crate) fn new(kind: Kind, event_interval: u32) -> Builder {
         Builder {
             kind,
 
             // I/O defaults to "off"
             enable_io: false,
+            nevents: 1024,
 
             // Time defaults to "off"
             enable_time: false,
@@ -121,6 +250,7 @@ impl Builder {
             // The clock starts not-paused
             start_paused: false,
 
+            // Read from environment variable first in multi-threaded mode.
             // Default to lazy auto-detection (one thread per CPU core)
             worker_threads: None,
 
@@ -135,8 +265,26 @@ impl Builder {
             // No worker thread callbacks
             after_start: None,
             before_stop: None,
+            before_park: None,
+            after_unpark: None,
 
             keep_alive: None,
+
+            // Defaults for these values depend on the scheduler kind, so we get them
+            // as parameters.
+            global_queue_interval: None,
+            event_interval,
+
+            seed_generator: RngSeedGenerator::new(RngSeed::new()),
+
+            #[cfg(tokio_unstable)]
+            unhandled_panic: UnhandledPanic::Ignore,
+
+            metrics_poll_count_histogram_enable: false,
+
+            metrics_poll_count_histogram: Default::default(),
+
+            disable_lifo_slot: false,
         }
     }
 
@@ -157,7 +305,11 @@ impl Builder {
     ///     .unwrap();
     /// ```
     pub fn enable_all(&mut self) -> &mut Self {
-        #[cfg(any(feature = "net", feature = "process", all(unix, feature = "signal")))]
+        #[cfg(any(
+            feature = "net",
+            all(unix, feature = "process"),
+            all(unix, feature = "signal")
+        ))]
         self.enable_io();
         #[cfg(feature = "time")]
         self.enable_time();
@@ -170,15 +322,13 @@ impl Builder {
     /// This can be any number above 0 though it is advised to keep this value
     /// on the smaller side.
     ///
+    /// This will override the value read from environment variable `TOKIO_WORKER_THREADS`.
+    ///
     /// # Default
     ///
     /// The default value is the number of cores available to the system.
     ///
-    /// # Panic
-    ///
-    /// When using the `current_thread` runtime this method will panic, since
-    /// those variants do not allow setting worker thread counts.
-    ///
+    /// When using the `current_thread` runtime this method has no effect.
     ///
     /// # Examples
     ///
@@ -211,9 +361,10 @@ impl Builder {
     /// rt.block_on(async move {});
     /// ```
     ///
-    /// # Panic
+    /// # Panics
     ///
     /// This will panic if `val` is not larger than `0`.
+    #[track_caller]
     pub fn worker_threads(&mut self, val: usize) -> &mut Self {
         assert!(val > 0, "Worker threads cannot be set to 0");
         self.worker_threads = Some(val);
@@ -229,7 +380,7 @@ impl Builder {
     ///
     /// The default value is 512.
     ///
-    /// # Panic
+    /// # Panics
     ///
     /// This will panic if `val` is not larger than `0`.
     ///
@@ -241,6 +392,7 @@ impl Builder {
     /// [`spawn_blocking`]: fn@crate::task::spawn_blocking
     /// [`worker_threads`]: Self::worker_threads
     /// [`thread_keep_alive`]: Self::thread_keep_alive
+    #[track_caller]
     #[cfg_attr(docsrs, doc(alias = "max_threads"))]
     pub fn max_blocking_threads(&mut self, val: usize) -> &mut Self {
         assert!(val > 0, "Max blocking threads cannot be set to 0");
@@ -278,7 +430,6 @@ impl Builder {
     /// ```
     /// # use tokio::runtime;
     /// # use std::sync::atomic::{AtomicUsize, Ordering};
-    ///
     /// # pub fn main() {
     /// let rt = runtime::Builder::new_multi_thread()
     ///     .thread_name_fn(|| {
@@ -330,7 +481,6 @@ impl Builder {
     ///
     /// ```
     /// # use tokio::runtime;
-    ///
     /// # pub fn main() {
     /// let runtime = runtime::Builder::new_multi_thread()
     ///     .on_thread_start(|| {
@@ -356,7 +506,6 @@ impl Builder {
     ///
     /// ```
     /// # use tokio::runtime;
-    ///
     /// # pub fn main() {
     /// let runtime = runtime::Builder::new_multi_thread()
     ///     .on_thread_stop(|| {
@@ -374,6 +523,119 @@ impl Builder {
         self
     }
 
+    /// Executes function `f` just before a thread is parked (goes idle).
+    /// `f` is called within the Tokio context, so functions like [`tokio::spawn`](crate::spawn)
+    /// can be called, and may result in this thread being unparked immediately.
+    ///
+    /// This can be used to start work only when the executor is idle, or for bookkeeping
+    /// and monitoring purposes.
+    ///
+    /// Note: There can only be one park callback for a runtime; calling this function
+    /// more than once replaces the last callback defined, rather than adding to it.
+    ///
+    /// # Examples
+    ///
+    /// ## Multithreaded executor
+    /// ```
+    /// # use std::sync::Arc;
+    /// # use std::sync::atomic::{AtomicBool, Ordering};
+    /// # use tokio::runtime;
+    /// # use tokio::sync::Barrier;
+    /// # pub fn main() {
+    /// let once = AtomicBool::new(true);
+    /// let barrier = Arc::new(Barrier::new(2));
+    ///
+    /// let runtime = runtime::Builder::new_multi_thread()
+    ///     .worker_threads(1)
+    ///     .on_thread_park({
+    ///         let barrier = barrier.clone();
+    ///         move || {
+    ///             let barrier = barrier.clone();
+    ///             if once.swap(false, Ordering::Relaxed) {
+    ///                 tokio::spawn(async move { barrier.wait().await; });
+    ///            }
+    ///         }
+    ///     })
+    ///     .build()
+    ///     .unwrap();
+    ///
+    /// runtime.block_on(async {
+    ///    barrier.wait().await;
+    /// })
+    /// # }
+    /// ```
+    /// ## Current thread executor
+    /// ```
+    /// # use std::sync::Arc;
+    /// # use std::sync::atomic::{AtomicBool, Ordering};
+    /// # use tokio::runtime;
+    /// # use tokio::sync::Barrier;
+    /// # pub fn main() {
+    /// let once = AtomicBool::new(true);
+    /// let barrier = Arc::new(Barrier::new(2));
+    ///
+    /// let runtime = runtime::Builder::new_current_thread()
+    ///     .on_thread_park({
+    ///         let barrier = barrier.clone();
+    ///         move || {
+    ///             let barrier = barrier.clone();
+    ///             if once.swap(false, Ordering::Relaxed) {
+    ///                 tokio::spawn(async move { barrier.wait().await; });
+    ///            }
+    ///         }
+    ///     })
+    ///     .build()
+    ///     .unwrap();
+    ///
+    /// runtime.block_on(async {
+    ///    barrier.wait().await;
+    /// })
+    /// # }
+    /// ```
+    #[cfg(not(loom))]
+    pub fn on_thread_park<F>(&mut self, f: F) -> &mut Self
+    where
+        F: Fn() + Send + Sync + 'static,
+    {
+        self.before_park = Some(std::sync::Arc::new(f));
+        self
+    }
+
+    /// Executes function `f` just after a thread unparks (starts executing tasks).
+    ///
+    /// This is intended for bookkeeping and monitoring use cases; note that work
+    /// in this callback will increase latencies when the application has allowed one or
+    /// more runtime threads to go idle.
+    ///
+    /// Note: There can only be one unpark callback for a runtime; calling this function
+    /// more than once replaces the last callback defined, rather than adding to it.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use tokio::runtime;
+    /// # pub fn main() {
+    /// let runtime = runtime::Builder::new_multi_thread()
+    ///     .on_thread_unpark(|| {
+    ///         println!("thread unparking");
+    ///     })
+    ///     .build();
+    ///
+    /// runtime.unwrap().block_on(async {
+    ///    tokio::task::yield_now().await;
+    ///    println!("Hello from Tokio!");
+    /// })
+    /// # }
+    /// ```
+    #[cfg(not(loom))]
+    pub fn on_thread_unpark<F>(&mut self, f: F) -> &mut Self
+    where
+        F: Fn() + Send + Sync + 'static,
+    {
+        self.after_unpark = Some(std::sync::Arc::new(f));
+        self
+    }
+
     /// Creates the configured `Runtime`.
     ///
     /// The returned `Runtime` instance is ready to spawn tasks.
@@ -391,8 +653,8 @@ impl Builder {
     /// ```
     pub fn build(&mut self) -> io::Result<Runtime> {
         match &self.kind {
-            Kind::CurrentThread => self.build_basic_runtime(),
-            #[cfg(feature = "rt-multi-thread")]
+            Kind::CurrentThread => self.build_current_thread_runtime(),
+            #[cfg(all(feature = "rt-multi-thread", not(tokio_wasi)))]
             Kind::MultiThread => self.build_threaded_runtime(),
         }
     }
@@ -401,12 +663,13 @@ impl Builder {
         driver::Cfg {
             enable_pause_time: match self.kind {
                 Kind::CurrentThread => true,
-                #[cfg(feature = "rt-multi-thread")]
+                #[cfg(all(feature = "rt-multi-thread", not(tokio_wasi)))]
                 Kind::MultiThread => false,
             },
             enable_io: self.enable_io,
             enable_time: self.enable_time,
             start_paused: self.start_paused,
+            nevents: self.nevents,
         }
     }
 
@@ -420,7 +683,6 @@ impl Builder {
     /// ```
     /// # use tokio::runtime;
     /// # use std::time::Duration;
-    ///
     /// # pub fn main() {
     /// let rt = runtime::Builder::new_multi_thread()
     ///     .thread_keep_alive(Duration::from_millis(100))
@@ -432,34 +694,385 @@ impl Builder {
         self
     }
 
-    fn build_basic_runtime(&mut self) -> io::Result<Runtime> {
-        use crate::runtime::{BasicScheduler, Kind};
+    /// Sets the number of scheduler ticks after which the scheduler will poll the global
+    /// task queue.
+    ///
+    /// A scheduler "tick" roughly corresponds to one `poll` invocation on a task.
+    ///
+    /// By default the global queue interval is:
+    ///
+    /// * `31` for the current-thread scheduler.
+    /// * `61` for the multithreaded scheduler.
+    ///
+    /// Schedulers have a local queue of already-claimed tasks, and a global queue of incoming
+    /// tasks. Setting the interval to a smaller value increases the fairness of the scheduler,
+    /// at the cost of more synchronization overhead. That can be beneficial for prioritizing
+    /// getting started on new work, especially if tasks frequently yield rather than complete
+    /// or await on further I/O. Conversely, a higher value prioritizes existing work, and
+    /// is a good choice when most tasks quickly complete polling.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use tokio::runtime;
+    /// # pub fn main() {
+    /// let rt = runtime::Builder::new_multi_thread()
+    ///     .global_queue_interval(31)
+    ///     .build();
+    /// # }
+    /// ```
+    pub fn global_queue_interval(&mut self, val: u32) -> &mut Self {
+        self.global_queue_interval = Some(val);
+        self
+    }
 
-        let (driver, resources) = driver::Driver::new(self.get_cfg())?;
+    /// Sets the number of scheduler ticks after which the scheduler will poll for
+    /// external events (timers, I/O, and so on).
+    ///
+    /// A scheduler "tick" roughly corresponds to one `poll` invocation on a task.
+    ///
+    /// By default, the event interval is `61` for all scheduler types.
+    ///
+    /// Setting the event interval determines the effective "priority" of delivering
+    /// these external events (which may wake up additional tasks), compared to
+    /// executing tasks that are currently ready to run. A smaller value is useful
+    /// when tasks frequently spend a long time in polling, or frequently yield,
+    /// which can result in overly long delays picking up I/O events. Conversely,
+    /// picking up new events requires extra synchronization and syscall overhead,
+    /// so if tasks generally complete their polling quickly, a higher event interval
+    /// will minimize that overhead while still keeping the scheduler responsive to
+    /// events.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use tokio::runtime;
+    /// # pub fn main() {
+    /// let rt = runtime::Builder::new_multi_thread()
+    ///     .event_interval(31)
+    ///     .build();
+    /// # }
+    /// ```
+    pub fn event_interval(&mut self, val: u32) -> &mut Self {
+        self.event_interval = val;
+        self
+    }
 
-        // And now put a single-threaded scheduler on top of the timer. When
-        // there are no futures ready to do something, it'll let the timer or
-        // the reactor to generate some new stimuli for the futures to continue
-        // in their life.
-        let scheduler = BasicScheduler::new(driver);
-        let spawner = Spawner::Basic(scheduler.spawner().clone());
+    cfg_unstable! {
+        /// Configure how the runtime responds to an unhandled panic on a
+        /// spawned task.
+        ///
+        /// By default, an unhandled panic (i.e. a panic not caught by
+        /// [`std::panic::catch_unwind`]) has no impact on the runtime's
+        /// execution. The panic is error value is forwarded to the task's
+        /// [`JoinHandle`] and all other spawned tasks continue running.
+        ///
+        /// The `unhandled_panic` option enables configuring this behavior.
+        ///
+        /// * `UnhandledPanic::Ignore` is the default behavior. Panics on
+        ///   spawned tasks have no impact on the runtime's execution.
+        /// * `UnhandledPanic::ShutdownRuntime` will force the runtime to
+        ///   shutdown immediately when a spawned task panics even if that
+        ///   task's `JoinHandle` has not been dropped. All other spawned tasks
+        ///   will immediately terminate and further calls to
+        ///   [`Runtime::block_on`] will panic.
+        ///
+        /// # Unstable
+        ///
+        /// This option is currently unstable and its implementation is
+        /// incomplete. The API may change or be removed in the future. See
+        /// tokio-rs/tokio#4516 for more details.
+        ///
+        /// # Examples
+        ///
+        /// The following demonstrates a runtime configured to shutdown on
+        /// panic. The first spawned task panics and results in the runtime
+        /// shutting down. The second spawned task never has a chance to
+        /// execute. The call to `block_on` will panic due to the runtime being
+        /// forcibly shutdown.
+        ///
+        /// ```should_panic
+        /// use tokio::runtime::{self, UnhandledPanic};
+        ///
+        /// # pub fn main() {
+        /// let rt = runtime::Builder::new_current_thread()
+        ///     .unhandled_panic(UnhandledPanic::ShutdownRuntime)
+        ///     .build()
+        ///     .unwrap();
+        ///
+        /// rt.spawn(async { panic!("boom"); });
+        /// rt.spawn(async {
+        ///     // This task never completes.
+        /// });
+        ///
+        /// rt.block_on(async {
+        ///     // Do some work
+        /// # loop { tokio::task::yield_now().await; }
+        /// })
+        /// # }
+        /// ```
+        ///
+        /// [`JoinHandle`]: struct@crate::task::JoinHandle
+        pub fn unhandled_panic(&mut self, behavior: UnhandledPanic) -> &mut Self {
+            self.unhandled_panic = behavior;
+            self
+        }
+
+        /// Disables the LIFO task scheduler heuristic.
+        ///
+        /// The multi-threaded scheduler includes a heuristic for optimizing
+        /// message-passing patterns. This heuristic results in the **last**
+        /// scheduled task being polled first.
+        ///
+        /// To implement this heuristic, each worker thread has a slot which
+        /// holds the task that should be polled next. However, this slot cannot
+        /// be stolen by other worker threads, which can result in lower total
+        /// throughput when tasks tend to have longer poll times.
+        ///
+        /// This configuration option will disable this heuristic resulting in
+        /// all scheduled tasks being pushed into the worker-local queue, which
+        /// is stealable.
+        ///
+        /// Consider trying this option when the task "scheduled" time is high
+        /// but the runtime is underutilized. Use tokio-rs/tokio-metrics to
+        /// collect this data.
+        ///
+        /// # Unstable
+        ///
+        /// This configuration option is considered a workaround for the LIFO
+        /// slot not being stealable. When the slot becomes stealable, we will
+        /// revisit whether or not this option is necessary. See
+        /// tokio-rs/tokio#4941.
+        ///
+        /// # Examples
+        ///
+        /// ```
+        /// use tokio::runtime;
+        ///
+        /// let rt = runtime::Builder::new_multi_thread()
+        ///     .disable_lifo_slot()
+        ///     .build()
+        ///     .unwrap();
+        /// ```
+        pub fn disable_lifo_slot(&mut self) -> &mut Self {
+            self.disable_lifo_slot = true;
+            self
+        }
+
+        /// Specifies the random number generation seed to use within all
+        /// threads associated with the runtime being built.
+        ///
+        /// This option is intended to make certain parts of the runtime
+        /// deterministic (e.g. the [`tokio::select!`] macro). In the case of
+        /// [`tokio::select!`] it will ensure that the order that branches are
+        /// polled is deterministic.
+        ///
+        /// In addition to the code specifying `rng_seed` and interacting with
+        /// the runtime, the internals of Tokio and the Rust compiler may affect
+        /// the sequences of random numbers. In order to ensure repeatable
+        /// results, the version of Tokio, the versions of all other
+        /// dependencies that interact with Tokio, and the Rust compiler version
+        /// should also all remain constant.
+        ///
+        /// # Examples
+        ///
+        /// ```
+        /// # use tokio::runtime::{self, RngSeed};
+        /// # pub fn main() {
+        /// let seed = RngSeed::from_bytes(b"place your seed here");
+        /// let rt = runtime::Builder::new_current_thread()
+        ///     .rng_seed(seed)
+        ///     .build();
+        /// # }
+        /// ```
+        ///
+        /// [`tokio::select!`]: crate::select
+        pub fn rng_seed(&mut self, seed: RngSeed) -> &mut Self {
+            self.seed_generator = RngSeedGenerator::new(seed);
+            self
+        }
+    }
+
+    cfg_metrics! {
+        /// Enables tracking the distribution of task poll times.
+        ///
+        /// Task poll times are not instrumented by default as doing so requires
+        /// calling [`Instant::now()`] twice per task poll, which could add
+        /// measurable overhead. Use the [`Handle::metrics()`] to access the
+        /// metrics data.
+        ///
+        /// The histogram uses fixed bucket sizes. In other words, the histogram
+        /// buckets are not dynamic based on input values. Use the
+        /// `metrics_poll_count_histogram_` builder methods to configure the
+        /// histogram details.
+        ///
+        /// # Examples
+        ///
+        /// ```
+        /// use tokio::runtime;
+        ///
+        /// let rt = runtime::Builder::new_multi_thread()
+        ///     .enable_metrics_poll_count_histogram()
+        ///     .build()
+        ///     .unwrap();
+        /// # // Test default values here
+        /// # fn us(n: u64) -> std::time::Duration { std::time::Duration::from_micros(n) }
+        /// # let m = rt.handle().metrics();
+        /// # assert_eq!(m.poll_count_histogram_num_buckets(), 10);
+        /// # assert_eq!(m.poll_count_histogram_bucket_range(0), us(0)..us(100));
+        /// # assert_eq!(m.poll_count_histogram_bucket_range(1), us(100)..us(200));
+        /// ```
+        ///
+        /// [`Handle::metrics()`]: crate::runtime::Handle::metrics
+        /// [`Instant::now()`]: std::time::Instant::now
+        pub fn enable_metrics_poll_count_histogram(&mut self) -> &mut Self {
+            self.metrics_poll_count_histogram_enable = true;
+            self
+        }
+
+        /// Sets the histogram scale for tracking the distribution of task poll
+        /// times.
+        ///
+        /// Tracking the distribution of task poll times can be done using a
+        /// linear or log scale. When using linear scale, each histogram bucket
+        /// will represent the same range of poll times. When using log scale,
+        /// each histogram bucket will cover a range twice as big as the
+        /// previous bucket.
+        ///
+        /// **Default:** linear scale.
+        ///
+        /// # Examples
+        ///
+        /// ```
+        /// use tokio::runtime::{self, HistogramScale};
+        ///
+        /// let rt = runtime::Builder::new_multi_thread()
+        ///     .enable_metrics_poll_count_histogram()
+        ///     .metrics_poll_count_histogram_scale(HistogramScale::Log)
+        ///     .build()
+        ///     .unwrap();
+        /// ```
+        pub fn metrics_poll_count_histogram_scale(&mut self, histogram_scale: crate::runtime::HistogramScale) -> &mut Self {
+            self.metrics_poll_count_histogram.scale = histogram_scale;
+            self
+        }
+
+        /// Sets the histogram resolution for tracking the distribution of task
+        /// poll times.
+        ///
+        /// The resolution is the histogram's first bucket's range. When using a
+        /// linear histogram scale, each bucket will cover the same range. When
+        /// using a log scale, each bucket will cover a range twice as big as
+        /// the previous bucket. In the log case, the resolution represents the
+        /// smallest bucket range.
+        ///
+        /// Note that, when using log scale, the resolution is rounded up to the
+        /// nearest power of 2 in nanoseconds.
+        ///
+        /// **Default:** 100 microseconds.
+        ///
+        /// # Examples
+        ///
+        /// ```
+        /// use tokio::runtime;
+        /// use std::time::Duration;
+        ///
+        /// let rt = runtime::Builder::new_multi_thread()
+        ///     .enable_metrics_poll_count_histogram()
+        ///     .metrics_poll_count_histogram_resolution(Duration::from_micros(100))
+        ///     .build()
+        ///     .unwrap();
+        /// ```
+        pub fn metrics_poll_count_histogram_resolution(&mut self, resolution: Duration) -> &mut Self {
+            assert!(resolution > Duration::from_secs(0));
+            // Sanity check the argument and also make the cast below safe.
+            assert!(resolution <= Duration::from_secs(1));
+
+            let resolution = resolution.as_nanos() as u64;
+            self.metrics_poll_count_histogram.resolution = resolution;
+            self
+        }
+
+        /// Sets the number of buckets for the histogram tracking the
+        /// distribution of task poll times.
+        ///
+        /// The last bucket tracks all greater values that fall out of other
+        /// ranges. So, configuring the histogram using a linear scale,
+        /// resolution of 50ms, and 10 buckets, the 10th bucket will track task
+        /// polls that take more than 450ms to complete.
+        ///
+        /// **Default:** 10
+        ///
+        /// # Examples
+        ///
+        /// ```
+        /// use tokio::runtime;
+        ///
+        /// let rt = runtime::Builder::new_multi_thread()
+        ///     .enable_metrics_poll_count_histogram()
+        ///     .metrics_poll_count_histogram_buckets(15)
+        ///     .build()
+        ///     .unwrap();
+        /// ```
+        pub fn metrics_poll_count_histogram_buckets(&mut self, buckets: usize) -> &mut Self {
+            self.metrics_poll_count_histogram.num_buckets = buckets;
+            self
+        }
+    }
+
+    fn build_current_thread_runtime(&mut self) -> io::Result<Runtime> {
+        use crate::runtime::scheduler::{self, CurrentThread};
+        use crate::runtime::{runtime::Scheduler, Config};
+
+        let (driver, driver_handle) = driver::Driver::new(self.get_cfg())?;
 
         // Blocking pool
         let blocking_pool = blocking::create_blocking_pool(self, self.max_blocking_threads);
         let blocking_spawner = blocking_pool.spawner().clone();
 
-        Ok(Runtime {
-            kind: Kind::CurrentThread(scheduler),
-            handle: Handle {
-                spawner,
-                io_handle: resources.io_handle,
-                time_handle: resources.time_handle,
-                signal_handle: resources.signal_handle,
-                clock: resources.clock,
-                blocking_spawner,
+        // Generate a rng seed for this runtime.
+        let seed_generator_1 = self.seed_generator.next_generator();
+        let seed_generator_2 = self.seed_generator.next_generator();
+
+        // And now put a single-threaded scheduler on top of the timer. When
+        // there are no futures ready to do something, it'll let the timer or
+        // the reactor to generate some new stimuli for the futures to continue
+        // in their life.
+        let (scheduler, handle) = CurrentThread::new(
+            driver,
+            driver_handle,
+            blocking_spawner,
+            seed_generator_2,
+            Config {
+                before_park: self.before_park.clone(),
+                after_unpark: self.after_unpark.clone(),
+                global_queue_interval: self.global_queue_interval,
+                event_interval: self.event_interval,
+                #[cfg(tokio_unstable)]
+                unhandled_panic: self.unhandled_panic.clone(),
+                disable_lifo_slot: self.disable_lifo_slot,
+                seed_generator: seed_generator_1,
+                metrics_poll_count_histogram: self.metrics_poll_count_histogram_builder(),
             },
+        );
+
+        let handle = Handle {
+            inner: scheduler::Handle::CurrentThread(handle),
+        };
+
+        Ok(Runtime::from_parts(
+            Scheduler::CurrentThread(scheduler),
+            handle,
             blocking_pool,
-        })
+        ))
+    }
+
+    fn metrics_poll_count_histogram_builder(&self) -> Option<HistogramBuilder> {
+        if self.metrics_poll_count_histogram_enable {
+            Some(self.metrics_poll_count_histogram.clone())
+        } else {
+            None
+        }
     }
 }
 
@@ -484,6 +1097,25 @@ cfg_io_driver! {
             self.enable_io = true;
             self
         }
+
+        /// Enables the I/O driver and configures the max number of events to be
+        /// processed per tick.
+        ///
+        /// # Examples
+        ///
+        /// ```
+        /// use tokio::runtime;
+        ///
+        /// let rt = runtime::Builder::new_current_thread()
+        ///     .enable_io()
+        ///     .max_io_events_per_tick(1024)
+        ///     .build()
+        ///     .unwrap();
+        /// ```
+        pub fn max_io_events_per_tick(&mut self, capacity: usize) -> &mut Self {
+            self.nevents = capacity;
+            self
+        }
     }
 }
 
@@ -539,39 +1171,48 @@ cfg_rt_multi_thread! {
     impl Builder {
         fn build_threaded_runtime(&mut self) -> io::Result<Runtime> {
             use crate::loom::sys::num_cpus;
-            use crate::runtime::{Kind, ThreadPool};
-            use crate::runtime::park::Parker;
+            use crate::runtime::{Config, runtime::Scheduler};
+            use crate::runtime::scheduler::{self, MultiThread};
 
             let core_threads = self.worker_threads.unwrap_or_else(num_cpus);
 
-            let (driver, resources) = driver::Driver::new(self.get_cfg())?;
-
-            let (scheduler, launch) = ThreadPool::new(core_threads, Parker::new(driver));
-            let spawner = Spawner::ThreadPool(scheduler.spawner().clone());
+            let (driver, driver_handle) = driver::Driver::new(self.get_cfg())?;
 
             // Create the blocking pool
-            let blocking_pool = blocking::create_blocking_pool(self, self.max_blocking_threads + core_threads);
+            let blocking_pool =
+                blocking::create_blocking_pool(self, self.max_blocking_threads + core_threads);
             let blocking_spawner = blocking_pool.spawner().clone();
 
-            // Create the runtime handle
-            let handle = Handle {
-                spawner,
-                io_handle: resources.io_handle,
-                time_handle: resources.time_handle,
-                signal_handle: resources.signal_handle,
-                clock: resources.clock,
+            // Generate a rng seed for this runtime.
+            let seed_generator_1 = self.seed_generator.next_generator();
+            let seed_generator_2 = self.seed_generator.next_generator();
+
+            let (scheduler, handle, launch) = MultiThread::new(
+                core_threads,
+                driver,
+                driver_handle,
                 blocking_spawner,
-            };
+                seed_generator_2,
+                Config {
+                    before_park: self.before_park.clone(),
+                    after_unpark: self.after_unpark.clone(),
+                    global_queue_interval: self.global_queue_interval,
+                    event_interval: self.event_interval,
+                    #[cfg(tokio_unstable)]
+                    unhandled_panic: self.unhandled_panic.clone(),
+                    disable_lifo_slot: self.disable_lifo_slot,
+                    seed_generator: seed_generator_1,
+                    metrics_poll_count_histogram: self.metrics_poll_count_histogram_builder(),
+                },
+            );
+
+            let handle = Handle { inner: scheduler::Handle::MultiThread(handle) };
 
             // Spawn the thread pool workers
-            let _enter = crate::runtime::context::enter(handle.clone());
+            let _enter = handle.enter();
             launch.launch();
 
-            Ok(Runtime {
-                kind: Kind::ThreadPool(scheduler),
-                handle,
-                blocking_pool,
-            })
+            Ok(Runtime::from_parts(Scheduler::MultiThread(scheduler), handle, blocking_pool))
         }
     }
 }
@@ -587,7 +1228,9 @@ impl fmt::Debug for Builder {
             )
             .field("thread_stack_size", &self.thread_stack_size)
             .field("after_start", &self.after_start.as_ref().map(|_| "..."))
-            .field("before_stop", &self.after_start.as_ref().map(|_| "..."))
+            .field("before_stop", &self.before_stop.as_ref().map(|_| "..."))
+            .field("before_park", &self.before_park.as_ref().map(|_| "..."))
+            .field("after_unpark", &self.after_unpark.as_ref().map(|_| "..."))
             .finish()
     }
 }
diff --git a/vendor/tokio/src/runtime/config.rs b/vendor/tokio/src/runtime/config.rs
new file mode 100644
index 000000000..c42e4fe5a
--- /dev/null
+++ b/vendor/tokio/src/runtime/config.rs
@@ -0,0 +1,37 @@
+#![cfg_attr(any(not(feature = "full"), tokio_wasm), allow(dead_code))]
+use crate::runtime::Callback;
+use crate::util::RngSeedGenerator;
+
+pub(crate) struct Config {
+    /// How many ticks before pulling a task from the global/remote queue?
+    pub(crate) global_queue_interval: Option<u32>,
+
+    /// How many ticks before yielding to the driver for timer and I/O events?
+    pub(crate) event_interval: u32,
+
+    /// Callback for a worker parking itself
+    pub(crate) before_park: Option<Callback>,
+
+    /// Callback for a worker unparking itself
+    pub(crate) after_unpark: Option<Callback>,
+
+    /// The multi-threaded scheduler includes a per-worker LIFO slot used to
+    /// store the last scheduled task. This can improve certain usage patterns,
+    /// especially message passing between tasks. However, this LIFO slot is not
+    /// currently stealable.
+    ///
+    /// Eventually, the LIFO slot **will** become stealable, however as a
+    /// stop-gap, this unstable option lets users disable the LIFO task.
+    pub(crate) disable_lifo_slot: bool,
+
+    /// Random number generator seed to configure runtimes to act in a
+    /// deterministic way.
+    pub(crate) seed_generator: RngSeedGenerator,
+
+    /// How to build poll time histograms
+    pub(crate) metrics_poll_count_histogram: Option<crate::runtime::HistogramBuilder>,
+
+    #[cfg(tokio_unstable)]
+    /// How to respond to unhandled task panics.
+    pub(crate) unhandled_panic: crate::runtime::UnhandledPanic,
+}
diff --git a/vendor/tokio/src/runtime/context.rs b/vendor/tokio/src/runtime/context.rs
index a727ed497..5943e9aa9 100644
--- a/vendor/tokio/src/runtime/context.rs
+++ b/vendor/tokio/src/runtime/context.rs
@@ -1,73 +1,191 @@
-//! Thread local runtime context
-use crate::runtime::Handle;
+use crate::loom::thread::AccessError;
+use crate::runtime::coop;
 
-use std::cell::RefCell;
+use std::cell::Cell;
 
-thread_local! {
-    static CONTEXT: RefCell<Option<Handle>> = RefCell::new(None)
-}
+#[cfg(any(feature = "rt", feature = "macros"))]
+use crate::util::rand::FastRand;
 
-pub(crate) fn current() -> Option<Handle> {
-    CONTEXT.with(|ctx| ctx.borrow().clone())
-}
+cfg_rt! {
+    mod blocking;
+    pub(crate) use blocking::{disallow_block_in_place, try_enter_blocking_region, BlockingRegionGuard};
 
-cfg_io_driver! {
-    pub(crate) fn io_handle() -> crate::runtime::driver::IoHandle {
-        CONTEXT.with(|ctx| {
-            let ctx = ctx.borrow();
-            ctx.as_ref().expect(crate::util::error::CONTEXT_MISSING_ERROR).io_handle.clone()
-        })
+    mod current;
+    pub(crate) use current::{with_current, try_set_current, SetCurrentGuard};
+
+    mod runtime;
+    pub(crate) use runtime::{EnterRuntime, enter_runtime};
+
+    mod scoped;
+    use scoped::Scoped;
+
+    use crate::runtime::{scheduler, task::Id};
+
+    use std::task::Waker;
+
+    cfg_taskdump! {
+        use crate::runtime::task::trace;
     }
 }
 
-cfg_signal_internal! {
-    #[cfg(unix)]
-    pub(crate) fn signal_handle() -> crate::runtime::driver::SignalHandle {
-        CONTEXT.with(|ctx| {
-            let ctx = ctx.borrow();
-            ctx.as_ref().expect(crate::util::error::CONTEXT_MISSING_ERROR).signal_handle.clone()
-        })
-    }
+cfg_rt_multi_thread! {
+    mod runtime_mt;
+    pub(crate) use runtime_mt::{current_enter_context, exit_runtime};
 }
 
-cfg_time! {
-    pub(crate) fn time_handle() -> crate::runtime::driver::TimeHandle {
-        CONTEXT.with(|ctx| {
-            let ctx = ctx.borrow();
-            ctx.as_ref().expect(crate::util::error::CONTEXT_MISSING_ERROR).time_handle.clone()
-        })
-    }
+struct Context {
+    /// Uniquely identifies the current thread
+    #[cfg(feature = "rt")]
+    thread_id: Cell<Option<ThreadId>>,
 
-    cfg_test_util! {
-        pub(crate) fn clock() -> Option<crate::runtime::driver::Clock> {
-            CONTEXT.with(|ctx| (*ctx.borrow()).as_ref().map(|ctx| ctx.clock.clone()))
-        }
-    }
+    /// Handle to the runtime scheduler running on the current thread.
+    #[cfg(feature = "rt")]
+    current: current::HandleCell,
+
+    /// Handle to the scheduler's internal "context"
+    #[cfg(feature = "rt")]
+    scheduler: Scoped<scheduler::Context>,
+
+    #[cfg(feature = "rt")]
+    current_task_id: Cell<Option<Id>>,
+
+    /// Tracks if the current thread is currently driving a runtime.
+    /// Note, that if this is set to "entered", the current scheduler
+    /// handle may not reference the runtime currently executing. This
+    /// is because other runtime handles may be set to current from
+    /// within a runtime.
+    #[cfg(feature = "rt")]
+    runtime: Cell<EnterRuntime>,
+
+    #[cfg(any(feature = "rt", feature = "macros"))]
+    rng: Cell<Option<FastRand>>,
+
+    /// Tracks the amount of "work" a task may still do before yielding back to
+    /// the sheduler
+    budget: Cell<coop::Budget>,
+
+    #[cfg(all(
+        tokio_unstable,
+        tokio_taskdump,
+        feature = "rt",
+        target_os = "linux",
+        any(target_arch = "aarch64", target_arch = "x86", target_arch = "x86_64")
+    ))]
+    trace: trace::Context,
 }
 
-cfg_rt! {
-    pub(crate) fn spawn_handle() -> Option<crate::runtime::Spawner> {
-        CONTEXT.with(|ctx| (*ctx.borrow()).as_ref().map(|ctx| ctx.spawner.clone()))
+tokio_thread_local! {
+    static CONTEXT: Context = const {
+        Context {
+            #[cfg(feature = "rt")]
+            thread_id: Cell::new(None),
+
+            /// Tracks the current runtime handle to use when spawning,
+            /// accessing drivers, etc...
+            #[cfg(feature = "rt")]
+            current: current::HandleCell::new(),
+
+            /// Tracks the current scheduler internal context
+            #[cfg(feature = "rt")]
+            scheduler: Scoped::new(),
+
+            #[cfg(feature = "rt")]
+            current_task_id: Cell::new(None),
+
+            /// Tracks if the current thread is currently driving a runtime.
+            /// Note, that if this is set to "entered", the current scheduler
+            /// handle may not reference the runtime currently executing. This
+            /// is because other runtime handles may be set to current from
+            /// within a runtime.
+            #[cfg(feature = "rt")]
+            runtime: Cell::new(EnterRuntime::NotEntered),
+
+            #[cfg(any(feature = "rt", feature = "macros"))]
+            rng: Cell::new(None),
+
+            budget: Cell::new(coop::Budget::unconstrained()),
+
+            #[cfg(all(
+                tokio_unstable,
+                tokio_taskdump,
+                feature = "rt",
+                target_os = "linux",
+                any(
+                    target_arch = "aarch64",
+                    target_arch = "x86",
+                    target_arch = "x86_64"
+                )
+            ))]
+            trace: trace::Context::new(),
+        }
     }
 }
 
-/// Set this [`Handle`] as the current active [`Handle`].
-///
-/// [`Handle`]: Handle
-pub(crate) fn enter(new: Handle) -> EnterGuard {
+#[cfg(any(feature = "macros", all(feature = "sync", feature = "rt")))]
+pub(crate) fn thread_rng_n(n: u32) -> u32 {
     CONTEXT.with(|ctx| {
-        let old = ctx.borrow_mut().replace(new);
-        EnterGuard(old)
+        let mut rng = ctx.rng.get().unwrap_or_else(FastRand::new);
+        let ret = rng.fastrand_n(n);
+        ctx.rng.set(Some(rng));
+        ret
     })
 }
 
-#[derive(Debug)]
-pub(crate) struct EnterGuard(Option<Handle>);
+pub(super) fn budget<R>(f: impl FnOnce(&Cell<coop::Budget>) -> R) -> Result<R, AccessError> {
+    CONTEXT.try_with(|ctx| f(&ctx.budget))
+}
+
+cfg_rt! {
+    use crate::runtime::ThreadId;
+
+    pub(crate) fn thread_id() -> Result<ThreadId, AccessError> {
+        CONTEXT.try_with(|ctx| {
+            match ctx.thread_id.get() {
+                Some(id) => id,
+                None => {
+                    let id = ThreadId::next();
+                    ctx.thread_id.set(Some(id));
+                    id
+                }
+            }
+        })
+    }
 
-impl Drop for EnterGuard {
-    fn drop(&mut self) {
-        CONTEXT.with(|ctx| {
-            *ctx.borrow_mut() = self.0.take();
+    pub(crate) fn set_current_task_id(id: Option<Id>) -> Option<Id> {
+        CONTEXT.try_with(|ctx| ctx.current_task_id.replace(id)).unwrap_or(None)
+    }
+
+    pub(crate) fn current_task_id() -> Option<Id> {
+        CONTEXT.try_with(|ctx| ctx.current_task_id.get()).unwrap_or(None)
+    }
+
+    #[track_caller]
+    pub(crate) fn defer(waker: &Waker) {
+        with_scheduler(|maybe_scheduler| {
+            if let Some(scheduler) = maybe_scheduler {
+                scheduler.defer(waker);
+            } else {
+                // Called from outside of the runtime, immediately wake the
+                // task.
+                waker.wake_by_ref();
+            }
         });
     }
+
+    pub(super) fn set_scheduler<R>(v: &scheduler::Context, f: impl FnOnce() -> R) -> R {
+        CONTEXT.with(|c| c.scheduler.set(v, f))
+    }
+
+    #[track_caller]
+    pub(super) fn with_scheduler<R>(f: impl FnOnce(Option<&scheduler::Context>) -> R) -> R {
+        CONTEXT.with(|c| c.scheduler.with(f))
+    }
+
+    cfg_taskdump! {
+        /// SAFETY: Callers of this function must ensure that trace frames always
+        /// form a valid linked list.
+        pub(crate) unsafe fn with_trace<R>(f: impl FnOnce(&trace::Context) -> R) -> Option<R> {
+            CONTEXT.try_with(|c| f(&c.trace)).ok()
+        }
+    }
 }
diff --git a/vendor/tokio/src/runtime/context/blocking.rs b/vendor/tokio/src/runtime/context/blocking.rs
new file mode 100644
index 000000000..8ae4f570e
--- /dev/null
+++ b/vendor/tokio/src/runtime/context/blocking.rs
@@ -0,0 +1,121 @@
+use super::{EnterRuntime, CONTEXT};
+
+use crate::loom::thread::AccessError;
+use crate::util::markers::NotSendOrSync;
+
+use std::marker::PhantomData;
+use std::time::Duration;
+
+/// Guard tracking that a caller has entered a blocking region.
+#[must_use]
+pub(crate) struct BlockingRegionGuard {
+    _p: PhantomData<NotSendOrSync>,
+}
+
+pub(crate) struct DisallowBlockInPlaceGuard(bool);
+
+pub(crate) fn try_enter_blocking_region() -> Option<BlockingRegionGuard> {
+    CONTEXT
+        .try_with(|c| {
+            if c.runtime.get().is_entered() {
+                None
+            } else {
+                Some(BlockingRegionGuard::new())
+            }
+            // If accessing the thread-local fails, the thread is terminating
+            // and thread-locals are being destroyed. Because we don't know if
+            // we are currently in a runtime or not, we default to being
+            // permissive.
+        })
+        .unwrap_or_else(|_| Some(BlockingRegionGuard::new()))
+}
+
+/// Disallows blocking in the current runtime context until the guard is dropped.
+pub(crate) fn disallow_block_in_place() -> DisallowBlockInPlaceGuard {
+    let reset = CONTEXT.with(|c| {
+        if let EnterRuntime::Entered {
+            allow_block_in_place: true,
+        } = c.runtime.get()
+        {
+            c.runtime.set(EnterRuntime::Entered {
+                allow_block_in_place: false,
+            });
+            true
+        } else {
+            false
+        }
+    });
+
+    DisallowBlockInPlaceGuard(reset)
+}
+
+impl BlockingRegionGuard {
+    pub(super) fn new() -> BlockingRegionGuard {
+        BlockingRegionGuard { _p: PhantomData }
+    }
+
+    /// Blocks the thread on the specified future, returning the value with
+    /// which that future completes.
+    pub(crate) fn block_on<F>(&mut self, f: F) -> Result<F::Output, AccessError>
+    where
+        F: std::future::Future,
+    {
+        use crate::runtime::park::CachedParkThread;
+
+        let mut park = CachedParkThread::new();
+        park.block_on(f)
+    }
+
+    /// Blocks the thread on the specified future for **at most** `timeout`
+    ///
+    /// If the future completes before `timeout`, the result is returned. If
+    /// `timeout` elapses, then `Err` is returned.
+    pub(crate) fn block_on_timeout<F>(&mut self, f: F, timeout: Duration) -> Result<F::Output, ()>
+    where
+        F: std::future::Future,
+    {
+        use crate::runtime::park::CachedParkThread;
+        use std::task::Context;
+        use std::task::Poll::Ready;
+        use std::time::Instant;
+
+        let mut park = CachedParkThread::new();
+        let waker = park.waker().map_err(|_| ())?;
+        let mut cx = Context::from_waker(&waker);
+
+        pin!(f);
+        let when = Instant::now() + timeout;
+
+        loop {
+            if let Ready(v) = crate::runtime::coop::budget(|| f.as_mut().poll(&mut cx)) {
+                return Ok(v);
+            }
+
+            let now = Instant::now();
+
+            if now >= when {
+                return Err(());
+            }
+
+            park.park_timeout(when - now);
+        }
+    }
+}
+
+impl Drop for DisallowBlockInPlaceGuard {
+    fn drop(&mut self) {
+        if self.0 {
+            // XXX: Do we want some kind of assertion here, or is "best effort" okay?
+            CONTEXT.with(|c| {
+                if let EnterRuntime::Entered {
+                    allow_block_in_place: false,
+                } = c.runtime.get()
+                {
+                    c.runtime.set(EnterRuntime::Entered {
+                        allow_block_in_place: true,
+                    });
+                }
+            })
+        }
+    }
+}
diff --git a/vendor/tokio/src/runtime/context/current.rs b/vendor/tokio/src/runtime/context/current.rs
new file mode 100644
index 000000000..c3dc5c899
--- /dev/null
+++ b/vendor/tokio/src/runtime/context/current.rs
@@ -0,0 +1,99 @@
+use super::{Context, CONTEXT};
+
+use crate::runtime::{scheduler, TryCurrentError};
+use crate::util::markers::SyncNotSend;
+
+use std::cell::{Cell, RefCell};
+use std::marker::PhantomData;
+
+#[derive(Debug)]
+#[must_use]
+pub(crate) struct SetCurrentGuard {
+    // The previous handle
+    prev: Option<scheduler::Handle>,
+
+    // The depth for this guard
+    depth: usize,
+
+    // Don't let the type move across threads.
+    _p: PhantomData<SyncNotSend>,
+}
+
+pub(super) struct HandleCell {
+    /// Current handle
+    handle: RefCell<Option<scheduler::Handle>>,
+
+    /// Tracks the number of nested calls to `try_set_current`.
+    depth: Cell<usize>,
+}
+
+/// Sets this [`Handle`] as the current active [`Handle`].
+///
+/// [`Handle`]: crate::runtime::scheduler::Handle
+pub(crate) fn try_set_current(handle: &scheduler::Handle) -> Option<SetCurrentGuard> {
+    CONTEXT.try_with(|ctx| ctx.set_current(handle)).ok()
+}
+
+pub(crate) fn with_current<F, R>(f: F) -> Result<R, TryCurrentError>
+where
+    F: FnOnce(&scheduler::Handle) -> R,
+{
+    match CONTEXT.try_with(|ctx| ctx.current.handle.borrow().as_ref().map(f)) {
+        Ok(Some(ret)) => Ok(ret),
+        Ok(None) => Err(TryCurrentError::new_no_context()),
+        Err(_access_error) => Err(TryCurrentError::new_thread_local_destroyed()),
+    }
+}
+
+impl Context {
+    pub(super) fn set_current(&self, handle: &scheduler::Handle) -> SetCurrentGuard {
+        let old_handle = self.current.handle.borrow_mut().replace(handle.clone());
+        let depth = self.current.depth.get();
+
+        if depth == usize::MAX {
+            panic!("reached max `enter` depth");
+        }
+
+        let depth = depth + 1;
+        self.current.depth.set(depth);
+
+        SetCurrentGuard {
+            prev: old_handle,
+            depth,
+            _p: PhantomData,
+        }
+    }
+}
+
+impl HandleCell {
+    pub(super) const fn new() -> HandleCell {
+        HandleCell {
+            handle: RefCell::new(None),
+            depth: Cell::new(0),
+        }
+    }
+}
+
+impl Drop for SetCurrentGuard {
+    fn drop(&mut self) {
+        CONTEXT.with(|ctx| {
+            let depth = ctx.current.depth.get();
+
+            if depth != self.depth {
+                if !std::thread::panicking() {
+                    panic!(
+                        "`EnterGuard` values dropped out of order. Guards returned by \
+                         `tokio::runtime::Handle::enter()` must be dropped in the reverse \
+                         order as they were acquired."
+                    );
+                } else {
+                    // Just return... this will leave handles in a wonky state though...
+                    return;
+                }
+            }
+
+            *ctx.current.handle.borrow_mut() = self.prev.take();
+            ctx.current.depth.set(depth - 1);
+        });
+    }
+}
diff --git a/vendor/tokio/src/runtime/context/runtime.rs b/vendor/tokio/src/runtime/context/runtime.rs
new file mode 100644
index 000000000..f2e29899a
--- /dev/null
+++ b/vendor/tokio/src/runtime/context/runtime.rs
@@ -0,0 +1,99 @@
+use super::{BlockingRegionGuard, SetCurrentGuard, CONTEXT};
+
+use crate::runtime::scheduler;
+use crate::util::rand::{FastRand, RngSeed};
+
+use std::fmt;
+
+#[derive(Debug, Clone, Copy)]
+#[must_use]
+pub(crate) enum EnterRuntime {
+    /// Currently in a runtime context.
+    #[cfg_attr(not(feature = "rt"), allow(dead_code))]
+    Entered { allow_block_in_place: bool },
+
+    /// Not in a runtime context **or** a blocking region.
+    NotEntered,
+}
+
+/// Guard tracking that a caller has entered a runtime context.
+#[must_use]
+pub(crate) struct EnterRuntimeGuard {
+    /// Tracks that the current thread has entered a blocking function call.
+    pub(crate) blocking: BlockingRegionGuard,
+
+    #[allow(dead_code)] // Only tracking the guard.
+    pub(crate) handle: SetCurrentGuard,
+
+    // Tracks the previous random number generator seed
+    old_seed: RngSeed,
+}
+
+/// Marks the current thread as being within the dynamic extent of an
+/// executor.
+#[track_caller]
+pub(crate) fn enter_runtime<F, R>(handle: &scheduler::Handle, allow_block_in_place: bool, f: F) -> R
+where
+    F: FnOnce(&mut BlockingRegionGuard) -> R,
+{
+    let maybe_guard = CONTEXT.with(|c| {
+        if c.runtime.get().is_entered() {
+            None
+        } else {
+            // Set the entered flag
+            c.runtime.set(EnterRuntime::Entered {
+                allow_block_in_place,
+            });
+
+            // Generate a new seed
+            let rng_seed = handle.seed_generator().next_seed();
+
+            // Swap the RNG seed
+            let mut rng = c.rng.get().unwrap_or_else(FastRand::new);
+            let old_seed = rng.replace_seed(rng_seed);
+            c.rng.set(Some(rng));
+
+            Some(EnterRuntimeGuard {
+                blocking: BlockingRegionGuard::new(),
+                handle: c.set_current(handle),
+                old_seed,
+            })
+        }
+    });
+
+    if let Some(mut guard) = maybe_guard {
+        return f(&mut guard.blocking);
+    }
+
+    panic!(
+        "Cannot start a runtime from within a runtime. This happens \
+            because a function (like `block_on`) attempted to block the \
+            current thread while the thread is being used to drive \
+            asynchronous tasks."
+    );
+}
+
+impl fmt::Debug for EnterRuntimeGuard {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("Enter").finish()
+    }
+}
+
+impl Drop for EnterRuntimeGuard {
+    fn drop(&mut self) {
+        CONTEXT.with(|c| {
+            assert!(c.runtime.get().is_entered());
+            c.runtime.set(EnterRuntime::NotEntered);
+            // Replace the previous RNG seed
+            let mut rng = c.rng.get().unwrap_or_else(FastRand::new);
+            rng.replace_seed(self.old_seed.clone());
+            c.rng.set(Some(rng));
+        });
+    }
+}
+
+impl EnterRuntime {
+    pub(crate) fn is_entered(self) -> bool {
+        matches!(self, EnterRuntime::Entered { .. })
+    }
+}
diff --git a/vendor/tokio/src/runtime/context/runtime_mt.rs b/vendor/tokio/src/runtime/context/runtime_mt.rs
new file mode 100644
index 000000000..728caeae9
--- /dev/null
+++ b/vendor/tokio/src/runtime/context/runtime_mt.rs
@@ -0,0 +1,36 @@
+use super::{EnterRuntime, CONTEXT};
+
+/// Returns true if in a runtime context.
+pub(crate) fn current_enter_context() -> EnterRuntime {
+    CONTEXT.with(|c| c.runtime.get())
+}
+
+/// Forces the current "entered" state to be cleared while the closure
+/// is executed.
+pub(crate) fn exit_runtime<F: FnOnce() -> R, R>(f: F) -> R {
+    // Reset in case the closure panics
+    struct Reset(EnterRuntime);
+
+    impl Drop for Reset {
+        fn drop(&mut self) {
+            CONTEXT.with(|c| {
+                assert!(
+                    !c.runtime.get().is_entered(),
+                    "closure claimed permanent executor"
+                );
+                c.runtime.set(self.0);
+            });
+        }
+    }
+
+    let was = CONTEXT.with(|c| {
+        let e = c.runtime.get();
+        assert!(e.is_entered(), "asked to exit when not entered");
+        c.runtime.set(EnterRuntime::NotEntered);
+        e
+    });
+
+    let _reset = Reset(was);
+    // dropping _reset after f() will reset ENTERED
+    f()
+}
diff --git a/vendor/tokio/src/runtime/context/scoped.rs b/vendor/tokio/src/runtime/context/scoped.rs
new file mode 100644
index 000000000..7b202a16c
--- /dev/null
+++ b/vendor/tokio/src/runtime/context/scoped.rs
@@ -0,0 +1,56 @@
+use std::cell::Cell;
+use std::ptr;
+
+/// Scoped thread-local storage
+pub(super) struct Scoped<T> {
+    pub(super) inner: Cell<*const T>,
+}
+
+impl<T> Scoped<T> {
+    pub(super) const fn new() -> Scoped<T> {
+        Scoped {
+            inner: Cell::new(ptr::null()),
+        }
+    }
+
+    /// Inserts a value into the scoped cell for the duration of the closure
+    pub(super) fn set<F, R>(&self, t: &T, f: F) -> R
+    where
+        F: FnOnce() -> R,
+    {
+        struct Reset<'a, T> {
+            cell: &'a Cell<*const T>,
+            prev: *const T,
+        }
+
+        impl<T> Drop for Reset<'_, T> {
+            fn drop(&mut self) {
+                self.cell.set(self.prev);
+            }
+        }
+
+        let prev = self.inner.get();
+        self.inner.set(t as *const _);
+
+        let _reset = Reset {
+            cell: &self.inner,
+            prev,
+        };
+
+        f()
+    }
+
+    /// Gets the value out of the scoped cell;
+    pub(super) fn with<F, R>(&self, f: F) -> R
+    where
+        F: FnOnce(Option<&T>) -> R,
+    {
+        let val = self.inner.get();
+
+        if val.is_null() {
+            f(None)
+        } else {
+            unsafe { f(Some(&*val)) }
+        }
+    }
+}
diff --git a/vendor/tokio/src/coop.rs b/vendor/tokio/src/runtime/coop.rs
index 16d93fb75..2dba24615 100644
--- a/vendor/tokio/src/coop.rs
+++ b/vendor/tokio/src/runtime/coop.rs
@@ -29,17 +29,18 @@
 // other futures. By doing this, you avoid double-counting each iteration of
 // the outer future against the cooperating budget.
 
-use std::cell::Cell;
-
-thread_local! {
-    static CURRENT: Cell<Budget> = Cell::new(Budget::unconstrained());
-}
+use crate::runtime::context;
 
 /// Opaque type tracking the amount of "work" a task may still do before
 /// yielding back to the scheduler.
 #[derive(Debug, Copy, Clone)]
 pub(crate) struct Budget(Option<u8>);
 
+pub(crate) struct BudgetDecrement {
+    success: bool,
+    hit_zero: bool,
+}
+
 impl Budget {
     /// Budget assigned to a task on each poll.
     ///
@@ -56,27 +57,23 @@ impl Budget {
     }
 
     /// Returns an unconstrained budget. Operations will not be limited.
-    const fn unconstrained() -> Budget {
+    pub(super) const fn unconstrained() -> Budget {
         Budget(None)
     }
-}
 
-cfg_rt_multi_thread! {
-    impl Budget {
-        fn has_remaining(self) -> bool {
-            self.0.map(|budget| budget > 0).unwrap_or(true)
-        }
+    fn has_remaining(self) -> bool {
+        self.0.map(|budget| budget > 0).unwrap_or(true)
     }
 }
 
-/// Run the given closure with a cooperative task budget. When the function
+/// Runs the given closure with a cooperative task budget. When the function
 /// returns, the budget is reset to the value prior to calling the function.
 #[inline(always)]
 pub(crate) fn budget<R>(f: impl FnOnce() -> R) -> R {
     with_budget(Budget::initial(), f)
 }
 
-/// Run the given closure with an unconstrained task budget. When the function returns, the budget
+/// Runs the given closure with an unconstrained task budget. When the function returns, the budget
 /// is reset to the value prior to calling the function.
 #[inline(always)]
 pub(crate) fn with_unconstrained<R>(f: impl FnOnce() -> R) -> R {
@@ -85,54 +82,60 @@ pub(crate) fn with_unconstrained<R>(f: impl FnOnce() -> R) -> R {
 
 #[inline(always)]
 fn with_budget<R>(budget: Budget, f: impl FnOnce() -> R) -> R {
-    struct ResetGuard<'a> {
-        cell: &'a Cell<Budget>,
+    struct ResetGuard {
         prev: Budget,
     }
 
-    impl<'a> Drop for ResetGuard<'a> {
+    impl Drop for ResetGuard {
         fn drop(&mut self) {
-            self.cell.set(self.prev);
+            let _ = context::budget(|cell| {
+                cell.set(self.prev);
+            });
         }
     }
 
-    CURRENT.with(move |cell| {
+    #[allow(unused_variables)]
+    let maybe_guard = context::budget(|cell| {
         let prev = cell.get();
-
         cell.set(budget);
 
-        let _guard = ResetGuard { cell, prev };
+        ResetGuard { prev }
+    });
+
+    // The function is called regardless even if the budget is not successfully
+    // set due to the thread-local being destroyed.
+    f()
+}
 
-        f()
-    })
+#[inline(always)]
+pub(crate) fn has_budget_remaining() -> bool {
+    // If the current budget cannot be accessed due to the thread-local being
+    // shutdown, then we assume there is budget remaining.
+    context::budget(|cell| cell.get().has_remaining()).unwrap_or(true)
 }
 
 cfg_rt_multi_thread! {
-    /// Set the current task's budget
+    /// Sets the current task's budget.
     pub(crate) fn set(budget: Budget) {
-        CURRENT.with(|cell| cell.set(budget))
-    }
-
-    #[inline(always)]
-    pub(crate) fn has_budget_remaining() -> bool {
-        CURRENT.with(|cell| cell.get().has_remaining())
+        let _ = context::budget(|cell| cell.set(budget));
     }
 }
 
 cfg_rt! {
-    /// Forcibly remove the budgeting constraints early.
+    /// Forcibly removes the budgeting constraints early.
     ///
     /// Returns the remaining budget
     pub(crate) fn stop() -> Budget {
-        CURRENT.with(|cell| {
+        context::budget(|cell| {
             let prev = cell.get();
             cell.set(Budget::unconstrained());
             prev
-        })
+        }).unwrap_or(Budget::unconstrained())
     }
 }
 
 cfg_coop! {
+    use std::cell::Cell;
     use std::task::{Context, Poll};
 
     #[must_use]
@@ -150,7 +153,7 @@ cfg_coop! {
             // They are both represented as the remembered budget being unconstrained.
             let budget = self.0.get();
             if !budget.is_unconstrained() {
-                CURRENT.with(|cell| {
+                let _ = context::budget(|cell| {
                     cell.set(budget);
                 });
             }
@@ -171,33 +174,65 @@ cfg_coop! {
     /// that progress was made.
     #[inline]
     pub(crate) fn poll_proceed(cx: &mut Context<'_>) -> Poll<RestoreOnPending> {
-        CURRENT.with(|cell| {
+        context::budget(|cell| {
             let mut budget = cell.get();
 
-            if budget.decrement() {
+            let decrement = budget.decrement();
+
+            if decrement.success {
                 let restore = RestoreOnPending(Cell::new(cell.get()));
                 cell.set(budget);
+
+                // avoid double counting
+                if decrement.hit_zero {
+                    inc_budget_forced_yield_count();
+                }
+
                 Poll::Ready(restore)
             } else {
                 cx.waker().wake_by_ref();
                 Poll::Pending
             }
-        })
+        }).unwrap_or(Poll::Ready(RestoreOnPending(Cell::new(Budget::unconstrained()))))
+    }
+
+    cfg_rt! {
+        cfg_metrics! {
+            #[inline(always)]
+            fn inc_budget_forced_yield_count() {
+                let _ = context::with_current(|handle| {
+                    handle.scheduler_metrics().inc_budget_forced_yield_count();
+                });
+            }
+        }
+
+        cfg_not_metrics! {
+            #[inline(always)]
+            fn inc_budget_forced_yield_count() {}
+        }
+    }
+
+    cfg_not_rt! {
+        #[inline(always)]
+        fn inc_budget_forced_yield_count() {}
     }
 
     impl Budget {
-        /// Decrement the budget. Returns `true` if successful. Decrementing fails
+        /// Decrements the budget. Returns `true` if successful. Decrementing fails
         /// when there is not enough remaining budget.
-        fn decrement(&mut self) -> bool {
+        fn decrement(&mut self) -> BudgetDecrement {
             if let Some(num) = &mut self.0 {
                 if *num > 0 {
                     *num -= 1;
-                    true
+
+                    let hit_zero = *num == 0;
+
+                    BudgetDecrement { success: true, hit_zero }
                 } else {
-                    false
+                    BudgetDecrement { success: false, hit_zero: false }
                 }
             } else {
-                true
+                BudgetDecrement { success: true, hit_zero: false }
             }
         }
 
@@ -211,12 +246,15 @@ cfg_coop! {
 mod test {
     use super::*;
 
+    #[cfg(tokio_wasm_not_wasi)]
+    use wasm_bindgen_test::wasm_bindgen_test as test;
+
     fn get() -> Budget {
-        CURRENT.with(|cell| cell.get())
+        context::budget(|cell| cell.get()).unwrap_or(Budget::unconstrained())
     }
 
     #[test]
-    fn bugeting() {
+    fn budgeting() {
         use futures::future::poll_fn;
         use tokio_test::*;
 
diff --git a/vendor/tokio/src/runtime/driver.rs b/vendor/tokio/src/runtime/driver.rs
index 7e459779b..572fdefb0 100644
--- a/vendor/tokio/src/runtime/driver.rs
+++ b/vendor/tokio/src/runtime/driver.rs
@@ -1,63 +1,233 @@
 //! Abstracts out the entire chain of runtime sub-drivers into common types.
-use crate::park::thread::ParkThread;
-use crate::park::Park;
+
+// Eventually, this file will see significant refactoring / cleanup. For now, we
+// don't need to worry much about dead code with certain feature permutations.
+#![cfg_attr(not(feature = "full"), allow(dead_code))]
+
+use crate::runtime::park::{ParkThread, UnparkThread};
 
 use std::io;
 use std::time::Duration;
 
+#[derive(Debug)]
+pub(crate) struct Driver {
+    inner: TimeDriver,
+}
+
+#[derive(Debug)]
+pub(crate) struct Handle {
+    /// IO driver handle
+    pub(crate) io: IoHandle,
+
+    /// Signal driver handle
+    #[cfg_attr(any(not(unix), loom), allow(dead_code))]
+    pub(crate) signal: SignalHandle,
+
+    /// Time driver handle
+    pub(crate) time: TimeHandle,
+
+    /// Source of `Instant::now()`
+    #[cfg_attr(not(all(feature = "time", feature = "test-util")), allow(dead_code))]
+    pub(crate) clock: Clock,
+}
+
+pub(crate) struct Cfg {
+    pub(crate) enable_io: bool,
+    pub(crate) enable_time: bool,
+    pub(crate) enable_pause_time: bool,
+    pub(crate) start_paused: bool,
+    pub(crate) nevents: usize,
+}
+
+impl Driver {
+    pub(crate) fn new(cfg: Cfg) -> io::Result<(Self, Handle)> {
+        let (io_stack, io_handle, signal_handle) = create_io_stack(cfg.enable_io, cfg.nevents)?;
+
+        let clock = create_clock(cfg.enable_pause_time, cfg.start_paused);
+
+        let (time_driver, time_handle) = create_time_driver(cfg.enable_time, io_stack, &clock);
+
+        Ok((
+            Self { inner: time_driver },
+            Handle {
+                io: io_handle,
+                signal: signal_handle,
+                time: time_handle,
+                clock,
+            },
+        ))
+    }
+
+    pub(crate) fn park(&mut self, handle: &Handle) {
+        self.inner.park(handle)
+    }
+
+    pub(crate) fn park_timeout(&mut self, handle: &Handle, duration: Duration) {
+        self.inner.park_timeout(handle, duration)
+    }
+
+    pub(crate) fn shutdown(&mut self, handle: &Handle) {
+        self.inner.shutdown(handle)
+    }
+}
+
+impl Handle {
+    pub(crate) fn unpark(&self) {
+        #[cfg(feature = "time")]
+        if let Some(handle) = &self.time {
+            handle.unpark();
+        }
+
+        self.io.unpark();
+    }
+
+    cfg_io_driver! {
+        #[track_caller]
+        pub(crate) fn io(&self) -> &crate::runtime::io::Handle {
+            self.io
+                .as_ref()
+                .expect("A Tokio 1.x context was found, but IO is disabled. Call `enable_io` on the runtime builder to enable IO.")
+        }
+    }
+
+    cfg_signal_internal_and_unix! {
+        #[track_caller]
+        pub(crate) fn signal(&self) -> &crate::runtime::signal::Handle {
+            self.signal
+                .as_ref()
+                .expect("there is no signal driver running, must be called from the context of Tokio runtime")
+        }
+    }
+
+    cfg_time! {
+        /// Returns a reference to the time driver handle.
+        ///
+        /// Panics if no time driver is present.
+        #[track_caller]
+        pub(crate) fn time(&self) -> &crate::runtime::time::Handle {
+            self.time
+                .as_ref()
+                .expect("A Tokio 1.x context was found, but timers are disabled. Call `enable_time` on the runtime builder to enable timers.")
+        }
+
+        pub(crate) fn clock(&self) -> &Clock {
+            &self.clock
+        }
+    }
+}
+
 // ===== io driver =====
 
 cfg_io_driver! {
-    type IoDriver = crate::io::driver::Driver;
-    type IoStack = crate::park::either::Either<ProcessDriver, ParkThread>;
-    pub(crate) type IoHandle = Option<crate::io::driver::Handle>;
+    pub(crate) type IoDriver = crate::runtime::io::Driver;
 
-    fn create_io_stack(enabled: bool) -> io::Result<(IoStack, IoHandle, SignalHandle)> {
-        use crate::park::either::Either;
+    #[derive(Debug)]
+    pub(crate) enum IoStack {
+        Enabled(ProcessDriver),
+        Disabled(ParkThread),
+    }
+
+    #[derive(Debug)]
+    pub(crate) enum IoHandle {
+        Enabled(crate::runtime::io::Handle),
+        Disabled(UnparkThread),
+    }
 
+    fn create_io_stack(enabled: bool, nevents: usize) -> io::Result<(IoStack, IoHandle, SignalHandle)> {
         #[cfg(loom)]
         assert!(!enabled);
 
         let ret = if enabled {
-            let io_driver = crate::io::driver::Driver::new()?;
-            let io_handle = io_driver.handle();
+            let (io_driver, io_handle) = crate::runtime::io::Driver::new(nevents)?;
 
-            let (signal_driver, signal_handle) = create_signal_driver(io_driver)?;
+            let (signal_driver, signal_handle) = create_signal_driver(io_driver, &io_handle)?;
             let process_driver = create_process_driver(signal_driver);
 
-            (Either::A(process_driver), Some(io_handle), signal_handle)
+            (IoStack::Enabled(process_driver), IoHandle::Enabled(io_handle), signal_handle)
         } else {
-            (Either::B(ParkThread::new()), Default::default(), Default::default())
+            let park_thread = ParkThread::new();
+            let unpark_thread = park_thread.unpark();
+            (IoStack::Disabled(park_thread), IoHandle::Disabled(unpark_thread), Default::default())
         };
 
         Ok(ret)
     }
+
+    impl IoStack {
+        pub(crate) fn park(&mut self, handle: &Handle) {
+            match self {
+                IoStack::Enabled(v) => v.park(handle),
+                IoStack::Disabled(v) => v.park(),
+            }
+        }
+
+        pub(crate) fn park_timeout(&mut self, handle: &Handle, duration: Duration) {
+            match self {
+                IoStack::Enabled(v) => v.park_timeout(handle, duration),
+                IoStack::Disabled(v) => v.park_timeout(duration),
+            }
+        }
+
+        pub(crate) fn shutdown(&mut self, handle: &Handle) {
+            match self {
+                IoStack::Enabled(v) => v.shutdown(handle),
+                IoStack::Disabled(v) => v.shutdown(),
+            }
+        }
+    }
+
+    impl IoHandle {
+        pub(crate) fn unpark(&self) {
+            match self {
+                IoHandle::Enabled(handle) => handle.unpark(),
+                IoHandle::Disabled(handle) => handle.unpark(),
+            }
+        }
+
+        pub(crate) fn as_ref(&self) -> Option<&crate::runtime::io::Handle> {
+            match self {
+                IoHandle::Enabled(v) => Some(v),
+                IoHandle::Disabled(..) => None,
+            }
+        }
+    }
 }
 
 cfg_not_io_driver! {
-    pub(crate) type IoHandle = ();
-    type IoStack = ParkThread;
+    pub(crate) type IoHandle = UnparkThread;
+
+    #[derive(Debug)]
+    pub(crate) struct IoStack(ParkThread);
 
-    fn create_io_stack(_enabled: bool) -> io::Result<(IoStack, IoHandle, SignalHandle)> {
-        Ok((ParkThread::new(), Default::default(), Default::default()))
+    fn create_io_stack(_enabled: bool, _nevents: usize) -> io::Result<(IoStack, IoHandle, SignalHandle)> {
+        let park_thread = ParkThread::new();
+        let unpark_thread = park_thread.unpark();
+        Ok((IoStack(park_thread), unpark_thread, Default::default()))
     }
-}
 
-// ===== signal driver =====
+    impl IoStack {
+        pub(crate) fn park(&mut self, _handle: &Handle) {
+            self.0.park();
+        }
+
+        pub(crate) fn park_timeout(&mut self, _handle: &Handle, duration: Duration) {
+            self.0.park_timeout(duration);
+        }
 
-macro_rules! cfg_signal_internal_and_unix {
-    ($($item:item)*) => {
-        #[cfg(unix)]
-        cfg_signal_internal! { $($item)* }
+        pub(crate) fn shutdown(&mut self, _handle: &Handle) {
+            self.0.shutdown();
+        }
     }
 }
 
+// ===== signal driver =====
+
 cfg_signal_internal_and_unix! {
-    type SignalDriver = crate::signal::unix::driver::Driver;
-    pub(crate) type SignalHandle = Option<crate::signal::unix::driver::Handle>;
+    type SignalDriver = crate::runtime::signal::Driver;
+    pub(crate) type SignalHandle = Option<crate::runtime::signal::Handle>;
 
-    fn create_signal_driver(io_driver: IoDriver) -> io::Result<(SignalDriver, SignalHandle)> {
-        let driver = crate::signal::unix::driver::Driver::new(io_driver)?;
+    fn create_signal_driver(io_driver: IoDriver, io_handle: &crate::runtime::io::Handle) -> io::Result<(SignalDriver, SignalHandle)> {
+        let driver = crate::runtime::signal::Driver::new(io_driver, io_handle)?;
         let handle = driver.handle();
         Ok((driver, Some(handle)))
     }
@@ -69,7 +239,7 @@ cfg_not_signal_internal! {
     cfg_io_driver! {
         type SignalDriver = IoDriver;
 
-        fn create_signal_driver(io_driver: IoDriver) -> io::Result<(SignalDriver, SignalHandle)> {
+        fn create_signal_driver(io_driver: IoDriver, _io_handle: &crate::runtime::io::Handle) -> io::Result<(SignalDriver, SignalHandle)> {
             Ok((io_driver, ()))
         }
     }
@@ -78,10 +248,10 @@ cfg_not_signal_internal! {
 // ===== process driver =====
 
 cfg_process_driver! {
-    type ProcessDriver = crate::process::unix::driver::Driver;
+    type ProcessDriver = crate::runtime::process::Driver;
 
     fn create_process_driver(signal_driver: SignalDriver) -> ProcessDriver {
-        crate::process::unix::driver::Driver::new(signal_driver)
+        ProcessDriver::new(signal_driver)
     }
 }
 
@@ -98,10 +268,16 @@ cfg_not_process_driver! {
 // ===== time driver =====
 
 cfg_time! {
-    type TimeDriver = crate::park::either::Either<crate::time::driver::Driver<IoStack>, IoStack>;
+    #[derive(Debug)]
+    pub(crate) enum TimeDriver {
+        Enabled {
+            driver: crate::runtime::time::Driver,
+        },
+        Disabled(IoStack),
+    }
 
     pub(crate) type Clock = crate::time::Clock;
-    pub(crate) type TimeHandle = Option<crate::time::driver::Handle>;
+    pub(crate) type TimeHandle = Option<crate::runtime::time::Handle>;
 
     fn create_clock(enable_pausing: bool, start_paused: bool) -> Clock {
         crate::time::Clock::new(enable_pausing, start_paused)
@@ -110,17 +286,37 @@ cfg_time! {
     fn create_time_driver(
         enable: bool,
         io_stack: IoStack,
-        clock: Clock,
+        clock: &Clock,
     ) -> (TimeDriver, TimeHandle) {
-        use crate::park::either::Either;
-
         if enable {
-            let driver = crate::time::driver::Driver::new(io_stack, clock);
-            let handle = driver.handle();
+            let (driver, handle) = crate::runtime::time::Driver::new(io_stack, clock);
 
-            (Either::A(driver), Some(handle))
+            (TimeDriver::Enabled { driver }, Some(handle))
         } else {
-            (Either::B(io_stack), None)
+            (TimeDriver::Disabled(io_stack), None)
+        }
+    }
+
+    impl TimeDriver {
+        pub(crate) fn park(&mut self, handle: &Handle) {
+            match self {
+                TimeDriver::Enabled { driver, .. } => driver.park(handle),
+                TimeDriver::Disabled(v) => v.park(handle),
+            }
+        }
+
+        pub(crate) fn park_timeout(&mut self, handle: &Handle, duration: Duration) {
+            match self {
+                TimeDriver::Enabled { driver } => driver.park_timeout(handle, duration),
+                TimeDriver::Disabled(v) => v.park_timeout(handle, duration),
+            }
+        }
+
+        pub(crate) fn shutdown(&mut self, handle: &Handle) {
+            match self {
+                TimeDriver::Enabled { driver } => driver.shutdown(handle),
+                TimeDriver::Disabled(v) => v.shutdown(handle),
+            }
         }
     }
 }
@@ -138,71 +334,8 @@ cfg_not_time! {
     fn create_time_driver(
         _enable: bool,
         io_stack: IoStack,
-        _clock: Clock,
+        _clock: &Clock,
     ) -> (TimeDriver, TimeHandle) {
         (io_stack, ())
     }
 }
-
-// ===== runtime driver =====
-
-#[derive(Debug)]
-pub(crate) struct Driver {
-    inner: TimeDriver,
-}
-
-pub(crate) struct Resources {
-    pub(crate) io_handle: IoHandle,
-    pub(crate) signal_handle: SignalHandle,
-    pub(crate) time_handle: TimeHandle,
-    pub(crate) clock: Clock,
-}
-
-pub(crate) struct Cfg {
-    pub(crate) enable_io: bool,
-    pub(crate) enable_time: bool,
-    pub(crate) enable_pause_time: bool,
-    pub(crate) start_paused: bool,
-}
-
-impl Driver {
-    pub(crate) fn new(cfg: Cfg) -> io::Result<(Self, Resources)> {
-        let (io_stack, io_handle, signal_handle) = create_io_stack(cfg.enable_io)?;
-
-        let clock = create_clock(cfg.enable_pause_time, cfg.start_paused);
-
-        let (time_driver, time_handle) =
-            create_time_driver(cfg.enable_time, io_stack, clock.clone());
-
-        Ok((
-            Self { inner: time_driver },
-            Resources {
-                io_handle,
-                signal_handle,
-                time_handle,
-                clock,
-            },
-        ))
-    }
-}
-
-impl Park for Driver {
-    type Unpark = <TimeDriver as Park>::Unpark;
-    type Error = <TimeDriver as Park>::Error;
-
-    fn unpark(&self) -> Self::Unpark {
-        self.inner.unpark()
-    }
-
-    fn park(&mut self) -> Result<(), Self::Error> {
-        self.inner.park()
-    }
-
-    fn park_timeout(&mut self, duration: Duration) -> Result<(), Self::Error> {
-        self.inner.park_timeout(duration)
-    }
-
-    fn shutdown(&mut self) {
-        self.inner.shutdown()
-    }
-}
diff --git a/vendor/tokio/src/runtime/dump.rs b/vendor/tokio/src/runtime/dump.rs
new file mode 100644
index 000000000..994b7f9c0
--- /dev/null
+++ b/vendor/tokio/src/runtime/dump.rs
@@ -0,0 +1,76 @@
+//! Snapshots of runtime state.
+//!
+//! See [Handle::dump][crate::runtime::Handle::dump].
+
+use std::fmt;
+
+/// A snapshot of a runtime's state.
+///
+/// See [Handle::dump][crate::runtime::Handle::dump].
+#[derive(Debug)]
+pub struct Dump {
+    tasks: Tasks,
+}
+
+/// Snapshots of tasks.
+///
+/// See [Handle::dump][crate::runtime::Handle::dump].
+#[derive(Debug)]
+pub struct Tasks {
+    tasks: Vec<Task>,
+}
+
+/// A snapshot of a task.
+///
+/// See [Handle::dump][crate::runtime::Handle::dump].
+#[derive(Debug)]
+pub struct Task {
+    trace: Trace,
+}
+
+/// An execution trace of a task's last poll.
+///
+/// See [Handle::dump][crate::runtime::Handle::dump].
+#[derive(Debug)]
+pub struct Trace {
+    inner: super::task::trace::Trace,
+}
+
+impl Dump {
+    pub(crate) fn new(tasks: Vec<Task>) -> Self {
+        Self {
+            tasks: Tasks { tasks },
+        }
+    }
+
+    /// Tasks in this snapshot.
+    pub fn tasks(&self) -> &Tasks {
+        &self.tasks
+    }
+}
+
+impl Tasks {
+    /// Iterate over tasks.
+    pub fn iter(&self) -> impl Iterator<Item = &Task> {
+        self.tasks.iter()
+    }
+}
+
+impl Task {
+    pub(crate) fn new(trace: super::task::trace::Trace) -> Self {
+        Self {
+            trace: Trace { inner: trace },
+        }
+    }
+
+    /// A trace of this task's state.
+    pub fn trace(&self) -> &Trace {
+        &self.trace
+    }
+}
+
+impl fmt::Display for Trace {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.inner.fmt(f)
+    }
+}
diff --git a/vendor/tokio/src/runtime/enter.rs b/vendor/tokio/src/runtime/enter.rs
deleted file mode 100644
index e91408f38..000000000
--- a/vendor/tokio/src/runtime/enter.rs
+++ /dev/null
@@ -1,205 +0,0 @@
-use std::cell::{Cell, RefCell};
-use std::fmt;
-use std::marker::PhantomData;
-
-#[derive(Debug, Clone, Copy)]
-pub(crate) enum EnterContext {
-    #[cfg_attr(not(feature = "rt"), allow(dead_code))]
-    Entered {
-        allow_blocking: bool,
-    },
-    NotEntered,
-}
-
-impl EnterContext {
-    pub(crate) fn is_entered(self) -> bool {
-        matches!(self, EnterContext::Entered { .. })
-    }
-}
-
-thread_local!(static ENTERED: Cell<EnterContext> = Cell::new(EnterContext::NotEntered));
-
-/// Represents an executor context.
-pub(crate) struct Enter {
-    _p: PhantomData<RefCell<()>>,
-}
-
-cfg_rt! {
-    use crate::park::thread::ParkError;
-
-    use std::time::Duration;
-
-    /// Marks the current thread as being within the dynamic extent of an
-    /// executor.
-    pub(crate) fn enter(allow_blocking: bool) -> Enter {
-        if let Some(enter) = try_enter(allow_blocking) {
-            return enter;
-        }
-
-        panic!(
-            "Cannot start a runtime from within a runtime. This happens \
-            because a function (like `block_on`) attempted to block the \
-            current thread while the thread is being used to drive \
-            asynchronous tasks."
-        );
-    }
-
-    /// Tries to enter a runtime context, returns `None` if already in a runtime
-    /// context.
-    pub(crate) fn try_enter(allow_blocking: bool) -> Option<Enter> {
-        ENTERED.with(|c| {
-            if c.get().is_entered() {
-                None
-            } else {
-                c.set(EnterContext::Entered { allow_blocking });
-                Some(Enter { _p: PhantomData })
-            }
-        })
-    }
-}
-
-// Forces the current "entered" state to be cleared while the closure
-// is executed.
-//
-// # Warning
-//
-// This is hidden for a reason. Do not use without fully understanding
-// executors. Misusing can easily cause your program to deadlock.
-cfg_rt_multi_thread! {
-    pub(crate) fn exit<F: FnOnce() -> R, R>(f: F) -> R {
-        // Reset in case the closure panics
-        struct Reset(EnterContext);
-        impl Drop for Reset {
-            fn drop(&mut self) {
-                ENTERED.with(|c| {
-                    assert!(!c.get().is_entered(), "closure claimed permanent executor");
-                    c.set(self.0);
-                });
-            }
-        }
-
-        let was = ENTERED.with(|c| {
-            let e = c.get();
-            assert!(e.is_entered(), "asked to exit when not entered");
-            c.set(EnterContext::NotEntered);
-            e
-        });
-
-        let _reset = Reset(was);
-        // dropping _reset after f() will reset ENTERED
-        f()
-    }
-}
-
-cfg_rt! {
-    /// Disallow blocking in the current runtime context until the guard is dropped.
-    pub(crate) fn disallow_blocking() -> DisallowBlockingGuard {
-        let reset = ENTERED.with(|c| {
-            if let EnterContext::Entered {
-                allow_blocking: true,
-            } = c.get()
-            {
-                c.set(EnterContext::Entered {
-                    allow_blocking: false,
-                });
-                true
-            } else {
-                false
-            }
-        });
-        DisallowBlockingGuard(reset)
-    }
-
-    pub(crate) struct DisallowBlockingGuard(bool);
-    impl Drop for DisallowBlockingGuard {
-        fn drop(&mut self) {
-            if self.0 {
-                // XXX: Do we want some kind of assertion here, or is "best effort" okay?
-                ENTERED.with(|c| {
-                    if let EnterContext::Entered {
-                        allow_blocking: false,
-                    } = c.get()
-                    {
-                        c.set(EnterContext::Entered {
-                            allow_blocking: true,
-                        });
-                    }
-                })
-            }
-        }
-    }
-}
-
-cfg_rt_multi_thread! {
-    /// Returns true if in a runtime context.
-    pub(crate) fn context() -> EnterContext {
-        ENTERED.with(|c| c.get())
-    }
-}
-
-cfg_rt! {
-    impl Enter {
-        /// Blocks the thread on the specified future, returning the value with
-        /// which that future completes.
-        pub(crate) fn block_on<F>(&mut self, f: F) -> Result<F::Output, ParkError>
-        where
-            F: std::future::Future,
-        {
-            use crate::park::thread::CachedParkThread;
-
-            let mut park = CachedParkThread::new();
-            park.block_on(f)
-        }
-
-        /// Blocks the thread on the specified future for **at most** `timeout`
-        ///
-        /// If the future completes before `timeout`, the result is returned. If
-        /// `timeout` elapses, then `Err` is returned.
-        pub(crate) fn block_on_timeout<F>(&mut self, f: F, timeout: Duration) -> Result<F::Output, ParkError>
-        where
-            F: std::future::Future,
-        {
-            use crate::park::Park;
-            use crate::park::thread::CachedParkThread;
-            use std::task::Context;
-            use std::task::Poll::Ready;
-            use std::time::Instant;
-
-            let mut park = CachedParkThread::new();
-            let waker = park.get_unpark()?.into_waker();
-            let mut cx = Context::from_waker(&waker);
-
-            pin!(f);
-            let when = Instant::now() + timeout;
-
-            loop {
-                if let Ready(v) = crate::coop::budget(|| f.as_mut().poll(&mut cx)) {
-                    return Ok(v);
-                }
-
-                let now = Instant::now();
-
-                if now >= when {
-                    return Err(());
-                }
-
-                park.park_timeout(when - now)?;
-            }
-        }
-    }
-}
-
-impl fmt::Debug for Enter {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.debug_struct("Enter").finish()
-    }
-}
-
-impl Drop for Enter {
-    fn drop(&mut self) {
-        ENTERED.with(|c| {
-            assert!(c.get().is_entered());
-            c.set(EnterContext::NotEntered);
-        });
-    }
-}
diff --git a/vendor/tokio/src/runtime/handle.rs b/vendor/tokio/src/runtime/handle.rs
index 7dff91448..be4743d47 100644
--- a/vendor/tokio/src/runtime/handle.rs
+++ b/vendor/tokio/src/runtime/handle.rs
@@ -1,10 +1,4 @@
-use crate::runtime::blocking::task::BlockingTask;
-use crate::runtime::task::{self, JoinHandle};
-use crate::runtime::{blocking, context, driver, Spawner};
-use crate::util::error::CONTEXT_MISSING_ERROR;
-
-use std::future::Future;
-use std::{error, fmt};
+use crate::runtime::{context, scheduler, RuntimeFlavor};
 
 /// Handle to the runtime.
 ///
@@ -13,24 +7,18 @@ use std::{error, fmt};
 ///
 /// [`Runtime::handle`]: crate::runtime::Runtime::handle()
 #[derive(Debug, Clone)]
+// When the `rt` feature is *not* enabled, this type is still defined, but not
+// included in the public API.
 pub struct Handle {
-    pub(super) spawner: Spawner,
-
-    /// Handles to the I/O drivers
-    pub(super) io_handle: driver::IoHandle,
-
-    /// Handles to the signal drivers
-    pub(super) signal_handle: driver::SignalHandle,
-
-    /// Handles to the time drivers
-    pub(super) time_handle: driver::TimeHandle,
+    pub(crate) inner: scheduler::Handle,
+}
 
-    /// Source of `Instant::now()`
-    pub(super) clock: driver::Clock,
+use crate::runtime::task::JoinHandle;
+use crate::util::error::{CONTEXT_MISSING_ERROR, THREAD_LOCAL_DESTROYED_ERROR};
 
-    /// Blocking pool spawner
-    pub(super) blocking_spawner: blocking::Spawner,
-}
+use std::future::Future;
+use std::marker::PhantomData;
+use std::{error, fmt};
 
 /// Runtime context guard.
 ///
@@ -41,32 +29,72 @@ pub struct Handle {
 #[derive(Debug)]
 #[must_use = "Creating and dropping a guard does nothing"]
 pub struct EnterGuard<'a> {
-    handle: &'a Handle,
-    guard: context::EnterGuard,
+    _guard: context::SetCurrentGuard,
+    _handle_lifetime: PhantomData<&'a Handle>,
 }
 
 impl Handle {
-    /// Enter the runtime context. This allows you to construct types that must
-    /// have an executor available on creation such as [`Sleep`] or [`TcpStream`].
-    /// It will also allow you to call methods such as [`tokio::spawn`].
+    /// Enters the runtime context. This allows you to construct types that must
+    /// have an executor available on creation such as [`Sleep`] or
+    /// [`TcpStream`]. It will also allow you to call methods such as
+    /// [`tokio::spawn`] and [`Handle::current`] without panicking.
+    ///
+    /// # Panics
+    ///
+    /// When calling `Handle::enter` multiple times, the returned guards
+    /// **must** be dropped in the reverse order that they were acquired.
+    /// Failure to do so will result in a panic and possible memory leaks.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::runtime::Runtime;
+    ///
+    /// let rt = Runtime::new().unwrap();
+    ///
+    /// let _guard = rt.enter();
+    /// tokio::spawn(async {
+    ///     println!("Hello world!");
+    /// });
+    /// ```
+    ///
+    /// Do **not** do the following, this shows a scenario that will result in a
+    /// panic and possible memory leak.
+    ///
+    /// ```should_panic
+    /// use tokio::runtime::Runtime;
+    ///
+    /// let rt1 = Runtime::new().unwrap();
+    /// let rt2 = Runtime::new().unwrap();
+    ///
+    /// let enter1 = rt1.enter();
+    /// let enter2 = rt2.enter();
+    ///
+    /// drop(enter1);
+    /// drop(enter2);
+    /// ```
     ///
     /// [`Sleep`]: struct@crate::time::Sleep
     /// [`TcpStream`]: struct@crate::net::TcpStream
     /// [`tokio::spawn`]: fn@crate::spawn
     pub fn enter(&self) -> EnterGuard<'_> {
         EnterGuard {
-            handle: self,
-            guard: context::enter(self.clone()),
+            _guard: match context::try_set_current(&self.inner) {
+                Some(guard) => guard,
+                None => panic!("{}", crate::util::error::THREAD_LOCAL_DESTROYED_ERROR),
+            },
+            _handle_lifetime: PhantomData,
         }
     }
 
-    /// Returns a `Handle` view over the currently running `Runtime`
+    /// Returns a `Handle` view over the currently running `Runtime`.
     ///
-    /// # Panic
+    /// # Panics
     ///
     /// This will panic if called outside the context of a Tokio runtime. That means that you must
-    /// call this on one of the threads **being run by the runtime**. Calling this from within a
-    /// thread created by `std::thread::spawn` (for example) will cause a panic.
+    /// call this on one of the threads **being run by the runtime**, or from a thread with an active
+    /// `EnterGuard`. Calling this from within a thread created by `std::thread::spawn` (for example)
+    /// will cause a panic unless that thread has an active `EnterGuard`.
     ///
     /// # Examples
     ///
@@ -90,16 +118,24 @@ impl Handle {
     /// # let handle =
     /// thread::spawn(move || {
     ///     // Notice that the handle is created outside of this thread and then moved in
-    ///     handle.spawn(async { /* ... */ })
-    ///     // This next line would cause a panic
-    ///     // let handle2 = Handle::current();
+    ///     handle.spawn(async { /* ... */ });
+    ///     // This next line would cause a panic because we haven't entered the runtime
+    ///     // and created an EnterGuard
+    ///     // let handle2 = Handle::current(); // panic
+    ///     // So we create a guard here with Handle::enter();
+    ///     let _guard = handle.enter();
+    ///     // Now we can call Handle::current();
+    ///     let handle2 = Handle::current();
     /// });
     /// # handle.join().unwrap();
     /// # });
     /// # }
     /// ```
+    #[track_caller]
     pub fn current() -> Self {
-        context::current().expect(CONTEXT_MISSING_ERROR)
+        Handle {
+            inner: scheduler::Handle::current(),
+        }
     }
 
     /// Returns a Handle view over the currently running Runtime
@@ -108,15 +144,21 @@ impl Handle {
     ///
     /// Contrary to `current`, this never panics
     pub fn try_current() -> Result<Self, TryCurrentError> {
-        context::current().ok_or(TryCurrentError(()))
+        context::with_current(|inner| Handle {
+            inner: inner.clone(),
+        })
     }
 
-    /// Spawn a future onto the Tokio runtime.
+    /// Spawns a future onto the Tokio runtime.
     ///
     /// This spawns the given future onto the runtime's executor, usually a
     /// thread pool. The thread pool is then responsible for polling the future
     /// until it completes.
     ///
+    /// The provided future will start running in the background immediately
+    /// when `spawn` is called, even if you don't await the returned
+    /// `JoinHandle`.
+    ///
     /// See [module level][mod] documentation for more details.
     ///
     /// [mod]: index.html
@@ -138,18 +180,16 @@ impl Handle {
     /// });
     /// # }
     /// ```
-    #[cfg_attr(tokio_track_caller, track_caller)]
+    #[track_caller]
     pub fn spawn<F>(&self, future: F) -> JoinHandle<F::Output>
     where
         F: Future + Send + 'static,
         F::Output: Send + 'static,
     {
-        #[cfg(all(tokio_unstable, feature = "tracing"))]
-        let future = crate::util::trace::task(future, "task", None);
-        self.spawner.spawn(future)
+        self.spawn_named(future, None)
     }
 
-    /// Run the provided function on an executor dedicated to blocking
+    /// Runs the provided function on an executor dedicated to blocking
     /// operations.
     ///
     /// # Examples
@@ -168,57 +208,16 @@ impl Handle {
     ///     println!("now running on a worker thread");
     /// });
     /// # }
-    #[cfg_attr(tokio_track_caller, track_caller)]
+    #[track_caller]
     pub fn spawn_blocking<F, R>(&self, func: F) -> JoinHandle<R>
     where
         F: FnOnce() -> R + Send + 'static,
         R: Send + 'static,
     {
-        self.spawn_blocking_inner(func, None)
+        self.inner.blocking_spawner().spawn_blocking(self, func)
     }
 
-    #[cfg_attr(tokio_track_caller, track_caller)]
-    pub(crate) fn spawn_blocking_inner<F, R>(&self, func: F, name: Option<&str>) -> JoinHandle<R>
-    where
-        F: FnOnce() -> R + Send + 'static,
-        R: Send + 'static,
-    {
-        let fut = BlockingTask::new(func);
-
-        #[cfg(all(tokio_unstable, feature = "tracing"))]
-        let fut = {
-            use tracing::Instrument;
-            #[cfg(tokio_track_caller)]
-            let location = std::panic::Location::caller();
-            #[cfg(tokio_track_caller)]
-            let span = tracing::trace_span!(
-                target: "tokio::task",
-                "task",
-                kind = %"blocking",
-                function = %std::any::type_name::<F>(),
-                task.name = %name.unwrap_or_default(),
-                spawn.location = %format_args!("{}:{}:{}", location.file(), location.line(), location.column()),
-            );
-            #[cfg(not(tokio_track_caller))]
-            let span = tracing::trace_span!(
-                target: "tokio::task",
-                "task",
-                kind = %"blocking",
-                task.name = %name.unwrap_or_default(),
-                function = %std::any::type_name::<F>(),
-            );
-            fut.instrument(span)
-        };
-
-        #[cfg(not(all(tokio_unstable, feature = "tracing")))]
-        let _ = name;
-
-        let (task, handle) = task::joinable(fut);
-        let _ = self.blocking_spawner.spawn(task, &self);
-        handle
-    }
-
-    /// Run a future to completion on this `Handle`'s associated `Runtime`.
+    /// Runs a future to completion on this `Handle`'s associated `Runtime`.
     ///
     /// This runs the given future on the current thread, blocking until it is
     /// complete, and yielding its resolved result. Any tasks or timers which
@@ -288,36 +287,300 @@ impl Handle {
     /// [`tokio::fs`]: crate::fs
     /// [`tokio::net`]: crate::net
     /// [`tokio::time`]: crate::time
+    #[track_caller]
     pub fn block_on<F: Future>(&self, future: F) -> F::Output {
-        // Enter the **runtime** context. This configures spawning, the current I/O driver, ...
-        let _rt_enter = self.enter();
+        #[cfg(all(
+            tokio_unstable,
+            tokio_taskdump,
+            feature = "rt",
+            target_os = "linux",
+            any(target_arch = "aarch64", target_arch = "x86", target_arch = "x86_64")
+        ))]
+        let future = super::task::trace::Trace::root(future);
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let future =
+            crate::util::trace::task(future, "block_on", None, super::task::Id::next().as_u64());
+
+        // Enter the runtime context. This sets the current driver handles and
+        // prevents blocking an existing runtime.
+        context::enter_runtime(&self.inner, true, |blocking| {
+            blocking.block_on(future).expect("failed to park thread")
+        })
+    }
 
-        // Enter a **blocking** context. This prevents blocking from a runtime.
-        let mut blocking_enter = crate::runtime::enter(true);
+    #[track_caller]
+    pub(crate) fn spawn_named<F>(&self, future: F, _name: Option<&str>) -> JoinHandle<F::Output>
+    where
+        F: Future + Send + 'static,
+        F::Output: Send + 'static,
+    {
+        let id = crate::runtime::task::Id::next();
+        #[cfg(all(
+            tokio_unstable,
+            tokio_taskdump,
+            feature = "rt",
+            target_os = "linux",
+            any(target_arch = "aarch64", target_arch = "x86", target_arch = "x86_64")
+        ))]
+        let future = super::task::trace::Trace::root(future);
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let future = crate::util::trace::task(future, "task", _name, id.as_u64());
+        self.inner.spawn(future, id)
+    }
 
-        // Block on the future
-        blocking_enter
-            .block_on(future)
-            .expect("failed to park thread")
+    /// Returns the flavor of the current `Runtime`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::runtime::{Handle, RuntimeFlavor};
+    ///
+    /// #[tokio::main(flavor = "current_thread")]
+    /// async fn main() {
+    ///   assert_eq!(RuntimeFlavor::CurrentThread, Handle::current().runtime_flavor());
+    /// }
+    /// ```
+    ///
+    /// ```
+    /// use tokio::runtime::{Handle, RuntimeFlavor};
+    ///
+    /// #[tokio::main(flavor = "multi_thread", worker_threads = 4)]
+    /// async fn main() {
+    ///   assert_eq!(RuntimeFlavor::MultiThread, Handle::current().runtime_flavor());
+    /// }
+    /// ```
+    pub fn runtime_flavor(&self) -> RuntimeFlavor {
+        match self.inner {
+            scheduler::Handle::CurrentThread(_) => RuntimeFlavor::CurrentThread,
+            #[cfg(all(feature = "rt-multi-thread", not(tokio_wasi)))]
+            scheduler::Handle::MultiThread(_) => RuntimeFlavor::MultiThread,
+        }
     }
+}
 
-    pub(crate) fn shutdown(mut self) {
-        self.spawner.shutdown();
+cfg_metrics! {
+    use crate::runtime::RuntimeMetrics;
+
+    impl Handle {
+        /// Returns a view that lets you get information about how the runtime
+        /// is performing.
+        pub fn metrics(&self) -> RuntimeMetrics {
+            RuntimeMetrics::new(self.clone())
+        }
+    }
+}
+
+cfg_taskdump! {
+    impl Handle {
+        /// Captures a snapshot of the runtime's state.
+        ///
+        /// This functionality is experimental, and comes with a number of
+        /// requirements and limitations.
+        ///
+        /// # Examples
+        ///
+        /// This can be used to get call traces of each task in the runtime.
+        /// Calls to `Handle::dump` should usually be enclosed in a
+        /// [timeout][crate::time::timeout], so that dumping does not escalate a
+        /// single blocked runtime thread into an entirely blocked runtime.
+        ///
+        /// ```
+        /// # use tokio::runtime::Runtime;
+        /// # fn dox() {
+        /// # let rt = Runtime::new().unwrap();
+        /// # rt.spawn(async {
+        /// use tokio::runtime::Handle;
+        /// use tokio::time::{timeout, Duration};
+        ///
+        /// // Inside an async block or function.
+        /// let handle = Handle::current();
+        /// if let Ok(dump) = timeout(Duration::from_secs(2), handle.dump()).await {
+        ///     for (i, task) in dump.tasks().iter().enumerate() {
+        ///         let trace = task.trace();
+        ///         println!("TASK {i}:");
+        ///         println!("{trace}\n");
+        ///     }
+        /// }
+        /// # });
+        /// # }
+        /// ```
+        ///
+        /// This produces highly detailed traces of tasks; e.g.:
+        ///
+        /// ```plain
+        /// TASK 0:
+        /// ╼ dump::main::{{closure}}::a::{{closure}} at /tokio/examples/dump.rs:18:20
+        /// └╼ dump::main::{{closure}}::b::{{closure}} at /tokio/examples/dump.rs:23:20
+        ///    └╼ dump::main::{{closure}}::c::{{closure}} at /tokio/examples/dump.rs:28:24
+        ///       └╼ tokio::sync::barrier::Barrier::wait::{{closure}} at /tokio/tokio/src/sync/barrier.rs:129:10
+        ///          └╼ <tokio::util::trace::InstrumentedAsyncOp<F> as core::future::future::Future>::poll at /tokio/tokio/src/util/trace.rs:77:46
+        ///             └╼ tokio::sync::barrier::Barrier::wait_internal::{{closure}} at /tokio/tokio/src/sync/barrier.rs:183:36
+        ///                └╼ tokio::sync::watch::Receiver<T>::changed::{{closure}} at /tokio/tokio/src/sync/watch.rs:604:55
+        ///                   └╼ tokio::sync::watch::changed_impl::{{closure}} at /tokio/tokio/src/sync/watch.rs:755:18
+        ///                      └╼ <tokio::sync::notify::Notified as core::future::future::Future>::poll at /tokio/tokio/src/sync/notify.rs:1103:9
+        ///                         └╼ tokio::sync::notify::Notified::poll_notified at /tokio/tokio/src/sync/notify.rs:996:32
+        /// ```
+        ///
+        /// # Requirements
+        ///
+        /// ## Debug Info Must Be Available
+        ///
+        /// To produce task traces, the application must **not** be compiled
+        /// with split debuginfo. On Linux, including debuginfo within the
+        /// application binary is the (correct) default. You can further ensure
+        /// this behavior with the following directive in your `Cargo.toml`:
+        ///
+        /// ```toml
+        /// [profile.*]
+        /// split-debuginfo = "off"
+        /// ```
+        ///
+        /// ## Unstable Features
+        ///
+        /// This functionality is **unstable**, and requires both the
+        /// `tokio_unstable` and `tokio_taskdump` cfg flags to be set.
+        ///
+        /// You can do this by setting the `RUSTFLAGS` environment variable
+        /// before invoking `cargo`; e.g.:
+        /// ```bash
+        /// RUSTFLAGS="--cfg tokio_unstable --cfg tokio_taskdump" cargo run --example dump
+        /// ```
+        ///
+        /// Or by [configuring][cargo-config] `rustflags` in
+        /// `.cargo/config.toml`:
+        /// ```text
+        /// [build]
+        /// rustflags = ["--cfg tokio_unstable", "--cfg tokio_taskdump"]
+        /// ```
+        ///
+        /// [cargo-config]:
+        ///     https://doc.rust-lang.org/cargo/reference/config.html
+        ///
+        /// ## Platform Requirements
+        ///
+        /// Task dumps are supported on Linux atop aarch64, x86 and x86_64.
+        ///
+        /// ## Current Thread Runtime Requirements
+        ///
+        /// On the `current_thread` runtime, task dumps may only be requested
+        /// from *within* the context of the runtime being dumped. Do not, for
+        /// example, await `Handle::dump()` on a different runtime.
+        ///
+        /// # Limitations
+        ///
+        /// ## Performance
+        ///
+        /// Although enabling the `tokio_taskdump` feature imposes virtually no
+        /// additional runtime overhead, actually calling `Handle::dump` is
+        /// expensive. The runtime must synchronize and pause its workers, then
+        /// re-poll every task in a special tracing mode. Avoid requesting dumps
+        /// often.
+        ///
+        /// ## Local Executors
+        ///
+        /// Tasks managed by local executors (e.g., `FuturesUnordered` and
+        /// [`LocalSet`][crate::task::LocalSet]) may not appear in task dumps.
+        ///
+        /// ## Non-Termination When Workers Are Blocked
+        ///
+        /// The future produced by `Handle::dump` may never produce `Ready` if
+        /// another runtime worker is blocked for more than 250ms. This may
+        /// occur if a dump is requested during shutdown, or if another runtime
+        /// worker is infinite looping or synchronously deadlocked. For these
+        /// reasons, task dumping should usually be paired with an explicit
+        /// [timeout][crate::time::timeout].
+        pub async fn dump(&self) -> crate::runtime::Dump {
+            match &self.inner {
+                scheduler::Handle::CurrentThread(handle) => handle.dump(),
+                #[cfg(all(feature = "rt-multi-thread", not(tokio_wasi)))]
+                scheduler::Handle::MultiThread(handle) => {
+                    // perform the trace in a separate thread so that the
+                    // trace itself does not appear in the taskdump.
+                    let handle = handle.clone();
+                    spawn_thread(async {
+                        let handle = handle;
+                        handle.dump().await
+                    }).await
+                },
+            }
+        }
+    }
+
+    cfg_rt_multi_thread! {
+        /// Spawn a new thread and asynchronously await on its result.
+        async fn spawn_thread<F>(f: F) -> <F as Future>::Output
+        where
+            F: Future + Send + 'static,
+            <F as Future>::Output: Send + 'static
+        {
+            let (tx, rx) = crate::sync::oneshot::channel();
+            crate::loom::thread::spawn(|| {
+                let rt = crate::runtime::Builder::new_current_thread().build().unwrap();
+                rt.block_on(async {
+                    let _ = tx.send(f.await);
+                });
+            });
+            rx.await.unwrap()
+        }
     }
 }
 
 /// Error returned by `try_current` when no Runtime has been started
-pub struct TryCurrentError(());
+#[derive(Debug)]
+pub struct TryCurrentError {
+    kind: TryCurrentErrorKind,
+}
+
+impl TryCurrentError {
+    pub(crate) fn new_no_context() -> Self {
+        Self {
+            kind: TryCurrentErrorKind::NoContext,
+        }
+    }
 
-impl fmt::Debug for TryCurrentError {
+    pub(crate) fn new_thread_local_destroyed() -> Self {
+        Self {
+            kind: TryCurrentErrorKind::ThreadLocalDestroyed,
+        }
+    }
+
+    /// Returns true if the call failed because there is currently no runtime in
+    /// the Tokio context.
+    pub fn is_missing_context(&self) -> bool {
+        matches!(self.kind, TryCurrentErrorKind::NoContext)
+    }
+
+    /// Returns true if the call failed because the Tokio context thread-local
+    /// had been destroyed. This can usually only happen if in the destructor of
+    /// other thread-locals.
+    pub fn is_thread_local_destroyed(&self) -> bool {
+        matches!(self.kind, TryCurrentErrorKind::ThreadLocalDestroyed)
+    }
+}
+
+enum TryCurrentErrorKind {
+    NoContext,
+    ThreadLocalDestroyed,
+}
+
+impl fmt::Debug for TryCurrentErrorKind {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.debug_struct("TryCurrentError").finish()
+        use TryCurrentErrorKind::*;
+        match self {
+            NoContext => f.write_str("NoContext"),
+            ThreadLocalDestroyed => f.write_str("ThreadLocalDestroyed"),
+        }
     }
 }
 
 impl fmt::Display for TryCurrentError {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.write_str(CONTEXT_MISSING_ERROR)
+        use TryCurrentErrorKind::*;
+        match self.kind {
+            NoContext => f.write_str(CONTEXT_MISSING_ERROR),
+            ThreadLocalDestroyed => f.write_str(THREAD_LOCAL_DESTROYED_ERROR),
+        }
     }
 }
 
diff --git a/vendor/tokio/src/runtime/io/metrics.rs b/vendor/tokio/src/runtime/io/metrics.rs
new file mode 100644
index 000000000..ec341efe6
--- /dev/null
+++ b/vendor/tokio/src/runtime/io/metrics.rs
@@ -0,0 +1,24 @@
+//! This file contains mocks of the metrics types used in the I/O driver.
+//!
+//! The reason these mocks don't live in `src/runtime/mock.rs` is because
+//! these need to be available in the case when `net` is enabled but
+//! `rt` is not.
+
+cfg_not_rt_and_metrics_and_net! {
+    #[derive(Default)]
+    pub(crate) struct IoDriverMetrics {}
+
+    impl IoDriverMetrics {
+        pub(crate) fn incr_fd_count(&self) {}
+        pub(crate) fn dec_fd_count(&self) {}
+        pub(crate) fn incr_ready_count_by(&self, _amt: u64) {}
+    }
+}
+
+cfg_net! {
+    cfg_rt! {
+        cfg_metrics! {
+            pub(crate) use crate::runtime::IoDriverMetrics;
+        }
+    }
+}
diff --git a/vendor/tokio/src/runtime/io/mod.rs b/vendor/tokio/src/runtime/io/mod.rs
new file mode 100644
index 000000000..2dd426f11
--- /dev/null
+++ b/vendor/tokio/src/runtime/io/mod.rs
@@ -0,0 +1,356 @@
+#![cfg_attr(not(all(feature = "rt", feature = "net")), allow(dead_code))]
+
+mod registration;
+pub(crate) use registration::Registration;
+
+mod scheduled_io;
+use scheduled_io::ScheduledIo;
+
+mod metrics;
+
+use crate::io::interest::Interest;
+use crate::io::ready::Ready;
+use crate::runtime::driver;
+use crate::util::slab::{self, Slab};
+use crate::{loom::sync::RwLock, util::bit};
+
+use metrics::IoDriverMetrics;
+
+use std::fmt;
+use std::io;
+use std::time::Duration;
+
+/// I/O driver, backed by Mio.
+pub(crate) struct Driver {
+    /// Tracks the number of times `turn` is called. It is safe for this to wrap
+    /// as it is mostly used to determine when to call `compact()`.
+    tick: u8,
+
+    /// True when an event with the signal token is received
+    signal_ready: bool,
+
+    /// Reuse the `mio::Events` value across calls to poll.
+    events: mio::Events,
+
+    /// Primary slab handle containing the state for each resource registered
+    /// with this driver.
+    resources: Slab<ScheduledIo>,
+
+    /// The system event queue.
+    poll: mio::Poll,
+}
+
+/// A reference to an I/O driver.
+pub(crate) struct Handle {
+    /// Registers I/O resources.
+    registry: mio::Registry,
+
+    /// Allocates `ScheduledIo` handles when creating new resources.
+    io_dispatch: RwLock<IoDispatcher>,
+
+    /// Used to wake up the reactor from a call to `turn`.
+    /// Not supported on Wasi due to lack of threading support.
+    #[cfg(not(tokio_wasi))]
+    waker: mio::Waker,
+
+    pub(crate) metrics: IoDriverMetrics,
+}
+
+#[derive(Debug)]
+pub(crate) struct ReadyEvent {
+    tick: u8,
+    pub(crate) ready: Ready,
+    is_shutdown: bool,
+}
+
+cfg_net_unix!(
+    impl ReadyEvent {
+        pub(crate) fn with_ready(&self, ready: Ready) -> Self {
+            Self {
+                ready,
+                tick: self.tick,
+                is_shutdown: self.is_shutdown,
+            }
+        }
+    }
+);
+
+struct IoDispatcher {
+    allocator: slab::Allocator<ScheduledIo>,
+    is_shutdown: bool,
+}
+
+#[derive(Debug, Eq, PartialEq, Clone, Copy)]
+enum Direction {
+    Read,
+    Write,
+}
+
+enum Tick {
+    Set(u8),
+    Clear(u8),
+}
+
+// TODO: Don't use a fake token. Instead, reserve a slot entry for the wakeup
+// token.
+const TOKEN_WAKEUP: mio::Token = mio::Token(1 << 31);
+const TOKEN_SIGNAL: mio::Token = mio::Token(1 + (1 << 31));
+
+const ADDRESS: bit::Pack = bit::Pack::least_significant(24);
+
+// Packs the generation value in the `readiness` field.
+//
+// The generation prevents a race condition where a slab slot is reused for a
+// new socket while the I/O driver is about to apply a readiness event. The
+// generation value is checked when setting new readiness. If the generation do
+// not match, then the readiness event is discarded.
+const GENERATION: bit::Pack = ADDRESS.then(7);
+
+fn _assert_kinds() {
+    fn _assert<T: Send + Sync>() {}
+
+    _assert::<Handle>();
+}
+
+// ===== impl Driver =====
+
+impl Driver {
+    /// Creates a new event loop, returning any error that happened during the
+    /// creation.
+    pub(crate) fn new(nevents: usize) -> io::Result<(Driver, Handle)> {
+        let poll = mio::Poll::new()?;
+        #[cfg(not(tokio_wasi))]
+        let waker = mio::Waker::new(poll.registry(), TOKEN_WAKEUP)?;
+        let registry = poll.registry().try_clone()?;
+
+        let slab = Slab::new();
+        let allocator = slab.allocator();
+
+        let driver = Driver {
+            tick: 0,
+            signal_ready: false,
+            events: mio::Events::with_capacity(nevents),
+            poll,
+            resources: slab,
+        };
+
+        let handle = Handle {
+            registry,
+            io_dispatch: RwLock::new(IoDispatcher::new(allocator)),
+            #[cfg(not(tokio_wasi))]
+            waker,
+            metrics: IoDriverMetrics::default(),
+        };
+
+        Ok((driver, handle))
+    }
+
+    pub(crate) fn park(&mut self, rt_handle: &driver::Handle) {
+        let handle = rt_handle.io();
+        self.turn(handle, None);
+    }
+
+    pub(crate) fn park_timeout(&mut self, rt_handle: &driver::Handle, duration: Duration) {
+        let handle = rt_handle.io();
+        self.turn(handle, Some(duration));
+    }
+
+    pub(crate) fn shutdown(&mut self, rt_handle: &driver::Handle) {
+        let handle = rt_handle.io();
+
+        if handle.shutdown() {
+            self.resources.for_each(|io| {
+                // If a task is waiting on the I/O resource, notify it that the
+                // runtime is being shutdown. And shutdown will clear all wakers.
+                io.shutdown();
+            });
+        }
+    }
+
+    fn turn(&mut self, handle: &Handle, max_wait: Option<Duration>) {
+        // How often to call `compact()` on the resource slab
+        const COMPACT_INTERVAL: u8 = 255;
+
+        self.tick = self.tick.wrapping_add(1);
+
+        if self.tick == COMPACT_INTERVAL {
+            self.resources.compact()
+        }
+
+        let events = &mut self.events;
+
+        // Block waiting for an event to happen, peeling out how many events
+        // happened.
+        match self.poll.poll(events, max_wait) {
+            Ok(_) => {}
+            Err(ref e) if e.kind() == io::ErrorKind::Interrupted => {}
+            #[cfg(tokio_wasi)]
+            Err(e) if e.kind() == io::ErrorKind::InvalidInput => {
+                // In case of wasm32_wasi this error happens, when trying to poll without subscriptions
+                // just return from the park, as there would be nothing, which wakes us up.
+            }
+            Err(e) => panic!("unexpected error when polling the I/O driver: {:?}", e),
+        }
+
+        // Process all the events that came in, dispatching appropriately
+        let mut ready_count = 0;
+        for event in events.iter() {
+            let token = event.token();
+
+            if token == TOKEN_WAKEUP {
+                // Nothing to do, the event is used to unblock the I/O driver
+            } else if token == TOKEN_SIGNAL {
+                self.signal_ready = true;
+            } else {
+                Self::dispatch(
+                    &mut self.resources,
+                    self.tick,
+                    token,
+                    Ready::from_mio(event),
+                );
+                ready_count += 1;
+            }
+        }
+
+        handle.metrics.incr_ready_count_by(ready_count);
+    }
+
+    fn dispatch(resources: &mut Slab<ScheduledIo>, tick: u8, token: mio::Token, ready: Ready) {
+        let addr = slab::Address::from_usize(ADDRESS.unpack(token.0));
+
+        let io = match resources.get(addr) {
+            Some(io) => io,
+            None => return,
+        };
+
+        let res = io.set_readiness(Some(token.0), Tick::Set(tick), |curr| curr | ready);
+
+        if res.is_err() {
+            // token no longer valid!
+            return;
+        }
+
+        io.wake(ready);
+    }
+}
+
+impl fmt::Debug for Driver {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "Driver")
+    }
+}
+
+impl Handle {
+    /// Forces a reactor blocked in a call to `turn` to wakeup, or otherwise
+    /// makes the next call to `turn` return immediately.
+    ///
+    /// This method is intended to be used in situations where a notification
+    /// needs to otherwise be sent to the main reactor. If the reactor is
+    /// currently blocked inside of `turn` then it will wake up and soon return
+    /// after this method has been called. If the reactor is not currently
+    /// blocked in `turn`, then the next call to `turn` will not block and
+    /// return immediately.
+    pub(crate) fn unpark(&self) {
+        #[cfg(not(tokio_wasi))]
+        self.waker.wake().expect("failed to wake I/O driver");
+    }
+
+    /// Registers an I/O resource with the reactor for a given `mio::Ready` state.
+    ///
+    /// The registration token is returned.
+    pub(super) fn add_source(
+        &self,
+        source: &mut impl mio::event::Source,
+        interest: Interest,
+    ) -> io::Result<slab::Ref<ScheduledIo>> {
+        let (address, shared) = self.allocate()?;
+
+        let token = GENERATION.pack(shared.generation(), ADDRESS.pack(address.as_usize(), 0));
+
+        self.registry
+            .register(source, mio::Token(token), interest.to_mio())?;
+
+        self.metrics.incr_fd_count();
+
+        Ok(shared)
+    }
+
+    /// Deregisters an I/O resource from the reactor.
+    pub(super) fn deregister_source(&self, source: &mut impl mio::event::Source) -> io::Result<()> {
+        self.registry.deregister(source)?;
+
+        self.metrics.dec_fd_count();
+
+        Ok(())
+    }
+
+    /// shutdown the dispatcher.
+    fn shutdown(&self) -> bool {
+        let mut io = self.io_dispatch.write().unwrap();
+        if io.is_shutdown {
+            return false;
+        }
+        io.is_shutdown = true;
+        true
+    }
+
+    fn allocate(&self) -> io::Result<(slab::Address, slab::Ref<ScheduledIo>)> {
+        let io = self.io_dispatch.read().unwrap();
+        if io.is_shutdown {
+            return Err(io::Error::new(
+                io::ErrorKind::Other,
+                crate::util::error::RUNTIME_SHUTTING_DOWN_ERROR,
+            ));
+        }
+        io.allocator.allocate().ok_or_else(|| {
+            io::Error::new(
+                io::ErrorKind::Other,
+                "reactor at max registered I/O resources",
+            )
+        })
+    }
+}
+
+impl fmt::Debug for Handle {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "Handle")
+    }
+}
+
+// ===== impl IoDispatcher =====
+
+impl IoDispatcher {
+    fn new(allocator: slab::Allocator<ScheduledIo>) -> Self {
+        Self {
+            allocator,
+            is_shutdown: false,
+        }
+    }
+}
+
+impl Direction {
+    pub(super) fn mask(self) -> Ready {
+        match self {
+            Direction::Read => Ready::READABLE | Ready::READ_CLOSED,
+            Direction::Write => Ready::WRITABLE | Ready::WRITE_CLOSED,
+        }
+    }
+}
+
+// Signal handling
+cfg_signal_internal_and_unix! {
+    impl Handle {
+        pub(crate) fn register_signal_receiver(&self, receiver: &mut mio::net::UnixStream) -> io::Result<()> {
+            self.registry.register(receiver, TOKEN_SIGNAL, mio::Interest::READABLE)?;
+            Ok(())
+        }
+    }
+
+    impl Driver {
+        pub(crate) fn consume_signal_ready(&mut self) -> bool {
+            let ret = self.signal_ready;
+            self.signal_ready = false;
+            ret
+        }
+    }
+}
diff --git a/vendor/tokio/src/io/driver/registration.rs b/vendor/tokio/src/runtime/io/registration.rs
index 7350be634..341fa0539 100644
--- a/vendor/tokio/src/io/driver/registration.rs
+++ b/vendor/tokio/src/runtime/io/registration.rs
@@ -1,6 +1,8 @@
 #![cfg_attr(not(feature = "net"), allow(dead_code))]
 
-use crate::io::driver::{Direction, Handle, Interest, ReadyEvent, ScheduledIo};
+use crate::io::interest::Interest;
+use crate::runtime::io::{Direction, Handle, ReadyEvent, ScheduledIo};
+use crate::runtime::scheduler;
 use crate::util::slab;
 
 use mio::event::Source;
@@ -42,8 +44,8 @@ cfg_io_driver! {
     /// [`poll_write_ready`]: method@Self::poll_write_ready`
     #[derive(Debug)]
     pub(crate) struct Registration {
-        /// Handle to the associated driver.
-        handle: Handle,
+        /// Handle to the associated runtime.
+        handle: scheduler::Handle,
 
         /// Reference to state stored by the driver.
         shared: slab::Ref<ScheduledIo>,
@@ -56,10 +58,8 @@ unsafe impl Sync for Registration {}
 // ===== impl Registration =====
 
 impl Registration {
-    /// Registers the I/O resource with the default reactor, for a specific
-    /// `Interest`. `new_with_interest` should be used over `new` when you need
-    /// control over the readiness state, such as when a file descriptor only
-    /// allows reads. This does not add `hup` or `error` so if you are
+    /// Registers the I/O resource with the reactor for the provided handle, for
+    /// a specific `Interest`. This does not add `hup` or `error` so if you are
     /// interested in those states, you will need to add them to the readiness
     /// state passed to this function.
     ///
@@ -67,19 +67,13 @@ impl Registration {
     ///
     /// - `Ok` if the registration happened successfully
     /// - `Err` if an error was encountered during registration
+    #[track_caller]
     pub(crate) fn new_with_interest_and_handle(
         io: &mut impl Source,
         interest: Interest,
-        handle: Handle,
+        handle: scheduler::Handle,
     ) -> io::Result<Registration> {
-        let shared = if let Some(inner) = handle.inner() {
-            inner.add_source(io, interest)?
-        } else {
-            return Err(io::Error::new(
-                io::ErrorKind::Other,
-                "failed to find event loop",
-            ));
-        };
+        let shared = handle.driver().io().add_source(io, interest)?;
 
         Ok(Registration { handle, shared })
     }
@@ -101,11 +95,7 @@ impl Registration {
     ///
     /// `Err` is returned if an error is encountered.
     pub(crate) fn deregister(&mut self, io: &mut impl Source) -> io::Result<()> {
-        let inner = match self.handle.inner() {
-            Some(inner) => inner,
-            None => return Err(io::Error::new(io::ErrorKind::Other, "reactor gone")),
-        };
-        inner.deregister_source(io)
+        self.handle().deregister_source(io)
     }
 
     pub(crate) fn clear_readiness(&self, event: ReadyEvent) {
@@ -126,6 +116,7 @@ impl Registration {
 
     // Uses the poll path, requiring the caller to ensure mutual exclusion for
     // correctness. Only the last task to call this function is notified.
+    #[cfg(not(tokio_wasi))]
     pub(crate) fn poll_read_io<R>(
         &self,
         cx: &mut Context<'_>,
@@ -153,11 +144,12 @@ impl Registration {
         cx: &mut Context<'_>,
         direction: Direction,
     ) -> Poll<io::Result<ReadyEvent>> {
+        ready!(crate::trace::trace_leaf(cx));
         // Keep track of task budget
-        let coop = ready!(crate::coop::poll_proceed(cx));
+        let coop = ready!(crate::runtime::coop::poll_proceed(cx));
         let ev = ready!(self.shared.poll_readiness(cx, direction));
 
-        if self.handle.inner().is_none() {
+        if ev.is_shutdown {
             return Poll::Ready(Err(gone()));
         }
 
@@ -206,6 +198,10 @@ impl Registration {
             res => res,
         }
     }
+
+    fn handle(&self) -> &Handle {
+        self.handle.driver().io()
+    }
 }
 
 impl Drop for Registration {
@@ -222,28 +218,22 @@ impl Drop for Registration {
 }
 
 fn gone() -> io::Error {
-    io::Error::new(io::ErrorKind::Other, "IO driver has terminated")
+    io::Error::new(
+        io::ErrorKind::Other,
+        crate::util::error::RUNTIME_SHUTTING_DOWN_ERROR,
+    )
 }
 
 cfg_io_readiness! {
     impl Registration {
         pub(crate) async fn readiness(&self, interest: Interest) -> io::Result<ReadyEvent> {
-            use std::future::Future;
-            use std::pin::Pin;
-
-            let fut = self.shared.readiness(interest);
-            pin!(fut);
+            let ev = self.shared.readiness(interest).await;
 
-            crate::future::poll_fn(|cx| {
-                if self.handle.inner().is_none() {
-                    return Poll::Ready(Err(io::Error::new(
-                        io::ErrorKind::Other,
-                        crate::util::error::RUNTIME_SHUTTING_DOWN_ERROR
-                    )));
-                }
+            if ev.is_shutdown {
+                return Err(gone())
+            }
 
-                Pin::new(&mut fut).poll(cx).map(Ok)
-            }).await
+            Ok(ev)
         }
 
         pub(crate) async fn async_io<R>(&self, interest: Interest, mut f: impl FnMut() -> io::Result<R>) -> io::Result<R> {
diff --git a/vendor/tokio/src/io/driver/scheduled_io.rs b/vendor/tokio/src/runtime/io/scheduled_io.rs
index 517801079..197a4e0e2 100644
--- a/vendor/tokio/src/io/driver/scheduled_io.rs
+++ b/vendor/tokio/src/runtime/io/scheduled_io.rs
@@ -1,8 +1,11 @@
-use super::{Interest, Ready, ReadyEvent, Tick};
+use super::{ReadyEvent, Tick};
+use crate::io::interest::Interest;
+use crate::io::ready::Ready;
 use crate::loom::sync::atomic::AtomicUsize;
 use crate::loom::sync::Mutex;
 use crate::util::bit;
 use crate::util::slab::Entry;
+use crate::util::WakeList;
 
 use std::sync::atomic::Ordering::{AcqRel, Acquire, Release};
 use std::task::{Context, Poll, Waker};
@@ -35,17 +38,14 @@ cfg_io_readiness! {
 #[derive(Debug, Default)]
 struct Waiters {
     #[cfg(feature = "net")]
-    /// List of all current waiters
+    /// List of all current waiters.
     list: WaitList,
 
-    /// Waker used for AsyncRead
+    /// Waker used for AsyncRead.
     reader: Option<Waker>,
 
-    /// Waker used for AsyncWrite
+    /// Waker used for AsyncWrite.
     writer: Option<Waker>,
-
-    /// True if this ScheduledIo has been killed due to IO driver shutdown
-    is_shutdown: bool,
 }
 
 cfg_io_readiness! {
@@ -53,19 +53,27 @@ cfg_io_readiness! {
     struct Waiter {
         pointers: linked_list::Pointers<Waiter>,
 
-        /// The waker for this task
+        /// The waker for this task.
         waker: Option<Waker>,
 
-        /// The interest this waiter is waiting on
+        /// The interest this waiter is waiting on.
         interest: Interest,
 
         is_ready: bool,
 
-        /// Should never be `!Unpin`
+        /// Should never be `!Unpin`.
         _p: PhantomPinned,
     }
 
-    /// Future returned by `readiness()`
+    generate_addr_of_methods! {
+        impl<> Waiter {
+            unsafe fn addr_of_pointers(self: NonNull<Self>) -> NonNull<linked_list::Pointers<Waiter>> {
+                &self.pointers
+            }
+        }
+    }
+
+    /// Future returned by `readiness()`.
     struct Readiness<'a> {
         scheduled_io: &'a ScheduledIo,
 
@@ -84,7 +92,7 @@ cfg_io_readiness! {
 
 // The `ScheduledIo::readiness` (`AtomicUsize`) is packed full of goodness.
 //
-// | reserved | generation |  driver tick | readiness |
+// | shutdown | generation |  driver tick | readiness |
 // |----------+------------+--------------+-----------|
 // |   1 bit  |   7 bits   +    8 bits    +   16 bits |
 
@@ -94,6 +102,8 @@ const TICK: bit::Pack = READINESS.then(8);
 
 const GENERATION: bit::Pack = TICK.then(7);
 
+const SHUTDOWN: bit::Pack = GENERATION.then(1);
+
 #[test]
 fn test_generations_assert_same() {
     assert_eq!(super::GENERATION, GENERATION);
@@ -127,9 +137,11 @@ impl ScheduledIo {
     }
 
     /// Invoked when the IO driver is shut down; forces this ScheduledIo into a
-    /// permanently ready state.
+    /// permanently shutdown state.
     pub(super) fn shutdown(&self) {
-        self.wake0(Ready::ALL, true)
+        let mask = SHUTDOWN.pack(1, 0);
+        self.readiness.fetch_or(mask, AcqRel);
+        self.wake(Ready::ALL);
     }
 
     /// Sets the readiness on this `ScheduledIo` by invoking the given closure on
@@ -208,32 +220,21 @@ impl ScheduledIo {
     /// than 32 wakers to notify, if the stack array fills up, the lock is
     /// released, the array is cleared, and the iteration continues.
     pub(super) fn wake(&self, ready: Ready) {
-        self.wake0(ready, false);
-    }
-
-    fn wake0(&self, ready: Ready, shutdown: bool) {
-        const NUM_WAKERS: usize = 32;
-
-        let mut wakers: [Option<Waker>; NUM_WAKERS] = Default::default();
-        let mut curr = 0;
+        let mut wakers = WakeList::new();
 
         let mut waiters = self.waiters.lock();
 
-        waiters.is_shutdown |= shutdown;
-
         // check for AsyncRead slot
         if ready.is_readable() {
             if let Some(waker) = waiters.reader.take() {
-                wakers[curr] = Some(waker);
-                curr += 1;
+                wakers.push(waker);
             }
         }
 
         // check for AsyncWrite slot
         if ready.is_writable() {
             if let Some(waker) = waiters.writer.take() {
-                wakers[curr] = Some(waker);
-                curr += 1;
+                wakers.push(waker);
             }
         }
 
@@ -241,15 +242,14 @@ impl ScheduledIo {
         'outer: loop {
             let mut iter = waiters.list.drain_filter(|w| ready.satisfies(w.interest));
 
-            while curr < NUM_WAKERS {
+            while wakers.can_push() {
                 match iter.next() {
                     Some(waiter) => {
                         let waiter = unsafe { &mut *waiter.as_ptr() };
 
                         if let Some(waker) = waiter.waker.take() {
                             waiter.is_ready = true;
-                            wakers[curr] = Some(waker);
-                            curr += 1;
+                            wakers.push(waker);
                         }
                     }
                     None => {
@@ -260,11 +260,7 @@ impl ScheduledIo {
 
             drop(waiters);
 
-            for waker in wakers.iter_mut().take(curr) {
-                waker.take().unwrap().wake();
-            }
-
-            curr = 0;
+            wakers.wake_all();
 
             // Acquire the lock again.
             waiters = self.waiters.lock();
@@ -273,9 +269,7 @@ impl ScheduledIo {
         // Release the lock before notifying
         drop(waiters);
 
-        for waker in wakers.iter_mut().take(curr) {
-            waker.take().unwrap().wake();
-        }
+        wakers.wake_all();
     }
 
     pub(super) fn ready_event(&self, interest: Interest) -> ReadyEvent {
@@ -284,10 +278,11 @@ impl ScheduledIo {
         ReadyEvent {
             tick: TICK.unpack(curr) as u8,
             ready: interest.mask() & Ready::from_usize(READINESS.unpack(curr)),
+            is_shutdown: SHUTDOWN.unpack(curr) != 0,
         }
     }
 
-    /// Poll version of checking readiness for a certain direction.
+    /// Polls for readiness events in a given direction.
     ///
     /// These are to support `AsyncRead` and `AsyncWrite` polling methods,
     /// which cannot use the `async fn` version. This uses reserved reader
@@ -300,8 +295,9 @@ impl ScheduledIo {
         let curr = self.readiness.load(Acquire);
 
         let ready = direction.mask() & Ready::from_usize(READINESS.unpack(curr));
+        let is_shutdown = SHUTDOWN.unpack(curr) != 0;
 
-        if ready.is_empty() {
+        if ready.is_empty() && !is_shutdown {
             // Update the task info
             let mut waiters = self.waiters.lock();
             let slot = match direction {
@@ -326,10 +322,12 @@ impl ScheduledIo {
             // taking the waiters lock
             let curr = self.readiness.load(Acquire);
             let ready = direction.mask() & Ready::from_usize(READINESS.unpack(curr));
-            if waiters.is_shutdown {
+            let is_shutdown = SHUTDOWN.unpack(curr) != 0;
+            if is_shutdown {
                 Poll::Ready(ReadyEvent {
                     tick: TICK.unpack(curr) as u8,
                     ready: direction.mask(),
+                    is_shutdown,
                 })
             } else if ready.is_empty() {
                 Poll::Pending
@@ -337,12 +335,14 @@ impl ScheduledIo {
                 Poll::Ready(ReadyEvent {
                     tick: TICK.unpack(curr) as u8,
                     ready,
+                    is_shutdown,
                 })
             }
         } else {
             Poll::Ready(ReadyEvent {
                 tick: TICK.unpack(curr) as u8,
                 ready,
+                is_shutdown,
             })
         }
     }
@@ -374,7 +374,7 @@ unsafe impl Sync for ScheduledIo {}
 
 cfg_io_readiness! {
     impl ScheduledIo {
-        /// An async version of `poll_readiness` which uses a linked list of wakers
+        /// An async version of `poll_readiness` which uses a linked list of wakers.
         pub(crate) async fn readiness(&self, interest: Interest) -> ReadyEvent {
             self.readiness_fut(interest).await
         }
@@ -410,8 +410,8 @@ cfg_io_readiness! {
             ptr
         }
 
-        unsafe fn pointers(mut target: NonNull<Waiter>) -> NonNull<linked_list::Pointers<Waiter>> {
-            NonNull::from(&mut target.as_mut().pointers)
+        unsafe fn pointers(target: NonNull<Waiter>) -> NonNull<linked_list::Pointers<Waiter>> {
+            Waiter::addr_of_pointers(target)
         }
     }
 
@@ -434,16 +434,17 @@ cfg_io_readiness! {
                         // Optimistically check existing readiness
                         let curr = scheduled_io.readiness.load(SeqCst);
                         let ready = Ready::from_usize(READINESS.unpack(curr));
+                        let is_shutdown = SHUTDOWN.unpack(curr) != 0;
 
                         // Safety: `waiter.interest` never changes
                         let interest = unsafe { (*waiter.get()).interest };
                         let ready = ready.intersection(interest);
 
-                        if !ready.is_empty() {
+                        if !ready.is_empty() || is_shutdown {
                             // Currently ready!
                             let tick = TICK.unpack(curr) as u8;
                             *state = State::Done;
-                            return Poll::Ready(ReadyEvent { tick, ready });
+                            return Poll::Ready(ReadyEvent { tick, ready, is_shutdown });
                         }
 
                         // Wasn't ready, take the lock (and check again while locked).
@@ -451,18 +452,19 @@ cfg_io_readiness! {
 
                         let curr = scheduled_io.readiness.load(SeqCst);
                         let mut ready = Ready::from_usize(READINESS.unpack(curr));
+                        let is_shutdown = SHUTDOWN.unpack(curr) != 0;
 
-                        if waiters.is_shutdown {
+                        if is_shutdown {
                             ready = Ready::ALL;
                         }
 
                         let ready = ready.intersection(interest);
 
-                        if !ready.is_empty() {
+                        if !ready.is_empty() || is_shutdown {
                             // Currently ready!
                             let tick = TICK.unpack(curr) as u8;
                             *state = State::Done;
-                            return Poll::Ready(ReadyEvent { tick, ready });
+                            return Poll::Ready(ReadyEvent { tick, ready, is_shutdown });
                         }
 
                         // Not ready even after locked, insert into list...
@@ -511,14 +513,26 @@ cfg_io_readiness! {
                         drop(waiters);
                     }
                     State::Done => {
-                        let tick = TICK.unpack(scheduled_io.readiness.load(Acquire)) as u8;
-
                         // Safety: State::Done means it is no longer shared
                         let w = unsafe { &mut *waiter.get() };
 
+                        let curr = scheduled_io.readiness.load(Acquire);
+                        let is_shutdown = SHUTDOWN.unpack(curr) != 0;
+
+                        // The returned tick might be newer than the event
+                        // which notified our waker. This is ok because the future
+                        // still didn't return `Poll::Ready`.
+                        let tick = TICK.unpack(curr) as u8;
+
+                        // The readiness state could have been cleared in the meantime,
+                        // but we allow the returned ready set to be empty.
+                        let curr_ready = Ready::from_usize(READINESS.unpack(curr));
+                        let ready = curr_ready.intersection(w.interest);
+
                         return Poll::Ready(ReadyEvent {
                             tick,
-                            ready: Ready::from_interest(w.interest),
+                            ready,
+                            is_shutdown,
                         });
                     }
                 }
diff --git a/vendor/tokio/src/runtime/metrics/batch.rs b/vendor/tokio/src/runtime/metrics/batch.rs
new file mode 100644
index 000000000..1bb4e261f
--- /dev/null
+++ b/vendor/tokio/src/runtime/metrics/batch.rs
@@ -0,0 +1,162 @@
+use crate::runtime::metrics::{HistogramBatch, WorkerMetrics};
+
+use std::sync::atomic::Ordering::Relaxed;
+use std::time::{Duration, Instant};
+
+pub(crate) struct MetricsBatch {
+    /// Number of times the worker parked.
+    park_count: u64,
+
+    /// Number of times the worker woke w/o doing work.
+    noop_count: u64,
+
+    /// Number of tasks stolen.
+    steal_count: u64,
+
+    /// Number of times tasks where stolen.
+    steal_operations: u64,
+
+    /// Number of tasks that were polled by the worker.
+    poll_count: u64,
+
+    /// Number of tasks polled when the worker entered park. This is used to
+    /// track the noop count.
+    poll_count_on_last_park: u64,
+
+    /// Number of tasks that were scheduled locally on this worker.
+    local_schedule_count: u64,
+
+    /// Number of tasks moved to the global queue to make space in the local
+    /// queue
+    overflow_count: u64,
+
+    /// The total busy duration in nanoseconds.
+    busy_duration_total: u64,
+
+    /// Instant at which work last resumed (continued after park).
+    processing_scheduled_tasks_started_at: Instant,
+
+    /// If `Some`, tracks poll times in nanoseconds
+    poll_timer: Option<PollTimer>,
+}
+
+struct PollTimer {
+    /// Histogram of poll counts within each band.
+    poll_counts: HistogramBatch,
+
+    /// Instant when the most recent task started polling.
+    poll_started_at: Instant,
+}
+
+impl MetricsBatch {
+    pub(crate) fn new(worker_metrics: &WorkerMetrics) -> MetricsBatch {
+        let now = Instant::now();
+
+        MetricsBatch {
+            park_count: 0,
+            noop_count: 0,
+            steal_count: 0,
+            steal_operations: 0,
+            poll_count: 0,
+            poll_count_on_last_park: 0,
+            local_schedule_count: 0,
+            overflow_count: 0,
+            busy_duration_total: 0,
+            processing_scheduled_tasks_started_at: now,
+            poll_timer: worker_metrics
+                .poll_count_histogram
+                .as_ref()
+                .map(|worker_poll_counts| PollTimer {
+                    poll_counts: HistogramBatch::from_histogram(worker_poll_counts),
+                    poll_started_at: now,
+                }),
+        }
+    }
+
+    pub(crate) fn submit(&mut self, worker: &WorkerMetrics) {
+        worker.park_count.store(self.park_count, Relaxed);
+        worker.noop_count.store(self.noop_count, Relaxed);
+        worker.steal_count.store(self.steal_count, Relaxed);
+        worker
+            .steal_operations
+            .store(self.steal_operations, Relaxed);
+        worker.poll_count.store(self.poll_count, Relaxed);
+
+        worker
+            .busy_duration_total
+            .store(self.busy_duration_total, Relaxed);
+
+        worker
+            .local_schedule_count
+            .store(self.local_schedule_count, Relaxed);
+        worker.overflow_count.store(self.overflow_count, Relaxed);
+
+        if let Some(poll_timer) = &self.poll_timer {
+            let dst = worker.poll_count_histogram.as_ref().unwrap();
+            poll_timer.poll_counts.submit(dst);
+        }
+    }
+
+    /// The worker is about to park.
+    pub(crate) fn about_to_park(&mut self) {
+        self.park_count += 1;
+
+        if self.poll_count_on_last_park == self.poll_count {
+            self.noop_count += 1;
+        } else {
+            self.poll_count_on_last_park = self.poll_count;
+        }
+    }
+
+    /// Start processing a batch of tasks
+    pub(crate) fn start_processing_scheduled_tasks(&mut self) {
+        self.processing_scheduled_tasks_started_at = Instant::now();
+    }
+
+    /// Stop processing a batch of tasks
+    pub(crate) fn end_processing_scheduled_tasks(&mut self) {
+        let busy_duration = self.processing_scheduled_tasks_started_at.elapsed();
+        self.busy_duration_total += duration_as_u64(busy_duration);
+    }
+
+    /// Start polling an individual task
+    pub(crate) fn start_poll(&mut self) {
+        self.poll_count += 1;
+
+        if let Some(poll_timer) = &mut self.poll_timer {
+            poll_timer.poll_started_at = Instant::now();
+        }
+    }
+
+    /// Stop polling an individual task
+    pub(crate) fn end_poll(&mut self) {
+        if let Some(poll_timer) = &mut self.poll_timer {
+            let elapsed = duration_as_u64(poll_timer.poll_started_at.elapsed());
+            poll_timer.poll_counts.measure(elapsed, 1);
+        }
+    }
+
+    pub(crate) fn inc_local_schedule_count(&mut self) {
+        self.local_schedule_count += 1;
+    }
+}
+
+cfg_rt_multi_thread! {
+    impl MetricsBatch {
+        pub(crate) fn incr_steal_count(&mut self, by: u16) {
+            self.steal_count += by as u64;
+        }
+
+        pub(crate) fn incr_steal_operations(&mut self) {
+            self.steal_operations += 1;
+        }
+
+        pub(crate) fn incr_overflow_count(&mut self) {
+            self.overflow_count += 1;
+        }
+    }
+}
+
+fn duration_as_u64(dur: Duration) -> u64 {
+    u64::try_from(dur.as_nanos()).unwrap_or(u64::MAX)
+}
diff --git a/vendor/tokio/src/runtime/metrics/histogram.rs b/vendor/tokio/src/runtime/metrics/histogram.rs
new file mode 100644
index 000000000..976f54fe8
--- /dev/null
+++ b/vendor/tokio/src/runtime/metrics/histogram.rs
@@ -0,0 +1,502 @@
+use crate::loom::sync::atomic::{AtomicU64, Ordering::Relaxed};
+
+use std::cmp;
+use std::ops::Range;
+
+#[derive(Debug)]
+pub(crate) struct Histogram {
+    /// The histogram buckets
+    buckets: Box<[AtomicU64]>,
+
+    /// Bucket scale, linear or log
+    scale: HistogramScale,
+
+    /// Minimum resolution
+    resolution: u64,
+}
+
+#[derive(Debug, Clone)]
+pub(crate) struct HistogramBuilder {
+    /// Histogram scale
+    pub(crate) scale: HistogramScale,
+
+    /// Must be a power of 2
+    pub(crate) resolution: u64,
+
+    /// Number of buckets
+    pub(crate) num_buckets: usize,
+}
+
+#[derive(Debug)]
+pub(crate) struct HistogramBatch {
+    buckets: Box<[u64]>,
+    scale: HistogramScale,
+    resolution: u64,
+}
+
+cfg_unstable! {
+    /// Whether the histogram used to aggregate a metric uses a linear or
+    /// logarithmic scale.
+    #[derive(Debug, Copy, Clone, Eq, PartialEq)]
+    #[non_exhaustive]
+    pub enum HistogramScale {
+        /// Linear bucket scale
+        Linear,
+
+        /// Logarithmic bucket scale
+        Log,
+    }
+}
+
+impl Histogram {
+    pub(crate) fn num_buckets(&self) -> usize {
+        self.buckets.len()
+    }
+
+    pub(crate) fn get(&self, bucket: usize) -> u64 {
+        self.buckets[bucket].load(Relaxed)
+    }
+
+    pub(crate) fn bucket_range(&self, bucket: usize) -> Range<u64> {
+        match self.scale {
+            HistogramScale::Log => Range {
+                start: if bucket == 0 {
+                    0
+                } else {
+                    self.resolution << (bucket - 1)
+                },
+                end: if bucket == self.buckets.len() - 1 {
+                    u64::MAX
+                } else {
+                    self.resolution << bucket
+                },
+            },
+            HistogramScale::Linear => Range {
+                start: self.resolution * bucket as u64,
+                end: if bucket == self.buckets.len() - 1 {
+                    u64::MAX
+                } else {
+                    self.resolution * (bucket as u64 + 1)
+                },
+            },
+        }
+    }
+}
+
+impl HistogramBatch {
+    pub(crate) fn from_histogram(histogram: &Histogram) -> HistogramBatch {
+        let buckets = vec![0; histogram.buckets.len()].into_boxed_slice();
+
+        HistogramBatch {
+            buckets,
+            scale: histogram.scale,
+            resolution: histogram.resolution,
+        }
+    }
+
+    pub(crate) fn measure(&mut self, value: u64, count: u64) {
+        self.buckets[self.value_to_bucket(value)] += count;
+    }
+
+    pub(crate) fn submit(&self, histogram: &Histogram) {
+        debug_assert_eq!(self.scale, histogram.scale);
+        debug_assert_eq!(self.resolution, histogram.resolution);
+        debug_assert_eq!(self.buckets.len(), histogram.buckets.len());
+
+        for i in 0..self.buckets.len() {
+            histogram.buckets[i].store(self.buckets[i], Relaxed);
+        }
+    }
+
+    fn value_to_bucket(&self, value: u64) -> usize {
+        match self.scale {
+            HistogramScale::Linear => {
+                let max = self.buckets.len() - 1;
+                cmp::min(value / self.resolution, max as u64) as usize
+            }
+            HistogramScale::Log => {
+                let max = self.buckets.len() - 1;
+
+                if value < self.resolution {
+                    0
+                } else {
+                    let significant_digits = 64 - value.leading_zeros();
+                    let bucket_digits = 64 - (self.resolution - 1).leading_zeros();
+                    cmp::min(significant_digits as usize - bucket_digits as usize, max)
+                }
+            }
+        }
+    }
+}
+
+impl HistogramBuilder {
+    pub(crate) fn new() -> HistogramBuilder {
+        HistogramBuilder {
+            scale: HistogramScale::Linear,
+            // Resolution is in nanoseconds.
+            resolution: 100_000,
+            num_buckets: 10,
+        }
+    }
+
+    pub(crate) fn build(&self) -> Histogram {
+        let mut resolution = self.resolution;
+
+        assert!(resolution > 0);
+
+        if matches!(self.scale, HistogramScale::Log) {
+            resolution = resolution.next_power_of_two();
+        }
+
+        Histogram {
+            buckets: (0..self.num_buckets)
+                .map(|_| AtomicU64::new(0))
+                .collect::<Vec<_>>()
+                .into_boxed_slice(),
+            resolution,
+            scale: self.scale,
+        }
+    }
+}
+
+impl Default for HistogramBuilder {
+    fn default() -> HistogramBuilder {
+        HistogramBuilder::new()
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    macro_rules! assert_bucket_eq {
+        ($h:expr, $bucket:expr, $val:expr) => {{
+            assert_eq!($h.buckets[$bucket], $val);
+        }};
+    }
+
+    #[test]
+    fn log_scale_resolution_1() {
+        let h = HistogramBuilder {
+            scale: HistogramScale::Log,
+            resolution: 1,
+            num_buckets: 10,
+        }
+        .build();
+
+        assert_eq!(h.bucket_range(0), 0..1);
+        assert_eq!(h.bucket_range(1), 1..2);
+        assert_eq!(h.bucket_range(2), 2..4);
+        assert_eq!(h.bucket_range(3), 4..8);
+        assert_eq!(h.bucket_range(9), 256..u64::MAX);
+
+        let mut b = HistogramBatch::from_histogram(&h);
+
+        b.measure(0, 1);
+        assert_bucket_eq!(b, 0, 1);
+        assert_bucket_eq!(b, 1, 0);
+
+        b.measure(1, 1);
+        assert_bucket_eq!(b, 0, 1);
+        assert_bucket_eq!(b, 1, 1);
+        assert_bucket_eq!(b, 2, 0);
+
+        b.measure(2, 1);
+        assert_bucket_eq!(b, 0, 1);
+        assert_bucket_eq!(b, 1, 1);
+        assert_bucket_eq!(b, 2, 1);
+
+        b.measure(3, 1);
+        assert_bucket_eq!(b, 0, 1);
+        assert_bucket_eq!(b, 1, 1);
+        assert_bucket_eq!(b, 2, 2);
+
+        b.measure(4, 1);
+        assert_bucket_eq!(b, 0, 1);
+        assert_bucket_eq!(b, 1, 1);
+        assert_bucket_eq!(b, 2, 2);
+        assert_bucket_eq!(b, 3, 1);
+
+        b.measure(100, 1);
+        assert_bucket_eq!(b, 7, 1);
+
+        b.measure(128, 1);
+        assert_bucket_eq!(b, 8, 1);
+
+        b.measure(4096, 1);
+        assert_bucket_eq!(b, 9, 1);
+    }
+
+    #[test]
+    fn log_scale_resolution_2() {
+        let h = HistogramBuilder {
+            scale: HistogramScale::Log,
+            resolution: 2,
+            num_buckets: 10,
+        }
+        .build();
+
+        assert_eq!(h.bucket_range(0), 0..2);
+        assert_eq!(h.bucket_range(1), 2..4);
+        assert_eq!(h.bucket_range(2), 4..8);
+        assert_eq!(h.bucket_range(3), 8..16);
+        assert_eq!(h.bucket_range(9), 512..u64::MAX);
+
+        let mut b = HistogramBatch::from_histogram(&h);
+
+        b.measure(0, 1);
+        assert_bucket_eq!(b, 0, 1);
+        assert_bucket_eq!(b, 1, 0);
+
+        b.measure(1, 1);
+        assert_bucket_eq!(b, 0, 2);
+        assert_bucket_eq!(b, 1, 0);
+
+        b.measure(2, 1);
+        assert_bucket_eq!(b, 0, 2);
+        assert_bucket_eq!(b, 1, 1);
+        assert_bucket_eq!(b, 2, 0);
+
+        b.measure(3, 1);
+        assert_bucket_eq!(b, 0, 2);
+        assert_bucket_eq!(b, 1, 2);
+        assert_bucket_eq!(b, 2, 0);
+
+        b.measure(4, 1);
+        assert_bucket_eq!(b, 0, 2);
+        assert_bucket_eq!(b, 1, 2);
+        assert_bucket_eq!(b, 2, 1);
+
+        b.measure(5, 1);
+        assert_bucket_eq!(b, 0, 2);
+        assert_bucket_eq!(b, 1, 2);
+        assert_bucket_eq!(b, 2, 2);
+
+        b.measure(6, 1);
+        assert_bucket_eq!(b, 0, 2);
+        assert_bucket_eq!(b, 1, 2);
+        assert_bucket_eq!(b, 2, 3);
+
+        b.measure(7, 1);
+        assert_bucket_eq!(b, 0, 2);
+        assert_bucket_eq!(b, 1, 2);
+        assert_bucket_eq!(b, 2, 4);
+
+        b.measure(8, 1);
+        assert_bucket_eq!(b, 0, 2);
+        assert_bucket_eq!(b, 1, 2);
+        assert_bucket_eq!(b, 2, 4);
+        assert_bucket_eq!(b, 3, 1);
+
+        b.measure(100, 1);
+        assert_bucket_eq!(b, 6, 1);
+
+        b.measure(128, 1);
+        assert_bucket_eq!(b, 7, 1);
+
+        b.measure(4096, 1);
+        assert_bucket_eq!(b, 9, 1);
+
+        for bucket in h.buckets.iter() {
+            assert_eq!(bucket.load(Relaxed), 0);
+        }
+
+        b.submit(&h);
+
+        for i in 0..h.buckets.len() {
+            assert_eq!(h.buckets[i].load(Relaxed), b.buckets[i]);
+        }
+
+        b.submit(&h);
+
+        for i in 0..h.buckets.len() {
+            assert_eq!(h.buckets[i].load(Relaxed), b.buckets[i]);
+        }
+    }
+
+    #[test]
+    fn linear_scale_resolution_1() {
+        let h = HistogramBuilder {
+            scale: HistogramScale::Linear,
+            resolution: 1,
+            num_buckets: 10,
+        }
+        .build();
+
+        assert_eq!(h.bucket_range(0), 0..1);
+        assert_eq!(h.bucket_range(1), 1..2);
+        assert_eq!(h.bucket_range(2), 2..3);
+        assert_eq!(h.bucket_range(3), 3..4);
+        assert_eq!(h.bucket_range(9), 9..u64::MAX);
+
+        let mut b = HistogramBatch::from_histogram(&h);
+
+        b.measure(0, 1);
+        assert_bucket_eq!(b, 0, 1);
+        assert_bucket_eq!(b, 1, 0);
+
+        b.measure(1, 1);
+        assert_bucket_eq!(b, 0, 1);
+        assert_bucket_eq!(b, 1, 1);
+        assert_bucket_eq!(b, 2, 0);
+
+        b.measure(2, 1);
+        assert_bucket_eq!(b, 0, 1);
+        assert_bucket_eq!(b, 1, 1);
+        assert_bucket_eq!(b, 2, 1);
+        assert_bucket_eq!(b, 3, 0);
+
+        b.measure(3, 1);
+        assert_bucket_eq!(b, 0, 1);
+        assert_bucket_eq!(b, 1, 1);
+        assert_bucket_eq!(b, 2, 1);
+        assert_bucket_eq!(b, 3, 1);
+
+        b.measure(5, 1);
+        assert_bucket_eq!(b, 5, 1);
+
+        b.measure(4096, 1);
+        assert_bucket_eq!(b, 9, 1);
+
+        for bucket in h.buckets.iter() {
+            assert_eq!(bucket.load(Relaxed), 0);
+        }
+
+        b.submit(&h);
+
+        for i in 0..h.buckets.len() {
+            assert_eq!(h.buckets[i].load(Relaxed), b.buckets[i]);
+        }
+
+        b.submit(&h);
+
+        for i in 0..h.buckets.len() {
+            assert_eq!(h.buckets[i].load(Relaxed), b.buckets[i]);
+        }
+    }
+
+    #[test]
+    fn linear_scale_resolution_100() {
+        let h = HistogramBuilder {
+            scale: HistogramScale::Linear,
+            resolution: 100,
+            num_buckets: 10,
+        }
+        .build();
+
+        assert_eq!(h.bucket_range(0), 0..100);
+        assert_eq!(h.bucket_range(1), 100..200);
+        assert_eq!(h.bucket_range(2), 200..300);
+        assert_eq!(h.bucket_range(3), 300..400);
+        assert_eq!(h.bucket_range(9), 900..u64::MAX);
+
+        let mut b = HistogramBatch::from_histogram(&h);
+
+        b.measure(0, 1);
+        assert_bucket_eq!(b, 0, 1);
+        assert_bucket_eq!(b, 1, 0);
+
+        b.measure(50, 1);
+        assert_bucket_eq!(b, 0, 2);
+        assert_bucket_eq!(b, 1, 0);
+
+        b.measure(100, 1);
+        assert_bucket_eq!(b, 0, 2);
+        assert_bucket_eq!(b, 1, 1);
+        assert_bucket_eq!(b, 2, 0);
+
+        b.measure(101, 1);
+        assert_bucket_eq!(b, 0, 2);
+        assert_bucket_eq!(b, 1, 2);
+        assert_bucket_eq!(b, 2, 0);
+
+        b.measure(200, 1);
+        assert_bucket_eq!(b, 0, 2);
+        assert_bucket_eq!(b, 1, 2);
+        assert_bucket_eq!(b, 2, 1);
+
+        b.measure(299, 1);
+        assert_bucket_eq!(b, 0, 2);
+        assert_bucket_eq!(b, 1, 2);
+        assert_bucket_eq!(b, 2, 2);
+
+        b.measure(222, 1);
+        assert_bucket_eq!(b, 0, 2);
+        assert_bucket_eq!(b, 1, 2);
+        assert_bucket_eq!(b, 2, 3);
+
+        b.measure(300, 1);
+        assert_bucket_eq!(b, 0, 2);
+        assert_bucket_eq!(b, 1, 2);
+        assert_bucket_eq!(b, 2, 3);
+        assert_bucket_eq!(b, 3, 1);
+
+        b.measure(888, 1);
+        assert_bucket_eq!(b, 8, 1);
+
+        b.measure(4096, 1);
+        assert_bucket_eq!(b, 9, 1);
+
+        for bucket in h.buckets.iter() {
+            assert_eq!(bucket.load(Relaxed), 0);
+        }
+
+        b.submit(&h);
+
+        for i in 0..h.buckets.len() {
+            assert_eq!(h.buckets[i].load(Relaxed), b.buckets[i]);
+        }
+
+        b.submit(&h);
+
+        for i in 0..h.buckets.len() {
+            assert_eq!(h.buckets[i].load(Relaxed), b.buckets[i]);
+        }
+    }
+
+    #[test]
+    fn inc_by_more_than_one() {
+        let h = HistogramBuilder {
+            scale: HistogramScale::Linear,
+            resolution: 100,
+            num_buckets: 10,
+        }
+        .build();
+
+        let mut b = HistogramBatch::from_histogram(&h);
+
+        b.measure(0, 3);
+        assert_bucket_eq!(b, 0, 3);
+        assert_bucket_eq!(b, 1, 0);
+
+        b.measure(50, 5);
+        assert_bucket_eq!(b, 0, 8);
+        assert_bucket_eq!(b, 1, 0);
+
+        b.measure(100, 2);
+        assert_bucket_eq!(b, 0, 8);
+        assert_bucket_eq!(b, 1, 2);
+        assert_bucket_eq!(b, 2, 0);
+
+        b.measure(101, 19);
+        assert_bucket_eq!(b, 0, 8);
+        assert_bucket_eq!(b, 1, 21);
+        assert_bucket_eq!(b, 2, 0);
+
+        for bucket in h.buckets.iter() {
+            assert_eq!(bucket.load(Relaxed), 0);
+        }
+
+        b.submit(&h);
+
+        for i in 0..h.buckets.len() {
+            assert_eq!(h.buckets[i].load(Relaxed), b.buckets[i]);
+        }
+
+        b.submit(&h);
+
+        for i in 0..h.buckets.len() {
+            assert_eq!(h.buckets[i].load(Relaxed), b.buckets[i]);
+        }
+    }
+}
diff --git a/vendor/tokio/src/runtime/metrics/io.rs b/vendor/tokio/src/runtime/metrics/io.rs
new file mode 100644
index 000000000..06efdd42d
--- /dev/null
+++ b/vendor/tokio/src/runtime/metrics/io.rs
@@ -0,0 +1,24 @@
+#![cfg_attr(not(feature = "net"), allow(dead_code))]
+
+use crate::loom::sync::atomic::{AtomicU64, Ordering::Relaxed};
+
+#[derive(Default)]
+pub(crate) struct IoDriverMetrics {
+    pub(super) fd_registered_count: AtomicU64,
+    pub(super) fd_deregistered_count: AtomicU64,
+    pub(super) ready_count: AtomicU64,
+}
+
+impl IoDriverMetrics {
+    pub(crate) fn incr_fd_count(&self) {
+        self.fd_registered_count.fetch_add(1, Relaxed);
+    }
+
+    pub(crate) fn dec_fd_count(&self) {
+        self.fd_deregistered_count.fetch_add(1, Relaxed);
+    }
+
+    pub(crate) fn incr_ready_count_by(&self, amt: u64) {
+        self.ready_count.fetch_add(amt, Relaxed);
+    }
+}
diff --git a/vendor/tokio/src/runtime/metrics/mock.rs b/vendor/tokio/src/runtime/metrics/mock.rs
new file mode 100644
index 000000000..8f8345c08
--- /dev/null
+++ b/vendor/tokio/src/runtime/metrics/mock.rs
@@ -0,0 +1,55 @@
+//! This file contains mocks of the types in src/runtime/metrics
+
+pub(crate) struct SchedulerMetrics {}
+
+pub(crate) struct WorkerMetrics {}
+
+pub(crate) struct MetricsBatch {}
+
+#[derive(Clone, Default)]
+pub(crate) struct HistogramBuilder {}
+
+impl SchedulerMetrics {
+    pub(crate) fn new() -> Self {
+        Self {}
+    }
+
+    /// Increment the number of tasks scheduled externally
+    pub(crate) fn inc_remote_schedule_count(&self) {}
+}
+
+impl WorkerMetrics {
+    pub(crate) fn new() -> Self {
+        Self {}
+    }
+
+    pub(crate) fn from_config(config: &crate::runtime::Config) -> Self {
+        // Prevent the dead-code warning from being triggered
+        let _ = &config.metrics_poll_count_histogram;
+        Self::new()
+    }
+
+    pub(crate) fn set_queue_depth(&self, _len: usize) {}
+}
+
+impl MetricsBatch {
+    pub(crate) fn new(_: &WorkerMetrics) -> Self {
+        Self {}
+    }
+
+    pub(crate) fn submit(&mut self, _to: &WorkerMetrics) {}
+    pub(crate) fn about_to_park(&mut self) {}
+    pub(crate) fn inc_local_schedule_count(&mut self) {}
+    pub(crate) fn start_processing_scheduled_tasks(&mut self) {}
+    pub(crate) fn end_processing_scheduled_tasks(&mut self) {}
+    pub(crate) fn start_poll(&mut self) {}
+    pub(crate) fn end_poll(&mut self) {}
+}
+
+cfg_rt_multi_thread! {
+    impl MetricsBatch {
+        pub(crate) fn incr_steal_count(&mut self, _by: u16) {}
+        pub(crate) fn incr_steal_operations(&mut self) {}
+        pub(crate) fn incr_overflow_count(&mut self) {}
+    }
+}
diff --git a/vendor/tokio/src/runtime/metrics/mod.rs b/vendor/tokio/src/runtime/metrics/mod.rs
new file mode 100644
index 000000000..88be4a521
--- /dev/null
+++ b/vendor/tokio/src/runtime/metrics/mod.rs
@@ -0,0 +1,40 @@
+//! This module contains information need to view information about how the
+//! runtime is performing.
+//!
+//! **Note**: This is an [unstable API][unstable]. The public API of types in
+//! this module may break in 1.x releases. See [the documentation on unstable
+//! features][unstable] for details.
+//!
+//! [unstable]: crate#unstable-features
+#![allow(clippy::module_inception)]
+
+cfg_metrics! {
+    mod batch;
+    pub(crate) use batch::MetricsBatch;
+
+    mod histogram;
+    pub(crate) use histogram::{Histogram, HistogramBatch, HistogramBuilder};
+    #[allow(unreachable_pub)] // rust-lang/rust#57411
+    pub use histogram::HistogramScale;
+
+    mod runtime;
+    #[allow(unreachable_pub)] // rust-lang/rust#57411
+    pub use runtime::RuntimeMetrics;
+
+    mod scheduler;
+    pub(crate) use scheduler::SchedulerMetrics;
+
+    mod worker;
+    pub(crate) use worker::WorkerMetrics;
+
+    cfg_net! {
+        mod io;
+        pub(crate) use io::IoDriverMetrics;
+    }
+}
+
+cfg_not_metrics! {
+    mod mock;
+
+    pub(crate) use mock::{SchedulerMetrics, WorkerMetrics, MetricsBatch, HistogramBuilder};
+}
diff --git a/vendor/tokio/src/runtime/metrics/runtime.rs b/vendor/tokio/src/runtime/metrics/runtime.rs
new file mode 100644
index 000000000..1f990a1f8
--- /dev/null
+++ b/vendor/tokio/src/runtime/metrics/runtime.rs
@@ -0,0 +1,883 @@
+use crate::runtime::Handle;
+
+use std::ops::Range;
+use std::sync::atomic::Ordering::Relaxed;
+use std::time::Duration;
+
+/// Handle to the runtime's metrics.
+///
+/// This handle is internally reference-counted and can be freely cloned. A
+/// `RuntimeMetrics` handle is obtained using the [`Runtime::metrics`] method.
+///
+/// [`Runtime::metrics`]: crate::runtime::Runtime::metrics()
+#[derive(Clone, Debug)]
+pub struct RuntimeMetrics {
+    handle: Handle,
+}
+
+impl RuntimeMetrics {
+    pub(crate) fn new(handle: Handle) -> RuntimeMetrics {
+        RuntimeMetrics { handle }
+    }
+
+    /// Returns the number of worker threads used by the runtime.
+    ///
+    /// The number of workers is set by configuring `worker_threads` on
+    /// `runtime::Builder`. When using the `current_thread` runtime, the return
+    /// value is always `1`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::runtime::Handle;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let metrics = Handle::current().metrics();
+    ///
+    ///     let n = metrics.num_workers();
+    ///     println!("Runtime is using {} workers", n);
+    /// }
+    /// ```
+    pub fn num_workers(&self) -> usize {
+        self.handle.inner.num_workers()
+    }
+
+    /// Returns the number of additional threads spawned by the runtime.
+    ///
+    /// The number of workers is set by configuring `max_blocking_threads` on
+    /// `runtime::Builder`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::runtime::Handle;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let _ = tokio::task::spawn_blocking(move || {
+    ///         // Stand-in for compute-heavy work or using synchronous APIs
+    ///         1 + 1
+    ///     }).await;
+    ///     let metrics = Handle::current().metrics();
+    ///
+    ///     let n = metrics.num_blocking_threads();
+    ///     println!("Runtime has created {} threads", n);
+    /// }
+    /// ```
+    pub fn num_blocking_threads(&self) -> usize {
+        self.handle.inner.num_blocking_threads()
+    }
+
+    /// Returns the number of active tasks in the runtime.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::runtime::Handle;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///    let metrics = Handle::current().metrics();
+    ///
+    ///     let n = metrics.active_tasks_count();
+    ///     println!("Runtime has {} active tasks", n);
+    /// }
+    /// ```
+    pub fn active_tasks_count(&self) -> usize {
+        self.handle.inner.active_tasks_count()
+    }
+
+    /// Returns the number of idle threads, which have spawned by the runtime
+    /// for `spawn_blocking` calls.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::runtime::Handle;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let _ = tokio::task::spawn_blocking(move || {
+    ///         // Stand-in for compute-heavy work or using synchronous APIs
+    ///         1 + 1
+    ///     }).await;
+    ///     let metrics = Handle::current().metrics();
+    ///
+    ///     let n = metrics.num_idle_blocking_threads();
+    ///     println!("Runtime has {} idle blocking thread pool threads", n);
+    /// }
+    /// ```
+    pub fn num_idle_blocking_threads(&self) -> usize {
+        self.handle.inner.num_idle_blocking_threads()
+    }
+
+    /// Returns the number of tasks scheduled from **outside** of the runtime.
+    ///
+    /// The remote schedule count starts at zero when the runtime is created and
+    /// increases by one each time a task is woken from **outside** of the
+    /// runtime. This usually means that a task is spawned or notified from a
+    /// non-runtime thread and must be queued using the Runtime's injection
+    /// queue, which tends to be slower.
+    ///
+    /// The counter is monotonically increasing. It is never decremented or
+    /// reset to zero.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::runtime::Handle;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let metrics = Handle::current().metrics();
+    ///
+    ///     let n = metrics.remote_schedule_count();
+    ///     println!("{} tasks were scheduled from outside the runtime", n);
+    /// }
+    /// ```
+    pub fn remote_schedule_count(&self) -> u64 {
+        self.handle
+            .inner
+            .scheduler_metrics()
+            .remote_schedule_count
+            .load(Relaxed)
+    }
+
+    /// Returns the number of times that tasks have been forced to yield back to the scheduler
+    /// after exhausting their task budgets.
+    ///
+    /// This count starts at zero when the runtime is created and increases by one each time a task yields due to exhausting its budget.
+    ///
+    /// The counter is monotonically increasing. It is never decremented or
+    /// reset to zero.
+    pub fn budget_forced_yield_count(&self) -> u64 {
+        self.handle
+            .inner
+            .scheduler_metrics()
+            .budget_forced_yield_count
+            .load(Relaxed)
+    }
+
+    /// Returns the total number of times the given worker thread has parked.
+    ///
+    /// The worker park count starts at zero when the runtime is created and
+    /// increases by one each time the worker parks the thread waiting for new
+    /// inbound events to process. This usually means the worker has processed
+    /// all pending work and is currently idle.
+    ///
+    /// The counter is monotonically increasing. It is never decremented or
+    /// reset to zero.
+    ///
+    /// # Arguments
+    ///
+    /// `worker` is the index of the worker being queried. The given value must
+    /// be between 0 and `num_workers()`. The index uniquely identifies a single
+    /// worker and will continue to identify the worker throughout the lifetime
+    /// of the runtime instance.
+    ///
+    /// # Panics
+    ///
+    /// The method panics when `worker` represents an invalid worker, i.e. is
+    /// greater than or equal to `num_workers()`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::runtime::Handle;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let metrics = Handle::current().metrics();
+    ///
+    ///     let n = metrics.worker_park_count(0);
+    ///     println!("worker 0 parked {} times", n);
+    /// }
+    /// ```
+    pub fn worker_park_count(&self, worker: usize) -> u64 {
+        self.handle
+            .inner
+            .worker_metrics(worker)
+            .park_count
+            .load(Relaxed)
+    }
+
+    /// Returns the number of times the given worker thread unparked but
+    /// performed no work before parking again.
+    ///
+    /// The worker no-op count starts at zero when the runtime is created and
+    /// increases by one each time the worker unparks the thread but finds no
+    /// new work and goes back to sleep. This indicates a false-positive wake up.
+    ///
+    /// The counter is monotonically increasing. It is never decremented or
+    /// reset to zero.
+    ///
+    /// # Arguments
+    ///
+    /// `worker` is the index of the worker being queried. The given value must
+    /// be between 0 and `num_workers()`. The index uniquely identifies a single
+    /// worker and will continue to identify the worker throughout the lifetime
+    /// of the runtime instance.
+    ///
+    /// # Panics
+    ///
+    /// The method panics when `worker` represents an invalid worker, i.e. is
+    /// greater than or equal to `num_workers()`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::runtime::Handle;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let metrics = Handle::current().metrics();
+    ///
+    ///     let n = metrics.worker_noop_count(0);
+    ///     println!("worker 0 had {} no-op unparks", n);
+    /// }
+    /// ```
+    pub fn worker_noop_count(&self, worker: usize) -> u64 {
+        self.handle
+            .inner
+            .worker_metrics(worker)
+            .noop_count
+            .load(Relaxed)
+    }
+
+    /// Returns the number of tasks the given worker thread stole from
+    /// another worker thread.
+    ///
+    /// This metric only applies to the **multi-threaded** runtime and will
+    /// always return `0` when using the current thread runtime.
+    ///
+    /// The worker steal count starts at zero when the runtime is created and
+    /// increases by `N` each time the worker has processed its scheduled queue
+    /// and successfully steals `N` more pending tasks from another worker.
+    ///
+    /// The counter is monotonically increasing. It is never decremented or
+    /// reset to zero.
+    ///
+    /// # Arguments
+    ///
+    /// `worker` is the index of the worker being queried. The given value must
+    /// be between 0 and `num_workers()`. The index uniquely identifies a single
+    /// worker and will continue to identify the worker throughout the lifetime
+    /// of the runtime instance.
+    ///
+    /// # Panics
+    ///
+    /// The method panics when `worker` represents an invalid worker, i.e. is
+    /// greater than or equal to `num_workers()`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::runtime::Handle;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let metrics = Handle::current().metrics();
+    ///
+    ///     let n = metrics.worker_steal_count(0);
+    ///     println!("worker 0 has stolen {} tasks", n);
+    /// }
+    /// ```
+    pub fn worker_steal_count(&self, worker: usize) -> u64 {
+        self.handle
+            .inner
+            .worker_metrics(worker)
+            .steal_count
+            .load(Relaxed)
+    }
+
+    /// Returns the number of times the given worker thread stole tasks from
+    /// another worker thread.
+    ///
+    /// This metric only applies to the **multi-threaded** runtime and will
+    /// always return `0` when using the current thread runtime.
+    ///
+    /// The worker steal count starts at zero when the runtime is created and
+    /// increases by one each time the worker has processed its scheduled queue
+    /// and successfully steals more pending tasks from another worker.
+    ///
+    /// The counter is monotonically increasing. It is never decremented or
+    /// reset to zero.
+    ///
+    /// # Arguments
+    ///
+    /// `worker` is the index of the worker being queried. The given value must
+    /// be between 0 and `num_workers()`. The index uniquely identifies a single
+    /// worker and will continue to identify the worker throughout the lifetime
+    /// of the runtime instance.
+    ///
+    /// # Panics
+    ///
+    /// The method panics when `worker` represents an invalid worker, i.e. is
+    /// greater than or equal to `num_workers()`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::runtime::Handle;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let metrics = Handle::current().metrics();
+    ///
+    ///     let n = metrics.worker_steal_operations(0);
+    ///     println!("worker 0 has stolen tasks {} times", n);
+    /// }
+    /// ```
+    pub fn worker_steal_operations(&self, worker: usize) -> u64 {
+        self.handle
+            .inner
+            .worker_metrics(worker)
+            .steal_operations
+            .load(Relaxed)
+    }
+
+    /// Returns the number of tasks the given worker thread has polled.
+    ///
+    /// The worker poll count starts at zero when the runtime is created and
+    /// increases by one each time the worker polls a scheduled task.
+    ///
+    /// The counter is monotonically increasing. It is never decremented or
+    /// reset to zero.
+    ///
+    /// # Arguments
+    ///
+    /// `worker` is the index of the worker being queried. The given value must
+    /// be between 0 and `num_workers()`. The index uniquely identifies a single
+    /// worker and will continue to identify the worker throughout the lifetime
+    /// of the runtime instance.
+    ///
+    /// # Panics
+    ///
+    /// The method panics when `worker` represents an invalid worker, i.e. is
+    /// greater than or equal to `num_workers()`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::runtime::Handle;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let metrics = Handle::current().metrics();
+    ///
+    ///     let n = metrics.worker_poll_count(0);
+    ///     println!("worker 0 has polled {} tasks", n);
+    /// }
+    /// ```
+    pub fn worker_poll_count(&self, worker: usize) -> u64 {
+        self.handle
+            .inner
+            .worker_metrics(worker)
+            .poll_count
+            .load(Relaxed)
+    }
+
+    /// Returns the amount of time the given worker thread has been busy.
+    ///
+    /// The worker busy duration starts at zero when the runtime is created and
+    /// increases whenever the worker is spending time processing work. Using
+    /// this value can indicate the load of the given worker. If a lot of time
+    /// is spent busy, then the worker is under load and will check for inbound
+    /// events less often.
+    ///
+    /// The timer is monotonically increasing. It is never decremented or reset
+    /// to zero.
+    ///
+    /// # Arguments
+    ///
+    /// `worker` is the index of the worker being queried. The given value must
+    /// be between 0 and `num_workers()`. The index uniquely identifies a single
+    /// worker and will continue to identify the worker throughout the lifetime
+    /// of the runtime instance.
+    ///
+    /// # Panics
+    ///
+    /// The method panics when `worker` represents an invalid worker, i.e. is
+    /// greater than or equal to `num_workers()`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::runtime::Handle;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let metrics = Handle::current().metrics();
+    ///
+    ///     let n = metrics.worker_total_busy_duration(0);
+    ///     println!("worker 0 was busy for a total of {:?}", n);
+    /// }
+    /// ```
+    pub fn worker_total_busy_duration(&self, worker: usize) -> Duration {
+        let nanos = self
+            .handle
+            .inner
+            .worker_metrics(worker)
+            .busy_duration_total
+            .load(Relaxed);
+        Duration::from_nanos(nanos)
+    }
+
+    /// Returns the number of tasks scheduled from **within** the runtime on the
+    /// given worker's local queue.
+    ///
+    /// The local schedule count starts at zero when the runtime is created and
+    /// increases by one each time a task is woken from **inside** of the
+    /// runtime on the given worker. This usually means that a task is spawned
+    /// or notified from within a runtime thread and will be queued on the
+    /// worker-local queue.
+    ///
+    /// The counter is monotonically increasing. It is never decremented or
+    /// reset to zero.
+    ///
+    /// # Arguments
+    ///
+    /// `worker` is the index of the worker being queried. The given value must
+    /// be between 0 and `num_workers()`. The index uniquely identifies a single
+    /// worker and will continue to identify the worker throughout the lifetime
+    /// of the runtime instance.
+    ///
+    /// # Panics
+    ///
+    /// The method panics when `worker` represents an invalid worker, i.e. is
+    /// greater than or equal to `num_workers()`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::runtime::Handle;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let metrics = Handle::current().metrics();
+    ///
+    ///     let n = metrics.worker_local_schedule_count(0);
+    ///     println!("{} tasks were scheduled on the worker's local queue", n);
+    /// }
+    /// ```
+    pub fn worker_local_schedule_count(&self, worker: usize) -> u64 {
+        self.handle
+            .inner
+            .worker_metrics(worker)
+            .local_schedule_count
+            .load(Relaxed)
+    }
+
+    /// Returns the number of times the given worker thread saturated its local
+    /// queue.
+    ///
+    /// This metric only applies to the **multi-threaded** scheduler.
+    ///
+    /// The worker steal count starts at zero when the runtime is created and
+    /// increases by one each time the worker attempts to schedule a task
+    /// locally, but its local queue is full. When this happens, half of the
+    /// local queue is moved to the injection queue.
+    ///
+    /// The counter is monotonically increasing. It is never decremented or
+    /// reset to zero.
+    ///
+    /// # Arguments
+    ///
+    /// `worker` is the index of the worker being queried. The given value must
+    /// be between 0 and `num_workers()`. The index uniquely identifies a single
+    /// worker and will continue to identify the worker throughout the lifetime
+    /// of the runtime instance.
+    ///
+    /// # Panics
+    ///
+    /// The method panics when `worker` represents an invalid worker, i.e. is
+    /// greater than or equal to `num_workers()`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::runtime::Handle;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let metrics = Handle::current().metrics();
+    ///
+    ///     let n = metrics.worker_overflow_count(0);
+    ///     println!("worker 0 has overflowed its queue {} times", n);
+    /// }
+    /// ```
+    pub fn worker_overflow_count(&self, worker: usize) -> u64 {
+        self.handle
+            .inner
+            .worker_metrics(worker)
+            .overflow_count
+            .load(Relaxed)
+    }
+
+    /// Returns the number of tasks currently scheduled in the runtime's
+    /// injection queue.
+    ///
+    /// Tasks that are spawned or notified from a non-runtime thread are
+    /// scheduled using the runtime's injection queue. This metric returns the
+    /// **current** number of tasks pending in the injection queue. As such, the
+    /// returned value may increase or decrease as new tasks are scheduled and
+    /// processed.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::runtime::Handle;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let metrics = Handle::current().metrics();
+    ///
+    ///     let n = metrics.injection_queue_depth();
+    ///     println!("{} tasks currently pending in the runtime's injection queue", n);
+    /// }
+    /// ```
+    pub fn injection_queue_depth(&self) -> usize {
+        self.handle.inner.injection_queue_depth()
+    }
+
+    /// Returns the number of tasks currently scheduled in the given worker's
+    /// local queue.
+    ///
+    /// Tasks that are spawned or notified from within a runtime thread are
+    /// scheduled using that worker's local queue. This metric returns the
+    /// **current** number of tasks pending in the worker's local queue. As
+    /// such, the returned value may increase or decrease as new tasks are
+    /// scheduled and processed.
+    ///
+    /// # Arguments
+    ///
+    /// `worker` is the index of the worker being queried. The given value must
+    /// be between 0 and `num_workers()`. The index uniquely identifies a single
+    /// worker and will continue to identify the worker throughout the lifetime
+    /// of the runtime instance.
+    ///
+    /// # Panics
+    ///
+    /// The method panics when `worker` represents an invalid worker, i.e. is
+    /// greater than or equal to `num_workers()`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::runtime::Handle;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let metrics = Handle::current().metrics();
+    ///
+    ///     let n = metrics.worker_local_queue_depth(0);
+    ///     println!("{} tasks currently pending in worker 0's local queue", n);
+    /// }
+    /// ```
+    pub fn worker_local_queue_depth(&self, worker: usize) -> usize {
+        self.handle.inner.worker_local_queue_depth(worker)
+    }
+
+    /// Returns `true` if the runtime is tracking the distribution of task poll
+    /// times.
+    ///
+    /// Task poll times are not instrumented by default as doing so requires
+    /// calling [`Instant::now()`] twice per task poll. The feature is enabled
+    /// by calling [`enable_metrics_poll_count_histogram()`] when building the
+    /// runtime.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::runtime::{self, Handle};
+    ///
+    /// fn main() {
+    ///     runtime::Builder::new_current_thread()
+    ///         .enable_metrics_poll_count_histogram()
+    ///         .build()
+    ///         .unwrap()
+    ///         .block_on(async {
+    ///             let metrics = Handle::current().metrics();
+    ///             let enabled = metrics.poll_count_histogram_enabled();
+    ///
+    ///             println!("Tracking task poll time distribution: {:?}", enabled);
+    ///         });
+    /// }
+    /// ```
+    ///
+    /// [`enable_metrics_poll_count_histogram()`]: crate::runtime::Builder::enable_metrics_poll_count_histogram
+    /// [`Instant::now()`]: std::time::Instant::now
+    pub fn poll_count_histogram_enabled(&self) -> bool {
+        self.handle
+            .inner
+            .worker_metrics(0)
+            .poll_count_histogram
+            .is_some()
+    }
+
+    /// Returns the number of histogram buckets tracking the distribution of
+    /// task poll times.
+    ///
+    /// This value is configured by calling
+    /// [`metrics_poll_count_histogram_buckets()`] when building the runtime.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::runtime::{self, Handle};
+    ///
+    /// fn main() {
+    ///     runtime::Builder::new_current_thread()
+    ///         .enable_metrics_poll_count_histogram()
+    ///         .build()
+    ///         .unwrap()
+    ///         .block_on(async {
+    ///             let metrics = Handle::current().metrics();
+    ///             let buckets = metrics.poll_count_histogram_num_buckets();
+    ///
+    ///             println!("Histogram buckets: {:?}", buckets);
+    ///         });
+    /// }
+    /// ```
+    ///
+    /// [`metrics_poll_count_histogram_buckets()`]:
+    ///     crate::runtime::Builder::metrics_poll_count_histogram_buckets
+    pub fn poll_count_histogram_num_buckets(&self) -> usize {
+        self.handle
+            .inner
+            .worker_metrics(0)
+            .poll_count_histogram
+            .as_ref()
+            .map(|histogram| histogram.num_buckets())
+            .unwrap_or_default()
+    }
+
+    /// Returns the range of task poll times tracked by the given bucket.
+    ///
+    /// This value is configured by calling
+    /// [`metrics_poll_count_histogram_resolution()`] when building the runtime.
+    ///
+    /// # Panics
+    ///
+    /// The method panics if `bucket` represents an invalid bucket index, i.e.
+    /// is greater than or equal to `poll_count_histogram_num_buckets()`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::runtime::{self, Handle};
+    ///
+    /// fn main() {
+    ///     runtime::Builder::new_current_thread()
+    ///         .enable_metrics_poll_count_histogram()
+    ///         .build()
+    ///         .unwrap()
+    ///         .block_on(async {
+    ///             let metrics = Handle::current().metrics();
+    ///             let buckets = metrics.poll_count_histogram_num_buckets();
+    ///
+    ///             for i in 0..buckets {
+    ///                 let range = metrics.poll_count_histogram_bucket_range(i);
+    ///                 println!("Histogram bucket {} range: {:?}", i, range);
+    ///             }
+    ///         });
+    /// }
+    /// ```
+    ///
+    /// [`metrics_poll_count_histogram_resolution()`]:
+    ///     crate::runtime::Builder::metrics_poll_count_histogram_resolution
+    #[track_caller]
+    pub fn poll_count_histogram_bucket_range(&self, bucket: usize) -> Range<Duration> {
+        self.handle
+            .inner
+            .worker_metrics(0)
+            .poll_count_histogram
+            .as_ref()
+            .map(|histogram| {
+                let range = histogram.bucket_range(bucket);
+                std::ops::Range {
+                    start: Duration::from_nanos(range.start),
+                    end: Duration::from_nanos(range.end),
+                }
+            })
+            .unwrap_or_default()
+    }
+
+    /// Returns the number of times the given worker polled tasks with a poll
+    /// duration within the given bucket's range.
+    ///
+    /// Each worker maintains its own histogram and the counts for each bucket
+    /// starts at zero when the runtime is created. Each time the worker polls a
+    /// task, it tracks the duration the task poll time took and increments the
+    /// associated bucket by 1.
+    ///
+    /// Each bucket is a monotonically increasing counter. It is never
+    /// decremented or reset to zero.
+    ///
+    /// # Arguments
+    ///
+    /// `worker` is the index of the worker being queried. The given value must
+    /// be between 0 and `num_workers()`. The index uniquely identifies a single
+    /// worker and will continue to identify the worker throughout the lifetime
+    /// of the runtime instance.
+    ///
+    /// `bucket` is the index of the bucket being queried. The bucket is scoped
+    /// to the worker. The range represented by the bucket can be queried by
+    /// calling [`poll_count_histogram_bucket_range()`]. Each worker maintains
+    /// identical bucket ranges.
+    ///
+    /// # Panics
+    ///
+    /// The method panics when `worker` represents an invalid worker, i.e. is
+    /// greater than or equal to `num_workers()` or if `bucket` represents an
+    /// invalid bucket.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::runtime::{self, Handle};
+    ///
+    /// fn main() {
+    ///     runtime::Builder::new_current_thread()
+    ///         .enable_metrics_poll_count_histogram()
+    ///         .build()
+    ///         .unwrap()
+    ///         .block_on(async {
+    ///             let metrics = Handle::current().metrics();
+    ///             let buckets = metrics.poll_count_histogram_num_buckets();
+    ///
+    ///             for worker in 0..metrics.num_workers() {
+    ///                 for i in 0..buckets {
+    ///                     let count = metrics.poll_count_histogram_bucket_count(worker, i);
+    ///                     println!("Poll count {}", count);
+    ///                 }
+    ///             }
+    ///         });
+    /// }
+    /// ```
+    ///
+    /// [`poll_count_histogram_bucket_range()`]: crate::runtime::RuntimeMetrics::poll_count_histogram_bucket_range
+    #[track_caller]
+    pub fn poll_count_histogram_bucket_count(&self, worker: usize, bucket: usize) -> u64 {
+        self.handle
+            .inner
+            .worker_metrics(worker)
+            .poll_count_histogram
+            .as_ref()
+            .map(|histogram| histogram.get(bucket))
+            .unwrap_or_default()
+    }
+
+    /// Returns the number of tasks currently scheduled in the blocking
+    /// thread pool, spawned using `spawn_blocking`.
+    ///
+    /// This metric returns the **current** number of tasks pending in
+    /// blocking thread pool. As such, the returned value may increase
+    /// or decrease as new tasks are scheduled and processed.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::runtime::Handle;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let metrics = Handle::current().metrics();
+    ///
+    ///     let n = metrics.blocking_queue_depth();
+    ///     println!("{} tasks currently pending in the blocking thread pool", n);
+    /// }
+    /// ```
+    pub fn blocking_queue_depth(&self) -> usize {
+        self.handle.inner.blocking_queue_depth()
+    }
+}
+
+cfg_net! {
+    impl RuntimeMetrics {
+        /// Returns the number of file descriptors that have been registered with the
+        /// runtime's I/O driver.
+        ///
+        /// # Examples
+        ///
+        /// ```
+        /// use tokio::runtime::Handle;
+        ///
+        /// #[tokio::main]
+        /// async fn main() {
+        ///     let metrics = Handle::current().metrics();
+        ///
+        ///     let registered_fds = metrics.io_driver_fd_registered_count();
+        ///     println!("{} fds have been registered with the runtime's I/O driver.", registered_fds);
+        ///
+        ///     let deregistered_fds = metrics.io_driver_fd_deregistered_count();
+        ///
+        ///     let current_fd_count = registered_fds - deregistered_fds;
+        ///     println!("{} fds are currently registered by the runtime's I/O driver.", current_fd_count);
+        /// }
+        /// ```
+        pub fn io_driver_fd_registered_count(&self) -> u64 {
+            self.with_io_driver_metrics(|m| {
+                m.fd_registered_count.load(Relaxed)
+            })
+        }
+
+        /// Returns the number of file descriptors that have been deregistered by the
+        /// runtime's I/O driver.
+        ///
+        /// # Examples
+        ///
+        /// ```
+        /// use tokio::runtime::Handle;
+        ///
+        /// #[tokio::main]
+        /// async fn main() {
+        ///     let metrics = Handle::current().metrics();
+        ///
+        ///     let n = metrics.io_driver_fd_deregistered_count();
+        ///     println!("{} fds have been deregistered by the runtime's I/O driver.", n);
+        /// }
+        /// ```
+        pub fn io_driver_fd_deregistered_count(&self) -> u64 {
+            self.with_io_driver_metrics(|m| {
+                m.fd_deregistered_count.load(Relaxed)
+            })
+        }
+
+        /// Returns the number of ready events processed by the runtime's
+        /// I/O driver.
+        ///
+        /// # Examples
+        ///
+        /// ```
+        /// use tokio::runtime::Handle;
+        ///
+        /// #[tokio::main]
+        /// async fn main() {
+        ///     let metrics = Handle::current().metrics();
+        ///
+        ///     let n = metrics.io_driver_ready_count();
+        ///     println!("{} ready events processed by the runtime's I/O driver.", n);
+        /// }
+        /// ```
+        pub fn io_driver_ready_count(&self) -> u64 {
+            self.with_io_driver_metrics(|m| m.ready_count.load(Relaxed))
+        }
+
+        fn with_io_driver_metrics<F>(&self, f: F) -> u64
+        where
+            F: Fn(&super::IoDriverMetrics) -> u64,
+        {
+            // TODO: Investigate if this should return 0, most of our metrics always increase
+            // thus this breaks that guarantee.
+            self.handle
+                .inner
+                .driver()
+                .io
+                .as_ref()
+                .map(|h| f(&h.metrics))
+                .unwrap_or(0)
+        }
+    }
+}
diff --git a/vendor/tokio/src/runtime/metrics/scheduler.rs b/vendor/tokio/src/runtime/metrics/scheduler.rs
new file mode 100644
index 000000000..d9f8edfaa
--- /dev/null
+++ b/vendor/tokio/src/runtime/metrics/scheduler.rs
@@ -0,0 +1,34 @@
+use crate::loom::sync::atomic::{AtomicU64, Ordering::Relaxed};
+
+/// Retrieves metrics from the Tokio runtime.
+///
+/// **Note**: This is an [unstable API][unstable]. The public API of this type
+/// may break in 1.x releases. See [the documentation on unstable
+/// features][unstable] for details.
+///
+/// [unstable]: crate#unstable-features
+#[derive(Debug)]
+pub(crate) struct SchedulerMetrics {
+    /// Number of tasks that are scheduled from outside the runtime.
+    pub(super) remote_schedule_count: AtomicU64,
+    pub(super) budget_forced_yield_count: AtomicU64,
+}
+
+impl SchedulerMetrics {
+    pub(crate) fn new() -> SchedulerMetrics {
+        SchedulerMetrics {
+            remote_schedule_count: AtomicU64::new(0),
+            budget_forced_yield_count: AtomicU64::new(0),
+        }
+    }
+
+    /// Increment the number of tasks scheduled externally
+    pub(crate) fn inc_remote_schedule_count(&self) {
+        self.remote_schedule_count.fetch_add(1, Relaxed);
+    }
+
+    /// Increment the number of tasks forced to yield due to budget exhaustion
+    pub(crate) fn inc_budget_forced_yield_count(&self) {
+        self.budget_forced_yield_count.fetch_add(1, Relaxed);
+    }
+}
diff --git a/vendor/tokio/src/runtime/metrics/worker.rs b/vendor/tokio/src/runtime/metrics/worker.rs
new file mode 100644
index 000000000..e0f23e6a0
--- /dev/null
+++ b/vendor/tokio/src/runtime/metrics/worker.rs
@@ -0,0 +1,80 @@
+use crate::loom::sync::atomic::Ordering::Relaxed;
+use crate::loom::sync::atomic::{AtomicU64, AtomicUsize};
+use crate::runtime::metrics::Histogram;
+use crate::runtime::Config;
+
+/// Retrieve runtime worker metrics.
+///
+/// **Note**: This is an [unstable API][unstable]. The public API of this type
+/// may break in 1.x releases. See [the documentation on unstable
+/// features][unstable] for details.
+///
+/// [unstable]: crate#unstable-features
+#[derive(Debug)]
+#[repr(align(128))]
+pub(crate) struct WorkerMetrics {
+    ///  Number of times the worker parked.
+    pub(crate) park_count: AtomicU64,
+
+    /// Number of times the worker woke then parked again without doing work.
+    pub(crate) noop_count: AtomicU64,
+
+    /// Number of tasks the worker stole.
+    pub(crate) steal_count: AtomicU64,
+
+    /// Number of times the worker stole
+    pub(crate) steal_operations: AtomicU64,
+
+    /// Number of tasks the worker polled.
+    pub(crate) poll_count: AtomicU64,
+
+    /// Amount of time the worker spent doing work vs. parking.
+    pub(crate) busy_duration_total: AtomicU64,
+
+    /// Number of tasks scheduled for execution on the worker's local queue.
+    pub(crate) local_schedule_count: AtomicU64,
+
+    /// Number of tasks moved from the local queue to the global queue to free space.
+    pub(crate) overflow_count: AtomicU64,
+
+    /// Number of tasks currently in the local queue. Used only by the
+    /// current-thread scheduler.
+    pub(crate) queue_depth: AtomicUsize,
+
+    /// If `Some`, tracks the the number of polls by duration range.
+    pub(super) poll_count_histogram: Option<Histogram>,
+}
+
+impl WorkerMetrics {
+    pub(crate) fn from_config(config: &Config) -> WorkerMetrics {
+        let mut worker_metrics = WorkerMetrics::new();
+        worker_metrics.poll_count_histogram = config
+            .metrics_poll_count_histogram
+            .as_ref()
+            .map(|histogram_builder| histogram_builder.build());
+        worker_metrics
+    }
+
+    pub(crate) fn new() -> WorkerMetrics {
+        WorkerMetrics {
+            park_count: AtomicU64::new(0),
+            noop_count: AtomicU64::new(0),
+            steal_count: AtomicU64::new(0),
+            steal_operations: AtomicU64::new(0),
+            poll_count: AtomicU64::new(0),
+            overflow_count: AtomicU64::new(0),
+            busy_duration_total: AtomicU64::new(0),
+            local_schedule_count: AtomicU64::new(0),
+            queue_depth: AtomicUsize::new(0),
+            poll_count_histogram: None,
+        }
+    }
+
+    pub(crate) fn queue_depth(&self) -> usize {
+        self.queue_depth.load(Relaxed)
+    }
+
+    pub(crate) fn set_queue_depth(&self, len: usize) {
+        self.queue_depth.store(len, Relaxed);
+    }
+}
diff --git a/vendor/tokio/src/runtime/mod.rs b/vendor/tokio/src/runtime/mod.rs
index 52532ec6f..cb198f51f 100644
--- a/vendor/tokio/src/runtime/mod.rs
+++ b/vendor/tokio/src/runtime/mod.rs
@@ -137,7 +137,7 @@
 //! use tokio::runtime;
 //!
 //! # fn main() -> Result<(), Box<dyn std::error::Error>> {
-//! let basic_rt = runtime::Builder::new_current_thread()
+//! let rt = runtime::Builder::new_current_thread()
 //!     .build()?;
 //! # Ok(()) }
 //! ```
@@ -156,9 +156,11 @@
 //! multi-thread scheduler spawns threads to schedule tasks and for `spawn_blocking`
 //! calls.
 //!
-//! While the `Runtime` is active, threads may shutdown after periods of being
-//! idle. Once `Runtime` is dropped, all runtime threads are forcibly shutdown.
-//! Any tasks that have not yet completed will be dropped.
+//! While the `Runtime` is active, threads may shut down after periods of being
+//! idle. Once `Runtime` is dropped, all runtime threads have usually been
+//! terminated, but in the presence of unstoppable spawned work are not
+//! guaranteed to have been terminated. See the
+//! [struct level documentation](Runtime#shutdown) for more details.
 //!
 //! [tasks]: crate::task
 //! [`Runtime`]: Runtime
@@ -166,7 +168,6 @@
 //! [`tokio::main`]: ../attr.main.html
 //! [runtime builder]: crate::runtime::Builder
 //! [`Runtime::new`]: crate::runtime::Runtime::new
-//! [`Builder::basic_scheduler`]: crate::runtime::Builder::basic_scheduler
 //! [`Builder::threaded_scheduler`]: crate::runtime::Builder::threaded_scheduler
 //! [`Builder::enable_io`]: crate::runtime::Builder::enable_io
 //! [`Builder::enable_time`]: crate::runtime::Builder::enable_time
@@ -174,390 +175,91 @@
 
 // At the top due to macros
 #[cfg(test)]
+#[cfg(not(tokio_wasm))]
 #[macro_use]
 mod tests;
 
-pub(crate) mod enter;
+pub(crate) mod context;
 
-pub(crate) mod task;
+pub(crate) mod coop;
 
-cfg_rt! {
-    mod basic_scheduler;
-    use basic_scheduler::BasicScheduler;
+pub(crate) mod park;
 
-    mod blocking;
-    use blocking::BlockingPool;
-    pub(crate) use blocking::spawn_blocking;
+mod driver;
 
-    mod builder;
-    pub use self::builder::Builder;
-
-    pub(crate) mod context;
-    pub(crate) mod driver;
-
-    use self::enter::enter;
-
-    mod handle;
-    pub use handle::{EnterGuard, Handle};
+pub(crate) mod scheduler;
 
-    mod spawner;
-    use self::spawner::Spawner;
+cfg_io_driver_impl! {
+    pub(crate) mod io;
 }
 
-cfg_rt_multi_thread! {
-    mod park;
-    use park::Parker;
+cfg_process_driver! {
+    mod process;
 }
 
-cfg_rt_multi_thread! {
-    mod queue;
+cfg_time! {
+    pub(crate) mod time;
+}
 
-    pub(crate) mod thread_pool;
-    use self::thread_pool::ThreadPool;
+cfg_signal_internal_and_unix! {
+    pub(crate) mod signal;
 }
 
 cfg_rt! {
-    use crate::task::JoinHandle;
-
-    use std::future::Future;
-    use std::time::Duration;
+    pub(crate) mod task;
 
-    /// The Tokio runtime.
-    ///
-    /// The runtime provides an I/O driver, task scheduler, [timer], and
-    /// blocking pool, necessary for running asynchronous tasks.
-    ///
-    /// Instances of `Runtime` can be created using [`new`], or [`Builder`].
-    /// However, most users will use the `#[tokio::main]` annotation on their
-    /// entry point instead.
-    ///
-    /// See [module level][mod] documentation for more details.
-    ///
-    /// # Shutdown
-    ///
-    /// Shutting down the runtime is done by dropping the value. The current
-    /// thread will block until the shut down operation has completed.
-    ///
-    /// * Drain any scheduled work queues.
-    /// * Drop any futures that have not yet completed.
-    /// * Drop the reactor.
-    ///
-    /// Once the reactor has dropped, any outstanding I/O resources bound to
-    /// that reactor will no longer function. Calling any method on them will
-    /// result in an error.
-    ///
-    /// # Sharing
-    ///
-    /// The Tokio runtime implements `Sync` and `Send` to allow you to wrap it
-    /// in a `Arc`. Most fn take `&self` to allow you to call them concurrently
-    /// across multiple threads.
-    ///
-    /// Calls to `shutdown` and `shutdown_timeout` require exclusive ownership of
-    /// the runtime type and this can be achieved via `Arc::try_unwrap` when only
-    /// one strong count reference is left over.
-    ///
-    /// [timer]: crate::time
-    /// [mod]: index.html
-    /// [`new`]: method@Self::new
-    /// [`Builder`]: struct@Builder
-    #[derive(Debug)]
-    pub struct Runtime {
-        /// Task executor
-        kind: Kind,
+    mod config;
+    use config::Config;
 
-        /// Handle to runtime, also contains driver handles
-        handle: Handle,
+    mod blocking;
+    #[cfg_attr(tokio_wasi, allow(unused_imports))]
+    pub(crate) use blocking::spawn_blocking;
 
-        /// Blocking pool handle, used to signal shutdown
-        blocking_pool: BlockingPool,
+    cfg_trace! {
+        pub(crate) use blocking::Mandatory;
     }
 
-    /// The runtime executor is either a thread-pool or a current-thread executor.
-    #[derive(Debug)]
-    enum Kind {
-        /// Execute all tasks on the current-thread.
-        CurrentThread(BasicScheduler<driver::Driver>),
-
-        /// Execute tasks across multiple threads.
-        #[cfg(feature = "rt-multi-thread")]
-        ThreadPool(ThreadPool),
+    cfg_fs! {
+        pub(crate) use blocking::spawn_mandatory_blocking;
     }
 
-    /// After thread starts / before thread stops
-    type Callback = std::sync::Arc<dyn Fn() + Send + Sync>;
-
-    impl Runtime {
-        /// Create a new runtime instance with default configuration values.
-        ///
-        /// This results in the multi threaded scheduler, I/O driver, and time driver being
-        /// initialized.
-        ///
-        /// Most applications will not need to call this function directly. Instead,
-        /// they will use the  [`#[tokio::main]` attribute][main]. When a more complex
-        /// configuration is necessary, the [runtime builder] may be used.
-        ///
-        /// See [module level][mod] documentation for more details.
-        ///
-        /// # Examples
-        ///
-        /// Creating a new `Runtime` with default configuration values.
-        ///
-        /// ```
-        /// use tokio::runtime::Runtime;
-        ///
-        /// let rt = Runtime::new()
-        ///     .unwrap();
-        ///
-        /// // Use the runtime...
-        /// ```
-        ///
-        /// [mod]: index.html
-        /// [main]: ../attr.main.html
-        /// [threaded scheduler]: index.html#threaded-scheduler
-        /// [basic scheduler]: index.html#basic-scheduler
-        /// [runtime builder]: crate::runtime::Builder
-        #[cfg(feature = "rt-multi-thread")]
-        #[cfg_attr(docsrs, doc(cfg(feature = "rt-multi-thread")))]
-        pub fn new() -> std::io::Result<Runtime> {
-            Builder::new_multi_thread().enable_all().build()
-        }
+    mod builder;
+    pub use self::builder::Builder;
+    cfg_unstable! {
+        pub use self::builder::UnhandledPanic;
+        pub use crate::util::rand::RngSeed;
+    }
 
-        /// Return a handle to the runtime's spawner.
-        ///
-        /// The returned handle can be used to spawn tasks that run on this runtime, and can
-        /// be cloned to allow moving the `Handle` to other threads.
-        ///
-        /// # Examples
-        ///
-        /// ```
-        /// use tokio::runtime::Runtime;
-        ///
-        /// let rt = Runtime::new()
-        ///     .unwrap();
-        ///
-        /// let handle = rt.handle();
-        ///
-        /// // Use the handle...
-        /// ```
-        pub fn handle(&self) -> &Handle {
-            &self.handle
-        }
+    cfg_taskdump! {
+        pub mod dump;
+        pub use dump::Dump;
+    }
 
-        /// Spawn a future onto the Tokio runtime.
-        ///
-        /// This spawns the given future onto the runtime's executor, usually a
-        /// thread pool. The thread pool is then responsible for polling the future
-        /// until it completes.
-        ///
-        /// See [module level][mod] documentation for more details.
-        ///
-        /// [mod]: index.html
-        ///
-        /// # Examples
-        ///
-        /// ```
-        /// use tokio::runtime::Runtime;
-        ///
-        /// # fn dox() {
-        /// // Create the runtime
-        /// let rt = Runtime::new().unwrap();
-        ///
-        /// // Spawn a future onto the runtime
-        /// rt.spawn(async {
-        ///     println!("now running on a worker thread");
-        /// });
-        /// # }
-        /// ```
-        #[cfg_attr(tokio_track_caller, track_caller)]
-        pub fn spawn<F>(&self, future: F) -> JoinHandle<F::Output>
-        where
-            F: Future + Send + 'static,
-            F::Output: Send + 'static,
-        {
-            self.handle.spawn(future)
-        }
+    mod handle;
+    pub use handle::{EnterGuard, Handle, TryCurrentError};
 
-        /// Run the provided function on an executor dedicated to blocking operations.
-        ///
-        /// # Examples
-        ///
-        /// ```
-        /// use tokio::runtime::Runtime;
-        ///
-        /// # fn dox() {
-        /// // Create the runtime
-        /// let rt = Runtime::new().unwrap();
-        ///
-        /// // Spawn a blocking function onto the runtime
-        /// rt.spawn_blocking(|| {
-        ///     println!("now running on a worker thread");
-        /// });
-        /// # }
-        #[cfg_attr(tokio_track_caller, track_caller)]
-        pub fn spawn_blocking<F, R>(&self, func: F) -> JoinHandle<R>
-        where
-            F: FnOnce() -> R + Send + 'static,
-            R: Send + 'static,
-        {
-            self.handle.spawn_blocking(func)
-        }
+    mod runtime;
+    pub use runtime::{Runtime, RuntimeFlavor};
 
-        /// Run a future to completion on the Tokio runtime. This is the
-        /// runtime's entry point.
-        ///
-        /// This runs the given future on the current thread, blocking until it is
-        /// complete, and yielding its resolved result. Any tasks or timers
-        /// which the future spawns internally will be executed on the runtime.
-        ///
-        /// # Multi thread scheduler
-        ///
-        /// When the multi thread scheduler is used this will allow futures
-        /// to run within the io driver and timer context of the overall runtime.
-        ///
-        /// # Current thread scheduler
-        ///
-        /// When the current thread scheduler is enabled `block_on`
-        /// can be called concurrently from multiple threads. The first call
-        /// will take ownership of the io and timer drivers. This means
-        /// other threads which do not own the drivers will hook into that one.
-        /// When the first `block_on` completes, other threads will be able to
-        /// "steal" the driver to allow continued execution of their futures.
-        ///
-        /// # Panics
-        ///
-        /// This function panics if the provided future panics, or if called within an
-        /// asynchronous execution context.
-        ///
-        /// # Examples
-        ///
-        /// ```no_run
-        /// use tokio::runtime::Runtime;
-        ///
-        /// // Create the runtime
-        /// let rt  = Runtime::new().unwrap();
-        ///
-        /// // Execute the future, blocking the current thread until completion
-        /// rt.block_on(async {
-        ///     println!("hello");
-        /// });
-        /// ```
-        ///
-        /// [handle]: fn@Handle::block_on
-        pub fn block_on<F: Future>(&self, future: F) -> F::Output {
-            let _enter = self.enter();
+    mod thread_id;
+    pub(crate) use thread_id::ThreadId;
 
-            match &self.kind {
-                Kind::CurrentThread(exec) => exec.block_on(future),
-                #[cfg(feature = "rt-multi-thread")]
-                Kind::ThreadPool(exec) => exec.block_on(future),
-            }
-        }
+    cfg_metrics! {
+        mod metrics;
+        pub use metrics::{RuntimeMetrics, HistogramScale};
 
-        /// Enter the runtime context.
-        ///
-        /// This allows you to construct types that must have an executor
-        /// available on creation such as [`Sleep`] or [`TcpStream`]. It will
-        /// also allow you to call methods such as [`tokio::spawn`].
-        ///
-        /// [`Sleep`]: struct@crate::time::Sleep
-        /// [`TcpStream`]: struct@crate::net::TcpStream
-        /// [`tokio::spawn`]: fn@crate::spawn
-        ///
-        /// # Example
-        ///
-        /// ```
-        /// use tokio::runtime::Runtime;
-        ///
-        /// fn function_that_spawns(msg: String) {
-        ///     // Had we not used `rt.enter` below, this would panic.
-        ///     tokio::spawn(async move {
-        ///         println!("{}", msg);
-        ///     });
-        /// }
-        ///
-        /// fn main() {
-        ///     let rt = Runtime::new().unwrap();
-        ///
-        ///     let s = "Hello World!".to_string();
-        ///
-        ///     // By entering the context, we tie `tokio::spawn` to this executor.
-        ///     let _guard = rt.enter();
-        ///     function_that_spawns(s);
-        /// }
-        /// ```
-        pub fn enter(&self) -> EnterGuard<'_> {
-            self.handle.enter()
-        }
+        pub(crate) use metrics::{MetricsBatch, SchedulerMetrics, WorkerMetrics, HistogramBuilder};
 
-        /// Shutdown the runtime, waiting for at most `duration` for all spawned
-        /// task to shutdown.
-        ///
-        /// Usually, dropping a `Runtime` handle is sufficient as tasks are able to
-        /// shutdown in a timely fashion. However, dropping a `Runtime` will wait
-        /// indefinitely for all tasks to terminate, and there are cases where a long
-        /// blocking task has been spawned, which can block dropping `Runtime`.
-        ///
-        /// In this case, calling `shutdown_timeout` with an explicit wait timeout
-        /// can work. The `shutdown_timeout` will signal all tasks to shutdown and
-        /// will wait for at most `duration` for all spawned tasks to terminate. If
-        /// `timeout` elapses before all tasks are dropped, the function returns and
-        /// outstanding tasks are potentially leaked.
-        ///
-        /// # Examples
-        ///
-        /// ```
-        /// use tokio::runtime::Runtime;
-        /// use tokio::task;
-        ///
-        /// use std::thread;
-        /// use std::time::Duration;
-        ///
-        /// fn main() {
-        ///    let runtime = Runtime::new().unwrap();
-        ///
-        ///    runtime.block_on(async move {
-        ///        task::spawn_blocking(move || {
-        ///            thread::sleep(Duration::from_secs(10_000));
-        ///        });
-        ///    });
-        ///
-        ///    runtime.shutdown_timeout(Duration::from_millis(100));
-        /// }
-        /// ```
-        pub fn shutdown_timeout(mut self, duration: Duration) {
-            // Wakeup and shutdown all the worker threads
-            self.handle.shutdown();
-            self.blocking_pool.shutdown(Some(duration));
+        cfg_net! {
+        pub(crate) use metrics::IoDriverMetrics;
         }
+    }
 
-        /// Shutdown the runtime, without waiting for any spawned tasks to shutdown.
-        ///
-        /// This can be useful if you want to drop a runtime from within another runtime.
-        /// Normally, dropping a runtime will block indefinitely for spawned blocking tasks
-        /// to complete, which would normally not be permitted within an asynchronous context.
-        /// By calling `shutdown_background()`, you can drop the runtime from such a context.
-        ///
-        /// Note however, that because we do not wait for any blocking tasks to complete, this
-        /// may result in a resource leak (in that any blocking tasks are still running until they
-        /// return.
-        ///
-        /// This function is equivalent to calling `shutdown_timeout(Duration::of_nanos(0))`.
-        ///
-        /// ```
-        /// use tokio::runtime::Runtime;
-        ///
-        /// fn main() {
-        ///    let runtime = Runtime::new().unwrap();
-        ///
-        ///    runtime.block_on(async move {
-        ///        let inner_runtime = Runtime::new().unwrap();
-        ///        // ...
-        ///        inner_runtime.shutdown_background();
-        ///    });
-        /// }
-        /// ```
-        pub fn shutdown_background(self) {
-            self.shutdown_timeout(Duration::from_nanos(0))
-        }
+    cfg_not_metrics! {
+        pub(crate) mod metrics;
+        pub(crate) use metrics::{SchedulerMetrics, WorkerMetrics, MetricsBatch, HistogramBuilder};
     }
+
+    /// After thread starts / before thread stops
+    type Callback = std::sync::Arc<dyn Fn() + Send + Sync>;
 }
diff --git a/vendor/tokio/src/runtime/park.rs b/vendor/tokio/src/runtime/park.rs
index 033b9f20b..2392846ab 100644
--- a/vendor/tokio/src/runtime/park.rs
+++ b/vendor/tokio/src/runtime/park.rs
@@ -1,153 +1,102 @@
-//! Parks the runtime.
-//!
-//! A combination of the various resource driver park handles.
+#![cfg_attr(not(feature = "full"), allow(dead_code))]
 
 use crate::loom::sync::atomic::AtomicUsize;
 use crate::loom::sync::{Arc, Condvar, Mutex};
-use crate::loom::thread;
-use crate::park::{Park, Unpark};
-use crate::runtime::driver::Driver;
-use crate::util::TryLock;
 
 use std::sync::atomic::Ordering::SeqCst;
 use std::time::Duration;
 
-pub(crate) struct Parker {
+#[derive(Debug)]
+pub(crate) struct ParkThread {
     inner: Arc<Inner>,
 }
 
-pub(crate) struct Unparker {
+/// Unblocks a thread that was blocked by `ParkThread`.
+#[derive(Clone, Debug)]
+pub(crate) struct UnparkThread {
     inner: Arc<Inner>,
 }
 
+#[derive(Debug)]
 struct Inner {
-    /// Avoids entering the park if possible
     state: AtomicUsize,
-
-    /// Used to coordinate access to the driver / condvar
     mutex: Mutex<()>,
-
-    /// Condvar to block on if the driver is unavailable.
     condvar: Condvar,
-
-    /// Resource (I/O, time, ...) driver
-    shared: Arc<Shared>,
 }
 
 const EMPTY: usize = 0;
-const PARKED_CONDVAR: usize = 1;
-const PARKED_DRIVER: usize = 2;
-const NOTIFIED: usize = 3;
+const PARKED: usize = 1;
+const NOTIFIED: usize = 2;
 
-/// Shared across multiple Parker handles
-struct Shared {
-    /// Shared driver. Only one thread at a time can use this
-    driver: TryLock<Driver>,
+tokio_thread_local! {
+    static CURRENT_PARKER: ParkThread = ParkThread::new();
+}
 
-    /// Unpark handle
-    handle: <Driver as Park>::Unpark,
+// Bit of a hack, but it is only for loom
+#[cfg(loom)]
+tokio_thread_local! {
+    static CURRENT_THREAD_PARK_COUNT: AtomicUsize = AtomicUsize::new(0);
 }
 
-impl Parker {
-    pub(crate) fn new(driver: Driver) -> Parker {
-        let handle = driver.unpark();
+// ==== impl ParkThread ====
 
-        Parker {
+impl ParkThread {
+    pub(crate) fn new() -> Self {
+        Self {
             inner: Arc::new(Inner {
                 state: AtomicUsize::new(EMPTY),
                 mutex: Mutex::new(()),
                 condvar: Condvar::new(),
-                shared: Arc::new(Shared {
-                    driver: TryLock::new(driver),
-                    handle,
-                }),
             }),
         }
     }
-}
 
-impl Clone for Parker {
-    fn clone(&self) -> Parker {
-        Parker {
-            inner: Arc::new(Inner {
-                state: AtomicUsize::new(EMPTY),
-                mutex: Mutex::new(()),
-                condvar: Condvar::new(),
-                shared: self.inner.shared.clone(),
-            }),
-        }
+    pub(crate) fn unpark(&self) -> UnparkThread {
+        let inner = self.inner.clone();
+        UnparkThread { inner }
     }
-}
-
-impl Park for Parker {
-    type Unpark = Unparker;
-    type Error = ();
 
-    fn unpark(&self) -> Unparker {
-        Unparker {
-            inner: self.inner.clone(),
-        }
-    }
-
-    fn park(&mut self) -> Result<(), Self::Error> {
+    pub(crate) fn park(&mut self) {
+        #[cfg(loom)]
+        CURRENT_THREAD_PARK_COUNT.with(|count| count.fetch_add(1, SeqCst));
         self.inner.park();
-        Ok(())
     }
 
-    fn park_timeout(&mut self, duration: Duration) -> Result<(), Self::Error> {
-        // Only parking with zero is supported...
-        assert_eq!(duration, Duration::from_millis(0));
+    pub(crate) fn park_timeout(&mut self, duration: Duration) {
+        #[cfg(loom)]
+        CURRENT_THREAD_PARK_COUNT.with(|count| count.fetch_add(1, SeqCst));
 
-        if let Some(mut driver) = self.inner.shared.driver.try_lock() {
-            driver.park_timeout(duration).map_err(|_| ())
-        } else {
-            Ok(())
-        }
+        // Wasm doesn't have threads, so just sleep.
+        #[cfg(not(tokio_wasm))]
+        self.inner.park_timeout(duration);
+        #[cfg(tokio_wasm)]
+        std::thread::sleep(duration);
     }
 
-    fn shutdown(&mut self) {
+    pub(crate) fn shutdown(&mut self) {
         self.inner.shutdown();
     }
 }
 
-impl Unpark for Unparker {
-    fn unpark(&self) {
-        self.inner.unpark();
-    }
-}
+// ==== impl Inner ====
 
 impl Inner {
     /// Parks the current thread for at most `dur`.
     fn park(&self) {
-        for _ in 0..3 {
-            // If we were previously notified then we consume this notification and
-            // return quickly.
-            if self
-                .state
-                .compare_exchange(NOTIFIED, EMPTY, SeqCst, SeqCst)
-                .is_ok()
-            {
-                return;
-            }
-
-            thread::yield_now();
-        }
-
-        if let Some(mut driver) = self.shared.driver.try_lock() {
-            self.park_driver(&mut driver);
-        } else {
-            self.park_condvar();
+        // If we were previously notified then we consume this notification and
+        // return quickly.
+        if self
+            .state
+            .compare_exchange(NOTIFIED, EMPTY, SeqCst, SeqCst)
+            .is_ok()
+        {
+            return;
         }
-    }
 
-    fn park_condvar(&self) {
         // Otherwise we need to coordinate going to sleep
         let mut m = self.mutex.lock();
 
-        match self
-            .state
-            .compare_exchange(EMPTY, PARKED_CONDVAR, SeqCst, SeqCst)
-        {
+        match self.state.compare_exchange(EMPTY, PARKED, SeqCst, SeqCst) {
             Ok(_) => {}
             Err(NOTIFIED) => {
                 // We must read here, even though we know it will be `NOTIFIED`.
@@ -180,33 +129,44 @@ impl Inner {
         }
     }
 
-    fn park_driver(&self, driver: &mut Driver) {
-        match self
+    fn park_timeout(&self, dur: Duration) {
+        // Like `park` above we have a fast path for an already-notified thread,
+        // and afterwards we start coordinating for a sleep. Return quickly.
+        if self
             .state
-            .compare_exchange(EMPTY, PARKED_DRIVER, SeqCst, SeqCst)
+            .compare_exchange(NOTIFIED, EMPTY, SeqCst, SeqCst)
+            .is_ok()
         {
+            return;
+        }
+
+        if dur == Duration::from_millis(0) {
+            return;
+        }
+
+        let m = self.mutex.lock();
+
+        match self.state.compare_exchange(EMPTY, PARKED, SeqCst, SeqCst) {
             Ok(_) => {}
             Err(NOTIFIED) => {
-                // We must read here, even though we know it will be `NOTIFIED`.
-                // This is because `unpark` may have been called again since we read
-                // `NOTIFIED` in the `compare_exchange` above. We must perform an
-                // acquire operation that synchronizes with that `unpark` to observe
-                // any writes it made before the call to unpark. To do that we must
-                // read from the write it made to `state`.
+                // We must read again here, see `park`.
                 let old = self.state.swap(EMPTY, SeqCst);
                 debug_assert_eq!(old, NOTIFIED, "park state changed unexpectedly");
 
                 return;
             }
-            Err(actual) => panic!("inconsistent park state; actual = {}", actual),
+            Err(actual) => panic!("inconsistent park_timeout state; actual = {}", actual),
         }
 
-        // TODO: don't unwrap
-        driver.park().unwrap();
+        // Wait with a timeout, and if we spuriously wake up or otherwise wake up
+        // from a notification, we just want to unconditionally set the state back to
+        // empty, either consuming a notification or un-flagging ourselves as
+        // parked.
+        let (_m, _result) = self.condvar.wait_timeout(m, dur).unwrap();
 
         match self.state.swap(EMPTY, SeqCst) {
-            NOTIFIED => {}      // got a notification, hurray!
-            PARKED_DRIVER => {} // no notification, alas
+            NOTIFIED => {} // got a notification, hurray!
+            PARKED => {}   // no notification, alas
             n => panic!("inconsistent park_timeout state: {}", n),
         }
     }
@@ -218,15 +178,12 @@ impl Inner {
         // is already `NOTIFIED`. That is why this must be a swap rather than a
         // compare-and-swap that returns if it reads `NOTIFIED` on failure.
         match self.state.swap(NOTIFIED, SeqCst) {
-            EMPTY => {}    // no one was waiting
-            NOTIFIED => {} // already unparked
-            PARKED_CONDVAR => self.unpark_condvar(),
-            PARKED_DRIVER => self.unpark_driver(),
-            actual => panic!("inconsistent state in unpark; actual = {}", actual),
+            EMPTY => return,    // no one was waiting
+            NOTIFIED => return, // already unparked
+            PARKED => {}        // gotta go wake someone up
+            _ => panic!("inconsistent state in unpark"),
         }
-    }
 
-    fn unpark_condvar(&self) {
         // There is a period between when the parked thread sets `state` to
         // `PARKED` (or last checked `state` in the case of a spurious wake
         // up) and when it actually waits on `cvar`. If we were to notify
@@ -243,15 +200,149 @@ impl Inner {
         self.condvar.notify_one()
     }
 
-    fn unpark_driver(&self) {
-        self.shared.handle.unpark();
+    fn shutdown(&self) {
+        self.condvar.notify_all();
     }
+}
 
-    fn shutdown(&self) {
-        if let Some(mut driver) = self.shared.driver.try_lock() {
-            driver.shutdown();
+impl Default for ParkThread {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+// ===== impl UnparkThread =====
+
+impl UnparkThread {
+    pub(crate) fn unpark(&self) {
+        self.inner.unpark();
+    }
+}
+
+use crate::loom::thread::AccessError;
+use std::future::Future;
+use std::marker::PhantomData;
+use std::mem;
+use std::rc::Rc;
+use std::task::{RawWaker, RawWakerVTable, Waker};
+
+/// Blocks the current thread using a condition variable.
+#[derive(Debug)]
+pub(crate) struct CachedParkThread {
+    _anchor: PhantomData<Rc<()>>,
+}
+
+impl CachedParkThread {
+    /// Creates a new `ParkThread` handle for the current thread.
+    ///
+    /// This type cannot be moved to other threads, so it should be created on
+    /// the thread that the caller intends to park.
+    pub(crate) fn new() -> CachedParkThread {
+        CachedParkThread {
+            _anchor: PhantomData,
         }
+    }
 
-        self.condvar.notify_all();
+    pub(crate) fn waker(&self) -> Result<Waker, AccessError> {
+        self.unpark().map(|unpark| unpark.into_waker())
     }
+
+    fn unpark(&self) -> Result<UnparkThread, AccessError> {
+        self.with_current(|park_thread| park_thread.unpark())
+    }
+
+    pub(crate) fn park(&mut self) {
+        self.with_current(|park_thread| park_thread.inner.park())
+            .unwrap();
+    }
+
+    pub(crate) fn park_timeout(&mut self, duration: Duration) {
+        self.with_current(|park_thread| park_thread.inner.park_timeout(duration))
+            .unwrap();
+    }
+
+    /// Gets a reference to the `ParkThread` handle for this thread.
+    fn with_current<F, R>(&self, f: F) -> Result<R, AccessError>
+    where
+        F: FnOnce(&ParkThread) -> R,
+    {
+        CURRENT_PARKER.try_with(|inner| f(inner))
+    }
+
+    pub(crate) fn block_on<F: Future>(&mut self, f: F) -> Result<F::Output, AccessError> {
+        use std::task::Context;
+        use std::task::Poll::Ready;
+
+        // `get_unpark()` should not return a Result
+        let waker = self.waker()?;
+        let mut cx = Context::from_waker(&waker);
+
+        pin!(f);
+
+        loop {
+            if let Ready(v) = crate::runtime::coop::budget(|| f.as_mut().poll(&mut cx)) {
+                return Ok(v);
+            }
+
+            self.park();
+        }
+    }
+}
+
+impl UnparkThread {
+    pub(crate) fn into_waker(self) -> Waker {
+        unsafe {
+            let raw = unparker_to_raw_waker(self.inner);
+            Waker::from_raw(raw)
+        }
+    }
+}
+
+impl Inner {
+    #[allow(clippy::wrong_self_convention)]
+    fn into_raw(this: Arc<Inner>) -> *const () {
+        Arc::into_raw(this) as *const ()
+    }
+
+    unsafe fn from_raw(ptr: *const ()) -> Arc<Inner> {
+        Arc::from_raw(ptr as *const Inner)
+    }
+}
+
+unsafe fn unparker_to_raw_waker(unparker: Arc<Inner>) -> RawWaker {
+    RawWaker::new(
+        Inner::into_raw(unparker),
+        &RawWakerVTable::new(clone, wake, wake_by_ref, drop_waker),
+    )
+}
+
+unsafe fn clone(raw: *const ()) -> RawWaker {
+    let unparker = Inner::from_raw(raw);
+
+    // Increment the ref count
+    mem::forget(unparker.clone());
+
+    unparker_to_raw_waker(unparker)
+}
+
+unsafe fn drop_waker(raw: *const ()) {
+    let _ = Inner::from_raw(raw);
+}
+
+unsafe fn wake(raw: *const ()) {
+    let unparker = Inner::from_raw(raw);
+    unparker.unpark();
+}
+
+unsafe fn wake_by_ref(raw: *const ()) {
+    let unparker = Inner::from_raw(raw);
+    unparker.unpark();
+
+    // We don't actually own a reference to the unparker
+    mem::forget(unparker);
+}
+
+#[cfg(loom)]
+pub(crate) fn current_thread_park_count() -> usize {
+    CURRENT_THREAD_PARK_COUNT.with(|count| count.load(SeqCst))
 }
diff --git a/vendor/tokio/src/process/unix/driver.rs b/vendor/tokio/src/runtime/process.rs
index 43b2efa0a..df339b0e7 100644
--- a/vendor/tokio/src/process/unix/driver.rs
+++ b/vendor/tokio/src/runtime/process.rs
@@ -1,12 +1,11 @@
 #![cfg_attr(not(feature = "rt"), allow(dead_code))]
 
-//! Process driver
+//! Process driver.
 
-use crate::park::Park;
 use crate::process::unix::GlobalOrphanQueue;
-use crate::signal::unix::driver::{Driver as SignalDriver, Handle as SignalHandle};
+use crate::runtime::driver;
+use crate::runtime::signal::{Driver as SignalDriver, Handle as SignalHandle};
 
-use std::io;
 use std::time::Duration;
 
 /// Responsible for cleaning up orphaned child processes on Unix platforms.
@@ -28,31 +27,18 @@ impl Driver {
             signal_handle,
         }
     }
-}
-
-// ===== impl Park for Driver =====
-
-impl Park for Driver {
-    type Unpark = <SignalDriver as Park>::Unpark;
-    type Error = io::Error;
-
-    fn unpark(&self) -> Self::Unpark {
-        self.park.unpark()
-    }
 
-    fn park(&mut self) -> Result<(), Self::Error> {
-        self.park.park()?;
+    pub(crate) fn park(&mut self, handle: &driver::Handle) {
+        self.park.park(handle);
         GlobalOrphanQueue::reap_orphans(&self.signal_handle);
-        Ok(())
     }
 
-    fn park_timeout(&mut self, duration: Duration) -> Result<(), Self::Error> {
-        self.park.park_timeout(duration)?;
+    pub(crate) fn park_timeout(&mut self, handle: &driver::Handle, duration: Duration) {
+        self.park.park_timeout(handle, duration);
         GlobalOrphanQueue::reap_orphans(&self.signal_handle);
-        Ok(())
     }
 
-    fn shutdown(&mut self) {
-        self.park.shutdown()
+    pub(crate) fn shutdown(&mut self, handle: &driver::Handle) {
+        self.park.shutdown(handle)
     }
 }
diff --git a/vendor/tokio/src/runtime/runtime.rs b/vendor/tokio/src/runtime/runtime.rs
new file mode 100644
index 000000000..3f3499975
--- /dev/null
+++ b/vendor/tokio/src/runtime/runtime.rs
@@ -0,0 +1,445 @@
+use crate::runtime::blocking::BlockingPool;
+use crate::runtime::scheduler::CurrentThread;
+use crate::runtime::{context, EnterGuard, Handle};
+use crate::task::JoinHandle;
+
+use std::future::Future;
+use std::time::Duration;
+
+cfg_rt_multi_thread! {
+    use crate::runtime::Builder;
+    use crate::runtime::scheduler::MultiThread;
+}
+
+/// The Tokio runtime.
+///
+/// The runtime provides an I/O driver, task scheduler, [timer], and
+/// blocking pool, necessary for running asynchronous tasks.
+///
+/// Instances of `Runtime` can be created using [`new`], or [`Builder`].
+/// However, most users will use the `#[tokio::main]` annotation on their
+/// entry point instead.
+///
+/// See [module level][mod] documentation for more details.
+///
+/// # Shutdown
+///
+/// Shutting down the runtime is done by dropping the value, or calling
+/// [`Runtime::shutdown_background`] or [`Runtime::shutdown_timeout`].
+///
+/// Tasks spawned through [`Runtime::spawn`] keep running until they yield.
+/// Then they are dropped. They are not *guaranteed* to run to completion, but
+/// *might* do so if they do not yield until completion.
+///
+/// Blocking functions spawned through [`Runtime::spawn_blocking`] keep running
+/// until they return.
+///
+/// The thread initiating the shutdown blocks until all spawned work has been
+/// stopped. This can take an indefinite amount of time. The `Drop`
+/// implementation waits forever for this.
+///
+/// `shutdown_background` and `shutdown_timeout` can be used if waiting forever
+/// is undesired. When the timeout is reached, spawned work that did not stop
+/// in time and threads running it are leaked. The work continues to run until
+/// one of the stopping conditions is fulfilled, but the thread initiating the
+/// shutdown is unblocked.
+///
+/// Once the runtime has been dropped, any outstanding I/O resources bound to
+/// it will no longer function. Calling any method on them will result in an
+/// error.
+///
+/// # Sharing
+///
+/// The Tokio runtime implements `Sync` and `Send` to allow you to wrap it
+/// in a `Arc`. Most fn take `&self` to allow you to call them concurrently
+/// across multiple threads.
+///
+/// Calls to `shutdown` and `shutdown_timeout` require exclusive ownership of
+/// the runtime type and this can be achieved via `Arc::try_unwrap` when only
+/// one strong count reference is left over.
+///
+/// [timer]: crate::time
+/// [mod]: index.html
+/// [`new`]: method@Self::new
+/// [`Builder`]: struct@Builder
+#[derive(Debug)]
+pub struct Runtime {
+    /// Task scheduler
+    scheduler: Scheduler,
+
+    /// Handle to runtime, also contains driver handles
+    handle: Handle,
+
+    /// Blocking pool handle, used to signal shutdown
+    blocking_pool: BlockingPool,
+}
+
+/// The flavor of a `Runtime`.
+///
+/// This is the return type for [`Handle::runtime_flavor`](crate::runtime::Handle::runtime_flavor()).
+#[derive(Debug, PartialEq, Eq)]
+#[non_exhaustive]
+pub enum RuntimeFlavor {
+    /// The flavor that executes all tasks on the current thread.
+    CurrentThread,
+    /// The flavor that executes tasks across multiple threads.
+    MultiThread,
+}
+
+/// The runtime scheduler is either a multi-thread or a current-thread executor.
+#[derive(Debug)]
+pub(super) enum Scheduler {
+    /// Execute all tasks on the current-thread.
+    CurrentThread(CurrentThread),
+
+    /// Execute tasks across multiple threads.
+    #[cfg(all(feature = "rt-multi-thread", not(tokio_wasi)))]
+    MultiThread(MultiThread),
+}
+
+impl Runtime {
+    pub(super) fn from_parts(
+        scheduler: Scheduler,
+        handle: Handle,
+        blocking_pool: BlockingPool,
+    ) -> Runtime {
+        Runtime {
+            scheduler,
+            handle,
+            blocking_pool,
+        }
+    }
+
+    cfg_not_wasi! {
+        /// Creates a new runtime instance with default configuration values.
+        ///
+        /// This results in the multi threaded scheduler, I/O driver, and time driver being
+        /// initialized.
+        ///
+        /// Most applications will not need to call this function directly. Instead,
+        /// they will use the  [`#[tokio::main]` attribute][main]. When a more complex
+        /// configuration is necessary, the [runtime builder] may be used.
+        ///
+        /// See [module level][mod] documentation for more details.
+        ///
+        /// # Examples
+        ///
+        /// Creating a new `Runtime` with default configuration values.
+        ///
+        /// ```
+        /// use tokio::runtime::Runtime;
+        ///
+        /// let rt = Runtime::new()
+        ///     .unwrap();
+        ///
+        /// // Use the runtime...
+        /// ```
+        ///
+        /// [mod]: index.html
+        /// [main]: ../attr.main.html
+        /// [threaded scheduler]: index.html#threaded-scheduler
+        /// [runtime builder]: crate::runtime::Builder
+        #[cfg(feature = "rt-multi-thread")]
+        #[cfg_attr(docsrs, doc(cfg(feature = "rt-multi-thread")))]
+        pub fn new() -> std::io::Result<Runtime> {
+            Builder::new_multi_thread().enable_all().build()
+        }
+    }
+
+    /// Returns a handle to the runtime's spawner.
+    ///
+    /// The returned handle can be used to spawn tasks that run on this runtime, and can
+    /// be cloned to allow moving the `Handle` to other threads.
+    ///
+    /// Calling [`Handle::block_on`] on a handle to a `current_thread` runtime is error-prone.
+    /// Refer to the documentation of [`Handle::block_on`] for more.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::runtime::Runtime;
+    ///
+    /// let rt = Runtime::new()
+    ///     .unwrap();
+    ///
+    /// let handle = rt.handle();
+    ///
+    /// // Use the handle...
+    /// ```
+    pub fn handle(&self) -> &Handle {
+        &self.handle
+    }
+
+    /// Spawns a future onto the Tokio runtime.
+    ///
+    /// This spawns the given future onto the runtime's executor, usually a
+    /// thread pool. The thread pool is then responsible for polling the future
+    /// until it completes.
+    ///
+    /// The provided future will start running in the background immediately
+    /// when `spawn` is called, even if you don't await the returned
+    /// `JoinHandle`.
+    ///
+    /// See [module level][mod] documentation for more details.
+    ///
+    /// [mod]: index.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::runtime::Runtime;
+    ///
+    /// # fn dox() {
+    /// // Create the runtime
+    /// let rt = Runtime::new().unwrap();
+    ///
+    /// // Spawn a future onto the runtime
+    /// rt.spawn(async {
+    ///     println!("now running on a worker thread");
+    /// });
+    /// # }
+    /// ```
+    #[track_caller]
+    pub fn spawn<F>(&self, future: F) -> JoinHandle<F::Output>
+    where
+        F: Future + Send + 'static,
+        F::Output: Send + 'static,
+    {
+        self.handle.spawn(future)
+    }
+
+    /// Runs the provided function on an executor dedicated to blocking operations.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::runtime::Runtime;
+    ///
+    /// # fn dox() {
+    /// // Create the runtime
+    /// let rt = Runtime::new().unwrap();
+    ///
+    /// // Spawn a blocking function onto the runtime
+    /// rt.spawn_blocking(|| {
+    ///     println!("now running on a worker thread");
+    /// });
+    /// # }
+    #[track_caller]
+    pub fn spawn_blocking<F, R>(&self, func: F) -> JoinHandle<R>
+    where
+        F: FnOnce() -> R + Send + 'static,
+        R: Send + 'static,
+    {
+        self.handle.spawn_blocking(func)
+    }
+
+    /// Runs a future to completion on the Tokio runtime. This is the
+    /// runtime's entry point.
+    ///
+    /// This runs the given future on the current thread, blocking until it is
+    /// complete, and yielding its resolved result. Any tasks or timers
+    /// which the future spawns internally will be executed on the runtime.
+    ///
+    /// # Non-worker future
+    ///
+    /// Note that the future required by this function does not run as a
+    /// worker. The expectation is that other tasks are spawned by the future here.
+    /// Awaiting on other futures from the future provided here will not
+    /// perform as fast as those spawned as workers.
+    ///
+    /// # Multi thread scheduler
+    ///
+    /// When the multi thread scheduler is used this will allow futures
+    /// to run within the io driver and timer context of the overall runtime.
+    ///
+    /// Any spawned tasks will continue running after `block_on` returns.
+    ///
+    /// # Current thread scheduler
+    ///
+    /// When the current thread scheduler is enabled `block_on`
+    /// can be called concurrently from multiple threads. The first call
+    /// will take ownership of the io and timer drivers. This means
+    /// other threads which do not own the drivers will hook into that one.
+    /// When the first `block_on` completes, other threads will be able to
+    /// "steal" the driver to allow continued execution of their futures.
+    ///
+    /// Any spawned tasks will be suspended after `block_on` returns. Calling
+    /// `block_on` again will resume previously spawned tasks.
+    ///
+    /// # Panics
+    ///
+    /// This function panics if the provided future panics, or if called within an
+    /// asynchronous execution context.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::runtime::Runtime;
+    ///
+    /// // Create the runtime
+    /// let rt  = Runtime::new().unwrap();
+    ///
+    /// // Execute the future, blocking the current thread until completion
+    /// rt.block_on(async {
+    ///     println!("hello");
+    /// });
+    /// ```
+    ///
+    /// [handle]: fn@Handle::block_on
+    #[track_caller]
+    pub fn block_on<F: Future>(&self, future: F) -> F::Output {
+        #[cfg(all(
+            tokio_unstable,
+            tokio_taskdump,
+            feature = "rt",
+            target_os = "linux",
+            any(target_arch = "aarch64", target_arch = "x86", target_arch = "x86_64")
+        ))]
+        let future = super::task::trace::Trace::root(future);
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let future = crate::util::trace::task(
+            future,
+            "block_on",
+            None,
+            crate::runtime::task::Id::next().as_u64(),
+        );
+
+        let _enter = self.enter();
+
+        match &self.scheduler {
+            Scheduler::CurrentThread(exec) => exec.block_on(&self.handle.inner, future),
+            #[cfg(all(feature = "rt-multi-thread", not(tokio_wasi)))]
+            Scheduler::MultiThread(exec) => exec.block_on(&self.handle.inner, future),
+        }
+    }
+
+    /// Enters the runtime context.
+    ///
+    /// This allows you to construct types that must have an executor
+    /// available on creation such as [`Sleep`] or [`TcpStream`]. It will
+    /// also allow you to call methods such as [`tokio::spawn`].
+    ///
+    /// [`Sleep`]: struct@crate::time::Sleep
+    /// [`TcpStream`]: struct@crate::net::TcpStream
+    /// [`tokio::spawn`]: fn@crate::spawn
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use tokio::runtime::Runtime;
+    ///
+    /// fn function_that_spawns(msg: String) {
+    ///     // Had we not used `rt.enter` below, this would panic.
+    ///     tokio::spawn(async move {
+    ///         println!("{}", msg);
+    ///     });
+    /// }
+    ///
+    /// fn main() {
+    ///     let rt = Runtime::new().unwrap();
+    ///
+    ///     let s = "Hello World!".to_string();
+    ///
+    ///     // By entering the context, we tie `tokio::spawn` to this executor.
+    ///     let _guard = rt.enter();
+    ///     function_that_spawns(s);
+    /// }
+    /// ```
+    pub fn enter(&self) -> EnterGuard<'_> {
+        self.handle.enter()
+    }
+
+    /// Shuts down the runtime, waiting for at most `duration` for all spawned
+    /// work to stop.
+    ///
+    /// See the [struct level documentation](Runtime#shutdown) for more details.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::runtime::Runtime;
+    /// use tokio::task;
+    ///
+    /// use std::thread;
+    /// use std::time::Duration;
+    ///
+    /// fn main() {
+    ///    let runtime = Runtime::new().unwrap();
+    ///
+    ///    runtime.block_on(async move {
+    ///        task::spawn_blocking(move || {
+    ///            thread::sleep(Duration::from_secs(10_000));
+    ///        });
+    ///    });
+    ///
+    ///    runtime.shutdown_timeout(Duration::from_millis(100));
+    /// }
+    /// ```
+    pub fn shutdown_timeout(mut self, duration: Duration) {
+        // Wakeup and shutdown all the worker threads
+        self.handle.inner.shutdown();
+        self.blocking_pool.shutdown(Some(duration));
+    }
+
+    /// Shuts down the runtime, without waiting for any spawned work to stop.
+    ///
+    /// This can be useful if you want to drop a runtime from within another runtime.
+    /// Normally, dropping a runtime will block indefinitely for spawned blocking tasks
+    /// to complete, which would normally not be permitted within an asynchronous context.
+    /// By calling `shutdown_background()`, you can drop the runtime from such a context.
+    ///
+    /// Note however, that because we do not wait for any blocking tasks to complete, this
+    /// may result in a resource leak (in that any blocking tasks are still running until they
+    /// return.
+    ///
+    /// See the [struct level documentation](Runtime#shutdown) for more details.
+    ///
+    /// This function is equivalent to calling `shutdown_timeout(Duration::from_nanos(0))`.
+    ///
+    /// ```
+    /// use tokio::runtime::Runtime;
+    ///
+    /// fn main() {
+    ///    let runtime = Runtime::new().unwrap();
+    ///
+    ///    runtime.block_on(async move {
+    ///        let inner_runtime = Runtime::new().unwrap();
+    ///        // ...
+    ///        inner_runtime.shutdown_background();
+    ///    });
+    /// }
+    /// ```
+    pub fn shutdown_background(self) {
+        self.shutdown_timeout(Duration::from_nanos(0))
+    }
+}
+
+#[allow(clippy::single_match)] // there are comments in the error branch, so we don't want if-let
+impl Drop for Runtime {
+    fn drop(&mut self) {
+        match &mut self.scheduler {
+            Scheduler::CurrentThread(current_thread) => {
+                // This ensures that tasks spawned on the current-thread
+                // runtime are dropped inside the runtime's context.
+                let _guard = context::try_set_current(&self.handle.inner);
+                current_thread.shutdown(&self.handle.inner);
+            }
+            #[cfg(all(feature = "rt-multi-thread", not(tokio_wasi)))]
+            Scheduler::MultiThread(multi_thread) => {
+                // The threaded scheduler drops its tasks on its worker threads, which is
+                // already in the runtime's context.
+                multi_thread.shutdown(&self.handle.inner);
+            }
+        }
+    }
+}
+
+cfg_metrics! {
+    impl Runtime {
+        /// TODO
+        pub fn metrics(&self) -> crate::runtime::RuntimeMetrics {
+            self.handle.metrics()
+        }
+    }
+}
diff --git a/vendor/tokio/src/runtime/scheduler/current_thread.rs b/vendor/tokio/src/runtime/scheduler/current_thread.rs
new file mode 100644
index 000000000..ac4a8d6fa
--- /dev/null
+++ b/vendor/tokio/src/runtime/scheduler/current_thread.rs
@@ -0,0 +1,750 @@
+use crate::future::poll_fn;
+use crate::loom::sync::atomic::AtomicBool;
+use crate::loom::sync::Arc;
+use crate::runtime::driver::{self, Driver};
+use crate::runtime::scheduler::{self, Defer, Inject};
+use crate::runtime::task::{self, JoinHandle, OwnedTasks, Schedule, Task};
+use crate::runtime::{blocking, context, Config, MetricsBatch, SchedulerMetrics, WorkerMetrics};
+use crate::sync::notify::Notify;
+use crate::util::atomic_cell::AtomicCell;
+use crate::util::{waker_ref, RngSeedGenerator, Wake, WakerRef};
+
+use std::cell::RefCell;
+use std::collections::VecDeque;
+use std::fmt;
+use std::future::Future;
+use std::sync::atomic::Ordering::{AcqRel, Release};
+use std::task::Poll::{Pending, Ready};
+use std::task::Waker;
+use std::time::Duration;
+
+/// Executes tasks on the current thread
+pub(crate) struct CurrentThread {
+    /// Core scheduler data is acquired by a thread entering `block_on`.
+    core: AtomicCell<Core>,
+
+    /// Notifier for waking up other threads to steal the
+    /// driver.
+    notify: Notify,
+}
+
+/// Handle to the current thread scheduler
+pub(crate) struct Handle {
+    /// Scheduler state shared across threads
+    shared: Shared,
+
+    /// Resource driver handles
+    pub(crate) driver: driver::Handle,
+
+    /// Blocking pool spawner
+    pub(crate) blocking_spawner: blocking::Spawner,
+
+    /// Current random number generator seed
+    pub(crate) seed_generator: RngSeedGenerator,
+}
+
+/// Data required for executing the scheduler. The struct is passed around to
+/// a function that will perform the scheduling work and acts as a capability token.
+struct Core {
+    /// Scheduler run queue
+    tasks: VecDeque<Notified>,
+
+    /// Current tick
+    tick: u32,
+
+    /// Runtime driver
+    ///
+    /// The driver is removed before starting to park the thread
+    driver: Option<Driver>,
+
+    /// Metrics batch
+    metrics: MetricsBatch,
+
+    /// How often to check the global queue
+    global_queue_interval: u32,
+
+    /// True if a task panicked without being handled and the runtime is
+    /// configured to shutdown on unhandled panic.
+    unhandled_panic: bool,
+}
+
+/// Scheduler state shared between threads.
+struct Shared {
+    /// Remote run queue
+    inject: Inject<Arc<Handle>>,
+
+    /// Collection of all active tasks spawned onto this executor.
+    owned: OwnedTasks<Arc<Handle>>,
+
+    /// Indicates whether the blocked on thread was woken.
+    woken: AtomicBool,
+
+    /// Scheduler configuration options
+    config: Config,
+
+    /// Keeps track of various runtime metrics.
+    scheduler_metrics: SchedulerMetrics,
+
+    /// This scheduler only has one worker.
+    worker_metrics: WorkerMetrics,
+}
+
+/// Thread-local context.
+///
+/// pub(crate) to store in `runtime::context`.
+pub(crate) struct Context {
+    /// Scheduler handle
+    handle: Arc<Handle>,
+
+    /// Scheduler core, enabling the holder of `Context` to execute the
+    /// scheduler.
+    core: RefCell<Option<Box<Core>>>,
+
+    /// Deferred tasks, usually ones that called `task::yield_now()`.
+    pub(crate) defer: Defer,
+}
+
+type Notified = task::Notified<Arc<Handle>>;
+
+/// Initial queue capacity.
+const INITIAL_CAPACITY: usize = 64;
+
+/// Used if none is specified. This is a temporary constant and will be removed
+/// as we unify tuning logic between the multi-thread and current-thread
+/// schedulers.
+const DEFAULT_GLOBAL_QUEUE_INTERVAL: u32 = 31;
+
+impl CurrentThread {
+    pub(crate) fn new(
+        driver: Driver,
+        driver_handle: driver::Handle,
+        blocking_spawner: blocking::Spawner,
+        seed_generator: RngSeedGenerator,
+        config: Config,
+    ) -> (CurrentThread, Arc<Handle>) {
+        let worker_metrics = WorkerMetrics::from_config(&config);
+
+        // Get the configured global queue interval, or use the default.
+        let global_queue_interval = config
+            .global_queue_interval
+            .unwrap_or(DEFAULT_GLOBAL_QUEUE_INTERVAL);
+
+        let handle = Arc::new(Handle {
+            shared: Shared {
+                inject: Inject::new(),
+                owned: OwnedTasks::new(),
+                woken: AtomicBool::new(false),
+                config,
+                scheduler_metrics: SchedulerMetrics::new(),
+                worker_metrics,
+            },
+            driver: driver_handle,
+            blocking_spawner,
+            seed_generator,
+        });
+
+        let core = AtomicCell::new(Some(Box::new(Core {
+            tasks: VecDeque::with_capacity(INITIAL_CAPACITY),
+            tick: 0,
+            driver: Some(driver),
+            metrics: MetricsBatch::new(&handle.shared.worker_metrics),
+            global_queue_interval,
+            unhandled_panic: false,
+        })));
+
+        let scheduler = CurrentThread {
+            core,
+            notify: Notify::new(),
+        };
+
+        (scheduler, handle)
+    }
+
+    #[track_caller]
+    pub(crate) fn block_on<F: Future>(&self, handle: &scheduler::Handle, future: F) -> F::Output {
+        pin!(future);
+
+        crate::runtime::context::enter_runtime(handle, false, |blocking| {
+            let handle = handle.as_current_thread();
+
+            // Attempt to steal the scheduler core and block_on the future if we can
+            // there, otherwise, lets select on a notification that the core is
+            // available or the future is complete.
+            loop {
+                if let Some(core) = self.take_core(handle) {
+                    return core.block_on(future);
+                } else {
+                    let notified = self.notify.notified();
+                    pin!(notified);
+
+                    if let Some(out) = blocking
+                        .block_on(poll_fn(|cx| {
+                            if notified.as_mut().poll(cx).is_ready() {
+                                return Ready(None);
+                            }
+
+                            if let Ready(out) = future.as_mut().poll(cx) {
+                                return Ready(Some(out));
+                            }
+
+                            Pending
+                        }))
+                        .expect("Failed to `Enter::block_on`")
+                    {
+                        return out;
+                    }
+                }
+            }
+        })
+    }
+
+    fn take_core(&self, handle: &Arc<Handle>) -> Option<CoreGuard<'_>> {
+        let core = self.core.take()?;
+
+        Some(CoreGuard {
+            context: scheduler::Context::CurrentThread(Context {
+                handle: handle.clone(),
+                core: RefCell::new(Some(core)),
+                defer: Defer::new(),
+            }),
+            scheduler: self,
+        })
+    }
+
+    pub(crate) fn shutdown(&mut self, handle: &scheduler::Handle) {
+        let handle = handle.as_current_thread();
+
+        // Avoid a double panic if we are currently panicking and
+        // the lock may be poisoned.
+
+        let core = match self.take_core(handle) {
+            Some(core) => core,
+            None if std::thread::panicking() => return,
+            None => panic!("Oh no! We never placed the Core back, this is a bug!"),
+        };
+
+        // Check that the thread-local is not being destroyed
+        let tls_available = context::with_current(|_| ()).is_ok();
+
+        if tls_available {
+            core.enter(|core, _context| {
+                let core = shutdown2(core, handle);
+                (core, ())
+            });
+        } else {
+            // Shutdown without setting the context. `tokio::spawn` calls will
+            // fail, but those will fail either way because the thread-local is
+            // not available anymore.
+            let context = core.context.expect_current_thread();
+            let core = context.core.borrow_mut().take().unwrap();
+
+            let core = shutdown2(core, handle);
+            *context.core.borrow_mut() = Some(core);
+        }
+    }
+}
+
+fn shutdown2(mut core: Box<Core>, handle: &Handle) -> Box<Core> {
+    // Drain the OwnedTasks collection. This call also closes the
+    // collection, ensuring that no tasks are ever pushed after this
+    // call returns.
+    handle.shared.owned.close_and_shutdown_all();
+
+    // Drain local queue
+    // We already shut down every task, so we just need to drop the task.
+    while let Some(task) = core.next_local_task(handle) {
+        drop(task);
+    }
+
+    // Close the injection queue
+    handle.shared.inject.close();
+
+    // Drain remote queue
+    while let Some(task) = handle.shared.inject.pop() {
+        drop(task);
+    }
+
+    assert!(handle.shared.owned.is_empty());
+
+    // Submit metrics
+    core.submit_metrics(handle);
+
+    // Shutdown the resource drivers
+    if let Some(driver) = core.driver.as_mut() {
+        driver.shutdown(&handle.driver);
+    }
+
+    core
+}
+
+impl fmt::Debug for CurrentThread {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt.debug_struct("CurrentThread").finish()
+    }
+}
+
+// ===== impl Core =====
+
+impl Core {
+    /// Get and increment the current tick
+    fn tick(&mut self) {
+        self.tick = self.tick.wrapping_add(1);
+    }
+
+    fn next_task(&mut self, handle: &Handle) -> Option<Notified> {
+        if self.tick % self.global_queue_interval == 0 {
+            handle
+                .next_remote_task()
+                .or_else(|| self.next_local_task(handle))
+        } else {
+            self.next_local_task(handle)
+                .or_else(|| handle.next_remote_task())
+        }
+    }
+
+    fn next_local_task(&mut self, handle: &Handle) -> Option<Notified> {
+        let ret = self.tasks.pop_front();
+        handle
+            .shared
+            .worker_metrics
+            .set_queue_depth(self.tasks.len());
+        ret
+    }
+
+    fn push_task(&mut self, handle: &Handle, task: Notified) {
+        self.tasks.push_back(task);
+        self.metrics.inc_local_schedule_count();
+        handle
+            .shared
+            .worker_metrics
+            .set_queue_depth(self.tasks.len());
+    }
+
+    fn submit_metrics(&mut self, handle: &Handle) {
+        self.metrics.submit(&handle.shared.worker_metrics);
+    }
+}
+
+#[cfg(tokio_taskdump)]
+fn wake_deferred_tasks_and_free(context: &Context) {
+    let wakers = context.defer.take_deferred();
+    for waker in wakers {
+        waker.wake();
+    }
+}
+
+// ===== impl Context =====
+
+impl Context {
+    /// Execute the closure with the given scheduler core stored in the
+    /// thread-local context.
+    fn run_task<R>(&self, mut core: Box<Core>, f: impl FnOnce() -> R) -> (Box<Core>, R) {
+        core.metrics.start_poll();
+        let mut ret = self.enter(core, || crate::runtime::coop::budget(f));
+        ret.0.metrics.end_poll();
+        ret
+    }
+
+    /// Blocks the current thread until an event is received by the driver,
+    /// including I/O events, timer events, ...
+    fn park(&self, mut core: Box<Core>, handle: &Handle) -> Box<Core> {
+        let mut driver = core.driver.take().expect("driver missing");
+
+        if let Some(f) = &handle.shared.config.before_park {
+            // Incorrect lint, the closures are actually different types so `f`
+            // cannot be passed as an argument to `enter`.
+            #[allow(clippy::redundant_closure)]
+            let (c, _) = self.enter(core, || f());
+            core = c;
+        }
+
+        // This check will fail if `before_park` spawns a task for us to run
+        // instead of parking the thread
+        if core.tasks.is_empty() {
+            // Park until the thread is signaled
+            core.metrics.about_to_park();
+            core.submit_metrics(handle);
+
+            let (c, _) = self.enter(core, || {
+                driver.park(&handle.driver);
+                self.defer.wake();
+            });
+
+            core = c;
+        }
+
+        if let Some(f) = &handle.shared.config.after_unpark {
+            // Incorrect lint, the closures are actually different types so `f`
+            // cannot be passed as an argument to `enter`.
+            #[allow(clippy::redundant_closure)]
+            let (c, _) = self.enter(core, || f());
+            core = c;
+        }
+
+        core.driver = Some(driver);
+        core
+    }
+
+    /// Checks the driver for new events without blocking the thread.
+    fn park_yield(&self, mut core: Box<Core>, handle: &Handle) -> Box<Core> {
+        let mut driver = core.driver.take().expect("driver missing");
+
+        core.submit_metrics(handle);
+
+        let (mut core, _) = self.enter(core, || {
+            driver.park_timeout(&handle.driver, Duration::from_millis(0));
+            self.defer.wake();
+        });
+
+        core.driver = Some(driver);
+        core
+    }
+
+    fn enter<R>(&self, core: Box<Core>, f: impl FnOnce() -> R) -> (Box<Core>, R) {
+        // Store the scheduler core in the thread-local context
+        //
+        // A drop-guard is employed at a higher level.
+        *self.core.borrow_mut() = Some(core);
+
+        // Execute the closure while tracking the execution budget
+        let ret = f();
+
+        // Take the scheduler core back
+        let core = self.core.borrow_mut().take().expect("core missing");
+        (core, ret)
+    }
+
+    pub(crate) fn defer(&self, waker: &Waker) {
+        self.defer.defer(waker);
+    }
+}
+
+// ===== impl Handle =====
+
+impl Handle {
+    /// Spawns a future onto the `CurrentThread` scheduler
+    pub(crate) fn spawn<F>(
+        me: &Arc<Self>,
+        future: F,
+        id: crate::runtime::task::Id,
+    ) -> JoinHandle<F::Output>
+    where
+        F: crate::future::Future + Send + 'static,
+        F::Output: Send + 'static,
+    {
+        let (handle, notified) = me.shared.owned.bind(future, me.clone(), id);
+
+        if let Some(notified) = notified {
+            me.schedule(notified);
+        }
+
+        handle
+    }
+
+    /// Capture a snapshot of this runtime's state.
+    #[cfg(all(
+        tokio_unstable,
+        tokio_taskdump,
+        target_os = "linux",
+        any(target_arch = "aarch64", target_arch = "x86", target_arch = "x86_64")
+    ))]
+    pub(crate) fn dump(&self) -> crate::runtime::Dump {
+        use crate::runtime::dump;
+        use task::trace::trace_current_thread;
+
+        let mut traces = vec![];
+
+        // todo: how to make this work outside of a runtime context?
+        context::with_scheduler(|maybe_context| {
+            // drain the local queue
+            let context = if let Some(context) = maybe_context {
+                context.expect_current_thread()
+            } else {
+                return;
+            };
+            let mut maybe_core = context.core.borrow_mut();
+            let core = if let Some(core) = maybe_core.as_mut() {
+                core
+            } else {
+                return;
+            };
+            let local = &mut core.tasks;
+
+            if self.shared.inject.is_closed() {
+                return;
+            }
+
+            traces = trace_current_thread(&self.shared.owned, local, &self.shared.inject)
+                .into_iter()
+                .map(dump::Task::new)
+                .collect();
+
+            // Avoid double borrow panic
+            drop(maybe_core);
+
+            // Taking a taskdump could wakes every task, but we probably don't want
+            // the `yield_now` vector to be that large under normal circumstances.
+            // Therefore, we free its allocation.
+            wake_deferred_tasks_and_free(context);
+        });
+
+        dump::Dump::new(traces)
+    }
+
+    fn next_remote_task(&self) -> Option<Notified> {
+        self.shared.inject.pop()
+    }
+
+    fn waker_ref(me: &Arc<Self>) -> WakerRef<'_> {
+        // Set woken to true when enter block_on, ensure outer future
+        // be polled for the first time when enter loop
+        me.shared.woken.store(true, Release);
+        waker_ref(me)
+    }
+
+    // reset woken to false and return original value
+    pub(crate) fn reset_woken(&self) -> bool {
+        self.shared.woken.swap(false, AcqRel)
+    }
+}
+
+cfg_metrics! {
+    impl Handle {
+        pub(crate) fn scheduler_metrics(&self) -> &SchedulerMetrics {
+            &self.shared.scheduler_metrics
+        }
+
+        pub(crate) fn injection_queue_depth(&self) -> usize {
+            self.shared.inject.len()
+        }
+
+        pub(crate) fn worker_metrics(&self, worker: usize) -> &WorkerMetrics {
+            assert_eq!(0, worker);
+            &self.shared.worker_metrics
+        }
+
+        pub(crate) fn num_blocking_threads(&self) -> usize {
+            self.blocking_spawner.num_threads()
+        }
+
+        pub(crate) fn num_idle_blocking_threads(&self) -> usize {
+            self.blocking_spawner.num_idle_threads()
+        }
+
+        pub(crate) fn blocking_queue_depth(&self) -> usize {
+            self.blocking_spawner.queue_depth()
+        }
+
+        pub(crate) fn active_tasks_count(&self) -> usize {
+            self.shared.owned.active_tasks_count()
+        }
+    }
+}
+
+impl fmt::Debug for Handle {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt.debug_struct("current_thread::Handle { ... }").finish()
+    }
+}
+
+// ===== impl Shared =====
+
+impl Schedule for Arc<Handle> {
+    fn release(&self, task: &Task<Self>) -> Option<Task<Self>> {
+        self.shared.owned.remove(task)
+    }
+
+    fn schedule(&self, task: task::Notified<Self>) {
+        use scheduler::Context::CurrentThread;
+
+        context::with_scheduler(|maybe_cx| match maybe_cx {
+            Some(CurrentThread(cx)) if Arc::ptr_eq(self, &cx.handle) => {
+                let mut core = cx.core.borrow_mut();
+
+                // If `None`, the runtime is shutting down, so there is no need
+                // to schedule the task.
+                if let Some(core) = core.as_mut() {
+                    core.push_task(self, task);
+                }
+            }
+            _ => {
+                // Track that a task was scheduled from **outside** of the runtime.
+                self.shared.scheduler_metrics.inc_remote_schedule_count();
+
+                // Schedule the task
+                self.shared.inject.push(task);
+                self.driver.unpark();
+            }
+        });
+    }
+
+    cfg_unstable! {
+        fn unhandled_panic(&self) {
+            use crate::runtime::UnhandledPanic;
+
+            match self.shared.config.unhandled_panic {
+                UnhandledPanic::Ignore => {
+                    // Do nothing
+                }
+                UnhandledPanic::ShutdownRuntime => {
+                    use scheduler::Context::CurrentThread;
+
+                    // This hook is only called from within the runtime, so
+                    // `context::with_scheduler` should match with `&self`, i.e.
+                    // there is no opportunity for a nested scheduler to be
+                    // called.
+                    context::with_scheduler(|maybe_cx| match maybe_cx {
+                        Some(CurrentThread(cx)) if Arc::ptr_eq(self, &cx.handle) => {
+                            let mut core = cx.core.borrow_mut();
+
+                            // If `None`, the runtime is shutting down, so there is no need to signal shutdown
+                            if let Some(core) = core.as_mut() {
+                                core.unhandled_panic = true;
+                                self.shared.owned.close_and_shutdown_all();
+                            }
+                        }
+                        _ => unreachable!("runtime core not set in CURRENT thread-local"),
+                    })
+                }
+            }
+        }
+    }
+}
+
+impl Wake for Handle {
+    fn wake(arc_self: Arc<Self>) {
+        Wake::wake_by_ref(&arc_self)
+    }
+
+    /// Wake by reference
+    fn wake_by_ref(arc_self: &Arc<Self>) {
+        arc_self.shared.woken.store(true, Release);
+        arc_self.driver.unpark();
+    }
+}
+
+// ===== CoreGuard =====
+
+/// Used to ensure we always place the `Core` value back into its slot in
+/// `CurrentThread`, even if the future panics.
+struct CoreGuard<'a> {
+    context: scheduler::Context,
+    scheduler: &'a CurrentThread,
+}
+
+impl CoreGuard<'_> {
+    #[track_caller]
+    fn block_on<F: Future>(self, future: F) -> F::Output {
+        let ret = self.enter(|mut core, context| {
+            let waker = Handle::waker_ref(&context.handle);
+            let mut cx = std::task::Context::from_waker(&waker);
+
+            pin!(future);
+
+            core.metrics.start_processing_scheduled_tasks();
+
+            'outer: loop {
+                let handle = &context.handle;
+
+                if handle.reset_woken() {
+                    let (c, res) = context.enter(core, || {
+                        crate::runtime::coop::budget(|| future.as_mut().poll(&mut cx))
+                    });
+
+                    core = c;
+
+                    if let Ready(v) = res {
+                        return (core, Some(v));
+                    }
+                }
+
+                for _ in 0..handle.shared.config.event_interval {
+                    // Make sure we didn't hit an unhandled_panic
+                    if core.unhandled_panic {
+                        return (core, None);
+                    }
+
+                    core.tick();
+
+                    let entry = core.next_task(handle);
+
+                    let task = match entry {
+                        Some(entry) => entry,
+                        None => {
+                            core.metrics.end_processing_scheduled_tasks();
+
+                            core = if !context.defer.is_empty() {
+                                context.park_yield(core, handle)
+                            } else {
+                                context.park(core, handle)
+                            };
+
+                            core.metrics.start_processing_scheduled_tasks();
+
+                            // Try polling the `block_on` future next
+                            continue 'outer;
+                        }
+                    };
+
+                    let task = context.handle.shared.owned.assert_owner(task);
+
+                    let (c, _) = context.run_task(core, || {
+                        task.run();
+                    });
+
+                    core = c;
+                }
+
+                core.metrics.end_processing_scheduled_tasks();
+
+                // Yield to the driver, this drives the timer and pulls any
+                // pending I/O events.
+                core = context.park_yield(core, handle);
+
+                core.metrics.start_processing_scheduled_tasks();
+            }
+        });
+
+        match ret {
+            Some(ret) => ret,
+            None => {
+                // `block_on` panicked.
+                panic!("a spawned task panicked and the runtime is configured to shut down on unhandled panic");
+            }
+        }
+    }
+
+    /// Enters the scheduler context. This sets the queue and other necessary
+    /// scheduler state in the thread-local.
+    fn enter<F, R>(self, f: F) -> R
+    where
+        F: FnOnce(Box<Core>, &Context) -> (Box<Core>, R),
+    {
+        let context = self.context.expect_current_thread();
+
+        // Remove `core` from `context` to pass into the closure.
+        let core = context.core.borrow_mut().take().expect("core missing");
+
+        // Call the closure and place `core` back
+        let (core, ret) = context::set_scheduler(&self.context, || f(core, context));
+
+        *context.core.borrow_mut() = Some(core);
+
+        ret
+    }
+}
+
+impl Drop for CoreGuard<'_> {
+    fn drop(&mut self) {
+        let context = self.context.expect_current_thread();
+
+        if let Some(core) = context.core.borrow_mut().take() {
+            // Replace old scheduler back into the state to allow
+            // other threads to pick it up and drive it.
+            self.scheduler.core.set(core);
+
+            // Wake up other possible threads that could steal the driver.
+            self.scheduler.notify.notify_one()
+        }
+    }
+}
diff --git a/vendor/tokio/src/runtime/scheduler/defer.rs b/vendor/tokio/src/runtime/scheduler/defer.rs
new file mode 100644
index 000000000..a4be8ef2e
--- /dev/null
+++ b/vendor/tokio/src/runtime/scheduler/defer.rs
@@ -0,0 +1,43 @@
+use std::cell::RefCell;
+use std::task::Waker;
+
+pub(crate) struct Defer {
+    deferred: RefCell<Vec<Waker>>,
+}
+
+impl Defer {
+    pub(crate) fn new() -> Defer {
+        Defer {
+            deferred: Default::default(),
+        }
+    }
+
+    pub(crate) fn defer(&self, waker: &Waker) {
+        let mut deferred = self.deferred.borrow_mut();
+
+        // If the same task adds itself a bunch of times, then only add it once.
+        if let Some(last) = deferred.last() {
+            if last.will_wake(waker) {
+                return;
+            }
+        }
+
+        deferred.push(waker.clone());
+    }
+
+    pub(crate) fn is_empty(&self) -> bool {
+        self.deferred.borrow().is_empty()
+    }
+
+    pub(crate) fn wake(&self) {
+        while let Some(waker) = self.deferred.borrow_mut().pop() {
+            waker.wake();
+        }
+    }
+
+    #[cfg(tokio_taskdump)]
+    pub(crate) fn take_deferred(&self) -> Vec<Waker> {
+        let mut deferred = self.deferred.borrow_mut();
+        std::mem::take(&mut *deferred)
+    }
+}
diff --git a/vendor/tokio/src/runtime/scheduler/inject.rs b/vendor/tokio/src/runtime/scheduler/inject.rs
new file mode 100644
index 000000000..39976fcd7
--- /dev/null
+++ b/vendor/tokio/src/runtime/scheduler/inject.rs
@@ -0,0 +1,72 @@
+//! Inject queue used to send wakeups to a work-stealing scheduler
+
+use crate::loom::sync::Mutex;
+use crate::runtime::task;
+
+mod pop;
+pub(crate) use pop::Pop;
+
+mod shared;
+pub(crate) use shared::Shared;
+
+mod synced;
+pub(crate) use synced::Synced;
+
+cfg_rt_multi_thread! {
+    mod rt_multi_thread;
+}
+
+cfg_metrics! {
+    mod metrics;
+}
+
+/// Growable, MPMC queue used to inject new tasks into the scheduler and as an
+/// overflow queue when the local, fixed-size, array queue overflows.
+pub(crate) struct Inject<T: 'static> {
+    shared: Shared<T>,
+    synced: Mutex<Synced>,
+}
+
+impl<T: 'static> Inject<T> {
+    pub(crate) fn new() -> Inject<T> {
+        let (shared, synced) = Shared::new();
+
+        Inject {
+            shared,
+            synced: Mutex::new(synced),
+        }
+    }
+
+    // Kind of annoying to have to include the cfg here
+    #[cfg(tokio_taskdump)]
+    pub(crate) fn is_closed(&self) -> bool {
+        let synced = self.synced.lock();
+        self.shared.is_closed(&synced)
+    }
+
+    /// Closes the injection queue, returns `true` if the queue is open when the
+    /// transition is made.
+    pub(crate) fn close(&self) -> bool {
+        let mut synced = self.synced.lock();
+        self.shared.close(&mut synced)
+    }
+
+    /// Pushes a value into the queue.
+    ///
+    /// This does nothing if the queue is closed.
+    pub(crate) fn push(&self, task: task::Notified<T>) {
+        let mut synced = self.synced.lock();
+        // safety: passing correct `Synced`
+        unsafe { self.shared.push(&mut synced, task) }
+    }
+
+    pub(crate) fn pop(&self) -> Option<task::Notified<T>> {
+        if self.shared.is_empty() {
+            return None;
+        }
+
+        let mut synced = self.synced.lock();
+        // safety: passing correct `Synced`
+        unsafe { self.shared.pop(&mut synced) }
+    }
+}
diff --git a/vendor/tokio/src/runtime/scheduler/inject/metrics.rs b/vendor/tokio/src/runtime/scheduler/inject/metrics.rs
new file mode 100644
index 000000000..76f045fdb
--- /dev/null
+++ b/vendor/tokio/src/runtime/scheduler/inject/metrics.rs
@@ -0,0 +1,7 @@
+use super::Inject;
+
+impl<T: 'static> Inject<T> {
+    pub(crate) fn len(&self) -> usize {
+        self.shared.len()
+    }
+}
diff --git a/vendor/tokio/src/runtime/scheduler/inject/pop.rs b/vendor/tokio/src/runtime/scheduler/inject/pop.rs
new file mode 100644
index 000000000..4e6d5d3be
--- /dev/null
+++ b/vendor/tokio/src/runtime/scheduler/inject/pop.rs
@@ -0,0 +1,55 @@
+use super::Synced;
+
+use crate::runtime::task;
+
+use std::marker::PhantomData;
+
+pub(crate) struct Pop<'a, T: 'static> {
+    len: usize,
+    synced: &'a mut Synced,
+    _p: PhantomData<T>,
+}
+
+impl<'a, T: 'static> Pop<'a, T> {
+    pub(super) fn new(len: usize, synced: &'a mut Synced) -> Pop<'a, T> {
+        Pop {
+            len,
+            synced,
+            _p: PhantomData,
+        }
+    }
+}
+
+impl<'a, T: 'static> Iterator for Pop<'a, T> {
+    type Item = task::Notified<T>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        if self.len == 0 {
+            return None;
+        }
+
+        let ret = self.synced.pop();
+
+        // Should be `Some` when `len > 0`
+        debug_assert!(ret.is_some());
+
+        self.len -= 1;
+        ret
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        (self.len, Some(self.len))
+    }
+}
+
+impl<'a, T: 'static> ExactSizeIterator for Pop<'a, T> {
+    fn len(&self) -> usize {
+        self.len
+    }
+}
+
+impl<'a, T: 'static> Drop for Pop<'a, T> {
+    fn drop(&mut self) {
+        for _ in self.by_ref() {}
+    }
+}
diff --git a/vendor/tokio/src/runtime/scheduler/inject/rt_multi_thread.rs b/vendor/tokio/src/runtime/scheduler/inject/rt_multi_thread.rs
new file mode 100644
index 000000000..07d1063c5
--- /dev/null
+++ b/vendor/tokio/src/runtime/scheduler/inject/rt_multi_thread.rs
@@ -0,0 +1,98 @@
+use super::{Shared, Synced};
+
+use crate::runtime::scheduler::Lock;
+use crate::runtime::task;
+
+use std::sync::atomic::Ordering::Release;
+
+impl<'a> Lock<Synced> for &'a mut Synced {
+    type Handle = &'a mut Synced;
+
+    fn lock(self) -> Self::Handle {
+        self
+    }
+}
+
+impl AsMut<Synced> for Synced {
+    fn as_mut(&mut self) -> &mut Synced {
+        self
+    }
+}
+
+impl<T: 'static> Shared<T> {
+    /// Pushes several values into the queue.
+    ///
+    /// # Safety
+    ///
+    /// Must be called with the same `Synced` instance returned by `Inject::new`
+    #[inline]
+    pub(crate) unsafe fn push_batch<L, I>(&self, shared: L, mut iter: I)
+    where
+        L: Lock<Synced>,
+        I: Iterator<Item = task::Notified<T>>,
+    {
+        let first = match iter.next() {
+            Some(first) => first.into_raw(),
+            None => return,
+        };
+
+        // Link up all the tasks.
+        let mut prev = first;
+        let mut counter = 1;
+
+        // We are going to be called with an `std::iter::Chain`, and that
+        // iterator overrides `for_each` to something that is easier for the
+        // compiler to optimize than a loop.
+        iter.for_each(|next| {
+            let next = next.into_raw();
+
+            // safety: Holding the Notified for a task guarantees exclusive
+            // access to the `queue_next` field.
+            unsafe { prev.set_queue_next(Some(next)) };
+            prev = next;
+            counter += 1;
+        });
+
+        // Now that the tasks are linked together, insert them into the
+        // linked list.
+        self.push_batch_inner(shared, first, prev, counter);
+    }
+
+    /// Inserts several tasks that have been linked together into the queue.
+    ///
+    /// The provided head and tail may be be the same task. In this case, a
+    /// single task is inserted.
+    #[inline]
+    unsafe fn push_batch_inner<L>(
+        &self,
+        shared: L,
+        batch_head: task::RawTask,
+        batch_tail: task::RawTask,
+        num: usize,
+    ) where
+        L: Lock<Synced>,
+    {
+        debug_assert!(unsafe { batch_tail.get_queue_next().is_none() });
+
+        let mut synced = shared.lock();
+        let synced = synced.as_mut();
+
+        if let Some(tail) = synced.tail {
+            unsafe {
+                tail.set_queue_next(Some(batch_head));
+            }
+        } else {
+            synced.head = Some(batch_head);
+        }
+
+        synced.tail = Some(batch_tail);
+
+        // Increment the count.
+        //
+        // safety: All updates to the len atomic are guarded by the mutex. As
+        // such, a non-atomic load followed by a store is safe.
+        let len = self.len.unsync_load();
+
+        self.len.store(len + num, Release);
+    }
+}
diff --git a/vendor/tokio/src/runtime/scheduler/inject/shared.rs b/vendor/tokio/src/runtime/scheduler/inject/shared.rs
new file mode 100644
index 000000000..7fdd2839d
--- /dev/null
+++ b/vendor/tokio/src/runtime/scheduler/inject/shared.rs
@@ -0,0 +1,119 @@
+use super::{Pop, Synced};
+
+use crate::loom::sync::atomic::AtomicUsize;
+use crate::runtime::task;
+
+use std::marker::PhantomData;
+use std::sync::atomic::Ordering::{Acquire, Release};
+
+pub(crate) struct Shared<T: 'static> {
+    /// Number of pending tasks in the queue. This helps prevent unnecessary
+    /// locking in the hot path.
+    pub(super) len: AtomicUsize,
+
+    _p: PhantomData<T>,
+}
+
+unsafe impl<T> Send for Shared<T> {}
+unsafe impl<T> Sync for Shared<T> {}
+
+impl<T: 'static> Shared<T> {
+    pub(crate) fn new() -> (Shared<T>, Synced) {
+        let inject = Shared {
+            len: AtomicUsize::new(0),
+            _p: PhantomData,
+        };
+
+        let synced = Synced {
+            is_closed: false,
+            head: None,
+            tail: None,
+        };
+
+        (inject, synced)
+    }
+
+    pub(crate) fn is_empty(&self) -> bool {
+        self.len() == 0
+    }
+
+    // Kind of annoying to have to include the cfg here
+    #[cfg(any(tokio_taskdump, all(feature = "rt-multi-thread", not(tokio_wasi))))]
+    pub(crate) fn is_closed(&self, synced: &Synced) -> bool {
+        synced.is_closed
+    }
+
+    /// Closes the injection queue, returns `true` if the queue is open when the
+    /// transition is made.
+    pub(crate) fn close(&self, synced: &mut Synced) -> bool {
+        if synced.is_closed {
+            return false;
+        }
+
+        synced.is_closed = true;
+        true
+    }
+
+    pub(crate) fn len(&self) -> usize {
+        self.len.load(Acquire)
+    }
+
+    /// Pushes a value into the queue.
+    ///
+    /// This does nothing if the queue is closed.
+    ///
+    /// # Safety
+    ///
+    /// Must be called with the same `Synced` instance returned by `Inject::new`
+    pub(crate) unsafe fn push(&self, synced: &mut Synced, task: task::Notified<T>) {
+        if synced.is_closed {
+            return;
+        }
+
+        // safety: only mutated with the lock held
+        let len = self.len.unsync_load();
+        let task = task.into_raw();
+
+        // The next pointer should already be null
+        debug_assert!(unsafe { task.get_queue_next().is_none() });
+
+        if let Some(tail) = synced.tail {
+            // safety: Holding the Notified for a task guarantees exclusive
+            // access to the `queue_next` field.
+            unsafe { tail.set_queue_next(Some(task)) };
+        } else {
+            synced.head = Some(task);
+        }
+
+        synced.tail = Some(task);
+        self.len.store(len + 1, Release);
+    }
+
+    /// Pop a value from the queue.
+    ///
+    /// # Safety
+    ///
+    /// Must be called with the same `Synced` instance returned by `Inject::new`
+    pub(crate) unsafe fn pop(&self, synced: &mut Synced) -> Option<task::Notified<T>> {
+        self.pop_n(synced, 1).next()
+    }
+
+    /// Pop `n` values from the queue
+    ///
+    /// # Safety
+    ///
+    /// Must be called with the same `Synced` instance returned by `Inject::new`
+    pub(crate) unsafe fn pop_n<'a>(&'a self, synced: &'a mut Synced, n: usize) -> Pop<'a, T> {
+        use std::cmp;
+
+        // safety: All updates to the len atomic are guarded by the mutex. As
+        // such, a non-atomic load followed by a store is safe.
+        let len = self.len.unsync_load();
+        let n = cmp::min(n, len);
+
+        // Decrement the count.
+        self.len.store(len - n, Release);
+
+        Pop::new(n, synced)
+    }
+}
diff --git a/vendor/tokio/src/runtime/scheduler/inject/synced.rs b/vendor/tokio/src/runtime/scheduler/inject/synced.rs
new file mode 100644
index 000000000..6847f68e5
--- /dev/null
+++ b/vendor/tokio/src/runtime/scheduler/inject/synced.rs
@@ -0,0 +1,32 @@
+use crate::runtime::task;
+
+pub(crate) struct Synced {
+    /// True if the queue is closed.
+    pub(super) is_closed: bool,
+
+    /// Linked-list head.
+    pub(super) head: Option<task::RawTask>,
+
+    /// Linked-list tail.
+    pub(super) tail: Option<task::RawTask>,
+}
+
+unsafe impl Send for Synced {}
+unsafe impl Sync for Synced {}
+
+impl Synced {
+    pub(super) fn pop<T: 'static>(&mut self) -> Option<task::Notified<T>> {
+        let task = self.head?;
+
+        self.head = unsafe { task.get_queue_next() };
+
+        if self.head.is_none() {
+            self.tail = None;
+        }
+
+        unsafe { task.set_queue_next(None) };
+
+        // safety: a `Notified` is pushed into the queue and now it is popped!
+        Some(unsafe { task::Notified::from_raw(task) })
+    }
+}
diff --git a/vendor/tokio/src/runtime/scheduler/lock.rs b/vendor/tokio/src/runtime/scheduler/lock.rs
new file mode 100644
index 000000000..0901c2b37
--- /dev/null
+++ b/vendor/tokio/src/runtime/scheduler/lock.rs
@@ -0,0 +1,6 @@
+/// A lock (mutex) yielding generic data.
+pub(crate) trait Lock<T> {
+    type Handle: AsMut<T>;
+
+    fn lock(self) -> Self::Handle;
+}
diff --git a/vendor/tokio/src/runtime/scheduler/mod.rs b/vendor/tokio/src/runtime/scheduler/mod.rs
new file mode 100644
index 000000000..3e3151711
--- /dev/null
+++ b/vendor/tokio/src/runtime/scheduler/mod.rs
@@ -0,0 +1,249 @@
+cfg_rt! {
+    pub(crate) mod current_thread;
+    pub(crate) use current_thread::CurrentThread;
+
+    mod defer;
+    use defer::Defer;
+
+    pub(crate) mod inject;
+    pub(crate) use inject::Inject;
+}
+
+cfg_rt_multi_thread! {
+    mod lock;
+    use lock::Lock;
+
+    pub(crate) mod multi_thread;
+    pub(crate) use multi_thread::MultiThread;
+}
+
+use crate::runtime::driver;
+
+#[derive(Debug, Clone)]
+pub(crate) enum Handle {
+    #[cfg(feature = "rt")]
+    CurrentThread(Arc<current_thread::Handle>),
+
+    #[cfg(all(feature = "rt-multi-thread", not(tokio_wasi)))]
+    MultiThread(Arc<multi_thread::Handle>),
+
+    // TODO: This is to avoid triggering "dead code" warnings many other places
+    // in the codebase. Remove this during a later cleanup
+    #[cfg(not(feature = "rt"))]
+    #[allow(dead_code)]
+    Disabled,
+}
+
+#[cfg(feature = "rt")]
+pub(super) enum Context {
+    CurrentThread(current_thread::Context),
+
+    #[cfg(all(feature = "rt-multi-thread", not(tokio_wasi)))]
+    MultiThread(multi_thread::Context),
+}
+
+impl Handle {
+    #[cfg_attr(not(feature = "full"), allow(dead_code))]
+    pub(crate) fn driver(&self) -> &driver::Handle {
+        match *self {
+            #[cfg(feature = "rt")]
+            Handle::CurrentThread(ref h) => &h.driver,
+
+            #[cfg(all(feature = "rt-multi-thread", not(tokio_wasi)))]
+            Handle::MultiThread(ref h) => &h.driver,
+
+            #[cfg(not(feature = "rt"))]
+            Handle::Disabled => unreachable!(),
+        }
+    }
+}
+
+cfg_rt! {
+    use crate::future::Future;
+    use crate::loom::sync::Arc;
+    use crate::runtime::{blocking, task::Id};
+    use crate::runtime::context;
+    use crate::task::JoinHandle;
+    use crate::util::RngSeedGenerator;
+    use std::task::Waker;
+
+    impl Handle {
+        #[track_caller]
+        pub(crate) fn current() -> Handle {
+            match context::with_current(Clone::clone) {
+                Ok(handle) => handle,
+                Err(e) => panic!("{}", e),
+            }
+        }
+
+        pub(crate) fn blocking_spawner(&self) -> &blocking::Spawner {
+            match self {
+                Handle::CurrentThread(h) => &h.blocking_spawner,
+
+                #[cfg(all(feature = "rt-multi-thread", not(tokio_wasi)))]
+                Handle::MultiThread(h) => &h.blocking_spawner,
+            }
+        }
+
+        pub(crate) fn spawn<F>(&self, future: F, id: Id) -> JoinHandle<F::Output>
+        where
+            F: Future + Send + 'static,
+            F::Output: Send + 'static,
+        {
+            match self {
+                Handle::CurrentThread(h) => current_thread::Handle::spawn(h, future, id),
+
+                #[cfg(all(feature = "rt-multi-thread", not(tokio_wasi)))]
+                Handle::MultiThread(h) => multi_thread::Handle::spawn(h, future, id),
+            }
+        }
+
+        pub(crate) fn shutdown(&self) {
+            match *self {
+                Handle::CurrentThread(_) => {},
+
+                #[cfg(all(feature = "rt-multi-thread", not(tokio_wasi)))]
+                Handle::MultiThread(ref h) => h.shutdown(),
+            }
+        }
+
+        pub(crate) fn seed_generator(&self) -> &RngSeedGenerator {
+            match self {
+                Handle::CurrentThread(h) => &h.seed_generator,
+
+                #[cfg(all(feature = "rt-multi-thread", not(tokio_wasi)))]
+                Handle::MultiThread(h) => &h.seed_generator,
+            }
+        }
+
+        pub(crate) fn as_current_thread(&self) -> &Arc<current_thread::Handle> {
+            match self {
+                Handle::CurrentThread(handle) => handle,
+                #[cfg(all(feature = "rt-multi-thread", not(tokio_wasi)))]
+                _ => panic!("not a CurrentThread handle"),
+            }
+        }
+    }
+
+    cfg_metrics! {
+        use crate::runtime::{SchedulerMetrics, WorkerMetrics};
+
+        impl Handle {
+            pub(crate) fn num_workers(&self) -> usize {
+                match self {
+                    Handle::CurrentThread(_) => 1,
+                    #[cfg(all(feature = "rt-multi-thread", not(tokio_wasi)))]
+                    Handle::MultiThread(handle) => handle.num_workers(),
+                }
+            }
+
+            pub(crate) fn num_blocking_threads(&self) -> usize {
+                match self {
+                    Handle::CurrentThread(handle) => handle.num_blocking_threads(),
+                    #[cfg(all(feature = "rt-multi-thread", not(tokio_wasi)))]
+                    Handle::MultiThread(handle) => handle.num_blocking_threads(),
+                }
+            }
+
+            pub(crate) fn num_idle_blocking_threads(&self) -> usize {
+                match self {
+                    Handle::CurrentThread(handle) => handle.num_idle_blocking_threads(),
+                    #[cfg(all(feature = "rt-multi-thread", not(tokio_wasi)))]
+                    Handle::MultiThread(handle) => handle.num_idle_blocking_threads(),
+                }
+            }
+
+            pub(crate) fn active_tasks_count(&self) -> usize {
+                match self {
+                    Handle::CurrentThread(handle) => handle.active_tasks_count(),
+                    #[cfg(all(feature = "rt-multi-thread", not(tokio_wasi)))]
+                    Handle::MultiThread(handle) => handle.active_tasks_count(),
+                }
+            }
+
+            pub(crate) fn scheduler_metrics(&self) -> &SchedulerMetrics {
+                match self {
+                    Handle::CurrentThread(handle) => handle.scheduler_metrics(),
+                    #[cfg(all(feature = "rt-multi-thread", not(tokio_wasi)))]
+                    Handle::MultiThread(handle) => handle.scheduler_metrics(),
+                }
+            }
+
+            pub(crate) fn worker_metrics(&self, worker: usize) -> &WorkerMetrics {
+                match self {
+                    Handle::CurrentThread(handle) => handle.worker_metrics(worker),
+                    #[cfg(all(feature = "rt-multi-thread", not(tokio_wasi)))]
+                    Handle::MultiThread(handle) => handle.worker_metrics(worker),
+                }
+            }
+
+            pub(crate) fn injection_queue_depth(&self) -> usize {
+                match self {
+                    Handle::CurrentThread(handle) => handle.injection_queue_depth(),
+                    #[cfg(all(feature = "rt-multi-thread", not(tokio_wasi)))]
+                    Handle::MultiThread(handle) => handle.injection_queue_depth(),
+                }
+            }
+
+            pub(crate) fn worker_local_queue_depth(&self, worker: usize) -> usize {
+                match self {
+                    Handle::CurrentThread(handle) => handle.worker_metrics(worker).queue_depth(),
+                    #[cfg(all(feature = "rt-multi-thread", not(tokio_wasi)))]
+                    Handle::MultiThread(handle) => handle.worker_local_queue_depth(worker),
+                }
+            }
+
+            pub(crate) fn blocking_queue_depth(&self) -> usize {
+                match self {
+                    Handle::CurrentThread(handle) => handle.blocking_queue_depth(),
+                    #[cfg(all(feature = "rt-multi-thread", not(tokio_wasi)))]
+                    Handle::MultiThread(handle) => handle.blocking_queue_depth(),
+                }
+            }
+        }
+    }
+
+    impl Context {
+        #[track_caller]
+        pub(crate) fn expect_current_thread(&self) -> &current_thread::Context {
+            match self {
+                Context::CurrentThread(context) => context,
+                #[cfg(all(feature = "rt-multi-thread", not(tokio_wasi)))]
+                _ => panic!("expected `CurrentThread::Context`")
+            }
+        }
+
+        pub(crate) fn defer(&self, waker: &Waker) {
+            match self {
+                Context::CurrentThread(context) => context.defer(waker),
+                #[cfg(all(feature = "rt-multi-thread", not(tokio_wasi)))]
+                Context::MultiThread(context) => context.defer(waker),
+            }
+        }
+
+        cfg_rt_multi_thread! {
+            #[track_caller]
+            pub(crate) fn expect_multi_thread(&self) -> &multi_thread::Context {
+                match self {
+                    Context::MultiThread(context) => context,
+                    _ => panic!("expected `MultiThread::Context`")
+                }
+            }
+        }
+    }
+}
+
+cfg_not_rt! {
+    #[cfg(any(
+        feature = "net",
+        all(unix, feature = "process"),
+        all(unix, feature = "signal"),
+        feature = "time",
+    ))]
+    impl Handle {
+        #[track_caller]
+        pub(crate) fn current() -> Handle {
+            panic!("{}", crate::util::error::CONTEXT_MISSING_ERROR)
+        }
+    }
+}
diff --git a/vendor/tokio/src/runtime/scheduler/multi_thread/counters.rs b/vendor/tokio/src/runtime/scheduler/multi_thread/counters.rs
new file mode 100644
index 000000000..50bcc1198
--- /dev/null
+++ b/vendor/tokio/src/runtime/scheduler/multi_thread/counters.rs
@@ -0,0 +1,62 @@
+#[cfg(tokio_internal_mt_counters)]
+mod imp {
+    use std::sync::atomic::AtomicUsize;
+    use std::sync::atomic::Ordering::Relaxed;
+
+    static NUM_MAINTENANCE: AtomicUsize = AtomicUsize::new(0);
+    static NUM_NOTIFY_LOCAL: AtomicUsize = AtomicUsize::new(0);
+    static NUM_UNPARKS_LOCAL: AtomicUsize = AtomicUsize::new(0);
+    static NUM_LIFO_SCHEDULES: AtomicUsize = AtomicUsize::new(0);
+    static NUM_LIFO_CAPPED: AtomicUsize = AtomicUsize::new(0);
+
+    impl Drop for super::Counters {
+        fn drop(&mut self) {
+            let notifies_local = NUM_NOTIFY_LOCAL.load(Relaxed);
+            let unparks_local = NUM_UNPARKS_LOCAL.load(Relaxed);
+            let maintenance = NUM_MAINTENANCE.load(Relaxed);
+            let lifo_scheds = NUM_LIFO_SCHEDULES.load(Relaxed);
+            let lifo_capped = NUM_LIFO_CAPPED.load(Relaxed);
+
+            println!("---");
+            println!("notifies (local): {}", notifies_local);
+            println!(" unparks (local): {}", unparks_local);
+            println!("     maintenance: {}", maintenance);
+            println!("  LIFO schedules: {}", lifo_scheds);
+            println!("     LIFO capped: {}", lifo_capped);
+        }
+    }
+
+    pub(crate) fn inc_num_inc_notify_local() {
+        NUM_NOTIFY_LOCAL.fetch_add(1, Relaxed);
+    }
+
+    pub(crate) fn inc_num_unparks_local() {
+        NUM_UNPARKS_LOCAL.fetch_add(1, Relaxed);
+    }
+
+    pub(crate) fn inc_num_maintenance() {
+        NUM_MAINTENANCE.fetch_add(1, Relaxed);
+    }
+
+    pub(crate) fn inc_lifo_schedules() {
+        NUM_LIFO_SCHEDULES.fetch_add(1, Relaxed);
+    }
+
+    pub(crate) fn inc_lifo_capped() {
+        NUM_LIFO_CAPPED.fetch_add(1, Relaxed);
+    }
+}
+
+#[cfg(not(tokio_internal_mt_counters))]
+mod imp {
+    pub(crate) fn inc_num_inc_notify_local() {}
+    pub(crate) fn inc_num_unparks_local() {}
+    pub(crate) fn inc_num_maintenance() {}
+    pub(crate) fn inc_lifo_schedules() {}
+    pub(crate) fn inc_lifo_capped() {}
+}
+
+#[derive(Debug)]
+pub(crate) struct Counters;
+
+pub(super) use imp::*;
diff --git a/vendor/tokio/src/runtime/scheduler/multi_thread/handle.rs b/vendor/tokio/src/runtime/scheduler/multi_thread/handle.rs
new file mode 100644
index 000000000..98e476585
--- /dev/null
+++ b/vendor/tokio/src/runtime/scheduler/multi_thread/handle.rs
@@ -0,0 +1,68 @@
+use crate::future::Future;
+use crate::loom::sync::Arc;
+use crate::runtime::scheduler::multi_thread::worker;
+use crate::runtime::{
+    blocking, driver,
+    task::{self, JoinHandle},
+};
+use crate::util::RngSeedGenerator;
+
+use std::fmt;
+
+cfg_metrics! {
+    mod metrics;
+}
+
+cfg_taskdump! {
+    mod taskdump;
+}
+
+/// Handle to the multi thread scheduler
+pub(crate) struct Handle {
+    /// Task spawner
+    pub(super) shared: worker::Shared,
+
+    /// Resource driver handles
+    pub(crate) driver: driver::Handle,
+
+    /// Blocking pool spawner
+    pub(crate) blocking_spawner: blocking::Spawner,
+
+    /// Current random number generator seed
+    pub(crate) seed_generator: RngSeedGenerator,
+}
+
+impl Handle {
+    /// Spawns a future onto the thread pool
+    pub(crate) fn spawn<F>(me: &Arc<Self>, future: F, id: task::Id) -> JoinHandle<F::Output>
+    where
+        F: crate::future::Future + Send + 'static,
+        F::Output: Send + 'static,
+    {
+        Self::bind_new_task(me, future, id)
+    }
+
+    pub(crate) fn shutdown(&self) {
+        self.close();
+    }
+
+    pub(super) fn bind_new_task<T>(me: &Arc<Self>, future: T, id: task::Id) -> JoinHandle<T::Output>
+    where
+        T: Future + Send + 'static,
+        T::Output: Send + 'static,
+    {
+        let (handle, notified) = me.shared.owned.bind(future, me.clone(), id);
+
+        if let Some(notified) = notified {
+            me.schedule_task(notified, false);
+        }
+
+        handle
+    }
+}
+
+impl fmt::Debug for Handle {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt.debug_struct("multi_thread::Handle { ... }").finish()
+    }
+}
diff --git a/vendor/tokio/src/runtime/scheduler/multi_thread/handle/metrics.rs b/vendor/tokio/src/runtime/scheduler/multi_thread/handle/metrics.rs
new file mode 100644
index 000000000..838694fc8
--- /dev/null
+++ b/vendor/tokio/src/runtime/scheduler/multi_thread/handle/metrics.rs
@@ -0,0 +1,41 @@
+use super::Handle;
+
+use crate::runtime::{SchedulerMetrics, WorkerMetrics};
+
+impl Handle {
+    pub(crate) fn num_workers(&self) -> usize {
+        self.shared.worker_metrics.len()
+    }
+
+    pub(crate) fn num_blocking_threads(&self) -> usize {
+        self.blocking_spawner.num_threads()
+    }
+
+    pub(crate) fn num_idle_blocking_threads(&self) -> usize {
+        self.blocking_spawner.num_idle_threads()
+    }
+
+    pub(crate) fn active_tasks_count(&self) -> usize {
+        self.shared.owned.active_tasks_count()
+    }
+
+    pub(crate) fn scheduler_metrics(&self) -> &SchedulerMetrics {
+        &self.shared.scheduler_metrics
+    }
+
+    pub(crate) fn worker_metrics(&self, worker: usize) -> &WorkerMetrics {
+        &self.shared.worker_metrics[worker]
+    }
+
+    pub(crate) fn injection_queue_depth(&self) -> usize {
+        self.shared.injection_queue_depth()
+    }
+
+    pub(crate) fn worker_local_queue_depth(&self, worker: usize) -> usize {
+        self.shared.worker_local_queue_depth(worker)
+    }
+
+    pub(crate) fn blocking_queue_depth(&self) -> usize {
+        self.blocking_spawner.queue_depth()
+    }
+}
diff --git a/vendor/tokio/src/runtime/scheduler/multi_thread/handle/taskdump.rs b/vendor/tokio/src/runtime/scheduler/multi_thread/handle/taskdump.rs
new file mode 100644
index 000000000..477d857d8
--- /dev/null
+++ b/vendor/tokio/src/runtime/scheduler/multi_thread/handle/taskdump.rs
@@ -0,0 +1,26 @@
+use super::Handle;
+
+use crate::runtime::Dump;
+
+impl Handle {
+    pub(crate) async fn dump(&self) -> Dump {
+        let trace_status = &self.shared.trace_status;
+
+        // If a dump is in progress, block.
+        trace_status.start_trace_request(&self).await;
+
+        let result = loop {
+            if let Some(result) = trace_status.take_result() {
+                break result;
+            } else {
+                self.notify_all();
+                trace_status.result_ready.notified().await;
+            }
+        };
+
+        // Allow other queued dumps to proceed.
+        trace_status.end_trace_request(&self).await;
+
+        result
+    }
+}
diff --git a/vendor/tokio/src/runtime/thread_pool/idle.rs b/vendor/tokio/src/runtime/scheduler/multi_thread/idle.rs
index 2cac30ee8..834bc2b66 100644
--- a/vendor/tokio/src/runtime/thread_pool/idle.rs
+++ b/vendor/tokio/src/runtime/scheduler/multi_thread/idle.rs
@@ -1,7 +1,7 @@
 //! Coordinates idling workers
 
 use crate::loom::sync::atomic::AtomicUsize;
-use crate::loom::sync::Mutex;
+use crate::runtime::scheduler::multi_thread::Shared;
 
 use std::fmt;
 use std::sync::atomic::Ordering::{self, SeqCst};
@@ -13,13 +13,16 @@ pub(super) struct Idle {
     /// Used as a fast-path to avoid acquiring the lock when needed.
     state: AtomicUsize,
 
-    /// Sleeping workers
-    sleepers: Mutex<Vec<usize>>,
-
     /// Total number of workers.
     num_workers: usize,
 }
 
+/// Data synchronized by the scheduler mutex
+pub(super) struct Synced {
+    /// Sleeping workers
+    sleepers: Vec<usize>,
+}
+
 const UNPARK_SHIFT: usize = 16;
 const UNPARK_MASK: usize = !SEARCH_MASK;
 const SEARCH_MASK: usize = (1 << UNPARK_SHIFT) - 1;
@@ -28,19 +31,24 @@ const SEARCH_MASK: usize = (1 << UNPARK_SHIFT) - 1;
 struct State(usize);
 
 impl Idle {
-    pub(super) fn new(num_workers: usize) -> Idle {
+    pub(super) fn new(num_workers: usize) -> (Idle, Synced) {
         let init = State::new(num_workers);
 
-        Idle {
+        let idle = Idle {
             state: AtomicUsize::new(init.into()),
-            sleepers: Mutex::new(Vec::with_capacity(num_workers)),
             num_workers,
-        }
+        };
+
+        let synced = Synced {
+            sleepers: Vec::with_capacity(num_workers),
+        };
+
+        (idle, synced)
     }
 
     /// If there are no workers actively searching, returns the index of a
     /// worker currently sleeping.
-    pub(super) fn worker_to_notify(&self) -> Option<usize> {
+    pub(super) fn worker_to_notify(&self, shared: &Shared) -> Option<usize> {
         // If at least one worker is spinning, work being notified will
         // eventually be found. A searching thread will find **some** work and
         // notify another worker, eventually leading to our work being found.
@@ -55,7 +63,7 @@ impl Idle {
         }
 
         // Acquire the lock
-        let mut sleepers = self.sleepers.lock();
+        let mut lock = shared.synced.lock();
 
         // Check again, now that the lock is acquired
         if !self.notify_should_wakeup() {
@@ -64,10 +72,10 @@ impl Idle {
 
         // A worker should be woken up, atomically increment the number of
         // searching workers as well as the number of unparked workers.
-        State::unpark_one(&self.state);
+        State::unpark_one(&self.state, 1);
 
         // Get the worker to unpark
-        let ret = sleepers.pop();
+        let ret = lock.idle.sleepers.pop();
         debug_assert!(ret.is_some());
 
         ret
@@ -75,15 +83,20 @@ impl Idle {
 
     /// Returns `true` if the worker needs to do a final check for submitted
     /// work.
-    pub(super) fn transition_worker_to_parked(&self, worker: usize, is_searching: bool) -> bool {
+    pub(super) fn transition_worker_to_parked(
+        &self,
+        shared: &Shared,
+        worker: usize,
+        is_searching: bool,
+    ) -> bool {
         // Acquire the lock
-        let mut sleepers = self.sleepers.lock();
+        let mut lock = shared.synced.lock();
 
         // Decrement the number of unparked threads
         let ret = State::dec_num_unparked(&self.state, is_searching);
 
         // Track the sleeping worker
-        sleepers.push(worker);
+        lock.idle.sleepers.push(worker);
 
         ret
     }
@@ -111,25 +124,30 @@ impl Idle {
 
     /// Unpark a specific worker. This happens if tasks are submitted from
     /// within the worker's park routine.
-    pub(super) fn unpark_worker_by_id(&self, worker_id: usize) {
-        let mut sleepers = self.sleepers.lock();
+    ///
+    /// Returns `true` if the worker was parked before calling the method.
+    pub(super) fn unpark_worker_by_id(&self, shared: &Shared, worker_id: usize) -> bool {
+        let mut lock = shared.synced.lock();
+        let sleepers = &mut lock.idle.sleepers;
 
         for index in 0..sleepers.len() {
             if sleepers[index] == worker_id {
                 sleepers.swap_remove(index);
 
                 // Update the state accordingly while the lock is held.
-                State::unpark_one(&self.state);
+                State::unpark_one(&self.state, 0);
 
-                return;
+                return true;
             }
         }
+
+        false
     }
 
-    /// Returns `true` if `worker_id` is contained in the sleep set
-    pub(super) fn is_parked(&self, worker_id: usize) -> bool {
-        let sleepers = self.sleepers.lock();
-        sleepers.contains(&worker_id)
+    /// Returns `true` if `worker_id` is contained in the sleep set.
+    pub(super) fn is_parked(&self, shared: &Shared, worker_id: usize) -> bool {
+        let lock = shared.synced.lock();
+        lock.idle.sleepers.contains(&worker_id)
     }
 
     fn notify_should_wakeup(&self) -> bool {
@@ -151,8 +169,8 @@ impl State {
         State(cell.load(ordering))
     }
 
-    fn unpark_one(cell: &AtomicUsize) {
-        cell.fetch_add(1 | (1 << UNPARK_SHIFT), SeqCst);
+    fn unpark_one(cell: &AtomicUsize, num_searching: usize) {
+        cell.fetch_add(num_searching | (1 << UNPARK_SHIFT), SeqCst);
     }
 
     fn inc_num_searching(cell: &AtomicUsize, ordering: Ordering) {
diff --git a/vendor/tokio/src/runtime/scheduler/multi_thread/mod.rs b/vendor/tokio/src/runtime/scheduler/multi_thread/mod.rs
new file mode 100644
index 000000000..d85a0ae0a
--- /dev/null
+++ b/vendor/tokio/src/runtime/scheduler/multi_thread/mod.rs
@@ -0,0 +1,103 @@
+//! Multi-threaded runtime
+
+mod counters;
+use counters::Counters;
+
+mod handle;
+pub(crate) use handle::Handle;
+
+mod overflow;
+pub(crate) use overflow::Overflow;
+
+mod idle;
+use self::idle::Idle;
+
+mod stats;
+pub(crate) use stats::Stats;
+
+mod park;
+pub(crate) use park::{Parker, Unparker};
+
+pub(crate) mod queue;
+
+mod worker;
+pub(crate) use worker::{Context, Launch, Shared};
+
+cfg_taskdump! {
+    mod trace;
+    use trace::TraceStatus;
+
+    pub(crate) use worker::Synced;
+}
+
+cfg_not_taskdump! {
+    mod trace_mock;
+    use trace_mock::TraceStatus;
+}
+
+pub(crate) use worker::block_in_place;
+
+use crate::loom::sync::Arc;
+use crate::runtime::{
+    blocking,
+    driver::{self, Driver},
+    scheduler, Config,
+};
+use crate::util::RngSeedGenerator;
+
+use std::fmt;
+use std::future::Future;
+
+/// Work-stealing based thread pool for executing futures.
+pub(crate) struct MultiThread;
+
+// ===== impl MultiThread =====
+
+impl MultiThread {
+    pub(crate) fn new(
+        size: usize,
+        driver: Driver,
+        driver_handle: driver::Handle,
+        blocking_spawner: blocking::Spawner,
+        seed_generator: RngSeedGenerator,
+        config: Config,
+    ) -> (MultiThread, Arc<Handle>, Launch) {
+        let parker = Parker::new(driver);
+        let (handle, launch) = worker::create(
+            size,
+            parker,
+            driver_handle,
+            blocking_spawner,
+            seed_generator,
+            config,
+        );
+
+        (MultiThread, handle, launch)
+    }
+
+    /// Blocks the current thread waiting for the future to complete.
+    ///
+    /// The future will execute on the current thread, but all spawned tasks
+    /// will be executed on the thread pool.
+    pub(crate) fn block_on<F>(&self, handle: &scheduler::Handle, future: F) -> F::Output
+    where
+        F: Future,
+    {
+        crate::runtime::context::enter_runtime(handle, true, |blocking| {
+            blocking.block_on(future).expect("failed to park thread")
+        })
+    }
+
+    pub(crate) fn shutdown(&mut self, handle: &scheduler::Handle) {
+        match handle {
+            scheduler::Handle::MultiThread(handle) => handle.shutdown(),
+            _ => panic!("expected MultiThread scheduler"),
+        }
+    }
+}
+
+impl fmt::Debug for MultiThread {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt.debug_struct("MultiThread").finish()
+    }
+}
diff --git a/vendor/tokio/src/runtime/scheduler/multi_thread/overflow.rs b/vendor/tokio/src/runtime/scheduler/multi_thread/overflow.rs
new file mode 100644
index 000000000..ab664811c
--- /dev/null
+++ b/vendor/tokio/src/runtime/scheduler/multi_thread/overflow.rs
@@ -0,0 +1,26 @@
+use crate::runtime::task;
+
+#[cfg(test)]
+use std::cell::RefCell;
+
+pub(crate) trait Overflow<T: 'static> {
+    fn push(&self, task: task::Notified<T>);
+
+    fn push_batch<I>(&self, iter: I)
+    where
+        I: Iterator<Item = task::Notified<T>>;
+}
+
+#[cfg(test)]
+impl<T: 'static> Overflow<T> for RefCell<Vec<task::Notified<T>>> {
+    fn push(&self, task: task::Notified<T>) {
+        self.borrow_mut().push(task);
+    }
+
+    fn push_batch<I>(&self, iter: I)
+    where
+        I: Iterator<Item = task::Notified<T>>,
+    {
+        self.borrow_mut().extend(iter);
+    }
+}
diff --git a/vendor/tokio/src/runtime/scheduler/multi_thread/park.rs b/vendor/tokio/src/runtime/scheduler/multi_thread/park.rs
new file mode 100644
index 000000000..0a00ea004
--- /dev/null
+++ b/vendor/tokio/src/runtime/scheduler/multi_thread/park.rs
@@ -0,0 +1,232 @@
+//! Parks the runtime.
+//!
+//! A combination of the various resource driver park handles.
+
+use crate::loom::sync::atomic::AtomicUsize;
+use crate::loom::sync::{Arc, Condvar, Mutex};
+use crate::runtime::driver::{self, Driver};
+use crate::util::TryLock;
+
+use std::sync::atomic::Ordering::SeqCst;
+use std::time::Duration;
+
+pub(crate) struct Parker {
+    inner: Arc<Inner>,
+}
+
+pub(crate) struct Unparker {
+    inner: Arc<Inner>,
+}
+
+struct Inner {
+    /// Avoids entering the park if possible
+    state: AtomicUsize,
+
+    /// Used to coordinate access to the driver / condvar
+    mutex: Mutex<()>,
+
+    /// Condvar to block on if the driver is unavailable.
+    condvar: Condvar,
+
+    /// Resource (I/O, time, ...) driver
+    shared: Arc<Shared>,
+}
+
+const EMPTY: usize = 0;
+const PARKED_CONDVAR: usize = 1;
+const PARKED_DRIVER: usize = 2;
+const NOTIFIED: usize = 3;
+
+/// Shared across multiple Parker handles
+struct Shared {
+    /// Shared driver. Only one thread at a time can use this
+    driver: TryLock<Driver>,
+}
+
+impl Parker {
+    pub(crate) fn new(driver: Driver) -> Parker {
+        Parker {
+            inner: Arc::new(Inner {
+                state: AtomicUsize::new(EMPTY),
+                mutex: Mutex::new(()),
+                condvar: Condvar::new(),
+                shared: Arc::new(Shared {
+                    driver: TryLock::new(driver),
+                }),
+            }),
+        }
+    }
+
+    pub(crate) fn unpark(&self) -> Unparker {
+        Unparker {
+            inner: self.inner.clone(),
+        }
+    }
+
+    pub(crate) fn park(&mut self, handle: &driver::Handle) {
+        self.inner.park(handle);
+    }
+
+    pub(crate) fn park_timeout(&mut self, handle: &driver::Handle, duration: Duration) {
+        // Only parking with zero is supported...
+        assert_eq!(duration, Duration::from_millis(0));
+
+        if let Some(mut driver) = self.inner.shared.driver.try_lock() {
+            driver.park_timeout(handle, duration)
+        }
+    }
+
+    pub(crate) fn shutdown(&mut self, handle: &driver::Handle) {
+        self.inner.shutdown(handle);
+    }
+}
+
+impl Clone for Parker {
+    fn clone(&self) -> Parker {
+        Parker {
+            inner: Arc::new(Inner {
+                state: AtomicUsize::new(EMPTY),
+                mutex: Mutex::new(()),
+                condvar: Condvar::new(),
+                shared: self.inner.shared.clone(),
+            }),
+        }
+    }
+}
+
+impl Unparker {
+    pub(crate) fn unpark(&self, driver: &driver::Handle) {
+        self.inner.unpark(driver);
+    }
+}
+
+impl Inner {
+    /// Parks the current thread for at most `dur`.
+    fn park(&self, handle: &driver::Handle) {
+        // If we were previously notified then we consume this notification and
+        // return quickly.
+        if self
+            .state
+            .compare_exchange(NOTIFIED, EMPTY, SeqCst, SeqCst)
+            .is_ok()
+        {
+            return;
+        }
+
+        if let Some(mut driver) = self.shared.driver.try_lock() {
+            self.park_driver(&mut driver, handle);
+        } else {
+            self.park_condvar();
+        }
+    }
+
+    fn park_condvar(&self) {
+        // Otherwise we need to coordinate going to sleep
+        let mut m = self.mutex.lock();
+
+        match self
+            .state
+            .compare_exchange(EMPTY, PARKED_CONDVAR, SeqCst, SeqCst)
+        {
+            Ok(_) => {}
+            Err(NOTIFIED) => {
+                // We must read here, even though we know it will be `NOTIFIED`.
+                // This is because `unpark` may have been called again since we read
+                // `NOTIFIED` in the `compare_exchange` above. We must perform an
+                // acquire operation that synchronizes with that `unpark` to observe
+                // any writes it made before the call to unpark. To do that we must
+                // read from the write it made to `state`.
+                let old = self.state.swap(EMPTY, SeqCst);
+                debug_assert_eq!(old, NOTIFIED, "park state changed unexpectedly");
+
+                return;
+            }
+            Err(actual) => panic!("inconsistent park state; actual = {}", actual),
+        }
+
+        loop {
+            m = self.condvar.wait(m).unwrap();
+
+            if self
+                .state
+                .compare_exchange(NOTIFIED, EMPTY, SeqCst, SeqCst)
+                .is_ok()
+            {
+                // got a notification
+                return;
+            }
+
+            // spurious wakeup, go back to sleep
+        }
+    }
+
+    fn park_driver(&self, driver: &mut Driver, handle: &driver::Handle) {
+        match self
+            .state
+            .compare_exchange(EMPTY, PARKED_DRIVER, SeqCst, SeqCst)
+        {
+            Ok(_) => {}
+            Err(NOTIFIED) => {
+                // We must read here, even though we know it will be `NOTIFIED`.
+                // This is because `unpark` may have been called again since we read
+                // `NOTIFIED` in the `compare_exchange` above. We must perform an
+                // acquire operation that synchronizes with that `unpark` to observe
+                // any writes it made before the call to unpark. To do that we must
+                // read from the write it made to `state`.
+                let old = self.state.swap(EMPTY, SeqCst);
+                debug_assert_eq!(old, NOTIFIED, "park state changed unexpectedly");
+
+                return;
+            }
+            Err(actual) => panic!("inconsistent park state; actual = {}", actual),
+        }
+
+        driver.park(handle);
+
+        match self.state.swap(EMPTY, SeqCst) {
+            NOTIFIED => {}      // got a notification, hurray!
+            PARKED_DRIVER => {} // no notification, alas
+            n => panic!("inconsistent park_timeout state: {}", n),
+        }
+    }
+
+    fn unpark(&self, driver: &driver::Handle) {
+        // To ensure the unparked thread will observe any writes we made before
+        // this call, we must perform a release operation that `park` can
+        // synchronize with. To do that we must write `NOTIFIED` even if `state`
+        // is already `NOTIFIED`. That is why this must be a swap rather than a
+        // compare-and-swap that returns if it reads `NOTIFIED` on failure.
+        match self.state.swap(NOTIFIED, SeqCst) {
+            EMPTY => {}    // no one was waiting
+            NOTIFIED => {} // already unparked
+            PARKED_CONDVAR => self.unpark_condvar(),
+            PARKED_DRIVER => driver.unpark(),
+            actual => panic!("inconsistent state in unpark; actual = {}", actual),
+        }
+    }
+
+    fn unpark_condvar(&self) {
+        // There is a period between when the parked thread sets `state` to
+        // `PARKED` (or last checked `state` in the case of a spurious wake
+        // up) and when it actually waits on `cvar`. If we were to notify
+        // during this period it would be ignored and then when the parked
+        // thread went to sleep it would never wake up. Fortunately, it has
+        // `lock` locked at this stage so we can acquire `lock` to wait until
+        // it is ready to receive the notification.
+        //
+        // Releasing `lock` before the call to `notify_one` means that when the
+        // parked thread wakes it doesn't get woken only to have to wait for us
+        // to release `lock`.
+        drop(self.mutex.lock());
+
+        self.condvar.notify_one()
+    }
+
+    fn shutdown(&self, handle: &driver::Handle) {
+        if let Some(mut driver) = self.shared.driver.try_lock() {
+            driver.shutdown(handle);
+        }
+
+        self.condvar.notify_all();
+    }
+}
diff --git a/vendor/tokio/src/runtime/queue.rs b/vendor/tokio/src/runtime/scheduler/multi_thread/queue.rs
index 818ef7bac..dd66fa2dd 100644
--- a/vendor/tokio/src/runtime/queue.rs
+++ b/vendor/tokio/src/runtime/scheduler/multi_thread/queue.rs
@@ -1,72 +1,63 @@
 //! Run-queue structures to support a work-stealing scheduler
 
 use crate::loom::cell::UnsafeCell;
-use crate::loom::sync::atomic::{AtomicU16, AtomicU32, AtomicUsize};
-use crate::loom::sync::{Arc, Mutex};
+use crate::loom::sync::Arc;
+use crate::runtime::scheduler::multi_thread::{Overflow, Stats};
 use crate::runtime::task;
 
-use std::marker::PhantomData;
-use std::mem::MaybeUninit;
-use std::ptr::{self, NonNull};
+use std::mem::{self, MaybeUninit};
+use std::ptr;
 use std::sync::atomic::Ordering::{AcqRel, Acquire, Relaxed, Release};
 
+// Use wider integers when possible to increase ABA resilience.
+//
+// See issue #5041: <https://github.com/tokio-rs/tokio/issues/5041>.
+cfg_has_atomic_u64! {
+    type UnsignedShort = u32;
+    type UnsignedLong = u64;
+    type AtomicUnsignedShort = crate::loom::sync::atomic::AtomicU32;
+    type AtomicUnsignedLong = crate::loom::sync::atomic::AtomicU64;
+}
+cfg_not_has_atomic_u64! {
+    type UnsignedShort = u16;
+    type UnsignedLong = u32;
+    type AtomicUnsignedShort = crate::loom::sync::atomic::AtomicU16;
+    type AtomicUnsignedLong = crate::loom::sync::atomic::AtomicU32;
+}
+
 /// Producer handle. May only be used from a single thread.
-pub(super) struct Local<T: 'static> {
+pub(crate) struct Local<T: 'static> {
     inner: Arc<Inner<T>>,
 }
 
 /// Consumer handle. May be used from many threads.
-pub(super) struct Steal<T: 'static>(Arc<Inner<T>>);
-
-/// Growable, MPMC queue used to inject new tasks into the scheduler and as an
-/// overflow queue when the local, fixed-size, array queue overflows.
-pub(super) struct Inject<T: 'static> {
-    /// Pointers to the head and tail of the queue
-    pointers: Mutex<Pointers>,
-
-    /// Number of pending tasks in the queue. This helps prevent unnecessary
-    /// locking in the hot path.
-    len: AtomicUsize,
+pub(crate) struct Steal<T: 'static>(Arc<Inner<T>>);
 
-    _p: PhantomData<T>,
-}
-
-pub(super) struct Inner<T: 'static> {
+pub(crate) struct Inner<T: 'static> {
     /// Concurrently updated by many threads.
     ///
-    /// Contains two `u16` values. The LSB byte is the "real" head of the queue.
-    /// The `u16` in the MSB is set by a stealer in process of stealing values.
-    /// It represents the first value being stolen in the batch. `u16` is used
-    /// in order to distinguish between `head == tail` and `head == tail -
-    /// capacity`.
+    /// Contains two `UnsignedShort` values. The LSB byte is the "real" head of
+    /// the queue. The `UnsignedShort` in the MSB is set by a stealer in process
+    /// of stealing values. It represents the first value being stolen in the
+    /// batch. The `UnsignedShort` indices are intentionally wider than strictly
+    /// required for buffer indexing in order to provide ABA mitigation and make
+    /// it possible to distinguish between full and empty buffers.
     ///
-    /// When both `u16` values are the same, there is no active stealer.
+    /// When both `UnsignedShort` values are the same, there is no active
+    /// stealer.
     ///
     /// Tracking an in-progress stealer prevents a wrapping scenario.
-    head: AtomicU32,
+    head: AtomicUnsignedLong,
 
     /// Only updated by producer thread but read by many threads.
-    tail: AtomicU16,
+    tail: AtomicUnsignedShort,
 
     /// Elements
-    buffer: Box<[UnsafeCell<MaybeUninit<task::Notified<T>>>]>,
-}
-
-struct Pointers {
-    /// True if the queue is closed
-    is_closed: bool,
-
-    /// Linked-list head
-    head: Option<NonNull<task::Header>>,
-
-    /// Linked-list tail
-    tail: Option<NonNull<task::Header>>,
+    buffer: Box<[UnsafeCell<MaybeUninit<task::Notified<T>>>; LOCAL_QUEUE_CAPACITY]>,
 }
 
 unsafe impl<T> Send for Inner<T> {}
 unsafe impl<T> Sync for Inner<T> {}
-unsafe impl<T> Send for Inject<T> {}
-unsafe impl<T> Sync for Inject<T> {}
 
 #[cfg(not(loom))]
 const LOCAL_QUEUE_CAPACITY: usize = 256;
@@ -79,8 +70,19 @@ const LOCAL_QUEUE_CAPACITY: usize = 4;
 
 const MASK: usize = LOCAL_QUEUE_CAPACITY - 1;
 
+// Constructing the fixed size array directly is very awkward. The only way to
+// do it is to repeat `UnsafeCell::new(MaybeUninit::uninit())` 256 times, as
+// the contents are not Copy. The trick with defining a const doesn't work for
+// generic types.
+fn make_fixed_size<T>(buffer: Box<[T]>) -> Box<[T; LOCAL_QUEUE_CAPACITY]> {
+    assert_eq!(buffer.len(), LOCAL_QUEUE_CAPACITY);
+
+    // safety: We check that the length is correct.
+    unsafe { Box::from_raw(Box::into_raw(buffer).cast()) }
+}
+
 /// Create a new local run-queue
-pub(super) fn local<T: 'static>() -> (Steal<T>, Local<T>) {
+pub(crate) fn local<T: 'static>() -> (Steal<T>, Local<T>) {
     let mut buffer = Vec::with_capacity(LOCAL_QUEUE_CAPACITY);
 
     for _ in 0..LOCAL_QUEUE_CAPACITY {
@@ -88,9 +90,9 @@ pub(super) fn local<T: 'static>() -> (Steal<T>, Local<T>) {
     }
 
     let inner = Arc::new(Inner {
-        head: AtomicU32::new(0),
-        tail: AtomicU16::new(0),
-        buffer: buffer.into(),
+        head: AtomicUnsignedLong::new(0),
+        tail: AtomicUnsignedShort::new(0),
+        buffer: make_fixed_size(buffer.into_boxed_slice()),
     });
 
     let local = Local {
@@ -103,16 +105,89 @@ pub(super) fn local<T: 'static>() -> (Steal<T>, Local<T>) {
 }
 
 impl<T> Local<T> {
-    /// Returns true if the queue has entries that can be stealed.
-    pub(super) fn is_stealable(&self) -> bool {
+    /// Returns the number of entries in the queue
+    pub(crate) fn len(&self) -> usize {
+        self.inner.len() as usize
+    }
+
+    /// How many tasks can be pushed into the queue
+    pub(crate) fn remaining_slots(&self) -> usize {
+        self.inner.remaining_slots()
+    }
+
+    pub(crate) fn max_capacity(&self) -> usize {
+        LOCAL_QUEUE_CAPACITY
+    }
+
+    /// Returns false if there are any entries in the queue
+    ///
+    /// Separate to is_stealable so that refactors of is_stealable to "protect"
+    /// some tasks from stealing won't affect this
+    pub(crate) fn has_tasks(&self) -> bool {
         !self.inner.is_empty()
     }
 
-    /// Pushes a task to the back of the local queue, skipping the LIFO slot.
-    pub(super) fn push_back(&mut self, mut task: task::Notified<T>, inject: &Inject<T>)
-    where
-        T: crate::runtime::task::Schedule,
-    {
+    /// Pushes a batch of tasks to the back of the queue. All tasks must fit in
+    /// the local queue.
+    ///
+    /// # Panics
+    ///
+    /// The method panics if there is not enough capacity to fit in the queue.
+    pub(crate) fn push_back(&mut self, tasks: impl ExactSizeIterator<Item = task::Notified<T>>) {
+        let len = tasks.len();
+        assert!(len <= LOCAL_QUEUE_CAPACITY);
+
+        if len == 0 {
+            // Nothing to do
+            return;
+        }
+
+        let head = self.inner.head.load(Acquire);
+        let (steal, _) = unpack(head);
+
+        // safety: this is the **only** thread that updates this cell.
+        let mut tail = unsafe { self.inner.tail.unsync_load() };
+
+        if tail.wrapping_sub(steal) <= (LOCAL_QUEUE_CAPACITY - len) as UnsignedShort {
+            // Yes, this if condition is structured a bit weird (first block
+            // does nothing, second returns an error). It is this way to match
+            // `push_back_or_overflow`.
+        } else {
+            panic!()
+        }
+
+        for task in tasks {
+            let idx = tail as usize & MASK;
+
+            self.inner.buffer[idx].with_mut(|ptr| {
+                // Write the task to the slot
+                //
+                // Safety: There is only one producer and the above `if`
+                // condition ensures we don't touch a cell if there is a
+                // value, thus no consumer.
+                unsafe {
+                    ptr::write((*ptr).as_mut_ptr(), task);
+                }
+            });
+
+            tail = tail.wrapping_add(1);
+        }
+
+        self.inner.tail.store(tail, Release);
+    }
+
+    /// Pushes a task to the back of the local queue, if there is not enough
+    /// capacity in the queue, this triggers the overflow operation.
+    ///
+    /// When the queue overflows, half of the curent contents of the queue is
+    /// moved to the given Injection queue. This frees up capacity for more
+    /// tasks to be pushed into the local queue.
+    pub(crate) fn push_back_or_overflow<O: Overflow<T>>(
+        &mut self,
+        mut task: task::Notified<T>,
+        overflow: &O,
+        stats: &mut Stats,
+    ) {
         let tail = loop {
             let head = self.inner.head.load(Acquire);
             let (steal, real) = unpack(head);
@@ -120,23 +195,18 @@ impl<T> Local<T> {
             // safety: this is the **only** thread that updates this cell.
             let tail = unsafe { self.inner.tail.unsync_load() };
 
-            if tail.wrapping_sub(steal) < LOCAL_QUEUE_CAPACITY as u16 {
+            if tail.wrapping_sub(steal) < LOCAL_QUEUE_CAPACITY as UnsignedShort {
                 // There is capacity for the task
                 break tail;
             } else if steal != real {
                 // Concurrently stealing, this will free up capacity, so only
-                // push the new task onto the inject queue
-                //
-                // If the task fails to be pushed on the injection queue, there
-                // is nothing to be done at this point as the task cannot be a
-                // newly spawned task. Shutting down this task is handled by the
-                // worker shutdown process.
-                let _ = inject.push(task);
+                // push the task onto the inject queue
+                overflow.push(task);
                 return;
             } else {
                 // Push the current task and half of the queue into the
                 // inject queue.
-                match self.push_overflow(task, real, tail, inject) {
+                match self.push_overflow(task, real, tail, overflow, stats) {
                     Ok(_) => return,
                     // Lost the race, try again
                     Err(v) => {
@@ -146,6 +216,11 @@ impl<T> Local<T> {
             }
         };
 
+        self.push_back_finish(task, tail);
+    }
+
+    // Second half of `push_back`
+    fn push_back_finish(&self, task: task::Notified<T>, tail: UnsignedShort) {
         // Map the position to a slot index.
         let idx = tail as usize & MASK;
 
@@ -172,16 +247,20 @@ impl<T> Local<T> {
     /// workers "missed" some of the tasks during a steal, they will get
     /// another opportunity.
     #[inline(never)]
-    fn push_overflow(
+    fn push_overflow<O: Overflow<T>>(
         &mut self,
         task: task::Notified<T>,
-        head: u16,
-        tail: u16,
-        inject: &Inject<T>,
+        head: UnsignedShort,
+        tail: UnsignedShort,
+        overflow: &O,
+        stats: &mut Stats,
     ) -> Result<(), task::Notified<T>> {
-        const BATCH_LEN: usize = LOCAL_QUEUE_CAPACITY / 2 + 1;
+        /// How many elements are we taking from the local queue.
+        ///
+        /// This is one less than the number of tasks pushed to the inject
+        /// queue as we are also inserting the `task` argument.
+        const NUM_TASKS_TAKEN: UnsignedShort = (LOCAL_QUEUE_CAPACITY / 2) as UnsignedShort;
 
-        let n = (LOCAL_QUEUE_CAPACITY / 2) as u16;
         assert_eq!(
             tail.wrapping_sub(head) as usize,
             LOCAL_QUEUE_CAPACITY,
@@ -207,7 +286,10 @@ impl<T> Local<T> {
             .head
             .compare_exchange(
                 prev,
-                pack(head.wrapping_add(n), head.wrapping_add(n)),
+                pack(
+                    head.wrapping_add(NUM_TASKS_TAKEN),
+                    head.wrapping_add(NUM_TASKS_TAKEN),
+                ),
                 Release,
                 Relaxed,
             )
@@ -219,47 +301,50 @@ impl<T> Local<T> {
             return Err(task);
         }
 
-        // link the tasks
-        for i in 0..n {
-            let j = i + 1;
-
-            let i_idx = i.wrapping_add(head) as usize & MASK;
-            let j_idx = j.wrapping_add(head) as usize & MASK;
-
-            // Get the next pointer
-            let next = if j == n {
-                // The last task in the local queue being moved
-                task.header().into()
-            } else {
-                // safety: The above CAS prevents a stealer from accessing these
-                // tasks and we are the only producer.
-                self.inner.buffer[j_idx].with(|ptr| unsafe {
-                    let value = (*ptr).as_ptr();
-                    (*value).header().into()
-                })
-            };
-
-            // safety: the above CAS prevents a stealer from accessing these
-            // tasks and we are the only producer.
-            self.inner.buffer[i_idx].with_mut(|ptr| unsafe {
-                let ptr = (*ptr).as_ptr();
-                (*ptr).header().set_next(Some(next))
-            });
+        /// An iterator that takes elements out of the run queue.
+        struct BatchTaskIter<'a, T: 'static> {
+            buffer: &'a [UnsafeCell<MaybeUninit<task::Notified<T>>>; LOCAL_QUEUE_CAPACITY],
+            head: UnsignedLong,
+            i: UnsignedLong,
+        }
+        impl<'a, T: 'static> Iterator for BatchTaskIter<'a, T> {
+            type Item = task::Notified<T>;
+
+            #[inline]
+            fn next(&mut self) -> Option<task::Notified<T>> {
+                if self.i == UnsignedLong::from(NUM_TASKS_TAKEN) {
+                    None
+                } else {
+                    let i_idx = self.i.wrapping_add(self.head) as usize & MASK;
+                    let slot = &self.buffer[i_idx];
+
+                    // safety: Our CAS from before has assumed exclusive ownership
+                    // of the task pointers in this range.
+                    let task = slot.with(|ptr| unsafe { ptr::read((*ptr).as_ptr()) });
+
+                    self.i += 1;
+                    Some(task)
+                }
+            }
         }
 
-        // safety: the above CAS prevents a stealer from accessing these tasks
-        // and we are the only producer.
-        let head = self.inner.buffer[head as usize & MASK]
-            .with(|ptr| unsafe { ptr::read((*ptr).as_ptr()) });
+        // safety: The CAS above ensures that no consumer will look at these
+        // values again, and we are the only producer.
+        let batch_iter = BatchTaskIter {
+            buffer: &self.inner.buffer,
+            head: head as UnsignedLong,
+            i: 0,
+        };
+        overflow.push_batch(batch_iter.chain(std::iter::once(task)));
 
-        // Push the tasks onto the inject queue
-        inject.push_batch(head, task, BATCH_LEN);
+        // Add 1 to factor in the task currently being scheduled.
+        stats.incr_overflow_count();
 
         Ok(())
     }
 
     /// Pops a task from the local queue.
-    pub(super) fn pop(&mut self) -> Option<task::Notified<T>> {
+    pub(crate) fn pop(&mut self) -> Option<task::Notified<T>> {
         let mut head = self.inner.head.load(Acquire);
 
         let idx = loop {
@@ -301,12 +386,16 @@ impl<T> Local<T> {
 }
 
 impl<T> Steal<T> {
-    pub(super) fn is_empty(&self) -> bool {
+    pub(crate) fn is_empty(&self) -> bool {
         self.0.is_empty()
     }
 
     /// Steals half the tasks from self and place them into `dst`.
-    pub(super) fn steal_into(&self, dst: &mut Local<T>) -> Option<task::Notified<T>> {
+    pub(crate) fn steal_into(
+        &self,
+        dst: &mut Local<T>,
+        dst_stats: &mut Stats,
+    ) -> Option<task::Notified<T>> {
         // Safety: the caller is the only thread that mutates `dst.tail` and
         // holds a mutable reference.
         let dst_tail = unsafe { dst.inner.tail.unsync_load() };
@@ -316,7 +405,7 @@ impl<T> Steal<T> {
         // from `dst` there may not be enough capacity to steal.
         let (steal, _) = unpack(dst.inner.head.load(Acquire));
 
-        if dst_tail.wrapping_sub(steal) > LOCAL_QUEUE_CAPACITY as u16 / 2 {
+        if dst_tail.wrapping_sub(steal) > LOCAL_QUEUE_CAPACITY as UnsignedShort / 2 {
             // we *could* try to steal less here, but for simplicity, we're just
             // going to abort.
             return None;
@@ -331,6 +420,9 @@ impl<T> Steal<T> {
             return None;
         }
 
+        dst_stats.incr_steal_count(n as u16);
+        dst_stats.incr_steal_operations();
+
         // We are returning a task here
         n -= 1;
 
@@ -354,7 +446,7 @@ impl<T> Steal<T> {
 
     // Steal tasks from `self`, placing them into `dst`. Returns the number of
     // tasks that were stolen.
-    fn steal_into2(&self, dst: &mut Local<T>, dst_tail: u16) -> u16 {
+    fn steal_into2(&self, dst: &mut Local<T>, dst_tail: UnsignedShort) -> UnsignedShort {
         let mut prev_packed = self.0.head.load(Acquire);
         let mut next_packed;
 
@@ -396,7 +488,11 @@ impl<T> Steal<T> {
             }
         };
 
-        assert!(n <= LOCAL_QUEUE_CAPACITY as u16 / 2, "actual = {}", n);
+        assert!(
+            n <= LOCAL_QUEUE_CAPACITY as UnsignedShort / 2,
+            "actual = {}",
+            n
+        );
 
         let (first, _) = unpack(next_packed);
 
@@ -450,6 +546,14 @@ impl<T> Steal<T> {
     }
 }
 
+cfg_metrics! {
+    impl<T> Steal<T> {
+        pub(crate) fn len(&self) -> usize {
+            self.0.len() as _
+        }
+    }
+}
+
 impl<T> Clone for Steal<T> {
     fn clone(&self) -> Steal<T> {
         Steal(self.0.clone())
@@ -465,179 +569,37 @@ impl<T> Drop for Local<T> {
 }
 
 impl<T> Inner<T> {
-    fn is_empty(&self) -> bool {
-        let (_, head) = unpack(self.head.load(Acquire));
+    fn remaining_slots(&self) -> usize {
+        let (steal, _) = unpack(self.head.load(Acquire));
         let tail = self.tail.load(Acquire);
 
-        head == tail
+        LOCAL_QUEUE_CAPACITY - (tail.wrapping_sub(steal) as usize)
     }
-}
 
-impl<T: 'static> Inject<T> {
-    pub(super) fn new() -> Inject<T> {
-        Inject {
-            pointers: Mutex::new(Pointers {
-                is_closed: false,
-                head: None,
-                tail: None,
-            }),
-            len: AtomicUsize::new(0),
-            _p: PhantomData,
-        }
-    }
-
-    pub(super) fn is_empty(&self) -> bool {
-        self.len() == 0
-    }
-
-    /// Close the injection queue, returns `true` if the queue is open when the
-    /// transition is made.
-    pub(super) fn close(&self) -> bool {
-        let mut p = self.pointers.lock();
-
-        if p.is_closed {
-            return false;
-        }
-
-        p.is_closed = true;
-        true
-    }
-
-    pub(super) fn is_closed(&self) -> bool {
-        self.pointers.lock().is_closed
-    }
-
-    pub(super) fn len(&self) -> usize {
-        self.len.load(Acquire)
-    }
-
-    /// Pushes a value into the queue.
-    ///
-    /// Returns `Err(task)` if pushing fails due to the queue being shutdown.
-    /// The caller is expected to call `shutdown()` on the task **if and only
-    /// if** it is a newly spawned task.
-    pub(super) fn push(&self, task: task::Notified<T>) -> Result<(), task::Notified<T>>
-    where
-        T: crate::runtime::task::Schedule,
-    {
-        // Acquire queue lock
-        let mut p = self.pointers.lock();
-
-        if p.is_closed {
-            return Err(task);
-        }
-
-        // safety: only mutated with the lock held
-        let len = unsafe { self.len.unsync_load() };
-        let task = task.into_raw();
-
-        // The next pointer should already be null
-        debug_assert!(get_next(task).is_none());
-
-        if let Some(tail) = p.tail {
-            set_next(tail, Some(task));
-        } else {
-            p.head = Some(task);
-        }
-
-        p.tail = Some(task);
-
-        self.len.store(len + 1, Release);
-        Ok(())
-    }
-
-    pub(super) fn push_batch(
-        &self,
-        batch_head: task::Notified<T>,
-        batch_tail: task::Notified<T>,
-        num: usize,
-    ) {
-        let batch_head = batch_head.into_raw();
-        let batch_tail = batch_tail.into_raw();
-
-        debug_assert!(get_next(batch_tail).is_none());
-
-        let mut p = self.pointers.lock();
-
-        if let Some(tail) = p.tail {
-            set_next(tail, Some(batch_head));
-        } else {
-            p.head = Some(batch_head);
-        }
-
-        p.tail = Some(batch_tail);
-
-        // Increment the count.
-        //
-        // safety: All updates to the len atomic are guarded by the mutex. As
-        // such, a non-atomic load followed by a store is safe.
-        let len = unsafe { self.len.unsync_load() };
-
-        self.len.store(len + num, Release);
-    }
-
-    pub(super) fn pop(&self) -> Option<task::Notified<T>> {
-        // Fast path, if len == 0, then there are no values
-        if self.is_empty() {
-            return None;
-        }
-
-        let mut p = self.pointers.lock();
-
-        // It is possible to hit null here if another thread popped the last
-        // task between us checking `len` and acquiring the lock.
-        let task = p.head?;
-
-        p.head = get_next(task);
-
-        if p.head.is_none() {
-            p.tail = None;
-        }
-
-        set_next(task, None);
-
-        // Decrement the count.
-        //
-        // safety: All updates to the len atomic are guarded by the mutex. As
-        // such, a non-atomic load followed by a store is safe.
-        self.len
-            .store(unsafe { self.len.unsync_load() } - 1, Release);
-
-        // safety: a `Notified` is pushed into the queue and now it is popped!
-        Some(unsafe { task::Notified::from_raw(task) })
-    }
-}
+    fn len(&self) -> UnsignedShort {
+        let (_, head) = unpack(self.head.load(Acquire));
+        let tail = self.tail.load(Acquire);
 
-impl<T: 'static> Drop for Inject<T> {
-    fn drop(&mut self) {
-        if !std::thread::panicking() {
-            assert!(self.pop().is_none(), "queue not empty");
-        }
+        tail.wrapping_sub(head)
     }
-}
 
-fn get_next(header: NonNull<task::Header>) -> Option<NonNull<task::Header>> {
-    unsafe { header.as_ref().queue_next.with(|ptr| *ptr) }
-}
-
-fn set_next(header: NonNull<task::Header>, val: Option<NonNull<task::Header>>) {
-    unsafe {
-        header.as_ref().set_next(val);
+    fn is_empty(&self) -> bool {
+        self.len() == 0
     }
 }
 
 /// Split the head value into the real head and the index a stealer is working
 /// on.
-fn unpack(n: u32) -> (u16, u16) {
-    let real = n & u16::MAX as u32;
-    let steal = n >> 16;
+fn unpack(n: UnsignedLong) -> (UnsignedShort, UnsignedShort) {
+    let real = n & UnsignedShort::MAX as UnsignedLong;
+    let steal = n >> (mem::size_of::<UnsignedShort>() * 8);
 
-    (steal as u16, real as u16)
+    (steal as UnsignedShort, real as UnsignedShort)
 }
 
 /// Join the two head values
-fn pack(steal: u16, real: u16) -> u32 {
-    (real as u32) | ((steal as u32) << 16)
+fn pack(steal: UnsignedShort, real: UnsignedShort) -> UnsignedLong {
+    (real as UnsignedLong) | ((steal as UnsignedLong) << (mem::size_of::<UnsignedShort>() * 8))
 }
 
 #[test]
diff --git a/vendor/tokio/src/runtime/scheduler/multi_thread/stats.rs b/vendor/tokio/src/runtime/scheduler/multi_thread/stats.rs
new file mode 100644
index 000000000..f01daaa1b
--- /dev/null
+++ b/vendor/tokio/src/runtime/scheduler/multi_thread/stats.rs
@@ -0,0 +1,140 @@
+use crate::runtime::{Config, MetricsBatch, WorkerMetrics};
+
+use std::cmp;
+use std::time::{Duration, Instant};
+
+/// Per-worker statistics. This is used for both tuning the scheduler and
+/// reporting runtime-level metrics/stats.
+pub(crate) struct Stats {
+    /// The metrics batch used to report runtime-level metrics/stats to the
+    /// user.
+    batch: MetricsBatch,
+
+    /// Instant at which work last resumed (continued after park).
+    ///
+    /// This duplicates the value stored in `MetricsBatch`. We will unify
+    /// `Stats` and `MetricsBatch` when we stabilize metrics.
+    processing_scheduled_tasks_started_at: Instant,
+
+    /// Number of tasks polled in the batch of scheduled tasks
+    tasks_polled_in_batch: usize,
+
+    /// Exponentially-weighted moving average of time spent polling scheduled a
+    /// task.
+    ///
+    /// Tracked in nanoseconds, stored as a f64 since that is what we use with
+    /// the EWMA calculations
+    task_poll_time_ewma: f64,
+}
+
+/// How to weigh each individual poll time, value is plucked from thin air.
+const TASK_POLL_TIME_EWMA_ALPHA: f64 = 0.1;
+
+/// Ideally, we wouldn't go above this, value is plucked from thin air.
+const TARGET_GLOBAL_QUEUE_INTERVAL: f64 = Duration::from_micros(200).as_nanos() as f64;
+
+/// Max value for the global queue interval. This is 2x the previous default
+const MAX_TASKS_POLLED_PER_GLOBAL_QUEUE_INTERVAL: u32 = 127;
+
+/// This is the previous default
+const TARGET_TASKS_POLLED_PER_GLOBAL_QUEUE_INTERVAL: u32 = 61;
+
+impl Stats {
+    pub(crate) fn new(worker_metrics: &WorkerMetrics) -> Stats {
+        // Seed the value with what we hope to see.
+        let task_poll_time_ewma =
+            TARGET_GLOBAL_QUEUE_INTERVAL / TARGET_TASKS_POLLED_PER_GLOBAL_QUEUE_INTERVAL as f64;
+
+        Stats {
+            batch: MetricsBatch::new(worker_metrics),
+            processing_scheduled_tasks_started_at: Instant::now(),
+            tasks_polled_in_batch: 0,
+            task_poll_time_ewma,
+        }
+    }
+
+    pub(crate) fn tuned_global_queue_interval(&self, config: &Config) -> u32 {
+        // If an interval is explicitly set, don't tune.
+        if let Some(configured) = config.global_queue_interval {
+            return configured;
+        }
+
+        // As of Rust 1.45, casts from f64 -> u32 are saturating, which is fine here.
+        let tasks_per_interval = (TARGET_GLOBAL_QUEUE_INTERVAL / self.task_poll_time_ewma) as u32;
+
+        cmp::max(
+            // We don't want to return less than 2 as that would result in the
+            // global queue always getting checked first.
+            2,
+            cmp::min(
+                MAX_TASKS_POLLED_PER_GLOBAL_QUEUE_INTERVAL,
+                tasks_per_interval,
+            ),
+        )
+    }
+
+    pub(crate) fn submit(&mut self, to: &WorkerMetrics) {
+        self.batch.submit(to);
+    }
+
+    pub(crate) fn about_to_park(&mut self) {
+        self.batch.about_to_park();
+    }
+
+    pub(crate) fn inc_local_schedule_count(&mut self) {
+        self.batch.inc_local_schedule_count();
+    }
+
+    pub(crate) fn start_processing_scheduled_tasks(&mut self) {
+        self.batch.start_processing_scheduled_tasks();
+
+        self.processing_scheduled_tasks_started_at = Instant::now();
+        self.tasks_polled_in_batch = 0;
+    }
+
+    pub(crate) fn end_processing_scheduled_tasks(&mut self) {
+        self.batch.end_processing_scheduled_tasks();
+
+        // Update the EWMA task poll time
+        if self.tasks_polled_in_batch > 0 {
+            let now = Instant::now();
+
+            // If we "overflow" this conversion, we have bigger problems than
+            // slightly off stats.
+            let elapsed = (now - self.processing_scheduled_tasks_started_at).as_nanos() as f64;
+            let num_polls = self.tasks_polled_in_batch as f64;
+
+            // Calculate the mean poll duration for a single task in the batch
+            let mean_poll_duration = elapsed / num_polls;
+
+            // Compute the alpha weighted by the number of tasks polled this batch.
+            let weighted_alpha = 1.0 - (1.0 - TASK_POLL_TIME_EWMA_ALPHA).powf(num_polls);
+
+            // Now compute the new weighted average task poll time.
+            self.task_poll_time_ewma = weighted_alpha * mean_poll_duration
+                + (1.0 - weighted_alpha) * self.task_poll_time_ewma;
+        }
+    }
+
+    pub(crate) fn start_poll(&mut self) {
+        self.batch.start_poll();
+
+        self.tasks_polled_in_batch += 1;
+    }
+
+    pub(crate) fn end_poll(&mut self) {
+        self.batch.end_poll();
+    }
+
+    pub(crate) fn incr_steal_count(&mut self, by: u16) {
+        self.batch.incr_steal_count(by);
+    }
+
+    pub(crate) fn incr_steal_operations(&mut self) {
+        self.batch.incr_steal_operations();
+    }
+
+    pub(crate) fn incr_overflow_count(&mut self) {
+        self.batch.incr_overflow_count();
+    }
+}
diff --git a/vendor/tokio/src/runtime/scheduler/multi_thread/trace.rs b/vendor/tokio/src/runtime/scheduler/multi_thread/trace.rs
new file mode 100644
index 000000000..7b4aeb5c1
--- /dev/null
+++ b/vendor/tokio/src/runtime/scheduler/multi_thread/trace.rs
@@ -0,0 +1,61 @@
+use crate::loom::sync::atomic::{AtomicBool, Ordering};
+use crate::loom::sync::{Barrier, Mutex};
+use crate::runtime::dump::Dump;
+use crate::runtime::scheduler::multi_thread::Handle;
+use crate::sync::notify::Notify;
+
+/// Tracing status of the worker.
+pub(super) struct TraceStatus {
+    pub(super) trace_requested: AtomicBool,
+    pub(super) trace_start: Barrier,
+    pub(super) trace_end: Barrier,
+    pub(super) result_ready: Notify,
+    pub(super) trace_result: Mutex<Option<Dump>>,
+}
+
+impl TraceStatus {
+    pub(super) fn new(remotes_len: usize) -> Self {
+        Self {
+            trace_requested: AtomicBool::new(false),
+            trace_start: Barrier::new(remotes_len),
+            trace_end: Barrier::new(remotes_len),
+            result_ready: Notify::new(),
+            trace_result: Mutex::new(None),
+        }
+    }
+
+    pub(super) fn trace_requested(&self) -> bool {
+        self.trace_requested.load(Ordering::Relaxed)
+    }
+
+    pub(super) async fn start_trace_request(&self, handle: &Handle) {
+        while self
+            .trace_requested
+            .compare_exchange(false, true, Ordering::Acquire, Ordering::Relaxed)
+            .is_err()
+        {
+            handle.notify_all();
+            crate::task::yield_now().await;
+        }
+    }
+
+    pub(super) fn stash_result(&self, dump: Dump) {
+        let _ = self.trace_result.lock().insert(dump);
+        self.result_ready.notify_one();
+    }
+
+    pub(super) fn take_result(&self) -> Option<Dump> {
+        self.trace_result.lock().take()
+    }
+
+    pub(super) async fn end_trace_request(&self, handle: &Handle) {
+        while self
+            .trace_requested
+            .compare_exchange(true, false, Ordering::Acquire, Ordering::Relaxed)
+            .is_err()
+        {
+            handle.notify_all();
+            crate::task::yield_now().await;
+        }
+    }
+}
diff --git a/vendor/tokio/src/runtime/scheduler/multi_thread/trace_mock.rs b/vendor/tokio/src/runtime/scheduler/multi_thread/trace_mock.rs
new file mode 100644
index 000000000..2c17a4e38
--- /dev/null
+++ b/vendor/tokio/src/runtime/scheduler/multi_thread/trace_mock.rs
@@ -0,0 +1,11 @@
+pub(super) struct TraceStatus {}
+
+impl TraceStatus {
+    pub(super) fn new(_: usize) -> Self {
+        Self {}
+    }
+
+    pub(super) fn trace_requested(&self) -> bool {
+        false
+    }
+}
diff --git a/vendor/tokio/src/runtime/scheduler/multi_thread/worker.rs b/vendor/tokio/src/runtime/scheduler/multi_thread/worker.rs
new file mode 100644
index 000000000..6ae114633
--- /dev/null
+++ b/vendor/tokio/src/runtime/scheduler/multi_thread/worker.rs
@@ -0,0 +1,1216 @@
+//! A scheduler is initialized with a fixed number of workers. Each worker is
+//! driven by a thread. Each worker has a "core" which contains data such as the
+//! run queue and other state. When `block_in_place` is called, the worker's
+//! "core" is handed off to a new thread allowing the scheduler to continue to
+//! make progress while the originating thread blocks.
+//!
+//! # Shutdown
+//!
+//! Shutting down the runtime involves the following steps:
+//!
+//!  1. The Shared::close method is called. This closes the inject queue and
+//!     OwnedTasks instance and wakes up all worker threads.
+//!
+//!  2. Each worker thread observes the close signal next time it runs
+//!     Core::maintenance by checking whether the inject queue is closed.
+//!     The Core::is_shutdown flag is set to true.
+//!
+//!  3. The worker thread calls `pre_shutdown` in parallel. Here, the worker
+//!     will keep removing tasks from OwnedTasks until it is empty. No new
+//!     tasks can be pushed to the OwnedTasks during or after this step as it
+//!     was closed in step 1.
+//!
+//!  5. The workers call Shared::shutdown to enter the single-threaded phase of
+//!     shutdown. These calls will push their core to Shared::shutdown_cores,
+//!     and the last thread to push its core will finish the shutdown procedure.
+//!
+//!  6. The local run queue of each core is emptied, then the inject queue is
+//!     emptied.
+//!
+//! At this point, shutdown has completed. It is not possible for any of the
+//! collections to contain any tasks at this point, as each collection was
+//! closed first, then emptied afterwards.
+//!
+//! ## Spawns during shutdown
+//!
+//! When spawning tasks during shutdown, there are two cases:
+//!
+//!  * The spawner observes the OwnedTasks being open, and the inject queue is
+//!    closed.
+//!  * The spawner observes the OwnedTasks being closed and doesn't check the
+//!    inject queue.
+//!
+//! The first case can only happen if the OwnedTasks::bind call happens before
+//! or during step 1 of shutdown. In this case, the runtime will clean up the
+//! task in step 3 of shutdown.
+//!
+//! In the latter case, the task was not spawned and the task is immediately
+//! cancelled by the spawner.
+//!
+//! The correctness of shutdown requires both the inject queue and OwnedTasks
+//! collection to have a closed bit. With a close bit on only the inject queue,
+//! spawning could run in to a situation where a task is successfully bound long
+//! after the runtime has shut down. With a close bit on only the OwnedTasks,
+//! the first spawning situation could result in the notification being pushed
+//! to the inject queue after step 6 of shutdown, which would leave a task in
+//! the inject queue indefinitely. This would be a ref-count cycle and a memory
+//! leak.
+
+use crate::loom::sync::{Arc, Mutex};
+use crate::runtime;
+use crate::runtime::context;
+use crate::runtime::scheduler::multi_thread::{
+    idle, queue, Counters, Handle, Idle, Overflow, Parker, Stats, TraceStatus, Unparker,
+};
+use crate::runtime::scheduler::{inject, Defer, Lock};
+use crate::runtime::task::OwnedTasks;
+use crate::runtime::{
+    blocking, coop, driver, scheduler, task, Config, SchedulerMetrics, WorkerMetrics,
+};
+use crate::util::atomic_cell::AtomicCell;
+use crate::util::rand::{FastRand, RngSeedGenerator};
+
+use std::cell::RefCell;
+use std::task::Waker;
+use std::time::Duration;
+
+cfg_metrics! {
+    mod metrics;
+}
+
+cfg_taskdump! {
+    mod taskdump;
+}
+
+cfg_not_taskdump! {
+    mod taskdump_mock;
+}
+
+/// A scheduler worker
+pub(super) struct Worker {
+    /// Reference to scheduler's handle
+    handle: Arc<Handle>,
+
+    /// Index holding this worker's remote state
+    index: usize,
+
+    /// Used to hand-off a worker's core to another thread.
+    core: AtomicCell<Core>,
+}
+
+/// Core data
+struct Core {
+    /// Used to schedule bookkeeping tasks every so often.
+    tick: u32,
+
+    /// When a task is scheduled from a worker, it is stored in this slot. The
+    /// worker will check this slot for a task **before** checking the run
+    /// queue. This effectively results in the **last** scheduled task to be run
+    /// next (LIFO). This is an optimization for improving locality which
+    /// benefits message passing patterns and helps to reduce latency.
+    lifo_slot: Option<Notified>,
+
+    /// When `true`, locally scheduled tasks go to the LIFO slot. When `false`,
+    /// they go to the back of the `run_queue`.
+    lifo_enabled: bool,
+
+    /// The worker-local run queue.
+    run_queue: queue::Local<Arc<Handle>>,
+
+    /// True if the worker is currently searching for more work. Searching
+    /// involves attempting to steal from other workers.
+    is_searching: bool,
+
+    /// True if the scheduler is being shutdown
+    is_shutdown: bool,
+
+    /// True if the scheduler is being traced
+    is_traced: bool,
+
+    /// Parker
+    ///
+    /// Stored in an `Option` as the parker is added / removed to make the
+    /// borrow checker happy.
+    park: Option<Parker>,
+
+    /// Per-worker runtime stats
+    stats: Stats,
+
+    /// How often to check the global queue
+    global_queue_interval: u32,
+
+    /// Fast random number generator.
+    rand: FastRand,
+}
+
+/// State shared across all workers
+pub(crate) struct Shared {
+    /// Per-worker remote state. All other workers have access to this and is
+    /// how they communicate between each other.
+    remotes: Box<[Remote]>,
+
+    /// Global task queue used for:
+    ///  1. Submit work to the scheduler while **not** currently on a worker thread.
+    ///  2. Submit work to the scheduler when a worker run queue is saturated
+    pub(super) inject: inject::Shared<Arc<Handle>>,
+
+    /// Coordinates idle workers
+    idle: Idle,
+
+    /// Collection of all active tasks spawned onto this executor.
+    pub(super) owned: OwnedTasks<Arc<Handle>>,
+
+    /// Data synchronized by the scheduler mutex
+    pub(super) synced: Mutex<Synced>,
+
+    /// Cores that have observed the shutdown signal
+    ///
+    /// The core is **not** placed back in the worker to avoid it from being
+    /// stolen by a thread that was spawned as part of `block_in_place`.
+    #[allow(clippy::vec_box)] // we're moving an already-boxed value
+    shutdown_cores: Mutex<Vec<Box<Core>>>,
+
+    /// The number of cores that have observed the trace signal.
+    pub(super) trace_status: TraceStatus,
+
+    /// Scheduler configuration options
+    config: Config,
+
+    /// Collects metrics from the runtime.
+    pub(super) scheduler_metrics: SchedulerMetrics,
+
+    pub(super) worker_metrics: Box<[WorkerMetrics]>,
+
+    /// Only held to trigger some code on drop. This is used to get internal
+    /// runtime metrics that can be useful when doing performance
+    /// investigations. This does nothing (empty struct, no drop impl) unless
+    /// the `tokio_internal_mt_counters` cfg flag is set.
+    _counters: Counters,
+}
+
+/// Data synchronized by the scheduler mutex
+pub(crate) struct Synced {
+    /// Synchronized state for `Idle`.
+    pub(super) idle: idle::Synced,
+
+    /// Synchronized state for `Inject`.
+    pub(crate) inject: inject::Synced,
+}
+
+/// Used to communicate with a worker from other threads.
+struct Remote {
+    /// Steals tasks from this worker.
+    pub(super) steal: queue::Steal<Arc<Handle>>,
+
+    /// Unparks the associated worker thread
+    unpark: Unparker,
+}
+
+/// Thread-local context
+pub(crate) struct Context {
+    /// Worker
+    worker: Arc<Worker>,
+
+    /// Core data
+    core: RefCell<Option<Box<Core>>>,
+
+    /// Tasks to wake after resource drivers are polled. This is mostly to
+    /// handle yielded tasks.
+    pub(crate) defer: Defer,
+}
+
+/// Starts the workers
+pub(crate) struct Launch(Vec<Arc<Worker>>);
+
+/// Running a task may consume the core. If the core is still available when
+/// running the task completes, it is returned. Otherwise, the worker will need
+/// to stop processing.
+type RunResult = Result<Box<Core>, ()>;
+
+/// A task handle
+type Task = task::Task<Arc<Handle>>;
+
+/// A notified task handle
+type Notified = task::Notified<Arc<Handle>>;
+
+/// Value picked out of thin-air. Running the LIFO slot a handful of times
+/// seemms sufficient to benefit from locality. More than 3 times probably is
+/// overweighing. The value can be tuned in the future with data that shows
+/// improvements.
+const MAX_LIFO_POLLS_PER_TICK: usize = 3;
+
+pub(super) fn create(
+    size: usize,
+    park: Parker,
+    driver_handle: driver::Handle,
+    blocking_spawner: blocking::Spawner,
+    seed_generator: RngSeedGenerator,
+    config: Config,
+) -> (Arc<Handle>, Launch) {
+    let mut cores = Vec::with_capacity(size);
+    let mut remotes = Vec::with_capacity(size);
+    let mut worker_metrics = Vec::with_capacity(size);
+
+    // Create the local queues
+    for _ in 0..size {
+        let (steal, run_queue) = queue::local();
+
+        let park = park.clone();
+        let unpark = park.unpark();
+        let metrics = WorkerMetrics::from_config(&config);
+        let stats = Stats::new(&metrics);
+
+        cores.push(Box::new(Core {
+            tick: 0,
+            lifo_slot: None,
+            lifo_enabled: !config.disable_lifo_slot,
+            run_queue,
+            is_searching: false,
+            is_shutdown: false,
+            is_traced: false,
+            park: Some(park),
+            global_queue_interval: stats.tuned_global_queue_interval(&config),
+            stats,
+            rand: FastRand::from_seed(config.seed_generator.next_seed()),
+        }));
+
+        remotes.push(Remote { steal, unpark });
+        worker_metrics.push(metrics);
+    }
+
+    let (idle, idle_synced) = Idle::new(size);
+    let (inject, inject_synced) = inject::Shared::new();
+
+    let remotes_len = remotes.len();
+    let handle = Arc::new(Handle {
+        shared: Shared {
+            remotes: remotes.into_boxed_slice(),
+            inject,
+            idle,
+            owned: OwnedTasks::new(),
+            synced: Mutex::new(Synced {
+                idle: idle_synced,
+                inject: inject_synced,
+            }),
+            shutdown_cores: Mutex::new(vec![]),
+            trace_status: TraceStatus::new(remotes_len),
+            config,
+            scheduler_metrics: SchedulerMetrics::new(),
+            worker_metrics: worker_metrics.into_boxed_slice(),
+            _counters: Counters,
+        },
+        driver: driver_handle,
+        blocking_spawner,
+        seed_generator,
+    });
+
+    let mut launch = Launch(vec![]);
+
+    for (index, core) in cores.drain(..).enumerate() {
+        launch.0.push(Arc::new(Worker {
+            handle: handle.clone(),
+            index,
+            core: AtomicCell::new(Some(core)),
+        }));
+    }
+
+    (handle, launch)
+}
+
+#[track_caller]
+pub(crate) fn block_in_place<F, R>(f: F) -> R
+where
+    F: FnOnce() -> R,
+{
+    // Try to steal the worker core back
+    struct Reset {
+        take_core: bool,
+        budget: coop::Budget,
+    }
+
+    impl Drop for Reset {
+        fn drop(&mut self) {
+            with_current(|maybe_cx| {
+                if let Some(cx) = maybe_cx {
+                    if self.take_core {
+                        let core = cx.worker.core.take();
+                        let mut cx_core = cx.core.borrow_mut();
+                        assert!(cx_core.is_none());
+                        *cx_core = core;
+                    }
+
+                    // Reset the task budget as we are re-entering the
+                    // runtime.
+                    coop::set(self.budget);
+                }
+            });
+        }
+    }
+
+    let mut had_entered = false;
+    let mut take_core = false;
+
+    let setup_result = with_current(|maybe_cx| {
+        match (
+            crate::runtime::context::current_enter_context(),
+            maybe_cx.is_some(),
+        ) {
+            (context::EnterRuntime::Entered { .. }, true) => {
+                // We are on a thread pool runtime thread, so we just need to
+                // set up blocking.
+                had_entered = true;
+            }
+            (
+                context::EnterRuntime::Entered {
+                    allow_block_in_place,
+                },
+                false,
+            ) => {
+                // We are on an executor, but _not_ on the thread pool.  That is
+                // _only_ okay if we are in a thread pool runtime's block_on
+                // method:
+                if allow_block_in_place {
+                    had_entered = true;
+                    return Ok(());
+                } else {
+                    // This probably means we are on the current_thread runtime or in a
+                    // LocalSet, where it is _not_ okay to block.
+                    return Err(
+                        "can call blocking only when running on the multi-threaded runtime",
+                    );
+                }
+            }
+            (context::EnterRuntime::NotEntered, true) => {
+                // This is a nested call to block_in_place (we already exited).
+                // All the necessary setup has already been done.
+                return Ok(());
+            }
+            (context::EnterRuntime::NotEntered, false) => {
+                // We are outside of the tokio runtime, so blocking is fine.
+                // We can also skip all of the thread pool blocking setup steps.
+                return Ok(());
+            }
+        }
+
+        let cx = maybe_cx.expect("no .is_some() == false cases above should lead here");
+
+        // Get the worker core. If none is set, then blocking is fine!
+        let core = match cx.core.borrow_mut().take() {
+            Some(core) => core,
+            None => return Ok(()),
+        };
+
+        // We are taking the core from the context and sending it to another
+        // thread.
+        take_core = true;
+
+        // The parker should be set here
+        assert!(core.park.is_some());
+
+        // In order to block, the core must be sent to another thread for
+        // execution.
+        //
+        // First, move the core back into the worker's shared core slot.
+        cx.worker.core.set(core);
+
+        // Next, clone the worker handle and send it to a new thread for
+        // processing.
+        //
+        // Once the blocking task is done executing, we will attempt to
+        // steal the core back.
+        let worker = cx.worker.clone();
+        runtime::spawn_blocking(move || run(worker));
+        Ok(())
+    });
+
+    if let Err(panic_message) = setup_result {
+        panic!("{}", panic_message);
+    }
+
+    if had_entered {
+        // Unset the current task's budget. Blocking sections are not
+        // constrained by task budgets.
+        let _reset = Reset {
+            take_core,
+            budget: coop::stop(),
+        };
+
+        crate::runtime::context::exit_runtime(f)
+    } else {
+        f()
+    }
+}
+
+impl Launch {
+    pub(crate) fn launch(mut self) {
+        for worker in self.0.drain(..) {
+            runtime::spawn_blocking(move || run(worker));
+        }
+    }
+}
+
+fn run(worker: Arc<Worker>) {
+    struct AbortOnPanic;
+
+    impl Drop for AbortOnPanic {
+        fn drop(&mut self) {
+            if std::thread::panicking() {
+                eprintln!("worker thread panicking; aborting process");
+                std::process::abort();
+            }
+        }
+    }
+
+    // Catching panics on worker threads in tests is quite tricky. Instead, when
+    // debug assertions are enabled, we just abort the process.
+    #[cfg(debug_assertions)]
+    let _abort_on_panic = AbortOnPanic;
+
+    // Acquire a core. If this fails, then another thread is running this
+    // worker and there is nothing further to do.
+    let core = match worker.core.take() {
+        Some(core) => core,
+        None => return,
+    };
+
+    let handle = scheduler::Handle::MultiThread(worker.handle.clone());
+
+    crate::runtime::context::enter_runtime(&handle, true, |_| {
+        // Set the worker context.
+        let cx = scheduler::Context::MultiThread(Context {
+            worker,
+            core: RefCell::new(None),
+            defer: Defer::new(),
+        });
+
+        context::set_scheduler(&cx, || {
+            let cx = cx.expect_multi_thread();
+
+            // This should always be an error. It only returns a `Result` to support
+            // using `?` to short circuit.
+            assert!(cx.run(core).is_err());
+
+            // Check if there are any deferred tasks to notify. This can happen when
+            // the worker core is lost due to `block_in_place()` being called from
+            // within the task.
+            cx.defer.wake();
+        });
+    });
+}
+
+impl Context {
+    fn run(&self, mut core: Box<Core>) -> RunResult {
+        // Reset `lifo_enabled` here in case the core was previously stolen from
+        // a task that had the LIFO slot disabled.
+        self.reset_lifo_enabled(&mut core);
+
+        // Start as "processing" tasks as polling tasks from the local queue
+        // will be one of the first things we do.
+        core.stats.start_processing_scheduled_tasks();
+
+        while !core.is_shutdown {
+            self.assert_lifo_enabled_is_correct(&core);
+
+            if core.is_traced {
+                core = self.worker.handle.trace_core(core);
+            }
+
+            // Increment the tick
+            core.tick();
+
+            // Run maintenance, if needed
+            core = self.maintenance(core);
+
+            // First, check work available to the current worker.
+            if let Some(task) = core.next_task(&self.worker) {
+                core = self.run_task(task, core)?;
+                continue;
+            }
+
+            // We consumed all work in the queues and will start searching for work.
+            core.stats.end_processing_scheduled_tasks();
+
+            // There is no more **local** work to process, try to steal work
+            // from other workers.
+            if let Some(task) = core.steal_work(&self.worker) {
+                // Found work, switch back to processing
+                core.stats.start_processing_scheduled_tasks();
+                core = self.run_task(task, core)?;
+            } else {
+                // Wait for work
+                core = if !self.defer.is_empty() {
+                    self.park_timeout(core, Some(Duration::from_millis(0)))
+                } else {
+                    self.park(core)
+                };
+            }
+        }
+
+        core.pre_shutdown(&self.worker);
+
+        // Signal shutdown
+        self.worker.handle.shutdown_core(core);
+        Err(())
+    }
+
+    fn run_task(&self, task: Notified, mut core: Box<Core>) -> RunResult {
+        let task = self.worker.handle.shared.owned.assert_owner(task);
+
+        // Make sure the worker is not in the **searching** state. This enables
+        // another idle worker to try to steal work.
+        core.transition_from_searching(&self.worker);
+
+        self.assert_lifo_enabled_is_correct(&core);
+
+        // Measure the poll start time. Note that we may end up polling other
+        // tasks under this measurement. In this case, the tasks came from the
+        // LIFO slot and are considered part of the current task for scheduling
+        // purposes. These tasks inherent the "parent"'s limits.
+        core.stats.start_poll();
+
+        // Make the core available to the runtime context
+        *self.core.borrow_mut() = Some(core);
+
+        // Run the task
+        coop::budget(|| {
+            task.run();
+            let mut lifo_polls = 0;
+
+            // As long as there is budget remaining and a task exists in the
+            // `lifo_slot`, then keep running.
+            loop {
+                // Check if we still have the core. If not, the core was stolen
+                // by another worker.
+                let mut core = match self.core.borrow_mut().take() {
+                    Some(core) => core,
+                    None => {
+                        // In this case, we cannot call `reset_lifo_enabled()`
+                        // because the core was stolen. The stealer will handle
+                        // that at the top of `Context::run`
+                        return Err(());
+                    }
+                };
+
+                // Check for a task in the LIFO slot
+                let task = match core.lifo_slot.take() {
+                    Some(task) => task,
+                    None => {
+                        self.reset_lifo_enabled(&mut core);
+                        core.stats.end_poll();
+                        return Ok(core);
+                    }
+                };
+
+                if !coop::has_budget_remaining() {
+                    core.stats.end_poll();
+
+                    // Not enough budget left to run the LIFO task, push it to
+                    // the back of the queue and return.
+                    core.run_queue.push_back_or_overflow(
+                        task,
+                        &*self.worker.handle,
+                        &mut core.stats,
+                    );
+                    // If we hit this point, the LIFO slot should be enabled.
+                    // There is no need to reset it.
+                    debug_assert!(core.lifo_enabled);
+                    return Ok(core);
+                }
+
+                // Track that we are about to run a task from the LIFO slot.
+                lifo_polls += 1;
+                super::counters::inc_lifo_schedules();
+
+                // Disable the LIFO slot if we reach our limit
+                //
+                // In ping-ping style workloads where task A notifies task B,
+                // which notifies task A again, continuously prioritizing the
+                // LIFO slot can cause starvation as these two tasks will
+                // repeatedly schedule the other. To mitigate this, we limit the
+                // number of times the LIFO slot is prioritized.
+                if lifo_polls >= MAX_LIFO_POLLS_PER_TICK {
+                    core.lifo_enabled = false;
+                    super::counters::inc_lifo_capped();
+                }
+
+                // Run the LIFO task, then loop
+                *self.core.borrow_mut() = Some(core);
+                let task = self.worker.handle.shared.owned.assert_owner(task);
+                task.run();
+            }
+        })
+    }
+
+    fn reset_lifo_enabled(&self, core: &mut Core) {
+        core.lifo_enabled = !self.worker.handle.shared.config.disable_lifo_slot;
+    }
+
+    fn assert_lifo_enabled_is_correct(&self, core: &Core) {
+        debug_assert_eq!(
+            core.lifo_enabled,
+            !self.worker.handle.shared.config.disable_lifo_slot
+        );
+    }
+
+    fn maintenance(&self, mut core: Box<Core>) -> Box<Core> {
+        if core.tick % self.worker.handle.shared.config.event_interval == 0 {
+            super::counters::inc_num_maintenance();
+
+            core.stats.end_processing_scheduled_tasks();
+
+            // Call `park` with a 0 timeout. This enables the I/O driver, timer, ...
+            // to run without actually putting the thread to sleep.
+            core = self.park_timeout(core, Some(Duration::from_millis(0)));
+
+            // Run regularly scheduled maintenance
+            core.maintenance(&self.worker);
+
+            core.stats.start_processing_scheduled_tasks();
+        }
+
+        core
+    }
+
+    /// Parks the worker thread while waiting for tasks to execute.
+    ///
+    /// This function checks if indeed there's no more work left to be done before parking.
+    /// Also important to notice that, before parking, the worker thread will try to take
+    /// ownership of the Driver (IO/Time) and dispatch any events that might have fired.
+    /// Whenever a worker thread executes the Driver loop, all waken tasks are scheduled
+    /// in its own local queue until the queue saturates (ntasks > LOCAL_QUEUE_CAPACITY).
+    /// When the local queue is saturated, the overflow tasks are added to the injection queue
+    /// from where other workers can pick them up.
+    /// Also, we rely on the workstealing algorithm to spread the tasks amongst workers
+    /// after all the IOs get dispatched
+    fn park(&self, mut core: Box<Core>) -> Box<Core> {
+        if let Some(f) = &self.worker.handle.shared.config.before_park {
+            f();
+        }
+
+        if core.transition_to_parked(&self.worker) {
+            while !core.is_shutdown && !core.is_traced {
+                core.stats.about_to_park();
+                core = self.park_timeout(core, None);
+
+                // Run regularly scheduled maintenance
+                core.maintenance(&self.worker);
+
+                if core.transition_from_parked(&self.worker) {
+                    break;
+                }
+            }
+        }
+
+        if let Some(f) = &self.worker.handle.shared.config.after_unpark {
+            f();
+        }
+        core
+    }
+
+    fn park_timeout(&self, mut core: Box<Core>, duration: Option<Duration>) -> Box<Core> {
+        self.assert_lifo_enabled_is_correct(&core);
+
+        // Take the parker out of core
+        let mut park = core.park.take().expect("park missing");
+
+        // Store `core` in context
+        *self.core.borrow_mut() = Some(core);
+
+        // Park thread
+        if let Some(timeout) = duration {
+            park.park_timeout(&self.worker.handle.driver, timeout);
+        } else {
+            park.park(&self.worker.handle.driver);
+        }
+
+        self.defer.wake();
+
+        // Remove `core` from context
+        core = self.core.borrow_mut().take().expect("core missing");
+
+        // Place `park` back in `core`
+        core.park = Some(park);
+
+        if core.should_notify_others() {
+            self.worker.handle.notify_parked_local();
+        }
+
+        core
+    }
+
+    pub(crate) fn defer(&self, waker: &Waker) {
+        self.defer.defer(waker);
+    }
+}
+
+impl Core {
+    /// Increment the tick
+    fn tick(&mut self) {
+        self.tick = self.tick.wrapping_add(1);
+    }
+
+    /// Return the next notified task available to this worker.
+    fn next_task(&mut self, worker: &Worker) -> Option<Notified> {
+        if self.tick % self.global_queue_interval == 0 {
+            // Update the global queue interval, if needed
+            self.tune_global_queue_interval(worker);
+
+            worker
+                .handle
+                .next_remote_task()
+                .or_else(|| self.next_local_task())
+        } else {
+            let maybe_task = self.next_local_task();
+
+            if maybe_task.is_some() {
+                return maybe_task;
+            }
+
+            if worker.inject().is_empty() {
+                return None;
+            }
+
+            // Other threads can only **remove** tasks from the current worker's
+            // `run_queue`. So, we can be confident that by the time we call
+            // `run_queue.push_back` below, there will be *at least* `cap`
+            // available slots in the queue.
+            let cap = usize::min(
+                self.run_queue.remaining_slots(),
+                self.run_queue.max_capacity() / 2,
+            );
+
+            // The worker is currently idle, pull a batch of work from the
+            // injection queue. We don't want to pull *all* the work so other
+            // workers can also get some.
+            let n = usize::min(
+                worker.inject().len() / worker.handle.shared.remotes.len() + 1,
+                cap,
+            );
+
+            let mut synced = worker.handle.shared.synced.lock();
+            // safety: passing in the correct `inject::Synced`.
+            let mut tasks = unsafe { worker.inject().pop_n(&mut synced.inject, n) };
+
+            // Pop the first task to return immedietly
+            let ret = tasks.next();
+
+            // Push the rest of the on the run queue
+            self.run_queue.push_back(tasks);
+
+            ret
+        }
+    }
+
+    fn next_local_task(&mut self) -> Option<Notified> {
+        self.lifo_slot.take().or_else(|| self.run_queue.pop())
+    }
+
+    /// Function responsible for stealing tasks from another worker
+    ///
+    /// Note: Only if less than half the workers are searching for tasks to steal
+    /// a new worker will actually try to steal. The idea is to make sure not all
+    /// workers will be trying to steal at the same time.
+    fn steal_work(&mut self, worker: &Worker) -> Option<Notified> {
+        if !self.transition_to_searching(worker) {
+            return None;
+        }
+
+        let num = worker.handle.shared.remotes.len();
+        // Start from a random worker
+        let start = self.rand.fastrand_n(num as u32) as usize;
+
+        for i in 0..num {
+            let i = (start + i) % num;
+
+            // Don't steal from ourself! We know we don't have work.
+            if i == worker.index {
+                continue;
+            }
+
+            let target = &worker.handle.shared.remotes[i];
+            if let Some(task) = target
+                .steal
+                .steal_into(&mut self.run_queue, &mut self.stats)
+            {
+                return Some(task);
+            }
+        }
+
+        // Fallback on checking the global queue
+        worker.handle.next_remote_task()
+    }
+
+    fn transition_to_searching(&mut self, worker: &Worker) -> bool {
+        if !self.is_searching {
+            self.is_searching = worker.handle.shared.idle.transition_worker_to_searching();
+        }
+
+        self.is_searching
+    }
+
+    fn transition_from_searching(&mut self, worker: &Worker) {
+        if !self.is_searching {
+            return;
+        }
+
+        self.is_searching = false;
+        worker.handle.transition_worker_from_searching();
+    }
+
+    fn has_tasks(&self) -> bool {
+        self.lifo_slot.is_some() || self.run_queue.has_tasks()
+    }
+
+    fn should_notify_others(&self) -> bool {
+        // If there are tasks available to steal, but this worker is not
+        // looking for tasks to steal, notify another worker.
+        if self.is_searching {
+            return false;
+        }
+        self.lifo_slot.is_some() as usize + self.run_queue.len() > 1
+    }
+
+    /// Prepares the worker state for parking.
+    ///
+    /// Returns true if the transition happened, false if there is work to do first.
+    fn transition_to_parked(&mut self, worker: &Worker) -> bool {
+        // Workers should not park if they have work to do
+        if self.has_tasks() || self.is_traced {
+            return false;
+        }
+
+        // When the final worker transitions **out** of searching to parked, it
+        // must check all the queues one last time in case work materialized
+        // between the last work scan and transitioning out of searching.
+        let is_last_searcher = worker.handle.shared.idle.transition_worker_to_parked(
+            &worker.handle.shared,
+            worker.index,
+            self.is_searching,
+        );
+
+        // The worker is no longer searching. Setting this is the local cache
+        // only.
+        self.is_searching = false;
+
+        if is_last_searcher {
+            worker.handle.notify_if_work_pending();
+        }
+
+        true
+    }
+
+    /// Returns `true` if the transition happened.
+    fn transition_from_parked(&mut self, worker: &Worker) -> bool {
+        // If a task is in the lifo slot/run queue, then we must unpark regardless of
+        // being notified
+        if self.has_tasks() {
+            // When a worker wakes, it should only transition to the "searching"
+            // state when the wake originates from another worker *or* a new task
+            // is pushed. We do *not* want the worker to transition to "searching"
+            // when it wakes when the I/O driver receives new events.
+            self.is_searching = !worker
+                .handle
+                .shared
+                .idle
+                .unpark_worker_by_id(&worker.handle.shared, worker.index);
+            return true;
+        }
+
+        if worker
+            .handle
+            .shared
+            .idle
+            .is_parked(&worker.handle.shared, worker.index)
+        {
+            return false;
+        }
+
+        // When unparked, the worker is in the searching state.
+        self.is_searching = true;
+        true
+    }
+
+    /// Runs maintenance work such as checking the pool's state.
+    fn maintenance(&mut self, worker: &Worker) {
+        self.stats
+            .submit(&worker.handle.shared.worker_metrics[worker.index]);
+
+        if !self.is_shutdown {
+            // Check if the scheduler has been shutdown
+            let synced = worker.handle.shared.synced.lock();
+            self.is_shutdown = worker.inject().is_closed(&synced.inject);
+        }
+
+        if !self.is_traced {
+            // Check if the worker should be tracing.
+            self.is_traced = worker.handle.shared.trace_status.trace_requested();
+        }
+    }
+
+    /// Signals all tasks to shut down, and waits for them to complete. Must run
+    /// before we enter the single-threaded phase of shutdown processing.
+    fn pre_shutdown(&mut self, worker: &Worker) {
+        // Signal to all tasks to shut down.
+        worker.handle.shared.owned.close_and_shutdown_all();
+
+        self.stats
+            .submit(&worker.handle.shared.worker_metrics[worker.index]);
+    }
+
+    /// Shuts down the core.
+    fn shutdown(&mut self, handle: &Handle) {
+        // Take the core
+        let mut park = self.park.take().expect("park missing");
+
+        // Drain the queue
+        while self.next_local_task().is_some() {}
+
+        park.shutdown(&handle.driver);
+    }
+
+    fn tune_global_queue_interval(&mut self, worker: &Worker) {
+        let next = self
+            .stats
+            .tuned_global_queue_interval(&worker.handle.shared.config);
+
+        debug_assert!(next > 1);
+
+        // Smooth out jitter
+        if abs_diff(self.global_queue_interval, next) > 2 {
+            self.global_queue_interval = next;
+        }
+    }
+}
+
+impl Worker {
+    /// Returns a reference to the scheduler's injection queue.
+    fn inject(&self) -> &inject::Shared<Arc<Handle>> {
+        &self.handle.shared.inject
+    }
+}
+
+// TODO: Move `Handle` impls into handle.rs
+impl task::Schedule for Arc<Handle> {
+    fn release(&self, task: &Task) -> Option<Task> {
+        self.shared.owned.remove(task)
+    }
+
+    fn schedule(&self, task: Notified) {
+        self.schedule_task(task, false);
+    }
+
+    fn yield_now(&self, task: Notified) {
+        self.schedule_task(task, true);
+    }
+}
+
+impl Handle {
+    pub(super) fn schedule_task(&self, task: Notified, is_yield: bool) {
+        with_current(|maybe_cx| {
+            if let Some(cx) = maybe_cx {
+                // Make sure the task is part of the **current** scheduler.
+                if self.ptr_eq(&cx.worker.handle) {
+                    // And the current thread still holds a core
+                    if let Some(core) = cx.core.borrow_mut().as_mut() {
+                        self.schedule_local(core, task, is_yield);
+                        return;
+                    }
+                }
+            }
+
+            // Otherwise, use the inject queue.
+            self.push_remote_task(task);
+            self.notify_parked_remote();
+        })
+    }
+
+    fn schedule_local(&self, core: &mut Core, task: Notified, is_yield: bool) {
+        core.stats.inc_local_schedule_count();
+
+        // Spawning from the worker thread. If scheduling a "yield" then the
+        // task must always be pushed to the back of the queue, enabling other
+        // tasks to be executed. If **not** a yield, then there is more
+        // flexibility and the task may go to the front of the queue.
+        let should_notify = if is_yield || !core.lifo_enabled {
+            core.run_queue
+                .push_back_or_overflow(task, self, &mut core.stats);
+            true
+        } else {
+            // Push to the LIFO slot
+            let prev = core.lifo_slot.take();
+            let ret = prev.is_some();
+
+            if let Some(prev) = prev {
+                core.run_queue
+                    .push_back_or_overflow(prev, self, &mut core.stats);
+            }
+
+            core.lifo_slot = Some(task);
+
+            ret
+        };
+
+        // Only notify if not currently parked. If `park` is `None`, then the
+        // scheduling is from a resource driver. As notifications often come in
+        // batches, the notification is delayed until the park is complete.
+        if should_notify && core.park.is_some() {
+            self.notify_parked_local();
+        }
+    }
+
+    fn next_remote_task(&self) -> Option<Notified> {
+        if self.shared.inject.is_empty() {
+            return None;
+        }
+
+        let mut synced = self.shared.synced.lock();
+        // safety: passing in correct `idle::Synced`
+        unsafe { self.shared.inject.pop(&mut synced.inject) }
+    }
+
+    fn push_remote_task(&self, task: Notified) {
+        self.shared.scheduler_metrics.inc_remote_schedule_count();
+
+        let mut synced = self.shared.synced.lock();
+        // safety: passing in correct `idle::Synced`
+        unsafe {
+            self.shared.inject.push(&mut synced.inject, task);
+        }
+    }
+
+    pub(super) fn close(&self) {
+        if self
+            .shared
+            .inject
+            .close(&mut self.shared.synced.lock().inject)
+        {
+            self.notify_all();
+        }
+    }
+
+    fn notify_parked_local(&self) {
+        super::counters::inc_num_inc_notify_local();
+
+        if let Some(index) = self.shared.idle.worker_to_notify(&self.shared) {
+            super::counters::inc_num_unparks_local();
+            self.shared.remotes[index].unpark.unpark(&self.driver);
+        }
+    }
+
+    fn notify_parked_remote(&self) {
+        if let Some(index) = self.shared.idle.worker_to_notify(&self.shared) {
+            self.shared.remotes[index].unpark.unpark(&self.driver);
+        }
+    }
+
+    pub(super) fn notify_all(&self) {
+        for remote in &self.shared.remotes[..] {
+            remote.unpark.unpark(&self.driver);
+        }
+    }
+
+    fn notify_if_work_pending(&self) {
+        for remote in &self.shared.remotes[..] {
+            if !remote.steal.is_empty() {
+                self.notify_parked_local();
+                return;
+            }
+        }
+
+        if !self.shared.inject.is_empty() {
+            self.notify_parked_local();
+        }
+    }
+
+    fn transition_worker_from_searching(&self) {
+        if self.shared.idle.transition_worker_from_searching() {
+            // We are the final searching worker. Because work was found, we
+            // need to notify another worker.
+            self.notify_parked_local();
+        }
+    }
+
+    /// Signals that a worker has observed the shutdown signal and has replaced
+    /// its core back into its handle.
+    ///
+    /// If all workers have reached this point, the final cleanup is performed.
+    fn shutdown_core(&self, core: Box<Core>) {
+        let mut cores = self.shared.shutdown_cores.lock();
+        cores.push(core);
+
+        if cores.len() != self.shared.remotes.len() {
+            return;
+        }
+
+        debug_assert!(self.shared.owned.is_empty());
+
+        for mut core in cores.drain(..) {
+            core.shutdown(self);
+        }
+
+        // Drain the injection queue
+        //
+        // We already shut down every task, so we can simply drop the tasks.
+        while let Some(task) = self.next_remote_task() {
+            drop(task);
+        }
+    }
+
+    fn ptr_eq(&self, other: &Handle) -> bool {
+        std::ptr::eq(self, other)
+    }
+}
+
+impl Overflow<Arc<Handle>> for Handle {
+    fn push(&self, task: task::Notified<Arc<Handle>>) {
+        self.push_remote_task(task);
+    }
+
+    fn push_batch<I>(&self, iter: I)
+    where
+        I: Iterator<Item = task::Notified<Arc<Handle>>>,
+    {
+        unsafe {
+            self.shared.inject.push_batch(self, iter);
+        }
+    }
+}
+
+pub(crate) struct InjectGuard<'a> {
+    lock: crate::loom::sync::MutexGuard<'a, Synced>,
+}
+
+impl<'a> AsMut<inject::Synced> for InjectGuard<'a> {
+    fn as_mut(&mut self) -> &mut inject::Synced {
+        &mut self.lock.inject
+    }
+}
+
+impl<'a> Lock<inject::Synced> for &'a Handle {
+    type Handle = InjectGuard<'a>;
+
+    fn lock(self) -> Self::Handle {
+        InjectGuard {
+            lock: self.shared.synced.lock(),
+        }
+    }
+}
+
+#[track_caller]
+fn with_current<R>(f: impl FnOnce(Option<&Context>) -> R) -> R {
+    use scheduler::Context::MultiThread;
+
+    context::with_scheduler(|ctx| match ctx {
+        Some(MultiThread(ctx)) => f(Some(ctx)),
+        _ => f(None),
+    })
+}
+
+// `u32::abs_diff` is not available on Tokio's MSRV.
+fn abs_diff(a: u32, b: u32) -> u32 {
+    if a > b {
+        a - b
+    } else {
+        b - a
+    }
+}
diff --git a/vendor/tokio/src/runtime/scheduler/multi_thread/worker/metrics.rs b/vendor/tokio/src/runtime/scheduler/multi_thread/worker/metrics.rs
new file mode 100644
index 000000000..a9a5ab3ed
--- /dev/null
+++ b/vendor/tokio/src/runtime/scheduler/multi_thread/worker/metrics.rs
@@ -0,0 +1,11 @@
+use super::Shared;
+
+impl Shared {
+    pub(crate) fn injection_queue_depth(&self) -> usize {
+        self.inject.len()
+    }
+
+    pub(crate) fn worker_local_queue_depth(&self, worker: usize) -> usize {
+        self.remotes[worker].steal.len()
+    }
+}
diff --git a/vendor/tokio/src/runtime/scheduler/multi_thread/worker/taskdump.rs b/vendor/tokio/src/runtime/scheduler/multi_thread/worker/taskdump.rs
new file mode 100644
index 000000000..d310d9f6d
--- /dev/null
+++ b/vendor/tokio/src/runtime/scheduler/multi_thread/worker/taskdump.rs
@@ -0,0 +1,79 @@
+use super::{Core, Handle, Shared};
+
+use crate::loom::sync::Arc;
+use crate::runtime::scheduler::multi_thread::Stats;
+use crate::runtime::task::trace::trace_multi_thread;
+use crate::runtime::{dump, WorkerMetrics};
+
+use std::time::Duration;
+
+impl Handle {
+    pub(super) fn trace_core(&self, mut core: Box<Core>) -> Box<Core> {
+        core.is_traced = false;
+
+        if core.is_shutdown {
+            return core;
+        }
+
+        // wait for other workers, or timeout without tracing
+        let timeout = Duration::from_millis(250); // a _very_ generous timeout
+        let barrier =
+            if let Some(barrier) = self.shared.trace_status.trace_start.wait_timeout(timeout) {
+                barrier
+            } else {
+                // don't attempt to trace
+                return core;
+            };
+
+        if !barrier.is_leader() {
+            // wait for leader to finish tracing
+            self.shared.trace_status.trace_end.wait();
+            return core;
+        }
+
+        // trace
+
+        let owned = &self.shared.owned;
+        let mut local = self.shared.steal_all();
+        let synced = &self.shared.synced;
+        let injection = &self.shared.inject;
+
+        // safety: `trace_multi_thread` is invoked with the same `synced` that `injection`
+        // was created with.
+        let traces = unsafe { trace_multi_thread(owned, &mut local, synced, injection) }
+            .into_iter()
+            .map(dump::Task::new)
+            .collect();
+
+        let result = dump::Dump::new(traces);
+
+        // stash the result
+        self.shared.trace_status.stash_result(result);
+
+        // allow other workers to proceed
+        self.shared.trace_status.trace_end.wait();
+
+        core
+    }
+}
+
+impl Shared {
+    /// Steal all tasks from remotes into a single local queue.
+    pub(super) fn steal_all(&self) -> super::queue::Local<Arc<Handle>> {
+        let (_steal, mut local) = super::queue::local();
+
+        let worker_metrics = WorkerMetrics::new();
+        let mut stats = Stats::new(&worker_metrics);
+
+        for remote in self.remotes.iter() {
+            let steal = &remote.steal;
+            while !steal.is_empty() {
+                if let Some(task) = steal.steal_into(&mut local, &mut stats) {
+                    local.push_back([task].into_iter());
+                }
+            }
+        }
+
+        local
+    }
+}
diff --git a/vendor/tokio/src/runtime/scheduler/multi_thread/worker/taskdump_mock.rs b/vendor/tokio/src/runtime/scheduler/multi_thread/worker/taskdump_mock.rs
new file mode 100644
index 000000000..24c5600ce
--- /dev/null
+++ b/vendor/tokio/src/runtime/scheduler/multi_thread/worker/taskdump_mock.rs
@@ -0,0 +1,7 @@
+use super::{Core, Handle};
+
+impl Handle {
+    pub(super) fn trace_core(&self, core: Box<Core>) -> Box<Core> {
+        core
+    }
+}
diff --git a/vendor/tokio/src/runtime/signal/mod.rs b/vendor/tokio/src/runtime/signal/mod.rs
new file mode 100644
index 000000000..24f2f4c6c
--- /dev/null
+++ b/vendor/tokio/src/runtime/signal/mod.rs
@@ -0,0 +1,142 @@
+#![cfg_attr(not(feature = "rt"), allow(dead_code))]
+
+//! Signal driver
+
+use crate::runtime::{driver, io};
+use crate::signal::registry::globals;
+
+use mio::net::UnixStream;
+use std::io::{self as std_io, Read};
+use std::sync::{Arc, Weak};
+use std::time::Duration;
+
+/// Responsible for registering wakeups when an OS signal is received, and
+/// subsequently dispatching notifications to any signal listeners as appropriate.
+///
+/// Note: this driver relies on having an enabled IO driver in order to listen to
+/// pipe write wakeups.
+#[derive(Debug)]
+pub(crate) struct Driver {
+    /// Thread parker. The `Driver` park implementation delegates to this.
+    io: io::Driver,
+
+    /// A pipe for receiving wake events from the signal handler
+    receiver: UnixStream,
+
+    /// Shared state. The driver keeps a strong ref and the handle keeps a weak
+    /// ref. The weak ref is used to check if the driver is still active before
+    /// trying to register a signal handler.
+    inner: Arc<()>,
+}
+
+#[derive(Debug, Default)]
+pub(crate) struct Handle {
+    /// Paired w/ the `Arc` above and is used to check if the driver is still
+    /// around before attempting to register a signal handler.
+    inner: Weak<()>,
+}
+
+// ===== impl Driver =====
+
+impl Driver {
+    /// Creates a new signal `Driver` instance that delegates wakeups to `park`.
+    pub(crate) fn new(io: io::Driver, io_handle: &io::Handle) -> std_io::Result<Self> {
+        use std::mem::ManuallyDrop;
+        use std::os::unix::io::{AsRawFd, FromRawFd};
+
+        // NB: We give each driver a "fresh" receiver file descriptor to avoid
+        // the issues described in alexcrichton/tokio-process#42.
+        //
+        // In the past we would reuse the actual receiver file descriptor and
+        // swallow any errors around double registration of the same descriptor.
+        // I'm not sure if the second (failed) registration simply doesn't end
+        // up receiving wake up notifications, or there could be some race
+        // condition when consuming readiness events, but having distinct
+        // descriptors appears to mitigate this.
+        //
+        // Unfortunately we cannot just use a single global UnixStream instance
+        // either, since we can't assume they will always be registered with the
+        // exact same reactor.
+        //
+        // Mio 0.7 removed `try_clone()` as an API due to unexpected behavior
+        // with registering dups with the same reactor. In this case, duping is
+        // safe as each dup is registered with separate reactors **and** we
+        // only expect at least one dup to receive the notification.
+
+        // Manually drop as we don't actually own this instance of UnixStream.
+        let receiver_fd = globals().receiver.as_raw_fd();
+
+        // safety: there is nothing unsafe about this, but the `from_raw_fd` fn is marked as unsafe.
+        let original =
+            ManuallyDrop::new(unsafe { std::os::unix::net::UnixStream::from_raw_fd(receiver_fd) });
+        let mut receiver = UnixStream::from_std(original.try_clone()?);
+
+        io_handle.register_signal_receiver(&mut receiver)?;
+
+        Ok(Self {
+            io,
+            receiver,
+            inner: Arc::new(()),
+        })
+    }
+
+    /// Returns a handle to this event loop which can be sent across threads
+    /// and can be used as a proxy to the event loop itself.
+    pub(crate) fn handle(&self) -> Handle {
+        Handle {
+            inner: Arc::downgrade(&self.inner),
+        }
+    }
+
+    pub(crate) fn park(&mut self, handle: &driver::Handle) {
+        self.io.park(handle);
+        self.process();
+    }
+
+    pub(crate) fn park_timeout(&mut self, handle: &driver::Handle, duration: Duration) {
+        self.io.park_timeout(handle, duration);
+        self.process();
+    }
+
+    pub(crate) fn shutdown(&mut self, handle: &driver::Handle) {
+        self.io.shutdown(handle)
+    }
+
+    fn process(&mut self) {
+        // If the signal pipe has not received a readiness event, then there is
+        // nothing else to do.
+        if !self.io.consume_signal_ready() {
+            return;
+        }
+
+        // Drain the pipe completely so we can receive a new readiness event
+        // if another signal has come in.
+        let mut buf = [0; 128];
+        loop {
+            match self.receiver.read(&mut buf) {
+                Ok(0) => panic!("EOF on self-pipe"),
+                Ok(_) => continue, // Keep reading
+                Err(e) if e.kind() == std_io::ErrorKind::WouldBlock => break,
+                Err(e) => panic!("Bad read on self-pipe: {}", e),
+            }
+        }
+
+        // Broadcast any signals which were received
+        globals().broadcast();
+    }
+}
+
+// ===== impl Handle =====
+
+impl Handle {
+    pub(crate) fn check_inner(&self) -> std_io::Result<()> {
+        if self.inner.strong_count() > 0 {
+            Ok(())
+        } else {
+            Err(std_io::Error::new(
+                std_io::ErrorKind::Other,
+                "signal driver gone",
+            ))
+        }
+    }
+}
diff --git a/vendor/tokio/src/runtime/spawner.rs b/vendor/tokio/src/runtime/spawner.rs
deleted file mode 100644
index fbcde2cfa..000000000
--- a/vendor/tokio/src/runtime/spawner.rs
+++ /dev/null
@@ -1,45 +0,0 @@
-cfg_rt! {
-    use crate::future::Future;
-    use crate::runtime::basic_scheduler;
-    use crate::task::JoinHandle;
-}
-
-cfg_rt_multi_thread! {
-    use crate::runtime::thread_pool;
-}
-
-#[derive(Debug, Clone)]
-pub(crate) enum Spawner {
-    #[cfg(feature = "rt")]
-    Basic(basic_scheduler::Spawner),
-    #[cfg(feature = "rt-multi-thread")]
-    ThreadPool(thread_pool::Spawner),
-}
-
-impl Spawner {
-    pub(crate) fn shutdown(&mut self) {
-        #[cfg(feature = "rt-multi-thread")]
-        {
-            if let Spawner::ThreadPool(spawner) = self {
-                spawner.shutdown();
-            }
-        }
-    }
-}
-
-cfg_rt! {
-    impl Spawner {
-        pub(crate) fn spawn<F>(&self, future: F) -> JoinHandle<F::Output>
-        where
-            F: Future + Send + 'static,
-            F::Output: Send + 'static,
-        {
-            match self {
-                #[cfg(feature = "rt")]
-                Spawner::Basic(spawner) => spawner.spawn(future),
-                #[cfg(feature = "rt-multi-thread")]
-                Spawner::ThreadPool(spawner) => spawner.spawn(future),
-            }
-        }
-    }
-}
diff --git a/vendor/tokio/src/runtime/task/abort.rs b/vendor/tokio/src/runtime/task/abort.rs
new file mode 100644
index 000000000..6edca1004
--- /dev/null
+++ b/vendor/tokio/src/runtime/task/abort.rs
@@ -0,0 +1,87 @@
+use crate::runtime::task::{Header, RawTask};
+use std::fmt;
+use std::panic::{RefUnwindSafe, UnwindSafe};
+
+/// An owned permission to abort a spawned task, without awaiting its completion.
+///
+/// Unlike a [`JoinHandle`], an `AbortHandle` does *not* represent the
+/// permission to await the task's completion, only to terminate it.
+///
+/// The task may be aborted by calling the [`AbortHandle::abort`] method.
+/// Dropping an `AbortHandle` releases the permission to terminate the task
+/// --- it does *not* abort the task.
+///
+/// [`JoinHandle`]: crate::task::JoinHandle
+#[cfg_attr(docsrs, doc(cfg(feature = "rt")))]
+pub struct AbortHandle {
+    raw: RawTask,
+}
+
+impl AbortHandle {
+    pub(super) fn new(raw: RawTask) -> Self {
+        Self { raw }
+    }
+
+    /// Abort the task associated with the handle.
+    ///
+    /// Awaiting a cancelled task might complete as usual if the task was
+    /// already completed at the time it was cancelled, but most likely it
+    /// will fail with a [cancelled] `JoinError`.
+    ///
+    /// If the task was already cancelled, such as by [`JoinHandle::abort`],
+    /// this method will do nothing.
+    ///
+    /// [cancelled]: method@super::error::JoinError::is_cancelled
+    /// [`JoinHandle::abort`]: method@super::JoinHandle::abort
+    pub fn abort(&self) {
+        self.raw.remote_abort();
+    }
+
+    /// Checks if the task associated with this `AbortHandle` has finished.
+    ///
+    /// Please note that this method can return `false` even if `abort` has been
+    /// called on the task. This is because the cancellation process may take
+    /// some time, and this method does not return `true` until it has
+    /// completed.
+    pub fn is_finished(&self) -> bool {
+        let state = self.raw.state().load();
+        state.is_complete()
+    }
+
+    /// Returns a [task ID] that uniquely identifies this task relative to other
+    /// currently spawned tasks.
+    ///
+    /// **Note**: This is an [unstable API][unstable]. The public API of this type
+    /// may break in 1.x releases. See [the documentation on unstable
+    /// features][unstable] for details.
+    ///
+    /// [task ID]: crate::task::Id
+    /// [unstable]: crate#unstable-features
+    #[cfg(tokio_unstable)]
+    #[cfg_attr(docsrs, doc(cfg(tokio_unstable)))]
+    pub fn id(&self) -> super::Id {
+        // Safety: The header pointer is valid.
+        unsafe { Header::get_id(self.raw.header_ptr()) }
+    }
+}
+
+unsafe impl Send for AbortHandle {}
+unsafe impl Sync for AbortHandle {}
+
+impl UnwindSafe for AbortHandle {}
+impl RefUnwindSafe for AbortHandle {}
+
+impl fmt::Debug for AbortHandle {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        // Safety: The header pointer is valid.
+        let id_ptr = unsafe { Header::get_id_ptr(self.raw.header_ptr()) };
+        let id = unsafe { id_ptr.as_ref() };
+        fmt.debug_struct("AbortHandle").field("id", id).finish()
+    }
+}
+
+impl Drop for AbortHandle {
+    fn drop(&mut self) {
+        self.raw.drop_abort_handle();
+    }
+}
diff --git a/vendor/tokio/src/runtime/task/core.rs b/vendor/tokio/src/runtime/task/core.rs
index 428c921fe..110933e58 100644
--- a/vendor/tokio/src/runtime/task/core.rs
+++ b/vendor/tokio/src/runtime/task/core.rs
@@ -11,9 +11,10 @@
 
 use crate::future::Future;
 use crate::loom::cell::UnsafeCell;
+use crate::runtime::context;
 use crate::runtime::task::raw::{self, Vtable};
 use crate::runtime::task::state::State;
-use crate::runtime::task::{Notified, Schedule, Task};
+use crate::runtime::task::{Id, Schedule};
 use crate::util::linked_list;
 
 use std::pin::Pin;
@@ -24,6 +25,97 @@ use std::task::{Context, Poll, Waker};
 ///
 /// It is critical for `Header` to be the first field as the task structure will
 /// be referenced by both *mut Cell and *mut Header.
+///
+/// Any changes to the layout of this struct _must_ also be reflected in the
+/// const fns in raw.rs.
+///
+// # This struct should be cache padded to avoid false sharing. The cache padding rules are copied
+// from crossbeam-utils/src/cache_padded.rs
+//
+// Starting from Intel's Sandy Bridge, spatial prefetcher is now pulling pairs of 64-byte cache
+// lines at a time, so we have to align to 128 bytes rather than 64.
+//
+// Sources:
+// - https://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-optimization-manual.pdf
+// - https://github.com/facebook/folly/blob/1b5288e6eea6df074758f877c849b6e73bbb9fbb/folly/lang/Align.h#L107
+//
+// ARM's big.LITTLE architecture has asymmetric cores and "big" cores have 128-byte cache line size.
+//
+// Sources:
+// - https://www.mono-project.com/news/2016/09/12/arm64-icache/
+//
+// powerpc64 has 128-byte cache line size.
+//
+// Sources:
+// - https://github.com/golang/go/blob/3dd58676054223962cd915bb0934d1f9f489d4d2/src/internal/cpu/cpu_ppc64x.go#L9
+#[cfg_attr(
+    any(
+        target_arch = "x86_64",
+        target_arch = "aarch64",
+        target_arch = "powerpc64",
+    ),
+    repr(align(128))
+)]
+// arm, mips, mips64, riscv64, sparc, and hexagon have 32-byte cache line size.
+//
+// Sources:
+// - https://github.com/golang/go/blob/3dd58676054223962cd915bb0934d1f9f489d4d2/src/internal/cpu/cpu_arm.go#L7
+// - https://github.com/golang/go/blob/3dd58676054223962cd915bb0934d1f9f489d4d2/src/internal/cpu/cpu_mips.go#L7
+// - https://github.com/golang/go/blob/3dd58676054223962cd915bb0934d1f9f489d4d2/src/internal/cpu/cpu_mipsle.go#L7
+// - https://github.com/golang/go/blob/3dd58676054223962cd915bb0934d1f9f489d4d2/src/internal/cpu/cpu_mips64x.go#L9
+// - https://github.com/golang/go/blob/3dd58676054223962cd915bb0934d1f9f489d4d2/src/internal/cpu/cpu_riscv64.go#L7
+// - https://github.com/torvalds/linux/blob/3516bd729358a2a9b090c1905bd2a3fa926e24c6/arch/sparc/include/asm/cache.h#L17
+// - https://github.com/torvalds/linux/blob/3516bd729358a2a9b090c1905bd2a3fa926e24c6/arch/hexagon/include/asm/cache.h#L12
+//
+// riscv32 is assumed not to exceed the cache line size of riscv64.
+#[cfg_attr(
+    any(
+        target_arch = "arm",
+        target_arch = "mips",
+        target_arch = "mips64",
+        target_arch = "riscv32",
+        target_arch = "riscv64",
+        target_arch = "sparc",
+        target_arch = "hexagon",
+    ),
+    repr(align(32))
+)]
+// m68k has 16-byte cache line size.
+//
+// Sources:
+// - https://github.com/torvalds/linux/blob/3516bd729358a2a9b090c1905bd2a3fa926e24c6/arch/m68k/include/asm/cache.h#L9
+#[cfg_attr(target_arch = "m68k", repr(align(16)))]
+// s390x has 256-byte cache line size.
+//
+// Sources:
+// - https://github.com/golang/go/blob/3dd58676054223962cd915bb0934d1f9f489d4d2/src/internal/cpu/cpu_s390x.go#L7
+// - https://github.com/torvalds/linux/blob/3516bd729358a2a9b090c1905bd2a3fa926e24c6/arch/s390/include/asm/cache.h#L13
+#[cfg_attr(target_arch = "s390x", repr(align(256)))]
+// x86, wasm, and sparc64 have 64-byte cache line size.
+//
+// Sources:
+// - https://github.com/golang/go/blob/dda2991c2ea0c5914714469c4defc2562a907230/src/internal/cpu/cpu_x86.go#L9
+// - https://github.com/golang/go/blob/3dd58676054223962cd915bb0934d1f9f489d4d2/src/internal/cpu/cpu_wasm.go#L7
+// - https://github.com/torvalds/linux/blob/3516bd729358a2a9b090c1905bd2a3fa926e24c6/arch/sparc/include/asm/cache.h#L19
+//
+// All others are assumed to have 64-byte cache line size.
+#[cfg_attr(
+    not(any(
+        target_arch = "x86_64",
+        target_arch = "aarch64",
+        target_arch = "powerpc64",
+        target_arch = "arm",
+        target_arch = "mips",
+        target_arch = "mips64",
+        target_arch = "riscv32",
+        target_arch = "riscv64",
+        target_arch = "sparc",
+        target_arch = "hexagon",
+        target_arch = "m68k",
+        target_arch = "s390x",
+    )),
+    repr(align(64))
+)]
 #[repr(C)]
 pub(super) struct Cell<T: Future, S> {
     /// Hot task state data
@@ -36,10 +128,6 @@ pub(super) struct Cell<T: Future, S> {
     pub(super) trailer: Trailer,
 }
 
-pub(super) struct Scheduler<S> {
-    scheduler: UnsafeCell<Option<S>>,
-}
-
 pub(super) struct CoreStage<T: Future> {
     stage: UnsafeCell<Stage<T>>,
 }
@@ -47,45 +135,71 @@ pub(super) struct CoreStage<T: Future> {
 /// The core of the task.
 ///
 /// Holds the future or output, depending on the stage of execution.
+///
+/// Any changes to the layout of this struct _must_ also be reflected in the
+/// const fns in raw.rs.
+#[repr(C)]
 pub(super) struct Core<T: Future, S> {
-    /// Scheduler used to drive this future
-    pub(super) scheduler: Scheduler<S>,
+    /// Scheduler used to drive this future.
+    pub(super) scheduler: S,
+
+    /// The task's ID, used for populating `JoinError`s.
+    pub(super) task_id: Id,
 
-    /// Either the future or the output
+    /// Either the future or the output.
     pub(super) stage: CoreStage<T>,
 }
 
 /// Crate public as this is also needed by the pool.
 #[repr(C)]
 pub(crate) struct Header {
-    /// Task state
+    /// Task state.
     pub(super) state: State,
 
-    pub(crate) owned: UnsafeCell<linked_list::Pointers<Header>>,
-
-    /// Pointer to next task, used with the injection queue
-    pub(crate) queue_next: UnsafeCell<Option<NonNull<Header>>>,
-
-    /// Pointer to the next task in the transfer stack
-    pub(super) stack_next: UnsafeCell<Option<NonNull<Header>>>,
+    /// Pointer to next task, used with the injection queue.
+    pub(super) queue_next: UnsafeCell<Option<NonNull<Header>>>,
 
     /// Table of function pointers for executing actions on the task.
     pub(super) vtable: &'static Vtable,
 
+    /// This integer contains the id of the OwnedTasks or LocalOwnedTasks that
+    /// this task is stored in. If the task is not in any list, should be the
+    /// id of the list that it was previously in, or zero if it has never been
+    /// in any list.
+    ///
+    /// Once a task has been bound to a list, it can never be bound to another
+    /// list, even if removed from the first list.
+    ///
+    /// The id is not unset when removed from a list because we want to be able
+    /// to read the id without synchronization, even if it is concurrently being
+    /// removed from the list.
+    pub(super) owner_id: UnsafeCell<u64>,
+
     /// The tracing ID for this instrumented task.
     #[cfg(all(tokio_unstable, feature = "tracing"))]
-    pub(super) id: Option<tracing::Id>,
+    pub(super) tracing_id: Option<tracing::Id>,
 }
 
 unsafe impl Send for Header {}
 unsafe impl Sync for Header {}
 
-/// Cold data is stored after the future.
+/// Cold data is stored after the future. Data is considered cold if it is only
+/// used during creation or shutdown of the task.
 pub(super) struct Trailer {
+    /// Pointers for the linked list in the `OwnedTasks` that owns this task.
+    pub(super) owned: linked_list::Pointers<Header>,
     /// Consumer task waiting on completion of this task.
     pub(super) waker: UnsafeCell<Option<Waker>>,
 }
 
+generate_addr_of_methods! {
+    impl<> Trailer {
+        pub(super) unsafe fn addr_of_owned(self: NonNull<Self>) -> NonNull<linked_list::Pointers<Header>> {
+            &self.owned
+        }
+    }
+}
+
 /// Either the future or the output.
 pub(super) enum Stage<T: Future> {
     Running(T),
@@ -96,117 +210,48 @@ pub(super) enum Stage<T: Future> {
 impl<T: Future, S: Schedule> Cell<T, S> {
     /// Allocates a new task cell, containing the header, trailer, and core
     /// structures.
-    pub(super) fn new(future: T, state: State) -> Box<Cell<T, S>> {
+    pub(super) fn new(future: T, scheduler: S, state: State, task_id: Id) -> Box<Cell<T, S>> {
         #[cfg(all(tokio_unstable, feature = "tracing"))]
-        let id = future.id();
-        Box::new(Cell {
+        let tracing_id = future.id();
+        let result = Box::new(Cell {
             header: Header {
                 state,
-                owned: UnsafeCell::new(linked_list::Pointers::new()),
                 queue_next: UnsafeCell::new(None),
-                stack_next: UnsafeCell::new(None),
                 vtable: raw::vtable::<T, S>(),
+                owner_id: UnsafeCell::new(0),
                 #[cfg(all(tokio_unstable, feature = "tracing"))]
-                id,
+                tracing_id,
             },
             core: Core {
-                scheduler: Scheduler {
-                    scheduler: UnsafeCell::new(None),
-                },
+                scheduler,
                 stage: CoreStage {
                     stage: UnsafeCell::new(Stage::Running(future)),
                 },
+                task_id,
             },
             trailer: Trailer {
                 waker: UnsafeCell::new(None),
+                owned: linked_list::Pointers::new(),
             },
-        })
-    }
-}
-
-impl<S: Schedule> Scheduler<S> {
-    pub(super) fn with_mut<R>(&self, f: impl FnOnce(*mut Option<S>) -> R) -> R {
-        self.scheduler.with_mut(f)
-    }
-
-    /// Bind a scheduler to the task.
-    ///
-    /// This only happens on the first poll and must be preceded by a call to
-    /// `is_bound` to determine if binding is appropriate or not.
-    ///
-    /// # Safety
-    ///
-    /// Binding must not be done concurrently since it will mutate the task
-    /// core through a shared reference.
-    pub(super) fn bind_scheduler(&self, task: Task<S>) {
-        // This function may be called concurrently, but the __first__ time it
-        // is called, the caller has unique access to this field. All subsequent
-        // concurrent calls will be via the `Waker`, which will "happens after"
-        // the first poll.
-        //
-        // In other words, it is always safe to read the field and it is safe to
-        // write to the field when it is `None`.
-        debug_assert!(!self.is_bound());
-
-        // Bind the task to the scheduler
-        let scheduler = S::bind(task);
-
-        // Safety: As `scheduler` is not set, this is the first poll
-        self.scheduler.with_mut(|ptr| unsafe {
-            *ptr = Some(scheduler);
         });
-    }
 
-    /// Returns true if the task is bound to a scheduler.
-    pub(super) fn is_bound(&self) -> bool {
-        // Safety: never called concurrently w/ a mutation.
-        self.scheduler.with(|ptr| unsafe { (*ptr).is_some() })
-    }
+        #[cfg(debug_assertions)]
+        {
+            let trailer_addr = (&result.trailer) as *const Trailer as usize;
+            let trailer_ptr = unsafe { Header::get_trailer(NonNull::from(&result.header)) };
+            assert_eq!(trailer_addr, trailer_ptr.as_ptr() as usize);
 
-    /// Schedule the future for execution
-    pub(super) fn schedule(&self, task: Notified<S>) {
-        self.scheduler.with(|ptr| {
-            // Safety: Can only be called after initial `poll`, which is the
-            // only time the field is mutated.
-            match unsafe { &*ptr } {
-                Some(scheduler) => scheduler.schedule(task),
-                None => panic!("no scheduler set"),
-            }
-        });
-    }
+            let scheduler_addr = (&result.core.scheduler) as *const S as usize;
+            let scheduler_ptr =
+                unsafe { Header::get_scheduler::<S>(NonNull::from(&result.header)) };
+            assert_eq!(scheduler_addr, scheduler_ptr.as_ptr() as usize);
 
-    /// Schedule the future for execution in the near future, yielding the
-    /// thread to other tasks.
-    pub(super) fn yield_now(&self, task: Notified<S>) {
-        self.scheduler.with(|ptr| {
-            // Safety: Can only be called after initial `poll`, which is the
-            // only time the field is mutated.
-            match unsafe { &*ptr } {
-                Some(scheduler) => scheduler.yield_now(task),
-                None => panic!("no scheduler set"),
-            }
-        });
-    }
+            let id_addr = (&result.core.task_id) as *const Id as usize;
+            let id_ptr = unsafe { Header::get_id_ptr(NonNull::from(&result.header)) };
+            assert_eq!(id_addr, id_ptr.as_ptr() as usize);
+        }
 
-    /// Release the task
-    ///
-    /// If the `Scheduler` implementation is able to, it returns the `Task`
-    /// handle immediately. The caller of this function will batch a ref-dec
-    /// with a state change.
-    pub(super) fn release(&self, task: Task<S>) -> Option<Task<S>> {
-        use std::mem::ManuallyDrop;
-
-        let task = ManuallyDrop::new(task);
-
-        self.scheduler.with(|ptr| {
-            // Safety: Can only be called after initial `poll`, which is the
-            // only time the field is mutated.
-            match unsafe { &*ptr } {
-                Some(scheduler) => scheduler.release(&*task),
-                // Task was never polled
-                None => None,
-            }
-        })
+        result
     }
 }
 
@@ -214,8 +259,30 @@ impl<T: Future> CoreStage<T> {
     pub(super) fn with_mut<R>(&self, f: impl FnOnce(*mut Stage<T>) -> R) -> R {
         self.stage.with_mut(f)
     }
+}
+
+/// Set and clear the task id in the context when the future is executed or
+/// dropped, or when the output produced by the future is dropped.
+pub(crate) struct TaskIdGuard {
+    parent_task_id: Option<Id>,
+}
+
+impl TaskIdGuard {
+    fn enter(id: Id) -> Self {
+        TaskIdGuard {
+            parent_task_id: context::set_current_task_id(Some(id)),
+        }
+    }
+}
 
-    /// Poll the future
+impl Drop for TaskIdGuard {
+    fn drop(&mut self) {
+        context::set_current_task_id(self.parent_task_id);
+    }
+}
+
+impl<T: Future, S: Schedule> Core<T, S> {
+    /// Polls the future.
     ///
     /// # Safety
     ///
@@ -230,7 +297,7 @@ impl<T: Future> CoreStage<T> {
     /// heap.
     pub(super) fn poll(&self, mut cx: Context<'_>) -> Poll<T::Output> {
         let res = {
-            self.stage.with_mut(|ptr| {
+            self.stage.stage.with_mut(|ptr| {
                 // Safety: The caller ensures mutual exclusion to the field.
                 let future = match unsafe { &mut *ptr } {
                     Stage::Running(future) => future,
@@ -240,6 +307,7 @@ impl<T: Future> CoreStage<T> {
                 // Safety: The caller ensures the future is pinned.
                 let future = unsafe { Pin::new_unchecked(future) };
 
+                let _guard = TaskIdGuard::enter(self.task_id);
                 future.poll(&mut cx)
             })
         };
@@ -251,7 +319,7 @@ impl<T: Future> CoreStage<T> {
         res
     }
 
-    /// Drop the future
+    /// Drops the future.
     ///
     /// # Safety
     ///
@@ -263,7 +331,7 @@ impl<T: Future> CoreStage<T> {
         }
     }
 
-    /// Store the task output
+    /// Stores the task output.
     ///
     /// # Safety
     ///
@@ -275,7 +343,7 @@ impl<T: Future> CoreStage<T> {
         }
     }
 
-    /// Take the task output
+    /// Takes the task output.
     ///
     /// # Safety
     ///
@@ -283,7 +351,7 @@ impl<T: Future> CoreStage<T> {
     pub(super) fn take_output(&self) -> super::Result<T::Output> {
         use std::mem;
 
-        self.stage.with_mut(|ptr| {
+        self.stage.stage.with_mut(|ptr| {
             // Safety:: the caller ensures mutual exclusion to the field.
             match mem::replace(unsafe { &mut *ptr }, Stage::Consumed) {
                 Stage::Finished(output) => output,
@@ -293,38 +361,99 @@ impl<T: Future> CoreStage<T> {
     }
 
     unsafe fn set_stage(&self, stage: Stage<T>) {
-        self.stage.with_mut(|ptr| *ptr = stage)
+        let _guard = TaskIdGuard::enter(self.task_id);
+        self.stage.stage.with_mut(|ptr| *ptr = stage)
     }
 }
 
-cfg_rt_multi_thread! {
-    impl Header {
-        pub(crate) fn shutdown(&self) {
-            use crate::runtime::task::RawTask;
+impl Header {
+    pub(super) unsafe fn set_next(&self, next: Option<NonNull<Header>>) {
+        self.queue_next.with_mut(|ptr| *ptr = next);
+    }
+
+    // safety: The caller must guarantee exclusive access to this field, and
+    // must ensure that the id is either 0 or the id of the OwnedTasks
+    // containing this task.
+    pub(super) unsafe fn set_owner_id(&self, owner: u64) {
+        self.owner_id.with_mut(|ptr| *ptr = owner);
+    }
 
-            let task = unsafe { RawTask::from_raw(self.into()) };
-            task.shutdown();
-        }
+    pub(super) fn get_owner_id(&self) -> u64 {
+        // safety: If there are concurrent writes, then that write has violated
+        // the safety requirements on `set_owner_id`.
+        unsafe { self.owner_id.with(|ptr| *ptr) }
+    }
 
-        pub(crate) unsafe fn set_next(&self, next: Option<NonNull<Header>>) {
-            self.queue_next.with_mut(|ptr| *ptr = next);
-        }
+    /// Gets a pointer to the `Trailer` of the task containing this `Header`.
+    ///
+    /// # Safety
+    ///
+    /// The provided raw pointer must point at the header of a task.
+    pub(super) unsafe fn get_trailer(me: NonNull<Header>) -> NonNull<Trailer> {
+        let offset = me.as_ref().vtable.trailer_offset;
+        let trailer = me.as_ptr().cast::<u8>().add(offset).cast::<Trailer>();
+        NonNull::new_unchecked(trailer)
+    }
+
+    /// Gets a pointer to the scheduler of the task containing this `Header`.
+    ///
+    /// # Safety
+    ///
+    /// The provided raw pointer must point at the header of a task.
+    ///
+    /// The generic type S must be set to the correct scheduler type for this
+    /// task.
+    pub(super) unsafe fn get_scheduler<S>(me: NonNull<Header>) -> NonNull<S> {
+        let offset = me.as_ref().vtable.scheduler_offset;
+        let scheduler = me.as_ptr().cast::<u8>().add(offset).cast::<S>();
+        NonNull::new_unchecked(scheduler)
+    }
+
+    /// Gets a pointer to the id of the task containing this `Header`.
+    ///
+    /// # Safety
+    ///
+    /// The provided raw pointer must point at the header of a task.
+    pub(super) unsafe fn get_id_ptr(me: NonNull<Header>) -> NonNull<Id> {
+        let offset = me.as_ref().vtable.id_offset;
+        let id = me.as_ptr().cast::<u8>().add(offset).cast::<Id>();
+        NonNull::new_unchecked(id)
+    }
+
+    /// Gets the id of the task containing this `Header`.
+    ///
+    /// # Safety
+    ///
+    /// The provided raw pointer must point at the header of a task.
+    pub(super) unsafe fn get_id(me: NonNull<Header>) -> Id {
+        let ptr = Header::get_id_ptr(me).as_ptr();
+        *ptr
+    }
+
+    /// Gets the tracing id of the task containing this `Header`.
+    ///
+    /// # Safety
+    ///
+    /// The provided raw pointer must point at the header of a task.
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    pub(super) unsafe fn get_tracing_id(me: &NonNull<Header>) -> Option<&tracing::Id> {
+        me.as_ref().tracing_id.as_ref()
     }
 }
 
 impl Trailer {
-    pub(crate) unsafe fn set_waker(&self, waker: Option<Waker>) {
+    pub(super) unsafe fn set_waker(&self, waker: Option<Waker>) {
         self.waker.with_mut(|ptr| {
             *ptr = waker;
         });
     }
 
-    pub(crate) unsafe fn will_wake(&self, waker: &Waker) -> bool {
+    pub(super) unsafe fn will_wake(&self, waker: &Waker) -> bool {
         self.waker
             .with(|ptr| (*ptr).as_ref().unwrap().will_wake(waker))
     }
 
-    pub(crate) fn wake_join(&self) {
+    pub(super) fn wake_join(&self) {
         self.waker.with(|ptr| match unsafe { &*ptr } {
             Some(waker) => waker.wake_by_ref(),
             None => panic!("waker missing"),
diff --git a/vendor/tokio/src/runtime/task/error.rs b/vendor/tokio/src/runtime/task/error.rs
index 177fe65e9..f7ead77b7 100644
--- a/vendor/tokio/src/runtime/task/error.rs
+++ b/vendor/tokio/src/runtime/task/error.rs
@@ -1,39 +1,43 @@
 use std::any::Any;
 use std::fmt;
 use std::io;
-use std::sync::Mutex;
 
+use super::Id;
+use crate::util::SyncWrapper;
 cfg_rt! {
     /// Task failed to execute to completion.
     pub struct JoinError {
         repr: Repr,
+        id: Id,
     }
 }
 
 enum Repr {
     Cancelled,
-    Panic(Mutex<Box<dyn Any + Send + 'static>>),
+    Panic(SyncWrapper<Box<dyn Any + Send + 'static>>),
 }
 
 impl JoinError {
-    pub(crate) fn cancelled() -> JoinError {
+    pub(crate) fn cancelled(id: Id) -> JoinError {
         JoinError {
             repr: Repr::Cancelled,
+            id,
         }
     }
 
-    pub(crate) fn panic(err: Box<dyn Any + Send + 'static>) -> JoinError {
+    pub(crate) fn panic(id: Id, err: Box<dyn Any + Send + 'static>) -> JoinError {
         JoinError {
-            repr: Repr::Panic(Mutex::new(err)),
+            repr: Repr::Panic(SyncWrapper::new(err)),
+            id,
         }
     }
 
-    /// Returns true if the error was caused by the task being cancelled
+    /// Returns true if the error was caused by the task being cancelled.
     pub fn is_cancelled(&self) -> bool {
         matches!(&self.repr, Repr::Cancelled)
     }
 
-    /// Returns true if the error was caused by the task panicking
+    /// Returns true if the error was caused by the task panicking.
     ///
     /// # Examples
     ///
@@ -78,6 +82,7 @@ impl JoinError {
     ///     }
     /// }
     /// ```
+    #[track_caller]
     pub fn into_panic(self) -> Box<dyn Any + Send + 'static> {
         self.try_into_panic()
             .expect("`JoinError` reason is not a panic.")
@@ -106,17 +111,32 @@ impl JoinError {
     /// ```
     pub fn try_into_panic(self) -> Result<Box<dyn Any + Send + 'static>, JoinError> {
         match self.repr {
-            Repr::Panic(p) => Ok(p.into_inner().expect("Extracting panic from mutex")),
+            Repr::Panic(p) => Ok(p.into_inner()),
             _ => Err(self),
         }
     }
+
+    /// Returns a [task ID] that identifies the task which errored relative to
+    /// other currently spawned tasks.
+    ///
+    /// **Note**: This is an [unstable API][unstable]. The public API of this type
+    /// may break in 1.x releases. See [the documentation on unstable
+    /// features][unstable] for details.
+    ///
+    /// [task ID]: crate::task::Id
+    /// [unstable]: crate#unstable-features
+    #[cfg(tokio_unstable)]
+    #[cfg_attr(docsrs, doc(cfg(tokio_unstable)))]
+    pub fn id(&self) -> Id {
+        self.id
+    }
 }
 
 impl fmt::Display for JoinError {
     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
         match &self.repr {
-            Repr::Cancelled => write!(fmt, "cancelled"),
-            Repr::Panic(_) => write!(fmt, "panic"),
+            Repr::Cancelled => write!(fmt, "task {} was cancelled", self.id),
+            Repr::Panic(_) => write!(fmt, "task {} panicked", self.id),
         }
     }
 }
@@ -124,8 +144,8 @@ impl fmt::Display for JoinError {
 impl fmt::Debug for JoinError {
     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
         match &self.repr {
-            Repr::Cancelled => write!(fmt, "JoinError::Cancelled"),
-            Repr::Panic(_) => write!(fmt, "JoinError::Panic(...)"),
+            Repr::Cancelled => write!(fmt, "JoinError::Cancelled({:?})", self.id),
+            Repr::Panic(_) => write!(fmt, "JoinError::Panic({:?}, ...)", self.id),
         }
     }
 }
diff --git a/vendor/tokio/src/runtime/task/harness.rs b/vendor/tokio/src/runtime/task/harness.rs
index 8cd649dc7..8e3c3d14f 100644
--- a/vendor/tokio/src/runtime/task/harness.rs
+++ b/vendor/tokio/src/runtime/task/harness.rs
@@ -1,15 +1,16 @@
 use crate::future::Future;
-use crate::runtime::task::core::{Cell, Core, CoreStage, Header, Scheduler, Trailer};
-use crate::runtime::task::state::Snapshot;
+use crate::runtime::task::core::{Cell, Core, Header, Trailer};
+use crate::runtime::task::state::{Snapshot, State};
 use crate::runtime::task::waker::waker_ref;
-use crate::runtime::task::{JoinError, Notified, Schedule, Task};
+use crate::runtime::task::{JoinError, Notified, RawTask, Schedule, Task};
 
 use std::mem;
+use std::mem::ManuallyDrop;
 use std::panic;
 use std::ptr::NonNull;
 use std::task::{Context, Poll, Waker};
 
-/// Typed raw task handle
+/// Typed raw task handle.
 pub(super) struct Harness<T: Future, S: 'static> {
     cell: NonNull<Cell<T, S>>,
 }
@@ -25,8 +26,16 @@ where
         }
     }
 
+    fn header_ptr(&self) -> NonNull<Header> {
+        self.cell.cast()
+    }
+
     fn header(&self) -> &Header {
-        unsafe { &self.cell.as_ref().header }
+        unsafe { &*self.header_ptr().as_ptr() }
+    }
+
+    fn state(&self) -> &State {
+        &self.header().state
     }
 
     fn trailer(&self) -> &Trailer {
@@ -36,13 +45,91 @@ where
     fn core(&self) -> &Core<T, S> {
         unsafe { &self.cell.as_ref().core }
     }
+}
+
+/// Task operations that can be implemented without being generic over the
+/// scheduler or task. Only one version of these methods should exist in the
+/// final binary.
+impl RawTask {
+    pub(super) fn drop_reference(self) {
+        if self.state().ref_dec() {
+            self.dealloc();
+        }
+    }
+
+    /// This call consumes a ref-count and notifies the task. This will create a
+    /// new Notified and submit it if necessary.
+    ///
+    /// The caller does not need to hold a ref-count besides the one that was
+    /// passed to this call.
+    pub(super) fn wake_by_val(&self) {
+        use super::state::TransitionToNotifiedByVal;
+
+        match self.state().transition_to_notified_by_val() {
+            TransitionToNotifiedByVal::Submit => {
+                // The caller has given us a ref-count, and the transition has
+                // created a new ref-count, so we now hold two. We turn the new
+                // ref-count Notified and pass it to the call to `schedule`.
+                //
+                // The old ref-count is retained for now to ensure that the task
+                // is not dropped during the call to `schedule` if the call
+                // drops the task it was given.
+                self.schedule();
+
+                // Now that we have completed the call to schedule, we can
+                // release our ref-count.
+                self.drop_reference();
+            }
+            TransitionToNotifiedByVal::Dealloc => {
+                self.dealloc();
+            }
+            TransitionToNotifiedByVal::DoNothing => {}
+        }
+    }
+
+    /// This call notifies the task. It will not consume any ref-counts, but the
+    /// caller should hold a ref-count.  This will create a new Notified and
+    /// submit it if necessary.
+    pub(super) fn wake_by_ref(&self) {
+        use super::state::TransitionToNotifiedByRef;
+
+        match self.state().transition_to_notified_by_ref() {
+            TransitionToNotifiedByRef::Submit => {
+                // The transition above incremented the ref-count for a new task
+                // and the caller also holds a ref-count. The caller's ref-count
+                // ensures that the task is not destroyed even if the new task
+                // is dropped before `schedule` returns.
+                self.schedule();
+            }
+            TransitionToNotifiedByRef::DoNothing => {}
+        }
+    }
 
-    fn scheduler_view(&self) -> SchedulerView<'_, S> {
-        SchedulerView {
-            header: self.header(),
-            scheduler: &self.core().scheduler,
+    /// Remotely aborts the task.
+    ///
+    /// The caller should hold a ref-count, but we do not consume it.
+    ///
+    /// This is similar to `shutdown` except that it asks the runtime to perform
+    /// the shutdown. This is necessary to avoid the shutdown happening in the
+    /// wrong thread for non-Send tasks.
+    pub(super) fn remote_abort(&self) {
+        if self.state().transition_to_notified_and_cancel() {
+            // The transition has created a new ref-count, which we turn into
+            // a Notified and pass to the task.
+            //
+            // Since the caller holds a ref-count, the task cannot be destroyed
+            // before the call to `schedule` returns even if the call drops the
+            // `Notified` internally.
+            self.schedule();
         }
     }
+
+    /// Try to set the waker notified when the task is complete. Returns true if
+    /// the task has already completed. If this call returns false, then the
+    /// waker will not be notified.
+    pub(super) fn try_set_join_waker(&self, waker: &Waker) -> bool {
+        can_read_output(self.header(), self.trailer(), waker)
+    }
 }
 
 impl<T, S> Harness<T, S>
@@ -50,43 +137,109 @@ where
     T: Future,
     S: Schedule,
 {
-    /// Polls the inner future.
+    pub(super) fn drop_reference(self) {
+        if self.state().ref_dec() {
+            self.dealloc();
+        }
+    }
+
+    /// Polls the inner future. A ref-count is consumed.
     ///
     /// All necessary state checks and transitions are performed.
-    ///
     /// Panics raised while polling the future are handled.
     pub(super) fn poll(self) {
+        // We pass our ref-count to `poll_inner`.
         match self.poll_inner() {
             PollFuture::Notified => {
-                // Signal yield
-                self.core().scheduler.yield_now(Notified(self.to_task()));
-                // The ref-count was incremented as part of
-                // `transition_to_idle`.
+                // The `poll_inner` call has given us two ref-counts back.
+                // We give one of them to a new task and call `yield_now`.
+                self.core()
+                    .scheduler
+                    .yield_now(Notified(self.get_new_task()));
+
+                // The remaining ref-count is now dropped. We kept the extra
+                // ref-count until now to ensure that even if the `yield_now`
+                // call drops the provided task, the task isn't deallocated
+                // before after `yield_now` returns.
                 self.drop_reference();
             }
-            PollFuture::DropReference => {
-                self.drop_reference();
+            PollFuture::Complete => {
+                self.complete();
             }
-            PollFuture::Complete(out, is_join_interested) => {
-                self.complete(out, is_join_interested);
+            PollFuture::Dealloc => {
+                self.dealloc();
             }
-            PollFuture::None => (),
+            PollFuture::Done => (),
         }
     }
 
-    fn poll_inner(&self) -> PollFuture<T::Output> {
-        let snapshot = match self.scheduler_view().transition_to_running() {
-            TransitionToRunning::Ok(snapshot) => snapshot,
-            TransitionToRunning::DropReference => return PollFuture::DropReference,
-        };
+    /// Polls the task and cancel it if necessary. This takes ownership of a
+    /// ref-count.
+    ///
+    /// If the return value is Notified, the caller is given ownership of two
+    /// ref-counts.
+    ///
+    /// If the return value is Complete, the caller is given ownership of a
+    /// single ref-count, which should be passed on to `complete`.
+    ///
+    /// If the return value is Dealloc, then this call consumed the last
+    /// ref-count and the caller should call `dealloc`.
+    ///
+    /// Otherwise the ref-count is consumed and the caller should not access
+    /// `self` again.
+    fn poll_inner(&self) -> PollFuture {
+        use super::state::{TransitionToIdle, TransitionToRunning};
+
+        match self.state().transition_to_running() {
+            TransitionToRunning::Success => {
+                let header_ptr = self.header_ptr();
+                let waker_ref = waker_ref::<T, S>(&header_ptr);
+                let cx = Context::from_waker(&waker_ref);
+                let res = poll_future(self.core(), cx);
+
+                if res == Poll::Ready(()) {
+                    // The future completed. Move on to complete the task.
+                    return PollFuture::Complete;
+                }
 
-        // The transition to `Running` done above ensures that a lock on the
-        // future has been obtained. This also ensures the `*mut T` pointer
-        // contains the future (as opposed to the output) and is initialized.
+                match self.state().transition_to_idle() {
+                    TransitionToIdle::Ok => PollFuture::Done,
+                    TransitionToIdle::OkNotified => PollFuture::Notified,
+                    TransitionToIdle::OkDealloc => PollFuture::Dealloc,
+                    TransitionToIdle::Cancelled => {
+                        // The transition to idle failed because the task was
+                        // cancelled during the poll.
+                        cancel_task(self.core());
+                        PollFuture::Complete
+                    }
+                }
+            }
+            TransitionToRunning::Cancelled => {
+                cancel_task(self.core());
+                PollFuture::Complete
+            }
+            TransitionToRunning::Failed => PollFuture::Done,
+            TransitionToRunning::Dealloc => PollFuture::Dealloc,
+        }
+    }
 
-        let waker_ref = waker_ref::<T, S>(self.header());
-        let cx = Context::from_waker(&*waker_ref);
-        poll_future(self.header(), &self.core().stage, snapshot, cx)
+    /// Forcibly shuts down the task.
+    ///
+    /// Attempt to transition to `Running` in order to forcibly shutdown the
+    /// task. If the task is currently running or in a state of completion, then
+    /// there is nothing further to do. When the task completes running, it will
+    /// notice the `CANCELLED` bit and finalize the task.
+    pub(super) fn shutdown(self) {
+        if !self.state().transition_to_shutdown() {
+            // The task is concurrently running. No further work needed.
+            self.drop_reference();
+            return;
+        }
+
+        // By transitioning the lifecycle to `Running`, we have permission to
+        // drop the future.
+        cancel_task(self.core());
+        self.complete();
     }
 
     pub(super) fn dealloc(self) {
@@ -95,8 +248,20 @@ where
 
         // Check causality
         self.core().stage.with_mut(drop);
-        self.core().scheduler.with_mut(drop);
 
+        // Safety: The caller of this method just transitioned our ref-count to
+        // zero, so it is our responsibility to release the allocation.
+        //
+        // We don't hold any references into the allocation at this point, but
+        // it is possible for another thread to still hold a `&State` into the
+        // allocation if that other thread has decremented its last ref-count,
+        // but has not yet returned from the relevant method on `State`.
+        //
+        // However, the `State` type consists of just an `AtomicUsize`, and an
+        // `AtomicUsize` wraps the entirety of its contents in an `UnsafeCell`.
+        // As explained in the documentation for `UnsafeCell`, such references
+        // are allowed to be dangling after their last use, even if the
+        // reference has not yet gone out of scope.
         unsafe {
             drop(Box::from_raw(self.cell.as_ptr()));
         }
@@ -107,227 +272,92 @@ where
     /// Read the task output into `dst`.
     pub(super) fn try_read_output(self, dst: &mut Poll<super::Result<T::Output>>, waker: &Waker) {
         if can_read_output(self.header(), self.trailer(), waker) {
-            *dst = Poll::Ready(self.core().stage.take_output());
+            *dst = Poll::Ready(self.core().take_output());
         }
     }
 
     pub(super) fn drop_join_handle_slow(self) {
-        let mut maybe_panic = None;
-
         // Try to unset `JOIN_INTEREST`. This must be done as a first step in
         // case the task concurrently completed.
-        if self.header().state.unset_join_interested().is_err() {
+        if self.state().unset_join_interested().is_err() {
             // It is our responsibility to drop the output. This is critical as
             // the task output may not be `Send` and as such must remain with
             // the scheduler or `JoinHandle`. i.e. if the output remains in the
             // task structure until the task is deallocated, it may be dropped
             // by a Waker on any arbitrary thread.
-            let panic = panic::catch_unwind(panic::AssertUnwindSafe(|| {
-                self.core().stage.drop_future_or_output();
+            //
+            // Panics are delivered to the user via the `JoinHandle`. Given that
+            // they are dropping the `JoinHandle`, we assume they are not
+            // interested in the panic and swallow it.
+            let _ = panic::catch_unwind(panic::AssertUnwindSafe(|| {
+                self.core().drop_future_or_output();
             }));
-            if let Err(panic) = panic {
-                maybe_panic = Some(panic);
-            }
         }
 
         // Drop the `JoinHandle` reference, possibly deallocating the task
         self.drop_reference();
-
-        if let Some(panic) = maybe_panic {
-            panic::resume_unwind(panic);
-        }
-    }
-
-    // ===== waker behavior =====
-
-    pub(super) fn wake_by_val(self) {
-        self.wake_by_ref();
-        self.drop_reference();
-    }
-
-    pub(super) fn wake_by_ref(&self) {
-        if self.header().state.transition_to_notified() {
-            self.core().scheduler.schedule(Notified(self.to_task()));
-        }
-    }
-
-    pub(super) fn drop_reference(self) {
-        if self.header().state.ref_dec() {
-            self.dealloc();
-        }
     }
 
-    #[cfg(all(tokio_unstable, feature = "tracing"))]
-    pub(super) fn id(&self) -> Option<&tracing::Id> {
-        self.header().id.as_ref()
-    }
-
-    /// Forcibly shutdown the task
-    ///
-    /// Attempt to transition to `Running` in order to forcibly shutdown the
-    /// task. If the task is currently running or in a state of completion, then
-    /// there is nothing further to do. When the task completes running, it will
-    /// notice the `CANCELLED` bit and finalize the task.
-    pub(super) fn shutdown(self) {
-        if !self.header().state.transition_to_shutdown() {
-            // The task is concurrently running. No further work needed.
-            return;
-        }
-
-        // By transitioning the lifecycle to `Running`, we have permission to
-        // drop the future.
-        let err = cancel_task(&self.core().stage);
-        self.complete(Err(err), true)
-    }
+    // ====== internal ======
 
-    /// Remotely abort the task
-    ///
-    /// This is similar to `shutdown` except that it asks the runtime to perform
-    /// the shutdown. This is necessary to avoid the shutdown happening in the
-    /// wrong thread for non-Send tasks.
-    pub(super) fn remote_abort(self) {
-        if self.header().state.transition_to_notified_and_cancel() {
-            self.core().scheduler.schedule(Notified(self.to_task()));
-        }
-    }
+    /// Completes the task. This method assumes that the state is RUNNING.
+    fn complete(self) {
+        // The future has completed and its output has been written to the task
+        // stage. We transition from running to complete.
 
-    // ====== internal ======
+        let snapshot = self.state().transition_to_complete();
 
-    fn complete(self, output: super::Result<T::Output>, is_join_interested: bool) {
-        // We catch panics here because dropping the output may panic.
-        //
-        // Dropping the output can also happen in the first branch inside
-        // transition_to_complete.
+        // We catch panics here in case dropping the future or waking the
+        // JoinHandle panics.
         let _ = panic::catch_unwind(panic::AssertUnwindSafe(|| {
-            if is_join_interested {
-                // Store the output. The future has already been dropped
-                //
-                // Safety: Mutual exclusion is obtained by having transitioned the task
-                // state -> Running
-                let stage = &self.core().stage;
-                stage.store_output(output);
-
-                // Transition to `Complete`, notifying the `JoinHandle` if necessary.
-                transition_to_complete(self.header(), stage, &self.trailer());
-            } else {
-                drop(output);
+            if !snapshot.is_join_interested() {
+                // The `JoinHandle` is not interested in the output of
+                // this task. It is our responsibility to drop the
+                // output.
+                self.core().drop_future_or_output();
+            } else if snapshot.is_join_waker_set() {
+                // Notify the waker. Reading the waker field is safe per rule 4
+                // in task/mod.rs, since the JOIN_WAKER bit is set and the call
+                // to transition_to_complete() above set the COMPLETE bit.
+                self.trailer().wake_join();
             }
         }));
 
         // The task has completed execution and will no longer be scheduled.
-        //
-        // Attempts to batch a ref-dec with the state transition below.
+        let num_release = self.release();
 
-        if self
-            .scheduler_view()
-            .transition_to_terminal(is_join_interested)
-        {
-            self.dealloc()
+        if self.state().transition_to_terminal(num_release) {
+            self.dealloc();
         }
     }
 
-    fn to_task(&self) -> Task<S> {
-        self.scheduler_view().to_task()
-    }
-}
+    /// Releases the task from the scheduler. Returns the number of ref-counts
+    /// that should be decremented.
+    fn release(&self) -> usize {
+        // We don't actually increment the ref-count here, but the new task is
+        // never destroyed, so that's ok.
+        let me = ManuallyDrop::new(self.get_new_task());
 
-enum TransitionToRunning {
-    Ok(Snapshot),
-    DropReference,
-}
-
-struct SchedulerView<'a, S> {
-    header: &'a Header,
-    scheduler: &'a Scheduler<S>,
-}
-
-impl<'a, S> SchedulerView<'a, S>
-where
-    S: Schedule,
-{
-    fn to_task(&self) -> Task<S> {
-        // SAFETY The header is from the same struct containing the scheduler `S` so  the cast is safe
-        unsafe { Task::from_raw(self.header.into()) }
-    }
-
-    /// Returns true if the task should be deallocated.
-    fn transition_to_terminal(&self, is_join_interested: bool) -> bool {
-        let ref_dec = if self.scheduler.is_bound() {
-            if let Some(task) = self.scheduler.release(self.to_task()) {
-                mem::forget(task);
-                true
-            } else {
-                false
-            }
+        if let Some(task) = self.core().scheduler.release(&me) {
+            mem::forget(task);
+            2
         } else {
-            false
-        };
-
-        // This might deallocate
-        let snapshot = self
-            .header
-            .state
-            .transition_to_terminal(!is_join_interested, ref_dec);
-
-        snapshot.ref_count() == 0
-    }
-
-    fn transition_to_running(&self) -> TransitionToRunning {
-        // If this is the first time the task is polled, the task will be bound
-        // to the scheduler, in which case the task ref count must be
-        // incremented.
-        let is_not_bound = !self.scheduler.is_bound();
-
-        // Transition the task to the running state.
-        //
-        // A failure to transition here indicates the task has been cancelled
-        // while in the run queue pending execution.
-        let snapshot = match self.header.state.transition_to_running(is_not_bound) {
-            Ok(snapshot) => snapshot,
-            Err(_) => {
-                // The task was shutdown while in the run queue. At this point,
-                // we just hold a ref counted reference. Since we do not have access to it here
-                // return `DropReference` so the caller drops it.
-                return TransitionToRunning::DropReference;
-            }
-        };
-
-        if is_not_bound {
-            // Ensure the task is bound to a scheduler instance. Since this is
-            // the first time polling the task, a scheduler instance is pulled
-            // from the local context and assigned to the task.
-            //
-            // The scheduler maintains ownership of the task and responds to
-            // `wake` calls.
-            //
-            // The task reference count has been incremented.
-            //
-            // Safety: Since we have unique access to the task so that we can
-            // safely call `bind_scheduler`.
-            self.scheduler.bind_scheduler(self.to_task());
+            1
         }
-        TransitionToRunning::Ok(snapshot)
     }
-}
 
-/// Transitions the task's lifecycle to `Complete`. Notifies the
-/// `JoinHandle` if it still has interest in the completion.
-fn transition_to_complete<T>(header: &Header, stage: &CoreStage<T>, trailer: &Trailer)
-where
-    T: Future,
-{
-    // Transition the task's lifecycle to `Complete` and get a snapshot of
-    // the task's sate.
-    let snapshot = header.state.transition_to_complete();
-
-    if !snapshot.is_join_interested() {
-        // The `JoinHandle` is not interested in the output of this task. It
-        // is our responsibility to drop the output.
-        stage.drop_future_or_output();
-    } else if snapshot.has_join_waker() {
-        // Notify the join handle. The previous transition obtains the
-        // lock on the waker cell.
-        trailer.wake_join();
+    /// Creates a new task that holds its own ref-count.
+    ///
+    /// # Safety
+    ///
+    /// Any use of `self` after this call must ensure that a ref-count to the
+    /// task holds the task alive until after the use of `self`. Passing the
+    /// returned Task to any method on `self` is unsound if dropping the Task
+    /// could drop `self` before the call on `self` returned.
+    fn get_new_task(&self) -> Task<S> {
+        // safety: The header is at the beginning of the cell, so this cast is
+        // safe.
+        unsafe { Task::from_raw(self.cell.cast()) }
     }
 }
 
@@ -338,36 +368,30 @@ fn can_read_output(header: &Header, trailer: &Trailer, waker: &Waker) -> bool {
     debug_assert!(snapshot.is_join_interested());
 
     if !snapshot.is_complete() {
-        // The waker must be stored in the task struct.
-        let res = if snapshot.has_join_waker() {
-            // There already is a waker stored in the struct. If it matches
-            // the provided waker, then there is no further work to do.
-            // Otherwise, the waker must be swapped.
-            let will_wake = unsafe {
-                // Safety: when `JOIN_INTEREST` is set, only `JOIN_HANDLE`
-                // may mutate the `waker` field.
-                trailer.will_wake(waker)
-            };
-
-            if will_wake {
-                // The task is not complete **and** the waker is up to date,
-                // there is nothing further that needs to be done.
+        // If the task is not complete, try storing the provided waker in the
+        // task's waker field.
+
+        let res = if snapshot.is_join_waker_set() {
+            // If JOIN_WAKER is set, then JoinHandle has previously stored a
+            // waker in the waker field per step (iii) of rule 5 in task/mod.rs.
+
+            // Optimization: if the stored waker and the provided waker wake the
+            // same task, then return without touching the waker field. (Reading
+            // the waker field below is safe per rule 3 in task/mod.rs.)
+            if unsafe { trailer.will_wake(waker) } {
                 return false;
             }
 
-            // Unset the `JOIN_WAKER` to gain mutable access to the `waker`
-            // field then update the field with the new join worker.
-            //
-            // This requires two atomic operations, unsetting the bit and
-            // then resetting it. If the task transitions to complete
-            // concurrently to either one of those operations, then setting
-            // the join waker fails and we proceed to reading the task
-            // output.
+            // Otherwise swap the stored waker with the provided waker by
+            // following the rule 5 in task/mod.rs.
             header
                 .state
                 .unset_waker()
                 .and_then(|snapshot| set_join_waker(header, trailer, waker.clone(), snapshot))
         } else {
+            // If JOIN_WAKER is unset, then JoinHandle has mutable access to the
+            // waker field per rule 2 in task/mod.rs; therefore, skip step (i)
+            // of rule 5 and try to store the provided waker in the waker field.
             set_join_waker(header, trailer, waker.clone(), snapshot)
         };
 
@@ -388,7 +412,7 @@ fn set_join_waker(
     snapshot: Snapshot,
 ) -> Result<Snapshot, Snapshot> {
     assert!(snapshot.is_join_interested());
-    assert!(!snapshot.has_join_waker());
+    assert!(!snapshot.is_join_waker_set());
 
     // Safety: Only the `JoinHandle` may set the `waker` field. When
     // `JOIN_INTEREST` is **not** set, nothing else will touch the field.
@@ -409,73 +433,69 @@ fn set_join_waker(
     res
 }
 
-enum PollFuture<T> {
-    Complete(Result<T, JoinError>, bool),
-    DropReference,
+enum PollFuture {
+    Complete,
     Notified,
-    None,
+    Done,
+    Dealloc,
 }
 
-fn cancel_task<T: Future>(stage: &CoreStage<T>) -> JoinError {
+/// Cancels the task and store the appropriate error in the stage field.
+fn cancel_task<T: Future, S: Schedule>(core: &Core<T, S>) {
     // Drop the future from a panic guard.
     let res = panic::catch_unwind(panic::AssertUnwindSafe(|| {
-        stage.drop_future_or_output();
+        core.drop_future_or_output();
     }));
 
-    if let Err(err) = res {
-        // Dropping the future panicked, complete the join
-        // handle with the panic to avoid dropping the panic
-        // on the ground.
-        JoinError::panic(err)
-    } else {
-        JoinError::cancelled()
+    match res {
+        Ok(()) => {
+            core.store_output(Err(JoinError::cancelled(core.task_id)));
+        }
+        Err(panic) => {
+            core.store_output(Err(JoinError::panic(core.task_id, panic)));
+        }
     }
 }
 
-fn poll_future<T: Future>(
-    header: &Header,
-    core: &CoreStage<T>,
-    snapshot: Snapshot,
-    cx: Context<'_>,
-) -> PollFuture<T::Output> {
-    if snapshot.is_cancelled() {
-        PollFuture::Complete(Err(cancel_task(core)), snapshot.is_join_interested())
-    } else {
-        let res = panic::catch_unwind(panic::AssertUnwindSafe(|| {
-            struct Guard<'a, T: Future> {
-                core: &'a CoreStage<T>,
-            }
-
-            impl<T: Future> Drop for Guard<'_, T> {
-                fn drop(&mut self) {
-                    self.core.drop_future_or_output();
-                }
+/// Polls the future. If the future completes, the output is written to the
+/// stage field.
+fn poll_future<T: Future, S: Schedule>(core: &Core<T, S>, cx: Context<'_>) -> Poll<()> {
+    // Poll the future.
+    let output = panic::catch_unwind(panic::AssertUnwindSafe(|| {
+        struct Guard<'a, T: Future, S: Schedule> {
+            core: &'a Core<T, S>,
+        }
+        impl<'a, T: Future, S: Schedule> Drop for Guard<'a, T, S> {
+            fn drop(&mut self) {
+                // If the future panics on poll, we drop it inside the panic
+                // guard.
+                self.core.drop_future_or_output();
             }
+        }
+        let guard = Guard { core };
+        let res = guard.core.poll(cx);
+        mem::forget(guard);
+        res
+    }));
 
-            let guard = Guard { core };
-
-            let res = guard.core.poll(cx);
+    // Prepare output for being placed in the core stage.
+    let output = match output {
+        Ok(Poll::Pending) => return Poll::Pending,
+        Ok(Poll::Ready(output)) => Ok(output),
+        Err(panic) => {
+            core.scheduler.unhandled_panic();
+            Err(JoinError::panic(core.task_id, panic))
+        }
+    };
 
-            // prevent the guard from dropping the future
-            mem::forget(guard);
+    // Catch and ignore panics if the future panics on drop.
+    let res = panic::catch_unwind(panic::AssertUnwindSafe(|| {
+        core.store_output(output);
+    }));
 
-            res
-        }));
-        match res {
-            Ok(Poll::Pending) => match header.state.transition_to_idle() {
-                Ok(snapshot) => {
-                    if snapshot.is_notified() {
-                        PollFuture::Notified
-                    } else {
-                        PollFuture::None
-                    }
-                }
-                Err(_) => PollFuture::Complete(Err(cancel_task(core)), true),
-            },
-            Ok(Poll::Ready(ok)) => PollFuture::Complete(Ok(ok), snapshot.is_join_interested()),
-            Err(err) => {
-                PollFuture::Complete(Err(JoinError::panic(err)), snapshot.is_join_interested())
-            }
-        }
+    if res.is_err() {
+        core.scheduler.unhandled_panic();
     }
+
+    Poll::Ready(())
 }
diff --git a/vendor/tokio/src/runtime/task/id.rs b/vendor/tokio/src/runtime/task/id.rs
new file mode 100644
index 000000000..2b0d95c02
--- /dev/null
+++ b/vendor/tokio/src/runtime/task/id.rs
@@ -0,0 +1,87 @@
+use crate::runtime::context;
+
+use std::fmt;
+
+/// An opaque ID that uniquely identifies a task relative to all other currently
+/// running tasks.
+///
+/// # Notes
+///
+/// - Task IDs are unique relative to other *currently running* tasks. When a
+///   task completes, the same ID may be used for another task.
+/// - Task IDs are *not* sequential, and do not indicate the order in which
+///   tasks are spawned, what runtime a task is spawned on, or any other data.
+/// - The task ID of the currently running task can be obtained from inside the
+///   task via the [`task::try_id()`](crate::task::try_id()) and
+///   [`task::id()`](crate::task::id()) functions and from outside the task via
+///   the [`JoinHandle::id()`](crate::task::JoinHandle::id()) function.
+///
+/// **Note**: This is an [unstable API][unstable]. The public API of this type
+/// may break in 1.x releases. See [the documentation on unstable
+/// features][unstable] for details.
+///
+/// [unstable]: crate#unstable-features
+#[cfg_attr(docsrs, doc(cfg(all(feature = "rt", tokio_unstable))))]
+#[cfg_attr(not(tokio_unstable), allow(unreachable_pub))]
+#[derive(Clone, Copy, Debug, Hash, Eq, PartialEq)]
+pub struct Id(u64);
+
+/// Returns the [`Id`] of the currently running task.
+///
+/// # Panics
+///
+/// This function panics if called from outside a task. Please note that calls
+/// to `block_on` do not have task IDs, so the method will panic if called from
+/// within a call to `block_on`. For a version of this function that doesn't
+/// panic, see [`task::try_id()`](crate::runtime::task::try_id()).
+///
+/// **Note**: This is an [unstable API][unstable]. The public API of this type
+/// may break in 1.x releases. See [the documentation on unstable
+/// features][unstable] for details.
+///
+/// [task ID]: crate::task::Id
+/// [unstable]: crate#unstable-features
+#[cfg_attr(not(tokio_unstable), allow(unreachable_pub))]
+#[track_caller]
+pub fn id() -> Id {
+    context::current_task_id().expect("Can't get a task id when not inside a task")
+}
+
+/// Returns the [`Id`] of the currently running task, or `None` if called outside
+/// of a task.
+///
+/// This function is similar to  [`task::id()`](crate::runtime::task::id()), except
+/// that it returns `None` rather than panicking if called outside of a task
+/// context.
+///
+/// **Note**: This is an [unstable API][unstable]. The public API of this type
+/// may break in 1.x releases. See [the documentation on unstable
+/// features][unstable] for details.
+///
+/// [task ID]: crate::task::Id
+/// [unstable]: crate#unstable-features
+#[cfg_attr(not(tokio_unstable), allow(unreachable_pub))]
+#[track_caller]
+pub fn try_id() -> Option<Id> {
+    context::current_task_id()
+}
+
+impl fmt::Display for Id {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.0.fmt(f)
+    }
+}
+
+impl Id {
+    pub(crate) fn next() -> Self {
+        use crate::loom::sync::atomic::{Ordering::Relaxed, StaticAtomicU64};
+
+        static NEXT_ID: StaticAtomicU64 = StaticAtomicU64::new(1);
+
+        Self(NEXT_ID.fetch_add(1, Relaxed))
+    }
+
+    pub(crate) fn as_u64(&self) -> u64 {
+        self.0
+    }
+}
diff --git a/vendor/tokio/src/runtime/task/join.rs b/vendor/tokio/src/runtime/task/join.rs
index 2fe40a721..ee3925884 100644
--- a/vendor/tokio/src/runtime/task/join.rs
+++ b/vendor/tokio/src/runtime/task/join.rs
@@ -1,16 +1,19 @@
-use crate::runtime::task::RawTask;
+use crate::runtime::task::{Header, RawTask};
 
 use std::fmt;
 use std::future::Future;
 use std::marker::PhantomData;
+use std::panic::{RefUnwindSafe, UnwindSafe};
 use std::pin::Pin;
-use std::task::{Context, Poll};
+use std::task::{Context, Poll, Waker};
 
 cfg_rt! {
     /// An owned permission to join on a task (await its termination).
     ///
-    /// This can be thought of as the equivalent of [`std::thread::JoinHandle`] for
-    /// a task rather than a thread.
+    /// This can be thought of as the equivalent of [`std::thread::JoinHandle`]
+    /// for a Tokio task rather than a thread. Note that the background task
+    /// associated with this `JoinHandle` started running immediately when you
+    /// called spawn, even if you have not yet awaited the `JoinHandle`.
     ///
     /// A `JoinHandle` *detaches* the associated task when it is dropped, which
     /// means that there is no longer any handle to the task, and no way to `join`
@@ -19,6 +22,15 @@ cfg_rt! {
     /// This `struct` is created by the [`task::spawn`] and [`task::spawn_blocking`]
     /// functions.
     ///
+    /// # Cancel safety
+    ///
+    /// The `&mut JoinHandle<T>` type is cancel safe. If it is used as the event
+    /// in a `tokio::select!` statement and some other branch completes first,
+    /// then it is guaranteed that the output of the task is not lost.
+    ///
+    /// If a `JoinHandle` is dropped, then the task continues running in the
+    /// background and its return value is lost.
+    ///
     /// # Examples
     ///
     /// Creation from [`task::spawn`]:
@@ -142,7 +154,7 @@ cfg_rt! {
     /// [`std::thread::JoinHandle`]: std::thread::JoinHandle
     /// [`JoinError`]: crate::task::JoinError
     pub struct JoinHandle<T> {
-        raw: Option<RawTask>,
+        raw: RawTask,
         _p: PhantomData<T>,
     }
 }
@@ -150,10 +162,13 @@ cfg_rt! {
 unsafe impl<T: Send> Send for JoinHandle<T> {}
 unsafe impl<T: Send> Sync for JoinHandle<T> {}
 
+impl<T> UnwindSafe for JoinHandle<T> {}
+impl<T> RefUnwindSafe for JoinHandle<T> {}
+
 impl<T> JoinHandle<T> {
     pub(super) fn new(raw: RawTask) -> JoinHandle<T> {
         JoinHandle {
-            raw: Some(raw),
+            raw,
             _p: PhantomData,
         }
     }
@@ -162,39 +177,134 @@ impl<T> JoinHandle<T> {
     ///
     /// Awaiting a cancelled task might complete as usual if the task was
     /// already completed at the time it was cancelled, but most likely it
-    /// will complete with a `Err(JoinError::Cancelled)`.
+    /// will fail with a [cancelled] `JoinError`.
     ///
     /// ```rust
     /// use tokio::time;
     ///
-    /// #[tokio::main]
-    /// async fn main() {
-    ///    let mut handles = Vec::new();
-    ///
-    ///    handles.push(tokio::spawn(async {
-    ///       time::sleep(time::Duration::from_secs(10)).await;
-    ///       true
-    ///    }));
-    ///
-    ///    handles.push(tokio::spawn(async {
-    ///       time::sleep(time::Duration::from_secs(10)).await;
-    ///       false
-    ///    }));
-    ///
-    ///    for handle in &handles {
-    ///        handle.abort();
-    ///    }
-    ///
-    ///    for handle in handles {
-    ///        assert!(handle.await.unwrap_err().is_cancelled());
-    ///    }
+    /// # #[tokio::main(flavor = "current_thread", start_paused = true)]
+    /// # async fn main() {
+    /// let mut handles = Vec::new();
+    ///
+    /// handles.push(tokio::spawn(async {
+    ///    time::sleep(time::Duration::from_secs(10)).await;
+    ///    true
+    /// }));
+    ///
+    /// handles.push(tokio::spawn(async {
+    ///    time::sleep(time::Duration::from_secs(10)).await;
+    ///    false
+    /// }));
+    ///
+    /// for handle in &handles {
+    ///     handle.abort();
+    /// }
+    ///
+    /// for handle in handles {
+    ///     assert!(handle.await.unwrap_err().is_cancelled());
     /// }
+    /// # }
     /// ```
+    /// [cancelled]: method@super::error::JoinError::is_cancelled
     pub fn abort(&self) {
-        if let Some(raw) = self.raw {
-            raw.remote_abort();
+        self.raw.remote_abort();
+    }
+
+    /// Checks if the task associated with this `JoinHandle` has finished.
+    ///
+    /// Please note that this method can return `false` even if [`abort`] has been
+    /// called on the task. This is because the cancellation process may take
+    /// some time, and this method does not return `true` until it has
+    /// completed.
+    ///
+    /// ```rust
+    /// use tokio::time;
+    ///
+    /// # #[tokio::main(flavor = "current_thread", start_paused = true)]
+    /// # async fn main() {
+    /// let handle1 = tokio::spawn(async {
+    ///     // do some stuff here
+    /// });
+    /// let handle2 = tokio::spawn(async {
+    ///     // do some other stuff here
+    ///     time::sleep(time::Duration::from_secs(10)).await;
+    /// });
+    /// // Wait for the task to finish
+    /// handle2.abort();
+    /// time::sleep(time::Duration::from_secs(1)).await;
+    /// assert!(handle1.is_finished());
+    /// assert!(handle2.is_finished());
+    /// # }
+    /// ```
+    /// [`abort`]: method@JoinHandle::abort
+    pub fn is_finished(&self) -> bool {
+        let state = self.raw.header().state.load();
+        state.is_complete()
+    }
+
+    /// Set the waker that is notified when the task completes.
+    pub(crate) fn set_join_waker(&mut self, waker: &Waker) {
+        if self.raw.try_set_join_waker(waker) {
+            // In this case the task has already completed. We wake the waker immediately.
+            waker.wake_by_ref();
         }
     }
+
+    /// Returns a new `AbortHandle` that can be used to remotely abort this task.
+    ///
+    /// Awaiting a task cancelled by the `AbortHandle` might complete as usual if the task was
+    /// already completed at the time it was cancelled, but most likely it
+    /// will fail with a [cancelled] `JoinError`.
+    ///
+    /// ```rust
+    /// use tokio::{time, task};
+    ///
+    /// # #[tokio::main(flavor = "current_thread", start_paused = true)]
+    /// # async fn main() {
+    /// let mut handles = Vec::new();
+    ///
+    /// handles.push(tokio::spawn(async {
+    ///    time::sleep(time::Duration::from_secs(10)).await;
+    ///    true
+    /// }));
+    ///
+    /// handles.push(tokio::spawn(async {
+    ///    time::sleep(time::Duration::from_secs(10)).await;
+    ///    false
+    /// }));
+    ///
+    /// let abort_handles: Vec<task::AbortHandle> = handles.iter().map(|h| h.abort_handle()).collect();
+    ///
+    /// for handle in abort_handles {
+    ///     handle.abort();
+    /// }
+    ///
+    /// for handle in handles {
+    ///     assert!(handle.await.unwrap_err().is_cancelled());
+    /// }
+    /// # }
+    /// ```
+    /// [cancelled]: method@super::error::JoinError::is_cancelled
+    pub fn abort_handle(&self) -> super::AbortHandle {
+        self.raw.ref_inc();
+        super::AbortHandle::new(self.raw)
+    }
+
+    /// Returns a [task ID] that uniquely identifies this task relative to other
+    /// currently spawned tasks.
+    ///
+    /// **Note**: This is an [unstable API][unstable]. The public API of this type
+    /// may break in 1.x releases. See [the documentation on unstable
+    /// features][unstable] for details.
+    ///
+    /// [task ID]: crate::task::Id
+    /// [unstable]: crate#unstable-features
+    #[cfg(tokio_unstable)]
+    #[cfg_attr(docsrs, doc(cfg(tokio_unstable)))]
+    pub fn id(&self) -> super::Id {
+        // Safety: The header pointer is valid.
+        unsafe { Header::get_id(self.raw.header_ptr()) }
+    }
 }
 
 impl<T> Unpin for JoinHandle<T> {}
@@ -203,17 +313,11 @@ impl<T> Future for JoinHandle<T> {
     type Output = super::Result<T>;
 
     fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        ready!(crate::trace::trace_leaf(cx));
         let mut ret = Poll::Pending;
 
         // Keep track of task budget
-        let coop = ready!(crate::coop::poll_proceed(cx));
-
-        // Raw should always be set. If it is not, this is due to polling after
-        // completion
-        let raw = self
-            .raw
-            .as_ref()
-            .expect("polling after `JoinHandle` already completed");
+        let coop = ready!(crate::runtime::coop::poll_proceed(cx));
 
         // Try to read the task output. If the task is not yet complete, the
         // waker is stored and is notified once the task does complete.
@@ -227,7 +331,8 @@ impl<T> Future for JoinHandle<T> {
         //
         // The type of `T` must match the task's output type.
         unsafe {
-            raw.try_read_output(&mut ret as *mut _ as *mut (), cx.waker());
+            self.raw
+                .try_read_output(&mut ret as *mut _ as *mut (), cx.waker());
         }
 
         if ret.is_ready() {
@@ -240,13 +345,11 @@ impl<T> Future for JoinHandle<T> {
 
 impl<T> Drop for JoinHandle<T> {
     fn drop(&mut self) {
-        if let Some(raw) = self.raw.take() {
-            if raw.header().state.drop_join_handle_fast().is_ok() {
-                return;
-            }
-
-            raw.drop_join_handle_slow();
+        if self.raw.state().drop_join_handle_fast().is_ok() {
+            return;
         }
+
+        self.raw.drop_join_handle_slow();
     }
 }
 
@@ -255,6 +358,9 @@ where
     T: fmt::Debug,
 {
     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt.debug_struct("JoinHandle").finish()
+        // Safety: The header pointer is valid.
+        let id_ptr = unsafe { Header::get_id_ptr(self.raw.header_ptr()) };
+        let id = unsafe { id_ptr.as_ref() };
+        fmt.debug_struct("JoinHandle").field("id", id).finish()
     }
 }
diff --git a/vendor/tokio/src/runtime/task/list.rs b/vendor/tokio/src/runtime/task/list.rs
new file mode 100644
index 000000000..fb7dbdc1d
--- /dev/null
+++ b/vendor/tokio/src/runtime/task/list.rs
@@ -0,0 +1,319 @@
+//! This module has containers for storing the tasks spawned on a scheduler. The
+//! `OwnedTasks` container is thread-safe but can only store tasks that
+//! implement Send. The `LocalOwnedTasks` container is not thread safe, but can
+//! store non-Send tasks.
+//!
+//! The collections can be closed to prevent adding new tasks during shutdown of
+//! the scheduler with the collection.
+
+use crate::future::Future;
+use crate::loom::cell::UnsafeCell;
+use crate::loom::sync::Mutex;
+use crate::runtime::task::{JoinHandle, LocalNotified, Notified, Schedule, Task};
+use crate::util::linked_list::{CountedLinkedList, Link, LinkedList};
+
+use std::marker::PhantomData;
+
+// The id from the module below is used to verify whether a given task is stored
+// in this OwnedTasks, or some other task. The counter starts at one so we can
+// use zero for tasks not owned by any list.
+//
+// The safety checks in this file can technically be violated if the counter is
+// overflown, but the checks are not supposed to ever fail unless there is a
+// bug in Tokio, so we accept that certain bugs would not be caught if the two
+// mixed up runtimes happen to have the same id.
+
+cfg_has_atomic_u64! {
+    use std::sync::atomic::{AtomicU64, Ordering};
+
+    static NEXT_OWNED_TASKS_ID: AtomicU64 = AtomicU64::new(1);
+
+    fn get_next_id() -> u64 {
+        loop {
+            let id = NEXT_OWNED_TASKS_ID.fetch_add(1, Ordering::Relaxed);
+            if id != 0 {
+                return id;
+            }
+        }
+    }
+}
+
+cfg_not_has_atomic_u64! {
+    use std::sync::atomic::{AtomicU32, Ordering};
+
+    static NEXT_OWNED_TASKS_ID: AtomicU32 = AtomicU32::new(1);
+
+    fn get_next_id() -> u64 {
+        loop {
+            let id = NEXT_OWNED_TASKS_ID.fetch_add(1, Ordering::Relaxed);
+            if id != 0 {
+                return u64::from(id);
+            }
+        }
+    }
+}
+
+pub(crate) struct OwnedTasks<S: 'static> {
+    inner: Mutex<CountedOwnedTasksInner<S>>,
+    id: u64,
+}
+struct CountedOwnedTasksInner<S: 'static> {
+    list: CountedLinkedList<Task<S>, <Task<S> as Link>::Target>,
+    closed: bool,
+}
+pub(crate) struct LocalOwnedTasks<S: 'static> {
+    inner: UnsafeCell<OwnedTasksInner<S>>,
+    id: u64,
+    _not_send_or_sync: PhantomData<*const ()>,
+}
+struct OwnedTasksInner<S: 'static> {
+    list: LinkedList<Task<S>, <Task<S> as Link>::Target>,
+    closed: bool,
+}
+
+impl<S: 'static> OwnedTasks<S> {
+    pub(crate) fn new() -> Self {
+        Self {
+            inner: Mutex::new(CountedOwnedTasksInner {
+                list: CountedLinkedList::new(),
+                closed: false,
+            }),
+            id: get_next_id(),
+        }
+    }
+
+    /// Binds the provided task to this OwnedTasks instance. This fails if the
+    /// OwnedTasks has been closed.
+    pub(crate) fn bind<T>(
+        &self,
+        task: T,
+        scheduler: S,
+        id: super::Id,
+    ) -> (JoinHandle<T::Output>, Option<Notified<S>>)
+    where
+        S: Schedule,
+        T: Future + Send + 'static,
+        T::Output: Send + 'static,
+    {
+        let (task, notified, join) = super::new_task(task, scheduler, id);
+
+        unsafe {
+            // safety: We just created the task, so we have exclusive access
+            // to the field.
+            task.header().set_owner_id(self.id);
+        }
+
+        let mut lock = self.inner.lock();
+        if lock.closed {
+            drop(lock);
+            drop(notified);
+            task.shutdown();
+            (join, None)
+        } else {
+            lock.list.push_front(task);
+            (join, Some(notified))
+        }
+    }
+
+    /// Asserts that the given task is owned by this OwnedTasks and convert it to
+    /// a LocalNotified, giving the thread permission to poll this task.
+    #[inline]
+    pub(crate) fn assert_owner(&self, task: Notified<S>) -> LocalNotified<S> {
+        assert_eq!(task.header().get_owner_id(), self.id);
+
+        // safety: All tasks bound to this OwnedTasks are Send, so it is safe
+        // to poll it on this thread no matter what thread we are on.
+        LocalNotified {
+            task: task.0,
+            _not_send: PhantomData,
+        }
+    }
+
+    /// Shuts down all tasks in the collection. This call also closes the
+    /// collection, preventing new items from being added.
+    pub(crate) fn close_and_shutdown_all(&self)
+    where
+        S: Schedule,
+    {
+        // The first iteration of the loop was unrolled so it can set the
+        // closed bool.
+        let first_task = {
+            let mut lock = self.inner.lock();
+            lock.closed = true;
+            lock.list.pop_back()
+        };
+        match first_task {
+            Some(task) => task.shutdown(),
+            None => return,
+        }
+
+        loop {
+            let task = match self.inner.lock().list.pop_back() {
+                Some(task) => task,
+                None => return,
+            };
+
+            task.shutdown();
+        }
+    }
+
+    pub(crate) fn active_tasks_count(&self) -> usize {
+        self.inner.lock().list.count()
+    }
+
+    pub(crate) fn remove(&self, task: &Task<S>) -> Option<Task<S>> {
+        let task_id = task.header().get_owner_id();
+        if task_id == 0 {
+            // The task is unowned.
+            return None;
+        }
+
+        assert_eq!(task_id, self.id);
+
+        // safety: We just checked that the provided task is not in some other
+        // linked list.
+        unsafe { self.inner.lock().list.remove(task.header_ptr()) }
+    }
+
+    pub(crate) fn is_empty(&self) -> bool {
+        self.inner.lock().list.is_empty()
+    }
+}
+
+cfg_taskdump! {
+    impl<S: 'static> OwnedTasks<S> {
+        /// Locks the tasks, and calls `f` on an iterator over them.
+        pub(crate) fn for_each<F>(&self, f: F)
+        where
+            F: FnMut(&Task<S>)
+        {
+            self.inner.lock().list.for_each(f)
+        }
+    }
+}
+
+impl<S: 'static> LocalOwnedTasks<S> {
+    pub(crate) fn new() -> Self {
+        Self {
+            inner: UnsafeCell::new(OwnedTasksInner {
+                list: LinkedList::new(),
+                closed: false,
+            }),
+            id: get_next_id(),
+            _not_send_or_sync: PhantomData,
+        }
+    }
+
+    pub(crate) fn bind<T>(
+        &self,
+        task: T,
+        scheduler: S,
+        id: super::Id,
+    ) -> (JoinHandle<T::Output>, Option<Notified<S>>)
+    where
+        S: Schedule,
+        T: Future + 'static,
+        T::Output: 'static,
+    {
+        let (task, notified, join) = super::new_task(task, scheduler, id);
+
+        unsafe {
+            // safety: We just created the task, so we have exclusive access
+            // to the field.
+            task.header().set_owner_id(self.id);
+        }
+
+        if self.is_closed() {
+            drop(notified);
+            task.shutdown();
+            (join, None)
+        } else {
+            self.with_inner(|inner| {
+                inner.list.push_front(task);
+            });
+            (join, Some(notified))
+        }
+    }
+
+    /// Shuts down all tasks in the collection. This call also closes the
+    /// collection, preventing new items from being added.
+    pub(crate) fn close_and_shutdown_all(&self)
+    where
+        S: Schedule,
+    {
+        self.with_inner(|inner| inner.closed = true);
+
+        while let Some(task) = self.with_inner(|inner| inner.list.pop_back()) {
+            task.shutdown();
+        }
+    }
+
+    pub(crate) fn remove(&self, task: &Task<S>) -> Option<Task<S>> {
+        let task_id = task.header().get_owner_id();
+        if task_id == 0 {
+            // The task is unowned.
+            return None;
+        }
+
+        assert_eq!(task_id, self.id);
+
+        self.with_inner(|inner|
+            // safety: We just checked that the provided task is not in some
+            // other linked list.
+            unsafe { inner.list.remove(task.header_ptr()) })
+    }
+
+    /// Asserts that the given task is owned by this LocalOwnedTasks and convert
+    /// it to a LocalNotified, giving the thread permission to poll this task.
+    #[inline]
+    pub(crate) fn assert_owner(&self, task: Notified<S>) -> LocalNotified<S> {
+        assert_eq!(task.header().get_owner_id(), self.id);
+
+        // safety: The task was bound to this LocalOwnedTasks, and the
+        // LocalOwnedTasks is not Send or Sync, so we are on the right thread
+        // for polling this task.
+        LocalNotified {
+            task: task.0,
+            _not_send: PhantomData,
+        }
+    }
+
+    #[inline]
+    fn with_inner<F, T>(&self, f: F) -> T
+    where
+        F: FnOnce(&mut OwnedTasksInner<S>) -> T,
+    {
+        // safety: This type is not Sync, so concurrent calls of this method
+        // can't happen.  Furthermore, all uses of this method in this file make
+        // sure that they don't call `with_inner` recursively.
+        self.inner.with_mut(|ptr| unsafe { f(&mut *ptr) })
+    }
+
+    pub(crate) fn is_closed(&self) -> bool {
+        self.with_inner(|inner| inner.closed)
+    }
+
+    pub(crate) fn is_empty(&self) -> bool {
+        self.with_inner(|inner| inner.list.is_empty())
+    }
+}
+
+#[cfg(all(test))]
+mod tests {
+    use super::*;
+
+    // This test may run in parallel with other tests, so we only test that ids
+    // come in increasing order.
+    #[test]
+    fn test_id_not_broken() {
+        let mut last_id = get_next_id();
+        assert_ne!(last_id, 0);
+
+        for _ in 0..1000 {
+            let next_id = get_next_id();
+            assert_ne!(next_id, 0);
+            assert!(last_id < next_id);
+            last_id = next_id;
+        }
+    }
+}
diff --git a/vendor/tokio/src/runtime/task/mod.rs b/vendor/tokio/src/runtime/task/mod.rs
index 58b8c2a15..932552fb9 100644
--- a/vendor/tokio/src/runtime/task/mod.rs
+++ b/vendor/tokio/src/runtime/task/mod.rs
@@ -1,29 +1,209 @@
+//! The task module.
+//!
+//! The task module contains the code that manages spawned tasks and provides a
+//! safe API for the rest of the runtime to use. Each task in a runtime is
+//! stored in an OwnedTasks or LocalOwnedTasks object.
+//!
+//! # Task reference types
+//!
+//! A task is usually referenced by multiple handles, and there are several
+//! types of handles.
+//!
+//!  * OwnedTask - tasks stored in an OwnedTasks or LocalOwnedTasks are of this
+//!    reference type.
+//!
+//!  * JoinHandle - each task has a JoinHandle that allows access to the output
+//!    of the task.
+//!
+//!  * Waker - every waker for a task has this reference type. There can be any
+//!    number of waker references.
+//!
+//!  * Notified - tracks whether the task is notified.
+//!
+//!  * Unowned - this task reference type is used for tasks not stored in any
+//!    runtime. Mainly used for blocking tasks, but also in tests.
+//!
+//! The task uses a reference count to keep track of how many active references
+//! exist. The Unowned reference type takes up two ref-counts. All other
+//! reference types take up a single ref-count.
+//!
+//! Besides the waker type, each task has at most one of each reference type.
+//!
+//! # State
+//!
+//! The task stores its state in an atomic usize with various bitfields for the
+//! necessary information. The state has the following bitfields:
+//!
+//!  * RUNNING - Tracks whether the task is currently being polled or cancelled.
+//!    This bit functions as a lock around the task.
+//!
+//!  * COMPLETE - Is one once the future has fully completed and has been
+//!    dropped. Never unset once set. Never set together with RUNNING.
+//!
+//!  * NOTIFIED - Tracks whether a Notified object currently exists.
+//!
+//!  * CANCELLED - Is set to one for tasks that should be cancelled as soon as
+//!    possible. May take any value for completed tasks.
+//!
+//!  * JOIN_INTEREST - Is set to one if there exists a JoinHandle.
+//!
+//!  * JOIN_WAKER - Acts as an access control bit for the join handle waker. The
+//!    protocol for its usage is described below.
+//!
+//! The rest of the bits are used for the ref-count.
+//!
+//! # Fields in the task
+//!
+//! The task has various fields. This section describes how and when it is safe
+//! to access a field.
+//!
+//!  * The state field is accessed with atomic instructions.
+//!
+//!  * The OwnedTask reference has exclusive access to the `owned` field.
+//!
+//!  * The Notified reference has exclusive access to the `queue_next` field.
+//!
+//!  * The `owner_id` field can be set as part of construction of the task, but
+//!    is otherwise immutable and anyone can access the field immutably without
+//!    synchronization.
+//!
+//!  * If COMPLETE is one, then the JoinHandle has exclusive access to the
+//!    stage field. If COMPLETE is zero, then the RUNNING bitfield functions as
+//!    a lock for the stage field, and it can be accessed only by the thread
+//!    that set RUNNING to one.
+//!
+//!  * The waker field may be concurrently accessed by different threads: in one
+//!    thread the runtime may complete a task and *read* the waker field to
+//!    invoke the waker, and in another thread the task's JoinHandle may be
+//!    polled, and if the task hasn't yet completed, the JoinHandle may *write*
+//!    a waker to the waker field. The JOIN_WAKER bit ensures safe access by
+//!    multiple threads to the waker field using the following rules:
+//!
+//!    1. JOIN_WAKER is initialized to zero.
+//!
+//!    2. If JOIN_WAKER is zero, then the JoinHandle has exclusive (mutable)
+//!       access to the waker field.
+//!
+//!    3. If JOIN_WAKER is one, then the JoinHandle has shared (read-only)
+//!       access to the waker field.
+//!
+//!    4. If JOIN_WAKER is one and COMPLETE is one, then the runtime has shared
+//!       (read-only) access to the waker field.
+//!
+//!    5. If the JoinHandle needs to write to the waker field, then the
+//!       JoinHandle needs to (i) successfully set JOIN_WAKER to zero if it is
+//!       not already zero to gain exclusive access to the waker field per rule
+//!       2, (ii) write a waker, and (iii) successfully set JOIN_WAKER to one.
+//!
+//!    6. The JoinHandle can change JOIN_WAKER only if COMPLETE is zero (i.e.
+//!       the task hasn't yet completed).
+//!
+//!    Rule 6 implies that the steps (i) or (iii) of rule 5 may fail due to a
+//!    race. If step (i) fails, then the attempt to write a waker is aborted. If
+//!    step (iii) fails because COMPLETE is set to one by another thread after
+//!    step (i), then the waker field is cleared. Once COMPLETE is one (i.e.
+//!    task has completed), the JoinHandle will not modify JOIN_WAKER. After the
+//!    runtime sets COMPLETE to one, it invokes the waker if there is one.
+//!
+//! All other fields are immutable and can be accessed immutably without
+//! synchronization by anyone.
+//!
+//! # Safety
+//!
+//! This section goes through various situations and explains why the API is
+//! safe in that situation.
+//!
+//! ## Polling or dropping the future
+//!
+//! Any mutable access to the future happens after obtaining a lock by modifying
+//! the RUNNING field, so exclusive access is ensured.
+//!
+//! When the task completes, exclusive access to the output is transferred to
+//! the JoinHandle. If the JoinHandle is already dropped when the transition to
+//! complete happens, the thread performing that transition retains exclusive
+//! access to the output and should immediately drop it.
+//!
+//! ## Non-Send futures
+//!
+//! If a future is not Send, then it is bound to a LocalOwnedTasks.  The future
+//! will only ever be polled or dropped given a LocalNotified or inside a call
+//! to LocalOwnedTasks::shutdown_all. In either case, it is guaranteed that the
+//! future is on the right thread.
+//!
+//! If the task is never removed from the LocalOwnedTasks, then it is leaked, so
+//! there is no risk that the task is dropped on some other thread when the last
+//! ref-count drops.
+//!
+//! ## Non-Send output
+//!
+//! When a task completes, the output is placed in the stage of the task. Then,
+//! a transition that sets COMPLETE to true is performed, and the value of
+//! JOIN_INTEREST when this transition happens is read.
+//!
+//! If JOIN_INTEREST is zero when the transition to COMPLETE happens, then the
+//! output is immediately dropped.
+//!
+//! If JOIN_INTEREST is one when the transition to COMPLETE happens, then the
+//! JoinHandle is responsible for cleaning up the output. If the output is not
+//! Send, then this happens:
+//!
+//!  1. The output is created on the thread that the future was polled on. Since
+//!     only non-Send futures can have non-Send output, the future was polled on
+//!     the thread that the future was spawned from.
+//!  2. Since `JoinHandle<Output>` is not Send if Output is not Send, the
+//!     JoinHandle is also on the thread that the future was spawned from.
+//!  3. Thus, the JoinHandle will not move the output across threads when it
+//!     takes or drops the output.
+//!
+//! ## Recursive poll/shutdown
+//!
+//! Calling poll from inside a shutdown call or vice-versa is not prevented by
+//! the API exposed by the task module, so this has to be safe. In either case,
+//! the lock in the RUNNING bitfield makes the inner call return immediately. If
+//! the inner call is a `shutdown` call, then the CANCELLED bit is set, and the
+//! poll call will notice it when the poll finishes, and the task is cancelled
+//! at that point.
+
+// Some task infrastructure is here to support `JoinSet`, which is currently
+// unstable. This should be removed once `JoinSet` is stabilized.
+#![cfg_attr(not(tokio_unstable), allow(dead_code))]
+
 mod core;
 use self::core::Cell;
-pub(crate) use self::core::Header;
+use self::core::Header;
 
 mod error;
-#[allow(unreachable_pub)] // https://github.com/rust-lang/rust/issues/57411
 pub use self::error::JoinError;
 
 mod harness;
 use self::harness::Harness;
 
+mod id;
+#[cfg_attr(not(tokio_unstable), allow(unreachable_pub))]
+pub use id::{id, try_id, Id};
+
+#[cfg(feature = "rt")]
+mod abort;
 mod join;
-#[allow(unreachable_pub)] // https://github.com/rust-lang/rust/issues/57411
+
+#[cfg(feature = "rt")]
+pub use self::abort::AbortHandle;
+
 pub use self::join::JoinHandle;
 
+mod list;
+pub(crate) use self::list::{LocalOwnedTasks, OwnedTasks};
+
 mod raw;
-use self::raw::RawTask;
+pub(crate) use self::raw::RawTask;
 
 mod state;
 use self::state::State;
 
 mod waker;
 
-cfg_rt_multi_thread! {
-    mod stack;
-    pub(crate) use self::stack::TransferStack;
+cfg_taskdump! {
+    pub(crate) mod trace;
 }
 
 use crate::future::Future;
@@ -33,7 +213,7 @@ use std::marker::PhantomData;
 use std::ptr::NonNull;
 use std::{fmt, mem};
 
-/// An owned handle to the task, tracked by ref count
+/// An owned handle to the task, tracked by ref count.
 #[repr(transparent)]
 pub(crate) struct Task<S: 'static> {
     raw: RawTask,
@@ -43,30 +223,43 @@ pub(crate) struct Task<S: 'static> {
 unsafe impl<S> Send for Task<S> {}
 unsafe impl<S> Sync for Task<S> {}
 
-/// A task was notified
+/// A task was notified.
 #[repr(transparent)]
 pub(crate) struct Notified<S: 'static>(Task<S>);
 
+// safety: This type cannot be used to touch the task without first verifying
+// that the value is on a thread where it is safe to poll the task.
 unsafe impl<S: Schedule> Send for Notified<S> {}
 unsafe impl<S: Schedule> Sync for Notified<S> {}
 
-/// Task result sent back
+/// A non-Send variant of Notified with the invariant that it is on a thread
+/// where it is safe to poll it.
+#[repr(transparent)]
+pub(crate) struct LocalNotified<S: 'static> {
+    task: Task<S>,
+    _not_send: PhantomData<*const ()>,
+}
+
+/// A task that is not owned by any OwnedTasks. Used for blocking tasks.
+/// This type holds two ref-counts.
+pub(crate) struct UnownedTask<S: 'static> {
+    raw: RawTask,
+    _p: PhantomData<S>,
+}
+
+// safety: This type can only be created given a Send task.
+unsafe impl<S> Send for UnownedTask<S> {}
+unsafe impl<S> Sync for UnownedTask<S> {}
+
+/// Task result sent back.
 pub(crate) type Result<T> = std::result::Result<T, JoinError>;
 
 pub(crate) trait Schedule: Sync + Sized + 'static {
-    /// Bind a task to the executor.
-    ///
-    /// Guaranteed to be called from the thread that called `poll` on the task.
-    /// The returned `Schedule` instance is associated with the task and is used
-    /// as `&self` in the other methods on this trait.
-    fn bind(task: Task<Self>) -> Self;
-
     /// The task has completed work and is ready to be released. The scheduler
-    /// is free to drop it whenever.
+    /// should release it immediately and return it. The task module will batch
+    /// the ref-dec with setting other options.
     ///
-    /// If the scheduler can immediately release the task, it should return
-    /// it as part of the function. This enables the task module to batch
-    /// the ref-dec with other options.
+    /// If the scheduler has already released the task, then None is returned.
     fn release(&self, task: &Task<Self>) -> Option<Task<Self>>;
 
     /// Schedule the task
@@ -77,104 +270,177 @@ pub(crate) trait Schedule: Sync + Sized + 'static {
     fn yield_now(&self, task: Notified<Self>) {
         self.schedule(task);
     }
+
+    /// Polling the task resulted in a panic. Should the runtime shutdown?
+    fn unhandled_panic(&self) {
+        // By default, do nothing. This maintains the 1.0 behavior.
+    }
 }
 
 cfg_rt! {
-    /// Create a new task with an associated join handle
-    pub(crate) fn joinable<T, S>(task: T) -> (Notified<S>, JoinHandle<T::Output>)
+    /// This is the constructor for a new task. Three references to the task are
+    /// created. The first task reference is usually put into an OwnedTasks
+    /// immediately. The Notified is sent to the scheduler as an ordinary
+    /// notification.
+    fn new_task<T, S>(
+        task: T,
+        scheduler: S,
+        id: Id,
+    ) -> (Task<S>, Notified<S>, JoinHandle<T::Output>)
     where
-        T: Future + Send + 'static,
         S: Schedule,
+        T: Future + 'static,
+        T::Output: 'static,
     {
-        let raw = RawTask::new::<_, S>(task);
-
+        let raw = RawTask::new::<T, S>(task, scheduler, id);
         let task = Task {
             raw,
             _p: PhantomData,
         };
-
+        let notified = Notified(Task {
+            raw,
+            _p: PhantomData,
+        });
         let join = JoinHandle::new(raw);
 
-        (Notified(task), join)
+        (task, notified, join)
     }
-}
 
-cfg_rt! {
-    /// Create a new `!Send` task with an associated join handle
-    pub(crate) unsafe fn joinable_local<T, S>(task: T) -> (Notified<S>, JoinHandle<T::Output>)
+    /// Creates a new task with an associated join handle. This method is used
+    /// only when the task is not going to be stored in an `OwnedTasks` list.
+    ///
+    /// Currently only blocking tasks use this method.
+    pub(crate) fn unowned<T, S>(task: T, scheduler: S, id: Id) -> (UnownedTask<S>, JoinHandle<T::Output>)
     where
-        T: Future + 'static,
         S: Schedule,
+        T: Send + Future + 'static,
+        T::Output: Send + 'static,
     {
-        let raw = RawTask::new::<_, S>(task);
+        let (task, notified, join) = new_task(task, scheduler, id);
 
-        let task = Task {
-            raw,
+        // This transfers the ref-count of task and notified into an UnownedTask.
+        // This is valid because an UnownedTask holds two ref-counts.
+        let unowned = UnownedTask {
+            raw: task.raw,
             _p: PhantomData,
         };
+        std::mem::forget(task);
+        std::mem::forget(notified);
 
-        let join = JoinHandle::new(raw);
-
-        (Notified(task), join)
+        (unowned, join)
     }
 }
 
 impl<S: 'static> Task<S> {
-    pub(crate) unsafe fn from_raw(ptr: NonNull<Header>) -> Task<S> {
+    unsafe fn new(raw: RawTask) -> Task<S> {
         Task {
-            raw: RawTask::from_raw(ptr),
+            raw,
             _p: PhantomData,
         }
     }
 
-    pub(crate) fn header(&self) -> &Header {
+    unsafe fn from_raw(ptr: NonNull<Header>) -> Task<S> {
+        Task::new(RawTask::from_raw(ptr))
+    }
+
+    #[cfg(all(
+        tokio_unstable,
+        tokio_taskdump,
+        feature = "rt",
+        target_os = "linux",
+        any(target_arch = "aarch64", target_arch = "x86", target_arch = "x86_64")
+    ))]
+    pub(super) fn as_raw(&self) -> RawTask {
+        self.raw
+    }
+
+    fn header(&self) -> &Header {
         self.raw.header()
     }
-}
 
-cfg_rt_multi_thread! {
-    impl<S: 'static> Notified<S> {
-        pub(crate) unsafe fn from_raw(ptr: NonNull<Header>) -> Notified<S> {
-            Notified(Task::from_raw(ptr))
-        }
+    fn header_ptr(&self) -> NonNull<Header> {
+        self.raw.header_ptr()
+    }
+}
 
-        pub(crate) fn header(&self) -> &Header {
-            self.0.header()
-        }
+impl<S: 'static> Notified<S> {
+    fn header(&self) -> &Header {
+        self.0.header()
     }
+}
 
-    impl<S: 'static> Task<S> {
-        pub(crate) fn into_raw(self) -> NonNull<Header> {
-            let ret = self.header().into();
-            mem::forget(self);
-            ret
-        }
+impl<S: 'static> Notified<S> {
+    pub(crate) unsafe fn from_raw(ptr: RawTask) -> Notified<S> {
+        Notified(Task::new(ptr))
     }
+}
 
-    impl<S: 'static> Notified<S> {
-        pub(crate) fn into_raw(self) -> NonNull<Header> {
-            self.0.into_raw()
-        }
+impl<S: 'static> Notified<S> {
+    pub(crate) fn into_raw(self) -> RawTask {
+        let raw = self.0.raw;
+        mem::forget(self);
+        raw
     }
 }
 
 impl<S: Schedule> Task<S> {
-    /// Pre-emptively cancel the task as part of the shutdown process.
-    pub(crate) fn shutdown(&self) {
-        self.raw.shutdown();
+    /// Preemptively cancels the task as part of the shutdown process.
+    pub(crate) fn shutdown(self) {
+        let raw = self.raw;
+        mem::forget(self);
+        raw.shutdown();
     }
 }
 
-impl<S: Schedule> Notified<S> {
-    /// Run the task
+impl<S: Schedule> LocalNotified<S> {
+    /// Runs the task.
+    pub(crate) fn run(self) {
+        let raw = self.task.raw;
+        mem::forget(self);
+        raw.poll();
+    }
+}
+
+impl<S: Schedule> UnownedTask<S> {
+    // Used in test of the inject queue.
+    #[cfg(test)]
+    #[cfg_attr(tokio_wasm, allow(dead_code))]
+    pub(super) fn into_notified(self) -> Notified<S> {
+        Notified(self.into_task())
+    }
+
+    fn into_task(self) -> Task<S> {
+        // Convert into a task.
+        let task = Task {
+            raw: self.raw,
+            _p: PhantomData,
+        };
+        mem::forget(self);
+
+        // Drop a ref-count since an UnownedTask holds two.
+        task.header().state.ref_dec();
+
+        task
+    }
+
     pub(crate) fn run(self) {
-        self.0.raw.poll();
+        let raw = self.raw;
         mem::forget(self);
+
+        // Transfer one ref-count to a Task object.
+        let task = Task::<S> {
+            raw,
+            _p: PhantomData,
+        };
+
+        // Use the other ref-count to poll the task.
+        raw.poll();
+        // Decrement our extra ref-count
+        drop(task);
     }
 
-    /// Pre-emptively cancel the task as part of the shutdown process.
     pub(crate) fn shutdown(self) {
-        self.0.shutdown();
+        self.into_task().shutdown()
     }
 }
 
@@ -188,6 +454,16 @@ impl<S: 'static> Drop for Task<S> {
     }
 }
 
+impl<S: 'static> Drop for UnownedTask<S> {
+    fn drop(&mut self) {
+        // Decrement the ref count
+        if self.raw.header().state.ref_dec_twice() {
+            // Deallocate if this is the final ref count
+            self.raw.dealloc();
+        }
+    }
+}
+
 impl<S> fmt::Debug for Task<S> {
     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(fmt, "Task({:p})", self.header())
@@ -202,13 +478,13 @@ impl<S> fmt::Debug for Notified<S> {
 
 /// # Safety
 ///
-/// Tasks are pinned
+/// Tasks are pinned.
 unsafe impl<S> linked_list::Link for Task<S> {
     type Handle = Task<S>;
     type Target = Header;
 
     fn as_raw(handle: &Task<S>) -> NonNull<Header> {
-        handle.header().into()
+        handle.raw.header_ptr()
     }
 
     unsafe fn from_raw(ptr: NonNull<Header>) -> Task<S> {
@@ -216,7 +492,6 @@ unsafe impl<S> linked_list::Link for Task<S> {
     }
 
     unsafe fn pointers(target: NonNull<Header>) -> NonNull<linked_list::Pointers<Header>> {
-        // Not super great as it avoids some of looms checking...
-        NonNull::from(target.as_ref().owned.with_mut(|ptr| &mut *ptr))
+        self::core::Trailer::addr_of_owned(Header::get_trailer(target))
     }
 }
diff --git a/vendor/tokio/src/runtime/task/raw.rs b/vendor/tokio/src/runtime/task/raw.rs
index 56d65d5a6..807885928 100644
--- a/vendor/tokio/src/runtime/task/raw.rs
+++ b/vendor/tokio/src/runtime/task/raw.rs
@@ -1,53 +1,167 @@
 use crate::future::Future;
-use crate::runtime::task::{Cell, Harness, Header, Schedule, State};
+use crate::runtime::task::core::{Core, Trailer};
+use crate::runtime::task::{Cell, Harness, Header, Id, Schedule, State};
 
 use std::ptr::NonNull;
 use std::task::{Poll, Waker};
 
 /// Raw task handle
-pub(super) struct RawTask {
+pub(crate) struct RawTask {
     ptr: NonNull<Header>,
 }
 
 pub(super) struct Vtable {
-    /// Poll the future
+    /// Polls the future.
     pub(super) poll: unsafe fn(NonNull<Header>),
 
-    /// Deallocate the memory
+    /// Schedules the task for execution on the runtime.
+    pub(super) schedule: unsafe fn(NonNull<Header>),
+
+    /// Deallocates the memory.
     pub(super) dealloc: unsafe fn(NonNull<Header>),
 
-    /// Read the task output, if complete
+    /// Reads the task output, if complete.
     pub(super) try_read_output: unsafe fn(NonNull<Header>, *mut (), &Waker),
 
-    /// The join handle has been dropped
+    /// The join handle has been dropped.
     pub(super) drop_join_handle_slow: unsafe fn(NonNull<Header>),
 
-    /// The task is remotely aborted
-    pub(super) remote_abort: unsafe fn(NonNull<Header>),
+    /// An abort handle has been dropped.
+    pub(super) drop_abort_handle: unsafe fn(NonNull<Header>),
 
-    /// Scheduler is being shutdown
+    /// Scheduler is being shutdown.
     pub(super) shutdown: unsafe fn(NonNull<Header>),
+
+    /// The number of bytes that the `trailer` field is offset from the header.
+    pub(super) trailer_offset: usize,
+
+    /// The number of bytes that the `scheduler` field is offset from the header.
+    pub(super) scheduler_offset: usize,
+
+    /// The number of bytes that the `id` field is offset from the header.
+    pub(super) id_offset: usize,
 }
 
 /// Get the vtable for the requested `T` and `S` generics.
 pub(super) fn vtable<T: Future, S: Schedule>() -> &'static Vtable {
     &Vtable {
         poll: poll::<T, S>,
+        schedule: schedule::<S>,
         dealloc: dealloc::<T, S>,
         try_read_output: try_read_output::<T, S>,
         drop_join_handle_slow: drop_join_handle_slow::<T, S>,
-        remote_abort: remote_abort::<T, S>,
+        drop_abort_handle: drop_abort_handle::<T, S>,
         shutdown: shutdown::<T, S>,
+        trailer_offset: OffsetHelper::<T, S>::TRAILER_OFFSET,
+        scheduler_offset: OffsetHelper::<T, S>::SCHEDULER_OFFSET,
+        id_offset: OffsetHelper::<T, S>::ID_OFFSET,
     }
 }
 
+/// Calling `get_trailer_offset` directly in vtable doesn't work because it
+/// prevents the vtable from being promoted to a static reference.
+///
+/// See this thread for more info:
+/// <https://users.rust-lang.org/t/custom-vtables-with-integers/78508>
+struct OffsetHelper<T, S>(T, S);
+impl<T: Future, S: Schedule> OffsetHelper<T, S> {
+    // Pass `size_of`/`align_of` as arguments rather than calling them directly
+    // inside `get_trailer_offset` because trait bounds on generic parameters
+    // of const fn are unstable on our MSRV.
+    const TRAILER_OFFSET: usize = get_trailer_offset(
+        std::mem::size_of::<Header>(),
+        std::mem::size_of::<Core<T, S>>(),
+        std::mem::align_of::<Core<T, S>>(),
+        std::mem::align_of::<Trailer>(),
+    );
+
+    // The `scheduler` is the first field of `Core`, so it has the same
+    // offset as `Core`.
+    const SCHEDULER_OFFSET: usize = get_core_offset(
+        std::mem::size_of::<Header>(),
+        std::mem::align_of::<Core<T, S>>(),
+    );
+
+    const ID_OFFSET: usize = get_id_offset(
+        std::mem::size_of::<Header>(),
+        std::mem::align_of::<Core<T, S>>(),
+        std::mem::size_of::<S>(),
+        std::mem::align_of::<Id>(),
+    );
+}
+
+/// Compute the offset of the `Trailer` field in `Cell<T, S>` using the
+/// `#[repr(C)]` algorithm.
+///
+/// Pseudo-code for the `#[repr(C)]` algorithm can be found here:
+/// <https://doc.rust-lang.org/reference/type-layout.html#reprc-structs>
+const fn get_trailer_offset(
+    header_size: usize,
+    core_size: usize,
+    core_align: usize,
+    trailer_align: usize,
+) -> usize {
+    let mut offset = header_size;
+
+    let core_misalign = offset % core_align;
+    if core_misalign > 0 {
+        offset += core_align - core_misalign;
+    }
+    offset += core_size;
+
+    let trailer_misalign = offset % trailer_align;
+    if trailer_misalign > 0 {
+        offset += trailer_align - trailer_misalign;
+    }
+
+    offset
+}
+
+/// Compute the offset of the `Core<T, S>` field in `Cell<T, S>` using the
+/// `#[repr(C)]` algorithm.
+///
+/// Pseudo-code for the `#[repr(C)]` algorithm can be found here:
+/// <https://doc.rust-lang.org/reference/type-layout.html#reprc-structs>
+const fn get_core_offset(header_size: usize, core_align: usize) -> usize {
+    let mut offset = header_size;
+
+    let core_misalign = offset % core_align;
+    if core_misalign > 0 {
+        offset += core_align - core_misalign;
+    }
+
+    offset
+}
+
+/// Compute the offset of the `Id` field in `Cell<T, S>` using the
+/// `#[repr(C)]` algorithm.
+///
+/// Pseudo-code for the `#[repr(C)]` algorithm can be found here:
+/// <https://doc.rust-lang.org/reference/type-layout.html#reprc-structs>
+const fn get_id_offset(
+    header_size: usize,
+    core_align: usize,
+    scheduler_size: usize,
+    id_align: usize,
+) -> usize {
+    let mut offset = get_core_offset(header_size, core_align);
+    offset += scheduler_size;
+
+    let id_misalign = offset % id_align;
+    if id_misalign > 0 {
+        offset += id_align - id_misalign;
+    }
+
+    offset
+}
+
 impl RawTask {
-    pub(super) fn new<T, S>(task: T) -> RawTask
+    pub(super) fn new<T, S>(task: T, scheduler: S, id: Id) -> RawTask
     where
         T: Future,
         S: Schedule,
     {
-        let ptr = Box::into_raw(Cell::<_, S>::new(task, State::new()));
+        let ptr = Box::into_raw(Cell::<_, S>::new(task, scheduler, State::new(), id));
         let ptr = unsafe { NonNull::new_unchecked(ptr as *mut Header) };
 
         RawTask { ptr }
@@ -57,19 +171,40 @@ impl RawTask {
         RawTask { ptr }
     }
 
-    /// Returns a reference to the task's meta structure.
-    ///
-    /// Safe as `Header` is `Sync`.
+    pub(super) fn header_ptr(&self) -> NonNull<Header> {
+        self.ptr
+    }
+
+    pub(super) fn trailer_ptr(&self) -> NonNull<Trailer> {
+        unsafe { Header::get_trailer(self.ptr) }
+    }
+
+    /// Returns a reference to the task's header.
     pub(super) fn header(&self) -> &Header {
         unsafe { self.ptr.as_ref() }
     }
 
+    /// Returns a reference to the task's trailer.
+    pub(super) fn trailer(&self) -> &Trailer {
+        unsafe { &*self.trailer_ptr().as_ptr() }
+    }
+
+    /// Returns a reference to the task's state.
+    pub(super) fn state(&self) -> &State {
+        &self.header().state
+    }
+
     /// Safety: mutual exclusion is required to call this function.
-    pub(super) fn poll(self) {
+    pub(crate) fn poll(self) {
         let vtable = self.header().vtable;
         unsafe { (vtable.poll)(self.ptr) }
     }
 
+    pub(super) fn schedule(self) {
+        let vtable = self.header().vtable;
+        unsafe { (vtable.schedule)(self.ptr) }
+    }
+
     pub(super) fn dealloc(self) {
         let vtable = self.header().vtable;
         unsafe {
@@ -89,14 +224,42 @@ impl RawTask {
         unsafe { (vtable.drop_join_handle_slow)(self.ptr) }
     }
 
+    pub(super) fn drop_abort_handle(self) {
+        let vtable = self.header().vtable;
+        unsafe { (vtable.drop_abort_handle)(self.ptr) }
+    }
+
     pub(super) fn shutdown(self) {
         let vtable = self.header().vtable;
         unsafe { (vtable.shutdown)(self.ptr) }
     }
 
-    pub(super) fn remote_abort(self) {
-        let vtable = self.header().vtable;
-        unsafe { (vtable.remote_abort)(self.ptr) }
+    /// Increment the task's reference count.
+    ///
+    /// Currently, this is used only when creating an `AbortHandle`.
+    pub(super) fn ref_inc(self) {
+        self.header().state.ref_inc();
+    }
+
+    /// Get the queue-next pointer
+    ///
+    /// This is for usage by the injection queue
+    ///
+    /// Safety: make sure only one queue uses this and access is synchronized.
+    pub(crate) unsafe fn get_queue_next(self) -> Option<RawTask> {
+        self.header()
+            .queue_next
+            .with(|ptr| *ptr)
+            .map(|p| RawTask::from_raw(p))
+    }
+
+    /// Sets the queue-next pointer
+    ///
+    /// This is for usage by the injection queue
+    ///
+    /// Safety: make sure only one queue uses this and access is synchronized.
+    pub(crate) unsafe fn set_queue_next(self, val: Option<RawTask>) {
+        self.header().set_next(val.map(|task| task.ptr));
     }
 }
 
@@ -113,6 +276,15 @@ unsafe fn poll<T: Future, S: Schedule>(ptr: NonNull<Header>) {
     harness.poll();
 }
 
+unsafe fn schedule<S: Schedule>(ptr: NonNull<Header>) {
+    use crate::runtime::task::{Notified, Task};
+
+    let scheduler = Header::get_scheduler::<S>(ptr);
+    scheduler
+        .as_ref()
+        .schedule(Notified(Task::from_raw(ptr.cast())));
+}
+
 unsafe fn dealloc<T: Future, S: Schedule>(ptr: NonNull<Header>) {
     let harness = Harness::<T, S>::from_raw(ptr);
     harness.dealloc();
@@ -134,9 +306,9 @@ unsafe fn drop_join_handle_slow<T: Future, S: Schedule>(ptr: NonNull<Header>) {
     harness.drop_join_handle_slow()
 }
 
-unsafe fn remote_abort<T: Future, S: Schedule>(ptr: NonNull<Header>) {
+unsafe fn drop_abort_handle<T: Future, S: Schedule>(ptr: NonNull<Header>) {
     let harness = Harness::<T, S>::from_raw(ptr);
-    harness.remote_abort()
+    harness.drop_reference();
 }
 
 unsafe fn shutdown<T: Future, S: Schedule>(ptr: NonNull<Header>) {
diff --git a/vendor/tokio/src/runtime/task/stack.rs b/vendor/tokio/src/runtime/task/stack.rs
deleted file mode 100644
index 9dd8d3f43..000000000
--- a/vendor/tokio/src/runtime/task/stack.rs
+++ /dev/null
@@ -1,83 +0,0 @@
-use crate::loom::sync::atomic::AtomicPtr;
-use crate::runtime::task::{Header, Task};
-
-use std::marker::PhantomData;
-use std::ptr::{self, NonNull};
-use std::sync::atomic::Ordering::{Acquire, Relaxed, Release};
-
-/// Concurrent stack of tasks, used to pass ownership of a task from one worker
-/// to another.
-pub(crate) struct TransferStack<T: 'static> {
-    head: AtomicPtr<Header>,
-    _p: PhantomData<T>,
-}
-
-impl<T: 'static> TransferStack<T> {
-    pub(crate) fn new() -> TransferStack<T> {
-        TransferStack {
-            head: AtomicPtr::new(ptr::null_mut()),
-            _p: PhantomData,
-        }
-    }
-
-    pub(crate) fn push(&self, task: Task<T>) {
-        let task = task.into_raw();
-
-        // We don't care about any memory associated w/ setting the `head`
-        // field, just the current value.
-        //
-        // The compare-exchange creates a release sequence.
-        let mut curr = self.head.load(Relaxed);
-
-        loop {
-            unsafe {
-                task.as_ref()
-                    .stack_next
-                    .with_mut(|ptr| *ptr = NonNull::new(curr))
-            };
-
-            let res = self
-                .head
-                .compare_exchange(curr, task.as_ptr() as *mut _, Release, Relaxed);
-
-            match res {
-                Ok(_) => return,
-                Err(actual) => {
-                    curr = actual;
-                }
-            }
-        }
-    }
-
-    pub(crate) fn drain(&self) -> impl Iterator<Item = Task<T>> {
-        struct Iter<T: 'static>(Option<NonNull<Header>>, PhantomData<T>);
-
-        impl<T: 'static> Iterator for Iter<T> {
-            type Item = Task<T>;
-
-            fn next(&mut self) -> Option<Task<T>> {
-                let task = self.0?;
-
-                // Move the cursor forward
-                self.0 = unsafe { task.as_ref().stack_next.with(|ptr| *ptr) };
-
-                // Return the task
-                unsafe { Some(Task::from_raw(task)) }
-            }
-        }
-
-        impl<T: 'static> Drop for Iter<T> {
-            fn drop(&mut self) {
-                use std::process;
-
-                if self.0.is_some() {
-                    // we have bugs
-                    process::abort();
-                }
-            }
-        }
-
-        let ptr = self.head.swap(ptr::null_mut(), Acquire);
-        Iter(NonNull::new(ptr), PhantomData)
-    }
-}
diff --git a/vendor/tokio/src/runtime/task/state.rs b/vendor/tokio/src/runtime/task/state.rs
index 603772162..12f544918 100644
--- a/vendor/tokio/src/runtime/task/state.rs
+++ b/vendor/tokio/src/runtime/task/state.rs
@@ -8,7 +8,7 @@ pub(super) struct State {
     val: AtomicUsize,
 }
 
-/// Current state value
+/// Current state value.
 #[derive(Copy, Clone)]
 pub(super) struct Snapshot(usize);
 
@@ -19,20 +19,20 @@ const RUNNING: usize = 0b0001;
 
 /// The task is complete.
 ///
-/// Once this bit is set, it is never unset
+/// Once this bit is set, it is never unset.
 const COMPLETE: usize = 0b0010;
 
-/// Extracts the task's lifecycle value from the state
+/// Extracts the task's lifecycle value from the state.
 const LIFECYCLE_MASK: usize = 0b11;
 
 /// Flag tracking if the task has been pushed into a run queue.
 const NOTIFIED: usize = 0b100;
 
-/// The join handle is still around
+/// The join handle is still around.
 #[allow(clippy::unusual_byte_groupings)] // https://github.com/rust-lang/rust-clippy/issues/6556
 const JOIN_INTEREST: usize = 0b1_000;
 
-/// A join handle waker has been set
+/// A join handle waker has been set.
 #[allow(clippy::unusual_byte_groupings)] // https://github.com/rust-lang/rust-clippy/issues/6556
 const JOIN_WAKER: usize = 0b10_000;
 
@@ -40,36 +40,66 @@ const JOIN_WAKER: usize = 0b10_000;
 #[allow(clippy::unusual_byte_groupings)] // https://github.com/rust-lang/rust-clippy/issues/6556
 const CANCELLED: usize = 0b100_000;
 
-/// All bits
+/// All bits.
 const STATE_MASK: usize = LIFECYCLE_MASK | NOTIFIED | JOIN_INTEREST | JOIN_WAKER | CANCELLED;
 
 /// Bits used by the ref count portion of the state.
 const REF_COUNT_MASK: usize = !STATE_MASK;
 
-/// Number of positions to shift the ref count
+/// Number of positions to shift the ref count.
 const REF_COUNT_SHIFT: usize = REF_COUNT_MASK.count_zeros() as usize;
 
-/// One ref count
+/// One ref count.
 const REF_ONE: usize = 1 << REF_COUNT_SHIFT;
 
-/// State a task is initialized with
+/// State a task is initialized with.
 ///
-/// A task is initialized with two references: one for the scheduler and one for
-/// the `JoinHandle`. As the task starts with a `JoinHandle`, `JOIN_INTEREST` is
-/// set. A new task is immediately pushed into the run queue for execution and
-/// starts with the `NOTIFIED` flag set.
-const INITIAL_STATE: usize = (REF_ONE * 2) | JOIN_INTEREST | NOTIFIED;
+/// A task is initialized with three references:
+///
+///  * A reference that will be stored in an OwnedTasks or LocalOwnedTasks.
+///  * A reference that will be sent to the scheduler as an ordinary notification.
+///  * A reference for the JoinHandle.
+///
+/// As the task starts with a `JoinHandle`, `JOIN_INTEREST` is set.
+/// As the task starts with a `Notified`, `NOTIFIED` is set.
+const INITIAL_STATE: usize = (REF_ONE * 3) | JOIN_INTEREST | NOTIFIED;
+
+#[must_use]
+pub(super) enum TransitionToRunning {
+    Success,
+    Cancelled,
+    Failed,
+    Dealloc,
+}
+
+#[must_use]
+pub(super) enum TransitionToIdle {
+    Ok,
+    OkNotified,
+    OkDealloc,
+    Cancelled,
+}
+
+#[must_use]
+pub(super) enum TransitionToNotifiedByVal {
+    DoNothing,
+    Submit,
+    Dealloc,
+}
+
+#[must_use]
+pub(crate) enum TransitionToNotifiedByRef {
+    DoNothing,
+    Submit,
+}
 
 /// All transitions are performed via RMW operations. This establishes an
 /// unambiguous modification order.
 impl State {
-    /// Return a task's initial state
+    /// Returns a task's initial state.
     pub(super) fn new() -> State {
-        // A task is initialized with three references: one for the scheduler,
-        // one for the `JoinHandle`, one for the task handle made available in
-        // release. As the task starts with a `JoinHandle`, `JOIN_INTEREST` is
-        // set. A new task is immediately pushed into the run queue for
-        // execution and starts with the `NOTIFIED` flag set.
+        // The raw task returned by this method has a ref-count of three. See
+        // the comment on INITIAL_STATE for more.
         State {
             val: AtomicUsize::new(INITIAL_STATE),
         }
@@ -80,57 +110,72 @@ impl State {
         Snapshot(self.val.load(Acquire))
     }
 
-    /// Attempt to transition the lifecycle to `Running`.
-    ///
-    /// If `ref_inc` is set, the reference count is also incremented.
-    ///
-    /// The `NOTIFIED` bit is always unset.
-    pub(super) fn transition_to_running(&self, ref_inc: bool) -> UpdateResult {
-        self.fetch_update(|curr| {
-            assert!(curr.is_notified());
-
-            let mut next = curr;
+    /// Attempts to transition the lifecycle to `Running`. This sets the
+    /// notified bit to false so notifications during the poll can be detected.
+    pub(super) fn transition_to_running(&self) -> TransitionToRunning {
+        self.fetch_update_action(|mut next| {
+            let action;
+            assert!(next.is_notified());
 
             if !next.is_idle() {
-                return None;
-            }
-
-            if ref_inc {
-                next.ref_inc();
+                // This happens if the task is either currently running or if it
+                // has already completed, e.g. if it was cancelled during
+                // shutdown. Consume the ref-count and return.
+                next.ref_dec();
+                if next.ref_count() == 0 {
+                    action = TransitionToRunning::Dealloc;
+                } else {
+                    action = TransitionToRunning::Failed;
+                }
+            } else {
+                // We are able to lock the RUNNING bit.
+                next.set_running();
+                next.unset_notified();
+
+                if next.is_cancelled() {
+                    action = TransitionToRunning::Cancelled;
+                } else {
+                    action = TransitionToRunning::Success;
+                }
             }
-
-            next.set_running();
-            next.unset_notified();
-            Some(next)
+            (action, Some(next))
         })
     }
 
     /// Transitions the task from `Running` -> `Idle`.
     ///
-    /// Returns `Ok` if the transition to `Idle` is successful, `Err` otherwise.
-    /// In both cases, a snapshot of the state from **after** the transition is
-    /// returned.
-    ///
+    /// Returns `true` if the transition to `Idle` is successful, `false` otherwise.
     /// The transition to `Idle` fails if the task has been flagged to be
     /// cancelled.
-    pub(super) fn transition_to_idle(&self) -> UpdateResult {
-        self.fetch_update(|curr| {
+    pub(super) fn transition_to_idle(&self) -> TransitionToIdle {
+        self.fetch_update_action(|curr| {
             assert!(curr.is_running());
 
             if curr.is_cancelled() {
-                return None;
+                return (TransitionToIdle::Cancelled, None);
             }
 
             let mut next = curr;
+            let action;
             next.unset_running();
 
-            if next.is_notified() {
-                // The caller needs to schedule the task. To do this, it needs a
-                // waker. The waker requires a ref count.
+            if !next.is_notified() {
+                // Polling the future consumes the ref-count of the Notified.
+                next.ref_dec();
+                if next.ref_count() == 0 {
+                    action = TransitionToIdle::OkDealloc;
+                } else {
+                    action = TransitionToIdle::Ok;
+                }
+            } else {
+                // The caller will schedule a new notification, so we create a
+                // new ref-count for the notification. Our own ref-count is kept
+                // for now, and the caller will drop it shortly.
                 next.ref_inc();
+                action = TransitionToIdle::OkNotified;
             }
 
-            Some(next)
+            (action, Some(next))
         })
     }
 
@@ -145,51 +190,139 @@ impl State {
         Snapshot(prev.0 ^ DELTA)
     }
 
-    /// Transition from `Complete` -> `Terminal`, decrementing the reference
-    /// count by 1.
+    /// Transitions from `Complete` -> `Terminal`, decrementing the reference
+    /// count the specified number of times.
     ///
-    /// When `ref_dec` is set, an additional ref count decrement is performed.
-    /// This is used to batch atomic ops when possible.
-    pub(super) fn transition_to_terminal(&self, complete: bool, ref_dec: bool) -> Snapshot {
-        self.fetch_update(|mut snapshot| {
-            if complete {
-                snapshot.set_complete();
-            } else {
-                assert!(snapshot.is_complete());
-            }
+    /// Returns true if the task should be deallocated.
+    pub(super) fn transition_to_terminal(&self, count: usize) -> bool {
+        let prev = Snapshot(self.val.fetch_sub(count * REF_ONE, AcqRel));
+        assert!(
+            prev.ref_count() >= count,
+            "current: {}, sub: {}",
+            prev.ref_count(),
+            count
+        );
+        prev.ref_count() == count
+    }
+
+    /// Transitions the state to `NOTIFIED`.
+    ///
+    /// If no task needs to be submitted, a ref-count is consumed.
+    ///
+    /// If a task needs to be submitted, the ref-count is incremented for the
+    /// new Notified.
+    pub(super) fn transition_to_notified_by_val(&self) -> TransitionToNotifiedByVal {
+        self.fetch_update_action(|mut snapshot| {
+            let action;
+
+            if snapshot.is_running() {
+                // If the task is running, we mark it as notified, but we should
+                // not submit anything as the thread currently running the
+                // future is responsible for that.
+                snapshot.set_notified();
+                snapshot.ref_dec();
 
-            // Decrement the primary handle
-            snapshot.ref_dec();
+                // The thread that set the running bit also holds a ref-count.
+                assert!(snapshot.ref_count() > 0);
 
-            if ref_dec {
-                // Decrement a second time
+                action = TransitionToNotifiedByVal::DoNothing;
+            } else if snapshot.is_complete() || snapshot.is_notified() {
+                // We do not need to submit any notifications, but we have to
+                // decrement the ref-count.
                 snapshot.ref_dec();
+
+                if snapshot.ref_count() == 0 {
+                    action = TransitionToNotifiedByVal::Dealloc;
+                } else {
+                    action = TransitionToNotifiedByVal::DoNothing;
+                }
+            } else {
+                // We create a new notified that we can submit. The caller
+                // retains ownership of the ref-count they passed in.
+                snapshot.set_notified();
+                snapshot.ref_inc();
+                action = TransitionToNotifiedByVal::Submit;
             }
 
-            Some(snapshot)
+            (action, Some(snapshot))
         })
-        .unwrap()
     }
 
     /// Transitions the state to `NOTIFIED`.
-    ///
-    /// Returns `true` if the task needs to be submitted to the pool for
-    /// execution
-    pub(super) fn transition_to_notified(&self) -> bool {
-        let prev = Snapshot(self.val.fetch_or(NOTIFIED, AcqRel));
-        prev.will_need_queueing()
+    pub(super) fn transition_to_notified_by_ref(&self) -> TransitionToNotifiedByRef {
+        self.fetch_update_action(|mut snapshot| {
+            if snapshot.is_complete() || snapshot.is_notified() {
+                // There is nothing to do in this case.
+                (TransitionToNotifiedByRef::DoNothing, None)
+            } else if snapshot.is_running() {
+                // If the task is running, we mark it as notified, but we should
+                // not submit as the thread currently running the future is
+                // responsible for that.
+                snapshot.set_notified();
+                (TransitionToNotifiedByRef::DoNothing, Some(snapshot))
+            } else {
+                // The task is idle and not notified. We should submit a
+                // notification.
+                snapshot.set_notified();
+                snapshot.ref_inc();
+                (TransitionToNotifiedByRef::Submit, Some(snapshot))
+            }
+        })
     }
 
-    /// Set the cancelled bit and transition the state to `NOTIFIED`.
+    /// Transitions the state to `NOTIFIED`, unconditionally increasing the ref count.
+    #[cfg(all(
+        tokio_unstable,
+        tokio_taskdump,
+        feature = "rt",
+        target_os = "linux",
+        any(target_arch = "aarch64", target_arch = "x86", target_arch = "x86_64")
+    ))]
+    pub(super) fn transition_to_notified_for_tracing(&self) {
+        self.fetch_update_action(|mut snapshot| {
+            snapshot.set_notified();
+            snapshot.ref_inc();
+            ((), Some(snapshot))
+        });
+    }
+
+    /// Sets the cancelled bit and transitions the state to `NOTIFIED` if idle.
     ///
     /// Returns `true` if the task needs to be submitted to the pool for
-    /// execution
+    /// execution.
     pub(super) fn transition_to_notified_and_cancel(&self) -> bool {
-        let prev = Snapshot(self.val.fetch_or(NOTIFIED | CANCELLED, AcqRel));
-        prev.will_need_queueing()
+        self.fetch_update_action(|mut snapshot| {
+            if snapshot.is_cancelled() || snapshot.is_complete() {
+                // Aborts to completed or cancelled tasks are no-ops.
+                (false, None)
+            } else if snapshot.is_running() {
+                // If the task is running, we mark it as cancelled. The thread
+                // running the task will notice the cancelled bit when it
+                // stops polling and it will kill the task.
+                //
+                // The set_notified() call is not strictly necessary but it will
+                // in some cases let a wake_by_ref call return without having
+                // to perform a compare_exchange.
+                snapshot.set_notified();
+                snapshot.set_cancelled();
+                (false, Some(snapshot))
+            } else {
+                // The task is idle. We set the cancelled and notified bits and
+                // submit a notification if the notified bit was not already
+                // set.
+                snapshot.set_cancelled();
+                if !snapshot.is_notified() {
+                    snapshot.set_notified();
+                    snapshot.ref_inc();
+                    (true, Some(snapshot))
+                } else {
+                    (false, Some(snapshot))
+                }
+            }
+        })
     }
 
-    /// Set the `CANCELLED` bit and attempt to transition to `Running`.
+    /// Sets the `CANCELLED` bit and attempts to transition to `Running`.
     ///
     /// Returns `true` if the transition to `Running` succeeded.
     pub(super) fn transition_to_shutdown(&self) -> bool {
@@ -200,17 +333,11 @@ impl State {
 
             if snapshot.is_idle() {
                 snapshot.set_running();
-
-                if snapshot.is_notified() {
-                    // If the task is idle and notified, this indicates the task is
-                    // in the run queue and is considered owned by the scheduler.
-                    // The shutdown operation claims ownership of the task, which
-                    // means we need to assign an additional ref-count to the task
-                    // in the queue.
-                    snapshot.ref_inc();
-                }
             }
 
+            // If the task was not idle, the thread currently running the task
+            // will notice the cancelled bit and cancel it once the poll
+            // completes.
             snapshot.set_cancelled();
             Some(snapshot)
         });
@@ -219,7 +346,7 @@ impl State {
     }
 
     /// Optimistically tries to swap the state assuming the join handle is
-    /// __immediately__ dropped on spawn
+    /// __immediately__ dropped on spawn.
     pub(super) fn drop_join_handle_fast(&self) -> Result<(), ()> {
         use std::sync::atomic::Ordering::Relaxed;
 
@@ -241,7 +368,7 @@ impl State {
             .map_err(|_| ())
     }
 
-    /// Try to unset the JOIN_INTEREST flag.
+    /// Tries to unset the JOIN_INTEREST flag.
     ///
     /// Returns `Ok` if the operation happens before the task transitions to a
     /// completed state, `Err` otherwise.
@@ -260,14 +387,14 @@ impl State {
         })
     }
 
-    /// Set the `JOIN_WAKER` bit.
+    /// Sets the `JOIN_WAKER` bit.
     ///
     /// Returns `Ok` if the bit is set, `Err` otherwise. This operation fails if
     /// the task has completed.
     pub(super) fn set_join_waker(&self) -> UpdateResult {
         self.fetch_update(|curr| {
             assert!(curr.is_join_interested());
-            assert!(!curr.has_join_waker());
+            assert!(!curr.is_join_waker_set());
 
             if curr.is_complete() {
                 return None;
@@ -287,7 +414,7 @@ impl State {
     pub(super) fn unset_waker(&self) -> UpdateResult {
         self.fetch_update(|curr| {
             assert!(curr.is_join_interested());
-            assert!(curr.has_join_waker());
+            assert!(curr.is_join_waker_set());
 
             if curr.is_complete() {
                 return None;
@@ -326,9 +453,39 @@ impl State {
     /// Returns `true` if the task should be released.
     pub(super) fn ref_dec(&self) -> bool {
         let prev = Snapshot(self.val.fetch_sub(REF_ONE, AcqRel));
+        assert!(prev.ref_count() >= 1);
         prev.ref_count() == 1
     }
 
+    /// Returns `true` if the task should be released.
+    pub(super) fn ref_dec_twice(&self) -> bool {
+        let prev = Snapshot(self.val.fetch_sub(2 * REF_ONE, AcqRel));
+        assert!(prev.ref_count() >= 2);
+        prev.ref_count() == 2
+    }
+
+    fn fetch_update_action<F, T>(&self, mut f: F) -> T
+    where
+        F: FnMut(Snapshot) -> (T, Option<Snapshot>),
+    {
+        let mut curr = self.load();
+
+        loop {
+            let (output, next) = f(curr);
+            let next = match next {
+                Some(next) => next,
+                None => return output,
+            };
+
+            let res = self.val.compare_exchange(curr.0, next.0, AcqRel, Acquire);
+
+            match res {
+                Ok(_) => return output,
+                Err(actual) => curr = Snapshot(actual),
+            }
+        }
+    }
+
     fn fetch_update<F>(&self, mut f: F) -> Result<Snapshot, Snapshot>
     where
         F: FnMut(Snapshot) -> Option<Snapshot>,
@@ -368,6 +525,10 @@ impl Snapshot {
         self.0 &= !NOTIFIED
     }
 
+    fn set_notified(&mut self) {
+        self.0 |= NOTIFIED
+    }
+
     pub(super) fn is_running(self) -> bool {
         self.0 & RUNNING == RUNNING
     }
@@ -388,10 +549,6 @@ impl Snapshot {
         self.0 |= CANCELLED;
     }
 
-    fn set_complete(&mut self) {
-        self.0 |= COMPLETE;
-    }
-
     /// Returns `true` if the task's future has completed execution.
     pub(super) fn is_complete(self) -> bool {
         self.0 & COMPLETE == COMPLETE
@@ -405,7 +562,7 @@ impl Snapshot {
         self.0 &= !JOIN_INTEREST
     }
 
-    pub(super) fn has_join_waker(self) -> bool {
+    pub(super) fn is_join_waker_set(self) -> bool {
         self.0 & JOIN_WAKER == JOIN_WAKER
     }
 
@@ -430,10 +587,6 @@ impl Snapshot {
         assert!(self.ref_count() > 0);
         self.0 -= REF_ONE
     }
-
-    fn will_need_queueing(self) -> bool {
-        !self.is_notified() && self.is_idle()
-    }
 }
 
 impl fmt::Debug for State {
@@ -451,7 +604,7 @@ impl fmt::Debug for Snapshot {
             .field("is_notified", &self.is_notified())
             .field("is_cancelled", &self.is_cancelled())
             .field("is_join_interested", &self.is_join_interested())
-            .field("has_join_waker", &self.has_join_waker())
+            .field("is_join_waker_set", &self.is_join_waker_set())
             .field("ref_count", &self.ref_count())
             .finish()
     }
diff --git a/vendor/tokio/src/runtime/task/trace/mod.rs b/vendor/tokio/src/runtime/task/trace/mod.rs
new file mode 100644
index 000000000..543b7eee9
--- /dev/null
+++ b/vendor/tokio/src/runtime/task/trace/mod.rs
@@ -0,0 +1,330 @@
+use crate::loom::sync::Arc;
+use crate::runtime::context;
+use crate::runtime::scheduler::{self, current_thread, Inject};
+
+use backtrace::BacktraceFrame;
+use std::cell::Cell;
+use std::collections::VecDeque;
+use std::ffi::c_void;
+use std::fmt;
+use std::future::Future;
+use std::pin::Pin;
+use std::ptr::{self, NonNull};
+use std::task::{self, Poll};
+
+mod symbol;
+mod tree;
+
+use symbol::Symbol;
+use tree::Tree;
+
+use super::{Notified, OwnedTasks};
+
+type Backtrace = Vec<BacktraceFrame>;
+type SymbolTrace = Vec<Symbol>;
+
+/// The ambiant backtracing context.
+pub(crate) struct Context {
+    /// The address of [`Trace::root`] establishes an upper unwinding bound on
+    /// the backtraces in `Trace`.
+    active_frame: Cell<Option<NonNull<Frame>>>,
+    /// The place to stash backtraces.
+    collector: Cell<Option<Trace>>,
+}
+
+/// A [`Frame`] in an intrusive, doubly-linked tree of [`Frame`]s.
+struct Frame {
+    /// The location associated with this frame.
+    inner_addr: *const c_void,
+
+    /// The parent frame, if any.
+    parent: Option<NonNull<Frame>>,
+}
+
+/// An tree execution trace.
+///
+/// Traces are captured with [`Trace::capture`], rooted with [`Trace::root`]
+/// and leaved with [`trace_leaf`].
+#[derive(Clone, Debug)]
+pub(crate) struct Trace {
+    // The linear backtraces that comprise this trace. These linear traces can
+    // be re-knitted into a tree.
+    backtraces: Vec<Backtrace>,
+}
+
+pin_project_lite::pin_project! {
+    #[derive(Debug, Clone)]
+    #[must_use = "futures do nothing unless you `.await` or poll them"]
+    pub(crate) struct Root<T> {
+        #[pin]
+        future: T,
+    }
+}
+
+const FAIL_NO_THREAD_LOCAL: &str = "The Tokio thread-local has been destroyed \
+                                    as part of shutting down the current \
+                                    thread, so collecting a taskdump is not \
+                                    possible.";
+
+impl Context {
+    pub(crate) const fn new() -> Self {
+        Context {
+            active_frame: Cell::new(None),
+            collector: Cell::new(None),
+        }
+    }
+
+    /// SAFETY: Callers of this function must ensure that trace frames always
+    /// form a valid linked list.
+    unsafe fn try_with_current<F, R>(f: F) -> Option<R>
+    where
+        F: FnOnce(&Self) -> R,
+    {
+        crate::runtime::context::with_trace(f)
+    }
+
+    unsafe fn with_current_frame<F, R>(f: F) -> R
+    where
+        F: FnOnce(&Cell<Option<NonNull<Frame>>>) -> R,
+    {
+        Self::try_with_current(|context| f(&context.active_frame)).expect(FAIL_NO_THREAD_LOCAL)
+    }
+
+    fn with_current_collector<F, R>(f: F) -> R
+    where
+        F: FnOnce(&Cell<Option<Trace>>) -> R,
+    {
+        // SAFETY: This call can only access the collector field, so it cannot
+        // break the trace frame linked list.
+        unsafe {
+            Self::try_with_current(|context| f(&context.collector)).expect(FAIL_NO_THREAD_LOCAL)
+        }
+    }
+}
+
+impl Trace {
+    /// Invokes `f`, returning both its result and the collection of backtraces
+    /// captured at each sub-invocation of [`trace_leaf`].
+    #[inline(never)]
+    pub(crate) fn capture<F, R>(f: F) -> (R, Trace)
+    where
+        F: FnOnce() -> R,
+    {
+        let collector = Trace { backtraces: vec![] };
+
+        let previous = Context::with_current_collector(|current| current.replace(Some(collector)));
+
+        let result = f();
+
+        let collector =
+            Context::with_current_collector(|current| current.replace(previous)).unwrap();
+
+        (result, collector)
+    }
+
+    /// The root of a trace.
+    #[inline(never)]
+    pub(crate) fn root<F>(future: F) -> Root<F> {
+        Root { future }
+    }
+}
+
+/// If this is a sub-invocation of [`Trace::capture`], capture a backtrace.
+///
+/// The captured backtrace will be returned by [`Trace::capture`].
+///
+/// Invoking this function does nothing when it is not a sub-invocation
+/// [`Trace::capture`].
+// This function is marked `#[inline(never)]` to ensure that it gets a distinct `Frame` in the
+// backtrace, below which frames should not be included in the backtrace (since they reflect the
+// internal implementation details of this crate).
+#[inline(never)]
+pub(crate) fn trace_leaf(cx: &mut task::Context<'_>) -> Poll<()> {
+    // Safety: We don't manipulate the current context's active frame.
+    let did_trace = unsafe {
+        Context::try_with_current(|context_cell| {
+            if let Some(mut collector) = context_cell.collector.take() {
+                let mut frames = vec![];
+                let mut above_leaf = false;
+
+                if let Some(active_frame) = context_cell.active_frame.get() {
+                    let active_frame = active_frame.as_ref();
+
+                    backtrace::trace(|frame| {
+                        let below_root = !ptr::eq(frame.symbol_address(), active_frame.inner_addr);
+
+                        // only capture frames above `Trace::leaf` and below
+                        // `Trace::root`.
+                        if above_leaf && below_root {
+                            frames.push(frame.to_owned().into());
+                        }
+
+                        if ptr::eq(frame.symbol_address(), trace_leaf as *const _) {
+                            above_leaf = true;
+                        }
+
+                        // only continue unwinding if we're below `Trace::root`
+                        below_root
+                    });
+                }
+                collector.backtraces.push(frames);
+                context_cell.collector.set(Some(collector));
+                true
+            } else {
+                false
+            }
+        })
+        .unwrap_or(false)
+    };
+
+    if did_trace {
+        // Use the same logic that `yield_now` uses to send out wakeups after
+        // the task yields.
+        context::with_scheduler(|scheduler| {
+            if let Some(scheduler) = scheduler {
+                match scheduler {
+                    scheduler::Context::CurrentThread(s) => s.defer.defer(cx.waker()),
+                    #[cfg(all(feature = "rt-multi-thread", not(tokio_wasi)))]
+                    scheduler::Context::MultiThread(s) => s.defer.defer(cx.waker()),
+                }
+            }
+        });
+
+        Poll::Pending
+    } else {
+        Poll::Ready(())
+    }
+}
+
+impl fmt::Display for Trace {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        Tree::from_trace(self.clone()).fmt(f)
+    }
+}
+
+fn defer<F: FnOnce() -> R, R>(f: F) -> impl Drop {
+    use std::mem::ManuallyDrop;
+
+    struct Defer<F: FnOnce() -> R, R>(ManuallyDrop<F>);
+
+    impl<F: FnOnce() -> R, R> Drop for Defer<F, R> {
+        #[inline(always)]
+        fn drop(&mut self) {
+            unsafe {
+                ManuallyDrop::take(&mut self.0)();
+            }
+        }
+    }
+
+    Defer(ManuallyDrop::new(f))
+}
+
+impl<T: Future> Future for Root<T> {
+    type Output = T::Output;
+
+    #[inline(never)]
+    fn poll(self: Pin<&mut Self>, cx: &mut task::Context<'_>) -> Poll<Self::Output> {
+        // SAFETY: The context's current frame is restored to its original state
+        // before `frame` is dropped.
+        unsafe {
+            let mut frame = Frame {
+                inner_addr: Self::poll as *const c_void,
+                parent: None,
+            };
+
+            Context::with_current_frame(|current| {
+                frame.parent = current.take();
+                current.set(Some(NonNull::from(&frame)));
+            });
+
+            let _restore = defer(|| {
+                Context::with_current_frame(|current| {
+                    current.set(frame.parent);
+                });
+            });
+
+            let this = self.project();
+            this.future.poll(cx)
+        }
+    }
+}
+
+/// Trace and poll all tasks of the current_thread runtime.
+pub(in crate::runtime) fn trace_current_thread(
+    owned: &OwnedTasks<Arc<current_thread::Handle>>,
+    local: &mut VecDeque<Notified<Arc<current_thread::Handle>>>,
+    injection: &Inject<Arc<current_thread::Handle>>,
+) -> Vec<Trace> {
+    // clear the local and injection queues
+    local.clear();
+
+    while let Some(task) = injection.pop() {
+        drop(task);
+    }
+
+    // notify each task
+    let mut tasks = vec![];
+    owned.for_each(|task| {
+        // set the notified bit
+        task.as_raw().state().transition_to_notified_for_tracing();
+        // store the raw tasks into a vec
+        tasks.push(task.as_raw());
+    });
+
+    tasks
+        .into_iter()
+        .map(|task| {
+            let ((), trace) = Trace::capture(|| task.poll());
+            trace
+        })
+        .collect()
+}
+
+cfg_rt_multi_thread! {
+    use crate::loom::sync::Mutex;
+    use crate::runtime::scheduler::multi_thread;
+    use crate::runtime::scheduler::multi_thread::Synced;
+    use crate::runtime::scheduler::inject::Shared;
+
+    /// Trace and poll all tasks of the current_thread runtime.
+    ///
+    /// ## Safety
+    ///
+    /// Must be called with the same `synced` that `injection` was created with.
+    pub(in crate::runtime) unsafe fn trace_multi_thread(
+        owned: &OwnedTasks<Arc<multi_thread::Handle>>,
+        local: &mut multi_thread::queue::Local<Arc<multi_thread::Handle>>,
+        synced: &Mutex<Synced>,
+        injection: &Shared<Arc<multi_thread::Handle>>,
+    ) -> Vec<Trace> {
+        // clear the local queue
+        while let Some(notified) = local.pop() {
+            drop(notified);
+        }
+
+        // clear the injection queue
+        let mut synced = synced.lock();
+        while let Some(notified) = injection.pop(&mut synced.inject) {
+            drop(notified);
+        }
+
+        drop(synced);
+
+        // notify each task
+        let mut traces = vec![];
+        owned.for_each(|task| {
+            // set the notified bit
+            task.as_raw().state().transition_to_notified_for_tracing();
+
+            // trace the task
+            let ((), trace) = Trace::capture(|| task.as_raw().poll());
+            traces.push(trace);
+
+            // reschedule the task
+            let _ = task.as_raw().state().transition_to_notified_by_ref();
+            task.as_raw().schedule();
+        });
+
+        traces
+    }
+}
diff --git a/vendor/tokio/src/runtime/task/trace/symbol.rs b/vendor/tokio/src/runtime/task/trace/symbol.rs
new file mode 100644
index 000000000..49d7ba37f
--- /dev/null
+++ b/vendor/tokio/src/runtime/task/trace/symbol.rs
@@ -0,0 +1,92 @@
+use backtrace::BacktraceSymbol;
+use std::fmt;
+use std::hash::{Hash, Hasher};
+use std::ptr;
+
+/// A symbol in a backtrace.
+///
+/// This wrapper type serves two purposes. The first is that it provides a
+/// representation of a symbol that can be inserted into hashmaps and hashsets;
+/// the [`backtrace`] crate does not define [`Hash`], [`PartialEq`], or [`Eq`]
+/// on [`BacktraceSymbol`], and recommends that users define their own wrapper
+/// which implements these traits.
+///
+/// Second, this wrapper includes a `parent_hash` field that uniquely
+/// identifies this symbol's position in its trace. Otherwise, e.g., our code
+/// would not be able to distinguish between recursive calls of a function at
+/// different depths.
+#[derive(Clone)]
+pub(super) struct Symbol {
+    pub(super) symbol: BacktraceSymbol,
+    pub(super) parent_hash: u64,
+}
+
+impl Hash for Symbol {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        if let Some(name) = self.symbol.name() {
+            name.as_bytes().hash(state);
+        }
+
+        if let Some(addr) = self.symbol.addr() {
+            ptr::hash(addr, state);
+        }
+
+        self.symbol.filename().hash(state);
+        self.symbol.lineno().hash(state);
+        self.symbol.colno().hash(state);
+        self.parent_hash.hash(state);
+    }
+}
+
+impl PartialEq for Symbol {
+    fn eq(&self, other: &Self) -> bool {
+        (self.parent_hash == other.parent_hash)
+            && match (self.symbol.name(), other.symbol.name()) {
+                (None, None) => true,
+                (Some(lhs_name), Some(rhs_name)) => lhs_name.as_bytes() == rhs_name.as_bytes(),
+                _ => false,
+            }
+            && match (self.symbol.addr(), other.symbol.addr()) {
+                (None, None) => true,
+                (Some(lhs_addr), Some(rhs_addr)) => ptr::eq(lhs_addr, rhs_addr),
+                _ => false,
+            }
+            && (self.symbol.filename() == other.symbol.filename())
+            && (self.symbol.lineno() == other.symbol.lineno())
+            && (self.symbol.colno() == other.symbol.colno())
+    }
+}
+
+impl Eq for Symbol {}
+
+impl fmt::Display for Symbol {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        if let Some(name) = self.symbol.name() {
+            let name = name.to_string();
+            let name = if let Some((name, _)) = name.rsplit_once("::") {
+                name
+            } else {
+                &name
+            };
+            fmt::Display::fmt(&name, f)?;
+        }
+
+        if let Some(filename) = self.symbol.filename() {
+            f.write_str(" at ")?;
+            filename.to_string_lossy().fmt(f)?;
+            if let Some(lineno) = self.symbol.lineno() {
+                f.write_str(":")?;
+                fmt::Display::fmt(&lineno, f)?;
+                if let Some(colno) = self.symbol.colno() {
+                    f.write_str(":")?;
+                    fmt::Display::fmt(&colno, f)?;
+                }
+            }
+        }
+
+        Ok(())
+    }
+}
diff --git a/vendor/tokio/src/runtime/task/trace/tree.rs b/vendor/tokio/src/runtime/task/trace/tree.rs
new file mode 100644
index 000000000..7e6f8efec
--- /dev/null
+++ b/vendor/tokio/src/runtime/task/trace/tree.rs
@@ -0,0 +1,126 @@
+use std::collections::{hash_map::DefaultHasher, HashMap, HashSet};
+use std::fmt;
+use std::hash::{Hash, Hasher};
+
+use super::{Backtrace, Symbol, SymbolTrace, Trace};
+
+/// An adjacency list representation of an execution tree.
+///
+/// This tree provides a convenient intermediate representation for formatting
+/// [`Trace`] as a tree.
+pub(super) struct Tree {
+    /// The roots of the trees.
+    ///
+    /// There should only be one root, but the code is robust to multiple roots.
+    roots: HashSet<Symbol>,
+
+    /// The adjacency list of symbols in the execution tree(s).
+    edges: HashMap<Symbol, HashSet<Symbol>>,
+}
+
+impl Tree {
+    /// Constructs a [`Tree`] from [`Trace`]
+    pub(super) fn from_trace(trace: Trace) -> Self {
+        let mut roots: HashSet<Symbol> = HashSet::default();
+        let mut edges: HashMap<Symbol, HashSet<Symbol>> = HashMap::default();
+
+        for trace in trace.backtraces {
+            let trace = to_symboltrace(trace);
+
+            if let Some(first) = trace.first() {
+                roots.insert(first.to_owned());
+            }
+
+            let mut trace = trace.into_iter().peekable();
+            while let Some(frame) = trace.next() {
+                let subframes = edges.entry(frame).or_default();
+                if let Some(subframe) = trace.peek() {
+                    subframes.insert(subframe.clone());
+                }
+            }
+        }
+
+        Tree { roots, edges }
+    }
+
+    /// Produces the sub-symbols of a given symbol.
+    fn consequences(&self, frame: &Symbol) -> Option<impl ExactSizeIterator<Item = &Symbol>> {
+        Some(self.edges.get(frame)?.iter())
+    }
+
+    /// Format this [`Tree`] as a textual tree.
+    fn display<W: fmt::Write>(
+        &self,
+        f: &mut W,
+        root: &Symbol,
+        is_last: bool,
+        prefix: &str,
+    ) -> fmt::Result {
+        let root_fmt = format!("{}", root);
+
+        let current;
+        let next;
+
+        if is_last {
+            current = format!("{prefix}└╼\u{a0}{root_fmt}");
+            next = format!("{}\u{a0}\u{a0}\u{a0}", prefix);
+        } else {
+            current = format!("{prefix}├╼\u{a0}{root_fmt}");
+            next = format!("{}│\u{a0}\u{a0}", prefix);
+        }
+
+        write!(f, "{}", {
+            let mut current = current.chars();
+            current.next().unwrap();
+            current.next().unwrap();
+            &current.as_str()
+        })?;
+
+        if let Some(consequences) = self.consequences(root) {
+            let len = consequences.len();
+            for (i, consequence) in consequences.enumerate() {
+                let is_last = i == len - 1;
+                writeln!(f)?;
+                self.display(f, consequence, is_last, &next)?;
+            }
+        }
+
+        Ok(())
+    }
+}
+
+impl fmt::Display for Tree {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        for root in &self.roots {
+            self.display(f, root, true, " ")?;
+        }
+        Ok(())
+    }
+}
+
+/// Resolve a sequence of [`backtrace::BacktraceFrame`]s into a sequence of
+/// [`Symbol`]s.
+fn to_symboltrace(backtrace: Backtrace) -> SymbolTrace {
+    // Resolve the backtrace frames to symbols.
+    let backtrace: Backtrace = {
+        let mut backtrace = backtrace::Backtrace::from(backtrace);
+        backtrace.resolve();
+        backtrace.into()
+    };
+
+    // Accumulate the symbols in descending order into `symboltrace`.
+    let mut symboltrace: SymbolTrace = vec![];
+    let mut state = DefaultHasher::new();
+    for frame in backtrace.into_iter().rev() {
+        for symbol in frame.symbols().iter().rev() {
+            let symbol = Symbol {
+                symbol: symbol.clone(),
+                parent_hash: state.finish(),
+            };
+            symbol.hash(&mut state);
+            symboltrace.push(symbol);
+        }
+    }
+
+    symboltrace
+}
diff --git a/vendor/tokio/src/runtime/task/waker.rs b/vendor/tokio/src/runtime/task/waker.rs
index b7313b4c5..b5f5ace9e 100644
--- a/vendor/tokio/src/runtime/task/waker.rs
+++ b/vendor/tokio/src/runtime/task/waker.rs
@@ -1,6 +1,5 @@
 use crate::future::Future;
-use crate::runtime::task::harness::Harness;
-use crate::runtime::task::{Header, Schedule};
+use crate::runtime::task::{Header, RawTask, Schedule};
 
 use std::marker::PhantomData;
 use std::mem::ManuallyDrop;
@@ -13,9 +12,9 @@ pub(super) struct WakerRef<'a, S: 'static> {
     _p: PhantomData<(&'a Header, S)>,
 }
 
-/// Returns a `WakerRef` which avoids having to pre-emptively increase the
+/// Returns a `WakerRef` which avoids having to preemptively increase the
 /// refcount if there is no need to do so.
-pub(super) fn waker_ref<T, S>(header: &Header) -> WakerRef<'_, S>
+pub(super) fn waker_ref<T, S>(header: &NonNull<Header>) -> WakerRef<'_, S>
 where
     T: Future,
     S: Schedule,
@@ -28,7 +27,7 @@ where
     // point and not an *owned* waker, we must ensure that `drop` is never
     // called on this waker instance. This is done by wrapping it with
     // `ManuallyDrop` and then never calling drop.
-    let waker = unsafe { ManuallyDrop::new(Waker::from_raw(raw_waker::<T, S>(header))) };
+    let waker = unsafe { ManuallyDrop::new(Waker::from_raw(raw_waker(*header))) };
 
     WakerRef {
         waker,
@@ -46,8 +45,8 @@ impl<S> ops::Deref for WakerRef<'_, S> {
 
 cfg_trace! {
     macro_rules! trace {
-        ($harness:expr, $op:expr) => {
-            if let Some(id) = $harness.id() {
+        ($header:expr, $op:expr) => {
+            if let Some(id) = Header::get_tracing_id(&$header) {
                 tracing::trace!(
                     target: "tokio::task::waker",
                     op = $op,
@@ -60,71 +59,46 @@ cfg_trace! {
 
 cfg_not_trace! {
     macro_rules! trace {
-        ($harness:expr, $op:expr) => {
+        ($header:expr, $op:expr) => {
             // noop
-            let _ = &$harness;
+            let _ = &$header;
         }
     }
 }
 
-unsafe fn clone_waker<T, S>(ptr: *const ()) -> RawWaker
-where
-    T: Future,
-    S: Schedule,
-{
-    let header = ptr as *const Header;
-    let ptr = NonNull::new_unchecked(ptr as *mut Header);
-    let harness = Harness::<T, S>::from_raw(ptr);
-    trace!(harness, "waker.clone");
-    (*header).state.ref_inc();
-    raw_waker::<T, S>(header)
+unsafe fn clone_waker(ptr: *const ()) -> RawWaker {
+    let header = NonNull::new_unchecked(ptr as *mut Header);
+    trace!(header, "waker.clone");
+    header.as_ref().state.ref_inc();
+    raw_waker(header)
 }
 
-unsafe fn drop_waker<T, S>(ptr: *const ())
-where
-    T: Future,
-    S: Schedule,
-{
+unsafe fn drop_waker(ptr: *const ()) {
     let ptr = NonNull::new_unchecked(ptr as *mut Header);
-    let harness = Harness::<T, S>::from_raw(ptr);
-    trace!(harness, "waker.drop");
-    harness.drop_reference();
+    trace!(ptr, "waker.drop");
+    let raw = RawTask::from_raw(ptr);
+    raw.drop_reference();
 }
 
-unsafe fn wake_by_val<T, S>(ptr: *const ())
-where
-    T: Future,
-    S: Schedule,
-{
+unsafe fn wake_by_val(ptr: *const ()) {
     let ptr = NonNull::new_unchecked(ptr as *mut Header);
-    let harness = Harness::<T, S>::from_raw(ptr);
-    trace!(harness, "waker.wake");
-    harness.wake_by_val();
+    trace!(ptr, "waker.wake");
+    let raw = RawTask::from_raw(ptr);
+    raw.wake_by_val();
 }
 
 // Wake without consuming the waker
-unsafe fn wake_by_ref<T, S>(ptr: *const ())
-where
-    T: Future,
-    S: Schedule,
-{
+unsafe fn wake_by_ref(ptr: *const ()) {
     let ptr = NonNull::new_unchecked(ptr as *mut Header);
-    let harness = Harness::<T, S>::from_raw(ptr);
-    trace!(harness, "waker.wake_by_ref");
-    harness.wake_by_ref();
+    trace!(ptr, "waker.wake_by_ref");
+    let raw = RawTask::from_raw(ptr);
+    raw.wake_by_ref();
 }
 
-fn raw_waker<T, S>(header: *const Header) -> RawWaker
-where
-    T: Future,
-    S: Schedule,
-{
-    let ptr = header as *const ();
-    let vtable = &RawWakerVTable::new(
-        clone_waker::<T, S>,
-        wake_by_val::<T, S>,
-        wake_by_ref::<T, S>,
-        drop_waker::<T, S>,
-    );
-    RawWaker::new(ptr, vtable)
+static WAKER_VTABLE: RawWakerVTable =
+    RawWakerVTable::new(clone_waker, wake_by_val, wake_by_ref, drop_waker);
+
+fn raw_waker(header: NonNull<Header>) -> RawWaker {
+    let ptr = header.as_ptr() as *const ();
+    RawWaker::new(ptr, &WAKER_VTABLE)
 }
diff --git a/vendor/tokio/src/runtime/tests/inject.rs b/vendor/tokio/src/runtime/tests/inject.rs
new file mode 100644
index 000000000..ccead5e02
--- /dev/null
+++ b/vendor/tokio/src/runtime/tests/inject.rs
@@ -0,0 +1,54 @@
+use crate::runtime::scheduler::inject;
+
+#[test]
+fn push_and_pop() {
+    const N: usize = 2;
+
+    let (inject, mut synced) = inject::Shared::new();
+
+    for i in 0..N {
+        assert_eq!(inject.len(), i);
+        let (task, _) = super::unowned(async {});
+        unsafe { inject.push(&mut synced, task) };
+    }
+
+    for i in 0..N {
+        assert_eq!(inject.len(), N - i);
+        assert!(unsafe { inject.pop(&mut synced) }.is_some());
+    }
+
+    println!("--------------");
+
+    assert!(unsafe { inject.pop(&mut synced) }.is_none());
+}
+
+#[test]
+fn push_batch_and_pop() {
+    let (inject, mut inject_synced) = inject::Shared::new();
+
+    unsafe {
+        inject.push_batch(
+            &mut inject_synced,
+            (0..10).map(|_| super::unowned(async {}).0),
+        );
+
+        assert_eq!(5, inject.pop_n(&mut inject_synced, 5).count());
+        assert_eq!(5, inject.pop_n(&mut inject_synced, 5).count());
+        assert_eq!(0, inject.pop_n(&mut inject_synced, 5).count());
+    }
+}
+
+#[test]
+fn pop_n_drains_on_drop() {
+    let (inject, mut inject_synced) = inject::Shared::new();
+
+    unsafe {
+        inject.push_batch(
+            &mut inject_synced,
+            (0..10).map(|_| super::unowned(async {}).0),
+        );
+        let _ = inject.pop_n(&mut inject_synced, 10);
+
+        assert_eq!(inject.len(), 0);
+    }
+}
diff --git a/vendor/tokio/src/runtime/tests/loom_basic_scheduler.rs b/vendor/tokio/src/runtime/tests/loom_basic_scheduler.rs
deleted file mode 100644
index e6221d3b1..000000000
--- a/vendor/tokio/src/runtime/tests/loom_basic_scheduler.rs
+++ /dev/null
@@ -1,82 +0,0 @@
-use crate::loom::sync::atomic::AtomicUsize;
-use crate::loom::sync::Arc;
-use crate::loom::thread;
-use crate::runtime::{Builder, Runtime};
-use crate::sync::oneshot::{self, Receiver};
-use crate::task;
-use std::future::Future;
-use std::pin::Pin;
-use std::sync::atomic::Ordering::{Acquire, Release};
-use std::task::{Context, Poll};
-
-fn assert_at_most_num_polls(rt: Arc<Runtime>, at_most_polls: usize) {
-    let (tx, rx) = oneshot::channel();
-    let num_polls = Arc::new(AtomicUsize::new(0));
-    rt.spawn(async move {
-        for _ in 0..12 {
-            task::yield_now().await;
-        }
-        tx.send(()).unwrap();
-    });
-
-    rt.block_on(async {
-        BlockedFuture {
-            rx,
-            num_polls: num_polls.clone(),
-        }
-        .await;
-    });
-
-    let polls = num_polls.load(Acquire);
-    assert!(polls <= at_most_polls);
-}
-
-#[test]
-fn block_on_num_polls() {
-    loom::model(|| {
-        // we expect at most 3 number of polls because there are
-        // three points at which we poll the future. At any of these
-        // points it can be ready:
-        //
-        // - when we fail to steal the parker and we block on a
-        //   notification that it is available.
-        //
-        // - when we steal the parker and we schedule the future
-        //
-        // - when the future is woken up and we have ran the max
-        //   number of tasks for the current tick or there are no
-        //   more tasks to run.
-        //
-        let at_most = 3;
-
-        let rt1 = Arc::new(Builder::new_current_thread().build().unwrap());
-        let rt2 = rt1.clone();
-        let rt3 = rt1.clone();
-
-        let th1 = thread::spawn(move || assert_at_most_num_polls(rt1, at_most));
-        let th2 = thread::spawn(move || assert_at_most_num_polls(rt2, at_most));
-        let th3 = thread::spawn(move || assert_at_most_num_polls(rt3, at_most));
-
-        th1.join().unwrap();
-        th2.join().unwrap();
-        th3.join().unwrap();
-    });
-}
-
-struct BlockedFuture {
-    rx: Receiver<()>,
-    num_polls: Arc<AtomicUsize>,
-}
-
-impl Future for BlockedFuture {
-    type Output = ();
-
-    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
-        self.num_polls.fetch_add(1, Release);
-
-        match Pin::new(&mut self.rx).poll(cx) {
-            Poll::Pending => Poll::Pending,
-            _ => Poll::Ready(()),
-        }
-    }
-}
diff --git a/vendor/tokio/src/runtime/tests/loom_blocking.rs b/vendor/tokio/src/runtime/tests/loom_blocking.rs
index 8fb54c565..5c4aeae39 100644
--- a/vendor/tokio/src/runtime/tests/loom_blocking.rs
+++ b/vendor/tokio/src/runtime/tests/loom_blocking.rs
@@ -23,6 +23,77 @@ fn blocking_shutdown() {
     });
 }
 
+#[test]
+fn spawn_mandatory_blocking_should_always_run() {
+    use crate::runtime::tests::loom_oneshot;
+    loom::model(|| {
+        let rt = runtime::Builder::new_current_thread().build().unwrap();
+
+        let (tx, rx) = loom_oneshot::channel();
+        let _enter = rt.enter();
+        runtime::spawn_blocking(|| {});
+        runtime::spawn_mandatory_blocking(move || {
+            let _ = tx.send(());
+        })
+        .unwrap();
+
+        drop(rt);
+
+        // This call will deadlock if `spawn_mandatory_blocking` doesn't run.
+        let () = rx.recv();
+    });
+}
+
+#[test]
+fn spawn_mandatory_blocking_should_run_even_when_shutting_down_from_other_thread() {
+    use crate::runtime::tests::loom_oneshot;
+    loom::model(|| {
+        let rt = runtime::Builder::new_current_thread().build().unwrap();
+        let handle = rt.handle().clone();
+
+        // Drop the runtime in a different thread
+        {
+            loom::thread::spawn(move || {
+                drop(rt);
+            });
+        }
+
+        let _enter = handle.enter();
+        let (tx, rx) = loom_oneshot::channel();
+        let handle = runtime::spawn_mandatory_blocking(move || {
+            let _ = tx.send(());
+        });
+
+        // handle.is_some() means that `spawn_mandatory_blocking`
+        // promised us to run the blocking task
+        if handle.is_some() {
+            // This call will deadlock if `spawn_mandatory_blocking` doesn't run.
+            let () = rx.recv();
+        }
+    });
+}
+
+#[test]
+fn spawn_blocking_when_paused() {
+    use std::time::Duration;
+    loom::model(|| {
+        let rt = crate::runtime::Builder::new_current_thread()
+            .enable_time()
+            .start_paused(true)
+            .build()
+            .unwrap();
+        let handle = rt.handle();
+        let _enter = handle.enter();
+        let a = crate::task::spawn_blocking(|| {});
+        let b = crate::task::spawn_blocking(|| {});
+        rt.block_on(crate::time::timeout(Duration::from_millis(1), async move {
+            a.await.expect("blocking task should finish");
+            b.await.expect("blocking task should finish");
+        }))
+        .expect("timeout should not trigger");
+    });
+}
+
 fn mk_runtime(num_threads: usize) -> Runtime {
     runtime::Builder::new_multi_thread()
         .worker_threads(num_threads)
diff --git a/vendor/tokio/src/runtime/tests/loom_current_thread_scheduler.rs b/vendor/tokio/src/runtime/tests/loom_current_thread_scheduler.rs
new file mode 100644
index 000000000..a772603f7
--- /dev/null
+++ b/vendor/tokio/src/runtime/tests/loom_current_thread_scheduler.rs
@@ -0,0 +1,142 @@
+use crate::loom::sync::atomic::AtomicUsize;
+use crate::loom::sync::Arc;
+use crate::loom::thread;
+use crate::runtime::{Builder, Runtime};
+use crate::sync::oneshot::{self, Receiver};
+use crate::task;
+use std::future::Future;
+use std::pin::Pin;
+use std::sync::atomic::Ordering::{Acquire, Release};
+use std::task::{Context, Poll};
+
+fn assert_at_most_num_polls(rt: Arc<Runtime>, at_most_polls: usize) {
+    let (tx, rx) = oneshot::channel();
+    let num_polls = Arc::new(AtomicUsize::new(0));
+    rt.spawn(async move {
+        for _ in 0..12 {
+            task::yield_now().await;
+        }
+        tx.send(()).unwrap();
+    });
+
+    rt.block_on(async {
+        BlockedFuture {
+            rx,
+            num_polls: num_polls.clone(),
+        }
+        .await;
+    });
+
+    let polls = num_polls.load(Acquire);
+    assert!(polls <= at_most_polls);
+}
+
+#[test]
+fn block_on_num_polls() {
+    loom::model(|| {
+        // we expect at most 4 number of polls because there are three points at
+        // which we poll the future and an opportunity for a false-positive.. At
+        // any of these points it can be ready:
+        //
+        // - when we fail to steal the parker and we block on a notification
+        //   that it is available.
+        //
+        // - when we steal the parker and we schedule the future
+        //
+        // - when the future is woken up and we have ran the max number of tasks
+        //   for the current tick or there are no more tasks to run.
+        //
+        // - a thread is notified that the parker is available but a third
+        //   thread acquires it before the notified thread can.
+        //
+        let at_most = 4;
+
+        let rt1 = Arc::new(Builder::new_current_thread().build().unwrap());
+        let rt2 = rt1.clone();
+        let rt3 = rt1.clone();
+
+        let th1 = thread::spawn(move || assert_at_most_num_polls(rt1, at_most));
+        let th2 = thread::spawn(move || assert_at_most_num_polls(rt2, at_most));
+        let th3 = thread::spawn(move || assert_at_most_num_polls(rt3, at_most));
+
+        th1.join().unwrap();
+        th2.join().unwrap();
+        th3.join().unwrap();
+    });
+}
+
+#[test]
+fn assert_no_unnecessary_polls() {
+    loom::model(|| {
+        // // After we poll outer future, woken should reset to false
+        let rt = Builder::new_current_thread().build().unwrap();
+        let (tx, rx) = oneshot::channel();
+        let pending_cnt = Arc::new(AtomicUsize::new(0));
+
+        rt.spawn(async move {
+            for _ in 0..24 {
+                task::yield_now().await;
+            }
+            tx.send(()).unwrap();
+        });
+
+        let pending_cnt_clone = pending_cnt.clone();
+        rt.block_on(async move {
+            // use task::yield_now() to ensure woken set to true
+            // ResetFuture will be polled at most once
+            // Here comes two cases
+            // 1. recv no message from channel, ResetFuture will be polled
+            //    but get Pending and we record ResetFuture.pending_cnt ++.
+            //    Then when message arrive, ResetFuture returns Ready. So we
+            //    expect ResetFuture.pending_cnt = 1
+            // 2. recv message from channel, ResetFuture returns Ready immediately.
+            //    We expect ResetFuture.pending_cnt = 0
+            task::yield_now().await;
+            ResetFuture {
+                rx,
+                pending_cnt: pending_cnt_clone,
+            }
+            .await;
+        });
+
+        let pending_cnt = pending_cnt.load(Acquire);
+        assert!(pending_cnt <= 1);
+    });
+}
+
+struct BlockedFuture {
+    rx: Receiver<()>,
+    num_polls: Arc<AtomicUsize>,
+}
+
+impl Future for BlockedFuture {
+    type Output = ();
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        self.num_polls.fetch_add(1, Release);
+
+        match Pin::new(&mut self.rx).poll(cx) {
+            Poll::Pending => Poll::Pending,
+            _ => Poll::Ready(()),
+        }
+    }
+}
+
+struct ResetFuture {
+    rx: Receiver<()>,
+    pending_cnt: Arc<AtomicUsize>,
+}
+
+impl Future for ResetFuture {
+    type Output = ();
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        match Pin::new(&mut self.rx).poll(cx) {
+            Poll::Pending => {
+                self.pending_cnt.fetch_add(1, Release);
+                Poll::Pending
+            }
+            _ => Poll::Ready(()),
+        }
+    }
+}
diff --git a/vendor/tokio/src/runtime/tests/loom_join_set.rs b/vendor/tokio/src/runtime/tests/loom_join_set.rs
new file mode 100644
index 000000000..bd343876a
--- /dev/null
+++ b/vendor/tokio/src/runtime/tests/loom_join_set.rs
@@ -0,0 +1,82 @@
+use crate::runtime::Builder;
+use crate::task::JoinSet;
+
+#[test]
+fn test_join_set() {
+    loom::model(|| {
+        let rt = Builder::new_multi_thread()
+            .worker_threads(1)
+            .build()
+            .unwrap();
+        let mut set = JoinSet::new();
+
+        rt.block_on(async {
+            assert_eq!(set.len(), 0);
+            set.spawn(async { () });
+            assert_eq!(set.len(), 1);
+            set.spawn(async { () });
+            assert_eq!(set.len(), 2);
+            let () = set.join_next().await.unwrap().unwrap();
+            assert_eq!(set.len(), 1);
+            set.spawn(async { () });
+            assert_eq!(set.len(), 2);
+            let () = set.join_next().await.unwrap().unwrap();
+            assert_eq!(set.len(), 1);
+            let () = set.join_next().await.unwrap().unwrap();
+            assert_eq!(set.len(), 0);
+            set.spawn(async { () });
+            assert_eq!(set.len(), 1);
+        });
+
+        drop(set);
+        drop(rt);
+    });
+}
+
+#[test]
+fn abort_all_during_completion() {
+    use std::sync::{
+        atomic::{AtomicBool, Ordering::SeqCst},
+        Arc,
+    };
+
+    // These booleans assert that at least one execution had the task complete first, and that at
+    // least one execution had the task be cancelled before it completed.
+    let complete_happened = Arc::new(AtomicBool::new(false));
+    let cancel_happened = Arc::new(AtomicBool::new(false));
+
+    {
+        let complete_happened = complete_happened.clone();
+        let cancel_happened = cancel_happened.clone();
+        loom::model(move || {
+            let rt = Builder::new_multi_thread()
+                .worker_threads(1)
+                .build()
+                .unwrap();
+
+            let mut set = JoinSet::new();
+
+            rt.block_on(async {
+                set.spawn(async { () });
+                set.abort_all();
+
+                match set.join_next().await {
+                    Some(Ok(())) => complete_happened.store(true, SeqCst),
+                    Some(Err(err)) if err.is_cancelled() => cancel_happened.store(true, SeqCst),
+                    Some(Err(err)) => panic!("fail: {}", err),
+                    None => {
+                        unreachable!("Aborting the task does not remove it from the JoinSet.")
+                    }
+                }
+
+                assert!(matches!(set.join_next().await, None));
+            });
+
+            drop(set);
+            drop(rt);
+        });
+    }
+
+    assert!(complete_happened.load(SeqCst));
+    assert!(cancel_happened.load(SeqCst));
+}
diff --git a/vendor/tokio/src/runtime/tests/loom_pool.rs b/vendor/tokio/src/runtime/tests/loom_pool.rs
index 06ad6412f..fb42e1eb4 100644
--- a/vendor/tokio/src/runtime/tests/loom_pool.rs
+++ b/vendor/tokio/src/runtime/tests/loom_pool.rs
@@ -11,7 +11,7 @@ use crate::{spawn, task};
 use tokio_test::assert_ok;
 
 use loom::sync::atomic::{AtomicBool, AtomicUsize};
-use loom::sync::{Arc, Mutex};
+use loom::sync::Arc;
 
 use pin_project_lite::pin_project;
 use std::future::Future;
@@ -19,6 +19,57 @@ use std::pin::Pin;
 use std::sync::atomic::Ordering::{Relaxed, SeqCst};
 use std::task::{Context, Poll};
 
+mod atomic_take {
+    use loom::sync::atomic::AtomicBool;
+    use std::mem::MaybeUninit;
+    use std::sync::atomic::Ordering::SeqCst;
+
+    pub(super) struct AtomicTake<T> {
+        inner: MaybeUninit<T>,
+        taken: AtomicBool,
+    }
+
+    impl<T> AtomicTake<T> {
+        pub(super) fn new(value: T) -> Self {
+            Self {
+                inner: MaybeUninit::new(value),
+                taken: AtomicBool::new(false),
+            }
+        }
+
+        pub(super) fn take(&self) -> Option<T> {
+            // safety: Only one thread will see the boolean change from false
+            // to true, so that thread is able to take the value.
+            match self.taken.fetch_or(true, SeqCst) {
+                false => unsafe { Some(std::ptr::read(self.inner.as_ptr())) },
+                true => None,
+            }
+        }
+    }
+
+    impl<T> Drop for AtomicTake<T> {
+        fn drop(&mut self) {
+            drop(self.take());
+        }
+    }
+}
+
+#[derive(Clone)]
+struct AtomicOneshot<T> {
+    value: std::sync::Arc<atomic_take::AtomicTake<oneshot::Sender<T>>>,
+}
+impl<T> AtomicOneshot<T> {
+    fn new(sender: oneshot::Sender<T>) -> Self {
+        Self {
+            value: std::sync::Arc::new(atomic_take::AtomicTake::new(sender)),
+        }
+    }
+
+    fn assert_send(&self, value: T) {
+        self.value.take().unwrap().send(value);
+    }
+}
+
 /// Tests are divided into groups to make the runs faster on CI.
 mod group_a {
     use super::*;
@@ -52,7 +103,7 @@ mod group_a {
             let c1 = Arc::new(AtomicUsize::new(0));
 
             let (tx, rx) = oneshot::channel();
-            let tx1 = Arc::new(Mutex::new(Some(tx)));
+            let tx1 = AtomicOneshot::new(tx);
 
             // Spawn a task
             let c2 = c1.clone();
@@ -60,7 +111,7 @@ mod group_a {
             pool.spawn(track(async move {
                 spawn(track(async move {
                     if 1 == c1.fetch_add(1, Relaxed) {
-                        tx1.lock().unwrap().take().unwrap().send(());
+                        tx1.assert_send(());
                     }
                 }));
             }));
@@ -69,7 +120,7 @@ mod group_a {
             pool.spawn(track(async move {
                 spawn(track(async move {
                     if 1 == c2.fetch_add(1, Relaxed) {
-                        tx2.lock().unwrap().take().unwrap().send(());
+                        tx2.assert_send(());
                     }
                 }));
             }));
@@ -119,7 +170,7 @@ mod group_b {
 
             let (block_tx, block_rx) = oneshot::channel();
             let (done_tx, done_rx) = oneshot::channel();
-            let done_tx = Arc::new(Mutex::new(Some(done_tx)));
+            let done_tx = AtomicOneshot::new(done_tx);
 
             pool.spawn(track(async move {
                 crate::task::block_in_place(move || {
@@ -136,7 +187,7 @@ mod group_b {
 
                 pool.spawn(track(async move {
                     if NUM == cnt.fetch_add(1, Relaxed) + 1 {
-                        done_tx.lock().unwrap().take().unwrap().send(());
+                        done_tx.assert_send(());
                     }
                 }));
             }
@@ -159,23 +210,6 @@ mod group_b {
     }
 
     #[test]
-    fn pool_shutdown() {
-        loom::model(|| {
-            let pool = mk_pool(2);
-
-            pool.spawn(track(async move {
-                gated2(true).await;
-            }));
-
-            pool.spawn(track(async move {
-                gated2(false).await;
-            }));
-
-            drop(pool);
-        });
-    }
-
-    #[test]
     fn join_output() {
         loom::model(|| {
             let rt = mk_pool(1);
@@ -223,10 +257,6 @@ mod group_b {
             });
         });
     }
-}
-
-mod group_c {
-    use super::*;
 
     #[test]
     fn shutdown_with_notification() {
@@ -255,6 +285,27 @@ mod group_c {
     }
 }
 
+mod group_c {
+    use super::*;
+
+    #[test]
+    fn pool_shutdown() {
+        loom::model(|| {
+            let pool = mk_pool(2);
+
+            pool.spawn(track(async move {
+                gated2(true).await;
+            }));
+
+            pool.spawn(track(async move {
+                gated2(false).await;
+            }));
+
+            drop(pool);
+        });
+    }
+}
+
 mod group_d {
     use super::*;
 
@@ -266,27 +317,25 @@ mod group_d {
             let c1 = Arc::new(AtomicUsize::new(0));
 
             let (done_tx, done_rx) = oneshot::channel();
-            let done_tx1 = Arc::new(Mutex::new(Some(done_tx)));
+            let done_tx1 = AtomicOneshot::new(done_tx);
+            let done_tx2 = done_tx1.clone();
 
             // Spawn a task
             let c2 = c1.clone();
-            let done_tx2 = done_tx1.clone();
             pool.spawn(track(async move {
-                gated().await;
-                gated().await;
+                multi_gated().await;
 
                 if 1 == c1.fetch_add(1, Relaxed) {
-                    done_tx1.lock().unwrap().take().unwrap().send(());
+                    done_tx1.assert_send(());
                 }
             }));
 
             // Spawn a second task
             pool.spawn(track(async move {
-                gated().await;
-                gated().await;
+                multi_gated().await;
 
                 if 1 == c2.fetch_add(1, Relaxed) {
-                    done_tx2.lock().unwrap().take().unwrap().send(());
+                    done_tx2.assert_send(());
                 }
             }));
 
@@ -298,14 +347,12 @@ mod group_d {
 fn mk_pool(num_threads: usize) -> Runtime {
     runtime::Builder::new_multi_thread()
         .worker_threads(num_threads)
+        // Set the intervals to avoid tuning logic
+        .event_interval(2)
         .build()
         .unwrap()
 }
 
-fn gated() -> impl Future<Output = &'static str> {
-    gated2(false)
-}
-
 fn gated2(thread: bool) -> impl Future<Output = &'static str> {
     use loom::thread;
     use std::sync::Arc;
@@ -343,6 +390,38 @@ fn gated2(thread: bool) -> impl Future<Output = &'static str> {
     })
 }
 
+async fn multi_gated() {
+    struct Gate {
+        waker: loom::future::AtomicWaker,
+        count: AtomicUsize,
+    }
+
+    let gate = Arc::new(Gate {
+        waker: loom::future::AtomicWaker::new(),
+        count: AtomicUsize::new(0),
+    });
+
+    {
+        let gate = gate.clone();
+        spawn(track(async move {
+            for i in 1..3 {
+                gate.count.store(i, SeqCst);
+                gate.waker.wake();
+            }
+        }));
+    }
+
+    poll_fn(move |cx| {
+        if gate.count.load(SeqCst) < 2 {
+            gate.waker.register_by_ref(cx.waker());
+            Poll::Pending
+        } else {
+            Poll::Ready(())
+        }
+    })
+    .await;
+}
+
 fn track<T: Future>(f: T) -> Track<T> {
     Track {
         inner: f,
diff --git a/vendor/tokio/src/runtime/tests/loom_queue.rs b/vendor/tokio/src/runtime/tests/loom_queue.rs
index 34da7fd66..b60e039b9 100644
--- a/vendor/tokio/src/runtime/tests/loom_queue.rs
+++ b/vendor/tokio/src/runtime/tests/loom_queue.rs
@@ -1,20 +1,27 @@
-use crate::runtime::queue;
-use crate::runtime::task::{self, Schedule, Task};
+use crate::runtime::scheduler::multi_thread::{queue, Stats};
+use crate::runtime::tests::NoopSchedule;
 
 use loom::thread;
+use std::cell::RefCell;
+
+fn new_stats() -> Stats {
+    Stats::new(&crate::runtime::WorkerMetrics::new())
+}
 
 #[test]
 fn basic() {
     loom::model(|| {
         let (steal, mut local) = queue::local();
-        let inject = queue::Inject::new();
+        let inject = RefCell::new(vec![]);
+        let mut stats = new_stats();
 
         let th = thread::spawn(move || {
+            let mut stats = new_stats();
             let (_, mut local) = queue::local();
             let mut n = 0;
 
             for _ in 0..3 {
-                if steal.steal_into(&mut local).is_some() {
+                if steal.steal_into(&mut local, &mut stats).is_some() {
                     n += 1;
                 }
 
@@ -30,8 +37,8 @@ fn basic() {
 
         for _ in 0..2 {
             for _ in 0..2 {
-                let (task, _) = super::joinable::<_, Runtime>(async {});
-                local.push_back(task, &inject);
+                let (task, _) = super::unowned(async {});
+                local.push_back_or_overflow(task, &inject, &mut stats);
             }
 
             if local.pop().is_some() {
@@ -39,17 +46,15 @@ fn basic() {
             }
 
             // Push another task
-            let (task, _) = super::joinable::<_, Runtime>(async {});
-            local.push_back(task, &inject);
+            let (task, _) = super::unowned(async {});
+            local.push_back_or_overflow(task, &inject, &mut stats);
 
             while local.pop().is_some() {
                 n += 1;
             }
         }
 
-        while inject.pop().is_some() {
-            n += 1;
-        }
+        n += inject.borrow_mut().drain(..).count();
 
         n += th.join().unwrap();
 
@@ -61,13 +66,15 @@ fn basic() {
 fn steal_overflow() {
     loom::model(|| {
         let (steal, mut local) = queue::local();
-        let inject = queue::Inject::new();
+        let inject = RefCell::new(vec![]);
+        let mut stats = new_stats();
 
         let th = thread::spawn(move || {
+            let mut stats = new_stats();
             let (_, mut local) = queue::local();
             let mut n = 0;
 
-            if steal.steal_into(&mut local).is_some() {
+            if steal.steal_into(&mut local, &mut stats).is_some() {
                 n += 1;
             }
 
@@ -81,16 +88,16 @@ fn steal_overflow() {
         let mut n = 0;
 
         // push a task, pop a task
-        let (task, _) = super::joinable::<_, Runtime>(async {});
-        local.push_back(task, &inject);
+        let (task, _) = super::unowned(async {});
+        local.push_back_or_overflow(task, &inject, &mut stats);
 
         if local.pop().is_some() {
             n += 1;
         }
 
         for _ in 0..6 {
-            let (task, _) = super::joinable::<_, Runtime>(async {});
-            local.push_back(task, &inject);
+            let (task, _) = super::unowned(async {});
+            local.push_back_or_overflow(task, &inject, &mut stats);
         }
 
         n += th.join().unwrap();
@@ -99,9 +106,7 @@ fn steal_overflow() {
             n += 1;
         }
 
-        while inject.pop().is_some() {
-            n += 1;
-        }
+        n += inject.borrow_mut().drain(..).count();
 
         assert_eq!(7, n);
     });
@@ -111,10 +116,11 @@ fn steal_overflow() {
 fn multi_stealer() {
     const NUM_TASKS: usize = 5;
 
-    fn steal_tasks(steal: queue::Steal<Runtime>) -> usize {
+    fn steal_tasks(steal: queue::Steal<NoopSchedule>) -> usize {
+        let mut stats = new_stats();
         let (_, mut local) = queue::local();
 
-        if steal.steal_into(&mut local).is_none() {
+        if steal.steal_into(&mut local, &mut stats).is_none() {
             return 0;
         }
 
@@ -129,12 +135,13 @@ fn multi_stealer() {
 
     loom::model(|| {
         let (steal, mut local) = queue::local();
-        let inject = queue::Inject::new();
+        let inject = RefCell::new(vec![]);
+        let mut stats = new_stats();
 
         // Push work
         for _ in 0..NUM_TASKS {
-            let (task, _) = super::joinable::<_, Runtime>(async {});
-            local.push_back(task, &inject);
+            let (task, _) = super::unowned(async {});
+            local.push_back_or_overflow(task, &inject, &mut stats);
         }
 
         let th1 = {
@@ -150,9 +157,7 @@ fn multi_stealer() {
             n += 1;
         }
 
-        while inject.pop().is_some() {
-            n += 1;
-        }
+        n += inject.borrow_mut().drain(..).count();
 
         n += th1.join().unwrap();
         n += th2.join().unwrap();
@@ -164,23 +169,25 @@ fn multi_stealer() {
 #[test]
 fn chained_steal() {
     loom::model(|| {
+        let mut stats = new_stats();
         let (s1, mut l1) = queue::local();
         let (s2, mut l2) = queue::local();
-        let inject = queue::Inject::new();
+        let inject = RefCell::new(vec![]);
 
         // Load up some tasks
         for _ in 0..4 {
-            let (task, _) = super::joinable::<_, Runtime>(async {});
-            l1.push_back(task, &inject);
+            let (task, _) = super::unowned(async {});
+            l1.push_back_or_overflow(task, &inject, &mut stats);
 
-            let (task, _) = super::joinable::<_, Runtime>(async {});
-            l2.push_back(task, &inject);
+            let (task, _) = super::unowned(async {});
+            l2.push_back_or_overflow(task, &inject, &mut stats);
         }
 
         // Spawn a task to steal from **our** queue
         let th = thread::spawn(move || {
+            let mut stats = new_stats();
             let (_, mut local) = queue::local();
-            s1.steal_into(&mut local);
+            s1.steal_into(&mut local, &mut stats);
 
             while local.pop().is_some() {}
         });
@@ -188,29 +195,11 @@ fn chained_steal() {
         // Drain our tasks, then attempt to steal
         while l1.pop().is_some() {}
 
-        s2.steal_into(&mut l1);
+        s2.steal_into(&mut l1, &mut stats);
 
         th.join().unwrap();
 
         while l1.pop().is_some() {}
         while l2.pop().is_some() {}
-        while inject.pop().is_some() {}
     });
 }
-
-struct Runtime;
-
-impl Schedule for Runtime {
-    fn bind(task: Task<Self>) -> Runtime {
-        std::mem::forget(task);
-        Runtime
-    }
-
-    fn release(&self, _task: &Task<Self>) -> Option<Task<Self>> {
-        None
-    }
-
-    fn schedule(&self, _task: task::Notified<Self>) {
-        unreachable!();
-    }
-}
diff --git a/vendor/tokio/src/runtime/tests/loom_yield.rs b/vendor/tokio/src/runtime/tests/loom_yield.rs
new file mode 100644
index 000000000..ba506e5a4
--- /dev/null
+++ b/vendor/tokio/src/runtime/tests/loom_yield.rs
@@ -0,0 +1,37 @@
+use crate::runtime::park;
+use crate::runtime::tests::loom_oneshot as oneshot;
+use crate::runtime::{self, Runtime};
+
+#[test]
+fn yield_calls_park_before_scheduling_again() {
+    // Don't need to check all permutations
+    let mut loom = loom::model::Builder::default();
+    loom.max_permutations = Some(1);
+    loom.check(|| {
+        let rt = mk_runtime(2);
+        let (tx, rx) = oneshot::channel::<()>();
+
+        rt.spawn(async {
+            let tid = loom::thread::current().id();
+            let park_count = park::current_thread_park_count();
+
+            crate::task::yield_now().await;
+
+            if tid == loom::thread::current().id() {
+                let new_park_count = park::current_thread_park_count();
+                assert_eq!(park_count + 1, new_park_count);
+            }
+
+            tx.send(());
+        });
+
+        rx.recv();
+    });
+}
+
+fn mk_runtime(num_threads: usize) -> Runtime {
+    runtime::Builder::new_multi_thread()
+        .worker_threads(num_threads)
+        .build()
+        .unwrap()
+}
diff --git a/vendor/tokio/src/runtime/tests/mod.rs b/vendor/tokio/src/runtime/tests/mod.rs
index 3f2cc9825..b12a76e26 100644
--- a/vendor/tokio/src/runtime/tests/mod.rs
+++ b/vendor/tokio/src/runtime/tests/mod.rs
@@ -1,35 +1,73 @@
-#[cfg(not(all(tokio_unstable, feature = "tracing")))]
-use crate::runtime::task::joinable;
+// Enable dead_code / unreachable_pub here. It has been disabled in lib.rs for
+// other code when running loom tests.
+#![cfg_attr(loom, warn(dead_code, unreachable_pub))]
 
-#[cfg(all(tokio_unstable, feature = "tracing"))]
-use self::joinable_wrapper::joinable;
+use self::noop_scheduler::NoopSchedule;
+use self::unowned_wrapper::unowned;
 
-#[cfg(all(tokio_unstable, feature = "tracing"))]
-mod joinable_wrapper {
-    use crate::runtime::task::{JoinHandle, Notified, Schedule};
-    use tracing::Instrument;
+mod noop_scheduler {
+    use crate::runtime::task::{self, Task};
 
-    pub(crate) fn joinable<T, S>(task: T) -> (Notified<S>, JoinHandle<T::Output>)
+    /// `task::Schedule` implementation that does nothing, for testing.
+    pub(crate) struct NoopSchedule;
+
+    impl task::Schedule for NoopSchedule {
+        fn release(&self, _task: &Task<Self>) -> Option<Task<Self>> {
+            None
+        }
+
+        fn schedule(&self, _task: task::Notified<Self>) {
+            unreachable!();
+        }
+    }
+}
+
+mod unowned_wrapper {
+    use crate::runtime::task::{Id, JoinHandle, Notified};
+    use crate::runtime::tests::NoopSchedule;
+
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    pub(crate) fn unowned<T>(task: T) -> (Notified<NoopSchedule>, JoinHandle<T::Output>)
     where
         T: std::future::Future + Send + 'static,
-        S: Schedule,
+        T::Output: Send + 'static,
     {
+        use tracing::Instrument;
         let span = tracing::trace_span!("test_span");
-        crate::runtime::task::joinable(task.instrument(span))
+        let task = task.instrument(span);
+        let (task, handle) = crate::runtime::task::unowned(task, NoopSchedule, Id::next());
+        (task.into_notified(), handle)
+    }
+
+    #[cfg(not(all(tokio_unstable, feature = "tracing")))]
+    pub(crate) fn unowned<T>(task: T) -> (Notified<NoopSchedule>, JoinHandle<T::Output>)
+    where
+        T: std::future::Future + Send + 'static,
+        T::Output: Send + 'static,
+    {
+        let (task, handle) = crate::runtime::task::unowned(task, NoopSchedule, Id::next());
+        (task.into_notified(), handle)
     }
 }
 
 cfg_loom! {
-    mod loom_basic_scheduler;
-    mod loom_local;
     mod loom_blocking;
+    mod loom_current_thread_scheduler;
+    mod loom_local;
     mod loom_oneshot;
     mod loom_pool;
     mod loom_queue;
     mod loom_shutdown_join;
+    mod loom_join_set;
+    mod loom_yield;
+
+    // Make sure debug assertions are enabled
+    #[cfg(not(debug_assertions))]
+    compiler_error!("these tests require debug assertions to be enabled");
 }
 
 cfg_not_loom! {
+    mod inject;
     mod queue;
 
     #[cfg(not(miri))]
diff --git a/vendor/tokio/src/runtime/tests/queue.rs b/vendor/tokio/src/runtime/tests/queue.rs
index b2962f154..5df92b7a2 100644
--- a/vendor/tokio/src/runtime/tests/queue.rs
+++ b/vendor/tokio/src/runtime/tests/queue.rs
@@ -1,39 +1,107 @@
-use crate::runtime::queue;
+use crate::runtime::scheduler::multi_thread::{queue, Stats};
 use crate::runtime::task::{self, Schedule, Task};
 
+use std::cell::RefCell;
 use std::thread;
 use std::time::Duration;
 
+#[allow(unused)]
+macro_rules! assert_metrics {
+    ($stats:ident, $field:ident == $v:expr) => {{
+        use crate::runtime::WorkerMetrics;
+        use std::sync::atomic::Ordering::Relaxed;
+
+        let worker = WorkerMetrics::new();
+        $stats.submit(&worker);
+
+        let expect = $v;
+        let actual = worker.$field.load(Relaxed);
+
+        assert!(actual == expect, "expect = {}; actual = {}", expect, actual)
+    }};
+}
+
+fn new_stats() -> Stats {
+    use crate::runtime::WorkerMetrics;
+    Stats::new(&WorkerMetrics::new())
+}
+
 #[test]
-fn fits_256() {
+fn fits_256_one_at_a_time() {
     let (_, mut local) = queue::local();
-    let inject = queue::Inject::new();
+    let inject = RefCell::new(vec![]);
+    let mut stats = new_stats();
 
     for _ in 0..256 {
-        let (task, _) = super::joinable::<_, Runtime>(async {});
-        local.push_back(task, &inject);
+        let (task, _) = super::unowned(async {});
+        local.push_back_or_overflow(task, &inject, &mut stats);
     }
 
-    assert!(inject.pop().is_none());
+    cfg_metrics! {
+        assert_metrics!(stats, overflow_count == 0);
+    }
+
+    assert!(inject.borrow_mut().pop().is_none());
 
     while local.pop().is_some() {}
 }
 
 #[test]
+fn fits_256_all_at_once() {
+    let (_, mut local) = queue::local();
+
+    let mut tasks = (0..256)
+        .map(|_| super::unowned(async {}).0)
+        .collect::<Vec<_>>();
+    local.push_back(tasks.drain(..));
+
+    let mut i = 0;
+    while local.pop().is_some() {
+        i += 1;
+    }
+
+    assert_eq!(i, 256);
+}
+
+#[test]
+fn fits_256_all_in_chunks() {
+    let (_, mut local) = queue::local();
+
+    let mut tasks = (0..256)
+        .map(|_| super::unowned(async {}).0)
+        .collect::<Vec<_>>();
+
+    local.push_back(tasks.drain(..10));
+    local.push_back(tasks.drain(..100));
+    local.push_back(tasks.drain(..46));
+    local.push_back(tasks.drain(..100));
+
+    let mut i = 0;
+    while local.pop().is_some() {
+        i += 1;
+    }
+
+    assert_eq!(i, 256);
+}
+
+#[test]
 fn overflow() {
     let (_, mut local) = queue::local();
-    let inject = queue::Inject::new();
+    let inject = RefCell::new(vec![]);
+    let mut stats = new_stats();
 
     for _ in 0..257 {
-        let (task, _) = super::joinable::<_, Runtime>(async {});
-        local.push_back(task, &inject);
+        let (task, _) = super::unowned(async {});
+        local.push_back_or_overflow(task, &inject, &mut stats);
+    }
+
+    cfg_metrics! {
+        assert_metrics!(stats, overflow_count == 1);
     }
 
     let mut n = 0;
 
-    while inject.pop().is_some() {
-        n += 1;
-    }
+    n += inject.borrow_mut().drain(..).count();
 
     while local.pop().is_some() {
         n += 1;
@@ -44,16 +112,22 @@ fn overflow() {
 
 #[test]
 fn steal_batch() {
+    let mut stats = new_stats();
+
     let (steal1, mut local1) = queue::local();
     let (_, mut local2) = queue::local();
-    let inject = queue::Inject::new();
+    let inject = RefCell::new(vec![]);
 
     for _ in 0..4 {
-        let (task, _) = super::joinable::<_, Runtime>(async {});
-        local1.push_back(task, &inject);
+        let (task, _) = super::unowned(async {});
+        local1.push_back_or_overflow(task, &inject, &mut stats);
     }
 
-    assert!(steal1.steal_into(&mut local2).is_some());
+    assert!(steal1.steal_into(&mut local2, &mut stats).is_some());
+
+    cfg_metrics! {
+        assert_metrics!(stats, steal_count == 2);
+    }
 
     for _ in 0..1 {
         assert!(local2.pop().is_some());
@@ -68,24 +142,35 @@ fn steal_batch() {
     assert!(local1.pop().is_none());
 }
 
+const fn normal_or_miri(normal: usize, miri: usize) -> usize {
+    if cfg!(miri) {
+        miri
+    } else {
+        normal
+    }
+}
+
 #[test]
 fn stress1() {
-    const NUM_ITER: usize = 1;
-    const NUM_STEAL: usize = 1_000;
-    const NUM_LOCAL: usize = 1_000;
-    const NUM_PUSH: usize = 500;
-    const NUM_POP: usize = 250;
+    const NUM_ITER: usize = 5;
+    const NUM_STEAL: usize = normal_or_miri(1_000, 10);
+    const NUM_LOCAL: usize = normal_or_miri(1_000, 10);
+    const NUM_PUSH: usize = normal_or_miri(500, 10);
+    const NUM_POP: usize = normal_or_miri(250, 10);
+
+    let mut stats = new_stats();
 
     for _ in 0..NUM_ITER {
         let (steal, mut local) = queue::local();
-        let inject = queue::Inject::new();
+        let inject = RefCell::new(vec![]);
 
         let th = thread::spawn(move || {
+            let mut stats = new_stats();
             let (_, mut local) = queue::local();
             let mut n = 0;
 
             for _ in 0..NUM_STEAL {
-                if steal.steal_into(&mut local).is_some() {
+                if steal.steal_into(&mut local, &mut stats).is_some() {
                     n += 1;
                 }
 
@@ -96,6 +181,10 @@ fn stress1() {
                 thread::yield_now();
             }
 
+            cfg_metrics! {
+                assert_metrics!(stats, steal_count == n as _);
+            }
+
             n
         });
 
@@ -103,8 +192,8 @@ fn stress1() {
 
         for _ in 0..NUM_LOCAL {
             for _ in 0..NUM_PUSH {
-                let (task, _) = super::joinable::<_, Runtime>(async {});
-                local.push_back(task, &inject);
+                let (task, _) = super::unowned(async {});
+                local.push_back_or_overflow(task, &inject, &mut stats);
             }
 
             for _ in 0..NUM_POP {
@@ -116,9 +205,7 @@ fn stress1() {
             }
         }
 
-        while inject.pop().is_some() {
-            n += 1;
-        }
+        n += inject.borrow_mut().drain(..).count();
 
         n += th.join().unwrap();
 
@@ -129,19 +216,22 @@ fn stress1() {
 #[test]
 fn stress2() {
     const NUM_ITER: usize = 1;
-    const NUM_TASKS: usize = 1_000_000;
-    const NUM_STEAL: usize = 1_000;
+    const NUM_TASKS: usize = normal_or_miri(1_000_000, 50);
+    const NUM_STEAL: usize = normal_or_miri(1_000, 10);
+
+    let mut stats = new_stats();
 
     for _ in 0..NUM_ITER {
         let (steal, mut local) = queue::local();
-        let inject = queue::Inject::new();
+        let inject = RefCell::new(vec![]);
 
         let th = thread::spawn(move || {
+            let mut stats = new_stats();
             let (_, mut local) = queue::local();
             let mut n = 0;
 
             for _ in 0..NUM_STEAL {
-                if steal.steal_into(&mut local).is_some() {
+                if steal.steal_into(&mut local, &mut stats).is_some() {
                     n += 1;
                 }
 
@@ -158,16 +248,14 @@ fn stress2() {
         let mut num_pop = 0;
 
         for i in 0..NUM_TASKS {
-            let (task, _) = super::joinable::<_, Runtime>(async {});
-            local.push_back(task, &inject);
+            let (task, _) = super::unowned(async {});
+            local.push_back_or_overflow(task, &inject, &mut stats);
 
             if i % 128 == 0 && local.pop().is_some() {
                 num_pop += 1;
             }
 
-            while inject.pop().is_some() {
-                num_pop += 1;
-            }
+            num_pop += inject.borrow_mut().drain(..).count();
         }
 
         num_pop += th.join().unwrap();
@@ -176,9 +264,7 @@ fn stress2() {
             num_pop += 1;
         }
 
-        while inject.pop().is_some() {
-            num_pop += 1;
-        }
+        num_pop += inject.borrow_mut().drain(..).count();
 
         assert_eq!(num_pop, NUM_TASKS);
     }
@@ -187,11 +273,6 @@ fn stress2() {
 struct Runtime;
 
 impl Schedule for Runtime {
-    fn bind(task: Task<Self>) -> Runtime {
-        std::mem::forget(task);
-        Runtime
-    }
-
     fn release(&self, _task: &Task<Self>) -> Option<Task<Self>> {
         None
     }
diff --git a/vendor/tokio/src/runtime/tests/task.rs b/vendor/tokio/src/runtime/tests/task.rs
index 7c2012523..a79c0f50d 100644
--- a/vendor/tokio/src/runtime/tests/task.rs
+++ b/vendor/tokio/src/runtime/tests/task.rs
@@ -1,44 +1,235 @@
-use crate::runtime::task::{self, Schedule, Task};
-use crate::util::linked_list::{Link, LinkedList};
+use crate::runtime::task::{self, unowned, Id, JoinHandle, OwnedTasks, Schedule, Task};
+use crate::runtime::tests::NoopSchedule;
 use crate::util::TryLock;
 
 use std::collections::VecDeque;
+use std::future::Future;
+use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::Arc;
 
+struct AssertDropHandle {
+    is_dropped: Arc<AtomicBool>,
+}
+impl AssertDropHandle {
+    #[track_caller]
+    fn assert_dropped(&self) {
+        assert!(self.is_dropped.load(Ordering::SeqCst));
+    }
+
+    #[track_caller]
+    fn assert_not_dropped(&self) {
+        assert!(!self.is_dropped.load(Ordering::SeqCst));
+    }
+}
+
+struct AssertDrop {
+    is_dropped: Arc<AtomicBool>,
+}
+impl AssertDrop {
+    fn new() -> (Self, AssertDropHandle) {
+        let shared = Arc::new(AtomicBool::new(false));
+        (
+            AssertDrop {
+                is_dropped: shared.clone(),
+            },
+            AssertDropHandle {
+                is_dropped: shared.clone(),
+            },
+        )
+    }
+}
+impl Drop for AssertDrop {
+    fn drop(&mut self) {
+        self.is_dropped.store(true, Ordering::SeqCst);
+    }
+}
+
+// A Notified does not shut down on drop, but it is dropped once the ref-count
+// hits zero.
+#[test]
+fn create_drop1() {
+    let (ad, handle) = AssertDrop::new();
+    let (notified, join) = unowned(
+        async {
+            drop(ad);
+            unreachable!()
+        },
+        NoopSchedule,
+        Id::next(),
+    );
+    drop(notified);
+    handle.assert_not_dropped();
+    drop(join);
+    handle.assert_dropped();
+}
+
 #[test]
-fn create_drop() {
-    let _ = super::joinable::<_, Runtime>(async { unreachable!() });
+fn create_drop2() {
+    let (ad, handle) = AssertDrop::new();
+    let (notified, join) = unowned(
+        async {
+            drop(ad);
+            unreachable!()
+        },
+        NoopSchedule,
+        Id::next(),
+    );
+    drop(join);
+    handle.assert_not_dropped();
+    drop(notified);
+    handle.assert_dropped();
+}
+
+#[test]
+fn drop_abort_handle1() {
+    let (ad, handle) = AssertDrop::new();
+    let (notified, join) = unowned(
+        async {
+            drop(ad);
+            unreachable!()
+        },
+        NoopSchedule,
+        Id::next(),
+    );
+    let abort = join.abort_handle();
+    drop(join);
+    handle.assert_not_dropped();
+    drop(notified);
+    handle.assert_not_dropped();
+    drop(abort);
+    handle.assert_dropped();
+}
+
+#[test]
+fn drop_abort_handle2() {
+    let (ad, handle) = AssertDrop::new();
+    let (notified, join) = unowned(
+        async {
+            drop(ad);
+            unreachable!()
+        },
+        NoopSchedule,
+        Id::next(),
+    );
+    let abort = join.abort_handle();
+    drop(notified);
+    handle.assert_not_dropped();
+    drop(abort);
+    handle.assert_not_dropped();
+    drop(join);
+    handle.assert_dropped();
+}
+
+// Shutting down through Notified works
+#[test]
+fn create_shutdown1() {
+    let (ad, handle) = AssertDrop::new();
+    let (notified, join) = unowned(
+        async {
+            drop(ad);
+            unreachable!()
+        },
+        NoopSchedule,
+        Id::next(),
+    );
+    drop(join);
+    handle.assert_not_dropped();
+    notified.shutdown();
+    handle.assert_dropped();
+}
+
+#[test]
+fn create_shutdown2() {
+    let (ad, handle) = AssertDrop::new();
+    let (notified, join) = unowned(
+        async {
+            drop(ad);
+            unreachable!()
+        },
+        NoopSchedule,
+        Id::next(),
+    );
+    handle.assert_not_dropped();
+    notified.shutdown();
+    handle.assert_dropped();
+    drop(join);
+}
+
+#[test]
+fn unowned_poll() {
+    let (task, _) = unowned(async {}, NoopSchedule, Id::next());
+    task.run();
 }
 
 #[test]
 fn schedule() {
     with(|rt| {
-        let (task, _) = super::joinable(async {
+        rt.spawn(async {
             crate::task::yield_now().await;
         });
 
-        rt.schedule(task);
-
         assert_eq!(2, rt.tick());
+        rt.shutdown();
     })
 }
 
 #[test]
 fn shutdown() {
     with(|rt| {
-        let (task, _) = super::joinable(async {
+        rt.spawn(async {
             loop {
                 crate::task::yield_now().await;
             }
         });
 
-        rt.schedule(task);
         rt.tick_max(1);
 
         rt.shutdown();
     })
 }
 
+#[test]
+fn shutdown_immediately() {
+    with(|rt| {
+        rt.spawn(async {
+            loop {
+                crate::task::yield_now().await;
+            }
+        });
+
+        rt.shutdown();
+    })
+}
+
+#[test]
+fn spawn_during_shutdown() {
+    static DID_SPAWN: AtomicBool = AtomicBool::new(false);
+
+    struct SpawnOnDrop(Runtime);
+    impl Drop for SpawnOnDrop {
+        fn drop(&mut self) {
+            DID_SPAWN.store(true, Ordering::SeqCst);
+            self.0.spawn(async {});
+        }
+    }
+
+    with(|rt| {
+        let rt2 = rt.clone();
+        rt.spawn(async move {
+            let _spawn_on_drop = SpawnOnDrop(rt2);
+
+            loop {
+                crate::task::yield_now().await;
+            }
+        });
+
+        rt.tick_max(1);
+        rt.shutdown();
+    });
+
+    assert!(DID_SPAWN.load(Ordering::SeqCst));
+}
+
 fn with(f: impl FnOnce(Runtime)) {
     struct Reset;
 
@@ -51,10 +242,9 @@ fn with(f: impl FnOnce(Runtime)) {
     let _reset = Reset;
 
     let rt = Runtime(Arc::new(Inner {
-        released: task::TransferStack::new(),
+        owned: OwnedTasks::new(),
         core: TryLock::new(Core {
             queue: VecDeque::new(),
-            tasks: LinkedList::new(),
         }),
     }));
 
@@ -66,18 +256,31 @@ fn with(f: impl FnOnce(Runtime)) {
 struct Runtime(Arc<Inner>);
 
 struct Inner {
-    released: task::TransferStack<Runtime>,
     core: TryLock<Core>,
+    owned: OwnedTasks<Runtime>,
 }
 
 struct Core {
     queue: VecDeque<task::Notified<Runtime>>,
-    tasks: LinkedList<Task<Runtime>, <Task<Runtime> as Link>::Target>,
 }
 
 static CURRENT: TryLock<Option<Runtime>> = TryLock::new(None);
 
 impl Runtime {
+    fn spawn<T>(&self, future: T) -> JoinHandle<T::Output>
+    where
+        T: 'static + Send + Future,
+        T::Output: 'static + Send,
+    {
+        let (handle, notified) = self.0.owned.bind(future, self.clone(), Id::next());
+
+        if let Some(notified) = notified {
+            self.schedule(notified);
+        }
+
+        handle
+    }
+
     fn tick(&self) -> usize {
         self.tick_max(usize::MAX)
     }
@@ -88,11 +291,10 @@ impl Runtime {
         while !self.is_empty() && n < max {
             let task = self.next_task();
             n += 1;
+            let task = self.0.owned.assert_owner(task);
             task.run();
         }
 
-        self.0.maintenance();
-
         n
     }
 
@@ -107,50 +309,21 @@ impl Runtime {
     fn shutdown(&self) {
         let mut core = self.0.core.try_lock().unwrap();
 
-        for task in core.tasks.iter() {
-            task.shutdown();
-        }
+        self.0.owned.close_and_shutdown_all();
 
         while let Some(task) = core.queue.pop_back() {
-            task.shutdown();
+            drop(task);
         }
 
         drop(core);
 
-        while !self.0.core.try_lock().unwrap().tasks.is_empty() {
-            self.0.maintenance();
-        }
-    }
-}
-
-impl Inner {
-    fn maintenance(&self) {
-        use std::mem::ManuallyDrop;
-
-        for task in self.released.drain() {
-            let task = ManuallyDrop::new(task);
-
-            // safety: see worker.rs
-            unsafe {
-                let ptr = task.header().into();
-                self.core.try_lock().unwrap().tasks.remove(ptr);
-            }
-        }
+        assert!(self.0.owned.is_empty());
     }
 }
 
 impl Schedule for Runtime {
-    fn bind(task: Task<Self>) -> Runtime {
-        let rt = CURRENT.try_lock().unwrap().as_ref().unwrap().clone();
-        rt.0.core.try_lock().unwrap().tasks.push_front(task);
-        rt
-    }
-
     fn release(&self, task: &Task<Self>) -> Option<Task<Self>> {
-        // safety: copying worker.rs
-        let task = unsafe { Task::from_raw(task.header().into()) };
-        self.0.released.push(task);
-        None
+        self.0.owned.remove(task)
     }
 
     fn schedule(&self, task: task::Notified<Self>) {
diff --git a/vendor/tokio/src/runtime/tests/task_combinations.rs b/vendor/tokio/src/runtime/tests/task_combinations.rs
index 76ce2330c..73a20d976 100644
--- a/vendor/tokio/src/runtime/tests/task_combinations.rs
+++ b/vendor/tokio/src/runtime/tests/task_combinations.rs
@@ -1,8 +1,10 @@
+use std::fmt;
 use std::future::Future;
 use std::panic;
 use std::pin::Pin;
 use std::task::{Context, Poll};
 
+use crate::runtime::task::AbortHandle;
 use crate::runtime::Builder;
 use crate::sync::oneshot;
 use crate::task::JoinHandle;
@@ -56,6 +58,12 @@ enum CombiAbort {
     AbortedAfterConsumeOutput = 4,
 }
 
+#[derive(Copy, Clone, Debug, PartialEq)]
+enum CombiAbortSource {
+    JoinHandle,
+    AbortHandle,
+}
+
 #[test]
 fn test_combinations() {
     let mut rt = &[
@@ -90,6 +98,13 @@ fn test_combinations() {
         CombiAbort::AbortedAfterFinish,
         CombiAbort::AbortedAfterConsumeOutput,
     ];
+    let ah = [
+        None,
+        Some(CombiJoinHandle::DropImmediately),
+        Some(CombiJoinHandle::DropFirstPoll),
+        Some(CombiJoinHandle::DropAfterNoConsume),
+        Some(CombiJoinHandle::DropAfterConsume),
+    ];
 
     for rt in rt.iter().copied() {
         for ls in ls.iter().copied() {
@@ -98,7 +113,34 @@ fn test_combinations() {
                     for ji in ji.iter().copied() {
                         for jh in jh.iter().copied() {
                             for abort in abort.iter().copied() {
-                                test_combination(rt, ls, task, output, ji, jh, abort);
+                                // abort via join handle --- abort  handles
+                                // may be dropped at any point
+                                for ah in ah.iter().copied() {
+                                    test_combination(
+                                        rt,
+                                        ls,
+                                        task,
+                                        output,
+                                        ji,
+                                        jh,
+                                        ah,
+                                        abort,
+                                        CombiAbortSource::JoinHandle,
+                                    );
+                                }
+                                // if aborting via AbortHandle, it will
+                                // never be dropped.
+                                test_combination(
+                                    rt,
+                                    ls,
+                                    task,
+                                    output,
+                                    ji,
+                                    jh,
+                                    None,
+                                    abort,
+                                    CombiAbortSource::AbortHandle,
+                                );
                             }
                         }
                     }
@@ -108,6 +150,9 @@ fn test_combinations() {
     }
 }
 
+fn is_debug<T: fmt::Debug>(_: &T) {}
+
+#[allow(clippy::too_many_arguments)]
 fn test_combination(
     rt: CombiRuntime,
     ls: CombiLocalSet,
@@ -115,12 +160,24 @@ fn test_combination(
     output: CombiOutput,
     ji: CombiJoinInterest,
     jh: CombiJoinHandle,
+    ah: Option<CombiJoinHandle>,
     abort: CombiAbort,
+    abort_src: CombiAbortSource,
 ) {
-    if (jh as usize) < (abort as usize) {
-        // drop before abort not possible
-        return;
+    match (abort_src, ah) {
+        (CombiAbortSource::JoinHandle, _) if (jh as usize) < (abort as usize) => {
+            // join handle dropped prior to abort
+            return;
+        }
+        (CombiAbortSource::AbortHandle, Some(_)) => {
+            // abort handle dropped, we can't abort through the
+            // abort handle
+            return;
+        }
+
+        _ => {}
     }
+
     if (task == CombiTask::PanicOnDrop) && (output == CombiOutput::PanicOnDrop) {
         // this causes double panic
         return;
@@ -130,7 +187,15 @@ fn test_combination(
         return;
     }
 
-    println!("Runtime {:?}, LocalSet {:?}, Task {:?}, Output {:?}, JoinInterest {:?}, JoinHandle {:?}, Abort {:?}", rt, ls, task, output, ji, jh, abort);
+    is_debug(&rt);
+    is_debug(&ls);
+    is_debug(&task);
+    is_debug(&output);
+    is_debug(&ji);
+    is_debug(&jh);
+    is_debug(&ah);
+    is_debug(&abort);
+    is_debug(&abort_src);
 
     // A runtime optionally with a LocalSet
     struct Rt {
@@ -282,8 +347,24 @@ fn test_combination(
         );
     }
 
+    // If we are either aborting the task via an abort handle, or dropping via
+    // an abort handle, do that now.
+    let mut abort_handle = if ah.is_some() || abort_src == CombiAbortSource::AbortHandle {
+        handle.as_ref().map(JoinHandle::abort_handle)
+    } else {
+        None
+    };
+
+    let do_abort = |abort_handle: &mut Option<AbortHandle>,
+                    join_handle: Option<&mut JoinHandle<_>>| {
+        match abort_src {
+            CombiAbortSource::AbortHandle => abort_handle.take().unwrap().abort(),
+            CombiAbortSource::JoinHandle => join_handle.unwrap().abort(),
+        }
+    };
+
     if abort == CombiAbort::AbortedImmediately {
-        handle.as_mut().unwrap().abort();
+        do_abort(&mut abort_handle, handle.as_mut());
         aborted = true;
     }
     if jh == CombiJoinHandle::DropImmediately {
@@ -301,12 +382,15 @@ fn test_combination(
     }
 
     if abort == CombiAbort::AbortedFirstPoll {
-        handle.as_mut().unwrap().abort();
+        do_abort(&mut abort_handle, handle.as_mut());
         aborted = true;
     }
     if jh == CombiJoinHandle::DropFirstPoll {
         drop(handle.take().unwrap());
     }
+    if ah == Some(CombiJoinHandle::DropFirstPoll) {
+        drop(abort_handle.take().unwrap());
+    }
 
     // Signal the future that it can return now
     let _ = on_complete.send(());
@@ -318,23 +402,42 @@ fn test_combination(
 
     if abort == CombiAbort::AbortedAfterFinish {
         // Don't set aborted to true here as the task already finished
-        handle.as_mut().unwrap().abort();
+        do_abort(&mut abort_handle, handle.as_mut());
     }
     if jh == CombiJoinHandle::DropAfterNoConsume {
-        // The runtime will usually have dropped every ref-count at this point,
-        // in which case dropping the JoinHandle drops the output.
-        //
-        // (But it might race and still hold a ref-count)
-        let panic = panic::catch_unwind(panic::AssertUnwindSafe(|| {
+        if ah == Some(CombiJoinHandle::DropAfterNoConsume) {
             drop(handle.take().unwrap());
-        }));
-        if panic.is_err() {
-            assert!(
-                (output == CombiOutput::PanicOnDrop)
-                    && (!matches!(task, CombiTask::PanicOnRun | CombiTask::PanicOnRunAndDrop))
-                    && !aborted,
-                "Dropping JoinHandle shouldn't panic here"
-            );
+            // The runtime will usually have dropped every ref-count at this point,
+            // in which case dropping the AbortHandle drops the output.
+            //
+            // (But it might race and still hold a ref-count)
+            let panic = panic::catch_unwind(panic::AssertUnwindSafe(|| {
+                drop(abort_handle.take().unwrap());
+            }));
+            if panic.is_err() {
+                assert!(
+                    (output == CombiOutput::PanicOnDrop)
+                        && (!matches!(task, CombiTask::PanicOnRun | CombiTask::PanicOnRunAndDrop))
+                        && !aborted,
+                    "Dropping AbortHandle shouldn't panic here"
+                );
+            }
+        } else {
+            // The runtime will usually have dropped every ref-count at this point,
+            // in which case dropping the JoinHandle drops the output.
+            //
+            // (But it might race and still hold a ref-count)
+            let panic = panic::catch_unwind(panic::AssertUnwindSafe(|| {
+                drop(handle.take().unwrap());
+            }));
+            if panic.is_err() {
+                assert!(
+                    (output == CombiOutput::PanicOnDrop)
+                        && (!matches!(task, CombiTask::PanicOnRun | CombiTask::PanicOnRunAndDrop))
+                        && !aborted,
+                    "Dropping JoinHandle shouldn't panic here"
+                );
+            }
         }
     }
 
@@ -362,11 +465,15 @@ fn test_combination(
             _ => unreachable!(),
         }
 
-        let handle = handle.take().unwrap();
+        let mut handle = handle.take().unwrap();
         if abort == CombiAbort::AbortedAfterConsumeOutput {
-            handle.abort();
+            do_abort(&mut abort_handle, Some(&mut handle));
         }
         drop(handle);
+
+        if ah == Some(CombiJoinHandle::DropAfterConsume) {
+            drop(abort_handle.take());
+        }
     }
 
     // The output should have been dropped now. Check whether the output
diff --git a/vendor/tokio/src/runtime/thread_id.rs b/vendor/tokio/src/runtime/thread_id.rs
new file mode 100644
index 000000000..ef3928979
--- /dev/null
+++ b/vendor/tokio/src/runtime/thread_id.rs
@@ -0,0 +1,31 @@
+use std::num::NonZeroU64;
+
+#[derive(Eq, PartialEq, Clone, Copy, Hash, Debug)]
+pub(crate) struct ThreadId(NonZeroU64);
+
+impl ThreadId {
+    pub(crate) fn next() -> Self {
+        use crate::loom::sync::atomic::{Ordering::Relaxed, StaticAtomicU64};
+
+        static NEXT_ID: StaticAtomicU64 = StaticAtomicU64::new(0);
+
+        let mut last = NEXT_ID.load(Relaxed);
+        loop {
+            let id = match last.checked_add(1) {
+                Some(id) => id,
+                None => exhausted(),
+            };
+
+            match NEXT_ID.compare_exchange_weak(last, id, Relaxed, Relaxed) {
+                Ok(_) => return ThreadId(NonZeroU64::new(id).unwrap()),
+                Err(id) => last = id,
+            }
+        }
+    }
+}
+
+#[cold]
+#[allow(dead_code)]
+fn exhausted() -> ! {
+    panic!("failed to generate unique thread ID: bitspace exhausted")
+}
diff --git a/vendor/tokio/src/runtime/thread_pool/mod.rs b/vendor/tokio/src/runtime/thread_pool/mod.rs
deleted file mode 100644
index 96312d346..000000000
--- a/vendor/tokio/src/runtime/thread_pool/mod.rs
+++ /dev/null
@@ -1,116 +0,0 @@
-//! Threadpool
-
-mod atomic_cell;
-use atomic_cell::AtomicCell;
-
-mod idle;
-use self::idle::Idle;
-
-mod worker;
-pub(crate) use worker::Launch;
-
-pub(crate) use worker::block_in_place;
-
-use crate::loom::sync::Arc;
-use crate::runtime::task::{self, JoinHandle};
-use crate::runtime::Parker;
-
-use std::fmt;
-use std::future::Future;
-
-/// Work-stealing based thread pool for executing futures.
-pub(crate) struct ThreadPool {
-    spawner: Spawner,
-}
-
-/// Submit futures to the associated thread pool for execution.
-///
-/// A `Spawner` instance is a handle to a single thread pool that allows the owner
-/// of the handle to spawn futures onto the thread pool.
-///
-/// The `Spawner` handle is *only* used for spawning new futures. It does not
-/// impact the lifecycle of the thread pool in any way. The thread pool may
-/// shutdown while there are outstanding `Spawner` instances.
-///
-/// `Spawner` instances are obtained by calling [`ThreadPool::spawner`].
-///
-/// [`ThreadPool::spawner`]: method@ThreadPool::spawner
-#[derive(Clone)]
-pub(crate) struct Spawner {
-    shared: Arc<worker::Shared>,
-}
-
-// ===== impl ThreadPool =====
-
-impl ThreadPool {
-    pub(crate) fn new(size: usize, parker: Parker) -> (ThreadPool, Launch) {
-        let (shared, launch) = worker::create(size, parker);
-        let spawner = Spawner { shared };
-        let thread_pool = ThreadPool { spawner };
-
-        (thread_pool, launch)
-    }
-
-    /// Returns reference to `Spawner`.
-    ///
-    /// The `Spawner` handle can be cloned and enables spawning tasks from other
-    /// threads.
-    pub(crate) fn spawner(&self) -> &Spawner {
-        &self.spawner
-    }
-
-    /// Blocks the current thread waiting for the future to complete.
-    ///
-    /// The future will execute on the current thread, but all spawned tasks
-    /// will be executed on the thread pool.
-    pub(crate) fn block_on<F>(&self, future: F) -> F::Output
-    where
-        F: Future,
-    {
-        let mut enter = crate::runtime::enter(true);
-        enter.block_on(future).expect("failed to park thread")
-    }
-}
-
-impl fmt::Debug for ThreadPool {
-    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt.debug_struct("ThreadPool").finish()
-    }
-}
-
-impl Drop for ThreadPool {
-    fn drop(&mut self) {
-        self.spawner.shutdown();
-    }
-}
-
-// ==== impl Spawner =====
-
-impl Spawner {
-    /// Spawns a future onto the thread pool
-    pub(crate) fn spawn<F>(&self, future: F) -> JoinHandle<F::Output>
-    where
-        F: crate::future::Future + Send + 'static,
-        F::Output: Send + 'static,
-    {
-        let (task, handle) = task::joinable(future);
-
-        if let Err(task) = self.shared.schedule(task, false) {
-            // The newly spawned task could not be scheduled because the runtime
-            // is shutting down. The task must be explicitly shutdown at this point.
-            task.shutdown();
-        }
-
-        handle
-    }
-
-    pub(crate) fn shutdown(&mut self) {
-        self.shared.close();
-    }
-}
-
-impl fmt::Debug for Spawner {
-    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt.debug_struct("Spawner").finish()
-    }
-}
diff --git a/vendor/tokio/src/runtime/thread_pool/worker.rs b/vendor/tokio/src/runtime/thread_pool/worker.rs
deleted file mode 100644
index 70cbddbd0..000000000
--- a/vendor/tokio/src/runtime/thread_pool/worker.rs
+++ /dev/null
@@ -1,841 +0,0 @@
-//! A scheduler is initialized with a fixed number of workers. Each worker is
-//! driven by a thread. Each worker has a "core" which contains data such as the
-//! run queue and other state. When `block_in_place` is called, the worker's
-//! "core" is handed off to a new thread allowing the scheduler to continue to
-//! make progress while the originating thread blocks.
-
-use crate::coop;
-use crate::loom::rand::seed;
-use crate::loom::sync::{Arc, Mutex};
-use crate::park::{Park, Unpark};
-use crate::runtime;
-use crate::runtime::enter::EnterContext;
-use crate::runtime::park::{Parker, Unparker};
-use crate::runtime::thread_pool::{AtomicCell, Idle};
-use crate::runtime::{queue, task};
-use crate::util::linked_list::{Link, LinkedList};
-use crate::util::FastRand;
-
-use std::cell::RefCell;
-use std::time::Duration;
-
-/// A scheduler worker
-pub(super) struct Worker {
-    /// Reference to shared state
-    shared: Arc<Shared>,
-
-    /// Index holding this worker's remote state
-    index: usize,
-
-    /// Used to hand-off a worker's core to another thread.
-    core: AtomicCell<Core>,
-}
-
-/// Core data
-struct Core {
-    /// Used to schedule bookkeeping tasks every so often.
-    tick: u8,
-
-    /// When a task is scheduled from a worker, it is stored in this slot. The
-    /// worker will check this slot for a task **before** checking the run
-    /// queue. This effectively results in the **last** scheduled task to be run
-    /// next (LIFO). This is an optimization for message passing patterns and
-    /// helps to reduce latency.
-    lifo_slot: Option<Notified>,
-
-    /// The worker-local run queue.
-    run_queue: queue::Local<Arc<Worker>>,
-
-    /// True if the worker is currently searching for more work. Searching
-    /// involves attempting to steal from other workers.
-    is_searching: bool,
-
-    /// True if the scheduler is being shutdown
-    is_shutdown: bool,
-
-    /// Tasks owned by the core
-    tasks: LinkedList<Task, <Task as Link>::Target>,
-
-    /// Parker
-    ///
-    /// Stored in an `Option` as the parker is added / removed to make the
-    /// borrow checker happy.
-    park: Option<Parker>,
-
-    /// Fast random number generator.
-    rand: FastRand,
-}
-
-/// State shared across all workers
-pub(super) struct Shared {
-    /// Per-worker remote state. All other workers have access to this and is
-    /// how they communicate between each other.
-    remotes: Box<[Remote]>,
-
-    /// Submit work to the scheduler while **not** currently on a worker thread.
-    inject: queue::Inject<Arc<Worker>>,
-
-    /// Coordinates idle workers
-    idle: Idle,
-
-    /// Cores that have observed the shutdown signal
-    ///
-    /// The core is **not** placed back in the worker to avoid it from being
-    /// stolen by a thread that was spawned as part of `block_in_place`.
-    #[allow(clippy::vec_box)] // we're moving an already-boxed value
-    shutdown_cores: Mutex<Vec<Box<Core>>>,
-}
-
-/// Used to communicate with a worker from other threads.
-struct Remote {
-    /// Steal tasks from this worker.
-    steal: queue::Steal<Arc<Worker>>,
-
-    /// Transfers tasks to be released. Any worker pushes tasks, only the owning
-    /// worker pops.
-    pending_drop: task::TransferStack<Arc<Worker>>,
-
-    /// Unparks the associated worker thread
-    unpark: Unparker,
-}
-
-/// Thread-local context
-struct Context {
-    /// Worker
-    worker: Arc<Worker>,
-
-    /// Core data
-    core: RefCell<Option<Box<Core>>>,
-}
-
-/// Starts the workers
-pub(crate) struct Launch(Vec<Arc<Worker>>);
-
-/// Running a task may consume the core. If the core is still available when
-/// running the task completes, it is returned. Otherwise, the worker will need
-/// to stop processing.
-type RunResult = Result<Box<Core>, ()>;
-
-/// A task handle
-type Task = task::Task<Arc<Worker>>;
-
-/// A notified task handle
-type Notified = task::Notified<Arc<Worker>>;
-
-// Tracks thread-local state
-scoped_thread_local!(static CURRENT: Context);
-
-pub(super) fn create(size: usize, park: Parker) -> (Arc<Shared>, Launch) {
-    let mut cores = vec![];
-    let mut remotes = vec![];
-
-    // Create the local queues
-    for _ in 0..size {
-        let (steal, run_queue) = queue::local();
-
-        let park = park.clone();
-        let unpark = park.unpark();
-
-        cores.push(Box::new(Core {
-            tick: 0,
-            lifo_slot: None,
-            run_queue,
-            is_searching: false,
-            is_shutdown: false,
-            tasks: LinkedList::new(),
-            park: Some(park),
-            rand: FastRand::new(seed()),
-        }));
-
-        remotes.push(Remote {
-            steal,
-            pending_drop: task::TransferStack::new(),
-            unpark,
-        });
-    }
-
-    let shared = Arc::new(Shared {
-        remotes: remotes.into_boxed_slice(),
-        inject: queue::Inject::new(),
-        idle: Idle::new(size),
-        shutdown_cores: Mutex::new(vec![]),
-    });
-
-    let mut launch = Launch(vec![]);
-
-    for (index, core) in cores.drain(..).enumerate() {
-        launch.0.push(Arc::new(Worker {
-            shared: shared.clone(),
-            index,
-            core: AtomicCell::new(Some(core)),
-        }));
-    }
-
-    (shared, launch)
-}
-
-pub(crate) fn block_in_place<F, R>(f: F) -> R
-where
-    F: FnOnce() -> R,
-{
-    // Try to steal the worker core back
-    struct Reset(coop::Budget);
-
-    impl Drop for Reset {
-        fn drop(&mut self) {
-            CURRENT.with(|maybe_cx| {
-                if let Some(cx) = maybe_cx {
-                    let core = cx.worker.core.take();
-                    let mut cx_core = cx.core.borrow_mut();
-                    assert!(cx_core.is_none());
-                    *cx_core = core;
-
-                    // Reset the task budget as we are re-entering the
-                    // runtime.
-                    coop::set(self.0);
-                }
-            });
-        }
-    }
-
-    let mut had_entered = false;
-
-    CURRENT.with(|maybe_cx| {
-        match (crate::runtime::enter::context(), maybe_cx.is_some()) {
-            (EnterContext::Entered { .. }, true) => {
-                // We are on a thread pool runtime thread, so we just need to set up blocking.
-                had_entered = true;
-            }
-            (EnterContext::Entered { allow_blocking }, false) => {
-                // We are on an executor, but _not_ on the thread pool.
-                // That is _only_ okay if we are in a thread pool runtime's block_on method:
-                if allow_blocking {
-                    had_entered = true;
-                    return;
-                } else {
-                    // This probably means we are on the basic_scheduler or in a LocalSet,
-                    // where it is _not_ okay to block.
-                    panic!("can call blocking only when running on the multi-threaded runtime");
-                }
-            }
-            (EnterContext::NotEntered, true) => {
-                // This is a nested call to block_in_place (we already exited).
-                // All the necessary setup has already been done.
-                return;
-            }
-            (EnterContext::NotEntered, false) => {
-                // We are outside of the tokio runtime, so blocking is fine.
-                // We can also skip all of the thread pool blocking setup steps.
-                return;
-            }
-        }
-
-        let cx = maybe_cx.expect("no .is_some() == false cases above should lead here");
-
-        // Get the worker core. If none is set, then blocking is fine!
-        let core = match cx.core.borrow_mut().take() {
-            Some(core) => core,
-            None => return,
-        };
-
-        // The parker should be set here
-        assert!(core.park.is_some());
-
-        // In order to block, the core must be sent to another thread for
-        // execution.
-        //
-        // First, move the core back into the worker's shared core slot.
-        cx.worker.core.set(core);
-
-        // Next, clone the worker handle and send it to a new thread for
-        // processing.
-        //
-        // Once the blocking task is done executing, we will attempt to
-        // steal the core back.
-        let worker = cx.worker.clone();
-        runtime::spawn_blocking(move || run(worker));
-    });
-
-    if had_entered {
-        // Unset the current task's budget. Blocking sections are not
-        // constrained by task budgets.
-        let _reset = Reset(coop::stop());
-
-        crate::runtime::enter::exit(f)
-    } else {
-        f()
-    }
-}
-
-/// After how many ticks is the global queue polled. This helps to ensure
-/// fairness.
-///
-/// The number is fairly arbitrary. I believe this value was copied from golang.
-const GLOBAL_POLL_INTERVAL: u8 = 61;
-
-impl Launch {
-    pub(crate) fn launch(mut self) {
-        for worker in self.0.drain(..) {
-            runtime::spawn_blocking(move || run(worker));
-        }
-    }
-}
-
-fn run(worker: Arc<Worker>) {
-    // Acquire a core. If this fails, then another thread is running this
-    // worker and there is nothing further to do.
-    let core = match worker.core.take() {
-        Some(core) => core,
-        None => return,
-    };
-
-    // Set the worker context.
-    let cx = Context {
-        worker,
-        core: RefCell::new(None),
-    };
-
-    let _enter = crate::runtime::enter(true);
-
-    CURRENT.set(&cx, || {
-        // This should always be an error. It only returns a `Result` to support
-        // using `?` to short circuit.
-        assert!(cx.run(core).is_err());
-    });
-}
-
-impl Context {
-    fn run(&self, mut core: Box<Core>) -> RunResult {
-        while !core.is_shutdown {
-            // Increment the tick
-            core.tick();
-
-            // Run maintenance, if needed
-            core = self.maintenance(core);
-
-            // First, check work available to the current worker.
-            if let Some(task) = core.next_task(&self.worker) {
-                core = self.run_task(task, core)?;
-                continue;
-            }
-
-            // There is no more **local** work to process, try to steal work
-            // from other workers.
-            if let Some(task) = core.steal_work(&self.worker) {
-                core = self.run_task(task, core)?;
-            } else {
-                // Wait for work
-                core = self.park(core);
-            }
-        }
-
-        core.pre_shutdown(&self.worker);
-
-        // Signal shutdown
-        self.worker.shared.shutdown(core);
-        Err(())
-    }
-
-    fn run_task(&self, task: Notified, mut core: Box<Core>) -> RunResult {
-        // Make sure the worker is not in the **searching** state. This enables
-        // another idle worker to try to steal work.
-        core.transition_from_searching(&self.worker);
-
-        // Make the core available to the runtime context
-        *self.core.borrow_mut() = Some(core);
-
-        // Run the task
-        coop::budget(|| {
-            task.run();
-
-            // As long as there is budget remaining and a task exists in the
-            // `lifo_slot`, then keep running.
-            loop {
-                // Check if we still have the core. If not, the core was stolen
-                // by another worker.
-                let mut core = match self.core.borrow_mut().take() {
-                    Some(core) => core,
-                    None => return Err(()),
-                };
-
-                // Check for a task in the LIFO slot
-                let task = match core.lifo_slot.take() {
-                    Some(task) => task,
-                    None => return Ok(core),
-                };
-
-                if coop::has_budget_remaining() {
-                    // Run the LIFO task, then loop
-                    *self.core.borrow_mut() = Some(core);
-                    task.run();
-                } else {
-                    // Not enough budget left to run the LIFO task, push it to
-                    // the back of the queue and return.
-                    core.run_queue.push_back(task, self.worker.inject());
-                    return Ok(core);
-                }
-            }
-        })
-    }
-
-    fn maintenance(&self, mut core: Box<Core>) -> Box<Core> {
-        if core.tick % GLOBAL_POLL_INTERVAL == 0 {
-            // Call `park` with a 0 timeout. This enables the I/O driver, timer, ...
-            // to run without actually putting the thread to sleep.
-            core = self.park_timeout(core, Some(Duration::from_millis(0)));
-
-            // Run regularly scheduled maintenance
-            core.maintenance(&self.worker);
-        }
-
-        core
-    }
-
-    fn park(&self, mut core: Box<Core>) -> Box<Core> {
-        core.transition_to_parked(&self.worker);
-
-        while !core.is_shutdown {
-            core = self.park_timeout(core, None);
-
-            // Run regularly scheduled maintenance
-            core.maintenance(&self.worker);
-
-            if core.transition_from_parked(&self.worker) {
-                return core;
-            }
-        }
-
-        core
-    }
-
-    fn park_timeout(&self, mut core: Box<Core>, duration: Option<Duration>) -> Box<Core> {
-        // Take the parker out of core
-        let mut park = core.park.take().expect("park missing");
-
-        // Store `core` in context
-        *self.core.borrow_mut() = Some(core);
-
-        // Park thread
-        if let Some(timeout) = duration {
-            park.park_timeout(timeout).expect("park failed");
-        } else {
-            park.park().expect("park failed");
-        }
-
-        // Remove `core` from context
-        core = self.core.borrow_mut().take().expect("core missing");
-
-        // Place `park` back in `core`
-        core.park = Some(park);
-
-        // If there are tasks available to steal, notify a worker
-        if core.run_queue.is_stealable() {
-            self.worker.shared.notify_parked();
-        }
-
-        core
-    }
-}
-
-impl Core {
-    /// Increment the tick
-    fn tick(&mut self) {
-        self.tick = self.tick.wrapping_add(1);
-    }
-
-    /// Return the next notified task available to this worker.
-    fn next_task(&mut self, worker: &Worker) -> Option<Notified> {
-        if self.tick % GLOBAL_POLL_INTERVAL == 0 {
-            worker.inject().pop().or_else(|| self.next_local_task())
-        } else {
-            self.next_local_task().or_else(|| worker.inject().pop())
-        }
-    }
-
-    fn next_local_task(&mut self) -> Option<Notified> {
-        self.lifo_slot.take().or_else(|| self.run_queue.pop())
-    }
-
-    fn steal_work(&mut self, worker: &Worker) -> Option<Notified> {
-        if !self.transition_to_searching(worker) {
-            return None;
-        }
-
-        let num = worker.shared.remotes.len();
-        // Start from a random worker
-        let start = self.rand.fastrand_n(num as u32) as usize;
-
-        for i in 0..num {
-            let i = (start + i) % num;
-
-            // Don't steal from ourself! We know we don't have work.
-            if i == worker.index {
-                continue;
-            }
-
-            let target = &worker.shared.remotes[i];
-            if let Some(task) = target.steal.steal_into(&mut self.run_queue) {
-                return Some(task);
-            }
-        }
-
-        // Fallback on checking the global queue
-        worker.shared.inject.pop()
-    }
-
-    fn transition_to_searching(&mut self, worker: &Worker) -> bool {
-        if !self.is_searching {
-            self.is_searching = worker.shared.idle.transition_worker_to_searching();
-        }
-
-        self.is_searching
-    }
-
-    fn transition_from_searching(&mut self, worker: &Worker) {
-        if !self.is_searching {
-            return;
-        }
-
-        self.is_searching = false;
-        worker.shared.transition_worker_from_searching();
-    }
-
-    /// Prepare the worker state for parking
-    fn transition_to_parked(&mut self, worker: &Worker) {
-        // When the final worker transitions **out** of searching to parked, it
-        // must check all the queues one last time in case work materialized
-        // between the last work scan and transitioning out of searching.
-        let is_last_searcher = worker
-            .shared
-            .idle
-            .transition_worker_to_parked(worker.index, self.is_searching);
-
-        // The worker is no longer searching. Setting this is the local cache
-        // only.
-        self.is_searching = false;
-
-        if is_last_searcher {
-            worker.shared.notify_if_work_pending();
-        }
-    }
-
-    /// Returns `true` if the transition happened.
-    fn transition_from_parked(&mut self, worker: &Worker) -> bool {
-        // If a task is in the lifo slot, then we must unpark regardless of
-        // being notified
-        if self.lifo_slot.is_some() {
-            worker.shared.idle.unpark_worker_by_id(worker.index);
-            self.is_searching = true;
-            return true;
-        }
-
-        if worker.shared.idle.is_parked(worker.index) {
-            return false;
-        }
-
-        // When unparked, the worker is in the searching state.
-        self.is_searching = true;
-        true
-    }
-
-    /// Runs maintenance work such as free pending tasks and check the pool's
-    /// state.
-    fn maintenance(&mut self, worker: &Worker) {
-        self.drain_pending_drop(worker);
-
-        if !self.is_shutdown {
-            // Check if the scheduler has been shutdown
-            self.is_shutdown = worker.inject().is_closed();
-        }
-    }
-
-    // Signals all tasks to shut down, and waits for them to complete. Must run
-    // before we enter the single-threaded phase of shutdown processing.
-    fn pre_shutdown(&mut self, worker: &Worker) {
-        // Signal to all tasks to shut down.
-        for header in self.tasks.iter() {
-            header.shutdown();
-        }
-
-        loop {
-            self.drain_pending_drop(worker);
-
-            if self.tasks.is_empty() {
-                break;
-            }
-
-            // Wait until signalled
-            let park = self.park.as_mut().expect("park missing");
-            park.park().expect("park failed");
-        }
-    }
-
-    // Shutdown the core
-    fn shutdown(&mut self) {
-        assert!(self.tasks.is_empty());
-
-        // Take the core
-        let mut park = self.park.take().expect("park missing");
-
-        // Drain the queue
-        while self.next_local_task().is_some() {}
-
-        park.shutdown();
-    }
-
-    fn drain_pending_drop(&mut self, worker: &Worker) {
-        use std::mem::ManuallyDrop;
-
-        for task in worker.remote().pending_drop.drain() {
-            let task = ManuallyDrop::new(task);
-
-            // safety: tasks are only pushed into the `pending_drop` stacks that
-            // are associated with the list they are inserted into. When a task
-            // is pushed into `pending_drop`, the ref-inc is skipped, so we must
-            // not ref-dec here.
-            //
-            // See `bind` and `release` implementations.
-            unsafe {
-                self.tasks.remove(task.header().into());
-            }
-        }
-    }
-}
-
-impl Worker {
-    /// Returns a reference to the scheduler's injection queue
-    fn inject(&self) -> &queue::Inject<Arc<Worker>> {
-        &self.shared.inject
-    }
-
-    /// Return a reference to this worker's remote data
-    fn remote(&self) -> &Remote {
-        &self.shared.remotes[self.index]
-    }
-
-    fn eq(&self, other: &Worker) -> bool {
-        self.shared.ptr_eq(&other.shared) && self.index == other.index
-    }
-}
-
-impl task::Schedule for Arc<Worker> {
-    fn bind(task: Task) -> Arc<Worker> {
-        CURRENT.with(|maybe_cx| {
-            let cx = maybe_cx.expect("scheduler context missing");
-
-            // Track the task
-            cx.core
-                .borrow_mut()
-                .as_mut()
-                .expect("scheduler core missing")
-                .tasks
-                .push_front(task);
-
-            // Return a clone of the worker
-            cx.worker.clone()
-        })
-    }
-
-    fn release(&self, task: &Task) -> Option<Task> {
-        use std::ptr::NonNull;
-
-        enum Immediate {
-            // Task has been synchronously removed from the Core owned by the
-            // current thread
-            Removed(Option<Task>),
-            // Task is owned by another thread, so we need to notify it to clean
-            // up the task later.
-            MaybeRemote,
-        }
-
-        let immediate = CURRENT.with(|maybe_cx| {
-            let cx = match maybe_cx {
-                Some(cx) => cx,
-                None => return Immediate::MaybeRemote,
-            };
-
-            if !self.eq(&cx.worker) {
-                // Task owned by another core, so we need to notify it.
-                return Immediate::MaybeRemote;
-            }
-
-            let mut maybe_core = cx.core.borrow_mut();
-
-            if let Some(core) = &mut *maybe_core {
-                // Directly remove the task
-                //
-                // safety: the task is inserted in the list in `bind`.
-                unsafe {
-                    let ptr = NonNull::from(task.header());
-                    return Immediate::Removed(core.tasks.remove(ptr));
-                }
-            }
-
-            Immediate::MaybeRemote
-        });
-
-        // Checks if we were called from within a worker, allowing for immediate
-        // removal of a scheduled task. Else we have to go through the slower
-        // process below where we remotely mark a task as dropped.
-        match immediate {
-            Immediate::Removed(task) => return task,
-            Immediate::MaybeRemote => (),
-        };
-
-        // Track the task to be released by the worker that owns it
-        //
-        // Safety: We get a new handle without incrementing the ref-count.
-        // A ref-count is held by the "owned" linked list and it is only
-        // ever removed from that list as part of the release process: this
-        // method or popping the task from `pending_drop`. Thus, we can rely
-        // on the ref-count held by the linked-list to keep the memory
-        // alive.
-        //
-        // When the task is removed from the stack, it is forgotten instead
-        // of dropped.
-        let task = unsafe { Task::from_raw(task.header().into()) };
-
-        self.remote().pending_drop.push(task);
-
-        // The worker core has been handed off to another thread. In the
-        // event that the scheduler is currently shutting down, the thread
-        // that owns the task may be waiting on the release to complete
-        // shutdown.
-        if self.inject().is_closed() {
-            self.remote().unpark.unpark();
-        }
-
-        None
-    }
-
-    fn schedule(&self, task: Notified) {
-        // Because this is not a newly spawned task, if scheduling fails due to
-        // the runtime shutting down, there is no special work that must happen
-        // here.
-        let _ = self.shared.schedule(task, false);
-    }
-
-    fn yield_now(&self, task: Notified) {
-        // Because this is not a newly spawned task, if scheduling fails due to
-        // the runtime shutting down, there is no special work that must happen
-        // here.
-        let _ = self.shared.schedule(task, true);
-    }
-}
-
-impl Shared {
-    pub(super) fn schedule(&self, task: Notified, is_yield: bool) -> Result<(), Notified> {
-        CURRENT.with(|maybe_cx| {
-            if let Some(cx) = maybe_cx {
-                // Make sure the task is part of the **current** scheduler.
-                if self.ptr_eq(&cx.worker.shared) {
-                    // And the current thread still holds a core
-                    if let Some(core) = cx.core.borrow_mut().as_mut() {
-                        self.schedule_local(core, task, is_yield);
-                        return Ok(());
-                    }
-                }
-            }
-
-            // Otherwise, use the inject queue
-            self.inject.push(task)?;
-            self.notify_parked();
-            Ok(())
-        })
-    }
-
-    fn schedule_local(&self, core: &mut Core, task: Notified, is_yield: bool) {
-        // Spawning from the worker thread. If scheduling a "yield" then the
-        // task must always be pushed to the back of the queue, enabling other
-        // tasks to be executed. If **not** a yield, then there is more
-        // flexibility and the task may go to the front of the queue.
-        let should_notify = if is_yield {
-            core.run_queue.push_back(task, &self.inject);
-            true
-        } else {
-            // Push to the LIFO slot
-            let prev = core.lifo_slot.take();
-            let ret = prev.is_some();
-
-            if let Some(prev) = prev {
-                core.run_queue.push_back(prev, &self.inject);
-            }
-
-            core.lifo_slot = Some(task);
-
-            ret
-        };
-
-        // Only notify if not currently parked. If `park` is `None`, then the
-        // scheduling is from a resource driver. As notifications often come in
-        // batches, the notification is delayed until the park is complete.
-        if should_notify && core.park.is_some() {
-            self.notify_parked();
-        }
-    }
-
-    pub(super) fn close(&self) {
-        if self.inject.close() {
-            self.notify_all();
-        }
-    }
-
-    fn notify_parked(&self) {
-        if let Some(index) = self.idle.worker_to_notify() {
-            self.remotes[index].unpark.unpark();
-        }
-    }
-
-    fn notify_all(&self) {
-        for remote in &self.remotes[..] {
-            remote.unpark.unpark();
-        }
-    }
-
-    fn notify_if_work_pending(&self) {
-        for remote in &self.remotes[..] {
-            if !remote.steal.is_empty() {
-                self.notify_parked();
-                return;
-            }
-        }
-
-        if !self.inject.is_empty() {
-            self.notify_parked();
-        }
-    }
-
-    fn transition_worker_from_searching(&self) {
-        if self.idle.transition_worker_from_searching() {
-            // We are the final searching worker. Because work was found, we
-            // need to notify another worker.
-            self.notify_parked();
-        }
-    }
-
-    /// Signals that a worker has observed the shutdown signal and has replaced
-    /// its core back into its handle.
-    ///
-    /// If all workers have reached this point, the final cleanup is performed.
-    fn shutdown(&self, core: Box<Core>) {
-        let mut cores = self.shutdown_cores.lock();
-        cores.push(core);
-
-        if cores.len() != self.remotes.len() {
-            return;
-        }
-
-        for mut core in cores.drain(..) {
-            core.shutdown();
-        }
-
-        // Drain the injection queue
-        while let Some(task) = self.inject.pop() {
-            task.shutdown();
-        }
-    }
-
-    fn ptr_eq(&self, other: &Shared) -> bool {
-        std::ptr::eq(self, other)
-    }
-}
diff --git a/vendor/tokio/src/time/driver/entry.rs b/vendor/tokio/src/runtime/time/entry.rs
index 168e0b995..798d3c11e 100644
--- a/vendor/tokio/src/time/driver/entry.rs
+++ b/vendor/tokio/src/runtime/time/entry.rs
@@ -5,9 +5,9 @@
 //!
 //! # Ground rules
 //!
-//! The heart of the timer implementation here is the `TimerShared` structure,
-//! shared between the `TimerEntry` and the driver. Generally, we permit access
-//! to `TimerShared` ONLY via either 1) a mutable reference to `TimerEntry` or
+//! The heart of the timer implementation here is the [`TimerShared`] structure,
+//! shared between the [`TimerEntry`] and the driver. Generally, we permit access
+//! to [`TimerShared`] ONLY via either 1) a mutable reference to [`TimerEntry`] or
 //! 2) a held driver lock.
 //!
 //! It follows from this that any changes made while holding BOTH 1 and 2 will
@@ -36,7 +36,7 @@
 //! point than it was originally scheduled for.
 //!
 //! This is accomplished by lazily rescheduling timers. That is, we update the
-//! state field field with the true expiration of the timer from the holder of
+//! state field with the true expiration of the timer from the holder of
 //! the [`TimerEntry`]. When the driver services timers (ie, whenever it's
 //! walking lists of timers), it checks this "true when" value, and reschedules
 //! based on it.
@@ -49,19 +49,20 @@
 //! There is of course a race condition between timer reset and timer
 //! expiration. If the driver fails to observe the updated expiration time, it
 //! could trigger expiration of the timer too early. However, because
-//! `mark_pending` performs a compare-and-swap, it will identify this race and
+//! [`mark_pending`][mark_pending] performs a compare-and-swap, it will identify this race and
 //! refuse to mark the timer as pending.
+//!
+//! [mark_pending]: TimerHandle::mark_pending
 
 use crate::loom::cell::UnsafeCell;
 use crate::loom::sync::atomic::AtomicU64;
 use crate::loom::sync::atomic::Ordering;
 
+use crate::runtime::scheduler;
 use crate::sync::AtomicWaker;
 use crate::time::Instant;
 use crate::util::linked_list;
 
-use super::Handle;
-
 use std::cell::UnsafeCell as StdUnsafeCell;
 use std::task::{Context, Poll, Waker};
 use std::{marker::PhantomPinned, pin::Pin, ptr::NonNull};
@@ -71,6 +72,10 @@ type TimerResult = Result<(), crate::time::error::Error>;
 const STATE_DEREGISTERED: u64 = u64::MAX;
 const STATE_PENDING_FIRE: u64 = STATE_DEREGISTERED - 1;
 const STATE_MIN_VALUE: u64 = STATE_PENDING_FIRE;
+/// The largest safe integer to use for ticks.
+///
+/// This value should be updated if any other signal values are added above.
+pub(super) const MAX_SAFE_MILLIS_DURATION: u64 = u64::MAX - 2;
 
 /// This structure holds the current shared state of the timer - its scheduled
 /// time (if registered), or otherwise the result of the timer completing, as
@@ -93,7 +98,7 @@ pub(super) struct StateCell {
     /// without holding the driver lock is undefined behavior.
     result: UnsafeCell<TimerResult>,
     /// The currently-registered waker
-    waker: CachePadded<AtomicWaker>,
+    waker: AtomicWaker,
 }
 
 impl Default for StateCell {
@@ -113,7 +118,7 @@ impl StateCell {
         Self {
             state: AtomicU64::new(STATE_DEREGISTERED),
             result: UnsafeCell::new(Ok(())),
-            waker: CachePadded(AtomicWaker::new()),
+            waker: AtomicWaker::new(),
         }
     }
 
@@ -125,7 +130,7 @@ impl StateCell {
     fn when(&self) -> Option<u64> {
         let cur_state = self.state.load(Ordering::Relaxed);
 
-        if cur_state == u64::MAX {
+        if cur_state == STATE_DEREGISTERED {
             None
         } else {
             Some(cur_state)
@@ -138,7 +143,7 @@ impl StateCell {
         // We must register first. This ensures that either `fire` will
         // observe the new waker, or we will observe a racing fire to have set
         // the state, or both.
-        self.waker.0.register_by_ref(waker);
+        self.waker.register_by_ref(waker);
 
         self.read_state()
     }
@@ -171,7 +176,12 @@ impl StateCell {
         let mut cur_state = self.state.load(Ordering::Relaxed);
 
         loop {
-            debug_assert!(cur_state < STATE_MIN_VALUE);
+            // improve the error message for things like
+            // https://github.com/tokio-rs/tokio/issues/3675
+            assert!(
+                cur_state < STATE_MIN_VALUE,
+                "mark_pending called when the timer entry is in an invalid state"
+            );
 
             if cur_state > not_after {
                 break Err(cur_state);
@@ -221,7 +231,7 @@ impl StateCell {
 
         self.state.store(STATE_DEREGISTERED, Ordering::Release);
 
-        self.waker.0.take_waker()
+        self.waker.take_waker()
     }
 
     /// Marks the timer as registered (poll will return None) and sets the
@@ -281,10 +291,10 @@ impl StateCell {
 /// timer. As this participates in intrusive data structures, it must be pinned
 /// before polling.
 #[derive(Debug)]
-pub(super) struct TimerEntry {
-    /// Arc reference to the driver. We can only free the driver after
+pub(crate) struct TimerEntry {
+    /// Arc reference to the runtime handle. We can only free the driver after
     /// deregistering everything from their respective timer wheels.
-    driver: Handle,
+    driver: scheduler::Handle,
     /// Shared inner structure; this is part of an intrusive linked list, and
     /// therefore other references can exist to it while mutable references to
     /// Entry exist.
@@ -292,9 +302,11 @@ pub(super) struct TimerEntry {
     /// This is manipulated only under the inner mutex. TODO: Can we use loom
     /// cells for this?
     inner: StdUnsafeCell<TimerShared>,
-    /// Initial deadline for the timer. This is used to register on the first
+    /// Deadline for the timer. This is used to register on the first
     /// poll, as we can't register prior to being pinned.
-    initial_deadline: Option<Instant>,
+    deadline: Instant,
+    /// Whether the deadline has been registered.
+    registered: bool,
     /// Ensure the type is !Unpin
     _m: std::marker::PhantomPinned,
 }
@@ -323,32 +335,65 @@ pub(super) type EntryList = crate::util::linked_list::LinkedList<TimerShared, Ti
 /// frontend (`Entry`) and driver backend.
 ///
 /// Note that this structure is located inside the `TimerEntry` structure.
-#[derive(Debug)]
 pub(crate) struct TimerShared {
+    /// A link within the doubly-linked list of timers on a particular level and
+    /// slot. Valid only if state is equal to Registered.
+    ///
+    /// Only accessed under the entry lock.
+    pointers: linked_list::Pointers<TimerShared>,
+
+    /// The expiration time for which this entry is currently registered.
+    /// Generally owned by the driver, but is accessed by the entry when not
+    /// registered.
+    cached_when: AtomicU64,
+
+    /// The true expiration time. Set by the timer future, read by the driver.
+    true_when: AtomicU64,
+
     /// Current state. This records whether the timer entry is currently under
     /// the ownership of the driver, and if not, its current state (not
     /// complete, fired, error, etc).
     state: StateCell,
 
-    /// Data manipulated by the driver thread itself, only.
-    driver_state: CachePadded<TimerSharedPadded>,
-
     _p: PhantomPinned,
 }
 
+unsafe impl Send for TimerShared {}
+unsafe impl Sync for TimerShared {}
+
+impl std::fmt::Debug for TimerShared {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("TimerShared")
+            .field("when", &self.true_when.load(Ordering::Relaxed))
+            .field("cached_when", &self.cached_when.load(Ordering::Relaxed))
+            .field("state", &self.state)
+            .finish()
+    }
+}
+
+generate_addr_of_methods! {
+    impl<> TimerShared {
+        unsafe fn addr_of_pointers(self: NonNull<Self>) -> NonNull<linked_list::Pointers<TimerShared>> {
+            &self.pointers
+        }
+    }
+}
+
 impl TimerShared {
     pub(super) fn new() -> Self {
         Self {
+            cached_when: AtomicU64::new(0),
+            true_when: AtomicU64::new(0),
+            pointers: linked_list::Pointers::new(),
             state: StateCell::default(),
-            driver_state: CachePadded(TimerSharedPadded::new()),
             _p: PhantomPinned,
         }
     }
 
-    /// Gets the cached time-of-expiration value
+    /// Gets the cached time-of-expiration value.
     pub(super) fn cached_when(&self) -> u64 {
         // Cached-when is only accessed under the driver lock, so we can use relaxed
-        self.driver_state.0.cached_when.load(Ordering::Relaxed)
+        self.cached_when.load(Ordering::Relaxed)
     }
 
     /// Gets the true time-of-expiration value, and copies it into the cached
@@ -359,10 +404,7 @@ impl TimerShared {
     pub(super) unsafe fn sync_when(&self) -> u64 {
         let true_when = self.true_when();
 
-        self.driver_state
-            .0
-            .cached_when
-            .store(true_when, Ordering::Relaxed);
+        self.cached_when.store(true_when, Ordering::Relaxed);
 
         true_when
     }
@@ -372,10 +414,7 @@ impl TimerShared {
     /// SAFETY: Must be called with the driver lock held, and when this entry is
     /// not in any timer wheel lists.
     unsafe fn set_cached_when(&self, when: u64) {
-        self.driver_state
-            .0
-            .cached_when
-            .store(when, Ordering::Relaxed);
+        self.cached_when.store(when, Ordering::Relaxed);
     }
 
     /// Returns the true time-of-expiration value, with relaxed memory ordering.
@@ -390,7 +429,7 @@ impl TimerShared {
     /// in the timer wheel.
     pub(super) unsafe fn set_expiration(&self, t: u64) {
         self.state.set_expiration(t);
-        self.driver_state.0.cached_when.store(t, Ordering::Relaxed);
+        self.cached_when.store(t, Ordering::Relaxed);
     }
 
     /// Sets the true time-of-expiration only if it is after the current.
@@ -414,48 +453,6 @@ impl TimerShared {
     }
 }
 
-/// Additional shared state between the driver and the timer which is cache
-/// padded. This contains the information that the driver thread accesses most
-/// frequently to minimize contention. In particular, we move it away from the
-/// waker, as the waker is updated on every poll.
-struct TimerSharedPadded {
-    /// The expiration time for which this entry is currently registered.
-    /// Generally owned by the driver, but is accessed by the entry when not
-    /// registered.
-    cached_when: AtomicU64,
-
-    /// The true expiration time. Set by the timer future, read by the driver.
-    true_when: AtomicU64,
-
-    /// A link within the doubly-linked list of timers on a particular level and
-    /// slot. Valid only if state is equal to Registered.
-    ///
-    /// Only accessed under the entry lock.
-    pointers: StdUnsafeCell<linked_list::Pointers<TimerShared>>,
-}
-
-impl std::fmt::Debug for TimerSharedPadded {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        f.debug_struct("TimerSharedPadded")
-            .field("when", &self.true_when.load(Ordering::Relaxed))
-            .field("cached_when", &self.cached_when.load(Ordering::Relaxed))
-            .finish()
-    }
-}
-
-impl TimerSharedPadded {
-    fn new() -> Self {
-        Self {
-            cached_when: AtomicU64::new(0),
-            true_when: AtomicU64::new(0),
-            pointers: StdUnsafeCell::new(linked_list::Pointers::new()),
-        }
-    }
-}
-
-unsafe impl Send for TimerShared {}
-unsafe impl Sync for TimerShared {}
-
 unsafe impl linked_list::Link for TimerShared {
     type Handle = TimerHandle;
 
@@ -472,20 +469,25 @@ unsafe impl linked_list::Link for TimerShared {
     unsafe fn pointers(
         target: NonNull<Self::Target>,
     ) -> NonNull<linked_list::Pointers<Self::Target>> {
-        unsafe { NonNull::new(target.as_ref().driver_state.0.pointers.get()).unwrap() }
+        TimerShared::addr_of_pointers(target)
     }
 }
 
 // ===== impl Entry =====
 
 impl TimerEntry {
-    pub(crate) fn new(handle: &Handle, deadline: Instant) -> Self {
+    #[track_caller]
+    pub(crate) fn new(handle: &scheduler::Handle, deadline: Instant) -> Self {
+        // Panic if the time driver is not enabled
+        let _ = handle.driver().time();
+
         let driver = handle.clone();
 
         Self {
             driver,
             inner: StdUnsafeCell::new(TimerShared::new()),
-            initial_deadline: Some(deadline),
+            deadline,
+            registered: false,
             _m: std::marker::PhantomPinned,
         }
     }
@@ -494,8 +496,12 @@ impl TimerEntry {
         unsafe { &*self.inner.get() }
     }
 
+    pub(crate) fn deadline(&self) -> Instant {
+        self.deadline
+    }
+
     pub(crate) fn is_elapsed(&self) -> bool {
-        !self.inner().state.might_be_registered() && self.initial_deadline.is_none()
+        !self.inner().state.might_be_registered() && self.registered
     }
 
     /// Cancels and deregisters the timer. This operation is irreversible.
@@ -522,20 +528,24 @@ impl TimerEntry {
         // driver did so far and happens-before everything the driver does in
         // the future. While we have the lock held, we also go ahead and
         // deregister the entry if necessary.
-        unsafe { self.driver.clear_entry(NonNull::from(self.inner())) };
+        unsafe { self.driver().clear_entry(NonNull::from(self.inner())) };
     }
 
-    pub(crate) fn reset(mut self: Pin<&mut Self>, new_time: Instant) {
-        unsafe { self.as_mut().get_unchecked_mut() }.initial_deadline = None;
+    pub(crate) fn reset(mut self: Pin<&mut Self>, new_time: Instant, reregister: bool) {
+        unsafe { self.as_mut().get_unchecked_mut() }.deadline = new_time;
+        unsafe { self.as_mut().get_unchecked_mut() }.registered = reregister;
 
-        let tick = self.driver.time_source().deadline_to_tick(new_time);
+        let tick = self.driver().time_source().deadline_to_tick(new_time);
 
         if self.inner().extend_expiration(tick).is_ok() {
             return;
         }
 
-        unsafe {
-            self.driver.reregister(tick, self.inner().into());
+        if reregister {
+            unsafe {
+                self.driver()
+                    .reregister(&self.driver.driver().io, tick, self.inner().into());
+            }
         }
     }
 
@@ -543,18 +553,28 @@ impl TimerEntry {
         mut self: Pin<&mut Self>,
         cx: &mut Context<'_>,
     ) -> Poll<Result<(), super::Error>> {
-        if self.driver.is_shutdown() {
+        if self.driver().is_shutdown() {
             panic!("{}", crate::util::error::RUNTIME_SHUTTING_DOWN_ERROR);
         }
 
-        if let Some(deadline) = self.initial_deadline {
-            self.as_mut().reset(deadline);
+        if !self.registered {
+            let deadline = self.deadline;
+            self.as_mut().reset(deadline, true);
         }
 
         let this = unsafe { self.get_unchecked_mut() };
 
         this.inner().state.poll(cx.waker())
     }
+
+    pub(crate) fn driver(&self) -> &super::Handle {
+        self.driver.driver().time()
+    }
+
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    pub(crate) fn clock(&self) -> &super::Clock {
+        self.driver.driver().clock()
+    }
 }
 
 impl TimerHandle {
@@ -622,8 +642,3 @@ impl Drop for TimerEntry {
         unsafe { Pin::new_unchecked(self) }.as_mut().cancel()
     }
 }
-
-#[cfg_attr(target_arch = "x86_64", repr(align(128)))]
-#[cfg_attr(not(target_arch = "x86_64"), repr(align(64)))]
-#[derive(Debug, Default)]
-struct CachePadded<T>(T);
diff --git a/vendor/tokio/src/runtime/time/handle.rs b/vendor/tokio/src/runtime/time/handle.rs
new file mode 100644
index 000000000..fce791d99
--- /dev/null
+++ b/vendor/tokio/src/runtime/time/handle.rs
@@ -0,0 +1,62 @@
+use crate::runtime::time::TimeSource;
+use std::fmt;
+
+/// Handle to time driver instance.
+pub(crate) struct Handle {
+    pub(super) time_source: TimeSource,
+    pub(super) inner: super::Inner,
+}
+
+impl Handle {
+    /// Returns the time source associated with this handle.
+    pub(crate) fn time_source(&self) -> &TimeSource {
+        &self.time_source
+    }
+
+    /// Checks whether the driver has been shutdown.
+    pub(super) fn is_shutdown(&self) -> bool {
+        self.inner.is_shutdown()
+    }
+
+    /// Track that the driver is being unparked
+    pub(crate) fn unpark(&self) {
+        #[cfg(feature = "test-util")]
+        self.inner
+            .did_wake
+            .store(true, std::sync::atomic::Ordering::SeqCst);
+    }
+}
+
+cfg_not_rt! {
+    impl Handle {
+        /// Tries to get a handle to the current timer.
+        ///
+        /// # Panics
+        ///
+        /// This function panics if there is no current timer set.
+        ///
+        /// It can be triggered when [`Builder::enable_time`] or
+        /// [`Builder::enable_all`] are not included in the builder.
+        ///
+        /// It can also panic whenever a timer is created outside of a
+        /// Tokio runtime. That is why `rt.block_on(sleep(...))` will panic,
+        /// since the function is executed outside of the runtime.
+        /// Whereas `rt.block_on(async {sleep(...).await})` doesn't panic.
+        /// And this is because wrapping the function on an async makes it lazy,
+        /// and so gets executed inside the runtime successfully without
+        /// panicking.
+        ///
+        /// [`Builder::enable_time`]: crate::runtime::Builder::enable_time
+        /// [`Builder::enable_all`]: crate::runtime::Builder::enable_all
+        #[track_caller]
+        pub(crate) fn current() -> Self {
+            panic!("{}", crate::util::error::CONTEXT_MISSING_ERROR)
+        }
+    }
+}
+
+impl fmt::Debug for Handle {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "Handle")
+    }
+}
diff --git a/vendor/tokio/src/time/driver/mod.rs b/vendor/tokio/src/runtime/time/mod.rs
index 37d2231c3..423ad79ab 100644
--- a/vendor/tokio/src/time/driver/mod.rs
+++ b/vendor/tokio/src/runtime/time/mod.rs
@@ -4,25 +4,26 @@
 #![allow(unused_unsafe)]
 #![cfg_attr(not(feature = "rt"), allow(dead_code))]
 
-//! Time driver
+//! Time driver.
 
 mod entry;
-pub(self) use self::entry::{EntryList, TimerEntry, TimerHandle, TimerShared};
+pub(crate) use entry::TimerEntry;
+use entry::{EntryList, TimerHandle, TimerShared, MAX_SAFE_MILLIS_DURATION};
 
 mod handle;
 pub(crate) use self::handle::Handle;
 
-mod wheel;
+mod source;
+pub(crate) use source::TimeSource;
 
-pub(super) mod sleep;
+mod wheel;
 
 use crate::loom::sync::atomic::{AtomicBool, Ordering};
-use crate::loom::sync::{Arc, Mutex};
-use crate::park::{Park, Unpark};
+use crate::loom::sync::Mutex;
+use crate::runtime::driver::{self, IoHandle, IoStack};
 use crate::time::error::Error;
-use crate::time::{Clock, Duration, Instant};
+use crate::time::{Clock, Duration};
 
-use std::convert::TryInto;
 use std::fmt;
 use std::{num::NonZeroU64, ptr::NonNull, task::Waker};
 
@@ -82,15 +83,18 @@ use std::{num::NonZeroU64, ptr::NonNull, task::Waker};
 /// [timeout]: crate::time::Timeout
 /// [interval]: crate::time::Interval
 #[derive(Debug)]
-pub(crate) struct Driver<P: Park + 'static> {
-    /// Timing backend in use
-    time_source: ClockTime,
+pub(crate) struct Driver {
+    /// Parker to delegate to.
+    park: IoStack,
+}
 
-    /// Shared state
-    handle: Handle,
+/// Timer state shared between `Driver`, `Handle`, and `Registration`.
+struct Inner {
+    // The state is split like this so `Handle` can access `is_shutdown` without locking the mutex
+    pub(super) state: Mutex<InnerState>,
 
-    /// Parker to delegate to
-    park: P,
+    /// True if the driver is being shutdown.
+    pub(super) is_shutdown: AtomicBool,
 
     // When `true`, a call to `park_timeout` should immediately return and time
     // should not advance. One reason for this to be `true` is if the task
@@ -99,113 +103,80 @@ pub(crate) struct Driver<P: Park + 'static> {
     // While it may look racy, it only has any effect when the clock is paused
     // and pausing the clock is restricted to a single-threaded runtime.
     #[cfg(feature = "test-util")]
-    did_wake: Arc<AtomicBool>,
-}
-
-/// A structure which handles conversion from Instants to u64 timestamps.
-#[derive(Debug, Clone)]
-pub(self) struct ClockTime {
-    clock: super::clock::Clock,
-    start_time: Instant,
-}
-
-impl ClockTime {
-    pub(self) fn new(clock: Clock) -> Self {
-        Self {
-            start_time: clock.now(),
-            clock,
-        }
-    }
-
-    pub(self) fn deadline_to_tick(&self, t: Instant) -> u64 {
-        // Round up to the end of a ms
-        self.instant_to_tick(t + Duration::from_nanos(999_999))
-    }
-
-    pub(self) fn instant_to_tick(&self, t: Instant) -> u64 {
-        // round up
-        let dur: Duration = t
-            .checked_duration_since(self.start_time)
-            .unwrap_or_else(|| Duration::from_secs(0));
-        let ms = dur.as_millis();
-
-        ms.try_into().expect("Duration too far into the future")
-    }
-
-    pub(self) fn tick_to_duration(&self, t: u64) -> Duration {
-        Duration::from_millis(t)
-    }
-
-    pub(self) fn now(&self) -> u64 {
-        self.instant_to_tick(self.clock.now())
-    }
-}
-
-/// Timer state shared between `Driver`, `Handle`, and `Registration`.
-struct Inner {
-    // The state is split like this so `Handle` can access `is_shutdown` without locking the mutex
-    pub(super) state: Mutex<InnerState>,
-
-    /// True if the driver is being shutdown
-    pub(super) is_shutdown: AtomicBool,
+    did_wake: AtomicBool,
 }
 
 /// Time state shared which must be protected by a `Mutex`
 struct InnerState {
-    /// Timing backend in use
-    time_source: ClockTime,
-
     /// The last published timer `elapsed` value.
     elapsed: u64,
 
-    /// The earliest time at which we promise to wake up without unparking
+    /// The earliest time at which we promise to wake up without unparking.
     next_wake: Option<NonZeroU64>,
 
-    /// Timer wheel
+    /// Timer wheel.
     wheel: wheel::Wheel,
-
-    /// Unparker that can be used to wake the time driver
-    unpark: Box<dyn Unpark>,
 }
 
 // ===== impl Driver =====
 
-impl<P> Driver<P>
-where
-    P: Park + 'static,
-{
+impl Driver {
     /// Creates a new `Driver` instance that uses `park` to block the current
     /// thread and `time_source` to get the current time and convert to ticks.
     ///
     /// Specifying the source of time is useful when testing.
-    pub(crate) fn new(park: P, clock: Clock) -> Driver<P> {
-        let time_source = ClockTime::new(clock);
+    pub(crate) fn new(park: IoStack, clock: &Clock) -> (Driver, Handle) {
+        let time_source = TimeSource::new(clock);
 
-        let inner = Inner::new(time_source.clone(), Box::new(park.unpark()));
-
-        Driver {
+        let handle = Handle {
             time_source,
-            handle: Handle::new(Arc::new(inner)),
-            park,
-            #[cfg(feature = "test-util")]
-            did_wake: Arc::new(AtomicBool::new(false)),
-        }
+            inner: Inner {
+                state: Mutex::new(InnerState {
+                    elapsed: 0,
+                    next_wake: None,
+                    wheel: wheel::Wheel::new(),
+                }),
+                is_shutdown: AtomicBool::new(false),
+
+                #[cfg(feature = "test-util")]
+                did_wake: AtomicBool::new(false),
+            },
+        };
+
+        let driver = Driver { park };
+
+        (driver, handle)
     }
 
-    /// Returns a handle to the timer.
-    ///
-    /// The `Handle` is how `Sleep` instances are created. The `Sleep` instances
-    /// can either be created directly or the `Handle` instance can be passed to
-    /// `with_default`, setting the timer as the default timer for the execution
-    /// context.
-    pub(crate) fn handle(&self) -> Handle {
-        self.handle.clone()
+    pub(crate) fn park(&mut self, handle: &driver::Handle) {
+        self.park_internal(handle, None)
     }
 
-    fn park_internal(&mut self, limit: Option<Duration>) -> Result<(), P::Error> {
-        let mut lock = self.handle.get().state.lock();
+    pub(crate) fn park_timeout(&mut self, handle: &driver::Handle, duration: Duration) {
+        self.park_internal(handle, Some(duration))
+    }
+
+    pub(crate) fn shutdown(&mut self, rt_handle: &driver::Handle) {
+        let handle = rt_handle.time();
+
+        if handle.is_shutdown() {
+            return;
+        }
+
+        handle.inner.is_shutdown.store(true, Ordering::SeqCst);
+
+        // Advance time forward to the end of time.
 
-        assert!(!self.handle.is_shutdown());
+        handle.process_at_time(u64::MAX);
+
+        self.park.shutdown(rt_handle);
+    }
+
+    fn park_internal(&mut self, rt_handle: &driver::Handle, limit: Option<Duration>) {
+        let handle = rt_handle.time();
+        let mut lock = handle.inner.state.lock();
+
+        assert!(!handle.is_shutdown());
 
         let next_wake = lock.wheel.next_expiration_time();
         lock.next_wake =
@@ -215,86 +186,91 @@ where
 
         match next_wake {
             Some(when) => {
-                let now = self.time_source.now();
+                let now = handle.time_source.now(rt_handle.clock());
                 // Note that we effectively round up to 1ms here - this avoids
                 // very short-duration microsecond-resolution sleeps that the OS
                 // might treat as zero-length.
-                let mut duration = self.time_source.tick_to_duration(when.saturating_sub(now));
+                let mut duration = handle
+                    .time_source
+                    .tick_to_duration(when.saturating_sub(now));
 
                 if duration > Duration::from_millis(0) {
                     if let Some(limit) = limit {
                         duration = std::cmp::min(limit, duration);
                     }
 
-                    self.park_timeout(duration)?;
+                    self.park_thread_timeout(rt_handle, duration);
                 } else {
-                    self.park.park_timeout(Duration::from_secs(0))?;
+                    self.park.park_timeout(rt_handle, Duration::from_secs(0));
                 }
             }
             None => {
                 if let Some(duration) = limit {
-                    self.park_timeout(duration)?;
+                    self.park_thread_timeout(rt_handle, duration);
                 } else {
-                    self.park.park()?;
+                    self.park.park(rt_handle);
                 }
             }
         }
 
         // Process pending timers after waking up
-        self.handle.process();
-
-        Ok(())
+        handle.process(rt_handle.clock());
     }
 
     cfg_test_util! {
-        fn park_timeout(&mut self, duration: Duration) -> Result<(), P::Error> {
-            let clock = &self.time_source.clock;
+        fn park_thread_timeout(&mut self, rt_handle: &driver::Handle, duration: Duration) {
+            let handle = rt_handle.time();
+            let clock = rt_handle.clock();
 
-            if clock.is_paused() {
-                self.park.park_timeout(Duration::from_secs(0))?;
+            if clock.can_auto_advance() {
+                self.park.park_timeout(rt_handle, Duration::from_secs(0));
 
                 // If the time driver was woken, then the park completed
                 // before the "duration" elapsed (usually caused by a
                 // yield in `Runtime::block_on`). In this case, we don't
                 // advance the clock.
-                if !self.did_wake() {
+                if !handle.did_wake() {
                     // Simulate advancing time
-                    clock.advance(duration);
+                    if let Err(msg) = clock.advance(duration) {
+                        panic!("{}", msg);
+                    }
                 }
             } else {
-                self.park.park_timeout(duration)?;
+                self.park.park_timeout(rt_handle, duration);
             }
-
-            Ok(())
-        }
-
-        fn did_wake(&self) -> bool {
-            self.did_wake.swap(false, Ordering::SeqCst)
         }
     }
 
     cfg_not_test_util! {
-        fn park_timeout(&mut self, duration: Duration) -> Result<(), P::Error> {
-            self.park.park_timeout(duration)
+        fn park_thread_timeout(&mut self, rt_handle: &driver::Handle, duration: Duration) {
+            self.park.park_timeout(rt_handle, duration);
         }
     }
 }
 
 impl Handle {
     /// Runs timer related logic, and returns the next wakeup time
-    pub(self) fn process(&self) {
-        let now = self.time_source().now();
+    pub(self) fn process(&self, clock: &Clock) {
+        let now = self.time_source().now(clock);
 
         self.process_at_time(now)
     }
 
-    pub(self) fn process_at_time(&self, now: u64) {
+    pub(self) fn process_at_time(&self, mut now: u64) {
         let mut waker_list: [Option<Waker>; 32] = Default::default();
         let mut waker_idx = 0;
 
-        let mut lock = self.get().lock();
+        let mut lock = self.inner.lock();
 
-        assert!(now >= lock.elapsed);
+        if now < lock.elapsed {
+            // Time went backwards! This normally shouldn't happen as the Rust language
+            // guarantees that an Instant is monotonic, but can happen when running
+            // Linux in a VM on a Windows host due to std incorrectly trusting the
+            // hardware clock to be monotonic.
+            //
+            // See <https://github.com/tokio-rs/tokio/issues/3619> for more information.
+            now = lock.elapsed;
+        }
 
         while let Some(entry) = lock.wheel.poll(now) {
             debug_assert!(unsafe { entry.is_pending() });
@@ -315,7 +291,7 @@ impl Handle {
 
                     waker_idx = 0;
 
-                    lock = self.get().lock();
+                    lock = self.inner.lock();
                 }
             }
         }
@@ -346,7 +322,7 @@ impl Handle {
     /// `add_entry` must not be called concurrently.
     pub(self) unsafe fn clear_entry(&self, entry: NonNull<TimerShared>) {
         unsafe {
-            let mut lock = self.get().lock();
+            let mut lock = self.inner.lock();
 
             if entry.as_ref().might_be_registered() {
                 lock.wheel.remove(entry);
@@ -362,9 +338,14 @@ impl Handle {
     /// driver. No other threads are allowed to concurrently manipulate the
     /// timer at all (the current thread should hold an exclusive reference to
     /// the `TimerEntry`)
-    pub(self) unsafe fn reregister(&self, new_tick: u64, entry: NonNull<TimerShared>) {
+    pub(self) unsafe fn reregister(
+        &self,
+        unpark: &IoHandle,
+        new_tick: u64,
+        entry: NonNull<TimerShared>,
+    ) {
         let waker = unsafe {
-            let mut lock = self.get().lock();
+            let mut lock = self.inner.lock();
 
             // We may have raced with a firing/deregistration, so check before
             // deregistering.
@@ -390,12 +371,12 @@ impl Handle {
                             .map(|next_wake| when < next_wake.get())
                             .unwrap_or(true)
                         {
-                            lock.unpark.unpark();
+                            unpark.unpark();
                         }
 
                         None
                     }
-                    Err((entry, super::error::InsertError::Elapsed)) => unsafe {
+                    Err((entry, crate::time::error::InsertError::Elapsed)) => unsafe {
                         entry.fire(Ok(()))
                     },
                 }
@@ -411,94 +392,17 @@ impl Handle {
             waker.wake();
         }
     }
-}
-
-impl<P> Park for Driver<P>
-where
-    P: Park + 'static,
-{
-    type Unpark = TimerUnpark<P>;
-    type Error = P::Error;
-
-    fn unpark(&self) -> Self::Unpark {
-        TimerUnpark::new(self)
-    }
-
-    fn park(&mut self) -> Result<(), Self::Error> {
-        self.park_internal(None)
-    }
-
-    fn park_timeout(&mut self, duration: Duration) -> Result<(), Self::Error> {
-        self.park_internal(Some(duration))
-    }
-
-    fn shutdown(&mut self) {
-        if self.handle.is_shutdown() {
-            return;
-        }
-
-        self.handle.get().is_shutdown.store(true, Ordering::SeqCst);
-
-        // Advance time forward to the end of time.
-
-        self.handle.process_at_time(u64::MAX);
-
-        self.park.shutdown();
-    }
-}
-
-impl<P> Drop for Driver<P>
-where
-    P: Park + 'static,
-{
-    fn drop(&mut self) {
-        self.shutdown();
-    }
-}
 
-pub(crate) struct TimerUnpark<P: Park + 'static> {
-    inner: P::Unpark,
-
-    #[cfg(feature = "test-util")]
-    did_wake: Arc<AtomicBool>,
-}
-
-impl<P: Park + 'static> TimerUnpark<P> {
-    fn new(driver: &Driver<P>) -> TimerUnpark<P> {
-        TimerUnpark {
-            inner: driver.park.unpark(),
-
-            #[cfg(feature = "test-util")]
-            did_wake: driver.did_wake.clone(),
+    cfg_test_util! {
+        fn did_wake(&self) -> bool {
+            self.inner.did_wake.swap(false, Ordering::SeqCst)
         }
     }
 }
 
-impl<P: Park + 'static> Unpark for TimerUnpark<P> {
-    fn unpark(&self) {
-        #[cfg(feature = "test-util")]
-        self.did_wake.store(true, Ordering::SeqCst);
-
-        self.inner.unpark();
-    }
-}
-
 // ===== impl Inner =====
 
 impl Inner {
-    pub(self) fn new(time_source: ClockTime, unpark: Box<dyn Unpark>) -> Self {
-        Inner {
-            state: Mutex::new(InnerState {
-                time_source,
-                elapsed: 0,
-                next_wake: None,
-                unpark,
-                wheel: wheel::Wheel::new(),
-            }),
-            is_shutdown: AtomicBool::new(false),
-        }
-    }
-
     /// Locks the driver's inner structure
     pub(super) fn lock(&self) -> crate::loom::sync::MutexGuard<'_, InnerState> {
         self.state.lock()
diff --git a/vendor/tokio/src/runtime/time/source.rs b/vendor/tokio/src/runtime/time/source.rs
new file mode 100644
index 000000000..4647bc412
--- /dev/null
+++ b/vendor/tokio/src/runtime/time/source.rs
@@ -0,0 +1,39 @@
+use super::MAX_SAFE_MILLIS_DURATION;
+use crate::time::{Clock, Duration, Instant};
+
+/// A structure which handles conversion from Instants to u64 timestamps.
+#[derive(Debug)]
+pub(crate) struct TimeSource {
+    start_time: Instant,
+}
+
+impl TimeSource {
+    pub(crate) fn new(clock: &Clock) -> Self {
+        Self {
+            start_time: clock.now(),
+        }
+    }
+
+    pub(crate) fn deadline_to_tick(&self, t: Instant) -> u64 {
+        // Round up to the end of a ms
+        self.instant_to_tick(t + Duration::from_nanos(999_999))
+    }
+
+    pub(crate) fn instant_to_tick(&self, t: Instant) -> u64 {
+        // round up
+        let dur: Duration = t
+            .checked_duration_since(self.start_time)
+            .unwrap_or_else(|| Duration::from_secs(0));
+        let ms = dur.as_millis();
+
+        ms.try_into().unwrap_or(MAX_SAFE_MILLIS_DURATION)
+    }
+
+    pub(crate) fn tick_to_duration(&self, t: u64) -> Duration {
+        Duration::from_millis(t)
+    }
+
+    pub(crate) fn now(&self, clock: &Clock) -> u64 {
+        self.instant_to_tick(clock.now())
+    }
+}
diff --git a/vendor/tokio/src/time/driver/tests/mod.rs b/vendor/tokio/src/runtime/time/tests/mod.rs
index 7c5cf1fd0..155d99a34 100644
--- a/vendor/tokio/src/time/driver/tests/mod.rs
+++ b/vendor/tokio/src/runtime/time/tests/mod.rs
@@ -1,33 +1,27 @@
+#![cfg(not(tokio_wasi))]
+
 use std::{task::Context, time::Duration};
 
 #[cfg(not(loom))]
 use futures::task::noop_waker_ref;
 
+use crate::loom::sync::atomic::{AtomicBool, Ordering};
 use crate::loom::sync::Arc;
 use crate::loom::thread;
-use crate::{
-    loom::sync::atomic::{AtomicBool, Ordering},
-    park::Unpark,
-};
-
-use super::{Handle, TimerEntry};
 
-struct MockUnpark {}
-impl Unpark for MockUnpark {
-    fn unpark(&self) {}
-}
-impl MockUnpark {
-    fn mock() -> Box<dyn Unpark> {
-        Box::new(Self {})
-    }
-}
+use super::TimerEntry;
 
 fn block_on<T>(f: impl std::future::Future<Output = T>) -> T {
     #[cfg(loom)]
     return loom::future::block_on(f);
 
     #[cfg(not(loom))]
-    return futures::executor::block_on(f);
+    {
+        let rt = crate::runtime::Builder::new_current_thread()
+            .build()
+            .unwrap();
+        rt.block_on(f)
+    }
 }
 
 fn model(f: impl Fn() + Send + Sync + 'static) {
@@ -38,18 +32,26 @@ fn model(f: impl Fn() + Send + Sync + 'static) {
     f();
 }
 
+fn rt(start_paused: bool) -> crate::runtime::Runtime {
+    crate::runtime::Builder::new_current_thread()
+        .enable_time()
+        .start_paused(start_paused)
+        .build()
+        .unwrap()
+}
+
 #[test]
 fn single_timer() {
     model(|| {
-        let clock = crate::time::clock::Clock::new(true, false);
-        let time_source = super::ClockTime::new(clock.clone());
-
-        let inner = super::Inner::new(time_source.clone(), MockUnpark::mock());
-        let handle = Handle::new(Arc::new(inner));
+        let rt = rt(false);
+        let handle = rt.handle();
 
         let handle_ = handle.clone();
         let jh = thread::spawn(move || {
-            let entry = TimerEntry::new(&handle_, clock.now() + Duration::from_secs(1));
+            let entry = TimerEntry::new(
+                &handle_.inner,
+                handle_.inner.driver().clock().now() + Duration::from_secs(1),
+            );
             pin!(entry);
 
             block_on(futures::future::poll_fn(|cx| {
@@ -60,10 +62,13 @@ fn single_timer() {
 
         thread::yield_now();
 
+        let time = handle.inner.driver().time();
+        let clock = handle.inner.driver().clock();
+
         // This may or may not return Some (depending on how it races with the
         // thread). If it does return None, however, the timer should complete
         // synchronously.
-        handle.process_at_time(time_source.now() + 2_000_000_000);
+        time.process_at_time(time.time_source().now(clock) + 2_000_000_000);
 
         jh.join().unwrap();
     })
@@ -72,15 +77,15 @@ fn single_timer() {
 #[test]
 fn drop_timer() {
     model(|| {
-        let clock = crate::time::clock::Clock::new(true, false);
-        let time_source = super::ClockTime::new(clock.clone());
-
-        let inner = super::Inner::new(time_source.clone(), MockUnpark::mock());
-        let handle = Handle::new(Arc::new(inner));
+        let rt = rt(false);
+        let handle = rt.handle();
 
         let handle_ = handle.clone();
         let jh = thread::spawn(move || {
-            let entry = TimerEntry::new(&handle_, clock.now() + Duration::from_secs(1));
+            let entry = TimerEntry::new(
+                &handle_.inner,
+                handle_.inner.driver().clock().now() + Duration::from_secs(1),
+            );
             pin!(entry);
 
             let _ = entry
@@ -93,8 +98,11 @@ fn drop_timer() {
 
         thread::yield_now();
 
+        let time = handle.inner.driver().time();
+        let clock = handle.inner.driver().clock();
+
         // advance 2s in the future.
-        handle.process_at_time(time_source.now() + 2_000_000_000);
+        time.process_at_time(time.time_source().now(clock) + 2_000_000_000);
 
         jh.join().unwrap();
     })
@@ -103,15 +111,15 @@ fn drop_timer() {
 #[test]
 fn change_waker() {
     model(|| {
-        let clock = crate::time::clock::Clock::new(true, false);
-        let time_source = super::ClockTime::new(clock.clone());
-
-        let inner = super::Inner::new(time_source.clone(), MockUnpark::mock());
-        let handle = Handle::new(Arc::new(inner));
+        let rt = rt(false);
+        let handle = rt.handle();
 
         let handle_ = handle.clone();
         let jh = thread::spawn(move || {
-            let entry = TimerEntry::new(&handle_, clock.now() + Duration::from_secs(1));
+            let entry = TimerEntry::new(
+                &handle_.inner,
+                handle_.inner.driver().clock().now() + Duration::from_secs(1),
+            );
             pin!(entry);
 
             let _ = entry
@@ -126,8 +134,11 @@ fn change_waker() {
 
         thread::yield_now();
 
+        let time = handle.inner.driver().time();
+        let clock = handle.inner.driver().clock();
+
         // advance 2s
-        handle.process_at_time(time_source.now() + 2_000_000_000);
+        time.process_at_time(time.time_source().now(clock) + 2_000_000_000);
 
         jh.join().unwrap();
     })
@@ -138,25 +149,22 @@ fn reset_future() {
     model(|| {
         let finished_early = Arc::new(AtomicBool::new(false));
 
-        let clock = crate::time::clock::Clock::new(true, false);
-        let time_source = super::ClockTime::new(clock.clone());
-
-        let inner = super::Inner::new(time_source.clone(), MockUnpark::mock());
-        let handle = Handle::new(Arc::new(inner));
+        let rt = rt(false);
+        let handle = rt.handle();
 
         let handle_ = handle.clone();
         let finished_early_ = finished_early.clone();
-        let start = clock.now();
+        let start = handle.inner.driver().clock().now();
 
         let jh = thread::spawn(move || {
-            let entry = TimerEntry::new(&handle_, start + Duration::from_secs(1));
+            let entry = TimerEntry::new(&handle_.inner, start + Duration::from_secs(1));
             pin!(entry);
 
             let _ = entry
                 .as_mut()
                 .poll_elapsed(&mut Context::from_waker(futures::task::noop_waker_ref()));
 
-            entry.as_mut().reset(start + Duration::from_secs(2));
+            entry.as_mut().reset(start + Duration::from_secs(2), true);
 
             // shouldn't complete before 2s
             block_on(futures::future::poll_fn(|cx| {
@@ -169,12 +177,22 @@ fn reset_future() {
 
         thread::yield_now();
 
+        let handle = handle.inner.driver().time();
+
         // This may or may not return a wakeup time.
-        handle.process_at_time(time_source.instant_to_tick(start + Duration::from_millis(1500)));
+        handle.process_at_time(
+            handle
+                .time_source()
+                .instant_to_tick(start + Duration::from_millis(1500)),
+        );
 
         assert!(!finished_early.load(Ordering::Relaxed));
 
-        handle.process_at_time(time_source.instant_to_tick(start + Duration::from_millis(2500)));
+        handle.process_at_time(
+            handle
+                .time_source()
+                .instant_to_tick(start + Duration::from_millis(2500)),
+        );
 
         jh.join().unwrap();
 
@@ -182,23 +200,27 @@ fn reset_future() {
     })
 }
 
+#[cfg(not(loom))]
+fn normal_or_miri<T>(normal: T, miri: T) -> T {
+    if cfg!(miri) {
+        miri
+    } else {
+        normal
+    }
+}
+
 #[test]
 #[cfg(not(loom))]
 fn poll_process_levels() {
-    let clock = crate::time::clock::Clock::new(true, false);
-    clock.pause();
-
-    let time_source = super::ClockTime::new(clock.clone());
-
-    let inner = super::Inner::new(time_source, MockUnpark::mock());
-    let handle = Handle::new(Arc::new(inner));
+    let rt = rt(true);
+    let handle = rt.handle();
 
     let mut entries = vec![];
 
-    for i in 0..1024 {
+    for i in 0..normal_or_miri(1024, 64) {
         let mut entry = Box::pin(TimerEntry::new(
-            &handle,
-            clock.now() + Duration::from_millis(i),
+            &handle.inner,
+            handle.inner.driver().clock().now() + Duration::from_millis(i),
         ));
 
         let _ = entry
@@ -208,8 +230,9 @@ fn poll_process_levels() {
         entries.push(entry);
     }
 
-    for t in 1..1024 {
-        handle.process_at_time(t as u64);
+    for t in 1..normal_or_miri(1024, 64) {
+        handle.inner.driver().time().process_at_time(t as u64);
+
         for (deadline, future) in entries.iter_mut().enumerate() {
             let mut context = Context::from_waker(noop_waker_ref());
             if deadline <= t {
@@ -226,62 +249,19 @@ fn poll_process_levels() {
 fn poll_process_levels_targeted() {
     let mut context = Context::from_waker(noop_waker_ref());
 
-    let clock = crate::time::clock::Clock::new(true, false);
-    clock.pause();
-
-    let time_source = super::ClockTime::new(clock.clone());
+    let rt = rt(true);
+    let handle = rt.handle();
 
-    let inner = super::Inner::new(time_source, MockUnpark::mock());
-    let handle = Handle::new(Arc::new(inner));
-
-    let e1 = TimerEntry::new(&handle, clock.now() + Duration::from_millis(193));
+    let e1 = TimerEntry::new(
+        &handle.inner,
+        handle.inner.driver().clock().now() + Duration::from_millis(193),
+    );
     pin!(e1);
 
+    let handle = handle.inner.driver().time();
+
     handle.process_at_time(62);
     assert!(e1.as_mut().poll_elapsed(&mut context).is_pending());
     handle.process_at_time(192);
     handle.process_at_time(192);
 }
-
-/*
-#[test]
-fn balanced_incr_and_decr() {
-    const OPS: usize = 5;
-
-    fn incr(inner: Arc<Inner>) {
-        for _ in 0..OPS {
-            inner.increment().expect("increment should not have failed");
-            thread::yield_now();
-        }
-    }
-
-    fn decr(inner: Arc<Inner>) {
-        let mut ops_performed = 0;
-        while ops_performed < OPS {
-            if inner.num(Ordering::Relaxed) > 0 {
-                ops_performed += 1;
-                inner.decrement();
-            }
-            thread::yield_now();
-        }
-    }
-
-    loom::model(|| {
-        let unpark = Box::new(MockUnpark);
-        let instant = Instant::now();
-
-        let inner = Arc::new(Inner::new(instant, unpark));
-
-        let incr_inner = inner.clone();
-        let decr_inner = inner.clone();
-
-        let incr_hndle = thread::spawn(move || incr(incr_inner));
-        let decr_hndle = thread::spawn(move || decr(decr_inner));
-
-        incr_hndle.join().expect("should never fail");
-        decr_hndle.join().expect("should never fail");
-
-        assert_eq!(inner.num(Ordering::SeqCst), 0);
-    })
-}
-*/
diff --git a/vendor/tokio/src/time/driver/wheel/level.rs b/vendor/tokio/src/runtime/time/wheel/level.rs
index 81d6b58c7..7e48ff5c5 100644
--- a/vendor/tokio/src/time/driver/wheel/level.rs
+++ b/vendor/tokio/src/runtime/time/wheel/level.rs
@@ -1,6 +1,4 @@
-use crate::time::driver::TimerHandle;
-
-use crate::time::driver::{EntryList, TimerShared};
+use crate::runtime::time::{EntryList, TimerHandle, TimerShared};
 
 use std::{fmt, ptr::NonNull};
 
@@ -53,7 +51,7 @@ impl Level {
         // However, that is only supported for arrays of size
         // 32 or fewer.  So in our case we have to explicitly
         // invoke the constructor for each array element.
-        let ctor = || EntryList::default();
+        let ctor = EntryList::default;
 
         Level {
             level,
@@ -143,8 +141,9 @@ impl Level {
         let level_range = level_range(self.level);
         let slot_range = slot_range(self.level);
 
-        // TODO: This can probably be simplified w/ power of 2 math
-        let level_start = now - (now % level_range);
+        // Compute the start date of the current level by masking the low bits
+        // of `now` (`level_range` is a power of 2).
+        let level_start = now & !(level_range - 1);
         let mut deadline = level_start + slot as u64 * slot_range;
 
         if deadline <= now {
@@ -250,7 +249,7 @@ fn level_range(level: usize) -> u64 {
     LEVEL_MULT as u64 * slot_range(level)
 }
 
-/// Convert a duration (milliseconds) and a level to a slot position
+/// Converts a duration (milliseconds) and a level to a slot position.
 fn slot_for(duration: u64, level: usize) -> usize {
     ((duration >> (level * 6)) % LEVEL_MULT as u64) as usize
 }
diff --git a/vendor/tokio/src/time/driver/wheel/mod.rs b/vendor/tokio/src/runtime/time/wheel/mod.rs
index 5a40f6db8..bf13b7b24 100644
--- a/vendor/tokio/src/time/driver/wheel/mod.rs
+++ b/vendor/tokio/src/runtime/time/wheel/mod.rs
@@ -1,4 +1,4 @@
-use crate::time::driver::{TimerHandle, TimerShared};
+use crate::runtime::time::{TimerHandle, TimerShared};
 use crate::time::error::InsertError;
 
 mod level;
@@ -46,11 +46,11 @@ pub(crate) struct Wheel {
 /// precision of 1 millisecond.
 const NUM_LEVELS: usize = 6;
 
-/// The maximum duration of a `Sleep`
+/// The maximum duration of a `Sleep`.
 pub(super) const MAX_DURATION: u64 = (1 << (6 * NUM_LEVELS)) - 1;
 
 impl Wheel {
-    /// Create a new timing wheel
+    /// Creates a new timing wheel.
     pub(crate) fn new() -> Wheel {
         let levels = (0..NUM_LEVELS).map(Level::new).collect();
 
@@ -61,13 +61,13 @@ impl Wheel {
         }
     }
 
-    /// Return the number of milliseconds that have elapsed since the timing
+    /// Returns the number of milliseconds that have elapsed since the timing
     /// wheel's creation.
     pub(crate) fn elapsed(&self) -> u64 {
         self.elapsed
     }
 
-    /// Insert an entry into the timing wheel.
+    /// Inserts an entry into the timing wheel.
     ///
     /// # Arguments
     ///
@@ -115,7 +115,7 @@ impl Wheel {
         Ok(when)
     }
 
-    /// Remove `item` from the timing wheel.
+    /// Removes `item` from the timing wheel.
     pub(crate) unsafe fn remove(&mut self, item: NonNull<TimerShared>) {
         unsafe {
             let when = item.as_ref().cached_when();
@@ -136,7 +136,7 @@ impl Wheel {
         }
     }
 
-    /// Instant at which to poll
+    /// Instant at which to poll.
     pub(crate) fn poll_at(&self) -> Option<u64> {
         self.next_expiration().map(|expiration| expiration.deadline)
     }
@@ -148,23 +148,13 @@ impl Wheel {
                 return Some(handle);
             }
 
-            // under what circumstances is poll.expiration Some vs. None?
-            let expiration = self.next_expiration().and_then(|expiration| {
-                if expiration.deadline > now {
-                    None
-                } else {
-                    Some(expiration)
-                }
-            });
-
-            match expiration {
-                Some(ref expiration) if expiration.deadline > now => return None,
-                Some(ref expiration) => {
+            match self.next_expiration() {
+                Some(ref expiration) if expiration.deadline <= now => {
                     self.process_expiration(expiration);
 
                     self.set_elapsed(expiration.deadline);
                 }
-                None => {
+                _ => {
                     // in this case the poll did not indicate an expiration
                     // _and_ we were not able to find a next expiration in
                     // the current list of timers.  advance to the poll's
diff --git a/vendor/tokio/src/signal/ctrl_c.rs b/vendor/tokio/src/signal/ctrl_c.rs
index 1eeeb85aa..b26ab7ead 100644
--- a/vendor/tokio/src/signal/ctrl_c.rs
+++ b/vendor/tokio/src/signal/ctrl_c.rs
@@ -47,6 +47,15 @@ use std::io;
 ///     println!("received ctrl-c event");
 /// }
 /// ```
+///
+/// Listen in the background:
+///
+/// ```rust,no_run
+/// tokio::spawn(async move {
+///     tokio::signal::ctrl_c().await.unwrap();
+///     // Your handler here
+/// });
+/// ```
 pub async fn ctrl_c() -> io::Result<()> {
     os_impl::ctrl_c()?.recv().await;
     Ok(())
diff --git a/vendor/tokio/src/signal/mod.rs b/vendor/tokio/src/signal/mod.rs
index fe572f041..3aacc60ef 100644
--- a/vendor/tokio/src/signal/mod.rs
+++ b/vendor/tokio/src/signal/mod.rs
@@ -1,4 +1,4 @@
-//! Asynchronous signal handling for Tokio
+//! Asynchronous signal handling for Tokio.
 //!
 //! Note that signal handling is in general a very tricky topic and should be
 //! used with great care. This crate attempts to implement 'best practice' for
@@ -48,7 +48,7 @@ use std::task::{Context, Poll};
 mod ctrl_c;
 pub use ctrl_c::ctrl_c;
 
-mod registry;
+pub(crate) mod registry;
 
 mod os {
     #[cfg(unix)]
diff --git a/vendor/tokio/src/signal/registry.rs b/vendor/tokio/src/signal/registry.rs
index 8b89108a6..48e98c832 100644
--- a/vendor/tokio/src/signal/registry.rs
+++ b/vendor/tokio/src/signal/registry.rs
@@ -1,12 +1,10 @@
 #![allow(clippy::unit_arg)]
 
 use crate::signal::os::{OsExtraData, OsStorage};
-
 use crate::sync::watch;
+use crate::util::once_cell::OnceCell;
 
-use once_cell::sync::Lazy;
 use std::ops;
-use std::pin::Pin;
 use std::sync::atomic::{AtomicBool, Ordering};
 
 pub(crate) type EventId = usize;
@@ -152,19 +150,25 @@ impl Globals {
     }
 }
 
-pub(crate) fn globals() -> Pin<&'static Globals>
+fn globals_init() -> Globals
 where
     OsExtraData: 'static + Send + Sync + Init,
     OsStorage: 'static + Send + Sync + Init,
 {
-    static GLOBALS: Lazy<Pin<Box<Globals>>> = Lazy::new(|| {
-        Box::pin(Globals {
-            extra: OsExtraData::init(),
-            registry: Registry::new(OsStorage::init()),
-        })
-    });
-
-    GLOBALS.as_ref()
+    Globals {
+        extra: OsExtraData::init(),
+        registry: Registry::new(OsStorage::init()),
+    }
+}
+
+pub(crate) fn globals() -> &'static Globals
+where
+    OsExtraData: 'static + Send + Sync + Init,
+    OsStorage: 'static + Send + Sync + Init,
+{
+    static GLOBALS: OnceCell<Globals> = OnceCell::new();
+
+    GLOBALS.get(globals_init)
 }
 
 #[cfg(all(test, not(loom)))]
@@ -202,7 +206,12 @@ mod tests {
                 registry.broadcast();
 
                 // Yield so the previous broadcast can get received
-                crate::time::sleep(std::time::Duration::from_millis(10)).await;
+                //
+                // This yields many times since the block_on task is only polled every 61
+                // ticks.
+                for _ in 0..100 {
+                    crate::task::yield_now().await;
+                }
 
                 // Send subsequent signal
                 registry.record_event(0);
@@ -232,7 +241,7 @@ mod tests {
     #[test]
     fn record_invalid_event_does_nothing() {
         let registry = Registry::new(vec![EventInfo::default()]);
-        registry.record_event(42);
+        registry.record_event(1302);
     }
 
     #[test]
@@ -240,17 +249,17 @@ mod tests {
         let registry = Registry::new(vec![EventInfo::default(), EventInfo::default()]);
 
         registry.record_event(0);
-        assert_eq!(false, registry.broadcast());
+        assert!(!registry.broadcast());
 
         let first = registry.register_listener(0);
         let second = registry.register_listener(1);
 
         registry.record_event(0);
-        assert_eq!(true, registry.broadcast());
+        assert!(registry.broadcast());
 
         drop(first);
         registry.record_event(0);
-        assert_eq!(false, registry.broadcast());
+        assert!(!registry.broadcast());
 
         drop(second);
     }
diff --git a/vendor/tokio/src/signal/reusable_box.rs b/vendor/tokio/src/signal/reusable_box.rs
index 426ecb06f..796fa210b 100644
--- a/vendor/tokio/src/signal/reusable_box.rs
+++ b/vendor/tokio/src/signal/reusable_box.rs
@@ -30,7 +30,7 @@ impl<T> ReusableBoxFuture<T> {
         Self { boxed }
     }
 
-    /// Replace the future currently stored in this box.
+    /// Replaces the future currently stored in this box.
     ///
     /// This reallocates if and only if the layout of the provided future is
     /// different from the layout of the currently stored future.
@@ -43,7 +43,7 @@ impl<T> ReusableBoxFuture<T> {
         }
     }
 
-    /// Replace the future currently stored in this box.
+    /// Replaces the future currently stored in this box.
     ///
     /// This function never reallocates, but returns an error if the provided
     /// future has a different size or alignment from the currently stored
@@ -70,7 +70,7 @@ impl<T> ReusableBoxFuture<T> {
         }
     }
 
-    /// Set the current future.
+    /// Sets the current future.
     ///
     /// # Safety
     ///
@@ -103,14 +103,14 @@ impl<T> ReusableBoxFuture<T> {
         }
     }
 
-    /// Get a pinned reference to the underlying future.
+    /// Gets a pinned reference to the underlying future.
     pub(crate) fn get_pin(&mut self) -> Pin<&mut (dyn Future<Output = T> + Send)> {
         // SAFETY: The user of this box cannot move the box, and we do not move it
         // either.
         unsafe { Pin::new_unchecked(self.boxed.as_mut()) }
     }
 
-    /// Poll the future stored inside this box.
+    /// Polls the future stored inside this box.
     pub(crate) fn poll(&mut self, cx: &mut Context<'_>) -> Poll<T> {
         self.get_pin().poll(cx)
     }
@@ -119,7 +119,7 @@ impl<T> ReusableBoxFuture<T> {
 impl<T> Future for ReusableBoxFuture<T> {
     type Output = T;
 
-    /// Poll the future stored inside this box.
+    /// Polls the future stored inside this box.
     fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<T> {
         Pin::into_inner(self).get_pin().poll(cx)
     }
diff --git a/vendor/tokio/src/signal/unix.rs b/vendor/tokio/src/signal/unix.rs
index f96b2f4c2..ae5c13085 100644
--- a/vendor/tokio/src/signal/unix.rs
+++ b/vendor/tokio/src/signal/unix.rs
@@ -4,30 +4,33 @@
 //! `Signal` type for receiving notifications of signals.
 
 #![cfg(unix)]
+#![cfg_attr(docsrs, doc(cfg(all(unix, feature = "signal"))))]
 
+use crate::runtime::scheduler;
+use crate::runtime::signal::Handle;
 use crate::signal::registry::{globals, EventId, EventInfo, Globals, Init, Storage};
 use crate::signal::RxFuture;
 use crate::sync::watch;
 
 use mio::net::UnixStream;
 use std::io::{self, Error, ErrorKind, Write};
-use std::pin::Pin;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::Once;
 use std::task::{Context, Poll};
 
-pub(crate) mod driver;
-use self::driver::Handle;
-
 pub(crate) type OsStorage = Vec<SignalInfo>;
 
-// Number of different unix signals
-// (FreeBSD has 33)
-const SIGNUM: usize = 33;
-
 impl Init for OsStorage {
     fn init() -> Self {
-        (0..SIGNUM).map(|_| SignalInfo::default()).collect()
+        // There are reliable signals ranging from 1 to 33 available on every Unix platform.
+        #[cfg(not(target_os = "linux"))]
+        let possible = 0..=33;
+
+        // On Linux, there are additional real-time signals available.
+        #[cfg(target_os = "linux")]
+        let possible = 0..=libc::SIGRTMAX();
+
+        possible.map(|_| SignalInfo::default()).collect()
     }
 }
 
@@ -47,7 +50,7 @@ impl Storage for OsStorage {
 #[derive(Debug)]
 pub(crate) struct OsExtraData {
     sender: UnixStream,
-    receiver: UnixStream,
+    pub(crate) receiver: UnixStream,
 }
 
 impl Init for OsExtraData {
@@ -59,7 +62,7 @@ impl Init for OsExtraData {
 }
 
 /// Represents the specific kind of signal to listen for.
-#[derive(Debug, Clone, Copy)]
+#[derive(Debug, Clone, Copy, Hash, PartialEq, Eq)]
 pub struct SignalKind(libc::c_int);
 
 impl SignalKind {
@@ -79,15 +82,26 @@ impl SignalKind {
     // unlikely to change to other types, but technically libc can change this
     // in the future minor version.
     // See https://github.com/tokio-rs/tokio/issues/3767 for more.
-    pub fn from_raw(signum: std::os::raw::c_int) -> Self {
+    pub const fn from_raw(signum: std::os::raw::c_int) -> Self {
         Self(signum as libc::c_int)
     }
 
+    /// Get the signal's numeric value.
+    ///
+    /// ```rust
+    /// # use tokio::signal::unix::SignalKind;
+    /// let kind = SignalKind::interrupt();
+    /// assert_eq!(kind.as_raw_value(), libc::SIGINT);
+    /// ```
+    pub const fn as_raw_value(&self) -> std::os::raw::c_int {
+        self.0
+    }
+
     /// Represents the SIGALRM signal.
     ///
     /// On Unix systems this signal is sent when a real-time timer has expired.
     /// By default, the process is terminated by this signal.
-    pub fn alarm() -> Self {
+    pub const fn alarm() -> Self {
         Self(libc::SIGALRM)
     }
 
@@ -95,7 +109,7 @@ impl SignalKind {
     ///
     /// On Unix systems this signal is sent when the status of a child process
     /// has changed. By default, this signal is ignored.
-    pub fn child() -> Self {
+    pub const fn child() -> Self {
         Self(libc::SIGCHLD)
     }
 
@@ -103,7 +117,7 @@ impl SignalKind {
     ///
     /// On Unix systems this signal is sent when the terminal is disconnected.
     /// By default, the process is terminated by this signal.
-    pub fn hangup() -> Self {
+    pub const fn hangup() -> Self {
         Self(libc::SIGHUP)
     }
 
@@ -118,7 +132,7 @@ impl SignalKind {
         target_os = "netbsd",
         target_os = "openbsd"
     ))]
-    pub fn info() -> Self {
+    pub const fn info() -> Self {
         Self(libc::SIGINFO)
     }
 
@@ -126,7 +140,7 @@ impl SignalKind {
     ///
     /// On Unix systems this signal is sent to interrupt a program.
     /// By default, the process is terminated by this signal.
-    pub fn interrupt() -> Self {
+    pub const fn interrupt() -> Self {
         Self(libc::SIGINT)
     }
 
@@ -134,7 +148,7 @@ impl SignalKind {
     ///
     /// On Unix systems this signal is sent when I/O operations are possible
     /// on some file descriptor. By default, this signal is ignored.
-    pub fn io() -> Self {
+    pub const fn io() -> Self {
         Self(libc::SIGIO)
     }
 
@@ -143,7 +157,7 @@ impl SignalKind {
     /// On Unix systems this signal is sent when the process attempts to write
     /// to a pipe which has no reader. By default, the process is terminated by
     /// this signal.
-    pub fn pipe() -> Self {
+    pub const fn pipe() -> Self {
         Self(libc::SIGPIPE)
     }
 
@@ -152,7 +166,7 @@ impl SignalKind {
     /// On Unix systems this signal is sent to issue a shutdown of the
     /// process, after which the OS will dump the process core.
     /// By default, the process is terminated by this signal.
-    pub fn quit() -> Self {
+    pub const fn quit() -> Self {
         Self(libc::SIGQUIT)
     }
 
@@ -160,7 +174,7 @@ impl SignalKind {
     ///
     /// On Unix systems this signal is sent to issue a shutdown of the
     /// process. By default, the process is terminated by this signal.
-    pub fn terminate() -> Self {
+    pub const fn terminate() -> Self {
         Self(libc::SIGTERM)
     }
 
@@ -168,7 +182,7 @@ impl SignalKind {
     ///
     /// On Unix systems this is a user defined signal.
     /// By default, the process is terminated by this signal.
-    pub fn user_defined1() -> Self {
+    pub const fn user_defined1() -> Self {
         Self(libc::SIGUSR1)
     }
 
@@ -176,7 +190,7 @@ impl SignalKind {
     ///
     /// On Unix systems this is a user defined signal.
     /// By default, the process is terminated by this signal.
-    pub fn user_defined2() -> Self {
+    pub const fn user_defined2() -> Self {
         Self(libc::SIGUSR2)
     }
 
@@ -184,11 +198,23 @@ impl SignalKind {
     ///
     /// On Unix systems this signal is sent when the terminal window is resized.
     /// By default, this signal is ignored.
-    pub fn window_change() -> Self {
+    pub const fn window_change() -> Self {
         Self(libc::SIGWINCH)
     }
 }
 
+impl From<std::os::raw::c_int> for SignalKind {
+    fn from(signum: std::os::raw::c_int) -> Self {
+        Self::from_raw(signum as libc::c_int)
+    }
+}
+
+impl From<SignalKind> for std::os::raw::c_int {
+    fn from(kind: SignalKind) -> Self {
+        kind.as_raw_value()
+    }
+}
+
 pub(crate) struct SignalInfo {
     event_info: EventInfo,
     init: Once,
@@ -213,7 +239,7 @@ impl Default for SignalInfo {
 /// 2. Wake up the driver by writing a byte to a pipe
 ///
 /// Those two operations should both be async-signal safe.
-fn action(globals: Pin<&'static Globals>, signal: libc::c_int) {
+fn action(globals: &'static Globals, signal: libc::c_int) {
     globals.record_event(signal as EventId);
 
     // Send a wakeup, ignore any errors (anything reasonably possible is
@@ -266,7 +292,11 @@ fn signal_enable(signal: SignalKind, handle: &Handle) -> io::Result<()> {
     }
 }
 
-/// A stream of events for receiving a particular type of OS signal.
+/// An listener for receiving a particular type of OS signal.
+///
+/// The listener can be turned into a `Stream` using [`SignalStream`].
+///
+/// [`SignalStream`]: https://docs.rs/tokio-stream/latest/tokio_stream/wrappers/struct.SignalStream.html
 ///
 /// In general signal handling on Unix is a pretty tricky topic, and this
 /// structure is no exception! There are some important limitations to keep in
@@ -281,7 +311,7 @@ fn signal_enable(signal: SignalKind, handle: &Handle) -> io::Result<()> {
 ///   Once `poll` has been called, however, a further signal is guaranteed to
 ///   be yielded as an item.
 ///
-///   Put another way, any element pulled off the returned stream corresponds to
+///   Put another way, any element pulled off the returned listener corresponds to
 ///   *at least one* signal, but possibly more.
 ///
 /// * Signal handling in general is relatively inefficient. Although some
@@ -319,11 +349,11 @@ fn signal_enable(signal: SignalKind, handle: &Handle) -> io::Result<()> {
 /// #[tokio::main]
 /// async fn main() -> Result<(), Box<dyn std::error::Error>> {
 ///     // An infinite stream of hangup signals.
-///     let mut stream = signal(SignalKind::hangup())?;
+///     let mut sig = signal(SignalKind::hangup())?;
 ///
 ///     // Print whenever a HUP signal is received
 ///     loop {
-///         stream.recv().await;
+///         sig.recv().await;
 ///         println!("got signal HUP");
 ///     }
 /// }
@@ -334,7 +364,7 @@ pub struct Signal {
     inner: RxFuture,
 }
 
-/// Creates a new stream which will receive notifications when the current
+/// Creates a new listener which will receive notifications when the current
 /// process receives the specified signal `kind`.
 ///
 /// This function will create a new stream which binds to the default reactor.
@@ -356,8 +386,15 @@ pub struct Signal {
 /// * If the previous initialization of this specific signal failed.
 /// * If the signal is one of
 ///   [`signal_hook::FORBIDDEN`](fn@signal_hook_registry::register#panics)
+///
+/// # Panics
+///
+/// This function panics if there is no current reactor set, or if the `rt`
+/// feature flag is not enabled.
+#[track_caller]
 pub fn signal(kind: SignalKind) -> io::Result<Signal> {
-    let rx = signal_with_handle(kind, &Handle::current())?;
+    let handle = scheduler::Handle::current();
+    let rx = signal_with_handle(kind, handle.driver().signal())?;
 
     Ok(Signal {
         inner: RxFuture::new(rx),
@@ -379,6 +416,12 @@ impl Signal {
     ///
     /// `None` is returned if no more events can be received by this stream.
     ///
+    /// # Cancel safety
+    ///
+    /// This method is cancel safe. If you use it as the event in a
+    /// [`tokio::select!`](crate::select) statement and some other branch
+    /// completes first, then it is guaranteed that no signal is lost.
+    ///
     /// # Examples
     ///
     /// Wait for SIGHUP
@@ -473,4 +516,15 @@ mod tests {
         )
         .unwrap_err();
     }
+
+    #[test]
+    fn from_c_int() {
+        assert_eq!(SignalKind::from(2), SignalKind::interrupt());
+    }
+
+    #[test]
+    fn into_c_int() {
+        let value: std::os::raw::c_int = SignalKind::interrupt().into();
+        assert_eq!(value, libc::SIGINT as _);
+    }
 }
diff --git a/vendor/tokio/src/signal/unix/driver.rs b/vendor/tokio/src/signal/unix/driver.rs
deleted file mode 100644
index 5fe7c354c..000000000
--- a/vendor/tokio/src/signal/unix/driver.rs
+++ /dev/null
@@ -1,207 +0,0 @@
-#![cfg_attr(not(feature = "rt"), allow(dead_code))]
-
-//! Signal driver
-
-use crate::io::driver::{Driver as IoDriver, Interest};
-use crate::io::PollEvented;
-use crate::park::Park;
-use crate::signal::registry::globals;
-
-use mio::net::UnixStream;
-use std::io::{self, Read};
-use std::ptr;
-use std::sync::{Arc, Weak};
-use std::task::{Context, Poll, RawWaker, RawWakerVTable, Waker};
-use std::time::Duration;
-
-/// Responsible for registering wakeups when an OS signal is received, and
-/// subsequently dispatching notifications to any signal listeners as appropriate.
-///
-/// Note: this driver relies on having an enabled IO driver in order to listen to
-/// pipe write wakeups.
-#[derive(Debug)]
-pub(crate) struct Driver {
-    /// Thread parker. The `Driver` park implementation delegates to this.
-    park: IoDriver,
-
-    /// A pipe for receiving wake events from the signal handler
-    receiver: PollEvented<UnixStream>,
-
-    /// Shared state
-    inner: Arc<Inner>,
-}
-
-#[derive(Clone, Debug, Default)]
-pub(crate) struct Handle {
-    inner: Weak<Inner>,
-}
-
-#[derive(Debug)]
-pub(super) struct Inner(());
-
-// ===== impl Driver =====
-
-impl Driver {
-    /// Creates a new signal `Driver` instance that delegates wakeups to `park`.
-    pub(crate) fn new(park: IoDriver) -> io::Result<Self> {
-        use std::mem::ManuallyDrop;
-        use std::os::unix::io::{AsRawFd, FromRawFd};
-
-        // NB: We give each driver a "fresh" receiver file descriptor to avoid
-        // the issues described in alexcrichton/tokio-process#42.
-        //
-        // In the past we would reuse the actual receiver file descriptor and
-        // swallow any errors around double registration of the same descriptor.
-        // I'm not sure if the second (failed) registration simply doesn't end
-        // up receiving wake up notifications, or there could be some race
-        // condition when consuming readiness events, but having distinct
-        // descriptors for distinct PollEvented instances appears to mitigate
-        // this.
-        //
-        // Unfortunately we cannot just use a single global PollEvented instance
-        // either, since we can't compare Handles or assume they will always
-        // point to the exact same reactor.
-        //
-        // Mio 0.7 removed `try_clone()` as an API due to unexpected behavior
-        // with registering dups with the same reactor. In this case, duping is
-        // safe as each dup is registered with separate reactors **and** we
-        // only expect at least one dup to receive the notification.
-
-        // Manually drop as we don't actually own this instance of UnixStream.
-        let receiver_fd = globals().receiver.as_raw_fd();
-
-        // safety: there is nothing unsafe about this, but the `from_raw_fd` fn is marked as unsafe.
-        let original =
-            ManuallyDrop::new(unsafe { std::os::unix::net::UnixStream::from_raw_fd(receiver_fd) });
-        let receiver = UnixStream::from_std(original.try_clone()?);
-        let receiver = PollEvented::new_with_interest_and_handle(
-            receiver,
-            Interest::READABLE | Interest::WRITABLE,
-            park.handle(),
-        )?;
-
-        Ok(Self {
-            park,
-            receiver,
-            inner: Arc::new(Inner(())),
-        })
-    }
-
-    /// Returns a handle to this event loop which can be sent across threads
-    /// and can be used as a proxy to the event loop itself.
-    pub(crate) fn handle(&self) -> Handle {
-        Handle {
-            inner: Arc::downgrade(&self.inner),
-        }
-    }
-
-    fn process(&self) {
-        // Check if the pipe is ready to read and therefore has "woken" us up
-        //
-        // To do so, we will `poll_read_ready` with a noop waker, since we don't
-        // need to actually be notified when read ready...
-        let waker = unsafe { Waker::from_raw(RawWaker::new(ptr::null(), &NOOP_WAKER_VTABLE)) };
-        let mut cx = Context::from_waker(&waker);
-
-        let ev = match self.receiver.registration().poll_read_ready(&mut cx) {
-            Poll::Ready(Ok(ev)) => ev,
-            Poll::Ready(Err(e)) => panic!("reactor gone: {}", e),
-            Poll::Pending => return, // No wake has arrived, bail
-        };
-
-        // Drain the pipe completely so we can receive a new readiness event
-        // if another signal has come in.
-        let mut buf = [0; 128];
-        loop {
-            match (&*self.receiver).read(&mut buf) {
-                Ok(0) => panic!("EOF on self-pipe"),
-                Ok(_) => continue, // Keep reading
-                Err(e) if e.kind() == io::ErrorKind::WouldBlock => break,
-                Err(e) => panic!("Bad read on self-pipe: {}", e),
-            }
-        }
-
-        self.receiver.registration().clear_readiness(ev);
-
-        // Broadcast any signals which were received
-        globals().broadcast();
-    }
-}
-
-const NOOP_WAKER_VTABLE: RawWakerVTable = RawWakerVTable::new(noop_clone, noop, noop, noop);
-
-unsafe fn noop_clone(_data: *const ()) -> RawWaker {
-    RawWaker::new(ptr::null(), &NOOP_WAKER_VTABLE)
-}
-
-unsafe fn noop(_data: *const ()) {}
-
-// ===== impl Park for Driver =====
-
-impl Park for Driver {
-    type Unpark = <IoDriver as Park>::Unpark;
-    type Error = io::Error;
-
-    fn unpark(&self) -> Self::Unpark {
-        self.park.unpark()
-    }
-
-    fn park(&mut self) -> Result<(), Self::Error> {
-        self.park.park()?;
-        self.process();
-        Ok(())
-    }
-
-    fn park_timeout(&mut self, duration: Duration) -> Result<(), Self::Error> {
-        self.park.park_timeout(duration)?;
-        self.process();
-        Ok(())
-    }
-
-    fn shutdown(&mut self) {
-        self.park.shutdown()
-    }
-}
-
-// ===== impl Handle =====
-
-impl Handle {
-    pub(super) fn check_inner(&self) -> io::Result<()> {
-        if self.inner.strong_count() > 0 {
-            Ok(())
-        } else {
-            Err(io::Error::new(io::ErrorKind::Other, "signal driver gone"))
-        }
-    }
-}
-
-cfg_rt! {
-    impl Handle {
-        /// Returns a handle to the current driver
-        ///
-        /// # Panics
-        ///
-        /// This function panics if there is no current signal driver set.
-        pub(super) fn current() -> Self {
-            crate::runtime::context::signal_handle().expect(
-                "there is no signal driver running, must be called from the context of Tokio runtime",
-            )
-        }
-    }
-}
-
-cfg_not_rt! {
-    impl Handle {
-        /// Returns a handle to the current driver
-        ///
-        /// # Panics
-        ///
-        /// This function panics if there is no current signal driver set.
-        pub(super) fn current() -> Self {
-            panic!(
-                "there is no signal driver running, must be called from the context of Tokio runtime or with\
-                `rt` enabled.",
-            )
-        }
-    }
-}
diff --git a/vendor/tokio/src/signal/windows.rs b/vendor/tokio/src/signal/windows.rs
index c231d6268..2f70f98b1 100644
--- a/vendor/tokio/src/signal/windows.rs
+++ b/vendor/tokio/src/signal/windows.rs
@@ -1,133 +1,28 @@
 //! Windows-specific types for signal handling.
 //!
-//! This module is only defined on Windows and allows receiving "ctrl-c"
-//! and "ctrl-break" notifications. These events are listened for via the
-//! `SetConsoleCtrlHandler` function which receives events of the type
-//! `CTRL_C_EVENT` and `CTRL_BREAK_EVENT`.
+//! This module is only defined on Windows and allows receiving "ctrl-c",
+//! "ctrl-break", "ctrl-logoff", "ctrl-shutdown", and "ctrl-close"
+//! notifications. These events are listened for via the `SetConsoleCtrlHandler`
+//! function which receives the corresponding windows_sys event type.
 
-#![cfg(windows)]
+#![cfg(any(windows, docsrs))]
+#![cfg_attr(docsrs, doc(cfg(all(windows, feature = "signal"))))]
 
-use crate::signal::registry::{globals, EventId, EventInfo, Init, Storage};
 use crate::signal::RxFuture;
-
-use std::convert::TryFrom;
 use std::io;
-use std::sync::Once;
 use std::task::{Context, Poll};
-use winapi::shared::minwindef::{BOOL, DWORD, FALSE, TRUE};
-use winapi::um::consoleapi::SetConsoleCtrlHandler;
-use winapi::um::wincon::{CTRL_BREAK_EVENT, CTRL_C_EVENT};
-
-#[derive(Debug)]
-pub(crate) struct OsStorage {
-    ctrl_c: EventInfo,
-    ctrl_break: EventInfo,
-}
 
-impl Init for OsStorage {
-    fn init() -> Self {
-        Self {
-            ctrl_c: EventInfo::default(),
-            ctrl_break: EventInfo::default(),
-        }
-    }
-}
-
-impl Storage for OsStorage {
-    fn event_info(&self, id: EventId) -> Option<&EventInfo> {
-        match DWORD::try_from(id) {
-            Ok(CTRL_C_EVENT) => Some(&self.ctrl_c),
-            Ok(CTRL_BREAK_EVENT) => Some(&self.ctrl_break),
-            _ => None,
-        }
-    }
+#[cfg(not(docsrs))]
+#[path = "windows/sys.rs"]
+mod imp;
+#[cfg(not(docsrs))]
+pub(crate) use self::imp::{OsExtraData, OsStorage};
 
-    fn for_each<'a, F>(&'a self, mut f: F)
-    where
-        F: FnMut(&'a EventInfo),
-    {
-        f(&self.ctrl_c);
-        f(&self.ctrl_break);
-    }
-}
-
-#[derive(Debug)]
-pub(crate) struct OsExtraData {}
-
-impl Init for OsExtraData {
-    fn init() -> Self {
-        Self {}
-    }
-}
+#[cfg(docsrs)]
+#[path = "windows/stub.rs"]
+mod imp;
 
-/// Stream of events discovered via `SetConsoleCtrlHandler`.
-///
-/// This structure can be used to listen for events of the type `CTRL_C_EVENT`
-/// and `CTRL_BREAK_EVENT`. The `Stream` trait is implemented for this struct
-/// and will resolve for each notification received by the process. Note that
-/// there are few limitations with this as well:
-///
-/// * A notification to this process notifies *all* `Event` streams for that
-///   event type.
-/// * Notifications to an `Event` stream **are coalesced** if they aren't
-///   processed quickly enough. This means that if two notifications are
-///   received back-to-back, then the stream may only receive one item about the
-///   two notifications.
-#[must_use = "streams do nothing unless polled"]
-#[derive(Debug)]
-pub(crate) struct Event {
-    inner: RxFuture,
-}
-
-impl Event {
-    fn new(signum: DWORD) -> io::Result<Self> {
-        global_init()?;
-
-        let rx = globals().register_listener(signum as EventId);
-
-        Ok(Self {
-            inner: RxFuture::new(rx),
-        })
-    }
-}
-
-fn global_init() -> io::Result<()> {
-    static INIT: Once = Once::new();
-
-    let mut init = None;
-
-    INIT.call_once(|| unsafe {
-        let rc = SetConsoleCtrlHandler(Some(handler), TRUE);
-        let ret = if rc == 0 {
-            Err(io::Error::last_os_error())
-        } else {
-            Ok(())
-        };
-
-        init = Some(ret);
-    });
-
-    init.unwrap_or_else(|| Ok(()))
-}
-
-unsafe extern "system" fn handler(ty: DWORD) -> BOOL {
-    let globals = globals();
-    globals.record_event(ty as EventId);
-
-    // According to https://docs.microsoft.com/en-us/windows/console/handlerroutine
-    // the handler routine is always invoked in a new thread, thus we don't
-    // have the same restrictions as in Unix signal handlers, meaning we can
-    // go ahead and perform the broadcast here.
-    if globals.broadcast() {
-        TRUE
-    } else {
-        // No one is listening for this notification any more
-        // let the OS fire the next (possibly the default) handler.
-        FALSE
-    }
-}
-
-/// Creates a new stream which receives "ctrl-c" notifications sent to the
+/// Creates a new listener which receives "ctrl-c" notifications sent to the
 /// process.
 ///
 /// # Examples
@@ -137,12 +32,12 @@ unsafe extern "system" fn handler(ty: DWORD) -> BOOL {
 ///
 /// #[tokio::main]
 /// async fn main() -> Result<(), Box<dyn std::error::Error>> {
-///     // An infinite stream of CTRL-C events.
-///     let mut stream = ctrl_c()?;
+///     // A listener of CTRL-C events.
+///     let mut signal = ctrl_c()?;
 ///
 ///     // Print whenever a CTRL-C event is received.
 ///     for countdown in (0..3).rev() {
-///         stream.recv().await;
+///         signal.recv().await;
 ///         println!("got CTRL-C. {} more to exit", countdown);
 ///     }
 ///
@@ -150,26 +45,32 @@ unsafe extern "system" fn handler(ty: DWORD) -> BOOL {
 /// }
 /// ```
 pub fn ctrl_c() -> io::Result<CtrlC> {
-    Event::new(CTRL_C_EVENT).map(|inner| CtrlC { inner })
+    Ok(CtrlC {
+        inner: self::imp::ctrl_c()?,
+    })
 }
 
-/// Represents a stream which receives "ctrl-c" notifications sent to the process
+/// Represents a listener which receives "ctrl-c" notifications sent to the process
 /// via `SetConsoleCtrlHandler`.
 ///
-/// A notification to this process notifies *all* streams listening for
+/// This event can be turned into a `Stream` using [`CtrlCStream`].
+///
+/// [`CtrlCStream`]: https://docs.rs/tokio-stream/latest/tokio_stream/wrappers/struct.CtrlCStream.html
+///
+/// A notification to this process notifies *all* receivers for
 /// this event. Moreover, the notifications **are coalesced** if they aren't processed
 /// quickly enough. This means that if two notifications are received back-to-back,
-/// then the stream may only receive one item about the two notifications.
-#[must_use = "streams do nothing unless polled"]
+/// then the listener may only receive one item about the two notifications.
+#[must_use = "listeners do nothing unless polled"]
 #[derive(Debug)]
 pub struct CtrlC {
-    inner: Event,
+    inner: RxFuture,
 }
 
 impl CtrlC {
     /// Receives the next signal notification event.
     ///
-    /// `None` is returned if no more events can be received by this stream.
+    /// `None` is returned if no more events can be received by the listener.
     ///
     /// # Examples
     ///
@@ -178,12 +79,11 @@ impl CtrlC {
     ///
     /// #[tokio::main]
     /// async fn main() -> Result<(), Box<dyn std::error::Error>> {
-    ///     // An infinite stream of CTRL-C events.
-    ///     let mut stream = ctrl_c()?;
+    ///     let mut signal = ctrl_c()?;
     ///
     ///     // Print whenever a CTRL-C event is received.
     ///     for countdown in (0..3).rev() {
-    ///         stream.recv().await;
+    ///         signal.recv().await;
     ///         println!("got CTRL-C. {} more to exit", countdown);
     ///     }
     ///
@@ -191,13 +91,13 @@ impl CtrlC {
     /// }
     /// ```
     pub async fn recv(&mut self) -> Option<()> {
-        self.inner.inner.recv().await
+        self.inner.recv().await
     }
 
     /// Polls to receive the next signal notification event, outside of an
     /// `async` context.
     ///
-    /// `None` is returned if no more events can be received by this stream.
+    /// `None` is returned if no more events can be received.
     ///
     /// # Examples
     ///
@@ -223,27 +123,31 @@ impl CtrlC {
     /// }
     /// ```
     pub fn poll_recv(&mut self, cx: &mut Context<'_>) -> Poll<Option<()>> {
-        self.inner.inner.poll_recv(cx)
+        self.inner.poll_recv(cx)
     }
 }
 
-/// Represents a stream which receives "ctrl-break" notifications sent to the process
+/// Represents a listener which receives "ctrl-break" notifications sent to the process
 /// via `SetConsoleCtrlHandler`.
 ///
-/// A notification to this process notifies *all* streams listening for
+/// This listener can be turned into a `Stream` using [`CtrlBreakStream`].
+///
+/// [`CtrlBreakStream`]: https://docs.rs/tokio-stream/latest/tokio_stream/wrappers/struct.CtrlBreakStream.html
+///
+/// A notification to this process notifies *all* receivers for
 /// this event. Moreover, the notifications **are coalesced** if they aren't processed
 /// quickly enough. This means that if two notifications are received back-to-back,
-/// then the stream may only receive one item about the two notifications.
-#[must_use = "streams do nothing unless polled"]
+/// then the listener may only receive one item about the two notifications.
+#[must_use = "listeners do nothing unless polled"]
 #[derive(Debug)]
 pub struct CtrlBreak {
-    inner: Event,
+    inner: RxFuture,
 }
 
 impl CtrlBreak {
     /// Receives the next signal notification event.
     ///
-    /// `None` is returned if no more events can be received by this stream.
+    /// `None` is returned if no more events can be received by this listener.
     ///
     /// # Examples
     ///
@@ -252,24 +156,24 @@ impl CtrlBreak {
     ///
     /// #[tokio::main]
     /// async fn main() -> Result<(), Box<dyn std::error::Error>> {
-    ///     // An infinite stream of CTRL-BREAK events.
-    ///     let mut stream = ctrl_break()?;
+    ///     // A listener of CTRL-BREAK events.
+    ///     let mut signal = ctrl_break()?;
     ///
     ///     // Print whenever a CTRL-BREAK event is received.
     ///     loop {
-    ///         stream.recv().await;
+    ///         signal.recv().await;
     ///         println!("got signal CTRL-BREAK");
     ///     }
     /// }
     /// ```
     pub async fn recv(&mut self) -> Option<()> {
-        self.inner.inner.recv().await
+        self.inner.recv().await
     }
 
     /// Polls to receive the next signal notification event, outside of an
     /// `async` context.
     ///
-    /// `None` is returned if no more events can be received by this stream.
+    /// `None` is returned if no more events can be received by this listener.
     ///
     /// # Examples
     ///
@@ -295,11 +199,11 @@ impl CtrlBreak {
     /// }
     /// ```
     pub fn poll_recv(&mut self, cx: &mut Context<'_>) -> Poll<Option<()>> {
-        self.inner.inner.poll_recv(cx)
+        self.inner.poll_recv(cx)
     }
 }
 
-/// Creates a new stream which receives "ctrl-break" notifications sent to the
+/// Creates a new listener which receives "ctrl-break" notifications sent to the
 /// process.
 ///
 /// # Examples
@@ -309,67 +213,312 @@ impl CtrlBreak {
 ///
 /// #[tokio::main]
 /// async fn main() -> Result<(), Box<dyn std::error::Error>> {
-///     // An infinite stream of CTRL-BREAK events.
-///     let mut stream = ctrl_break()?;
+///     // A listener of CTRL-BREAK events.
+///     let mut signal = ctrl_break()?;
 ///
 ///     // Print whenever a CTRL-BREAK event is received.
 ///     loop {
-///         stream.recv().await;
+///         signal.recv().await;
 ///         println!("got signal CTRL-BREAK");
 ///     }
 /// }
 /// ```
 pub fn ctrl_break() -> io::Result<CtrlBreak> {
-    Event::new(CTRL_BREAK_EVENT).map(|inner| CtrlBreak { inner })
+    Ok(CtrlBreak {
+        inner: self::imp::ctrl_break()?,
+    })
 }
 
-#[cfg(all(test, not(loom)))]
-mod tests {
-    use super::*;
-    use crate::runtime::Runtime;
+/// Creates a new listener which receives "ctrl-close" notifications sent to the
+/// process.
+///
+/// # Examples
+///
+/// ```rust,no_run
+/// use tokio::signal::windows::ctrl_close;
+///
+/// #[tokio::main]
+/// async fn main() -> Result<(), Box<dyn std::error::Error>> {
+///     // A listener of CTRL-CLOSE events.
+///     let mut signal = ctrl_close()?;
+///
+///     // Print whenever a CTRL-CLOSE event is received.
+///     for countdown in (0..3).rev() {
+///         signal.recv().await;
+///         println!("got CTRL-CLOSE. {} more to exit", countdown);
+///     }
+///
+///     Ok(())
+/// }
+/// ```
+pub fn ctrl_close() -> io::Result<CtrlClose> {
+    Ok(CtrlClose {
+        inner: self::imp::ctrl_close()?,
+    })
+}
 
-    use tokio_test::{assert_ok, assert_pending, assert_ready_ok, task};
+/// Represents a listener which receives "ctrl-close" notitifications sent to the process
+/// via 'SetConsoleCtrlHandler'.
+///
+/// A notification to this process notifies *all* listeners listening for
+/// this event. Moreover, the notifications **are coalesced** if they aren't processed
+/// quickly enough. This means that if two notifications are received back-to-back,
+/// then the listener may only receive one item about the two notifications.
+#[must_use = "listeners do nothing unless polled"]
+#[derive(Debug)]
+pub struct CtrlClose {
+    inner: RxFuture,
+}
 
-    #[test]
-    fn ctrl_c() {
-        let rt = rt();
-        let _enter = rt.enter();
+impl CtrlClose {
+    /// Receives the next signal notification event.
+    ///
+    /// `None` is returned if no more events can be received by this listener.
+    ///
+    /// # Examples
+    ///
+    /// ```rust,no_run
+    /// use tokio::signal::windows::ctrl_close;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> Result<(), Box<dyn std::error::Error>> {
+    ///     // A listener of CTRL-CLOSE events.
+    ///     let mut signal = ctrl_close()?;
+    ///
+    ///     // Print whenever a CTRL-CLOSE event is received.
+    ///     signal.recv().await;
+    ///     println!("got CTRL-CLOSE. Cleaning up before exiting");
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    pub async fn recv(&mut self) -> Option<()> {
+        self.inner.recv().await
+    }
 
-        let mut ctrl_c = task::spawn(crate::signal::ctrl_c());
+    /// Polls to receive the next signal notification event, outside of an
+    /// `async` context.
+    ///
+    /// `None` is returned if no more events can be received by this listener.
+    ///
+    /// # Examples
+    ///
+    /// Polling from a manually implemented future
+    ///
+    /// ```rust,no_run
+    /// use std::pin::Pin;
+    /// use std::future::Future;
+    /// use std::task::{Context, Poll};
+    /// use tokio::signal::windows::CtrlClose;
+    ///
+    /// struct MyFuture {
+    ///     ctrl_close: CtrlClose,
+    /// }
+    ///
+    /// impl Future for MyFuture {
+    ///     type Output = Option<()>;
+    ///
+    ///     fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+    ///         println!("polling MyFuture");
+    ///         self.ctrl_close.poll_recv(cx)
+    ///     }
+    /// }
+    /// ```
+    pub fn poll_recv(&mut self, cx: &mut Context<'_>) -> Poll<Option<()>> {
+        self.inner.poll_recv(cx)
+    }
+}
 
-        assert_pending!(ctrl_c.poll());
+/// Creates a new listener which receives "ctrl-shutdown" notifications sent to the
+/// process.
+///
+/// # Examples
+///
+/// ```rust,no_run
+/// use tokio::signal::windows::ctrl_shutdown;
+///
+/// #[tokio::main]
+/// async fn main() -> Result<(), Box<dyn std::error::Error>> {
+///     // A listener of CTRL-SHUTDOWN events.
+///     let mut signal = ctrl_shutdown()?;
+///
+///     signal.recv().await;
+///     println!("got CTRL-SHUTDOWN. Cleaning up before exiting");
+///
+///     Ok(())
+/// }
+/// ```
+pub fn ctrl_shutdown() -> io::Result<CtrlShutdown> {
+    Ok(CtrlShutdown {
+        inner: self::imp::ctrl_shutdown()?,
+    })
+}
 
-        // Windows doesn't have a good programmatic way of sending events
-        // like sending signals on Unix, so we'll stub out the actual OS
-        // integration and test that our handling works.
-        unsafe {
-            super::handler(CTRL_C_EVENT);
-        }
+/// Represents a listener which receives "ctrl-shutdown" notitifications sent to the process
+/// via 'SetConsoleCtrlHandler'.
+///
+/// A notification to this process notifies *all* listeners listening for
+/// this event. Moreover, the notifications **are coalesced** if they aren't processed
+/// quickly enough. This means that if two notifications are received back-to-back,
+/// then the listener may only receive one item about the two notifications.
+#[must_use = "listeners do nothing unless polled"]
+#[derive(Debug)]
+pub struct CtrlShutdown {
+    inner: RxFuture,
+}
 
-        assert_ready_ok!(ctrl_c.poll());
+impl CtrlShutdown {
+    /// Receives the next signal notification event.
+    ///
+    /// `None` is returned if no more events can be received by this listener.
+    ///
+    /// # Examples
+    ///
+    /// ```rust,no_run
+    /// use tokio::signal::windows::ctrl_shutdown;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> Result<(), Box<dyn std::error::Error>> {
+    ///     // A listener of CTRL-SHUTDOWN events.
+    ///     let mut signal = ctrl_shutdown()?;
+    ///
+    ///     // Print whenever a CTRL-SHUTDOWN event is received.
+    ///     signal.recv().await;
+    ///     println!("got CTRL-SHUTDOWN. Cleaning up before exiting");
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    pub async fn recv(&mut self) -> Option<()> {
+        self.inner.recv().await
     }
 
-    #[test]
-    fn ctrl_break() {
-        let rt = rt();
+    /// Polls to receive the next signal notification event, outside of an
+    /// `async` context.
+    ///
+    /// `None` is returned if no more events can be received by this listener.
+    ///
+    /// # Examples
+    ///
+    /// Polling from a manually implemented future
+    ///
+    /// ```rust,no_run
+    /// use std::pin::Pin;
+    /// use std::future::Future;
+    /// use std::task::{Context, Poll};
+    /// use tokio::signal::windows::CtrlShutdown;
+    ///
+    /// struct MyFuture {
+    ///     ctrl_shutdown: CtrlShutdown,
+    /// }
+    ///
+    /// impl Future for MyFuture {
+    ///     type Output = Option<()>;
+    ///
+    ///     fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+    ///         println!("polling MyFuture");
+    ///         self.ctrl_shutdown.poll_recv(cx)
+    ///     }
+    /// }
+    /// ```
+    pub fn poll_recv(&mut self, cx: &mut Context<'_>) -> Poll<Option<()>> {
+        self.inner.poll_recv(cx)
+    }
+}
 
-        rt.block_on(async {
-            let mut ctrl_break = assert_ok!(super::ctrl_break());
+/// Creates a new listener which receives "ctrl-logoff" notifications sent to the
+/// process.
+///
+/// # Examples
+///
+/// ```rust,no_run
+/// use tokio::signal::windows::ctrl_logoff;
+///
+/// #[tokio::main]
+/// async fn main() -> Result<(), Box<dyn std::error::Error>> {
+///     // A listener of CTRL-LOGOFF events.
+///     let mut signal = ctrl_logoff()?;
+///
+///     signal.recv().await;
+///     println!("got CTRL-LOGOFF. Cleaning up before exiting");
+///
+///     Ok(())
+/// }
+/// ```
+pub fn ctrl_logoff() -> io::Result<CtrlLogoff> {
+    Ok(CtrlLogoff {
+        inner: self::imp::ctrl_logoff()?,
+    })
+}
 
-            // Windows doesn't have a good programmatic way of sending events
-            // like sending signals on Unix, so we'll stub out the actual OS
-            // integration and test that our handling works.
-            unsafe {
-                super::handler(CTRL_BREAK_EVENT);
-            }
+/// Represents a listener which receives "ctrl-logoff" notitifications sent to the process
+/// via 'SetConsoleCtrlHandler'.
+///
+/// A notification to this process notifies *all* listeners listening for
+/// this event. Moreover, the notifications **are coalesced** if they aren't processed
+/// quickly enough. This means that if two notifications are received back-to-back,
+/// then the listener may only receive one item about the two notifications.
+#[must_use = "listeners do nothing unless polled"]
+#[derive(Debug)]
+pub struct CtrlLogoff {
+    inner: RxFuture,
+}
 
-            ctrl_break.recv().await.unwrap();
-        });
+impl CtrlLogoff {
+    /// Receives the next signal notification event.
+    ///
+    /// `None` is returned if no more events can be received by this listener.
+    ///
+    /// # Examples
+    ///
+    /// ```rust,no_run
+    /// use tokio::signal::windows::ctrl_logoff;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> Result<(), Box<dyn std::error::Error>> {
+    ///     // An listener of CTRL-LOGOFF events.
+    ///     let mut signal = ctrl_logoff()?;
+    ///
+    ///     // Print whenever a CTRL-LOGOFF event is received.
+    ///     signal.recv().await;
+    ///     println!("got CTRL-LOGOFF. Cleaning up before exiting");
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    pub async fn recv(&mut self) -> Option<()> {
+        self.inner.recv().await
     }
 
-    fn rt() -> Runtime {
-        crate::runtime::Builder::new_current_thread()
-            .build()
-            .unwrap()
+    /// Polls to receive the next signal notification event, outside of an
+    /// `async` context.
+    ///
+    /// `None` is returned if no more events can be received by this listener.
+    ///
+    /// # Examples
+    ///
+    /// Polling from a manually implemented future
+    ///
+    /// ```rust,no_run
+    /// use std::pin::Pin;
+    /// use std::future::Future;
+    /// use std::task::{Context, Poll};
+    /// use tokio::signal::windows::CtrlLogoff;
+    ///
+    /// struct MyFuture {
+    ///     ctrl_logoff: CtrlLogoff,
+    /// }
+    ///
+    /// impl Future for MyFuture {
+    ///     type Output = Option<()>;
+    ///
+    ///     fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+    ///         println!("polling MyFuture");
+    ///         self.ctrl_logoff.poll_recv(cx)
+    ///     }
+    /// }
+    /// ```
+    pub fn poll_recv(&mut self, cx: &mut Context<'_>) -> Poll<Option<()>> {
+        self.inner.poll_recv(cx)
     }
 }
diff --git a/vendor/tokio/src/signal/windows/stub.rs b/vendor/tokio/src/signal/windows/stub.rs
new file mode 100644
index 000000000..61df30979
--- /dev/null
+++ b/vendor/tokio/src/signal/windows/stub.rs
@@ -0,0 +1,25 @@
+//! Stub implementations for the platform API so that rustdoc can build linkable
+//! documentation on non-windows platforms.
+
+use crate::signal::RxFuture;
+use std::io;
+
+pub(super) fn ctrl_break() -> io::Result<RxFuture> {
+    panic!()
+}
+
+pub(super) fn ctrl_close() -> io::Result<RxFuture> {
+    panic!()
+}
+
+pub(super) fn ctrl_c() -> io::Result<RxFuture> {
+    panic!()
+}
+
+pub(super) fn ctrl_logoff() -> io::Result<RxFuture> {
+    panic!()
+}
+
+pub(super) fn ctrl_shutdown() -> io::Result<RxFuture> {
+    panic!()
+}
diff --git a/vendor/tokio/src/signal/windows/sys.rs b/vendor/tokio/src/signal/windows/sys.rs
new file mode 100644
index 000000000..26e6bdf81
--- /dev/null
+++ b/vendor/tokio/src/signal/windows/sys.rs
@@ -0,0 +1,229 @@
+use std::io;
+use std::sync::Once;
+
+use crate::signal::registry::{globals, EventId, EventInfo, Init, Storage};
+use crate::signal::RxFuture;
+
+use windows_sys::Win32::Foundation::BOOL;
+use windows_sys::Win32::System::Console as console;
+
+pub(super) fn ctrl_break() -> io::Result<RxFuture> {
+    new(console::CTRL_BREAK_EVENT)
+}
+
+pub(super) fn ctrl_close() -> io::Result<RxFuture> {
+    new(console::CTRL_CLOSE_EVENT)
+}
+
+pub(super) fn ctrl_c() -> io::Result<RxFuture> {
+    new(console::CTRL_C_EVENT)
+}
+
+pub(super) fn ctrl_logoff() -> io::Result<RxFuture> {
+    new(console::CTRL_LOGOFF_EVENT)
+}
+
+pub(super) fn ctrl_shutdown() -> io::Result<RxFuture> {
+    new(console::CTRL_SHUTDOWN_EVENT)
+}
+
+fn new(signum: u32) -> io::Result<RxFuture> {
+    global_init()?;
+    let rx = globals().register_listener(signum as EventId);
+    Ok(RxFuture::new(rx))
+}
+
+#[derive(Debug)]
+pub(crate) struct OsStorage {
+    ctrl_break: EventInfo,
+    ctrl_close: EventInfo,
+    ctrl_c: EventInfo,
+    ctrl_logoff: EventInfo,
+    ctrl_shutdown: EventInfo,
+}
+
+impl Init for OsStorage {
+    fn init() -> Self {
+        Self {
+            ctrl_break: Default::default(),
+            ctrl_close: Default::default(),
+            ctrl_c: Default::default(),
+            ctrl_logoff: Default::default(),
+            ctrl_shutdown: Default::default(),
+        }
+    }
+}
+
+impl Storage for OsStorage {
+    fn event_info(&self, id: EventId) -> Option<&EventInfo> {
+        match u32::try_from(id) {
+            Ok(console::CTRL_BREAK_EVENT) => Some(&self.ctrl_break),
+            Ok(console::CTRL_CLOSE_EVENT) => Some(&self.ctrl_close),
+            Ok(console::CTRL_C_EVENT) => Some(&self.ctrl_c),
+            Ok(console::CTRL_LOGOFF_EVENT) => Some(&self.ctrl_logoff),
+            Ok(console::CTRL_SHUTDOWN_EVENT) => Some(&self.ctrl_shutdown),
+            _ => None,
+        }
+    }
+
+    fn for_each<'a, F>(&'a self, mut f: F)
+    where
+        F: FnMut(&'a EventInfo),
+    {
+        f(&self.ctrl_break);
+        f(&self.ctrl_close);
+        f(&self.ctrl_c);
+        f(&self.ctrl_logoff);
+        f(&self.ctrl_shutdown);
+    }
+}
+
+#[derive(Debug)]
+pub(crate) struct OsExtraData {}
+
+impl Init for OsExtraData {
+    fn init() -> Self {
+        Self {}
+    }
+}
+
+fn global_init() -> io::Result<()> {
+    static INIT: Once = Once::new();
+
+    let mut init = None;
+
+    INIT.call_once(|| unsafe {
+        let rc = console::SetConsoleCtrlHandler(Some(handler), 1);
+        let ret = if rc == 0 {
+            Err(io::Error::last_os_error())
+        } else {
+            Ok(())
+        };
+
+        init = Some(ret);
+    });
+
+    init.unwrap_or_else(|| Ok(()))
+}
+
+unsafe extern "system" fn handler(ty: u32) -> BOOL {
+    let globals = globals();
+    globals.record_event(ty as EventId);
+
+    // According to https://docs.microsoft.com/en-us/windows/console/handlerroutine
+    // the handler routine is always invoked in a new thread, thus we don't
+    // have the same restrictions as in Unix signal handlers, meaning we can
+    // go ahead and perform the broadcast here.
+    if globals.broadcast() {
+        1
+    } else {
+        // No one is listening for this notification any more
+        // let the OS fire the next (possibly the default) handler.
+        0
+    }
+}
+
+#[cfg(all(test, not(loom)))]
+mod tests {
+    use super::*;
+    use crate::runtime::Runtime;
+
+    use tokio_test::{assert_ok, assert_pending, assert_ready_ok, task};
+
+    #[test]
+    fn ctrl_c() {
+        let rt = rt();
+        let _enter = rt.enter();
+
+        let mut ctrl_c = task::spawn(crate::signal::ctrl_c());
+
+        assert_pending!(ctrl_c.poll());
+
+        // Windows doesn't have a good programmatic way of sending events
+        // like sending signals on Unix, so we'll stub out the actual OS
+        // integration and test that our handling works.
+        unsafe {
+            super::handler(console::CTRL_C_EVENT);
+        }
+
+        assert_ready_ok!(ctrl_c.poll());
+    }
+
+    #[test]
+    fn ctrl_break() {
+        let rt = rt();
+
+        rt.block_on(async {
+            let mut ctrl_break = assert_ok!(crate::signal::windows::ctrl_break());
+
+            // Windows doesn't have a good programmatic way of sending events
+            // like sending signals on Unix, so we'll stub out the actual OS
+            // integration and test that our handling works.
+            unsafe {
+                super::handler(console::CTRL_BREAK_EVENT);
+            }
+
+            ctrl_break.recv().await.unwrap();
+        });
+    }
+
+    #[test]
+    fn ctrl_close() {
+        let rt = rt();
+
+        rt.block_on(async {
+            let mut ctrl_close = assert_ok!(crate::signal::windows::ctrl_close());
+
+            // Windows doesn't have a good programmatic way of sending events
+            // like sending signals on Unix, so we'll stub out the actual OS
+            // integration and test that our handling works.
+            unsafe {
+                super::handler(console::CTRL_CLOSE_EVENT);
+            }
+
+            ctrl_close.recv().await.unwrap();
+        });
+    }
+
+    #[test]
+    fn ctrl_shutdown() {
+        let rt = rt();
+
+        rt.block_on(async {
+            let mut ctrl_shutdown = assert_ok!(crate::signal::windows::ctrl_shutdown());
+
+            // Windows doesn't have a good programmatic way of sending events
+            // like sending signals on Unix, so we'll stub out the actual OS
+            // integration and test that our handling works.
+            unsafe {
+                super::handler(console::CTRL_SHUTDOWN_EVENT);
+            }
+
+            ctrl_shutdown.recv().await.unwrap();
+        });
+    }
+
+    #[test]
+    fn ctrl_logoff() {
+        let rt = rt();
+
+        rt.block_on(async {
+            let mut ctrl_logoff = assert_ok!(crate::signal::windows::ctrl_logoff());
+
+            // Windows doesn't have a good programmatic way of sending events
+            // like sending signals on Unix, so we'll stub out the actual OS
+            // integration and test that our handling works.
+            unsafe {
+                super::handler(console::CTRL_LOGOFF_EVENT);
+            }
+
+            ctrl_logoff.recv().await.unwrap();
+        });
+    }
+
+    fn rt() -> Runtime {
+        crate::runtime::Builder::new_current_thread()
+            .build()
+            .unwrap()
+    }
+}
diff --git a/vendor/tokio/src/sync/barrier.rs b/vendor/tokio/src/sync/barrier.rs
index 0e39dac8b..29b6d4e48 100644
--- a/vendor/tokio/src/sync/barrier.rs
+++ b/vendor/tokio/src/sync/barrier.rs
@@ -1,5 +1,7 @@
 use crate::loom::sync::Mutex;
 use crate::sync::watch;
+#[cfg(all(tokio_unstable, feature = "tracing"))]
+use crate::util::trace;
 
 /// A barrier enables multiple tasks to synchronize the beginning of some computation.
 ///
@@ -41,6 +43,8 @@ pub struct Barrier {
     state: Mutex<BarrierState>,
     wait: watch::Receiver<usize>,
     n: usize,
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    resource_span: tracing::Span,
 }
 
 #[derive(Debug)]
@@ -55,6 +59,7 @@ impl Barrier {
     ///
     /// A barrier will block `n`-1 tasks which call [`Barrier::wait`] and then wake up all
     /// tasks at once when the `n`th task calls `wait`.
+    #[track_caller]
     pub fn new(mut n: usize) -> Barrier {
         let (waker, wait) = crate::sync::watch::channel(0);
 
@@ -65,6 +70,32 @@ impl Barrier {
             n = 1;
         }
 
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let resource_span = {
+            let location = std::panic::Location::caller();
+            let resource_span = tracing::trace_span!(
+                "runtime.resource",
+                concrete_type = "Barrier",
+                kind = "Sync",
+                loc.file = location.file(),
+                loc.line = location.line(),
+                loc.col = location.column(),
+            );
+
+            resource_span.in_scope(|| {
+                tracing::trace!(
+                    target: "runtime::resource::state_update",
+                    size = n,
+                );
+
+                tracing::trace!(
+                    target: "runtime::resource::state_update",
+                    arrived = 0,
+                )
+            });
+            resource_span
+        };
+
         Barrier {
             state: Mutex::new(BarrierState {
                 waker,
@@ -73,6 +104,8 @@ impl Barrier {
             }),
             n,
             wait,
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span,
         }
     }
 
@@ -85,10 +118,26 @@ impl Barrier {
     /// [`BarrierWaitResult::is_leader`] when returning from this function, and all other tasks
     /// will receive a result that will return `false` from `is_leader`.
     pub async fn wait(&self) -> BarrierWaitResult {
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        return trace::async_op(
+            || self.wait_internal(),
+            self.resource_span.clone(),
+            "Barrier::wait",
+            "poll",
+            false,
+        )
+        .await;
+
+        #[cfg(any(not(tokio_unstable), not(feature = "tracing")))]
+        return self.wait_internal().await;
+    }
+    async fn wait_internal(&self) -> BarrierWaitResult {
+        crate::trace::async_trace_leaf().await;
+
         // NOTE: we are taking a _synchronous_ lock here.
         // It is okay to do so because the critical section is fast and never yields, so it cannot
         // deadlock even if another future is concurrently holding the lock.
-        // It is _desireable_ to do so as synchronous Mutexes are, at least in theory, faster than
+        // It is _desirable_ to do so as synchronous Mutexes are, at least in theory, faster than
         // the asynchronous counter-parts, so we should use them where possible [citation needed].
         // NOTE: the extra scope here is so that the compiler doesn't think `state` is held across
         // a yield point, and thus marks the returned future as !Send.
@@ -96,7 +145,23 @@ impl Barrier {
             let mut state = self.state.lock();
             let generation = state.generation;
             state.arrived += 1;
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            tracing::trace!(
+                target: "runtime::resource::state_update",
+                arrived = 1,
+                arrived.op = "add",
+            );
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            tracing::trace!(
+                target: "runtime::resource::async_op::state_update",
+                arrived = true,
+            );
             if state.arrived == self.n {
+                #[cfg(all(tokio_unstable, feature = "tracing"))]
+                tracing::trace!(
+                    target: "runtime::resource::async_op::state_update",
+                    is_leader = true,
+                );
                 // we are the leader for this generation
                 // wake everyone, increment the generation, and return
                 state
diff --git a/vendor/tokio/src/sync/batch_semaphore.rs b/vendor/tokio/src/sync/batch_semaphore.rs
index a0bf5ef94..a762f799d 100644
--- a/vendor/tokio/src/sync/batch_semaphore.rs
+++ b/vendor/tokio/src/sync/batch_semaphore.rs
@@ -1,5 +1,5 @@
 #![cfg_attr(not(feature = "sync"), allow(unreachable_pub, dead_code))]
-//! # Implementation Details
+//! # Implementation Details.
 //!
 //! The semaphore is implemented using an intrusive linked list of waiters. An
 //! atomic counter tracks the number of available permits. If the semaphore does
@@ -19,6 +19,9 @@ use crate::loom::cell::UnsafeCell;
 use crate::loom::sync::atomic::AtomicUsize;
 use crate::loom::sync::{Mutex, MutexGuard};
 use crate::util::linked_list::{self, LinkedList};
+#[cfg(all(tokio_unstable, feature = "tracing"))]
+use crate::util::trace;
+use crate::util::WakeList;
 
 use std::future::Future;
 use std::marker::PhantomPinned;
@@ -34,6 +37,8 @@ pub(crate) struct Semaphore {
     waiters: Mutex<Waitlist>,
     /// The current number of available permits in the semaphore.
     permits: AtomicUsize,
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    resource_span: tracing::Span,
 }
 
 struct Waitlist {
@@ -44,7 +49,7 @@ struct Waitlist {
 /// Error returned from the [`Semaphore::try_acquire`] function.
 ///
 /// [`Semaphore::try_acquire`]: crate::sync::Semaphore::try_acquire
-#[derive(Debug, PartialEq)]
+#[derive(Debug, PartialEq, Eq)]
 pub enum TryAcquireError {
     /// The semaphore has been [closed] and cannot issue new permits.
     ///
@@ -100,10 +105,21 @@ struct Waiter {
     /// use `UnsafeCell` internally.
     pointers: linked_list::Pointers<Waiter>,
 
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    ctx: trace::AsyncOpTracingCtx,
+
     /// Should not be `Unpin`.
     _p: PhantomPinned,
 }
 
+generate_addr_of_methods! {
+    impl<> Waiter {
+        unsafe fn addr_of_pointers(self: NonNull<Self>) -> NonNull<linked_list::Pointers<Waiter>> {
+            &self.pointers
+        }
+    }
+}
+
 impl Semaphore {
     /// The maximum number of permits which a semaphore can hold.
     ///
@@ -128,16 +144,38 @@ impl Semaphore {
             "a semaphore may not have more than MAX_PERMITS permits ({})",
             Self::MAX_PERMITS
         );
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let resource_span = {
+            let resource_span = tracing::trace_span!(
+                "runtime.resource",
+                concrete_type = "Semaphore",
+                kind = "Sync",
+                is_internal = true
+            );
+
+            resource_span.in_scope(|| {
+                tracing::trace!(
+                    target: "runtime::resource::state_update",
+                    permits = permits,
+                    permits.op = "override",
+                )
+            });
+            resource_span
+        };
+
         Self {
             permits: AtomicUsize::new(permits << Self::PERMIT_SHIFT),
             waiters: Mutex::new(Waitlist {
                 queue: LinkedList::new(),
                 closed: false,
             }),
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span,
         }
     }
 
-    /// Creates a new semaphore with the initial number of permits
+    /// Creates a new semaphore with the initial number of permits.
     ///
     /// Maximum number of permits on 32-bit platforms is `1<<29`.
     ///
@@ -155,10 +193,12 @@ impl Semaphore {
                 queue: LinkedList::new(),
                 closed: false,
             }),
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: tracing::Span::none(),
         }
     }
 
-    /// Returns the current number of available permits
+    /// Returns the current number of available permits.
     pub(crate) fn available_permits(&self) -> usize {
         self.permits.load(Acquire) >> Self::PERMIT_SHIFT
     }
@@ -196,7 +236,7 @@ impl Semaphore {
         }
     }
 
-    /// Returns true if the semaphore is closed
+    /// Returns true if the semaphore is closed.
     pub(crate) fn is_closed(&self) -> bool {
         self.permits.load(Acquire) & Self::CLOSED == Self::CLOSED
     }
@@ -223,7 +263,10 @@ impl Semaphore {
             let next = curr - num_permits;
 
             match self.permits.compare_exchange(curr, next, AcqRel, Acquire) {
-                Ok(_) => return Ok(()),
+                Ok(_) => {
+                    // TODO: Instrument once issue has been solved
+                    return Ok(());
+                }
                 Err(actual) => curr = actual,
             }
         }
@@ -239,12 +282,12 @@ impl Semaphore {
     /// If `rem` exceeds the number of permits needed by the wait list, the
     /// remainder are assigned back to the semaphore.
     fn add_permits_locked(&self, mut rem: usize, waiters: MutexGuard<'_, Waitlist>) {
-        let mut wakers: [Option<Waker>; 8] = Default::default();
+        let mut wakers = WakeList::new();
         let mut lock = Some(waiters);
         let mut is_empty = false;
         while rem > 0 {
             let mut waiters = lock.take().unwrap_or_else(|| self.waiters.lock());
-            'inner: for slot in &mut wakers[..] {
+            'inner: while wakers.can_push() {
                 // Was the waiter assigned enough permits to wake it?
                 match waiters.queue.last() {
                     Some(waiter) => {
@@ -260,7 +303,11 @@ impl Semaphore {
                     }
                 };
                 let mut waiter = waiters.queue.pop_back().unwrap();
-                *slot = unsafe { waiter.as_mut().waker.with_mut(|waker| (*waker).take()) };
+                if let Some(waker) =
+                    unsafe { waiter.as_mut().waker.with_mut(|waker| (*waker).take()) }
+                {
+                    wakers.push(waker);
+                }
             }
 
             if rem > 0 && is_empty {
@@ -278,15 +325,23 @@ impl Semaphore {
                     rem,
                     Self::MAX_PERMITS
                 );
+
+                // add remaining permits back
+                #[cfg(all(tokio_unstable, feature = "tracing"))]
+                self.resource_span.in_scope(|| {
+                    tracing::trace!(
+                    target: "runtime::resource::state_update",
+                    permits = rem,
+                    permits.op = "add",
+                    )
+                });
+
                 rem = 0;
             }
 
             drop(waiters); // release the lock
 
-            wakers
-                .iter_mut()
-                .filter_map(Option::take)
-                .for_each(Waker::wake);
+            wakers.wake_all();
         }
 
         assert_eq!(rem, 0);
@@ -345,6 +400,20 @@ impl Semaphore {
                     acquired += acq;
                     if remaining == 0 {
                         if !queued {
+                            #[cfg(all(tokio_unstable, feature = "tracing"))]
+                            self.resource_span.in_scope(|| {
+                                tracing::trace!(
+                                    target: "runtime::resource::state_update",
+                                    permits = acquired,
+                                    permits.op = "sub",
+                                );
+                                tracing::trace!(
+                                    target: "runtime::resource::async_op::state_update",
+                                    permits_obtained = acquired,
+                                    permits.op = "add",
+                                )
+                            });
+
                             return Ready(Ok(()));
                         } else if lock.is_none() {
                             break self.waiters.lock();
@@ -360,12 +429,22 @@ impl Semaphore {
             return Ready(Err(AcquireError::closed()));
         }
 
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        self.resource_span.in_scope(|| {
+            tracing::trace!(
+                target: "runtime::resource::state_update",
+                permits = acquired,
+                permits.op = "sub",
+            )
+        });
+
         if node.assign_permits(&mut acquired) {
             self.add_permits_locked(acquired, waiters);
             return Ready(Ok(()));
         }
 
         assert_eq!(acquired, 0);
+        let mut old_waker = None;
 
         // Otherwise, register the waker & enqueue the node.
         node.waker.with_mut(|waker| {
@@ -377,7 +456,7 @@ impl Semaphore {
                 .map(|waker| !waker.will_wake(cx.waker()))
                 .unwrap_or(true)
             {
-                *waker = Some(cx.waker().clone());
+                old_waker = std::mem::replace(waker, Some(cx.waker().clone()));
             }
         });
 
@@ -390,6 +469,8 @@ impl Semaphore {
 
             waiters.queue.push_front(node);
         }
+        drop(waiters);
+        drop(old_waker);
 
         Pending
     }
@@ -404,11 +485,16 @@ impl fmt::Debug for Semaphore {
 }
 
 impl Waiter {
-    fn new(num_permits: u32) -> Self {
+    fn new(
+        num_permits: u32,
+        #[cfg(all(tokio_unstable, feature = "tracing"))] ctx: trace::AsyncOpTracingCtx,
+    ) -> Self {
         Waiter {
             waker: UnsafeCell::new(None),
             state: AtomicUsize::new(num_permits as usize),
             pointers: linked_list::Pointers::new(),
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            ctx,
             _p: PhantomPinned,
         }
     }
@@ -424,6 +510,14 @@ impl Waiter {
             match self.state.compare_exchange(curr, next, AcqRel, Acquire) {
                 Ok(_) => {
                     *n -= assign;
+                    #[cfg(all(tokio_unstable, feature = "tracing"))]
+                    self.ctx.async_op_span.in_scope(|| {
+                        tracing::trace!(
+                            target: "runtime::resource::async_op::state_update",
+                            permits_obtained = assign,
+                            permits.op = "add",
+                        );
+                    });
                     return next == 0;
                 }
                 Err(actual) => curr = actual,
@@ -436,12 +530,26 @@ impl Future for Acquire<'_> {
     type Output = Result<(), AcquireError>;
 
     fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
-        // First, ensure the current task has enough budget to proceed.
-        let coop = ready!(crate::coop::poll_proceed(cx));
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let _resource_span = self.node.ctx.resource_span.clone().entered();
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let _async_op_span = self.node.ctx.async_op_span.clone().entered();
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let _async_op_poll_span = self.node.ctx.async_op_poll_span.clone().entered();
 
         let (node, semaphore, needed, queued) = self.project();
 
-        match semaphore.poll_acquire(cx, needed, node, *queued) {
+        // First, ensure the current task has enough budget to proceed.
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let coop = ready!(trace_poll_op!(
+            "poll_acquire",
+            crate::runtime::coop::poll_proceed(cx),
+        ));
+
+        #[cfg(not(all(tokio_unstable, feature = "tracing")))]
+        let coop = ready!(crate::runtime::coop::poll_proceed(cx));
+
+        let result = match semaphore.poll_acquire(cx, needed, node, *queued) {
             Pending => {
                 *queued = true;
                 Pending
@@ -452,18 +560,59 @@ impl Future for Acquire<'_> {
                 *queued = false;
                 Ready(Ok(()))
             }
-        }
+        };
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        return trace_poll_op!("poll_acquire", result);
+
+        #[cfg(not(all(tokio_unstable, feature = "tracing")))]
+        return result;
     }
 }
 
 impl<'a> Acquire<'a> {
     fn new(semaphore: &'a Semaphore, num_permits: u32) -> Self {
-        Self {
+        #[cfg(any(not(tokio_unstable), not(feature = "tracing")))]
+        return Self {
             node: Waiter::new(num_permits),
             semaphore,
             num_permits,
             queued: false,
-        }
+        };
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        return semaphore.resource_span.in_scope(|| {
+            let async_op_span =
+                tracing::trace_span!("runtime.resource.async_op", source = "Acquire::new");
+            let async_op_poll_span = async_op_span.in_scope(|| {
+                tracing::trace!(
+                    target: "runtime::resource::async_op::state_update",
+                    permits_requested = num_permits,
+                    permits.op = "override",
+                );
+
+                tracing::trace!(
+                    target: "runtime::resource::async_op::state_update",
+                    permits_obtained = 0usize,
+                    permits.op = "override",
+                );
+
+                tracing::trace_span!("runtime.resource.async_op.poll")
+            });
+
+            let ctx = trace::AsyncOpTracingCtx {
+                async_op_span,
+                async_op_poll_span,
+                resource_span: semaphore.resource_span.clone(),
+            };
+
+            Self {
+                node: Waiter::new(num_permits, ctx),
+                semaphore,
+                num_permits,
+                queued: false,
+            }
+        });
     }
 
     fn project(self: Pin<&mut Self>) -> (Pin<&mut Waiter>, &Semaphore, u32, &mut bool) {
@@ -478,7 +627,7 @@ impl<'a> Acquire<'a> {
             let this = self.get_unchecked_mut();
             (
                 Pin::new_unchecked(&mut this.node),
-                &this.semaphore,
+                this.semaphore,
                 this.num_permits,
                 &mut this.queued,
             )
@@ -566,12 +715,6 @@ impl std::error::Error for TryAcquireError {}
 ///
 /// `Waiter` is forced to be !Unpin.
 unsafe impl linked_list::Link for Waiter {
-    // XXX: ideally, we would be able to use `Pin` here, to enforce the
-    // invariant that list entries may not move while in the list. However, we
-    // can't do this currently, as using `Pin<&'a mut Waiter>` as the `Handle`
-    // type would require `Semaphore` to be generic over a lifetime. We can't
-    // use `Pin<*mut Waiter>`, as raw pointers are `Unpin` regardless of whether
-    // or not they dereference to an `!Unpin` target.
     type Handle = NonNull<Waiter>;
     type Target = Waiter;
 
@@ -583,7 +726,7 @@ unsafe impl linked_list::Link for Waiter {
         ptr
     }
 
-    unsafe fn pointers(mut target: NonNull<Waiter>) -> NonNull<linked_list::Pointers<Waiter>> {
-        NonNull::from(&mut target.as_mut().pointers)
+    unsafe fn pointers(target: NonNull<Waiter>) -> NonNull<linked_list::Pointers<Waiter>> {
+        Waiter::addr_of_pointers(target)
     }
 }
diff --git a/vendor/tokio/src/sync/broadcast.rs b/vendor/tokio/src/sync/broadcast.rs
index a2ca4459e..4b36452ce 100644
--- a/vendor/tokio/src/sync/broadcast.rs
+++ b/vendor/tokio/src/sync/broadcast.rs
@@ -4,7 +4,7 @@
 //! A [`Sender`] is used to broadcast values to **all** connected [`Receiver`]
 //! values. [`Sender`] handles are clone-able, allowing concurrent send and
 //! receive actions. [`Sender`] and [`Receiver`] are both `Send` and `Sync` as
-//! long as `T` is also `Send` or `Sync` respectively.
+//! long as `T` is `Send`.
 //!
 //! When a value is sent, **all** [`Receiver`] handles are notified and will
 //! receive the value. The value is stored once inside the channel and cloned on
@@ -18,6 +18,9 @@
 //! returned [`Receiver`] will receive values sent **after** the call to
 //! `subscribe`.
 //!
+//! This channel is also suitable for the single-producer multi-consumer
+//! use-case, where a single sender broadcasts values to many receivers.
+//!
 //! ## Lagging
 //!
 //! As sent messages must be retained until **all** [`Receiver`] handles receive
@@ -51,6 +54,10 @@
 //! all values retained by the channel, the next call to [`recv`] will return
 //! with [`RecvError::Closed`].
 //!
+//! When a [`Receiver`] handle is dropped, any messages not read by the receiver
+//! will be marked as read. If this receiver was the only one not to have read
+//! that message, the message will be dropped at this point.
+//!
 //! [`Sender`]: crate::sync::broadcast::Sender
 //! [`Sender::subscribe`]: crate::sync::broadcast::Sender::subscribe
 //! [`Receiver`]: crate::sync::broadcast::Receiver
@@ -111,8 +118,9 @@
 
 use crate::loom::cell::UnsafeCell;
 use crate::loom::sync::atomic::AtomicUsize;
-use crate::loom::sync::{Arc, Mutex, RwLock, RwLockReadGuard};
+use crate::loom::sync::{Arc, Mutex, MutexGuard, RwLock, RwLockReadGuard};
 use crate::util::linked_list::{self, LinkedList};
+use crate::util::WakeList;
 
 use std::fmt;
 use std::future::Future;
@@ -230,7 +238,7 @@ pub mod error {
     ///
     /// [`recv`]: crate::sync::broadcast::Receiver::recv
     /// [`Receiver`]: crate::sync::broadcast::Receiver
-    #[derive(Debug, PartialEq)]
+    #[derive(Debug, PartialEq, Eq, Clone)]
     pub enum RecvError {
         /// There are no more active senders implying no further messages will ever
         /// be sent.
@@ -258,7 +266,7 @@ pub mod error {
     ///
     /// [`try_recv`]: crate::sync::broadcast::Receiver::try_recv
     /// [`Receiver`]: crate::sync::broadcast::Receiver
-    #[derive(Debug, PartialEq)]
+    #[derive(Debug, PartialEq, Eq, Clone)]
     pub enum TryRecvError {
         /// The channel is currently empty. There are still active
         /// [`Sender`] handles, so data may yet become available.
@@ -293,37 +301,37 @@ pub mod error {
 
 use self::error::*;
 
-/// Data shared between senders and receivers
+/// Data shared between senders and receivers.
 struct Shared<T> {
-    /// slots in the channel
+    /// slots in the channel.
     buffer: Box<[RwLock<Slot<T>>]>,
 
-    /// Mask a position -> index
+    /// Mask a position -> index.
     mask: usize,
 
     /// Tail of the queue. Includes the rx wait list.
     tail: Mutex<Tail>,
 
-    /// Number of outstanding Sender handles
+    /// Number of outstanding Sender handles.
     num_tx: AtomicUsize,
 }
 
-/// Next position to write a value
+/// Next position to write a value.
 struct Tail {
-    /// Next position to write to
+    /// Next position to write to.
     pos: u64,
 
-    /// Number of active receivers
+    /// Number of active receivers.
     rx_cnt: usize,
 
-    /// True if the channel is closed
+    /// True if the channel is closed.
     closed: bool,
 
-    /// Receivers waiting for a value
+    /// Receivers waiting for a value.
     waiters: LinkedList<Waiter, <Waiter as linked_list::Link>::Target>,
 }
 
-/// Slot in the buffer
+/// Slot in the buffer.
 struct Slot<T> {
     /// Remaining number of receivers that are expected to see this value.
     ///
@@ -333,12 +341,9 @@ struct Slot<T> {
     /// acquired.
     rem: AtomicUsize,
 
-    /// Uniquely identifies the `send` stored in the slot
+    /// Uniquely identifies the `send` stored in the slot.
     pos: u64,
 
-    /// True signals the channel is closed.
-    closed: bool,
-
     /// The value being broadcast.
     ///
     /// The value is set by `send` when the write lock is held. When a reader
@@ -346,9 +351,9 @@ struct Slot<T> {
     val: UnsafeCell<Option<T>>,
 }
 
-/// An entry in the wait queue
+/// An entry in the wait queue.
 struct Waiter {
-    /// True if queued
+    /// True if queued.
     queued: bool,
 
     /// Task waiting on the broadcast channel.
@@ -361,16 +366,24 @@ struct Waiter {
     _p: PhantomPinned,
 }
 
+generate_addr_of_methods! {
+    impl<> Waiter {
+        unsafe fn addr_of_pointers(self: NonNull<Self>) -> NonNull<linked_list::Pointers<Waiter>> {
+            &self.pointers
+        }
+    }
+}
+
 struct RecvGuard<'a, T> {
     slot: RwLockReadGuard<'a, Slot<T>>,
 }
 
-/// Receive a value future
+/// Receive a value future.
 struct Recv<'a, T> {
-    /// Receiver being waited on
+    /// Receiver being waited on.
     receiver: &'a mut Receiver<T>,
 
-    /// Entry in the waiter `LinkedList`
+    /// Entry in the waiter `LinkedList`.
     waiter: UnsafeCell<Waiter>,
 }
 
@@ -425,6 +438,12 @@ const MAX_RECEIVERS: usize = usize::MAX >> 2;
 ///     tx.send(20).unwrap();
 /// }
 /// ```
+///
+/// # Panics
+///
+/// This will panic if `capacity` is equal to `0` or larger
+/// than `usize::MAX / 2`.
+#[track_caller]
 pub fn channel<T: Clone>(mut capacity: usize) -> (Sender<T>, Receiver<T>) {
     assert!(capacity > 0, "capacity is empty");
     assert!(capacity <= usize::MAX >> 1, "requested capacity too large");
@@ -438,7 +457,6 @@ pub fn channel<T: Clone>(mut capacity: usize) -> (Sender<T>, Receiver<T>) {
         buffer.push(RwLock::new(Slot {
             rem: AtomicUsize::new(0),
             pos: (i as u64).wrapping_sub(capacity as u64),
-            closed: false,
             val: UnsafeCell::new(None),
         }));
     }
@@ -523,8 +541,41 @@ impl<T> Sender<T> {
     /// }
     /// ```
     pub fn send(&self, value: T) -> Result<usize, SendError<T>> {
-        self.send2(Some(value))
-            .map_err(|SendError(maybe_v)| SendError(maybe_v.unwrap()))
+        let mut tail = self.shared.tail.lock();
+
+        if tail.rx_cnt == 0 {
+            return Err(SendError(value));
+        }
+
+        // Position to write into
+        let pos = tail.pos;
+        let rem = tail.rx_cnt;
+        let idx = (pos & self.shared.mask as u64) as usize;
+
+        // Update the tail position
+        tail.pos = tail.pos.wrapping_add(1);
+
+        // Get the slot
+        let mut slot = self.shared.buffer[idx].write().unwrap();
+
+        // Track the position
+        slot.pos = pos;
+
+        // Set remaining receivers
+        slot.rem.with_mut(|v| *v = rem);
+
+        // Write the value
+        slot.val = UnsafeCell::new(Some(value));
+
+        // Release the slot lock before notifying the receivers.
+        drop(slot);
+
+        // Notify and release the mutex. This must happen after the slot lock is
+        // released, otherwise the writer lock bit could be cleared while another
+        // thread is in the critical section.
+        self.shared.notify_rx(tail);
+
+        Ok(rem)
     }
 
     /// Creates a new [`Receiver`] handle that will receive values sent **after**
@@ -555,6 +606,97 @@ impl<T> Sender<T> {
         new_receiver(shared)
     }
 
+    /// Returns the number of queued values.
+    ///
+    /// A value is queued until it has either been seen by all receivers that were alive at the time
+    /// it was sent, or has been evicted from the queue by subsequent sends that exceeded the
+    /// queue's capacity.
+    ///
+    /// # Note
+    ///
+    /// In contrast to [`Receiver::len`], this method only reports queued values and not values that
+    /// have been evicted from the queue before being seen by all receivers.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::sync::broadcast;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let (tx, mut rx1) = broadcast::channel(16);
+    ///     let mut rx2 = tx.subscribe();
+    ///
+    ///     tx.send(10).unwrap();
+    ///     tx.send(20).unwrap();
+    ///     tx.send(30).unwrap();
+    ///
+    ///     assert_eq!(tx.len(), 3);
+    ///
+    ///     rx1.recv().await.unwrap();
+    ///
+    ///     // The len is still 3 since rx2 hasn't seen the first value yet.
+    ///     assert_eq!(tx.len(), 3);
+    ///
+    ///     rx2.recv().await.unwrap();
+    ///
+    ///     assert_eq!(tx.len(), 2);
+    /// }
+    /// ```
+    pub fn len(&self) -> usize {
+        let tail = self.shared.tail.lock();
+
+        let base_idx = (tail.pos & self.shared.mask as u64) as usize;
+        let mut low = 0;
+        let mut high = self.shared.buffer.len();
+        while low < high {
+            let mid = low + (high - low) / 2;
+            let idx = base_idx.wrapping_add(mid) & self.shared.mask;
+            if self.shared.buffer[idx].read().unwrap().rem.load(SeqCst) == 0 {
+                low = mid + 1;
+            } else {
+                high = mid;
+            }
+        }
+
+        self.shared.buffer.len() - low
+    }
+
+    /// Returns true if there are no queued values.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::sync::broadcast;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let (tx, mut rx1) = broadcast::channel(16);
+    ///     let mut rx2 = tx.subscribe();
+    ///
+    ///     assert!(tx.is_empty());
+    ///
+    ///     tx.send(10).unwrap();
+    ///
+    ///     assert!(!tx.is_empty());
+    ///
+    ///     rx1.recv().await.unwrap();
+    ///
+    ///     // The queue is still not empty since rx2 hasn't seen the value.
+    ///     assert!(!tx.is_empty());
+    ///
+    ///     rx2.recv().await.unwrap();
+    ///
+    ///     assert!(tx.is_empty());
+    /// }
+    /// ```
+    pub fn is_empty(&self) -> bool {
+        let tail = self.shared.tail.lock();
+
+        let idx = (tail.pos.wrapping_sub(1) & self.shared.mask as u64) as usize;
+        self.shared.buffer[idx].read().unwrap().rem.load(SeqCst) == 0
+    }
+
     /// Returns the number of active receivers
     ///
     /// An active receiver is a [`Receiver`] handle returned from [`channel`] or
@@ -596,52 +738,38 @@ impl<T> Sender<T> {
         tail.rx_cnt
     }
 
-    fn send2(&self, value: Option<T>) -> Result<usize, SendError<Option<T>>> {
-        let mut tail = self.shared.tail.lock();
-
-        if tail.rx_cnt == 0 {
-            return Err(SendError(value));
-        }
-
-        // Position to write into
-        let pos = tail.pos;
-        let rem = tail.rx_cnt;
-        let idx = (pos & self.shared.mask as u64) as usize;
-
-        // Update the tail position
-        tail.pos = tail.pos.wrapping_add(1);
-
-        // Get the slot
-        let mut slot = self.shared.buffer[idx].write().unwrap();
-
-        // Track the position
-        slot.pos = pos;
-
-        // Set remaining receivers
-        slot.rem.with_mut(|v| *v = rem);
-
-        // Set the closed bit if the value is `None`; otherwise write the value
-        if value.is_none() {
-            tail.closed = true;
-            slot.closed = true;
-        } else {
-            slot.val.with_mut(|ptr| unsafe { *ptr = value });
-        }
-
-        // Release the slot lock before notifying the receivers.
-        drop(slot);
-
-        tail.notify_rx();
+    /// Returns `true` if senders belong to the same channel.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::sync::broadcast;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let (tx, _rx) = broadcast::channel::<()>(16);
+    ///     let tx2 = tx.clone();
+    ///
+    ///     assert!(tx.same_channel(&tx2));
+    ///
+    ///     let (tx3, _rx3) = broadcast::channel::<()>(16);
+    ///
+    ///     assert!(!tx3.same_channel(&tx2));
+    /// }
+    /// ```
+    pub fn same_channel(&self, other: &Self) -> bool {
+        Arc::ptr_eq(&self.shared, &other.shared)
+    }
 
-        // Release the mutex. This must happen after the slot lock is released,
-        // otherwise the writer lock bit could be cleared while another thread
-        // is in the critical section.
-        drop(tail);
+    fn close_channel(&self) {
+        let mut tail = self.shared.tail.lock();
+        tail.closed = true;
 
-        Ok(rem)
+        self.shared.notify_rx(tail);
     }
 }
 
+/// Create a new `Receiver` which reads starting from the tail.
 fn new_receiver<T>(shared: Arc<Shared<T>>) -> Receiver<T> {
     let mut tail = shared.tail.lock();
 
@@ -658,18 +786,47 @@ fn new_receiver<T>(shared: Arc<Shared<T>>) -> Receiver<T> {
     Receiver { shared, next }
 }
 
-impl Tail {
-    fn notify_rx(&mut self) {
-        while let Some(mut waiter) = self.waiters.pop_back() {
-            // Safety: `waiters` lock is still held.
-            let waiter = unsafe { waiter.as_mut() };
+impl<T> Shared<T> {
+    fn notify_rx<'a, 'b: 'a>(&'b self, mut tail: MutexGuard<'a, Tail>) {
+        let mut wakers = WakeList::new();
+        'outer: loop {
+            while wakers.can_push() {
+                match tail.waiters.pop_back() {
+                    Some(mut waiter) => {
+                        // Safety: `tail` lock is still held.
+                        let waiter = unsafe { waiter.as_mut() };
+
+                        assert!(waiter.queued);
+                        waiter.queued = false;
+
+                        if let Some(waker) = waiter.waker.take() {
+                            wakers.push(waker);
+                        }
+                    }
+                    None => {
+                        break 'outer;
+                    }
+                }
+            }
+
+            // Release the lock before waking.
+            drop(tail);
 
-            assert!(waiter.queued);
-            waiter.queued = false;
+            // Before we acquire the lock again all sorts of things can happen:
+            // some waiters may remove themselves from the list and new waiters
+            // may be added. This is fine since at worst we will unnecessarily
+            // wake up waiters which will then queue themselves again.
 
-            let waker = waiter.waker.take().unwrap();
-            waker.wake();
+            wakers.wake_all();
+
+            // Acquire the lock again.
+            tail = self.tail.lock();
         }
+
+        // Release the lock before waking.
+        drop(tail);
+
+        wakers.wake_all();
     }
 }
 
@@ -685,12 +842,102 @@ impl<T> Clone for Sender<T> {
 impl<T> Drop for Sender<T> {
     fn drop(&mut self) {
         if 1 == self.shared.num_tx.fetch_sub(1, SeqCst) {
-            let _ = self.send2(None);
+            self.close_channel();
         }
     }
 }
 
 impl<T> Receiver<T> {
+    /// Returns the number of messages that were sent into the channel and that
+    /// this [`Receiver`] has yet to receive.
+    ///
+    /// If the returned value from `len` is larger than the next largest power of 2
+    /// of the capacity of the channel any call to [`recv`] will return an
+    /// `Err(RecvError::Lagged)` and any call to [`try_recv`] will return an
+    /// `Err(TryRecvError::Lagged)`, e.g. if the capacity of the channel is 10,
+    /// [`recv`] will start to return `Err(RecvError::Lagged)` once `len` returns
+    /// values larger than 16.
+    ///
+    /// [`Receiver`]: crate::sync::broadcast::Receiver
+    /// [`recv`]: crate::sync::broadcast::Receiver::recv
+    /// [`try_recv`]: crate::sync::broadcast::Receiver::try_recv
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::sync::broadcast;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let (tx, mut rx1) = broadcast::channel(16);
+    ///
+    ///     tx.send(10).unwrap();
+    ///     tx.send(20).unwrap();
+    ///
+    ///     assert_eq!(rx1.len(), 2);
+    ///     assert_eq!(rx1.recv().await.unwrap(), 10);
+    ///     assert_eq!(rx1.len(), 1);
+    ///     assert_eq!(rx1.recv().await.unwrap(), 20);
+    ///     assert_eq!(rx1.len(), 0);
+    /// }
+    /// ```
+    pub fn len(&self) -> usize {
+        let next_send_pos = self.shared.tail.lock().pos;
+        (next_send_pos - self.next) as usize
+    }
+
+    /// Returns true if there aren't any messages in the channel that the [`Receiver`]
+    /// has yet to receive.
+    ///
+    /// [`Receiver]: create::sync::broadcast::Receiver
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::sync::broadcast;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let (tx, mut rx1) = broadcast::channel(16);
+    ///
+    ///     assert!(rx1.is_empty());
+    ///
+    ///     tx.send(10).unwrap();
+    ///     tx.send(20).unwrap();
+    ///
+    ///     assert!(!rx1.is_empty());
+    ///     assert_eq!(rx1.recv().await.unwrap(), 10);
+    ///     assert_eq!(rx1.recv().await.unwrap(), 20);
+    ///     assert!(rx1.is_empty());
+    /// }
+    /// ```
+    pub fn is_empty(&self) -> bool {
+        self.len() == 0
+    }
+
+    /// Returns `true` if receivers belong to the same channel.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::sync::broadcast;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let (tx, rx) = broadcast::channel::<()>(16);
+    ///     let rx2 = tx.subscribe();
+    ///
+    ///     assert!(rx.same_channel(&rx2));
+    ///
+    ///     let (_tx3, rx3) = broadcast::channel::<()>(16);
+    ///
+    ///     assert!(!rx3.same_channel(&rx2));
+    /// }
+    /// ```
+    pub fn same_channel(&self, other: &Self) -> bool {
+        Arc::ptr_eq(&self.shared, &other.shared)
+    }
+
     /// Locks the next value if there is one.
     fn recv_ref(
         &mut self,
@@ -702,14 +949,6 @@ impl<T> Receiver<T> {
         let mut slot = self.shared.buffer[idx].read().unwrap();
 
         if slot.pos != self.next {
-            let next_pos = slot.pos.wrapping_add(self.shared.buffer.len() as u64);
-
-            // The receiver has read all current values in the channel and there
-            // is no waiter to register
-            if waiter.is_none() && next_pos == self.next {
-                return Err(TryRecvError::Empty);
-            }
-
             // Release the `slot` lock before attempting to acquire the `tail`
             // lock. This is required because `send2` acquires the tail lock
             // first followed by the slot lock. Acquiring the locks in reverse
@@ -719,6 +958,8 @@ impl<T> Receiver<T> {
             // the slot lock.
             drop(slot);
 
+            let mut old_waker = None;
+
             let mut tail = self.shared.tail.lock();
 
             // Acquire slot lock again
@@ -731,6 +972,13 @@ impl<T> Receiver<T> {
                 let next_pos = slot.pos.wrapping_add(self.shared.buffer.len() as u64);
 
                 if next_pos == self.next {
+                    // At this point the channel is empty for *this* receiver. If
+                    // it's been closed, then that's what we return, otherwise we
+                    // set a waker and return empty.
+                    if tail.closed {
+                        return Err(TryRecvError::Closed);
+                    }
+
                     // Store the waker
                     if let Some((waiter, waker)) = waiter {
                         // Safety: called while locked.
@@ -744,7 +992,10 @@ impl<T> Receiver<T> {
                                 match (*ptr).waker {
                                     Some(ref w) if w.will_wake(waker) => {}
                                     _ => {
-                                        (*ptr).waker = Some(waker.clone());
+                                        old_waker = std::mem::replace(
+                                            &mut (*ptr).waker,
+                                            Some(waker.clone()),
+                                        );
                                     }
                                 }
 
@@ -756,6 +1007,11 @@ impl<T> Receiver<T> {
                         }
                     }
 
+                    // Drop the old waker after releasing the locks.
+                    drop(slot);
+                    drop(tail);
+                    drop(old_waker);
+
                     return Err(TryRecvError::Empty);
                 }
 
@@ -764,22 +1020,7 @@ impl<T> Receiver<T> {
                 // catch up by skipping dropped messages and setting the
                 // internal cursor to the **oldest** message stored by the
                 // channel.
-                //
-                // However, finding the oldest position is a bit more
-                // complicated than `tail-position - buffer-size`. When
-                // the channel is closed, the tail position is incremented to
-                // signal a new `None` message, but `None` is not stored in the
-                // channel itself (see issue #2425 for why).
-                //
-                // To account for this, if the channel is closed, the tail
-                // position is decremented by `buffer-size + 1`.
-                let mut adjust = 0;
-                if tail.closed {
-                    adjust = 1
-                }
-                let next = tail
-                    .pos
-                    .wrapping_sub(self.shared.buffer.len() as u64 + adjust);
+                let next = tail.pos.wrapping_sub(self.shared.buffer.len() as u64);
 
                 let missed = next.wrapping_sub(self.next);
 
@@ -800,15 +1041,38 @@ impl<T> Receiver<T> {
 
         self.next = self.next.wrapping_add(1);
 
-        if slot.closed {
-            return Err(TryRecvError::Closed);
-        }
-
         Ok(RecvGuard { slot })
     }
 }
 
 impl<T: Clone> Receiver<T> {
+    /// Re-subscribes to the channel starting from the current tail element.
+    ///
+    /// This [`Receiver`] handle will receive a clone of all values sent
+    /// **after** it has resubscribed. This will not include elements that are
+    /// in the queue of the current receiver. Consider the following example.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::sync::broadcast;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///   let (tx, mut rx) = broadcast::channel(2);
+    ///
+    ///   tx.send(1).unwrap();
+    ///   let mut rx2 = rx.resubscribe();
+    ///   tx.send(2).unwrap();
+    ///
+    ///   assert_eq!(rx2.recv().await.unwrap(), 2);
+    ///   assert_eq!(rx.recv().await.unwrap(), 1);
+    /// }
+    /// ```
+    pub fn resubscribe(&self) -> Self {
+        let shared = self.shared.clone();
+        new_receiver(shared)
+    }
     /// Receives the next value for this receiver.
     ///
     /// Each [`Receiver`] handle will receive a clone of all values sent
@@ -930,6 +1194,33 @@ impl<T: Clone> Receiver<T> {
         let guard = self.recv_ref(None)?;
         guard.clone_value().ok_or(TryRecvError::Closed)
     }
+
+    /// Blocking receive to call outside of asynchronous contexts.
+    ///
+    /// # Panics
+    ///
+    /// This function panics if called within an asynchronous execution
+    /// context.
+    ///
+    /// # Examples
+    /// ```
+    /// use std::thread;
+    /// use tokio::sync::broadcast;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let (tx, mut rx) = broadcast::channel(16);
+    ///
+    ///     let sync_code = thread::spawn(move || {
+    ///         assert_eq!(rx.blocking_recv(), Ok(10));
+    ///     });
+    ///
+    ///     let _ = tx.send(10);
+    ///     sync_code.join().unwrap();
+    /// }
+    pub fn blocking_recv(&mut self) -> Result<T, RecvError> {
+        crate::future::block_on(self.recv())
+    }
 }
 
 impl<T> Drop for Receiver<T> {
@@ -988,6 +1279,8 @@ where
     type Output = Result<T, RecvError>;
 
     fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<T, RecvError>> {
+        ready!(crate::trace::trace_leaf(cx));
+
         let (receiver, waiter) = self.project();
 
         let guard = match receiver.recv_ref(Some((waiter, cx.waker()))) {
@@ -1039,8 +1332,8 @@ unsafe impl linked_list::Link for Waiter {
         ptr
     }
 
-    unsafe fn pointers(mut target: NonNull<Waiter>) -> NonNull<linked_list::Pointers<Waiter>> {
-        NonNull::from(&mut target.as_mut().pointers)
+    unsafe fn pointers(target: NonNull<Waiter>) -> NonNull<linked_list::Pointers<Waiter>> {
+        Waiter::addr_of_pointers(target)
     }
 }
 
diff --git a/vendor/tokio/src/sync/mod.rs b/vendor/tokio/src/sync/mod.rs
index 457e6ab29..70fd9b9e3 100644
--- a/vendor/tokio/src/sync/mod.rs
+++ b/vendor/tokio/src/sync/mod.rs
@@ -94,6 +94,10 @@
 //! producers to a single consumer. This channel is often used to send work to a
 //! task or to receive the result of many computations.
 //!
+//! This is also the channel you should use if you want to send many messages
+//! from a single producer to a single consumer. There is no dedicated spsc
+//! channel.
+//!
 //! **Example:** using an mpsc to incrementally stream the results of a series
 //! of computations.
 //!
@@ -244,6 +248,10 @@
 //! This channel tends to be used less often than `oneshot` and `mpsc` but still
 //! has its use cases.
 //!
+//! This is also the channel you should use if you want to broadcast values from
+//! a single producer to many consumers. There is no dedicated spmc broadcast
+//! channel.
+//!
 //! Basic usage
 //!
 //! ```
@@ -441,7 +449,7 @@ cfg_sync! {
     pub mod mpsc;
 
     mod mutex;
-    pub use mutex::{Mutex, MutexGuard, TryLockError, OwnedMutexGuard, MappedMutexGuard};
+    pub use mutex::{Mutex, MutexGuard, TryLockError, OwnedMutexGuard, MappedMutexGuard, OwnedMappedMutexGuard};
 
     pub(crate) mod notify;
     pub use notify::Notify;
diff --git a/vendor/tokio/src/sync/mpsc/block.rs b/vendor/tokio/src/sync/mpsc/block.rs
index 1c9ab14e9..39c3e1be2 100644
--- a/vendor/tokio/src/sync/mpsc/block.rs
+++ b/vendor/tokio/src/sync/mpsc/block.rs
@@ -1,7 +1,7 @@
 use crate::loom::cell::UnsafeCell;
 use crate::loom::sync::atomic::{AtomicPtr, AtomicUsize};
-use crate::loom::thread;
 
+use std::alloc::Layout;
 use std::mem::MaybeUninit;
 use std::ops;
 use std::ptr::{self, NonNull};
@@ -11,6 +11,17 @@ use std::sync::atomic::Ordering::{self, AcqRel, Acquire, Release};
 ///
 /// Each block in the list can hold up to `BLOCK_CAP` messages.
 pub(crate) struct Block<T> {
+    /// The header fields.
+    header: BlockHeader<T>,
+
+    /// Array containing values pushed into the block. Values are stored in a
+    /// continuous array in order to improve cache line behavior when reading.
+    /// The values must be manually dropped.
+    values: Values<T>,
+}
+
+/// Extra fields for a `Block<T>`.
+struct BlockHeader<T> {
     /// The start index of this block.
     ///
     /// Slots in this block have indices in `start_index .. start_index + BLOCK_CAP`.
@@ -25,11 +36,6 @@ pub(crate) struct Block<T> {
     /// The observed `tail_position` value *after* the block has been passed by
     /// `block_tail`.
     observed_tail_position: UnsafeCell<usize>,
-
-    /// Array containing values pushed into the block. Values are stored in a
-    /// continuous array in order to improve cache line behavior when reading.
-    /// The values must be manually dropped.
-    values: Values<T>,
 }
 
 pub(crate) enum Read<T> {
@@ -37,11 +43,12 @@ pub(crate) enum Read<T> {
     Closed,
 }
 
+#[repr(transparent)]
 struct Values<T>([UnsafeCell<MaybeUninit<T>>; BLOCK_CAP]);
 
 use super::BLOCK_CAP;
 
-/// Masks an index to get the block identifier
+/// Masks an index to get the block identifier.
 const BLOCK_MASK: usize = !(BLOCK_CAP - 1);
 
 /// Masks an index to get the value offset in a block.
@@ -72,28 +79,56 @@ pub(crate) fn offset(slot_index: usize) -> usize {
     SLOT_MASK & slot_index
 }
 
+generate_addr_of_methods! {
+    impl<T> Block<T> {
+        unsafe fn addr_of_header(self: NonNull<Self>) -> NonNull<BlockHeader<T>> {
+            &self.header
+        }
+
+        unsafe fn addr_of_values(self: NonNull<Self>) -> NonNull<Values<T>> {
+            &self.values
+        }
+    }
+}
+
 impl<T> Block<T> {
-    pub(crate) fn new(start_index: usize) -> Block<T> {
-        Block {
-            // The absolute index in the channel of the first slot in the block.
-            start_index,
+    pub(crate) fn new(start_index: usize) -> Box<Block<T>> {
+        unsafe {
+            // Allocate the block on the heap.
+            // SAFETY: The size of the Block<T> is non-zero, since it is at least the size of the header.
+            let block = std::alloc::alloc(Layout::new::<Block<T>>()) as *mut Block<T>;
+            let block = match NonNull::new(block) {
+                Some(block) => block,
+                None => std::alloc::handle_alloc_error(Layout::new::<Block<T>>()),
+            };
+
+            // Write the header to the block.
+            Block::addr_of_header(block).as_ptr().write(BlockHeader {
+                // The absolute index in the channel of the first slot in the block.
+                start_index,
 
-            // Pointer to the next block in the linked list.
-            next: AtomicPtr::new(ptr::null_mut()),
+                // Pointer to the next block in the linked list.
+                next: AtomicPtr::new(ptr::null_mut()),
 
-            ready_slots: AtomicUsize::new(0),
+                ready_slots: AtomicUsize::new(0),
 
-            observed_tail_position: UnsafeCell::new(0),
+                observed_tail_position: UnsafeCell::new(0),
+            });
 
-            // Value storage
-            values: unsafe { Values::uninitialized() },
+            // Initialize the values array.
+            Values::initialize(Block::addr_of_values(block));
+
+            // Convert the pointer to a `Box`.
+            // Safety: The raw pointer was allocated using the global allocator, and with
+            // the layout for a `Block<T>`, so it's valid to convert it to box.
+            Box::from_raw(block.as_ptr())
         }
     }
 
-    /// Returns `true` if the block matches the given index
+    /// Returns `true` if the block matches the given index.
     pub(crate) fn is_at_index(&self, index: usize) -> bool {
         debug_assert!(offset(index) == 0);
-        self.start_index == index
+        self.header.start_index == index
     }
 
     /// Returns the number of blocks between `self` and the block at the
@@ -102,7 +137,7 @@ impl<T> Block<T> {
     /// `start_index` must represent a block *after* `self`.
     pub(crate) fn distance(&self, other_index: usize) -> usize {
         debug_assert!(offset(other_index) == 0);
-        other_index.wrapping_sub(self.start_index) / BLOCK_CAP
+        other_index.wrapping_sub(self.header.start_index) / BLOCK_CAP
     }
 
     /// Reads the value at the given offset.
@@ -117,7 +152,7 @@ impl<T> Block<T> {
     pub(crate) unsafe fn read(&self, slot_index: usize) -> Option<Read<T>> {
         let offset = offset(slot_index);
 
-        let ready_bits = self.ready_slots.load(Acquire);
+        let ready_bits = self.header.ready_slots.load(Acquire);
 
         if !is_ready(ready_bits, offset) {
             if is_tx_closed(ready_bits) {
@@ -157,7 +192,7 @@ impl<T> Block<T> {
 
     /// Signal to the receiver that the sender half of the list is closed.
     pub(crate) unsafe fn tx_close(&self) {
-        self.ready_slots.fetch_or(TX_CLOSED, Release);
+        self.header.ready_slots.fetch_or(TX_CLOSED, Release);
     }
 
     /// Resets the block to a blank state. This enables reusing blocks in the
@@ -170,9 +205,9 @@ impl<T> Block<T> {
     /// * All slots are empty.
     /// * The caller holds a unique pointer to the block.
     pub(crate) unsafe fn reclaim(&mut self) {
-        self.start_index = 0;
-        self.next = AtomicPtr::new(ptr::null_mut());
-        self.ready_slots = AtomicUsize::new(0);
+        self.header.start_index = 0;
+        self.header.next = AtomicPtr::new(ptr::null_mut());
+        self.header.ready_slots = AtomicUsize::new(0);
     }
 
     /// Releases the block to the rx half for freeing.
@@ -188,19 +223,20 @@ impl<T> Block<T> {
     pub(crate) unsafe fn tx_release(&self, tail_position: usize) {
         // Track the observed tail_position. Any sender targeting a greater
         // tail_position is guaranteed to not access this block.
-        self.observed_tail_position
+        self.header
+            .observed_tail_position
             .with_mut(|ptr| *ptr = tail_position);
 
         // Set the released bit, signalling to the receiver that it is safe to
         // free the block's memory as soon as all slots **prior** to
         // `observed_tail_position` have been filled.
-        self.ready_slots.fetch_or(RELEASED, Release);
+        self.header.ready_slots.fetch_or(RELEASED, Release);
     }
 
     /// Mark a slot as ready
     fn set_ready(&self, slot: usize) {
         let mask = 1 << slot;
-        self.ready_slots.fetch_or(mask, Release);
+        self.header.ready_slots.fetch_or(mask, Release);
     }
 
     /// Returns `true` when all slots have their `ready` bits set.
@@ -215,25 +251,31 @@ impl<T> Block<T> {
     /// single atomic cell. However, this could have negative impact on cache
     /// behavior as there would be many more mutations to a single slot.
     pub(crate) fn is_final(&self) -> bool {
-        self.ready_slots.load(Acquire) & READY_MASK == READY_MASK
+        self.header.ready_slots.load(Acquire) & READY_MASK == READY_MASK
     }
 
     /// Returns the `observed_tail_position` value, if set
     pub(crate) fn observed_tail_position(&self) -> Option<usize> {
-        if 0 == RELEASED & self.ready_slots.load(Acquire) {
+        if 0 == RELEASED & self.header.ready_slots.load(Acquire) {
             None
         } else {
-            Some(self.observed_tail_position.with(|ptr| unsafe { *ptr }))
+            Some(
+                self.header
+                    .observed_tail_position
+                    .with(|ptr| unsafe { *ptr }),
+            )
         }
     }
 
     /// Loads the next block
     pub(crate) fn load_next(&self, ordering: Ordering) -> Option<NonNull<Block<T>>> {
-        let ret = NonNull::new(self.next.load(ordering));
+        let ret = NonNull::new(self.header.next.load(ordering));
 
         debug_assert!(unsafe {
-            ret.map(|block| block.as_ref().start_index == self.start_index.wrapping_add(BLOCK_CAP))
-                .unwrap_or(true)
+            ret.map(|block| {
+                block.as_ref().header.start_index == self.header.start_index.wrapping_add(BLOCK_CAP)
+            })
+            .unwrap_or(true)
         });
 
         ret
@@ -261,9 +303,10 @@ impl<T> Block<T> {
         success: Ordering,
         failure: Ordering,
     ) -> Result<(), NonNull<Block<T>>> {
-        block.as_mut().start_index = self.start_index.wrapping_add(BLOCK_CAP);
+        block.as_mut().header.start_index = self.header.start_index.wrapping_add(BLOCK_CAP);
 
         let next_ptr = self
+            .header
             .next
             .compare_exchange(ptr::null_mut(), block.as_ptr(), success, failure)
             .unwrap_or_else(|x| x);
@@ -292,7 +335,7 @@ impl<T> Block<T> {
         // Create the new block. It is assumed that the block will become the
         // next one after `&self`. If this turns out to not be the case,
         // `start_index` is updated accordingly.
-        let new_block = Box::new(Block::new(self.start_index + BLOCK_CAP));
+        let new_block = Block::new(self.header.start_index + BLOCK_CAP);
 
         let mut new_block = unsafe { NonNull::new_unchecked(Box::into_raw(new_block)) };
 
@@ -309,7 +352,8 @@ impl<T> Block<T> {
         // `Release` ensures that the newly allocated block is available to
         // other threads acquiring the next pointer.
         let next = NonNull::new(
-            self.next
+            self.header
+                .next
                 .compare_exchange(ptr::null_mut(), new_block.as_ptr(), AcqRel, Acquire)
                 .unwrap_or_else(|x| x),
         );
@@ -344,8 +388,7 @@ impl<T> Block<T> {
                 Err(curr) => curr,
             };
 
-            // When running outside of loom, this calls `spin_loop_hint`.
-            thread::yield_now();
+            crate::loom::thread::yield_now();
         }
     }
 }
@@ -362,19 +405,20 @@ fn is_tx_closed(bits: usize) -> bool {
 }
 
 impl<T> Values<T> {
-    unsafe fn uninitialized() -> Values<T> {
-        let mut vals = MaybeUninit::uninit();
-
+    /// Initialize a `Values` struct from a pointer.
+    ///
+    /// # Safety
+    ///
+    /// The raw pointer must be valid for writing a `Values<T>`.
+    unsafe fn initialize(_value: NonNull<Values<T>>) {
         // When fuzzing, `UnsafeCell` needs to be initialized.
         if_loom! {
-            let p = vals.as_mut_ptr() as *mut UnsafeCell<MaybeUninit<T>>;
+            let p = _value.as_ptr() as *mut UnsafeCell<MaybeUninit<T>>;
             for i in 0..BLOCK_CAP {
                 p.add(i)
                     .write(UnsafeCell::new(MaybeUninit::uninit()));
             }
         }
-
-        Values(vals.assume_init())
     }
 }
 
@@ -385,3 +429,20 @@ impl<T> ops::Index<usize> for Values<T> {
         self.0.index(index)
     }
 }
+
+#[cfg(all(test, not(loom)))]
+#[test]
+fn assert_no_stack_overflow() {
+    // https://github.com/tokio-rs/tokio/issues/5293
+
+    struct Foo {
+        _a: [u8; 2_000_000],
+    }
+
+    assert_eq!(
+        Layout::new::<MaybeUninit<Block<Foo>>>(),
+        Layout::new::<Block<Foo>>()
+    );
+
+    let _block = Block::<Foo>::new(0);
+}
diff --git a/vendor/tokio/src/sync/mpsc/bounded.rs b/vendor/tokio/src/sync/mpsc/bounded.rs
index d7af17251..e870ae5f4 100644
--- a/vendor/tokio/src/sync/mpsc/bounded.rs
+++ b/vendor/tokio/src/sync/mpsc/bounded.rs
@@ -1,6 +1,7 @@
+use crate::loom::sync::Arc;
 use crate::sync::batch_semaphore::{self as semaphore, TryAcquireError};
 use crate::sync::mpsc::chan;
-use crate::sync::mpsc::error::{SendError, TrySendError};
+use crate::sync::mpsc::error::{SendError, TryRecvError, TrySendError};
 
 cfg_time! {
     use crate::sync::mpsc::error::SendTimeoutError;
@@ -10,19 +11,53 @@ cfg_time! {
 use std::fmt;
 use std::task::{Context, Poll};
 
-/// Send values to the associated `Receiver`.
+/// Sends values to the associated `Receiver`.
 ///
 /// Instances are created by the [`channel`](channel) function.
 ///
-/// To use the `Sender` in a poll function, you can use the [`PollSender`]
-/// utility.
+/// To convert the `Sender` into a `Sink` or use it in a poll function, you can
+/// use the [`PollSender`] utility.
 ///
-/// [`PollSender`]: https://docs.rs/tokio-util/0.6/tokio_util/sync/struct.PollSender.html
+/// [`PollSender`]: https://docs.rs/tokio-util/latest/tokio_util/sync/struct.PollSender.html
 pub struct Sender<T> {
     chan: chan::Tx<T, Semaphore>,
 }
 
-/// Permit to send one value into the channel.
+/// A sender that does not prevent the channel from being closed.
+///
+/// If all [`Sender`] instances of a channel were dropped and only `WeakSender`
+/// instances remain, the channel is closed.
+///
+/// In order to send messages, the `WeakSender` needs to be upgraded using
+/// [`WeakSender::upgrade`], which returns `Option<Sender>`. It returns `None`
+/// if all `Sender`s have been dropped, and otherwise it returns a `Sender`.
+///
+/// [`Sender`]: Sender
+/// [`WeakSender::upgrade`]: WeakSender::upgrade
+///
+/// #Examples
+///
+/// ```
+/// use tokio::sync::mpsc::channel;
+///
+/// #[tokio::main]
+/// async fn main() {
+///     let (tx, _rx) = channel::<i32>(15);
+///     let tx_weak = tx.downgrade();
+///   
+///     // Upgrading will succeed because `tx` still exists.
+///     assert!(tx_weak.upgrade().is_some());
+///   
+///     // If we drop `tx`, then it will fail.
+///     drop(tx);
+///     assert!(tx_weak.clone().upgrade().is_none());
+/// }
+/// ```
+pub struct WeakSender<T> {
+    chan: Arc<chan::Chan<T, Semaphore>>,
+}
+
+/// Permits to send one value into the channel.
 ///
 /// `Permit` values are returned by [`Sender::reserve()`] and [`Sender::try_reserve()`]
 /// and are used to guarantee channel capacity before generating a message to send.
@@ -49,7 +84,7 @@ pub struct OwnedPermit<T> {
     chan: Option<chan::Tx<T, Semaphore>>,
 }
 
-/// Receive values from the associated `Sender`.
+/// Receives values from the associated `Sender`.
 ///
 /// Instances are created by the [`channel`](channel) function.
 ///
@@ -57,7 +92,7 @@ pub struct OwnedPermit<T> {
 ///
 /// [`ReceiverStream`]: https://docs.rs/tokio-stream/0.1/tokio_stream/wrappers/struct.ReceiverStream.html
 pub struct Receiver<T> {
-    /// The channel receiver
+    /// The channel receiver.
     chan: chan::Rx<T, Semaphore>,
 }
 
@@ -105,9 +140,13 @@ pub struct Receiver<T> {
 ///     }
 /// }
 /// ```
+#[track_caller]
 pub fn channel<T>(buffer: usize) -> (Sender<T>, Receiver<T>) {
     assert!(buffer > 0, "mpsc bounded channel requires buffer > 0");
-    let semaphore = (semaphore::Semaphore::new(buffer), buffer);
+    let semaphore = Semaphore {
+        semaphore: semaphore::Semaphore::new(buffer),
+        bound: buffer,
+    };
     let (tx, rx) = chan::channel(semaphore);
 
     let tx = Sender::new(tx);
@@ -118,7 +157,11 @@ pub fn channel<T>(buffer: usize) -> (Sender<T>, Receiver<T>) {
 
 /// Channel semaphore is a tuple of the semaphore implementation and a `usize`
 /// representing the channel bound.
-type Semaphore = (semaphore::Semaphore, usize);
+#[derive(Debug)]
+pub(crate) struct Semaphore {
+    pub(crate) semaphore: semaphore::Semaphore,
+    pub(crate) bound: usize,
+}
 
 impl<T> Receiver<T> {
     pub(crate) fn new(chan: chan::Rx<T, Semaphore>) -> Receiver<T> {
@@ -187,6 +230,50 @@ impl<T> Receiver<T> {
         poll_fn(|cx| self.chan.recv(cx)).await
     }
 
+    /// Tries to receive the next value for this receiver.
+    ///
+    /// This method returns the [`Empty`] error if the channel is currently
+    /// empty, but there are still outstanding [senders] or [permits].
+    ///
+    /// This method returns the [`Disconnected`] error if the channel is
+    /// currently empty, and there are no outstanding [senders] or [permits].
+    ///
+    /// Unlike the [`poll_recv`] method, this method will never return an
+    /// [`Empty`] error spuriously.
+    ///
+    /// [`Empty`]: crate::sync::mpsc::error::TryRecvError::Empty
+    /// [`Disconnected`]: crate::sync::mpsc::error::TryRecvError::Disconnected
+    /// [`poll_recv`]: Self::poll_recv
+    /// [senders]: crate::sync::mpsc::Sender
+    /// [permits]: crate::sync::mpsc::Permit
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::sync::mpsc;
+    /// use tokio::sync::mpsc::error::TryRecvError;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let (tx, mut rx) = mpsc::channel(100);
+    ///
+    ///     tx.send("hello").await.unwrap();
+    ///
+    ///     assert_eq!(Ok("hello"), rx.try_recv());
+    ///     assert_eq!(Err(TryRecvError::Empty), rx.try_recv());
+    ///
+    ///     tx.send("hello").await.unwrap();
+    ///     // Drop the last sender, closing the channel.
+    ///     drop(tx);
+    ///
+    ///     assert_eq!(Ok("hello"), rx.try_recv());
+    ///     assert_eq!(Err(TryRecvError::Disconnected), rx.try_recv());
+    /// }
+    /// ```
+    pub fn try_recv(&mut self) -> Result<T, TryRecvError> {
+        self.chan.try_recv()
+    }
+
     /// Blocking receive to call outside of asynchronous contexts.
     ///
     /// This method returns `None` if the channel has been closed and there are
@@ -237,7 +324,9 @@ impl<T> Receiver<T> {
     ///     sync_code.join().unwrap()
     /// }
     /// ```
+    #[track_caller]
     #[cfg(feature = "sync")]
+    #[cfg_attr(docsrs, doc(alias = "recv_blocking"))]
     pub fn blocking_recv(&mut self) -> Option<T> {
         crate::future::block_on(self.recv())
     }
@@ -291,7 +380,7 @@ impl<T> Receiver<T> {
     /// This method returns:
     ///
     ///  * `Poll::Pending` if no messages are available but the channel is not
-    ///    closed.
+    ///    closed, or if a spurious failure happens.
     ///  * `Poll::Ready(Some(message))` if a message is available.
     ///  * `Poll::Ready(None)` if the channel has been closed and all messages
     ///    sent before it was closed have been received.
@@ -301,6 +390,12 @@ impl<T> Receiver<T> {
     /// receiver, or when the channel is closed.  Note that on multiple calls to
     /// `poll_recv`, only the `Waker` from the `Context` passed to the most
     /// recent call is scheduled to receive a wakeup.
+    ///
+    /// If this method returns `Poll::Pending` due to a spurious failure, then
+    /// the `Waker` will be notified when the situation causing the spurious
+    /// failure has been resolved. Note that receiving such a wakeup does not
+    /// guarantee that the next call will succeed — it could fail with another
+    /// spurious failure.
     pub fn poll_recv(&mut self, cx: &mut Context<'_>) -> Poll<Option<T>> {
         self.chan.recv(cx)
     }
@@ -485,7 +580,7 @@ impl<T> Sender<T> {
     /// }
     /// ```
     pub fn try_send(&self, message: T) -> Result<(), TrySendError<T>> {
-        match self.chan.semaphore().0.try_acquire(1) {
+        match self.chan.semaphore().semaphore.try_acquire(1) {
             Ok(_) => {}
             Err(TryAcquireError::Closed) => return Err(TrySendError::Closed(message)),
             Err(TryAcquireError::NoPermits) => return Err(TrySendError::Full(message)),
@@ -513,6 +608,11 @@ impl<T> Sender<T> {
     /// [`close`]: Receiver::close
     /// [`Receiver`]: Receiver
     ///
+    /// # Panics
+    ///
+    /// This function panics if it is called outside the context of a Tokio
+    /// runtime [with time enabled](crate::runtime::Builder::enable_time).
+    ///
     /// # Examples
     ///
     /// In the following example, each call to `send_timeout` will block until the
@@ -595,7 +695,9 @@ impl<T> Sender<T> {
     ///     sync_code.join().unwrap()
     /// }
     /// ```
+    #[track_caller]
     #[cfg(feature = "sync")]
+    #[cfg_attr(docsrs, doc(alias = "send_blocking"))]
     pub fn blocking_send(&self, value: T) -> Result<(), SendError<T>> {
         crate::future::block_on(self.send(value))
     }
@@ -622,7 +724,7 @@ impl<T> Sender<T> {
         self.chan.is_closed()
     }
 
-    /// Wait for channel capacity. Once capacity to send one message is
+    /// Waits for channel capacity. Once capacity to send one message is
     /// available, it is reserved for the caller.
     ///
     /// If the channel is full, the function waits for the number of unreceived
@@ -671,7 +773,7 @@ impl<T> Sender<T> {
         Ok(Permit { chan: &self.chan })
     }
 
-    /// Wait for channel capacity, moving the `Sender` and returning an owned
+    /// Waits for channel capacity, moving the `Sender` and returning an owned
     /// permit. Once capacity to send one message is available, it is reserved
     /// for the caller.
     ///
@@ -759,13 +861,15 @@ impl<T> Sender<T> {
     }
 
     async fn reserve_inner(&self) -> Result<(), SendError<()>> {
-        match self.chan.semaphore().0.acquire(1).await {
+        crate::trace::async_trace_leaf().await;
+
+        match self.chan.semaphore().semaphore.acquire(1).await {
             Ok(_) => Ok(()),
             Err(_) => Err(SendError(())),
         }
     }
 
-    /// Try to acquire a slot in the channel without waiting for the slot to become
+    /// Tries to acquire a slot in the channel without waiting for the slot to become
     /// available.
     ///
     /// If the channel is full this function will return [`TrySendError`], otherwise
@@ -809,15 +913,16 @@ impl<T> Sender<T> {
     /// }
     /// ```
     pub fn try_reserve(&self) -> Result<Permit<'_, T>, TrySendError<()>> {
-        match self.chan.semaphore().0.try_acquire(1) {
+        match self.chan.semaphore().semaphore.try_acquire(1) {
             Ok(_) => {}
-            Err(_) => return Err(TrySendError::Full(())),
+            Err(TryAcquireError::Closed) => return Err(TrySendError::Closed(())),
+            Err(TryAcquireError::NoPermits) => return Err(TrySendError::Full(())),
         }
 
         Ok(Permit { chan: &self.chan })
     }
 
-    /// Try to acquire a slot in the channel without waiting for the slot to become
+    /// Tries to acquire a slot in the channel without waiting for the slot to become
     /// available, returning an owned permit.
     ///
     /// This moves the sender _by value_, and returns an owned permit that can
@@ -873,9 +978,10 @@ impl<T> Sender<T> {
     /// }
     /// ```
     pub fn try_reserve_owned(self) -> Result<OwnedPermit<T>, TrySendError<Self>> {
-        match self.chan.semaphore().0.try_acquire(1) {
+        match self.chan.semaphore().semaphore.try_acquire(1) {
             Ok(_) => {}
-            Err(_) => return Err(TrySendError::Full(self)),
+            Err(TryAcquireError::Closed) => return Err(TrySendError::Closed(self)),
+            Err(TryAcquireError::NoPermits) => return Err(TrySendError::Full(self)),
         }
 
         Ok(OwnedPermit {
@@ -903,6 +1009,8 @@ impl<T> Sender<T> {
     ///
     /// The capacity goes down when sending a value by calling [`send`] or by reserving capacity
     /// with [`reserve`]. The capacity goes up when values are received by the [`Receiver`].
+    /// This is distinct from [`max_capacity`], which always returns buffer capacity initially
+    /// specified when calling [`channel`]
     ///
     /// # Examples
     ///
@@ -928,8 +1036,56 @@ impl<T> Sender<T> {
     ///
     /// [`send`]: Sender::send
     /// [`reserve`]: Sender::reserve
+    /// [`channel`]: channel
+    /// [`max_capacity`]: Sender::max_capacity
     pub fn capacity(&self) -> usize {
-        self.chan.semaphore().0.available_permits()
+        self.chan.semaphore().semaphore.available_permits()
+    }
+
+    /// Converts the `Sender` to a [`WeakSender`] that does not count
+    /// towards RAII semantics, i.e. if all `Sender` instances of the
+    /// channel were dropped and only `WeakSender` instances remain,
+    /// the channel is closed.
+    pub fn downgrade(&self) -> WeakSender<T> {
+        WeakSender {
+            chan: self.chan.downgrade(),
+        }
+    }
+
+    /// Returns the maximum buffer capacity of the channel.
+    ///
+    /// The maximum capacity is the buffer capacity initially specified when calling
+    /// [`channel`]. This is distinct from [`capacity`], which returns the *current*
+    /// available buffer capacity: as messages are sent and received, the
+    /// value returned by [`capacity`] will go up or down, whereas the value
+    /// returned by `max_capacity` will remain constant.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::sync::mpsc;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let (tx, _rx) = mpsc::channel::<()>(5);
+    ///      
+    ///     // both max capacity and capacity are the same at first
+    ///     assert_eq!(tx.max_capacity(), 5);
+    ///     assert_eq!(tx.capacity(), 5);
+    ///
+    ///     // Making a reservation doesn't change the max capacity.
+    ///     let permit = tx.reserve().await.unwrap();
+    ///     assert_eq!(tx.max_capacity(), 5);
+    ///     // but drops the capacity by one
+    ///     assert_eq!(tx.capacity(), 4);
+    /// }
+    /// ```
+    ///
+    /// [`channel`]: channel
+    /// [`max_capacity`]: Sender::max_capacity
+    /// [`capacity`]: Sender::capacity
+    pub fn max_capacity(&self) -> usize {
+        self.chan.semaphore().bound
     }
 }
 
@@ -949,6 +1105,29 @@ impl<T> fmt::Debug for Sender<T> {
     }
 }
 
+impl<T> Clone for WeakSender<T> {
+    fn clone(&self) -> Self {
+        WeakSender {
+            chan: self.chan.clone(),
+        }
+    }
+}
+
+impl<T> WeakSender<T> {
+    /// Tries to convert a WeakSender into a [`Sender`]. This will return `Some`
+    /// if there are other `Sender` instances alive and the channel wasn't
+    /// previously dropped, otherwise `None` is returned.
+    pub fn upgrade(&self) -> Option<Sender<T>> {
+        chan::Tx::upgrade(self.chan.clone()).map(Sender::new)
+    }
+}
+
+impl<T> fmt::Debug for WeakSender<T> {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt.debug_struct("WeakSender").finish()
+    }
+}
+
 // ===== impl Permit =====
 
 impl<T> Permit<'_, T> {
@@ -1065,7 +1244,7 @@ impl<T> OwnedPermit<T> {
         Sender { chan }
     }
 
-    /// Release the reserved capacity *without* sending a message, returning the
+    /// Releases the reserved capacity *without* sending a message, returning the
     /// [`Sender`].
     ///
     /// # Examples
diff --git a/vendor/tokio/src/sync/mpsc/chan.rs b/vendor/tokio/src/sync/mpsc/chan.rs
index 554d02284..6f87715dd 100644
--- a/vendor/tokio/src/sync/mpsc/chan.rs
+++ b/vendor/tokio/src/sync/mpsc/chan.rs
@@ -2,16 +2,18 @@ use crate::loom::cell::UnsafeCell;
 use crate::loom::future::AtomicWaker;
 use crate::loom::sync::atomic::AtomicUsize;
 use crate::loom::sync::Arc;
-use crate::sync::mpsc::list;
+use crate::runtime::park::CachedParkThread;
+use crate::sync::mpsc::error::TryRecvError;
+use crate::sync::mpsc::{bounded, list, unbounded};
 use crate::sync::notify::Notify;
 
 use std::fmt;
 use std::process;
-use std::sync::atomic::Ordering::{AcqRel, Relaxed};
+use std::sync::atomic::Ordering::{AcqRel, Acquire, Relaxed, Release};
 use std::task::Poll::{Pending, Ready};
 use std::task::{Context, Poll};
 
-/// Channel sender
+/// Channel sender.
 pub(crate) struct Tx<T, S> {
     inner: Arc<Chan<T, S>>,
 }
@@ -22,7 +24,7 @@ impl<T, S: fmt::Debug> fmt::Debug for Tx<T, S> {
     }
 }
 
-/// Channel receiver
+/// Channel receiver.
 pub(crate) struct Rx<T, S: Semaphore> {
     inner: Arc<Chan<T, S>>,
 }
@@ -43,8 +45,8 @@ pub(crate) trait Semaphore {
     fn is_closed(&self) -> bool;
 }
 
-struct Chan<T, S> {
-    /// Notifies all tasks listening for the receiver being dropped
+pub(super) struct Chan<T, S> {
+    /// Notifies all tasks listening for the receiver being dropped.
     notify_rx_closed: Notify,
 
     /// Handle to the push half of the lock-free list.
@@ -126,6 +128,30 @@ impl<T, S> Tx<T, S> {
         Tx { inner: chan }
     }
 
+    pub(super) fn downgrade(&self) -> Arc<Chan<T, S>> {
+        self.inner.clone()
+    }
+
+    // Returns the upgraded channel or None if the upgrade failed.
+    pub(super) fn upgrade(chan: Arc<Chan<T, S>>) -> Option<Self> {
+        let mut tx_count = chan.tx_count.load(Acquire);
+
+        loop {
+            if tx_count == 0 {
+                // channel is closed
+                return None;
+            }
+
+            match chan
+                .tx_count
+                .compare_exchange_weak(tx_count, tx_count + 1, AcqRel, Acquire)
+            {
+                Ok(_) => return Some(Tx { inner: chan }),
+                Err(prev_count) => tx_count = prev_count,
+            }
+        }
+    }
+
     pub(super) fn semaphore(&self) -> &S {
         &self.inner.semaphore
     }
@@ -216,8 +242,10 @@ impl<T, S: Semaphore> Rx<T, S> {
     pub(crate) fn recv(&mut self, cx: &mut Context<'_>) -> Poll<Option<T>> {
         use super::block::Read::*;
 
+        ready!(crate::trace::trace_leaf(cx));
+
         // Keep track of task budget
-        let coop = ready!(crate::coop::poll_proceed(cx));
+        let coop = ready!(crate::runtime::coop::poll_proceed(cx));
 
         self.inner.rx_fields.with_mut(|rx_fields_ptr| {
             let rx_fields = unsafe { &mut *rx_fields_ptr };
@@ -263,6 +291,51 @@ impl<T, S: Semaphore> Rx<T, S> {
             }
         })
     }
+
+    /// Try to receive the next value.
+    pub(crate) fn try_recv(&mut self) -> Result<T, TryRecvError> {
+        use super::list::TryPopResult;
+
+        self.inner.rx_fields.with_mut(|rx_fields_ptr| {
+            let rx_fields = unsafe { &mut *rx_fields_ptr };
+
+            macro_rules! try_recv {
+                () => {
+                    match rx_fields.list.try_pop(&self.inner.tx) {
+                        TryPopResult::Ok(value) => {
+                            self.inner.semaphore.add_permit();
+                            return Ok(value);
+                        }
+                        TryPopResult::Closed => return Err(TryRecvError::Disconnected),
+                        TryPopResult::Empty => return Err(TryRecvError::Empty),
+                        TryPopResult::Busy => {} // fall through
+                    }
+                };
+            }
+
+            try_recv!();
+
+            // If a previous `poll_recv` call has set a waker, we wake it here.
+            // This allows us to put our own CachedParkThread waker in the
+            // AtomicWaker slot instead.
+            //
+            // This is not a spurious wakeup to `poll_recv` since we just got a
+            // Busy from `try_pop`, which only happens if there are messages in
+            // the queue.
+            self.inner.rx_waker.wake();
+
+            // Park the thread until the problematic send has completed.
+            let mut park = CachedParkThread::new();
+            let waker = park.waker().unwrap();
+            loop {
+                self.inner.rx_waker.register_by_ref(&waker);
+                // It is possible that the problematic send has now completed,
+                // so we have to check for messages again.
+                try_recv!();
+                park.park();
+            }
+        })
+    }
 }
 
 impl<T, S: Semaphore> Drop for Rx<T, S> {
@@ -297,7 +370,7 @@ impl<T, S> Drop for Chan<T, S> {
     fn drop(&mut self) {
         use super::block::Read::Value;
 
-        // Safety: the only owner of the rx fields is Chan, and eing
+        // Safety: the only owner of the rx fields is Chan, and being
         // inside its own Drop means we're the last ones to touch it.
         self.rx_fields.with_mut(|rx_fields_ptr| {
             let rx_fields = unsafe { &mut *rx_fields_ptr };
@@ -310,32 +383,29 @@ impl<T, S> Drop for Chan<T, S> {
 
 // ===== impl Semaphore for (::Semaphore, capacity) =====
 
-impl Semaphore for (crate::sync::batch_semaphore::Semaphore, usize) {
+impl Semaphore for bounded::Semaphore {
     fn add_permit(&self) {
-        self.0.release(1)
+        self.semaphore.release(1)
     }
 
     fn is_idle(&self) -> bool {
-        self.0.available_permits() == self.1
+        self.semaphore.available_permits() == self.bound
     }
 
     fn close(&self) {
-        self.0.close();
+        self.semaphore.close();
     }
 
     fn is_closed(&self) -> bool {
-        self.0.is_closed()
+        self.semaphore.is_closed()
     }
 }
 
 // ===== impl Semaphore for AtomicUsize =====
 
-use std::sync::atomic::Ordering::{Acquire, Release};
-use std::usize;
-
-impl Semaphore for AtomicUsize {
+impl Semaphore for unbounded::Semaphore {
     fn add_permit(&self) {
-        let prev = self.fetch_sub(2, Release);
+        let prev = self.0.fetch_sub(2, Release);
 
         if prev >> 1 == 0 {
             // Something went wrong
@@ -344,14 +414,14 @@ impl Semaphore for AtomicUsize {
     }
 
     fn is_idle(&self) -> bool {
-        self.load(Acquire) >> 1 == 0
+        self.0.load(Acquire) >> 1 == 0
     }
 
     fn close(&self) {
-        self.fetch_or(1, Release);
+        self.0.fetch_or(1, Release);
     }
 
     fn is_closed(&self) -> bool {
-        self.load(Acquire) & 1 == 1
+        self.0.load(Acquire) & 1 == 1
     }
 }
diff --git a/vendor/tokio/src/sync/mpsc/error.rs b/vendor/tokio/src/sync/mpsc/error.rs
index 0d25ad386..25b4455be 100644
--- a/vendor/tokio/src/sync/mpsc/error.rs
+++ b/vendor/tokio/src/sync/mpsc/error.rs
@@ -1,25 +1,31 @@
-//! Channel error types
+//! Channel error types.
 
 use std::error::Error;
 use std::fmt;
 
 /// Error returned by the `Sender`.
-#[derive(Debug)]
+#[derive(PartialEq, Eq, Clone, Copy)]
 pub struct SendError<T>(pub T);
 
+impl<T> fmt::Debug for SendError<T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("SendError").finish_non_exhaustive()
+    }
+}
+
 impl<T> fmt::Display for SendError<T> {
     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(fmt, "channel closed")
     }
 }
 
-impl<T: fmt::Debug> std::error::Error for SendError<T> {}
+impl<T> std::error::Error for SendError<T> {}
 
 // ===== TrySendError =====
 
 /// This enumeration is the list of the possible error outcomes for the
 /// [try_send](super::Sender::try_send) method.
-#[derive(Debug)]
+#[derive(PartialEq, Eq, Clone, Copy)]
 pub enum TrySendError<T> {
     /// The data could not be sent on the channel because the channel is
     /// currently full and sending would require blocking.
@@ -30,7 +36,14 @@ pub enum TrySendError<T> {
     Closed(T),
 }
 
-impl<T: fmt::Debug> Error for TrySendError<T> {}
+impl<T> fmt::Debug for TrySendError<T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match *self {
+            TrySendError::Full(..) => "Full(..)".fmt(f),
+            TrySendError::Closed(..) => "Closed(..)".fmt(f),
+        }
+    }
+}
 
 impl<T> fmt::Display for TrySendError<T> {
     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
@@ -45,16 +58,42 @@ impl<T> fmt::Display for TrySendError<T> {
     }
 }
 
+impl<T> Error for TrySendError<T> {}
+
 impl<T> From<SendError<T>> for TrySendError<T> {
     fn from(src: SendError<T>) -> TrySendError<T> {
         TrySendError::Closed(src.0)
     }
 }
 
+// ===== TryRecvError =====
+
+/// Error returned by `try_recv`.
+#[derive(PartialEq, Eq, Clone, Copy, Debug)]
+pub enum TryRecvError {
+    /// This **channel** is currently empty, but the **Sender**(s) have not yet
+    /// disconnected, so data may yet become available.
+    Empty,
+    /// The **channel**'s sending half has become disconnected, and there will
+    /// never be any more data received on it.
+    Disconnected,
+}
+
+impl fmt::Display for TryRecvError {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match *self {
+            TryRecvError::Empty => "receiving on an empty channel".fmt(fmt),
+            TryRecvError::Disconnected => "receiving on a closed channel".fmt(fmt),
+        }
+    }
+}
+
+impl Error for TryRecvError {}
+
 // ===== RecvError =====
 
 /// Error returned by `Receiver`.
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 #[doc(hidden)]
 #[deprecated(note = "This type is unused because recv returns an Option.")]
 pub struct RecvError(());
@@ -72,7 +111,7 @@ impl Error for RecvError {}
 cfg_time! {
     // ===== SendTimeoutError =====
 
-    #[derive(Debug)]
+    #[derive(PartialEq, Eq, Clone, Copy)]
     /// Error returned by [`Sender::send_timeout`](super::Sender::send_timeout)].
     pub enum SendTimeoutError<T> {
         /// The data could not be sent on the channel because the channel is
@@ -84,7 +123,14 @@ cfg_time! {
         Closed(T),
     }
 
-    impl<T: fmt::Debug> Error for SendTimeoutError<T> {}
+    impl<T> fmt::Debug for SendTimeoutError<T> {
+        fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+            match *self {
+                SendTimeoutError::Timeout(..) => "Timeout(..)".fmt(f),
+                SendTimeoutError::Closed(..) => "Closed(..)".fmt(f),
+            }
+        }
+    }
 
     impl<T> fmt::Display for SendTimeoutError<T> {
         fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
@@ -98,4 +144,6 @@ cfg_time! {
             )
         }
     }
+
+    impl<T> Error for SendTimeoutError<T> {}
 }
diff --git a/vendor/tokio/src/sync/mpsc/list.rs b/vendor/tokio/src/sync/mpsc/list.rs
index 5dad2babf..10b29575b 100644
--- a/vendor/tokio/src/sync/mpsc/list.rs
+++ b/vendor/tokio/src/sync/mpsc/list.rs
@@ -8,31 +8,43 @@ use std::fmt;
 use std::ptr::NonNull;
 use std::sync::atomic::Ordering::{AcqRel, Acquire, Relaxed, Release};
 
-/// List queue transmit handle
+/// List queue transmit handle.
 pub(crate) struct Tx<T> {
     /// Tail in the `Block` mpmc list.
     block_tail: AtomicPtr<Block<T>>,
 
-    /// Position to push the next message. This reference a block and offset
+    /// Position to push the next message. This references a block and offset
     /// into the block.
     tail_position: AtomicUsize,
 }
 
 /// List queue receive handle
 pub(crate) struct Rx<T> {
-    /// Pointer to the block being processed
+    /// Pointer to the block being processed.
     head: NonNull<Block<T>>,
 
-    /// Next slot index to process
+    /// Next slot index to process.
     index: usize,
 
-    /// Pointer to the next block pending release
+    /// Pointer to the next block pending release.
     free_head: NonNull<Block<T>>,
 }
 
+/// Return value of `Rx::try_pop`.
+pub(crate) enum TryPopResult<T> {
+    /// Successfully popped a value.
+    Ok(T),
+    /// The channel is empty.
+    Empty,
+    /// The channel is empty and closed.
+    Closed,
+    /// The channel is not empty, but the first value is being written.
+    Busy,
+}
+
 pub(crate) fn channel<T>() -> (Tx<T>, Rx<T>) {
     // Create the initial block shared between the tx and rx halves.
-    let initial_block = Box::new(Block::new(0));
+    let initial_block = Block::new(0);
     let initial_block_ptr = Box::into_raw(initial_block);
 
     let tx = Tx {
@@ -67,7 +79,7 @@ impl<T> Tx<T> {
         }
     }
 
-    /// Closes the send half of the list
+    /// Closes the send half of the list.
     ///
     /// Similar process as pushing a value, but instead of writing the value &
     /// setting the ready flag, the TX_CLOSED flag is set on the block.
@@ -218,7 +230,7 @@ impl<T> fmt::Debug for Tx<T> {
 }
 
 impl<T> Rx<T> {
-    /// Pops the next value off the queue
+    /// Pops the next value off the queue.
     pub(crate) fn pop(&mut self, tx: &Tx<T>) -> Option<block::Read<T>> {
         // Advance `head`, if needed
         if !self.try_advancing_head() {
@@ -240,6 +252,26 @@ impl<T> Rx<T> {
         }
     }
 
+    /// Pops the next value off the queue, detecting whether the block
+    /// is busy or empty on failure.
+    ///
+    /// This function exists because `Rx::pop` can return `None` even if the
+    /// channel's queue contains a message that has been completely written.
+    /// This can happen if the fully delivered message is behind another message
+    /// that is in the middle of being written to the block, since the channel
+    /// can't return the messages out of order.
+    pub(crate) fn try_pop(&mut self, tx: &Tx<T>) -> TryPopResult<T> {
+        let tail_position = tx.tail_position.load(Acquire);
+        let result = self.pop(tx);
+
+        match result {
+            Some(block::Read::Value(t)) => TryPopResult::Ok(t),
+            Some(block::Read::Closed) => TryPopResult::Closed,
+            None if tail_position == self.index => TryPopResult::Empty,
+            None => TryPopResult::Busy,
+        }
+    }
+
     /// Tries advancing the block pointer to the block referenced by `self.index`.
     ///
     /// Returns `true` if successful, `false` if there is no next block to load.
diff --git a/vendor/tokio/src/sync/mpsc/mod.rs b/vendor/tokio/src/sync/mpsc/mod.rs
index 879e3dcfc..b2af084b2 100644
--- a/vendor/tokio/src/sync/mpsc/mod.rs
+++ b/vendor/tokio/src/sync/mpsc/mod.rs
@@ -21,6 +21,9 @@
 //! when additional capacity is available. In other words, the channel provides
 //! backpressure.
 //!
+//! This channel is also suitable for the single-producer single-consumer
+//! use-case. (Unless you only need to send one message, in which case you
+//! should use the [oneshot] channel.)
 //!
 //! # Disconnection
 //!
@@ -30,7 +33,8 @@
 //!
 //! If the [`Receiver`] handle is dropped, then messages can no longer
 //! be read out of the channel. In this case, all further attempts to send will
-//! result in an error.
+//! result in an error. Additionally, all unread messages will be drained from the
+//! channel and dropped.
 //!
 //! # Clean Shutdown
 //!
@@ -58,6 +62,22 @@
 //! [crossbeam][crossbeam-unbounded].  Similarly, for sending a message _from sync
 //! to async_, you should use an unbounded Tokio `mpsc` channel.
 //!
+//! Please be aware that the above remarks were written with the `mpsc` channel
+//! in mind, but they can also be generalized to other kinds of channels. In
+//! general, any channel method that isn't marked async can be called anywhere,
+//! including outside of the runtime. For example, sending a message on a
+//! [oneshot] channel from outside the runtime is perfectly fine.
+//!
+//! # Multiple runtimes
+//!
+//! The mpsc channel does not care about which runtime you use it in, and can be
+//! used to send messages from one runtime to another. It can also be used in
+//! non-Tokio runtimes.
+//!
+//! There is one exception to the above: the [`send_timeout`] must be used from
+//! within a Tokio runtime, however it is still not tied to one specific Tokio
+//! runtime, and the sender may be moved from one Tokio runtime to another.
+//!
 //! [`Sender`]: crate::sync::mpsc::Sender
 //! [`Receiver`]: crate::sync::mpsc::Receiver
 //! [bounded-send]: crate::sync::mpsc::Sender::send()
@@ -66,21 +86,25 @@
 //! [blocking-recv]: crate::sync::mpsc::Receiver::blocking_recv()
 //! [`UnboundedSender`]: crate::sync::mpsc::UnboundedSender
 //! [`UnboundedReceiver`]: crate::sync::mpsc::UnboundedReceiver
+//! [oneshot]: crate::sync::oneshot
 //! [`Handle::block_on`]: crate::runtime::Handle::block_on()
 //! [std-unbounded]: std::sync::mpsc::channel
 //! [crossbeam-unbounded]: https://docs.rs/crossbeam/*/crossbeam/channel/fn.unbounded.html
+//! [`send_timeout`]: crate::sync::mpsc::Sender::send_timeout
 
 pub(super) mod block;
 
 mod bounded;
-pub use self::bounded::{channel, OwnedPermit, Permit, Receiver, Sender};
+pub use self::bounded::{channel, OwnedPermit, Permit, Receiver, Sender, WeakSender};
 
 mod chan;
 
 pub(super) mod list;
 
 mod unbounded;
-pub use self::unbounded::{unbounded_channel, UnboundedReceiver, UnboundedSender};
+pub use self::unbounded::{
+    unbounded_channel, UnboundedReceiver, UnboundedSender, WeakUnboundedSender,
+};
 
 pub mod error;
 
diff --git a/vendor/tokio/src/sync/mpsc/unbounded.rs b/vendor/tokio/src/sync/mpsc/unbounded.rs
index 23c80f60a..cd83fc125 100644
--- a/vendor/tokio/src/sync/mpsc/unbounded.rs
+++ b/vendor/tokio/src/sync/mpsc/unbounded.rs
@@ -1,6 +1,6 @@
-use crate::loom::sync::atomic::AtomicUsize;
+use crate::loom::sync::{atomic::AtomicUsize, Arc};
 use crate::sync::mpsc::chan;
-use crate::sync::mpsc::error::SendError;
+use crate::sync::mpsc::error::{SendError, TryRecvError};
 
 use std::fmt;
 use std::task::{Context, Poll};
@@ -13,6 +13,40 @@ pub struct UnboundedSender<T> {
     chan: chan::Tx<T, Semaphore>,
 }
 
+/// An unbounded sender that does not prevent the channel from being closed.
+///
+/// If all [`UnboundedSender`] instances of a channel were dropped and only
+/// `WeakUnboundedSender` instances remain, the channel is closed.
+///
+/// In order to send messages, the `WeakUnboundedSender` needs to be upgraded using
+/// [`WeakUnboundedSender::upgrade`], which returns `Option<UnboundedSender>`. It returns `None`
+/// if all `UnboundedSender`s have been dropped, and otherwise it returns an `UnboundedSender`.
+///
+/// [`UnboundedSender`]: UnboundedSender
+/// [`WeakUnboundedSender::upgrade`]: WeakUnboundedSender::upgrade
+///
+/// #Examples
+///
+/// ```
+/// use tokio::sync::mpsc::unbounded_channel;
+///
+/// #[tokio::main]
+/// async fn main() {
+///     let (tx, _rx) = unbounded_channel::<i32>();
+///     let tx_weak = tx.downgrade();
+///   
+///     // Upgrading will succeed because `tx` still exists.
+///     assert!(tx_weak.upgrade().is_some());
+///   
+///     // If we drop `tx`, then it will fail.
+///     drop(tx);
+///     assert!(tx_weak.clone().upgrade().is_none());
+/// }
+/// ```
+pub struct WeakUnboundedSender<T> {
+    chan: Arc<chan::Chan<T, Semaphore>>,
+}
+
 impl<T> Clone for UnboundedSender<T> {
     fn clone(&self) -> Self {
         UnboundedSender {
@@ -61,7 +95,7 @@ impl<T> fmt::Debug for UnboundedReceiver<T> {
 /// the channel. Using an `unbounded` channel has the ability of causing the
 /// process to run out of memory. In this case, the process will be aborted.
 pub fn unbounded_channel<T>() -> (UnboundedSender<T>, UnboundedReceiver<T>) {
-    let (tx, rx) = chan::channel(AtomicUsize::new(0));
+    let (tx, rx) = chan::channel(Semaphore(AtomicUsize::new(0)));
 
     let tx = UnboundedSender::new(tx);
     let rx = UnboundedReceiver::new(rx);
@@ -70,7 +104,8 @@ pub fn unbounded_channel<T>() -> (UnboundedSender<T>, UnboundedReceiver<T>) {
 }
 
 /// No capacity
-type Semaphore = AtomicUsize;
+#[derive(Debug)]
+pub(crate) struct Semaphore(pub(crate) AtomicUsize);
 
 impl<T> UnboundedReceiver<T> {
     pub(crate) fn new(chan: chan::Rx<T, Semaphore>) -> UnboundedReceiver<T> {
@@ -79,8 +114,14 @@ impl<T> UnboundedReceiver<T> {
 
     /// Receives the next value for this receiver.
     ///
-    /// `None` is returned when all `Sender` halves have dropped, indicating
-    /// that no further values can be sent on the channel.
+    /// This method returns `None` if the channel has been closed and there are
+    /// no remaining messages in the channel's buffer. This indicates that no
+    /// further values can ever be received from this `Receiver`. The channel is
+    /// closed when all senders have been dropped, or when [`close`] is called.
+    ///
+    /// If there are no messages in the channel's buffer, but the channel has
+    /// not yet been closed, this method will sleep until a message is sent or
+    /// the channel is closed.
     ///
     /// # Cancel safety
     ///
@@ -89,6 +130,8 @@ impl<T> UnboundedReceiver<T> {
     /// completes first, it is guaranteed that no messages were received on this
     /// channel.
     ///
+    /// [`close`]: Self::close
+    ///
     /// # Examples
     ///
     /// ```
@@ -129,6 +172,50 @@ impl<T> UnboundedReceiver<T> {
         poll_fn(|cx| self.poll_recv(cx)).await
     }
 
+    /// Tries to receive the next value for this receiver.
+    ///
+    /// This method returns the [`Empty`] error if the channel is currently
+    /// empty, but there are still outstanding [senders] or [permits].
+    ///
+    /// This method returns the [`Disconnected`] error if the channel is
+    /// currently empty, and there are no outstanding [senders] or [permits].
+    ///
+    /// Unlike the [`poll_recv`] method, this method will never return an
+    /// [`Empty`] error spuriously.
+    ///
+    /// [`Empty`]: crate::sync::mpsc::error::TryRecvError::Empty
+    /// [`Disconnected`]: crate::sync::mpsc::error::TryRecvError::Disconnected
+    /// [`poll_recv`]: Self::poll_recv
+    /// [senders]: crate::sync::mpsc::Sender
+    /// [permits]: crate::sync::mpsc::Permit
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::sync::mpsc;
+    /// use tokio::sync::mpsc::error::TryRecvError;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let (tx, mut rx) = mpsc::unbounded_channel();
+    ///
+    ///     tx.send("hello").unwrap();
+    ///
+    ///     assert_eq!(Ok("hello"), rx.try_recv());
+    ///     assert_eq!(Err(TryRecvError::Empty), rx.try_recv());
+    ///
+    ///     tx.send("hello").unwrap();
+    ///     // Drop the last sender, closing the channel.
+    ///     drop(tx);
+    ///
+    ///     assert_eq!(Ok("hello"), rx.try_recv());
+    ///     assert_eq!(Err(TryRecvError::Disconnected), rx.try_recv());
+    /// }
+    /// ```
+    pub fn try_recv(&mut self) -> Result<T, TryRecvError> {
+        self.chan.try_recv()
+    }
+
     /// Blocking receive to call outside of asynchronous contexts.
     ///
     /// # Panics
@@ -154,7 +241,9 @@ impl<T> UnboundedReceiver<T> {
     ///     sync_code.join().unwrap();
     /// }
     /// ```
+    #[track_caller]
     #[cfg(feature = "sync")]
+    #[cfg_attr(docsrs, doc(alias = "recv_blocking"))]
     pub fn blocking_recv(&mut self) -> Option<T> {
         crate::future::block_on(self.recv())
     }
@@ -163,6 +252,9 @@ impl<T> UnboundedReceiver<T> {
     ///
     /// This prevents any further messages from being sent on the channel while
     /// still enabling the receiver to drain messages that are buffered.
+    ///
+    /// To guarantee that no messages are dropped, after calling `close()`,
+    /// `recv()` must be called until `None` is returned.
     pub fn close(&mut self) {
         self.chan.close();
     }
@@ -172,7 +264,7 @@ impl<T> UnboundedReceiver<T> {
     /// This method returns:
     ///
     ///  * `Poll::Pending` if no messages are available but the channel is not
-    ///    closed.
+    ///    closed, or if a spurious failure happens.
     ///  * `Poll::Ready(Some(message))` if a message is available.
     ///  * `Poll::Ready(None)` if the channel has been closed and all messages
     ///    sent before it was closed have been received.
@@ -182,6 +274,12 @@ impl<T> UnboundedReceiver<T> {
     /// receiver, or when the channel is closed.  Note that on multiple calls to
     /// `poll_recv`, only the `Waker` from the `Context` passed to the most
     /// recent call is scheduled to receive a wakeup.
+    ///
+    /// If this method returns `Poll::Pending` due to a spurious failure, then
+    /// the `Waker` will be notified when the situation causing the spurious
+    /// failure has been resolved. Note that receiving such a wakeup does not
+    /// guarantee that the next call will succeed — it could fail with another
+    /// spurious failure.
     pub fn poll_recv(&mut self, cx: &mut Context<'_>) -> Poll<Option<T>> {
         self.chan.recv(cx)
     }
@@ -217,7 +315,7 @@ impl<T> UnboundedSender<T> {
         use std::process;
         use std::sync::atomic::Ordering::{AcqRel, Acquire};
 
-        let mut curr = self.chan.semaphore().load(Acquire);
+        let mut curr = self.chan.semaphore().0.load(Acquire);
 
         loop {
             if curr & 1 == 1 {
@@ -233,6 +331,7 @@ impl<T> UnboundedSender<T> {
             match self
                 .chan
                 .semaphore()
+                .0
                 .compare_exchange(curr, curr + 2, AcqRel, Acquire)
             {
                 Ok(_) => return true,
@@ -320,4 +419,37 @@ impl<T> UnboundedSender<T> {
     pub fn same_channel(&self, other: &Self) -> bool {
         self.chan.same_channel(&other.chan)
     }
+
+    /// Converts the `UnboundedSender` to a [`WeakUnboundedSender`] that does not count
+    /// towards RAII semantics, i.e. if all `UnboundedSender` instances of the
+    /// channel were dropped and only `WeakUnboundedSender` instances remain,
+    /// the channel is closed.
+    pub fn downgrade(&self) -> WeakUnboundedSender<T> {
+        WeakUnboundedSender {
+            chan: self.chan.downgrade(),
+        }
+    }
+}
+
+impl<T> Clone for WeakUnboundedSender<T> {
+    fn clone(&self) -> Self {
+        WeakUnboundedSender {
+            chan: self.chan.clone(),
+        }
+    }
+}
+
+impl<T> WeakUnboundedSender<T> {
+    /// Tries to convert a WeakUnboundedSender into an [`UnboundedSender`].
+    /// This will return `Some` if there are other `Sender` instances alive and
+    /// the channel wasn't previously dropped, otherwise `None` is returned.
+    pub fn upgrade(&self) -> Option<UnboundedSender<T>> {
+        chan::Tx::upgrade(self.chan.clone()).map(UnboundedSender::new)
+    }
+}
+
+impl<T> fmt::Debug for WeakUnboundedSender<T> {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt.debug_struct("WeakUnboundedSender").finish()
+    }
 }
diff --git a/vendor/tokio/src/sync/mutex.rs b/vendor/tokio/src/sync/mutex.rs
index 8ae824770..549c77b32 100644
--- a/vendor/tokio/src/sync/mutex.rs
+++ b/vendor/tokio/src/sync/mutex.rs
@@ -1,12 +1,15 @@
 #![cfg_attr(not(feature = "sync"), allow(unreachable_pub, dead_code))]
 
 use crate::sync::batch_semaphore as semaphore;
+#[cfg(all(tokio_unstable, feature = "tracing"))]
+use crate::util::trace;
 
 use std::cell::UnsafeCell;
 use std::error::Error;
+use std::marker::PhantomData;
 use std::ops::{Deref, DerefMut};
 use std::sync::Arc;
-use std::{fmt, marker, mem};
+use std::{fmt, mem, ptr};
 
 /// An asynchronous `Mutex`-like type.
 ///
@@ -124,6 +127,8 @@ use std::{fmt, marker, mem};
 /// [`Send`]: trait@std::marker::Send
 /// [`lock`]: method@Mutex::lock
 pub struct Mutex<T: ?Sized> {
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    resource_span: tracing::Span,
     s: semaphore::Semaphore,
     c: UnsafeCell<T>,
 }
@@ -137,7 +142,13 @@ pub struct Mutex<T: ?Sized> {
 ///
 /// The lock is automatically released whenever the guard is dropped, at which
 /// point `lock` will succeed yet again.
+#[clippy::has_significant_drop]
+#[must_use = "if unused the Mutex will immediately unlock"]
 pub struct MutexGuard<'a, T: ?Sized> {
+    // When changing the fields in this struct, make sure to update the
+    // `skip_drop` method.
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    resource_span: tracing::Span,
     lock: &'a Mutex<T>,
 }
 
@@ -156,7 +167,12 @@ pub struct MutexGuard<'a, T: ?Sized> {
 /// point `lock` will succeed yet again.
 ///
 /// [`Arc`]: std::sync::Arc
+#[clippy::has_significant_drop]
 pub struct OwnedMutexGuard<T: ?Sized> {
+    // When changing the fields in this struct, make sure to update the
+    // `skip_drop` method.
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    resource_span: tracing::Span,
     lock: Arc<Mutex<T>>,
 }
 
@@ -165,12 +181,71 @@ pub struct OwnedMutexGuard<T: ?Sized> {
 /// This can be used to hold a subfield of the protected data.
 ///
 /// [`MutexGuard::map`]: method@MutexGuard::map
+#[clippy::has_significant_drop]
 #[must_use = "if unused the Mutex will immediately unlock"]
 pub struct MappedMutexGuard<'a, T: ?Sized> {
+    // When changing the fields in this struct, make sure to update the
+    // `skip_drop` method.
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    resource_span: tracing::Span,
     s: &'a semaphore::Semaphore,
     data: *mut T,
     // Needed to tell the borrow checker that we are holding a `&mut T`
-    marker: marker::PhantomData<&'a mut T>,
+    marker: PhantomData<&'a mut T>,
+}
+
+/// A owned handle to a held `Mutex` that has had a function applied to it via
+/// [`OwnedMutexGuard::map`].
+///
+/// This can be used to hold a subfield of the protected data.
+///
+/// [`OwnedMutexGuard::map`]: method@OwnedMutexGuard::map
+#[clippy::has_significant_drop]
+#[must_use = "if unused the Mutex will immediately unlock"]
+pub struct OwnedMappedMutexGuard<T: ?Sized, U: ?Sized = T> {
+    // When changing the fields in this struct, make sure to update the
+    // `skip_drop` method.
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    resource_span: tracing::Span,
+    data: *mut U,
+    lock: Arc<Mutex<T>>,
+}
+
+/// A helper type used when taking apart a `MutexGuard` without running its
+/// Drop implementation.
+#[allow(dead_code)] // Unused fields are still used in Drop.
+struct MutexGuardInner<'a, T: ?Sized> {
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    resource_span: tracing::Span,
+    lock: &'a Mutex<T>,
+}
+
+/// A helper type used when taking apart a `OwnedMutexGuard` without running
+/// its Drop implementation.
+struct OwnedMutexGuardInner<T: ?Sized> {
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    resource_span: tracing::Span,
+    lock: Arc<Mutex<T>>,
+}
+
+/// A helper type used when taking apart a `MappedMutexGuard` without running
+/// its Drop implementation.
+#[allow(dead_code)] // Unused fields are still used in Drop.
+struct MappedMutexGuardInner<'a, T: ?Sized> {
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    resource_span: tracing::Span,
+    s: &'a semaphore::Semaphore,
+    data: *mut T,
+}
+
+/// A helper type used when taking apart a `OwnedMappedMutexGuard` without running
+/// its Drop implementation.
+#[allow(dead_code)] // Unused fields are still used in Drop.
+struct OwnedMappedMutexGuardInner<T: ?Sized, U: ?Sized> {
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    resource_span: tracing::Span,
+    data: *mut U,
+    lock: Arc<Mutex<T>>,
 }
 
 // As long as T: Send, it's fine to send and share Mutex<T> between threads.
@@ -183,6 +258,19 @@ unsafe impl<T> Sync for OwnedMutexGuard<T> where T: ?Sized + Send + Sync {}
 unsafe impl<'a, T> Sync for MappedMutexGuard<'a, T> where T: ?Sized + Sync + 'a {}
 unsafe impl<'a, T> Send for MappedMutexGuard<'a, T> where T: ?Sized + Send + 'a {}
 
+unsafe impl<T, U> Sync for OwnedMappedMutexGuard<T, U>
+where
+    T: ?Sized + Send + Sync,
+    U: ?Sized + Send + Sync,
+{
+}
+unsafe impl<T, U> Send for OwnedMappedMutexGuard<T, U>
+where
+    T: ?Sized + Send,
+    U: ?Sized + Send,
+{
+}
+
 /// Error returned from the [`Mutex::try_lock`], [`RwLock::try_read`] and
 /// [`RwLock::try_write`] functions.
 ///
@@ -191,8 +279,8 @@ unsafe impl<'a, T> Send for MappedMutexGuard<'a, T> where T: ?Sized + Send + 'a
 /// `RwLock::try_read` operation will only fail if the lock is currently held
 /// by an exclusive writer.
 ///
-/// `RwLock::try_write` operation will if lock is held by any reader or by an
-/// exclusive writer.
+/// `RwLock::try_write` operation will only fail if the lock is currently held
+/// by any reader or by an exclusive writer.
 ///
 /// [`Mutex::try_lock`]: Mutex::try_lock
 /// [`RwLock::try_read`]: fn@super::RwLock::try_read
@@ -242,13 +330,42 @@ impl<T: ?Sized> Mutex<T> {
     ///
     /// let lock = Mutex::new(5);
     /// ```
+    #[track_caller]
     pub fn new(t: T) -> Self
     where
         T: Sized,
     {
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let resource_span = {
+            let location = std::panic::Location::caller();
+
+            tracing::trace_span!(
+                "runtime.resource",
+                concrete_type = "Mutex",
+                kind = "Sync",
+                loc.file = location.file(),
+                loc.line = location.line(),
+                loc.col = location.column(),
+            )
+        };
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let s = resource_span.in_scope(|| {
+            tracing::trace!(
+                target: "runtime::resource::state_update",
+                locked = false,
+            );
+            semaphore::Semaphore::new(1)
+        });
+
+        #[cfg(any(not(tokio_unstable), not(feature = "tracing")))]
+        let s = semaphore::Semaphore::new(1);
+
         Self {
             c: UnsafeCell::new(t),
-            s: semaphore::Semaphore::new(1),
+            s,
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span,
         }
     }
 
@@ -270,6 +387,8 @@ impl<T: ?Sized> Mutex<T> {
         Self {
             c: UnsafeCell::new(t),
             s: semaphore::Semaphore::const_new(1),
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: tracing::Span::none(),
         }
     }
 
@@ -297,8 +416,147 @@ impl<T: ?Sized> Mutex<T> {
     /// }
     /// ```
     pub async fn lock(&self) -> MutexGuard<'_, T> {
-        self.acquire().await;
-        MutexGuard { lock: self }
+        let acquire_fut = async {
+            self.acquire().await;
+
+            MutexGuard {
+                lock: self,
+                #[cfg(all(tokio_unstable, feature = "tracing"))]
+                resource_span: self.resource_span.clone(),
+            }
+        };
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let acquire_fut = trace::async_op(
+            move || acquire_fut,
+            self.resource_span.clone(),
+            "Mutex::lock",
+            "poll",
+            false,
+        );
+
+        #[allow(clippy::let_and_return)] // this lint triggers when disabling tracing
+        let guard = acquire_fut.await;
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        self.resource_span.in_scope(|| {
+            tracing::trace!(
+                target: "runtime::resource::state_update",
+                locked = true,
+            );
+        });
+
+        guard
+    }
+
+    /// Blockingly locks this `Mutex`. When the lock has been acquired, function returns a
+    /// [`MutexGuard`].
+    ///
+    /// This method is intended for use cases where you
+    /// need to use this mutex in asynchronous code as well as in synchronous code.
+    ///
+    /// # Panics
+    ///
+    /// This function panics if called within an asynchronous execution context.
+    ///
+    ///   - If you find yourself in an asynchronous execution context and needing
+    ///     to call some (synchronous) function which performs one of these
+    ///     `blocking_` operations, then consider wrapping that call inside
+    ///     [`spawn_blocking()`][crate::runtime::Handle::spawn_blocking]
+    ///     (or [`block_in_place()`][crate::task::block_in_place]).
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::sync::Arc;
+    /// use tokio::sync::Mutex;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let mutex =  Arc::new(Mutex::new(1));
+    ///     let lock = mutex.lock().await;
+    ///
+    ///     let mutex1 = Arc::clone(&mutex);
+    ///     let blocking_task = tokio::task::spawn_blocking(move || {
+    ///         // This shall block until the `lock` is released.
+    ///         let mut n = mutex1.blocking_lock();
+    ///         *n = 2;
+    ///     });
+    ///
+    ///     assert_eq!(*lock, 1);
+    ///     // Release the lock.
+    ///     drop(lock);
+    ///
+    ///     // Await the completion of the blocking task.
+    ///     blocking_task.await.unwrap();
+    ///
+    ///     // Assert uncontended.
+    ///     let n = mutex.try_lock().unwrap();
+    ///     assert_eq!(*n, 2);
+    /// }
+    ///
+    /// ```
+    #[track_caller]
+    #[cfg(feature = "sync")]
+    #[cfg_attr(docsrs, doc(alias = "lock_blocking"))]
+    pub fn blocking_lock(&self) -> MutexGuard<'_, T> {
+        crate::future::block_on(self.lock())
+    }
+
+    /// Blockingly locks this `Mutex`. When the lock has been acquired, function returns an
+    /// [`OwnedMutexGuard`].
+    ///
+    /// This method is identical to [`Mutex::blocking_lock`], except that the returned
+    /// guard references the `Mutex` with an [`Arc`] rather than by borrowing
+    /// it. Therefore, the `Mutex` must be wrapped in an `Arc` to call this
+    /// method, and the guard will live for the `'static` lifetime, as it keeps
+    /// the `Mutex` alive by holding an `Arc`.
+    ///
+    /// # Panics
+    ///
+    /// This function panics if called within an asynchronous execution context.
+    ///
+    ///   - If you find yourself in an asynchronous execution context and needing
+    ///     to call some (synchronous) function which performs one of these
+    ///     `blocking_` operations, then consider wrapping that call inside
+    ///     [`spawn_blocking()`][crate::runtime::Handle::spawn_blocking]
+    ///     (or [`block_in_place()`][crate::task::block_in_place]).
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::sync::Arc;
+    /// use tokio::sync::Mutex;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let mutex =  Arc::new(Mutex::new(1));
+    ///     let lock = mutex.lock().await;
+    ///
+    ///     let mutex1 = Arc::clone(&mutex);
+    ///     let blocking_task = tokio::task::spawn_blocking(move || {
+    ///         // This shall block until the `lock` is released.
+    ///         let mut n = mutex1.blocking_lock_owned();
+    ///         *n = 2;
+    ///     });
+    ///
+    ///     assert_eq!(*lock, 1);
+    ///     // Release the lock.
+    ///     drop(lock);
+    ///
+    ///     // Await the completion of the blocking task.
+    ///     blocking_task.await.unwrap();
+    ///
+    ///     // Assert uncontended.
+    ///     let n = mutex.try_lock().unwrap();
+    ///     assert_eq!(*n, 2);
+    /// }
+    ///
+    /// ```
+    #[track_caller]
+    #[cfg(feature = "sync")]
+    pub fn blocking_lock_owned(self: Arc<Self>) -> OwnedMutexGuard<T> {
+        crate::future::block_on(self.lock_owned())
     }
 
     /// Locks this mutex, causing the current task to yield until the lock has
@@ -334,11 +592,45 @@ impl<T: ?Sized> Mutex<T> {
     ///
     /// [`Arc`]: std::sync::Arc
     pub async fn lock_owned(self: Arc<Self>) -> OwnedMutexGuard<T> {
-        self.acquire().await;
-        OwnedMutexGuard { lock: self }
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let resource_span = self.resource_span.clone();
+
+        let acquire_fut = async {
+            self.acquire().await;
+
+            OwnedMutexGuard {
+                #[cfg(all(tokio_unstable, feature = "tracing"))]
+                resource_span: self.resource_span.clone(),
+                lock: self,
+            }
+        };
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let acquire_fut = trace::async_op(
+            move || acquire_fut,
+            resource_span,
+            "Mutex::lock_owned",
+            "poll",
+            false,
+        );
+
+        #[allow(clippy::let_and_return)] // this lint triggers when disabling tracing
+        let guard = acquire_fut.await;
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        guard.resource_span.in_scope(|| {
+            tracing::trace!(
+                target: "runtime::resource::state_update",
+                locked = true,
+            );
+        });
+
+        guard
     }
 
     async fn acquire(&self) {
+        crate::trace::async_trace_leaf().await;
+
         self.s.acquire(1).await.unwrap_or_else(|_| {
             // The semaphore was closed. but, we never explicitly close it, and
             // we own it exclusively, which means that this can never happen.
@@ -365,7 +657,23 @@ impl<T: ?Sized> Mutex<T> {
     /// ```
     pub fn try_lock(&self) -> Result<MutexGuard<'_, T>, TryLockError> {
         match self.s.try_acquire(1) {
-            Ok(_) => Ok(MutexGuard { lock: self }),
+            Ok(_) => {
+                let guard = MutexGuard {
+                    lock: self,
+                    #[cfg(all(tokio_unstable, feature = "tracing"))]
+                    resource_span: self.resource_span.clone(),
+                };
+
+                #[cfg(all(tokio_unstable, feature = "tracing"))]
+                self.resource_span.in_scope(|| {
+                    tracing::trace!(
+                        target: "runtime::resource::state_update",
+                        locked = true,
+                    );
+                });
+
+                Ok(guard)
+            }
             Err(_) => Err(TryLockError(())),
         }
     }
@@ -420,7 +728,23 @@ impl<T: ?Sized> Mutex<T> {
     /// # }
     pub fn try_lock_owned(self: Arc<Self>) -> Result<OwnedMutexGuard<T>, TryLockError> {
         match self.s.try_acquire(1) {
-            Ok(_) => Ok(OwnedMutexGuard { lock: self }),
+            Ok(_) => {
+                let guard = OwnedMutexGuard {
+                    #[cfg(all(tokio_unstable, feature = "tracing"))]
+                    resource_span: self.resource_span.clone(),
+                    lock: self,
+                };
+
+                #[cfg(all(tokio_unstable, feature = "tracing"))]
+                guard.resource_span.in_scope(|| {
+                    tracing::trace!(
+                        target: "runtime::resource::state_update",
+                        locked = true,
+                    );
+                });
+
+                Ok(guard)
+            }
             Err(_) => Err(TryLockError(())),
         }
     }
@@ -462,14 +786,14 @@ where
     }
 }
 
-impl<T> std::fmt::Debug for Mutex<T>
+impl<T: ?Sized> std::fmt::Debug for Mutex<T>
 where
     T: std::fmt::Debug,
 {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         let mut d = f.debug_struct("Mutex");
         match self.try_lock() {
-            Ok(inner) => d.field("data", &*inner),
+            Ok(inner) => d.field("data", &&*inner),
             Err(_) => d.field("data", &format_args!("<locked>")),
         };
         d.finish()
@@ -479,6 +803,17 @@ where
 // === impl MutexGuard ===
 
 impl<'a, T: ?Sized> MutexGuard<'a, T> {
+    fn skip_drop(self) -> MutexGuardInner<'a, T> {
+        let me = mem::ManuallyDrop::new(self);
+        // SAFETY: This duplicates the `resource_span` and then forgets the
+        // original. In the end, we have not duplicated or forgotten any values.
+        MutexGuardInner {
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: unsafe { std::ptr::read(&me.resource_span) },
+            lock: me.lock,
+        }
+    }
+
     /// Makes a new [`MappedMutexGuard`] for a component of the locked data.
     ///
     /// This operation cannot fail as the [`MutexGuard`] passed in already locked the mutex.
@@ -515,12 +850,13 @@ impl<'a, T: ?Sized> MutexGuard<'a, T> {
         F: FnOnce(&mut T) -> &mut U,
     {
         let data = f(&mut *this) as *mut U;
-        let s = &this.lock.s;
-        mem::forget(this);
+        let inner = this.skip_drop();
         MappedMutexGuard {
-            s,
+            s: &inner.lock.s,
             data,
-            marker: marker::PhantomData,
+            marker: PhantomData,
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: inner.resource_span,
         }
     }
 
@@ -565,19 +901,54 @@ impl<'a, T: ?Sized> MutexGuard<'a, T> {
             Some(data) => data as *mut U,
             None => return Err(this),
         };
-        let s = &this.lock.s;
-        mem::forget(this);
+        let inner = this.skip_drop();
         Ok(MappedMutexGuard {
-            s,
+            s: &inner.lock.s,
             data,
-            marker: marker::PhantomData,
+            marker: PhantomData,
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: inner.resource_span,
         })
     }
+
+    /// Returns a reference to the original `Mutex`.
+    ///
+    /// ```
+    /// use tokio::sync::{Mutex, MutexGuard};
+    ///
+    /// async fn unlock_and_relock<'l>(guard: MutexGuard<'l, u32>) -> MutexGuard<'l, u32> {
+    ///     println!("1. contains: {:?}", *guard);
+    ///     let mutex = MutexGuard::mutex(&guard);
+    ///     drop(guard);
+    ///     let guard = mutex.lock().await;
+    ///     println!("2. contains: {:?}", *guard);
+    ///     guard
+    /// }
+    /// #
+    /// # #[tokio::main]
+    /// # async fn main() {
+    /// #     let mutex = Mutex::new(0u32);
+    /// #     let guard = mutex.lock().await;
+    /// #     let _guard = unlock_and_relock(guard).await;
+    /// # }
+    /// ```
+    #[inline]
+    pub fn mutex(this: &Self) -> &'a Mutex<T> {
+        this.lock
+    }
 }
 
 impl<T: ?Sized> Drop for MutexGuard<'_, T> {
     fn drop(&mut self) {
-        self.lock.s.release(1)
+        self.lock.s.release(1);
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        self.resource_span.in_scope(|| {
+            tracing::trace!(
+                target: "runtime::resource::state_update",
+                locked = false,
+            );
+        });
     }
 }
 
@@ -608,9 +979,156 @@ impl<T: ?Sized + fmt::Display> fmt::Display for MutexGuard<'_, T> {
 
 // === impl OwnedMutexGuard ===
 
+impl<T: ?Sized> OwnedMutexGuard<T> {
+    fn skip_drop(self) -> OwnedMutexGuardInner<T> {
+        let me = mem::ManuallyDrop::new(self);
+        // SAFETY: This duplicates the values in every field of the guard, then
+        // forgets the originals, so in the end no value is duplicated.
+        unsafe {
+            OwnedMutexGuardInner {
+                lock: ptr::read(&me.lock),
+                #[cfg(all(tokio_unstable, feature = "tracing"))]
+                resource_span: ptr::read(&me.resource_span),
+            }
+        }
+    }
+
+    /// Makes a new [`OwnedMappedMutexGuard`] for a component of the locked data.
+    ///
+    /// This operation cannot fail as the [`OwnedMutexGuard`] passed in already locked the mutex.
+    ///
+    /// This is an associated function that needs to be used as `OwnedMutexGuard::map(...)`. A method
+    /// would interfere with methods of the same name on the contents of the locked data.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::sync::{Mutex, OwnedMutexGuard};
+    /// use std::sync::Arc;
+    ///
+    /// #[derive(Debug, Clone, Copy, PartialEq, Eq)]
+    /// struct Foo(u32);
+    ///
+    /// # #[tokio::main]
+    /// # async fn main() {
+    /// let foo = Arc::new(Mutex::new(Foo(1)));
+    ///
+    /// {
+    ///     let mut mapped = OwnedMutexGuard::map(foo.clone().lock_owned().await, |f| &mut f.0);
+    ///     *mapped = 2;
+    /// }
+    ///
+    /// assert_eq!(Foo(2), *foo.lock().await);
+    /// # }
+    /// ```
+    ///
+    /// [`OwnedMutexGuard`]: struct@OwnedMutexGuard
+    /// [`OwnedMappedMutexGuard`]: struct@OwnedMappedMutexGuard
+    #[inline]
+    pub fn map<U, F>(mut this: Self, f: F) -> OwnedMappedMutexGuard<T, U>
+    where
+        F: FnOnce(&mut T) -> &mut U,
+    {
+        let data = f(&mut *this) as *mut U;
+        let inner = this.skip_drop();
+        OwnedMappedMutexGuard {
+            data,
+            lock: inner.lock,
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: inner.resource_span,
+        }
+    }
+
+    /// Attempts to make a new [`OwnedMappedMutexGuard`] for a component of the locked data. The
+    /// original guard is returned if the closure returns `None`.
+    ///
+    /// This operation cannot fail as the [`OwnedMutexGuard`] passed in already locked the mutex.
+    ///
+    /// This is an associated function that needs to be used as `OwnedMutexGuard::try_map(...)`. A
+    /// method would interfere with methods of the same name on the contents of the locked data.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::sync::{Mutex, OwnedMutexGuard};
+    /// use std::sync::Arc;
+    ///
+    /// #[derive(Debug, Clone, Copy, PartialEq, Eq)]
+    /// struct Foo(u32);
+    ///
+    /// # #[tokio::main]
+    /// # async fn main() {
+    /// let foo = Arc::new(Mutex::new(Foo(1)));
+    ///
+    /// {
+    ///     let mut mapped = OwnedMutexGuard::try_map(foo.clone().lock_owned().await, |f| Some(&mut f.0))
+    ///         .expect("should not fail");
+    ///     *mapped = 2;
+    /// }
+    ///
+    /// assert_eq!(Foo(2), *foo.lock().await);
+    /// # }
+    /// ```
+    ///
+    /// [`OwnedMutexGuard`]: struct@OwnedMutexGuard
+    /// [`OwnedMappedMutexGuard`]: struct@OwnedMappedMutexGuard
+    #[inline]
+    pub fn try_map<U, F>(mut this: Self, f: F) -> Result<OwnedMappedMutexGuard<T, U>, Self>
+    where
+        F: FnOnce(&mut T) -> Option<&mut U>,
+    {
+        let data = match f(&mut *this) {
+            Some(data) => data as *mut U,
+            None => return Err(this),
+        };
+        let inner = this.skip_drop();
+        Ok(OwnedMappedMutexGuard {
+            data,
+            lock: inner.lock,
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: inner.resource_span,
+        })
+    }
+
+    /// Returns a reference to the original `Arc<Mutex>`.
+    ///
+    /// ```
+    /// use std::sync::Arc;
+    /// use tokio::sync::{Mutex, OwnedMutexGuard};
+    ///
+    /// async fn unlock_and_relock(guard: OwnedMutexGuard<u32>) -> OwnedMutexGuard<u32> {
+    ///     println!("1. contains: {:?}", *guard);
+    ///     let mutex: Arc<Mutex<u32>> = OwnedMutexGuard::mutex(&guard).clone();
+    ///     drop(guard);
+    ///     let guard = mutex.lock_owned().await;
+    ///     println!("2. contains: {:?}", *guard);
+    ///     guard
+    /// }
+    /// #
+    /// # #[tokio::main]
+    /// # async fn main() {
+    /// #     let mutex = Arc::new(Mutex::new(0u32));
+    /// #     let guard = mutex.lock_owned().await;
+    /// #     unlock_and_relock(guard).await;
+    /// # }
+    /// ```
+    #[inline]
+    pub fn mutex(this: &Self) -> &Arc<Mutex<T>> {
+        &this.lock
+    }
+}
+
 impl<T: ?Sized> Drop for OwnedMutexGuard<T> {
     fn drop(&mut self) {
-        self.lock.s.release(1)
+        self.lock.s.release(1);
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        self.resource_span.in_scope(|| {
+            tracing::trace!(
+                target: "runtime::resource::state_update",
+                locked = false,
+            );
+        });
     }
 }
 
@@ -642,6 +1160,16 @@ impl<T: ?Sized + fmt::Display> fmt::Display for OwnedMutexGuard<T> {
 // === impl MappedMutexGuard ===
 
 impl<'a, T: ?Sized> MappedMutexGuard<'a, T> {
+    fn skip_drop(self) -> MappedMutexGuardInner<'a, T> {
+        let me = mem::ManuallyDrop::new(self);
+        MappedMutexGuardInner {
+            s: me.s,
+            data: me.data,
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: unsafe { std::ptr::read(&me.resource_span) },
+        }
+    }
+
     /// Makes a new [`MappedMutexGuard`] for a component of the locked data.
     ///
     /// This operation cannot fail as the [`MappedMutexGuard`] passed in already locked the mutex.
@@ -656,12 +1184,13 @@ impl<'a, T: ?Sized> MappedMutexGuard<'a, T> {
         F: FnOnce(&mut T) -> &mut U,
     {
         let data = f(&mut *this) as *mut U;
-        let s = this.s;
-        mem::forget(this);
+        let inner = this.skip_drop();
         MappedMutexGuard {
-            s,
+            s: inner.s,
             data,
-            marker: marker::PhantomData,
+            marker: PhantomData,
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: inner.resource_span,
         }
     }
 
@@ -683,19 +1212,28 @@ impl<'a, T: ?Sized> MappedMutexGuard<'a, T> {
             Some(data) => data as *mut U,
             None => return Err(this),
         };
-        let s = this.s;
-        mem::forget(this);
+        let inner = this.skip_drop();
         Ok(MappedMutexGuard {
-            s,
+            s: inner.s,
             data,
-            marker: marker::PhantomData,
+            marker: PhantomData,
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: inner.resource_span,
         })
     }
 }
 
 impl<'a, T: ?Sized> Drop for MappedMutexGuard<'a, T> {
     fn drop(&mut self) {
-        self.s.release(1)
+        self.s.release(1);
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        self.resource_span.in_scope(|| {
+            tracing::trace!(
+                target: "runtime::resource::state_update",
+                locked = false,
+            );
+        });
     }
 }
 
@@ -723,3 +1261,111 @@ impl<'a, T: ?Sized + fmt::Display> fmt::Display for MappedMutexGuard<'a, T> {
         fmt::Display::fmt(&**self, f)
     }
 }
+
+// === impl OwnedMappedMutexGuard ===
+
+impl<T: ?Sized, U: ?Sized> OwnedMappedMutexGuard<T, U> {
+    fn skip_drop(self) -> OwnedMappedMutexGuardInner<T, U> {
+        let me = mem::ManuallyDrop::new(self);
+        // SAFETY: This duplicates the values in every field of the guard, then
+        // forgets the originals, so in the end no value is duplicated.
+        unsafe {
+            OwnedMappedMutexGuardInner {
+                data: me.data,
+                lock: ptr::read(&me.lock),
+                #[cfg(all(tokio_unstable, feature = "tracing"))]
+                resource_span: ptr::read(&me.resource_span),
+            }
+        }
+    }
+
+    /// Makes a new [`OwnedMappedMutexGuard`] for a component of the locked data.
+    ///
+    /// This operation cannot fail as the [`OwnedMappedMutexGuard`] passed in already locked the mutex.
+    ///
+    /// This is an associated function that needs to be used as `OwnedMappedMutexGuard::map(...)`. A method
+    /// would interfere with methods of the same name on the contents of the locked data.
+    ///
+    /// [`OwnedMappedMutexGuard`]: struct@OwnedMappedMutexGuard
+    #[inline]
+    pub fn map<S, F>(mut this: Self, f: F) -> OwnedMappedMutexGuard<T, S>
+    where
+        F: FnOnce(&mut U) -> &mut S,
+    {
+        let data = f(&mut *this) as *mut S;
+        let inner = this.skip_drop();
+        OwnedMappedMutexGuard {
+            data,
+            lock: inner.lock,
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: inner.resource_span,
+        }
+    }
+
+    /// Attempts to make a new [`OwnedMappedMutexGuard`] for a component of the locked data. The
+    /// original guard is returned if the closure returns `None`.
+    ///
+    /// This operation cannot fail as the [`OwnedMutexGuard`] passed in already locked the mutex.
+    ///
+    /// This is an associated function that needs to be used as `OwnedMutexGuard::try_map(...)`. A
+    /// method would interfere with methods of the same name on the contents of the locked data.
+    ///
+    /// [`OwnedMutexGuard`]: struct@OwnedMutexGuard
+    /// [`OwnedMappedMutexGuard`]: struct@OwnedMappedMutexGuard
+    #[inline]
+    pub fn try_map<S, F>(mut this: Self, f: F) -> Result<OwnedMappedMutexGuard<T, S>, Self>
+    where
+        F: FnOnce(&mut U) -> Option<&mut S>,
+    {
+        let data = match f(&mut *this) {
+            Some(data) => data as *mut S,
+            None => return Err(this),
+        };
+        let inner = this.skip_drop();
+        Ok(OwnedMappedMutexGuard {
+            data,
+            lock: inner.lock,
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: inner.resource_span,
+        })
+    }
+}
+
+impl<T: ?Sized, U: ?Sized> Drop for OwnedMappedMutexGuard<T, U> {
+    fn drop(&mut self) {
+        self.lock.s.release(1);
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        self.resource_span.in_scope(|| {
+            tracing::trace!(
+                target: "runtime::resource::state_update",
+                locked = false,
+            );
+        });
+    }
+}
+
+impl<T: ?Sized, U: ?Sized> Deref for OwnedMappedMutexGuard<T, U> {
+    type Target = U;
+    fn deref(&self) -> &Self::Target {
+        unsafe { &*self.data }
+    }
+}
+
+impl<T: ?Sized, U: ?Sized> DerefMut for OwnedMappedMutexGuard<T, U> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        unsafe { &mut *self.data }
+    }
+}
+
+impl<T: ?Sized, U: ?Sized + fmt::Debug> fmt::Debug for OwnedMappedMutexGuard<T, U> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Debug::fmt(&**self, f)
+    }
+}
+
+impl<T: ?Sized, U: ?Sized + fmt::Display> fmt::Display for OwnedMappedMutexGuard<T, U> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt(&**self, f)
+    }
+}
diff --git a/vendor/tokio/src/sync/notify.rs b/vendor/tokio/src/sync/notify.rs
index af7b9423a..0f104b71a 100644
--- a/vendor/tokio/src/sync/notify.rs
+++ b/vendor/tokio/src/sync/notify.rs
@@ -5,42 +5,46 @@
 // triggers this warning but it is safe to ignore in this case.
 #![cfg_attr(not(feature = "sync"), allow(unreachable_pub, dead_code))]
 
+use crate::loom::cell::UnsafeCell;
 use crate::loom::sync::atomic::AtomicUsize;
 use crate::loom::sync::Mutex;
-use crate::util::linked_list::{self, LinkedList};
+use crate::util::linked_list::{self, GuardedLinkedList, LinkedList};
+use crate::util::WakeList;
 
-use std::cell::UnsafeCell;
 use std::future::Future;
 use std::marker::PhantomPinned;
+use std::panic::{RefUnwindSafe, UnwindSafe};
 use std::pin::Pin;
 use std::ptr::NonNull;
-use std::sync::atomic::Ordering::SeqCst;
+use std::sync::atomic::Ordering::{self, Acquire, Relaxed, Release, SeqCst};
 use std::task::{Context, Poll, Waker};
 
 type WaitList = LinkedList<Waiter, <Waiter as linked_list::Link>::Target>;
+type GuardedWaitList = GuardedLinkedList<Waiter, <Waiter as linked_list::Link>::Target>;
 
-/// Notify a single task to wake up.
+/// Notifies a single task to wake up.
 ///
 /// `Notify` provides a basic mechanism to notify a single task of an event.
 /// `Notify` itself does not carry any data. Instead, it is to be used to signal
 /// another task to perform an operation.
 ///
-/// `Notify` can be thought of as a [`Semaphore`] starting with 0 permits.
-/// [`notified().await`] waits for a permit to become available, and [`notify_one()`]
-/// sets a permit **if there currently are no available permits**.
+/// A `Notify` can be thought of as a [`Semaphore`] starting with 0 permits. The
+/// [`notified().await`] method waits for a permit to become available, and
+/// [`notify_one()`] sets a permit **if there currently are no available
+/// permits**.
 ///
 /// The synchronization details of `Notify` are similar to
 /// [`thread::park`][park] and [`Thread::unpark`][unpark] from std. A [`Notify`]
 /// value contains a single permit. [`notified().await`] waits for the permit to
-/// be made available, consumes the permit, and resumes.  [`notify_one()`] sets the
-/// permit, waking a pending task if there is one.
+/// be made available, consumes the permit, and resumes.  [`notify_one()`] sets
+/// the permit, waking a pending task if there is one.
 ///
-/// If `notify_one()` is called **before** `notified().await`, then the next call to
-/// `notified().await` will complete immediately, consuming the permit. Any
-/// subsequent calls to `notified().await` will wait for a new permit.
+/// If `notify_one()` is called **before** `notified().await`, then the next
+/// call to `notified().await` will complete immediately, consuming the permit.
+/// Any subsequent calls to `notified().await` will wait for a new permit.
 ///
-/// If `notify_one()` is called **multiple** times before `notified().await`, only a
-/// **single** permit is stored. The next call to `notified().await` will
+/// If `notify_one()` is called **multiple** times before `notified().await`,
+/// only a **single** permit is stored. The next call to `notified().await` will
 /// complete immediately, but the one after will wait for a new permit.
 ///
 /// # Examples
@@ -56,17 +60,24 @@ type WaitList = LinkedList<Waiter, <Waiter as linked_list::Link>::Target>;
 ///     let notify = Arc::new(Notify::new());
 ///     let notify2 = notify.clone();
 ///
-///     tokio::spawn(async move {
+///     let handle = tokio::spawn(async move {
 ///         notify2.notified().await;
 ///         println!("received notification");
 ///     });
 ///
 ///     println!("sending notification");
 ///     notify.notify_one();
+///
+///     // Wait for task to receive notification.
+///     handle.await.unwrap();
 /// }
 /// ```
 ///
-/// Unbound mpsc channel.
+/// Unbound multi-producer single-consumer (mpsc) channel.
+///
+/// No wakeups can be lost when using this channel because the call to
+/// `notify_one()` will store a permit in the `Notify`, which the following call
+/// to `notified()` will consume.
 ///
 /// ```
 /// use tokio::sync::Notify;
@@ -88,6 +99,8 @@ type WaitList = LinkedList<Waiter, <Waiter as linked_list::Link>::Target>;
 ///         self.notify.notify_one();
 ///     }
 ///
+///     // This is a single-consumer channel, so several concurrent calls to
+///     // `recv` are not allowed.
 ///     pub async fn recv(&self) -> T {
 ///         loop {
 ///             // Drain values
@@ -102,45 +115,250 @@ type WaitList = LinkedList<Waiter, <Waiter as linked_list::Link>::Target>;
 /// }
 /// ```
 ///
+/// Unbound multi-producer multi-consumer (mpmc) channel.
+///
+/// The call to [`enable`] is important because otherwise if you have two
+/// calls to `recv` and two calls to `send` in parallel, the following could
+/// happen:
+///
+///  1. Both calls to `try_recv` return `None`.
+///  2. Both new elements are added to the vector.
+///  3. The `notify_one` method is called twice, adding only a single
+///     permit to the `Notify`.
+///  4. Both calls to `recv` reach the `Notified` future. One of them
+///     consumes the permit, and the other sleeps forever.
+///
+/// By adding the `Notified` futures to the list by calling `enable` before
+/// `try_recv`, the `notify_one` calls in step three would remove the
+/// futures from the list and mark them notified instead of adding a permit
+/// to the `Notify`. This ensures that both futures are woken.
+///
+/// Notice that this failure can only happen if there are two concurrent calls
+/// to `recv`. This is why the mpsc example above does not require a call to
+/// `enable`.
+///
+/// ```
+/// use tokio::sync::Notify;
+///
+/// use std::collections::VecDeque;
+/// use std::sync::Mutex;
+///
+/// struct Channel<T> {
+///     messages: Mutex<VecDeque<T>>,
+///     notify_on_sent: Notify,
+/// }
+///
+/// impl<T> Channel<T> {
+///     pub fn send(&self, msg: T) {
+///         let mut locked_queue = self.messages.lock().unwrap();
+///         locked_queue.push_back(msg);
+///         drop(locked_queue);
+///
+///         // Send a notification to one of the calls currently
+///         // waiting in a call to `recv`.
+///         self.notify_on_sent.notify_one();
+///     }
+///
+///     pub fn try_recv(&self) -> Option<T> {
+///         let mut locked_queue = self.messages.lock().unwrap();
+///         locked_queue.pop_front()
+///     }
+///
+///     pub async fn recv(&self) -> T {
+///         let future = self.notify_on_sent.notified();
+///         tokio::pin!(future);
+///
+///         loop {
+///             // Make sure that no wakeup is lost if we get
+///             // `None` from `try_recv`.
+///             future.as_mut().enable();
+///
+///             if let Some(msg) = self.try_recv() {
+///                 return msg;
+///             }
+///
+///             // Wait for a call to `notify_one`.
+///             //
+///             // This uses `.as_mut()` to avoid consuming the future,
+///             // which lets us call `Pin::set` below.
+///             future.as_mut().await;
+///
+///             // Reset the future in case another call to
+///             // `try_recv` got the message before us.
+///             future.set(self.notify_on_sent.notified());
+///         }
+///     }
+/// }
+/// ```
+///
 /// [park]: std::thread::park
 /// [unpark]: std::thread::Thread::unpark
 /// [`notified().await`]: Notify::notified()
 /// [`notify_one()`]: Notify::notify_one()
+/// [`enable`]: Notified::enable()
 /// [`Semaphore`]: crate::sync::Semaphore
 #[derive(Debug)]
 pub struct Notify {
-    // This uses 2 bits to store one of `EMPTY`,
+    // `state` uses 2 bits to store one of `EMPTY`,
     // `WAITING` or `NOTIFIED`. The rest of the bits
     // are used to store the number of times `notify_waiters`
     // was called.
+    //
+    // Throughout the code there are two assumptions:
+    // - state can be transitioned *from* `WAITING` only if
+    //   `waiters` lock is held
+    // - number of times `notify_waiters` was called can
+    //   be modified only if `waiters` lock is held
     state: AtomicUsize,
     waiters: Mutex<WaitList>,
 }
 
-#[derive(Debug, Clone, Copy)]
-enum NotificationType {
-    // Notification triggered by calling `notify_waiters`
-    AllWaiters,
-    // Notification triggered by calling `notify_one`
-    OneWaiter,
-}
-
 #[derive(Debug)]
 struct Waiter {
-    /// Intrusive linked-list pointers
+    /// Intrusive linked-list pointers.
     pointers: linked_list::Pointers<Waiter>,
 
-    /// Waiting task's waker
-    waker: Option<Waker>,
+    /// Waiting task's waker. Depending on the value of `notification`,
+    /// this field is either protected by the `waiters` lock in
+    /// `Notify`, or it is exclusively owned by the enclosing `Waiter`.
+    waker: UnsafeCell<Option<Waker>>,
 
-    /// `true` if the notification has been assigned to this waiter.
-    notified: Option<NotificationType>,
+    /// Notification for this waiter.
+    /// * if it's `None`, then `waker` is protected by the `waiters` lock.
+    /// * if it's `Some`, then `waker` is exclusively owned by the
+    ///   enclosing `Waiter` and can be accessed without locking.
+    notification: AtomicNotification,
 
     /// Should not be `Unpin`.
     _p: PhantomPinned,
 }
 
-/// Future returned from [`Notify::notified()`]
+impl Waiter {
+    fn new() -> Waiter {
+        Waiter {
+            pointers: linked_list::Pointers::new(),
+            waker: UnsafeCell::new(None),
+            notification: AtomicNotification::none(),
+            _p: PhantomPinned,
+        }
+    }
+}
+
+generate_addr_of_methods! {
+    impl<> Waiter {
+        unsafe fn addr_of_pointers(self: NonNull<Self>) -> NonNull<linked_list::Pointers<Waiter>> {
+            &self.pointers
+        }
+    }
+}
+
+// No notification.
+const NOTIFICATION_NONE: usize = 0;
+
+// Notification type used by `notify_one`.
+const NOTIFICATION_ONE: usize = 1;
+
+// Notification type used by `notify_waiters`.
+const NOTIFICATION_ALL: usize = 2;
+
+/// Notification for a `Waiter`.
+/// This struct is equivalent to `Option<Notification>`, but uses
+/// `AtomicUsize` inside for atomic operations.
+#[derive(Debug)]
+struct AtomicNotification(AtomicUsize);
+
+impl AtomicNotification {
+    fn none() -> Self {
+        AtomicNotification(AtomicUsize::new(NOTIFICATION_NONE))
+    }
+
+    /// Store-release a notification.
+    /// This method should be called exactly once.
+    fn store_release(&self, notification: Notification) {
+        self.0.store(notification as usize, Release);
+    }
+
+    fn load(&self, ordering: Ordering) -> Option<Notification> {
+        match self.0.load(ordering) {
+            NOTIFICATION_NONE => None,
+            NOTIFICATION_ONE => Some(Notification::One),
+            NOTIFICATION_ALL => Some(Notification::All),
+            _ => unreachable!(),
+        }
+    }
+
+    /// Clears the notification.
+    /// This method is used by a `Notified` future to consume the
+    /// notification. It uses relaxed ordering and should be only
+    /// used once the atomic notification is no longer shared.
+    fn clear(&self) {
+        self.0.store(NOTIFICATION_NONE, Relaxed);
+    }
+}
+
+#[derive(Debug, PartialEq, Eq)]
+#[repr(usize)]
+enum Notification {
+    One = NOTIFICATION_ONE,
+    All = NOTIFICATION_ALL,
+}
+
+/// List used in `Notify::notify_waiters`. It wraps a guarded linked list
+/// and gates the access to it on `notify.waiters` mutex. It also empties
+/// the list on drop.
+struct NotifyWaitersList<'a> {
+    list: GuardedWaitList,
+    is_empty: bool,
+    notify: &'a Notify,
+}
+
+impl<'a> NotifyWaitersList<'a> {
+    fn new(
+        unguarded_list: WaitList,
+        guard: Pin<&'a Waiter>,
+        notify: &'a Notify,
+    ) -> NotifyWaitersList<'a> {
+        let guard_ptr = NonNull::from(guard.get_ref());
+        let list = unguarded_list.into_guarded(guard_ptr);
+        NotifyWaitersList {
+            list,
+            is_empty: false,
+            notify,
+        }
+    }
+
+    /// Removes the last element from the guarded list. Modifying this list
+    /// requires an exclusive access to the main list in `Notify`.
+    fn pop_back_locked(&mut self, _waiters: &mut WaitList) -> Option<NonNull<Waiter>> {
+        let result = self.list.pop_back();
+        if result.is_none() {
+            // Save information about emptiness to avoid waiting for lock
+            // in the destructor.
+            self.is_empty = true;
+        }
+        result
+    }
+}
+
+impl Drop for NotifyWaitersList<'_> {
+    fn drop(&mut self) {
+        // If the list is not empty, we unlink all waiters from it.
+        // We do not wake the waiters to avoid double panics.
+        if !self.is_empty {
+            let _lock_guard = self.notify.waiters.lock();
+            while let Some(waiter) = self.list.pop_back() {
+                // Safety: we never make mutable references to waiters.
+                let waiter = unsafe { waiter.as_ref() };
+                waiter.notification.store_release(Notification::All);
+            }
+        }
+    }
+}
+
+/// Future returned from [`Notify::notified()`].
+///
+/// This future is fused, so once it has completed, any future calls to poll
+/// will immediately return `Poll::Ready`.
 #[derive(Debug)]
 pub struct Notified<'a> {
     /// The `Notify` being received on.
@@ -149,8 +367,11 @@ pub struct Notified<'a> {
     /// The current state of the receiving process.
     state: State,
 
+    /// Number of calls to `notify_waiters` at the time of creation.
+    notify_waiters_calls: usize,
+
     /// Entry in the waiter `LinkedList`.
-    waiter: UnsafeCell<Waiter>,
+    waiter: Waiter,
 }
 
 unsafe impl<'a> Send for Notified<'a> {}
@@ -158,7 +379,7 @@ unsafe impl<'a> Sync for Notified<'a> {}
 
 #[derive(Debug)]
 enum State {
-    Init(usize),
+    Init,
     Waiting,
     Done,
 }
@@ -167,13 +388,13 @@ const NOTIFY_WAITERS_SHIFT: usize = 2;
 const STATE_MASK: usize = (1 << NOTIFY_WAITERS_SHIFT) - 1;
 const NOTIFY_WAITERS_CALLS_MASK: usize = !STATE_MASK;
 
-/// Initial "idle" state
+/// Initial "idle" state.
 const EMPTY: usize = 0;
 
 /// One or more threads are currently waiting to be notified.
 const WAITING: usize = 1;
 
-/// Pending notification
+/// Pending notification.
 const NOTIFIED: usize = 2;
 
 fn set_state(data: usize, state: usize) -> usize {
@@ -244,7 +465,16 @@ impl Notify {
     /// immediately, consuming that permit. Otherwise, `notified().await` waits
     /// for a permit to be made available by the next call to `notify_one()`.
     ///
+    /// The `Notified` future is not guaranteed to receive wakeups from calls to
+    /// `notify_one()` if it has not yet been polled. See the documentation for
+    /// [`Notified::enable()`] for more details.
+    ///
+    /// The `Notified` future is guaranteed to receive wakeups from
+    /// `notify_waiters()` as soon as it has been created, even if it has not
+    /// yet been polled.
+    ///
     /// [`notify_one()`]: Notify::notify_one
+    /// [`Notified::enable()`]: Notified::enable
     ///
     /// # Cancel safety
     ///
@@ -274,21 +504,17 @@ impl Notify {
     /// ```
     pub fn notified(&self) -> Notified<'_> {
         // we load the number of times notify_waiters
-        // was called and store that in our initial state
+        // was called and store that in the future.
         let state = self.state.load(SeqCst);
         Notified {
             notify: self,
-            state: State::Init(state >> NOTIFY_WAITERS_SHIFT),
-            waiter: UnsafeCell::new(Waiter {
-                pointers: linked_list::Pointers::new(),
-                waker: None,
-                notified: None,
-                _p: PhantomPinned,
-            }),
+            state: State::Init,
+            notify_waiters_calls: get_num_notify_waiters_calls(state),
+            waiter: Waiter::new(),
         }
     }
 
-    /// Notifies a waiting task
+    /// Notifies a waiting task.
     ///
     /// If a task is currently waiting, that task is notified. Otherwise, a
     /// permit is stored in this `Notify` value and the **next** call to
@@ -358,7 +584,7 @@ impl Notify {
         }
     }
 
-    /// Notifies all waiting tasks
+    /// Notifies all waiting tasks.
     ///
     /// If a task is currently waiting, that task is notified. Unlike with
     /// `notify_one()`, no permit is stored to be used by the next call to
@@ -391,43 +617,56 @@ impl Notify {
     /// }
     /// ```
     pub fn notify_waiters(&self) {
-        const NUM_WAKERS: usize = 32;
-
-        let mut wakers: [Option<Waker>; NUM_WAKERS] = Default::default();
-        let mut curr_waker = 0;
-
-        // There are waiters, the lock must be acquired to notify.
         let mut waiters = self.waiters.lock();
 
-        // The state must be reloaded while the lock is held. The state may only
+        // The state must be loaded while the lock is held. The state may only
         // transition out of WAITING while the lock is held.
         let curr = self.state.load(SeqCst);
 
-        if let EMPTY | NOTIFIED = get_state(curr) {
+        if matches!(get_state(curr), EMPTY | NOTIFIED) {
             // There are no waiting tasks. All we need to do is increment the
             // number of times this method was called.
             atomic_inc_num_notify_waiters_calls(&self.state);
             return;
         }
 
-        // At this point, it is guaranteed that the state will not
-        // concurrently change, as holding the lock is required to
-        // transition **out** of `WAITING`.
+        // Increment the number of times this method was called
+        // and transition to empty.
+        let new_state = set_state(inc_num_notify_waiters_calls(curr), EMPTY);
+        self.state.store(new_state, SeqCst);
+
+        // It is critical for `GuardedLinkedList` safety that the guard node is
+        // pinned in memory and is not dropped until the guarded list is dropped.
+        let guard = Waiter::new();
+        pin!(guard);
+
+        // We move all waiters to a secondary list. It uses a `GuardedLinkedList`
+        // underneath to allow every waiter to safely remove itself from it.
+        //
+        // * This list will be still guarded by the `waiters` lock.
+        //   `NotifyWaitersList` wrapper makes sure we hold the lock to modify it.
+        // * This wrapper will empty the list on drop. It is critical for safety
+        //   that we will not leave any list entry with a pointer to the local
+        //   guard node after this function returns / panics.
+        let mut list = NotifyWaitersList::new(std::mem::take(&mut *waiters), guard.as_ref(), self);
+
+        let mut wakers = WakeList::new();
         'outer: loop {
-            while curr_waker < NUM_WAKERS {
-                match waiters.pop_back() {
-                    Some(mut waiter) => {
-                        // Safety: `waiters` lock is still held.
-                        let waiter = unsafe { waiter.as_mut() };
-
-                        assert!(waiter.notified.is_none());
-
-                        waiter.notified = Some(NotificationType::AllWaiters);
-
-                        if let Some(waker) = waiter.waker.take() {
-                            wakers[curr_waker] = Some(waker);
-                            curr_waker += 1;
+            while wakers.can_push() {
+                match list.pop_back_locked(&mut waiters) {
+                    Some(waiter) => {
+                        // Safety: we never make mutable references to waiters.
+                        let waiter = unsafe { waiter.as_ref() };
+
+                        // Safety: we hold the lock, so we can access the waker.
+                        if let Some(waker) =
+                            unsafe { waiter.waker.with_mut(|waker| (*waker).take()) }
+                        {
+                            wakers.push(waker);
                         }
+
+                        // This waiter is unlinked and will not be shared ever again, release it.
+                        waiter.notification.store_release(Notification::All);
                     }
                     None => {
                         break 'outer;
@@ -435,30 +674,21 @@ impl Notify {
                 }
             }
 
+            // Release the lock before notifying.
             drop(waiters);
 
-            for waker in wakers.iter_mut().take(curr_waker) {
-                waker.take().unwrap().wake();
-            }
-
-            curr_waker = 0;
+            // One of the wakers may panic, but the remaining waiters will still
+            // be unlinked from the list in `NotifyWaitersList` destructor.
+            wakers.wake_all();
 
             // Acquire the lock again.
             waiters = self.waiters.lock();
         }
 
-        // All waiters will be notified, the state must be transitioned to
-        // `EMPTY`. As transitioning **from** `WAITING` requires the lock to be
-        // held, a `store` is sufficient.
-        let new = set_state(inc_num_notify_waiters_calls(curr), EMPTY);
-        self.state.store(new, SeqCst);
-
         // Release the lock before notifying
         drop(waiters);
 
-        for waker in wakers.iter_mut().take(curr_waker) {
-            waker.take().unwrap().wake();
-        }
+        wakers.wake_all();
     }
 }
 
@@ -468,6 +698,9 @@ impl Default for Notify {
     }
 }
 
+impl UnwindSafe for Notify {}
+impl RefUnwindSafe for Notify {}
+
 fn notify_locked(waiters: &mut WaitList, state: &AtomicUsize, curr: usize) -> Option<Waker> {
     loop {
         match get_state(curr) {
@@ -490,15 +723,16 @@ fn notify_locked(waiters: &mut WaitList, state: &AtomicUsize, curr: usize) -> Op
                 // transition **out** of `WAITING`.
                 //
                 // Get a pending waiter
-                let mut waiter = waiters.pop_back().unwrap();
+                let waiter = waiters.pop_back().unwrap();
 
-                // Safety: `waiters` lock is still held.
-                let waiter = unsafe { waiter.as_mut() };
+                // Safety: we never make mutable references to waiters.
+                let waiter = unsafe { waiter.as_ref() };
 
-                assert!(waiter.notified.is_none());
+                // Safety: we hold the lock, so we can access the waker.
+                let waker = unsafe { waiter.waker.with_mut(|waker| (*waker).take()) };
 
-                waiter.notified = Some(NotificationType::OneWaiter);
-                let waker = waiter.waker.take();
+                // This waiter is unlinked and will not be shared ever again, release it.
+                waiter.notification.store_release(Notification::One);
 
                 if waiters.is_empty() {
                     // As this the **final** waiter in the list, the state
@@ -518,32 +752,142 @@ fn notify_locked(waiters: &mut WaitList, state: &AtomicUsize, curr: usize) -> Op
 // ===== impl Notified =====
 
 impl Notified<'_> {
+    /// Adds this future to the list of futures that are ready to receive
+    /// wakeups from calls to [`notify_one`].
+    ///
+    /// Polling the future also adds it to the list, so this method should only
+    /// be used if you want to add the future to the list before the first call
+    /// to `poll`. (In fact, this method is equivalent to calling `poll` except
+    /// that no `Waker` is registered.)
+    ///
+    /// This has no effect on notifications sent using [`notify_waiters`], which
+    /// are received as long as they happen after the creation of the `Notified`
+    /// regardless of whether `enable` or `poll` has been called.
+    ///
+    /// This method returns true if the `Notified` is ready. This happens in the
+    /// following situations:
+    ///
+    ///  1. The `notify_waiters` method was called between the creation of the
+    ///     `Notified` and the call to this method.
+    ///  2. This is the first call to `enable` or `poll` on this future, and the
+    ///     `Notify` was holding a permit from a previous call to `notify_one`.
+    ///     The call consumes the permit in that case.
+    ///  3. The future has previously been enabled or polled, and it has since
+    ///     then been marked ready by either consuming a permit from the
+    ///     `Notify`, or by a call to `notify_one` or `notify_waiters` that
+    ///     removed it from the list of futures ready to receive wakeups.
+    ///
+    /// If this method returns true, any future calls to poll on the same future
+    /// will immediately return `Poll::Ready`.
+    ///
+    /// # Examples
+    ///
+    /// Unbound multi-producer multi-consumer (mpmc) channel.
+    ///
+    /// The call to `enable` is important because otherwise if you have two
+    /// calls to `recv` and two calls to `send` in parallel, the following could
+    /// happen:
+    ///
+    ///  1. Both calls to `try_recv` return `None`.
+    ///  2. Both new elements are added to the vector.
+    ///  3. The `notify_one` method is called twice, adding only a single
+    ///     permit to the `Notify`.
+    ///  4. Both calls to `recv` reach the `Notified` future. One of them
+    ///     consumes the permit, and the other sleeps forever.
+    ///
+    /// By adding the `Notified` futures to the list by calling `enable` before
+    /// `try_recv`, the `notify_one` calls in step three would remove the
+    /// futures from the list and mark them notified instead of adding a permit
+    /// to the `Notify`. This ensures that both futures are woken.
+    ///
+    /// ```
+    /// use tokio::sync::Notify;
+    ///
+    /// use std::collections::VecDeque;
+    /// use std::sync::Mutex;
+    ///
+    /// struct Channel<T> {
+    ///     messages: Mutex<VecDeque<T>>,
+    ///     notify_on_sent: Notify,
+    /// }
+    ///
+    /// impl<T> Channel<T> {
+    ///     pub fn send(&self, msg: T) {
+    ///         let mut locked_queue = self.messages.lock().unwrap();
+    ///         locked_queue.push_back(msg);
+    ///         drop(locked_queue);
+    ///
+    ///         // Send a notification to one of the calls currently
+    ///         // waiting in a call to `recv`.
+    ///         self.notify_on_sent.notify_one();
+    ///     }
+    ///
+    ///     pub fn try_recv(&self) -> Option<T> {
+    ///         let mut locked_queue = self.messages.lock().unwrap();
+    ///         locked_queue.pop_front()
+    ///     }
+    ///
+    ///     pub async fn recv(&self) -> T {
+    ///         let future = self.notify_on_sent.notified();
+    ///         tokio::pin!(future);
+    ///
+    ///         loop {
+    ///             // Make sure that no wakeup is lost if we get
+    ///             // `None` from `try_recv`.
+    ///             future.as_mut().enable();
+    ///
+    ///             if let Some(msg) = self.try_recv() {
+    ///                 return msg;
+    ///             }
+    ///
+    ///             // Wait for a call to `notify_one`.
+    ///             //
+    ///             // This uses `.as_mut()` to avoid consuming the future,
+    ///             // which lets us call `Pin::set` below.
+    ///             future.as_mut().await;
+    ///
+    ///             // Reset the future in case another call to
+    ///             // `try_recv` got the message before us.
+    ///             future.set(self.notify_on_sent.notified());
+    ///         }
+    ///     }
+    /// }
+    /// ```
+    ///
+    /// [`notify_one`]: Notify::notify_one()
+    /// [`notify_waiters`]: Notify::notify_waiters()
+    pub fn enable(self: Pin<&mut Self>) -> bool {
+        self.poll_notified(None).is_ready()
+    }
+
     /// A custom `project` implementation is used in place of `pin-project-lite`
     /// as a custom drop implementation is needed.
-    fn project(self: Pin<&mut Self>) -> (&Notify, &mut State, &UnsafeCell<Waiter>) {
+    fn project(self: Pin<&mut Self>) -> (&Notify, &mut State, &usize, &Waiter) {
         unsafe {
-            // Safety: both `notify` and `state` are `Unpin`.
+            // Safety: `notify`, `state` and `notify_waiters_calls` are `Unpin`.
 
             is_unpin::<&Notify>();
-            is_unpin::<AtomicUsize>();
+            is_unpin::<State>();
+            is_unpin::<usize>();
 
             let me = self.get_unchecked_mut();
-            (&me.notify, &mut me.state, &me.waiter)
+            (
+                me.notify,
+                &mut me.state,
+                &me.notify_waiters_calls,
+                &me.waiter,
+            )
         }
     }
-}
-
-impl Future for Notified<'_> {
-    type Output = ();
 
-    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<()> {
+    fn poll_notified(self: Pin<&mut Self>, waker: Option<&Waker>) -> Poll<()> {
         use State::*;
 
-        let (notify, state, waiter) = self.project();
+        let (notify, state, notify_waiters_calls, waiter) = self.project();
 
-        loop {
+        'outer_loop: loop {
             match *state {
-                Init(initial_notify_waiters_calls) => {
+                Init => {
                     let curr = notify.state.load(SeqCst);
 
                     // Optimistically try acquiring a pending notification
@@ -557,9 +901,13 @@ impl Future for Notified<'_> {
                     if res.is_ok() {
                         // Acquired the notification
                         *state = Done;
-                        return Poll::Ready(());
+                        continue 'outer_loop;
                     }
 
+                    // Clone the waker before locking, a waker clone can be
+                    // triggering arbitrary code.
+                    let waker = waker.cloned();
+
                     // Acquire the lock and attempt to transition to the waiting
                     // state.
                     let mut waiters = notify.waiters.lock();
@@ -569,9 +917,9 @@ impl Future for Notified<'_> {
 
                     // if notify_waiters has been called after the future
                     // was created, then we are done
-                    if get_num_notify_waiters_calls(curr) != initial_notify_waiters_calls {
+                    if get_num_notify_waiters_calls(curr) != *notify_waiters_calls {
                         *state = Done;
-                        return Poll::Ready(());
+                        continue 'outer_loop;
                     }
 
                     // Transition the state to WAITING.
@@ -607,7 +955,7 @@ impl Future for Notified<'_> {
                                     Ok(_) => {
                                         // Acquired the notification
                                         *state = Done;
-                                        return Poll::Ready(());
+                                        continue 'outer_loop;
                                     }
                                     Err(actual) => {
                                         assert_eq!(get_state(actual), EMPTY);
@@ -619,44 +967,109 @@ impl Future for Notified<'_> {
                         }
                     }
 
-                    // Safety: called while locked.
-                    unsafe {
-                        (*waiter.get()).waker = Some(cx.waker().clone());
+                    let mut old_waker = None;
+                    if waker.is_some() {
+                        // Safety: called while locked.
+                        //
+                        // The use of `old_waiter` here is not necessary, as the field is always
+                        // None when we reach this line.
+                        unsafe {
+                            old_waker =
+                                waiter.waker.with_mut(|v| std::mem::replace(&mut *v, waker));
+                        }
                     }
 
                     // Insert the waiter into the linked list
-                    //
-                    // safety: pointers from `UnsafeCell` are never null.
-                    waiters.push_front(unsafe { NonNull::new_unchecked(waiter.get()) });
+                    waiters.push_front(NonNull::from(waiter));
 
                     *state = Waiting;
 
+                    drop(waiters);
+                    drop(old_waker);
+
                     return Poll::Pending;
                 }
                 Waiting => {
-                    // Currently in the "Waiting" state, implying the caller has
-                    // a waiter stored in the waiter list (guarded by
-                    // `notify.waiters`). In order to access the waker fields,
-                    // we must hold the lock.
+                    #[cfg(tokio_taskdump)]
+                    if let Some(waker) = waker {
+                        let mut ctx = Context::from_waker(waker);
+                        ready!(crate::trace::trace_leaf(&mut ctx));
+                    }
+
+                    if waiter.notification.load(Acquire).is_some() {
+                        // Safety: waiter is already unlinked and will not be shared again,
+                        // so we have an exclusive access to `waker`.
+                        drop(unsafe { waiter.waker.with_mut(|waker| (*waker).take()) });
+
+                        waiter.notification.clear();
+                        *state = Done;
+                        return Poll::Ready(());
+                    }
+
+                    // Our waiter was not notified, implying it is still stored in a waiter
+                    // list (guarded by `notify.waiters`). In order to access the waker
+                    // fields, we must acquire the lock.
+
+                    let mut old_waker = None;
+                    let mut waiters = notify.waiters.lock();
+
+                    // We hold the lock and notifications are set only with the lock held,
+                    // so this can be relaxed, because the happens-before relationship is
+                    // established through the mutex.
+                    if waiter.notification.load(Relaxed).is_some() {
+                        // Safety: waiter is already unlinked and will not be shared again,
+                        // so we have an exclusive access to `waker`.
+                        old_waker = unsafe { waiter.waker.with_mut(|waker| (*waker).take()) };
+
+                        waiter.notification.clear();
+
+                        // Drop the old waker after releasing the lock.
+                        drop(waiters);
+                        drop(old_waker);
 
-                    let waiters = notify.waiters.lock();
+                        *state = Done;
+                        return Poll::Ready(());
+                    }
+
+                    // Load the state with the lock held.
+                    let curr = notify.state.load(SeqCst);
+
+                    if get_num_notify_waiters_calls(curr) != *notify_waiters_calls {
+                        // Before we add a waiter to the list we check if these numbers are
+                        // different while holding the lock. If these numbers are different now,
+                        // it means that there is a call to `notify_waiters` in progress and this
+                        // waiter must be contained by a guarded list used in `notify_waiters`.
+                        // We can treat the waiter as notified and remove it from the list, as
+                        // it would have been notified in the `notify_waiters` call anyways.
 
-                    // Safety: called while locked
-                    let w = unsafe { &mut *waiter.get() };
+                        // Safety: we hold the lock, so we can modify the waker.
+                        old_waker = unsafe { waiter.waker.with_mut(|waker| (*waker).take()) };
 
-                    if w.notified.is_some() {
-                        // Our waker has been notified. Reset the fields and
-                        // remove it from the list.
-                        w.waker = None;
-                        w.notified = None;
+                        // Safety: we hold the lock, so we have an exclusive access to the list.
+                        // The list is used in `notify_waiters`, so it must be guarded.
+                        unsafe { waiters.remove(NonNull::from(waiter)) };
 
                         *state = Done;
                     } else {
-                        // Update the waker, if necessary.
-                        if !w.waker.as_ref().unwrap().will_wake(cx.waker()) {
-                            w.waker = Some(cx.waker().clone());
+                        // Safety: we hold the lock, so we can modify the waker.
+                        unsafe {
+                            waiter.waker.with_mut(|v| {
+                                if let Some(waker) = waker {
+                                    let should_update = match &*v {
+                                        Some(current_waker) => !current_waker.will_wake(waker),
+                                        None => true,
+                                    };
+                                    if should_update {
+                                        old_waker = std::mem::replace(&mut *v, Some(waker.clone()));
+                                    }
+                                }
+                            });
                         }
 
+                        // Drop the old waker after releasing the lock.
+                        drop(waiters);
+                        drop(old_waker);
+
                         return Poll::Pending;
                     }
 
@@ -666,8 +1079,16 @@ impl Future for Notified<'_> {
                     // is helpful to visualize the scope of the critical
                     // section.
                     drop(waiters);
+
+                    // Drop the old waker after releasing the lock.
+                    drop(old_waker);
                 }
                 Done => {
+                    #[cfg(tokio_taskdump)]
+                    if let Some(waker) = waker {
+                        let mut ctx = Context::from_waker(waker);
+                        ready!(crate::trace::trace_leaf(&mut ctx));
+                    }
                     return Poll::Ready(());
                 }
             }
@@ -675,40 +1096,48 @@ impl Future for Notified<'_> {
     }
 }
 
+impl Future for Notified<'_> {
+    type Output = ();
+
+    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<()> {
+        self.poll_notified(Some(cx.waker()))
+    }
+}
+
 impl Drop for Notified<'_> {
     fn drop(&mut self) {
         use State::*;
 
         // Safety: The type only transitions to a "Waiting" state when pinned.
-        let (notify, state, waiter) = unsafe { Pin::new_unchecked(self).project() };
+        let (notify, state, _, waiter) = unsafe { Pin::new_unchecked(self).project() };
 
         // This is where we ensure safety. The `Notified` value is being
         // dropped, which means we must ensure that the waiter entry is no
         // longer stored in the linked list.
-        if let Waiting = *state {
+        if matches!(*state, Waiting) {
             let mut waiters = notify.waiters.lock();
             let mut notify_state = notify.state.load(SeqCst);
 
+            // We hold the lock, so this field is not concurrently accessed by
+            // `notify_*` functions and we can use the relaxed ordering.
+            let notification = waiter.notification.load(Relaxed);
+
             // remove the entry from the list (if not already removed)
             //
-            // safety: the waiter is only added to `waiters` by virtue of it
-            // being the only `LinkedList` available to the type.
-            unsafe { waiters.remove(NonNull::new_unchecked(waiter.get())) };
-
-            if waiters.is_empty() {
-                if let WAITING = get_state(notify_state) {
-                    notify_state = set_state(notify_state, EMPTY);
-                    notify.state.store(notify_state, SeqCst);
-                }
+            // Safety: we hold the lock, so we have an exclusive access to every list the
+            // waiter may be contained in. If the node is not contained in the `waiters`
+            // list, then it is contained by a guarded list used by `notify_waiters`.
+            unsafe { waiters.remove(NonNull::from(waiter)) };
+
+            if waiters.is_empty() && get_state(notify_state) == WAITING {
+                notify_state = set_state(notify_state, EMPTY);
+                notify.state.store(notify_state, SeqCst);
             }
 
             // See if the node was notified but not received. In this case, if
             // the notification was triggered via `notify_one`, it must be sent
             // to the next waiter.
-            //
-            // Safety: with the entry removed from the linked list, there can be
-            // no concurrent access to the entry
-            if let Some(NotificationType::OneWaiter) = unsafe { (*waiter.get()).notified } {
+            if notification == Some(Notification::One) {
                 if let Some(waker) = notify_locked(&mut waiters, &notify.state, notify_state) {
                     drop(waiters);
                     waker.wake();
@@ -733,8 +1162,8 @@ unsafe impl linked_list::Link for Waiter {
         ptr
     }
 
-    unsafe fn pointers(mut target: NonNull<Waiter>) -> NonNull<linked_list::Pointers<Waiter>> {
-        NonNull::from(&mut target.as_mut().pointers)
+    unsafe fn pointers(target: NonNull<Waiter>) -> NonNull<linked_list::Pointers<Waiter>> {
+        Waiter::addr_of_pointers(target)
     }
 }
 
diff --git a/vendor/tokio/src/sync/once_cell.rs b/vendor/tokio/src/sync/once_cell.rs
index ce55d9e35..90ea5cd68 100644
--- a/vendor/tokio/src/sync/once_cell.rs
+++ b/vendor/tokio/src/sync/once_cell.rs
@@ -1,4 +1,4 @@
-use super::Semaphore;
+use super::{Semaphore, SemaphorePermit, TryAcquireError};
 use crate::loom::cell::UnsafeCell;
 use std::error::Error;
 use std::fmt;
@@ -8,15 +8,30 @@ use std::ops::Drop;
 use std::ptr;
 use std::sync::atomic::{AtomicBool, Ordering};
 
-/// A thread-safe cell which can be written to only once.
+// This file contains an implementation of an OnceCell. The principle
+// behind the safety the of the cell is that any thread with an `&OnceCell` may
+// access the `value` field according the following rules:
+//
+//  1. When `value_set` is false, the `value` field may be modified by the
+//     thread holding the permit on the semaphore.
+//  2. When `value_set` is true, the `value` field may be accessed immutably by
+//     any thread.
+//
+// It is an invariant that if the semaphore is closed, then `value_set` is true.
+// The reverse does not necessarily hold — but if not, the semaphore may not
+// have any available permits.
+//
+// A thread with a `&mut OnceCell` may modify the value in any way it wants as
+// long as the invariants are upheld.
+
+/// A thread-safe cell that can be written to only once.
 ///
-/// Provides the functionality to either set the value, in case `OnceCell`
-/// is uninitialized, or get the already initialized value by using an async
-/// function via [`OnceCell::get_or_init`].
-///
-/// [`OnceCell::get_or_init`]: crate::sync::OnceCell::get_or_init
+/// A `OnceCell` is typically used for global variables that need to be
+/// initialized once on first use, but need no further changes. The `OnceCell`
+/// in Tokio allows the initialization procedure to be asynchronous.
 ///
 /// # Examples
+///
 /// ```
 /// use tokio::sync::OnceCell;
 ///
@@ -28,8 +43,28 @@ use std::sync::atomic::{AtomicBool, Ordering};
 ///
 /// #[tokio::main]
 /// async fn main() {
-///     let result1 = ONCE.get_or_init(some_computation).await;
-///     assert_eq!(*result1, 2);
+///     let result = ONCE.get_or_init(some_computation).await;
+///     assert_eq!(*result, 2);
+/// }
+/// ```
+///
+/// It is often useful to write a wrapper method for accessing the value.
+///
+/// ```
+/// use tokio::sync::OnceCell;
+///
+/// static ONCE: OnceCell<u32> = OnceCell::const_new();
+///
+/// async fn get_global_integer() -> &'static u32 {
+///     ONCE.get_or_init(|| async {
+///         1 + 1
+///     }).await
+/// }
+///
+/// #[tokio::main]
+/// async fn main() {
+///     let result = get_global_integer().await;
+///     assert_eq!(*result, 2);
 /// }
 /// ```
 pub struct OnceCell<T> {
@@ -68,10 +103,10 @@ impl<T: Eq> Eq for OnceCell<T> {}
 
 impl<T> Drop for OnceCell<T> {
     fn drop(&mut self) {
-        if self.initialized() {
+        if self.initialized_mut() {
             unsafe {
                 self.value
-                    .with_mut(|ptr| ptr::drop_in_place((&mut *ptr).as_mut_ptr()));
+                    .with_mut(|ptr| ptr::drop_in_place((*ptr).as_mut_ptr()));
             };
         }
     }
@@ -90,7 +125,7 @@ impl<T> From<T> for OnceCell<T> {
 }
 
 impl<T> OnceCell<T> {
-    /// Creates a new uninitialized OnceCell instance.
+    /// Creates a new empty `OnceCell` instance.
     pub fn new() -> Self {
         OnceCell {
             value_set: AtomicBool::new(false),
@@ -99,8 +134,9 @@ impl<T> OnceCell<T> {
         }
     }
 
-    /// Creates a new initialized OnceCell instance if `value` is `Some`, otherwise
-    /// has the same functionality as [`OnceCell::new`].
+    /// Creates a new `OnceCell` that contains the provided value, if any.
+    ///
+    /// If the `Option` is `None`, this is equivalent to `OnceCell::new`.
     ///
     /// [`OnceCell::new`]: crate::sync::OnceCell::new
     pub fn new_with(value: Option<T>) -> Self {
@@ -111,8 +147,31 @@ impl<T> OnceCell<T> {
         }
     }
 
-    /// Creates a new uninitialized OnceCell instance.
-    #[cfg(all(feature = "parking_lot", not(all(loom, test)),))]
+    /// Creates a new empty `OnceCell` instance.
+    ///
+    /// Equivalent to `OnceCell::new`, except that it can be used in static
+    /// variables.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use tokio::sync::OnceCell;
+    ///
+    /// static ONCE: OnceCell<u32> = OnceCell::const_new();
+    ///
+    /// async fn get_global_integer() -> &'static u32 {
+    ///     ONCE.get_or_init(|| async {
+    ///         1 + 1
+    ///     }).await
+    /// }
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let result = get_global_integer().await;
+    ///     assert_eq!(*result, 2);
+    /// }
+    /// ```
+    #[cfg(all(feature = "parking_lot", not(all(loom, test))))]
     #[cfg_attr(docsrs, doc(cfg(feature = "parking_lot")))]
     pub const fn const_new() -> Self {
         OnceCell {
@@ -122,33 +181,48 @@ impl<T> OnceCell<T> {
         }
     }
 
-    /// Whether the value of the OnceCell is set or not.
+    /// Returns `true` if the `OnceCell` currently contains a value, and `false`
+    /// otherwise.
     pub fn initialized(&self) -> bool {
+        // Using acquire ordering so any threads that read a true from this
+        // atomic is able to read the value.
         self.value_set.load(Ordering::Acquire)
     }
 
-    // SAFETY: safe to call only once self.initialized() is true
+    /// Returns `true` if the `OnceCell` currently contains a value, and `false`
+    /// otherwise.
+    fn initialized_mut(&mut self) -> bool {
+        *self.value_set.get_mut()
+    }
+
+    // SAFETY: The OnceCell must not be empty.
     unsafe fn get_unchecked(&self) -> &T {
         &*self.value.with(|ptr| (*ptr).as_ptr())
     }
 
-    // SAFETY: safe to call only once self.initialized() is true. Safe because
-    // because of the mutable reference.
+    // SAFETY: The OnceCell must not be empty.
     unsafe fn get_unchecked_mut(&mut self) -> &mut T {
         &mut *self.value.with_mut(|ptr| (*ptr).as_mut_ptr())
     }
 
-    // SAFETY: safe to call only once a permit on the semaphore has been
-    // acquired
-    unsafe fn set_value(&self, value: T) {
-        self.value.with_mut(|ptr| (*ptr).as_mut_ptr().write(value));
+    fn set_value(&self, value: T, permit: SemaphorePermit<'_>) -> &T {
+        // SAFETY: We are holding the only permit on the semaphore.
+        unsafe {
+            self.value.with_mut(|ptr| (*ptr).as_mut_ptr().write(value));
+        }
+
+        // Using release ordering so any threads that read a true from this
+        // atomic is able to read the value we just stored.
         self.value_set.store(true, Ordering::Release);
         self.semaphore.close();
+        permit.forget();
+
+        // SAFETY: We just initialized the cell.
+        unsafe { self.get_unchecked() }
     }
 
-    /// Tries to get a reference to the value of the OnceCell.
-    ///
-    /// Returns None if the value of the OnceCell hasn't previously been initialized.
+    /// Returns a reference to the value currently stored in the `OnceCell`, or
+    /// `None` if the `OnceCell` is empty.
     pub fn get(&self) -> Option<&T> {
         if self.initialized() {
             Some(unsafe { self.get_unchecked() })
@@ -157,179 +231,165 @@ impl<T> OnceCell<T> {
         }
     }
 
-    /// Tries to return a mutable reference to the value of the cell.
+    /// Returns a mutable reference to the value currently stored in the
+    /// `OnceCell`, or `None` if the `OnceCell` is empty.
     ///
-    /// Returns None if the cell hasn't previously been initialized.
+    /// Since this call borrows the `OnceCell` mutably, it is safe to mutate the
+    /// value inside the `OnceCell` — the mutable borrow statically guarantees
+    /// no other references exist.
     pub fn get_mut(&mut self) -> Option<&mut T> {
-        if self.initialized() {
+        if self.initialized_mut() {
             Some(unsafe { self.get_unchecked_mut() })
         } else {
             None
         }
     }
 
-    /// Sets the value of the OnceCell to the argument value.
+    /// Sets the value of the `OnceCell` to the given value if the `OnceCell` is
+    /// empty.
+    ///
+    /// If the `OnceCell` already has a value, this call will fail with an
+    /// [`SetError::AlreadyInitializedError`].
     ///
-    /// If the value of the OnceCell was already set prior to this call
-    /// then [`SetError::AlreadyInitializedError`] is returned. If another thread
-    /// is initializing the cell while this method is called,
-    /// [`SetError::InitializingError`] is returned. In order to wait
-    /// for an ongoing initialization to finish, call
-    /// [`OnceCell::get_or_init`] instead.
+    /// If the `OnceCell` is empty, but some other task is currently trying to
+    /// set the value, this call will fail with [`SetError::InitializingError`].
     ///
     /// [`SetError::AlreadyInitializedError`]: crate::sync::SetError::AlreadyInitializedError
     /// [`SetError::InitializingError`]: crate::sync::SetError::InitializingError
-    /// ['OnceCell::get_or_init`]: crate::sync::OnceCell::get_or_init
     pub fn set(&self, value: T) -> Result<(), SetError<T>> {
-        if !self.initialized() {
-            // Another thread might be initializing the cell, in which case `try_acquire` will
-            // return an error
-            match self.semaphore.try_acquire() {
-                Ok(_permit) => {
-                    if !self.initialized() {
-                        // SAFETY: There is only one permit on the semaphore, hence only one
-                        // mutable reference is created
-                        unsafe { self.set_value(value) };
-
-                        return Ok(());
-                    } else {
-                        unreachable!(
-                            "acquired the permit after OnceCell value was already initialized."
-                        );
-                    }
-                }
-                _ => {
-                    // Couldn't acquire the permit, look if initializing process is already completed
-                    if !self.initialized() {
-                        return Err(SetError::InitializingError(value));
-                    }
-                }
-            }
+        if self.initialized() {
+            return Err(SetError::AlreadyInitializedError(value));
         }
 
-        Err(SetError::AlreadyInitializedError(value))
+        // Another task might be initializing the cell, in which case
+        // `try_acquire` will return an error. If we succeed to acquire the
+        // permit, then we can set the value.
+        match self.semaphore.try_acquire() {
+            Ok(permit) => {
+                debug_assert!(!self.initialized());
+                self.set_value(value, permit);
+                Ok(())
+            }
+            Err(TryAcquireError::NoPermits) => {
+                // Some other task is holding the permit. That task is
+                // currently trying to initialize the value.
+                Err(SetError::InitializingError(value))
+            }
+            Err(TryAcquireError::Closed) => {
+                // The semaphore was closed. Some other task has initialized
+                // the value.
+                Err(SetError::AlreadyInitializedError(value))
+            }
+        }
     }
 
-    /// Tries to initialize the value of the OnceCell using the async function `f`.
-    /// If the value of the OnceCell was already initialized prior to this call,
-    /// a reference to that initialized value is returned. If some other thread
-    /// initiated the initialization prior to this call and the initialization
-    /// hasn't completed, this call waits until the initialization is finished.
+    /// Gets the value currently in the `OnceCell`, or initialize it with the
+    /// given asynchronous operation.
+    ///
+    /// If some other task is currently working on initializing the `OnceCell`,
+    /// this call will wait for that other task to finish, then return the value
+    /// that the other task produced.
+    ///
+    /// If the provided operation is cancelled or panics, the initialization
+    /// attempt is cancelled. If there are other tasks waiting for the value to
+    /// be initialized, one of them will start another attempt at initializing
+    /// the value.
     ///
-    /// This will deadlock if `f` tries to initialize the cell itself.
+    /// This will deadlock if `f` tries to initialize the cell recursively.
     pub async fn get_or_init<F, Fut>(&self, f: F) -> &T
     where
         F: FnOnce() -> Fut,
         Fut: Future<Output = T>,
     {
+        crate::trace::async_trace_leaf().await;
+
         if self.initialized() {
-            // SAFETY: once the value is initialized, no mutable references are given out, so
-            // we can give out arbitrarily many immutable references
+            // SAFETY: The OnceCell has been fully initialized.
             unsafe { self.get_unchecked() }
         } else {
-            // After acquire().await we have either acquired a permit while self.value
-            // is still uninitialized, or the current thread is awoken after another thread
-            // has initialized the value and closed the semaphore, in which case self.initialized
-            // is true and we don't set the value here
+            // Here we try to acquire the semaphore permit. Holding the permit
+            // will allow us to set the value of the OnceCell, and prevents
+            // other tasks from initializing the OnceCell while we are holding
+            // it.
             match self.semaphore.acquire().await {
-                Ok(_permit) => {
-                    if !self.initialized() {
-                        // If `f()` panics or `select!` is called, this `get_or_init` call
-                        // is aborted and the semaphore permit is dropped.
-                        let value = f().await;
-
-                        // SAFETY: There is only one permit on the semaphore, hence only one
-                        // mutable reference is created
-                        unsafe { self.set_value(value) };
-
-                        // SAFETY: once the value is initialized, no mutable references are given out, so
-                        // we can give out arbitrarily many immutable references
-                        unsafe { self.get_unchecked() }
-                    } else {
-                        unreachable!("acquired semaphore after value was already initialized.");
-                    }
+                Ok(permit) => {
+                    debug_assert!(!self.initialized());
+
+                    // If `f()` panics or `select!` is called, this
+                    // `get_or_init` call is aborted and the semaphore permit is
+                    // dropped.
+                    let value = f().await;
+
+                    self.set_value(value, permit)
                 }
                 Err(_) => {
-                    if self.initialized() {
-                        // SAFETY: once the value is initialized, no mutable references are given out, so
-                        // we can give out arbitrarily many immutable references
-                        unsafe { self.get_unchecked() }
-                    } else {
-                        unreachable!(
-                            "Semaphore closed, but the OnceCell has not been initialized."
-                        );
-                    }
+                    debug_assert!(self.initialized());
+
+                    // SAFETY: The semaphore has been closed. This only happens
+                    // when the OnceCell is fully initialized.
+                    unsafe { self.get_unchecked() }
                 }
             }
         }
     }
 
-    /// Tries to initialize the value of the OnceCell using the async function `f`.
-    /// If the value of the OnceCell was already initialized prior to this call,
-    /// a reference to that initialized value is returned. If some other thread
-    /// initiated the initialization prior to this call and the initialization
-    /// hasn't completed, this call waits until the initialization is finished.
-    /// If the function argument `f` returns an error, `get_or_try_init`
-    /// returns that error, otherwise the result of `f` will be stored in the cell.
+    /// Gets the value currently in the `OnceCell`, or initialize it with the
+    /// given asynchronous operation.
+    ///
+    /// If some other task is currently working on initializing the `OnceCell`,
+    /// this call will wait for that other task to finish, then return the value
+    /// that the other task produced.
     ///
-    /// This will deadlock if `f` tries to initialize the cell itself.
+    /// If the provided operation returns an error, is cancelled or panics, the
+    /// initialization attempt is cancelled. If there are other tasks waiting
+    /// for the value to be initialized, one of them will start another attempt
+    /// at initializing the value.
+    ///
+    /// This will deadlock if `f` tries to initialize the cell recursively.
     pub async fn get_or_try_init<E, F, Fut>(&self, f: F) -> Result<&T, E>
     where
         F: FnOnce() -> Fut,
         Fut: Future<Output = Result<T, E>>,
     {
+        crate::trace::async_trace_leaf().await;
+
         if self.initialized() {
-            // SAFETY: once the value is initialized, no mutable references are given out, so
-            // we can give out arbitrarily many immutable references
+            // SAFETY: The OnceCell has been fully initialized.
             unsafe { Ok(self.get_unchecked()) }
         } else {
-            // After acquire().await we have either acquired a permit while self.value
-            // is still uninitialized, or the current thread is awoken after another thread
-            // has initialized the value and closed the semaphore, in which case self.initialized
-            // is true and we don't set the value here
+            // Here we try to acquire the semaphore permit. Holding the permit
+            // will allow us to set the value of the OnceCell, and prevents
+            // other tasks from initializing the OnceCell while we are holding
+            // it.
             match self.semaphore.acquire().await {
-                Ok(_permit) => {
-                    if !self.initialized() {
-                        // If `f()` panics or `select!` is called, this `get_or_try_init` call
-                        // is aborted and the semaphore permit is dropped.
-                        let value = f().await;
-
-                        match value {
-                            Ok(value) => {
-                                // SAFETY: There is only one permit on the semaphore, hence only one
-                                // mutable reference is created
-                                unsafe { self.set_value(value) };
-
-                                // SAFETY: once the value is initialized, no mutable references are given out, so
-                                // we can give out arbitrarily many immutable references
-                                unsafe { Ok(self.get_unchecked()) }
-                            }
-                            Err(e) => Err(e),
-                        }
-                    } else {
-                        unreachable!("acquired semaphore after value was already initialized.");
+                Ok(permit) => {
+                    debug_assert!(!self.initialized());
+
+                    // If `f()` panics or `select!` is called, this
+                    // `get_or_try_init` call is aborted and the semaphore
+                    // permit is dropped.
+                    let value = f().await;
+
+                    match value {
+                        Ok(value) => Ok(self.set_value(value, permit)),
+                        Err(e) => Err(e),
                     }
                 }
                 Err(_) => {
-                    if self.initialized() {
-                        // SAFETY: once the value is initialized, no mutable references are given out, so
-                        // we can give out arbitrarily many immutable references
-                        unsafe { Ok(self.get_unchecked()) }
-                    } else {
-                        unreachable!(
-                            "Semaphore closed, but the OnceCell has not been initialized."
-                        );
-                    }
+                    debug_assert!(self.initialized());
+
+                    // SAFETY: The semaphore has been closed. This only happens
+                    // when the OnceCell is fully initialized.
+                    unsafe { Ok(self.get_unchecked()) }
                 }
             }
         }
     }
 
-    /// Moves the value out of the cell, destroying the cell in the process.
-    ///
-    /// Returns `None` if the cell is uninitialized.
+    /// Takes the value from the cell, destroying the cell in the process.
+    /// Returns `None` if the cell is empty.
     pub fn into_inner(mut self) -> Option<T> {
-        if self.initialized() {
+        if self.initialized_mut() {
             // Set to uninitialized for the destructor of `OnceCell` to work properly
             *self.value_set.get_mut() = false;
             Some(unsafe { self.value.with(|ptr| ptr::read(ptr).assume_init()) })
@@ -338,20 +398,18 @@ impl<T> OnceCell<T> {
         }
     }
 
-    /// Takes ownership of the current value, leaving the cell uninitialized.
-    ///
-    /// Returns `None` if the cell is uninitialized.
+    /// Takes ownership of the current value, leaving the cell empty.  Returns
+    /// `None` if the cell is empty.
     pub fn take(&mut self) -> Option<T> {
         std::mem::take(self).into_inner()
     }
 }
 
-// Since `get` gives us access to immutable references of the
-// OnceCell, OnceCell can only be Sync if T is Sync, otherwise
-// OnceCell would allow sharing references of !Sync values across
-// threads. We need T to be Send in order for OnceCell to by Sync
-// because we can use `set` on `&OnceCell<T>` to send
-// values (of type T) across threads.
+// Since `get` gives us access to immutable references of the OnceCell, OnceCell
+// can only be Sync if T is Sync, otherwise OnceCell would allow sharing
+// references of !Sync values across threads. We need T to be Send in order for
+// OnceCell to by Sync because we can use `set` on `&OnceCell<T>` to send values
+// (of type T) across threads.
 unsafe impl<T: Sync + Send> Sync for OnceCell<T> {}
 
 // Access to OnceCell's value is guarded by the semaphore permit
@@ -359,20 +417,17 @@ unsafe impl<T: Sync + Send> Sync for OnceCell<T> {}
 // it's safe to send it to another thread
 unsafe impl<T: Send> Send for OnceCell<T> {}
 
-/// Errors that can be returned from [`OnceCell::set`]
+/// Errors that can be returned from [`OnceCell::set`].
 ///
 /// [`OnceCell::set`]: crate::sync::OnceCell::set
-#[derive(Debug, PartialEq)]
+#[derive(Debug, PartialEq, Eq)]
 pub enum SetError<T> {
-    /// Error resulting from [`OnceCell::set`] calls if the cell was previously initialized.
+    /// The cell was already initialized when [`OnceCell::set`] was called.
     ///
     /// [`OnceCell::set`]: crate::sync::OnceCell::set
     AlreadyInitializedError(T),
 
-    /// Error resulting from [`OnceCell::set`] calls when the cell is currently being
-    /// initialized during the calls to that method.
-    ///
-    /// [`OnceCell::set`]: crate::sync::OnceCell::set
+    /// The cell is currently being initialized.
     InitializingError(T),
 }
 
diff --git a/vendor/tokio/src/sync/oneshot.rs b/vendor/tokio/src/sync/oneshot.rs
index cb4649d86..af3cc854f 100644
--- a/vendor/tokio/src/sync/oneshot.rs
+++ b/vendor/tokio/src/sync/oneshot.rs
@@ -9,6 +9,13 @@
 //!
 //! Each handle can be used on separate tasks.
 //!
+//! Since the `send` method is not async, it can be used anywhere. This includes
+//! sending between two runtimes, and using it from non-async code.
+//!
+//! If the [`Receiver`] is closed before receiving a message which has already
+//! been sent, the message will remain in the channel until the receiver is
+//! dropped, at which point the message will be dropped immediately.
+//!
 //! # Examples
 //!
 //! ```
@@ -51,10 +58,76 @@
 //!     }
 //! }
 //! ```
+//!
+//! To use a oneshot channel in a `tokio::select!` loop, add `&mut` in front of
+//! the channel.
+//!
+//! ```
+//! use tokio::sync::oneshot;
+//! use tokio::time::{interval, sleep, Duration};
+//!
+//! #[tokio::main]
+//! # async fn _doc() {}
+//! # #[tokio::main(flavor = "current_thread", start_paused = true)]
+//! async fn main() {
+//!     let (send, mut recv) = oneshot::channel();
+//!     let mut interval = interval(Duration::from_millis(100));
+//!
+//!     # let handle =
+//!     tokio::spawn(async move {
+//!         sleep(Duration::from_secs(1)).await;
+//!         send.send("shut down").unwrap();
+//!     });
+//!
+//!     loop {
+//!         tokio::select! {
+//!             _ = interval.tick() => println!("Another 100ms"),
+//!             msg = &mut recv => {
+//!                 println!("Got message: {}", msg.unwrap());
+//!                 break;
+//!             }
+//!         }
+//!     }
+//!     # handle.await.unwrap();
+//! }
+//! ```
+//!
+//! To use a `Sender` from a destructor, put it in an [`Option`] and call
+//! [`Option::take`].
+//!
+//! ```
+//! use tokio::sync::oneshot;
+//!
+//! struct SendOnDrop {
+//!     sender: Option<oneshot::Sender<&'static str>>,
+//! }
+//! impl Drop for SendOnDrop {
+//!     fn drop(&mut self) {
+//!         if let Some(sender) = self.sender.take() {
+//!             // Using `let _ =` to ignore send errors.
+//!             let _ = sender.send("I got dropped!");
+//!         }
+//!     }
+//! }
+//!
+//! #[tokio::main]
+//! # async fn _doc() {}
+//! # #[tokio::main(flavor = "current_thread")]
+//! async fn main() {
+//!     let (send, recv) = oneshot::channel();
+//!
+//!     let send_on_drop = SendOnDrop { sender: Some(send) };
+//!     drop(send_on_drop);
+//!
+//!     assert_eq!(recv.await, Ok("I got dropped!"));
+//! }
+//! ```
 
 use crate::loom::cell::UnsafeCell;
 use crate::loom::sync::atomic::AtomicUsize;
 use crate::loom::sync::Arc;
+#[cfg(all(tokio_unstable, feature = "tracing"))]
+use crate::util::trace;
 
 use std::fmt;
 use std::future::Future;
@@ -68,16 +141,108 @@ use std::task::{Context, Poll, Waker};
 ///
 /// A pair of both a [`Sender`] and a [`Receiver`]  are created by the
 /// [`channel`](fn@channel) function.
+///
+/// # Examples
+///
+/// ```
+/// use tokio::sync::oneshot;
+///
+/// #[tokio::main]
+/// async fn main() {
+///     let (tx, rx) = oneshot::channel();
+///
+///     tokio::spawn(async move {
+///         if let Err(_) = tx.send(3) {
+///             println!("the receiver dropped");
+///         }
+///     });
+///
+///     match rx.await {
+///         Ok(v) => println!("got = {:?}", v),
+///         Err(_) => println!("the sender dropped"),
+///     }
+/// }
+/// ```
+///
+/// If the sender is dropped without sending, the receiver will fail with
+/// [`error::RecvError`]:
+///
+/// ```
+/// use tokio::sync::oneshot;
+///
+/// #[tokio::main]
+/// async fn main() {
+///     let (tx, rx) = oneshot::channel::<u32>();
+///
+///     tokio::spawn(async move {
+///         drop(tx);
+///     });
+///
+///     match rx.await {
+///         Ok(_) => panic!("This doesn't happen"),
+///         Err(_) => println!("the sender dropped"),
+///     }
+/// }
+/// ```
+///
+/// To use a `Sender` from a destructor, put it in an [`Option`] and call
+/// [`Option::take`].
+///
+/// ```
+/// use tokio::sync::oneshot;
+///
+/// struct SendOnDrop {
+///     sender: Option<oneshot::Sender<&'static str>>,
+/// }
+/// impl Drop for SendOnDrop {
+///     fn drop(&mut self) {
+///         if let Some(sender) = self.sender.take() {
+///             // Using `let _ =` to ignore send errors.
+///             let _ = sender.send("I got dropped!");
+///         }
+///     }
+/// }
+///
+/// #[tokio::main]
+/// # async fn _doc() {}
+/// # #[tokio::main(flavor = "current_thread")]
+/// async fn main() {
+///     let (send, recv) = oneshot::channel();
+///
+///     let send_on_drop = SendOnDrop { sender: Some(send) };
+///     drop(send_on_drop);
+///
+///     assert_eq!(recv.await, Ok("I got dropped!"));
+/// }
+/// ```
+///
+/// [`Option`]: std::option::Option
+/// [`Option::take`]: std::option::Option::take
 #[derive(Debug)]
 pub struct Sender<T> {
     inner: Option<Arc<Inner<T>>>,
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    resource_span: tracing::Span,
 }
 
-/// Receive a value from the associated [`Sender`].
+/// Receives a value from the associated [`Sender`].
 ///
 /// A pair of both a [`Sender`] and a [`Receiver`]  are created by the
 /// [`channel`](fn@channel) function.
 ///
+/// This channel has no `recv` method because the receiver itself implements the
+/// [`Future`] trait. To receive a `Result<T, `[`error::RecvError`]`>`, `.await` the `Receiver` object directly.
+///
+/// The `poll` method on the `Future` trait is allowed to spuriously return
+/// `Poll::Pending` even if the message has been sent. If such a spurious
+/// failure happens, then the caller will be woken when the spurious failure has
+/// been resolved so that the caller can attempt to receive the message again.
+/// Note that receiving such a wakeup does not guarantee that the next call will
+/// succeed — it could fail with another spurious failure. (A spurious failure
+/// does not mean that the message is lost. It is just delayed.)
+///
+/// [`Future`]: trait@std::future::Future
+///
 /// # Examples
 ///
 /// ```
@@ -120,22 +285,63 @@ pub struct Sender<T> {
 ///     }
 /// }
 /// ```
+///
+/// To use a `Receiver` in a `tokio::select!` loop, add `&mut` in front of the
+/// channel.
+///
+/// ```
+/// use tokio::sync::oneshot;
+/// use tokio::time::{interval, sleep, Duration};
+///
+/// #[tokio::main]
+/// # async fn _doc() {}
+/// # #[tokio::main(flavor = "current_thread", start_paused = true)]
+/// async fn main() {
+///     let (send, mut recv) = oneshot::channel();
+///     let mut interval = interval(Duration::from_millis(100));
+///
+///     # let handle =
+///     tokio::spawn(async move {
+///         sleep(Duration::from_secs(1)).await;
+///         send.send("shut down").unwrap();
+///     });
+///
+///     loop {
+///         tokio::select! {
+///             _ = interval.tick() => println!("Another 100ms"),
+///             msg = &mut recv => {
+///                 println!("Got message: {}", msg.unwrap());
+///                 break;
+///             }
+///         }
+///     }
+///     # handle.await.unwrap();
+/// }
+/// ```
 #[derive(Debug)]
 pub struct Receiver<T> {
     inner: Option<Arc<Inner<T>>>,
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    resource_span: tracing::Span,
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    async_op_span: tracing::Span,
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    async_op_poll_span: tracing::Span,
 }
 
 pub mod error {
-    //! Oneshot error types
+    //! Oneshot error types.
 
     use std::fmt;
 
     /// Error returned by the `Future` implementation for `Receiver`.
-    #[derive(Debug, Eq, PartialEq)]
+    ///
+    /// This error is returned by the receiver when the sender is dropped without sending.
+    #[derive(Debug, Eq, PartialEq, Clone)]
     pub struct RecvError(pub(super) ());
 
     /// Error returned by the `try_recv` function on `Receiver`.
-    #[derive(Debug, Eq, PartialEq)]
+    #[derive(Debug, Eq, PartialEq, Clone)]
     pub enum TryRecvError {
         /// The send half of the channel has not yet sent a value.
         Empty,
@@ -171,7 +377,7 @@ pub mod error {
 use self::error::*;
 
 struct Inner<T> {
-    /// Manages the state of the inner cell
+    /// Manages the state of the inner cell.
     state: AtomicUsize,
 
     /// The value. This is set by `Sender` and read by `Receiver`. The state of
@@ -207,21 +413,21 @@ impl Task {
         F: FnOnce(&Waker) -> R,
     {
         self.0.with(|ptr| {
-            let waker: *const Waker = (&*ptr).as_ptr();
+            let waker: *const Waker = (*ptr).as_ptr();
             f(&*waker)
         })
     }
 
     unsafe fn drop_task(&self) {
         self.0.with_mut(|ptr| {
-            let ptr: *mut Waker = (&mut *ptr).as_mut_ptr();
+            let ptr: *mut Waker = (*ptr).as_mut_ptr();
             ptr.drop_in_place();
         });
     }
 
     unsafe fn set_task(&self, cx: &mut Context<'_>) {
         self.0.with_mut(|ptr| {
-            let ptr: *mut Waker = (&mut *ptr).as_mut_ptr();
+            let ptr: *mut Waker = (*ptr).as_mut_ptr();
             ptr.write(cx.waker().clone());
         });
     }
@@ -230,7 +436,7 @@ impl Task {
 #[derive(Clone, Copy)]
 struct State(usize);
 
-/// Create a new one-shot channel for sending single values across asynchronous
+/// Creates a new one-shot channel for sending single values across asynchronous
 /// tasks.
 ///
 /// The function returns separate "send" and "receive" handles. The `Sender`
@@ -260,7 +466,56 @@ struct State(usize);
 ///     }
 /// }
 /// ```
+#[track_caller]
 pub fn channel<T>() -> (Sender<T>, Receiver<T>) {
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    let resource_span = {
+        let location = std::panic::Location::caller();
+
+        let resource_span = tracing::trace_span!(
+            "runtime.resource",
+            concrete_type = "Sender|Receiver",
+            kind = "Sync",
+            loc.file = location.file(),
+            loc.line = location.line(),
+            loc.col = location.column(),
+        );
+
+        resource_span.in_scope(|| {
+            tracing::trace!(
+            target: "runtime::resource::state_update",
+            tx_dropped = false,
+            tx_dropped.op = "override",
+            )
+        });
+
+        resource_span.in_scope(|| {
+            tracing::trace!(
+            target: "runtime::resource::state_update",
+            rx_dropped = false,
+            rx_dropped.op = "override",
+            )
+        });
+
+        resource_span.in_scope(|| {
+            tracing::trace!(
+            target: "runtime::resource::state_update",
+            value_sent = false,
+            value_sent.op = "override",
+            )
+        });
+
+        resource_span.in_scope(|| {
+            tracing::trace!(
+            target: "runtime::resource::state_update",
+            value_received = false,
+            value_received.op = "override",
+            )
+        });
+
+        resource_span
+    };
+
     let inner = Arc::new(Inner {
         state: AtomicUsize::new(State::new().as_usize()),
         value: UnsafeCell::new(None),
@@ -270,8 +525,27 @@ pub fn channel<T>() -> (Sender<T>, Receiver<T>) {
 
     let tx = Sender {
         inner: Some(inner.clone()),
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        resource_span: resource_span.clone(),
+    };
+
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    let async_op_span = resource_span
+        .in_scope(|| tracing::trace_span!("runtime.resource.async_op", source = "Receiver::await"));
+
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    let async_op_poll_span =
+        async_op_span.in_scope(|| tracing::trace_span!("runtime.resource.async_op.poll"));
+
+    let rx = Receiver {
+        inner: Some(inner),
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        resource_span,
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        async_op_span,
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        async_op_poll_span,
     };
-    let rx = Receiver { inner: Some(inner) };
 
     (tx, rx)
 }
@@ -343,6 +617,15 @@ impl<T> Sender<T> {
             }
         }
 
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        self.resource_span.in_scope(|| {
+            tracing::trace!(
+            target: "runtime::resource::state_update",
+            value_sent = true,
+            value_sent.op = "override",
+            )
+        });
+
         Ok(())
     }
 
@@ -416,7 +699,20 @@ impl<T> Sender<T> {
     pub async fn closed(&mut self) {
         use crate::future::poll_fn;
 
-        poll_fn(|cx| self.poll_closed(cx)).await
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let resource_span = self.resource_span.clone();
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let closed = trace::async_op(
+            || poll_fn(|cx| self.poll_closed(cx)),
+            resource_span,
+            "Sender::closed",
+            "poll_closed",
+            false,
+        );
+        #[cfg(not(all(tokio_unstable, feature = "tracing")))]
+        let closed = poll_fn(|cx| self.poll_closed(cx));
+
+        closed.await
     }
 
     /// Returns `true` if the associated [`Receiver`] handle has been dropped.
@@ -453,7 +749,7 @@ impl<T> Sender<T> {
         state.is_closed()
     }
 
-    /// Check whether the oneshot channel has been closed, and if not, schedules the
+    /// Checks whether the oneshot channel has been closed, and if not, schedules the
     /// `Waker` in the provided `Context` to receive a notification when the channel is
     /// closed.
     ///
@@ -494,8 +790,10 @@ impl<T> Sender<T> {
     /// }
     /// ```
     pub fn poll_closed(&mut self, cx: &mut Context<'_>) -> Poll<()> {
+        ready!(crate::trace::trace_leaf(cx));
+
         // Keep track of task budget
-        let coop = ready!(crate::coop::poll_proceed(cx));
+        let coop = ready!(crate::runtime::coop::poll_proceed(cx));
 
         let inner = self.inner.as_ref().unwrap();
 
@@ -503,7 +801,7 @@ impl<T> Sender<T> {
 
         if state.is_closed() {
             coop.made_progress();
-            return Poll::Ready(());
+            return Ready(());
         }
 
         if state.is_tx_task_set() {
@@ -546,6 +844,14 @@ impl<T> Drop for Sender<T> {
     fn drop(&mut self) {
         if let Some(inner) = self.inner.as_ref() {
             inner.complete();
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            self.resource_span.in_scope(|| {
+                tracing::trace!(
+                target: "runtime::resource::state_update",
+                tx_dropped = true,
+                tx_dropped.op = "override",
+                )
+            });
         }
     }
 }
@@ -613,6 +919,14 @@ impl<T> Receiver<T> {
     pub fn close(&mut self) {
         if let Some(inner) = self.inner.as_ref() {
             inner.close();
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            self.resource_span.in_scope(|| {
+                tracing::trace!(
+                target: "runtime::resource::state_update",
+                rx_dropped = true,
+                rx_dropped.op = "override",
+                )
+            });
         }
     }
 
@@ -625,12 +939,16 @@ impl<T> Receiver<T> {
     /// This function is useful to call from outside the context of an
     /// asynchronous task.
     ///
+    /// Note that unlike the `poll` method, the `try_recv` method cannot fail
+    /// spuriously. Any send or close event that happens before this call to
+    /// `try_recv` will be correctly returned to the caller.
+    ///
     /// # Return
     ///
     /// - `Ok(T)` if a value is pending in the channel.
     /// - `Err(TryRecvError::Empty)` if no value has been sent yet.
     /// - `Err(TryRecvError::Closed)` if the sender has dropped without sending
-    ///   a value.
+    ///   a value, or if the message has already been received.
     ///
     /// # Examples
     ///
@@ -690,7 +1008,17 @@ impl<T> Receiver<T> {
                 // `UnsafeCell`. Therefore, it is now safe for us to access the
                 // cell.
                 match unsafe { inner.consume_value() } {
-                    Some(value) => Ok(value),
+                    Some(value) => {
+                        #[cfg(all(tokio_unstable, feature = "tracing"))]
+                        self.resource_span.in_scope(|| {
+                            tracing::trace!(
+                            target: "runtime::resource::state_update",
+                            value_received = true,
+                            value_received.op = "override",
+                            )
+                        });
+                        Ok(value)
+                    }
                     None => Err(TryRecvError::Closed),
                 }
             } else if state.is_closed() {
@@ -706,12 +1034,52 @@ impl<T> Receiver<T> {
         self.inner = None;
         result
     }
+
+    /// Blocking receive to call outside of asynchronous contexts.
+    ///
+    /// # Panics
+    ///
+    /// This function panics if called within an asynchronous execution
+    /// context.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::thread;
+    /// use tokio::sync::oneshot;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let (tx, rx) = oneshot::channel::<u8>();
+    ///
+    ///     let sync_code = thread::spawn(move || {
+    ///         assert_eq!(Ok(10), rx.blocking_recv());
+    ///     });
+    ///
+    ///     let _ = tx.send(10);
+    ///     sync_code.join().unwrap();
+    /// }
+    /// ```
+    #[track_caller]
+    #[cfg(feature = "sync")]
+    #[cfg_attr(docsrs, doc(alias = "recv_blocking"))]
+    pub fn blocking_recv(self) -> Result<T, RecvError> {
+        crate::future::block_on(self)
+    }
 }
 
 impl<T> Drop for Receiver<T> {
     fn drop(&mut self) {
         if let Some(inner) = self.inner.as_ref() {
             inner.close();
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            self.resource_span.in_scope(|| {
+                tracing::trace!(
+                target: "runtime::resource::state_update",
+                rx_dropped = true,
+                rx_dropped.op = "override",
+                )
+            });
         }
     }
 }
@@ -721,8 +1089,21 @@ impl<T> Future for Receiver<T> {
 
     fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
         // If `inner` is `None`, then `poll()` has already completed.
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let _res_span = self.resource_span.clone().entered();
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let _ao_span = self.async_op_span.clone().entered();
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let _ao_poll_span = self.async_op_poll_span.clone().entered();
+
         let ret = if let Some(inner) = self.as_ref().get_ref().inner.as_ref() {
-            ready!(inner.poll_recv(cx))?
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            let res = ready!(trace_poll_op!("poll_recv", inner.poll_recv(cx)))?;
+
+            #[cfg(any(not(tokio_unstable), not(feature = "tracing")))]
+            let res = ready!(inner.poll_recv(cx))?;
+
+            res
         } else {
             panic!("called after complete");
         };
@@ -751,8 +1132,9 @@ impl<T> Inner<T> {
     }
 
     fn poll_recv(&self, cx: &mut Context<'_>) -> Poll<Result<T, RecvError>> {
+        ready!(crate::trace::trace_leaf(cx));
         // Keep track of task budget
-        let coop = ready!(crate::coop::poll_proceed(cx));
+        let coop = ready!(crate::runtime::coop::poll_proceed(cx));
 
         // Load the state
         let mut state = State::load(&self.state, Acquire);
diff --git a/vendor/tokio/src/sync/rwlock.rs b/vendor/tokio/src/sync/rwlock.rs
index 120bc72b8..dd4928546 100644
--- a/vendor/tokio/src/sync/rwlock.rs
+++ b/vendor/tokio/src/sync/rwlock.rs
@@ -1,9 +1,10 @@
 use crate::sync::batch_semaphore::{Semaphore, TryAcquireError};
 use crate::sync::mutex::TryLockError;
+#[cfg(all(tokio_unstable, feature = "tracing"))]
+use crate::util::trace;
 use std::cell::UnsafeCell;
 use std::marker;
 use std::marker::PhantomData;
-use std::mem::ManuallyDrop;
 use std::sync::Arc;
 
 pub(crate) mod owned_read_guard;
@@ -84,8 +85,10 @@ const MAX_READS: u32 = 10;
 /// [`RwLockWriteGuard`]: struct@RwLockWriteGuard
 /// [`Send`]: trait@std::marker::Send
 /// [_write-preferring_]: https://en.wikipedia.org/wiki/Readers%E2%80%93writer_lock#Priority_policies
-#[derive(Debug)]
 pub struct RwLock<T: ?Sized> {
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    resource_span: tracing::Span,
+
     // maximum number of concurrent readers
     mr: u32,
 
@@ -197,14 +200,55 @@ impl<T: ?Sized> RwLock<T> {
     ///
     /// let lock = RwLock::new(5);
     /// ```
+    #[track_caller]
     pub fn new(value: T) -> RwLock<T>
     where
         T: Sized,
     {
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let resource_span = {
+            let location = std::panic::Location::caller();
+            let resource_span = tracing::trace_span!(
+                "runtime.resource",
+                concrete_type = "RwLock",
+                kind = "Sync",
+                loc.file = location.file(),
+                loc.line = location.line(),
+                loc.col = location.column(),
+            );
+
+            resource_span.in_scope(|| {
+                tracing::trace!(
+                    target: "runtime::resource::state_update",
+                    max_readers = MAX_READS,
+                );
+
+                tracing::trace!(
+                    target: "runtime::resource::state_update",
+                    write_locked = false,
+                );
+
+                tracing::trace!(
+                    target: "runtime::resource::state_update",
+                    current_readers = 0,
+                );
+            });
+
+            resource_span
+        };
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let s = resource_span.in_scope(|| Semaphore::new(MAX_READS as usize));
+
+        #[cfg(any(not(tokio_unstable), not(feature = "tracing")))]
+        let s = Semaphore::new(MAX_READS as usize);
+
         RwLock {
             mr: MAX_READS,
             c: UnsafeCell::new(value),
-            s: Semaphore::new(MAX_READS as usize),
+            s,
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span,
         }
     }
 
@@ -222,6 +266,7 @@ impl<T: ?Sized> RwLock<T> {
     /// # Panics
     ///
     /// Panics if `max_reads` is more than `u32::MAX >> 3`.
+    #[track_caller]
     pub fn with_max_readers(value: T, max_reads: u32) -> RwLock<T>
     where
         T: Sized,
@@ -231,10 +276,52 @@ impl<T: ?Sized> RwLock<T> {
             "a RwLock may not be created with more than {} readers",
             MAX_READS
         );
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let resource_span = {
+            let location = std::panic::Location::caller();
+
+            let resource_span = tracing::trace_span!(
+                "runtime.resource",
+                concrete_type = "RwLock",
+                kind = "Sync",
+                loc.file = location.file(),
+                loc.line = location.line(),
+                loc.col = location.column(),
+            );
+
+            resource_span.in_scope(|| {
+                tracing::trace!(
+                    target: "runtime::resource::state_update",
+                    max_readers = max_reads,
+                );
+
+                tracing::trace!(
+                    target: "runtime::resource::state_update",
+                    write_locked = false,
+                );
+
+                tracing::trace!(
+                    target: "runtime::resource::state_update",
+                    current_readers = 0,
+                );
+            });
+
+            resource_span
+        };
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let s = resource_span.in_scope(|| Semaphore::new(max_reads as usize));
+
+        #[cfg(any(not(tokio_unstable), not(feature = "tracing")))]
+        let s = Semaphore::new(max_reads as usize);
+
         RwLock {
             mr: max_reads,
             c: UnsafeCell::new(value),
-            s: Semaphore::new(max_reads as usize),
+            s,
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span,
         }
     }
 
@@ -257,6 +344,8 @@ impl<T: ?Sized> RwLock<T> {
             mr: MAX_READS,
             c: UnsafeCell::new(value),
             s: Semaphore::const_new(MAX_READS as usize),
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: tracing::Span::none(),
         }
     }
 
@@ -281,6 +370,8 @@ impl<T: ?Sized> RwLock<T> {
             mr: max_reads,
             c: UnsafeCell::new(value),
             s: Semaphore::const_new(max_reads as usize),
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: tracing::Span::none(),
         }
     }
 
@@ -327,19 +418,100 @@ impl<T: ?Sized> RwLock<T> {
     ///
     ///     // Drop the guard after the spawned task finishes.
     ///     drop(n);
-    ///}
+    /// }
     /// ```
     pub async fn read(&self) -> RwLockReadGuard<'_, T> {
-        self.s.acquire(1).await.unwrap_or_else(|_| {
-            // The semaphore was closed. but, we never explicitly close it, and we have a
-            // handle to it through the Arc, which means that this can never happen.
-            unreachable!()
+        let acquire_fut = async {
+            self.s.acquire(1).await.unwrap_or_else(|_| {
+                // The semaphore was closed. but, we never explicitly close it, and we have a
+                // handle to it through the Arc, which means that this can never happen.
+                unreachable!()
+            });
+
+            RwLockReadGuard {
+                s: &self.s,
+                data: self.c.get(),
+                marker: PhantomData,
+                #[cfg(all(tokio_unstable, feature = "tracing"))]
+                resource_span: self.resource_span.clone(),
+            }
+        };
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let acquire_fut = trace::async_op(
+            move || acquire_fut,
+            self.resource_span.clone(),
+            "RwLock::read",
+            "poll",
+            false,
+        );
+
+        #[allow(clippy::let_and_return)] // this lint triggers when disabling tracing
+        let guard = acquire_fut.await;
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        self.resource_span.in_scope(|| {
+            tracing::trace!(
+            target: "runtime::resource::state_update",
+            current_readers = 1,
+            current_readers.op = "add",
+            )
         });
-        RwLockReadGuard {
-            s: &self.s,
-            data: self.c.get(),
-            marker: marker::PhantomData,
-        }
+
+        guard
+    }
+
+    /// Blockingly locks this `RwLock` with shared read access.
+    ///
+    /// This method is intended for use cases where you
+    /// need to use this rwlock in asynchronous code as well as in synchronous code.
+    ///
+    /// Returns an RAII guard which will drop the read access of this `RwLock` when dropped.
+    ///
+    /// # Panics
+    ///
+    /// This function panics if called within an asynchronous execution context.
+    ///
+    ///   - If you find yourself in an asynchronous execution context and needing
+    ///     to call some (synchronous) function which performs one of these
+    ///     `blocking_` operations, then consider wrapping that call inside
+    ///     [`spawn_blocking()`][crate::runtime::Handle::spawn_blocking]
+    ///     (or [`block_in_place()`][crate::task::block_in_place]).
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::sync::Arc;
+    /// use tokio::sync::RwLock;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let rwlock = Arc::new(RwLock::new(1));
+    ///     let mut write_lock = rwlock.write().await;
+    ///
+    ///     let blocking_task = tokio::task::spawn_blocking({
+    ///         let rwlock = Arc::clone(&rwlock);
+    ///         move || {
+    ///             // This shall block until the `write_lock` is released.
+    ///             let read_lock = rwlock.blocking_read();
+    ///             assert_eq!(*read_lock, 0);
+    ///         }
+    ///     });
+    ///
+    ///     *write_lock -= 1;
+    ///     drop(write_lock); // release the lock.
+    ///
+    ///     // Await the completion of the blocking task.
+    ///     blocking_task.await.unwrap();
+    ///
+    ///     // Assert uncontended.
+    ///     assert!(rwlock.try_write().is_ok());
+    /// }
+    /// ```
+    #[track_caller]
+    #[cfg(feature = "sync")]
+    pub fn blocking_read(&self) -> RwLockReadGuard<'_, T> {
+        crate::future::block_on(self.read())
     }
 
     /// Locks this `RwLock` with shared read access, causing the current task
@@ -394,16 +566,47 @@ impl<T: ?Sized> RwLock<T> {
     ///}
     /// ```
     pub async fn read_owned(self: Arc<Self>) -> OwnedRwLockReadGuard<T> {
-        self.s.acquire(1).await.unwrap_or_else(|_| {
-            // The semaphore was closed. but, we never explicitly close it, and we have a
-            // handle to it through the Arc, which means that this can never happen.
-            unreachable!()
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let resource_span = self.resource_span.clone();
+
+        let acquire_fut = async {
+            self.s.acquire(1).await.unwrap_or_else(|_| {
+                // The semaphore was closed. but, we never explicitly close it, and we have a
+                // handle to it through the Arc, which means that this can never happen.
+                unreachable!()
+            });
+
+            OwnedRwLockReadGuard {
+                #[cfg(all(tokio_unstable, feature = "tracing"))]
+                resource_span: self.resource_span.clone(),
+                data: self.c.get(),
+                lock: self,
+                _p: PhantomData,
+            }
+        };
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let acquire_fut = trace::async_op(
+            move || acquire_fut,
+            resource_span,
+            "RwLock::read_owned",
+            "poll",
+            false,
+        );
+
+        #[allow(clippy::let_and_return)] // this lint triggers when disabling tracing
+        let guard = acquire_fut.await;
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        guard.resource_span.in_scope(|| {
+            tracing::trace!(
+            target: "runtime::resource::state_update",
+            current_readers = 1,
+            current_readers.op = "add",
+            )
         });
-        OwnedRwLockReadGuard {
-            data: self.c.get(),
-            lock: ManuallyDrop::new(self),
-            _p: PhantomData,
-        }
+
+        guard
     }
 
     /// Attempts to acquire this `RwLock` with shared read access.
@@ -445,11 +648,24 @@ impl<T: ?Sized> RwLock<T> {
             Err(TryAcquireError::Closed) => unreachable!(),
         }
 
-        Ok(RwLockReadGuard {
+        let guard = RwLockReadGuard {
             s: &self.s,
             data: self.c.get(),
             marker: marker::PhantomData,
-        })
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: self.resource_span.clone(),
+        };
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        self.resource_span.in_scope(|| {
+            tracing::trace!(
+            target: "runtime::resource::state_update",
+            current_readers = 1,
+            current_readers.op = "add",
+            )
+        });
+
+        Ok(guard)
     }
 
     /// Attempts to acquire this `RwLock` with shared read access.
@@ -497,11 +713,24 @@ impl<T: ?Sized> RwLock<T> {
             Err(TryAcquireError::Closed) => unreachable!(),
         }
 
-        Ok(OwnedRwLockReadGuard {
+        let guard = OwnedRwLockReadGuard {
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: self.resource_span.clone(),
             data: self.c.get(),
-            lock: ManuallyDrop::new(self),
+            lock: self,
             _p: PhantomData,
-        })
+        };
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        guard.resource_span.in_scope(|| {
+            tracing::trace!(
+            target: "runtime::resource::state_update",
+            current_readers = 1,
+            current_readers.op = "add",
+            )
+        });
+
+        Ok(guard)
     }
 
     /// Locks this `RwLock` with exclusive write access, causing the current
@@ -533,17 +762,100 @@ impl<T: ?Sized> RwLock<T> {
     ///}
     /// ```
     pub async fn write(&self) -> RwLockWriteGuard<'_, T> {
-        self.s.acquire(self.mr).await.unwrap_or_else(|_| {
-            // The semaphore was closed. but, we never explicitly close it, and we have a
-            // handle to it through the Arc, which means that this can never happen.
-            unreachable!()
+        let acquire_fut = async {
+            self.s.acquire(self.mr).await.unwrap_or_else(|_| {
+                // The semaphore was closed. but, we never explicitly close it, and we have a
+                // handle to it through the Arc, which means that this can never happen.
+                unreachable!()
+            });
+
+            RwLockWriteGuard {
+                permits_acquired: self.mr,
+                s: &self.s,
+                data: self.c.get(),
+                marker: marker::PhantomData,
+                #[cfg(all(tokio_unstable, feature = "tracing"))]
+                resource_span: self.resource_span.clone(),
+            }
+        };
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let acquire_fut = trace::async_op(
+            move || acquire_fut,
+            self.resource_span.clone(),
+            "RwLock::write",
+            "poll",
+            false,
+        );
+
+        #[allow(clippy::let_and_return)] // this lint triggers when disabling tracing
+        let guard = acquire_fut.await;
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        self.resource_span.in_scope(|| {
+            tracing::trace!(
+            target: "runtime::resource::state_update",
+            write_locked = true,
+            write_locked.op = "override",
+            )
         });
-        RwLockWriteGuard {
-            permits_acquired: self.mr,
-            s: &self.s,
-            data: self.c.get(),
-            marker: marker::PhantomData,
-        }
+
+        guard
+    }
+
+    /// Blockingly locks this `RwLock` with exclusive write access.
+    ///
+    /// This method is intended for use cases where you
+    /// need to use this rwlock in asynchronous code as well as in synchronous code.
+    ///
+    /// Returns an RAII guard which will drop the write access of this `RwLock` when dropped.
+    ///
+    /// # Panics
+    ///
+    /// This function panics if called within an asynchronous execution context.
+    ///
+    ///   - If you find yourself in an asynchronous execution context and needing
+    ///     to call some (synchronous) function which performs one of these
+    ///     `blocking_` operations, then consider wrapping that call inside
+    ///     [`spawn_blocking()`][crate::runtime::Handle::spawn_blocking]
+    ///     (or [`block_in_place()`][crate::task::block_in_place]).
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::sync::Arc;
+    /// use tokio::{sync::RwLock};
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let rwlock =  Arc::new(RwLock::new(1));
+    ///     let read_lock = rwlock.read().await;
+    ///
+    ///     let blocking_task = tokio::task::spawn_blocking({
+    ///         let rwlock = Arc::clone(&rwlock);
+    ///         move || {
+    ///             // This shall block until the `read_lock` is released.
+    ///             let mut write_lock = rwlock.blocking_write();
+    ///             *write_lock = 2;
+    ///         }
+    ///     });
+    ///
+    ///     assert_eq!(*read_lock, 1);
+    ///     // Release the last outstanding read lock.
+    ///     drop(read_lock);
+    ///
+    ///     // Await the completion of the blocking task.
+    ///     blocking_task.await.unwrap();
+    ///
+    ///     // Assert uncontended.
+    ///     let read_lock = rwlock.try_read().unwrap();
+    ///     assert_eq!(*read_lock, 2);
+    /// }
+    /// ```
+    #[track_caller]
+    #[cfg(feature = "sync")]
+    pub fn blocking_write(&self) -> RwLockWriteGuard<'_, T> {
+        crate::future::block_on(self.write())
     }
 
     /// Locks this `RwLock` with exclusive write access, causing the current
@@ -582,17 +894,48 @@ impl<T: ?Sized> RwLock<T> {
     ///}
     /// ```
     pub async fn write_owned(self: Arc<Self>) -> OwnedRwLockWriteGuard<T> {
-        self.s.acquire(self.mr).await.unwrap_or_else(|_| {
-            // The semaphore was closed. but, we never explicitly close it, and we have a
-            // handle to it through the Arc, which means that this can never happen.
-            unreachable!()
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let resource_span = self.resource_span.clone();
+
+        let acquire_fut = async {
+            self.s.acquire(self.mr).await.unwrap_or_else(|_| {
+                // The semaphore was closed. but, we never explicitly close it, and we have a
+                // handle to it through the Arc, which means that this can never happen.
+                unreachable!()
+            });
+
+            OwnedRwLockWriteGuard {
+                #[cfg(all(tokio_unstable, feature = "tracing"))]
+                resource_span: self.resource_span.clone(),
+                permits_acquired: self.mr,
+                data: self.c.get(),
+                lock: self,
+                _p: PhantomData,
+            }
+        };
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let acquire_fut = trace::async_op(
+            move || acquire_fut,
+            resource_span,
+            "RwLock::write_owned",
+            "poll",
+            false,
+        );
+
+        #[allow(clippy::let_and_return)] // this lint triggers when disabling tracing
+        let guard = acquire_fut.await;
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        guard.resource_span.in_scope(|| {
+            tracing::trace!(
+            target: "runtime::resource::state_update",
+            write_locked = true,
+            write_locked.op = "override",
+            )
         });
-        OwnedRwLockWriteGuard {
-            permits_acquired: self.mr,
-            data: self.c.get(),
-            lock: ManuallyDrop::new(self),
-            _p: PhantomData,
-        }
+
+        guard
     }
 
     /// Attempts to acquire this `RwLock` with exclusive write access.
@@ -625,12 +968,25 @@ impl<T: ?Sized> RwLock<T> {
             Err(TryAcquireError::Closed) => unreachable!(),
         }
 
-        Ok(RwLockWriteGuard {
+        let guard = RwLockWriteGuard {
             permits_acquired: self.mr,
             s: &self.s,
             data: self.c.get(),
             marker: marker::PhantomData,
-        })
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: self.resource_span.clone(),
+        };
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        self.resource_span.in_scope(|| {
+            tracing::trace!(
+            target: "runtime::resource::state_update",
+            write_locked = true,
+            write_locked.op = "override",
+            )
+        });
+
+        Ok(guard)
     }
 
     /// Attempts to acquire this `RwLock` with exclusive write access.
@@ -670,12 +1026,25 @@ impl<T: ?Sized> RwLock<T> {
             Err(TryAcquireError::Closed) => unreachable!(),
         }
 
-        Ok(OwnedRwLockWriteGuard {
+        let guard = OwnedRwLockWriteGuard {
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: self.resource_span.clone(),
             permits_acquired: self.mr,
             data: self.c.get(),
-            lock: ManuallyDrop::new(self),
+            lock: self,
             _p: PhantomData,
-        })
+        };
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        guard.resource_span.in_scope(|| {
+            tracing::trace!(
+            target: "runtime::resource::state_update",
+            write_locked = true,
+            write_locked.op = "override",
+            )
+        });
+
+        Ok(guard)
     }
 
     /// Returns a mutable reference to the underlying data.
@@ -725,3 +1094,17 @@ where
         Self::new(T::default())
     }
 }
+
+impl<T: ?Sized> std::fmt::Debug for RwLock<T>
+where
+    T: std::fmt::Debug,
+{
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let mut d = f.debug_struct("RwLock");
+        match self.try_read() {
+            Ok(inner) => d.field("data", &&*inner),
+            Err(_) => d.field("data", &format_args!("<locked>")),
+        };
+        d.finish()
+    }
+}
diff --git a/vendor/tokio/src/sync/rwlock/owned_read_guard.rs b/vendor/tokio/src/sync/rwlock/owned_read_guard.rs
index b7f3926a4..273e7b86f 100644
--- a/vendor/tokio/src/sync/rwlock/owned_read_guard.rs
+++ b/vendor/tokio/src/sync/rwlock/owned_read_guard.rs
@@ -1,10 +1,7 @@
 use crate::sync::rwlock::RwLock;
-use std::fmt;
 use std::marker::PhantomData;
-use std::mem;
-use std::mem::ManuallyDrop;
-use std::ops;
 use std::sync::Arc;
+use std::{fmt, mem, ops, ptr};
 
 /// Owned RAII structure used to release the shared read access of a lock when
 /// dropped.
@@ -14,15 +11,41 @@ use std::sync::Arc;
 ///
 /// [`read_owned`]: method@crate::sync::RwLock::read_owned
 /// [`RwLock`]: struct@crate::sync::RwLock
+#[clippy::has_significant_drop]
 pub struct OwnedRwLockReadGuard<T: ?Sized, U: ?Sized = T> {
-    // ManuallyDrop allows us to destructure into this field without running the destructor.
-    pub(super) lock: ManuallyDrop<Arc<RwLock<T>>>,
+    // When changing the fields in this struct, make sure to update the
+    // `skip_drop` method.
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    pub(super) resource_span: tracing::Span,
+    pub(super) lock: Arc<RwLock<T>>,
     pub(super) data: *const U,
     pub(super) _p: PhantomData<T>,
 }
 
+#[allow(dead_code)] // Unused fields are still used in Drop.
+struct Inner<T: ?Sized, U: ?Sized> {
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    resource_span: tracing::Span,
+    lock: Arc<RwLock<T>>,
+    data: *const U,
+}
+
 impl<T: ?Sized, U: ?Sized> OwnedRwLockReadGuard<T, U> {
-    /// Make a new `OwnedRwLockReadGuard` for a component of the locked data.
+    fn skip_drop(self) -> Inner<T, U> {
+        let me = mem::ManuallyDrop::new(self);
+        // SAFETY: This duplicates the values in every field of the guard, then
+        // forgets the originals, so in the end no value is duplicated.
+        unsafe {
+            Inner {
+                #[cfg(all(tokio_unstable, feature = "tracing"))]
+                resource_span: ptr::read(&me.resource_span),
+                lock: ptr::read(&me.lock),
+                data: me.data,
+            }
+        }
+    }
+
+    /// Makes a new `OwnedRwLockReadGuard` for a component of the locked data.
     /// This operation cannot fail as the `OwnedRwLockReadGuard` passed in
     /// already locked the data.
     ///
@@ -50,18 +73,19 @@ impl<T: ?Sized, U: ?Sized> OwnedRwLockReadGuard<T, U> {
     /// # }
     /// ```
     #[inline]
-    pub fn map<F, V: ?Sized>(mut this: Self, f: F) -> OwnedRwLockReadGuard<T, V>
+    pub fn map<F, V: ?Sized>(this: Self, f: F) -> OwnedRwLockReadGuard<T, V>
     where
         F: FnOnce(&U) -> &V,
     {
         let data = f(&*this) as *const V;
-        let lock = unsafe { ManuallyDrop::take(&mut this.lock) };
-        // NB: Forget to avoid drop impl from being called.
-        mem::forget(this);
+        let this = this.skip_drop();
+
         OwnedRwLockReadGuard {
-            lock: ManuallyDrop::new(lock),
+            lock: this.lock,
             data,
             _p: PhantomData,
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: this.resource_span,
         }
     }
 
@@ -96,7 +120,7 @@ impl<T: ?Sized, U: ?Sized> OwnedRwLockReadGuard<T, U> {
     /// # }
     /// ```
     #[inline]
-    pub fn try_map<F, V: ?Sized>(mut this: Self, f: F) -> Result<OwnedRwLockReadGuard<T, V>, Self>
+    pub fn try_map<F, V: ?Sized>(this: Self, f: F) -> Result<OwnedRwLockReadGuard<T, V>, Self>
     where
         F: FnOnce(&U) -> Option<&V>,
     {
@@ -104,13 +128,14 @@ impl<T: ?Sized, U: ?Sized> OwnedRwLockReadGuard<T, U> {
             Some(data) => data as *const V,
             None => return Err(this),
         };
-        let lock = unsafe { ManuallyDrop::take(&mut this.lock) };
-        // NB: Forget to avoid drop impl from being called.
-        mem::forget(this);
+        let this = this.skip_drop();
+
         Ok(OwnedRwLockReadGuard {
-            lock: ManuallyDrop::new(lock),
+            lock: this.lock,
             data,
             _p: PhantomData,
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: this.resource_span,
         })
     }
 }
@@ -144,6 +169,14 @@ where
 impl<T: ?Sized, U: ?Sized> Drop for OwnedRwLockReadGuard<T, U> {
     fn drop(&mut self) {
         self.lock.s.release(1);
-        unsafe { ManuallyDrop::drop(&mut self.lock) };
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        self.resource_span.in_scope(|| {
+            tracing::trace!(
+            target: "runtime::resource::state_update",
+            current_readers = 1,
+            current_readers.op = "sub",
+            )
+        });
     }
 }
diff --git a/vendor/tokio/src/sync/rwlock/owned_write_guard.rs b/vendor/tokio/src/sync/rwlock/owned_write_guard.rs
index 91b659524..a8ce4a160 100644
--- a/vendor/tokio/src/sync/rwlock/owned_write_guard.rs
+++ b/vendor/tokio/src/sync/rwlock/owned_write_guard.rs
@@ -1,11 +1,9 @@
 use crate::sync::rwlock::owned_read_guard::OwnedRwLockReadGuard;
 use crate::sync::rwlock::owned_write_guard_mapped::OwnedRwLockMappedWriteGuard;
 use crate::sync::rwlock::RwLock;
-use std::fmt;
 use std::marker::PhantomData;
-use std::mem::{self, ManuallyDrop};
-use std::ops;
 use std::sync::Arc;
+use std::{fmt, mem, ops, ptr};
 
 /// Owned RAII structure used to release the exclusive write access of a lock when
 /// dropped.
@@ -15,16 +13,44 @@ use std::sync::Arc;
 ///
 /// [`write_owned`]: method@crate::sync::RwLock::write_owned
 /// [`RwLock`]: struct@crate::sync::RwLock
+#[clippy::has_significant_drop]
 pub struct OwnedRwLockWriteGuard<T: ?Sized> {
+    // When changing the fields in this struct, make sure to update the
+    // `skip_drop` method.
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    pub(super) resource_span: tracing::Span,
     pub(super) permits_acquired: u32,
-    // ManuallyDrop allows us to destructure into this field without running the destructor.
-    pub(super) lock: ManuallyDrop<Arc<RwLock<T>>>,
+    pub(super) lock: Arc<RwLock<T>>,
     pub(super) data: *mut T,
     pub(super) _p: PhantomData<T>,
 }
 
+#[allow(dead_code)] // Unused fields are still used in Drop.
+struct Inner<T: ?Sized> {
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    resource_span: tracing::Span,
+    permits_acquired: u32,
+    lock: Arc<RwLock<T>>,
+    data: *const T,
+}
+
 impl<T: ?Sized> OwnedRwLockWriteGuard<T> {
-    /// Make a new [`OwnedRwLockMappedWriteGuard`] for a component of the locked
+    fn skip_drop(self) -> Inner<T> {
+        let me = mem::ManuallyDrop::new(self);
+        // SAFETY: This duplicates the values in every field of the guard, then
+        // forgets the originals, so in the end no value is duplicated.
+        unsafe {
+            Inner {
+                #[cfg(all(tokio_unstable, feature = "tracing"))]
+                resource_span: ptr::read(&me.resource_span),
+                permits_acquired: me.permits_acquired,
+                lock: ptr::read(&me.lock),
+                data: me.data,
+            }
+        }
+    }
+
+    /// Makes a new [`OwnedRwLockMappedWriteGuard`] for a component of the locked
     /// data.
     ///
     /// This operation cannot fail as the `OwnedRwLockWriteGuard` passed in
@@ -62,19 +88,90 @@ impl<T: ?Sized> OwnedRwLockWriteGuard<T> {
         F: FnOnce(&mut T) -> &mut U,
     {
         let data = f(&mut *this) as *mut U;
-        let lock = unsafe { ManuallyDrop::take(&mut this.lock) };
-        let permits_acquired = this.permits_acquired;
-        // NB: Forget to avoid drop impl from being called.
-        mem::forget(this);
+        let this = this.skip_drop();
+
         OwnedRwLockMappedWriteGuard {
-            permits_acquired,
-            lock: ManuallyDrop::new(lock),
+            permits_acquired: this.permits_acquired,
+            lock: this.lock,
             data,
             _p: PhantomData,
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: this.resource_span,
         }
     }
 
-    /// Attempts to make  a new [`OwnedRwLockMappedWriteGuard`] for a component
+    /// Makes a new [`OwnedRwLockReadGuard`] for a component of the locked data.
+    ///
+    /// This operation cannot fail as the `OwnedRwLockWriteGuard` passed in already
+    /// locked the data.
+    ///
+    /// This is an associated function that needs to be used as
+    /// `OwnedRwLockWriteGuard::downgrade_map(..)`. A method would interfere with methods of
+    /// the same name on the contents of the locked data.
+    ///
+    /// Inside of `f`, you retain exclusive access to the data, despite only being given a `&T`. Handing out a
+    /// `&mut T` would result in unsoundness, as you could use interior mutability.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::sync::Arc;
+    /// use tokio::sync::{RwLock, OwnedRwLockWriteGuard};
+    ///
+    /// #[derive(Debug, Clone, Copy, PartialEq, Eq)]
+    /// struct Foo(u32);
+    ///
+    /// # #[tokio::main]
+    /// # async fn main() {
+    /// let lock = Arc::new(RwLock::new(Foo(1)));
+    ///
+    /// let guard = Arc::clone(&lock).write_owned().await;
+    /// let mapped = OwnedRwLockWriteGuard::downgrade_map(guard, |f| &f.0);
+    /// let foo = lock.read_owned().await;
+    /// assert_eq!(foo.0, *mapped);
+    /// # }
+    /// ```
+    #[inline]
+    pub fn downgrade_map<F, U: ?Sized>(this: Self, f: F) -> OwnedRwLockReadGuard<T, U>
+    where
+        F: FnOnce(&T) -> &U,
+    {
+        let data = f(&*this) as *const U;
+        let this = this.skip_drop();
+        let guard = OwnedRwLockReadGuard {
+            lock: this.lock,
+            data,
+            _p: PhantomData,
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: this.resource_span,
+        };
+
+        // Release all but one of the permits held by the write guard
+        let to_release = (this.permits_acquired - 1) as usize;
+        guard.lock.s.release(to_release);
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        guard.resource_span.in_scope(|| {
+            tracing::trace!(
+            target: "runtime::resource::state_update",
+            write_locked = false,
+            write_locked.op = "override",
+            )
+        });
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        guard.resource_span.in_scope(|| {
+            tracing::trace!(
+            target: "runtime::resource::state_update",
+            current_readers = 1,
+            current_readers.op = "add",
+            )
+        });
+
+        guard
+    }
+
+    /// Attempts to make a new [`OwnedRwLockMappedWriteGuard`] for a component
     /// of the locked data. The original guard is returned if the closure
     /// returns `None`.
     ///
@@ -121,18 +218,99 @@ impl<T: ?Sized> OwnedRwLockWriteGuard<T> {
             Some(data) => data as *mut U,
             None => return Err(this),
         };
-        let permits_acquired = this.permits_acquired;
-        let lock = unsafe { ManuallyDrop::take(&mut this.lock) };
-        // NB: Forget to avoid drop impl from being called.
-        mem::forget(this);
+        let this = this.skip_drop();
+
         Ok(OwnedRwLockMappedWriteGuard {
-            permits_acquired,
-            lock: ManuallyDrop::new(lock),
+            permits_acquired: this.permits_acquired,
+            lock: this.lock,
             data,
             _p: PhantomData,
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: this.resource_span,
         })
     }
 
+    /// Attempts to make a new [`OwnedRwLockReadGuard`] for a component of
+    /// the locked data. The original guard is returned if the closure returns
+    /// `None`.
+    ///
+    /// This operation cannot fail as the `OwnedRwLockWriteGuard` passed in already
+    /// locked the data.
+    ///
+    /// This is an associated function that needs to be
+    /// used as `OwnedRwLockWriteGuard::try_downgrade_map(...)`. A method would interfere with
+    /// methods of the same name on the contents of the locked data.
+    ///
+    /// Inside of `f`, you retain exclusive access to the data, despite only being given a `&T`. Handing out a
+    /// `&mut T` would result in unsoundness, as you could use interior mutability.
+    ///
+    /// If this function returns `Err(...)`, the lock is never unlocked nor downgraded.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::sync::Arc;
+    /// use tokio::sync::{RwLock, OwnedRwLockWriteGuard};
+    ///
+    /// #[derive(Debug, Clone, Copy, PartialEq, Eq)]
+    /// struct Foo(u32);
+    ///
+    /// # #[tokio::main]
+    /// # async fn main() {
+    /// let lock = Arc::new(RwLock::new(Foo(1)));
+    ///
+    /// let guard = Arc::clone(&lock).write_owned().await;
+    /// let guard = OwnedRwLockWriteGuard::try_downgrade_map(guard, |f| Some(&f.0)).expect("should not fail");
+    /// let foo = lock.read_owned().await;
+    /// assert_eq!(foo.0, *guard);
+    /// # }
+    /// ```
+    #[inline]
+    pub fn try_downgrade_map<F, U: ?Sized>(
+        this: Self,
+        f: F,
+    ) -> Result<OwnedRwLockReadGuard<T, U>, Self>
+    where
+        F: FnOnce(&T) -> Option<&U>,
+    {
+        let data = match f(&*this) {
+            Some(data) => data as *const U,
+            None => return Err(this),
+        };
+        let this = this.skip_drop();
+        let guard = OwnedRwLockReadGuard {
+            lock: this.lock,
+            data,
+            _p: PhantomData,
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: this.resource_span,
+        };
+
+        // Release all but one of the permits held by the write guard
+        let to_release = (this.permits_acquired - 1) as usize;
+        guard.lock.s.release(to_release);
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        guard.resource_span.in_scope(|| {
+            tracing::trace!(
+            target: "runtime::resource::state_update",
+            write_locked = false,
+            write_locked.op = "override",
+            )
+        });
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        guard.resource_span.in_scope(|| {
+            tracing::trace!(
+            target: "runtime::resource::state_update",
+            current_readers = 1,
+            current_readers.op = "add",
+            )
+        });
+
+        Ok(guard)
+    }
+
     /// Converts this `OwnedRwLockWriteGuard` into an
     /// `OwnedRwLockMappedWriteGuard`. This method can be used to store a
     /// non-mapped guard in a struct field that expects a mapped guard.
@@ -178,19 +356,39 @@ impl<T: ?Sized> OwnedRwLockWriteGuard<T> {
     /// assert_eq!(*lock.read().await, 2, "second writer obtained write lock");
     /// # }
     /// ```
-    pub fn downgrade(mut self) -> OwnedRwLockReadGuard<T> {
-        let lock = unsafe { ManuallyDrop::take(&mut self.lock) };
-        let data = self.data;
+    pub fn downgrade(self) -> OwnedRwLockReadGuard<T> {
+        let this = self.skip_drop();
+        let guard = OwnedRwLockReadGuard {
+            lock: this.lock,
+            data: this.data,
+            _p: PhantomData,
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: this.resource_span,
+        };
 
         // Release all but one of the permits held by the write guard
-        lock.s.release((self.permits_acquired - 1) as usize);
-        // NB: Forget to avoid drop impl from being called.
-        mem::forget(self);
-        OwnedRwLockReadGuard {
-            lock: ManuallyDrop::new(lock),
-            data,
-            _p: PhantomData,
-        }
+        let to_release = (this.permits_acquired - 1) as usize;
+        guard.lock.s.release(to_release);
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        guard.resource_span.in_scope(|| {
+            tracing::trace!(
+            target: "runtime::resource::state_update",
+            write_locked = false,
+            write_locked.op = "override",
+            )
+        });
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        guard.resource_span.in_scope(|| {
+            tracing::trace!(
+            target: "runtime::resource::state_update",
+            current_readers = 1,
+            current_readers.op = "add",
+            )
+        });
+
+        guard
     }
 }
 
@@ -229,6 +427,14 @@ where
 impl<T: ?Sized> Drop for OwnedRwLockWriteGuard<T> {
     fn drop(&mut self) {
         self.lock.s.release(self.permits_acquired as usize);
-        unsafe { ManuallyDrop::drop(&mut self.lock) };
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        self.resource_span.in_scope(|| {
+            tracing::trace!(
+            target: "runtime::resource::state_update",
+            write_locked = false,
+            write_locked.op = "override",
+            )
+        });
     }
 }
diff --git a/vendor/tokio/src/sync/rwlock/owned_write_guard_mapped.rs b/vendor/tokio/src/sync/rwlock/owned_write_guard_mapped.rs
index 6453236eb..9f4952100 100644
--- a/vendor/tokio/src/sync/rwlock/owned_write_guard_mapped.rs
+++ b/vendor/tokio/src/sync/rwlock/owned_write_guard_mapped.rs
@@ -1,9 +1,7 @@
 use crate::sync::rwlock::RwLock;
-use std::fmt;
 use std::marker::PhantomData;
-use std::mem::{self, ManuallyDrop};
-use std::ops;
 use std::sync::Arc;
+use std::{fmt, mem, ops, ptr};
 
 /// Owned RAII structure used to release the exclusive write access of a lock when
 /// dropped.
@@ -14,16 +12,44 @@ use std::sync::Arc;
 ///
 /// [mapping]: method@crate::sync::OwnedRwLockWriteGuard::map
 /// [`OwnedRwLockWriteGuard`]: struct@crate::sync::OwnedRwLockWriteGuard
+#[clippy::has_significant_drop]
 pub struct OwnedRwLockMappedWriteGuard<T: ?Sized, U: ?Sized = T> {
+    // When changing the fields in this struct, make sure to update the
+    // `skip_drop` method.
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    pub(super) resource_span: tracing::Span,
     pub(super) permits_acquired: u32,
-    // ManuallyDrop allows us to destructure into this field without running the destructor.
-    pub(super) lock: ManuallyDrop<Arc<RwLock<T>>>,
+    pub(super) lock: Arc<RwLock<T>>,
     pub(super) data: *mut U,
     pub(super) _p: PhantomData<T>,
 }
 
+#[allow(dead_code)] // Unused fields are still used in Drop.
+struct Inner<T: ?Sized, U: ?Sized> {
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    resource_span: tracing::Span,
+    permits_acquired: u32,
+    lock: Arc<RwLock<T>>,
+    data: *const U,
+}
+
 impl<T: ?Sized, U: ?Sized> OwnedRwLockMappedWriteGuard<T, U> {
-    /// Make a new `OwnedRwLockMappedWriteGuard` for a component of the locked
+    fn skip_drop(self) -> Inner<T, U> {
+        let me = mem::ManuallyDrop::new(self);
+        // SAFETY: This duplicates the values in every field of the guard, then
+        // forgets the originals, so in the end no value is duplicated.
+        unsafe {
+            Inner {
+                #[cfg(all(tokio_unstable, feature = "tracing"))]
+                resource_span: ptr::read(&me.resource_span),
+                permits_acquired: me.permits_acquired,
+                lock: ptr::read(&me.lock),
+                data: me.data,
+            }
+        }
+    }
+
+    /// Makes a new `OwnedRwLockMappedWriteGuard` for a component of the locked
     /// data.
     ///
     /// This operation cannot fail as the `OwnedRwLockMappedWriteGuard` passed
@@ -61,15 +87,15 @@ impl<T: ?Sized, U: ?Sized> OwnedRwLockMappedWriteGuard<T, U> {
         F: FnOnce(&mut U) -> &mut V,
     {
         let data = f(&mut *this) as *mut V;
-        let lock = unsafe { ManuallyDrop::take(&mut this.lock) };
-        let permits_acquired = this.permits_acquired;
-        // NB: Forget to avoid drop impl from being called.
-        mem::forget(this);
+        let this = this.skip_drop();
+
         OwnedRwLockMappedWriteGuard {
-            permits_acquired,
-            lock: ManuallyDrop::new(lock),
+            permits_acquired: this.permits_acquired,
+            lock: this.lock,
             data,
             _p: PhantomData,
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: this.resource_span,
         }
     }
 
@@ -118,15 +144,15 @@ impl<T: ?Sized, U: ?Sized> OwnedRwLockMappedWriteGuard<T, U> {
             Some(data) => data as *mut V,
             None => return Err(this),
         };
-        let lock = unsafe { ManuallyDrop::take(&mut this.lock) };
-        let permits_acquired = this.permits_acquired;
-        // NB: Forget to avoid drop impl from being called.
-        mem::forget(this);
+        let this = this.skip_drop();
+
         Ok(OwnedRwLockMappedWriteGuard {
-            permits_acquired,
-            lock: ManuallyDrop::new(lock),
+            permits_acquired: this.permits_acquired,
+            lock: this.lock,
             data,
             _p: PhantomData,
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: this.resource_span,
         })
     }
 }
@@ -166,6 +192,14 @@ where
 impl<T: ?Sized, U: ?Sized> Drop for OwnedRwLockMappedWriteGuard<T, U> {
     fn drop(&mut self) {
         self.lock.s.release(self.permits_acquired as usize);
-        unsafe { ManuallyDrop::drop(&mut self.lock) };
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        self.resource_span.in_scope(|| {
+            tracing::trace!(
+            target: "runtime::resource::state_update",
+            write_locked = false,
+            write_locked.op = "override",
+            )
+        });
     }
 }
diff --git a/vendor/tokio/src/sync/rwlock/read_guard.rs b/vendor/tokio/src/sync/rwlock/read_guard.rs
index 38eec7727..a04b59588 100644
--- a/vendor/tokio/src/sync/rwlock/read_guard.rs
+++ b/vendor/tokio/src/sync/rwlock/read_guard.rs
@@ -1,8 +1,6 @@
 use crate::sync::batch_semaphore::Semaphore;
-use std::fmt;
-use std::marker;
-use std::mem;
-use std::ops;
+use std::marker::PhantomData;
+use std::{fmt, mem, ops};
 
 /// RAII structure used to release the shared read access of a lock when
 /// dropped.
@@ -12,14 +10,40 @@ use std::ops;
 ///
 /// [`read`]: method@crate::sync::RwLock::read
 /// [`RwLock`]: struct@crate::sync::RwLock
+#[clippy::has_significant_drop]
+#[must_use = "if unused the RwLock will immediately unlock"]
 pub struct RwLockReadGuard<'a, T: ?Sized> {
+    // When changing the fields in this struct, make sure to update the
+    // `skip_drop` method.
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    pub(super) resource_span: tracing::Span,
     pub(super) s: &'a Semaphore,
     pub(super) data: *const T,
-    pub(super) marker: marker::PhantomData<&'a T>,
+    pub(super) marker: PhantomData<&'a T>,
+}
+
+#[allow(dead_code)] // Unused fields are still used in Drop.
+struct Inner<'a, T: ?Sized> {
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    resource_span: tracing::Span,
+    s: &'a Semaphore,
+    data: *const T,
 }
 
 impl<'a, T: ?Sized> RwLockReadGuard<'a, T> {
-    /// Make a new `RwLockReadGuard` for a component of the locked data.
+    fn skip_drop(self) -> Inner<'a, T> {
+        let me = mem::ManuallyDrop::new(self);
+        // SAFETY: This duplicates the values in every field of the guard, then
+        // forgets the originals, so in the end no value is duplicated.
+        Inner {
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: unsafe { std::ptr::read(&me.resource_span) },
+            s: me.s,
+            data: me.data,
+        }
+    }
+
+    /// Makes a new `RwLockReadGuard` for a component of the locked data.
     ///
     /// This operation cannot fail as the `RwLockReadGuard` passed in already
     /// locked the data.
@@ -58,13 +82,14 @@ impl<'a, T: ?Sized> RwLockReadGuard<'a, T> {
         F: FnOnce(&T) -> &U,
     {
         let data = f(&*this) as *const U;
-        let s = this.s;
-        // NB: Forget to avoid drop impl from being called.
-        mem::forget(this);
+        let this = this.skip_drop();
+
         RwLockReadGuard {
-            s,
+            s: this.s,
             data,
-            marker: marker::PhantomData,
+            marker: PhantomData,
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: this.resource_span,
         }
     }
 
@@ -112,13 +137,14 @@ impl<'a, T: ?Sized> RwLockReadGuard<'a, T> {
             Some(data) => data as *const U,
             None => return Err(this),
         };
-        let s = this.s;
-        // NB: Forget to avoid drop impl from being called.
-        mem::forget(this);
+        let this = this.skip_drop();
+
         Ok(RwLockReadGuard {
-            s,
+            s: this.s,
             data,
-            marker: marker::PhantomData,
+            marker: PhantomData,
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: this.resource_span,
         })
     }
 }
@@ -152,5 +178,14 @@ where
 impl<'a, T: ?Sized> Drop for RwLockReadGuard<'a, T> {
     fn drop(&mut self) {
         self.s.release(1);
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        self.resource_span.in_scope(|| {
+            tracing::trace!(
+            target: "runtime::resource::state_update",
+            current_readers = 1,
+            current_readers.op = "sub",
+            )
+        });
     }
 }
diff --git a/vendor/tokio/src/sync/rwlock/write_guard.rs b/vendor/tokio/src/sync/rwlock/write_guard.rs
index 865a121ed..d405fc2b3 100644
--- a/vendor/tokio/src/sync/rwlock/write_guard.rs
+++ b/vendor/tokio/src/sync/rwlock/write_guard.rs
@@ -1,10 +1,8 @@
 use crate::sync::batch_semaphore::Semaphore;
 use crate::sync::rwlock::read_guard::RwLockReadGuard;
 use crate::sync::rwlock::write_guard_mapped::RwLockMappedWriteGuard;
-use std::fmt;
-use std::marker;
-use std::mem;
-use std::ops;
+use std::marker::PhantomData;
+use std::{fmt, mem, ops};
 
 /// RAII structure used to release the exclusive write access of a lock when
 /// dropped.
@@ -14,15 +12,43 @@ use std::ops;
 ///
 /// [`write`]: method@crate::sync::RwLock::write
 /// [`RwLock`]: struct@crate::sync::RwLock
+#[clippy::has_significant_drop]
+#[must_use = "if unused the RwLock will immediately unlock"]
 pub struct RwLockWriteGuard<'a, T: ?Sized> {
+    // When changing the fields in this struct, make sure to update the
+    // `skip_drop` method.
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    pub(super) resource_span: tracing::Span,
     pub(super) permits_acquired: u32,
     pub(super) s: &'a Semaphore,
     pub(super) data: *mut T,
-    pub(super) marker: marker::PhantomData<&'a mut T>,
+    pub(super) marker: PhantomData<&'a mut T>,
+}
+
+#[allow(dead_code)] // Unused fields are still used in Drop.
+struct Inner<'a, T: ?Sized> {
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    resource_span: tracing::Span,
+    permits_acquired: u32,
+    s: &'a Semaphore,
+    data: *mut T,
 }
 
 impl<'a, T: ?Sized> RwLockWriteGuard<'a, T> {
-    /// Make a new [`RwLockMappedWriteGuard`] for a component of the locked data.
+    fn skip_drop(self) -> Inner<'a, T> {
+        let me = mem::ManuallyDrop::new(self);
+        // SAFETY: This duplicates the values in every field of the guard, then
+        // forgets the originals, so in the end no value is duplicated.
+        Inner {
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: unsafe { std::ptr::read(&me.resource_span) },
+            permits_acquired: me.permits_acquired,
+            s: me.s,
+            data: me.data,
+        }
+    }
+
+    /// Makes a new [`RwLockMappedWriteGuard`] for a component of the locked data.
     ///
     /// This operation cannot fail as the `RwLockWriteGuard` passed in already
     /// locked the data.
@@ -64,19 +90,96 @@ impl<'a, T: ?Sized> RwLockWriteGuard<'a, T> {
         F: FnOnce(&mut T) -> &mut U,
     {
         let data = f(&mut *this) as *mut U;
-        let s = this.s;
-        let permits_acquired = this.permits_acquired;
-        // NB: Forget to avoid drop impl from being called.
-        mem::forget(this);
+        let this = this.skip_drop();
+
         RwLockMappedWriteGuard {
-            permits_acquired,
-            s,
+            permits_acquired: this.permits_acquired,
+            s: this.s,
             data,
-            marker: marker::PhantomData,
+            marker: PhantomData,
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: this.resource_span,
         }
     }
 
-    /// Attempts to make  a new [`RwLockMappedWriteGuard`] for a component of
+    /// Makes a new [`RwLockReadGuard`] for a component of the locked data.
+    ///
+    /// This operation cannot fail as the `RwLockWriteGuard` passed in already
+    /// locked the data.
+    ///
+    /// This is an associated function that needs to be used as
+    /// `RwLockWriteGuard::downgrade_map(..)`. A method would interfere with methods of
+    /// the same name on the contents of the locked data.
+    ///
+    /// This is equivalent to a combination of asynchronous [`RwLockWriteGuard::map`] and [`RwLockWriteGuard::downgrade`]
+    /// from the [`parking_lot` crate].
+    ///
+    /// Inside of `f`, you retain exclusive access to the data, despite only being given a `&T`. Handing out a
+    /// `&mut T` would result in unsoundness, as you could use interior mutability.
+    ///
+    /// [`RwLockMappedWriteGuard`]: struct@crate::sync::RwLockMappedWriteGuard
+    /// [`RwLockWriteGuard::map`]: https://docs.rs/lock_api/latest/lock_api/struct.RwLockWriteGuard.html#method.map
+    /// [`RwLockWriteGuard::downgrade`]: https://docs.rs/lock_api/latest/lock_api/struct.RwLockWriteGuard.html#method.downgrade
+    /// [`parking_lot` crate]: https://crates.io/crates/parking_lot
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::sync::{RwLock, RwLockWriteGuard};
+    ///
+    /// #[derive(Debug, Clone, Copy, PartialEq, Eq)]
+    /// struct Foo(u32);
+    ///
+    /// # #[tokio::main]
+    /// # async fn main() {
+    /// let lock = RwLock::new(Foo(1));
+    ///
+    /// let mapped = RwLockWriteGuard::downgrade_map(lock.write().await, |f| &f.0);
+    /// let foo = lock.read().await;
+    /// assert_eq!(foo.0, *mapped);
+    /// # }
+    /// ```
+    #[inline]
+    pub fn downgrade_map<F, U: ?Sized>(this: Self, f: F) -> RwLockReadGuard<'a, U>
+    where
+        F: FnOnce(&T) -> &U,
+    {
+        let data = f(&*this) as *const U;
+        let this = this.skip_drop();
+        let guard = RwLockReadGuard {
+            s: this.s,
+            data,
+            marker: PhantomData,
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: this.resource_span,
+        };
+
+        // Release all but one of the permits held by the write guard
+        let to_release = (this.permits_acquired - 1) as usize;
+        this.s.release(to_release);
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        guard.resource_span.in_scope(|| {
+            tracing::trace!(
+            target: "runtime::resource::state_update",
+            write_locked = false,
+            write_locked.op = "override",
+            )
+        });
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        guard.resource_span.in_scope(|| {
+            tracing::trace!(
+            target: "runtime::resource::state_update",
+            current_readers = 1,
+            current_readers.op = "add",
+            )
+        });
+
+        guard
+    }
+
+    /// Attempts to make a new [`RwLockMappedWriteGuard`] for a component of
     /// the locked data. The original guard is returned if the closure returns
     /// `None`.
     ///
@@ -127,18 +230,102 @@ impl<'a, T: ?Sized> RwLockWriteGuard<'a, T> {
             Some(data) => data as *mut U,
             None => return Err(this),
         };
-        let s = this.s;
-        let permits_acquired = this.permits_acquired;
-        // NB: Forget to avoid drop impl from being called.
-        mem::forget(this);
+        let this = this.skip_drop();
+
         Ok(RwLockMappedWriteGuard {
-            permits_acquired,
-            s,
+            permits_acquired: this.permits_acquired,
+            s: this.s,
             data,
-            marker: marker::PhantomData,
+            marker: PhantomData,
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: this.resource_span,
         })
     }
 
+    /// Attempts to make a new [`RwLockReadGuard`] for a component of
+    /// the locked data. The original guard is returned if the closure returns
+    /// `None`.
+    ///
+    /// This operation cannot fail as the `RwLockWriteGuard` passed in already
+    /// locked the data.
+    ///
+    /// This is an associated function that needs to be
+    /// used as `RwLockWriteGuard::try_downgrade_map(...)`. A method would interfere with
+    /// methods of the same name on the contents of the locked data.
+    ///
+    /// This is equivalent to a combination of asynchronous [`RwLockWriteGuard::try_map`] and [`RwLockWriteGuard::downgrade`]
+    /// from the [`parking_lot` crate].
+    ///
+    /// Inside of `f`, you retain exclusive access to the data, despite only being given a `&T`. Handing out a
+    /// `&mut T` would result in unsoundness, as you could use interior mutability.
+    ///
+    /// If this function returns `Err(...)`, the lock is never unlocked nor downgraded.
+    ///
+    /// [`RwLockMappedWriteGuard`]: struct@crate::sync::RwLockMappedWriteGuard
+    /// [`RwLockWriteGuard::map`]: https://docs.rs/lock_api/latest/lock_api/struct.RwLockWriteGuard.html#method.map
+    /// [`RwLockWriteGuard::downgrade`]: https://docs.rs/lock_api/latest/lock_api/struct.RwLockWriteGuard.html#method.downgrade
+    /// [`parking_lot` crate]: https://crates.io/crates/parking_lot
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::sync::{RwLock, RwLockWriteGuard};
+    ///
+    /// #[derive(Debug, Clone, Copy, PartialEq, Eq)]
+    /// struct Foo(u32);
+    ///
+    /// # #[tokio::main]
+    /// # async fn main() {
+    /// let lock = RwLock::new(Foo(1));
+    ///
+    /// let guard = RwLockWriteGuard::try_downgrade_map(lock.write().await, |f| Some(&f.0)).expect("should not fail");
+    /// let foo = lock.read().await;
+    /// assert_eq!(foo.0, *guard);
+    /// # }
+    /// ```
+    #[inline]
+    pub fn try_downgrade_map<F, U: ?Sized>(this: Self, f: F) -> Result<RwLockReadGuard<'a, U>, Self>
+    where
+        F: FnOnce(&T) -> Option<&U>,
+    {
+        let data = match f(&*this) {
+            Some(data) => data as *const U,
+            None => return Err(this),
+        };
+        let this = this.skip_drop();
+        let guard = RwLockReadGuard {
+            s: this.s,
+            data,
+            marker: PhantomData,
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: this.resource_span,
+        };
+
+        // Release all but one of the permits held by the write guard
+        let to_release = (this.permits_acquired - 1) as usize;
+        this.s.release(to_release);
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        guard.resource_span.in_scope(|| {
+            tracing::trace!(
+            target: "runtime::resource::state_update",
+            write_locked = false,
+            write_locked.op = "override",
+            )
+        });
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        guard.resource_span.in_scope(|| {
+            tracing::trace!(
+            target: "runtime::resource::state_update",
+            current_readers = 1,
+            current_readers.op = "add",
+            )
+        });
+
+        Ok(guard)
+    }
+
     /// Converts this `RwLockWriteGuard` into an `RwLockMappedWriteGuard`. This
     /// method can be used to store a non-mapped guard in a struct field that
     /// expects a mapped guard.
@@ -187,17 +374,38 @@ impl<'a, T: ?Sized> RwLockWriteGuard<'a, T> {
     ///
     /// [`RwLock`]: struct@crate::sync::RwLock
     pub fn downgrade(self) -> RwLockReadGuard<'a, T> {
-        let RwLockWriteGuard { s, data, .. } = self;
+        let this = self.skip_drop();
+        let guard = RwLockReadGuard {
+            s: this.s,
+            data: this.data,
+            marker: PhantomData,
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: this.resource_span,
+        };
 
         // Release all but one of the permits held by the write guard
-        s.release((self.permits_acquired - 1) as usize);
-        // NB: Forget to avoid drop impl from being called.
-        mem::forget(self);
-        RwLockReadGuard {
-            s,
-            data,
-            marker: marker::PhantomData,
-        }
+        let to_release = (this.permits_acquired - 1) as usize;
+        this.s.release(to_release);
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        guard.resource_span.in_scope(|| {
+            tracing::trace!(
+            target: "runtime::resource::state_update",
+            write_locked = false,
+            write_locked.op = "override",
+            )
+        });
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        guard.resource_span.in_scope(|| {
+            tracing::trace!(
+            target: "runtime::resource::state_update",
+            current_readers = 1,
+            current_readers.op = "add",
+            )
+        });
+
+        guard
     }
 }
 
@@ -236,5 +444,14 @@ where
 impl<'a, T: ?Sized> Drop for RwLockWriteGuard<'a, T> {
     fn drop(&mut self) {
         self.s.release(self.permits_acquired as usize);
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        self.resource_span.in_scope(|| {
+            tracing::trace!(
+            target: "runtime::resource::state_update",
+            write_locked = false,
+            write_locked.op = "override",
+            )
+        });
     }
 }
diff --git a/vendor/tokio/src/sync/rwlock/write_guard_mapped.rs b/vendor/tokio/src/sync/rwlock/write_guard_mapped.rs
index 9c5b1e7c3..7705189e7 100644
--- a/vendor/tokio/src/sync/rwlock/write_guard_mapped.rs
+++ b/vendor/tokio/src/sync/rwlock/write_guard_mapped.rs
@@ -1,8 +1,6 @@
 use crate::sync::batch_semaphore::Semaphore;
-use std::fmt;
-use std::marker;
-use std::mem;
-use std::ops;
+use std::marker::PhantomData;
+use std::{fmt, mem, ops};
 
 /// RAII structure used to release the exclusive write access of a lock when
 /// dropped.
@@ -13,15 +11,42 @@ use std::ops;
 ///
 /// [mapping]: method@crate::sync::RwLockWriteGuard::map
 /// [`RwLockWriteGuard`]: struct@crate::sync::RwLockWriteGuard
+#[clippy::has_significant_drop]
 pub struct RwLockMappedWriteGuard<'a, T: ?Sized> {
+    // When changing the fields in this struct, make sure to update the
+    // `skip_drop` method.
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    pub(super) resource_span: tracing::Span,
     pub(super) permits_acquired: u32,
     pub(super) s: &'a Semaphore,
     pub(super) data: *mut T,
-    pub(super) marker: marker::PhantomData<&'a mut T>,
+    pub(super) marker: PhantomData<&'a mut T>,
+}
+
+#[allow(dead_code)] // Unused fields are still used in Drop.
+struct Inner<'a, T: ?Sized> {
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    resource_span: tracing::Span,
+    permits_acquired: u32,
+    s: &'a Semaphore,
+    data: *mut T,
 }
 
 impl<'a, T: ?Sized> RwLockMappedWriteGuard<'a, T> {
-    /// Make a new `RwLockMappedWriteGuard` for a component of the locked data.
+    fn skip_drop(self) -> Inner<'a, T> {
+        let me = mem::ManuallyDrop::new(self);
+        // SAFETY: This duplicates the values in every field of the guard, then
+        // forgets the originals, so in the end no value is duplicated.
+        Inner {
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: unsafe { std::ptr::read(&me.resource_span) },
+            permits_acquired: me.permits_acquired,
+            s: me.s,
+            data: me.data,
+        }
+    }
+
+    /// Makes a new `RwLockMappedWriteGuard` for a component of the locked data.
     ///
     /// This operation cannot fail as the `RwLockMappedWriteGuard` passed in already
     /// locked the data.
@@ -62,15 +87,15 @@ impl<'a, T: ?Sized> RwLockMappedWriteGuard<'a, T> {
         F: FnOnce(&mut T) -> &mut U,
     {
         let data = f(&mut *this) as *mut U;
-        let s = this.s;
-        let permits_acquired = this.permits_acquired;
-        // NB: Forget to avoid drop impl from being called.
-        mem::forget(this);
+        let this = this.skip_drop();
+
         RwLockMappedWriteGuard {
-            permits_acquired,
-            s,
+            permits_acquired: this.permits_acquired,
+            s: this.s,
             data,
-            marker: marker::PhantomData,
+            marker: PhantomData,
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: this.resource_span,
         }
     }
 
@@ -124,17 +149,20 @@ impl<'a, T: ?Sized> RwLockMappedWriteGuard<'a, T> {
             Some(data) => data as *mut U,
             None => return Err(this),
         };
-        let s = this.s;
-        let permits_acquired = this.permits_acquired;
-        // NB: Forget to avoid drop impl from being called.
-        mem::forget(this);
+        let this = this.skip_drop();
+
         Ok(RwLockMappedWriteGuard {
-            permits_acquired,
-            s,
+            permits_acquired: this.permits_acquired,
+            s: this.s,
             data,
-            marker: marker::PhantomData,
+            marker: PhantomData,
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span: this.resource_span,
         })
     }
+
+    // Note: No `downgrade`, `downgrade_map` nor `try_downgrade_map` because they would be unsound, as we're already
+    //       potentially been mapped with internal mutability.
 }
 
 impl<T: ?Sized> ops::Deref for RwLockMappedWriteGuard<'_, T> {
@@ -172,5 +200,14 @@ where
 impl<'a, T: ?Sized> Drop for RwLockMappedWriteGuard<'a, T> {
     fn drop(&mut self) {
         self.s.release(self.permits_acquired as usize);
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        self.resource_span.in_scope(|| {
+            tracing::trace!(
+            target: "runtime::resource::state_update",
+            write_locked = false,
+            write_locked.op = "override",
+            )
+        });
     }
 }
diff --git a/vendor/tokio/src/sync/semaphore.rs b/vendor/tokio/src/sync/semaphore.rs
index 4b697a9bf..e679d0e6b 100644
--- a/vendor/tokio/src/sync/semaphore.rs
+++ b/vendor/tokio/src/sync/semaphore.rs
@@ -1,5 +1,7 @@
 use super::batch_semaphore as ll; // low level implementation
 use super::{AcquireError, TryAcquireError};
+#[cfg(all(tokio_unstable, feature = "tracing"))]
+use crate::util::trace;
 use std::sync::Arc;
 
 /// Counting semaphore performing asynchronous permit acquisition.
@@ -71,12 +73,14 @@ use std::sync::Arc;
 /// }
 /// ```
 ///
-/// [`PollSemaphore`]: https://docs.rs/tokio-util/0.6/tokio_util/sync/struct.PollSemaphore.html
+/// [`PollSemaphore`]: https://docs.rs/tokio-util/latest/tokio_util/sync/struct.PollSemaphore.html
 /// [`Semaphore::acquire_owned`]: crate::sync::Semaphore::acquire_owned
 #[derive(Debug)]
 pub struct Semaphore {
     /// The low level semaphore
     ll_sem: ll::Semaphore,
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    resource_span: tracing::Span,
 }
 
 /// A permit from the semaphore.
@@ -85,6 +89,7 @@ pub struct Semaphore {
 ///
 /// [`acquire`]: crate::sync::Semaphore::acquire()
 #[must_use]
+#[clippy::has_significant_drop]
 #[derive(Debug)]
 pub struct SemaphorePermit<'a> {
     sem: &'a Semaphore,
@@ -97,6 +102,7 @@ pub struct SemaphorePermit<'a> {
 ///
 /// [`acquire_owned`]: crate::sync::Semaphore::acquire_owned()
 #[must_use]
+#[clippy::has_significant_drop]
 #[derive(Debug)]
 pub struct OwnedSemaphorePermit {
     sem: Arc<Semaphore>,
@@ -119,10 +125,41 @@ fn bounds() {
 }
 
 impl Semaphore {
+    /// The maximum number of permits which a semaphore can hold. It is `usize::MAX >> 3`.
+    ///
+    /// Exceeding this limit typically results in a panic.
+    pub const MAX_PERMITS: usize = super::batch_semaphore::Semaphore::MAX_PERMITS;
+
     /// Creates a new semaphore with the initial number of permits.
+    ///
+    /// Panics if `permits` exceeds [`Semaphore::MAX_PERMITS`].
+    #[track_caller]
     pub fn new(permits: usize) -> Self {
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let resource_span = {
+            let location = std::panic::Location::caller();
+
+            tracing::trace_span!(
+                "runtime.resource",
+                concrete_type = "Semaphore",
+                kind = "Sync",
+                loc.file = location.file(),
+                loc.line = location.line(),
+                loc.col = location.column(),
+                inherits_child_attrs = true,
+            )
+        };
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let ll_sem = resource_span.in_scope(|| ll::Semaphore::new(permits));
+
+        #[cfg(any(not(tokio_unstable), not(feature = "tracing")))]
+        let ll_sem = ll::Semaphore::new(permits);
+
         Self {
-            ll_sem: ll::Semaphore::new(permits),
+            ll_sem,
+            #[cfg(all(tokio_unstable, feature = "tracing"))]
+            resource_span,
         }
     }
 
@@ -139,9 +176,16 @@ impl Semaphore {
     #[cfg(all(feature = "parking_lot", not(all(loom, test))))]
     #[cfg_attr(docsrs, doc(cfg(feature = "parking_lot")))]
     pub const fn const_new(permits: usize) -> Self {
-        Self {
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        return Self {
             ll_sem: ll::Semaphore::const_new(permits),
-        }
+            resource_span: tracing::Span::none(),
+        };
+
+        #[cfg(any(not(tokio_unstable), not(feature = "tracing")))]
+        return Self {
+            ll_sem: ll::Semaphore::const_new(permits),
+        };
     }
 
     /// Returns the current number of available permits.
@@ -151,7 +195,7 @@ impl Semaphore {
 
     /// Adds `n` new permits to the semaphore.
     ///
-    /// The maximum number of permits is `usize::MAX >> 3`, and this function will panic if the limit is exceeded.
+    /// The maximum number of permits is [`Semaphore::MAX_PERMITS`], and this function will panic if the limit is exceeded.
     pub fn add_permits(&self, n: usize) {
         self.ll_sem.release(n);
     }
@@ -191,9 +235,20 @@ impl Semaphore {
     /// [`AcquireError`]: crate::sync::AcquireError
     /// [`SemaphorePermit`]: crate::sync::SemaphorePermit
     pub async fn acquire(&self) -> Result<SemaphorePermit<'_>, AcquireError> {
-        self.ll_sem.acquire(1).await?;
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let inner = trace::async_op(
+            || self.ll_sem.acquire(1),
+            self.resource_span.clone(),
+            "Semaphore::acquire",
+            "poll",
+            true,
+        );
+        #[cfg(not(all(tokio_unstable, feature = "tracing")))]
+        let inner = self.ll_sem.acquire(1);
+
+        inner.await?;
         Ok(SemaphorePermit {
-            sem: &self,
+            sem: self,
             permits: 1,
         })
     }
@@ -227,9 +282,21 @@ impl Semaphore {
     /// [`AcquireError`]: crate::sync::AcquireError
     /// [`SemaphorePermit`]: crate::sync::SemaphorePermit
     pub async fn acquire_many(&self, n: u32) -> Result<SemaphorePermit<'_>, AcquireError> {
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        trace::async_op(
+            || self.ll_sem.acquire(n),
+            self.resource_span.clone(),
+            "Semaphore::acquire_many",
+            "poll",
+            true,
+        )
+        .await?;
+
+        #[cfg(not(all(tokio_unstable, feature = "tracing")))]
         self.ll_sem.acquire(n).await?;
+
         Ok(SemaphorePermit {
-            sem: &self,
+            sem: self,
             permits: n,
         })
     }
@@ -350,7 +417,18 @@ impl Semaphore {
     /// [`AcquireError`]: crate::sync::AcquireError
     /// [`OwnedSemaphorePermit`]: crate::sync::OwnedSemaphorePermit
     pub async fn acquire_owned(self: Arc<Self>) -> Result<OwnedSemaphorePermit, AcquireError> {
-        self.ll_sem.acquire(1).await?;
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let inner = trace::async_op(
+            || self.ll_sem.acquire(1),
+            self.resource_span.clone(),
+            "Semaphore::acquire_owned",
+            "poll",
+            true,
+        );
+        #[cfg(not(all(tokio_unstable, feature = "tracing")))]
+        let inner = self.ll_sem.acquire(1);
+
+        inner.await?;
         Ok(OwnedSemaphorePermit {
             sem: self,
             permits: 1,
@@ -403,7 +481,18 @@ impl Semaphore {
         self: Arc<Self>,
         n: u32,
     ) -> Result<OwnedSemaphorePermit, AcquireError> {
-        self.ll_sem.acquire(n).await?;
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let inner = trace::async_op(
+            || self.ll_sem.acquire(n),
+            self.resource_span.clone(),
+            "Semaphore::acquire_many_owned",
+            "poll",
+            true,
+        );
+        #[cfg(not(all(tokio_unstable, feature = "tracing")))]
+        let inner = self.ll_sem.acquire(n);
+
+        inner.await?;
         Ok(OwnedSemaphorePermit {
             sem: self,
             permits: n,
@@ -540,6 +629,25 @@ impl<'a> SemaphorePermit<'a> {
     pub fn forget(mut self) {
         self.permits = 0;
     }
+
+    /// Merge two [`SemaphorePermit`] instances together, consuming `other`
+    /// without releasing the permits it holds.
+    ///
+    /// Permits held by both `self` and `other` are released when `self` drops.
+    ///
+    /// # Panics
+    ///
+    /// This function panics if permits from different [`Semaphore`] instances
+    /// are merged.
+    #[track_caller]
+    pub fn merge(&mut self, mut other: Self) {
+        assert!(
+            std::ptr::eq(self.sem, other.sem),
+            "merging permits from different semaphore instances"
+        );
+        self.permits += other.permits;
+        other.permits = 0;
+    }
 }
 
 impl OwnedSemaphorePermit {
@@ -549,9 +657,33 @@ impl OwnedSemaphorePermit {
     pub fn forget(mut self) {
         self.permits = 0;
     }
+
+    /// Merge two [`OwnedSemaphorePermit`] instances together, consuming `other`
+    /// without releasing the permits it holds.
+    ///
+    /// Permits held by both `self` and `other` are released when `self` drops.
+    ///
+    /// # Panics
+    ///
+    /// This function panics if permits from different [`Semaphore`] instances
+    /// are merged.
+    #[track_caller]
+    pub fn merge(&mut self, mut other: Self) {
+        assert!(
+            Arc::ptr_eq(&self.sem, &other.sem),
+            "merging permits from different semaphore instances"
+        );
+        self.permits += other.permits;
+        other.permits = 0;
+    }
+
+    /// Returns the [`Semaphore`] from which this permit was acquired.
+    pub fn semaphore(&self) -> &Arc<Semaphore> {
+        &self.sem
+    }
 }
 
-impl<'a> Drop for SemaphorePermit<'_> {
+impl Drop for SemaphorePermit<'_> {
     fn drop(&mut self) {
         self.sem.add_permits(self.permits as usize);
     }
diff --git a/vendor/tokio/src/sync/task/atomic_waker.rs b/vendor/tokio/src/sync/task/atomic_waker.rs
index 8616007a3..13aba3544 100644
--- a/vendor/tokio/src/sync/task/atomic_waker.rs
+++ b/vendor/tokio/src/sync/task/atomic_waker.rs
@@ -1,9 +1,11 @@
 #![cfg_attr(any(loom, not(feature = "sync")), allow(dead_code, unreachable_pub))]
 
 use crate::loom::cell::UnsafeCell;
-use crate::loom::sync::atomic::{self, AtomicUsize};
+use crate::loom::hint;
+use crate::loom::sync::atomic::AtomicUsize;
 
 use std::fmt;
+use std::panic::{resume_unwind, AssertUnwindSafe, RefUnwindSafe, UnwindSafe};
 use std::sync::atomic::Ordering::{AcqRel, Acquire, Release};
 use std::task::Waker;
 
@@ -27,6 +29,9 @@ pub(crate) struct AtomicWaker {
     waker: UnsafeCell<Option<Waker>>,
 }
 
+impl RefUnwindSafe for AtomicWaker {}
+impl UnwindSafe for AtomicWaker {}
+
 // `AtomicWaker` is a multi-consumer, single-producer transfer cell. The cell
 // stores a `Waker` value produced by calls to `register` and many threads can
 // race to take the waker by calling `wake`.
@@ -84,7 +89,7 @@ pub(crate) struct AtomicWaker {
 // back to `WAITING`. This transition must succeed as, at this point, the state
 // cannot be transitioned by another thread.
 //
-// If the thread is unable to obtain the lock, the `WAKING` bit is still.
+// If the thread is unable to obtain the lock, the `WAKING` bit is still set.
 // This is because it has either been set by the current thread but the previous
 // value included the `REGISTERING` bit **or** a concurrent thread is in the
 // `WAKING` critical section. Either way, no action must be taken.
@@ -123,7 +128,7 @@ pub(crate) struct AtomicWaker {
 //    Thread A still holds the `wake` lock, the call to `register` will result
 //    in the task waking itself and get scheduled again.
 
-/// Idle state
+/// Idle state.
 const WAITING: usize = 0;
 
 /// A new waker value is being registered with the `AtomicWaker` cell.
@@ -171,6 +176,10 @@ impl AtomicWaker {
     where
         W: WakerRef,
     {
+        fn catch_unwind<F: FnOnce() -> R, R>(f: F) -> std::thread::Result<R> {
+            std::panic::catch_unwind(AssertUnwindSafe(f))
+        }
+
         match self
             .state
             .compare_exchange(WAITING, REGISTERING, Acquire, Acquire)
@@ -178,8 +187,24 @@ impl AtomicWaker {
         {
             WAITING => {
                 unsafe {
-                    // Locked acquired, update the waker cell
-                    self.waker.with_mut(|t| *t = Some(waker.into_waker()));
+                    // If `into_waker` panics (because it's code outside of
+                    // AtomicWaker) we need to prime a guard that is called on
+                    // unwind to restore the waker to a WAITING state. Otherwise
+                    // any future calls to register will incorrectly be stuck
+                    // believing it's being updated by someone else.
+                    let new_waker_or_panic = catch_unwind(move || waker.into_waker());
+
+                    // Set the field to contain the new waker, or if
+                    // `into_waker` panicked, leave the old value.
+                    let mut maybe_panic = None;
+                    let mut old_waker = None;
+                    match new_waker_or_panic {
+                        Ok(new_waker) => {
+                            old_waker = self.waker.with_mut(|t| (*t).take());
+                            self.waker.with_mut(|t| *t = Some(new_waker));
+                        }
+                        Err(panic) => maybe_panic = Some(panic),
+                    }
 
                     // Release the lock. If the state transitioned to include
                     // the `WAKING` bit, this means that a wake has been
@@ -193,39 +218,71 @@ impl AtomicWaker {
                         .compare_exchange(REGISTERING, WAITING, AcqRel, Acquire);
 
                     match res {
-                        Ok(_) => {}
+                        Ok(_) => {
+                            // We don't want to give the caller the panic if it
+                            // was someone else who put in that waker.
+                            let _ = catch_unwind(move || {
+                                drop(old_waker);
+                            });
+                        }
                         Err(actual) => {
                             // This branch can only be reached if a
                             // concurrent thread called `wake`. In this
                             // case, `actual` **must** be `REGISTERING |
-                            // `WAKING`.
+                            // WAKING`.
                             debug_assert_eq!(actual, REGISTERING | WAKING);
 
                             // Take the waker to wake once the atomic operation has
                             // completed.
-                            let waker = self.waker.with_mut(|t| (*t).take()).unwrap();
+                            let mut waker = self.waker.with_mut(|t| (*t).take());
 
                             // Just swap, because no one could change state
                             // while state == `Registering | `Waking`
                             self.state.swap(WAITING, AcqRel);
 
-                            // The atomic swap was complete, now
-                            // wake the waker and return.
-                            waker.wake();
+                            // If `into_waker` panicked, then the waker in the
+                            // waker slot is actually the old waker.
+                            if maybe_panic.is_some() {
+                                old_waker = waker.take();
+                            }
+
+                            // We don't want to give the caller the panic if it
+                            // was someone else who put in that waker.
+                            if let Some(old_waker) = old_waker {
+                                let _ = catch_unwind(move || {
+                                    old_waker.wake();
+                                });
+                            }
+
+                            // The atomic swap was complete, now wake the waker
+                            // and return.
+                            //
+                            // If this panics, we end up in a consumed state and
+                            // return the panic to the caller.
+                            if let Some(waker) = waker {
+                                debug_assert!(maybe_panic.is_none());
+                                waker.wake();
+                            }
                         }
                     }
+
+                    if let Some(panic) = maybe_panic {
+                        // If `into_waker` panicked, return the panic to the caller.
+                        resume_unwind(panic);
+                    }
                 }
             }
             WAKING => {
                 // Currently in the process of waking the task, i.e.,
                 // `wake` is currently being called on the old waker.
                 // So, we call wake on the new waker.
+                //
+                // If this panics, someone else is responsible for restoring the
+                // state of the waker.
                 waker.wake();
 
                 // This is equivalent to a spin lock, so use a spin hint.
-                // TODO: once we bump MSRV to 1.49+, use `hint::spin_loop` instead.
-                #[allow(deprecated)]
-                atomic::spin_loop_hint();
+                hint::spin_loop();
             }
             state => {
                 // In this case, a concurrent thread is holding the
@@ -245,6 +302,8 @@ impl AtomicWaker {
     /// If `register` has not been called yet, then this does nothing.
     pub(crate) fn wake(&self) {
         if let Some(waker) = self.take_waker() {
+            // If wake panics, we've consumed the waker which is a legitimate
+            // outcome.
             waker.wake();
         }
     }
diff --git a/vendor/tokio/src/sync/tests/atomic_waker.rs b/vendor/tokio/src/sync/tests/atomic_waker.rs
index c832d62e9..8ebfb915f 100644
--- a/vendor/tokio/src/sync/tests/atomic_waker.rs
+++ b/vendor/tokio/src/sync/tests/atomic_waker.rs
@@ -4,7 +4,7 @@ use tokio_test::task;
 use std::task::Waker;
 
 trait AssertSend: Send {}
-trait AssertSync: Send {}
+trait AssertSync: Sync {}
 
 impl AssertSend for AtomicWaker {}
 impl AssertSync for AtomicWaker {}
@@ -12,6 +12,9 @@ impl AssertSync for AtomicWaker {}
 impl AssertSend for Waker {}
 impl AssertSync for Waker {}
 
+#[cfg(tokio_wasm_not_wasi)]
+use wasm_bindgen_test::wasm_bindgen_test as test;
+
 #[test]
 fn basic_usage() {
     let mut waker = task::spawn(AtomicWaker::new());
@@ -32,3 +35,43 @@ fn wake_without_register() {
 
     assert!(!waker.is_woken());
 }
+
+#[test]
+#[cfg(not(tokio_wasm))] // wasm currently doesn't support unwinding
+fn atomic_waker_panic_safe() {
+    use std::panic;
+    use std::ptr;
+    use std::task::{RawWaker, RawWakerVTable, Waker};
+
+    static PANICKING_VTABLE: RawWakerVTable = RawWakerVTable::new(
+        |_| panic!("clone"),
+        |_| unimplemented!("wake"),
+        |_| unimplemented!("wake_by_ref"),
+        |_| (),
+    );
+
+    static NONPANICKING_VTABLE: RawWakerVTable = RawWakerVTable::new(
+        |_| RawWaker::new(ptr::null(), &NONPANICKING_VTABLE),
+        |_| unimplemented!("wake"),
+        |_| unimplemented!("wake_by_ref"),
+        |_| (),
+    );
+
+    let panicking = unsafe { Waker::from_raw(RawWaker::new(ptr::null(), &PANICKING_VTABLE)) };
+    let nonpanicking = unsafe { Waker::from_raw(RawWaker::new(ptr::null(), &NONPANICKING_VTABLE)) };
+
+    let atomic_waker = AtomicWaker::new();
+
+    let panicking = panic::AssertUnwindSafe(&panicking);
+
+    let result = panic::catch_unwind(|| {
+        let panic::AssertUnwindSafe(panicking) = panicking;
+        atomic_waker.register_by_ref(panicking);
+    });
+
+    assert!(result.is_err());
+    assert!(atomic_waker.take_waker().is_none());
+
+    atomic_waker.register_by_ref(&nonpanicking);
+    assert!(atomic_waker.take_waker().is_some());
+}
diff --git a/vendor/tokio/src/sync/tests/loom_atomic_waker.rs b/vendor/tokio/src/sync/tests/loom_atomic_waker.rs
index c148bcbe1..f8bae65d1 100644
--- a/vendor/tokio/src/sync/tests/loom_atomic_waker.rs
+++ b/vendor/tokio/src/sync/tests/loom_atomic_waker.rs
@@ -43,3 +43,58 @@ fn basic_notification() {
         }));
     });
 }
+
+#[test]
+fn test_panicky_waker() {
+    use std::panic;
+    use std::ptr;
+    use std::task::{RawWaker, RawWakerVTable, Waker};
+
+    static PANICKING_VTABLE: RawWakerVTable =
+        RawWakerVTable::new(|_| panic!("clone"), |_| (), |_| (), |_| ());
+
+    let panicking = unsafe { Waker::from_raw(RawWaker::new(ptr::null(), &PANICKING_VTABLE)) };
+
+    // If you're working with this test (and I sure hope you never have to!),
+    // uncomment the following section because there will be a lot of panics
+    // which would otherwise log.
+    //
+    // We can't however leaved it uncommented, because it's global.
+    // panic::set_hook(Box::new(|_| ()));
+
+    const NUM_NOTIFY: usize = 2;
+
+    loom::model(move || {
+        let chan = Arc::new(Chan {
+            num: AtomicUsize::new(0),
+            task: AtomicWaker::new(),
+        });
+
+        for _ in 0..NUM_NOTIFY {
+            let chan = chan.clone();
+
+            thread::spawn(move || {
+                chan.num.fetch_add(1, Relaxed);
+                chan.task.wake();
+            });
+        }
+
+        // Note: this panic should have no effect on the overall state of the
+        // waker and it should proceed as normal.
+        //
+        // A thread above might race to flag a wakeup, and a WAKING state will
+        // be preserved if this expected panic races with that so the below
+        // procedure should be allowed to continue uninterrupted.
+        let _ = panic::catch_unwind(|| chan.task.register_by_ref(&panicking));
+
+        block_on(poll_fn(move |cx| {
+            chan.task.register_by_ref(cx.waker());
+
+            if NUM_NOTIFY == chan.num.load(Relaxed) {
+                return Ready(());
+            }
+
+            Pending
+        }));
+    });
+}
diff --git a/vendor/tokio/src/sync/tests/loom_mpsc.rs b/vendor/tokio/src/sync/tests/loom_mpsc.rs
index c12313bd3..f165e7076 100644
--- a/vendor/tokio/src/sync/tests/loom_mpsc.rs
+++ b/vendor/tokio/src/sync/tests/loom_mpsc.rs
@@ -132,3 +132,59 @@ fn dropping_unbounded_tx() {
         assert!(v.is_none());
     });
 }
+
+#[test]
+fn try_recv() {
+    loom::model(|| {
+        use crate::sync::{mpsc, Semaphore};
+        use loom::sync::{Arc, Mutex};
+
+        const PERMITS: usize = 2;
+        const TASKS: usize = 2;
+        const CYCLES: usize = 1;
+
+        struct Context {
+            sem: Arc<Semaphore>,
+            tx: mpsc::Sender<()>,
+            rx: Mutex<mpsc::Receiver<()>>,
+        }
+
+        fn run(ctx: &Context) {
+            block_on(async {
+                let permit = ctx.sem.acquire().await;
+                assert_ok!(ctx.rx.lock().unwrap().try_recv());
+                crate::task::yield_now().await;
+                assert_ok!(ctx.tx.clone().try_send(()));
+                drop(permit);
+            });
+        }
+
+        let (tx, rx) = mpsc::channel(PERMITS);
+        let sem = Arc::new(Semaphore::new(PERMITS));
+        let ctx = Arc::new(Context {
+            sem,
+            tx,
+            rx: Mutex::new(rx),
+        });
+
+        for _ in 0..PERMITS {
+            assert_ok!(ctx.tx.clone().try_send(()));
+        }
+
+        let mut ths = Vec::new();
+
+        for _ in 0..TASKS {
+            let ctx = ctx.clone();
+
+            ths.push(thread::spawn(move || {
+                run(&ctx);
+            }));
+        }
+
+        run(&ctx);
+
+        for th in ths {
+            th.join().unwrap();
+        }
+    });
+}
diff --git a/vendor/tokio/src/sync/tests/loom_notify.rs b/vendor/tokio/src/sync/tests/loom_notify.rs
index d484a7581..a4ded1d35 100644
--- a/vendor/tokio/src/sync/tests/loom_notify.rs
+++ b/vendor/tokio/src/sync/tests/loom_notify.rs
@@ -4,6 +4,11 @@ use loom::future::block_on;
 use loom::sync::Arc;
 use loom::thread;
 
+use tokio_test::{assert_pending, assert_ready};
+
+/// `util::wake_list::NUM_WAKERS`
+const WAKE_LIST_SIZE: usize = 32;
+
 #[test]
 fn notify_one() {
     loom::model(|| {
@@ -138,3 +143,189 @@ fn notify_drop() {
         th2.join().unwrap();
     });
 }
+
+/// Polls two `Notified` futures and checks if poll results are consistent
+/// with each other. If the first future is notified by a `notify_waiters`
+/// call, then the second one must be notified as well.
+#[test]
+fn notify_waiters_poll_consistency() {
+    fn notify_waiters_poll_consistency_variant(poll_setting: [bool; 2]) {
+        let notify = Arc::new(Notify::new());
+        let mut notified = [
+            tokio_test::task::spawn(notify.notified()),
+            tokio_test::task::spawn(notify.notified()),
+        ];
+        for i in 0..2 {
+            if poll_setting[i] {
+                assert_pending!(notified[i].poll());
+            }
+        }
+
+        let tx = notify.clone();
+        let th = thread::spawn(move || {
+            tx.notify_waiters();
+        });
+
+        let res1 = notified[0].poll();
+        let res2 = notified[1].poll();
+
+        // If res1 is ready, then res2 must also be ready.
+        assert!(res1.is_pending() || res2.is_ready());
+
+        th.join().unwrap();
+    }
+
+    // We test different scenarios in which pending futures had or had not
+    // been polled before the call to `notify_waiters`.
+    loom::model(|| notify_waiters_poll_consistency_variant([false, false]));
+    loom::model(|| notify_waiters_poll_consistency_variant([true, false]));
+    loom::model(|| notify_waiters_poll_consistency_variant([false, true]));
+    loom::model(|| notify_waiters_poll_consistency_variant([true, true]));
+}
+
+/// Polls two `Notified` futures and checks if poll results are consistent
+/// with each other. If the first future is notified by a `notify_waiters`
+/// call, then the second one must be notified as well.
+///
+/// Here we also add other `Notified` futures in between to force the two
+/// tested futures to end up in different chunks.
+#[test]
+fn notify_waiters_poll_consistency_many() {
+    fn notify_waiters_poll_consistency_many_variant(order: [usize; 2]) {
+        let notify = Arc::new(Notify::new());
+
+        let mut futs = (0..WAKE_LIST_SIZE + 1)
+            .map(|_| tokio_test::task::spawn(notify.notified()))
+            .collect::<Vec<_>>();
+
+        assert_pending!(futs[order[0]].poll());
+        for i in 2..futs.len() {
+            assert_pending!(futs[i].poll());
+        }
+        assert_pending!(futs[order[1]].poll());
+
+        let tx = notify.clone();
+        let th = thread::spawn(move || {
+            tx.notify_waiters();
+        });
+
+        let res1 = futs[0].poll();
+        let res2 = futs[1].poll();
+
+        // If res1 is ready, then res2 must also be ready.
+        assert!(res1.is_pending() || res2.is_ready());
+
+        th.join().unwrap();
+    }
+
+    // We test different scenarios in which futures are polled in different order.
+    loom::model(|| notify_waiters_poll_consistency_many_variant([0, 1]));
+    loom::model(|| notify_waiters_poll_consistency_many_variant([1, 0]));
+}
+
+/// Checks if a call to `notify_waiters` is observed as atomic when combined
+/// with a concurrent call to `notify_one`.
+#[test]
+fn notify_waiters_is_atomic() {
+    fn notify_waiters_is_atomic_variant(tested_fut_index: usize) {
+        let notify = Arc::new(Notify::new());
+
+        let mut futs = (0..WAKE_LIST_SIZE + 1)
+            .map(|_| tokio_test::task::spawn(notify.notified()))
+            .collect::<Vec<_>>();
+
+        for fut in &mut futs {
+            assert_pending!(fut.poll());
+        }
+
+        let tx = notify.clone();
+        let th = thread::spawn(move || {
+            tx.notify_waiters();
+        });
+
+        block_on(async {
+            // If awaiting one of the futures completes, then we should be
+            // able to assume that all pending futures are notified. Therefore
+            // a notification from a subsequent `notify_one` call should not
+            // be consumed by an old future.
+            futs.remove(tested_fut_index).await;
+
+            let mut new_fut = tokio_test::task::spawn(notify.notified());
+            assert_pending!(new_fut.poll());
+
+            notify.notify_one();
+
+            // `new_fut` must consume the notification from `notify_one`.
+            assert_ready!(new_fut.poll());
+        });
+
+        th.join().unwrap();
+    }
+
+    // We test different scenarios in which the tested future is at the beginning
+    // or at the end of the waiters queue used by `Notify`.
+    loom::model(|| notify_waiters_is_atomic_variant(0));
+    loom::model(|| notify_waiters_is_atomic_variant(32));
+}
+
+/// Checks if a single call to `notify_waiters` does not get through two `Notified`
+/// futures created and awaited sequentially like this:
+/// ```ignore
+/// notify.notified().await;
+/// notify.notified().await;
+/// ```
+#[test]
+fn notify_waiters_sequential_notified_await() {
+    use crate::sync::oneshot;
+
+    loom::model(|| {
+        let notify = Arc::new(Notify::new());
+
+        let (tx_fst, rx_fst) = oneshot::channel();
+        let (tx_snd, rx_snd) = oneshot::channel();
+
+        let receiver = thread::spawn({
+            let notify = notify.clone();
+            move || {
+                block_on(async {
+                    // Poll the first `Notified` to put it as the first waiter
+                    // in the queue.
+                    let mut first_notified = tokio_test::task::spawn(notify.notified());
+                    assert_pending!(first_notified.poll());
+
+                    // Create additional waiters to force `notify_waiters` to
+                    // release the lock at least once.
+                    let _task_pile = (0..WAKE_LIST_SIZE + 1)
+                        .map(|_| {
+                            let mut fut = tokio_test::task::spawn(notify.notified());
+                            assert_pending!(fut.poll());
+                            fut
+                        })
+                        .collect::<Vec<_>>();
+
+                    // We are ready for the notify_waiters call.
+                    tx_fst.send(()).unwrap();
+
+                    first_notified.await;
+
+                    // Poll the second `Notified` future to try to insert
+                    // it to the waiters queue.
+                    let mut second_notified = tokio_test::task::spawn(notify.notified());
+                    assert_pending!(second_notified.poll());
+
+                    // Wait for the `notify_waiters` to end and check if we
+                    // are woken up.
+                    rx_snd.await.unwrap();
+                    assert_pending!(second_notified.poll());
+                });
+            }
+        });
+
+        // Wait for the signal and call `notify_waiters`.
+        block_on(rx_fst).unwrap();
+        notify.notify_waiters();
+        tx_snd.send(()).unwrap();
+
+        receiver.join().unwrap();
+    });
+}
diff --git a/vendor/tokio/src/sync/tests/loom_watch.rs b/vendor/tokio/src/sync/tests/loom_watch.rs
index c575b5b66..51589cd80 100644
--- a/vendor/tokio/src/sync/tests/loom_watch.rs
+++ b/vendor/tokio/src/sync/tests/loom_watch.rs
@@ -2,6 +2,7 @@ use crate::sync::watch;
 
 use loom::future::block_on;
 use loom::thread;
+use std::sync::Arc;
 
 #[test]
 fn smoke() {
@@ -34,3 +35,56 @@ fn smoke() {
         th.join().unwrap();
     })
 }
+
+#[test]
+fn wait_for_test() {
+    loom::model(move || {
+        let (tx, mut rx) = watch::channel(false);
+
+        let tx_arc = Arc::new(tx);
+        let tx1 = tx_arc.clone();
+        let tx2 = tx_arc.clone();
+
+        let th1 = thread::spawn(move || {
+            for _ in 0..2 {
+                tx1.send_modify(|_x| {});
+            }
+        });
+
+        let th2 = thread::spawn(move || {
+            tx2.send(true).unwrap();
+        });
+
+        assert_eq!(*block_on(rx.wait_for(|x| *x)).unwrap(), true);
+
+        th1.join().unwrap();
+        th2.join().unwrap();
+    });
+}
+
+#[test]
+fn wait_for_returns_correct_value() {
+    loom::model(move || {
+        let (tx, mut rx) = watch::channel(0);
+
+        let jh = thread::spawn(move || {
+            tx.send(1).unwrap();
+            tx.send(2).unwrap();
+            tx.send(3).unwrap();
+        });
+
+        // Stop at the first value we are called at.
+        let mut stopped_at = usize::MAX;
+        let returned = *block_on(rx.wait_for(|x| {
+            stopped_at = *x;
+            true
+        }))
+        .unwrap();
+
+        // Check that it returned the same value as the one we returned
+        // `true` for.
+        assert_eq!(stopped_at, returned);
+
+        jh.join().unwrap();
+    });
+}
diff --git a/vendor/tokio/src/sync/tests/mod.rs b/vendor/tokio/src/sync/tests/mod.rs
index c5d560196..ee76418ac 100644
--- a/vendor/tokio/src/sync/tests/mod.rs
+++ b/vendor/tokio/src/sync/tests/mod.rs
@@ -1,5 +1,6 @@
 cfg_not_loom! {
     mod atomic_waker;
+    mod notify;
     mod semaphore_batch;
 }
 
diff --git a/vendor/tokio/src/sync/tests/notify.rs b/vendor/tokio/src/sync/tests/notify.rs
new file mode 100644
index 000000000..4b5989597
--- /dev/null
+++ b/vendor/tokio/src/sync/tests/notify.rs
@@ -0,0 +1,120 @@
+use crate::sync::Notify;
+use std::future::Future;
+use std::mem::ManuallyDrop;
+use std::sync::Arc;
+use std::task::{Context, RawWaker, RawWakerVTable, Waker};
+
+#[cfg(tokio_wasm_not_wasi)]
+use wasm_bindgen_test::wasm_bindgen_test as test;
+
+#[test]
+fn notify_clones_waker_before_lock() {
+    const VTABLE: &RawWakerVTable = &RawWakerVTable::new(clone_w, wake, wake_by_ref, drop_w);
+
+    unsafe fn clone_w(data: *const ()) -> RawWaker {
+        let arc = ManuallyDrop::new(Arc::<Notify>::from_raw(data as *const Notify));
+        // Or some other arbitrary code that shouldn't be executed while the
+        // Notify wait list is locked.
+        arc.notify_one();
+        let _arc_clone: ManuallyDrop<_> = arc.clone();
+        RawWaker::new(data, VTABLE)
+    }
+
+    unsafe fn drop_w(data: *const ()) {
+        let _ = Arc::<Notify>::from_raw(data as *const Notify);
+    }
+
+    unsafe fn wake(_data: *const ()) {
+        unreachable!()
+    }
+
+    unsafe fn wake_by_ref(_data: *const ()) {
+        unreachable!()
+    }
+
+    let notify = Arc::new(Notify::new());
+    let notify2 = notify.clone();
+
+    let waker =
+        unsafe { Waker::from_raw(RawWaker::new(Arc::into_raw(notify2) as *const _, VTABLE)) };
+    let mut cx = Context::from_waker(&waker);
+
+    let future = notify.notified();
+    pin!(future);
+
+    // The result doesn't matter, we're just testing that we don't deadlock.
+    let _ = future.poll(&mut cx);
+}
+
+#[cfg(panic = "unwind")]
+#[test]
+fn notify_waiters_handles_panicking_waker() {
+    use futures::task::ArcWake;
+
+    let notify = Arc::new(Notify::new());
+
+    struct PanickingWaker(Arc<Notify>);
+
+    impl ArcWake for PanickingWaker {
+        fn wake_by_ref(_arc_self: &Arc<Self>) {
+            panic!("waker panicked");
+        }
+    }
+
+    let bad_fut = notify.notified();
+    pin!(bad_fut);
+
+    let waker = futures::task::waker(Arc::new(PanickingWaker(notify.clone())));
+    let mut cx = Context::from_waker(&waker);
+    let _ = bad_fut.poll(&mut cx);
+
+    let mut futs = Vec::new();
+    for _ in 0..32 {
+        let mut fut = tokio_test::task::spawn(notify.notified());
+        assert!(fut.poll().is_pending());
+        futs.push(fut);
+    }
+
+    assert!(std::panic::catch_unwind(|| {
+        notify.notify_waiters();
+    })
+    .is_err());
+
+    for mut fut in futs {
+        assert!(fut.poll().is_ready());
+    }
+}
+
+#[test]
+fn notify_simple() {
+    let notify = Notify::new();
+
+    let mut fut1 = tokio_test::task::spawn(notify.notified());
+    assert!(fut1.poll().is_pending());
+
+    let mut fut2 = tokio_test::task::spawn(notify.notified());
+    assert!(fut2.poll().is_pending());
+
+    notify.notify_waiters();
+
+    assert!(fut1.poll().is_ready());
+    assert!(fut2.poll().is_ready());
+}
+
+#[test]
+#[cfg(not(tokio_wasm))]
+fn watch_test() {
+    let rt = crate::runtime::Builder::new_current_thread()
+        .build()
+        .unwrap();
+
+    rt.block_on(async {
+        let (tx, mut rx) = crate::sync::watch::channel(());
+
+        crate::spawn(async move {
+            let _ = tx.send(());
+        });
+
+        let _ = rx.changed().await;
+    });
+}
diff --git a/vendor/tokio/src/sync/tests/semaphore_batch.rs b/vendor/tokio/src/sync/tests/semaphore_batch.rs
index 9342cd1cb..85089cd22 100644
--- a/vendor/tokio/src/sync/tests/semaphore_batch.rs
+++ b/vendor/tokio/src/sync/tests/semaphore_batch.rs
@@ -1,6 +1,11 @@
 use crate::sync::batch_semaphore::Semaphore;
 use tokio_test::*;
 
+const MAX_PERMITS: usize = crate::sync::Semaphore::MAX_PERMITS;
+
+#[cfg(tokio_wasm_not_wasi)]
+use wasm_bindgen_test::wasm_bindgen_test as test;
+
 #[test]
 fn poll_acquire_one_available() {
     let s = Semaphore::new(100);
@@ -166,10 +171,15 @@ fn poll_acquire_one_zero_permits() {
 }
 
 #[test]
+fn max_permits_doesnt_panic() {
+    Semaphore::new(MAX_PERMITS);
+}
+
+#[test]
 #[should_panic]
+#[cfg(not(tokio_wasm))] // wasm currently doesn't support unwinding
 fn validates_max_permits() {
-    use std::usize;
-    Semaphore::new((usize::MAX >> 2) + 1);
+    Semaphore::new(MAX_PERMITS + 1);
 }
 
 #[test]
@@ -248,3 +258,32 @@ fn cancel_acquire_releases_permits() {
     assert_eq!(6, s.available_permits());
     assert_ok!(s.try_acquire(6));
 }
+
+#[test]
+fn release_permits_at_drop() {
+    use crate::sync::semaphore::*;
+    use futures::task::ArcWake;
+    use std::future::Future;
+    use std::sync::Arc;
+
+    let sem = Arc::new(Semaphore::new(1));
+
+    struct ReleaseOnDrop(Option<OwnedSemaphorePermit>);
+
+    impl ArcWake for ReleaseOnDrop {
+        fn wake_by_ref(_arc_self: &Arc<Self>) {}
+    }
+
+    let mut fut = Box::pin(async {
+        let _permit = sem.acquire().await.unwrap();
+    });
+
+    // Second iteration shouldn't deadlock.
+    for _ in 0..=1 {
+        let waker = futures::task::waker(Arc::new(ReleaseOnDrop(
+            sem.clone().try_acquire_owned().ok(),
+        )));
+        let mut cx = std::task::Context::from_waker(&waker);
+        assert!(fut.as_mut().poll(&mut cx).is_pending());
+    }
+}
diff --git a/vendor/tokio/src/sync/watch.rs b/vendor/tokio/src/sync/watch.rs
index 7852b0cb1..61049b71e 100644
--- a/vendor/tokio/src/sync/watch.rs
+++ b/vendor/tokio/src/sync/watch.rs
@@ -9,10 +9,10 @@
 //! # Usage
 //!
 //! [`channel`] returns a [`Sender`] / [`Receiver`] pair. These are the producer
-//! and sender halves of the channel. The channel is created with an initial
+//! and consumer halves of the channel. The channel is created with an initial
 //! value. The **latest** value stored in the channel is accessed with
 //! [`Receiver::borrow()`]. Awaiting [`Receiver::changed()`] waits for a new
-//! value to sent by the [`Sender`] half.
+//! value to be sent by the [`Sender`] half.
 //!
 //! # Examples
 //!
@@ -20,15 +20,15 @@
 //! use tokio::sync::watch;
 //!
 //! # async fn dox() -> Result<(), Box<dyn std::error::Error>> {
-//!     let (tx, mut rx) = watch::channel("hello");
+//! let (tx, mut rx) = watch::channel("hello");
 //!
-//!     tokio::spawn(async move {
-//!         while rx.changed().await.is_ok() {
-//!             println!("received = {:?}", *rx.borrow());
-//!         }
-//!     });
+//! tokio::spawn(async move {
+//!     while rx.changed().await.is_ok() {
+//!         println!("received = {:?}", *rx.borrow());
+//!     }
+//! });
 //!
-//!     tx.send("world")?;
+//! tx.send("world")?;
 //! # Ok(())
 //! # }
 //! ```
@@ -39,6 +39,9 @@
 //! when all [`Receiver`] handles have been dropped. This indicates that there
 //! is no further interest in the values being produced and work can be stopped.
 //!
+//! The value in the channel will not be dropped until the sender and all receivers
+//! have been dropped.
+//!
 //! # Thread safety
 //!
 //! Both [`Sender`] and [`Receiver`] are thread safe. They can be moved to other
@@ -56,9 +59,12 @@
 use crate::sync::notify::Notify;
 
 use crate::loom::sync::atomic::AtomicUsize;
-use crate::loom::sync::atomic::Ordering::{Relaxed, SeqCst};
+use crate::loom::sync::atomic::Ordering::Relaxed;
 use crate::loom::sync::{Arc, RwLock, RwLockReadGuard};
+use std::fmt;
+use std::mem;
 use std::ops;
+use std::panic;
 
 /// Receives values from the associated [`Sender`](struct@Sender).
 ///
@@ -74,7 +80,7 @@ pub struct Receiver<T> {
     shared: Arc<Shared<T>>,
 
     /// Last observed version
-    version: usize,
+    version: Version,
 }
 
 /// Sends values to the associated [`Receiver`](struct@Receiver).
@@ -85,60 +91,144 @@ pub struct Sender<T> {
     shared: Arc<Shared<T>>,
 }
 
-/// Returns a reference to the inner value
+/// Returns a reference to the inner value.
 ///
 /// Outstanding borrows hold a read lock on the inner value. This means that
-/// long lived borrows could cause the produce half to block. It is recommended
-/// to keep the borrow as short lived as possible.
+/// long-lived borrows could cause the producer half to block. It is recommended
+/// to keep the borrow as short-lived as possible. Additionally, if you are
+/// running in an environment that allows `!Send` futures, you must ensure that
+/// the returned `Ref` type is never held alive across an `.await` point,
+/// otherwise, it can lead to a deadlock.
+///
+/// The priority policy of the lock is dependent on the underlying lock
+/// implementation, and this type does not guarantee that any particular policy
+/// will be used. In particular, a producer which is waiting to acquire the lock
+/// in `send` might or might not block concurrent calls to `borrow`, e.g.:
+///
+/// <details><summary>Potential deadlock example</summary>
+///
+/// ```text
+/// // Task 1 (on thread A)    |  // Task 2 (on thread B)
+/// let _ref1 = rx.borrow();   |
+///                            |  // will block
+///                            |  let _ = tx.send(());
+/// // may deadlock            |
+/// let _ref2 = rx.borrow();   |
+/// ```
+/// </details>
 #[derive(Debug)]
 pub struct Ref<'a, T> {
     inner: RwLockReadGuard<'a, T>,
+    has_changed: bool,
+}
+
+impl<'a, T> Ref<'a, T> {
+    /// Indicates if the borrowed value is considered as _changed_ since the last
+    /// time it has been marked as seen.
+    ///
+    /// Unlike [`Receiver::has_changed()`], this method does not fail if the channel is closed.
+    ///
+    /// When borrowed from the [`Sender`] this function will always return `false`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::sync::watch;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let (tx, mut rx) = watch::channel("hello");
+    ///
+    ///     tx.send("goodbye").unwrap();
+    ///     // The sender does never consider the value as changed.
+    ///     assert!(!tx.borrow().has_changed());
+    ///
+    ///     // Drop the sender immediately, just for testing purposes.
+    ///     drop(tx);
+    ///
+    ///     // Even if the sender has already been dropped...
+    ///     assert!(rx.has_changed().is_err());
+    ///     // ...the modified value is still readable and detected as changed.
+    ///     assert_eq!(*rx.borrow(), "goodbye");
+    ///     assert!(rx.borrow().has_changed());
+    ///
+    ///     // Read the changed value and mark it as seen.
+    ///     {
+    ///         let received = rx.borrow_and_update();
+    ///         assert_eq!(*received, "goodbye");
+    ///         assert!(received.has_changed());
+    ///         // Release the read lock when leaving this scope.
+    ///     }
+    ///
+    ///     // Now the value has already been marked as seen and could
+    ///     // never be modified again (after the sender has been dropped).
+    ///     assert!(!rx.borrow().has_changed());
+    /// }
+    /// ```
+    pub fn has_changed(&self) -> bool {
+        self.has_changed
+    }
 }
 
-#[derive(Debug)]
 struct Shared<T> {
-    /// The most recent value
+    /// The most recent value.
     value: RwLock<T>,
 
-    /// The current version
+    /// The current version.
     ///
     /// The lowest bit represents a "closed" state. The rest of the bits
     /// represent the current version.
-    version: AtomicUsize,
+    state: AtomicState,
 
-    /// Tracks the number of `Receiver` instances
+    /// Tracks the number of `Receiver` instances.
     ref_count_rx: AtomicUsize,
 
     /// Notifies waiting receivers that the value changed.
-    notify_rx: Notify,
+    notify_rx: big_notify::BigNotify,
 
-    /// Notifies any task listening for `Receiver` dropped events
+    /// Notifies any task listening for `Receiver` dropped events.
     notify_tx: Notify,
 }
 
+impl<T: fmt::Debug> fmt::Debug for Shared<T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let state = self.state.load();
+        f.debug_struct("Shared")
+            .field("value", &self.value)
+            .field("version", &state.version())
+            .field("is_closed", &state.is_closed())
+            .field("ref_count_rx", &self.ref_count_rx)
+            .finish()
+    }
+}
+
 pub mod error {
-    //! Watch error types
+    //! Watch error types.
 
     use std::fmt;
 
     /// Error produced when sending a value fails.
-    #[derive(Debug)]
-    pub struct SendError<T> {
-        pub(crate) inner: T,
-    }
+    #[derive(PartialEq, Eq, Clone, Copy)]
+    pub struct SendError<T>(pub T);
 
     // ===== impl SendError =====
 
-    impl<T: fmt::Debug> fmt::Display for SendError<T> {
+    impl<T> fmt::Debug for SendError<T> {
+        fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+            f.debug_struct("SendError").finish_non_exhaustive()
+        }
+    }
+
+    impl<T> fmt::Display for SendError<T> {
         fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
             write!(fmt, "channel closed")
         }
     }
 
-    impl<T: fmt::Debug> std::error::Error for SendError<T> {}
+    impl<T> std::error::Error for SendError<T> {}
 
     /// Error produced when receiving a change notification.
-    #[derive(Debug)]
+    #[derive(Debug, Clone)]
     pub struct RecvError(pub(super) ());
 
     // ===== impl RecvError =====
@@ -152,7 +242,128 @@ pub mod error {
     impl std::error::Error for RecvError {}
 }
 
-const CLOSED: usize = 1;
+mod big_notify {
+    use super::*;
+    use crate::sync::notify::Notified;
+
+    // To avoid contention on the lock inside the `Notify`, we store multiple
+    // copies of it. Then, we use either circular access or randomness to spread
+    // out threads over different `Notify` objects.
+    //
+    // Some simple benchmarks show that randomness performs slightly better than
+    // circular access (probably due to contention on `next`), so we prefer to
+    // use randomness when Tokio is compiled with a random number generator.
+    //
+    // When the random number generator is not available, we fall back to
+    // circular access.
+
+    pub(super) struct BigNotify {
+        #[cfg(not(all(not(loom), feature = "sync", any(feature = "rt", feature = "macros"))))]
+        next: AtomicUsize,
+        inner: [Notify; 8],
+    }
+
+    impl BigNotify {
+        pub(super) fn new() -> Self {
+            Self {
+                #[cfg(not(all(
+                    not(loom),
+                    feature = "sync",
+                    any(feature = "rt", feature = "macros")
+                )))]
+                next: AtomicUsize::new(0),
+                inner: Default::default(),
+            }
+        }
+
+        pub(super) fn notify_waiters(&self) {
+            for notify in &self.inner {
+                notify.notify_waiters();
+            }
+        }
+
+        /// This function implements the case where randomness is not available.
+        #[cfg(not(all(not(loom), feature = "sync", any(feature = "rt", feature = "macros"))))]
+        pub(super) fn notified(&self) -> Notified<'_> {
+            let i = self.next.fetch_add(1, Relaxed) % 8;
+            self.inner[i].notified()
+        }
+
+        /// This function implements the case where randomness is available.
+        #[cfg(all(not(loom), feature = "sync", any(feature = "rt", feature = "macros")))]
+        pub(super) fn notified(&self) -> Notified<'_> {
+            let i = crate::runtime::context::thread_rng_n(8) as usize;
+            self.inner[i].notified()
+        }
+    }
+}
+
+use self::state::{AtomicState, Version};
+mod state {
+    use crate::loom::sync::atomic::AtomicUsize;
+    use crate::loom::sync::atomic::Ordering::SeqCst;
+
+    const CLOSED: usize = 1;
+
+    /// The version part of the state. The lowest bit is always zero.
+    #[derive(Copy, Clone, Debug, Eq, PartialEq)]
+    pub(super) struct Version(usize);
+
+    /// Snapshot of the state. The first bit is used as the CLOSED bit.
+    /// The remaining bits are used as the version.
+    ///
+    /// The CLOSED bit tracks whether the Sender has been dropped. Dropping all
+    /// receivers does not set it.
+    #[derive(Copy, Clone, Debug)]
+    pub(super) struct StateSnapshot(usize);
+
+    /// The state stored in an atomic integer.
+    #[derive(Debug)]
+    pub(super) struct AtomicState(AtomicUsize);
+
+    impl Version {
+        /// Get the initial version when creating the channel.
+        pub(super) fn initial() -> Self {
+            Version(0)
+        }
+    }
+
+    impl StateSnapshot {
+        /// Extract the version from the state.
+        pub(super) fn version(self) -> Version {
+            Version(self.0 & !CLOSED)
+        }
+
+        /// Is the closed bit set?
+        pub(super) fn is_closed(self) -> bool {
+            (self.0 & CLOSED) == CLOSED
+        }
+    }
+
+    impl AtomicState {
+        /// Create a new `AtomicState` that is not closed and which has the
+        /// version set to `Version::initial()`.
+        pub(super) fn new() -> Self {
+            AtomicState(AtomicUsize::new(0))
+        }
+
+        /// Load the current value of the state.
+        pub(super) fn load(&self) -> StateSnapshot {
+            StateSnapshot(self.0.load(SeqCst))
+        }
+
+        /// Increment the version counter.
+        pub(super) fn increment_version(&self) {
+            // Increment by two to avoid touching the CLOSED bit.
+            self.0.fetch_add(2, SeqCst);
+        }
+
+        /// Set the closed bit in the state.
+        pub(super) fn set_closed(&self) {
+            self.0.fetch_or(CLOSED, SeqCst);
+        }
+    }
+}
 
 /// Creates a new watch channel, returning the "send" and "receive" handles.
 ///
@@ -184,9 +395,9 @@ const CLOSED: usize = 1;
 pub fn channel<T>(init: T) -> (Sender<T>, Receiver<T>) {
     let shared = Arc::new(Shared {
         value: RwLock::new(init),
-        version: AtomicUsize::new(0),
+        state: AtomicState::new(),
         ref_count_rx: AtomicUsize::new(1),
-        notify_rx: Notify::new(),
+        notify_rx: big_notify::BigNotify::new(),
         notify_tx: Notify::new(),
     });
 
@@ -194,13 +405,16 @@ pub fn channel<T>(init: T) -> (Sender<T>, Receiver<T>) {
         shared: shared.clone(),
     };
 
-    let rx = Receiver { shared, version: 0 };
+    let rx = Receiver {
+        shared,
+        version: Version::initial(),
+    };
 
     (tx, rx)
 }
 
 impl<T> Receiver<T> {
-    fn from_shared(version: usize, shared: Arc<Shared<T>>) -> Self {
+    fn from_shared(version: Version, shared: Arc<Shared<T>>) -> Self {
         // No synchronization necessary as this is only used as a counter and
         // not memory access.
         shared.ref_count_rx.fetch_add(1, Relaxed);
@@ -214,9 +428,29 @@ impl<T> Receiver<T> {
     /// [`changed`] may return immediately even if you have already seen the
     /// value with a call to `borrow`.
     ///
-    /// Outstanding borrows hold a read lock. This means that long lived borrows
-    /// could cause the send half to block. It is recommended to keep the borrow
-    /// as short lived as possible.
+    /// Outstanding borrows hold a read lock on the inner value. This means that
+    /// long-lived borrows could cause the producer half to block. It is recommended
+    /// to keep the borrow as short-lived as possible. Additionally, if you are
+    /// running in an environment that allows `!Send` futures, you must ensure that
+    /// the returned `Ref` type is never held alive across an `.await` point,
+    /// otherwise, it can lead to a deadlock.
+    ///
+    /// The priority policy of the lock is dependent on the underlying lock
+    /// implementation, and this type does not guarantee that any particular policy
+    /// will be used. In particular, a producer which is waiting to acquire the lock
+    /// in `send` might or might not block concurrent calls to `borrow`, e.g.:
+    ///
+    /// <details><summary>Potential deadlock example</summary>
+    ///
+    /// ```text
+    /// // Task 1 (on thread A)    |  // Task 2 (on thread B)
+    /// let _ref1 = rx.borrow();   |
+    ///                            |  // will block
+    ///                            |  let _ = tx.send(());
+    /// // may deadlock            |
+    /// let _ref2 = rx.borrow();   |
+    /// ```
+    /// </details>
     ///
     /// [`changed`]: Receiver::changed
     ///
@@ -230,28 +464,104 @@ impl<T> Receiver<T> {
     /// ```
     pub fn borrow(&self) -> Ref<'_, T> {
         let inner = self.shared.value.read().unwrap();
-        Ref { inner }
+
+        // After obtaining a read-lock no concurrent writes could occur
+        // and the loaded version matches that of the borrowed reference.
+        let new_version = self.shared.state.load().version();
+        let has_changed = self.version != new_version;
+
+        Ref { inner, has_changed }
     }
 
-    /// Returns a reference to the most recently sent value and mark that value
+    /// Returns a reference to the most recently sent value and marks that value
     /// as seen.
     ///
-    /// This method marks the value as seen, so [`changed`] will not return
-    /// immediately if the newest value is one previously returned by
-    /// `borrow_and_update`.
+    /// This method marks the current value as seen. Subsequent calls to [`changed`]
+    /// will not return immediately until the [`Sender`] has modified the shared
+    /// value again.
+    ///
+    /// Outstanding borrows hold a read lock on the inner value. This means that
+    /// long-lived borrows could cause the producer half to block. It is recommended
+    /// to keep the borrow as short-lived as possible. Additionally, if you are
+    /// running in an environment that allows `!Send` futures, you must ensure that
+    /// the returned `Ref` type is never held alive across an `.await` point,
+    /// otherwise, it can lead to a deadlock.
+    ///
+    /// The priority policy of the lock is dependent on the underlying lock
+    /// implementation, and this type does not guarantee that any particular policy
+    /// will be used. In particular, a producer which is waiting to acquire the lock
+    /// in `send` might or might not block concurrent calls to `borrow`, e.g.:
     ///
-    /// Outstanding borrows hold a read lock. This means that long lived borrows
-    /// could cause the send half to block. It is recommended to keep the borrow
-    /// as short lived as possible.
+    /// <details><summary>Potential deadlock example</summary>
+    ///
+    /// ```text
+    /// // Task 1 (on thread A)                |  // Task 2 (on thread B)
+    /// let _ref1 = rx1.borrow_and_update();   |
+    ///                                        |  // will block
+    ///                                        |  let _ = tx.send(());
+    /// // may deadlock                        |
+    /// let _ref2 = rx2.borrow_and_update();   |
+    /// ```
+    /// </details>
     ///
     /// [`changed`]: Receiver::changed
     pub fn borrow_and_update(&mut self) -> Ref<'_, T> {
         let inner = self.shared.value.read().unwrap();
-        self.version = self.shared.version.load(SeqCst) & !CLOSED;
-        Ref { inner }
+
+        // After obtaining a read-lock no concurrent writes could occur
+        // and the loaded version matches that of the borrowed reference.
+        let new_version = self.shared.state.load().version();
+        let has_changed = self.version != new_version;
+
+        // Mark the shared value as seen by updating the version
+        self.version = new_version;
+
+        Ref { inner, has_changed }
+    }
+
+    /// Checks if this channel contains a message that this receiver has not yet
+    /// seen. The new value is not marked as seen.
+    ///
+    /// Although this method is called `has_changed`, it does not check new
+    /// messages for equality, so this call will return true even if the new
+    /// message is equal to the old message.
+    ///
+    /// Returns an error if the channel has been closed.
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::sync::watch;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let (tx, mut rx) = watch::channel("hello");
+    ///
+    ///     tx.send("goodbye").unwrap();
+    ///
+    ///     assert!(rx.has_changed().unwrap());
+    ///     assert_eq!(*rx.borrow_and_update(), "goodbye");
+    ///
+    ///     // The value has been marked as seen
+    ///     assert!(!rx.has_changed().unwrap());
+    ///
+    ///     drop(tx);
+    ///     // The `tx` handle has been dropped
+    ///     assert!(rx.has_changed().is_err());
+    /// }
+    /// ```
+    pub fn has_changed(&self) -> Result<bool, error::RecvError> {
+        // Load the version from the state
+        let state = self.shared.state.load();
+        if state.is_closed() {
+            // The sender has dropped.
+            return Err(error::RecvError(()));
+        }
+        let new_version = state.version();
+
+        Ok(self.version != new_version)
     }
 
-    /// Wait for a change notification, then mark the newest value as seen.
+    /// Waits for a change notification, then marks the newest value as seen.
     ///
     /// If the newest value in the channel has not yet been marked seen when
     /// this method is called, the method marks that value seen and returns
@@ -291,21 +601,112 @@ impl<T> Receiver<T> {
     /// }
     /// ```
     pub async fn changed(&mut self) -> Result<(), error::RecvError> {
+        changed_impl(&self.shared, &mut self.version).await
+    }
+
+    /// Waits for a value that satisifes the provided condition.
+    ///
+    /// This method will call the provided closure whenever something is sent on
+    /// the channel. Once the closure returns `true`, this method will return a
+    /// reference to the value that was passed to the closure.
+    ///
+    /// Before `wait_for` starts waiting for changes, it will call the closure
+    /// on the current value. If the closure returns `true` when given the
+    /// current value, then `wait_for` will immediately return a reference to
+    /// the current value. This is the case even if the current value is already
+    /// considered seen.
+    ///
+    /// The watch channel only keeps track of the most recent value, so if
+    /// several messages are sent faster than `wait_for` is able to call the
+    /// closure, then it may skip some updates. Whenever the closure is called,
+    /// it will be called with the most recent value.
+    ///
+    /// When this function returns, the value that was passed to the closure
+    /// when it returned `true` will be considered seen.
+    ///
+    /// If the channel is closed, then `wait_for` will return a `RecvError`.
+    /// Once this happens, no more messages can ever be sent on the channel.
+    /// When an error is returned, it is guaranteed that the closure has been
+    /// called on the last value, and that it returned `false` for that value.
+    /// (If the closure returned `true`, then the last value would have been
+    /// returned instead of the error.)
+    ///
+    /// Like the `borrow` method, the returned borrow holds a read lock on the
+    /// inner value. This means that long-lived borrows could cause the producer
+    /// half to block. It is recommended to keep the borrow as short-lived as
+    /// possible. See the documentation of `borrow` for more information on
+    /// this.
+    ///
+    /// [`Receiver::changed()`]: crate::sync::watch::Receiver::changed
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::sync::watch;
+    ///
+    /// #[tokio::main]
+    ///
+    /// async fn main() {
+    ///     let (tx, _rx) = watch::channel("hello");
+    ///
+    ///     tx.send("goodbye").unwrap();
+    ///
+    ///     // here we subscribe to a second receiver
+    ///     // now in case of using `changed` we would have
+    ///     // to first check the current value and then wait
+    ///     // for changes or else `changed` would hang.
+    ///     let mut rx2 = tx.subscribe();
+    ///
+    ///     // in place of changed we have use `wait_for`
+    ///     // which would automatically check the current value
+    ///     // and wait for changes until the closure returns true.
+    ///     assert!(rx2.wait_for(|val| *val == "goodbye").await.is_ok());
+    ///     assert_eq!(*rx2.borrow(), "goodbye");
+    /// }
+    /// ```
+    pub async fn wait_for(
+        &mut self,
+        mut f: impl FnMut(&T) -> bool,
+    ) -> Result<Ref<'_, T>, error::RecvError> {
+        let mut closed = false;
         loop {
-            // In order to avoid a race condition, we first request a notification,
-            // **then** check the current value's version. If a new version exists,
-            // the notification request is dropped.
-            let notified = self.shared.notify_rx.notified();
+            {
+                let inner = self.shared.value.read().unwrap();
 
-            if let Some(ret) = maybe_changed(&self.shared, &mut self.version) {
-                return ret;
+                let new_version = self.shared.state.load().version();
+                let has_changed = self.version != new_version;
+                self.version = new_version;
+
+                if (!closed || has_changed) && f(&inner) {
+                    return Ok(Ref { inner, has_changed });
+                }
             }
 
-            notified.await;
-            // loop around again in case the wake-up was spurious
+            if closed {
+                return Err(error::RecvError(()));
+            }
+
+            // Wait for the value to change.
+            closed = changed_impl(&self.shared, &mut self.version).await.is_err();
         }
     }
 
+    /// Returns `true` if receivers belong to the same channel.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let (tx, rx) = tokio::sync::watch::channel(true);
+    /// let rx2 = rx.clone();
+    /// assert!(rx.same_channel(&rx2));
+    ///
+    /// let (tx3, rx3) = tokio::sync::watch::channel(true);
+    /// assert!(!rx3.same_channel(&rx2));
+    /// ```
+    pub fn same_channel(&self, other: &Self) -> bool {
+        Arc::ptr_eq(&self.shared, &other.shared)
+    }
+
     cfg_process_driver! {
         pub(crate) fn try_has_changed(&mut self) -> Option<Result<(), error::RecvError>> {
             maybe_changed(&self.shared, &mut self.version)
@@ -315,11 +716,11 @@ impl<T> Receiver<T> {
 
 fn maybe_changed<T>(
     shared: &Shared<T>,
-    version: &mut usize,
+    version: &mut Version,
 ) -> Option<Result<(), error::RecvError>> {
     // Load the version from the state
-    let state = shared.version.load(SeqCst);
-    let new_version = state & !CLOSED;
+    let state = shared.state.load();
+    let new_version = state.version();
 
     if *version != new_version {
         // Observe the new version and return
@@ -327,7 +728,7 @@ fn maybe_changed<T>(
         return Some(Ok(()));
     }
 
-    if CLOSED == state & CLOSED {
+    if state.is_closed() {
         // All receivers have dropped.
         return Some(Err(error::RecvError(())));
     }
@@ -335,6 +736,27 @@ fn maybe_changed<T>(
     None
 }
 
+async fn changed_impl<T>(
+    shared: &Shared<T>,
+    version: &mut Version,
+) -> Result<(), error::RecvError> {
+    crate::trace::async_trace_leaf().await;
+
+    loop {
+        // In order to avoid a race condition, we first request a notification,
+        // **then** check the current value's version. If a new version exists,
+        // the notification request is dropped.
+        let notified = shared.notify_rx.notified();
+
+        if let Some(ret) = maybe_changed(shared, version) {
+            return ret;
+        }
+
+        notified.await;
+        // loop around again in case the wake-up was spurious
+    }
+}
+
 impl<T> Clone for Receiver<T> {
     fn clone(&self) -> Self {
         let version = self.version;
@@ -357,19 +779,158 @@ impl<T> Drop for Receiver<T> {
 
 impl<T> Sender<T> {
     /// Sends a new value via the channel, notifying all receivers.
+    ///
+    /// This method fails if the channel is closed, which is the case when
+    /// every receiver has been dropped. It is possible to reopen the channel
+    /// using the [`subscribe`] method. However, when `send` fails, the value
+    /// isn't made available for future receivers (but returned with the
+    /// [`SendError`]).
+    ///
+    /// To always make a new value available for future receivers, even if no
+    /// receiver currently exists, one of the other send methods
+    /// ([`send_if_modified`], [`send_modify`], or [`send_replace`]) can be
+    /// used instead.
+    ///
+    /// [`subscribe`]: Sender::subscribe
+    /// [`SendError`]: error::SendError
+    /// [`send_if_modified`]: Sender::send_if_modified
+    /// [`send_modify`]: Sender::send_modify
+    /// [`send_replace`]: Sender::send_replace
     pub fn send(&self, value: T) -> Result<(), error::SendError<T>> {
         // This is pretty much only useful as a hint anyway, so synchronization isn't critical.
-        if 0 == self.shared.ref_count_rx.load(Relaxed) {
-            return Err(error::SendError { inner: value });
+        if 0 == self.receiver_count() {
+            return Err(error::SendError(value));
         }
 
+        self.send_replace(value);
+        Ok(())
+    }
+
+    /// Modifies the watched value **unconditionally** in-place,
+    /// notifying all receivers.
+    ///
+    /// This can be useful for modifying the watched value, without
+    /// having to allocate a new instance. Additionally, this
+    /// method permits sending values even when there are no receivers.
+    ///
+    /// Prefer to use the more versatile function [`Self::send_if_modified()`]
+    /// if the value is only modified conditionally during the mutable borrow
+    /// to prevent unneeded change notifications for unmodified values.
+    ///
+    /// # Panics
+    ///
+    /// This function panics when the invocation of the `modify` closure panics.
+    /// No receivers are notified when panicking. All changes of the watched
+    /// value applied by the closure before panicking will be visible in
+    /// subsequent calls to `borrow`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::sync::watch;
+    ///
+    /// struct State {
+    ///     counter: usize,
+    /// }
+    /// let (state_tx, state_rx) = watch::channel(State { counter: 0 });
+    /// state_tx.send_modify(|state| state.counter += 1);
+    /// assert_eq!(state_rx.borrow().counter, 1);
+    /// ```
+    pub fn send_modify<F>(&self, modify: F)
+    where
+        F: FnOnce(&mut T),
+    {
+        self.send_if_modified(|value| {
+            modify(value);
+            true
+        });
+    }
+
+    /// Modifies the watched value **conditionally** in-place,
+    /// notifying all receivers only if modified.
+    ///
+    /// This can be useful for modifying the watched value, without
+    /// having to allocate a new instance. Additionally, this
+    /// method permits sending values even when there are no receivers.
+    ///
+    /// The `modify` closure must return `true` if the value has actually
+    /// been modified during the mutable borrow. It should only return `false`
+    /// if the value is guaranteed to be unmodified despite the mutable
+    /// borrow.
+    ///
+    /// Receivers are only notified if the closure returned `true`. If the
+    /// closure has modified the value but returned `false` this results
+    /// in a *silent modification*, i.e. the modified value will be visible
+    /// in subsequent calls to `borrow`, but receivers will not receive
+    /// a change notification.
+    ///
+    /// Returns the result of the closure, i.e. `true` if the value has
+    /// been modified and `false` otherwise.
+    ///
+    /// # Panics
+    ///
+    /// This function panics when the invocation of the `modify` closure panics.
+    /// No receivers are notified when panicking. All changes of the watched
+    /// value applied by the closure before panicking will be visible in
+    /// subsequent calls to `borrow`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::sync::watch;
+    ///
+    /// struct State {
+    ///     counter: usize,
+    /// }
+    /// let (state_tx, mut state_rx) = watch::channel(State { counter: 1 });
+    /// let inc_counter_if_odd = |state: &mut State| {
+    ///     if state.counter % 2 == 1 {
+    ///         state.counter += 1;
+    ///         return true;
+    ///     }
+    ///     false
+    /// };
+    ///
+    /// assert_eq!(state_rx.borrow().counter, 1);
+    ///
+    /// assert!(!state_rx.has_changed().unwrap());
+    /// assert!(state_tx.send_if_modified(inc_counter_if_odd));
+    /// assert!(state_rx.has_changed().unwrap());
+    /// assert_eq!(state_rx.borrow_and_update().counter, 2);
+    ///
+    /// assert!(!state_rx.has_changed().unwrap());
+    /// assert!(!state_tx.send_if_modified(inc_counter_if_odd));
+    /// assert!(!state_rx.has_changed().unwrap());
+    /// assert_eq!(state_rx.borrow_and_update().counter, 2);
+    /// ```
+    pub fn send_if_modified<F>(&self, modify: F) -> bool
+    where
+        F: FnOnce(&mut T) -> bool,
+    {
         {
             // Acquire the write lock and update the value.
             let mut lock = self.shared.value.write().unwrap();
-            *lock = value;
 
-            // Update the version. 2 is used so that the CLOSED bit is not set.
-            self.shared.version.fetch_add(2, SeqCst);
+            // Update the value and catch possible panic inside func.
+            let result = panic::catch_unwind(panic::AssertUnwindSafe(|| modify(&mut lock)));
+            match result {
+                Ok(modified) => {
+                    if !modified {
+                        // Abort, i.e. don't notify receivers if unmodified
+                        return false;
+                    }
+                    // Continue if modified
+                }
+                Err(panicked) => {
+                    // Drop the lock to avoid poisoning it.
+                    drop(lock);
+                    // Forward the panic to the caller.
+                    panic::resume_unwind(panicked);
+                    // Unreachable
+                }
+            };
+
+            self.shared.state.increment_version();
 
             // Release the write lock.
             //
@@ -379,17 +940,42 @@ impl<T> Sender<T> {
             drop(lock);
         }
 
-        // Notify all watchers
         self.shared.notify_rx.notify_waiters();
 
-        Ok(())
+        true
+    }
+
+    /// Sends a new value via the channel, notifying all receivers and returning
+    /// the previous value in the channel.
+    ///
+    /// This can be useful for reusing the buffers inside a watched value.
+    /// Additionally, this method permits sending values even when there are no
+    /// receivers.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::sync::watch;
+    ///
+    /// let (tx, _rx) = watch::channel(1);
+    /// assert_eq!(tx.send_replace(2), 1);
+    /// assert_eq!(tx.send_replace(3), 2);
+    /// ```
+    pub fn send_replace(&self, mut value: T) -> T {
+        // swap old watched value with the new one
+        self.send_modify(|old| mem::swap(old, &mut value));
+
+        value
     }
 
     /// Returns a reference to the most recently sent value
     ///
-    /// Outstanding borrows hold a read lock. This means that long lived borrows
-    /// could cause the send half to block. It is recommended to keep the borrow
-    /// as short lived as possible.
+    /// Outstanding borrows hold a read lock on the inner value. This means that
+    /// long-lived borrows could cause the producer half to block. It is recommended
+    /// to keep the borrow as short-lived as possible. Additionally, if you are
+    /// running in an environment that allows `!Send` futures, you must ensure that
+    /// the returned `Ref` type is never held alive across an `.await` point,
+    /// otherwise, it can lead to a deadlock.
     ///
     /// # Examples
     ///
@@ -401,7 +987,11 @@ impl<T> Sender<T> {
     /// ```
     pub fn borrow(&self) -> Ref<'_, T> {
         let inner = self.shared.value.read().unwrap();
-        Ref { inner }
+
+        // The sender/producer always sees the current version
+        let has_changed = false;
+
+        Ref { inner, has_changed }
     }
 
     /// Checks if the channel has been closed. This happens when all receivers
@@ -417,7 +1007,7 @@ impl<T> Sender<T> {
     /// assert!(tx.is_closed());
     /// ```
     pub fn is_closed(&self) -> bool {
-        self.shared.ref_count_rx.load(Relaxed) == 0
+        self.receiver_count() == 0
     }
 
     /// Completes when all receivers have dropped.
@@ -450,26 +1040,86 @@ impl<T> Sender<T> {
     /// }
     /// ```
     pub async fn closed(&self) {
-        let notified = self.shared.notify_tx.notified();
+        crate::trace::async_trace_leaf().await;
 
-        if self.shared.ref_count_rx.load(Relaxed) == 0 {
-            return;
-        }
+        while self.receiver_count() > 0 {
+            let notified = self.shared.notify_tx.notified();
 
-        notified.await;
-        debug_assert_eq!(0, self.shared.ref_count_rx.load(Relaxed));
+            if self.receiver_count() == 0 {
+                return;
+            }
+
+            notified.await;
+            // The channel could have been reopened in the meantime by calling
+            // `subscribe`, so we loop again.
+        }
     }
 
-    cfg_signal_internal! {
-        pub(crate) fn subscribe(&self) -> Receiver<T> {
-            let shared = self.shared.clone();
-            let version = shared.version.load(SeqCst);
+    /// Creates a new [`Receiver`] connected to this `Sender`.
+    ///
+    /// All messages sent before this call to `subscribe` are initially marked
+    /// as seen by the new `Receiver`.
+    ///
+    /// This method can be called even if there are no other receivers. In this
+    /// case, the channel is reopened.
+    ///
+    /// # Examples
+    ///
+    /// The new channel will receive messages sent on this `Sender`.
+    ///
+    /// ```
+    /// use tokio::sync::watch;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let (tx, _rx) = watch::channel(0u64);
+    ///
+    ///     tx.send(5).unwrap();
+    ///
+    ///     let rx = tx.subscribe();
+    ///     assert_eq!(5, *rx.borrow());
+    ///
+    ///     tx.send(10).unwrap();
+    ///     assert_eq!(10, *rx.borrow());
+    /// }
+    /// ```
+    ///
+    /// The most recent message is considered seen by the channel, so this test
+    /// is guaranteed to pass.
+    ///
+    /// ```
+    /// use tokio::sync::watch;
+    /// use tokio::time::Duration;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let (tx, _rx) = watch::channel(0u64);
+    ///     tx.send(5).unwrap();
+    ///     let mut rx = tx.subscribe();
+    ///
+    ///     tokio::spawn(async move {
+    ///         // by spawning and sleeping, the message is sent after `main`
+    ///         // hits the call to `changed`.
+    ///         # if false {
+    ///         tokio::time::sleep(Duration::from_millis(10)).await;
+    ///         # }
+    ///         tx.send(100).unwrap();
+    ///     });
+    ///
+    ///     rx.changed().await.unwrap();
+    ///     assert_eq!(100, *rx.borrow());
+    /// }
+    /// ```
+    pub fn subscribe(&self) -> Receiver<T> {
+        let shared = self.shared.clone();
+        let version = shared.state.load().version();
 
-            Receiver::from_shared(version, shared)
-        }
+        // The CLOSED bit in the state tracks only whether the sender is
+        // dropped, so we do not need to unset it if this reopens the channel.
+        Receiver::from_shared(version, shared)
     }
 
-    /// Returns the number of receivers that currently exist
+    /// Returns the number of receivers that currently exist.
     ///
     /// # Examples
     ///
@@ -494,7 +1144,7 @@ impl<T> Sender<T> {
 
 impl<T> Drop for Sender<T> {
     fn drop(&mut self) {
-        self.shared.version.fetch_or(CLOSED, SeqCst);
+        self.shared.state.set_closed();
         self.shared.notify_rx.notify_waiters();
     }
 }
diff --git a/vendor/tokio/src/task/blocking.rs b/vendor/tokio/src/task/blocking.rs
index e4fe254a0..9bd15ebd5 100644
--- a/vendor/tokio/src/task/blocking.rs
+++ b/vendor/tokio/src/task/blocking.rs
@@ -70,11 +70,12 @@ cfg_rt_multi_thread! {
     /// This function panics if called from a [`current_thread`] runtime.
     ///
     /// [`current_thread`]: fn@crate::runtime::Builder::new_current_thread
+    #[track_caller]
     pub fn block_in_place<F, R>(f: F) -> R
     where
         F: FnOnce() -> R,
     {
-        crate::runtime::thread_pool::block_in_place(f)
+        crate::runtime::scheduler::multi_thread::block_in_place(f)
     }
 }
 
@@ -89,50 +90,117 @@ cfg_rt! {
     ///
     /// Tokio will spawn more blocking threads when they are requested through this
     /// function until the upper limit configured on the [`Builder`] is reached.
-    /// This limit is very large by default, because `spawn_blocking` is often used
-    /// for various kinds of IO operations that cannot be performed asynchronously.
-    /// When you run CPU-bound code using `spawn_blocking`, you should keep this
-    /// large upper limit in mind. When running many CPU-bound computations, a
-    /// semaphore or some other synchronization primitive should be used to limit
-    /// the number of computation executed in parallel. Specialized CPU-bound
-    /// executors, such as [rayon], may also be a good fit.
+    /// After reaching the upper limit, the tasks are put in a queue.
+    /// The thread limit is very large by default, because `spawn_blocking` is often
+    /// used for various kinds of IO operations that cannot be performed
+    /// asynchronously.  When you run CPU-bound code using `spawn_blocking`, you
+    /// should keep this large upper limit in mind. When running many CPU-bound
+    /// computations, a semaphore or some other synchronization primitive should be
+    /// used to limit the number of computation executed in parallel. Specialized
+    /// CPU-bound executors, such as [rayon], may also be a good fit.
     ///
     /// This function is intended for non-async operations that eventually finish on
     /// their own. If you want to spawn an ordinary thread, you should use
     /// [`thread::spawn`] instead.
     ///
-    /// Closures spawned using `spawn_blocking` cannot be cancelled. When you shut
-    /// down the executor, it will wait indefinitely for all blocking operations to
+    /// Closures spawned using `spawn_blocking` cannot be cancelled abruptly; there
+    /// is no standard low level API to cause a thread to stop running.  However,
+    /// a useful pattern is to pass some form of "cancellation token" into
+    /// the thread.  This could be an [`AtomicBool`] that the task checks periodically.
+    /// Another approach is to have the thread primarily read or write from a channel,
+    /// and to exit when the channel closes; assuming the other side of the channel is dropped
+    /// when cancellation occurs, this will cause the blocking task thread to exit
+    /// soon after as well.
+    ///
+    /// When you shut down the executor, it will wait indefinitely for all blocking operations to
     /// finish. You can use [`shutdown_timeout`] to stop waiting for them after a
     /// certain timeout. Be aware that this will still not cancel the tasks — they
-    /// are simply allowed to keep running after the method returns.
+    /// are simply allowed to keep running after the method returns.  It is possible
+    /// for a blocking task to be cancelled if it has not yet started running, but this
+    /// is not guaranteed.
     ///
     /// Note that if you are using the single threaded runtime, this function will
-    /// still spawn additional threads for blocking operations. The basic
+    /// still spawn additional threads for blocking operations. The current-thread
     /// scheduler's single thread is only used for asynchronous code.
     ///
+    /// # Related APIs and patterns for bridging asynchronous and blocking code
+    ///
+    /// In simple cases, it is sufficient to have the closure accept input
+    /// parameters at creation time and return a single value (or struct/tuple, etc.).
+    ///
+    /// For more complex situations in which it is desirable to stream data to or from
+    /// the synchronous context, the [`mpsc channel`] has `blocking_send` and
+    /// `blocking_recv` methods for use in non-async code such as the thread created
+    /// by `spawn_blocking`.
+    ///
+    /// Another option is [`SyncIoBridge`] for cases where the synchronous context
+    /// is operating on byte streams.  For example, you might use an asynchronous
+    /// HTTP client such as [hyper] to fetch data, but perform complex parsing
+    /// of the payload body using a library written for synchronous I/O.
+    ///
+    /// Finally, see also [Bridging with sync code][bridgesync] for discussions
+    /// around the opposite case of using Tokio as part of a larger synchronous
+    /// codebase.
+    ///
     /// [`Builder`]: struct@crate::runtime::Builder
     /// [blocking]: ../index.html#cpu-bound-tasks-and-blocking-code
     /// [rayon]: https://docs.rs/rayon
+    /// [`mpsc channel`]: crate::sync::mpsc
+    /// [`SyncIoBridge`]: https://docs.rs/tokio-util/latest/tokio_util/io/struct.SyncIoBridge.html
+    /// [hyper]: https://docs.rs/hyper
     /// [`thread::spawn`]: fn@std::thread::spawn
     /// [`shutdown_timeout`]: fn@crate::runtime::Runtime::shutdown_timeout
+    /// [bridgesync]: https://tokio.rs/tokio/topics/bridging
+    /// [`AtomicBool`]: struct@std::sync::atomic::AtomicBool
     ///
     /// # Examples
     ///
+    /// Pass an input value and receive result of computation:
+    ///
     /// ```
     /// use tokio::task;
     ///
     /// # async fn docs() -> Result<(), Box<dyn std::error::Error>>{
+    /// // Initial input
+    /// let mut v = "Hello, ".to_string();
     /// let res = task::spawn_blocking(move || {
-    ///     // do some compute-heavy work or call synchronous code
-    ///     "done computing"
+    ///     // Stand-in for compute-heavy work or using synchronous APIs
+    ///     v.push_str("world");
+    ///     // Pass ownership of the value back to the asynchronous context
+    ///     v
     /// }).await?;
     ///
-    /// assert_eq!(res, "done computing");
+    /// // `res` is the value returned from the thread
+    /// assert_eq!(res.as_str(), "Hello, world");
     /// # Ok(())
     /// # }
     /// ```
-    #[cfg_attr(tokio_track_caller, track_caller)]
+    ///
+    /// Use a channel:
+    ///
+    /// ```
+    /// use tokio::task;
+    /// use tokio::sync::mpsc;
+    ///
+    /// # async fn docs() {
+    /// let (tx, mut rx) = mpsc::channel(2);
+    /// let start = 5;
+    /// let worker = task::spawn_blocking(move || {
+    ///     for x in 0..10 {
+    ///         // Stand in for complex computation
+    ///         tx.blocking_send(start + x).unwrap();
+    ///     }
+    /// });
+    ///
+    /// let mut acc = 0;
+    /// while let Some(v) = rx.recv().await {
+    ///     acc += v;
+    /// }
+    /// assert_eq!(acc, 95);
+    /// worker.await.unwrap();
+    /// # }
+    /// ```
+    #[track_caller]
     pub fn spawn_blocking<F, R>(f: F) -> JoinHandle<R>
     where
         F: FnOnce() -> R + Send + 'static,
diff --git a/vendor/tokio/src/task/builder.rs b/vendor/tokio/src/task/builder.rs
index e46bdefe9..306cc39d1 100644
--- a/vendor/tokio/src/task/builder.rs
+++ b/vendor/tokio/src/task/builder.rs
@@ -1,10 +1,16 @@
 #![allow(unreachable_pub)]
-use crate::util::error::CONTEXT_MISSING_ERROR;
-use crate::{runtime::context, task::JoinHandle};
-use std::future::Future;
+use crate::{
+    runtime::Handle,
+    task::{JoinHandle, LocalSet},
+};
+use std::{future::Future, io};
 
 /// Factory which is used to configure the properties of a new task.
 ///
+/// **Note**: This is an [unstable API][unstable]. The public API of this type
+/// may break in 1.x releases. See [the documentation on unstable
+/// features][unstable] for details.
+///
 /// Methods can be chained in order to configure it.
 ///
 /// Currently, there is only one configuration option:
@@ -42,11 +48,17 @@ use std::future::Future;
 ///             .spawn(async move {
 ///                 // Process each socket concurrently.
 ///                 process(socket).await
-///             });
+///             })?;
 ///     }
 /// }
 /// ```
+/// [unstable]: crate#unstable-features
+/// [`name`]: Builder::name
+/// [`spawn_local`]: Builder::spawn_local
+/// [`spawn`]: Builder::spawn
+/// [`spawn_blocking`]: Builder::spawn_blocking
 #[derive(Default, Debug)]
+#[cfg_attr(docsrs, doc(cfg(all(tokio_unstable, feature = "tracing"))))]
 pub struct Builder<'a> {
     name: Option<&'a str>,
 }
@@ -62,44 +74,128 @@ impl<'a> Builder<'a> {
         Self { name: Some(name) }
     }
 
-    /// Spawns a task on the executor.
+    /// Spawns a task with this builder's settings on the current runtime.
+    ///
+    /// # Panics
+    ///
+    /// This method panics if called outside of a Tokio runtime.
     ///
-    /// See [`task::spawn`](crate::task::spawn) for
+    /// See [`task::spawn`](crate::task::spawn()) for
     /// more details.
-    #[cfg_attr(tokio_track_caller, track_caller)]
-    pub fn spawn<Fut>(self, future: Fut) -> JoinHandle<Fut::Output>
+    #[track_caller]
+    pub fn spawn<Fut>(self, future: Fut) -> io::Result<JoinHandle<Fut::Output>>
     where
         Fut: Future + Send + 'static,
         Fut::Output: Send + 'static,
     {
-        super::spawn::spawn_inner(future, self.name)
+        Ok(super::spawn::spawn_inner(future, self.name))
     }
 
-    /// Spawns a task on the current thread.
+    /// Spawn a task with this builder's settings on the provided [runtime
+    /// handle].
     ///
-    /// See [`task::spawn_local`](crate::task::spawn_local)
-    /// for more details.
-    #[cfg_attr(tokio_track_caller, track_caller)]
-    pub fn spawn_local<Fut>(self, future: Fut) -> JoinHandle<Fut::Output>
+    /// See [`Handle::spawn`] for more details.
+    ///
+    /// [runtime handle]: crate::runtime::Handle
+    /// [`Handle::spawn`]: crate::runtime::Handle::spawn
+    #[track_caller]
+    pub fn spawn_on<Fut>(self, future: Fut, handle: &Handle) -> io::Result<JoinHandle<Fut::Output>>
+    where
+        Fut: Future + Send + 'static,
+        Fut::Output: Send + 'static,
+    {
+        Ok(handle.spawn_named(future, self.name))
+    }
+
+    /// Spawns `!Send` a task on the current [`LocalSet`] with this builder's
+    /// settings.
+    ///
+    /// The spawned future will be run on the same thread that called `spawn_local`.
+    /// This may only be called from the context of a [local task set][`LocalSet`].
+    ///
+    /// # Panics
+    ///
+    /// This function panics if called outside of a [local task set][`LocalSet`].
+    ///
+    /// See [`task::spawn_local`] for more details.
+    ///
+    /// [`task::spawn_local`]: crate::task::spawn_local
+    /// [`LocalSet`]: crate::task::LocalSet
+    #[track_caller]
+    pub fn spawn_local<Fut>(self, future: Fut) -> io::Result<JoinHandle<Fut::Output>>
     where
         Fut: Future + 'static,
         Fut::Output: 'static,
     {
-        super::local::spawn_local_inner(future, self.name)
+        Ok(super::local::spawn_local_inner(future, self.name))
+    }
+
+    /// Spawns `!Send` a task on the provided [`LocalSet`] with this builder's
+    /// settings.
+    ///
+    /// See [`LocalSet::spawn_local`] for more details.
+    ///
+    /// [`LocalSet::spawn_local`]: crate::task::LocalSet::spawn_local
+    /// [`LocalSet`]: crate::task::LocalSet
+    #[track_caller]
+    pub fn spawn_local_on<Fut>(
+        self,
+        future: Fut,
+        local_set: &LocalSet,
+    ) -> io::Result<JoinHandle<Fut::Output>>
+    where
+        Fut: Future + 'static,
+        Fut::Output: 'static,
+    {
+        Ok(local_set.spawn_named(future, self.name))
     }
 
     /// Spawns blocking code on the blocking threadpool.
     ///
+    /// # Panics
+    ///
+    /// This method panics if called outside of a Tokio runtime.
+    ///
     /// See [`task::spawn_blocking`](crate::task::spawn_blocking)
     /// for more details.
-    #[cfg_attr(tokio_track_caller, track_caller)]
-    pub fn spawn_blocking<Function, Output>(self, function: Function) -> JoinHandle<Output>
+    #[track_caller]
+    pub fn spawn_blocking<Function, Output>(
+        self,
+        function: Function,
+    ) -> io::Result<JoinHandle<Output>>
     where
         Function: FnOnce() -> Output + Send + 'static,
         Output: Send + 'static,
     {
-        context::current()
-            .expect(CONTEXT_MISSING_ERROR)
-            .spawn_blocking_inner(function, self.name)
+        let handle = Handle::current();
+        self.spawn_blocking_on(function, &handle)
+    }
+
+    /// Spawns blocking code on the provided [runtime handle]'s blocking threadpool.
+    ///
+    /// See [`Handle::spawn_blocking`] for more details.
+    ///
+    /// [runtime handle]: crate::runtime::Handle
+    /// [`Handle::spawn_blocking`]: crate::runtime::Handle::spawn_blocking
+    #[track_caller]
+    pub fn spawn_blocking_on<Function, Output>(
+        self,
+        function: Function,
+        handle: &Handle,
+    ) -> io::Result<JoinHandle<Output>>
+    where
+        Function: FnOnce() -> Output + Send + 'static,
+        Output: Send + 'static,
+    {
+        use crate::runtime::Mandatory;
+        let (join_handle, spawn_result) = handle.inner.blocking_spawner().spawn_blocking_inner(
+            function,
+            Mandatory::NonMandatory,
+            self.name,
+            handle,
+        );
+
+        spawn_result?;
+        Ok(join_handle)
     }
 }
diff --git a/vendor/tokio/src/task/consume_budget.rs b/vendor/tokio/src/task/consume_budget.rs
new file mode 100644
index 000000000..e7432ffe7
--- /dev/null
+++ b/vendor/tokio/src/task/consume_budget.rs
@@ -0,0 +1,46 @@
+use std::task::Poll;
+
+/// Consumes a unit of budget and returns the execution back to the Tokio
+/// runtime *if* the task's coop budget was exhausted.
+///
+/// The task will only yield if its entire coop budget has been exhausted.
+/// This function can be used in order to insert optional yield points into long
+/// computations that do not use Tokio resources like sockets or semaphores,
+/// without redundantly yielding to the runtime each time.
+///
+/// **Note**: This is an [unstable API][unstable]. The public API of this type
+/// may break in 1.x releases. See [the documentation on unstable
+/// features][unstable] for details.
+///
+/// # Examples
+///
+/// Make sure that a function which returns a sum of (potentially lots of)
+/// iterated values is cooperative.
+///
+/// ```
+/// async fn sum_iterator(input: &mut impl std::iter::Iterator<Item=i64>) -> i64 {
+///     let mut sum: i64 = 0;
+///     while let Some(i) = input.next() {
+///         sum += i;
+///         tokio::task::consume_budget().await
+///     }
+///     sum
+/// }
+/// ```
+/// [unstable]: crate#unstable-features
+#[cfg_attr(docsrs, doc(cfg(all(tokio_unstable, feature = "rt"))))]
+pub async fn consume_budget() {
+    let mut status = Poll::Pending;
+
+    crate::future::poll_fn(move |cx| {
+        ready!(crate::trace::trace_leaf(cx));
+        if status.is_ready() {
+            return status;
+        }
+        status = crate::runtime::coop::poll_proceed(cx).map(|restore| {
+            restore.made_progress();
+        });
+        status
+    })
+    .await
+}
diff --git a/vendor/tokio/src/task/join_set.rs b/vendor/tokio/src/task/join_set.rs
new file mode 100644
index 000000000..4eb15a24d
--- /dev/null
+++ b/vendor/tokio/src/task/join_set.rs
@@ -0,0 +1,584 @@
+//! A collection of tasks spawned on a Tokio runtime.
+//!
+//! This module provides the [`JoinSet`] type, a collection which stores a set
+//! of spawned tasks and allows asynchronously awaiting the output of those
+//! tasks as they complete. See the documentation for the [`JoinSet`] type for
+//! details.
+use std::fmt;
+use std::future::Future;
+use std::pin::Pin;
+use std::task::{Context, Poll};
+
+use crate::runtime::Handle;
+#[cfg(tokio_unstable)]
+use crate::task::Id;
+use crate::task::{AbortHandle, JoinError, JoinHandle, LocalSet};
+use crate::util::IdleNotifiedSet;
+
+/// A collection of tasks spawned on a Tokio runtime.
+///
+/// A `JoinSet` can be used to await the completion of some or all of the tasks
+/// in the set. The set is not ordered, and the tasks will be returned in the
+/// order they complete.
+///
+/// All of the tasks must have the same return type `T`.
+///
+/// When the `JoinSet` is dropped, all tasks in the `JoinSet` are immediately aborted.
+///
+/// # Examples
+///
+/// Spawn multiple tasks and wait for them.
+///
+/// ```
+/// use tokio::task::JoinSet;
+///
+/// #[tokio::main]
+/// async fn main() {
+///     let mut set = JoinSet::new();
+///
+///     for i in 0..10 {
+///         set.spawn(async move { i });
+///     }
+///
+///     let mut seen = [false; 10];
+///     while let Some(res) = set.join_next().await {
+///         let idx = res.unwrap();
+///         seen[idx] = true;
+///     }
+///
+///     for i in 0..10 {
+///         assert!(seen[i]);
+///     }
+/// }
+/// ```
+#[cfg_attr(docsrs, doc(cfg(feature = "rt")))]
+pub struct JoinSet<T> {
+    inner: IdleNotifiedSet<JoinHandle<T>>,
+}
+
+/// A variant of [`task::Builder`] that spawns tasks on a [`JoinSet`] rather
+/// than on the current default runtime.
+///
+/// [`task::Builder`]: crate::task::Builder
+#[cfg(all(tokio_unstable, feature = "tracing"))]
+#[cfg_attr(docsrs, doc(cfg(all(tokio_unstable, feature = "tracing"))))]
+#[must_use = "builders do nothing unless used to spawn a task"]
+pub struct Builder<'a, T> {
+    joinset: &'a mut JoinSet<T>,
+    builder: super::Builder<'a>,
+}
+
+impl<T> JoinSet<T> {
+    /// Create a new `JoinSet`.
+    pub fn new() -> Self {
+        Self {
+            inner: IdleNotifiedSet::new(),
+        }
+    }
+
+    /// Returns the number of tasks currently in the `JoinSet`.
+    pub fn len(&self) -> usize {
+        self.inner.len()
+    }
+
+    /// Returns whether the `JoinSet` is empty.
+    pub fn is_empty(&self) -> bool {
+        self.inner.is_empty()
+    }
+}
+
+impl<T: 'static> JoinSet<T> {
+    /// Returns a [`Builder`] that can be used to configure a task prior to
+    /// spawning it on this `JoinSet`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::task::JoinSet;
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> std::io::Result<()> {
+    ///     let mut set = JoinSet::new();
+    ///
+    ///     // Use the builder to configure a task's name before spawning it.
+    ///     set.build_task()
+    ///         .name("my_task")
+    ///         .spawn(async { /* ... */ })?;
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    #[cfg_attr(docsrs, doc(cfg(all(tokio_unstable, feature = "tracing"))))]
+    pub fn build_task(&mut self) -> Builder<'_, T> {
+        Builder {
+            builder: super::Builder::new(),
+            joinset: self,
+        }
+    }
+
+    /// Spawn the provided task on the `JoinSet`, returning an [`AbortHandle`]
+    /// that can be used to remotely cancel the task.
+    ///
+    /// The provided future will start running in the background immediately
+    /// when this method is called, even if you don't await anything on this
+    /// `JoinSet`.
+    ///
+    /// # Panics
+    ///
+    /// This method panics if called outside of a Tokio runtime.
+    ///
+    /// [`AbortHandle`]: crate::task::AbortHandle
+    #[track_caller]
+    pub fn spawn<F>(&mut self, task: F) -> AbortHandle
+    where
+        F: Future<Output = T>,
+        F: Send + 'static,
+        T: Send,
+    {
+        self.insert(crate::spawn(task))
+    }
+
+    /// Spawn the provided task on the provided runtime and store it in this
+    /// `JoinSet` returning an [`AbortHandle`] that can be used to remotely
+    /// cancel the task.
+    ///
+    /// The provided future will start running in the background immediately
+    /// when this method is called, even if you don't await anything on this
+    /// `JoinSet`.
+    ///
+    /// [`AbortHandle`]: crate::task::AbortHandle
+    #[track_caller]
+    pub fn spawn_on<F>(&mut self, task: F, handle: &Handle) -> AbortHandle
+    where
+        F: Future<Output = T>,
+        F: Send + 'static,
+        T: Send,
+    {
+        self.insert(handle.spawn(task))
+    }
+
+    /// Spawn the provided task on the current [`LocalSet`] and store it in this
+    /// `JoinSet`, returning an [`AbortHandle`] that can be used to remotely
+    /// cancel the task.
+    ///
+    /// The provided future will start running in the background immediately
+    /// when this method is called, even if you don't await anything on this
+    /// `JoinSet`.
+    ///
+    /// # Panics
+    ///
+    /// This method panics if it is called outside of a `LocalSet`.
+    ///
+    /// [`LocalSet`]: crate::task::LocalSet
+    /// [`AbortHandle`]: crate::task::AbortHandle
+    #[track_caller]
+    pub fn spawn_local<F>(&mut self, task: F) -> AbortHandle
+    where
+        F: Future<Output = T>,
+        F: 'static,
+    {
+        self.insert(crate::task::spawn_local(task))
+    }
+
+    /// Spawn the provided task on the provided [`LocalSet`] and store it in
+    /// this `JoinSet`, returning an [`AbortHandle`] that can be used to
+    /// remotely cancel the task.
+    ///
+    /// Unlike the [`spawn_local`] method, this method may be used to spawn local
+    /// tasks on a `LocalSet` that is _not_ currently running. The provided
+    /// future will start running whenever the `LocalSet` is next started.
+    ///
+    /// [`LocalSet`]: crate::task::LocalSet
+    /// [`AbortHandle`]: crate::task::AbortHandle
+    /// [`spawn_local`]: Self::spawn_local
+    #[track_caller]
+    pub fn spawn_local_on<F>(&mut self, task: F, local_set: &LocalSet) -> AbortHandle
+    where
+        F: Future<Output = T>,
+        F: 'static,
+    {
+        self.insert(local_set.spawn_local(task))
+    }
+
+    /// Spawn the blocking code on the blocking threadpool and store
+    /// it in this `JoinSet`, returning an [`AbortHandle`] that can be
+    /// used to remotely cancel the task.
+    ///
+    /// # Examples
+    ///
+    /// Spawn multiple blocking tasks and wait for them.
+    ///
+    /// ```
+    /// use tokio::task::JoinSet;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let mut set = JoinSet::new();
+    ///
+    ///     for i in 0..10 {
+    ///         set.spawn_blocking(move || { i });
+    ///     }
+    ///
+    ///     let mut seen = [false; 10];
+    ///     while let Some(res) = set.join_next().await {
+    ///         let idx = res.unwrap();
+    ///         seen[idx] = true;
+    ///     }
+    ///
+    ///     for i in 0..10 {
+    ///         assert!(seen[i]);
+    ///     }
+    /// }
+    /// ```
+    ///
+    /// # Panics
+    ///
+    /// This method panics if called outside of a Tokio runtime.
+    ///
+    /// [`AbortHandle`]: crate::task::AbortHandle
+    #[track_caller]
+    pub fn spawn_blocking<F>(&mut self, f: F) -> AbortHandle
+    where
+        F: FnOnce() -> T,
+        F: Send + 'static,
+        T: Send,
+    {
+        self.insert(crate::runtime::spawn_blocking(f))
+    }
+
+    /// Spawn the blocking code on the blocking threadpool of the
+    /// provided runtime and store it in this `JoinSet`, returning an
+    /// [`AbortHandle`] that can be used to remotely cancel the task.
+    ///
+    /// [`AbortHandle`]: crate::task::AbortHandle
+    #[track_caller]
+    pub fn spawn_blocking_on<F>(&mut self, f: F, handle: &Handle) -> AbortHandle
+    where
+        F: FnOnce() -> T,
+        F: Send + 'static,
+        T: Send,
+    {
+        self.insert(handle.spawn_blocking(f))
+    }
+
+    fn insert(&mut self, jh: JoinHandle<T>) -> AbortHandle {
+        let abort = jh.abort_handle();
+        let mut entry = self.inner.insert_idle(jh);
+
+        // Set the waker that is notified when the task completes.
+        entry.with_value_and_context(|jh, ctx| jh.set_join_waker(ctx.waker()));
+        abort
+    }
+
+    /// Waits until one of the tasks in the set completes and returns its output.
+    ///
+    /// Returns `None` if the set is empty.
+    ///
+    /// # Cancel Safety
+    ///
+    /// This method is cancel safe. If `join_next` is used as the event in a `tokio::select!`
+    /// statement and some other branch completes first, it is guaranteed that no tasks were
+    /// removed from this `JoinSet`.
+    pub async fn join_next(&mut self) -> Option<Result<T, JoinError>> {
+        crate::future::poll_fn(|cx| self.poll_join_next(cx)).await
+    }
+
+    /// Waits until one of the tasks in the set completes and returns its
+    /// output, along with the [task ID] of the completed task.
+    ///
+    /// Returns `None` if the set is empty.
+    ///
+    /// When this method returns an error, then the id of the task that failed can be accessed
+    /// using the [`JoinError::id`] method.
+    ///
+    /// # Cancel Safety
+    ///
+    /// This method is cancel safe. If `join_next_with_id` is used as the event in a `tokio::select!`
+    /// statement and some other branch completes first, it is guaranteed that no tasks were
+    /// removed from this `JoinSet`.
+    ///
+    /// [task ID]: crate::task::Id
+    /// [`JoinError::id`]: fn@crate::task::JoinError::id
+    #[cfg(tokio_unstable)]
+    #[cfg_attr(docsrs, doc(cfg(tokio_unstable)))]
+    pub async fn join_next_with_id(&mut self) -> Option<Result<(Id, T), JoinError>> {
+        crate::future::poll_fn(|cx| self.poll_join_next_with_id(cx)).await
+    }
+
+    /// Aborts all tasks and waits for them to finish shutting down.
+    ///
+    /// Calling this method is equivalent to calling [`abort_all`] and then calling [`join_next`] in
+    /// a loop until it returns `None`.
+    ///
+    /// This method ignores any panics in the tasks shutting down. When this call returns, the
+    /// `JoinSet` will be empty.
+    ///
+    /// [`abort_all`]: fn@Self::abort_all
+    /// [`join_next`]: fn@Self::join_next
+    pub async fn shutdown(&mut self) {
+        self.abort_all();
+        while self.join_next().await.is_some() {}
+    }
+
+    /// Aborts all tasks on this `JoinSet`.
+    ///
+    /// This does not remove the tasks from the `JoinSet`. To wait for the tasks to complete
+    /// cancellation, you should call `join_next` in a loop until the `JoinSet` is empty.
+    pub fn abort_all(&mut self) {
+        self.inner.for_each(|jh| jh.abort());
+    }
+
+    /// Removes all tasks from this `JoinSet` without aborting them.
+    ///
+    /// The tasks removed by this call will continue to run in the background even if the `JoinSet`
+    /// is dropped.
+    pub fn detach_all(&mut self) {
+        self.inner.drain(drop);
+    }
+
+    /// Polls for one of the tasks in the set to complete.
+    ///
+    /// If this returns `Poll::Ready(Some(_))`, then the task that completed is removed from the set.
+    ///
+    /// When the method returns `Poll::Pending`, the `Waker` in the provided `Context` is scheduled
+    /// to receive a wakeup when a task in the `JoinSet` completes. Note that on multiple calls to
+    /// `poll_join_next`, only the `Waker` from the `Context` passed to the most recent call is
+    /// scheduled to receive a wakeup.
+    ///
+    /// # Returns
+    ///
+    /// This function returns:
+    ///
+    ///  * `Poll::Pending` if the `JoinSet` is not empty but there is no task whose output is
+    ///     available right now.
+    ///  * `Poll::Ready(Some(Ok(value)))` if one of the tasks in this `JoinSet` has completed.
+    ///     The `value` is the return value of one of the tasks that completed.
+    ///  * `Poll::Ready(Some(Err(err)))` if one of the tasks in this `JoinSet` has panicked or been
+    ///     aborted. The `err` is the `JoinError` from the panicked/aborted task.
+    ///  * `Poll::Ready(None)` if the `JoinSet` is empty.
+    ///
+    /// Note that this method may return `Poll::Pending` even if one of the tasks has completed.
+    /// This can happen if the [coop budget] is reached.
+    ///
+    /// [coop budget]: crate::task#cooperative-scheduling
+    pub fn poll_join_next(&mut self, cx: &mut Context<'_>) -> Poll<Option<Result<T, JoinError>>> {
+        // The call to `pop_notified` moves the entry to the `idle` list. It is moved back to
+        // the `notified` list if the waker is notified in the `poll` call below.
+        let mut entry = match self.inner.pop_notified(cx.waker()) {
+            Some(entry) => entry,
+            None => {
+                if self.is_empty() {
+                    return Poll::Ready(None);
+                } else {
+                    // The waker was set by `pop_notified`.
+                    return Poll::Pending;
+                }
+            }
+        };
+
+        let res = entry.with_value_and_context(|jh, ctx| Pin::new(jh).poll(ctx));
+
+        if let Poll::Ready(res) = res {
+            let _entry = entry.remove();
+            Poll::Ready(Some(res))
+        } else {
+            // A JoinHandle generally won't emit a wakeup without being ready unless
+            // the coop limit has been reached. We yield to the executor in this
+            // case.
+            cx.waker().wake_by_ref();
+            Poll::Pending
+        }
+    }
+
+    /// Polls for one of the tasks in the set to complete.
+    ///
+    /// If this returns `Poll::Ready(Some(_))`, then the task that completed is removed from the set.
+    ///
+    /// When the method returns `Poll::Pending`, the `Waker` in the provided `Context` is scheduled
+    /// to receive a wakeup when a task in the `JoinSet` completes. Note that on multiple calls to
+    /// `poll_join_next`, only the `Waker` from the `Context` passed to the most recent call is
+    /// scheduled to receive a wakeup.
+    ///
+    /// # Returns
+    ///
+    /// This function returns:
+    ///
+    ///  * `Poll::Pending` if the `JoinSet` is not empty but there is no task whose output is
+    ///     available right now.
+    ///  * `Poll::Ready(Some(Ok((id, value))))` if one of the tasks in this `JoinSet` has completed.
+    ///     The `value` is the return value of one of the tasks that completed, and
+    ///    `id` is the [task ID] of that task.
+    ///  * `Poll::Ready(Some(Err(err)))` if one of the tasks in this `JoinSet` has panicked or been
+    ///     aborted. The `err` is the `JoinError` from the panicked/aborted task.
+    ///  * `Poll::Ready(None)` if the `JoinSet` is empty.
+    ///
+    /// Note that this method may return `Poll::Pending` even if one of the tasks has completed.
+    /// This can happen if the [coop budget] is reached.
+    ///
+    /// [coop budget]: crate::task#cooperative-scheduling
+    /// [task ID]: crate::task::Id
+    #[cfg(tokio_unstable)]
+    #[cfg_attr(docsrs, doc(cfg(tokio_unstable)))]
+    pub fn poll_join_next_with_id(
+        &mut self,
+        cx: &mut Context<'_>,
+    ) -> Poll<Option<Result<(Id, T), JoinError>>> {
+        // The call to `pop_notified` moves the entry to the `idle` list. It is moved back to
+        // the `notified` list if the waker is notified in the `poll` call below.
+        let mut entry = match self.inner.pop_notified(cx.waker()) {
+            Some(entry) => entry,
+            None => {
+                if self.is_empty() {
+                    return Poll::Ready(None);
+                } else {
+                    // The waker was set by `pop_notified`.
+                    return Poll::Pending;
+                }
+            }
+        };
+
+        let res = entry.with_value_and_context(|jh, ctx| Pin::new(jh).poll(ctx));
+
+        if let Poll::Ready(res) = res {
+            let entry = entry.remove();
+            // If the task succeeded, add the task ID to the output. Otherwise, the
+            // `JoinError` will already have the task's ID.
+            Poll::Ready(Some(res.map(|output| (entry.id(), output))))
+        } else {
+            // A JoinHandle generally won't emit a wakeup without being ready unless
+            // the coop limit has been reached. We yield to the executor in this
+            // case.
+            cx.waker().wake_by_ref();
+            Poll::Pending
+        }
+    }
+}
+
+impl<T> Drop for JoinSet<T> {
+    fn drop(&mut self) {
+        self.inner.drain(|join_handle| join_handle.abort());
+    }
+}
+
+impl<T> fmt::Debug for JoinSet<T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("JoinSet").field("len", &self.len()).finish()
+    }
+}
+
+impl<T> Default for JoinSet<T> {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+// === impl Builder ===
+
+#[cfg(all(tokio_unstable, feature = "tracing"))]
+#[cfg_attr(docsrs, doc(cfg(all(tokio_unstable, feature = "tracing"))))]
+impl<'a, T: 'static> Builder<'a, T> {
+    /// Assigns a name to the task which will be spawned.
+    pub fn name(self, name: &'a str) -> Self {
+        let builder = self.builder.name(name);
+        Self { builder, ..self }
+    }
+
+    /// Spawn the provided task with this builder's settings and store it in the
+    /// [`JoinSet`], returning an [`AbortHandle`] that can be used to remotely
+    /// cancel the task.
+    ///
+    /// # Returns
+    ///
+    /// An [`AbortHandle`] that can be used to remotely cancel the task.
+    ///
+    /// # Panics
+    ///
+    /// This method panics if called outside of a Tokio runtime.
+    ///
+    /// [`AbortHandle`]: crate::task::AbortHandle
+    #[track_caller]
+    pub fn spawn<F>(self, future: F) -> std::io::Result<AbortHandle>
+    where
+        F: Future<Output = T>,
+        F: Send + 'static,
+        T: Send,
+    {
+        Ok(self.joinset.insert(self.builder.spawn(future)?))
+    }
+
+    /// Spawn the provided task on the provided [runtime handle] with this
+    /// builder's settings, and store it in the [`JoinSet`].
+    ///
+    /// # Returns
+    ///
+    /// An [`AbortHandle`] that can be used to remotely cancel the task.
+    ///
+    ///
+    /// [`AbortHandle`]: crate::task::AbortHandle
+    /// [runtime handle]: crate::runtime::Handle
+    #[track_caller]
+    pub fn spawn_on<F>(self, future: F, handle: &Handle) -> std::io::Result<AbortHandle>
+    where
+        F: Future<Output = T>,
+        F: Send + 'static,
+        T: Send,
+    {
+        Ok(self.joinset.insert(self.builder.spawn_on(future, handle)?))
+    }
+
+    /// Spawn the provided task on the current [`LocalSet`] with this builder's
+    /// settings, and store it in the [`JoinSet`].
+    ///
+    /// # Returns
+    ///
+    /// An [`AbortHandle`] that can be used to remotely cancel the task.
+    ///
+    /// # Panics
+    ///
+    /// This method panics if it is called outside of a `LocalSet`.
+    ///
+    /// [`LocalSet`]: crate::task::LocalSet
+    /// [`AbortHandle`]: crate::task::AbortHandle
+    #[track_caller]
+    pub fn spawn_local<F>(self, future: F) -> std::io::Result<AbortHandle>
+    where
+        F: Future<Output = T>,
+        F: 'static,
+    {
+        Ok(self.joinset.insert(self.builder.spawn_local(future)?))
+    }
+
+    /// Spawn the provided task on the provided [`LocalSet`] with this builder's
+    /// settings, and store it in the [`JoinSet`].
+    ///
+    /// # Returns
+    ///
+    /// An [`AbortHandle`] that can be used to remotely cancel the task.
+    ///
+    /// [`LocalSet`]: crate::task::LocalSet
+    /// [`AbortHandle`]: crate::task::AbortHandle
+    #[track_caller]
+    pub fn spawn_local_on<F>(self, future: F, local_set: &LocalSet) -> std::io::Result<AbortHandle>
+    where
+        F: Future<Output = T>,
+        F: 'static,
+    {
+        Ok(self
+            .joinset
+            .insert(self.builder.spawn_local_on(future, local_set)?))
+    }
+}
+
+// Manual `Debug` impl so that `Builder` is `Debug` regardless of whether `T` is
+// `Debug`.
+#[cfg(all(tokio_unstable, feature = "tracing"))]
+#[cfg_attr(docsrs, doc(cfg(all(tokio_unstable, feature = "tracing"))))]
+impl<'a, T> fmt::Debug for Builder<'a, T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("join_set::Builder")
+            .field("joinset", &self.joinset)
+            .field("builder", &self.builder)
+            .finish()
+    }
+}
diff --git a/vendor/tokio/src/task/local.rs b/vendor/tokio/src/task/local.rs
index 37c2c508a..734b95587 100644
--- a/vendor/tokio/src/task/local.rs
+++ b/vendor/tokio/src/task/local.rs
@@ -1,15 +1,18 @@
 //! Runs `!Send` futures on the current thread.
+use crate::loom::cell::UnsafeCell;
 use crate::loom::sync::{Arc, Mutex};
-use crate::runtime::task::{self, JoinHandle, Task};
+use crate::runtime::task::{self, JoinHandle, LocalOwnedTasks, Task};
+use crate::runtime::{context, ThreadId};
 use crate::sync::AtomicWaker;
-use crate::util::linked_list::{Link, LinkedList};
+use crate::util::RcCell;
 
-use std::cell::{Cell, RefCell};
+use std::cell::Cell;
 use std::collections::VecDeque;
 use std::fmt;
 use std::future::Future;
 use std::marker::PhantomData;
 use std::pin::Pin;
+use std::rc::Rc;
 use std::task::Poll;
 
 use pin_project_lite::pin_project;
@@ -31,14 +34,14 @@ cfg_rt! {
     /// async fn main() {
     ///     // `Rc` does not implement `Send`, and thus may not be sent between
     ///     // threads safely.
-    ///     let unsend_data = Rc::new("my unsend data...");
+    ///     let nonsend_data = Rc::new("my nonsend data...");
     ///
-    ///     let unsend_data = unsend_data.clone();
-    ///     // Because the `async` block here moves `unsend_data`, the future is `!Send`.
+    ///     let nonsend_data = nonsend_data.clone();
+    ///     // Because the `async` block here moves `nonsend_data`, the future is `!Send`.
     ///     // Since `tokio::spawn` requires the spawned future to implement `Send`, this
     ///     // will not compile.
     ///     tokio::spawn(async move {
-    ///         println!("{}", unsend_data);
+    ///         println!("{}", nonsend_data);
     ///         // ...
     ///     }).await.unwrap();
     /// }
@@ -57,18 +60,18 @@ cfg_rt! {
     ///
     /// #[tokio::main]
     /// async fn main() {
-    ///     let unsend_data = Rc::new("my unsend data...");
+    ///     let nonsend_data = Rc::new("my nonsend data...");
     ///
     ///     // Construct a local task set that can run `!Send` futures.
     ///     let local = task::LocalSet::new();
     ///
     ///     // Run the local task set.
     ///     local.run_until(async move {
-    ///         let unsend_data = unsend_data.clone();
+    ///         let nonsend_data = nonsend_data.clone();
     ///         // `spawn_local` ensures that the future is spawned on the local
     ///         // task set.
     ///         task::spawn_local(async move {
-    ///             println!("{}", unsend_data);
+    ///             println!("{}", nonsend_data);
     ///             // ...
     ///         }).await.unwrap();
     ///     }).await;
@@ -91,18 +94,18 @@ cfg_rt! {
     ///
     /// #[tokio::main]
     /// async fn main() {
-    ///     let unsend_data = Rc::new("world");
+    ///     let nonsend_data = Rc::new("world");
     ///     let local = task::LocalSet::new();
     ///
-    ///     let unsend_data2 = unsend_data.clone();
+    ///     let nonsend_data2 = nonsend_data.clone();
     ///     local.spawn_local(async move {
     ///         // ...
-    ///         println!("hello {}", unsend_data2)
+    ///         println!("hello {}", nonsend_data2)
     ///     });
     ///
     ///     local.spawn_local(async move {
     ///         time::sleep(time::Duration::from_millis(100)).await;
-    ///         println!("goodbye {}", unsend_data)
+    ///         println!("goodbye {}", nonsend_data)
     ///     });
     ///
     ///     // ...
@@ -159,7 +162,7 @@ cfg_rt! {
     ///                     tokio::task::spawn_local(run_task(new_task));
     ///                 }
     ///                 // If the while loop returns, then all the LocalSpawner
-    ///                 // objects have have been dropped.
+    ///                 // objects have been dropped.
     ///             });
     ///
     ///             // This will return once all senders are dropped and all
@@ -211,41 +214,57 @@ cfg_rt! {
     /// [`task::spawn_local`]: fn@spawn_local
     /// [`mpsc`]: mod@crate::sync::mpsc
     pub struct LocalSet {
-        /// Current scheduler tick
+        /// Current scheduler tick.
         tick: Cell<u8>,
 
-        /// State available from thread-local
-        context: Context,
+        /// State available from thread-local.
+        context: Rc<Context>,
 
         /// This type should not be Send.
         _not_send: PhantomData<*const ()>,
     }
 }
 
-/// State available from the thread-local
+/// State available from the thread-local.
 struct Context {
-    /// Owned task set and local run queue
-    tasks: RefCell<Tasks>,
-
     /// State shared between threads.
     shared: Arc<Shared>,
-}
 
-struct Tasks {
-    /// Collection of all active tasks spawned onto this executor.
-    owned: LinkedList<Task<Arc<Shared>>, <Task<Arc<Shared>> as Link>::Target>,
-
-    /// Local run queue sender and receiver.
-    queue: VecDeque<task::Notified<Arc<Shared>>>,
+    /// True if a task panicked without being handled and the local set is
+    /// configured to shutdown on unhandled panic.
+    unhandled_panic: Cell<bool>,
 }
 
 /// LocalSet state shared between threads.
 struct Shared {
-    /// Remote run queue sender
+    /// # Safety
+    ///
+    /// This field must *only* be accessed from the thread that owns the
+    /// `LocalSet` (i.e., `Thread::current().id() == owner`).
+    local_state: LocalState,
+
+    /// Remote run queue sender.
     queue: Mutex<Option<VecDeque<task::Notified<Arc<Shared>>>>>,
 
-    /// Wake the `LocalSet` task
+    /// Wake the `LocalSet` task.
     waker: AtomicWaker,
+
+    /// How to respond to unhandled task panics.
+    #[cfg(tokio_unstable)]
+    pub(crate) unhandled_panic: crate::runtime::UnhandledPanic,
+}
+
+/// Tracks the `LocalSet` state that must only be accessed from the thread that
+/// created the `LocalSet`.
+struct LocalState {
+    /// The `ThreadId` of the thread that owns the `LocalSet`.
+    owner: ThreadId,
+
+    /// Local run queue sender and receiver.
+    local_queue: UnsafeCell<VecDeque<task::Notified<Arc<Shared>>>>,
+
+    /// Collection of all active tasks spawned onto this executor.
+    owned: LocalOwnedTasks<Arc<Shared>>,
 }
 
 pin_project! {
@@ -257,17 +276,30 @@ pin_project! {
     }
 }
 
-scoped_thread_local!(static CURRENT: Context);
+tokio_thread_local!(static CURRENT: LocalData = const { LocalData {
+    ctx: RcCell::new(),
+} });
+
+struct LocalData {
+    ctx: RcCell<Context>,
+}
 
 cfg_rt! {
-    /// Spawns a `!Send` future on the local task set.
+    /// Spawns a `!Send` future on the current [`LocalSet`].
+    ///
+    /// The spawned future will run on the same thread that called `spawn_local`.
     ///
-    /// The spawned future will be run on the same thread that called `spawn_local.`
-    /// This may only be called from the context of a local task set.
+    /// The provided future will start running in the background immediately
+    /// when `spawn_local` is called, even if you don't await the returned
+    /// `JoinHandle`.
     ///
     /// # Panics
     ///
-    /// - This function panics if called outside of a local task set.
+    /// This function panics if called outside of a [`LocalSet`].
+    ///
+    /// Note that if [`tokio::spawn`] is used from within a `LocalSet`, the
+    /// resulting new task will _not_ be inside the `LocalSet`, so you must use
+    /// `spawn_local` if you want to stay within the `LocalSet`.
     ///
     /// # Examples
     ///
@@ -277,21 +309,24 @@ cfg_rt! {
     ///
     /// #[tokio::main]
     /// async fn main() {
-    ///     let unsend_data = Rc::new("my unsend data...");
+    ///     let nonsend_data = Rc::new("my nonsend data...");
     ///
     ///     let local = task::LocalSet::new();
     ///
     ///     // Run the local task set.
     ///     local.run_until(async move {
-    ///         let unsend_data = unsend_data.clone();
+    ///         let nonsend_data = nonsend_data.clone();
     ///         task::spawn_local(async move {
-    ///             println!("{}", unsend_data);
+    ///             println!("{}", nonsend_data);
     ///             // ...
     ///         }).await.unwrap();
     ///     }).await;
     /// }
     /// ```
-    #[cfg_attr(tokio_track_caller, track_caller)]
+    ///
+    /// [`LocalSet`]: struct@crate::task::LocalSet
+    /// [`tokio::spawn`]: fn@crate::task::spawn
+    #[track_caller]
     pub fn spawn_local<F>(future: F) -> JoinHandle<F::Output>
     where
         F: Future + 'static,
@@ -300,58 +335,94 @@ cfg_rt! {
         spawn_local_inner(future, None)
     }
 
+
+    #[track_caller]
     pub(super) fn spawn_local_inner<F>(future: F, name: Option<&str>) -> JoinHandle<F::Output>
     where F: Future + 'static,
           F::Output: 'static
     {
-        let future = crate::util::trace::task(future, "local", name);
-        CURRENT.with(|maybe_cx| {
-            let cx = maybe_cx
-                .expect("`spawn_local` called from outside of a `task::LocalSet`");
-
-            // Safety: Tasks are only polled and dropped from the thread that
-            // spawns them.
-            let (task, handle) = unsafe { task::joinable_local(future) };
-            cx.tasks.borrow_mut().queue.push_back(task);
-            handle
-        })
+        match CURRENT.with(|LocalData { ctx, .. }| ctx.get()) {
+            None => panic!("`spawn_local` called from outside of a `task::LocalSet`"),
+            Some(cx) => cx.spawn(future, name)
+       }
     }
 }
 
-/// Initial queue capacity
+/// Initial queue capacity.
 const INITIAL_CAPACITY: usize = 64;
 
 /// Max number of tasks to poll per tick.
 const MAX_TASKS_PER_TICK: usize = 61;
 
-/// How often it check the remote queue first
+/// How often it check the remote queue first.
 const REMOTE_FIRST_INTERVAL: u8 = 31;
 
+/// Context guard for LocalSet
+pub struct LocalEnterGuard(Option<Rc<Context>>);
+
+impl Drop for LocalEnterGuard {
+    fn drop(&mut self) {
+        CURRENT.with(|LocalData { ctx, .. }| {
+            ctx.set(self.0.take());
+        })
+    }
+}
+
+impl fmt::Debug for LocalEnterGuard {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("LocalEnterGuard").finish()
+    }
+}
+
 impl LocalSet {
     /// Returns a new local task set.
     pub fn new() -> LocalSet {
+        let owner = context::thread_id().expect("cannot create LocalSet during thread shutdown");
+
         LocalSet {
             tick: Cell::new(0),
-            context: Context {
-                tasks: RefCell::new(Tasks {
-                    owned: LinkedList::new(),
-                    queue: VecDeque::with_capacity(INITIAL_CAPACITY),
-                }),
+            context: Rc::new(Context {
                 shared: Arc::new(Shared {
+                    local_state: LocalState {
+                        owner,
+                        owned: LocalOwnedTasks::new(),
+                        local_queue: UnsafeCell::new(VecDeque::with_capacity(INITIAL_CAPACITY)),
+                    },
                     queue: Mutex::new(Some(VecDeque::with_capacity(INITIAL_CAPACITY))),
                     waker: AtomicWaker::new(),
+                    #[cfg(tokio_unstable)]
+                    unhandled_panic: crate::runtime::UnhandledPanic::Ignore,
                 }),
-            },
+                unhandled_panic: Cell::new(false),
+            }),
             _not_send: PhantomData,
         }
     }
 
+    /// Enters the context of this `LocalSet`.
+    ///
+    /// The [`spawn_local`] method will spawn tasks on the `LocalSet` whose
+    /// context you are inside.
+    ///
+    /// [`spawn_local`]: fn@crate::task::spawn_local
+    pub fn enter(&self) -> LocalEnterGuard {
+        CURRENT.with(|LocalData { ctx, .. }| {
+            let old = ctx.replace(Some(self.context.clone()));
+            LocalEnterGuard(old)
+        })
+    }
+
     /// Spawns a `!Send` task onto the local task set.
     ///
     /// This task is guaranteed to be run on the current thread.
     ///
     /// Unlike the free function [`spawn_local`], this method may be used to
-    /// spawn local tasks when the task set is _not_ running. For example:
+    /// spawn local tasks when the `LocalSet` is _not_ running. The provided
+    /// future will start running once the `LocalSet` is next started, even if
+    /// you don't await the returned `JoinHandle`.
+    ///
+    /// # Examples
+    ///
     /// ```rust
     /// use tokio::task;
     ///
@@ -382,17 +453,13 @@ impl LocalSet {
     /// }
     /// ```
     /// [`spawn_local`]: fn@spawn_local
-    #[cfg_attr(tokio_track_caller, track_caller)]
+    #[track_caller]
     pub fn spawn_local<F>(&self, future: F) -> JoinHandle<F::Output>
     where
         F: Future + 'static,
         F::Output: 'static,
     {
-        let future = crate::util::trace::task(future, "local", None);
-        let (task, handle) = unsafe { task::joinable_local(future) };
-        self.context.tasks.borrow_mut().queue.push_back(task);
-        self.context.shared.waker.wake();
-        handle
+        self.spawn_named(future, None)
     }
 
     /// Runs a future to completion on the provided runtime, driving any local
@@ -457,6 +524,7 @@ impl LocalSet {
     /// [`Runtime::block_on`]: method@crate::runtime::Runtime::block_on
     /// [in-place blocking]: fn@crate::task::block_in_place
     /// [`spawn_blocking`]: fn@crate::task::spawn_blocking
+    #[track_caller]
     #[cfg(feature = "rt")]
     #[cfg_attr(docsrs, doc(cfg(feature = "rt")))]
     pub fn block_on<F>(&self, rt: &crate::runtime::Runtime, future: F) -> F::Output
@@ -466,7 +534,7 @@ impl LocalSet {
         rt.block_on(self.run_until(future))
     }
 
-    /// Run a future to completion on the local set, returning its output.
+    /// Runs a future to completion on the local set, returning its output.
     ///
     /// This returns a future that runs the given future with a local set,
     /// allowing it to call [`spawn_local`] to spawn additional `!Send` futures.
@@ -505,10 +573,36 @@ impl LocalSet {
         run_until.await
     }
 
-    /// Tick the scheduler, returning whether the local future needs to be
+    pub(in crate::task) fn spawn_named<F>(
+        &self,
+        future: F,
+        name: Option<&str>,
+    ) -> JoinHandle<F::Output>
+    where
+        F: Future + 'static,
+        F::Output: 'static,
+    {
+        let handle = self.context.spawn(future, name);
+
+        // Because a task was spawned from *outside* the `LocalSet`, wake the
+        // `LocalSet` future to execute the new task, if it hasn't been woken.
+        //
+        // Spawning via the free fn `spawn` does not require this, as it can
+        // only be called from *within* a future executing on the `LocalSet` —
+        // in that case, the `LocalSet` must already be awake.
+        self.context.shared.waker.wake();
+        handle
+    }
+
+    /// Ticks the scheduler, returning whether the local future needs to be
     /// notified again.
     fn tick(&self) -> bool {
         for _ in 0..MAX_TASKS_PER_TICK {
+            // Make sure we didn't hit an unhandled panic
+            if self.context.unhandled_panic.get() {
+                panic!("a spawned task panicked and the LocalSet is configured to shutdown on unhandled panic");
+            }
+
             match self.next_task() {
                 // Run the task
                 //
@@ -518,7 +612,7 @@ impl LocalSet {
                 // task initially. Because `LocalSet` itself is `!Send`, and
                 // `spawn_local` spawns into the `LocalSet` on the current
                 // thread, the invariant is maintained.
-                Some(task) => crate::coop::budget(|| task.run()),
+                Some(task) => crate::runtime::coop::budget(|| task.run()),
                 // We have fully drained the queue of notified tasks, so the
                 // local future doesn't need to be notified again — it can wait
                 // until something else wakes a task in the local set.
@@ -529,37 +623,168 @@ impl LocalSet {
         true
     }
 
-    fn next_task(&self) -> Option<task::Notified<Arc<Shared>>> {
+    fn next_task(&self) -> Option<task::LocalNotified<Arc<Shared>>> {
         let tick = self.tick.get();
         self.tick.set(tick.wrapping_add(1));
 
-        if tick % REMOTE_FIRST_INTERVAL == 0 {
+        let task = if tick % REMOTE_FIRST_INTERVAL == 0 {
             self.context
                 .shared
                 .queue
                 .lock()
                 .as_mut()
                 .and_then(|queue| queue.pop_front())
-                .or_else(|| self.context.tasks.borrow_mut().queue.pop_front())
+                .or_else(|| self.pop_local())
         } else {
-            self.context
-                .tasks
-                .borrow_mut()
-                .queue
-                .pop_front()
-                .or_else(|| {
-                    self.context
-                        .shared
-                        .queue
-                        .lock()
-                        .as_mut()
-                        .and_then(|queue| queue.pop_front())
-                })
+            self.pop_local().or_else(|| {
+                self.context
+                    .shared
+                    .queue
+                    .lock()
+                    .as_mut()
+                    .and_then(|queue| queue.pop_front())
+            })
+        };
+
+        task.map(|task| unsafe {
+            // Safety: because the `LocalSet` itself is `!Send`, we know we are
+            // on the same thread if we have access to the `LocalSet`, and can
+            // therefore access the local run queue.
+            self.context.shared.local_state.assert_owner(task)
+        })
+    }
+
+    fn pop_local(&self) -> Option<task::Notified<Arc<Shared>>> {
+        unsafe {
+            // Safety: because the `LocalSet` itself is `!Send`, we know we are
+            // on the same thread if we have access to the `LocalSet`, and can
+            // therefore access the local run queue.
+            self.context.shared.local_state.task_pop_front()
         }
     }
 
     fn with<T>(&self, f: impl FnOnce() -> T) -> T {
-        CURRENT.set(&self.context, f)
+        CURRENT.with(|LocalData { ctx, .. }| {
+            struct Reset<'a> {
+                ctx_ref: &'a RcCell<Context>,
+                val: Option<Rc<Context>>,
+            }
+            impl<'a> Drop for Reset<'a> {
+                fn drop(&mut self) {
+                    self.ctx_ref.set(self.val.take());
+                }
+            }
+            let old = ctx.replace(Some(self.context.clone()));
+
+            let _reset = Reset {
+                ctx_ref: ctx,
+                val: old,
+            };
+
+            f()
+        })
+    }
+
+    /// This method is like `with`, but it just calls `f` without setting the thread-local if that
+    /// fails.
+    fn with_if_possible<T>(&self, f: impl FnOnce() -> T) -> T {
+        let mut f = Some(f);
+
+        let res = CURRENT.try_with(|LocalData { ctx, .. }| {
+            struct Reset<'a> {
+                ctx_ref: &'a RcCell<Context>,
+                val: Option<Rc<Context>>,
+            }
+            impl<'a> Drop for Reset<'a> {
+                fn drop(&mut self) {
+                    self.ctx_ref.replace(self.val.take());
+                }
+            }
+            let old = ctx.replace(Some(self.context.clone()));
+
+            let _reset = Reset {
+                ctx_ref: ctx,
+                val: old,
+            };
+
+            (f.take().unwrap())()
+        });
+
+        match res {
+            Ok(res) => res,
+            Err(_access_error) => (f.take().unwrap())(),
+        }
+    }
+}
+
+cfg_unstable! {
+    impl LocalSet {
+        /// Configure how the `LocalSet` responds to an unhandled panic on a
+        /// spawned task.
+        ///
+        /// By default, an unhandled panic (i.e. a panic not caught by
+        /// [`std::panic::catch_unwind`]) has no impact on the `LocalSet`'s
+        /// execution. The panic is error value is forwarded to the task's
+        /// [`JoinHandle`] and all other spawned tasks continue running.
+        ///
+        /// The `unhandled_panic` option enables configuring this behavior.
+        ///
+        /// * `UnhandledPanic::Ignore` is the default behavior. Panics on
+        ///   spawned tasks have no impact on the `LocalSet`'s execution.
+        /// * `UnhandledPanic::ShutdownRuntime` will force the `LocalSet` to
+        ///   shutdown immediately when a spawned task panics even if that
+        ///   task's `JoinHandle` has not been dropped. All other spawned tasks
+        ///   will immediately terminate and further calls to
+        ///   [`LocalSet::block_on`] and [`LocalSet::run_until`] will panic.
+        ///
+        /// # Panics
+        ///
+        /// This method panics if called after the `LocalSet` has started
+        /// running.
+        ///
+        /// # Unstable
+        ///
+        /// This option is currently unstable and its implementation is
+        /// incomplete. The API may change or be removed in the future. See
+        /// tokio-rs/tokio#4516 for more details.
+        ///
+        /// # Examples
+        ///
+        /// The following demonstrates a `LocalSet` configured to shutdown on
+        /// panic. The first spawned task panics and results in the `LocalSet`
+        /// shutting down. The second spawned task never has a chance to
+        /// execute. The call to `run_until` will panic due to the runtime being
+        /// forcibly shutdown.
+        ///
+        /// ```should_panic
+        /// use tokio::runtime::UnhandledPanic;
+        ///
+        /// # #[tokio::main]
+        /// # async fn main() {
+        /// tokio::task::LocalSet::new()
+        ///     .unhandled_panic(UnhandledPanic::ShutdownRuntime)
+        ///     .run_until(async {
+        ///         tokio::task::spawn_local(async { panic!("boom"); });
+        ///         tokio::task::spawn_local(async {
+        ///             // This task never completes
+        ///         });
+        ///
+        ///         // Do some work, but `run_until` will panic before it completes
+        /// # loop { tokio::task::yield_now().await; }
+        ///     })
+        ///     .await;
+        /// # }
+        /// ```
+        ///
+        /// [`JoinHandle`]: struct@crate::task::JoinHandle
+        pub fn unhandled_panic(&mut self, behavior: crate::runtime::UnhandledPanic) -> &mut Self {
+            // TODO: This should be set as a builder
+            Rc::get_mut(&mut self.context)
+                .and_then(|ctx| Arc::get_mut(&mut ctx.shared))
+                .expect("Unhandled Panic behavior modified after starting LocalSet")
+                .unhandled_panic = behavior;
+            self
+        }
     }
 }
 
@@ -581,7 +806,10 @@ impl Future for LocalSet {
             // there are still tasks remaining in the run queue.
             cx.waker().wake_by_ref();
             Poll::Pending
-        } else if self.context.tasks.borrow().owned.is_empty() {
+
+        // Safety: called from the thread that owns `LocalSet`. Because
+        // `LocalSet` is `!Send`, this is safe.
+        } else if unsafe { self.context.shared.local_state.owned_is_empty() } {
             // If the scheduler has no remaining futures, we're done!
             Poll::Ready(())
         } else {
@@ -601,35 +829,79 @@ impl Default for LocalSet {
 
 impl Drop for LocalSet {
     fn drop(&mut self) {
-        self.with(|| {
-            // Loop required here to ensure borrow is dropped between iterations
-            #[allow(clippy::while_let_loop)]
-            loop {
-                let task = match self.context.tasks.borrow_mut().owned.pop_back() {
-                    Some(task) => task,
-                    None => break,
-                };
-
-                // Safety: same as `run_unchecked`.
-                task.shutdown();
+        self.with_if_possible(|| {
+            // Shut down all tasks in the LocalOwnedTasks and close it to
+            // prevent new tasks from ever being added.
+            unsafe {
+                // Safety: called from the thread that owns `LocalSet`
+                self.context.shared.local_state.close_and_shutdown_all();
             }
 
-            for task in self.context.tasks.borrow_mut().queue.drain(..) {
-                task.shutdown();
+            // We already called shutdown on all tasks above, so there is no
+            // need to call shutdown.
+
+            // Safety: note that this *intentionally* bypasses the unsafe
+            // `Shared::local_queue()` method. This is in order to avoid the
+            // debug assertion that we are on the thread that owns the
+            // `LocalSet`, because on some systems (e.g. at least some macOS
+            // versions), attempting to get the current thread ID can panic due
+            // to the thread's local data that stores the thread ID being
+            // dropped *before* the `LocalSet`.
+            //
+            // Despite avoiding the assertion here, it is safe for us to access
+            // the local queue in `Drop`, because the `LocalSet` itself is
+            // `!Send`, so we can reasonably guarantee that it will not be
+            // `Drop`ped from another thread.
+            let local_queue = unsafe {
+                // Safety: called from the thread that owns `LocalSet`
+                self.context.shared.local_state.take_local_queue()
+            };
+            for task in local_queue {
+                drop(task);
             }
 
             // Take the queue from the Shared object to prevent pushing
             // notifications to it in the future.
             let queue = self.context.shared.queue.lock().take().unwrap();
             for task in queue {
-                task.shutdown();
+                drop(task);
             }
 
-            assert!(self.context.tasks.borrow().owned.is_empty());
+            // Safety: called from the thread that owns `LocalSet`
+            assert!(unsafe { self.context.shared.local_state.owned_is_empty() });
         });
     }
 }
 
+// === impl Context ===
+
+impl Context {
+    #[track_caller]
+    fn spawn<F>(&self, future: F, name: Option<&str>) -> JoinHandle<F::Output>
+    where
+        F: Future + 'static,
+        F::Output: 'static,
+    {
+        let id = crate::runtime::task::Id::next();
+        let future = crate::util::trace::task(future, "local", name, id.as_u64());
+
+        // Safety: called from the thread that owns the `LocalSet`
+        let (handle, notified) = {
+            self.shared.local_state.assert_called_from_owner_thread();
+            self.shared
+                .local_state
+                .owned
+                .bind(future, self.shared.clone(), id)
+        };
+
+        if let Some(notified) = notified {
+            self.shared.schedule(notified);
+        }
+
+        handle
+    }
+}
+
 // === impl LocalFuture ===
 
 impl<T: Future> Future for RunUntil<'_, T> {
@@ -645,10 +917,10 @@ impl<T: Future> Future for RunUntil<'_, T> {
                 .waker
                 .register_by_ref(cx.waker());
 
-            let _no_blocking = crate::runtime::enter::disallow_blocking();
+            let _no_blocking = crate::runtime::context::disallow_block_in_place();
             let f = me.future;
 
-            if let Poll::Ready(output) = crate::coop::budget(|| f.poll(cx)) {
+            if let Poll::Ready(output) = f.poll(cx) {
                 return Poll::Ready(output);
             }
 
@@ -666,21 +938,41 @@ impl<T: Future> Future for RunUntil<'_, T> {
 impl Shared {
     /// Schedule the provided task on the scheduler.
     fn schedule(&self, task: task::Notified<Arc<Self>>) {
-        CURRENT.with(|maybe_cx| match maybe_cx {
-            Some(cx) if cx.shared.ptr_eq(self) => {
-                cx.tasks.borrow_mut().queue.push_back(task);
-            }
-            _ => {
-                // First check whether the queue is still there (if not, the
-                // LocalSet is dropped). Then push to it if so, and if not,
-                // do nothing.
-                let mut lock = self.queue.lock();
-
-                if let Some(queue) = lock.as_mut() {
-                    queue.push_back(task);
-                    drop(lock);
+        CURRENT.with(|localdata| {
+            match localdata.ctx.get() {
+                Some(cx) if cx.shared.ptr_eq(self) => unsafe {
+                    // Safety: if the current `LocalSet` context points to this
+                    // `LocalSet`, then we are on the thread that owns it.
+                    cx.shared.local_state.task_push_back(task);
+                },
+
+                // We are on the thread that owns the `LocalSet`, so we can
+                // wake to the local queue.
+                _ if context::thread_id().ok() == Some(self.local_state.owner) => {
+                    unsafe {
+                        // Safety: we just checked that the thread ID matches
+                        // the localset's owner, so this is safe.
+                        self.local_state.task_push_back(task);
+                    }
+                    // We still have to wake the `LocalSet`, because it isn't
+                    // currently being polled.
                     self.waker.wake();
                 }
+
+                // We are *not* on the thread that owns the `LocalSet`, so we
+                // have to wake to the remote queue.
+                _ => {
+                    // First, check whether the queue is still there (if not, the
+                    // LocalSet is dropped). Then push to it if so, and if not,
+                    // do nothing.
+                    let mut lock = self.queue.lock();
+
+                    if let Some(queue) = lock.as_mut() {
+                        queue.push_back(task);
+                        drop(lock);
+                        self.waker.wake();
+                    }
+                }
             }
         });
     }
@@ -690,31 +982,194 @@ impl Shared {
     }
 }
 
+// This is safe because (and only because) we *pinky pwomise* to never touch the
+// local run queue except from the thread that owns the `LocalSet`.
+unsafe impl Sync for Shared {}
+
 impl task::Schedule for Arc<Shared> {
-    fn bind(task: Task<Self>) -> Arc<Shared> {
-        CURRENT.with(|maybe_cx| {
-            let cx = maybe_cx.expect("scheduler context missing");
-            cx.tasks.borrow_mut().owned.push_front(task);
-            cx.shared.clone()
-        })
+    fn release(&self, task: &Task<Self>) -> Option<Task<Self>> {
+        // Safety, this is always called from the thread that owns `LocalSet`
+        unsafe { self.local_state.task_remove(task) }
     }
 
-    fn release(&self, task: &Task<Self>) -> Option<Task<Self>> {
-        use std::ptr::NonNull;
+    fn schedule(&self, task: task::Notified<Self>) {
+        Shared::schedule(self, task);
+    }
+
+    cfg_unstable! {
+        fn unhandled_panic(&self) {
+            use crate::runtime::UnhandledPanic;
+
+            match self.unhandled_panic {
+                UnhandledPanic::Ignore => {
+                    // Do nothing
+                }
+                UnhandledPanic::ShutdownRuntime => {
+                    // This hook is only called from within the runtime, so
+                    // `CURRENT` should match with `&self`, i.e. there is no
+                    // opportunity for a nested scheduler to be called.
+                    CURRENT.with(|LocalData { ctx, .. }| match ctx.get() {
+                        Some(cx) if Arc::ptr_eq(self, &cx.shared) => {
+                            cx.unhandled_panic.set(true);
+                            // Safety: this is always called from the thread that owns `LocalSet`
+                            unsafe { cx.shared.local_state.close_and_shutdown_all(); }
+                        }
+                        _ => unreachable!("runtime core not set in CURRENT thread-local"),
+                    })
+                }
+            }
+        }
+    }
+}
 
-        CURRENT.with(|maybe_cx| {
-            let cx = maybe_cx.expect("scheduler context missing");
+impl LocalState {
+    unsafe fn task_pop_front(&self) -> Option<task::Notified<Arc<Shared>>> {
+        // The caller ensures it is called from the same thread that owns
+        // the LocalSet.
+        self.assert_called_from_owner_thread();
 
-            assert!(cx.shared.ptr_eq(self));
+        self.local_queue.with_mut(|ptr| (*ptr).pop_front())
+    }
 
-            let ptr = NonNull::from(task.header());
-            // safety: task must be contained by list. It is inserted into the
-            // list in `bind`.
-            unsafe { cx.tasks.borrow_mut().owned.remove(ptr) }
-        })
+    unsafe fn task_push_back(&self, task: task::Notified<Arc<Shared>>) {
+        // The caller ensures it is called from the same thread that owns
+        // the LocalSet.
+        self.assert_called_from_owner_thread();
+
+        self.local_queue.with_mut(|ptr| (*ptr).push_back(task))
     }
 
-    fn schedule(&self, task: task::Notified<Self>) {
-        Shared::schedule(self, task);
+    unsafe fn take_local_queue(&self) -> VecDeque<task::Notified<Arc<Shared>>> {
+        // The caller ensures it is called from the same thread that owns
+        // the LocalSet.
+        self.assert_called_from_owner_thread();
+
+        self.local_queue.with_mut(|ptr| std::mem::take(&mut (*ptr)))
+    }
+
+    unsafe fn task_remove(&self, task: &Task<Arc<Shared>>) -> Option<Task<Arc<Shared>>> {
+        // The caller ensures it is called from the same thread that owns
+        // the LocalSet.
+        self.assert_called_from_owner_thread();
+
+        self.owned.remove(task)
+    }
+
+    /// Returns true if the `LocalSet` does not have any spawned tasks
+    unsafe fn owned_is_empty(&self) -> bool {
+        // The caller ensures it is called from the same thread that owns
+        // the LocalSet.
+        self.assert_called_from_owner_thread();
+
+        self.owned.is_empty()
+    }
+
+    unsafe fn assert_owner(
+        &self,
+        task: task::Notified<Arc<Shared>>,
+    ) -> task::LocalNotified<Arc<Shared>> {
+        // The caller ensures it is called from the same thread that owns
+        // the LocalSet.
+        self.assert_called_from_owner_thread();
+
+        self.owned.assert_owner(task)
+    }
+
+    unsafe fn close_and_shutdown_all(&self) {
+        // The caller ensures it is called from the same thread that owns
+        // the LocalSet.
+        self.assert_called_from_owner_thread();
+
+        self.owned.close_and_shutdown_all()
+    }
+
+    #[track_caller]
+    fn assert_called_from_owner_thread(&self) {
+        // FreeBSD has some weirdness around thread-local destruction.
+        // TODO: remove this hack when thread id is cleaned up
+        #[cfg(not(any(target_os = "openbsd", target_os = "freebsd")))]
+        debug_assert!(
+            // if we couldn't get the thread ID because we're dropping the local
+            // data, skip the assertion --- the `Drop` impl is not going to be
+            // called from another thread, because `LocalSet` is `!Send`
+            context::thread_id()
+                .map(|id| id == self.owner)
+                .unwrap_or(true),
+            "`LocalSet`'s local run queue must not be accessed by another thread!"
+        );
+    }
+}
+
+// This is `Send` because it is stored in `Shared`. It is up to the caller to
+// ensure they are on the same thread that owns the `LocalSet`.
+unsafe impl Send for LocalState {}
+
+#[cfg(all(test, not(loom)))]
+mod tests {
+    use super::*;
+
+    // Does a `LocalSet` running on a current-thread runtime...basically work?
+    //
+    // This duplicates a test in `tests/task_local_set.rs`, but because this is
+    // a lib test, it wil run under Miri, so this is necessary to catch stacked
+    // borrows violations in the `LocalSet` implementation.
+    #[test]
+    fn local_current_thread_scheduler() {
+        let f = async {
+            LocalSet::new()
+                .run_until(async {
+                    spawn_local(async {}).await.unwrap();
+                })
+                .await;
+        };
+        crate::runtime::Builder::new_current_thread()
+            .build()
+            .expect("rt")
+            .block_on(f)
+    }
+
+    // Tests that when a task on a `LocalSet` is woken by an io driver on the
+    // same thread, the task is woken to the localset's local queue rather than
+    // its remote queue.
+    //
+    // This test has to be defined in the `local.rs` file as a lib test, rather
+    // than in `tests/`, because it makes assertions about the local set's
+    // internal state.
+    #[test]
+    fn wakes_to_local_queue() {
+        use super::*;
+        use crate::sync::Notify;
+        let rt = crate::runtime::Builder::new_current_thread()
+            .build()
+            .expect("rt");
+        rt.block_on(async {
+            let local = LocalSet::new();
+            let notify = Arc::new(Notify::new());
+            let task = local.spawn_local({
+                let notify = notify.clone();
+                async move {
+                    notify.notified().await;
+                }
+            });
+            let mut run_until = Box::pin(local.run_until(async move {
+                task.await.unwrap();
+            }));
+
+            // poll the run until future once
+            crate::future::poll_fn(|cx| {
+                let _ = run_until.as_mut().poll(cx);
+                Poll::Ready(())
+            })
+            .await;
+
+            notify.notify_one();
+            let task = unsafe { local.context.shared.local_state.task_pop_front() };
+            // TODO(eliza): it would be nice to be able to assert that this is
+            // the local task.
+            assert!(
+                task.is_some(),
+                "task should have been notified to the LocalSet's local queue"
+            );
+        })
     }
 }
diff --git a/vendor/tokio/src/task/mod.rs b/vendor/tokio/src/task/mod.rs
index ae4c35c9c..9b7537018 100644
--- a/vendor/tokio/src/task/mod.rs
+++ b/vendor/tokio/src/task/mod.rs
@@ -243,7 +243,7 @@
 //!
 //! #### unconstrained
 //!
-//! If necessary, [`task::unconstrained`] lets you opt out a future of Tokio's cooperative
+//! If necessary, [`task::unconstrained`] lets you opt a future out of of Tokio's cooperative
 //! scheduling. When a future is wrapped with `unconstrained`, it will never be forced to yield to
 //! Tokio. For example:
 //!
@@ -278,8 +278,10 @@
 cfg_rt! {
     pub use crate::runtime::task::{JoinError, JoinHandle};
 
-    mod blocking;
-    pub use blocking::spawn_blocking;
+    cfg_not_wasi! {
+        mod blocking;
+        pub use blocking::spawn_blocking;
+    }
 
     mod spawn;
     pub use spawn::spawn;
@@ -291,8 +293,13 @@ cfg_rt! {
     mod yield_now;
     pub use yield_now::yield_now;
 
+    cfg_unstable! {
+        mod consume_budget;
+        pub use consume_budget::consume_budget;
+    }
+
     mod local;
-    pub use local::{spawn_local, LocalSet};
+    pub use local::{spawn_local, LocalSet, LocalEnterGuard};
 
     mod task_local;
     pub use task_local::LocalKey;
@@ -300,8 +307,27 @@ cfg_rt! {
     mod unconstrained;
     pub use unconstrained::{unconstrained, Unconstrained};
 
+    #[doc(inline)]
+    pub use join_set::JoinSet;
+    pub use crate::runtime::task::AbortHandle;
+
+    // Uses #[cfg(...)] instead of macro since the macro adds docsrs annotations.
+    #[cfg(not(tokio_unstable))]
+    mod join_set;
+    #[cfg(tokio_unstable)]
+    pub mod join_set;
+
+    cfg_unstable! {
+        pub use crate::runtime::task::{Id, id, try_id};
+    }
+
     cfg_trace! {
         mod builder;
         pub use builder::Builder;
     }
+
+    /// Task-related futures.
+    pub mod futures {
+        pub use super::task_local::TaskLocalFuture;
+    }
 }
diff --git a/vendor/tokio/src/task/spawn.rs b/vendor/tokio/src/task/spawn.rs
index 3c577b82d..23a46d745 100644
--- a/vendor/tokio/src/task/spawn.rs
+++ b/vendor/tokio/src/task/spawn.rs
@@ -1,4 +1,4 @@
-use crate::{task::JoinHandle, util::error::CONTEXT_MISSING_ERROR};
+use crate::task::JoinHandle;
 
 use std::future::Future;
 
@@ -6,11 +6,19 @@ cfg_rt! {
     /// Spawns a new asynchronous task, returning a
     /// [`JoinHandle`](super::JoinHandle) for it.
     ///
+    /// The provided future will start running in the background immediately
+    /// when `spawn` is called, even if you don't await the returned
+    /// `JoinHandle`.
+    ///
     /// Spawning a task enables the task to execute concurrently to other tasks. The
     /// spawned task may execute on the current thread, or it may be sent to a
     /// different thread to be executed. The specifics depend on the current
     /// [`Runtime`](crate::runtime::Runtime) configuration.
     ///
+    /// It is guaranteed that spawn will not synchronously poll the task being spawned.
+    /// This means that calling spawn while holding a lock does not pose a risk of
+    /// deadlocking with the spawned task.
+    ///
     /// There is no guarantee that a spawned task will execute to completion.
     /// When a runtime is shutdown, all outstanding tasks are dropped,
     /// regardless of the lifecycle of that task.
@@ -49,6 +57,37 @@ cfg_rt! {
     /// }
     /// ```
     ///
+    /// To run multiple tasks in parallel and receive their results, join
+    /// handles can be stored in a vector.
+    /// ```
+    /// # #[tokio::main(flavor = "current_thread")] async fn main() {
+    /// async fn my_background_op(id: i32) -> String {
+    ///     let s = format!("Starting background task {}.", id);
+    ///     println!("{}", s);
+    ///     s
+    /// }
+    ///
+    /// let ops = vec![1, 2, 3];
+    /// let mut tasks = Vec::with_capacity(ops.len());
+    /// for op in ops {
+    ///     // This call will make them start running in the background
+    ///     // immediately.
+    ///     tasks.push(tokio::spawn(my_background_op(op)));
+    /// }
+    ///
+    /// let mut outputs = Vec::with_capacity(tasks.len());
+    /// for task in tasks {
+    ///     outputs.push(task.await.unwrap());
+    /// }
+    /// println!("{:?}", outputs);
+    /// # }
+    /// ```
+    /// This example pushes the tasks to `outputs` in the order they were
+    /// started in. If you do not care about the ordering of the outputs, then
+    /// you can also use a [`JoinSet`].
+    ///
+    /// [`JoinSet`]: struct@crate::task::JoinSet
+    ///
     /// # Panics
     ///
     /// Panics if called from **outside** of the Tokio runtime.
@@ -121,23 +160,47 @@ cfg_rt! {
     /// ```text
     /// error[E0391]: cycle detected when processing `main`
     /// ```
-    #[cfg_attr(tokio_track_caller, track_caller)]
+    #[track_caller]
     pub fn spawn<T>(future: T) -> JoinHandle<T::Output>
     where
         T: Future + Send + 'static,
         T::Output: Send + 'static,
     {
-        spawn_inner(future, None)
+        // preventing stack overflows on debug mode, by quickly sending the
+        // task to the heap.
+        if cfg!(debug_assertions) && std::mem::size_of::<T>() > 2048 {
+            spawn_inner(Box::pin(future), None)
+        } else {
+            spawn_inner(future, None)
+        }
     }
 
-    #[cfg_attr(tokio_track_caller, track_caller)]
+    #[track_caller]
     pub(super) fn spawn_inner<T>(future: T, name: Option<&str>) -> JoinHandle<T::Output>
     where
         T: Future + Send + 'static,
         T::Output: Send + 'static,
     {
-        let spawn_handle = crate::runtime::context::spawn_handle().expect(CONTEXT_MISSING_ERROR);
-        let task = crate::util::trace::task(future, "task", name);
-        spawn_handle.spawn(task)
+        use crate::runtime::{context, task};
+
+        #[cfg(all(
+            tokio_unstable,
+            tokio_taskdump,
+            feature = "rt",
+            target_os = "linux",
+            any(
+                target_arch = "aarch64",
+                target_arch = "x86",
+                target_arch = "x86_64"
+            )
+        ))]
+        let future = task::trace::Trace::root(future);
+        let id = task::Id::next();
+        let task = crate::util::trace::task(future, "task", name, id.as_u64());
+
+        match context::with_current(|handle| handle.spawn(task, id)) {
+            Ok(join_handle) => join_handle,
+            Err(e) => panic!("{}", e),
+        }
     }
 }
diff --git a/vendor/tokio/src/task/task_local.rs b/vendor/tokio/src/task/task_local.rs
index 6571ffd7b..eeadfbd3e 100644
--- a/vendor/tokio/src/task/task_local.rs
+++ b/vendor/tokio/src/task/task_local.rs
@@ -2,9 +2,10 @@ use pin_project_lite::pin_project;
 use std::cell::RefCell;
 use std::error::Error;
 use std::future::Future;
+use std::marker::PhantomPinned;
 use std::pin::Pin;
 use std::task::{Context, Poll};
-use std::{fmt, thread};
+use std::{fmt, mem, thread};
 
 /// Declares a new task-local key of type [`tokio::task::LocalKey`].
 ///
@@ -47,9 +48,27 @@ macro_rules! task_local {
 }
 
 #[doc(hidden)]
+#[cfg(not(tokio_no_const_thread_local))]
 #[macro_export]
 macro_rules! __task_local_inner {
     ($(#[$attr:meta])* $vis:vis $name:ident, $t:ty) => {
+        $(#[$attr])*
+        $vis static $name: $crate::task::LocalKey<$t> = {
+            std::thread_local! {
+                static __KEY: std::cell::RefCell<Option<$t>> = const { std::cell::RefCell::new(None) };
+            }
+
+            $crate::task::LocalKey { inner: __KEY }
+        };
+    };
+}
+
+#[doc(hidden)]
+#[cfg(tokio_no_const_thread_local)]
+#[macro_export]
+macro_rules! __task_local_inner {
+    ($(#[$attr:meta])* $vis:vis $name:ident, $t:ty) => {
+        $(#[$attr])*
         $vis static $name: $crate::task::LocalKey<$t> = {
             std::thread_local! {
                 static __KEY: std::cell::RefCell<Option<$t>> = std::cell::RefCell::new(None);
@@ -62,7 +81,7 @@ macro_rules! __task_local_inner {
 
 /// A key for task-local data.
 ///
-/// This type is generated by the `task_local!` macro.
+/// This type is generated by the [`task_local!`] macro.
 ///
 /// Unlike [`std::thread::LocalKey`], `tokio::task::LocalKey` will
 /// _not_ lazily initialize the value on first access. Instead, the
@@ -90,7 +109,9 @@ macro_rules! __task_local_inner {
 /// }).await;
 /// # }
 /// ```
+///
 /// [`std::thread::LocalKey`]: struct@std::thread::LocalKey
+/// [`task_local!`]: ../macro.task_local.html
 #[cfg_attr(docsrs, doc(cfg(feature = "rt")))]
 pub struct LocalKey<T: 'static> {
     #[doc(hidden)]
@@ -102,6 +123,11 @@ impl<T: 'static> LocalKey<T> {
     ///
     /// On completion of `scope`, the task-local will be dropped.
     ///
+    /// ### Panics
+    ///
+    /// If you poll the returned future inside a call to [`with`] or
+    /// [`try_with`] on the same `LocalKey`, then the call to `poll` will panic.
+    ///
     /// ### Examples
     ///
     /// ```
@@ -115,21 +141,29 @@ impl<T: 'static> LocalKey<T> {
     /// }).await;
     /// # }
     /// ```
-    pub async fn scope<F>(&'static self, value: T, f: F) -> F::Output
+    ///
+    /// [`with`]: fn@Self::with
+    /// [`try_with`]: fn@Self::try_with
+    pub fn scope<F>(&'static self, value: T, f: F) -> TaskLocalFuture<T, F>
     where
         F: Future,
     {
         TaskLocalFuture {
-            local: &self,
+            local: self,
             slot: Some(value),
-            future: f,
+            future: Some(f),
+            _pinned: PhantomPinned,
         }
-        .await
     }
 
     /// Sets a value `T` as the task-local value for the closure `F`.
     ///
-    /// On completion of `scope`, the task-local will be dropped.
+    /// On completion of `sync_scope`, the task-local will be dropped.
+    ///
+    /// ### Panics
+    ///
+    /// This method panics if called inside a call to [`with`] or [`try_with`]
+    /// on the same `LocalKey`.
     ///
     /// ### Examples
     ///
@@ -144,32 +178,80 @@ impl<T: 'static> LocalKey<T> {
     /// });
     /// # }
     /// ```
+    ///
+    /// [`with`]: fn@Self::with
+    /// [`try_with`]: fn@Self::try_with
+    #[track_caller]
     pub fn sync_scope<F, R>(&'static self, value: T, f: F) -> R
     where
         F: FnOnce() -> R,
     {
-        let mut scope = TaskLocalFuture {
-            local: &self,
-            slot: Some(value),
-            future: (),
-        };
-        Pin::new(&mut scope).with_task(|_| f())
+        let mut value = Some(value);
+        match self.scope_inner(&mut value, f) {
+            Ok(res) => res,
+            Err(err) => err.panic(),
+        }
+    }
+
+    fn scope_inner<F, R>(&'static self, slot: &mut Option<T>, f: F) -> Result<R, ScopeInnerErr>
+    where
+        F: FnOnce() -> R,
+    {
+        struct Guard<'a, T: 'static> {
+            local: &'static LocalKey<T>,
+            slot: &'a mut Option<T>,
+        }
+
+        impl<'a, T: 'static> Drop for Guard<'a, T> {
+            fn drop(&mut self) {
+                // This should not panic.
+                //
+                // We know that the RefCell was not borrowed before the call to
+                // `scope_inner`, so the only way for this to panic is if the
+                // closure has created but not destroyed a RefCell guard.
+                // However, we never give user-code access to the guards, so
+                // there's no way for user-code to forget to destroy a guard.
+                //
+                // The call to `with` also should not panic, since the
+                // thread-local wasn't destroyed when we first called
+                // `scope_inner`, and it shouldn't have gotten destroyed since
+                // then.
+                self.local.inner.with(|inner| {
+                    let mut ref_mut = inner.borrow_mut();
+                    mem::swap(self.slot, &mut *ref_mut);
+                });
+            }
+        }
+
+        self.inner.try_with(|inner| {
+            inner
+                .try_borrow_mut()
+                .map(|mut ref_mut| mem::swap(slot, &mut *ref_mut))
+        })??;
+
+        let guard = Guard { local: self, slot };
+
+        let res = f();
+
+        drop(guard);
+
+        Ok(res)
     }
 
     /// Accesses the current task-local and runs the provided closure.
     ///
     /// # Panics
     ///
-    /// This function will panic if not called within the context
-    /// of a future containing a task-local with the corresponding key.
+    /// This function will panic if the task local doesn't have a value set.
+    #[track_caller]
     pub fn with<F, R>(&'static self, f: F) -> R
     where
         F: FnOnce(&T) -> R,
     {
-        self.try_with(f).expect(
-            "cannot access a Task Local Storage value \
-             without setting it via `LocalKey::set`",
-        )
+        match self.try_with(f) {
+            Ok(res) => res,
+            Err(_) => panic!("cannot access a task-local storage value without setting it first"),
+        }
     }
 
     /// Accesses the current task-local and runs the provided closure.
@@ -181,19 +263,32 @@ impl<T: 'static> LocalKey<T> {
     where
         F: FnOnce(&T) -> R,
     {
-        self.inner.with(|v| {
-            if let Some(val) = v.borrow().as_ref() {
-                Ok(f(val))
-            } else {
-                Err(AccessError { _private: () })
-            }
-        })
+        // If called after the thread-local storing the task-local is destroyed,
+        // then we are outside of a closure where the task-local is set.
+        //
+        // Therefore, it is correct to return an AccessError if `try_with`
+        // returns an error.
+        let try_with_res = self.inner.try_with(|v| {
+            // This call to `borrow` cannot panic because no user-defined code
+            // runs while a `borrow_mut` call is active.
+            v.borrow().as_ref().map(f)
+        });
+
+        match try_with_res {
+            Ok(Some(res)) => Ok(res),
+            Ok(None) | Err(_) => Err(AccessError { _private: () }),
+        }
     }
 }
 
 impl<T: Copy + 'static> LocalKey<T> {
     /// Returns a copy of the task-local value
     /// if the task-local value implements `Copy`.
+    ///
+    /// # Panics
+    ///
+    /// This function will panic if the task local doesn't have a value set.
+    #[track_caller]
     pub fn get(&'static self) -> T {
         self.with(|v| *v)
     }
@@ -206,55 +301,107 @@ impl<T: 'static> fmt::Debug for LocalKey<T> {
 }
 
 pin_project! {
-    struct TaskLocalFuture<T: StaticLifetime, F> {
+    /// A future that sets a value `T` of a task local for the future `F` during
+    /// its execution.
+    ///
+    /// The value of the task-local must be `'static` and will be dropped on the
+    /// completion of the future.
+    ///
+    /// Created by the function [`LocalKey::scope`](self::LocalKey::scope).
+    ///
+    /// ### Examples
+    ///
+    /// ```
+    /// # async fn dox() {
+    /// tokio::task_local! {
+    ///     static NUMBER: u32;
+    /// }
+    ///
+    /// NUMBER.scope(1, async move {
+    ///     println!("task local value: {}", NUMBER.get());
+    /// }).await;
+    /// # }
+    /// ```
+    pub struct TaskLocalFuture<T, F>
+    where
+        T: 'static,
+    {
         local: &'static LocalKey<T>,
         slot: Option<T>,
         #[pin]
-        future: F,
+        future: Option<F>,
+        #[pin]
+        _pinned: PhantomPinned,
     }
-}
 
-impl<T: 'static, F> TaskLocalFuture<T, F> {
-    fn with_task<F2: FnOnce(Pin<&mut F>) -> R, R>(self: Pin<&mut Self>, f: F2) -> R {
-        struct Guard<'a, T: 'static> {
-            local: &'static LocalKey<T>,
-            slot: &'a mut Option<T>,
-            prev: Option<T>,
-        }
-
-        impl<T> Drop for Guard<'_, T> {
-            fn drop(&mut self) {
-                let value = self.local.inner.with(|c| c.replace(self.prev.take()));
-                *self.slot = value;
+    impl<T: 'static, F> PinnedDrop for TaskLocalFuture<T, F> {
+        fn drop(this: Pin<&mut Self>) {
+            let this = this.project();
+            if mem::needs_drop::<F>() && this.future.is_some() {
+                // Drop the future while the task-local is set, if possible. Otherwise
+                // the future is dropped normally when the `Option<F>` field drops.
+                let mut future = this.future;
+                let _ = this.local.scope_inner(this.slot, || {
+                    future.set(None);
+                });
             }
         }
-
-        let mut project = self.project();
-        let val = project.slot.take();
-
-        let prev = project.local.inner.with(|c| c.replace(val));
-
-        let _guard = Guard {
-            prev,
-            slot: &mut project.slot,
-            local: *project.local,
-        };
-
-        f(project.future)
     }
 }
 
 impl<T: 'static, F: Future> Future for TaskLocalFuture<T, F> {
     type Output = F::Output;
 
+    #[track_caller]
     fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
-        self.with_task(|f| f.poll(cx))
+        let this = self.project();
+        let mut future_opt = this.future;
+
+        let res = this
+            .local
+            .scope_inner(this.slot, || match future_opt.as_mut().as_pin_mut() {
+                Some(fut) => {
+                    let res = fut.poll(cx);
+                    if res.is_ready() {
+                        future_opt.set(None);
+                    }
+                    Some(res)
+                }
+                None => None,
+            });
+
+        match res {
+            Ok(Some(res)) => res,
+            Ok(None) => panic!("`TaskLocalFuture` polled after completion"),
+            Err(err) => err.panic(),
+        }
     }
 }
 
-// Required to make `pin_project` happy.
-trait StaticLifetime: 'static {}
-impl<T: 'static> StaticLifetime for T {}
+impl<T: 'static, F> fmt::Debug for TaskLocalFuture<T, F>
+where
+    T: fmt::Debug,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        /// Format the Option without Some.
+        struct TransparentOption<'a, T> {
+            value: &'a Option<T>,
+        }
+        impl<'a, T: fmt::Debug> fmt::Debug for TransparentOption<'a, T> {
+            fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+                match self.value.as_ref() {
+                    Some(value) => value.fmt(f),
+                    // Hitting the None branch should not be possible.
+                    None => f.pad("<missing>"),
+                }
+            }
+        }
+
+        f.debug_struct("TaskLocalFuture")
+            .field("value", &TransparentOption { value: &self.slot })
+            .finish()
+    }
+}
 
 /// An error returned by [`LocalKey::try_with`](method@LocalKey::try_with).
 #[derive(Clone, Copy, Eq, PartialEq)]
@@ -275,3 +422,30 @@ impl fmt::Display for AccessError {
 }
 
 impl Error for AccessError {}
+
+enum ScopeInnerErr {
+    BorrowError,
+    AccessError,
+}
+
+impl ScopeInnerErr {
+    #[track_caller]
+    fn panic(&self) -> ! {
+        match self {
+            Self::BorrowError => panic!("cannot enter a task-local scope while the task-local storage is borrowed"),
+            Self::AccessError => panic!("cannot enter a task-local scope during or after destruction of the underlying thread-local"),
+        }
+    }
+}
+
+impl From<std::cell::BorrowMutError> for ScopeInnerErr {
+    fn from(_: std::cell::BorrowMutError) -> Self {
+        Self::BorrowError
+    }
+}
+
+impl From<std::thread::AccessError> for ScopeInnerErr {
+    fn from(_: std::thread::AccessError) -> Self {
+        Self::AccessError
+    }
+}
diff --git a/vendor/tokio/src/task/unconstrained.rs b/vendor/tokio/src/task/unconstrained.rs
index 31c732bfc..40384c870 100644
--- a/vendor/tokio/src/task/unconstrained.rs
+++ b/vendor/tokio/src/task/unconstrained.rs
@@ -22,7 +22,7 @@ where
     cfg_coop! {
         fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
             let inner = self.project().inner;
-            crate::coop::with_unconstrained(|| inner.poll(cx))
+            crate::runtime::coop::with_unconstrained(|| inner.poll(cx))
         }
     }
 
diff --git a/vendor/tokio/src/task/yield_now.rs b/vendor/tokio/src/task/yield_now.rs
index 251cb931b..428d124c3 100644
--- a/vendor/tokio/src/task/yield_now.rs
+++ b/vendor/tokio/src/task/yield_now.rs
@@ -1,38 +1,64 @@
+use crate::runtime::context;
+
 use std::future::Future;
 use std::pin::Pin;
 use std::task::{Context, Poll};
 
-cfg_rt! {
-    /// Yields execution back to the Tokio runtime.
-    ///
-    /// A task yields by awaiting on `yield_now()`, and may resume when that
-    /// future completes (with no output.) The current task will be re-added as
-    /// a pending task at the _back_ of the pending queue. Any other pending
-    /// tasks will be scheduled. No other waking is required for the task to
-    /// continue.
-    ///
-    /// See also the usage example in the [task module](index.html#yield_now).
-    #[must_use = "yield_now does nothing unless polled/`await`-ed"]
-    pub async fn yield_now() {
-        /// Yield implementation
-        struct YieldNow {
-            yielded: bool,
-        }
+/// Yields execution back to the Tokio runtime.
+///
+/// A task yields by awaiting on `yield_now()`, and may resume when that future
+/// completes (with no output.) The current task will be re-added as a pending
+/// task at the _back_ of the pending queue. Any other pending tasks will be
+/// scheduled. No other waking is required for the task to continue.
+///
+/// See also the usage example in the [task module](index.html#yield_now).
+///
+/// ## Non-guarantees
+///
+/// This function may not yield all the way up to the executor if there are any
+/// special combinators above it in the call stack. For example, if a
+/// [`tokio::select!`] has another branch complete during the same poll as the
+/// `yield_now()`, then the yield is not propagated all the way up to the
+/// runtime.
+///
+/// It is generally not guaranteed that the runtime behaves like you expect it
+/// to when deciding which task to schedule next after a call to `yield_now()`.
+/// In particular, the runtime may choose to poll the task that just ran
+/// `yield_now()` again immediately without polling any other tasks first. For
+/// example, the runtime will not drive the IO driver between every poll of a
+/// task, and this could result in the runtime polling the current task again
+/// immediately even if there is another task that could make progress if that
+/// other task is waiting for a notification from the IO driver.
+///
+/// In general, changes to the order in which the runtime polls tasks is not
+/// considered a breaking change, and your program should be correct no matter
+/// which order the runtime polls your tasks in.
+///
+/// [`tokio::select!`]: macro@crate::select
+#[cfg_attr(docsrs, doc(cfg(feature = "rt")))]
+pub async fn yield_now() {
+    /// Yield implementation
+    struct YieldNow {
+        yielded: bool,
+    }
 
-        impl Future for YieldNow {
-            type Output = ();
+    impl Future for YieldNow {
+        type Output = ();
 
-            fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<()> {
-                if self.yielded {
-                    return Poll::Ready(());
-                }
+        fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<()> {
+            ready!(crate::trace::trace_leaf(cx));
 
-                self.yielded = true;
-                cx.waker().wake_by_ref();
-                Poll::Pending
+            if self.yielded {
+                return Poll::Ready(());
             }
-        }
 
-        YieldNow { yielded: false }.await
+            self.yielded = true;
+
+            context::defer(cx.waker());
+
+            Poll::Pending
+        }
     }
+
+    YieldNow { yielded: false }.await
 }
diff --git a/vendor/tokio/src/time/clock.rs b/vendor/tokio/src/time/clock.rs
index a44d75f3c..091cf4b19 100644
--- a/vendor/tokio/src/time/clock.rs
+++ b/vendor/tokio/src/time/clock.rs
@@ -29,26 +29,53 @@ cfg_not_test_util! {
 
 cfg_test_util! {
     use crate::time::{Duration, Instant};
-    use crate::loom::sync::{Arc, Mutex};
+    use crate::loom::sync::Mutex;
+    use crate::loom::sync::atomic::Ordering;
+    use std::sync::atomic::AtomicBool as StdAtomicBool;
 
     cfg_rt! {
-        fn clock() -> Option<Clock> {
-            crate::runtime::context::clock()
+        #[track_caller]
+        fn with_clock<R>(f: impl FnOnce(Option<&Clock>) -> Result<R, &'static str>) -> R {
+            use crate::runtime::Handle;
+
+            let res = match Handle::try_current() {
+                Ok(handle) => f(Some(handle.inner.driver().clock())),
+                Err(ref e) if e.is_missing_context() => f(None),
+                Err(_) => panic!("{}", crate::util::error::THREAD_LOCAL_DESTROYED_ERROR),
+            };
+
+            match res {
+                Ok(ret) => ret,
+                Err(msg) => panic!("{}", msg),
+            }
         }
     }
 
     cfg_not_rt! {
-        fn clock() -> Option<Clock> {
-            None
+        #[track_caller]
+        fn with_clock<R>(f: impl FnOnce(Option<&Clock>) -> Result<R, &'static str>) -> R {
+            match f(None) {
+                Ok(ret) => ret,
+                Err(msg) => panic!("{}", msg),
+            }
         }
     }
 
     /// A handle to a source of time.
-    #[derive(Debug, Clone)]
+    #[derive(Debug)]
     pub(crate) struct Clock {
-        inner: Arc<Mutex<Inner>>,
+        inner: Mutex<Inner>,
     }
 
+    // Used to track if the clock was ever paused. This is an optimization to
+    // avoid touching the mutex if `test-util` was accidentally enabled in
+    // release mode.
+    //
+    // A static is used so we can avoid accessing the thread-local as well. The
+    // `std` AtomicBool is used directly because loom does not support static
+    // atomics.
+    static DID_PAUSE_CLOCK: StdAtomicBool = StdAtomicBool::new(false);
+
     #[derive(Debug)]
     struct Inner {
         /// True if the ability to pause time is enabled.
@@ -57,22 +84,34 @@ cfg_test_util! {
         /// Instant to use as the clock's base instant.
         base: std::time::Instant,
 
-        /// Instant at which the clock was last unfrozen
+        /// Instant at which the clock was last unfrozen.
         unfrozen: Option<std::time::Instant>,
+
+        /// Number of `inhibit_auto_advance` calls still in effect.
+        auto_advance_inhibit_count: usize,
     }
 
-    /// Pause time
+    /// Pauses time.
     ///
     /// The current value of `Instant::now()` is saved and all subsequent calls
-    /// to `Instant::now()` until the timer wheel is checked again will return
-    /// the saved value. Once the timer wheel is checked, time will immediately
-    /// advance to the next registered `Sleep`. This is useful for running tests
-    /// that depend on time.
+    /// to `Instant::now()` will return the saved value. The saved value can be
+    /// changed by [`advance`] or by the time auto-advancing once the runtime
+    /// has no work to do. This only affects the `Instant` type in Tokio, and
+    /// the `Instant` in std continues to work as normal.
     ///
     /// Pausing time requires the `current_thread` Tokio runtime. This is the
     /// default runtime used by `#[tokio::test]`. The runtime can be initialized
     /// with time in a paused state using the `Builder::start_paused` method.
     ///
+    /// For cases where time is immediately paused, it is better to pause
+    /// the time using the `main` or `test` macro:
+    /// ```
+    /// #[tokio::main(flavor = "current_thread", start_paused = true)]
+    /// async fn main() {
+    ///    println!("Hello world");
+    /// }
+    /// ```
+    ///
     /// # Panics
     ///
     /// Panics if time is already frozen or if called from outside of a
@@ -86,12 +125,18 @@ cfg_test_util! {
     /// current time when awaited.
     ///
     /// [`Sleep`]: crate::time::Sleep
+    /// [`advance`]: crate::time::advance
+    #[track_caller]
     pub fn pause() {
-        let clock = clock().expect("time cannot be frozen from outside the Tokio runtime");
-        clock.pause();
+        with_clock(|maybe_clock| {
+            match maybe_clock {
+                Some(clock) => clock.pause(),
+                None => Err("time cannot be frozen from outside the Tokio runtime"),
+            }
+        })
     }
 
-    /// Resume time
+    /// Resumes time.
     ///
     /// Clears the saved `Instant::now()` value. Subsequent calls to
     /// `Instant::now()` will return the value returned by the system call.
@@ -100,22 +145,44 @@ cfg_test_util! {
     ///
     /// Panics if time is not frozen or if called from outside of the Tokio
     /// runtime.
+    #[track_caller]
     pub fn resume() {
-        let clock = clock().expect("time cannot be frozen from outside the Tokio runtime");
-        let mut inner = clock.inner.lock();
+        with_clock(|maybe_clock| {
+            let clock = match maybe_clock {
+                Some(clock) => clock,
+                None => return Err("time cannot be frozen from outside the Tokio runtime"),
+            };
 
-        if inner.unfrozen.is_some() {
-            panic!("time is not frozen");
-        }
+            let mut inner = clock.inner.lock();
+
+            if inner.unfrozen.is_some() {
+                return Err("time is not frozen");
+            }
 
-        inner.unfrozen = Some(std::time::Instant::now());
+            inner.unfrozen = Some(std::time::Instant::now());
+            Ok(())
+        })
     }
 
-    /// Advance time
+    /// Advances time.
     ///
     /// Increments the saved `Instant::now()` value by `duration`. Subsequent
     /// calls to `Instant::now()` will return the result of the increment.
     ///
+    /// This function will make the current time jump forward by the given
+    /// duration in one jump. This means that all `sleep` calls with a deadline
+    /// before the new time will immediately complete "at the same time", and
+    /// the runtime is free to poll them in any order.  Additionally, this
+    /// method will not wait for the `sleep` calls it advanced past to complete.
+    /// If you want to do that, you should instead call [`sleep`] and rely on
+    /// the runtime's auto-advance feature.
+    ///
+    /// Note that calls to `sleep` are not guaranteed to complete the first time
+    /// they are polled after a call to `advance`. For example, this can happen
+    /// if the runtime has not yet touched the timer driver after the call to
+    /// `advance`. However if they don't, the runtime will poll the task again
+    /// shortly.
+    ///
     /// # Panics
     ///
     /// Panics if time is not frozen or if called from outside of the Tokio
@@ -126,70 +193,107 @@ cfg_test_util! {
     /// If the time is paused and there is no work to do, the runtime advances
     /// time to the next timer. See [`pause`](pause#auto-advance) for more
     /// details.
+    ///
+    /// [`sleep`]: fn@crate::time::sleep
     pub async fn advance(duration: Duration) {
-        let clock = clock().expect("time cannot be frozen from outside the Tokio runtime");
-        clock.advance(duration);
+        with_clock(|maybe_clock| {
+            let clock = match maybe_clock {
+                Some(clock) => clock,
+                None => return Err("time cannot be frozen from outside the Tokio runtime"),
+            };
+
+            clock.advance(duration)
+        });
 
         crate::task::yield_now().await;
     }
 
-    /// Return the current instant, factoring in frozen time.
+    /// Returns the current instant, factoring in frozen time.
     pub(crate) fn now() -> Instant {
-        if let Some(clock) = clock() {
-            clock.now()
-        } else {
-            Instant::from_std(std::time::Instant::now())
+        if !DID_PAUSE_CLOCK.load(Ordering::Acquire) {
+            return Instant::from_std(std::time::Instant::now());
         }
+
+        with_clock(|maybe_clock| {
+            Ok(if let Some(clock) = maybe_clock {
+                clock.now()
+            } else {
+                Instant::from_std(std::time::Instant::now())
+            })
+        })
     }
 
     impl Clock {
-        /// Return a new `Clock` instance that uses the current execution context's
+        /// Returns a new `Clock` instance that uses the current execution context's
         /// source of time.
         pub(crate) fn new(enable_pausing: bool, start_paused: bool) -> Clock {
             let now = std::time::Instant::now();
 
             let clock = Clock {
-                inner: Arc::new(Mutex::new(Inner {
+                inner: Mutex::new(Inner {
                     enable_pausing,
                     base: now,
                     unfrozen: Some(now),
-                })),
+                    auto_advance_inhibit_count: 0,
+                }),
             };
 
             if start_paused {
-                clock.pause();
+                if let Err(msg) = clock.pause() {
+                    panic!("{}", msg);
+                }
             }
 
             clock
         }
 
-        pub(crate) fn pause(&self) {
+        pub(crate) fn pause(&self) -> Result<(), &'static str> {
             let mut inner = self.inner.lock();
 
             if !inner.enable_pausing {
                 drop(inner); // avoid poisoning the lock
-                panic!("`time::pause()` requires the `current_thread` Tokio runtime. \
+                return Err("`time::pause()` requires the `current_thread` Tokio runtime. \
                         This is the default Runtime used by `#[tokio::test].");
             }
 
-            let elapsed = inner.unfrozen.as_ref().expect("time is already frozen").elapsed();
+            // Track that we paused the clock
+            DID_PAUSE_CLOCK.store(true, Ordering::Release);
+
+            let elapsed = match inner.unfrozen.as_ref() {
+                Some(v) => v.elapsed(),
+                None => return Err("time is already frozen")
+            };
             inner.base += elapsed;
             inner.unfrozen = None;
+
+            Ok(())
+        }
+
+        /// Temporarily stop auto-advancing the clock (see `tokio::time::pause`).
+        pub(crate) fn inhibit_auto_advance(&self) {
+            let mut inner = self.inner.lock();
+            inner.auto_advance_inhibit_count += 1;
+        }
+
+        pub(crate) fn allow_auto_advance(&self) {
+            let mut inner = self.inner.lock();
+            inner.auto_advance_inhibit_count -= 1;
         }
 
-        pub(crate) fn is_paused(&self) -> bool {
+        pub(crate) fn can_auto_advance(&self) -> bool {
             let inner = self.inner.lock();
-            inner.unfrozen.is_none()
+            inner.unfrozen.is_none() && inner.auto_advance_inhibit_count == 0
         }
 
-        pub(crate) fn advance(&self, duration: Duration) {
+        pub(crate) fn advance(&self, duration: Duration) -> Result<(), &'static str> {
             let mut inner = self.inner.lock();
 
             if inner.unfrozen.is_some() {
-                panic!("time is not frozen");
+                return Err("time is not frozen");
             }
 
             inner.base += duration;
+            Ok(())
         }
 
         pub(crate) fn now(&self) -> Instant {
diff --git a/vendor/tokio/src/time/driver/handle.rs b/vendor/tokio/src/time/driver/handle.rs
deleted file mode 100644
index 77b435873..000000000
--- a/vendor/tokio/src/time/driver/handle.rs
+++ /dev/null
@@ -1,88 +0,0 @@
-use crate::loom::sync::Arc;
-use crate::time::driver::ClockTime;
-use std::fmt;
-
-/// Handle to time driver instance.
-#[derive(Clone)]
-pub(crate) struct Handle {
-    time_source: ClockTime,
-    inner: Arc<super::Inner>,
-}
-
-impl Handle {
-    /// Creates a new timer `Handle` from a shared `Inner` timer state.
-    pub(super) fn new(inner: Arc<super::Inner>) -> Self {
-        let time_source = inner.state.lock().time_source.clone();
-        Handle { time_source, inner }
-    }
-
-    /// Returns the time source associated with this handle
-    pub(super) fn time_source(&self) -> &ClockTime {
-        &self.time_source
-    }
-
-    /// Access the driver's inner structure
-    pub(super) fn get(&self) -> &super::Inner {
-        &*self.inner
-    }
-
-    // Check whether the driver has been shutdown
-    pub(super) fn is_shutdown(&self) -> bool {
-        self.inner.is_shutdown()
-    }
-}
-
-cfg_rt! {
-    impl Handle {
-        /// Tries to get a handle to the current timer.
-        ///
-        /// # Panics
-        ///
-        /// This function panics if there is no current timer set.
-        ///
-        /// It can be triggered when `Builder::enable_time()` or
-        /// `Builder::enable_all()` are not included in the builder.
-        ///
-        /// It can also panic whenever a timer is created outside of a
-        /// Tokio runtime. That is why `rt.block_on(delay_for(...))` will panic,
-        /// since the function is executed outside of the runtime.
-        /// Whereas `rt.block_on(async {delay_for(...).await})` doesn't panic.
-        /// And this is because wrapping the function on an async makes it lazy,
-        /// and so gets executed inside the runtime successfully without
-        /// panicking.
-        pub(crate) fn current() -> Self {
-            crate::runtime::context::time_handle()
-                .expect("A Tokio 1.x context was found, but timers are disabled. Call `enable_time` on the runtime builder to enable timers.")
-        }
-    }
-}
-
-cfg_not_rt! {
-    impl Handle {
-        /// Tries to get a handle to the current timer.
-        ///
-        /// # Panics
-        ///
-        /// This function panics if there is no current timer set.
-        ///
-        /// It can be triggered when `Builder::enable_time()` or
-        /// `Builder::enable_all()` are not included in the builder.
-        ///
-        /// It can also panic whenever a timer is created outside of a Tokio
-        /// runtime. That is why `rt.block_on(delay_for(...))` will panic,
-        /// since the function is executed outside of the runtime.
-        /// Whereas `rt.block_on(async {delay_for(...).await})` doesn't
-        /// panic. And this is because wrapping the function on an async makes it
-        /// lazy, and so outside executed inside the runtime successfully without
-        /// panicking.
-        pub(crate) fn current() -> Self {
-            panic!("{}", crate::util::error::CONTEXT_MISSING_ERROR)
-        }
-    }
-}
-
-impl fmt::Debug for Handle {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "Handle")
-    }
-}
diff --git a/vendor/tokio/src/time/driver/sleep.rs b/vendor/tokio/src/time/driver/sleep.rs
deleted file mode 100644
index 40f745ad7..000000000
--- a/vendor/tokio/src/time/driver/sleep.rs
+++ /dev/null
@@ -1,257 +0,0 @@
-use crate::time::driver::{Handle, TimerEntry};
-use crate::time::{error::Error, Duration, Instant};
-
-use pin_project_lite::pin_project;
-use std::future::Future;
-use std::pin::Pin;
-use std::task::{self, Poll};
-
-/// Waits until `deadline` is reached.
-///
-/// No work is performed while awaiting on the sleep future to complete. `Sleep`
-/// operates at millisecond granularity and should not be used for tasks that
-/// require high-resolution timers.
-///
-/// # Cancellation
-///
-/// Canceling a sleep instance is done by dropping the returned future. No additional
-/// cleanup work is required.
-// Alias for old name in 0.x
-#[cfg_attr(docsrs, doc(alias = "delay_until"))]
-pub fn sleep_until(deadline: Instant) -> Sleep {
-    Sleep::new_timeout(deadline)
-}
-
-/// Waits until `duration` has elapsed.
-///
-/// Equivalent to `sleep_until(Instant::now() + duration)`. An asynchronous
-/// analog to `std::thread::sleep`.
-///
-/// No work is performed while awaiting on the sleep future to complete. `Sleep`
-/// operates at millisecond granularity and should not be used for tasks that
-/// require high-resolution timers.
-///
-/// To run something regularly on a schedule, see [`interval`].
-///
-/// The maximum duration for a sleep is 68719476734 milliseconds (approximately 2.2 years).
-///
-/// # Cancellation
-///
-/// Canceling a sleep instance is done by dropping the returned future. No additional
-/// cleanup work is required.
-///
-/// # Examples
-///
-/// Wait 100ms and print "100 ms have elapsed".
-///
-/// ```
-/// use tokio::time::{sleep, Duration};
-///
-/// #[tokio::main]
-/// async fn main() {
-///     sleep(Duration::from_millis(100)).await;
-///     println!("100 ms have elapsed");
-/// }
-/// ```
-///
-/// [`interval`]: crate::time::interval()
-// Alias for old name in 0.x
-#[cfg_attr(docsrs, doc(alias = "delay_for"))]
-#[cfg_attr(docsrs, doc(alias = "wait"))]
-pub fn sleep(duration: Duration) -> Sleep {
-    match Instant::now().checked_add(duration) {
-        Some(deadline) => sleep_until(deadline),
-        None => sleep_until(Instant::far_future()),
-    }
-}
-
-pin_project! {
-    /// Future returned by [`sleep`](sleep) and [`sleep_until`](sleep_until).
-    ///
-    /// This type does not implement the `Unpin` trait, which means that if you
-    /// use it with [`select!`] or by calling `poll`, you have to pin it first.
-    /// If you use it with `.await`, this does not apply.
-    ///
-    /// # Examples
-    ///
-    /// Wait 100ms and print "100 ms have elapsed".
-    ///
-    /// ```
-    /// use tokio::time::{sleep, Duration};
-    ///
-    /// #[tokio::main]
-    /// async fn main() {
-    ///     sleep(Duration::from_millis(100)).await;
-    ///     println!("100 ms have elapsed");
-    /// }
-    /// ```
-    ///
-    /// Use with [`select!`]. Pinning the `Sleep` with [`tokio::pin!`] is
-    /// necessary when the same `Sleep` is selected on multiple times.
-    /// ```no_run
-    /// use tokio::time::{self, Duration, Instant};
-    ///
-    /// #[tokio::main]
-    /// async fn main() {
-    ///     let sleep = time::sleep(Duration::from_millis(10));
-    ///     tokio::pin!(sleep);
-    ///
-    ///     loop {
-    ///         tokio::select! {
-    ///             () = &mut sleep => {
-    ///                 println!("timer elapsed");
-    ///                 sleep.as_mut().reset(Instant::now() + Duration::from_millis(50));
-    ///             },
-    ///         }
-    ///     }
-    /// }
-    /// ```
-    /// Use in a struct with boxing. By pinning the `Sleep` with a `Box`, the
-    /// `HasSleep` struct implements `Unpin`, even though `Sleep` does not.
-    /// ```
-    /// use std::future::Future;
-    /// use std::pin::Pin;
-    /// use std::task::{Context, Poll};
-    /// use tokio::time::Sleep;
-    ///
-    /// struct HasSleep {
-    ///     sleep: Pin<Box<Sleep>>,
-    /// }
-    ///
-    /// impl Future for HasSleep {
-    ///     type Output = ();
-    ///
-    ///     fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<()> {
-    ///         self.sleep.as_mut().poll(cx)
-    ///     }
-    /// }
-    /// ```
-    /// Use in a struct with pin projection. This method avoids the `Box`, but
-    /// the `HasSleep` struct will not be `Unpin` as a consequence.
-    /// ```
-    /// use std::future::Future;
-    /// use std::pin::Pin;
-    /// use std::task::{Context, Poll};
-    /// use tokio::time::Sleep;
-    /// use pin_project_lite::pin_project;
-    ///
-    /// pin_project! {
-    ///     struct HasSleep {
-    ///         #[pin]
-    ///         sleep: Sleep,
-    ///     }
-    /// }
-    ///
-    /// impl Future for HasSleep {
-    ///     type Output = ();
-    ///
-    ///     fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<()> {
-    ///         self.project().sleep.poll(cx)
-    ///     }
-    /// }
-    /// ```
-    ///
-    /// [`select!`]: ../macro.select.html
-    /// [`tokio::pin!`]: ../macro.pin.html
-    // Alias for old name in 0.2
-    #[cfg_attr(docsrs, doc(alias = "Delay"))]
-    #[derive(Debug)]
-    #[must_use = "futures do nothing unless you `.await` or poll them"]
-    pub struct Sleep {
-        deadline: Instant,
-
-        // The link between the `Sleep` instance and the timer that drives it.
-        #[pin]
-        entry: TimerEntry,
-    }
-}
-
-impl Sleep {
-    pub(crate) fn new_timeout(deadline: Instant) -> Sleep {
-        let handle = Handle::current();
-        let entry = TimerEntry::new(&handle, deadline);
-
-        Sleep { deadline, entry }
-    }
-
-    pub(crate) fn far_future() -> Sleep {
-        Self::new_timeout(Instant::far_future())
-    }
-
-    /// Returns the instant at which the future will complete.
-    pub fn deadline(&self) -> Instant {
-        self.deadline
-    }
-
-    /// Returns `true` if `Sleep` has elapsed.
-    ///
-    /// A `Sleep` instance is elapsed when the requested duration has elapsed.
-    pub fn is_elapsed(&self) -> bool {
-        self.entry.is_elapsed()
-    }
-
-    /// Resets the `Sleep` instance to a new deadline.
-    ///
-    /// Calling this function allows changing the instant at which the `Sleep`
-    /// future completes without having to create new associated state.
-    ///
-    /// This function can be called both before and after the future has
-    /// completed.
-    ///
-    /// To call this method, you will usually combine the call with
-    /// [`Pin::as_mut`], which lets you call the method without consuming the
-    /// `Sleep` itself.
-    ///
-    /// # Example
-    ///
-    /// ```
-    /// use tokio::time::{Duration, Instant};
-    ///
-    /// # #[tokio::main(flavor = "current_thread")]
-    /// # async fn main() {
-    /// let sleep = tokio::time::sleep(Duration::from_millis(10));
-    /// tokio::pin!(sleep);
-    ///
-    /// sleep.as_mut().reset(Instant::now() + Duration::from_millis(20));
-    /// # }
-    /// ```
-    ///
-    /// [`Pin::as_mut`]: fn@std::pin::Pin::as_mut
-    pub fn reset(self: Pin<&mut Self>, deadline: Instant) {
-        let me = self.project();
-        me.entry.reset(deadline);
-        *me.deadline = deadline;
-    }
-
-    fn poll_elapsed(self: Pin<&mut Self>, cx: &mut task::Context<'_>) -> Poll<Result<(), Error>> {
-        let me = self.project();
-
-        // Keep track of task budget
-        let coop = ready!(crate::coop::poll_proceed(cx));
-
-        me.entry.poll_elapsed(cx).map(move |r| {
-            coop.made_progress();
-            r
-        })
-    }
-}
-
-impl Future for Sleep {
-    type Output = ();
-
-    fn poll(mut self: Pin<&mut Self>, cx: &mut task::Context<'_>) -> Poll<Self::Output> {
-        // `poll_elapsed` can return an error in two cases:
-        //
-        // - AtCapacity: this is a pathological case where far too many
-        //   sleep instances have been scheduled.
-        // - Shutdown: No timer has been setup, which is a mis-use error.
-        //
-        // Both cases are extremely rare, and pretty accurately fit into
-        // "logic errors", so we just panic in this case. A user couldn't
-        // really do much better if we passed the error onwards.
-        match ready!(self.as_mut().poll_elapsed(cx)) {
-            Ok(()) => Poll::Ready(()),
-            Err(e) => panic!("timer error: {}", e),
-        }
-    }
-}
diff --git a/vendor/tokio/src/time/driver/wheel/stack.rs b/vendor/tokio/src/time/driver/wheel/stack.rs
deleted file mode 100644
index e7ed137f5..000000000
--- a/vendor/tokio/src/time/driver/wheel/stack.rs
+++ /dev/null
@@ -1,112 +0,0 @@
-use super::{Item, OwnedItem};
-use crate::time::driver::Entry;
-
-use std::ptr;
-
-/// A doubly linked stack
-#[derive(Debug)]
-pub(crate) struct Stack {
-    head: Option<OwnedItem>,
-}
-
-impl Default for Stack {
-    fn default() -> Stack {
-        Stack { head: None }
-    }
-}
-
-impl Stack {
-    pub(crate) fn is_empty(&self) -> bool {
-        self.head.is_none()
-    }
-
-    pub(crate) fn push(&mut self, entry: OwnedItem) {
-        // Get a pointer to the entry to for the prev link
-        let ptr: *const Entry = &*entry as *const _;
-
-        // Remove the old head entry
-        let old = self.head.take();
-
-        unsafe {
-            // Ensure the entry is not already in a stack.
-            debug_assert!((*entry.next_stack.get()).is_none());
-            debug_assert!((*entry.prev_stack.get()).is_null());
-
-            if let Some(ref entry) = old.as_ref() {
-                debug_assert!({
-                    // The head is not already set to the entry
-                    ptr != &***entry as *const _
-                });
-
-                // Set the previous link on the old head
-                *entry.prev_stack.get() = ptr;
-            }
-
-            // Set this entry's next pointer
-            *entry.next_stack.get() = old;
-        }
-
-        // Update the head pointer
-        self.head = Some(entry);
-    }
-
-    /// Pops an item from the stack
-    pub(crate) fn pop(&mut self) -> Option<OwnedItem> {
-        let entry = self.head.take();
-
-        unsafe {
-            if let Some(entry) = entry.as_ref() {
-                self.head = (*entry.next_stack.get()).take();
-
-                if let Some(entry) = self.head.as_ref() {
-                    *entry.prev_stack.get() = ptr::null();
-                }
-
-                *entry.prev_stack.get() = ptr::null();
-            }
-        }
-
-        entry
-    }
-
-    pub(crate) fn remove(&mut self, entry: &Item) {
-        unsafe {
-            // Ensure that the entry is in fact contained by the stack
-            debug_assert!({
-                // This walks the full linked list even if an entry is found.
-                let mut next = self.head.as_ref();
-                let mut contains = false;
-
-                while let Some(n) = next {
-                    if entry as *const _ == &**n as *const _ {
-                        debug_assert!(!contains);
-                        contains = true;
-                    }
-
-                    next = (*n.next_stack.get()).as_ref();
-                }
-
-                contains
-            });
-
-            // Unlink `entry` from the next node
-            let next = (*entry.next_stack.get()).take();
-
-            if let Some(next) = next.as_ref() {
-                (*next.prev_stack.get()) = *entry.prev_stack.get();
-            }
-
-            // Unlink `entry` from the prev node
-
-            if let Some(prev) = (*entry.prev_stack.get()).as_ref() {
-                *prev.next_stack.get() = next;
-            } else {
-                // It is the head
-                self.head = next;
-            }
-
-            // Unset the prev pointer
-            *entry.prev_stack.get() = ptr::null();
-        }
-    }
-}
diff --git a/vendor/tokio/src/time/error.rs b/vendor/tokio/src/time/error.rs
index 8674febe9..71344d434 100644
--- a/vendor/tokio/src/time/error.rs
+++ b/vendor/tokio/src/time/error.rs
@@ -40,8 +40,11 @@ impl From<Kind> for Error {
     }
 }
 
-/// Error returned by `Timeout`.
-#[derive(Debug, PartialEq)]
+/// Errors returned by `Timeout`.
+///
+/// This error is returned when a timeout expires before the function was able
+/// to finish.
+#[derive(Debug, PartialEq, Eq)]
 pub struct Elapsed(());
 
 #[derive(Debug)]
@@ -72,7 +75,7 @@ impl Error {
         matches!(self.0, Kind::AtCapacity)
     }
 
-    /// Create an error representing a misconfigured timer.
+    /// Creates an error representing a misconfigured timer.
     pub fn invalid() -> Error {
         Error(Invalid)
     }
diff --git a/vendor/tokio/src/time/instant.rs b/vendor/tokio/src/time/instant.rs
index f7cf12d4a..14cf6e567 100644
--- a/vendor/tokio/src/time/instant.rs
+++ b/vendor/tokio/src/time/instant.rs
@@ -67,13 +67,10 @@ impl Instant {
         self.std
     }
 
-    /// Returns the amount of time elapsed from another instant to this one.
-    ///
-    /// # Panics
-    ///
-    /// This function will panic if `earlier` is later than `self`.
+    /// Returns the amount of time elapsed from another instant to this one, or
+    /// zero duration if that instant is later than this one.
     pub fn duration_since(&self, earlier: Instant) -> Duration {
-        self.std.duration_since(earlier.std)
+        self.std.saturating_duration_since(earlier.std)
     }
 
     /// Returns the amount of time elapsed from another instant to this one, or
@@ -118,13 +115,8 @@ impl Instant {
         self.std.saturating_duration_since(earlier.std)
     }
 
-    /// Returns the amount of time elapsed since this instant was created.
-    ///
-    /// # Panics
-    ///
-    /// This function may panic if the current time is earlier than this
-    /// instant, which is something that can happen if an `Instant` is
-    /// produced synthetically.
+    /// Returns the amount of time elapsed since this instant was created,
+    /// or zero duration if that this instant is in the future.
     ///
     /// # Examples
     ///
@@ -140,7 +132,7 @@ impl Instant {
     /// }
     /// ```
     pub fn elapsed(&self) -> Duration {
-        Instant::now() - *self
+        Instant::now().saturating_duration_since(*self)
     }
 
     /// Returns `Some(t)` where `t` is the time `self + duration` if `t` can be
@@ -188,7 +180,7 @@ impl ops::Sub for Instant {
     type Output = Duration;
 
     fn sub(self, rhs: Instant) -> Duration {
-        self.std - rhs.std
+        self.std.saturating_duration_since(rhs.std)
     }
 }
 
@@ -196,7 +188,7 @@ impl ops::Sub<Duration> for Instant {
     type Output = Instant;
 
     fn sub(self, rhs: Duration) -> Instant {
-        Instant::from_std(self.std - rhs)
+        Instant::from_std(std::time::Instant::sub(self.std, rhs))
     }
 }
 
diff --git a/vendor/tokio/src/time/interval.rs b/vendor/tokio/src/time/interval.rs
index a63e47b6e..2e153fdbe 100644
--- a/vendor/tokio/src/time/interval.rs
+++ b/vendor/tokio/src/time/interval.rs
@@ -1,9 +1,11 @@
 use crate::future::poll_fn;
 use crate::time::{sleep_until, Duration, Instant, Sleep};
+use crate::util::trace;
 
+use std::future::Future;
+use std::panic::Location;
 use std::pin::Pin;
 use std::task::{Context, Poll};
-use std::{convert::TryInto, future::Future};
 
 /// Creates new [`Interval`] that yields with interval of `period`. The first
 /// tick completes immediately. The default [`MissedTickBehavior`] is
@@ -68,10 +70,10 @@ use std::{convert::TryInto, future::Future};
 ///
 /// [`sleep`]: crate::time::sleep()
 /// [`.tick().await`]: Interval::tick
+#[track_caller]
 pub fn interval(period: Duration) -> Interval {
     assert!(period > Duration::new(0, 0), "`period` must be non-zero.");
-
-    interval_at(Instant::now(), period)
+    internal_interval_at(Instant::now(), period, trace::caller_location())
 }
 
 /// Creates new [`Interval`] that yields with interval of `period` with the
@@ -103,13 +105,44 @@ pub fn interval(period: Duration) -> Interval {
 ///     // approximately 70ms have elapsed.
 /// }
 /// ```
+#[track_caller]
 pub fn interval_at(start: Instant, period: Duration) -> Interval {
     assert!(period > Duration::new(0, 0), "`period` must be non-zero.");
+    internal_interval_at(start, period, trace::caller_location())
+}
+
+#[cfg_attr(not(all(tokio_unstable, feature = "tracing")), allow(unused_variables))]
+fn internal_interval_at(
+    start: Instant,
+    period: Duration,
+    location: Option<&'static Location<'static>>,
+) -> Interval {
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    let resource_span = {
+        let location = location.expect("should have location if tracing");
+
+        tracing::trace_span!(
+            "runtime.resource",
+            concrete_type = "Interval",
+            kind = "timer",
+            loc.file = location.file(),
+            loc.line = location.line(),
+            loc.col = location.column(),
+        )
+    };
+
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    let delay = resource_span.in_scope(|| Box::pin(sleep_until(start)));
+
+    #[cfg(not(all(tokio_unstable, feature = "tracing")))]
+    let delay = Box::pin(sleep_until(start));
 
     Interval {
-        delay: Box::pin(sleep_until(start)),
+        delay,
         period,
         missed_tick_behavior: Default::default(),
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        resource_span,
     }
 }
 
@@ -124,7 +157,7 @@ pub fn interval_at(start: Instant, period: Duration) -> Interval {
 ///
 /// #[tokio::main]
 /// async fn main() {
-///     // ticks every 2 seconds
+///     // ticks every 2 milliseconds
 ///     let mut interval = time::interval(Duration::from_millis(2));
 ///     for _ in 0..5 {
 ///         interval.tick().await;
@@ -147,7 +180,7 @@ pub fn interval_at(start: Instant, period: Duration) -> Interval {
 /// milliseconds.
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum MissedTickBehavior {
-    /// Tick as fast as possible until caught up.
+    /// Ticks as fast as possible until caught up.
     ///
     /// When this strategy is used, [`Interval`] schedules ticks "normally" (the
     /// same as it would have if the ticks hadn't been delayed), which results
@@ -174,6 +207,9 @@ pub enum MissedTickBehavior {
     /// # async fn main() {
     /// let mut interval = interval(Duration::from_millis(50));
     ///
+    /// // First tick resolves immediately after creation
+    /// interval.tick().await;
+    ///
     /// task_that_takes_200_millis().await;
     /// // The `Interval` has missed a tick
     ///
@@ -242,7 +278,7 @@ pub enum MissedTickBehavior {
     /// // 50ms after the call to `tick` up above. That is, in `tick`, when we
     /// // recognize that we missed a tick, we schedule the next tick to happen
     /// // 50ms (or whatever the `period` is) from right then, not from when
-    /// // were were *supposed* to tick
+    /// // were *supposed* to tick
     /// interval.tick().await;
     /// # }
     /// ```
@@ -252,7 +288,7 @@ pub enum MissedTickBehavior {
     /// [`tick`]: Interval::tick
     Delay,
 
-    /// Skip missed ticks and tick on the next multiple of `period` from
+    /// Skips missed ticks and tick on the next multiple of `period` from
     /// `start`.
     ///
     /// When this strategy is used, [`Interval`] schedules the next tick to fire
@@ -342,7 +378,7 @@ impl Default for MissedTickBehavior {
     }
 }
 
-/// Interval returned by [`interval`] and [`interval_at`]
+/// Interval returned by [`interval`] and [`interval_at`].
 ///
 /// This type allows you to wait on a sequence of instants with a certain
 /// duration between each instant. Unlike calling [`sleep`] in a loop, this lets
@@ -351,7 +387,7 @@ impl Default for MissedTickBehavior {
 /// An `Interval` can be turned into a `Stream` with [`IntervalStream`].
 ///
 /// [`IntervalStream`]: https://docs.rs/tokio-stream/latest/tokio_stream/wrappers/struct.IntervalStream.html
-/// [`sleep`]: crate::time::sleep
+/// [`sleep`]: crate::time::sleep()
 #[derive(Debug)]
 pub struct Interval {
     /// Future that completes the next time the `Interval` yields a value.
@@ -362,11 +398,19 @@ pub struct Interval {
 
     /// The strategy `Interval` should use when a tick is missed.
     missed_tick_behavior: MissedTickBehavior,
+
+    #[cfg(all(tokio_unstable, feature = "tracing"))]
+    resource_span: tracing::Span,
 }
 
 impl Interval {
     /// Completes when the next instant in the interval has been reached.
     ///
+    /// # Cancel safety
+    ///
+    /// This method is cancellation safe. If `tick` is used as the branch in a `tokio::select!` and
+    /// another branch completes first, then no tick has been consumed.
+    ///
     /// # Examples
     ///
     /// ```
@@ -379,6 +423,7 @@ impl Interval {
     ///     let mut interval = time::interval(Duration::from_millis(10));
     ///
     ///     interval.tick().await;
+    ///     // approximately 0ms have elapsed. The first tick completes immediately.
     ///     interval.tick().await;
     ///     interval.tick().await;
     ///
@@ -386,10 +431,23 @@ impl Interval {
     /// }
     /// ```
     pub async fn tick(&mut self) -> Instant {
-        poll_fn(|cx| self.poll_tick(cx)).await
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let resource_span = self.resource_span.clone();
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let instant = trace::async_op(
+            || poll_fn(|cx| self.poll_tick(cx)),
+            resource_span,
+            "Interval::tick",
+            "poll_tick",
+            false,
+        );
+        #[cfg(not(all(tokio_unstable, feature = "tracing")))]
+        let instant = poll_fn(|cx| self.poll_tick(cx));
+
+        instant.await
     }
 
-    /// Poll for the next instant in the interval to be reached.
+    /// Polls for the next instant in the interval to be reached.
     ///
     /// This method can return the following values:
     ///
@@ -424,12 +482,45 @@ impl Interval {
             timeout + self.period
         };
 
-        self.delay.as_mut().reset(next);
+        // When we arrive here, the internal delay returned `Poll::Ready`.
+        // Reset the delay but do not register it. It should be registered with
+        // the next call to [`poll_tick`].
+        self.delay.as_mut().reset_without_reregister(next);
 
         // Return the time when we were scheduled to tick
         Poll::Ready(timeout)
     }
 
+    /// Resets the interval to complete one period after the current time.
+    ///
+    /// This method ignores [`MissedTickBehavior`] strategy.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::time;
+    ///
+    /// use std::time::Duration;
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let mut interval = time::interval(Duration::from_millis(100));
+    ///
+    ///     interval.tick().await;
+    ///
+    ///     time::sleep(Duration::from_millis(50)).await;
+    ///     interval.reset();
+    ///
+    ///     interval.tick().await;
+    ///     interval.tick().await;
+    ///
+    ///     // approximately 250ms have elapsed.
+    /// }
+    /// ```
+    pub fn reset(&mut self) {
+        self.delay.as_mut().reset(Instant::now() + self.period);
+    }
+
     /// Returns the [`MissedTickBehavior`] strategy currently being used.
     pub fn missed_tick_behavior(&self) -> MissedTickBehavior {
         self.missed_tick_behavior
diff --git a/vendor/tokio/src/time/mod.rs b/vendor/tokio/src/time/mod.rs
index 281990ef9..a1f27b839 100644
--- a/vendor/tokio/src/time/mod.rs
+++ b/vendor/tokio/src/time/mod.rs
@@ -82,17 +82,13 @@
 //! ```
 //!
 //! [`interval`]: crate::time::interval()
+//! [`sleep`]: sleep()
 
 mod clock;
 pub(crate) use self::clock::Clock;
 #[cfg(feature = "test-util")]
 pub use clock::{advance, pause, resume};
 
-pub(crate) mod driver;
-
-#[doc(inline)]
-pub use driver::sleep::{sleep, sleep_until, Sleep};
-
 pub mod error;
 
 mod instant;
@@ -101,14 +97,13 @@ pub use self::instant::Instant;
 mod interval;
 pub use interval::{interval, interval_at, Interval, MissedTickBehavior};
 
+mod sleep;
+pub use sleep::{sleep, sleep_until, Sleep};
+
 mod timeout;
 #[doc(inline)]
 pub use timeout::{timeout, timeout_at, Timeout};
 
-#[cfg(test)]
-#[cfg(not(loom))]
-mod tests;
-
 // Re-export for convenience
 #[doc(no_inline)]
 pub use std::time::Duration;
diff --git a/vendor/tokio/src/time/sleep.rs b/vendor/tokio/src/time/sleep.rs
new file mode 100644
index 000000000..6c9b33793
--- /dev/null
+++ b/vendor/tokio/src/time/sleep.rs
@@ -0,0 +1,452 @@
+use crate::runtime::time::TimerEntry;
+use crate::time::{error::Error, Duration, Instant};
+use crate::util::trace;
+
+use pin_project_lite::pin_project;
+use std::future::Future;
+use std::panic::Location;
+use std::pin::Pin;
+use std::task::{self, Poll};
+
+/// Waits until `deadline` is reached.
+///
+/// No work is performed while awaiting on the sleep future to complete. `Sleep`
+/// operates at millisecond granularity and should not be used for tasks that
+/// require high-resolution timers.
+///
+/// To run something regularly on a schedule, see [`interval`].
+///
+/// # Cancellation
+///
+/// Canceling a sleep instance is done by dropping the returned future. No additional
+/// cleanup work is required.
+///
+/// # Examples
+///
+/// Wait 100ms and print "100 ms have elapsed".
+///
+/// ```
+/// use tokio::time::{sleep_until, Instant, Duration};
+///
+/// #[tokio::main]
+/// async fn main() {
+///     sleep_until(Instant::now() + Duration::from_millis(100)).await;
+///     println!("100 ms have elapsed");
+/// }
+/// ```
+///
+/// See the documentation for the [`Sleep`] type for more examples.
+///
+/// # Panics
+///
+/// This function panics if there is no current timer set.
+///
+/// It can be triggered when [`Builder::enable_time`] or
+/// [`Builder::enable_all`] are not included in the builder.
+///
+/// It can also panic whenever a timer is created outside of a
+/// Tokio runtime. That is why `rt.block_on(sleep(...))` will panic,
+/// since the function is executed outside of the runtime.
+/// Whereas `rt.block_on(async {sleep(...).await})` doesn't panic.
+/// And this is because wrapping the function on an async makes it lazy,
+/// and so gets executed inside the runtime successfully without
+/// panicking.
+///
+/// [`Sleep`]: struct@crate::time::Sleep
+/// [`interval`]: crate::time::interval()
+/// [`Builder::enable_time`]: crate::runtime::Builder::enable_time
+/// [`Builder::enable_all`]: crate::runtime::Builder::enable_all
+// Alias for old name in 0.x
+#[cfg_attr(docsrs, doc(alias = "delay_until"))]
+#[track_caller]
+pub fn sleep_until(deadline: Instant) -> Sleep {
+    return Sleep::new_timeout(deadline, trace::caller_location());
+}
+
+/// Waits until `duration` has elapsed.
+///
+/// Equivalent to `sleep_until(Instant::now() + duration)`. An asynchronous
+/// analog to `std::thread::sleep`.
+///
+/// No work is performed while awaiting on the sleep future to complete. `Sleep`
+/// operates at millisecond granularity and should not be used for tasks that
+/// require high-resolution timers. The implementation is platform specific,
+/// and some platforms (specifically Windows) will provide timers with a
+/// larger resolution than 1 ms.
+///
+/// To run something regularly on a schedule, see [`interval`].
+///
+/// The maximum duration for a sleep is 68719476734 milliseconds (approximately 2.2 years).
+///
+/// # Cancellation
+///
+/// Canceling a sleep instance is done by dropping the returned future. No additional
+/// cleanup work is required.
+///
+/// # Examples
+///
+/// Wait 100ms and print "100 ms have elapsed".
+///
+/// ```
+/// use tokio::time::{sleep, Duration};
+///
+/// #[tokio::main]
+/// async fn main() {
+///     sleep(Duration::from_millis(100)).await;
+///     println!("100 ms have elapsed");
+/// }
+/// ```
+///
+/// See the documentation for the [`Sleep`] type for more examples.
+///
+/// # Panics
+///
+/// This function panics if there is no current timer set.
+///
+/// It can be triggered when [`Builder::enable_time`] or
+/// [`Builder::enable_all`] are not included in the builder.
+///
+/// It can also panic whenever a timer is created outside of a
+/// Tokio runtime. That is why `rt.block_on(sleep(...))` will panic,
+/// since the function is executed outside of the runtime.
+/// Whereas `rt.block_on(async {sleep(...).await})` doesn't panic.
+/// And this is because wrapping the function on an async makes it lazy,
+/// and so gets executed inside the runtime successfully without
+/// panicking.
+///
+/// [`Sleep`]: struct@crate::time::Sleep
+/// [`interval`]: crate::time::interval()
+/// [`Builder::enable_time`]: crate::runtime::Builder::enable_time
+/// [`Builder::enable_all`]: crate::runtime::Builder::enable_all
+// Alias for old name in 0.x
+#[cfg_attr(docsrs, doc(alias = "delay_for"))]
+#[cfg_attr(docsrs, doc(alias = "wait"))]
+#[track_caller]
+pub fn sleep(duration: Duration) -> Sleep {
+    let location = trace::caller_location();
+
+    match Instant::now().checked_add(duration) {
+        Some(deadline) => Sleep::new_timeout(deadline, location),
+        None => Sleep::new_timeout(Instant::far_future(), location),
+    }
+}
+
+pin_project! {
+    /// Future returned by [`sleep`](sleep) and [`sleep_until`](sleep_until).
+    ///
+    /// This type does not implement the `Unpin` trait, which means that if you
+    /// use it with [`select!`] or by calling `poll`, you have to pin it first.
+    /// If you use it with `.await`, this does not apply.
+    ///
+    /// # Examples
+    ///
+    /// Wait 100ms and print "100 ms have elapsed".
+    ///
+    /// ```
+    /// use tokio::time::{sleep, Duration};
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     sleep(Duration::from_millis(100)).await;
+    ///     println!("100 ms have elapsed");
+    /// }
+    /// ```
+    ///
+    /// Use with [`select!`]. Pinning the `Sleep` with [`tokio::pin!`] is
+    /// necessary when the same `Sleep` is selected on multiple times.
+    /// ```no_run
+    /// use tokio::time::{self, Duration, Instant};
+    ///
+    /// #[tokio::main]
+    /// async fn main() {
+    ///     let sleep = time::sleep(Duration::from_millis(10));
+    ///     tokio::pin!(sleep);
+    ///
+    ///     loop {
+    ///         tokio::select! {
+    ///             () = &mut sleep => {
+    ///                 println!("timer elapsed");
+    ///                 sleep.as_mut().reset(Instant::now() + Duration::from_millis(50));
+    ///             },
+    ///         }
+    ///     }
+    /// }
+    /// ```
+    /// Use in a struct with boxing. By pinning the `Sleep` with a `Box`, the
+    /// `HasSleep` struct implements `Unpin`, even though `Sleep` does not.
+    /// ```
+    /// use std::future::Future;
+    /// use std::pin::Pin;
+    /// use std::task::{Context, Poll};
+    /// use tokio::time::Sleep;
+    ///
+    /// struct HasSleep {
+    ///     sleep: Pin<Box<Sleep>>,
+    /// }
+    ///
+    /// impl Future for HasSleep {
+    ///     type Output = ();
+    ///
+    ///     fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<()> {
+    ///         self.sleep.as_mut().poll(cx)
+    ///     }
+    /// }
+    /// ```
+    /// Use in a struct with pin projection. This method avoids the `Box`, but
+    /// the `HasSleep` struct will not be `Unpin` as a consequence.
+    /// ```
+    /// use std::future::Future;
+    /// use std::pin::Pin;
+    /// use std::task::{Context, Poll};
+    /// use tokio::time::Sleep;
+    /// use pin_project_lite::pin_project;
+    ///
+    /// pin_project! {
+    ///     struct HasSleep {
+    ///         #[pin]
+    ///         sleep: Sleep,
+    ///     }
+    /// }
+    ///
+    /// impl Future for HasSleep {
+    ///     type Output = ();
+    ///
+    ///     fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<()> {
+    ///         self.project().sleep.poll(cx)
+    ///     }
+    /// }
+    /// ```
+    ///
+    /// [`select!`]: ../macro.select.html
+    /// [`tokio::pin!`]: ../macro.pin.html
+    // Alias for old name in 0.2
+    #[cfg_attr(docsrs, doc(alias = "Delay"))]
+    #[derive(Debug)]
+    #[must_use = "futures do nothing unless you `.await` or poll them"]
+    pub struct Sleep {
+        inner: Inner,
+
+        // The link between the `Sleep` instance and the timer that drives it.
+        #[pin]
+        entry: TimerEntry,
+    }
+}
+
+cfg_trace! {
+    #[derive(Debug)]
+    struct Inner {
+        ctx: trace::AsyncOpTracingCtx,
+    }
+}
+
+cfg_not_trace! {
+    #[derive(Debug)]
+    struct Inner {
+    }
+}
+
+impl Sleep {
+    #[cfg_attr(not(all(tokio_unstable, feature = "tracing")), allow(unused_variables))]
+    #[track_caller]
+    pub(crate) fn new_timeout(
+        deadline: Instant,
+        location: Option<&'static Location<'static>>,
+    ) -> Sleep {
+        use crate::runtime::scheduler;
+
+        let handle = scheduler::Handle::current();
+        let entry = TimerEntry::new(&handle, deadline);
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let inner = {
+            let clock = handle.driver().clock();
+            let handle = &handle.driver().time();
+            let time_source = handle.time_source();
+            let deadline_tick = time_source.deadline_to_tick(deadline);
+            let duration = deadline_tick.saturating_sub(time_source.now(clock));
+
+            let location = location.expect("should have location if tracing");
+            let resource_span = tracing::trace_span!(
+                "runtime.resource",
+                concrete_type = "Sleep",
+                kind = "timer",
+                loc.file = location.file(),
+                loc.line = location.line(),
+                loc.col = location.column(),
+            );
+
+            let async_op_span = resource_span.in_scope(|| {
+                tracing::trace!(
+                    target: "runtime::resource::state_update",
+                    duration = duration,
+                    duration.unit = "ms",
+                    duration.op = "override",
+                );
+
+                tracing::trace_span!("runtime.resource.async_op", source = "Sleep::new_timeout")
+            });
+
+            let async_op_poll_span =
+                async_op_span.in_scope(|| tracing::trace_span!("runtime.resource.async_op.poll"));
+
+            let ctx = trace::AsyncOpTracingCtx {
+                async_op_span,
+                async_op_poll_span,
+                resource_span,
+            };
+
+            Inner { ctx }
+        };
+
+        #[cfg(not(all(tokio_unstable, feature = "tracing")))]
+        let inner = Inner {};
+
+        Sleep { inner, entry }
+    }
+
+    pub(crate) fn far_future(location: Option<&'static Location<'static>>) -> Sleep {
+        Self::new_timeout(Instant::far_future(), location)
+    }
+
+    /// Returns the instant at which the future will complete.
+    pub fn deadline(&self) -> Instant {
+        self.entry.deadline()
+    }
+
+    /// Returns `true` if `Sleep` has elapsed.
+    ///
+    /// A `Sleep` instance is elapsed when the requested duration has elapsed.
+    pub fn is_elapsed(&self) -> bool {
+        self.entry.is_elapsed()
+    }
+
+    /// Resets the `Sleep` instance to a new deadline.
+    ///
+    /// Calling this function allows changing the instant at which the `Sleep`
+    /// future completes without having to create new associated state.
+    ///
+    /// This function can be called both before and after the future has
+    /// completed.
+    ///
+    /// To call this method, you will usually combine the call with
+    /// [`Pin::as_mut`], which lets you call the method without consuming the
+    /// `Sleep` itself.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use tokio::time::{Duration, Instant};
+    ///
+    /// # #[tokio::main(flavor = "current_thread")]
+    /// # async fn main() {
+    /// let sleep = tokio::time::sleep(Duration::from_millis(10));
+    /// tokio::pin!(sleep);
+    ///
+    /// sleep.as_mut().reset(Instant::now() + Duration::from_millis(20));
+    /// # }
+    /// ```
+    ///
+    /// See also the top-level examples.
+    ///
+    /// [`Pin::as_mut`]: fn@std::pin::Pin::as_mut
+    pub fn reset(self: Pin<&mut Self>, deadline: Instant) {
+        self.reset_inner(deadline)
+    }
+
+    /// Resets the `Sleep` instance to a new deadline without reregistering it
+    /// to be woken up.
+    ///
+    /// Calling this function allows changing the instant at which the `Sleep`
+    /// future completes without having to create new associated state and
+    /// without having it registered. This is required in e.g. the
+    /// [crate::time::Interval] where we want to reset the internal [Sleep]
+    /// without having it wake up the last task that polled it.
+    pub(crate) fn reset_without_reregister(self: Pin<&mut Self>, deadline: Instant) {
+        let mut me = self.project();
+        me.entry.as_mut().reset(deadline, false);
+    }
+
+    fn reset_inner(self: Pin<&mut Self>, deadline: Instant) {
+        let mut me = self.project();
+        me.entry.as_mut().reset(deadline, true);
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        {
+            let _resource_enter = me.inner.ctx.resource_span.enter();
+            me.inner.ctx.async_op_span =
+                tracing::trace_span!("runtime.resource.async_op", source = "Sleep::reset");
+            let _async_op_enter = me.inner.ctx.async_op_span.enter();
+
+            me.inner.ctx.async_op_poll_span =
+                tracing::trace_span!("runtime.resource.async_op.poll");
+
+            let duration = {
+                let clock = me.entry.clock();
+                let time_source = me.entry.driver().time_source();
+                let now = time_source.now(clock);
+                let deadline_tick = time_source.deadline_to_tick(deadline);
+                deadline_tick.saturating_sub(now)
+            };
+
+            tracing::trace!(
+                target: "runtime::resource::state_update",
+                duration = duration,
+                duration.unit = "ms",
+                duration.op = "override",
+            );
+        }
+    }
+
+    fn poll_elapsed(self: Pin<&mut Self>, cx: &mut task::Context<'_>) -> Poll<Result<(), Error>> {
+        let me = self.project();
+
+        ready!(crate::trace::trace_leaf(cx));
+
+        // Keep track of task budget
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let coop = ready!(trace_poll_op!(
+            "poll_elapsed",
+            crate::runtime::coop::poll_proceed(cx),
+        ));
+
+        #[cfg(any(not(tokio_unstable), not(feature = "tracing")))]
+        let coop = ready!(crate::runtime::coop::poll_proceed(cx));
+
+        let result = me.entry.poll_elapsed(cx).map(move |r| {
+            coop.made_progress();
+            r
+        });
+
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        return trace_poll_op!("poll_elapsed", result);
+
+        #[cfg(any(not(tokio_unstable), not(feature = "tracing")))]
+        return result;
+    }
+}
+
+impl Future for Sleep {
+    type Output = ();
+
+    // `poll_elapsed` can return an error in two cases:
+    //
+    // - AtCapacity: this is a pathological case where far too many
+    //   sleep instances have been scheduled.
+    // - Shutdown: No timer has been setup, which is a mis-use error.
+    //
+    // Both cases are extremely rare, and pretty accurately fit into
+    // "logic errors", so we just panic in this case. A user couldn't
+    // really do much better if we passed the error onwards.
+    fn poll(mut self: Pin<&mut Self>, cx: &mut task::Context<'_>) -> Poll<Self::Output> {
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let _res_span = self.inner.ctx.resource_span.clone().entered();
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let _ao_span = self.inner.ctx.async_op_span.clone().entered();
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        let _ao_poll_span = self.inner.ctx.async_op_poll_span.clone().entered();
+        match ready!(self.as_mut().poll_elapsed(cx)) {
+            Ok(()) => Poll::Ready(()),
+            Err(e) => panic!("timer error: {}", e),
+        }
+    }
+}
diff --git a/vendor/tokio/src/time/tests/mod.rs b/vendor/tokio/src/time/tests/mod.rs
deleted file mode 100644
index 35e1060ac..000000000
--- a/vendor/tokio/src/time/tests/mod.rs
+++ /dev/null
@@ -1,22 +0,0 @@
-mod test_sleep;
-
-use crate::time::{self, Instant};
-use std::time::Duration;
-
-fn assert_send<T: Send>() {}
-fn assert_sync<T: Sync>() {}
-
-#[test]
-fn registration_is_send_and_sync() {
-    use crate::time::Sleep;
-
-    assert_send::<Sleep>();
-    assert_sync::<Sleep>();
-}
-
-#[test]
-#[should_panic]
-fn sleep_is_eager() {
-    let when = Instant::now() + Duration::from_millis(100);
-    let _ = time::sleep_until(when);
-}
diff --git a/vendor/tokio/src/time/tests/test_sleep.rs b/vendor/tokio/src/time/tests/test_sleep.rs
deleted file mode 100644
index 77ca07e31..000000000
--- a/vendor/tokio/src/time/tests/test_sleep.rs
+++ /dev/null
@@ -1,443 +0,0 @@
-//use crate::time::driver::{Driver, Entry, Handle};
-
-/*
-macro_rules! poll {
-    ($e:expr) => {
-        $e.enter(|cx, e| e.poll_elapsed(cx))
-    };
-}
-
-#[test]
-fn frozen_utility_returns_correct_advanced_duration() {
-    let clock = Clock::new();
-    clock.pause();
-    let start = clock.now();
-
-    clock.advance(ms(10));
-    assert_eq!(clock.now() - start, ms(10));
-}
-
-#[test]
-fn immediate_sleep() {
-    let (mut driver, clock, handle) = setup();
-    let start = clock.now();
-
-    let when = clock.now();
-    let mut e = task::spawn(sleep_until(&handle, when));
-
-    assert_ready_ok!(poll!(e));
-
-    assert_ok!(driver.park_timeout(Duration::from_millis(1000)));
-
-    // The time has not advanced. The `turn` completed immediately.
-    assert_eq!(clock.now() - start, ms(1000));
-}
-
-#[test]
-fn delayed_sleep_level_0() {
-    let (mut driver, clock, handle) = setup();
-    let start = clock.now();
-
-    for &i in &[1, 10, 60] {
-        // Create a `Sleep` that elapses in the future
-        let mut e = task::spawn(sleep_until(&handle, start + ms(i)));
-
-        // The sleep instance has not elapsed.
-        assert_pending!(poll!(e));
-
-        assert_ok!(driver.park());
-        assert_eq!(clock.now() - start, ms(i));
-
-        assert_ready_ok!(poll!(e));
-    }
-}
-
-#[test]
-fn sub_ms_delayed_sleep() {
-    let (mut driver, clock, handle) = setup();
-
-    for _ in 0..5 {
-        let deadline = clock.now() + ms(1) + Duration::new(0, 1);
-
-        let mut e = task::spawn(sleep_until(&handle, deadline));
-
-        assert_pending!(poll!(e));
-
-        assert_ok!(driver.park());
-        assert_ready_ok!(poll!(e));
-
-        assert!(clock.now() >= deadline);
-
-        clock.advance(Duration::new(0, 1));
-    }
-}
-
-#[test]
-fn delayed_sleep_wrapping_level_0() {
-    let (mut driver, clock, handle) = setup();
-    let start = clock.now();
-
-    assert_ok!(driver.park_timeout(ms(5)));
-    assert_eq!(clock.now() - start, ms(5));
-
-    let mut e = task::spawn(sleep_until(&handle, clock.now() + ms(60)));
-
-    assert_pending!(poll!(e));
-
-    assert_ok!(driver.park());
-    assert_eq!(clock.now() - start, ms(64));
-    assert_pending!(poll!(e));
-
-    assert_ok!(driver.park());
-    assert_eq!(clock.now() - start, ms(65));
-
-    assert_ready_ok!(poll!(e));
-}
-
-#[test]
-fn timer_wrapping_with_higher_levels() {
-    let (mut driver, clock, handle) = setup();
-    let start = clock.now();
-
-    // Set sleep to hit level 1
-    let mut e1 = task::spawn(sleep_until(&handle, clock.now() + ms(64)));
-    assert_pending!(poll!(e1));
-
-    // Turn a bit
-    assert_ok!(driver.park_timeout(ms(5)));
-
-    // Set timeout such that it will hit level 0, but wrap
-    let mut e2 = task::spawn(sleep_until(&handle, clock.now() + ms(60)));
-    assert_pending!(poll!(e2));
-
-    // This should result in s1 firing
-    assert_ok!(driver.park());
-    assert_eq!(clock.now() - start, ms(64));
-
-    assert_ready_ok!(poll!(e1));
-    assert_pending!(poll!(e2));
-
-    assert_ok!(driver.park());
-    assert_eq!(clock.now() - start, ms(65));
-
-    assert_ready_ok!(poll!(e1));
-}
-
-#[test]
-fn sleep_with_deadline_in_past() {
-    let (mut driver, clock, handle) = setup();
-    let start = clock.now();
-
-    // Create `Sleep` that elapsed immediately.
-    let mut e = task::spawn(sleep_until(&handle, clock.now() - ms(100)));
-
-    // Even though the `Sleep` expires in the past, it is not ready yet
-    // because the timer must observe it.
-    assert_ready_ok!(poll!(e));
-
-    // Turn the timer, it runs for the elapsed time
-    assert_ok!(driver.park_timeout(ms(1000)));
-
-    // The time has not advanced. The `turn` completed immediately.
-    assert_eq!(clock.now() - start, ms(1000));
-}
-
-#[test]
-fn delayed_sleep_level_1() {
-    let (mut driver, clock, handle) = setup();
-    let start = clock.now();
-
-    // Create a `Sleep` that elapses in the future
-    let mut e = task::spawn(sleep_until(&handle, clock.now() + ms(234)));
-
-    // The sleep has not elapsed.
-    assert_pending!(poll!(e));
-
-    // Turn the timer, this will wake up to cascade the timer down.
-    assert_ok!(driver.park_timeout(ms(1000)));
-    assert_eq!(clock.now() - start, ms(192));
-
-    // The sleep has not elapsed.
-    assert_pending!(poll!(e));
-
-    // Turn the timer again
-    assert_ok!(driver.park_timeout(ms(1000)));
-    assert_eq!(clock.now() - start, ms(234));
-
-    // The sleep has elapsed.
-    assert_ready_ok!(poll!(e));
-
-    let (mut driver, clock, handle) = setup();
-    let start = clock.now();
-
-    // Create a `Sleep` that elapses in the future
-    let mut e = task::spawn(sleep_until(&handle, clock.now() + ms(234)));
-
-    // The sleep has not elapsed.
-    assert_pending!(poll!(e));
-
-    // Turn the timer with a smaller timeout than the cascade.
-    assert_ok!(driver.park_timeout(ms(100)));
-    assert_eq!(clock.now() - start, ms(100));
-
-    assert_pending!(poll!(e));
-
-    // Turn the timer, this will wake up to cascade the timer down.
-    assert_ok!(driver.park_timeout(ms(1000)));
-    assert_eq!(clock.now() - start, ms(192));
-
-    // The sleep has not elapsed.
-    assert_pending!(poll!(e));
-
-    // Turn the timer again
-    assert_ok!(driver.park_timeout(ms(1000)));
-    assert_eq!(clock.now() - start, ms(234));
-
-    // The sleep has elapsed.
-    assert_ready_ok!(poll!(e));
-}
-
-#[test]
-fn concurrently_set_two_timers_second_one_shorter() {
-    let (mut driver, clock, handle) = setup();
-    let start = clock.now();
-
-    let mut e1 = task::spawn(sleep_until(&handle, clock.now() + ms(500)));
-    let mut e2 = task::spawn(sleep_until(&handle, clock.now() + ms(200)));
-
-    // The sleep has not elapsed
-    assert_pending!(poll!(e1));
-    assert_pending!(poll!(e2));
-
-    // Sleep until a cascade
-    assert_ok!(driver.park());
-    assert_eq!(clock.now() - start, ms(192));
-
-    // Sleep until the second timer.
-    assert_ok!(driver.park());
-    assert_eq!(clock.now() - start, ms(200));
-
-    // The shorter sleep fires
-    assert_ready_ok!(poll!(e2));
-    assert_pending!(poll!(e1));
-
-    assert_ok!(driver.park());
-    assert_eq!(clock.now() - start, ms(448));
-
-    assert_pending!(poll!(e1));
-
-    // Turn again, this time the time will advance to the second sleep
-    assert_ok!(driver.park());
-    assert_eq!(clock.now() - start, ms(500));
-
-    assert_ready_ok!(poll!(e1));
-}
-
-#[test]
-fn short_sleep() {
-    let (mut driver, clock, handle) = setup();
-    let start = clock.now();
-
-    // Create a `Sleep` that elapses in the future
-    let mut e = task::spawn(sleep_until(&handle, clock.now() + ms(1)));
-
-    // The sleep has not elapsed.
-    assert_pending!(poll!(e));
-
-    // Turn the timer, but not enough time will go by.
-    assert_ok!(driver.park());
-
-    // The sleep has elapsed.
-    assert_ready_ok!(poll!(e));
-
-    // The time has advanced to the point of the sleep elapsing.
-    assert_eq!(clock.now() - start, ms(1));
-}
-
-#[test]
-fn sorta_long_sleep_until() {
-    const MIN_5: u64 = 5 * 60 * 1000;
-
-    let (mut driver, clock, handle) = setup();
-    let start = clock.now();
-
-    // Create a `Sleep` that elapses in the future
-    let mut e = task::spawn(sleep_until(&handle, clock.now() + ms(MIN_5)));
-
-    // The sleep has not elapsed.
-    assert_pending!(poll!(e));
-
-    let cascades = &[262_144, 262_144 + 9 * 4096, 262_144 + 9 * 4096 + 15 * 64];
-
-    for &elapsed in cascades {
-        assert_ok!(driver.park());
-        assert_eq!(clock.now() - start, ms(elapsed));
-
-        assert_pending!(poll!(e));
-    }
-
-    assert_ok!(driver.park());
-    assert_eq!(clock.now() - start, ms(MIN_5));
-
-    // The sleep has elapsed.
-    assert_ready_ok!(poll!(e));
-}
-
-#[test]
-fn very_long_sleep() {
-    const MO_5: u64 = 5 * 30 * 24 * 60 * 60 * 1000;
-
-    let (mut driver, clock, handle) = setup();
-    let start = clock.now();
-
-    // Create a `Sleep` that elapses in the future
-    let mut e = task::spawn(sleep_until(&handle, clock.now() + ms(MO_5)));
-
-    // The sleep has not elapsed.
-    assert_pending!(poll!(e));
-
-    let cascades = &[
-        12_884_901_888,
-        12_952_010_752,
-        12_959_875_072,
-        12_959_997_952,
-    ];
-
-    for &elapsed in cascades {
-        assert_ok!(driver.park());
-        assert_eq!(clock.now() - start, ms(elapsed));
-
-        assert_pending!(poll!(e));
-    }
-
-    // Turn the timer, but not enough time will go by.
-    assert_ok!(driver.park());
-
-    // The time has advanced to the point of the sleep elapsing.
-    assert_eq!(clock.now() - start, ms(MO_5));
-
-    // The sleep has elapsed.
-    assert_ready_ok!(poll!(e));
-}
-
-#[test]
-fn unpark_is_delayed() {
-    // A special park that will take much longer than the requested duration
-    struct MockPark(Clock);
-
-    struct MockUnpark;
-
-    impl Park for MockPark {
-        type Unpark = MockUnpark;
-        type Error = ();
-
-        fn unpark(&self) -> Self::Unpark {
-            MockUnpark
-        }
-
-        fn park(&mut self) -> Result<(), Self::Error> {
-            panic!("parking forever");
-        }
-
-        fn park_timeout(&mut self, duration: Duration) -> Result<(), Self::Error> {
-            assert_eq!(duration, ms(0));
-            self.0.advance(ms(436));
-            Ok(())
-        }
-
-        fn shutdown(&mut self) {}
-    }
-
-    impl Unpark for MockUnpark {
-        fn unpark(&self) {}
-    }
-
-    let clock = Clock::new();
-    clock.pause();
-    let start = clock.now();
-    let mut driver = Driver::new(MockPark(clock.clone()), clock.clone());
-    let handle = driver.handle();
-
-    let mut e1 = task::spawn(sleep_until(&handle, clock.now() + ms(100)));
-    let mut e2 = task::spawn(sleep_until(&handle, clock.now() + ms(101)));
-    let mut e3 = task::spawn(sleep_until(&handle, clock.now() + ms(200)));
-
-    assert_pending!(poll!(e1));
-    assert_pending!(poll!(e2));
-    assert_pending!(poll!(e3));
-
-    assert_ok!(driver.park());
-
-    assert_eq!(clock.now() - start, ms(500));
-
-    assert_ready_ok!(poll!(e1));
-    assert_ready_ok!(poll!(e2));
-    assert_ready_ok!(poll!(e3));
-}
-
-#[test]
-fn set_timeout_at_deadline_greater_than_max_timer() {
-    const YR_1: u64 = 365 * 24 * 60 * 60 * 1000;
-    const YR_5: u64 = 5 * YR_1;
-
-    let (mut driver, clock, handle) = setup();
-    let start = clock.now();
-
-    for _ in 0..5 {
-        assert_ok!(driver.park_timeout(ms(YR_1)));
-    }
-
-    let mut e = task::spawn(sleep_until(&handle, clock.now() + ms(1)));
-    assert_pending!(poll!(e));
-
-    assert_ok!(driver.park_timeout(ms(1000)));
-    assert_eq!(clock.now() - start, ms(YR_5) + ms(1));
-
-    assert_ready_ok!(poll!(e));
-}
-
-fn setup() -> (Driver<MockPark>, Clock, Handle) {
-    let clock = Clock::new();
-    clock.pause();
-    let driver = Driver::new(MockPark(clock.clone()), clock.clone());
-    let handle = driver.handle();
-
-    (driver, clock, handle)
-}
-
-fn sleep_until(handle: &Handle, when: Instant) -> Arc<Entry> {
-    Entry::new(&handle, when, ms(0))
-}
-
-struct MockPark(Clock);
-
-struct MockUnpark;
-
-impl Park for MockPark {
-    type Unpark = MockUnpark;
-    type Error = ();
-
-    fn unpark(&self) -> Self::Unpark {
-        MockUnpark
-    }
-
-    fn park(&mut self) -> Result<(), Self::Error> {
-        panic!("parking forever");
-    }
-
-    fn park_timeout(&mut self, duration: Duration) -> Result<(), Self::Error> {
-        self.0.advance(duration);
-        Ok(())
-    }
-
-    fn shutdown(&mut self) {}
-}
-
-impl Unpark for MockUnpark {
-    fn unpark(&self) {}
-}
-
-fn ms(n: u64) -> Duration {
-    Duration::from_millis(n)
-}
-*/
diff --git a/vendor/tokio/src/time/timeout.rs b/vendor/tokio/src/time/timeout.rs
index 61964ad24..52ab9891c 100644
--- a/vendor/tokio/src/time/timeout.rs
+++ b/vendor/tokio/src/time/timeout.rs
@@ -4,20 +4,39 @@
 //!
 //! [`Timeout`]: struct@Timeout
 
-use crate::time::{error::Elapsed, sleep_until, Duration, Instant, Sleep};
+use crate::{
+    runtime::coop,
+    time::{error::Elapsed, sleep_until, Duration, Instant, Sleep},
+    util::trace,
+};
 
 use pin_project_lite::pin_project;
 use std::future::Future;
 use std::pin::Pin;
 use std::task::{self, Poll};
 
-/// Require a `Future` to complete before the specified duration has elapsed.
+/// Requires a `Future` to complete before the specified duration has elapsed.
 ///
 /// If the future completes before the duration has elapsed, then the completed
 /// value is returned. Otherwise, an error is returned and the future is
 /// canceled.
 ///
-/// # Cancelation
+/// Note that the timeout is checked before polling the future, so if the future
+/// does not yield during execution then it is possible for the future to complete
+/// and exceed the timeout _without_ returning an error.
+///
+/// This function returns a future whose return type is [`Result`]`<T,`[`Elapsed`]`>`, where `T` is the
+/// return type of the provided future.
+///
+/// If the provided future completes immediately, then the future returned from
+/// this function is guaranteed to complete immediately with an [`Ok`] variant
+/// no matter the provided duration.
+///
+/// [`Ok`]: std::result::Result::Ok
+/// [`Result`]: std::result::Result
+/// [`Elapsed`]: crate::time::error::Elapsed
+///
+/// # Cancellation
 ///
 /// Cancelling a timeout is done by dropping the future. No additional cleanup
 /// or other work is required.
@@ -45,24 +64,56 @@ use std::task::{self, Poll};
 /// }
 /// # }
 /// ```
-pub fn timeout<T>(duration: Duration, future: T) -> Timeout<T>
+///
+/// # Panics
+///
+/// This function panics if there is no current timer set.
+///
+/// It can be triggered when [`Builder::enable_time`] or
+/// [`Builder::enable_all`] are not included in the builder.
+///
+/// It can also panic whenever a timer is created outside of a
+/// Tokio runtime. That is why `rt.block_on(sleep(...))` will panic,
+/// since the function is executed outside of the runtime.
+/// Whereas `rt.block_on(async {sleep(...).await})` doesn't panic.
+/// And this is because wrapping the function on an async makes it lazy,
+/// and so gets executed inside the runtime successfully without
+/// panicking.
+///
+/// [`Builder::enable_time`]: crate::runtime::Builder::enable_time
+/// [`Builder::enable_all`]: crate::runtime::Builder::enable_all
+#[track_caller]
+pub fn timeout<F>(duration: Duration, future: F) -> Timeout<F>
 where
-    T: Future,
+    F: Future,
 {
+    let location = trace::caller_location();
+
     let deadline = Instant::now().checked_add(duration);
     let delay = match deadline {
-        Some(deadline) => Sleep::new_timeout(deadline),
-        None => Sleep::far_future(),
+        Some(deadline) => Sleep::new_timeout(deadline, location),
+        None => Sleep::far_future(location),
     };
     Timeout::new_with_delay(future, delay)
 }
 
-/// Require a `Future` to complete before the specified instant in time.
+/// Requires a `Future` to complete before the specified instant in time.
 ///
 /// If the future completes before the instant is reached, then the completed
 /// value is returned. Otherwise, an error is returned.
 ///
-/// # Cancelation
+/// This function returns a future whose return type is [`Result`]`<T,`[`Elapsed`]`>`, where `T` is the
+/// return type of the provided future.
+///
+/// If the provided future completes immediately, then the future returned from
+/// this function is guaranteed to complete immediately with an [`Ok`] variant
+/// no matter the provided deadline.
+///
+/// [`Ok`]: std::result::Result::Ok
+/// [`Result`]: std::result::Result
+/// [`Elapsed`]: crate::time::error::Elapsed
+///
+/// # Cancellation
 ///
 /// Cancelling a timeout is done by dropping the future. No additional cleanup
 /// or other work is required.
@@ -91,9 +142,9 @@ where
 /// }
 /// # }
 /// ```
-pub fn timeout_at<T>(deadline: Instant, future: T) -> Timeout<T>
+pub fn timeout_at<F>(deadline: Instant, future: F) -> Timeout<F>
 where
-    T: Future,
+    F: Future,
 {
     let delay = sleep_until(deadline);
 
@@ -145,15 +196,33 @@ where
     fn poll(self: Pin<&mut Self>, cx: &mut task::Context<'_>) -> Poll<Self::Output> {
         let me = self.project();
 
+        let had_budget_before = coop::has_budget_remaining();
+
         // First, try polling the future
         if let Poll::Ready(v) = me.value.poll(cx) {
             return Poll::Ready(Ok(v));
         }
 
-        // Now check the timer
-        match me.delay.poll(cx) {
-            Poll::Ready(()) => Poll::Ready(Err(Elapsed::new())),
-            Poll::Pending => Poll::Pending,
+        let has_budget_now = coop::has_budget_remaining();
+
+        let delay = me.delay;
+
+        let poll_delay = || -> Poll<Self::Output> {
+            match delay.poll(cx) {
+                Poll::Ready(()) => Poll::Ready(Err(Elapsed::new())),
+                Poll::Pending => Poll::Pending,
+            }
+        };
+
+        if let (true, false) = (had_budget_before, has_budget_now) {
+            // if it is the underlying future that exhausted the budget, we poll
+            // the `delay` with an unconstrained one. This prevents pathological
+            // cases where the underlying future always exhausts the budget and
+            // we never get a chance to evaluate whether the timeout was hit or
+            // not.
+            coop::with_unconstrained(poll_delay)
+        } else {
+            poll_delay()
         }
     }
 }
diff --git a/vendor/tokio/src/runtime/thread_pool/atomic_cell.rs b/vendor/tokio/src/util/atomic_cell.rs
index 98847e6ff..07e37303a 100644
--- a/vendor/tokio/src/runtime/thread_pool/atomic_cell.rs
+++ b/vendor/tokio/src/util/atomic_cell.rs
@@ -3,7 +3,7 @@ use crate::loom::sync::atomic::AtomicPtr;
 use std::ptr;
 use std::sync::atomic::Ordering::AcqRel;
 
-pub(super) struct AtomicCell<T> {
+pub(crate) struct AtomicCell<T> {
     data: AtomicPtr<T>,
 }
 
@@ -11,22 +11,22 @@ unsafe impl<T: Send> Send for AtomicCell<T> {}
 unsafe impl<T: Send> Sync for AtomicCell<T> {}
 
 impl<T> AtomicCell<T> {
-    pub(super) fn new(data: Option<Box<T>>) -> AtomicCell<T> {
+    pub(crate) fn new(data: Option<Box<T>>) -> AtomicCell<T> {
         AtomicCell {
             data: AtomicPtr::new(to_raw(data)),
         }
     }
 
-    pub(super) fn swap(&self, val: Option<Box<T>>) -> Option<Box<T>> {
+    pub(crate) fn swap(&self, val: Option<Box<T>>) -> Option<Box<T>> {
         let old = self.data.swap(to_raw(val), AcqRel);
         from_raw(old)
     }
 
-    pub(super) fn set(&self, val: Box<T>) {
+    pub(crate) fn set(&self, val: Box<T>) {
         let _ = self.swap(Some(val));
     }
 
-    pub(super) fn take(&self) -> Option<Box<T>> {
+    pub(crate) fn take(&self) -> Option<Box<T>> {
         self.swap(None)
     }
 }
diff --git a/vendor/tokio/src/util/bit.rs b/vendor/tokio/src/util/bit.rs
index 392a0e8b0..a43c2c2d3 100644
--- a/vendor/tokio/src/util/bit.rs
+++ b/vendor/tokio/src/util/bit.rs
@@ -27,7 +27,7 @@ impl Pack {
         pointer_width() - (self.mask >> self.shift).leading_zeros()
     }
 
-    /// Max representable value
+    /// Max representable value.
     pub(crate) const fn max_value(&self) -> usize {
         (1 << self.width()) - 1
     }
@@ -60,7 +60,7 @@ impl fmt::Debug for Pack {
     }
 }
 
-/// Returns the width of a pointer in bits
+/// Returns the width of a pointer in bits.
 pub(crate) const fn pointer_width() -> u32 {
     std::mem::size_of::<usize>() as u32 * 8
 }
@@ -71,7 +71,7 @@ pub(crate) const fn mask_for(n: u32) -> usize {
     shift | (shift - 1)
 }
 
-/// Unpack a value using a mask & shift
+/// Unpacks a value using a mask & shift.
 pub(crate) const fn unpack(src: usize, mask: usize, shift: u32) -> usize {
     (src & mask) >> shift
 }
diff --git a/vendor/tokio/src/util/error.rs b/vendor/tokio/src/util/error.rs
index 0e52364a7..ebb27f638 100644
--- a/vendor/tokio/src/util/error.rs
+++ b/vendor/tokio/src/util/error.rs
@@ -1,9 +1,16 @@
+// Some combinations of features may not use these constants.
+#![cfg_attr(not(feature = "full"), allow(dead_code))]
+
 /// Error string explaining that the Tokio context hasn't been instantiated.
 pub(crate) const CONTEXT_MISSING_ERROR: &str =
     "there is no reactor running, must be called from the context of a Tokio 1.x runtime";
 
-// some combinations of features might not use this
-#[allow(dead_code)]
 /// Error string explaining that the Tokio context is shutting down and cannot drive timers.
 pub(crate) const RUNTIME_SHUTTING_DOWN_ERROR: &str =
     "A Tokio 1.x context was found, but it is being shutdown.";
+
+/// Error string explaining that the Tokio context is not available because the
+/// thread-local storing it has been destroyed. This usually only happens during
+/// destructors of other thread-locals.
+pub(crate) const THREAD_LOCAL_DESTROYED_ERROR: &str =
+    "The Tokio context thread-local variable has been destroyed.";
diff --git a/vendor/tokio/src/util/idle_notified_set.rs b/vendor/tokio/src/util/idle_notified_set.rs
new file mode 100644
index 000000000..19b81e28b
--- /dev/null
+++ b/vendor/tokio/src/util/idle_notified_set.rs
@@ -0,0 +1,481 @@
+//! This module defines an `IdleNotifiedSet`, which is a collection of elements.
+//! Each element is intended to correspond to a task, and the collection will
+//! keep track of which tasks have had their waker notified, and which have not.
+//!
+//! Each entry in the set holds some user-specified value. The value's type is
+//! specified using the `T` parameter. It will usually be a `JoinHandle` or
+//! similar.
+
+use std::marker::PhantomPinned;
+use std::mem::ManuallyDrop;
+use std::ptr::NonNull;
+use std::task::{Context, Waker};
+
+use crate::loom::cell::UnsafeCell;
+use crate::loom::sync::{Arc, Mutex};
+use crate::util::linked_list::{self, Link};
+use crate::util::{waker_ref, Wake};
+
+type LinkedList<T> =
+    linked_list::LinkedList<ListEntry<T>, <ListEntry<T> as linked_list::Link>::Target>;
+
+/// This is the main handle to the collection.
+pub(crate) struct IdleNotifiedSet<T> {
+    lists: Arc<Lists<T>>,
+    length: usize,
+}
+
+/// A handle to an entry that is guaranteed to be stored in the idle or notified
+/// list of its `IdleNotifiedSet`. This value borrows the `IdleNotifiedSet`
+/// mutably to prevent the entry from being moved to the `Neither` list, which
+/// only the `IdleNotifiedSet` may do.
+///
+/// The main consequence of being stored in one of the lists is that the `value`
+/// field has not yet been consumed.
+///
+/// Note: This entry can be moved from the idle to the notified list while this
+/// object exists by waking its waker.
+pub(crate) struct EntryInOneOfTheLists<'a, T> {
+    entry: Arc<ListEntry<T>>,
+    set: &'a mut IdleNotifiedSet<T>,
+}
+
+type Lists<T> = Mutex<ListsInner<T>>;
+
+/// The linked lists hold strong references to the ListEntry items, and the
+/// ListEntry items also hold a strong reference back to the Lists object, but
+/// the destructor of the `IdleNotifiedSet` will clear the two lists, so once
+/// that object is destroyed, no ref-cycles will remain.
+struct ListsInner<T> {
+    notified: LinkedList<T>,
+    idle: LinkedList<T>,
+    /// Whenever an element in the `notified` list is woken, this waker will be
+    /// notified and consumed, if it exists.
+    waker: Option<Waker>,
+}
+
+/// Which of the two lists in the shared Lists object is this entry stored in?
+///
+/// If the value is `Idle`, then an entry's waker may move it to the notified
+/// list. Otherwise, only the `IdleNotifiedSet` may move it.
+///
+/// If the value is `Neither`, then it is still possible that the entry is in
+/// some third external list (this happens in `drain`).
+#[derive(Copy, Clone, Eq, PartialEq)]
+enum List {
+    Notified,
+    Idle,
+    Neither,
+}
+
+/// An entry in the list.
+///
+/// # Safety
+///
+/// The `my_list` field must only be accessed while holding the mutex in
+/// `parent`. It is an invariant that the value of `my_list` corresponds to
+/// which linked list in the `parent` holds this entry. Once this field takes
+/// the value `Neither`, then it may never be modified again.
+///
+/// If the value of `my_list` is `Notified` or `Idle`, then the `pointers` field
+/// must only be accessed while holding the mutex. If the value of `my_list` is
+/// `Neither`, then the `pointers` field may be accessed by the
+/// `IdleNotifiedSet` (this happens inside `drain`).
+///
+/// The `value` field is owned by the `IdleNotifiedSet` and may only be accessed
+/// by the `IdleNotifiedSet`. The operation that sets the value of `my_list` to
+/// `Neither` assumes ownership of the `value`, and it must either drop it or
+/// move it out from this entry to prevent it from getting leaked. (Since the
+/// two linked lists are emptied in the destructor of `IdleNotifiedSet`, the
+/// value should not be leaked.)
+struct ListEntry<T> {
+    /// The linked list pointers of the list this entry is in.
+    pointers: linked_list::Pointers<ListEntry<T>>,
+    /// Pointer to the shared `Lists` struct.
+    parent: Arc<Lists<T>>,
+    /// The value stored in this entry.
+    value: UnsafeCell<ManuallyDrop<T>>,
+    /// Used to remember which list this entry is in.
+    my_list: UnsafeCell<List>,
+    /// Required by the `linked_list::Pointers` field.
+    _pin: PhantomPinned,
+}
+
+generate_addr_of_methods! {
+    impl<T> ListEntry<T> {
+        unsafe fn addr_of_pointers(self: NonNull<Self>) -> NonNull<linked_list::Pointers<ListEntry<T>>> {
+            &self.pointers
+        }
+    }
+}
+
+// With mutable access to the `IdleNotifiedSet`, you can get mutable access to
+// the values.
+unsafe impl<T: Send> Send for IdleNotifiedSet<T> {}
+// With the current API we strictly speaking don't even need `T: Sync`, but we
+// require it anyway to support adding &self APIs that access the values in the
+// future.
+unsafe impl<T: Sync> Sync for IdleNotifiedSet<T> {}
+
+// These impls control when it is safe to create a Waker. Since the waker does
+// not allow access to the value in any way (including its destructor), it is
+// not necessary for `T` to be Send or Sync.
+unsafe impl<T> Send for ListEntry<T> {}
+unsafe impl<T> Sync for ListEntry<T> {}
+
+impl<T> IdleNotifiedSet<T> {
+    /// Create a new IdleNotifiedSet.
+    pub(crate) fn new() -> Self {
+        let lists = Mutex::new(ListsInner {
+            notified: LinkedList::new(),
+            idle: LinkedList::new(),
+            waker: None,
+        });
+
+        IdleNotifiedSet {
+            lists: Arc::new(lists),
+            length: 0,
+        }
+    }
+
+    pub(crate) fn len(&self) -> usize {
+        self.length
+    }
+
+    pub(crate) fn is_empty(&self) -> bool {
+        self.length == 0
+    }
+
+    /// Insert the given value into the `idle` list.
+    pub(crate) fn insert_idle(&mut self, value: T) -> EntryInOneOfTheLists<'_, T> {
+        self.length += 1;
+
+        let entry = Arc::new(ListEntry {
+            parent: self.lists.clone(),
+            value: UnsafeCell::new(ManuallyDrop::new(value)),
+            my_list: UnsafeCell::new(List::Idle),
+            pointers: linked_list::Pointers::new(),
+            _pin: PhantomPinned,
+        });
+
+        {
+            let mut lock = self.lists.lock();
+            lock.idle.push_front(entry.clone());
+        }
+
+        // Safety: We just put the entry in the idle list, so it is in one of the lists.
+        EntryInOneOfTheLists { entry, set: self }
+    }
+
+    /// Pop an entry from the notified list to poll it. The entry is moved to
+    /// the idle list atomically.
+    pub(crate) fn pop_notified(&mut self, waker: &Waker) -> Option<EntryInOneOfTheLists<'_, T>> {
+        // We don't decrement the length because this call moves the entry to
+        // the idle list rather than removing it.
+        if self.length == 0 {
+            // Fast path.
+            return None;
+        }
+
+        let mut lock = self.lists.lock();
+
+        let should_update_waker = match lock.waker.as_mut() {
+            Some(cur_waker) => !waker.will_wake(cur_waker),
+            None => true,
+        };
+        if should_update_waker {
+            lock.waker = Some(waker.clone());
+        }
+
+        // Pop the entry, returning None if empty.
+        let entry = lock.notified.pop_back()?;
+
+        lock.idle.push_front(entry.clone());
+
+        // Safety: We are holding the lock.
+        entry.my_list.with_mut(|ptr| unsafe {
+            *ptr = List::Idle;
+        });
+
+        drop(lock);
+
+        // Safety: We just put the entry in the idle list, so it is in one of the lists.
+        Some(EntryInOneOfTheLists { entry, set: self })
+    }
+
+    /// Call a function on every element in this list.
+    pub(crate) fn for_each<F: FnMut(&mut T)>(&mut self, mut func: F) {
+        fn get_ptrs<T>(list: &mut LinkedList<T>, ptrs: &mut Vec<*mut T>) {
+            let mut node = list.last();
+
+            while let Some(entry) = node {
+                ptrs.push(entry.value.with_mut(|ptr| {
+                    let ptr: *mut ManuallyDrop<T> = ptr;
+                    let ptr: *mut T = ptr.cast();
+                    ptr
+                }));
+
+                let prev = entry.pointers.get_prev();
+                node = prev.map(|prev| unsafe { &*prev.as_ptr() });
+            }
+        }
+
+        // Atomically get a raw pointer to the value of every entry.
+        //
+        // Since this only locks the mutex once, it is not possible for a value
+        // to get moved from the idle list to the notified list during the
+        // operation, which would otherwise result in some value being listed
+        // twice.
+        let mut ptrs = Vec::with_capacity(self.len());
+        {
+            let mut lock = self.lists.lock();
+
+            get_ptrs(&mut lock.idle, &mut ptrs);
+            get_ptrs(&mut lock.notified, &mut ptrs);
+        }
+        debug_assert_eq!(ptrs.len(), ptrs.capacity());
+
+        for ptr in ptrs {
+            // Safety: When we grabbed the pointers, the entries were in one of
+            // the two lists. This means that their value was valid at the time,
+            // and it must still be valid because we are the IdleNotifiedSet,
+            // and only we can remove an entry from the two lists. (It's
+            // possible that an entry is moved from one list to the other during
+            // this loop, but that is ok.)
+            func(unsafe { &mut *ptr });
+        }
+    }
+
+    /// Remove all entries in both lists, applying some function to each element.
+    ///
+    /// The closure is called on all elements even if it panics. Having it panic
+    /// twice is a double-panic, and will abort the application.
+    pub(crate) fn drain<F: FnMut(T)>(&mut self, func: F) {
+        if self.length == 0 {
+            // Fast path.
+            return;
+        }
+        self.length = 0;
+
+        // The LinkedList is not cleared on panic, so we use a bomb to clear it.
+        //
+        // This value has the invariant that any entry in its `all_entries` list
+        // has `my_list` set to `Neither` and that the value has not yet been
+        // dropped.
+        struct AllEntries<T, F: FnMut(T)> {
+            all_entries: LinkedList<T>,
+            func: F,
+        }
+
+        impl<T, F: FnMut(T)> AllEntries<T, F> {
+            fn pop_next(&mut self) -> bool {
+                if let Some(entry) = self.all_entries.pop_back() {
+                    // Safety: We just took this value from the list, so we can
+                    // destroy the value in the entry.
+                    entry
+                        .value
+                        .with_mut(|ptr| unsafe { (self.func)(ManuallyDrop::take(&mut *ptr)) });
+                    true
+                } else {
+                    false
+                }
+            }
+        }
+
+        impl<T, F: FnMut(T)> Drop for AllEntries<T, F> {
+            fn drop(&mut self) {
+                while self.pop_next() {}
+            }
+        }
+
+        let mut all_entries = AllEntries {
+            all_entries: LinkedList::new(),
+            func,
+        };
+
+        // Atomically move all entries to the new linked list in the AllEntries
+        // object.
+        {
+            let mut lock = self.lists.lock();
+            unsafe {
+                // Safety: We are holding the lock and `all_entries` is a new
+                // LinkedList.
+                move_to_new_list(&mut lock.idle, &mut all_entries.all_entries);
+                move_to_new_list(&mut lock.notified, &mut all_entries.all_entries);
+            }
+        }
+
+        // Keep destroying entries in the list until it is empty.
+        //
+        // If the closure panics, then the destructor of the `AllEntries` bomb
+        // ensures that we keep running the destructor on the remaining values.
+        // A second panic will abort the program.
+        while all_entries.pop_next() {}
+    }
+}
+
+/// # Safety
+///
+/// The mutex for the entries must be held, and the target list must be such
+/// that setting `my_list` to `Neither` is ok.
+unsafe fn move_to_new_list<T>(from: &mut LinkedList<T>, to: &mut LinkedList<T>) {
+    while let Some(entry) = from.pop_back() {
+        entry.my_list.with_mut(|ptr| {
+            *ptr = List::Neither;
+        });
+        to.push_front(entry);
+    }
+}
+
+impl<'a, T> EntryInOneOfTheLists<'a, T> {
+    /// Remove this entry from the list it is in, returning the value associated
+    /// with the entry.
+    ///
+    /// This consumes the value, since it is no longer guaranteed to be in a
+    /// list.
+    pub(crate) fn remove(self) -> T {
+        self.set.length -= 1;
+
+        {
+            let mut lock = self.set.lists.lock();
+
+            // Safety: We are holding the lock so there is no race, and we will
+            // remove the entry afterwards to uphold invariants.
+            let old_my_list = self.entry.my_list.with_mut(|ptr| unsafe {
+                let old_my_list = *ptr;
+                *ptr = List::Neither;
+                old_my_list
+            });
+
+            let list = match old_my_list {
+                List::Idle => &mut lock.idle,
+                List::Notified => &mut lock.notified,
+                // An entry in one of the lists is in one of the lists.
+                List::Neither => unreachable!(),
+            };
+
+            unsafe {
+                // Safety: We just checked that the entry is in this particular
+                // list.
+                list.remove(ListEntry::as_raw(&self.entry)).unwrap();
+            }
+        }
+
+        // By setting `my_list` to `Neither`, we have taken ownership of the
+        // value. We return it to the caller.
+        //
+        // Safety: We have a mutable reference to the `IdleNotifiedSet` that
+        // owns this entry, so we can use its permission to access the value.
+        self.entry
+            .value
+            .with_mut(|ptr| unsafe { ManuallyDrop::take(&mut *ptr) })
+    }
+
+    /// Access the value in this entry together with a context for its waker.
+    pub(crate) fn with_value_and_context<F, U>(&mut self, func: F) -> U
+    where
+        F: FnOnce(&mut T, &mut Context<'_>) -> U,
+        T: 'static,
+    {
+        let waker = waker_ref(&self.entry);
+
+        let mut context = Context::from_waker(&waker);
+
+        // Safety: We have a mutable reference to the `IdleNotifiedSet` that
+        // owns this entry, so we can use its permission to access the value.
+        self.entry
+            .value
+            .with_mut(|ptr| unsafe { func(&mut *ptr, &mut context) })
+    }
+}
+
+impl<T> Drop for IdleNotifiedSet<T> {
+    fn drop(&mut self) {
+        // Clear both lists.
+        self.drain(drop);
+
+        #[cfg(debug_assertions)]
+        if !std::thread::panicking() {
+            let lock = self.lists.lock();
+            assert!(lock.idle.is_empty());
+            assert!(lock.notified.is_empty());
+        }
+    }
+}
+
+impl<T: 'static> Wake for ListEntry<T> {
+    fn wake_by_ref(me: &Arc<Self>) {
+        let mut lock = me.parent.lock();
+
+        // Safety: We are holding the lock and we will update the lists to
+        // maintain invariants.
+        let old_my_list = me.my_list.with_mut(|ptr| unsafe {
+            let old_my_list = *ptr;
+            if old_my_list == List::Idle {
+                *ptr = List::Notified;
+            }
+            old_my_list
+        });
+
+        if old_my_list == List::Idle {
+            // We move ourself to the notified list.
+            let me = unsafe {
+                // Safety: We just checked that we are in this particular list.
+                lock.idle.remove(ListEntry::as_raw(me)).unwrap()
+            };
+            lock.notified.push_front(me);
+
+            if let Some(waker) = lock.waker.take() {
+                drop(lock);
+                waker.wake();
+            }
+        }
+    }
+
+    fn wake(me: Arc<Self>) {
+        Self::wake_by_ref(&me)
+    }
+}
+
+/// # Safety
+///
+/// `ListEntry` is forced to be !Unpin.
+unsafe impl<T> linked_list::Link for ListEntry<T> {
+    type Handle = Arc<ListEntry<T>>;
+    type Target = ListEntry<T>;
+
+    fn as_raw(handle: &Self::Handle) -> NonNull<ListEntry<T>> {
+        let ptr: *const ListEntry<T> = Arc::as_ptr(handle);
+        // Safety: We can't get a null pointer from `Arc::as_ptr`.
+        unsafe { NonNull::new_unchecked(ptr as *mut ListEntry<T>) }
+    }
+
+    unsafe fn from_raw(ptr: NonNull<ListEntry<T>>) -> Arc<ListEntry<T>> {
+        Arc::from_raw(ptr.as_ptr())
+    }
+
+    unsafe fn pointers(
+        target: NonNull<ListEntry<T>>,
+    ) -> NonNull<linked_list::Pointers<ListEntry<T>>> {
+        ListEntry::addr_of_pointers(target)
+    }
+}
+
+#[cfg(all(test, not(loom)))]
+mod tests {
+    use crate::runtime::Builder;
+    use crate::task::JoinSet;
+
+    // A test that runs under miri.
+    //
+    // https://github.com/tokio-rs/tokio/pull/5693
+    #[test]
+    fn join_set_test() {
+        let rt = Builder::new_current_thread().build().unwrap();
+
+        let mut set = JoinSet::new();
+        set.spawn_on(futures::future::ready(()), rt.handle());
+
+        rt.block_on(set.join_next()).unwrap().unwrap();
+    }
+}
diff --git a/vendor/tokio/src/util/linked_list.rs b/vendor/tokio/src/util/linked_list.rs
index a74f56215..ca6ef0e7b 100644
--- a/vendor/tokio/src/util/linked_list.rs
+++ b/vendor/tokio/src/util/linked_list.rs
@@ -1,6 +1,6 @@
 #![cfg_attr(not(feature = "full"), allow(dead_code))]
 
-//! An intrusive double linked list of data
+//! An intrusive double linked list of data.
 //!
 //! The data structure supports tracking pinned nodes. Most of the data
 //! structure's APIs are `unsafe` as they require the caller to ensure the
@@ -46,10 +46,10 @@ pub(crate) unsafe trait Link {
     /// This is usually a pointer-ish type.
     type Handle;
 
-    /// Node type
+    /// Node type.
     type Target;
 
-    /// Convert the handle to a raw pointer without consuming the handle
+    /// Convert the handle to a raw pointer without consuming the handle.
     #[allow(clippy::wrong_self_convention)]
     fn as_raw(handle: &Self::Handle) -> NonNull<Self::Target>;
 
@@ -57,10 +57,17 @@ pub(crate) unsafe trait Link {
     unsafe fn from_raw(ptr: NonNull<Self::Target>) -> Self::Handle;
 
     /// Return the pointers for a node
+    ///
+    /// # Safety
+    ///
+    /// The resulting pointer should have the same tag in the stacked-borrows
+    /// stack as the argument. In particular, the method may not create an
+    /// intermediate reference in the process of creating the resulting raw
+    /// pointer.
     unsafe fn pointers(target: NonNull<Self::Target>) -> NonNull<Pointers<Self::Target>>;
 }
 
-/// Previous / next pointers
+/// Previous / next pointers.
 pub(crate) struct Pointers<T> {
     inner: UnsafeCell<PointersInner<T>>,
 }
@@ -119,7 +126,7 @@ impl<L: Link> LinkedList<L, L::Target> {
     pub(crate) fn push_front(&mut self, val: L::Handle) {
         // The value should not be dropped, it is being inserted into the list
         let val = ManuallyDrop::new(val);
-        let ptr = L::as_raw(&*val);
+        let ptr = L::as_raw(&val);
         assert_ne!(self.head, Some(ptr));
         unsafe {
             L::pointers(ptr).as_mut().set_next(self.head);
@@ -171,8 +178,12 @@ impl<L: Link> LinkedList<L, L::Target> {
     ///
     /// # Safety
     ///
-    /// The caller **must** ensure that `node` is currently contained by
-    /// `self` or not contained by any other list.
+    /// The caller **must** ensure that exactly one of the following is true:
+    /// - `node` is currently contained by `self`,
+    /// - `node` is not contained by any list,
+    /// - `node` is currently contained by some other `GuardedLinkedList` **and**
+    ///   the caller has an exclusive access to that list. This condition is
+    ///   used by the linked list in `sync::Notify`.
     pub(crate) unsafe fn remove(&mut self, node: NonNull<L::Target>) -> Option<L::Handle> {
         if let Some(prev) = L::pointers(node).as_ref().get_prev() {
             debug_assert_eq!(L::pointers(prev).as_ref().get_next(), Some(node));
@@ -217,8 +228,56 @@ impl<L: Link> fmt::Debug for LinkedList<L, L::Target> {
     }
 }
 
+// ===== impl CountedLinkedList ====
+
+// Delegates operations to the base LinkedList implementation, and adds a counter to the elements
+// in the list.
+pub(crate) struct CountedLinkedList<L: Link, T> {
+    list: LinkedList<L, T>,
+    count: usize,
+}
+
+impl<L: Link> CountedLinkedList<L, L::Target> {
+    pub(crate) fn new() -> CountedLinkedList<L, L::Target> {
+        CountedLinkedList {
+            list: LinkedList::new(),
+            count: 0,
+        }
+    }
+
+    pub(crate) fn push_front(&mut self, val: L::Handle) {
+        self.list.push_front(val);
+        self.count += 1;
+    }
+
+    pub(crate) fn pop_back(&mut self) -> Option<L::Handle> {
+        let val = self.list.pop_back();
+        if val.is_some() {
+            self.count -= 1;
+        }
+        val
+    }
+
+    pub(crate) fn is_empty(&self) -> bool {
+        self.list.is_empty()
+    }
+
+    pub(crate) unsafe fn remove(&mut self, node: NonNull<L::Target>) -> Option<L::Handle> {
+        let val = self.list.remove(node);
+        if val.is_some() {
+            self.count -= 1;
+        }
+        val
+    }
+
+    pub(crate) fn count(&self) -> usize {
+        self.count
+    }
+}
+
 #[cfg(any(
     feature = "fs",
+    feature = "rt",
     all(unix, feature = "process"),
     feature = "signal",
     feature = "sync",
@@ -236,37 +295,6 @@ impl<L: Link> Default for LinkedList<L, L::Target> {
     }
 }
 
-// ===== impl Iter =====
-
-cfg_rt_multi_thread! {
-    pub(crate) struct Iter<'a, T: Link> {
-        curr: Option<NonNull<T::Target>>,
-        _p: core::marker::PhantomData<&'a T>,
-    }
-
-    impl<L: Link> LinkedList<L, L::Target> {
-        pub(crate) fn iter(&self) -> Iter<'_, L> {
-            Iter {
-                curr: self.head,
-                _p: core::marker::PhantomData,
-            }
-        }
-    }
-
-    impl<'a, T: Link> Iterator for Iter<'a, T> {
-        type Item = &'a T::Target;
-
-        fn next(&mut self) -> Option<&'a T::Target> {
-            let curr = self.curr?;
-            // safety: the pointer references data contained by the list
-            self.curr = unsafe { T::pointers(curr).as_ref() }.get_next();
-
-            // safety: the value is still owned by the linked list.
-            Some(unsafe { &*curr.as_ptr() })
-        }
-    }
-}
-
 // ===== impl DrainFilter =====
 
 cfg_io_readiness! {
@@ -313,6 +341,126 @@ cfg_io_readiness! {
     }
 }
 
+cfg_taskdump! {
+    impl<T: Link> CountedLinkedList<T, T::Target> {
+        pub(crate) fn for_each<F>(&mut self, f: F)
+        where
+            F: FnMut(&T::Handle),
+        {
+            self.list.for_each(f)
+        }
+    }
+
+    impl<T: Link> LinkedList<T, T::Target> {
+        pub(crate) fn for_each<F>(&mut self, mut f: F)
+        where
+            F: FnMut(&T::Handle),
+        {
+            use std::mem::ManuallyDrop;
+
+            let mut next = self.head;
+
+            while let Some(curr) = next {
+                unsafe {
+                    let handle = ManuallyDrop::new(T::from_raw(curr));
+                    f(&handle);
+                    next = T::pointers(curr).as_ref().get_next();
+                }
+            }
+        }
+    }
+}
+
+// ===== impl GuardedLinkedList =====
+
+feature! {
+    #![any(
+        feature = "process",
+        feature = "sync",
+        feature = "rt",
+        feature = "signal",
+    )]
+
+    /// An intrusive linked list, but instead of keeping pointers to the head
+    /// and tail nodes, it uses a special guard node linked with those nodes.
+    /// It means that the list is circular and every pointer of a node from
+    /// the list is not `None`, including pointers from the guard node.
+    ///
+    /// If a list is empty, then both pointers of the guard node are pointing
+    /// at the guard node itself.
+    pub(crate) struct GuardedLinkedList<L, T> {
+        /// Pointer to the guard node.
+        guard: NonNull<T>,
+
+        /// Node type marker.
+        _marker: PhantomData<*const L>,
+    }
+
+    impl<U, L: Link<Handle = NonNull<U>>> LinkedList<L, L::Target> {
+        /// Turns a linked list into the guarded version by linking the guard node
+        /// with the head and tail nodes. Like with other nodes, you should guarantee
+        /// that the guard node is pinned in memory.
+        pub(crate) fn into_guarded(self, guard_handle: L::Handle) -> GuardedLinkedList<L, L::Target> {
+            // `guard_handle` is a NonNull pointer, we don't have to care about dropping it.
+            let guard = L::as_raw(&guard_handle);
+
+            unsafe {
+                if let Some(head) = self.head {
+                    debug_assert!(L::pointers(head).as_ref().get_prev().is_none());
+                    L::pointers(head).as_mut().set_prev(Some(guard));
+                    L::pointers(guard).as_mut().set_next(Some(head));
+
+                    // The list is not empty, so the tail cannot be `None`.
+                    let tail = self.tail.unwrap();
+                    debug_assert!(L::pointers(tail).as_ref().get_next().is_none());
+                    L::pointers(tail).as_mut().set_next(Some(guard));
+                    L::pointers(guard).as_mut().set_prev(Some(tail));
+                } else {
+                    // The list is empty.
+                    L::pointers(guard).as_mut().set_prev(Some(guard));
+                    L::pointers(guard).as_mut().set_next(Some(guard));
+                }
+            }
+
+            GuardedLinkedList { guard, _marker: PhantomData }
+        }
+    }
+
+    impl<L: Link> GuardedLinkedList<L, L::Target> {
+        fn tail(&self) -> Option<NonNull<L::Target>> {
+            let tail_ptr = unsafe {
+                L::pointers(self.guard).as_ref().get_prev().unwrap()
+            };
+
+            // Compare the tail pointer with the address of the guard node itself.
+            // If the guard points at itself, then there are no other nodes and
+            // the list is considered empty.
+            if tail_ptr != self.guard {
+                Some(tail_ptr)
+            } else {
+                None
+            }
+        }
+
+        /// Removes the last element from a list and returns it, or None if it is
+        /// empty.
+        pub(crate) fn pop_back(&mut self) -> Option<L::Handle> {
+            unsafe {
+                let last = self.tail()?;
+                let before_last = L::pointers(last).as_ref().get_prev().unwrap();
+
+                L::pointers(self.guard).as_mut().set_prev(Some(before_last));
+                L::pointers(before_last).as_mut().set_next(Some(self.guard));
+
+                L::pointers(last).as_mut().set_prev(None);
+                L::pointers(last).as_mut().set_next(None);
+
+                Some(L::from_raw(last))
+            }
+        }
+    }
+}
+
 // ===== impl Pointers =====
 
 impl<T> Pointers<T> {
@@ -327,7 +475,7 @@ impl<T> Pointers<T> {
         }
     }
 
-    fn get_prev(&self) -> Option<NonNull<T>> {
+    pub(crate) fn get_prev(&self) -> Option<NonNull<T>> {
         // SAFETY: prev is the first field in PointersInner, which is #[repr(C)].
         unsafe {
             let inner = self.inner.get();
@@ -335,7 +483,7 @@ impl<T> Pointers<T> {
             ptr::read(prev)
         }
     }
-    fn get_next(&self) -> Option<NonNull<T>> {
+    pub(crate) fn get_next(&self) -> Option<NonNull<T>> {
         // SAFETY: next is the second field in PointersInner, which is #[repr(C)].
         unsafe {
             let inner = self.inner.get();
@@ -375,14 +523,15 @@ impl<T> fmt::Debug for Pointers<T> {
     }
 }
 
-#[cfg(test)]
+#[cfg(any(test, fuzzing))]
 #[cfg(not(loom))]
-mod tests {
+pub(crate) mod tests {
     use super::*;
 
     use std::pin::Pin;
 
     #[derive(Debug)]
+    #[repr(C)]
     struct Entry {
         pointers: Pointers<Entry>,
         val: i32,
@@ -400,8 +549,8 @@ mod tests {
             Pin::new_unchecked(&*ptr.as_ptr())
         }
 
-        unsafe fn pointers(mut target: NonNull<Entry>) -> NonNull<Pointers<Entry>> {
-            NonNull::from(&mut target.as_mut().pointers)
+        unsafe fn pointers(target: NonNull<Entry>) -> NonNull<Pointers<Entry>> {
+            target.cast()
         }
     }
 
@@ -435,6 +584,7 @@ mod tests {
         }
     }
 
+    #[cfg(test)]
     macro_rules! assert_clean {
         ($e:ident) => {{
             assert!($e.pointers.get_next().is_none());
@@ -442,6 +592,7 @@ mod tests {
         }};
     }
 
+    #[cfg(test)]
     macro_rules! assert_ptr_eq {
         ($a:expr, $b:expr) => {{
             // Deal with mapping a Pin<&mut T> -> Option<NonNull<T>>
@@ -646,46 +797,41 @@ mod tests {
     }
 
     #[test]
-    fn iter() {
+    fn count() {
+        let mut list = CountedLinkedList::<&Entry, <&Entry as Link>::Target>::new();
+        assert_eq!(0, list.count());
+
         let a = entry(5);
         let b = entry(7);
-
-        let mut list = LinkedList::<&Entry, <&Entry as Link>::Target>::new();
-
-        assert_eq!(0, list.iter().count());
-
         list.push_front(a.as_ref());
         list.push_front(b.as_ref());
+        assert_eq!(2, list.count());
 
-        let mut i = list.iter();
-        assert_eq!(7, i.next().unwrap().val);
-        assert_eq!(5, i.next().unwrap().val);
-        assert!(i.next().is_none());
-    }
+        list.pop_back();
+        assert_eq!(1, list.count());
 
-    proptest::proptest! {
-        #[test]
-        fn fuzz_linked_list(ops: Vec<usize>) {
-            run_fuzz(ops);
+        unsafe {
+            list.remove(ptr(&b));
         }
+        assert_eq!(0, list.count());
     }
 
-    fn run_fuzz(ops: Vec<usize>) {
-        use std::collections::VecDeque;
-
-        #[derive(Debug)]
+    /// This is a fuzz test. You run it by entering `cargo fuzz run fuzz_linked_list` in CLI in `/tokio/` module.
+    #[cfg(fuzzing)]
+    pub fn fuzz_linked_list(ops: &[u8]) {
         enum Op {
             Push,
             Pop,
             Remove(usize),
         }
+        use std::collections::VecDeque;
 
         let ops = ops
             .iter()
-            .map(|i| match i % 3 {
+            .map(|i| match i % 3u8 {
                 0 => Op::Push,
                 1 => Op::Pop,
-                2 => Op::Remove(i / 3),
+                2 => Op::Remove((i / 3u8) as usize),
                 _ => unreachable!(),
             })
             .collect::<Vec<_>>();
diff --git a/vendor/tokio/src/util/markers.rs b/vendor/tokio/src/util/markers.rs
new file mode 100644
index 000000000..7031fb6bc
--- /dev/null
+++ b/vendor/tokio/src/util/markers.rs
@@ -0,0 +1,8 @@
+/// Marker for types that are `Sync` but not `Send`
+pub(crate) struct SyncNotSend(*mut ());
+
+unsafe impl Sync for SyncNotSend {}
+
+cfg_rt! {
+    pub(crate) struct NotSendOrSync(*mut ());
+}
diff --git a/vendor/tokio/src/util/memchr.rs b/vendor/tokio/src/util/memchr.rs
new file mode 100644
index 000000000..44fd2da37
--- /dev/null
+++ b/vendor/tokio/src/util/memchr.rs
@@ -0,0 +1,74 @@
+//! Search for a byte in a byte array using libc.
+//!
+//! When nothing pulls in libc, then just use a trivial implementation. Note
+//! that we only depend on libc on unix.
+
+#[cfg(not(all(unix, feature = "libc")))]
+pub(crate) fn memchr(needle: u8, haystack: &[u8]) -> Option<usize> {
+    haystack.iter().position(|val| needle == *val)
+}
+
+#[cfg(all(unix, feature = "libc"))]
+pub(crate) fn memchr(needle: u8, haystack: &[u8]) -> Option<usize> {
+    let start = haystack.as_ptr();
+
+    // SAFETY: `start` is valid for `haystack.len()` bytes.
+    let ptr = unsafe { libc::memchr(start.cast(), needle as _, haystack.len()) };
+
+    if ptr.is_null() {
+        None
+    } else {
+        Some(ptr as usize - start as usize)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::memchr;
+
+    #[test]
+    fn memchr_test() {
+        let haystack = b"123abc456\0\xffabc\n";
+
+        assert_eq!(memchr(b'1', haystack), Some(0));
+        assert_eq!(memchr(b'2', haystack), Some(1));
+        assert_eq!(memchr(b'3', haystack), Some(2));
+        assert_eq!(memchr(b'4', haystack), Some(6));
+        assert_eq!(memchr(b'5', haystack), Some(7));
+        assert_eq!(memchr(b'6', haystack), Some(8));
+        assert_eq!(memchr(b'7', haystack), None);
+        assert_eq!(memchr(b'a', haystack), Some(3));
+        assert_eq!(memchr(b'b', haystack), Some(4));
+        assert_eq!(memchr(b'c', haystack), Some(5));
+        assert_eq!(memchr(b'd', haystack), None);
+        assert_eq!(memchr(b'A', haystack), None);
+        assert_eq!(memchr(0, haystack), Some(9));
+        assert_eq!(memchr(0xff, haystack), Some(10));
+        assert_eq!(memchr(0xfe, haystack), None);
+        assert_eq!(memchr(1, haystack), None);
+        assert_eq!(memchr(b'\n', haystack), Some(14));
+        assert_eq!(memchr(b'\r', haystack), None);
+    }
+
+    #[test]
+    fn memchr_all() {
+        let mut arr = Vec::new();
+        for b in 0..=255 {
+            arr.push(b);
+        }
+        for b in 0..=255 {
+            assert_eq!(memchr(b, &arr), Some(b as usize));
+        }
+        arr.reverse();
+        for b in 0..=255 {
+            assert_eq!(memchr(b, &arr), Some(255 - b as usize));
+        }
+    }
+
+    #[test]
+    fn memchr_empty() {
+        for b in 0..=255 {
+            assert_eq!(memchr(b, b""), None);
+        }
+    }
+}
diff --git a/vendor/tokio/src/util/mod.rs b/vendor/tokio/src/util/mod.rs
index b267125b1..6a7d4b103 100644
--- a/vendor/tokio/src/util/mod.rs
+++ b/vendor/tokio/src/util/mod.rs
@@ -3,6 +3,40 @@ cfg_io_driver! {
     pub(crate) mod slab;
 }
 
+#[cfg(feature = "rt")]
+pub(crate) mod atomic_cell;
+
+#[cfg(any(
+    feature = "rt",
+    feature = "signal",
+    feature = "process",
+    tokio_no_const_mutex_new,
+))]
+pub(crate) mod once_cell;
+
+#[cfg(any(
+    // io driver uses `WakeList` directly
+    feature = "net",
+    feature = "process",
+    // `sync` enables `Notify` and `batch_semaphore`, which require `WakeList`.
+    feature = "sync",
+    // `fs` uses `batch_semaphore`, which requires `WakeList`.
+    feature = "fs",
+    // rt and signal use `Notify`, which requires `WakeList`.
+    feature = "rt",
+    feature = "signal",
+))]
+mod wake_list;
+#[cfg(any(
+    feature = "net",
+    feature = "process",
+    feature = "sync",
+    feature = "fs",
+    feature = "rt",
+    feature = "signal",
+))]
+pub(crate) use wake_list::WakeList;
+
 #[cfg(any(
     feature = "fs",
     feature = "net",
@@ -14,33 +48,36 @@ cfg_io_driver! {
 ))]
 pub(crate) mod linked_list;
 
-#[cfg(any(feature = "rt-multi-thread", feature = "macros"))]
-mod rand;
+#[cfg(any(feature = "rt", feature = "macros"))]
+pub(crate) mod rand;
 
 cfg_rt! {
+    mod idle_notified_set;
+    pub(crate) use idle_notified_set::IdleNotifiedSet;
+
+    pub(crate) use self::rand::RngSeedGenerator;
+
     mod wake;
     pub(crate) use wake::WakerRef;
     pub(crate) use wake::{waker_ref, Wake};
+
+    mod sync_wrapper;
+    pub(crate) use sync_wrapper::SyncWrapper;
+
+    mod rc_cell;
+    pub(crate) use rc_cell::RcCell;
 }
 
 cfg_rt_multi_thread! {
-    pub(crate) use self::rand::FastRand;
-
     mod try_lock;
     pub(crate) use try_lock::TryLock;
 }
 
 pub(crate) mod trace;
 
-#[cfg(any(feature = "macros"))]
-#[cfg_attr(not(feature = "macros"), allow(unreachable_pub))]
-pub use self::rand::thread_rng_n;
-
-#[cfg(any(
-    feature = "rt",
-    feature = "time",
-    feature = "net",
-    feature = "process",
-    all(unix, feature = "signal")
-))]
 pub(crate) mod error;
+
+#[cfg(feature = "io-util")]
+pub(crate) mod memchr;
+
+pub(crate) mod markers;
diff --git a/vendor/tokio/src/util/once_cell.rs b/vendor/tokio/src/util/once_cell.rs
new file mode 100644
index 000000000..71fc00758
--- /dev/null
+++ b/vendor/tokio/src/util/once_cell.rs
@@ -0,0 +1,70 @@
+#![allow(dead_code)]
+use std::cell::UnsafeCell;
+use std::mem::MaybeUninit;
+use std::sync::Once;
+
+pub(crate) struct OnceCell<T> {
+    once: Once,
+    value: UnsafeCell<MaybeUninit<T>>,
+}
+
+unsafe impl<T: Send + Sync> Send for OnceCell<T> {}
+unsafe impl<T: Send + Sync> Sync for OnceCell<T> {}
+
+impl<T> OnceCell<T> {
+    pub(crate) const fn new() -> Self {
+        Self {
+            once: Once::new(),
+            value: UnsafeCell::new(MaybeUninit::uninit()),
+        }
+    }
+
+    /// Get the value inside this cell, initializing it using the provided
+    /// function if necessary.
+    ///
+    /// If the `init` closure panics, then the `OnceCell` is poisoned and all
+    /// future calls to `get` will panic.
+    #[inline]
+    pub(crate) fn get(&self, init: impl FnOnce() -> T) -> &T {
+        if !self.once.is_completed() {
+            self.do_init(init);
+        }
+
+        // Safety: The `std::sync::Once` guarantees that we can only reach this
+        // line if a `call_once` closure has been run exactly once and without
+        // panicking. Thus, the value is not uninitialized.
+        //
+        // There is also no race because the only `&self` method that modifies
+        // `value` is `do_init`, but if the `call_once` closure is still
+        // running, then no thread has gotten past the `call_once`.
+        unsafe { &*(self.value.get() as *const T) }
+    }
+
+    #[cold]
+    fn do_init(&self, init: impl FnOnce() -> T) {
+        let value_ptr = self.value.get() as *mut T;
+
+        self.once.call_once(|| {
+            let set_to = init();
+
+            // Safety: The `std::sync::Once` guarantees that this initialization
+            // will run at most once, and that no thread can get past the
+            // `call_once` until it has run exactly once. Thus, we have
+            // exclusive access to `value`.
+            unsafe {
+                std::ptr::write(value_ptr, set_to);
+            }
+        });
+    }
+}
+
+impl<T> Drop for OnceCell<T> {
+    fn drop(&mut self) {
+        if self.once.is_completed() {
+            let value_ptr = self.value.get() as *mut T;
+            unsafe {
+                std::ptr::drop_in_place(value_ptr);
+            }
+        }
+    }
+}
diff --git a/vendor/tokio/src/util/pad.rs b/vendor/tokio/src/util/pad.rs
deleted file mode 100644
index bf0913ca8..000000000
--- a/vendor/tokio/src/util/pad.rs
+++ /dev/null
@@ -1,52 +0,0 @@
-use core::fmt;
-use core::ops::{Deref, DerefMut};
-
-#[derive(Clone, Copy, Default, Hash, PartialEq, Eq)]
-// Starting from Intel's Sandy Bridge, spatial prefetcher is now pulling pairs of 64-byte cache
-// lines at a time, so we have to align to 128 bytes rather than 64.
-//
-// Sources:
-// - https://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-optimization-manual.pdf
-// - https://github.com/facebook/folly/blob/1b5288e6eea6df074758f877c849b6e73bbb9fbb/folly/lang/Align.h#L107
-#[cfg_attr(target_arch = "x86_64", repr(align(128)))]
-#[cfg_attr(not(target_arch = "x86_64"), repr(align(64)))]
-pub(crate) struct CachePadded<T> {
-    value: T,
-}
-
-unsafe impl<T: Send> Send for CachePadded<T> {}
-unsafe impl<T: Sync> Sync for CachePadded<T> {}
-
-impl<T> CachePadded<T> {
-    pub(crate) fn new(t: T) -> CachePadded<T> {
-        CachePadded::<T> { value: t }
-    }
-}
-
-impl<T> Deref for CachePadded<T> {
-    type Target = T;
-
-    fn deref(&self) -> &T {
-        &self.value
-    }
-}
-
-impl<T> DerefMut for CachePadded<T> {
-    fn deref_mut(&mut self) -> &mut T {
-        &mut self.value
-    }
-}
-
-impl<T: fmt::Debug> fmt::Debug for CachePadded<T> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.debug_struct("CachePadded")
-            .field("value", &self.value)
-            .finish()
-    }
-}
-
-impl<T> From<T> for CachePadded<T> {
-    fn from(t: T) -> Self {
-        CachePadded::new(t)
-    }
-}
diff --git a/vendor/tokio/src/util/rand.rs b/vendor/tokio/src/util/rand.rs
index 17b3ec1ae..d96c8d37e 100644
--- a/vendor/tokio/src/util/rand.rs
+++ b/vendor/tokio/src/util/rand.rs
@@ -1,21 +1,43 @@
-use std::cell::Cell;
+cfg_rt! {
+    mod rt;
+    pub(crate) use rt::RngSeedGenerator;
 
-/// Fast random number generate
+    cfg_unstable! {
+        mod rt_unstable;
+    }
+}
+
+/// A seed for random number generation.
+///
+/// In order to make certain functions within a runtime deterministic, a seed
+/// can be specified at the time of creation.
+#[allow(unreachable_pub)]
+#[derive(Clone, Debug)]
+pub struct RngSeed {
+    s: u32,
+    r: u32,
+}
+
+/// Fast random number generate.
 ///
 /// Implement xorshift64+: 2 32-bit xorshift sequences added together.
 /// Shift triplet `[17,7,16]` was calculated as indicated in Marsaglia's
 /// Xorshift paper: <https://www.jstatsoft.org/article/view/v008i14/xorshift.pdf>
 /// This generator passes the SmallCrush suite, part of TestU01 framework:
 /// <http://simul.iro.umontreal.ca/testu01/tu01.html>
-#[derive(Debug)]
+#[derive(Clone, Copy, Debug)]
 pub(crate) struct FastRand {
-    one: Cell<u32>,
-    two: Cell<u32>,
+    one: u32,
+    two: u32,
 }
 
-impl FastRand {
-    /// Initialize a new, thread-local, fast random number generator.
-    pub(crate) fn new(seed: u64) -> FastRand {
+impl RngSeed {
+    /// Creates a random seed using loom internally.
+    pub(crate) fn new() -> Self {
+        Self::from_u64(crate::loom::rand::seed())
+    }
+
+    fn from_u64(seed: u64) -> Self {
         let one = (seed >> 32) as u32;
         let mut two = seed as u32;
 
@@ -24,41 +46,50 @@ impl FastRand {
             two = 1;
         }
 
+        Self::from_pair(one, two)
+    }
+
+    fn from_pair(s: u32, r: u32) -> Self {
+        Self { s, r }
+    }
+}
+
+impl FastRand {
+    /// Initialize a new fast random number generator using the default source of entropy.
+    pub(crate) fn new() -> FastRand {
+        FastRand::from_seed(RngSeed::new())
+    }
+
+    /// Initializes a new, thread-local, fast random number generator.
+    pub(crate) fn from_seed(seed: RngSeed) -> FastRand {
         FastRand {
-            one: Cell::new(one),
-            two: Cell::new(two),
+            one: seed.s,
+            two: seed.r,
         }
     }
 
-    pub(crate) fn fastrand_n(&self, n: u32) -> u32 {
+    #[cfg(any(
+        feature = "macros",
+        feature = "rt-multi-thread",
+        all(feature = "sync", feature = "rt")
+    ))]
+    pub(crate) fn fastrand_n(&mut self, n: u32) -> u32 {
         // This is similar to fastrand() % n, but faster.
         // See https://lemire.me/blog/2016/06/27/a-fast-alternative-to-the-modulo-reduction/
         let mul = (self.fastrand() as u64).wrapping_mul(n as u64);
         (mul >> 32) as u32
     }
 
-    fn fastrand(&self) -> u32 {
-        let mut s1 = self.one.get();
-        let s0 = self.two.get();
+    fn fastrand(&mut self) -> u32 {
+        let mut s1 = self.one;
+        let s0 = self.two;
 
         s1 ^= s1 << 17;
         s1 = s1 ^ s0 ^ s1 >> 7 ^ s0 >> 16;
 
-        self.one.set(s0);
-        self.two.set(s1);
+        self.one = s0;
+        self.two = s1;
 
         s0.wrapping_add(s1)
     }
 }
-
-// Used by the select macro and `StreamMap`
-#[cfg(any(feature = "macros"))]
-#[doc(hidden)]
-#[cfg_attr(not(feature = "macros"), allow(unreachable_pub))]
-pub fn thread_rng_n(n: u32) -> u32 {
-    thread_local! {
-        static THREAD_RNG: FastRand = FastRand::new(crate::loom::rand::seed());
-    }
-
-    THREAD_RNG.with(|rng| rng.fastrand_n(n))
-}
diff --git a/vendor/tokio/src/util/rand/rt.rs b/vendor/tokio/src/util/rand/rt.rs
new file mode 100644
index 000000000..6584ba4f2
--- /dev/null
+++ b/vendor/tokio/src/util/rand/rt.rs
@@ -0,0 +1,61 @@
+use super::{FastRand, RngSeed};
+
+use std::sync::Mutex;
+
+/// A deterministic generator for seeds (and other generators).
+///
+/// Given the same initial seed, the generator will output the same sequence of seeds.
+///
+/// Since the seed generator will be kept in a runtime handle, we need to wrap `FastRand`
+/// in a Mutex to make it thread safe. Different to the `FastRand` that we keep in a
+/// thread local store, the expectation is that seed generation will not need to happen
+/// very frequently, so the cost of the mutex should be minimal.
+#[derive(Debug)]
+pub(crate) struct RngSeedGenerator {
+    /// Internal state for the seed generator. We keep it in a Mutex so that we can safely
+    /// use it across multiple threads.
+    state: Mutex<FastRand>,
+}
+
+impl RngSeedGenerator {
+    /// Returns a new generator from the provided seed.
+    pub(crate) fn new(seed: RngSeed) -> Self {
+        Self {
+            state: Mutex::new(FastRand::from_seed(seed)),
+        }
+    }
+
+    /// Returns the next seed in the sequence.
+    pub(crate) fn next_seed(&self) -> RngSeed {
+        let mut rng = self
+            .state
+            .lock()
+            .expect("RNG seed generator is internally corrupt");
+
+        let s = rng.fastrand();
+        let r = rng.fastrand();
+
+        RngSeed::from_pair(s, r)
+    }
+
+    /// Directly creates a generator using the next seed.
+    pub(crate) fn next_generator(&self) -> Self {
+        RngSeedGenerator::new(self.next_seed())
+    }
+}
+
+impl FastRand {
+    /// Replaces the state of the random number generator with the provided seed, returning
+    /// the seed that represents the previous state of the random number generator.
+    ///
+    /// The random number generator will become equivalent to one created with
+    /// the same seed.
+    pub(crate) fn replace_seed(&mut self, seed: RngSeed) -> RngSeed {
+        let old_seed = RngSeed::from_pair(self.one, self.two);
+
+        self.one = seed.s;
+        self.two = seed.r;
+
+        old_seed
+    }
+}
diff --git a/vendor/tokio/src/util/rand/rt_unstable.rs b/vendor/tokio/src/util/rand/rt_unstable.rs
new file mode 100644
index 000000000..3a8613eb0
--- /dev/null
+++ b/vendor/tokio/src/util/rand/rt_unstable.rs
@@ -0,0 +1,20 @@
+use super::RngSeed;
+
+use std::collections::hash_map::DefaultHasher;
+use std::hash::Hasher;
+
+impl RngSeed {
+    /// Generates a seed from the provided byte slice.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// # use tokio::runtime::RngSeed;
+    /// let seed = RngSeed::from_bytes(b"make me a seed");
+    /// ```
+    pub fn from_bytes(bytes: &[u8]) -> Self {
+        let mut hasher = DefaultHasher::default();
+        hasher.write(bytes);
+        Self::from_u64(hasher.finish())
+    }
+}
diff --git a/vendor/tokio/src/util/rc_cell.rs b/vendor/tokio/src/util/rc_cell.rs
new file mode 100644
index 000000000..447249268
--- /dev/null
+++ b/vendor/tokio/src/util/rc_cell.rs
@@ -0,0 +1,57 @@
+use crate::loom::cell::UnsafeCell;
+
+use std::rc::Rc;
+
+/// This is exactly like `Cell<Option<Rc<T>>>`, except that it provides a `get`
+/// method even though `Rc` is not `Copy`.
+pub(crate) struct RcCell<T> {
+    inner: UnsafeCell<Option<Rc<T>>>,
+}
+
+impl<T> RcCell<T> {
+    #[cfg(not(all(loom, test)))]
+    pub(crate) const fn new() -> Self {
+        Self {
+            inner: UnsafeCell::new(None),
+        }
+    }
+
+    // The UnsafeCell in loom does not have a const `new` fn.
+    #[cfg(all(loom, test))]
+    pub(crate) fn new() -> Self {
+        Self {
+            inner: UnsafeCell::new(None),
+        }
+    }
+
+    /// Safety: This method may not be called recursively.
+    #[inline]
+    unsafe fn with_inner<F, R>(&self, f: F) -> R
+    where
+        F: FnOnce(&mut Option<Rc<T>>) -> R,
+    {
+        // safety: This type is not Sync, so concurrent calls of this method
+        // cannot happen. Furthermore, the caller guarantees that the method is
+        // not called recursively. Finally, this is the only place that can
+        // create mutable references to the inner Rc. This ensures that any
+        // mutable references created here are exclusive.
+        self.inner.with_mut(|ptr| f(&mut *ptr))
+    }
+
+    pub(crate) fn get(&self) -> Option<Rc<T>> {
+        // safety: The `Rc::clone` method will not call any unknown user-code,
+        // so it will not result in a recursive call to `with_inner`.
+        unsafe { self.with_inner(|rc| rc.clone()) }
+    }
+
+    pub(crate) fn replace(&self, val: Option<Rc<T>>) -> Option<Rc<T>> {
+        // safety: No destructors or other unknown user-code will run inside the
+        // `with_inner` call, so no recursive call to `with_inner` can happen.
+        unsafe { self.with_inner(|rc| std::mem::replace(rc, val)) }
+    }
+
+    pub(crate) fn set(&self, val: Option<Rc<T>>) {
+        let old = self.replace(val);
+        drop(old);
+    }
+}
diff --git a/vendor/tokio/src/util/slab.rs b/vendor/tokio/src/util/slab.rs
index 2ddaa6c74..cc1208ebe 100644
--- a/vendor/tokio/src/util/slab.rs
+++ b/vendor/tokio/src/util/slab.rs
@@ -85,11 +85,11 @@ pub(crate) struct Address(usize);
 
 /// An entry in the slab.
 pub(crate) trait Entry: Default {
-    /// Reset the entry's value and track the generation.
+    /// Resets the entry's value and track the generation.
     fn reset(&self);
 }
 
-/// A reference to a value stored in the slab
+/// A reference to a value stored in the slab.
 pub(crate) struct Ref<T> {
     value: *const Value<T>,
 }
@@ -101,9 +101,9 @@ const NUM_PAGES: usize = 19;
 const PAGE_INITIAL_SIZE: usize = 32;
 const PAGE_INDEX_SHIFT: u32 = PAGE_INITIAL_SIZE.trailing_zeros() + 1;
 
-/// A page in the slab
+/// A page in the slab.
 struct Page<T> {
-    /// Slots
+    /// Slots.
     slots: Mutex<Slots<T>>,
 
     // Number of slots currently being used. This is not guaranteed to be up to
@@ -116,7 +116,7 @@ struct Page<T> {
     // The number of slots the page can hold.
     len: usize,
 
-    // Length of all previous pages combined
+    // Length of all previous pages combined.
     prev_len: usize,
 }
 
@@ -128,9 +128,9 @@ struct CachedPage<T> {
     init: usize,
 }
 
-/// Page state
+/// Page state.
 struct Slots<T> {
-    /// Slots
+    /// Slots.
     slots: Vec<Slot<T>>,
 
     head: usize,
@@ -157,11 +157,17 @@ struct Slot<T> {
 
     /// Next entry in the free list.
     next: u32,
+
+    /// Makes miri happy by making mutable references not take exclusive access.
+    ///
+    /// Could probably also be fixed by replacing `slots` with a raw-pointer
+    /// based equivalent.
+    _pin: std::marker::PhantomPinned,
 }
 
-/// Value paired with a reference to the page
+/// Value paired with a reference to the page.
 struct Value<T> {
-    /// Value stored in the value
+    /// Value stored in the value.
     value: T,
 
     /// Pointer to the page containing the slot.
@@ -171,7 +177,7 @@ struct Value<T> {
 }
 
 impl<T> Slab<T> {
-    /// Create a new, empty, slab
+    /// Create a new, empty, slab.
     pub(crate) fn new() -> Slab<T> {
         // Initializing arrays is a bit annoying. Instead of manually writing
         // out an array and every single entry, `Default::default()` is used to
@@ -409,7 +415,7 @@ impl<T: Entry> Page<T> {
             slot.value.with(|ptr| unsafe { (*ptr).value.reset() });
 
             // Return a reference to the slot
-            Some((me.addr(idx), slot.gen_ref(me)))
+            Some((me.addr(idx), locked.gen_ref(idx, me)))
         } else if me.len == locked.slots.len() {
             // The page is full
             None
@@ -428,9 +434,10 @@ impl<T: Entry> Page<T> {
             locked.slots.push(Slot {
                 value: UnsafeCell::new(Value {
                     value: Default::default(),
-                    page: &**me as *const _,
+                    page: Arc::as_ptr(me),
                 }),
                 next: 0,
+                _pin: std::marker::PhantomPinned,
             });
 
             // Increment the head to indicate the free stack is empty
@@ -443,7 +450,7 @@ impl<T: Entry> Page<T> {
 
             debug_assert_eq!(locked.slots.len(), locked.head);
 
-            Some((me.addr(idx), locked.slots[idx].gen_ref(me)))
+            Some((me.addr(idx), locked.gen_ref(idx, me)))
         }
     }
 }
@@ -455,7 +462,7 @@ impl<T> Page<T> {
         addr.0 - self.prev_len
     }
 
-    /// Returns the address for the given slot
+    /// Returns the address for the given slot.
     fn addr(&self, slot: usize) -> Address {
         Address(slot + self.prev_len)
     }
@@ -478,7 +485,7 @@ impl<T> Default for Page<T> {
 }
 
 impl<T> Page<T> {
-    /// Release a slot into the page's free list
+    /// Release a slot into the page's free list.
     fn release(&self, value: *const Value<T>) {
         let mut locked = self.slots.lock();
 
@@ -492,7 +499,7 @@ impl<T> Page<T> {
 }
 
 impl<T> CachedPage<T> {
-    /// Refresh the cache
+    /// Refreshes the cache.
     fn refresh(&mut self, page: &Page<T>) {
         let slots = page.slots.lock();
 
@@ -502,7 +509,7 @@ impl<T> CachedPage<T> {
         }
     }
 
-    // Get a value by index
+    /// Gets a value by index.
     fn get(&self, idx: usize) -> &T {
         assert!(idx < self.init);
 
@@ -544,39 +551,35 @@ impl<T> Slots<T> {
     fn index_for(&self, slot: *const Value<T>) -> usize {
         use std::mem;
 
-        let base = &self.slots[0] as *const _ as usize;
-
-        assert!(base != 0, "page is unallocated");
+        assert_ne!(self.slots.capacity(), 0, "page is unallocated");
 
+        let base = self.slots.as_ptr() as usize;
         let slot = slot as usize;
         let width = mem::size_of::<Slot<T>>();
 
         assert!(slot >= base, "unexpected pointer");
 
         let idx = (slot - base) / width;
-        assert!(idx < self.slots.len() as usize);
+        assert!(idx < self.slots.len());
 
         idx
     }
-}
 
-impl<T: Entry> Slot<T> {
-    /// Generates a `Ref` for the slot. This involves bumping the page's ref count.
-    fn gen_ref(&self, page: &Arc<Page<T>>) -> Ref<T> {
-        // The ref holds a ref on the page. The `Arc` is forgotten here and is
-        // resurrected in `release` when the `Ref` is dropped. By avoiding to
-        // hold on to an explicit `Arc` value, the struct size of `Ref` is
-        // reduced.
+    /// Generates a `Ref` for the slot at the given index. This involves bumping the page's ref count.
+    fn gen_ref(&self, idx: usize, page: &Arc<Page<T>>) -> Ref<T> {
+        assert!(idx < self.slots.len());
         mem::forget(page.clone());
-        let slot = self as *const Slot<T>;
-        let value = slot as *const Value<T>;
+
+        let vec_ptr = self.slots.as_ptr();
+        let slot: *const Slot<T> = unsafe { vec_ptr.add(idx) };
+        let value: *const Value<T> = slot as *const Value<T>;
 
         Ref { value }
     }
 }
 
 impl<T> Value<T> {
-    // Release the slot, returning the `Arc<Page<T>>` logically owned by the ref.
+    /// Releases the slot, returning the `Arc<Page<T>>` logically owned by the ref.
     fn release(&self) -> Arc<Page<T>> {
         // Safety: called by `Ref`, which owns an `Arc<Page<T>>` instance.
         let page = unsafe { Arc::from_raw(self.page) };
@@ -691,11 +694,13 @@ mod test {
 
     #[test]
     fn insert_many() {
+        const MANY: usize = normal_or_miri(10_000, 50);
+
         let mut slab = Slab::<Foo>::new();
         let alloc = slab.allocator();
         let mut entries = vec![];
 
-        for i in 0..10_000 {
+        for i in 0..MANY {
             let (addr, val) = alloc.allocate().unwrap();
             val.id.store(i, SeqCst);
             entries.push((addr, val));
@@ -708,15 +713,15 @@ mod test {
 
         entries.clear();
 
-        for i in 0..10_000 {
+        for i in 0..MANY {
             let (addr, val) = alloc.allocate().unwrap();
-            val.id.store(10_000 - i, SeqCst);
+            val.id.store(MANY - i, SeqCst);
             entries.push((addr, val));
         }
 
         for (i, (addr, v)) in entries.iter().enumerate() {
-            assert_eq!(10_000 - i, v.id.load(SeqCst));
-            assert_eq!(10_000 - i, slab.get(*addr).unwrap().id.load(SeqCst));
+            assert_eq!(MANY - i, v.id.load(SeqCst));
+            assert_eq!(MANY - i, slab.get(*addr).unwrap().id.load(SeqCst));
         }
     }
 
@@ -726,7 +731,7 @@ mod test {
         let alloc = slab.allocator();
         let mut entries = vec![];
 
-        for i in 0..10_000 {
+        for i in 0..normal_or_miri(10_000, 100) {
             let (addr, val) = alloc.allocate().unwrap();
             val.id.store(i, SeqCst);
             entries.push((addr, val));
@@ -734,7 +739,7 @@ mod test {
 
         for _ in 0..10 {
             // Drop 1000 in reverse
-            for _ in 0..1_000 {
+            for _ in 0..normal_or_miri(1_000, 10) {
                 entries.pop();
             }
 
@@ -753,7 +758,7 @@ mod test {
         let mut entries1 = vec![];
         let mut entries2 = vec![];
 
-        for i in 0..10_000 {
+        for i in 0..normal_or_miri(10_000, 100) {
             let (addr, val) = alloc.allocate().unwrap();
             val.id.store(i, SeqCst);
 
@@ -771,6 +776,14 @@ mod test {
         }
     }
 
+    const fn normal_or_miri(normal: usize, miri: usize) -> usize {
+        if cfg!(miri) {
+            miri
+        } else {
+            normal
+        }
+    }
+
     #[test]
     fn compact_all() {
         let mut slab = Slab::<Foo>::new();
@@ -780,7 +793,7 @@ mod test {
         for _ in 0..2 {
             entries.clear();
 
-            for i in 0..10_000 {
+            for i in 0..normal_or_miri(10_000, 100) {
                 let (addr, val) = alloc.allocate().unwrap();
                 val.id.store(i, SeqCst);
 
@@ -808,7 +821,7 @@ mod test {
         let alloc = slab.allocator();
         let mut entries = vec![];
 
-        for _ in 0..5 {
+        for _ in 0..normal_or_miri(5, 2) {
             entries.clear();
 
             // Allocate a few pages + 1
diff --git a/vendor/tokio/src/util/sync_wrapper.rs b/vendor/tokio/src/util/sync_wrapper.rs
new file mode 100644
index 000000000..5ffc8f96b
--- /dev/null
+++ b/vendor/tokio/src/util/sync_wrapper.rs
@@ -0,0 +1,26 @@
+//! This module contains a type that can make `Send + !Sync` types `Sync` by
+//! disallowing all immutable access to the value.
+//!
+//! A similar primitive is provided in the `sync_wrapper` crate.
+
+pub(crate) struct SyncWrapper<T> {
+    value: T,
+}
+
+// safety: The SyncWrapper being send allows you to send the inner value across
+// thread boundaries.
+unsafe impl<T: Send> Send for SyncWrapper<T> {}
+
+// safety: An immutable reference to a SyncWrapper is useless, so moving such an
+// immutable reference across threads is safe.
+unsafe impl<T> Sync for SyncWrapper<T> {}
+
+impl<T> SyncWrapper<T> {
+    pub(crate) fn new(value: T) -> Self {
+        Self { value }
+    }
+
+    pub(crate) fn into_inner(self) -> T {
+        self.value
+    }
+}
diff --git a/vendor/tokio/src/util/trace.rs b/vendor/tokio/src/util/trace.rs
index c51a5a72b..76e8a6cbf 100644
--- a/vendor/tokio/src/util/trace.rs
+++ b/vendor/tokio/src/util/trace.rs
@@ -1,37 +1,98 @@
 cfg_trace! {
     cfg_rt! {
+        use core::{
+            pin::Pin,
+            task::{Context, Poll},
+        };
+        use pin_project_lite::pin_project;
+        use std::future::Future;
         pub(crate) use tracing::instrument::Instrumented;
 
         #[inline]
-        #[cfg_attr(tokio_track_caller, track_caller)]
-        pub(crate) fn task<F>(task: F, kind: &'static str, name: Option<&str>) -> Instrumented<F> {
+        #[track_caller]
+        pub(crate) fn task<F>(task: F, kind: &'static str, name: Option<&str>, id: u64) -> Instrumented<F> {
             use tracing::instrument::Instrument;
-            #[cfg(tokio_track_caller)]
             let location = std::panic::Location::caller();
-            #[cfg(tokio_track_caller)]
             let span = tracing::trace_span!(
                 target: "tokio::task",
-                "task",
+                "runtime.spawn",
                 %kind,
-                spawn.location = %format_args!("{}:{}:{}", location.file(), location.line(), location.column()),
-                task.name = %name.unwrap_or_default()
-            );
-            #[cfg(not(tokio_track_caller))]
-            let span = tracing::trace_span!(
-                target: "tokio::task",
-                "task",
-                %kind,
-                task.name = %name.unwrap_or_default()
+                task.name = %name.unwrap_or_default(),
+                task.id = id,
+                loc.file = location.file(),
+                loc.line = location.line(),
+                loc.col = location.column(),
             );
             task.instrument(span)
         }
+
+        pub(crate) fn async_op<P,F>(inner: P, resource_span: tracing::Span, source: &str, poll_op_name: &'static str, inherits_child_attrs: bool) -> InstrumentedAsyncOp<F>
+        where P: FnOnce() -> F {
+            resource_span.in_scope(|| {
+                let async_op_span = tracing::trace_span!("runtime.resource.async_op", source = source, inherits_child_attrs = inherits_child_attrs);
+                let enter = async_op_span.enter();
+                let async_op_poll_span = tracing::trace_span!("runtime.resource.async_op.poll");
+                let inner = inner();
+                drop(enter);
+                let tracing_ctx = AsyncOpTracingCtx {
+                    async_op_span,
+                    async_op_poll_span,
+                    resource_span: resource_span.clone(),
+                };
+                InstrumentedAsyncOp {
+                    inner,
+                    tracing_ctx,
+                    poll_op_name,
+                }
+            })
+        }
+
+        #[derive(Debug, Clone)]
+        pub(crate) struct AsyncOpTracingCtx {
+            pub(crate) async_op_span: tracing::Span,
+            pub(crate) async_op_poll_span: tracing::Span,
+            pub(crate) resource_span: tracing::Span,
+        }
+
+
+        pin_project! {
+            #[derive(Debug, Clone)]
+            pub(crate) struct InstrumentedAsyncOp<F> {
+                #[pin]
+                pub(crate) inner: F,
+                pub(crate) tracing_ctx: AsyncOpTracingCtx,
+                pub(crate) poll_op_name: &'static str
+            }
+        }
+
+        impl<F: Future> Future for InstrumentedAsyncOp<F> {
+            type Output = F::Output;
+
+            fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+                let this = self.project();
+                let poll_op_name = &*this.poll_op_name;
+                let _res_enter = this.tracing_ctx.resource_span.enter();
+                let _async_op_enter = this.tracing_ctx.async_op_span.enter();
+                let _async_op_poll_enter = this.tracing_ctx.async_op_poll_span.enter();
+                trace_poll_op!(poll_op_name, this.inner.poll(cx))
+            }
+        }
+    }
+}
+cfg_time! {
+    #[track_caller]
+    pub(crate) fn caller_location() -> Option<&'static std::panic::Location<'static>> {
+        #[cfg(all(tokio_unstable, feature = "tracing"))]
+        return Some(std::panic::Location::caller());
+        #[cfg(not(all(tokio_unstable, feature = "tracing")))]
+        None
     }
 }
 
 cfg_not_trace! {
     cfg_rt! {
         #[inline]
-        pub(crate) fn task<F>(task: F, _: &'static str, _name: Option<&str>) -> F {
+        pub(crate) fn task<F>(task: F, _: &'static str, _name: Option<&str>, _: u64) -> F {
             // nop
             task
         }
diff --git a/vendor/tokio/src/util/wake.rs b/vendor/tokio/src/util/wake.rs
index 57739371d..5526cbc63 100644
--- a/vendor/tokio/src/util/wake.rs
+++ b/vendor/tokio/src/util/wake.rs
@@ -1,15 +1,16 @@
+use crate::loom::sync::Arc;
+
 use std::marker::PhantomData;
 use std::mem::ManuallyDrop;
 use std::ops::Deref;
-use std::sync::Arc;
 use std::task::{RawWaker, RawWakerVTable, Waker};
 
-/// Simplified waking interface based on Arcs
-pub(crate) trait Wake: Send + Sync {
-    /// Wake by value
-    fn wake(self: Arc<Self>);
+/// Simplified waking interface based on Arcs.
+pub(crate) trait Wake: Send + Sync + Sized + 'static {
+    /// Wake by value.
+    fn wake(arc_self: Arc<Self>);
 
-    /// Wake by reference
+    /// Wake by reference.
     fn wake_by_ref(arc_self: &Arc<Self>);
 }
 
@@ -30,7 +31,7 @@ impl Deref for WakerRef<'_> {
 
 /// Creates a reference to a `Waker` from a reference to `Arc<impl Wake>`.
 pub(crate) fn waker_ref<W: Wake>(wake: &Arc<W>) -> WakerRef<'_> {
-    let ptr = &**wake as *const _ as *const ();
+    let ptr = Arc::as_ptr(wake) as *const ();
 
     let waker = unsafe { Waker::from_raw(RawWaker::new(ptr, waker_vtable::<W>())) };
 
diff --git a/vendor/tokio/src/util/wake_list.rs b/vendor/tokio/src/util/wake_list.rs
new file mode 100644
index 000000000..aa569dd17
--- /dev/null
+++ b/vendor/tokio/src/util/wake_list.rs
@@ -0,0 +1,53 @@
+use core::mem::MaybeUninit;
+use core::ptr;
+use std::task::Waker;
+
+const NUM_WAKERS: usize = 32;
+
+pub(crate) struct WakeList {
+    inner: [MaybeUninit<Waker>; NUM_WAKERS],
+    curr: usize,
+}
+
+impl WakeList {
+    pub(crate) fn new() -> Self {
+        Self {
+            inner: unsafe {
+                // safety: Create an uninitialized array of `MaybeUninit`. The
+                // `assume_init` is safe because the type we are claiming to
+                // have initialized here is a bunch of `MaybeUninit`s, which do
+                // not require initialization.
+                MaybeUninit::uninit().assume_init()
+            },
+            curr: 0,
+        }
+    }
+
+    #[inline]
+    pub(crate) fn can_push(&self) -> bool {
+        self.curr < NUM_WAKERS
+    }
+
+    pub(crate) fn push(&mut self, val: Waker) {
+        debug_assert!(self.can_push());
+
+        self.inner[self.curr] = MaybeUninit::new(val);
+        self.curr += 1;
+    }
+
+    pub(crate) fn wake_all(&mut self) {
+        assert!(self.curr <= NUM_WAKERS);
+        while self.curr > 0 {
+            self.curr -= 1;
+            let waker = unsafe { ptr::read(self.inner[self.curr].as_mut_ptr()) };
+            waker.wake();
+        }
+    }
+}
+
+impl Drop for WakeList {
+    fn drop(&mut self) {
+        let slice = ptr::slice_from_raw_parts_mut(self.inner.as_mut_ptr() as *mut Waker, self.curr);
+        unsafe { ptr::drop_in_place(slice) };
+    }
+}
diff --git a/vendor/tokio/tests/_require_full.rs b/vendor/tokio/tests/_require_full.rs
index 98455bede..4b9698afe 100644
--- a/vendor/tokio/tests/_require_full.rs
+++ b/vendor/tokio/tests/_require_full.rs
@@ -1,2 +1,8 @@
-#![cfg(not(feature = "full"))]
+#[cfg(not(any(feature = "full", tokio_wasm)))]
 compile_error!("run main Tokio tests with `--features full`");
+
+// CI sets `--cfg tokio_no_parking_lot` when trying to run tests with
+// `parking_lot` disabled. This check prevents "silent failure" if `parking_lot`
+// accidentally gets enabled.
+#[cfg(all(tokio_no_parking_lot, feature = "parking_lot"))]
+compile_error!("parking_lot feature enabled when it should not be");
diff --git a/vendor/tokio/tests/async_send_sync.rs b/vendor/tokio/tests/async_send_sync.rs
index 01e608186..32c03a54b 100644
--- a/vendor/tokio/tests/async_send_sync.rs
+++ b/vendor/tokio/tests/async_send_sync.rs
@@ -4,13 +4,30 @@
 
 use std::cell::Cell;
 use std::future::Future;
-use std::io::{Cursor, SeekFrom};
+use std::io::SeekFrom;
 use std::net::SocketAddr;
 use std::pin::Pin;
 use std::rc::Rc;
 use tokio::net::TcpStream;
 use tokio::time::{Duration, Instant};
 
+// The names of these structs behaves better when sorted.
+// Send: Yes, Sync: Yes
+#[derive(Clone)]
+struct YY {}
+
+// Send: Yes, Sync: No
+#[derive(Clone)]
+struct YN {
+    _value: Cell<u8>,
+}
+
+// Send: No, Sync: No
+#[derive(Clone)]
+struct NN {
+    _value: Rc<u8>,
+}
+
 #[allow(dead_code)]
 type BoxFutureSync<T> = std::pin::Pin<Box<dyn std::future::Future<Output = T> + Send + Sync>>;
 #[allow(dead_code)]
@@ -19,11 +36,11 @@ type BoxFutureSend<T> = std::pin::Pin<Box<dyn std::future::Future<Output = T> +
 type BoxFuture<T> = std::pin::Pin<Box<dyn std::future::Future<Output = T>>>;
 
 #[allow(dead_code)]
-type BoxAsyncRead = std::pin::Pin<Box<dyn tokio::io::AsyncBufRead>>;
+type BoxAsyncRead = std::pin::Pin<Box<dyn tokio::io::AsyncBufRead + Send + Sync>>;
 #[allow(dead_code)]
-type BoxAsyncSeek = std::pin::Pin<Box<dyn tokio::io::AsyncSeek>>;
+type BoxAsyncSeek = std::pin::Pin<Box<dyn tokio::io::AsyncSeek + Send + Sync>>;
 #[allow(dead_code)]
-type BoxAsyncWrite = std::pin::Pin<Box<dyn tokio::io::AsyncWrite>>;
+type BoxAsyncWrite = std::pin::Pin<Box<dyn tokio::io::AsyncWrite + Send + Sync>>;
 
 #[allow(dead_code)]
 fn require_send<T: Send>(_t: &T) {}
@@ -59,310 +76,671 @@ macro_rules! into_todo {
         x
     }};
 }
-macro_rules! assert_value {
-    ($type:ty: Send & Sync) => {
-        #[allow(unreachable_code)]
-        #[allow(unused_variables)]
-        const _: fn() = || {
-            let f: $type = todo!();
-            require_send(&f);
-            require_sync(&f);
-        };
-    };
-    ($type:ty: !Send & Sync) => {
-        #[allow(unreachable_code)]
-        #[allow(unused_variables)]
-        const _: fn() = || {
-            let f: $type = todo!();
-            AmbiguousIfSend::some_item(&f);
-            require_sync(&f);
-        };
-    };
-    ($type:ty: Send & !Sync) => {
-        #[allow(unreachable_code)]
-        #[allow(unused_variables)]
-        const _: fn() = || {
-            let f: $type = todo!();
-            require_send(&f);
-            AmbiguousIfSync::some_item(&f);
-        };
-    };
-    ($type:ty: !Send & !Sync) => {
-        #[allow(unreachable_code)]
-        #[allow(unused_variables)]
-        const _: fn() = || {
-            let f: $type = todo!();
-            AmbiguousIfSend::some_item(&f);
-            AmbiguousIfSync::some_item(&f);
-        };
+
+macro_rules! async_assert_fn_send {
+    (Send & $(!)?Sync & $(!)?Unpin, $value:expr) => {
+        require_send(&$value);
     };
-    ($type:ty: Unpin) => {
-        #[allow(unreachable_code)]
-        #[allow(unused_variables)]
-        const _: fn() = || {
-            let f: $type = todo!();
-            require_unpin(&f);
-        };
+    (!Send & $(!)?Sync & $(!)?Unpin, $value:expr) => {
+        AmbiguousIfSend::some_item(&$value);
     };
 }
-macro_rules! async_assert_fn {
-    ($($f:ident $(< $($generic:ty),* > )? )::+($($arg:ty),*): Send & Sync) => {
-        #[allow(unreachable_code)]
-        #[allow(unused_variables)]
-        const _: fn() = || {
-            let f = $($f $(::<$($generic),*>)? )::+( $( into_todo!($arg) ),* );
-            require_send(&f);
-            require_sync(&f);
-        };
+macro_rules! async_assert_fn_sync {
+    ($(!)?Send & Sync & $(!)?Unpin, $value:expr) => {
+        require_sync(&$value);
     };
-    ($($f:ident $(< $($generic:ty),* > )? )::+($($arg:ty),*): Send & !Sync) => {
-        #[allow(unreachable_code)]
-        #[allow(unused_variables)]
-        const _: fn() = || {
-            let f = $($f $(::<$($generic),*>)? )::+( $( into_todo!($arg) ),* );
-            require_send(&f);
-            AmbiguousIfSync::some_item(&f);
-        };
+    ($(!)?Send & !Sync & $(!)?Unpin, $value:expr) => {
+        AmbiguousIfSync::some_item(&$value);
     };
-    ($($f:ident $(< $($generic:ty),* > )? )::+($($arg:ty),*): !Send & Sync) => {
-        #[allow(unreachable_code)]
-        #[allow(unused_variables)]
-        const _: fn() = || {
-            let f = $($f $(::<$($generic),*>)? )::+( $( into_todo!($arg) ),* );
-            AmbiguousIfSend::some_item(&f);
-            require_sync(&f);
-        };
+}
+macro_rules! async_assert_fn_unpin {
+    ($(!)?Send & $(!)?Sync & Unpin, $value:expr) => {
+        require_unpin(&$value);
     };
-    ($($f:ident $(< $($generic:ty),* > )? )::+($($arg:ty),*): !Send & !Sync) => {
-        #[allow(unreachable_code)]
-        #[allow(unused_variables)]
-        const _: fn() = || {
-            let f = $($f $(::<$($generic),*>)? )::+( $( into_todo!($arg) ),* );
-            AmbiguousIfSend::some_item(&f);
-            AmbiguousIfSync::some_item(&f);
-        };
+    ($(!)?Send & $(!)?Sync & !Unpin, $value:expr) => {
+        AmbiguousIfUnpin::some_item(&$value);
     };
-    ($($f:ident $(< $($generic:ty),* > )? )::+($($arg:ty),*): !Unpin) => {
+}
+
+macro_rules! async_assert_fn {
+    ($($f:ident $(< $($generic:ty),* > )? )::+($($arg:ty),*): $($tok:tt)*) => {
         #[allow(unreachable_code)]
         #[allow(unused_variables)]
         const _: fn() = || {
             let f = $($f $(::<$($generic),*>)? )::+( $( into_todo!($arg) ),* );
-            AmbiguousIfUnpin::some_item(&f);
+            async_assert_fn_send!($($tok)*, f);
+            async_assert_fn_sync!($($tok)*, f);
+            async_assert_fn_unpin!($($tok)*, f);
         };
     };
-    ($($f:ident $(< $($generic:ty),* > )? )::+($($arg:ty),*): Unpin) => {
+}
+macro_rules! assert_value {
+    ($type:ty: $($tok:tt)*) => {
         #[allow(unreachable_code)]
         #[allow(unused_variables)]
         const _: fn() = || {
-            let f = $($f $(::<$($generic),*>)? )::+( $( into_todo!($arg) ),* );
-            require_unpin(&f);
+            let f: $type = todo!();
+            async_assert_fn_send!($($tok)*, f);
+            async_assert_fn_sync!($($tok)*, f);
+            async_assert_fn_unpin!($($tok)*, f);
         };
     };
 }
 
-async_assert_fn!(tokio::io::copy(&mut TcpStream, &mut TcpStream): Send & Sync);
-async_assert_fn!(tokio::io::empty(): Send & Sync);
-async_assert_fn!(tokio::io::repeat(u8): Send & Sync);
-async_assert_fn!(tokio::io::sink(): Send & Sync);
-async_assert_fn!(tokio::io::split(TcpStream): Send & Sync);
-async_assert_fn!(tokio::io::stderr(): Send & Sync);
-async_assert_fn!(tokio::io::stdin(): Send & Sync);
-async_assert_fn!(tokio::io::stdout(): Send & Sync);
-async_assert_fn!(tokio::io::Split<Cursor<Vec<u8>>>::next_segment(_): Send & Sync);
-
-async_assert_fn!(tokio::fs::canonicalize(&str): Send & Sync);
-async_assert_fn!(tokio::fs::copy(&str, &str): Send & Sync);
-async_assert_fn!(tokio::fs::create_dir(&str): Send & Sync);
-async_assert_fn!(tokio::fs::create_dir_all(&str): Send & Sync);
-async_assert_fn!(tokio::fs::hard_link(&str, &str): Send & Sync);
-async_assert_fn!(tokio::fs::metadata(&str): Send & Sync);
-async_assert_fn!(tokio::fs::read(&str): Send & Sync);
-async_assert_fn!(tokio::fs::read_dir(&str): Send & Sync);
-async_assert_fn!(tokio::fs::read_link(&str): Send & Sync);
-async_assert_fn!(tokio::fs::read_to_string(&str): Send & Sync);
-async_assert_fn!(tokio::fs::remove_dir(&str): Send & Sync);
-async_assert_fn!(tokio::fs::remove_dir_all(&str): Send & Sync);
-async_assert_fn!(tokio::fs::remove_file(&str): Send & Sync);
-async_assert_fn!(tokio::fs::rename(&str, &str): Send & Sync);
-async_assert_fn!(tokio::fs::set_permissions(&str, std::fs::Permissions): Send & Sync);
-async_assert_fn!(tokio::fs::symlink_metadata(&str): Send & Sync);
-async_assert_fn!(tokio::fs::write(&str, Vec<u8>): Send & Sync);
-async_assert_fn!(tokio::fs::ReadDir::next_entry(_): Send & Sync);
-async_assert_fn!(tokio::fs::OpenOptions::open(_, &str): Send & Sync);
-async_assert_fn!(tokio::fs::DirEntry::metadata(_): Send & Sync);
-async_assert_fn!(tokio::fs::DirEntry::file_type(_): Send & Sync);
-
-async_assert_fn!(tokio::fs::File::open(&str): Send & Sync);
-async_assert_fn!(tokio::fs::File::create(&str): Send & Sync);
-async_assert_fn!(tokio::fs::File::sync_all(_): Send & Sync);
-async_assert_fn!(tokio::fs::File::sync_data(_): Send & Sync);
-async_assert_fn!(tokio::fs::File::set_len(_, u64): Send & Sync);
-async_assert_fn!(tokio::fs::File::metadata(_): Send & Sync);
-async_assert_fn!(tokio::fs::File::try_clone(_): Send & Sync);
-async_assert_fn!(tokio::fs::File::into_std(_): Send & Sync);
-async_assert_fn!(tokio::fs::File::set_permissions(_, std::fs::Permissions): Send & Sync);
-
-async_assert_fn!(tokio::net::lookup_host(SocketAddr): Send & Sync);
-async_assert_fn!(tokio::net::TcpListener::bind(SocketAddr): Send & Sync);
-async_assert_fn!(tokio::net::TcpListener::accept(_): Send & Sync);
-async_assert_fn!(tokio::net::TcpStream::connect(SocketAddr): Send & Sync);
-async_assert_fn!(tokio::net::TcpStream::peek(_, &mut [u8]): Send & Sync);
-async_assert_fn!(tokio::net::tcp::ReadHalf::peek(_, &mut [u8]): Send & Sync);
-async_assert_fn!(tokio::net::UdpSocket::bind(SocketAddr): Send & Sync);
-async_assert_fn!(tokio::net::UdpSocket::connect(_, SocketAddr): Send & Sync);
-async_assert_fn!(tokio::net::UdpSocket::send(_, &[u8]): Send & Sync);
-async_assert_fn!(tokio::net::UdpSocket::recv(_, &mut [u8]): Send & Sync);
-async_assert_fn!(tokio::net::UdpSocket::send_to(_, &[u8], SocketAddr): Send & Sync);
-async_assert_fn!(tokio::net::UdpSocket::recv_from(_, &mut [u8]): Send & Sync);
+macro_rules! cfg_not_wasi {
+    ($($item:item)*) => {
+        $(
+            #[cfg(not(tokio_wasi))]
+            $item
+        )*
+    }
+}
+
+// Manually re-implementation of `async_assert_fn` for `poll_fn`. The macro
+// doesn't work for this particular case because constructing the closure
+// is too complicated.
+const _: fn() = || {
+    let pinned = std::marker::PhantomPinned;
+    let f = tokio::macros::support::poll_fn(move |_| {
+        // Use `pinned` to take ownership of it.
+        let _ = &pinned;
+        std::task::Poll::Pending::<()>
+    });
+    require_send(&f);
+    require_sync(&f);
+    AmbiguousIfUnpin::some_item(&f);
+};
+
+cfg_not_wasi! {
+    mod fs {
+        use super::*;
+        assert_value!(tokio::fs::DirBuilder: Send & Sync & Unpin);
+        assert_value!(tokio::fs::DirEntry: Send & Sync & Unpin);
+        assert_value!(tokio::fs::File: Send & Sync & Unpin);
+        assert_value!(tokio::fs::OpenOptions: Send & Sync & Unpin);
+        assert_value!(tokio::fs::ReadDir: Send & Sync & Unpin);
+
+        async_assert_fn!(tokio::fs::canonicalize(&str): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::fs::copy(&str, &str): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::fs::create_dir(&str): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::fs::create_dir_all(&str): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::fs::hard_link(&str, &str): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::fs::metadata(&str): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::fs::read(&str): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::fs::read_dir(&str): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::fs::read_link(&str): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::fs::read_to_string(&str): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::fs::remove_dir(&str): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::fs::remove_dir_all(&str): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::fs::remove_file(&str): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::fs::rename(&str, &str): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::fs::set_permissions(&str, std::fs::Permissions): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::fs::symlink_metadata(&str): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::fs::write(&str, Vec<u8>): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::fs::ReadDir::next_entry(_): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::fs::OpenOptions::open(_, &str): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::fs::DirBuilder::create(_, &str): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::fs::DirEntry::metadata(_): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::fs::DirEntry::file_type(_): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::fs::File::open(&str): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::fs::File::create(&str): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::fs::File::sync_all(_): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::fs::File::sync_data(_): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::fs::File::set_len(_, u64): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::fs::File::metadata(_): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::fs::File::try_clone(_): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::fs::File::into_std(_): Send & Sync & !Unpin);
+        async_assert_fn!(
+            tokio::fs::File::set_permissions(_, std::fs::Permissions): Send & Sync & !Unpin
+        );
+    }
+}
+
+cfg_not_wasi! {
+    assert_value!(tokio::net::TcpSocket: Send & Sync & Unpin);
+    async_assert_fn!(tokio::net::TcpListener::bind(SocketAddr): Send & Sync & !Unpin);
+    async_assert_fn!(tokio::net::TcpStream::connect(SocketAddr): Send & Sync & !Unpin);
+}
+
+assert_value!(tokio::net::TcpListener: Send & Sync & Unpin);
+assert_value!(tokio::net::TcpStream: Send & Sync & Unpin);
+assert_value!(tokio::net::tcp::OwnedReadHalf: Send & Sync & Unpin);
+assert_value!(tokio::net::tcp::OwnedWriteHalf: Send & Sync & Unpin);
+assert_value!(tokio::net::tcp::ReadHalf<'_>: Send & Sync & Unpin);
+assert_value!(tokio::net::tcp::ReuniteError: Send & Sync & Unpin);
+assert_value!(tokio::net::tcp::WriteHalf<'_>: Send & Sync & Unpin);
+async_assert_fn!(tokio::net::TcpListener::accept(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::net::TcpStream::peek(_, &mut [u8]): Send & Sync & !Unpin);
+async_assert_fn!(tokio::net::TcpStream::readable(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::net::TcpStream::ready(_, tokio::io::Interest): Send & Sync & !Unpin);
+async_assert_fn!(tokio::net::TcpStream::writable(_): Send & Sync & !Unpin);
+
+// Wasi does not support UDP
+cfg_not_wasi! {
+    mod udp_socket {
+        use super::*;
+        assert_value!(tokio::net::UdpSocket: Send & Sync & Unpin);
+        async_assert_fn!(tokio::net::UdpSocket::bind(SocketAddr): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::net::UdpSocket::connect(_, SocketAddr): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::net::UdpSocket::peek_from(_, &mut [u8]): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::net::UdpSocket::readable(_): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::net::UdpSocket::ready(_, tokio::io::Interest): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::net::UdpSocket::recv(_, &mut [u8]): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::net::UdpSocket::recv_from(_, &mut [u8]): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::net::UdpSocket::send(_, &[u8]): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::net::UdpSocket::send_to(_, &[u8], SocketAddr): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::net::UdpSocket::writable(_): Send & Sync & !Unpin);
+    }
+}
+async_assert_fn!(tokio::net::lookup_host(SocketAddr): Send & Sync & !Unpin);
+async_assert_fn!(tokio::net::tcp::ReadHalf::peek(_, &mut [u8]): Send & Sync & !Unpin);
 
 #[cfg(unix)]
 mod unix_datagram {
     use super::*;
-    async_assert_fn!(tokio::net::UnixListener::bind(&str): Send & Sync);
-    async_assert_fn!(tokio::net::UnixListener::accept(_): Send & Sync);
-    async_assert_fn!(tokio::net::UnixDatagram::send(_, &[u8]): Send & Sync);
-    async_assert_fn!(tokio::net::UnixDatagram::recv(_, &mut [u8]): Send & Sync);
-    async_assert_fn!(tokio::net::UnixDatagram::send_to(_, &[u8], &str): Send & Sync);
-    async_assert_fn!(tokio::net::UnixDatagram::recv_from(_, &mut [u8]): Send & Sync);
-    async_assert_fn!(tokio::net::UnixStream::connect(&str): Send & Sync);
+    use tokio::net::*;
+    assert_value!(UnixDatagram: Send & Sync & Unpin);
+    assert_value!(UnixListener: Send & Sync & Unpin);
+    assert_value!(UnixStream: Send & Sync & Unpin);
+    assert_value!(unix::OwnedReadHalf: Send & Sync & Unpin);
+    assert_value!(unix::OwnedWriteHalf: Send & Sync & Unpin);
+    assert_value!(unix::ReadHalf<'_>: Send & Sync & Unpin);
+    assert_value!(unix::ReuniteError: Send & Sync & Unpin);
+    assert_value!(unix::SocketAddr: Send & Sync & Unpin);
+    assert_value!(unix::UCred: Send & Sync & Unpin);
+    assert_value!(unix::WriteHalf<'_>: Send & Sync & Unpin);
+    async_assert_fn!(UnixDatagram::readable(_): Send & Sync & !Unpin);
+    async_assert_fn!(UnixDatagram::ready(_, tokio::io::Interest): Send & Sync & !Unpin);
+    async_assert_fn!(UnixDatagram::recv(_, &mut [u8]): Send & Sync & !Unpin);
+    async_assert_fn!(UnixDatagram::recv_from(_, &mut [u8]): Send & Sync & !Unpin);
+    async_assert_fn!(UnixDatagram::send(_, &[u8]): Send & Sync & !Unpin);
+    async_assert_fn!(UnixDatagram::send_to(_, &[u8], &str): Send & Sync & !Unpin);
+    async_assert_fn!(UnixDatagram::writable(_): Send & Sync & !Unpin);
+    async_assert_fn!(UnixListener::accept(_): Send & Sync & !Unpin);
+    async_assert_fn!(UnixStream::connect(&str): Send & Sync & !Unpin);
+    async_assert_fn!(UnixStream::readable(_): Send & Sync & !Unpin);
+    async_assert_fn!(UnixStream::ready(_, tokio::io::Interest): Send & Sync & !Unpin);
+    async_assert_fn!(UnixStream::writable(_): Send & Sync & !Unpin);
 }
 
-async_assert_fn!(tokio::process::Child::wait_with_output(_): Send & Sync);
-async_assert_fn!(tokio::signal::ctrl_c(): Send & Sync);
 #[cfg(unix)]
-async_assert_fn!(tokio::signal::unix::Signal::recv(_): Send & Sync);
-
-async_assert_fn!(tokio::sync::Barrier::wait(_): Send & Sync);
-async_assert_fn!(tokio::sync::Mutex<u8>::lock(_): Send & Sync);
-async_assert_fn!(tokio::sync::Mutex<Cell<u8>>::lock(_): Send & Sync);
-async_assert_fn!(tokio::sync::Mutex<Rc<u8>>::lock(_): !Send & !Sync);
-async_assert_fn!(tokio::sync::Mutex<u8>::lock_owned(_): Send & Sync);
-async_assert_fn!(tokio::sync::Mutex<Cell<u8>>::lock_owned(_): Send & Sync);
-async_assert_fn!(tokio::sync::Mutex<Rc<u8>>::lock_owned(_): !Send & !Sync);
-async_assert_fn!(tokio::sync::Notify::notified(_): Send & Sync);
-async_assert_fn!(tokio::sync::RwLock<u8>::read(_): Send & Sync);
-async_assert_fn!(tokio::sync::RwLock<u8>::write(_): Send & Sync);
-async_assert_fn!(tokio::sync::RwLock<Cell<u8>>::read(_): !Send & !Sync);
-async_assert_fn!(tokio::sync::RwLock<Cell<u8>>::write(_): !Send & !Sync);
-async_assert_fn!(tokio::sync::RwLock<Rc<u8>>::read(_): !Send & !Sync);
-async_assert_fn!(tokio::sync::RwLock<Rc<u8>>::write(_): !Send & !Sync);
-async_assert_fn!(tokio::sync::Semaphore::acquire(_): Send & Sync);
-
-async_assert_fn!(tokio::sync::broadcast::Receiver<u8>::recv(_): Send & Sync);
-async_assert_fn!(tokio::sync::broadcast::Receiver<Cell<u8>>::recv(_): Send & Sync);
-async_assert_fn!(tokio::sync::broadcast::Receiver<Rc<u8>>::recv(_): !Send & !Sync);
-
-async_assert_fn!(tokio::sync::mpsc::Receiver<u8>::recv(_): Send & Sync);
-async_assert_fn!(tokio::sync::mpsc::Receiver<Cell<u8>>::recv(_): Send & Sync);
-async_assert_fn!(tokio::sync::mpsc::Receiver<Rc<u8>>::recv(_): !Send & !Sync);
-async_assert_fn!(tokio::sync::mpsc::Sender<u8>::send(_, u8): Send & Sync);
-async_assert_fn!(tokio::sync::mpsc::Sender<Cell<u8>>::send(_, Cell<u8>): Send & !Sync);
-async_assert_fn!(tokio::sync::mpsc::Sender<Rc<u8>>::send(_, Rc<u8>): !Send & !Sync);
-
-async_assert_fn!(tokio::sync::mpsc::UnboundedReceiver<u8>::recv(_): Send & Sync);
-async_assert_fn!(tokio::sync::mpsc::UnboundedReceiver<Cell<u8>>::recv(_): Send & Sync);
-async_assert_fn!(tokio::sync::mpsc::UnboundedReceiver<Rc<u8>>::recv(_): !Send & !Sync);
-
-async_assert_fn!(tokio::sync::watch::Receiver<u8>::changed(_): Send & Sync);
-async_assert_fn!(tokio::sync::watch::Sender<u8>::closed(_): Send & Sync);
-async_assert_fn!(tokio::sync::watch::Sender<Cell<u8>>::closed(_): !Send & !Sync);
-async_assert_fn!(tokio::sync::watch::Sender<Rc<u8>>::closed(_): !Send & !Sync);
-
-async_assert_fn!(tokio::sync::OnceCell<u8>::get_or_init(
-    _, fn() -> Pin<Box<dyn Future<Output = u8> + Send + Sync>>): Send & Sync);
-async_assert_fn!(tokio::sync::OnceCell<u8>::get_or_init(
-    _, fn() -> Pin<Box<dyn Future<Output = u8> + Send>>): Send & !Sync);
-async_assert_fn!(tokio::sync::OnceCell<u8>::get_or_init(
-    _, fn() -> Pin<Box<dyn Future<Output = u8>>>): !Send & !Sync);
-async_assert_fn!(tokio::sync::OnceCell<Cell<u8>>::get_or_init(
-    _, fn() -> Pin<Box<dyn Future<Output = Cell<u8>> + Send + Sync>>): !Send & !Sync);
-async_assert_fn!(tokio::sync::OnceCell<Cell<u8>>::get_or_init(
-    _, fn() -> Pin<Box<dyn Future<Output = Cell<u8>> + Send>>): !Send & !Sync);
-async_assert_fn!(tokio::sync::OnceCell<Cell<u8>>::get_or_init(
-    _, fn() -> Pin<Box<dyn Future<Output = Cell<u8>>>>): !Send & !Sync);
-async_assert_fn!(tokio::sync::OnceCell<Rc<u8>>::get_or_init(
-    _, fn() -> Pin<Box<dyn Future<Output = Rc<u8>> + Send + Sync>>): !Send & !Sync);
-async_assert_fn!(tokio::sync::OnceCell<Rc<u8>>::get_or_init(
-    _, fn() -> Pin<Box<dyn Future<Output = Rc<u8>> + Send>>): !Send & !Sync);
-async_assert_fn!(tokio::sync::OnceCell<Rc<u8>>::get_or_init(
-    _, fn() -> Pin<Box<dyn Future<Output = Rc<u8>>>>): !Send & !Sync);
-assert_value!(tokio::sync::OnceCell<u8>: Send & Sync);
-assert_value!(tokio::sync::OnceCell<Cell<u8>>: Send & !Sync);
-assert_value!(tokio::sync::OnceCell<Rc<u8>>: !Send & !Sync);
-
-async_assert_fn!(tokio::task::LocalKey<u32>::scope(_, u32, BoxFutureSync<()>): Send & Sync);
-async_assert_fn!(tokio::task::LocalKey<u32>::scope(_, u32, BoxFutureSend<()>): Send & !Sync);
-async_assert_fn!(tokio::task::LocalKey<u32>::scope(_, u32, BoxFuture<()>): !Send & !Sync);
-async_assert_fn!(tokio::task::LocalKey<Cell<u32>>::scope(_, Cell<u32>, BoxFutureSync<()>): Send & !Sync);
-async_assert_fn!(tokio::task::LocalKey<Cell<u32>>::scope(_, Cell<u32>, BoxFutureSend<()>): Send & !Sync);
-async_assert_fn!(tokio::task::LocalKey<Cell<u32>>::scope(_, Cell<u32>, BoxFuture<()>): !Send & !Sync);
-async_assert_fn!(tokio::task::LocalKey<Rc<u32>>::scope(_, Rc<u32>, BoxFutureSync<()>): !Send & !Sync);
-async_assert_fn!(tokio::task::LocalKey<Rc<u32>>::scope(_, Rc<u32>, BoxFutureSend<()>): !Send & !Sync);
-async_assert_fn!(tokio::task::LocalKey<Rc<u32>>::scope(_, Rc<u32>, BoxFuture<()>): !Send & !Sync);
-async_assert_fn!(tokio::task::LocalSet::run_until(_, BoxFutureSync<()>): !Send & !Sync);
-assert_value!(tokio::task::LocalSet: !Send & !Sync);
-
-async_assert_fn!(tokio::time::advance(Duration): Send & Sync);
-async_assert_fn!(tokio::time::sleep(Duration): Send & Sync);
-async_assert_fn!(tokio::time::sleep_until(Instant): Send & Sync);
-async_assert_fn!(tokio::time::timeout(Duration, BoxFutureSync<()>): Send & Sync);
-async_assert_fn!(tokio::time::timeout(Duration, BoxFutureSend<()>): Send & !Sync);
-async_assert_fn!(tokio::time::timeout(Duration, BoxFuture<()>): !Send & !Sync);
-async_assert_fn!(tokio::time::timeout_at(Instant, BoxFutureSync<()>): Send & Sync);
-async_assert_fn!(tokio::time::timeout_at(Instant, BoxFutureSend<()>): Send & !Sync);
-async_assert_fn!(tokio::time::timeout_at(Instant, BoxFuture<()>): !Send & !Sync);
-async_assert_fn!(tokio::time::Interval::tick(_): Send & Sync);
-
-assert_value!(tokio::time::Interval: Unpin);
-async_assert_fn!(tokio::time::sleep(Duration): !Unpin);
-async_assert_fn!(tokio::time::sleep_until(Instant): !Unpin);
-async_assert_fn!(tokio::time::timeout(Duration, BoxFuture<()>): !Unpin);
-async_assert_fn!(tokio::time::timeout_at(Instant, BoxFuture<()>): !Unpin);
-async_assert_fn!(tokio::time::Interval::tick(_): !Unpin);
-async_assert_fn!(tokio::io::AsyncBufReadExt::read_until(&mut BoxAsyncRead, u8, &mut Vec<u8>): !Unpin);
-async_assert_fn!(tokio::io::AsyncBufReadExt::read_line(&mut BoxAsyncRead, &mut String): !Unpin);
-async_assert_fn!(tokio::io::AsyncReadExt::read(&mut BoxAsyncRead, &mut [u8]): !Unpin);
-async_assert_fn!(tokio::io::AsyncReadExt::read_exact(&mut BoxAsyncRead, &mut [u8]): !Unpin);
-async_assert_fn!(tokio::io::AsyncReadExt::read_u8(&mut BoxAsyncRead): !Unpin);
-async_assert_fn!(tokio::io::AsyncReadExt::read_i8(&mut BoxAsyncRead): !Unpin);
-async_assert_fn!(tokio::io::AsyncReadExt::read_u16(&mut BoxAsyncRead): !Unpin);
-async_assert_fn!(tokio::io::AsyncReadExt::read_i16(&mut BoxAsyncRead): !Unpin);
-async_assert_fn!(tokio::io::AsyncReadExt::read_u32(&mut BoxAsyncRead): !Unpin);
-async_assert_fn!(tokio::io::AsyncReadExt::read_i32(&mut BoxAsyncRead): !Unpin);
-async_assert_fn!(tokio::io::AsyncReadExt::read_u64(&mut BoxAsyncRead): !Unpin);
-async_assert_fn!(tokio::io::AsyncReadExt::read_i64(&mut BoxAsyncRead): !Unpin);
-async_assert_fn!(tokio::io::AsyncReadExt::read_u128(&mut BoxAsyncRead): !Unpin);
-async_assert_fn!(tokio::io::AsyncReadExt::read_i128(&mut BoxAsyncRead): !Unpin);
-async_assert_fn!(tokio::io::AsyncReadExt::read_u16_le(&mut BoxAsyncRead): !Unpin);
-async_assert_fn!(tokio::io::AsyncReadExt::read_i16_le(&mut BoxAsyncRead): !Unpin);
-async_assert_fn!(tokio::io::AsyncReadExt::read_u32_le(&mut BoxAsyncRead): !Unpin);
-async_assert_fn!(tokio::io::AsyncReadExt::read_i32_le(&mut BoxAsyncRead): !Unpin);
-async_assert_fn!(tokio::io::AsyncReadExt::read_u64_le(&mut BoxAsyncRead): !Unpin);
-async_assert_fn!(tokio::io::AsyncReadExt::read_i64_le(&mut BoxAsyncRead): !Unpin);
-async_assert_fn!(tokio::io::AsyncReadExt::read_u128_le(&mut BoxAsyncRead): !Unpin);
-async_assert_fn!(tokio::io::AsyncReadExt::read_i128_le(&mut BoxAsyncRead): !Unpin);
-async_assert_fn!(tokio::io::AsyncReadExt::read_to_end(&mut BoxAsyncRead, &mut Vec<u8>): !Unpin);
-async_assert_fn!(tokio::io::AsyncReadExt::read_to_string(&mut BoxAsyncRead, &mut String): !Unpin);
-async_assert_fn!(tokio::io::AsyncSeekExt::seek(&mut BoxAsyncSeek, SeekFrom): !Unpin);
-async_assert_fn!(tokio::io::AsyncWriteExt::write(&mut BoxAsyncWrite, &[u8]): !Unpin);
-async_assert_fn!(tokio::io::AsyncWriteExt::write_all(&mut BoxAsyncWrite, &[u8]): !Unpin);
-async_assert_fn!(tokio::io::AsyncWriteExt::write_u8(&mut BoxAsyncWrite, u8): !Unpin);
-async_assert_fn!(tokio::io::AsyncWriteExt::write_i8(&mut BoxAsyncWrite, i8): !Unpin);
-async_assert_fn!(tokio::io::AsyncWriteExt::write_u16(&mut BoxAsyncWrite, u16): !Unpin);
-async_assert_fn!(tokio::io::AsyncWriteExt::write_i16(&mut BoxAsyncWrite, i16): !Unpin);
-async_assert_fn!(tokio::io::AsyncWriteExt::write_u32(&mut BoxAsyncWrite, u32): !Unpin);
-async_assert_fn!(tokio::io::AsyncWriteExt::write_i32(&mut BoxAsyncWrite, i32): !Unpin);
-async_assert_fn!(tokio::io::AsyncWriteExt::write_u64(&mut BoxAsyncWrite, u64): !Unpin);
-async_assert_fn!(tokio::io::AsyncWriteExt::write_i64(&mut BoxAsyncWrite, i64): !Unpin);
-async_assert_fn!(tokio::io::AsyncWriteExt::write_u128(&mut BoxAsyncWrite, u128): !Unpin);
-async_assert_fn!(tokio::io::AsyncWriteExt::write_i128(&mut BoxAsyncWrite, i128): !Unpin);
-async_assert_fn!(tokio::io::AsyncWriteExt::write_u16_le(&mut BoxAsyncWrite, u16): !Unpin);
-async_assert_fn!(tokio::io::AsyncWriteExt::write_i16_le(&mut BoxAsyncWrite, i16): !Unpin);
-async_assert_fn!(tokio::io::AsyncWriteExt::write_u32_le(&mut BoxAsyncWrite, u32): !Unpin);
-async_assert_fn!(tokio::io::AsyncWriteExt::write_i32_le(&mut BoxAsyncWrite, i32): !Unpin);
-async_assert_fn!(tokio::io::AsyncWriteExt::write_u64_le(&mut BoxAsyncWrite, u64): !Unpin);
-async_assert_fn!(tokio::io::AsyncWriteExt::write_i64_le(&mut BoxAsyncWrite, i64): !Unpin);
-async_assert_fn!(tokio::io::AsyncWriteExt::write_u128_le(&mut BoxAsyncWrite, u128): !Unpin);
-async_assert_fn!(tokio::io::AsyncWriteExt::write_i128_le(&mut BoxAsyncWrite, i128): !Unpin);
-async_assert_fn!(tokio::io::AsyncWriteExt::flush(&mut BoxAsyncWrite): !Unpin);
-async_assert_fn!(tokio::io::AsyncWriteExt::shutdown(&mut BoxAsyncWrite): !Unpin);
+mod unix_pipe {
+    use super::*;
+    use tokio::net::unix::pipe::*;
+    assert_value!(OpenOptions: Send & Sync & Unpin);
+    assert_value!(Receiver: Send & Sync & Unpin);
+    assert_value!(Sender: Send & Sync & Unpin);
+    async_assert_fn!(Receiver::readable(_): Send & Sync & !Unpin);
+    async_assert_fn!(Receiver::ready(_, tokio::io::Interest): Send & Sync & !Unpin);
+    async_assert_fn!(Sender::ready(_, tokio::io::Interest): Send & Sync & !Unpin);
+    async_assert_fn!(Sender::writable(_): Send & Sync & !Unpin);
+}
+
+#[cfg(windows)]
+mod windows_named_pipe {
+    use super::*;
+    use tokio::net::windows::named_pipe::*;
+    assert_value!(ClientOptions: Send & Sync & Unpin);
+    assert_value!(NamedPipeClient: Send & Sync & Unpin);
+    assert_value!(NamedPipeServer: Send & Sync & Unpin);
+    assert_value!(PipeEnd: Send & Sync & Unpin);
+    assert_value!(PipeInfo: Send & Sync & Unpin);
+    assert_value!(PipeMode: Send & Sync & Unpin);
+    assert_value!(ServerOptions: Send & Sync & Unpin);
+    async_assert_fn!(NamedPipeClient::readable(_): Send & Sync & !Unpin);
+    async_assert_fn!(NamedPipeClient::ready(_, tokio::io::Interest): Send & Sync & !Unpin);
+    async_assert_fn!(NamedPipeClient::writable(_): Send & Sync & !Unpin);
+    async_assert_fn!(NamedPipeServer::connect(_): Send & Sync & !Unpin);
+    async_assert_fn!(NamedPipeServer::readable(_): Send & Sync & !Unpin);
+    async_assert_fn!(NamedPipeServer::ready(_, tokio::io::Interest): Send & Sync & !Unpin);
+    async_assert_fn!(NamedPipeServer::writable(_): Send & Sync & !Unpin);
+}
+
+cfg_not_wasi! {
+    mod test_process {
+        use super::*;
+        assert_value!(tokio::process::Child: Send & Sync & Unpin);
+        assert_value!(tokio::process::ChildStderr: Send & Sync & Unpin);
+        assert_value!(tokio::process::ChildStdin: Send & Sync & Unpin);
+        assert_value!(tokio::process::ChildStdout: Send & Sync & Unpin);
+        assert_value!(tokio::process::Command: Send & Sync & Unpin);
+        async_assert_fn!(tokio::process::Child::kill(_): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::process::Child::wait(_): Send & Sync & !Unpin);
+        async_assert_fn!(tokio::process::Child::wait_with_output(_): Send & Sync & !Unpin);
+    }
+
+    async_assert_fn!(tokio::signal::ctrl_c(): Send & Sync & !Unpin);
+}
+
+#[cfg(unix)]
+mod unix_signal {
+    use super::*;
+    assert_value!(tokio::signal::unix::Signal: Send & Sync & Unpin);
+    assert_value!(tokio::signal::unix::SignalKind: Send & Sync & Unpin);
+    async_assert_fn!(tokio::signal::unix::Signal::recv(_): Send & Sync & !Unpin);
+}
+#[cfg(windows)]
+mod windows_signal {
+    use super::*;
+    assert_value!(tokio::signal::windows::CtrlC: Send & Sync & Unpin);
+    assert_value!(tokio::signal::windows::CtrlBreak: Send & Sync & Unpin);
+    async_assert_fn!(tokio::signal::windows::CtrlC::recv(_): Send & Sync & !Unpin);
+    async_assert_fn!(tokio::signal::windows::CtrlBreak::recv(_): Send & Sync & !Unpin);
+}
+
+assert_value!(tokio::sync::AcquireError: Send & Sync & Unpin);
+assert_value!(tokio::sync::Barrier: Send & Sync & Unpin);
+assert_value!(tokio::sync::BarrierWaitResult: Send & Sync & Unpin);
+assert_value!(tokio::sync::MappedMutexGuard<'_, NN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::MappedMutexGuard<'_, YN>: Send & !Sync & Unpin);
+assert_value!(tokio::sync::MappedMutexGuard<'_, YY>: Send & Sync & Unpin);
+assert_value!(tokio::sync::Mutex<NN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::Mutex<YN>: Send & Sync & Unpin);
+assert_value!(tokio::sync::Mutex<YY>: Send & Sync & Unpin);
+assert_value!(tokio::sync::MutexGuard<'_, NN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::MutexGuard<'_, YN>: Send & !Sync & Unpin);
+assert_value!(tokio::sync::MutexGuard<'_, YY>: Send & Sync & Unpin);
+assert_value!(tokio::sync::Notify: Send & Sync & Unpin);
+assert_value!(tokio::sync::OnceCell<NN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::OnceCell<YN>: Send & !Sync & Unpin);
+assert_value!(tokio::sync::OnceCell<YY>: Send & Sync & Unpin);
+assert_value!(tokio::sync::OwnedMutexGuard<NN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::OwnedMutexGuard<YN>: Send & !Sync & Unpin);
+assert_value!(tokio::sync::OwnedMutexGuard<YY>: Send & Sync & Unpin);
+assert_value!(tokio::sync::OwnedMappedMutexGuard<NN,NN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::OwnedMappedMutexGuard<NN,YN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::OwnedMappedMutexGuard<NN,YY>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::OwnedMappedMutexGuard<YN,NN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::OwnedMappedMutexGuard<YN,YN>: Send & !Sync & Unpin);
+assert_value!(tokio::sync::OwnedMappedMutexGuard<YN,YY>: Send & !Sync & Unpin);
+assert_value!(tokio::sync::OwnedMappedMutexGuard<YY,NN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::OwnedMappedMutexGuard<YY,YN>: Send & !Sync & Unpin);
+assert_value!(tokio::sync::OwnedMappedMutexGuard<YY,YY>: Send & Sync & Unpin);
+assert_value!(tokio::sync::OwnedRwLockMappedWriteGuard<NN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::OwnedRwLockMappedWriteGuard<YN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::OwnedRwLockMappedWriteGuard<YY>: Send & Sync & Unpin);
+assert_value!(tokio::sync::OwnedRwLockReadGuard<NN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::OwnedRwLockReadGuard<YN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::OwnedRwLockReadGuard<YY>: Send & Sync & Unpin);
+assert_value!(tokio::sync::OwnedRwLockWriteGuard<NN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::OwnedRwLockWriteGuard<YN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::OwnedRwLockWriteGuard<YY>: Send & Sync & Unpin);
+assert_value!(tokio::sync::OwnedSemaphorePermit: Send & Sync & Unpin);
+assert_value!(tokio::sync::RwLock<NN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::RwLock<YN>: Send & !Sync & Unpin);
+assert_value!(tokio::sync::RwLock<YY>: Send & Sync & Unpin);
+assert_value!(tokio::sync::RwLockMappedWriteGuard<'_, NN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::RwLockMappedWriteGuard<'_, YN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::RwLockMappedWriteGuard<'_, YY>: Send & Sync & Unpin);
+assert_value!(tokio::sync::RwLockReadGuard<'_, NN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::RwLockReadGuard<'_, YN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::RwLockReadGuard<'_, YY>: Send & Sync & Unpin);
+assert_value!(tokio::sync::RwLockWriteGuard<'_, NN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::RwLockWriteGuard<'_, YN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::RwLockWriteGuard<'_, YY>: Send & Sync & Unpin);
+assert_value!(tokio::sync::Semaphore: Send & Sync & Unpin);
+assert_value!(tokio::sync::SemaphorePermit<'_>: Send & Sync & Unpin);
+assert_value!(tokio::sync::TryAcquireError: Send & Sync & Unpin);
+assert_value!(tokio::sync::TryLockError: Send & Sync & Unpin);
+assert_value!(tokio::sync::broadcast::Receiver<NN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::broadcast::Receiver<YN>: Send & Sync & Unpin);
+assert_value!(tokio::sync::broadcast::Receiver<YY>: Send & Sync & Unpin);
+assert_value!(tokio::sync::broadcast::Sender<NN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::broadcast::Sender<YN>: Send & Sync & Unpin);
+assert_value!(tokio::sync::broadcast::Sender<YY>: Send & Sync & Unpin);
+assert_value!(tokio::sync::futures::Notified<'_>: Send & Sync & !Unpin);
+assert_value!(tokio::sync::mpsc::OwnedPermit<NN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::mpsc::OwnedPermit<YN>: Send & Sync & Unpin);
+assert_value!(tokio::sync::mpsc::OwnedPermit<YY>: Send & Sync & Unpin);
+assert_value!(tokio::sync::mpsc::Permit<'_, NN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::mpsc::Permit<'_, YN>: Send & Sync & Unpin);
+assert_value!(tokio::sync::mpsc::Permit<'_, YY>: Send & Sync & Unpin);
+assert_value!(tokio::sync::mpsc::Receiver<NN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::mpsc::Receiver<YN>: Send & Sync & Unpin);
+assert_value!(tokio::sync::mpsc::Receiver<YY>: Send & Sync & Unpin);
+assert_value!(tokio::sync::mpsc::Sender<NN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::mpsc::Sender<YN>: Send & Sync & Unpin);
+assert_value!(tokio::sync::mpsc::Sender<YY>: Send & Sync & Unpin);
+assert_value!(tokio::sync::mpsc::UnboundedReceiver<NN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::mpsc::UnboundedReceiver<YN>: Send & Sync & Unpin);
+assert_value!(tokio::sync::mpsc::UnboundedReceiver<YY>: Send & Sync & Unpin);
+assert_value!(tokio::sync::mpsc::UnboundedSender<NN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::mpsc::UnboundedSender<YN>: Send & Sync & Unpin);
+assert_value!(tokio::sync::mpsc::UnboundedSender<YY>: Send & Sync & Unpin);
+assert_value!(tokio::sync::mpsc::error::SendError<NN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::mpsc::error::SendError<YN>: Send & !Sync & Unpin);
+assert_value!(tokio::sync::mpsc::error::SendError<YY>: Send & Sync & Unpin);
+assert_value!(tokio::sync::mpsc::error::SendTimeoutError<NN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::mpsc::error::SendTimeoutError<YN>: Send & !Sync & Unpin);
+assert_value!(tokio::sync::mpsc::error::SendTimeoutError<YY>: Send & Sync & Unpin);
+assert_value!(tokio::sync::mpsc::error::TrySendError<NN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::mpsc::error::TrySendError<YN>: Send & !Sync & Unpin);
+assert_value!(tokio::sync::mpsc::error::TrySendError<YY>: Send & Sync & Unpin);
+assert_value!(tokio::sync::oneshot::Receiver<NN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::oneshot::Receiver<YN>: Send & Sync & Unpin);
+assert_value!(tokio::sync::oneshot::Receiver<YY>: Send & Sync & Unpin);
+assert_value!(tokio::sync::oneshot::Sender<NN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::oneshot::Sender<YN>: Send & Sync & Unpin);
+assert_value!(tokio::sync::oneshot::Sender<YY>: Send & Sync & Unpin);
+assert_value!(tokio::sync::watch::Receiver<NN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::watch::Receiver<YN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::watch::Receiver<YY>: Send & Sync & Unpin);
+assert_value!(tokio::sync::watch::Ref<'_, NN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::watch::Ref<'_, YN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::watch::Ref<'_, YY>: !Send & Sync & Unpin);
+assert_value!(tokio::sync::watch::Sender<NN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::watch::Sender<YN>: !Send & !Sync & Unpin);
+assert_value!(tokio::sync::watch::Sender<YY>: Send & Sync & Unpin);
+assert_value!(tokio::task::JoinError: Send & Sync & Unpin);
+assert_value!(tokio::task::JoinHandle<NN>: !Send & !Sync & Unpin);
+assert_value!(tokio::task::JoinHandle<YN>: Send & Sync & Unpin);
+assert_value!(tokio::task::JoinHandle<YY>: Send & Sync & Unpin);
+assert_value!(tokio::task::JoinSet<NN>: !Send & !Sync & Unpin);
+assert_value!(tokio::task::JoinSet<YN>: Send & Sync & Unpin);
+assert_value!(tokio::task::JoinSet<YY>: Send & Sync & Unpin);
+assert_value!(tokio::task::LocalSet: !Send & !Sync & Unpin);
+async_assert_fn!(tokio::sync::Barrier::wait(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::sync::Mutex<NN>::lock(_): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::Mutex<NN>::lock_owned(_): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::Mutex<YN>::lock(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::sync::Mutex<YN>::lock_owned(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::sync::Mutex<YY>::lock(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::sync::Mutex<YY>::lock_owned(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::sync::Notify::notified(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::sync::OnceCell<NN>::get_or_init( _, fn() -> Pin<Box<dyn Future<Output = NN> + Send + Sync>>): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::OnceCell<NN>::get_or_init( _, fn() -> Pin<Box<dyn Future<Output = NN> + Send>>): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::OnceCell<NN>::get_or_init( _, fn() -> Pin<Box<dyn Future<Output = NN>>>): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::OnceCell<NN>::get_or_try_init( _, fn() -> Pin<Box<dyn Future<Output = std::io::Result<NN>> + Send + Sync>>): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::OnceCell<NN>::get_or_try_init( _, fn() -> Pin<Box<dyn Future<Output = std::io::Result<NN>> + Send>>): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::OnceCell<NN>::get_or_try_init( _, fn() -> Pin<Box<dyn Future<Output = std::io::Result<NN>>>>): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::OnceCell<YN>::get_or_init( _, fn() -> Pin<Box<dyn Future<Output = YN> + Send + Sync>>): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::OnceCell<YN>::get_or_init( _, fn() -> Pin<Box<dyn Future<Output = YN> + Send>>): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::OnceCell<YN>::get_or_init( _, fn() -> Pin<Box<dyn Future<Output = YN>>>): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::OnceCell<YN>::get_or_try_init( _, fn() -> Pin<Box<dyn Future<Output = std::io::Result<YN>> + Send + Sync>>): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::OnceCell<YN>::get_or_try_init( _, fn() -> Pin<Box<dyn Future<Output = std::io::Result<YN>> + Send>>): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::OnceCell<YN>::get_or_try_init( _, fn() -> Pin<Box<dyn Future<Output = std::io::Result<YN>>>>): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::OnceCell<YY>::get_or_init( _, fn() -> Pin<Box<dyn Future<Output = YY> + Send + Sync>>): Send & Sync & !Unpin);
+async_assert_fn!(tokio::sync::OnceCell<YY>::get_or_init( _, fn() -> Pin<Box<dyn Future<Output = YY> + Send>>): Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::OnceCell<YY>::get_or_init( _, fn() -> Pin<Box<dyn Future<Output = YY>>>): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::OnceCell<YY>::get_or_try_init( _, fn() -> Pin<Box<dyn Future<Output = std::io::Result<YY>> + Send + Sync>>): Send & Sync & !Unpin);
+async_assert_fn!(tokio::sync::OnceCell<YY>::get_or_try_init( _, fn() -> Pin<Box<dyn Future<Output = std::io::Result<YY>> + Send>>): Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::OnceCell<YY>::get_or_try_init( _, fn() -> Pin<Box<dyn Future<Output = std::io::Result<YY>>>>): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::RwLock<NN>::read(_): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::RwLock<NN>::write(_): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::RwLock<YN>::read(_): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::RwLock<YN>::write(_): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::RwLock<YY>::read(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::sync::RwLock<YY>::write(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::sync::Semaphore::acquire(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::sync::Semaphore::acquire_many(_, u32): Send & Sync & !Unpin);
+async_assert_fn!(tokio::sync::Semaphore::acquire_many_owned(_, u32): Send & Sync & !Unpin);
+async_assert_fn!(tokio::sync::Semaphore::acquire_owned(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::sync::broadcast::Receiver<NN>::recv(_): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::broadcast::Receiver<YN>::recv(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::sync::broadcast::Receiver<YY>::recv(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::sync::mpsc::Receiver<NN>::recv(_): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::mpsc::Receiver<YN>::recv(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::sync::mpsc::Receiver<YY>::recv(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::sync::mpsc::Sender<NN>::closed(_): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::mpsc::Sender<NN>::reserve(_): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::mpsc::Sender<NN>::reserve_owned(_): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::mpsc::Sender<NN>::send(_, NN): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::mpsc::Sender<NN>::send_timeout(_, NN, Duration): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::mpsc::Sender<YN>::closed(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::sync::mpsc::Sender<YN>::reserve(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::sync::mpsc::Sender<YN>::reserve_owned(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::sync::mpsc::Sender<YN>::send(_, YN): Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::mpsc::Sender<YN>::send_timeout(_, YN, Duration): Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::mpsc::Sender<YY>::closed(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::sync::mpsc::Sender<YY>::reserve(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::sync::mpsc::Sender<YY>::reserve_owned(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::sync::mpsc::Sender<YY>::send(_, YY): Send & Sync & !Unpin);
+async_assert_fn!(tokio::sync::mpsc::Sender<YY>::send_timeout(_, YY, Duration): Send & Sync & !Unpin);
+async_assert_fn!(tokio::sync::mpsc::UnboundedReceiver<NN>::recv(_): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::mpsc::UnboundedReceiver<YN>::recv(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::sync::mpsc::UnboundedReceiver<YY>::recv(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::sync::mpsc::UnboundedSender<NN>::closed(_): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::mpsc::UnboundedSender<YN>::closed(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::sync::mpsc::UnboundedSender<YY>::closed(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::sync::oneshot::Sender<NN>::closed(_): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::oneshot::Sender<YN>::closed(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::sync::oneshot::Sender<YY>::closed(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::sync::watch::Receiver<NN>::changed(_): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::watch::Receiver<YN>::changed(_): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::watch::Receiver<YY>::changed(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::sync::watch::Sender<NN>::closed(_): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::watch::Sender<YN>::closed(_): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::sync::watch::Sender<YY>::closed(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::task::JoinSet<Cell<u32>>::join_next(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::task::JoinSet<Cell<u32>>::shutdown(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::task::JoinSet<Rc<u32>>::join_next(_): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::task::JoinSet<Rc<u32>>::shutdown(_): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::task::JoinSet<u32>::join_next(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::task::JoinSet<u32>::shutdown(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::task::LocalKey<Cell<u32>>::scope(_, Cell<u32>, BoxFuture<()>): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::task::LocalKey<Cell<u32>>::scope(_, Cell<u32>, BoxFutureSend<()>): Send & !Sync & !Unpin);
+async_assert_fn!(tokio::task::LocalKey<Cell<u32>>::scope(_, Cell<u32>, BoxFutureSync<()>): Send & !Sync & !Unpin);
+async_assert_fn!(tokio::task::LocalKey<Rc<u32>>::scope(_, Rc<u32>, BoxFuture<()>): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::task::LocalKey<Rc<u32>>::scope(_, Rc<u32>, BoxFutureSend<()>): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::task::LocalKey<Rc<u32>>::scope(_, Rc<u32>, BoxFutureSync<()>): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::task::LocalKey<u32>::scope(_, u32, BoxFuture<()>): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::task::LocalKey<u32>::scope(_, u32, BoxFutureSend<()>): Send & !Sync & !Unpin);
+async_assert_fn!(tokio::task::LocalKey<u32>::scope(_, u32, BoxFutureSync<()>): Send & Sync & !Unpin);
+async_assert_fn!(tokio::task::LocalSet::run_until(_, BoxFutureSync<()>): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::task::unconstrained(BoxFuture<()>): !Send & !Sync & Unpin);
+async_assert_fn!(tokio::task::unconstrained(BoxFutureSend<()>): Send & !Sync & Unpin);
+async_assert_fn!(tokio::task::unconstrained(BoxFutureSync<()>): Send & Sync & Unpin);
+
+assert_value!(tokio::runtime::Builder: Send & Sync & Unpin);
+assert_value!(tokio::runtime::EnterGuard<'_>: !Send & Sync & Unpin);
+assert_value!(tokio::runtime::Handle: Send & Sync & Unpin);
+assert_value!(tokio::runtime::Runtime: Send & Sync & Unpin);
+
+assert_value!(tokio::time::Interval: Send & Sync & Unpin);
+assert_value!(tokio::time::Instant: Send & Sync & Unpin);
+assert_value!(tokio::time::Sleep: Send & Sync & !Unpin);
+assert_value!(tokio::time::Timeout<BoxFutureSync<()>>: Send & Sync & !Unpin);
+assert_value!(tokio::time::Timeout<BoxFutureSend<()>>: Send & !Sync & !Unpin);
+assert_value!(tokio::time::Timeout<BoxFuture<()>>: !Send & !Sync & !Unpin);
+assert_value!(tokio::time::error::Elapsed: Send & Sync & Unpin);
+assert_value!(tokio::time::error::Error: Send & Sync & Unpin);
+async_assert_fn!(tokio::time::advance(Duration): Send & Sync & !Unpin);
+async_assert_fn!(tokio::time::sleep(Duration): Send & Sync & !Unpin);
+async_assert_fn!(tokio::time::sleep_until(Instant): Send & Sync & !Unpin);
+async_assert_fn!(tokio::time::timeout(Duration, BoxFutureSync<()>): Send & Sync & !Unpin);
+async_assert_fn!(tokio::time::timeout(Duration, BoxFutureSend<()>): Send & !Sync & !Unpin);
+async_assert_fn!(tokio::time::timeout(Duration, BoxFuture<()>): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::time::timeout_at(Instant, BoxFutureSync<()>): Send & Sync & !Unpin);
+async_assert_fn!(tokio::time::timeout_at(Instant, BoxFutureSend<()>): Send & !Sync & !Unpin);
+async_assert_fn!(tokio::time::timeout_at(Instant, BoxFuture<()>): !Send & !Sync & !Unpin);
+async_assert_fn!(tokio::time::Interval::tick(_): Send & Sync & !Unpin);
+
+assert_value!(tokio::io::BufReader<TcpStream>: Send & Sync & Unpin);
+assert_value!(tokio::io::BufStream<TcpStream>: Send & Sync & Unpin);
+assert_value!(tokio::io::BufWriter<TcpStream>: Send & Sync & Unpin);
+assert_value!(tokio::io::DuplexStream: Send & Sync & Unpin);
+assert_value!(tokio::io::Empty: Send & Sync & Unpin);
+assert_value!(tokio::io::Interest: Send & Sync & Unpin);
+assert_value!(tokio::io::Lines<TcpStream>: Send & Sync & Unpin);
+assert_value!(tokio::io::ReadBuf<'_>: Send & Sync & Unpin);
+assert_value!(tokio::io::ReadHalf<TcpStream>: Send & Sync & Unpin);
+assert_value!(tokio::io::Ready: Send & Sync & Unpin);
+assert_value!(tokio::io::Repeat: Send & Sync & Unpin);
+assert_value!(tokio::io::Sink: Send & Sync & Unpin);
+assert_value!(tokio::io::Split<TcpStream>: Send & Sync & Unpin);
+assert_value!(tokio::io::Stderr: Send & Sync & Unpin);
+assert_value!(tokio::io::Stdin: Send & Sync & Unpin);
+assert_value!(tokio::io::Stdout: Send & Sync & Unpin);
+assert_value!(tokio::io::Take<TcpStream>: Send & Sync & Unpin);
+assert_value!(tokio::io::WriteHalf<TcpStream>: Send & Sync & Unpin);
+async_assert_fn!(tokio::io::copy(&mut TcpStream, &mut TcpStream): Send & Sync & !Unpin);
+async_assert_fn!(
+    tokio::io::copy_bidirectional(&mut TcpStream, &mut TcpStream): Send & Sync & !Unpin
+);
+async_assert_fn!(tokio::io::copy_buf(&mut tokio::io::BufReader<TcpStream>, &mut TcpStream): Send & Sync & !Unpin);
+async_assert_fn!(tokio::io::empty(): Send & Sync & Unpin);
+async_assert_fn!(tokio::io::repeat(u8): Send & Sync & Unpin);
+async_assert_fn!(tokio::io::sink(): Send & Sync & Unpin);
+async_assert_fn!(tokio::io::split(TcpStream): Send & Sync & Unpin);
+async_assert_fn!(tokio::io::stderr(): Send & Sync & Unpin);
+async_assert_fn!(tokio::io::stdin(): Send & Sync & Unpin);
+async_assert_fn!(tokio::io::stdout(): Send & Sync & Unpin);
+async_assert_fn!(tokio::io::Split<tokio::io::BufReader<TcpStream>>::next_segment(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::io::Lines<tokio::io::BufReader<TcpStream>>::next_line(_): Send & Sync & !Unpin);
+async_assert_fn!(tokio::io::AsyncBufReadExt::read_until(&mut BoxAsyncRead, u8, &mut Vec<u8>): Send & Sync & !Unpin);
+async_assert_fn!(
+    tokio::io::AsyncBufReadExt::read_line(&mut BoxAsyncRead, &mut String): Send & Sync & !Unpin
+);
+async_assert_fn!(tokio::io::AsyncBufReadExt::fill_buf(&mut BoxAsyncRead): Send & Sync & !Unpin);
+async_assert_fn!(tokio::io::AsyncReadExt::read(&mut BoxAsyncRead, &mut [u8]): Send & Sync & !Unpin);
+async_assert_fn!(tokio::io::AsyncReadExt::read_buf(&mut BoxAsyncRead, &mut Vec<u8>): Send & Sync & !Unpin);
+async_assert_fn!(
+    tokio::io::AsyncReadExt::read_exact(&mut BoxAsyncRead, &mut [u8]): Send & Sync & !Unpin
+);
+async_assert_fn!(tokio::io::AsyncReadExt::read_u8(&mut BoxAsyncRead): Send & Sync & !Unpin);
+async_assert_fn!(tokio::io::AsyncReadExt::read_i8(&mut BoxAsyncRead): Send & Sync & !Unpin);
+async_assert_fn!(tokio::io::AsyncReadExt::read_u16(&mut BoxAsyncRead): Send & Sync & !Unpin);
+async_assert_fn!(tokio::io::AsyncReadExt::read_i16(&mut BoxAsyncRead): Send & Sync & !Unpin);
+async_assert_fn!(tokio::io::AsyncReadExt::read_u32(&mut BoxAsyncRead): Send & Sync & !Unpin);
+async_assert_fn!(tokio::io::AsyncReadExt::read_i32(&mut BoxAsyncRead): Send & Sync & !Unpin);
+async_assert_fn!(tokio::io::AsyncReadExt::read_u64(&mut BoxAsyncRead): Send & Sync & !Unpin);
+async_assert_fn!(tokio::io::AsyncReadExt::read_i64(&mut BoxAsyncRead): Send & Sync & !Unpin);
+async_assert_fn!(tokio::io::AsyncReadExt::read_u128(&mut BoxAsyncRead): Send & Sync & !Unpin);
+async_assert_fn!(tokio::io::AsyncReadExt::read_i128(&mut BoxAsyncRead): Send & Sync & !Unpin);
+async_assert_fn!(tokio::io::AsyncReadExt::read_f32(&mut BoxAsyncRead): Send & Sync & !Unpin);
+async_assert_fn!(tokio::io::AsyncReadExt::read_f64(&mut BoxAsyncRead): Send & Sync & !Unpin);
+async_assert_fn!(tokio::io::AsyncReadExt::read_u16_le(&mut BoxAsyncRead): Send & Sync & !Unpin);
+async_assert_fn!(tokio::io::AsyncReadExt::read_i16_le(&mut BoxAsyncRead): Send & Sync & !Unpin);
+async_assert_fn!(tokio::io::AsyncReadExt::read_u32_le(&mut BoxAsyncRead): Send & Sync & !Unpin);
+async_assert_fn!(tokio::io::AsyncReadExt::read_i32_le(&mut BoxAsyncRead): Send & Sync & !Unpin);
+async_assert_fn!(tokio::io::AsyncReadExt::read_u64_le(&mut BoxAsyncRead): Send & Sync & !Unpin);
+async_assert_fn!(tokio::io::AsyncReadExt::read_i64_le(&mut BoxAsyncRead): Send & Sync & !Unpin);
+async_assert_fn!(tokio::io::AsyncReadExt::read_u128_le(&mut BoxAsyncRead): Send & Sync & !Unpin);
+async_assert_fn!(tokio::io::AsyncReadExt::read_i128_le(&mut BoxAsyncRead): Send & Sync & !Unpin);
+async_assert_fn!(tokio::io::AsyncReadExt::read_f32_le(&mut BoxAsyncRead): Send & Sync & !Unpin);
+async_assert_fn!(tokio::io::AsyncReadExt::read_f64_le(&mut BoxAsyncRead): Send & Sync & !Unpin);
+async_assert_fn!(tokio::io::AsyncReadExt::read_to_end(&mut BoxAsyncRead, &mut Vec<u8>): Send & Sync & !Unpin);
+async_assert_fn!(
+    tokio::io::AsyncReadExt::read_to_string(&mut BoxAsyncRead, &mut String): Send & Sync & !Unpin
+);
+async_assert_fn!(tokio::io::AsyncSeekExt::seek(&mut BoxAsyncSeek, SeekFrom): Send & Sync & !Unpin);
+async_assert_fn!(tokio::io::AsyncSeekExt::stream_position(&mut BoxAsyncSeek): Send & Sync & !Unpin);
+async_assert_fn!(tokio::io::AsyncWriteExt::write(&mut BoxAsyncWrite, &[u8]): Send & Sync & !Unpin);
+async_assert_fn!(
+    tokio::io::AsyncWriteExt::write_vectored(&mut BoxAsyncWrite, _): Send & Sync & !Unpin
+);
+async_assert_fn!(
+    tokio::io::AsyncWriteExt::write_buf(&mut BoxAsyncWrite, &mut bytes::Bytes): Send
+        & Sync
+        & !Unpin
+);
+async_assert_fn!(
+    tokio::io::AsyncWriteExt::write_all_buf(&mut BoxAsyncWrite, &mut bytes::Bytes): Send
+        & Sync
+        & !Unpin
+);
+async_assert_fn!(
+    tokio::io::AsyncWriteExt::write_all(&mut BoxAsyncWrite, &[u8]): Send & Sync & !Unpin
+);
+async_assert_fn!(tokio::io::AsyncWriteExt::write_u8(&mut BoxAsyncWrite, u8): Send & Sync & !Unpin);
+async_assert_fn!(tokio::io::AsyncWriteExt::write_i8(&mut BoxAsyncWrite, i8): Send & Sync & !Unpin);
+async_assert_fn!(
+    tokio::io::AsyncWriteExt::write_u16(&mut BoxAsyncWrite, u16): Send & Sync & !Unpin
+);
+async_assert_fn!(
+    tokio::io::AsyncWriteExt::write_i16(&mut BoxAsyncWrite, i16): Send & Sync & !Unpin
+);
+async_assert_fn!(
+    tokio::io::AsyncWriteExt::write_u32(&mut BoxAsyncWrite, u32): Send & Sync & !Unpin
+);
+async_assert_fn!(
+    tokio::io::AsyncWriteExt::write_i32(&mut BoxAsyncWrite, i32): Send & Sync & !Unpin
+);
+async_assert_fn!(
+    tokio::io::AsyncWriteExt::write_u64(&mut BoxAsyncWrite, u64): Send & Sync & !Unpin
+);
+async_assert_fn!(
+    tokio::io::AsyncWriteExt::write_i64(&mut BoxAsyncWrite, i64): Send & Sync & !Unpin
+);
+async_assert_fn!(
+    tokio::io::AsyncWriteExt::write_u128(&mut BoxAsyncWrite, u128): Send & Sync & !Unpin
+);
+async_assert_fn!(
+    tokio::io::AsyncWriteExt::write_i128(&mut BoxAsyncWrite, i128): Send & Sync & !Unpin
+);
+async_assert_fn!(
+    tokio::io::AsyncWriteExt::write_f32(&mut BoxAsyncWrite, f32): Send & Sync & !Unpin
+);
+async_assert_fn!(
+    tokio::io::AsyncWriteExt::write_f64(&mut BoxAsyncWrite, f64): Send & Sync & !Unpin
+);
+async_assert_fn!(
+    tokio::io::AsyncWriteExt::write_u16_le(&mut BoxAsyncWrite, u16): Send & Sync & !Unpin
+);
+async_assert_fn!(
+    tokio::io::AsyncWriteExt::write_i16_le(&mut BoxAsyncWrite, i16): Send & Sync & !Unpin
+);
+async_assert_fn!(
+    tokio::io::AsyncWriteExt::write_u32_le(&mut BoxAsyncWrite, u32): Send & Sync & !Unpin
+);
+async_assert_fn!(
+    tokio::io::AsyncWriteExt::write_i32_le(&mut BoxAsyncWrite, i32): Send & Sync & !Unpin
+);
+async_assert_fn!(
+    tokio::io::AsyncWriteExt::write_u64_le(&mut BoxAsyncWrite, u64): Send & Sync & !Unpin
+);
+async_assert_fn!(
+    tokio::io::AsyncWriteExt::write_i64_le(&mut BoxAsyncWrite, i64): Send & Sync & !Unpin
+);
+async_assert_fn!(
+    tokio::io::AsyncWriteExt::write_u128_le(&mut BoxAsyncWrite, u128): Send & Sync & !Unpin
+);
+async_assert_fn!(
+    tokio::io::AsyncWriteExt::write_i128_le(&mut BoxAsyncWrite, i128): Send & Sync & !Unpin
+);
+async_assert_fn!(
+    tokio::io::AsyncWriteExt::write_f32_le(&mut BoxAsyncWrite, f32): Send & Sync & !Unpin
+);
+async_assert_fn!(
+    tokio::io::AsyncWriteExt::write_f64_le(&mut BoxAsyncWrite, f64): Send & Sync & !Unpin
+);
+async_assert_fn!(tokio::io::AsyncWriteExt::flush(&mut BoxAsyncWrite): Send & Sync & !Unpin);
+async_assert_fn!(tokio::io::AsyncWriteExt::shutdown(&mut BoxAsyncWrite): Send & Sync & !Unpin);
+
+#[cfg(unix)]
+mod unix_asyncfd {
+    use super::*;
+    use tokio::io::unix::*;
+
+    struct ImplsFd<T> {
+        _t: T,
+    }
+    impl<T> std::os::unix::io::AsRawFd for ImplsFd<T> {
+        fn as_raw_fd(&self) -> std::os::unix::io::RawFd {
+            unreachable!()
+        }
+    }
+
+    assert_value!(AsyncFd<ImplsFd<YY>>: Send & Sync & Unpin);
+    assert_value!(AsyncFd<ImplsFd<YN>>: Send & !Sync & Unpin);
+    assert_value!(AsyncFd<ImplsFd<NN>>: !Send & !Sync & Unpin);
+    assert_value!(AsyncFdReadyGuard<'_, ImplsFd<YY>>: Send & Sync & Unpin);
+    assert_value!(AsyncFdReadyGuard<'_, ImplsFd<YN>>: !Send & !Sync & Unpin);
+    assert_value!(AsyncFdReadyGuard<'_, ImplsFd<NN>>: !Send & !Sync & Unpin);
+    assert_value!(AsyncFdReadyMutGuard<'_, ImplsFd<YY>>: Send & Sync & Unpin);
+    assert_value!(AsyncFdReadyMutGuard<'_, ImplsFd<YN>>: Send & !Sync & Unpin);
+    assert_value!(AsyncFdReadyMutGuard<'_, ImplsFd<NN>>: !Send & !Sync & Unpin);
+    assert_value!(TryIoError: Send & Sync & Unpin);
+    async_assert_fn!(AsyncFd<ImplsFd<YY>>::readable(_): Send & Sync & !Unpin);
+    async_assert_fn!(AsyncFd<ImplsFd<YY>>::readable_mut(_): Send & Sync & !Unpin);
+    async_assert_fn!(AsyncFd<ImplsFd<YY>>::writable(_): Send & Sync & !Unpin);
+    async_assert_fn!(AsyncFd<ImplsFd<YY>>::writable_mut(_): Send & Sync & !Unpin);
+    async_assert_fn!(AsyncFd<ImplsFd<YN>>::readable(_): !Send & !Sync & !Unpin);
+    async_assert_fn!(AsyncFd<ImplsFd<YN>>::readable_mut(_): Send & !Sync & !Unpin);
+    async_assert_fn!(AsyncFd<ImplsFd<YN>>::writable(_): !Send & !Sync & !Unpin);
+    async_assert_fn!(AsyncFd<ImplsFd<YN>>::writable_mut(_): Send & !Sync & !Unpin);
+    async_assert_fn!(AsyncFd<ImplsFd<NN>>::readable(_): !Send & !Sync & !Unpin);
+    async_assert_fn!(AsyncFd<ImplsFd<NN>>::readable_mut(_): !Send & !Sync & !Unpin);
+    async_assert_fn!(AsyncFd<ImplsFd<NN>>::writable(_): !Send & !Sync & !Unpin);
+    async_assert_fn!(AsyncFd<ImplsFd<NN>>::writable_mut(_): !Send & !Sync & !Unpin);
+}
diff --git a/vendor/tokio/tests/buffered.rs b/vendor/tokio/tests/buffered.rs
index 98b6d5f31..4251c3fcc 100644
--- a/vendor/tokio/tests/buffered.rs
+++ b/vendor/tokio/tests/buffered.rs
@@ -1,5 +1,5 @@
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi does not support bind()
 
 use tokio::net::TcpListener;
 use tokio_test::assert_ok;
@@ -18,10 +18,10 @@ async fn echo_server() {
     let msg = "foo bar baz";
 
     let t = thread::spawn(move || {
-        let mut s = assert_ok!(TcpStream::connect(&addr));
+        let mut s = assert_ok!(TcpStream::connect(addr));
 
         let t2 = thread::spawn(move || {
-            let mut s = assert_ok!(TcpStream::connect(&addr));
+            let mut s = assert_ok!(TcpStream::connect(addr));
             let mut b = vec![0; msg.len() * N];
             assert_ok!(s.read_exact(&mut b));
             b
diff --git a/vendor/tokio/tests/dump.rs b/vendor/tokio/tests/dump.rs
new file mode 100644
index 000000000..658ee4b9b
--- /dev/null
+++ b/vendor/tokio/tests/dump.rs
@@ -0,0 +1,99 @@
+#![cfg(all(
+    tokio_unstable,
+    tokio_taskdump,
+    target_os = "linux",
+    any(target_arch = "aarch64", target_arch = "x86", target_arch = "x86_64")
+))]
+
+use std::hint::black_box;
+use tokio::runtime::{self, Handle};
+
+#[inline(never)]
+async fn a() {
+    black_box(b()).await
+}
+
+#[inline(never)]
+async fn b() {
+    black_box(c()).await
+}
+
+#[inline(never)]
+async fn c() {
+    loop {
+        black_box(tokio::task::yield_now()).await
+    }
+}
+
+#[test]
+fn current_thread() {
+    let rt = runtime::Builder::new_current_thread()
+        .enable_all()
+        .build()
+        .unwrap();
+
+    async fn dump() {
+        let handle = Handle::current();
+        let dump = handle.dump().await;
+
+        let tasks: Vec<_> = dump.tasks().iter().collect();
+
+        assert_eq!(tasks.len(), 3);
+
+        for task in tasks {
+            let trace = task.trace().to_string();
+            eprintln!("\n\n{trace}\n\n");
+            assert!(trace.contains("dump::a"));
+            assert!(trace.contains("dump::b"));
+            assert!(trace.contains("dump::c"));
+            assert!(trace.contains("tokio::task::yield_now"));
+        }
+    }
+
+    rt.block_on(async {
+        tokio::select!(
+            biased;
+            _ = tokio::spawn(a()) => {},
+            _ = tokio::spawn(a()) => {},
+            _ = tokio::spawn(a()) => {},
+            _ = dump() => {},
+        );
+    });
+}
+
+#[test]
+fn multi_thread() {
+    let rt = runtime::Builder::new_multi_thread()
+        .enable_all()
+        .worker_threads(3)
+        .build()
+        .unwrap();
+
+    async fn dump() {
+        let handle = Handle::current();
+        let dump = handle.dump().await;
+
+        let tasks: Vec<_> = dump.tasks().iter().collect();
+
+        assert_eq!(tasks.len(), 3);
+
+        for task in tasks {
+            let trace = task.trace().to_string();
+            eprintln!("\n\n{trace}\n\n");
+            assert!(trace.contains("dump::a"));
+            assert!(trace.contains("dump::b"));
+            assert!(trace.contains("dump::c"));
+            assert!(trace.contains("tokio::task::yield_now"));
+        }
+    }
+
+    rt.block_on(async {
+        tokio::select!(
+            biased;
+            _ = tokio::spawn(a()) => {},
+            _ = tokio::spawn(a()) => {},
+            _ = tokio::spawn(a()) => {},
+            _ = dump() => {},
+        );
+    });
+}
diff --git a/vendor/tokio/tests/fs.rs b/vendor/tokio/tests/fs.rs
index 13c44c08d..ba38b719f 100644
--- a/vendor/tokio/tests/fs.rs
+++ b/vendor/tokio/tests/fs.rs
@@ -1,5 +1,5 @@
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi does not support file operations
 
 use tokio::fs;
 use tokio_test::assert_ok;
diff --git a/vendor/tokio/tests/fs_canonicalize_dir.rs b/vendor/tokio/tests/fs_canonicalize_dir.rs
new file mode 100644
index 000000000..83f0d8137
--- /dev/null
+++ b/vendor/tokio/tests/fs_canonicalize_dir.rs
@@ -0,0 +1,22 @@
+#![warn(rust_2018_idioms)]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // WASI does not support all fs operations
+
+use tokio::fs;
+
+#[tokio::test]
+#[cfg(unix)]
+async fn canonicalize_root_dir_unix() {
+    assert_eq!(fs::canonicalize("/.").await.unwrap().to_str().unwrap(), "/");
+}
+
+#[tokio::test]
+#[cfg(windows)]
+async fn canonicalize_root_dir_windows() {
+    // 2-step let bindings due to Rust memory semantics
+    let dir_path = fs::canonicalize("C:\\.\\").await.unwrap();
+
+    let dir_name = dir_path.to_str().unwrap();
+
+    assert!(dir_name.starts_with("\\\\"));
+    assert!(dir_name.ends_with("C:\\"));
+}
diff --git a/vendor/tokio/tests/fs_copy.rs b/vendor/tokio/tests/fs_copy.rs
index 8d1632013..e6e5b666f 100644
--- a/vendor/tokio/tests/fs_copy.rs
+++ b/vendor/tokio/tests/fs_copy.rs
@@ -1,5 +1,5 @@
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // WASI does not support all fs operations
 
 use tempfile::tempdir;
 use tokio::fs;
diff --git a/vendor/tokio/tests/fs_dir.rs b/vendor/tokio/tests/fs_dir.rs
index 21efe8c0e..5f653cb21 100644
--- a/vendor/tokio/tests/fs_dir.rs
+++ b/vendor/tokio/tests/fs_dir.rs
@@ -1,5 +1,5 @@
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // WASI does not support all fs operations
 
 use tokio::fs;
 use tokio_test::{assert_err, assert_ok};
@@ -46,6 +46,27 @@ async fn build_dir() {
 }
 
 #[tokio::test]
+#[cfg(unix)]
+async fn build_dir_mode_read_only() {
+    let base_dir = tempdir().unwrap();
+    let new_dir = base_dir.path().join("abc");
+
+    assert_ok!(
+        fs::DirBuilder::new()
+            .recursive(true)
+            .mode(0o444)
+            .create(&new_dir)
+            .await
+    );
+
+    assert!(fs::metadata(new_dir)
+        .await
+        .expect("metadata result")
+        .permissions()
+        .readonly());
+}
+
+#[tokio::test]
 async fn remove() {
     let base_dir = tempdir().unwrap();
     let new_dir = base_dir.path().join("foo");
@@ -85,3 +106,21 @@ async fn read_inherent() {
         vec!["aa".to_string(), "bb".to_string(), "cc".to_string()]
     );
 }
+
+#[tokio::test]
+async fn read_dir_entry_info() {
+    let temp_dir = tempdir().unwrap();
+
+    let file_path = temp_dir.path().join("a.txt");
+
+    fs::write(&file_path, b"Hello File!").await.unwrap();
+
+    let mut dir = fs::read_dir(temp_dir.path()).await.unwrap();
+
+    let first_entry = dir.next_entry().await.unwrap().unwrap();
+
+    assert_eq!(first_entry.path(), file_path);
+    assert_eq!(first_entry.file_name(), "a.txt");
+    assert!(first_entry.metadata().await.unwrap().is_file());
+    assert!(first_entry.file_type().await.unwrap().is_file());
+}
diff --git a/vendor/tokio/tests/fs_file.rs b/vendor/tokio/tests/fs_file.rs
index bf2f1d7b5..94d872a57 100644
--- a/vendor/tokio/tests/fs_file.rs
+++ b/vendor/tokio/tests/fs_file.rs
@@ -1,12 +1,11 @@
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
-
-use tokio::fs::File;
-use tokio::io::{AsyncReadExt, AsyncSeekExt, AsyncWriteExt};
-use tokio_test::task;
+#![cfg(all(feature = "full", not(tokio_wasi)))] // WASI does not support all fs operations
 
 use std::io::prelude::*;
 use tempfile::NamedTempFile;
+use tokio::fs::File;
+use tokio::io::{AsyncReadExt, AsyncSeekExt, AsyncWriteExt, SeekFrom};
+use tokio_test::task;
 
 const HELLO: &[u8] = b"hello world...";
 
@@ -51,6 +50,19 @@ async fn basic_write_and_shutdown() {
 }
 
 #[tokio::test]
+async fn rewind_seek_position() {
+    let tempfile = tempfile();
+
+    let mut file = File::create(tempfile.path()).await.unwrap();
+
+    file.seek(SeekFrom::Current(10)).await.unwrap();
+
+    file.rewind().await.unwrap();
+
+    assert_eq!(file.stream_position().await.unwrap(), 0);
+}
+
+#[tokio::test]
 async fn coop() {
     let mut tempfile = tempfile();
     tempfile.write_all(HELLO).unwrap();
@@ -61,7 +73,7 @@ async fn coop() {
         let mut buf = [0; 1024];
 
         loop {
-            file.read(&mut buf).await.unwrap();
+            let _ = file.read(&mut buf).await.unwrap();
             file.seek(std::io::SeekFrom::Start(0)).await.unwrap();
         }
     });
@@ -75,13 +87,93 @@ async fn coop() {
     panic!("did not yield");
 }
 
+#[tokio::test]
+async fn write_to_clone() {
+    let tempfile = tempfile();
+
+    let file = File::create(tempfile.path()).await.unwrap();
+    let mut clone = file.try_clone().await.unwrap();
+
+    clone.write_all(HELLO).await.unwrap();
+    clone.flush().await.unwrap();
+
+    let contents = std::fs::read(tempfile.path()).unwrap();
+    assert_eq!(contents, HELLO);
+}
+
+#[tokio::test]
+async fn write_into_std() {
+    let tempfile = tempfile();
+
+    let file = File::create(tempfile.path()).await.unwrap();
+    let mut std_file = file.into_std().await;
+
+    std_file.write_all(HELLO).unwrap();
+
+    let contents = std::fs::read(tempfile.path()).unwrap();
+    assert_eq!(contents, HELLO);
+}
+
+#[tokio::test]
+async fn write_into_std_immediate() {
+    let tempfile = tempfile();
+
+    let file = File::create(tempfile.path()).await.unwrap();
+    let mut std_file = file.try_into_std().unwrap();
+
+    std_file.write_all(HELLO).unwrap();
+
+    let contents = std::fs::read(tempfile.path()).unwrap();
+    assert_eq!(contents, HELLO);
+}
+
+#[tokio::test]
+async fn read_file_from_std() {
+    let mut tempfile = tempfile();
+    tempfile.write_all(HELLO).unwrap();
+
+    let std_file = std::fs::File::open(tempfile.path()).unwrap();
+    let mut file = File::from(std_file);
+
+    let mut buf = [0; 1024];
+    let n = file.read(&mut buf).await.unwrap();
+    assert_eq!(n, HELLO.len());
+    assert_eq!(&buf[..n], HELLO);
+}
+
 fn tempfile() -> NamedTempFile {
     NamedTempFile::new().unwrap()
 }
 
 #[tokio::test]
 #[cfg(unix)]
-async fn unix_fd() {
+async fn file_debug_fmt() {
+    let tempfile = tempfile();
+
+    let file = File::open(tempfile.path()).await.unwrap();
+
+    assert_eq!(
+        &format!("{:?}", file)[0..33],
+        "tokio::fs::File { std: File { fd:"
+    );
+}
+
+#[tokio::test]
+#[cfg(windows)]
+async fn file_debug_fmt() {
+    let tempfile = tempfile();
+
+    let file = File::open(tempfile.path()).await.unwrap();
+
+    assert_eq!(
+        &format!("{:?}", file)[0..37],
+        "tokio::fs::File { std: File { handle:"
+    );
+}
+
+#[tokio::test]
+#[cfg(unix)]
+async fn unix_fd_is_valid() {
     use std::os::unix::io::AsRawFd;
     let tempfile = tempfile();
 
@@ -90,6 +182,26 @@ async fn unix_fd() {
 }
 
 #[tokio::test]
+#[cfg(unix)]
+async fn read_file_from_unix_fd() {
+    use std::os::unix::io::{FromRawFd, IntoRawFd};
+
+    let mut tempfile = tempfile();
+    tempfile.write_all(HELLO).unwrap();
+
+    let file1 = File::open(tempfile.path()).await.unwrap();
+    let raw_fd = file1.into_std().await.into_raw_fd();
+    assert!(raw_fd > 0);
+
+    let mut file2 = unsafe { File::from_raw_fd(raw_fd) };
+
+    let mut buf = [0; 1024];
+    let n = file2.read(&mut buf).await.unwrap();
+    assert_eq!(n, HELLO.len());
+    assert_eq!(&buf[..n], HELLO);
+}
+
+#[tokio::test]
 #[cfg(windows)]
 async fn windows_handle() {
     use std::os::windows::io::AsRawHandle;
diff --git a/vendor/tokio/tests/fs_link.rs b/vendor/tokio/tests/fs_link.rs
index 2ef666fb2..681b56660 100644
--- a/vendor/tokio/tests/fs_link.rs
+++ b/vendor/tokio/tests/fs_link.rs
@@ -1,10 +1,9 @@
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // WASI does not support all fs operations
 
 use tokio::fs;
 
-use std::io::prelude::*;
-use std::io::BufReader;
+use std::io::Write;
 use tempfile::tempdir;
 
 #[tokio::test]
@@ -13,24 +12,23 @@ async fn test_hard_link() {
     let src = dir.path().join("src.txt");
     let dst = dir.path().join("dst.txt");
 
-    {
-        let mut file = std::fs::File::create(&src).unwrap();
-        file.write_all(b"hello").unwrap();
-    }
+    std::fs::File::create(&src)
+        .unwrap()
+        .write_all(b"hello")
+        .unwrap();
 
-    let dst_2 = dst.clone();
+    fs::hard_link(&src, &dst).await.unwrap();
 
-    assert!(fs::hard_link(src, dst_2.clone()).await.is_ok());
+    std::fs::File::create(&src)
+        .unwrap()
+        .write_all(b"new-data")
+        .unwrap();
 
-    let mut content = String::new();
+    let content = fs::read(&dst).await.unwrap();
+    assert_eq!(content, b"new-data");
 
-    {
-        let file = std::fs::File::open(dst).unwrap();
-        let mut reader = BufReader::new(file);
-        reader.read_to_string(&mut content).unwrap();
-    }
-
-    assert!(content == "hello");
+    // test that this is not a symlink:
+    assert!(fs::read_link(&dst).await.is_err());
 }
 
 #[cfg(unix)]
@@ -40,25 +38,20 @@ async fn test_symlink() {
     let src = dir.path().join("src.txt");
     let dst = dir.path().join("dst.txt");
 
-    {
-        let mut file = std::fs::File::create(&src).unwrap();
-        file.write_all(b"hello").unwrap();
-    }
-
-    let src_2 = src.clone();
-    let dst_2 = dst.clone();
-
-    assert!(fs::symlink(src_2.clone(), dst_2.clone()).await.is_ok());
+    std::fs::File::create(&src)
+        .unwrap()
+        .write_all(b"hello")
+        .unwrap();
 
-    let mut content = String::new();
+    fs::symlink(&src, &dst).await.unwrap();
 
-    {
-        let file = std::fs::File::open(dst.clone()).unwrap();
-        let mut reader = BufReader::new(file);
-        reader.read_to_string(&mut content).unwrap();
-    }
+    std::fs::File::create(&src)
+        .unwrap()
+        .write_all(b"new-data")
+        .unwrap();
 
-    assert!(content == "hello");
+    let content = fs::read(&dst).await.unwrap();
+    assert_eq!(content, b"new-data");
 
     let read = fs::read_link(dst.clone()).await.unwrap();
     assert!(read == src);
diff --git a/vendor/tokio/tests/fs_open_options.rs b/vendor/tokio/tests/fs_open_options.rs
new file mode 100644
index 000000000..e8d8b51b3
--- /dev/null
+++ b/vendor/tokio/tests/fs_open_options.rs
@@ -0,0 +1,80 @@
+#![warn(rust_2018_idioms)]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // WASI does not support all fs operations
+
+use std::io::Write;
+use tempfile::NamedTempFile;
+use tokio::fs::OpenOptions;
+use tokio::io::AsyncReadExt;
+
+const HELLO: &[u8] = b"hello world...";
+
+#[tokio::test]
+async fn open_with_open_options_and_read() {
+    let mut tempfile = NamedTempFile::new().unwrap();
+    tempfile.write_all(HELLO).unwrap();
+
+    let mut file = OpenOptions::new().read(true).open(tempfile).await.unwrap();
+
+    let mut buf = [0; 1024];
+    let n = file.read(&mut buf).await.unwrap();
+
+    assert_eq!(n, HELLO.len());
+    assert_eq!(&buf[..n], HELLO);
+}
+
+#[tokio::test]
+async fn open_options_write() {
+    // TESTING HACK: use Debug output to check the stored data
+    assert!(format!("{:?}", OpenOptions::new().write(true)).contains("write: true"));
+}
+
+#[tokio::test]
+async fn open_options_append() {
+    // TESTING HACK: use Debug output to check the stored data
+    assert!(format!("{:?}", OpenOptions::new().append(true)).contains("append: true"));
+}
+
+#[tokio::test]
+async fn open_options_truncate() {
+    // TESTING HACK: use Debug output to check the stored data
+    assert!(format!("{:?}", OpenOptions::new().truncate(true)).contains("truncate: true"));
+}
+
+#[tokio::test]
+async fn open_options_create() {
+    // TESTING HACK: use Debug output to check the stored data
+    assert!(format!("{:?}", OpenOptions::new().create(true)).contains("create: true"));
+}
+
+#[tokio::test]
+async fn open_options_create_new() {
+    // TESTING HACK: use Debug output to check the stored data
+    assert!(format!("{:?}", OpenOptions::new().create_new(true)).contains("create_new: true"));
+}
+
+#[tokio::test]
+#[cfg(unix)]
+async fn open_options_mode() {
+    // TESTING HACK: use Debug output to check the stored data
+    assert!(format!("{:?}", OpenOptions::new().mode(0o644)).contains("mode: 420 "));
+}
+
+#[tokio::test]
+#[cfg(target_os = "linux")]
+async fn open_options_custom_flags_linux() {
+    // TESTING HACK: use Debug output to check the stored data
+    assert!(
+        format!("{:?}", OpenOptions::new().custom_flags(libc::O_TRUNC))
+            .contains("custom_flags: 512,")
+    );
+}
+
+#[tokio::test]
+#[cfg(any(target_os = "freebsd", target_os = "macos"))]
+async fn open_options_custom_flags_bsd_family() {
+    // TESTING HACK: use Debug output to check the stored data
+    assert!(
+        format!("{:?}", OpenOptions::new().custom_flags(libc::O_NOFOLLOW))
+            .contains("custom_flags: 256,")
+    );
+}
diff --git a/vendor/tokio/tests/fs_open_options_windows.rs b/vendor/tokio/tests/fs_open_options_windows.rs
new file mode 100644
index 000000000..398e6a12b
--- /dev/null
+++ b/vendor/tokio/tests/fs_open_options_windows.rs
@@ -0,0 +1,51 @@
+#![warn(rust_2018_idioms)]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // WASI does not support all fs operations
+#![cfg(windows)]
+
+use tokio::fs::OpenOptions;
+use windows_sys::Win32::Storage::FileSystem;
+
+#[tokio::test]
+#[cfg(windows)]
+async fn open_options_windows_access_mode() {
+    // TESTING HACK: use Debug output to check the stored data
+    assert!(format!("{:?}", OpenOptions::new().access_mode(0)).contains("access_mode: Some(0)"));
+}
+
+#[tokio::test]
+#[cfg(windows)]
+async fn open_options_windows_share_mode() {
+    // TESTING HACK: use Debug output to check the stored data
+    assert!(format!("{:?}", OpenOptions::new().share_mode(0)).contains("share_mode: 0,"));
+}
+
+#[tokio::test]
+#[cfg(windows)]
+async fn open_options_windows_custom_flags() {
+    // TESTING HACK: use Debug output to check the stored data
+    assert!(format!(
+        "{:?}",
+        OpenOptions::new().custom_flags(FileSystem::FILE_FLAG_DELETE_ON_CLOSE)
+    )
+    .contains("custom_flags: 67108864,"));
+}
+
+#[tokio::test]
+#[cfg(windows)]
+async fn open_options_windows_attributes() {
+    assert!(format!(
+        "{:?}",
+        OpenOptions::new().attributes(FileSystem::FILE_ATTRIBUTE_HIDDEN)
+    )
+    .contains("attributes: 2,"));
+}
+
+#[tokio::test]
+#[cfg(windows)]
+async fn open_options_windows_security_qos_flags() {
+    assert!(format!(
+        "{:?}",
+        OpenOptions::new().security_qos_flags(FileSystem::SECURITY_IDENTIFICATION)
+    )
+    .contains("security_qos_flags: 1114112,"));
+}
diff --git a/vendor/tokio/tests/fs_remove_dir_all.rs b/vendor/tokio/tests/fs_remove_dir_all.rs
new file mode 100644
index 000000000..53a2fd34f
--- /dev/null
+++ b/vendor/tokio/tests/fs_remove_dir_all.rs
@@ -0,0 +1,31 @@
+#![warn(rust_2018_idioms)]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // WASI does not support all fs operations
+
+use tempfile::tempdir;
+use tokio::fs;
+
+#[tokio::test]
+async fn remove_dir_all() {
+    let temp_dir = tempdir().unwrap();
+
+    let test_dir = temp_dir.path().join("test");
+    fs::create_dir(&test_dir).await.unwrap();
+
+    let file_path = test_dir.as_path().join("a.txt");
+
+    fs::write(&file_path, b"Hello File!").await.unwrap();
+
+    fs::remove_dir_all(test_dir.as_path()).await.unwrap();
+
+    // test dir should no longer exist
+    match fs::try_exists(test_dir).await {
+        Ok(exists) => assert!(!exists),
+        Err(_) => println!("ignored try_exists error after remove_dir_all"),
+    };
+
+    // contents should no longer exist
+    match fs::try_exists(file_path).await {
+        Ok(exists) => assert!(!exists),
+        Err(_) => println!("ignored try_exists error after remove_dir_all"),
+    };
+}
diff --git a/vendor/tokio/tests/fs_remove_file.rs b/vendor/tokio/tests/fs_remove_file.rs
new file mode 100644
index 000000000..14fd680da
--- /dev/null
+++ b/vendor/tokio/tests/fs_remove_file.rs
@@ -0,0 +1,24 @@
+#![warn(rust_2018_idioms)]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // WASI does not support all fs operations
+
+use tempfile::tempdir;
+use tokio::fs;
+
+#[tokio::test]
+async fn remove_file() {
+    let temp_dir = tempdir().unwrap();
+
+    let file_path = temp_dir.path().join("a.txt");
+
+    fs::write(&file_path, b"Hello File!").await.unwrap();
+
+    assert!(fs::try_exists(&file_path).await.unwrap());
+
+    fs::remove_file(&file_path).await.unwrap();
+
+    // should no longer exist
+    match fs::try_exists(file_path).await {
+        Ok(exists) => assert!(!exists),
+        Err(_) => println!("ignored try_exists error after remove_file"),
+    };
+}
diff --git a/vendor/tokio/tests/fs_rename.rs b/vendor/tokio/tests/fs_rename.rs
new file mode 100644
index 000000000..382fea079
--- /dev/null
+++ b/vendor/tokio/tests/fs_rename.rs
@@ -0,0 +1,28 @@
+#![warn(rust_2018_idioms)]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // WASI does not support all fs operations
+
+use tempfile::tempdir;
+use tokio::fs;
+
+#[tokio::test]
+async fn rename_file() {
+    let temp_dir = tempdir().unwrap();
+
+    let file_path = temp_dir.path().join("a.txt");
+
+    fs::write(&file_path, b"Hello File!").await.unwrap();
+
+    assert!(fs::try_exists(&file_path).await.unwrap());
+
+    let new_file_path = temp_dir.path().join("b.txt");
+
+    fs::rename(&file_path, &new_file_path).await.unwrap();
+
+    assert!(fs::try_exists(new_file_path).await.unwrap());
+
+    // original file should no longer exist
+    match fs::try_exists(file_path).await {
+        Ok(exists) => assert!(!exists),
+        Err(_) => println!("ignored try_exists error after rename"),
+    };
+}
diff --git a/vendor/tokio/tests/fs_symlink_dir_windows.rs b/vendor/tokio/tests/fs_symlink_dir_windows.rs
new file mode 100644
index 000000000..d80354268
--- /dev/null
+++ b/vendor/tokio/tests/fs_symlink_dir_windows.rs
@@ -0,0 +1,31 @@
+#![warn(rust_2018_idioms)]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // WASI does not support all fs operations
+#![cfg(windows)]
+
+use tempfile::tempdir;
+use tokio::fs;
+
+#[tokio::test]
+async fn symlink_file_windows() {
+    const FILE_NAME: &str = "abc.txt";
+
+    let temp_dir = tempdir().unwrap();
+
+    let dir1 = temp_dir.path().join("a");
+    fs::create_dir(&dir1).await.unwrap();
+
+    let file1 = dir1.as_path().join(FILE_NAME);
+    fs::write(&file1, b"Hello File!").await.unwrap();
+
+    let dir2 = temp_dir.path().join("b");
+    fs::symlink_dir(&dir1, &dir2).await.unwrap();
+
+    fs::write(&file1, b"new data!").await.unwrap();
+
+    let file2 = dir2.as_path().join(FILE_NAME);
+
+    let from = fs::read(&file1).await.unwrap();
+    let to = fs::read(&file2).await.unwrap();
+
+    assert_eq!(from, to);
+}
diff --git a/vendor/tokio/tests/fs_symlink_file_windows.rs b/vendor/tokio/tests/fs_symlink_file_windows.rs
new file mode 100644
index 000000000..50eaf8aab
--- /dev/null
+++ b/vendor/tokio/tests/fs_symlink_file_windows.rs
@@ -0,0 +1,24 @@
+#![warn(rust_2018_idioms)]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // WASI does not support all fs operations
+#![cfg(windows)]
+
+use tempfile::tempdir;
+use tokio::fs;
+
+#[tokio::test]
+async fn symlink_file_windows() {
+    let dir = tempdir().unwrap();
+
+    let source_path = dir.path().join("foo.txt");
+    let dest_path = dir.path().join("bar.txt");
+
+    fs::write(&source_path, b"Hello File!").await.unwrap();
+    fs::symlink_file(&source_path, &dest_path).await.unwrap();
+
+    fs::write(&source_path, b"new data!").await.unwrap();
+
+    let from = fs::read(&source_path).await.unwrap();
+    let to = fs::read(&dest_path).await.unwrap();
+
+    assert_eq!(from, to);
+}
diff --git a/vendor/tokio/tests/fs_try_exists.rs b/vendor/tokio/tests/fs_try_exists.rs
new file mode 100644
index 000000000..00d236500
--- /dev/null
+++ b/vendor/tokio/tests/fs_try_exists.rs
@@ -0,0 +1,44 @@
+#![warn(rust_2018_idioms)]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // WASI does not support all fs operations
+
+use tempfile::tempdir;
+use tokio::fs;
+
+#[tokio::test]
+async fn try_exists() {
+    let dir = tempdir().unwrap();
+
+    let existing_path = dir.path().join("foo.txt");
+    fs::write(&existing_path, b"Hello File!").await.unwrap();
+    let nonexisting_path = dir.path().join("bar.txt");
+
+    assert!(fs::try_exists(existing_path).await.unwrap());
+    assert!(!fs::try_exists(nonexisting_path).await.unwrap());
+    // FreeBSD root user always has permission to stat.
+    #[cfg(all(unix, not(target_os = "freebsd")))]
+    {
+        use std::os::unix::prelude::PermissionsExt;
+        let permission_denied_directory_path = dir.path().join("baz");
+        fs::create_dir(&permission_denied_directory_path)
+            .await
+            .unwrap();
+        let permission_denied_file_path = permission_denied_directory_path.join("baz.txt");
+        fs::write(&permission_denied_file_path, b"Hello File!")
+            .await
+            .unwrap();
+        let mut perms = tokio::fs::metadata(&permission_denied_directory_path)
+            .await
+            .unwrap()
+            .permissions();
+
+        perms.set_mode(0o244);
+        fs::set_permissions(&permission_denied_directory_path, perms)
+            .await
+            .unwrap();
+        let permission_denied_result = fs::try_exists(permission_denied_file_path).await;
+        assert_eq!(
+            permission_denied_result.err().unwrap().kind(),
+            std::io::ErrorKind::PermissionDenied
+        );
+    }
+}
diff --git a/vendor/tokio/tests/io_async_fd.rs b/vendor/tokio/tests/io_async_fd.rs
index dc21e426f..cdbfbacd0 100644
--- a/vendor/tokio/tests/io_async_fd.rs
+++ b/vendor/tokio/tests/io_async_fd.rs
@@ -15,7 +15,7 @@ use std::{
 
 use nix::unistd::{close, read, write};
 
-use futures::{poll, FutureExt};
+use futures::poll;
 
 use tokio::io::unix::{AsyncFd, AsyncFdReadyGuard};
 use tokio_test::{assert_err, assert_pending};
@@ -163,10 +163,11 @@ async fn initially_writable() {
     afd_a.writable().await.unwrap().clear_ready();
     afd_b.writable().await.unwrap().clear_ready();
 
-    futures::select_biased! {
-        _ = tokio::time::sleep(Duration::from_millis(10)).fuse() => {},
-        _ = afd_a.readable().fuse() => panic!("Unexpected readable state"),
-        _ = afd_b.readable().fuse() => panic!("Unexpected readable state"),
+    tokio::select! {
+        biased;
+        _ = tokio::time::sleep(Duration::from_millis(10)) => {},
+        _ = afd_a.readable() => panic!("Unexpected readable state"),
+        _ = afd_b.readable() => panic!("Unexpected readable state"),
     }
 }
 
@@ -353,12 +354,13 @@ async fn multiple_waiters() {
                 futures::future::pending::<()>().await;
             };
 
-            futures::select_biased! {
-                guard = afd_a.readable().fuse() => {
+            tokio::select! {
+                biased;
+                guard = afd_a.readable() => {
                     tokio::task::yield_now().await;
                     guard.unwrap().clear_ready()
                 },
-                _ = notify_barrier.fuse() => unreachable!(),
+                _ = notify_barrier => unreachable!(),
             }
 
             std::mem::drop(afd_a);
@@ -597,3 +599,89 @@ fn driver_shutdown_wakes_poll_race() {
         assert_err!(futures::executor::block_on(poll_writable(&afd_a)));
     }
 }
+
+#[tokio::test]
+#[cfg(any(target_os = "linux", target_os = "android"))]
+async fn priority_event_on_oob_data() {
+    use std::net::SocketAddr;
+
+    use tokio::io::Interest;
+
+    let addr: SocketAddr = "127.0.0.1:0".parse().unwrap();
+
+    let listener = std::net::TcpListener::bind(addr).unwrap();
+    let addr = listener.local_addr().unwrap();
+
+    let client = std::net::TcpStream::connect(addr).unwrap();
+    let client = AsyncFd::with_interest(client, Interest::PRIORITY).unwrap();
+
+    let (stream, _) = listener.accept().unwrap();
+
+    // Sending out of band data should trigger priority event.
+    send_oob_data(&stream, b"hello").unwrap();
+
+    let _ = client.ready(Interest::PRIORITY).await.unwrap();
+}
+
+#[cfg(any(target_os = "linux", target_os = "android"))]
+fn send_oob_data<S: AsRawFd>(stream: &S, data: &[u8]) -> io::Result<usize> {
+    unsafe {
+        let res = libc::send(
+            stream.as_raw_fd(),
+            data.as_ptr().cast(),
+            data.len(),
+            libc::MSG_OOB,
+        );
+        if res == -1 {
+            Err(io::Error::last_os_error())
+        } else {
+            Ok(res as usize)
+        }
+    }
+}
+
+#[tokio::test]
+async fn clear_ready_matching_clears_ready() {
+    use tokio::io::{Interest, Ready};
+
+    let (a, mut b) = socketpair();
+
+    let afd_a = AsyncFd::new(a).unwrap();
+    b.write_all(b"0").unwrap();
+
+    let mut guard = afd_a
+        .ready(Interest::READABLE | Interest::WRITABLE)
+        .await
+        .unwrap();
+
+    assert_eq!(guard.ready(), Ready::READABLE | Ready::WRITABLE);
+
+    guard.clear_ready_matching(Ready::READABLE);
+    assert_eq!(guard.ready(), Ready::WRITABLE);
+
+    guard.clear_ready_matching(Ready::WRITABLE);
+    assert_eq!(guard.ready(), Ready::EMPTY);
+}
+
+#[tokio::test]
+async fn clear_ready_matching_clears_ready_mut() {
+    use tokio::io::{Interest, Ready};
+
+    let (a, mut b) = socketpair();
+
+    let mut afd_a = AsyncFd::new(a).unwrap();
+    b.write_all(b"0").unwrap();
+
+    let mut guard = afd_a
+        .ready_mut(Interest::READABLE | Interest::WRITABLE)
+        .await
+        .unwrap();
+
+    assert_eq!(guard.ready(), Ready::READABLE | Ready::WRITABLE);
+
+    guard.clear_ready_matching(Ready::READABLE);
+    assert_eq!(guard.ready(), Ready::WRITABLE);
+
+    guard.clear_ready_matching(Ready::WRITABLE);
+    assert_eq!(guard.ready(), Ready::EMPTY);
+}
diff --git a/vendor/tokio/tests/io_buf_reader.rs b/vendor/tokio/tests/io_buf_reader.rs
index c72c058d7..0d3f6bafc 100644
--- a/vendor/tokio/tests/io_buf_reader.rs
+++ b/vendor/tokio/tests/io_buf_reader.rs
@@ -8,9 +8,11 @@ use std::cmp;
 use std::io::{self, Cursor};
 use std::pin::Pin;
 use tokio::io::{
-    AsyncBufRead, AsyncBufReadExt, AsyncRead, AsyncReadExt, AsyncSeek, AsyncSeekExt, BufReader,
-    ReadBuf, SeekFrom,
+    AsyncBufRead, AsyncBufReadExt, AsyncRead, AsyncReadExt, AsyncSeek, AsyncSeekExt, AsyncWriteExt,
+    BufReader, ReadBuf, SeekFrom,
 };
+use tokio_test::task::spawn;
+use tokio_test::{assert_pending, assert_ready};
 
 macro_rules! run_fill_buf {
     ($reader:expr) => {{
@@ -348,3 +350,30 @@ async fn maybe_pending_seek() {
     Pin::new(&mut reader).consume(1);
     assert_eq!(reader.seek(SeekFrom::Current(-2)).await.unwrap(), 3);
 }
+
+// This tests the AsyncBufReadExt::fill_buf wrapper.
+#[tokio::test]
+async fn test_fill_buf_wrapper() {
+    let (mut write, read) = tokio::io::duplex(16);
+
+    let mut read = BufReader::new(read);
+    write.write_all(b"hello world").await.unwrap();
+
+    assert_eq!(read.fill_buf().await.unwrap(), b"hello world");
+    read.consume(b"hello ".len());
+    assert_eq!(read.fill_buf().await.unwrap(), b"world");
+    assert_eq!(read.fill_buf().await.unwrap(), b"world");
+    read.consume(b"world".len());
+
+    let mut fill = spawn(read.fill_buf());
+    assert_pending!(fill.poll());
+
+    write.write_all(b"foo bar").await.unwrap();
+    assert_eq!(assert_ready!(fill.poll()).unwrap(), b"foo bar");
+    drop(fill);
+
+    drop(write);
+    assert_eq!(read.fill_buf().await.unwrap(), b"foo bar");
+    read.consume(b"foo bar".len());
+    assert_eq!(read.fill_buf().await.unwrap(), b"");
+}
diff --git a/vendor/tokio/tests/io_buf_writer.rs b/vendor/tokio/tests/io_buf_writer.rs
index 47a0d466f..d3acf62c7 100644
--- a/vendor/tokio/tests/io_buf_writer.rs
+++ b/vendor/tokio/tests/io_buf_writer.rs
@@ -70,15 +70,15 @@ where
 async fn buf_writer() {
     let mut writer = BufWriter::with_capacity(2, Vec::new());
 
-    writer.write(&[0, 1]).await.unwrap();
+    assert_eq!(writer.write(&[0, 1]).await.unwrap(), 2);
     assert_eq!(writer.buffer(), []);
     assert_eq!(*writer.get_ref(), [0, 1]);
 
-    writer.write(&[2]).await.unwrap();
+    assert_eq!(writer.write(&[2]).await.unwrap(), 1);
     assert_eq!(writer.buffer(), [2]);
     assert_eq!(*writer.get_ref(), [0, 1]);
 
-    writer.write(&[3]).await.unwrap();
+    assert_eq!(writer.write(&[3]).await.unwrap(), 1);
     assert_eq!(writer.buffer(), [2, 3]);
     assert_eq!(*writer.get_ref(), [0, 1]);
 
@@ -86,20 +86,20 @@ async fn buf_writer() {
     assert_eq!(writer.buffer(), []);
     assert_eq!(*writer.get_ref(), [0, 1, 2, 3]);
 
-    writer.write(&[4]).await.unwrap();
-    writer.write(&[5]).await.unwrap();
+    assert_eq!(writer.write(&[4]).await.unwrap(), 1);
+    assert_eq!(writer.write(&[5]).await.unwrap(), 1);
     assert_eq!(writer.buffer(), [4, 5]);
     assert_eq!(*writer.get_ref(), [0, 1, 2, 3]);
 
-    writer.write(&[6]).await.unwrap();
+    assert_eq!(writer.write(&[6]).await.unwrap(), 1);
     assert_eq!(writer.buffer(), [6]);
     assert_eq!(*writer.get_ref(), [0, 1, 2, 3, 4, 5]);
 
-    writer.write(&[7, 8]).await.unwrap();
+    assert_eq!(writer.write(&[7, 8]).await.unwrap(), 2);
     assert_eq!(writer.buffer(), []);
     assert_eq!(*writer.get_ref(), [0, 1, 2, 3, 4, 5, 6, 7, 8]);
 
-    writer.write(&[9, 10, 11]).await.unwrap();
+    assert_eq!(writer.write(&[9, 10, 11]).await.unwrap(), 3);
     assert_eq!(writer.buffer(), []);
     assert_eq!(*writer.get_ref(), [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]);
 
@@ -111,7 +111,7 @@ async fn buf_writer() {
 #[tokio::test]
 async fn buf_writer_inner_flushes() {
     let mut w = BufWriter::with_capacity(3, Vec::new());
-    w.write(&[0, 1]).await.unwrap();
+    assert_eq!(w.write(&[0, 1]).await.unwrap(), 2);
     assert_eq!(*w.get_ref(), []);
     w.flush().await.unwrap();
     let w = w.into_inner();
@@ -135,15 +135,15 @@ async fn buf_writer_seek() {
 async fn maybe_pending_buf_writer() {
     let mut writer = BufWriter::with_capacity(2, MaybePending::new(Vec::new()));
 
-    writer.write(&[0, 1]).await.unwrap();
+    assert_eq!(writer.write(&[0, 1]).await.unwrap(), 2);
     assert_eq!(writer.buffer(), []);
     assert_eq!(&writer.get_ref().inner, &[0, 1]);
 
-    writer.write(&[2]).await.unwrap();
+    assert_eq!(writer.write(&[2]).await.unwrap(), 1);
     assert_eq!(writer.buffer(), [2]);
     assert_eq!(&writer.get_ref().inner, &[0, 1]);
 
-    writer.write(&[3]).await.unwrap();
+    assert_eq!(writer.write(&[3]).await.unwrap(), 1);
     assert_eq!(writer.buffer(), [2, 3]);
     assert_eq!(&writer.get_ref().inner, &[0, 1]);
 
@@ -151,20 +151,20 @@ async fn maybe_pending_buf_writer() {
     assert_eq!(writer.buffer(), []);
     assert_eq!(&writer.get_ref().inner, &[0, 1, 2, 3]);
 
-    writer.write(&[4]).await.unwrap();
-    writer.write(&[5]).await.unwrap();
+    assert_eq!(writer.write(&[4]).await.unwrap(), 1);
+    assert_eq!(writer.write(&[5]).await.unwrap(), 1);
     assert_eq!(writer.buffer(), [4, 5]);
     assert_eq!(&writer.get_ref().inner, &[0, 1, 2, 3]);
 
-    writer.write(&[6]).await.unwrap();
+    assert_eq!(writer.write(&[6]).await.unwrap(), 1);
     assert_eq!(writer.buffer(), [6]);
     assert_eq!(writer.get_ref().inner, &[0, 1, 2, 3, 4, 5]);
 
-    writer.write(&[7, 8]).await.unwrap();
+    assert_eq!(writer.write(&[7, 8]).await.unwrap(), 2);
     assert_eq!(writer.buffer(), []);
     assert_eq!(writer.get_ref().inner, &[0, 1, 2, 3, 4, 5, 6, 7, 8]);
 
-    writer.write(&[9, 10, 11]).await.unwrap();
+    assert_eq!(writer.write(&[9, 10, 11]).await.unwrap(), 3);
     assert_eq!(writer.buffer(), []);
     assert_eq!(
         writer.get_ref().inner,
@@ -182,7 +182,7 @@ async fn maybe_pending_buf_writer() {
 #[tokio::test]
 async fn maybe_pending_buf_writer_inner_flushes() {
     let mut w = BufWriter::with_capacity(3, MaybePending::new(Vec::new()));
-    w.write(&[0, 1]).await.unwrap();
+    assert_eq!(w.write(&[0, 1]).await.unwrap(), 2);
     assert_eq!(&w.get_ref().inner, &[]);
     w.flush().await.unwrap();
     let w = w.into_inner().inner;
diff --git a/vendor/tokio/tests/io_copy.rs b/vendor/tokio/tests/io_copy.rs
index 9ed7995c7..005e17011 100644
--- a/vendor/tokio/tests/io_copy.rs
+++ b/vendor/tokio/tests/io_copy.rs
@@ -1,7 +1,9 @@
 #![warn(rust_2018_idioms)]
 #![cfg(feature = "full")]
 
-use tokio::io::{self, AsyncRead, ReadBuf};
+use bytes::BytesMut;
+use futures::ready;
+use tokio::io::{self, AsyncRead, AsyncReadExt, AsyncWrite, AsyncWriteExt, ReadBuf};
 use tokio_test::assert_ok;
 
 use std::pin::Pin;
@@ -34,3 +36,52 @@ async fn copy() {
     assert_eq!(n, 11);
     assert_eq!(wr, b"hello world");
 }
+
+#[tokio::test]
+async fn proxy() {
+    struct BufferedWd {
+        buf: BytesMut,
+        writer: io::DuplexStream,
+    }
+
+    impl AsyncWrite for BufferedWd {
+        fn poll_write(
+            self: Pin<&mut Self>,
+            _cx: &mut Context<'_>,
+            buf: &[u8],
+        ) -> Poll<io::Result<usize>> {
+            self.get_mut().buf.extend_from_slice(buf);
+            Poll::Ready(Ok(buf.len()))
+        }
+
+        fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+            let this = self.get_mut();
+
+            while !this.buf.is_empty() {
+                let n = ready!(Pin::new(&mut this.writer).poll_write(cx, &this.buf))?;
+                let _ = this.buf.split_to(n);
+            }
+
+            Pin::new(&mut this.writer).poll_flush(cx)
+        }
+
+        fn poll_shutdown(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+            Pin::new(&mut self.writer).poll_shutdown(cx)
+        }
+    }
+
+    let (rd, wd) = io::duplex(1024);
+    let mut rd = rd.take(1024);
+    let mut wd = BufferedWd {
+        buf: BytesMut::new(),
+        writer: wd,
+    };
+
+    // write start bytes
+    assert_ok!(wd.write_all(&[0x42; 512]).await);
+    assert_ok!(wd.flush().await);
+
+    let n = assert_ok!(io::copy(&mut rd, &mut wd).await);
+
+    assert_eq!(n, 1024);
+}
diff --git a/vendor/tokio/tests/io_copy_bidirectional.rs b/vendor/tokio/tests/io_copy_bidirectional.rs
index 0ce7f85c5..c54967595 100644
--- a/vendor/tokio/tests/io_copy_bidirectional.rs
+++ b/vendor/tokio/tests/io_copy_bidirectional.rs
@@ -1,5 +1,5 @@
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi does not support bind()
 
 use std::time::Duration;
 use tokio::io::{self, copy_bidirectional, AsyncReadExt, AsyncWriteExt};
@@ -26,7 +26,7 @@ async fn block_write(s: &mut TcpStream) -> usize {
             result = s.write(&BUF) => {
                 copied += result.expect("write error")
             },
-            _ = tokio::time::sleep(Duration::from_millis(100)) => {
+            _ = tokio::time::sleep(Duration::from_millis(10)) => {
                 break;
             }
         }
@@ -111,18 +111,30 @@ async fn blocking_one_side_does_not_block_other() {
 }
 
 #[tokio::test]
-async fn immediate_exit_on_error() {
-    symmetric(|handle, mut a, mut b| async move {
-        block_write(&mut a).await;
+async fn immediate_exit_on_write_error() {
+    let payload = b"here, take this";
+    let error = || io::Error::new(io::ErrorKind::Other, "no thanks!");
 
-        // Fill up the b->copy->a path. We expect that this will _not_ drain
-        // before we exit the copy task.
-        let _bytes_written = block_write(&mut b).await;
+    let mut a = tokio_test::io::Builder::new()
+        .read(payload)
+        .write_error(error())
+        .build();
 
-        // Drop b. We should not wait for a to consume the data buffered in the
-        // copy loop, since b will be failing writes.
-        drop(b);
-        assert!(handle.await.unwrap().is_err());
-    })
-    .await
+    let mut b = tokio_test::io::Builder::new()
+        .read(payload)
+        .write_error(error())
+        .build();
+
+    assert!(copy_bidirectional(&mut a, &mut b).await.is_err());
+}
+
+#[tokio::test]
+async fn immediate_exit_on_read_error() {
+    let error = || io::Error::new(io::ErrorKind::Other, "got nothing!");
+
+    let mut a = tokio_test::io::Builder::new().read_error(error()).build();
+
+    let mut b = tokio_test::io::Builder::new().read_error(error()).build();
+
+    assert!(copy_bidirectional(&mut a, &mut b).await.is_err());
 }
diff --git a/vendor/tokio/tests/io_driver.rs b/vendor/tokio/tests/io_driver.rs
index 6fb566de5..97018e0f9 100644
--- a/vendor/tokio/tests/io_driver.rs
+++ b/vendor/tokio/tests/io_driver.rs
@@ -1,5 +1,6 @@
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+// Wasi does not support panic recovery or threading
+#![cfg(all(feature = "full", not(tokio_wasi)))]
 
 use tokio::net::TcpListener;
 use tokio::runtime;
@@ -79,7 +80,7 @@ fn test_drop_on_notify() {
     drop(task);
 
     // Establish a connection to the acceptor
-    let _s = TcpStream::connect(&addr).unwrap();
+    let _s = TcpStream::connect(addr).unwrap();
 
     // Force the reactor to turn
     rt.block_on(async {});
diff --git a/vendor/tokio/tests/io_driver_drop.rs b/vendor/tokio/tests/io_driver_drop.rs
index 631e66e9f..0a384d419 100644
--- a/vendor/tokio/tests/io_driver_drop.rs
+++ b/vendor/tokio/tests/io_driver_drop.rs
@@ -1,5 +1,5 @@
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi does not support bind
 
 use tokio::net::TcpListener;
 use tokio::runtime;
diff --git a/vendor/tokio/tests/io_fill_buf.rs b/vendor/tokio/tests/io_fill_buf.rs
new file mode 100644
index 000000000..62c3f1b37
--- /dev/null
+++ b/vendor/tokio/tests/io_fill_buf.rs
@@ -0,0 +1,34 @@
+#![warn(rust_2018_idioms)]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi does not support file operations
+
+use tempfile::NamedTempFile;
+use tokio::fs::File;
+use tokio::io::{AsyncBufReadExt, BufReader};
+use tokio_test::assert_ok;
+
+#[tokio::test]
+async fn fill_buf_file() {
+    let file = NamedTempFile::new().unwrap();
+
+    assert_ok!(std::fs::write(file.path(), b"hello"));
+
+    let file = assert_ok!(File::open(file.path()).await);
+    let mut file = BufReader::new(file);
+
+    let mut contents = Vec::new();
+
+    loop {
+        let consumed = {
+            let buffer = assert_ok!(file.fill_buf().await);
+            if buffer.is_empty() {
+                break;
+            }
+            contents.extend_from_slice(buffer);
+            buffer.len()
+        };
+
+        file.consume(consumed);
+    }
+
+    assert_eq!(contents, b"hello");
+}
diff --git a/vendor/tokio/tests/io_mem_stream.rs b/vendor/tokio/tests/io_mem_stream.rs
index 01baa5369..e79ec4e9d 100644
--- a/vendor/tokio/tests/io_mem_stream.rs
+++ b/vendor/tokio/tests/io_mem_stream.rs
@@ -100,3 +100,22 @@ async fn max_write_size() {
     // drop b only after task t1 finishes writing
     drop(b);
 }
+
+#[tokio::test]
+async fn duplex_is_cooperative() {
+    let (mut tx, mut rx) = tokio::io::duplex(1024 * 8);
+
+    tokio::select! {
+        biased;
+
+        _ = async {
+            loop {
+                let buf = [3u8; 4096];
+                tx.write_all(&buf).await.unwrap();
+                let mut buf = [0u8; 4096];
+                let _ = rx.read(&mut buf).await.unwrap();
+            }
+        } => {},
+        _ = tokio::task::yield_now() => {}
+    }
+}
diff --git a/vendor/tokio/tests/io_panic.rs b/vendor/tokio/tests/io_panic.rs
new file mode 100644
index 000000000..922d7c076
--- /dev/null
+++ b/vendor/tokio/tests/io_panic.rs
@@ -0,0 +1,176 @@
+#![warn(rust_2018_idioms)]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi does not support panic recovery
+
+use std::task::{Context, Poll};
+use std::{error::Error, pin::Pin};
+use tokio::io::{self, split, AsyncRead, AsyncWrite, ReadBuf};
+
+mod support {
+    pub mod panic;
+}
+use support::panic::test_panic;
+
+struct RW;
+
+impl AsyncRead for RW {
+    fn poll_read(
+        self: Pin<&mut Self>,
+        _cx: &mut Context<'_>,
+        buf: &mut ReadBuf<'_>,
+    ) -> Poll<io::Result<()>> {
+        buf.put_slice(&[b'z']);
+        Poll::Ready(Ok(()))
+    }
+}
+
+impl AsyncWrite for RW {
+    fn poll_write(
+        self: Pin<&mut Self>,
+        _cx: &mut Context<'_>,
+        _buf: &[u8],
+    ) -> Poll<Result<usize, io::Error>> {
+        Poll::Ready(Ok(1))
+    }
+
+    fn poll_flush(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Result<(), io::Error>> {
+        Poll::Ready(Ok(()))
+    }
+
+    fn poll_shutdown(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Result<(), io::Error>> {
+        Poll::Ready(Ok(()))
+    }
+}
+
+#[cfg(unix)]
+mod unix {
+    use std::os::unix::prelude::{AsRawFd, RawFd};
+
+    pub struct MockFd;
+
+    impl AsRawFd for MockFd {
+        fn as_raw_fd(&self) -> RawFd {
+            0
+        }
+    }
+}
+
+#[test]
+fn read_buf_initialize_unfilled_to_panic_caller() -> Result<(), Box<dyn Error>> {
+    let panic_location_file = test_panic(|| {
+        let mut buffer = Vec::<u8>::new();
+        let mut read_buf = ReadBuf::new(&mut buffer);
+
+        read_buf.initialize_unfilled_to(2);
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+fn read_buf_advance_panic_caller() -> Result<(), Box<dyn Error>> {
+    let panic_location_file = test_panic(|| {
+        let mut buffer = Vec::<u8>::new();
+        let mut read_buf = ReadBuf::new(&mut buffer);
+
+        read_buf.advance(2);
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+fn read_buf_set_filled_panic_caller() -> Result<(), Box<dyn Error>> {
+    let panic_location_file = test_panic(|| {
+        let mut buffer = Vec::<u8>::new();
+        let mut read_buf = ReadBuf::new(&mut buffer);
+
+        read_buf.set_filled(2);
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+fn read_buf_put_slice_panic_caller() -> Result<(), Box<dyn Error>> {
+    let panic_location_file = test_panic(|| {
+        let mut buffer = Vec::<u8>::new();
+        let mut read_buf = ReadBuf::new(&mut buffer);
+
+        let new_slice = [0x40_u8, 0x41_u8];
+
+        read_buf.put_slice(&new_slice);
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+fn unsplit_panic_caller() -> Result<(), Box<dyn Error>> {
+    let panic_location_file = test_panic(|| {
+        let (r1, _w1) = split(RW);
+        let (_r2, w2) = split(RW);
+        r1.unsplit(w2);
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+#[cfg(unix)]
+fn async_fd_new_panic_caller() -> Result<(), Box<dyn Error>> {
+    use tokio::io::unix::AsyncFd;
+    use tokio::runtime::Builder;
+
+    let panic_location_file = test_panic(|| {
+        // Runtime without `enable_io` so it has no IO driver set.
+        let rt = Builder::new_current_thread().build().unwrap();
+        rt.block_on(async {
+            let fd = unix::MockFd;
+
+            let _ = AsyncFd::new(fd);
+        });
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+#[cfg(unix)]
+fn async_fd_with_interest_panic_caller() -> Result<(), Box<dyn Error>> {
+    use tokio::io::unix::AsyncFd;
+    use tokio::io::Interest;
+    use tokio::runtime::Builder;
+
+    let panic_location_file = test_panic(|| {
+        // Runtime without `enable_io` so it has no IO driver set.
+        let rt = Builder::new_current_thread().build().unwrap();
+        rt.block_on(async {
+            let fd = unix::MockFd;
+
+            let _ = AsyncFd::with_interest(fd, Interest::READABLE);
+        });
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
diff --git a/vendor/tokio/tests/io_poll_aio.rs b/vendor/tokio/tests/io_poll_aio.rs
new file mode 100644
index 000000000..f044af5cc
--- /dev/null
+++ b/vendor/tokio/tests/io_poll_aio.rs
@@ -0,0 +1,375 @@
+#![warn(rust_2018_idioms)]
+#![cfg(all(target_os = "freebsd", feature = "net"))]
+
+use mio_aio::{AioCb, AioFsyncMode, LioCb};
+use std::{
+    future::Future,
+    mem,
+    os::unix::io::{AsRawFd, RawFd},
+    pin::Pin,
+    task::{Context, Poll},
+};
+use tempfile::tempfile;
+use tokio::io::bsd::{Aio, AioSource};
+use tokio_test::assert_pending;
+
+mod aio {
+    use super::*;
+
+    /// Adapts mio_aio::AioCb (which implements mio::event::Source) to AioSource
+    struct WrappedAioCb<'a>(AioCb<'a>);
+    impl<'a> AioSource for WrappedAioCb<'a> {
+        fn register(&mut self, kq: RawFd, token: usize) {
+            self.0.register_raw(kq, token)
+        }
+        fn deregister(&mut self) {
+            self.0.deregister_raw()
+        }
+    }
+
+    /// A very crude implementation of an AIO-based future
+    struct FsyncFut(Aio<WrappedAioCb<'static>>);
+
+    impl Future for FsyncFut {
+        type Output = std::io::Result<()>;
+
+        fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+            let poll_result = self.0.poll_ready(cx);
+            match poll_result {
+                Poll::Pending => Poll::Pending,
+                Poll::Ready(Err(e)) => Poll::Ready(Err(e)),
+                Poll::Ready(Ok(_ev)) => {
+                    // At this point, we could clear readiness.  But there's no
+                    // point, since we're about to drop the Aio.
+                    let result = (*self.0).0.aio_return();
+                    match result {
+                        Ok(_) => Poll::Ready(Ok(())),
+                        Err(e) => Poll::Ready(Err(e.into())),
+                    }
+                }
+            }
+        }
+    }
+
+    /// Low-level AIO Source
+    ///
+    /// An example bypassing mio_aio and Nix to demonstrate how the kevent
+    /// registration actually works, under the hood.
+    struct LlSource(Pin<Box<libc::aiocb>>);
+
+    impl AioSource for LlSource {
+        fn register(&mut self, kq: RawFd, token: usize) {
+            let mut sev: libc::sigevent = unsafe { mem::MaybeUninit::zeroed().assume_init() };
+            sev.sigev_notify = libc::SIGEV_KEVENT;
+            sev.sigev_signo = kq;
+            sev.sigev_value = libc::sigval {
+                sival_ptr: token as *mut libc::c_void,
+            };
+            self.0.aio_sigevent = sev;
+        }
+
+        fn deregister(&mut self) {
+            unsafe {
+                self.0.aio_sigevent = mem::zeroed();
+            }
+        }
+    }
+
+    struct LlFut(Aio<LlSource>);
+
+    impl Future for LlFut {
+        type Output = std::io::Result<()>;
+
+        fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+            let poll_result = self.0.poll_ready(cx);
+            match poll_result {
+                Poll::Pending => Poll::Pending,
+                Poll::Ready(Err(e)) => Poll::Ready(Err(e)),
+                Poll::Ready(Ok(_ev)) => {
+                    let r = unsafe { libc::aio_return(self.0 .0.as_mut().get_unchecked_mut()) };
+                    assert_eq!(0, r);
+                    Poll::Ready(Ok(()))
+                }
+            }
+        }
+    }
+
+    /// A very simple object that can implement AioSource and can be reused.
+    ///
+    /// mio_aio normally assumes that each AioCb will be consumed on completion.
+    /// This somewhat contrived example shows how an Aio object can be reused
+    /// anyway.
+    struct ReusableFsyncSource {
+        aiocb: Pin<Box<AioCb<'static>>>,
+        fd: RawFd,
+        token: usize,
+    }
+    impl ReusableFsyncSource {
+        fn fsync(&mut self) {
+            self.aiocb.register_raw(self.fd, self.token);
+            self.aiocb.fsync(AioFsyncMode::O_SYNC).unwrap();
+        }
+        fn new(aiocb: AioCb<'static>) -> Self {
+            ReusableFsyncSource {
+                aiocb: Box::pin(aiocb),
+                fd: 0,
+                token: 0,
+            }
+        }
+        fn reset(&mut self, aiocb: AioCb<'static>) {
+            self.aiocb = Box::pin(aiocb);
+        }
+    }
+    impl AioSource for ReusableFsyncSource {
+        fn register(&mut self, kq: RawFd, token: usize) {
+            self.fd = kq;
+            self.token = token;
+        }
+        fn deregister(&mut self) {
+            self.fd = 0;
+        }
+    }
+
+    struct ReusableFsyncFut<'a>(&'a mut Aio<ReusableFsyncSource>);
+    impl<'a> Future for ReusableFsyncFut<'a> {
+        type Output = std::io::Result<()>;
+
+        fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+            let poll_result = self.0.poll_ready(cx);
+            match poll_result {
+                Poll::Pending => Poll::Pending,
+                Poll::Ready(Err(e)) => Poll::Ready(Err(e)),
+                Poll::Ready(Ok(ev)) => {
+                    // Since this future uses a reusable Aio, we must clear
+                    // its readiness here.  That makes the future
+                    // non-idempotent; the caller can't poll it repeatedly after
+                    // it has already returned Ready.  But that's ok; most
+                    // futures behave this way.
+                    self.0.clear_ready(ev);
+                    let result = (*self.0).aiocb.aio_return();
+                    match result {
+                        Ok(_) => Poll::Ready(Ok(())),
+                        Err(e) => Poll::Ready(Err(e.into())),
+                    }
+                }
+            }
+        }
+    }
+
+    #[tokio::test]
+    async fn fsync() {
+        let f = tempfile().unwrap();
+        let fd = f.as_raw_fd();
+        let aiocb = AioCb::from_fd(fd, 0);
+        let source = WrappedAioCb(aiocb);
+        let mut poll_aio = Aio::new_for_aio(source).unwrap();
+        (*poll_aio).0.fsync(AioFsyncMode::O_SYNC).unwrap();
+        let fut = FsyncFut(poll_aio);
+        fut.await.unwrap();
+    }
+
+    #[tokio::test]
+    async fn ll_fsync() {
+        let f = tempfile().unwrap();
+        let fd = f.as_raw_fd();
+        let mut aiocb: libc::aiocb = unsafe { mem::MaybeUninit::zeroed().assume_init() };
+        aiocb.aio_fildes = fd;
+        let source = LlSource(Box::pin(aiocb));
+        let mut poll_aio = Aio::new_for_aio(source).unwrap();
+        let r = unsafe {
+            let p = (*poll_aio).0.as_mut().get_unchecked_mut();
+            libc::aio_fsync(libc::O_SYNC, p)
+        };
+        assert_eq!(0, r);
+        let fut = LlFut(poll_aio);
+        fut.await.unwrap();
+    }
+
+    /// A suitably crafted future type can reuse an Aio object
+    #[tokio::test]
+    async fn reuse() {
+        let f = tempfile().unwrap();
+        let fd = f.as_raw_fd();
+        let aiocb0 = AioCb::from_fd(fd, 0);
+        let source = ReusableFsyncSource::new(aiocb0);
+        let mut poll_aio = Aio::new_for_aio(source).unwrap();
+        poll_aio.fsync();
+        let fut0 = ReusableFsyncFut(&mut poll_aio);
+        fut0.await.unwrap();
+
+        let aiocb1 = AioCb::from_fd(fd, 0);
+        poll_aio.reset(aiocb1);
+        let mut ctx = Context::from_waker(futures::task::noop_waker_ref());
+        assert_pending!(poll_aio.poll_ready(&mut ctx));
+        poll_aio.fsync();
+        let fut1 = ReusableFsyncFut(&mut poll_aio);
+        fut1.await.unwrap();
+    }
+}
+
+mod lio {
+    use super::*;
+
+    struct WrappedLioCb<'a>(LioCb<'a>);
+    impl<'a> AioSource for WrappedLioCb<'a> {
+        fn register(&mut self, kq: RawFd, token: usize) {
+            self.0.register_raw(kq, token)
+        }
+        fn deregister(&mut self) {
+            self.0.deregister_raw()
+        }
+    }
+
+    /// A very crude lio_listio-based Future
+    struct LioFut(Option<Aio<WrappedLioCb<'static>>>);
+
+    impl Future for LioFut {
+        type Output = std::io::Result<Vec<isize>>;
+
+        fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+            let poll_result = self.0.as_mut().unwrap().poll_ready(cx);
+            match poll_result {
+                Poll::Pending => Poll::Pending,
+                Poll::Ready(Err(e)) => Poll::Ready(Err(e)),
+                Poll::Ready(Ok(_ev)) => {
+                    // At this point, we could clear readiness.  But there's no
+                    // point, since we're about to drop the Aio.
+                    let r = self.0.take().unwrap().into_inner().0.into_results(|iter| {
+                        iter.map(|lr| lr.result.unwrap()).collect::<Vec<isize>>()
+                    });
+                    Poll::Ready(Ok(r))
+                }
+            }
+        }
+    }
+
+    /// Minimal example demonstrating reuse of an Aio object with lio
+    /// readiness.  mio_aio::LioCb actually does something similar under the
+    /// hood.
+    struct ReusableLioSource {
+        liocb: Option<LioCb<'static>>,
+        fd: RawFd,
+        token: usize,
+    }
+    impl ReusableLioSource {
+        fn new(liocb: LioCb<'static>) -> Self {
+            ReusableLioSource {
+                liocb: Some(liocb),
+                fd: 0,
+                token: 0,
+            }
+        }
+        fn reset(&mut self, liocb: LioCb<'static>) {
+            self.liocb = Some(liocb);
+        }
+        fn submit(&mut self) {
+            self.liocb
+                .as_mut()
+                .unwrap()
+                .register_raw(self.fd, self.token);
+            self.liocb.as_mut().unwrap().submit().unwrap();
+        }
+    }
+    impl AioSource for ReusableLioSource {
+        fn register(&mut self, kq: RawFd, token: usize) {
+            self.fd = kq;
+            self.token = token;
+        }
+        fn deregister(&mut self) {
+            self.fd = 0;
+        }
+    }
+    struct ReusableLioFut<'a>(&'a mut Aio<ReusableLioSource>);
+    impl<'a> Future for ReusableLioFut<'a> {
+        type Output = std::io::Result<Vec<isize>>;
+
+        fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+            let poll_result = self.0.poll_ready(cx);
+            match poll_result {
+                Poll::Pending => Poll::Pending,
+                Poll::Ready(Err(e)) => Poll::Ready(Err(e)),
+                Poll::Ready(Ok(ev)) => {
+                    // Since this future uses a reusable Aio, we must clear
+                    // its readiness here.  That makes the future
+                    // non-idempotent; the caller can't poll it repeatedly after
+                    // it has already returned Ready.  But that's ok; most
+                    // futures behave this way.
+                    self.0.clear_ready(ev);
+                    let r = (*self.0).liocb.take().unwrap().into_results(|iter| {
+                        iter.map(|lr| lr.result.unwrap()).collect::<Vec<isize>>()
+                    });
+                    Poll::Ready(Ok(r))
+                }
+            }
+        }
+    }
+
+    /// An lio_listio operation with one write element
+    #[tokio::test]
+    async fn onewrite() {
+        const WBUF: &[u8] = b"abcdef";
+        let f = tempfile().unwrap();
+
+        let mut builder = mio_aio::LioCbBuilder::with_capacity(1);
+        builder = builder.emplace_slice(
+            f.as_raw_fd(),
+            0,
+            &WBUF[..],
+            0,
+            mio_aio::LioOpcode::LIO_WRITE,
+        );
+        let liocb = builder.finish();
+        let source = WrappedLioCb(liocb);
+        let mut poll_aio = Aio::new_for_lio(source).unwrap();
+
+        // Send the operation to the kernel
+        (*poll_aio).0.submit().unwrap();
+        let fut = LioFut(Some(poll_aio));
+        let v = fut.await.unwrap();
+        assert_eq!(v.len(), 1);
+        assert_eq!(v[0] as usize, WBUF.len());
+    }
+
+    /// A suitably crafted future type can reuse an Aio object
+    #[tokio::test]
+    async fn reuse() {
+        const WBUF: &[u8] = b"abcdef";
+        let f = tempfile().unwrap();
+
+        let mut builder0 = mio_aio::LioCbBuilder::with_capacity(1);
+        builder0 = builder0.emplace_slice(
+            f.as_raw_fd(),
+            0,
+            &WBUF[..],
+            0,
+            mio_aio::LioOpcode::LIO_WRITE,
+        );
+        let liocb0 = builder0.finish();
+        let source = ReusableLioSource::new(liocb0);
+        let mut poll_aio = Aio::new_for_aio(source).unwrap();
+        poll_aio.submit();
+        let fut0 = ReusableLioFut(&mut poll_aio);
+        let v = fut0.await.unwrap();
+        assert_eq!(v.len(), 1);
+        assert_eq!(v[0] as usize, WBUF.len());
+
+        // Now reuse the same Aio
+        let mut builder1 = mio_aio::LioCbBuilder::with_capacity(1);
+        builder1 = builder1.emplace_slice(
+            f.as_raw_fd(),
+            0,
+            &WBUF[..],
+            0,
+            mio_aio::LioOpcode::LIO_WRITE,
+        );
+        let liocb1 = builder1.finish();
+        poll_aio.reset(liocb1);
+        let mut ctx = Context::from_waker(futures::task::noop_waker_ref());
+        assert_pending!(poll_aio.poll_ready(&mut ctx));
+        poll_aio.submit();
+        let fut1 = ReusableLioFut(&mut poll_aio);
+        let v = fut1.await.unwrap();
+        assert_eq!(v.len(), 1);
+        assert_eq!(v[0] as usize, WBUF.len());
+    }
+}
diff --git a/vendor/tokio/tests/io_read.rs b/vendor/tokio/tests/io_read.rs
index cb1aa7052..7f74c5e85 100644
--- a/vendor/tokio/tests/io_read.rs
+++ b/vendor/tokio/tests/io_read.rs
@@ -1,5 +1,5 @@
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi does not support panic recovery
 
 use tokio::io::{AsyncRead, AsyncReadExt, ReadBuf};
 use tokio_test::assert_ok;
@@ -8,6 +8,11 @@ use std::io;
 use std::pin::Pin;
 use std::task::{Context, Poll};
 
+mod support {
+    pub(crate) mod leaked_buffers;
+}
+use support::leaked_buffers::LeakedBuffers;
+
 #[tokio::test]
 async fn read() {
     #[derive(Default)]
@@ -37,16 +42,27 @@ async fn read() {
     assert_eq!(buf[..], b"hello world"[..]);
 }
 
-struct BadAsyncRead;
+struct BadAsyncRead {
+    leaked_buffers: LeakedBuffers,
+}
+
+impl BadAsyncRead {
+    fn new() -> Self {
+        Self {
+            leaked_buffers: LeakedBuffers::new(),
+        }
+    }
+}
 
 impl AsyncRead for BadAsyncRead {
     fn poll_read(
-        self: Pin<&mut Self>,
+        mut self: Pin<&mut Self>,
         _cx: &mut Context<'_>,
         buf: &mut ReadBuf<'_>,
     ) -> Poll<io::Result<()>> {
-        *buf = ReadBuf::new(Box::leak(vec![0; buf.capacity()].into_boxed_slice()));
+        *buf = ReadBuf::new(unsafe { self.leaked_buffers.create(buf.capacity()) });
         buf.advance(buf.capacity());
+
         Poll::Ready(Ok(()))
     }
 }
@@ -55,5 +71,5 @@ impl AsyncRead for BadAsyncRead {
 #[should_panic]
 async fn read_buf_bad_async_read() {
     let mut buf = Vec::with_capacity(10);
-    BadAsyncRead.read_buf(&mut buf).await.unwrap();
+    BadAsyncRead::new().read_buf(&mut buf).await.unwrap();
 }
diff --git a/vendor/tokio/tests/io_read_buf.rs b/vendor/tokio/tests/io_read_buf.rs
index 0328168d7..49a4f86f8 100644
--- a/vendor/tokio/tests/io_read_buf.rs
+++ b/vendor/tokio/tests/io_read_buf.rs
@@ -34,3 +34,61 @@ async fn read_buf() {
     assert_eq!(n, 11);
     assert_eq!(buf[..], b"hello world"[..]);
 }
+
+#[tokio::test]
+#[cfg(feature = "io-util")]
+async fn issue_5588() {
+    use bytes::BufMut;
+
+    // steps to zero
+    let mut buf = [0; 8];
+    let mut read_buf = ReadBuf::new(&mut buf);
+    assert_eq!(read_buf.remaining_mut(), 8);
+    assert_eq!(read_buf.chunk_mut().len(), 8);
+    unsafe {
+        read_buf.advance_mut(1);
+    }
+    assert_eq!(read_buf.remaining_mut(), 7);
+    assert_eq!(read_buf.chunk_mut().len(), 7);
+    unsafe {
+        read_buf.advance_mut(5);
+    }
+    assert_eq!(read_buf.remaining_mut(), 2);
+    assert_eq!(read_buf.chunk_mut().len(), 2);
+    unsafe {
+        read_buf.advance_mut(2);
+    }
+    assert_eq!(read_buf.remaining_mut(), 0);
+    assert_eq!(read_buf.chunk_mut().len(), 0);
+
+    // directly to zero
+    let mut buf = [0; 8];
+    let mut read_buf = ReadBuf::new(&mut buf);
+    assert_eq!(read_buf.remaining_mut(), 8);
+    assert_eq!(read_buf.chunk_mut().len(), 8);
+    unsafe {
+        read_buf.advance_mut(8);
+    }
+    assert_eq!(read_buf.remaining_mut(), 0);
+    assert_eq!(read_buf.chunk_mut().len(), 0);
+
+    // uninit
+    let mut buf = [std::mem::MaybeUninit::new(1); 8];
+    let mut uninit = ReadBuf::uninit(&mut buf);
+    assert_eq!(uninit.remaining_mut(), 8);
+    assert_eq!(uninit.chunk_mut().len(), 8);
+
+    let mut buf = [std::mem::MaybeUninit::uninit(); 8];
+    let mut uninit = ReadBuf::uninit(&mut buf);
+    unsafe {
+        uninit.advance_mut(4);
+    }
+    assert_eq!(uninit.remaining_mut(), 4);
+    assert_eq!(uninit.chunk_mut().len(), 4);
+    uninit.put_u8(1);
+    assert_eq!(uninit.remaining_mut(), 3);
+    assert_eq!(uninit.chunk_mut().len(), 3);
+    uninit.put_slice(&[1, 2, 3]);
+    assert_eq!(uninit.remaining_mut(), 0);
+    assert_eq!(uninit.chunk_mut().len(), 0);
+}
diff --git a/vendor/tokio/tests/io_read_to_end.rs b/vendor/tokio/tests/io_read_to_end.rs
index 171e6d648..29b60bece 100644
--- a/vendor/tokio/tests/io_read_to_end.rs
+++ b/vendor/tokio/tests/io_read_to_end.rs
@@ -5,6 +5,7 @@ use std::pin::Pin;
 use std::task::{Context, Poll};
 use tokio::io::{AsyncRead, AsyncReadExt, ReadBuf};
 use tokio_test::assert_ok;
+use tokio_test::io::Builder;
 
 #[tokio::test]
 async fn read_to_end() {
@@ -76,3 +77,48 @@ async fn read_to_end_uninit() {
     test.read_to_end(&mut buf).await.unwrap();
     assert_eq!(buf.len(), 33);
 }
+
+#[tokio::test]
+async fn read_to_end_doesnt_grow_with_capacity() {
+    let arr: Vec<u8> = (0..100).collect();
+
+    // We only test from 32 since we allocate at least 32 bytes each time
+    for len in 32..100 {
+        let bytes = &arr[..len];
+        for split in 0..len {
+            for cap in 0..101 {
+                let mut mock = if split == 0 {
+                    Builder::new().read(bytes).build()
+                } else {
+                    Builder::new()
+                        .read(&bytes[..split])
+                        .read(&bytes[split..])
+                        .build()
+                };
+                let mut buf = Vec::with_capacity(cap);
+                AsyncReadExt::read_to_end(&mut mock, &mut buf)
+                    .await
+                    .unwrap();
+                // It has the right data.
+                assert_eq!(buf.as_slice(), bytes);
+                // Unless cap was smaller than length, then we did not reallocate.
+                if cap >= len {
+                    assert_eq!(buf.capacity(), cap);
+                }
+            }
+        }
+    }
+}
+
+#[tokio::test]
+async fn read_to_end_grows_capacity_if_unfit() {
+    let bytes = b"the_vector_startingcap_will_be_smaller";
+    let mut mock = Builder::new().read(bytes).build();
+    let initial_capacity = bytes.len() - 4;
+    let mut buf = Vec::with_capacity(initial_capacity);
+    AsyncReadExt::read_to_end(&mut mock, &mut buf)
+        .await
+        .unwrap();
+    // *4 since it doubles when it doesn't fit and again when reaching EOF
+    assert_eq!(buf.capacity(), initial_capacity * 4);
+}
diff --git a/vendor/tokio/tests/io_split.rs b/vendor/tokio/tests/io_split.rs
index db168e9f8..4cbd2a2d1 100644
--- a/vendor/tokio/tests/io_split.rs
+++ b/vendor/tokio/tests/io_split.rs
@@ -1,5 +1,5 @@
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi does not support panic recovery
 
 use tokio::io::{split, AsyncRead, AsyncWrite, ReadBuf, ReadHalf, WriteHalf};
 
@@ -50,10 +50,10 @@ fn is_send_and_sync() {
 fn split_stream_id() {
     let (r1, w1) = split(RW);
     let (r2, w2) = split(RW);
-    assert_eq!(r1.is_pair_of(&w1), true);
-    assert_eq!(r1.is_pair_of(&w2), false);
-    assert_eq!(r2.is_pair_of(&w2), true);
-    assert_eq!(r2.is_pair_of(&w1), false);
+    assert!(r1.is_pair_of(&w1));
+    assert!(!r1.is_pair_of(&w2));
+    assert!(r2.is_pair_of(&w2));
+    assert!(!r2.is_pair_of(&w1));
 }
 
 #[test]
diff --git a/vendor/tokio/tests/io_take.rs b/vendor/tokio/tests/io_take.rs
index 683606f72..fba01d2e0 100644
--- a/vendor/tokio/tests/io_take.rs
+++ b/vendor/tokio/tests/io_take.rs
@@ -1,9 +1,16 @@
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi does not support panic recovery
 
-use tokio::io::AsyncReadExt;
+use std::pin::Pin;
+use std::task::{Context, Poll};
+use tokio::io::{self, AsyncRead, AsyncReadExt, ReadBuf};
 use tokio_test::assert_ok;
 
+mod support {
+    pub(crate) mod leaked_buffers;
+}
+use support::leaked_buffers::LeakedBuffers;
+
 #[tokio::test]
 async fn take() {
     let mut buf = [0; 6];
@@ -14,3 +21,54 @@ async fn take() {
     assert_eq!(n, 4);
     assert_eq!(&buf, &b"hell\0\0"[..]);
 }
+
+#[tokio::test]
+async fn issue_4435() {
+    let mut buf = [0; 8];
+    let rd: &[u8] = b"hello world";
+
+    let rd = rd.take(4);
+    tokio::pin!(rd);
+
+    let mut read_buf = ReadBuf::new(&mut buf);
+    read_buf.put_slice(b"AB");
+
+    futures::future::poll_fn(|cx| rd.as_mut().poll_read(cx, &mut read_buf))
+        .await
+        .unwrap();
+    assert_eq!(&buf, &b"ABhell\0\0"[..]);
+}
+
+struct BadReader {
+    leaked_buffers: LeakedBuffers,
+}
+
+impl BadReader {
+    fn new() -> Self {
+        Self {
+            leaked_buffers: LeakedBuffers::new(),
+        }
+    }
+}
+
+impl AsyncRead for BadReader {
+    fn poll_read(
+        mut self: Pin<&mut Self>,
+        _cx: &mut Context<'_>,
+        read_buf: &mut ReadBuf<'_>,
+    ) -> Poll<io::Result<()>> {
+        let mut buf = ReadBuf::new(unsafe { self.leaked_buffers.create(10) });
+        buf.put_slice(&[123; 10]);
+        *read_buf = buf;
+
+        Poll::Ready(Ok(()))
+    }
+}
+
+#[tokio::test]
+#[should_panic]
+async fn bad_reader_fails() {
+    let mut buf = Vec::with_capacity(10);
+
+    BadReader::new().take(10).read_buf(&mut buf).await.unwrap();
+}
diff --git a/vendor/tokio/tests/io_util_empty.rs b/vendor/tokio/tests/io_util_empty.rs
new file mode 100644
index 000000000..e49cd17fc
--- /dev/null
+++ b/vendor/tokio/tests/io_util_empty.rs
@@ -0,0 +1,32 @@
+#![cfg(feature = "full")]
+use tokio::io::{AsyncBufReadExt, AsyncReadExt};
+
+#[tokio::test]
+async fn empty_read_is_cooperative() {
+    tokio::select! {
+        biased;
+
+        _ = async {
+            loop {
+                let mut buf = [0u8; 4096];
+                let _ = tokio::io::empty().read(&mut buf).await;
+            }
+        } => {},
+        _ = tokio::task::yield_now() => {}
+    }
+}
+
+#[tokio::test]
+async fn empty_buf_reads_are_cooperative() {
+    tokio::select! {
+        biased;
+
+        _ = async {
+            loop {
+                let mut buf = String::new();
+                let _ = tokio::io::empty().read_line(&mut buf).await;
+            }
+        } => {},
+        _ = tokio::task::yield_now() => {}
+    }
+}
diff --git a/vendor/tokio/tests/io_write_all_buf.rs b/vendor/tokio/tests/io_write_all_buf.rs
index b49a58ebe..7c8b61935 100644
--- a/vendor/tokio/tests/io_write_all_buf.rs
+++ b/vendor/tokio/tests/io_write_all_buf.rs
@@ -52,7 +52,7 @@ async fn write_all_buf() {
     assert_eq!(wr.buf, b"helloworld"[..]);
     // expect 4 writes, [hell],[o],[worl],[d]
     assert_eq!(wr.cnt, 4);
-    assert_eq!(buf.has_remaining(), false);
+    assert!(!buf.has_remaining());
 }
 
 #[tokio::test]
diff --git a/vendor/tokio/tests/join_handle_panic.rs b/vendor/tokio/tests/join_handle_panic.rs
new file mode 100644
index 000000000..bc34fd0ea
--- /dev/null
+++ b/vendor/tokio/tests/join_handle_panic.rs
@@ -0,0 +1,20 @@
+#![warn(rust_2018_idioms)]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi does not support panic recovery
+
+struct PanicsOnDrop;
+
+impl Drop for PanicsOnDrop {
+    fn drop(&mut self) {
+        panic!("I told you so");
+    }
+}
+
+#[tokio::test]
+async fn test_panics_do_not_propagate_when_dropping_join_handle() {
+    let join_handle = tokio::spawn(async move { PanicsOnDrop });
+
+    // only drop the JoinHandle when the task has completed
+    // (which is difficult to synchronize precisely)
+    tokio::time::sleep(std::time::Duration::from_millis(3)).await;
+    drop(join_handle);
+}
diff --git a/vendor/tokio/tests/macros_join.rs b/vendor/tokio/tests/macros_join.rs
index 169e898f9..7866ac086 100644
--- a/vendor/tokio/tests/macros_join.rs
+++ b/vendor/tokio/tests/macros_join.rs
@@ -1,36 +1,48 @@
-#![allow(clippy::blacklisted_name)]
-use tokio::sync::oneshot;
+#![cfg(feature = "macros")]
+#![allow(clippy::disallowed_names)]
+use std::sync::Arc;
+
+#[cfg(tokio_wasm_not_wasi)]
+#[cfg(target_pointer_width = "64")]
+use wasm_bindgen_test::wasm_bindgen_test as test;
+#[cfg(tokio_wasm_not_wasi)]
+use wasm_bindgen_test::wasm_bindgen_test as maybe_tokio_test;
+
+#[cfg(not(tokio_wasm_not_wasi))]
+use tokio::test as maybe_tokio_test;
+
+use tokio::sync::{oneshot, Semaphore};
 use tokio_test::{assert_pending, assert_ready, task};
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn sync_one_lit_expr_comma() {
     let foo = tokio::join!(async { 1 },);
 
     assert_eq!(foo, (1,));
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn sync_one_lit_expr_no_comma() {
     let foo = tokio::join!(async { 1 });
 
     assert_eq!(foo, (1,));
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn sync_two_lit_expr_comma() {
     let foo = tokio::join!(async { 1 }, async { 2 },);
 
     assert_eq!(foo, (1, 2));
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn sync_two_lit_expr_no_comma() {
     let foo = tokio::join!(async { 1 }, async { 2 });
 
     assert_eq!(foo, (1, 2));
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn two_await() {
     let (tx1, rx1) = oneshot::channel::<&str>();
     let (tx2, rx2) = oneshot::channel::<u32>();
@@ -53,6 +65,7 @@ async fn two_await() {
 }
 
 #[test]
+#[cfg(target_pointer_width = "64")]
 fn join_size() {
     use futures::future;
     use std::mem;
@@ -61,12 +74,88 @@ fn join_size() {
         let ready = future::ready(0i32);
         tokio::join!(ready)
     };
-    assert_eq!(mem::size_of_val(&fut), 16);
+    assert_eq!(mem::size_of_val(&fut), 32);
 
     let fut = async {
         let ready1 = future::ready(0i32);
         let ready2 = future::ready(0i32);
         tokio::join!(ready1, ready2)
     };
-    assert_eq!(mem::size_of_val(&fut), 28);
+    assert_eq!(mem::size_of_val(&fut), 40);
+}
+
+async fn non_cooperative_task(permits: Arc<Semaphore>) -> usize {
+    let mut exceeded_budget = 0;
+
+    for _ in 0..5 {
+        // Another task should run after this task uses its whole budget
+        for _ in 0..128 {
+            let _permit = permits.clone().acquire_owned().await.unwrap();
+        }
+
+        exceeded_budget += 1;
+    }
+
+    exceeded_budget
+}
+
+async fn poor_little_task(permits: Arc<Semaphore>) -> usize {
+    let mut how_many_times_i_got_to_run = 0;
+
+    for _ in 0..5 {
+        let _permit = permits.clone().acquire_owned().await.unwrap();
+        how_many_times_i_got_to_run += 1;
+    }
+
+    how_many_times_i_got_to_run
+}
+
+#[tokio::test]
+async fn join_does_not_allow_tasks_to_starve() {
+    let permits = Arc::new(Semaphore::new(1));
+
+    // non_cooperative_task should yield after its budget is exceeded and then poor_little_task should run.
+    let (non_cooperative_result, little_task_result) = tokio::join!(
+        non_cooperative_task(Arc::clone(&permits)),
+        poor_little_task(permits)
+    );
+
+    assert_eq!(5, non_cooperative_result);
+    assert_eq!(5, little_task_result);
+}
+
+#[tokio::test]
+async fn a_different_future_is_polled_first_every_time_poll_fn_is_polled() {
+    let poll_order = Arc::new(std::sync::Mutex::new(vec![]));
+
+    let fut = |x, poll_order: Arc<std::sync::Mutex<Vec<i32>>>| async move {
+        for _ in 0..4 {
+            {
+                let mut guard = poll_order.lock().unwrap();
+
+                guard.push(x);
+            }
+
+            tokio::task::yield_now().await;
+        }
+    };
+
+    tokio::join!(
+        fut(1, Arc::clone(&poll_order)),
+        fut(2, Arc::clone(&poll_order)),
+        fut(3, Arc::clone(&poll_order)),
+    );
+
+    // Each time the future created by join! is polled, it should start
+    // by polling a different future first.
+    assert_eq!(
+        vec![1, 2, 3, 2, 3, 1, 3, 1, 2, 1, 2, 3],
+        *poll_order.lock().unwrap()
+    );
+}
+
+#[tokio::test]
+#[allow(clippy::unit_cmp)]
+async fn empty_join() {
+    assert_eq!(tokio::join!(), ());
 }
diff --git a/vendor/tokio/tests/macros_pin.rs b/vendor/tokio/tests/macros_pin.rs
index da6e0be6e..e99a3ee20 100644
--- a/vendor/tokio/tests/macros_pin.rs
+++ b/vendor/tokio/tests/macros_pin.rs
@@ -1,7 +1,15 @@
+#![cfg(feature = "macros")]
+
+#[cfg(tokio_wasm_not_wasi)]
+use wasm_bindgen_test::wasm_bindgen_test as maybe_tokio_test;
+
+#[cfg(not(tokio_wasm_not_wasi))]
+use tokio::test as maybe_tokio_test;
+
 async fn one() {}
 async fn two() {}
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn multi_pin() {
     tokio::pin! {
         let f1 = one();
diff --git a/vendor/tokio/tests/macros_rename_test.rs b/vendor/tokio/tests/macros_rename_test.rs
new file mode 100644
index 000000000..6c2ce2f57
--- /dev/null
+++ b/vendor/tokio/tests/macros_rename_test.rs
@@ -0,0 +1,35 @@
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi doesn't support threading
+
+#[allow(unused_imports)]
+use std as tokio;
+
+use ::tokio as tokio1;
+
+mod test {
+    pub use ::tokio;
+}
+
+async fn compute() -> usize {
+    let join = tokio1::spawn(async { 1 });
+    join.await.unwrap()
+}
+
+#[tokio1::main(crate = "tokio1")]
+async fn compute_main() -> usize {
+    compute().await
+}
+
+#[test]
+fn crate_rename_main() {
+    assert_eq!(1, compute_main());
+}
+
+#[tokio1::test(crate = "tokio1")]
+async fn crate_rename_test() {
+    assert_eq!(1, compute().await);
+}
+
+#[test::tokio::test(crate = "test::tokio")]
+async fn crate_path_test() {
+    assert_eq!(1, compute().await);
+}
diff --git a/vendor/tokio/tests/macros_select.rs b/vendor/tokio/tests/macros_select.rs
index a089602cb..0514c864d 100644
--- a/vendor/tokio/tests/macros_select.rs
+++ b/vendor/tokio/tests/macros_select.rs
@@ -1,12 +1,19 @@
-#![allow(clippy::blacklisted_name)]
-use tokio::sync::{mpsc, oneshot};
-use tokio::task;
+#![cfg(feature = "macros")]
+#![allow(clippy::disallowed_names)]
+
+#[cfg(tokio_wasm_not_wasi)]
+use wasm_bindgen_test::wasm_bindgen_test as maybe_tokio_test;
+
+#[cfg(not(tokio_wasm_not_wasi))]
+use tokio::test as maybe_tokio_test;
+
+use tokio::sync::oneshot;
 use tokio_test::{assert_ok, assert_pending, assert_ready};
 
 use futures::future::poll_fn;
 use std::task::Poll::Ready;
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn sync_one_lit_expr_comma() {
     let foo = tokio::select! {
         foo = async { 1 } => foo,
@@ -15,7 +22,7 @@ async fn sync_one_lit_expr_comma() {
     assert_eq!(foo, 1);
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn nested_one() {
     let foo = tokio::select! {
         foo = async { 1 } => tokio::select! {
@@ -26,7 +33,7 @@ async fn nested_one() {
     assert_eq!(foo, 1);
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn sync_one_lit_expr_no_comma() {
     let foo = tokio::select! {
         foo = async { 1 } => foo
@@ -35,7 +42,7 @@ async fn sync_one_lit_expr_no_comma() {
     assert_eq!(foo, 1);
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn sync_one_lit_expr_block() {
     let foo = tokio::select! {
         foo = async { 1 } => { foo }
@@ -44,7 +51,7 @@ async fn sync_one_lit_expr_block() {
     assert_eq!(foo, 1);
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn sync_one_await() {
     let foo = tokio::select! {
         foo = one() => foo,
@@ -53,7 +60,7 @@ async fn sync_one_await() {
     assert_eq!(foo, 1);
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn sync_one_ident() {
     let one = one();
 
@@ -64,7 +71,7 @@ async fn sync_one_ident() {
     assert_eq!(foo, 1);
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn sync_two() {
     use std::cell::Cell;
 
@@ -85,7 +92,7 @@ async fn sync_two() {
     assert!(res == 1 || res == 2);
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn drop_in_fut() {
     let s = "hello".to_string();
 
@@ -100,7 +107,8 @@ async fn drop_in_fut() {
     assert_eq!(res, 1);
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
+#[cfg(feature = "full")]
 async fn one_ready() {
     let (tx1, rx1) = oneshot::channel::<i32>();
     let (_tx2, rx2) = oneshot::channel::<i32>();
@@ -117,20 +125,23 @@ async fn one_ready() {
     assert_eq!(1, v);
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
+#[cfg(feature = "full")]
 async fn select_streams() {
+    use tokio::sync::mpsc;
+
     let (tx1, mut rx1) = mpsc::unbounded_channel::<i32>();
     let (tx2, mut rx2) = mpsc::unbounded_channel::<i32>();
 
     tokio::spawn(async move {
         assert_ok!(tx2.send(1));
-        task::yield_now().await;
+        tokio::task::yield_now().await;
 
         assert_ok!(tx1.send(2));
-        task::yield_now().await;
+        tokio::task::yield_now().await;
 
         assert_ok!(tx2.send(3));
-        task::yield_now().await;
+        tokio::task::yield_now().await;
 
         drop((tx1, tx2));
     });
@@ -156,7 +167,7 @@ async fn select_streams() {
     assert_eq!(&msgs[..], &[1, 2, 3]);
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn move_uncompleted_futures() {
     let (tx1, mut rx1) = oneshot::channel::<i32>();
     let (tx2, mut rx2) = oneshot::channel::<i32>();
@@ -182,7 +193,7 @@ async fn move_uncompleted_futures() {
     assert!(ran);
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn nested() {
     let res = tokio::select! {
         x = async { 1 } => {
@@ -195,49 +206,59 @@ async fn nested() {
     assert_eq!(res, 3);
 }
 
-#[tokio::test]
-async fn struct_size() {
+#[cfg(target_pointer_width = "64")]
+mod pointer_64_tests {
+    use super::maybe_tokio_test;
     use futures::future;
     use std::mem;
 
-    let fut = async {
-        let ready = future::ready(0i32);
+    #[maybe_tokio_test]
+    async fn struct_size_1() {
+        let fut = async {
+            let ready = future::ready(0i32);
 
-        tokio::select! {
-            _ = ready => {},
-        }
-    };
+            tokio::select! {
+                _ = ready => {},
+            }
+        };
 
-    assert!(mem::size_of_val(&fut) <= 32);
+        assert_eq!(mem::size_of_val(&fut), 32);
+    }
 
-    let fut = async {
-        let ready1 = future::ready(0i32);
-        let ready2 = future::ready(0i32);
+    #[maybe_tokio_test]
+    async fn struct_size_2() {
+        let fut = async {
+            let ready1 = future::ready(0i32);
+            let ready2 = future::ready(0i32);
 
-        tokio::select! {
-            _ = ready1 => {},
-            _ = ready2 => {},
-        }
-    };
+            tokio::select! {
+                _ = ready1 => {},
+                _ = ready2 => {},
+            }
+        };
 
-    assert!(mem::size_of_val(&fut) <= 40);
+        assert_eq!(mem::size_of_val(&fut), 40);
+    }
 
-    let fut = async {
-        let ready1 = future::ready(0i32);
-        let ready2 = future::ready(0i32);
-        let ready3 = future::ready(0i32);
+    #[maybe_tokio_test]
+    async fn struct_size_3() {
+        let fut = async {
+            let ready1 = future::ready(0i32);
+            let ready2 = future::ready(0i32);
+            let ready3 = future::ready(0i32);
 
-        tokio::select! {
-            _ = ready1 => {},
-            _ = ready2 => {},
-            _ = ready3 => {},
-        }
-    };
+            tokio::select! {
+                _ = ready1 => {},
+                _ = ready2 => {},
+                _ = ready3 => {},
+            }
+        };
 
-    assert!(mem::size_of_val(&fut) <= 48);
+        assert_eq!(mem::size_of_val(&fut), 48);
+    }
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn mutable_borrowing_future_with_same_borrow_in_block() {
     let mut value = 234;
 
@@ -251,7 +272,7 @@ async fn mutable_borrowing_future_with_same_borrow_in_block() {
     assert!(value >= 234);
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn mutable_borrowing_future_with_same_borrow_in_block_and_else() {
     let mut value = 234;
 
@@ -268,7 +289,7 @@ async fn mutable_borrowing_future_with_same_borrow_in_block_and_else() {
     assert!(value >= 234);
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn future_panics_after_poll() {
     use tokio_test::task;
 
@@ -298,7 +319,7 @@ async fn future_panics_after_poll() {
     assert_eq!(1, res);
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn disable_with_if() {
     use tokio_test::task;
 
@@ -320,7 +341,7 @@ async fn disable_with_if() {
     assert_ready!(f.poll());
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn join_with_select() {
     use tokio_test::task;
 
@@ -356,11 +377,12 @@ async fn join_with_select() {
 }
 
 #[tokio::test]
+#[cfg(feature = "full")]
 async fn use_future_in_if_condition() {
     use tokio::time::{self, Duration};
 
     tokio::select! {
-        _ = time::sleep(Duration::from_millis(50)), if false => {
+        _ = time::sleep(Duration::from_millis(10)), if false => {
             panic!("if condition ignored")
         }
         _ = async { 1u32 } => {
@@ -369,6 +391,21 @@ async fn use_future_in_if_condition() {
 }
 
 #[tokio::test]
+#[cfg(feature = "full")]
+async fn use_future_in_if_condition_biased() {
+    use tokio::time::{self, Duration};
+
+    tokio::select! {
+        biased;
+        _ = time::sleep(Duration::from_millis(10)), if false => {
+            panic!("if condition ignored")
+        }
+        _ = async { 1u32 } => {
+        }
+    }
+}
+
+#[maybe_tokio_test]
 async fn many_branches() {
     let num = tokio::select! {
         x = async { 1 } => x,
@@ -434,12 +471,13 @@ async fn many_branches() {
         x = async { 1 } => x,
         x = async { 1 } => x,
         x = async { 1 } => x,
+        x = async { 1 } => x,
     };
 
     assert_eq!(1, num);
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn never_branch_no_warnings() {
     let t = tokio::select! {
         _ = async_never() => 0,
@@ -456,14 +494,11 @@ async fn require_mutable(_: &mut i32) {}
 async fn async_noop() {}
 
 async fn async_never() -> ! {
-    use tokio::time::Duration;
-    loop {
-        tokio::time::sleep(Duration::from_millis(10)).await;
-    }
+    futures::future::pending().await
 }
 
 // From https://github.com/tokio-rs/tokio/issues/2857
-#[tokio::test]
+#[maybe_tokio_test]
 async fn mut_on_left_hand_side() {
     let v = async move {
         let ok = async { 1 };
@@ -479,7 +514,7 @@ async fn mut_on_left_hand_side() {
     assert_eq!(v, 2);
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn biased_one_not_ready() {
     let (_tx1, rx1) = oneshot::channel::<i32>();
     let (tx2, rx2) = oneshot::channel::<i32>();
@@ -503,7 +538,8 @@ async fn biased_one_not_ready() {
     assert_eq!(2, v);
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
+#[cfg(feature = "full")]
 async fn biased_eventually_ready() {
     use tokio::task::yield_now;
 
@@ -547,3 +583,92 @@ pub async fn default_numeric_fallback() {
         else => (),
     }
 }
+
+// https://github.com/tokio-rs/tokio/issues/4182
+#[maybe_tokio_test]
+async fn mut_ref_patterns() {
+    tokio::select! {
+        Some(mut foo) = async { Some("1".to_string()) } => {
+            assert_eq!(foo, "1");
+            foo = "2".to_string();
+            assert_eq!(foo, "2");
+        },
+    };
+
+    tokio::select! {
+        Some(ref foo) = async { Some("1".to_string()) } => {
+            assert_eq!(*foo, "1");
+        },
+    };
+
+    tokio::select! {
+        Some(ref mut foo) = async { Some("1".to_string()) } => {
+            assert_eq!(*foo, "1");
+            *foo = "2".to_string();
+            assert_eq!(*foo, "2");
+        },
+    };
+}
+
+#[cfg(tokio_unstable)]
+mod unstable {
+    use tokio::runtime::RngSeed;
+
+    #[test]
+    fn deterministic_select_current_thread() {
+        let seed = b"bytes used to generate seed";
+        let rt1 = tokio::runtime::Builder::new_current_thread()
+            .rng_seed(RngSeed::from_bytes(seed))
+            .build()
+            .unwrap();
+        let rt1_values = rt1.block_on(async { (select_0_to_9().await, select_0_to_9().await) });
+
+        let rt2 = tokio::runtime::Builder::new_current_thread()
+            .rng_seed(RngSeed::from_bytes(seed))
+            .build()
+            .unwrap();
+        let rt2_values = rt2.block_on(async { (select_0_to_9().await, select_0_to_9().await) });
+
+        assert_eq!(rt1_values, rt2_values);
+    }
+
+    #[test]
+    #[cfg(all(feature = "rt-multi-thread", not(tokio_wasi)))]
+    fn deterministic_select_multi_thread() {
+        let seed = b"bytes used to generate seed";
+        let rt1 = tokio::runtime::Builder::new_multi_thread()
+            .worker_threads(1)
+            .rng_seed(RngSeed::from_bytes(seed))
+            .build()
+            .unwrap();
+        let rt1_values = rt1.block_on(async {
+            let _ = tokio::spawn(async { (select_0_to_9().await, select_0_to_9().await) }).await;
+        });
+
+        let rt2 = tokio::runtime::Builder::new_multi_thread()
+            .worker_threads(1)
+            .rng_seed(RngSeed::from_bytes(seed))
+            .build()
+            .unwrap();
+        let rt2_values = rt2.block_on(async {
+            let _ = tokio::spawn(async { (select_0_to_9().await, select_0_to_9().await) }).await;
+        });
+
+        assert_eq!(rt1_values, rt2_values);
+    }
+
+    async fn select_0_to_9() -> u32 {
+        tokio::select!(
+            x = async { 0 } => x,
+            x = async { 1 } => x,
+            x = async { 2 } => x,
+            x = async { 3 } => x,
+            x = async { 4 } => x,
+            x = async { 5 } => x,
+            x = async { 6 } => x,
+            x = async { 7 } => x,
+            x = async { 8 } => x,
+            x = async { 9 } => x,
+        )
+    }
+}
diff --git a/vendor/tokio/tests/macros_test.rs b/vendor/tokio/tests/macros_test.rs
index bca2c9198..85279b7ed 100644
--- a/vendor/tokio/tests/macros_test.rs
+++ b/vendor/tokio/tests/macros_test.rs
@@ -1,3 +1,5 @@
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi doesn't support threading
+
 use tokio::test;
 
 #[test]
@@ -46,3 +48,41 @@ pub async fn issue_4175_test() -> std::io::Result<()> {
     return Ok(());
     panic!();
 }
+
+// https://github.com/tokio-rs/tokio/issues/4175
+#[allow(clippy::let_unit_value)]
+pub mod clippy_semicolon_if_nothing_returned {
+    #![deny(clippy::semicolon_if_nothing_returned)]
+
+    #[tokio::main]
+    pub async fn local() {
+        let _x = ();
+    }
+    #[tokio::main]
+    pub async fn item() {
+        fn _f() {}
+    }
+    #[tokio::main]
+    pub async fn semi() {
+        panic!();
+    }
+    #[tokio::main]
+    pub async fn empty() {
+        // To trigger clippy::semicolon_if_nothing_returned lint, the block needs to contain newline.
+    }
+}
+
+// https://github.com/tokio-rs/tokio/issues/5243
+pub mod issue_5243 {
+    macro_rules! mac {
+        (async fn $name:ident() $b:block) => {
+            #[::tokio::test]
+            async fn $name() {
+                $b
+            }
+        };
+    }
+    mac!(
+        async fn foo() {}
+    );
+}
diff --git a/vendor/tokio/tests/macros_try_join.rs b/vendor/tokio/tests/macros_try_join.rs
index a92515326..74b1c9f94 100644
--- a/vendor/tokio/tests/macros_try_join.rs
+++ b/vendor/tokio/tests/macros_try_join.rs
@@ -1,36 +1,46 @@
-#![allow(clippy::blacklisted_name)]
-use tokio::sync::oneshot;
+#![cfg(feature = "macros")]
+#![allow(clippy::disallowed_names)]
+
+use std::sync::Arc;
+
+use tokio::sync::{oneshot, Semaphore};
 use tokio_test::{assert_pending, assert_ready, task};
 
-#[tokio::test]
+#[cfg(tokio_wasm_not_wasi)]
+use wasm_bindgen_test::wasm_bindgen_test as maybe_tokio_test;
+
+#[cfg(not(tokio_wasm_not_wasi))]
+use tokio::test as maybe_tokio_test;
+
+#[maybe_tokio_test]
 async fn sync_one_lit_expr_comma() {
     let foo = tokio::try_join!(async { ok(1) },);
 
     assert_eq!(foo, Ok((1,)));
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn sync_one_lit_expr_no_comma() {
     let foo = tokio::try_join!(async { ok(1) });
 
     assert_eq!(foo, Ok((1,)));
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn sync_two_lit_expr_comma() {
     let foo = tokio::try_join!(async { ok(1) }, async { ok(2) },);
 
     assert_eq!(foo, Ok((1, 2)));
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn sync_two_lit_expr_no_comma() {
     let foo = tokio::try_join!(async { ok(1) }, async { ok(2) });
 
     assert_eq!(foo, Ok((1, 2)));
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn two_await() {
     let (tx1, rx1) = oneshot::channel::<&str>();
     let (tx2, rx2) = oneshot::channel::<u32>();
@@ -51,7 +61,7 @@ async fn two_await() {
     assert_eq!(Ok(("hello", 123)), res);
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn err_abort_early() {
     let (tx1, rx1) = oneshot::channel::<&str>();
     let (tx2, rx2) = oneshot::channel::<u32>();
@@ -78,6 +88,7 @@ async fn err_abort_early() {
 }
 
 #[test]
+#[cfg(target_pointer_width = "64")]
 fn join_size() {
     use futures::future;
     use std::mem;
@@ -86,16 +97,94 @@ fn join_size() {
         let ready = future::ready(ok(0i32));
         tokio::try_join!(ready)
     };
-    assert_eq!(mem::size_of_val(&fut), 16);
+    assert_eq!(mem::size_of_val(&fut), 32);
 
     let fut = async {
         let ready1 = future::ready(ok(0i32));
         let ready2 = future::ready(ok(0i32));
         tokio::try_join!(ready1, ready2)
     };
-    assert_eq!(mem::size_of_val(&fut), 28);
+    assert_eq!(mem::size_of_val(&fut), 48);
 }
 
 fn ok<T>(val: T) -> Result<T, ()> {
     Ok(val)
 }
+
+async fn non_cooperative_task(permits: Arc<Semaphore>) -> Result<usize, String> {
+    let mut exceeded_budget = 0;
+
+    for _ in 0..5 {
+        // Another task should run after this task uses its whole budget
+        for _ in 0..128 {
+            let _permit = permits.clone().acquire_owned().await.unwrap();
+        }
+
+        exceeded_budget += 1;
+    }
+
+    Ok(exceeded_budget)
+}
+
+async fn poor_little_task(permits: Arc<Semaphore>) -> Result<usize, String> {
+    let mut how_many_times_i_got_to_run = 0;
+
+    for _ in 0..5 {
+        let _permit = permits.clone().acquire_owned().await.unwrap();
+
+        how_many_times_i_got_to_run += 1;
+    }
+
+    Ok(how_many_times_i_got_to_run)
+}
+
+#[tokio::test]
+async fn try_join_does_not_allow_tasks_to_starve() {
+    let permits = Arc::new(Semaphore::new(10));
+
+    // non_cooperative_task should yield after its budget is exceeded and then poor_little_task should run.
+    let result = tokio::try_join!(
+        non_cooperative_task(Arc::clone(&permits)),
+        poor_little_task(permits)
+    );
+
+    let (non_cooperative_result, little_task_result) = result.unwrap();
+
+    assert_eq!(5, non_cooperative_result);
+    assert_eq!(5, little_task_result);
+}
+
+#[tokio::test]
+async fn a_different_future_is_polled_first_every_time_poll_fn_is_polled() {
+    let poll_order = Arc::new(std::sync::Mutex::new(vec![]));
+
+    let fut = |x, poll_order: Arc<std::sync::Mutex<Vec<i32>>>| async move {
+        for _ in 0..4 {
+            {
+                let mut guard = poll_order.lock().unwrap();
+
+                guard.push(x);
+            }
+
+            tokio::task::yield_now().await;
+        }
+    };
+
+    tokio::join!(
+        fut(1, Arc::clone(&poll_order)),
+        fut(2, Arc::clone(&poll_order)),
+        fut(3, Arc::clone(&poll_order)),
+    );
+
+    // Each time the future created by join! is polled, it should start
+    // by polling a different future first.
+    assert_eq!(
+        vec![1, 2, 3, 2, 3, 1, 3, 1, 2, 1, 2, 3],
+        *poll_order.lock().unwrap()
+    );
+}
+
+#[tokio::test]
+async fn empty_try_join() {
+    assert_eq!(tokio::try_join!() as Result<_, ()>, Ok(()));
+}
diff --git a/vendor/tokio/tests/net_bind_resource.rs b/vendor/tokio/tests/net_bind_resource.rs
index d4a0b8dab..76378b3ea 100644
--- a/vendor/tokio/tests/net_bind_resource.rs
+++ b/vendor/tokio/tests/net_bind_resource.rs
@@ -1,9 +1,8 @@
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi doesn't support panic recovery or bind
 
 use tokio::net::TcpListener;
 
-use std::convert::TryFrom;
 use std::net;
 
 #[test]
diff --git a/vendor/tokio/tests/net_lookup_host.rs b/vendor/tokio/tests/net_lookup_host.rs
index 4d0640298..2b346e65e 100644
--- a/vendor/tokio/tests/net_lookup_host.rs
+++ b/vendor/tokio/tests/net_lookup_host.rs
@@ -1,3 +1,5 @@
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi does not support direct socket operations
+
 use tokio::net;
 use tokio_test::assert_ok;
 
diff --git a/vendor/tokio/tests/named_pipe.rs b/vendor/tokio/tests/net_named_pipe.rs
index fd33203f8..02eda48e5 100644
--- a/vendor/tokio/tests/named_pipe.rs
+++ b/vendor/tokio/tests/net_named_pipe.rs
@@ -2,13 +2,11 @@
 #![cfg(all(windows))]
 
 use std::io;
-use std::mem;
-use std::os::windows::io::AsRawHandle;
 use std::time::Duration;
-use tokio::io::AsyncWriteExt;
+use tokio::io::{AsyncReadExt, AsyncWriteExt};
 use tokio::net::windows::named_pipe::{ClientOptions, PipeMode, ServerOptions};
 use tokio::time;
-use winapi::shared::winerror;
+use windows_sys::Win32::Foundation::{ERROR_NO_DATA, ERROR_PIPE_BUSY};
 
 #[tokio::test]
 async fn test_named_pipe_client_drop() -> io::Result<()> {
@@ -16,8 +14,6 @@ async fn test_named_pipe_client_drop() -> io::Result<()> {
 
     let mut server = ServerOptions::new().create(PIPE_NAME)?;
 
-    assert_eq!(num_instances("test-named-pipe-client-drop")?, 1);
-
     let client = ClientOptions::new().open(PIPE_NAME)?;
 
     server.connect().await?;
@@ -25,7 +21,7 @@ async fn test_named_pipe_client_drop() -> io::Result<()> {
 
     // instance will be broken because client is gone
     match server.write_all(b"ping").await {
-        Err(e) if e.raw_os_error() == Some(winerror::ERROR_NO_DATA as i32) => (),
+        Err(e) if e.raw_os_error() == Some(ERROR_NO_DATA as i32) => (),
         x => panic!("{:?}", x),
     }
 
@@ -120,13 +116,13 @@ async fn test_named_pipe_multi_client() -> io::Result<()> {
             let client = loop {
                 match ClientOptions::new().open(PIPE_NAME) {
                     Ok(client) => break client,
-                    Err(e) if e.raw_os_error() == Some(winerror::ERROR_PIPE_BUSY as i32) => (),
+                    Err(e) if e.raw_os_error() == Some(ERROR_PIPE_BUSY as i32) => (),
                     Err(e) if e.kind() == io::ErrorKind::NotFound => (),
                     Err(e) => return Err(e),
                 }
 
                 // Wait for a named pipe to become available.
-                time::sleep(Duration::from_millis(50)).await;
+                time::sleep(Duration::from_millis(10)).await;
             };
 
             let mut client = BufReader::new(client);
@@ -249,13 +245,13 @@ async fn test_named_pipe_multi_client_ready() -> io::Result<()> {
             let client = loop {
                 match ClientOptions::new().open(PIPE_NAME) {
                     Ok(client) => break client,
-                    Err(e) if e.raw_os_error() == Some(winerror::ERROR_PIPE_BUSY as i32) => (),
+                    Err(e) if e.raw_os_error() == Some(ERROR_PIPE_BUSY as i32) => (),
                     Err(e) if e.kind() == io::ErrorKind::NotFound => (),
                     Err(e) => return Err(e),
                 }
 
                 // Wait for a named pipe to become available.
-                time::sleep(Duration::from_millis(50)).await;
+                time::sleep(Duration::from_millis(10)).await;
             };
 
             let mut read_buf = [0u8; 5];
@@ -327,67 +323,77 @@ async fn test_named_pipe_multi_client_ready() -> io::Result<()> {
     Ok(())
 }
 
-// This tests what happens when a client tries to disconnect.
+// This tests that message mode works as expected.
 #[tokio::test]
 async fn test_named_pipe_mode_message() -> io::Result<()> {
-    const PIPE_NAME: &str = r"\\.\pipe\test-named-pipe-mode-message";
+    // it's easy to accidentally get a seemingly working test here because byte pipes
+    // often return contents at write boundaries. to make sure we're doing the right thing we
+    // explicitly test that it doesn't work in byte mode.
+    _named_pipe_mode_message(PipeMode::Message).await?;
+    _named_pipe_mode_message(PipeMode::Byte).await
+}
+
+async fn _named_pipe_mode_message(mode: PipeMode) -> io::Result<()> {
+    let pipe_name = format!(
+        r"\\.\pipe\test-named-pipe-mode-message-{}",
+        matches!(mode, PipeMode::Message)
+    );
+    let mut buf = [0u8; 32];
 
-    let server = ServerOptions::new()
-        .pipe_mode(PipeMode::Message)
-        .create(PIPE_NAME)?;
+    let mut server = ServerOptions::new()
+        .first_pipe_instance(true)
+        .pipe_mode(mode)
+        .create(&pipe_name)?;
+
+    let mut client = ClientOptions::new().pipe_mode(mode).open(&pipe_name)?;
 
-    let _ = ClientOptions::new().open(PIPE_NAME)?;
     server.connect().await?;
+
+    // this needs a few iterations, presumably Windows waits for a few calls before merging buffers
+    for _ in 0..10 {
+        client.write_all(b"hello").await?;
+        server.write_all(b"world").await?;
+    }
+    for _ in 0..10 {
+        let n = server.read(&mut buf).await?;
+        if buf[..n] != b"hello"[..] {
+            assert!(matches!(mode, PipeMode::Byte));
+            return Ok(());
+        }
+        let n = client.read(&mut buf).await?;
+        if buf[..n] != b"world"[..] {
+            assert!(matches!(mode, PipeMode::Byte));
+            return Ok(());
+        }
+    }
+    // byte mode should have errored before.
+    assert!(matches!(mode, PipeMode::Message));
     Ok(())
 }
 
-fn num_instances(pipe_name: impl AsRef<str>) -> io::Result<u32> {
-    use ntapi::ntioapi;
-    use winapi::shared::ntdef;
-
-    let mut name = pipe_name.as_ref().encode_utf16().collect::<Vec<_>>();
-    let mut name = ntdef::UNICODE_STRING {
-        Length: (name.len() * mem::size_of::<u16>()) as u16,
-        MaximumLength: (name.len() * mem::size_of::<u16>()) as u16,
-        Buffer: name.as_mut_ptr(),
-    };
-    let root = std::fs::File::open(r"\\.\Pipe\")?;
-    let mut io_status_block = unsafe { mem::zeroed() };
-    let mut file_directory_information = [0_u8; 1024];
-
-    let status = unsafe {
-        ntioapi::NtQueryDirectoryFile(
-            root.as_raw_handle(),
-            std::ptr::null_mut(),
-            None,
-            std::ptr::null_mut(),
-            &mut io_status_block,
-            &mut file_directory_information as *mut _ as *mut _,
-            1024,
-            ntioapi::FileDirectoryInformation,
-            0,
-            &mut name,
-            0,
-        )
-    };
-
-    if status as u32 != winerror::NO_ERROR {
-        return Err(io::Error::last_os_error());
+// This tests `NamedPipeServer::connect` with various access settings.
+#[tokio::test]
+async fn test_named_pipe_access() -> io::Result<()> {
+    const PIPE_NAME: &str = r"\\.\pipe\test-named-pipe-access";
+
+    for (inb, outb) in [(true, true), (true, false), (false, true)] {
+        let (tx, rx) = tokio::sync::oneshot::channel();
+        let server = tokio::spawn(async move {
+            let s = ServerOptions::new()
+                .access_inbound(inb)
+                .access_outbound(outb)
+                .create(PIPE_NAME)?;
+            let mut connect_fut = tokio_test::task::spawn(s.connect());
+            assert!(connect_fut.poll().is_pending());
+            tx.send(()).unwrap();
+            connect_fut.await
+        });
+
+        // Wait for the server to call connect.
+        rx.await.unwrap();
+        let _ = ClientOptions::new().read(outb).write(inb).open(PIPE_NAME)?;
+
+        server.await??;
     }
-
-    let info = unsafe {
-        mem::transmute::<_, &ntioapi::FILE_DIRECTORY_INFORMATION>(&file_directory_information)
-    };
-    let raw_name = unsafe {
-        std::slice::from_raw_parts(
-            info.FileName.as_ptr(),
-            info.FileNameLength as usize / mem::size_of::<u16>(),
-        )
-    };
-    let name = String::from_utf16(raw_name).unwrap();
-    let num_instances = unsafe { *info.EndOfFile.QuadPart() };
-
-    assert_eq!(name, pipe_name.as_ref());
-
-    Ok(num_instances as u32)
+    Ok(())
 }
diff --git a/vendor/tokio/tests/net_panic.rs b/vendor/tokio/tests/net_panic.rs
new file mode 100644
index 000000000..fc2209ad4
--- /dev/null
+++ b/vendor/tokio/tests/net_panic.rs
@@ -0,0 +1,188 @@
+#![warn(rust_2018_idioms)]
+#![cfg(all(feature = "full", not(tokio_wasi)))]
+
+use std::error::Error;
+use tokio::net::{TcpListener, TcpStream};
+use tokio::runtime::{Builder, Runtime};
+
+mod support {
+    pub mod panic;
+}
+use support::panic::test_panic;
+
+#[test]
+fn udp_socket_from_std_panic_caller() -> Result<(), Box<dyn Error>> {
+    use std::net::SocketAddr;
+    use tokio::net::UdpSocket;
+
+    let addr = "127.0.0.1:0".parse::<SocketAddr>().unwrap();
+    let std_sock = std::net::UdpSocket::bind(addr).unwrap();
+    std_sock.set_nonblocking(true).unwrap();
+
+    let panic_location_file = test_panic(|| {
+        let rt = runtime_without_io();
+        rt.block_on(async {
+            let _sock = UdpSocket::from_std(std_sock);
+        });
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+fn tcp_listener_from_std_panic_caller() -> Result<(), Box<dyn Error>> {
+    let std_listener = std::net::TcpListener::bind("127.0.0.1:0").unwrap();
+    std_listener.set_nonblocking(true).unwrap();
+
+    let panic_location_file = test_panic(|| {
+        let rt = runtime_without_io();
+        rt.block_on(async {
+            let _ = TcpListener::from_std(std_listener);
+        });
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+fn tcp_stream_from_std_panic_caller() -> Result<(), Box<dyn Error>> {
+    let std_listener = std::net::TcpListener::bind("127.0.0.1:0").unwrap();
+
+    let std_stream = std::net::TcpStream::connect(std_listener.local_addr().unwrap()).unwrap();
+    std_stream.set_nonblocking(true).unwrap();
+
+    let panic_location_file = test_panic(|| {
+        let rt = runtime_without_io();
+        rt.block_on(async {
+            let _ = TcpStream::from_std(std_stream);
+        });
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+#[cfg(unix)]
+fn unix_listener_bind_panic_caller() -> Result<(), Box<dyn Error>> {
+    use tokio::net::UnixListener;
+
+    let dir = tempfile::tempdir().unwrap();
+    let sock_path = dir.path().join("socket");
+
+    let panic_location_file = test_panic(|| {
+        let rt = runtime_without_io();
+        rt.block_on(async {
+            let _ = UnixListener::bind(&sock_path);
+        });
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+#[cfg(unix)]
+fn unix_listener_from_std_panic_caller() -> Result<(), Box<dyn Error>> {
+    use tokio::net::UnixListener;
+
+    let dir = tempfile::tempdir().unwrap();
+    let sock_path = dir.path().join("socket");
+    let std_listener = std::os::unix::net::UnixListener::bind(&sock_path).unwrap();
+
+    let panic_location_file = test_panic(|| {
+        let rt = runtime_without_io();
+        rt.block_on(async {
+            let _ = UnixListener::from_std(std_listener);
+        });
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+#[cfg(unix)]
+fn unix_stream_from_std_panic_caller() -> Result<(), Box<dyn Error>> {
+    use tokio::net::UnixStream;
+
+    let dir = tempfile::tempdir().unwrap();
+    let sock_path = dir.path().join("socket");
+    let _std_listener = std::os::unix::net::UnixListener::bind(&sock_path).unwrap();
+    let std_stream = std::os::unix::net::UnixStream::connect(&sock_path).unwrap();
+
+    let panic_location_file = test_panic(|| {
+        let rt = runtime_without_io();
+        rt.block_on(async {
+            let _ = UnixStream::from_std(std_stream);
+        });
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+#[cfg(unix)]
+fn unix_datagram_from_std_panic_caller() -> Result<(), Box<dyn Error>> {
+    use std::os::unix::net::UnixDatagram as StdUDS;
+    use tokio::net::UnixDatagram;
+
+    let dir = tempfile::tempdir().unwrap();
+    let sock_path = dir.path().join("socket");
+
+    // Bind the socket to a filesystem path
+    // /let socket_path = tmp.path().join("socket");
+    let std_socket = StdUDS::bind(&sock_path).unwrap();
+    std_socket.set_nonblocking(true).unwrap();
+
+    let panic_location_file = test_panic(move || {
+        let rt = runtime_without_io();
+        rt.block_on(async {
+            let _ = UnixDatagram::from_std(std_socket);
+        });
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+#[cfg(windows)]
+fn server_options_max_instances_panic_caller() -> Result<(), Box<dyn Error>> {
+    use tokio::net::windows::named_pipe::ServerOptions;
+
+    let panic_location_file = test_panic(move || {
+        let rt = runtime_without_io();
+        rt.block_on(async {
+            let mut options = ServerOptions::new();
+            options.max_instances(255);
+        });
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+// Runtime without `enable_io` so it has no IO driver set.
+fn runtime_without_io() -> Runtime {
+    Builder::new_current_thread().build().unwrap()
+}
diff --git a/vendor/tokio/tests/net_unix_pipe.rs b/vendor/tokio/tests/net_unix_pipe.rs
new file mode 100644
index 000000000..c96d6e70f
--- /dev/null
+++ b/vendor/tokio/tests/net_unix_pipe.rs
@@ -0,0 +1,429 @@
+#![cfg(feature = "full")]
+#![cfg(unix)]
+
+use tokio::io::{AsyncReadExt, AsyncWriteExt, Interest};
+use tokio::net::unix::pipe;
+use tokio_test::task;
+use tokio_test::{assert_err, assert_ok, assert_pending, assert_ready_ok};
+
+use std::fs::File;
+use std::io;
+use std::os::unix::fs::OpenOptionsExt;
+use std::os::unix::io::AsRawFd;
+use std::path::{Path, PathBuf};
+
+/// Helper struct which will clean up temporary files once dropped.
+struct TempFifo {
+    path: PathBuf,
+    _dir: tempfile::TempDir,
+}
+
+impl TempFifo {
+    fn new(name: &str) -> io::Result<TempFifo> {
+        let dir = tempfile::Builder::new()
+            .prefix("tokio-fifo-tests")
+            .tempdir()?;
+        let path = dir.path().join(name);
+        nix::unistd::mkfifo(&path, nix::sys::stat::Mode::S_IRWXU)?;
+
+        Ok(TempFifo { path, _dir: dir })
+    }
+}
+
+impl AsRef<Path> for TempFifo {
+    fn as_ref(&self) -> &Path {
+        self.path.as_ref()
+    }
+}
+
+#[tokio::test]
+async fn fifo_simple_send() -> io::Result<()> {
+    const DATA: &[u8] = b"this is some data to write to the fifo";
+
+    let fifo = TempFifo::new("simple_send")?;
+
+    // Create a reading task which should wait for data from the pipe.
+    let mut reader = pipe::OpenOptions::new().open_receiver(&fifo)?;
+    let mut read_fut = task::spawn(async move {
+        let mut buf = vec![0; DATA.len()];
+        reader.read_exact(&mut buf).await?;
+        Ok::<_, io::Error>(buf)
+    });
+    assert_pending!(read_fut.poll());
+
+    let mut writer = pipe::OpenOptions::new().open_sender(&fifo)?;
+    writer.write_all(DATA).await?;
+
+    // Let the IO driver poll events for the reader.
+    while !read_fut.is_woken() {
+        tokio::task::yield_now().await;
+    }
+
+    // Reading task should be ready now.
+    let read_data = assert_ready_ok!(read_fut.poll());
+    assert_eq!(&read_data, DATA);
+
+    Ok(())
+}
+
+#[tokio::test]
+#[cfg(target_os = "linux")]
+async fn fifo_simple_send_sender_first() -> io::Result<()> {
+    const DATA: &[u8] = b"this is some data to write to the fifo";
+
+    // Create a new fifo file with *no reading ends open*.
+    let fifo = TempFifo::new("simple_send_sender_first")?;
+
+    // Simple `open_sender` should fail with ENXIO (no such device or address).
+    let err = assert_err!(pipe::OpenOptions::new().open_sender(&fifo));
+    assert_eq!(err.raw_os_error(), Some(libc::ENXIO));
+
+    // `open_sender` in read-write mode should succeed and the pipe should be ready to write.
+    let mut writer = pipe::OpenOptions::new()
+        .read_write(true)
+        .open_sender(&fifo)?;
+    writer.write_all(DATA).await?;
+
+    // Read the written data and validate.
+    let mut reader = pipe::OpenOptions::new().open_receiver(&fifo)?;
+    let mut read_data = vec![0; DATA.len()];
+    reader.read_exact(&mut read_data).await?;
+    assert_eq!(&read_data, DATA);
+
+    Ok(())
+}
+
+// Opens a FIFO file, write and *close the writer*.
+async fn write_and_close(path: impl AsRef<Path>, msg: &[u8]) -> io::Result<()> {
+    let mut writer = pipe::OpenOptions::new().open_sender(path)?;
+    writer.write_all(msg).await?;
+    drop(writer); // Explicit drop.
+    Ok(())
+}
+
+/// Checks EOF behavior with single reader and writers sequentially opening
+/// and closing a FIFO.
+#[tokio::test]
+async fn fifo_multiple_writes() -> io::Result<()> {
+    const DATA: &[u8] = b"this is some data to write to the fifo";
+
+    let fifo = TempFifo::new("fifo_multiple_writes")?;
+
+    let mut reader = pipe::OpenOptions::new().open_receiver(&fifo)?;
+
+    write_and_close(&fifo, DATA).await?;
+    let ev = reader.ready(Interest::READABLE).await?;
+    assert!(ev.is_readable());
+    let mut read_data = vec![0; DATA.len()];
+    assert_ok!(reader.read_exact(&mut read_data).await);
+
+    // Check that reader hits EOF.
+    let err = assert_err!(reader.read_exact(&mut read_data).await);
+    assert_eq!(err.kind(), io::ErrorKind::UnexpectedEof);
+
+    // Write more data and read again.
+    write_and_close(&fifo, DATA).await?;
+    assert_ok!(reader.read_exact(&mut read_data).await);
+
+    Ok(())
+}
+
+/// Checks behavior of a resilient reader (Receiver in O_RDWR access mode)
+/// with writers sequentially opening and closing a FIFO.
+#[tokio::test]
+#[cfg(target_os = "linux")]
+async fn fifo_resilient_reader() -> io::Result<()> {
+    const DATA: &[u8] = b"this is some data to write to the fifo";
+
+    let fifo = TempFifo::new("fifo_resilient_reader")?;
+
+    // Open reader in read-write access mode.
+    let mut reader = pipe::OpenOptions::new()
+        .read_write(true)
+        .open_receiver(&fifo)?;
+
+    write_and_close(&fifo, DATA).await?;
+    let ev = reader.ready(Interest::READABLE).await?;
+    let mut read_data = vec![0; DATA.len()];
+    reader.read_exact(&mut read_data).await?;
+
+    // Check that reader didn't hit EOF.
+    assert!(!ev.is_read_closed());
+
+    // Resilient reader can asynchronously wait for the next writer.
+    let mut second_read_fut = task::spawn(reader.read_exact(&mut read_data));
+    assert_pending!(second_read_fut.poll());
+
+    // Write more data and read again.
+    write_and_close(&fifo, DATA).await?;
+    assert_ok!(second_read_fut.await);
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn open_detects_not_a_fifo() -> io::Result<()> {
+    let dir = tempfile::Builder::new()
+        .prefix("tokio-fifo-tests")
+        .tempdir()
+        .unwrap();
+    let path = dir.path().join("not_a_fifo");
+
+    // Create an ordinary file.
+    File::create(&path)?;
+
+    // Check if Sender detects invalid file type.
+    let err = assert_err!(pipe::OpenOptions::new().open_sender(&path));
+    assert_eq!(err.kind(), io::ErrorKind::InvalidInput);
+
+    // Check if Receiver detects invalid file type.
+    let err = assert_err!(pipe::OpenOptions::new().open_sender(&path));
+    assert_eq!(err.kind(), io::ErrorKind::InvalidInput);
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn from_file() -> io::Result<()> {
+    const DATA: &[u8] = b"this is some data to write to the fifo";
+
+    let fifo = TempFifo::new("from_file")?;
+
+    // Construct a Receiver from a File.
+    let file = std::fs::OpenOptions::new()
+        .read(true)
+        .custom_flags(libc::O_NONBLOCK)
+        .open(&fifo)?;
+    let mut reader = pipe::Receiver::from_file(file)?;
+
+    // Construct a Sender from a File.
+    let file = std::fs::OpenOptions::new()
+        .write(true)
+        .custom_flags(libc::O_NONBLOCK)
+        .open(&fifo)?;
+    let mut writer = pipe::Sender::from_file(file)?;
+
+    // Write and read some data to test async.
+    let mut read_fut = task::spawn(async move {
+        let mut buf = vec![0; DATA.len()];
+        reader.read_exact(&mut buf).await?;
+        Ok::<_, io::Error>(buf)
+    });
+    assert_pending!(read_fut.poll());
+
+    writer.write_all(DATA).await?;
+
+    let read_data = assert_ok!(read_fut.await);
+    assert_eq!(&read_data, DATA);
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn from_file_detects_not_a_fifo() -> io::Result<()> {
+    let dir = tempfile::Builder::new()
+        .prefix("tokio-fifo-tests")
+        .tempdir()
+        .unwrap();
+    let path = dir.path().join("not_a_fifo");
+
+    // Create an ordinary file.
+    File::create(&path)?;
+
+    // Check if Sender detects invalid file type.
+    let file = std::fs::OpenOptions::new().write(true).open(&path)?;
+    let err = assert_err!(pipe::Sender::from_file(file));
+    assert_eq!(err.kind(), io::ErrorKind::InvalidInput);
+
+    // Check if Receiver detects invalid file type.
+    let file = std::fs::OpenOptions::new().read(true).open(&path)?;
+    let err = assert_err!(pipe::Receiver::from_file(file));
+    assert_eq!(err.kind(), io::ErrorKind::InvalidInput);
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn from_file_detects_wrong_access_mode() -> io::Result<()> {
+    let fifo = TempFifo::new("wrong_access_mode")?;
+
+    // Open a read end to open the fifo for writing.
+    let _reader = pipe::OpenOptions::new().open_receiver(&fifo)?;
+
+    // Check if Receiver detects write-only access mode.
+    let wronly = std::fs::OpenOptions::new()
+        .write(true)
+        .custom_flags(libc::O_NONBLOCK)
+        .open(&fifo)?;
+    let err = assert_err!(pipe::Receiver::from_file(wronly));
+    assert_eq!(err.kind(), io::ErrorKind::InvalidInput);
+
+    // Check if Sender detects read-only access mode.
+    let rdonly = std::fs::OpenOptions::new()
+        .read(true)
+        .custom_flags(libc::O_NONBLOCK)
+        .open(&fifo)?;
+    let err = assert_err!(pipe::Sender::from_file(rdonly));
+    assert_eq!(err.kind(), io::ErrorKind::InvalidInput);
+
+    Ok(())
+}
+
+fn is_nonblocking<T: AsRawFd>(fd: &T) -> io::Result<bool> {
+    let flags = nix::fcntl::fcntl(fd.as_raw_fd(), nix::fcntl::F_GETFL)?;
+    Ok((flags & libc::O_NONBLOCK) != 0)
+}
+
+#[tokio::test]
+async fn from_file_sets_nonblock() -> io::Result<()> {
+    let fifo = TempFifo::new("sets_nonblock")?;
+
+    // Open read and write ends to let blocking files open.
+    let _reader = pipe::OpenOptions::new().open_receiver(&fifo)?;
+    let _writer = pipe::OpenOptions::new().open_sender(&fifo)?;
+
+    // Check if Receiver sets the pipe in non-blocking mode.
+    let rdonly = std::fs::OpenOptions::new().read(true).open(&fifo)?;
+    assert!(!is_nonblocking(&rdonly)?);
+    let reader = pipe::Receiver::from_file(rdonly)?;
+    assert!(is_nonblocking(&reader)?);
+
+    // Check if Sender sets the pipe in non-blocking mode.
+    let wronly = std::fs::OpenOptions::new().write(true).open(&fifo)?;
+    assert!(!is_nonblocking(&wronly)?);
+    let writer = pipe::Sender::from_file(wronly)?;
+    assert!(is_nonblocking(&writer)?);
+
+    Ok(())
+}
+
+fn writable_by_poll(writer: &pipe::Sender) -> bool {
+    task::spawn(writer.writable()).poll().is_ready()
+}
+
+#[tokio::test]
+async fn try_read_write() -> io::Result<()> {
+    const DATA: &[u8] = b"this is some data to write to the fifo";
+
+    // Create a pipe pair over a fifo file.
+    let fifo = TempFifo::new("try_read_write")?;
+    let reader = pipe::OpenOptions::new().open_receiver(&fifo)?;
+    let writer = pipe::OpenOptions::new().open_sender(&fifo)?;
+
+    // Fill the pipe buffer with `try_write`.
+    let mut write_data = Vec::new();
+    while writable_by_poll(&writer) {
+        match writer.try_write(DATA) {
+            Ok(n) => write_data.extend(&DATA[..n]),
+            Err(e) => {
+                assert_eq!(e.kind(), io::ErrorKind::WouldBlock);
+                break;
+            }
+        }
+    }
+
+    // Drain the pipe buffer with `try_read`.
+    let mut read_data = vec![0; write_data.len()];
+    let mut i = 0;
+    while i < write_data.len() {
+        reader.readable().await?;
+        match reader.try_read(&mut read_data[i..]) {
+            Ok(n) => i += n,
+            Err(e) => {
+                assert_eq!(e.kind(), io::ErrorKind::WouldBlock);
+                continue;
+            }
+        }
+    }
+
+    assert_eq!(read_data, write_data);
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn try_read_write_vectored() -> io::Result<()> {
+    const DATA: &[u8] = b"this is some data to write to the fifo";
+
+    // Create a pipe pair over a fifo file.
+    let fifo = TempFifo::new("try_read_write_vectored")?;
+    let reader = pipe::OpenOptions::new().open_receiver(&fifo)?;
+    let writer = pipe::OpenOptions::new().open_sender(&fifo)?;
+
+    let write_bufs: Vec<_> = DATA.chunks(3).map(io::IoSlice::new).collect();
+
+    // Fill the pipe buffer with `try_write_vectored`.
+    let mut write_data = Vec::new();
+    while writable_by_poll(&writer) {
+        match writer.try_write_vectored(&write_bufs) {
+            Ok(n) => write_data.extend(&DATA[..n]),
+            Err(e) => {
+                assert_eq!(e.kind(), io::ErrorKind::WouldBlock);
+                break;
+            }
+        }
+    }
+
+    // Drain the pipe buffer with `try_read_vectored`.
+    let mut read_data = vec![0; write_data.len()];
+    let mut i = 0;
+    while i < write_data.len() {
+        reader.readable().await?;
+
+        let mut read_bufs: Vec<_> = read_data[i..]
+            .chunks_mut(0x10000)
+            .map(io::IoSliceMut::new)
+            .collect();
+        match reader.try_read_vectored(&mut read_bufs) {
+            Ok(n) => i += n,
+            Err(e) => {
+                assert_eq!(e.kind(), io::ErrorKind::WouldBlock);
+                continue;
+            }
+        }
+    }
+
+    assert_eq!(read_data, write_data);
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn try_read_buf() -> std::io::Result<()> {
+    const DATA: &[u8] = b"this is some data to write to the fifo";
+
+    // Create a pipe pair over a fifo file.
+    let fifo = TempFifo::new("try_read_write_vectored")?;
+    let reader = pipe::OpenOptions::new().open_receiver(&fifo)?;
+    let writer = pipe::OpenOptions::new().open_sender(&fifo)?;
+
+    // Fill the pipe buffer with `try_write`.
+    let mut write_data = Vec::new();
+    while writable_by_poll(&writer) {
+        match writer.try_write(DATA) {
+            Ok(n) => write_data.extend(&DATA[..n]),
+            Err(e) => {
+                assert_eq!(e.kind(), io::ErrorKind::WouldBlock);
+                break;
+            }
+        }
+    }
+
+    // Drain the pipe buffer with `try_read_buf`.
+    let mut read_data = vec![0; write_data.len()];
+    let mut i = 0;
+    while i < write_data.len() {
+        reader.readable().await?;
+        match reader.try_read_buf(&mut read_data) {
+            Ok(n) => i += n,
+            Err(e) => {
+                assert_eq!(e.kind(), io::ErrorKind::WouldBlock);
+                continue;
+            }
+        }
+    }
+
+    assert_eq!(read_data, write_data);
+
+    Ok(())
+}
diff --git a/vendor/tokio/tests/no_rt.rs b/vendor/tokio/tests/no_rt.rs
index 8437b8046..747fab6af 100644
--- a/vendor/tokio/tests/no_rt.rs
+++ b/vendor/tokio/tests/no_rt.rs
@@ -1,3 +1,5 @@
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi does not support panic recovery
+
 use tokio::net::TcpStream;
 use tokio::sync::oneshot;
 use tokio::time::{timeout, Duration};
@@ -26,7 +28,7 @@ fn panics_when_no_reactor() {
 
 async fn timeout_value() {
     let (_tx, rx) = oneshot::channel::<()>();
-    let dur = Duration::from_millis(20);
+    let dur = Duration::from_millis(10);
     let _ = timeout(dur, rx).await;
 }
 
diff --git a/vendor/tokio/tests/process_arg0.rs b/vendor/tokio/tests/process_arg0.rs
new file mode 100644
index 000000000..4fabea0fe
--- /dev/null
+++ b/vendor/tokio/tests/process_arg0.rs
@@ -0,0 +1,13 @@
+#![warn(rust_2018_idioms)]
+#![cfg(all(feature = "full", unix))]
+
+use tokio::process::Command;
+
+#[tokio::test]
+async fn arg0() {
+    let mut cmd = Command::new("sh");
+    cmd.arg0("test_string").arg("-c").arg("echo $0");
+
+    let output = cmd.output().await.unwrap();
+    assert_eq!(output.stdout, b"test_string\n");
+}
diff --git a/vendor/tokio/tests/process_kill_on_drop.rs b/vendor/tokio/tests/process_kill_on_drop.rs
index 00f5c6dc6..d919b1a27 100644
--- a/vendor/tokio/tests/process_kill_on_drop.rs
+++ b/vendor/tokio/tests/process_kill_on_drop.rs
@@ -1,6 +1,7 @@
 #![cfg(all(unix, feature = "process"))]
 #![warn(rust_2018_idioms)]
 
+use std::io::ErrorKind;
 use std::process::Stdio;
 use std::time::Duration;
 use tokio::io::AsyncReadExt;
@@ -11,7 +12,7 @@ use tokio_test::assert_ok;
 #[tokio::test]
 async fn kill_on_drop() {
     let mut cmd = Command::new("bash");
-    cmd.args(&[
+    cmd.args([
         "-c",
         "
        # Fork another child that won't get killed
@@ -24,11 +25,12 @@ async fn kill_on_drop() {
     ",
     ]);
 
-    let mut child = cmd
-        .kill_on_drop(true)
-        .stdout(Stdio::piped())
-        .spawn()
-        .unwrap();
+    let e = cmd.kill_on_drop(true).stdout(Stdio::piped()).spawn();
+    if e.is_err() && e.as_ref().unwrap_err().kind() == ErrorKind::NotFound {
+        println!("bash not available; skipping test");
+        return;
+    }
+    let mut child = e.unwrap();
 
     sleep(Duration::from_secs(2)).await;
 
diff --git a/vendor/tokio/tests/process_raw_handle.rs b/vendor/tokio/tests/process_raw_handle.rs
new file mode 100644
index 000000000..fbe22b07c
--- /dev/null
+++ b/vendor/tokio/tests/process_raw_handle.rs
@@ -0,0 +1,23 @@
+#![warn(rust_2018_idioms)]
+#![cfg(feature = "full")]
+#![cfg(windows)]
+
+use tokio::process::Command;
+use windows_sys::Win32::System::Threading::GetProcessId;
+
+#[tokio::test]
+async fn obtain_raw_handle() {
+    let mut cmd = Command::new("cmd");
+    cmd.kill_on_drop(true);
+    cmd.arg("/c");
+    cmd.arg("pause");
+
+    let child = cmd.spawn().unwrap();
+
+    let orig_id = child.id().expect("missing id");
+    assert!(orig_id > 0);
+
+    let handle = child.raw_handle().expect("process stopped");
+    let handled_id = unsafe { GetProcessId(handle as _) };
+    assert_eq!(handled_id, orig_id);
+}
diff --git a/vendor/tokio/tests/process_smoke.rs b/vendor/tokio/tests/process_smoke.rs
index fae5793fa..81d2020a0 100644
--- a/vendor/tokio/tests/process_smoke.rs
+++ b/vendor/tokio/tests/process_smoke.rs
@@ -1,5 +1,5 @@
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi cannot run system commands
 
 use tokio::process::Command;
 use tokio_test::assert_ok;
diff --git a/vendor/tokio/tests/rt_basic.rs b/vendor/tokio/tests/rt_basic.rs
index 4b1bdadc1..6caf0a44b 100644
--- a/vendor/tokio/tests/rt_basic.rs
+++ b/vendor/tokio/tests/rt_basic.rs
@@ -3,15 +3,28 @@
 
 use tokio::runtime::Runtime;
 use tokio::sync::oneshot;
+use tokio::time::{timeout, Duration};
 use tokio_test::{assert_err, assert_ok};
 
+use std::future::Future;
+use std::pin::Pin;
+use std::sync::atomic::{AtomicBool, Ordering};
+use std::task::{Context, Poll};
 use std::thread;
-use tokio::time::{timeout, Duration};
 
 mod support {
     pub(crate) mod mpsc_stream;
 }
 
+macro_rules! cfg_metrics {
+    ($($t:tt)*) => {
+        #[cfg(tokio_unstable)]
+        {
+            $( $t )*
+        }
+    }
+}
+
 #[test]
 fn spawned_task_does_not_progress_without_block_on() {
     let (tx, mut rx) = oneshot::channel();
@@ -136,6 +149,134 @@ fn acquire_mutex_in_drop() {
 }
 
 #[test]
+fn drop_tasks_in_context() {
+    static SUCCESS: AtomicBool = AtomicBool::new(false);
+
+    struct ContextOnDrop;
+
+    impl Future for ContextOnDrop {
+        type Output = ();
+
+        fn poll(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<()> {
+            Poll::Pending
+        }
+    }
+
+    impl Drop for ContextOnDrop {
+        fn drop(&mut self) {
+            if tokio::runtime::Handle::try_current().is_ok() {
+                SUCCESS.store(true, Ordering::SeqCst);
+            }
+        }
+    }
+
+    let rt = rt();
+    rt.spawn(ContextOnDrop);
+    drop(rt);
+
+    assert!(SUCCESS.load(Ordering::SeqCst));
+}
+
+#[test]
+#[cfg_attr(tokio_wasi, ignore = "Wasi does not support panic recovery")]
+#[should_panic(expected = "boom")]
+fn wake_in_drop_after_panic() {
+    let (tx, rx) = oneshot::channel::<()>();
+
+    struct WakeOnDrop(Option<oneshot::Sender<()>>);
+
+    impl Drop for WakeOnDrop {
+        fn drop(&mut self) {
+            self.0.take().unwrap().send(()).unwrap();
+        }
+    }
+
+    let rt = rt();
+
+    rt.spawn(async move {
+        let _wake_on_drop = WakeOnDrop(Some(tx));
+        // wait forever
+        futures::future::pending::<()>().await;
+    });
+
+    let _join = rt.spawn(async move { rx.await });
+
+    rt.block_on(async {
+        tokio::task::yield_now().await;
+        panic!("boom");
+    });
+}
+
+#[test]
+fn spawn_two() {
+    let rt = rt();
+
+    let out = rt.block_on(async {
+        let (tx, rx) = oneshot::channel();
+
+        tokio::spawn(async move {
+            tokio::spawn(async move {
+                tx.send("ZOMG").unwrap();
+            });
+        });
+
+        assert_ok!(rx.await)
+    });
+
+    assert_eq!(out, "ZOMG");
+
+    cfg_metrics! {
+        let metrics = rt.metrics();
+        drop(rt);
+        assert_eq!(0, metrics.remote_schedule_count());
+
+        let mut local = 0;
+        for i in 0..metrics.num_workers() {
+            local += metrics.worker_local_schedule_count(i);
+        }
+
+        assert_eq!(2, local);
+    }
+}
+
+#[cfg_attr(tokio_wasi, ignore = "WASI: std::thread::spawn not supported")]
+#[test]
+fn spawn_remote() {
+    let rt = rt();
+
+    let out = rt.block_on(async {
+        let (tx, rx) = oneshot::channel();
+
+        let handle = tokio::spawn(async move {
+            std::thread::spawn(move || {
+                std::thread::sleep(Duration::from_millis(10));
+                tx.send("ZOMG").unwrap();
+            });
+
+            rx.await.unwrap()
+        });
+
+        handle.await.unwrap()
+    });
+
+    assert_eq!(out, "ZOMG");
+
+    cfg_metrics! {
+        let metrics = rt.metrics();
+        drop(rt);
+        assert_eq!(1, metrics.remote_schedule_count());
+
+        let mut local = 0;
+        for i in 0..metrics.num_workers() {
+            local += metrics.worker_local_schedule_count(i);
+        }
+
+        assert_eq!(1, local);
+    }
+}
+
+#[test]
+#[cfg_attr(tokio_wasi, ignore = "Wasi does not support panic recovery")]
 #[should_panic(
     expected = "A Tokio 1.x context was found, but timers are disabled. Call `enable_time` on the runtime builder to enable timers."
 )]
@@ -150,6 +291,155 @@ fn timeout_panics_when_no_time_handle() {
     });
 }
 
+#[cfg(tokio_unstable)]
+mod unstable {
+    use tokio::runtime::{Builder, RngSeed, UnhandledPanic};
+
+    #[test]
+    #[should_panic(
+        expected = "a spawned task panicked and the runtime is configured to shut down on unhandled panic"
+    )]
+    fn shutdown_on_panic() {
+        let rt = Builder::new_current_thread()
+            .unhandled_panic(UnhandledPanic::ShutdownRuntime)
+            .build()
+            .unwrap();
+
+        rt.block_on(async {
+            tokio::spawn(async {
+                panic!("boom");
+            });
+
+            futures::future::pending::<()>().await;
+        })
+    }
+
+    #[test]
+    #[cfg_attr(tokio_wasi, ignore = "Wasi does not support panic recovery")]
+    fn spawns_do_nothing() {
+        use std::sync::Arc;
+
+        let rt = Builder::new_current_thread()
+            .unhandled_panic(UnhandledPanic::ShutdownRuntime)
+            .build()
+            .unwrap();
+
+        let rt1 = Arc::new(rt);
+        let rt2 = rt1.clone();
+
+        let _ = std::thread::spawn(move || {
+            rt2.block_on(async {
+                tokio::spawn(async {
+                    panic!("boom");
+                });
+
+                futures::future::pending::<()>().await;
+            })
+        })
+        .join();
+
+        let task = rt1.spawn(async {});
+        let res = futures::executor::block_on(task);
+        assert!(res.is_err());
+    }
+
+    #[test]
+    #[cfg_attr(tokio_wasi, ignore = "Wasi does not support panic recovery")]
+    fn shutdown_all_concurrent_block_on() {
+        const N: usize = 2;
+        use std::sync::{mpsc, Arc};
+
+        let rt = Builder::new_current_thread()
+            .unhandled_panic(UnhandledPanic::ShutdownRuntime)
+            .build()
+            .unwrap();
+
+        let rt = Arc::new(rt);
+        let mut ths = vec![];
+        let (tx, rx) = mpsc::channel();
+
+        for _ in 0..N {
+            let rt = rt.clone();
+            let tx = tx.clone();
+            ths.push(std::thread::spawn(move || {
+                rt.block_on(async {
+                    tx.send(()).unwrap();
+                    futures::future::pending::<()>().await;
+                });
+            }));
+        }
+
+        for _ in 0..N {
+            rx.recv().unwrap();
+        }
+
+        rt.spawn(async {
+            panic!("boom");
+        });
+
+        for th in ths {
+            assert!(th.join().is_err());
+        }
+    }
+
+    #[test]
+    fn rng_seed() {
+        let seed = b"bytes used to generate seed";
+        let rt1 = tokio::runtime::Builder::new_current_thread()
+            .rng_seed(RngSeed::from_bytes(seed))
+            .build()
+            .unwrap();
+        let rt1_values = rt1.block_on(async {
+            let rand_1 = tokio::macros::support::thread_rng_n(100);
+            let rand_2 = tokio::macros::support::thread_rng_n(100);
+
+            (rand_1, rand_2)
+        });
+
+        let rt2 = tokio::runtime::Builder::new_current_thread()
+            .rng_seed(RngSeed::from_bytes(seed))
+            .build()
+            .unwrap();
+        let rt2_values = rt2.block_on(async {
+            let rand_1 = tokio::macros::support::thread_rng_n(100);
+            let rand_2 = tokio::macros::support::thread_rng_n(100);
+
+            (rand_1, rand_2)
+        });
+
+        assert_eq!(rt1_values, rt2_values);
+    }
+
+    #[test]
+    fn rng_seed_multi_enter() {
+        let seed = b"bytes used to generate seed";
+
+        fn two_rand_values() -> (u32, u32) {
+            let rand_1 = tokio::macros::support::thread_rng_n(100);
+            let rand_2 = tokio::macros::support::thread_rng_n(100);
+
+            (rand_1, rand_2)
+        }
+
+        let rt1 = tokio::runtime::Builder::new_current_thread()
+            .rng_seed(RngSeed::from_bytes(seed))
+            .build()
+            .unwrap();
+        let rt1_values_1 = rt1.block_on(async { two_rand_values() });
+        let rt1_values_2 = rt1.block_on(async { two_rand_values() });
+
+        let rt2 = tokio::runtime::Builder::new_current_thread()
+            .rng_seed(RngSeed::from_bytes(seed))
+            .build()
+            .unwrap();
+        let rt2_values_1 = rt2.block_on(async { two_rand_values() });
+        let rt2_values_2 = rt2.block_on(async { two_rand_values() });
+
+        assert_eq!(rt1_values_1, rt2_values_1);
+        assert_eq!(rt1_values_2, rt2_values_2);
+    }
+}
+
 fn rt() -> Runtime {
     tokio::runtime::Builder::new_current_thread()
         .enable_all()
diff --git a/vendor/tokio/tests/rt_common.rs b/vendor/tokio/tests/rt_common.rs
index cb1d0f661..9c6add047 100644
--- a/vendor/tokio/tests/rt_common.rs
+++ b/vendor/tokio/tests/rt_common.rs
@@ -2,13 +2,16 @@
 #![warn(rust_2018_idioms)]
 #![cfg(feature = "full")]
 
-// Tests to run on both current-thread & thread-pool runtime variants.
+// Tests to run on both current-thread & multi-thread runtime variants.
 
 macro_rules! rt_test {
     ($($t:tt)*) => {
         mod current_thread_scheduler {
             $($t)*
 
+            #[cfg(not(target_os="wasi"))]
+            const NUM_WORKERS: usize = 1;
+
             fn rt() -> Arc<Runtime> {
                 tokio::runtime::Builder::new_current_thread()
                     .enable_all()
@@ -18,9 +21,12 @@ macro_rules! rt_test {
             }
         }
 
+        #[cfg(not(tokio_wasi))] // Wasi doesn't support threads
         mod threaded_scheduler_4_threads {
             $($t)*
 
+            const NUM_WORKERS: usize = 4;
+
             fn rt() -> Arc<Runtime> {
                 tokio::runtime::Builder::new_multi_thread()
                     .worker_threads(4)
@@ -31,9 +37,12 @@ macro_rules! rt_test {
             }
         }
 
+        #[cfg(not(tokio_wasi))] // Wasi doesn't support threads
         mod threaded_scheduler_1_thread {
             $($t)*
 
+            const NUM_WORKERS: usize = 1;
+
             fn rt() -> Arc<Runtime> {
                 tokio::runtime::Builder::new_multi_thread()
                     .worker_threads(1)
@@ -55,18 +64,30 @@ fn send_sync_bound() {
 }
 
 rt_test! {
-    use tokio::net::{TcpListener, TcpStream, UdpSocket};
+    #[cfg(not(target_os="wasi"))]
+    use tokio::net::{TcpListener, TcpStream};
+    #[cfg(not(target_os="wasi"))]
     use tokio::io::{AsyncReadExt, AsyncWriteExt};
+
     use tokio::runtime::Runtime;
     use tokio::sync::oneshot;
     use tokio::{task, time};
-    use tokio_test::{assert_err, assert_ok};
+
+    #[cfg(not(target_os="wasi"))]
+    use tokio_test::assert_err;
+    use tokio_test::assert_ok;
 
     use futures::future::poll_fn;
     use std::future::Future;
     use std::pin::Pin;
-    use std::sync::{mpsc, Arc};
+
+    #[cfg(not(target_os="wasi"))]
+    use std::sync::mpsc;
+
+    use std::sync::Arc;
     use std::task::{Context, Poll};
+
+    #[cfg(not(target_os="wasi"))]
     use std::thread;
     use std::time::{Duration, Instant};
 
@@ -83,6 +104,7 @@ rt_test! {
     }
 
 
+    #[cfg(not(target_os="wasi"))]
     #[test]
     fn block_on_async() {
         let rt = rt();
@@ -164,6 +186,7 @@ rt_test! {
         assert_eq!(out, "ZOMG");
     }
 
+    #[cfg(not(target_os="wasi"))] // Wasi does not support threads
     #[test]
     fn spawn_many_from_block_on() {
         use tokio::sync::mpsc;
@@ -214,6 +237,7 @@ rt_test! {
         }
     }
 
+    #[cfg(not(target_os="wasi"))] // Wasi does not support threads
     #[test]
     fn spawn_many_from_task() {
         use tokio::sync::mpsc;
@@ -226,14 +250,6 @@ rt_test! {
             tokio::spawn(async move {
                 let (done_tx, mut done_rx) = mpsc::unbounded_channel();
 
-                /*
-                for _ in 0..100 {
-                    tokio::spawn(async move { });
-                }
-
-                tokio::task::yield_now().await;
-                */
-
                 let mut txs = (0..ITER)
                     .map(|i| {
                         let (tx, rx) = oneshot::channel();
@@ -275,6 +291,31 @@ rt_test! {
     }
 
     #[test]
+    fn spawn_one_from_block_on_called_on_handle() {
+        let rt = rt();
+        let (tx, rx) = oneshot::channel();
+
+        #[allow(clippy::async_yields_async)]
+        let handle = rt.handle().block_on(async {
+            tokio::spawn(async move {
+                tx.send("ZOMG").unwrap();
+                "DONE"
+            })
+        });
+
+        let out = rt.block_on(async {
+            let msg = assert_ok!(rx.await);
+
+            let out = assert_ok!(handle.await);
+            assert_eq!(out, "DONE");
+
+            msg
+        });
+
+        assert_eq!(out, "ZOMG");
+    }
+
+    #[test]
     fn spawn_await_chain() {
         let rt = rt();
 
@@ -329,6 +370,7 @@ rt_test! {
         assert_eq!(out, "ZOMG");
     }
 
+    #[cfg(not(target_os="wasi"))] // Wasi does not support threads
     #[test]
     fn complete_block_on_under_load() {
         let rt = rt();
@@ -352,6 +394,7 @@ rt_test! {
         });
     }
 
+    #[cfg(not(target_os="wasi"))] // Wasi does not support threads
     #[test]
     fn complete_task_under_load() {
         let rt = rt();
@@ -381,6 +424,7 @@ rt_test! {
         });
     }
 
+    #[cfg(not(target_os="wasi"))] // Wasi does not support threads
     #[test]
     fn spawn_from_other_thread_idle() {
         let rt = rt();
@@ -401,6 +445,7 @@ rt_test! {
         });
     }
 
+    #[cfg(not(target_os="wasi"))] // Wasi does not support threads
     #[test]
     fn spawn_from_other_thread_under_load() {
         let rt = rt();
@@ -461,6 +506,7 @@ rt_test! {
         assert!(now.elapsed() >= dur);
     }
 
+    #[cfg(not(target_os="wasi"))] // Wasi does not support bind
     #[test]
     fn block_on_socket() {
         let rt = rt();
@@ -481,6 +527,7 @@ rt_test! {
         });
     }
 
+    #[cfg(not(target_os="wasi"))] // Wasi does not support threads
     #[test]
     fn spawn_from_blocking() {
         let rt = rt();
@@ -496,6 +543,7 @@ rt_test! {
         assert_eq!(out, "hello")
     }
 
+    #[cfg(not(target_os="wasi"))] // Wasi does not support threads
     #[test]
     fn spawn_blocking_from_blocking() {
         let rt = rt();
@@ -511,6 +559,7 @@ rt_test! {
         assert_eq!(out, "hello")
     }
 
+    #[cfg(not(target_os="wasi"))] // Wasi does not support threads
     #[test]
     fn sleep_from_blocking() {
         let rt = rt();
@@ -531,6 +580,7 @@ rt_test! {
         });
     }
 
+    #[cfg(not(target_os="wasi"))] // Wasi does not support bind
     #[test]
     fn socket_from_blocking() {
         let rt = rt();
@@ -554,6 +604,7 @@ rt_test! {
         });
     }
 
+    #[cfg(not(target_os="wasi"))] // Wasi does not support threads
     #[test]
     fn always_active_parker() {
         // This test it to show that we will always have
@@ -600,6 +651,7 @@ rt_test! {
     // concern. There also isn't a great/obvious solution to take. For now, the
     // test is disabled.
     #[cfg(not(windows))]
+    #[cfg(not(target_os="wasi"))] // Wasi does not support bind or threads
     fn io_driver_called_when_under_load() {
         let rt = rt();
 
@@ -607,7 +659,12 @@ rt_test! {
         for _ in 0..100 {
             rt.spawn(async {
                 loop {
-                    tokio::task::yield_now().await;
+                    // Don't use Tokio's `yield_now()` to avoid special defer
+                    // logic.
+                    futures::future::poll_fn::<(), _>(|cx| {
+                        cx.waker().wake_by_ref();
+                        std::task::Poll::Pending
+                    }).await;
                 }
             });
         }
@@ -635,6 +692,113 @@ rt_test! {
         });
     }
 
+    /// Tests that yielded tasks are not scheduled until **after** resource
+    /// drivers are polled.
+    ///
+    /// The OS does not guarantee when I/O events are delivered, so there may be
+    /// more yields than anticipated. This makes the test slightly flaky. To
+    /// help avoid flakiness, we run the test 10 times and only fail it after
+    /// 10 failures in a row.
+    ///
+    /// Note that if the test fails by panicking rather than by returning false,
+    /// then we fail it immediately. That kind of failure should not happen
+    /// spuriously.
+    #[test]
+    #[cfg(not(target_os="wasi"))]
+    fn yield_defers_until_park() {
+        for _ in 0..10 {
+            if yield_defers_until_park_inner() {
+                // test passed
+                return;
+            }
+
+            // Wait a bit and run the test again.
+            std::thread::sleep(std::time::Duration::from_secs(2));
+        }
+
+        panic!("yield_defers_until_park is failing consistently");
+    }
+
+    /// Implementation of `yield_defers_until_park` test. Returns `true` if the
+    /// test passed.
+    #[cfg(not(target_os="wasi"))]
+    fn yield_defers_until_park_inner() -> bool {
+        use std::sync::atomic::{AtomicBool, Ordering::SeqCst};
+        use std::sync::Barrier;
+
+        let rt = rt();
+
+        let flag = Arc::new(AtomicBool::new(false));
+        let barrier = Arc::new(Barrier::new(NUM_WORKERS));
+
+        rt.block_on(async {
+            // Make sure other workers cannot steal tasks
+            #[allow(clippy::reversed_empty_ranges)]
+            for _ in 0..(NUM_WORKERS-1) {
+                let flag = flag.clone();
+                let barrier = barrier.clone();
+
+                tokio::spawn(async move {
+                    barrier.wait();
+
+                    while !flag.load(SeqCst) {
+                        std::thread::sleep(std::time::Duration::from_millis(1));
+                    }
+                });
+            }
+
+            barrier.wait();
+
+            let (fail_test, fail_test_recv) = oneshot::channel::<()>();
+
+            let jh = tokio::spawn(async move {
+                // Create a TCP litener
+                let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+                let addr = listener.local_addr().unwrap();
+
+                tokio::join!(
+                    async {
+                        // Done in a blocking manner intentionally.
+                        let _socket = std::net::TcpStream::connect(addr).unwrap();
+
+                        // Yield until connected
+                        let mut cnt = 0;
+                        while !flag.load(SeqCst){
+                            tokio::task::yield_now().await;
+                            cnt += 1;
+
+                            if cnt >= 10 {
+                                // yielded too many times; report failure and
+                                // sleep forever so that the `fail_test` branch
+                                // of the `select!` below triggers.
+                                let _ = fail_test.send(());
+                                futures::future::pending::<()>().await;
+                                break;
+                            }
+                        }
+                    },
+                    async {
+                        let _ = listener.accept().await.unwrap();
+                        flag.store(true, SeqCst);
+                    }
+                );
+            });
+
+            // Wait until the spawned task completes or fails. If no message is
+            // sent on `fail_test`, then the test succeeds. Otherwise, it fails.
+            let success = fail_test_recv.await.is_err();
+
+            if success {
+                // Check for panics in spawned task.
+                jh.abort();
+                jh.await.unwrap();
+            }
+
+            success
+        })
+    }
+
+    #[cfg(not(target_os="wasi"))] // Wasi does not support threads
     #[test]
     fn client_server_block_on() {
         let rt = rt();
@@ -646,6 +810,7 @@ rt_test! {
         assert_err!(rx.try_recv());
     }
 
+    #[cfg_attr(tokio_wasi, ignore = "Wasi does not support threads or panic recovery")]
     #[test]
     fn panic_in_task() {
         let rt = rt();
@@ -674,11 +839,13 @@ rt_test! {
 
     #[test]
     #[should_panic]
+    #[cfg_attr(tokio_wasi, ignore = "Wasi does not support panic recovery")]
     fn panic_in_block_on() {
         let rt = rt();
         rt.block_on(async { panic!() });
     }
 
+    #[cfg(not(target_os="wasi"))] // Wasi does not support threads
     async fn yield_once() {
         let mut yielded = false;
         poll_fn(|cx| {
@@ -748,7 +915,11 @@ rt_test! {
 
     #[test]
     fn wake_while_rt_is_dropping() {
-        use tokio::task;
+        use tokio::sync::Barrier;
+        use core::sync::atomic::{AtomicBool, Ordering};
+
+        let drop_triggered = Arc::new(AtomicBool::new(false));
+        let set_drop_triggered = drop_triggered.clone();
 
         struct OnDrop<F: FnMut()>(F);
 
@@ -762,17 +933,21 @@ rt_test! {
         let (tx2, rx2) = oneshot::channel();
         let (tx3, rx3) = oneshot::channel();
 
-        let rt = rt();
+        let barrier = Arc::new(Barrier::new(4));
+        let barrier1 = barrier.clone();
+        let barrier2 = barrier.clone();
+        let barrier3 = barrier.clone();
 
-        let h1 = rt.clone();
+        let rt = rt();
 
         rt.spawn(async move {
             // Ensure a waker gets stored in oneshot 1.
-            let _ = rx1.await;
+            let _ = tokio::join!(rx1, barrier1.wait());
             tx3.send(()).unwrap();
         });
 
         rt.spawn(async move {
+            let h1 = tokio::runtime::Handle::current();
             // When this task is dropped, we'll be "closing remotes".
             // We spawn a new task that owns the `tx1`, to move its Drop
             // out of here.
@@ -785,36 +960,40 @@ rt_test! {
                 h1.spawn(async move {
                     tx1.send(()).unwrap();
                 });
+                // Just a sanity check that this entire thing actually happened
+                set_drop_triggered.store(true, Ordering::Relaxed);
             });
-            let _ = rx2.await;
+            let _ = tokio::join!(rx2, barrier2.wait());
         });
 
         rt.spawn(async move {
-            let _ = rx3.await;
+            let _ = tokio::join!(rx3, barrier3.wait());
             // We'll never get here, but once task 3 drops, this will
             // force task 2 to re-schedule since it's waiting on oneshot 2.
             tx2.send(()).unwrap();
         });
 
-        // Tick the loop
-        rt.block_on(async {
-            task::yield_now().await;
-        });
+        // Wait until every oneshot channel has been polled.
+        rt.block_on(barrier.wait());
 
         // Drop the rt
         drop(rt);
+
+        // Make sure that the spawn actually happened
+        assert!(drop_triggered.load(Ordering::Relaxed));
     }
 
+    #[cfg(not(target_os="wasi"))] // Wasi doesn't support UDP or bind()
     #[test]
     fn io_notify_while_shutting_down() {
-        use std::net::Ipv6Addr;
+        use tokio::net::UdpSocket;
         use std::sync::Arc;
 
         for _ in 1..10 {
             let runtime = rt();
 
             runtime.block_on(async {
-                let socket = UdpSocket::bind((Ipv6Addr::LOCALHOST, 0)).await.unwrap();
+                let socket = UdpSocket::bind("127.0.0.1:0").await.unwrap();
                 let addr = socket.local_addr().unwrap();
                 let send_half = Arc::new(socket);
                 let recv_half = send_half.clone();
@@ -840,6 +1019,7 @@ rt_test! {
         }
     }
 
+    #[cfg(not(target_os="wasi"))] // Wasi does not support threads
     #[test]
     fn shutdown_timeout() {
         let (tx, rx) = oneshot::channel();
@@ -857,6 +1037,7 @@ rt_test! {
         Arc::try_unwrap(runtime).unwrap().shutdown_timeout(Duration::from_millis(100));
     }
 
+    #[cfg(not(target_os="wasi"))] // Wasi does not support threads
     #[test]
     fn shutdown_timeout_0() {
         let runtime = rt();
@@ -888,6 +1069,7 @@ rt_test! {
     // See https://github.com/rust-lang/rust/issues/74875
     #[test]
     #[cfg(not(windows))]
+    #[cfg_attr(tokio_wasi, ignore = "Wasi does not support threads")]
     fn runtime_in_thread_local() {
         use std::cell::RefCell;
         use std::thread;
@@ -907,6 +1089,7 @@ rt_test! {
         }).join().unwrap();
     }
 
+    #[cfg(not(target_os="wasi"))] // Wasi does not support bind
     async fn client_server(tx: mpsc::Sender<()>) {
         let server = assert_ok!(TcpListener::bind("127.0.0.1:0").await);
 
@@ -931,6 +1114,7 @@ rt_test! {
         tx.send(()).unwrap();
     }
 
+    #[cfg(not(tokio_wasi))] // Wasi does not support bind
     #[test]
     fn local_set_block_on_socket() {
         let rt = rt();
@@ -952,6 +1136,7 @@ rt_test! {
         });
     }
 
+    #[cfg(not(tokio_wasi))] // Wasi does not support bind
     #[test]
     fn local_set_client_server_block_on() {
         let rt = rt();
@@ -965,6 +1150,7 @@ rt_test! {
         assert_err!(rx.try_recv());
     }
 
+    #[cfg(not(tokio_wasi))] // Wasi does not support bind
     async fn client_server_local(tx: mpsc::Sender<()>) {
         let server = assert_ok!(TcpListener::bind("127.0.0.1:0").await);
 
@@ -992,22 +1178,22 @@ rt_test! {
     #[test]
     fn coop() {
         use std::task::Poll::Ready;
+        use tokio::sync::mpsc;
 
         let rt = rt();
 
         rt.block_on(async {
-            // Create a bunch of tasks
-            let mut tasks = (0..1_000).map(|_| {
-                tokio::spawn(async { })
-            }).collect::<Vec<_>>();
+            let (send, mut recv) = mpsc::unbounded_channel();
 
-            // Hope that all the tasks complete...
-            time::sleep(Duration::from_millis(100)).await;
+            // Send a bunch of messages.
+            for _ in 0..1_000 {
+                send.send(()).unwrap();
+            }
 
             poll_fn(|cx| {
-                // At least one task should not be ready
-                for task in &mut tasks {
-                    if Pin::new(task).poll(cx).is_pending() {
+                // At least one response should return pending.
+                for _ in 0..1_000 {
+                    if recv.poll_recv(cx).is_pending() {
                         return Ready(());
                     }
                 }
@@ -1020,22 +1206,22 @@ rt_test! {
     #[test]
     fn coop_unconstrained() {
         use std::task::Poll::Ready;
+        use tokio::sync::mpsc;
 
         let rt = rt();
 
         rt.block_on(async {
-            // Create a bunch of tasks
-            let mut tasks = (0..1_000).map(|_| {
-                tokio::spawn(async { })
-            }).collect::<Vec<_>>();
+            let (send, mut recv) = mpsc::unbounded_channel();
 
-            // Hope that all the tasks complete...
-            time::sleep(Duration::from_millis(100)).await;
+            // Send a bunch of messages.
+            for _ in 0..1_000 {
+                send.send(()).unwrap();
+            }
 
             tokio::task::unconstrained(poll_fn(|cx| {
-                // All the tasks should be ready
-                for task in &mut tasks {
-                    assert!(Pin::new(task).poll(cx).is_ready());
+                // All the responses should be ready.
+                for _ in 0..1_000 {
+                    assert_eq!(recv.poll_recv(cx), Poll::Ready(Some(())));
                 }
 
                 Ready(())
@@ -1043,6 +1229,31 @@ rt_test! {
         });
     }
 
+    #[cfg(tokio_unstable)]
+    #[test]
+    fn coop_consume_budget() {
+        let rt = rt();
+
+        rt.block_on(async {
+            poll_fn(|cx| {
+                let counter = Arc::new(std::sync::Mutex::new(0));
+                let counter_clone = Arc::clone(&counter);
+                let mut worker = Box::pin(async move {
+                    // Consume the budget until a yield happens
+                    for _ in 0..1000 {
+                        *counter.lock().unwrap() += 1;
+                        task::consume_budget().await
+                    }
+                });
+                // Assert that the worker was yielded and it didn't manage
+                // to finish the whole work (assuming the total budget of 128)
+                assert!(Pin::new(&mut worker).poll(cx).is_pending());
+                assert!(*counter_clone.lock().unwrap() < 1000);
+                std::task::Poll::Ready(())
+            }).await;
+        });
+    }
+
     // Tests that the "next task" scheduler optimization is not able to starve
     // other tasks.
     #[test]
@@ -1060,7 +1271,7 @@ rt_test! {
             let (spawned_tx, mut spawned_rx) = mpsc::unbounded_channel();
 
             let mut tasks = vec![];
-            // Spawn a bunch of tasks that ping ping between each other to
+            // Spawn a bunch of tasks that ping-pong between each other to
             // saturate the runtime.
             for _ in 0..NUM {
                 let (tx1, mut rx1) = mpsc::unbounded_channel();
@@ -1106,4 +1317,39 @@ rt_test! {
             }
         });
     }
+
+    #[test]
+    #[cfg(not(target_os="wasi"))]
+    fn shutdown_concurrent_spawn() {
+        const NUM_TASKS: usize = 10_000;
+        for _ in 0..5 {
+            let (tx, rx) = std::sync::mpsc::channel();
+            let rt = rt();
+
+            let mut txs = vec![];
+
+            for _ in 0..NUM_TASKS {
+                let (tx, rx) = tokio::sync::oneshot::channel();
+                txs.push(tx);
+                rt.spawn(async move {
+                    rx.await.unwrap();
+                });
+            }
+
+            // Prime the tasks
+            rt.block_on(async { tokio::task::yield_now().await });
+
+            let th = std::thread::spawn(move || {
+                tx.send(()).unwrap();
+                for tx in txs.drain(..) {
+                    let _ = tx.send(());
+                }
+            });
+
+            rx.recv().unwrap();
+            drop(rt);
+
+            th.join().unwrap();
+        }
+    }
 }
diff --git a/vendor/tokio/tests/rt_handle.rs b/vendor/tokio/tests/rt_handle.rs
new file mode 100644
index 000000000..34c99cdae
--- /dev/null
+++ b/vendor/tokio/tests/rt_handle.rs
@@ -0,0 +1,67 @@
+#![warn(rust_2018_idioms)]
+#![cfg(feature = "full")]
+
+use tokio::runtime::Runtime;
+
+#[test]
+fn basic_enter() {
+    let rt1 = rt();
+    let rt2 = rt();
+
+    let enter1 = rt1.enter();
+    let enter2 = rt2.enter();
+
+    drop(enter2);
+    drop(enter1);
+}
+
+#[test]
+#[should_panic]
+fn interleave_enter_different_rt() {
+    let rt1 = rt();
+    let rt2 = rt();
+
+    let enter1 = rt1.enter();
+    let enter2 = rt2.enter();
+
+    drop(enter1);
+    drop(enter2);
+}
+
+#[test]
+#[should_panic]
+fn interleave_enter_same_rt() {
+    let rt1 = rt();
+
+    let _enter1 = rt1.enter();
+    let enter2 = rt1.enter();
+    let enter3 = rt1.enter();
+
+    drop(enter2);
+    drop(enter3);
+}
+
+#[test]
+#[cfg(not(tokio_wasi))]
+fn interleave_then_enter() {
+    let _ = std::panic::catch_unwind(|| {
+        let rt1 = rt();
+        let rt2 = rt();
+
+        let enter1 = rt1.enter();
+        let enter2 = rt2.enter();
+
+        drop(enter1);
+        drop(enter2);
+    });
+
+    // Can still enter
+    let rt3 = rt();
+    let _enter = rt3.enter();
+}
+
+fn rt() -> Runtime {
+    tokio::runtime::Builder::new_current_thread()
+        .build()
+        .unwrap()
+}
diff --git a/vendor/tokio/tests/rt_handle_block_on.rs b/vendor/tokio/tests/rt_handle_block_on.rs
index 17878c8d2..5ec783e55 100644
--- a/vendor/tokio/tests/rt_handle_block_on.rs
+++ b/vendor/tokio/tests/rt_handle_block_on.rs
@@ -10,9 +10,10 @@
 use std::time::Duration;
 use tokio::runtime::{Handle, Runtime};
 use tokio::sync::mpsc;
-use tokio::task::spawn_blocking;
-use tokio::{fs, net, time};
+#[cfg(not(tokio_wasi))]
+use tokio::{net, time};
 
+#[cfg(not(tokio_wasi))] // Wasi doesn't support threads
 macro_rules! multi_threaded_rt_test {
     ($($t:tt)*) => {
         mod threaded_scheduler_4_threads_only {
@@ -45,6 +46,7 @@ macro_rules! multi_threaded_rt_test {
     }
 }
 
+#[cfg(not(tokio_wasi))]
 macro_rules! rt_test {
     ($($t:tt)*) => {
         mod current_thread_scheduler {
@@ -124,7 +126,9 @@ fn unbounded_mpsc_channel() {
     })
 }
 
+#[cfg(not(tokio_wasi))] // Wasi doesn't support file operations or bind
 rt_test! {
+    use tokio::fs;
     // ==== spawn blocking futures ======
 
     #[test]
@@ -135,7 +139,7 @@ rt_test! {
         let contents = Handle::current()
             .block_on(fs::read_to_string("Cargo.toml"))
             .unwrap();
-        assert!(contents.contains("Cargo.toml"));
+        assert!(contents.contains("https://tokio.rs"));
     }
 
     #[test]
@@ -156,6 +160,7 @@ rt_test! {
 
     #[test]
     fn basic_spawn_blocking() {
+        use tokio::task::spawn_blocking;
         let rt = rt();
         let _enter = rt.enter();
 
@@ -171,6 +176,7 @@ rt_test! {
 
     #[test]
     fn spawn_blocking_after_shutdown_fails() {
+        use tokio::task::spawn_blocking;
         let rt = rt();
         let _enter = rt.enter();
         rt.shutdown_timeout(Duration::from_secs(1000));
@@ -187,6 +193,7 @@ rt_test! {
 
     #[test]
     fn spawn_blocking_started_before_shutdown_continues() {
+        use tokio::task::spawn_blocking;
         let rt = rt();
         let _enter = rt.enter();
 
@@ -412,6 +419,7 @@ rt_test! {
     }
 }
 
+#[cfg(not(tokio_wasi))]
 multi_threaded_rt_test! {
     #[cfg(unix)]
     #[test]
@@ -474,6 +482,7 @@ multi_threaded_rt_test! {
 // ==== utils ======
 
 /// Create a new multi threaded runtime
+#[cfg(not(tokio_wasi))]
 fn new_multi_thread(n: usize) -> Runtime {
     tokio::runtime::Builder::new_multi_thread()
         .worker_threads(n)
@@ -496,37 +505,30 @@ where
     F: Fn(),
 {
     {
-        println!("current thread runtime");
-
         let rt = new_current_thread();
         let _enter = rt.enter();
         f();
 
-        println!("current thread runtime after shutdown");
         rt.shutdown_timeout(Duration::from_secs(1000));
         f();
     }
 
+    #[cfg(not(tokio_wasi))]
     {
-        println!("multi thread (1 thread) runtime");
-
         let rt = new_multi_thread(1);
         let _enter = rt.enter();
         f();
 
-        println!("multi thread runtime after shutdown");
         rt.shutdown_timeout(Duration::from_secs(1000));
         f();
     }
 
+    #[cfg(not(tokio_wasi))]
     {
-        println!("multi thread (4 threads) runtime");
-
         let rt = new_multi_thread(4);
         let _enter = rt.enter();
         f();
 
-        println!("multi thread runtime after shutdown");
         rt.shutdown_timeout(Duration::from_secs(1000));
         f();
     }
diff --git a/vendor/tokio/tests/rt_metrics.rs b/vendor/tokio/tests/rt_metrics.rs
new file mode 100644
index 000000000..0fe839a2f
--- /dev/null
+++ b/vendor/tokio/tests/rt_metrics.rs
@@ -0,0 +1,718 @@
+#![warn(rust_2018_idioms)]
+#![cfg(all(feature = "full", tokio_unstable, not(tokio_wasi)))]
+
+use std::future::Future;
+use std::sync::{Arc, Mutex};
+use std::task::Poll;
+use tokio::macros::support::poll_fn;
+
+use tokio::runtime::Runtime;
+use tokio::task::consume_budget;
+use tokio::time::{self, Duration};
+
+#[test]
+fn num_workers() {
+    let rt = current_thread();
+    assert_eq!(1, rt.metrics().num_workers());
+
+    let rt = threaded();
+    assert_eq!(2, rt.metrics().num_workers());
+}
+
+#[test]
+fn num_blocking_threads() {
+    let rt = current_thread();
+    assert_eq!(0, rt.metrics().num_blocking_threads());
+    let _ = rt.block_on(rt.spawn_blocking(move || {}));
+    assert_eq!(1, rt.metrics().num_blocking_threads());
+}
+
+#[test]
+fn num_idle_blocking_threads() {
+    let rt = current_thread();
+    assert_eq!(0, rt.metrics().num_idle_blocking_threads());
+    let _ = rt.block_on(rt.spawn_blocking(move || {}));
+    rt.block_on(async {
+        time::sleep(Duration::from_millis(5)).await;
+    });
+
+    // We need to wait until the blocking thread has become idle. Usually 5ms is
+    // enough for this to happen, but not always. When it isn't enough, sleep
+    // for another second. We don't always wait for a whole second since we want
+    // the test suite to finish quickly.
+    //
+    // Note that the timeout for idle threads to be killed is 10 seconds.
+    if 0 == rt.metrics().num_idle_blocking_threads() {
+        rt.block_on(async {
+            time::sleep(Duration::from_secs(1)).await;
+        });
+    }
+
+    assert_eq!(1, rt.metrics().num_idle_blocking_threads());
+}
+
+#[test]
+fn blocking_queue_depth() {
+    let rt = tokio::runtime::Builder::new_current_thread()
+        .enable_all()
+        .max_blocking_threads(1)
+        .build()
+        .unwrap();
+
+    assert_eq!(0, rt.metrics().blocking_queue_depth());
+
+    let ready = Arc::new(Mutex::new(()));
+    let guard = ready.lock().unwrap();
+
+    let ready_cloned = ready.clone();
+    let wait_until_ready = move || {
+        let _unused = ready_cloned.lock().unwrap();
+    };
+
+    let h1 = rt.spawn_blocking(wait_until_ready.clone());
+    let h2 = rt.spawn_blocking(wait_until_ready);
+    assert!(rt.metrics().blocking_queue_depth() > 0);
+
+    drop(guard);
+
+    let _ = rt.block_on(h1);
+    let _ = rt.block_on(h2);
+
+    assert_eq!(0, rt.metrics().blocking_queue_depth());
+}
+
+#[test]
+fn active_tasks_count() {
+    let rt = current_thread();
+    let metrics = rt.metrics();
+    assert_eq!(0, metrics.active_tasks_count());
+    rt.spawn(async move {
+        assert_eq!(1, metrics.active_tasks_count());
+    });
+
+    let rt = threaded();
+    let metrics = rt.metrics();
+    assert_eq!(0, metrics.active_tasks_count());
+    rt.spawn(async move {
+        assert_eq!(1, metrics.active_tasks_count());
+    });
+}
+
+#[test]
+fn remote_schedule_count() {
+    use std::thread;
+
+    let rt = current_thread();
+    let handle = rt.handle().clone();
+    let task = thread::spawn(move || {
+        handle.spawn(async {
+            // DO nothing
+        })
+    })
+    .join()
+    .unwrap();
+
+    rt.block_on(task).unwrap();
+
+    assert_eq!(1, rt.metrics().remote_schedule_count());
+
+    let rt = threaded();
+    let handle = rt.handle().clone();
+    let task = thread::spawn(move || {
+        handle.spawn(async {
+            // DO nothing
+        })
+    })
+    .join()
+    .unwrap();
+
+    rt.block_on(task).unwrap();
+
+    assert_eq!(1, rt.metrics().remote_schedule_count());
+}
+
+#[test]
+fn worker_park_count() {
+    let rt = current_thread();
+    let metrics = rt.metrics();
+    rt.block_on(async {
+        time::sleep(Duration::from_millis(1)).await;
+    });
+    drop(rt);
+    assert!(1 <= metrics.worker_park_count(0));
+
+    let rt = threaded();
+    let metrics = rt.metrics();
+    rt.block_on(async {
+        time::sleep(Duration::from_millis(1)).await;
+    });
+    drop(rt);
+    assert!(1 <= metrics.worker_park_count(0));
+    assert!(1 <= metrics.worker_park_count(1));
+}
+
+#[test]
+fn worker_noop_count() {
+    // There isn't really a great way to generate no-op parks as they happen as
+    // false-positive events under concurrency.
+
+    let rt = current_thread();
+    let metrics = rt.metrics();
+    rt.block_on(async {
+        time::sleep(Duration::from_millis(1)).await;
+    });
+    drop(rt);
+    assert!(0 < metrics.worker_noop_count(0));
+
+    let rt = threaded();
+    let metrics = rt.metrics();
+    rt.block_on(async {
+        time::sleep(Duration::from_millis(1)).await;
+    });
+    drop(rt);
+    assert!(0 < metrics.worker_noop_count(0));
+    assert!(0 < metrics.worker_noop_count(1));
+}
+
+#[test]
+fn worker_steal_count() {
+    // This metric only applies to the multi-threaded runtime.
+    //
+    // We use a blocking channel to backup one worker thread.
+    use std::sync::mpsc::channel;
+
+    let rt = threaded();
+    let metrics = rt.metrics();
+
+    rt.block_on(async {
+        let (tx, rx) = channel();
+
+        // Move to the runtime.
+        tokio::spawn(async move {
+            // Spawn the task that sends to the channel
+            tokio::spawn(async move {
+                tx.send(()).unwrap();
+            });
+
+            // Spawn a task that bumps the previous task out of the "next
+            // scheduled" slot.
+            tokio::spawn(async {});
+
+            // Blocking receive on the channel.
+            rx.recv().unwrap();
+        })
+        .await
+        .unwrap();
+    });
+
+    drop(rt);
+
+    let n: u64 = (0..metrics.num_workers())
+        .map(|i| metrics.worker_steal_count(i))
+        .sum();
+
+    assert_eq!(1, n);
+}
+
+#[test]
+fn worker_poll_count() {
+    const N: u64 = 5;
+
+    let rt = current_thread();
+    let metrics = rt.metrics();
+    rt.block_on(async {
+        for _ in 0..N {
+            tokio::spawn(async {}).await.unwrap();
+        }
+    });
+    drop(rt);
+    assert_eq!(N, metrics.worker_poll_count(0));
+
+    // Does not populate the histogram
+    assert!(!metrics.poll_count_histogram_enabled());
+    for i in 0..10 {
+        assert_eq!(0, metrics.poll_count_histogram_bucket_count(0, i));
+    }
+
+    let rt = threaded();
+    let metrics = rt.metrics();
+    rt.block_on(async {
+        for _ in 0..N {
+            tokio::spawn(async {}).await.unwrap();
+        }
+    });
+    drop(rt);
+    // Account for the `block_on` task
+    let n = (0..metrics.num_workers())
+        .map(|i| metrics.worker_poll_count(i))
+        .sum();
+
+    assert_eq!(N, n);
+
+    // Does not populate the histogram
+    assert!(!metrics.poll_count_histogram_enabled());
+    for n in 0..metrics.num_workers() {
+        for i in 0..10 {
+            assert_eq!(0, metrics.poll_count_histogram_bucket_count(n, i));
+        }
+    }
+}
+
+#[test]
+fn worker_poll_count_histogram() {
+    const N: u64 = 5;
+
+    let rts = [
+        tokio::runtime::Builder::new_current_thread()
+            .enable_all()
+            .enable_metrics_poll_count_histogram()
+            .metrics_poll_count_histogram_scale(tokio::runtime::HistogramScale::Linear)
+            .metrics_poll_count_histogram_buckets(3)
+            .metrics_poll_count_histogram_resolution(Duration::from_millis(50))
+            .build()
+            .unwrap(),
+        tokio::runtime::Builder::new_multi_thread()
+            .worker_threads(2)
+            .enable_all()
+            .enable_metrics_poll_count_histogram()
+            .metrics_poll_count_histogram_scale(tokio::runtime::HistogramScale::Linear)
+            .metrics_poll_count_histogram_buckets(3)
+            .metrics_poll_count_histogram_resolution(Duration::from_millis(50))
+            .build()
+            .unwrap(),
+    ];
+
+    for rt in rts {
+        let metrics = rt.metrics();
+        rt.block_on(async {
+            for _ in 0..N {
+                tokio::spawn(async {}).await.unwrap();
+            }
+        });
+        drop(rt);
+
+        let num_workers = metrics.num_workers();
+        let num_buckets = metrics.poll_count_histogram_num_buckets();
+
+        assert!(metrics.poll_count_histogram_enabled());
+        assert_eq!(num_buckets, 3);
+
+        let n = (0..num_workers)
+            .flat_map(|i| (0..num_buckets).map(move |j| (i, j)))
+            .map(|(worker, bucket)| metrics.poll_count_histogram_bucket_count(worker, bucket))
+            .sum();
+        assert_eq!(N, n);
+    }
+}
+
+#[test]
+fn worker_poll_count_histogram_range() {
+    let max = Duration::from_nanos(u64::MAX);
+
+    let rt = tokio::runtime::Builder::new_current_thread()
+        .enable_all()
+        .enable_metrics_poll_count_histogram()
+        .metrics_poll_count_histogram_scale(tokio::runtime::HistogramScale::Linear)
+        .metrics_poll_count_histogram_buckets(3)
+        .metrics_poll_count_histogram_resolution(us(50))
+        .build()
+        .unwrap();
+    let metrics = rt.metrics();
+
+    assert_eq!(metrics.poll_count_histogram_bucket_range(0), us(0)..us(50));
+    assert_eq!(
+        metrics.poll_count_histogram_bucket_range(1),
+        us(50)..us(100)
+    );
+    assert_eq!(metrics.poll_count_histogram_bucket_range(2), us(100)..max);
+
+    let rt = tokio::runtime::Builder::new_current_thread()
+        .enable_all()
+        .enable_metrics_poll_count_histogram()
+        .metrics_poll_count_histogram_scale(tokio::runtime::HistogramScale::Log)
+        .metrics_poll_count_histogram_buckets(3)
+        .metrics_poll_count_histogram_resolution(us(50))
+        .build()
+        .unwrap();
+    let metrics = rt.metrics();
+
+    let a = Duration::from_nanos(50000_u64.next_power_of_two());
+    let b = a * 2;
+
+    assert_eq!(metrics.poll_count_histogram_bucket_range(0), us(0)..a);
+    assert_eq!(metrics.poll_count_histogram_bucket_range(1), a..b);
+    assert_eq!(metrics.poll_count_histogram_bucket_range(2), b..max);
+}
+
+#[test]
+fn worker_poll_count_histogram_disabled_without_explicit_enable() {
+    let rts = [
+        tokio::runtime::Builder::new_current_thread()
+            .enable_all()
+            .metrics_poll_count_histogram_scale(tokio::runtime::HistogramScale::Linear)
+            .metrics_poll_count_histogram_buckets(3)
+            .metrics_poll_count_histogram_resolution(Duration::from_millis(50))
+            .build()
+            .unwrap(),
+        tokio::runtime::Builder::new_multi_thread()
+            .worker_threads(2)
+            .enable_all()
+            .metrics_poll_count_histogram_scale(tokio::runtime::HistogramScale::Linear)
+            .metrics_poll_count_histogram_buckets(3)
+            .metrics_poll_count_histogram_resolution(Duration::from_millis(50))
+            .build()
+            .unwrap(),
+    ];
+
+    for rt in rts {
+        let metrics = rt.metrics();
+        assert!(!metrics.poll_count_histogram_enabled());
+    }
+}
+
+#[test]
+fn worker_total_busy_duration() {
+    const N: usize = 5;
+
+    let zero = Duration::from_millis(0);
+
+    let rt = current_thread();
+    let metrics = rt.metrics();
+
+    rt.block_on(async {
+        for _ in 0..N {
+            tokio::spawn(async {
+                tokio::task::yield_now().await;
+            })
+            .await
+            .unwrap();
+        }
+    });
+
+    drop(rt);
+
+    assert!(zero < metrics.worker_total_busy_duration(0));
+
+    let rt = threaded();
+    let metrics = rt.metrics();
+
+    rt.block_on(async {
+        for _ in 0..N {
+            tokio::spawn(async {
+                tokio::task::yield_now().await;
+            })
+            .await
+            .unwrap();
+        }
+    });
+
+    drop(rt);
+
+    for i in 0..metrics.num_workers() {
+        assert!(zero < metrics.worker_total_busy_duration(i));
+    }
+}
+
+#[test]
+fn worker_local_schedule_count() {
+    let rt = current_thread();
+    let metrics = rt.metrics();
+    rt.block_on(async {
+        tokio::spawn(async {}).await.unwrap();
+    });
+    drop(rt);
+
+    assert_eq!(1, metrics.worker_local_schedule_count(0));
+    assert_eq!(0, metrics.remote_schedule_count());
+
+    let rt = threaded();
+    let metrics = rt.metrics();
+    rt.block_on(async {
+        // Move to the runtime
+        tokio::spawn(async {
+            tokio::spawn(async {}).await.unwrap();
+        })
+        .await
+        .unwrap();
+    });
+    drop(rt);
+
+    let n: u64 = (0..metrics.num_workers())
+        .map(|i| metrics.worker_local_schedule_count(i))
+        .sum();
+
+    assert_eq!(2, n);
+    assert_eq!(1, metrics.remote_schedule_count());
+}
+
+#[test]
+fn worker_overflow_count() {
+    // Only applies to the threaded worker
+    let rt = threaded();
+    let metrics = rt.metrics();
+    rt.block_on(async {
+        // Move to the runtime
+        tokio::spawn(async {
+            let (tx1, rx1) = std::sync::mpsc::channel();
+            let (tx2, rx2) = std::sync::mpsc::channel();
+
+            // First, we need to block the other worker until all tasks have
+            // been spawned.
+            tokio::spawn(async move {
+                tx1.send(()).unwrap();
+                rx2.recv().unwrap();
+            });
+
+            // Bump the next-run spawn
+            tokio::spawn(async {});
+
+            rx1.recv().unwrap();
+
+            // Spawn many tasks
+            for _ in 0..300 {
+                tokio::spawn(async {});
+            }
+
+            tx2.send(()).unwrap();
+        })
+        .await
+        .unwrap();
+    });
+    drop(rt);
+
+    let n: u64 = (0..metrics.num_workers())
+        .map(|i| metrics.worker_overflow_count(i))
+        .sum();
+
+    assert_eq!(1, n);
+}
+
+#[test]
+fn injection_queue_depth() {
+    use std::thread;
+
+    let rt = current_thread();
+    let handle = rt.handle().clone();
+    let metrics = rt.metrics();
+
+    thread::spawn(move || {
+        handle.spawn(async {});
+    })
+    .join()
+    .unwrap();
+
+    assert_eq!(1, metrics.injection_queue_depth());
+
+    let rt = threaded();
+    let handle = rt.handle().clone();
+    let metrics = rt.metrics();
+
+    // First we need to block the runtime workers
+    let (tx1, rx1) = std::sync::mpsc::channel();
+    let (tx2, rx2) = std::sync::mpsc::channel();
+    let (tx3, rx3) = std::sync::mpsc::channel();
+    let rx3 = Arc::new(Mutex::new(rx3));
+
+    rt.spawn(async move { rx1.recv().unwrap() });
+    rt.spawn(async move { rx2.recv().unwrap() });
+
+    // Spawn some more to make sure there are items
+    for _ in 0..10 {
+        let rx = rx3.clone();
+        rt.spawn(async move {
+            rx.lock().unwrap().recv().unwrap();
+        });
+    }
+
+    thread::spawn(move || {
+        handle.spawn(async {});
+    })
+    .join()
+    .unwrap();
+
+    let n = metrics.injection_queue_depth();
+    assert!(1 <= n, "{}", n);
+    assert!(15 >= n, "{}", n);
+
+    for _ in 0..10 {
+        tx3.send(()).unwrap();
+    }
+
+    tx1.send(()).unwrap();
+    tx2.send(()).unwrap();
+}
+
+#[test]
+fn worker_local_queue_depth() {
+    const N: usize = 100;
+
+    let rt = current_thread();
+    let metrics = rt.metrics();
+    rt.block_on(async {
+        for _ in 0..N {
+            tokio::spawn(async {});
+        }
+
+        assert_eq!(N, metrics.worker_local_queue_depth(0));
+    });
+
+    let rt = threaded();
+    let metrics = rt.metrics();
+    rt.block_on(async move {
+        // Move to the runtime
+        tokio::spawn(async move {
+            let (tx1, rx1) = std::sync::mpsc::channel();
+            let (tx2, rx2) = std::sync::mpsc::channel();
+
+            // First, we need to block the other worker until all tasks have
+            // been spawned.
+            tokio::spawn(async move {
+                tx1.send(()).unwrap();
+                rx2.recv().unwrap();
+            });
+
+            // Bump the next-run spawn
+            tokio::spawn(async {});
+
+            rx1.recv().unwrap();
+
+            // Spawn some tasks
+            for _ in 0..100 {
+                tokio::spawn(async {});
+            }
+
+            let n: usize = (0..metrics.num_workers())
+                .map(|i| metrics.worker_local_queue_depth(i))
+                .sum();
+
+            assert_eq!(n, N);
+
+            tx2.send(()).unwrap();
+        })
+        .await
+        .unwrap();
+    });
+}
+
+#[test]
+fn budget_exhaustion_yield() {
+    let rt = current_thread();
+    let metrics = rt.metrics();
+
+    assert_eq!(0, metrics.budget_forced_yield_count());
+
+    let mut did_yield = false;
+
+    // block on a task which consumes budget until it yields
+    rt.block_on(poll_fn(|cx| loop {
+        if did_yield {
+            return Poll::Ready(());
+        }
+
+        let fut = consume_budget();
+        tokio::pin!(fut);
+
+        if fut.poll(cx).is_pending() {
+            did_yield = true;
+            return Poll::Pending;
+        }
+    }));
+
+    assert_eq!(1, rt.metrics().budget_forced_yield_count());
+}
+
+#[test]
+fn budget_exhaustion_yield_with_joins() {
+    let rt = current_thread();
+    let metrics = rt.metrics();
+
+    assert_eq!(0, metrics.budget_forced_yield_count());
+
+    let mut did_yield_1 = false;
+    let mut did_yield_2 = false;
+
+    // block on a task which consumes budget until it yields
+    rt.block_on(async {
+        tokio::join!(
+            poll_fn(|cx| loop {
+                if did_yield_1 {
+                    return Poll::Ready(());
+                }
+
+                let fut = consume_budget();
+                tokio::pin!(fut);
+
+                if fut.poll(cx).is_pending() {
+                    did_yield_1 = true;
+                    return Poll::Pending;
+                }
+            }),
+            poll_fn(|cx| loop {
+                if did_yield_2 {
+                    return Poll::Ready(());
+                }
+
+                let fut = consume_budget();
+                tokio::pin!(fut);
+
+                if fut.poll(cx).is_pending() {
+                    did_yield_2 = true;
+                    return Poll::Pending;
+                }
+            })
+        )
+    });
+
+    assert_eq!(1, rt.metrics().budget_forced_yield_count());
+}
+
+#[cfg(any(target_os = "linux", target_os = "macos"))]
+#[test]
+fn io_driver_fd_count() {
+    let rt = current_thread();
+    let metrics = rt.metrics();
+
+    assert_eq!(metrics.io_driver_fd_registered_count(), 0);
+
+    let stream = tokio::net::TcpStream::connect("google.com:80");
+    let stream = rt.block_on(async move { stream.await.unwrap() });
+
+    assert_eq!(metrics.io_driver_fd_registered_count(), 1);
+    assert_eq!(metrics.io_driver_fd_deregistered_count(), 0);
+
+    drop(stream);
+
+    assert_eq!(metrics.io_driver_fd_deregistered_count(), 1);
+    assert_eq!(metrics.io_driver_fd_registered_count(), 1);
+}
+
+#[cfg(any(target_os = "linux", target_os = "macos"))]
+#[test]
+fn io_driver_ready_count() {
+    let rt = current_thread();
+    let metrics = rt.metrics();
+
+    let stream = tokio::net::TcpStream::connect("google.com:80");
+    let _stream = rt.block_on(async move { stream.await.unwrap() });
+
+    assert_eq!(metrics.io_driver_ready_count(), 1);
+}
+
+fn current_thread() -> Runtime {
+    tokio::runtime::Builder::new_current_thread()
+        .enable_all()
+        .build()
+        .unwrap()
+}
+
+fn threaded() -> Runtime {
+    tokio::runtime::Builder::new_multi_thread()
+        .worker_threads(2)
+        .enable_all()
+        .build()
+        .unwrap()
+}
+
+fn us(n: u64) -> Duration {
+    Duration::from_micros(n)
+}
diff --git a/vendor/tokio/tests/rt_panic.rs b/vendor/tokio/tests/rt_panic.rs
new file mode 100644
index 000000000..f9a684fda
--- /dev/null
+++ b/vendor/tokio/tests/rt_panic.rs
@@ -0,0 +1,77 @@
+#![warn(rust_2018_idioms)]
+#![cfg(feature = "full")]
+#![cfg(not(tokio_wasi))] // Wasi doesn't support panic recovery
+
+use futures::future;
+use std::error::Error;
+use tokio::runtime::{Builder, Handle, Runtime};
+
+mod support {
+    pub mod panic;
+}
+use support::panic::test_panic;
+
+#[test]
+fn current_handle_panic_caller() -> Result<(), Box<dyn Error>> {
+    let panic_location_file = test_panic(|| {
+        let _ = Handle::current();
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+fn into_panic_panic_caller() -> Result<(), Box<dyn Error>> {
+    let panic_location_file = test_panic(move || {
+        let rt = current_thread();
+        rt.block_on(async {
+            let handle = tokio::spawn(future::pending::<()>());
+
+            handle.abort();
+
+            let err = handle.await.unwrap_err();
+            assert!(!&err.is_panic());
+
+            let _ = err.into_panic();
+        });
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+fn builder_worker_threads_panic_caller() -> Result<(), Box<dyn Error>> {
+    let panic_location_file = test_panic(|| {
+        let _ = Builder::new_multi_thread().worker_threads(0).build();
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+fn builder_max_blocking_threads_panic_caller() -> Result<(), Box<dyn Error>> {
+    let panic_location_file = test_panic(|| {
+        let _ = Builder::new_multi_thread().max_blocking_threads(0).build();
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+fn current_thread() -> Runtime {
+    tokio::runtime::Builder::new_current_thread()
+        .enable_all()
+        .build()
+        .unwrap()
+}
diff --git a/vendor/tokio/tests/rt_threaded.rs b/vendor/tokio/tests/rt_threaded.rs
index 9e76c4ed0..69b186947 100644
--- a/vendor/tokio/tests/rt_threaded.rs
+++ b/vendor/tokio/tests/rt_threaded.rs
@@ -1,9 +1,9 @@
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+#![cfg(all(feature = "full", not(tokio_wasi)))]
 
 use tokio::io::{AsyncReadExt, AsyncWriteExt};
 use tokio::net::{TcpListener, TcpStream};
-use tokio::runtime::{self, Runtime};
+use tokio::runtime;
 use tokio::sync::oneshot;
 use tokio_test::{assert_err, assert_ok};
 
@@ -15,13 +15,23 @@ use std::sync::atomic::Ordering::Relaxed;
 use std::sync::{mpsc, Arc, Mutex};
 use std::task::{Context, Poll, Waker};
 
+macro_rules! cfg_metrics {
+    ($($t:tt)*) => {
+        #[cfg(tokio_unstable)]
+        {
+            $( $t )*
+        }
+    }
+}
+
 #[test]
 fn single_thread() {
     // No panic when starting a runtime w/ a single thread
     let _ = runtime::Builder::new_multi_thread()
         .enable_all()
         .worker_threads(1)
-        .build();
+        .build()
+        .unwrap();
 }
 
 #[test]
@@ -54,6 +64,39 @@ fn many_oneshot_futures() {
         drop(rt);
     }
 }
+
+#[test]
+fn spawn_two() {
+    let rt = rt();
+
+    let out = rt.block_on(async {
+        let (tx, rx) = oneshot::channel();
+
+        tokio::spawn(async move {
+            tokio::spawn(async move {
+                tx.send("ZOMG").unwrap();
+            });
+        });
+
+        assert_ok!(rx.await)
+    });
+
+    assert_eq!(out, "ZOMG");
+
+    cfg_metrics! {
+        let metrics = rt.metrics();
+        drop(rt);
+        assert_eq!(1, metrics.remote_schedule_count());
+
+        let mut local = 0;
+        for i in 0..metrics.num_workers() {
+            local += metrics.worker_local_schedule_count(i);
+        }
+
+        assert_eq!(1, local);
+    }
+}
+
 #[test]
 fn many_multishot_futures() {
     const CHAIN: usize = 200;
@@ -119,6 +162,32 @@ fn many_multishot_futures() {
 }
 
 #[test]
+fn lifo_slot_budget() {
+    async fn my_fn() {
+        spawn_another();
+    }
+
+    fn spawn_another() {
+        tokio::spawn(my_fn());
+    }
+
+    let rt = runtime::Builder::new_multi_thread()
+        .enable_all()
+        .worker_threads(1)
+        .build()
+        .unwrap();
+
+    let (send, recv) = oneshot::channel();
+
+    rt.spawn(async move {
+        tokio::spawn(my_fn());
+        let _ = send.send(());
+    });
+
+    let _ = rt.block_on(recv);
+}
+
+#[test]
 fn spawn_shutdown() {
     let rt = rt();
     let (tx, rx) = mpsc::channel();
@@ -373,6 +442,32 @@ fn coop_and_block_in_place() {
     });
 }
 
+#[test]
+fn yield_after_block_in_place() {
+    let rt = tokio::runtime::Builder::new_multi_thread()
+        .worker_threads(1)
+        .build()
+        .unwrap();
+
+    rt.block_on(async {
+        tokio::spawn(async move {
+            // Block in place then enter a new runtime
+            tokio::task::block_in_place(|| {
+                let rt = tokio::runtime::Builder::new_current_thread()
+                    .build()
+                    .unwrap();
+
+                rt.block_on(async {});
+            });
+
+            // Yield, then complete
+            tokio::task::yield_now().await;
+        })
+        .await
+        .unwrap()
+    });
+}
+
 // Testing this does not panic
 #[test]
 fn max_blocking_threads() {
@@ -438,9 +533,7 @@ fn wake_during_shutdown() {
         fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<()> {
             let me = Pin::into_inner(self);
             let mut lock = me.shared.lock().unwrap();
-            println!("poll {}", me.put_waker);
             if me.put_waker {
-                println!("putting");
                 lock.waker = Some(cx.waker().clone());
             }
             Poll::Pending
@@ -449,13 +542,11 @@ fn wake_during_shutdown() {
 
     impl Drop for MyFuture {
         fn drop(&mut self) {
-            println!("drop {} start", self.put_waker);
             let mut lock = self.shared.lock().unwrap();
             if !self.put_waker {
                 lock.waker.take().unwrap().wake();
             }
             drop(lock);
-            println!("drop {} stop", self.put_waker);
         }
     }
 
@@ -473,6 +564,202 @@ fn wake_during_shutdown() {
     rt.block_on(async { tokio::time::sleep(tokio::time::Duration::from_millis(20)).await });
 }
 
-fn rt() -> Runtime {
-    Runtime::new().unwrap()
+#[should_panic]
+#[tokio::test]
+async fn test_block_in_place1() {
+    tokio::task::block_in_place(|| {});
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn test_block_in_place2() {
+    tokio::task::block_in_place(|| {});
+}
+
+#[should_panic]
+#[tokio::main(flavor = "current_thread")]
+#[test]
+async fn test_block_in_place3() {
+    tokio::task::block_in_place(|| {});
+}
+
+#[tokio::main]
+#[test]
+async fn test_block_in_place4() {
+    tokio::task::block_in_place(|| {});
+}
+
+// Repro for tokio-rs/tokio#5239
+#[test]
+fn test_nested_block_in_place_with_block_on_between() {
+    let rt = runtime::Builder::new_multi_thread()
+        .worker_threads(1)
+        // Needs to be more than 0
+        .max_blocking_threads(1)
+        .build()
+        .unwrap();
+
+    // Triggered by a race condition, so run a few times to make sure it is OK.
+    for _ in 0..100 {
+        let h = rt.handle().clone();
+
+        rt.block_on(async move {
+            tokio::spawn(async move {
+                tokio::task::block_in_place(|| {
+                    h.block_on(async {
+                        tokio::task::block_in_place(|| {});
+                    });
+                })
+            })
+            .await
+            .unwrap()
+        });
+    }
+}
+
+// Testing the tuning logic is tricky as it is inherently timing based, and more
+// of a heuristic than an exact behavior. This test checks that the interval
+// changes over time based on load factors. There are no assertions, completion
+// is sufficient. If there is a regression, this test will hang. In theory, we
+// could add limits, but that would be likely to fail on CI.
+#[test]
+#[cfg(not(tokio_no_tuning_tests))]
+fn test_tuning() {
+    use std::sync::atomic::AtomicBool;
+    use std::time::Duration;
+
+    let rt = runtime::Builder::new_multi_thread()
+        .worker_threads(1)
+        .build()
+        .unwrap();
+
+    fn iter(flag: Arc<AtomicBool>, counter: Arc<AtomicUsize>, stall: bool) {
+        if flag.load(Relaxed) {
+            if stall {
+                std::thread::sleep(Duration::from_micros(5));
+            }
+
+            counter.fetch_add(1, Relaxed);
+            tokio::spawn(async move { iter(flag, counter, stall) });
+        }
+    }
+
+    let flag = Arc::new(AtomicBool::new(true));
+    let counter = Arc::new(AtomicUsize::new(61));
+    let interval = Arc::new(AtomicUsize::new(61));
+
+    {
+        let flag = flag.clone();
+        let counter = counter.clone();
+        rt.spawn(async move { iter(flag, counter, true) });
+    }
+
+    // Now, hammer the injection queue until the interval drops.
+    let mut n = 0;
+    loop {
+        let curr = interval.load(Relaxed);
+
+        if curr <= 8 {
+            n += 1;
+        } else {
+            n = 0;
+        }
+
+        // Make sure we get a few good rounds. Jitter in the tuning could result
+        // in one "good" value without being representative of reaching a good
+        // state.
+        if n == 3 {
+            break;
+        }
+
+        if Arc::strong_count(&interval) < 5_000 {
+            let counter = counter.clone();
+            let interval = interval.clone();
+
+            rt.spawn(async move {
+                let prev = counter.swap(0, Relaxed);
+                interval.store(prev, Relaxed);
+            });
+
+            std::thread::yield_now();
+        }
+    }
+
+    flag.store(false, Relaxed);
+
+    let w = Arc::downgrade(&interval);
+    drop(interval);
+
+    while w.strong_count() > 0 {
+        std::thread::sleep(Duration::from_micros(500));
+    }
+
+    // Now, run it again with a faster task
+    let flag = Arc::new(AtomicBool::new(true));
+    // Set it high, we know it shouldn't ever really be this high
+    let counter = Arc::new(AtomicUsize::new(10_000));
+    let interval = Arc::new(AtomicUsize::new(10_000));
+
+    {
+        let flag = flag.clone();
+        let counter = counter.clone();
+        rt.spawn(async move { iter(flag, counter, false) });
+    }
+
+    // Now, hammer the injection queue until the interval reaches the expected range.
+    let mut n = 0;
+    loop {
+        let curr = interval.load(Relaxed);
+
+        if curr <= 1_000 && curr > 32 {
+            n += 1;
+        } else {
+            n = 0;
+        }
+
+        if n == 3 {
+            break;
+        }
+
+        if Arc::strong_count(&interval) <= 5_000 {
+            let counter = counter.clone();
+            let interval = interval.clone();
+
+            rt.spawn(async move {
+                let prev = counter.swap(0, Relaxed);
+                interval.store(prev, Relaxed);
+            });
+        }
+
+        std::thread::yield_now();
+    }
+
+    flag.store(false, Relaxed);
+}
+
+fn rt() -> runtime::Runtime {
+    runtime::Runtime::new().unwrap()
+}
+
+#[cfg(tokio_unstable)]
+mod unstable {
+    use super::*;
+
+    #[test]
+    fn test_disable_lifo_slot() {
+        let rt = runtime::Builder::new_multi_thread()
+            .disable_lifo_slot()
+            .worker_threads(2)
+            .build()
+            .unwrap();
+
+        rt.block_on(async {
+            tokio::spawn(async {
+                // Spawn another task and block the thread until completion. If the LIFO slot
+                // is used then the test doesn't complete.
+                futures::executor::block_on(tokio::spawn(async {})).unwrap();
+            })
+            .await
+            .unwrap();
+        })
+    }
 }
diff --git a/vendor/tokio/tests/rt_time_start_paused.rs b/vendor/tokio/tests/rt_time_start_paused.rs
new file mode 100644
index 000000000..283f4748a
--- /dev/null
+++ b/vendor/tokio/tests/rt_time_start_paused.rs
@@ -0,0 +1,14 @@
+#![cfg(all(feature = "full"))]
+
+use tokio::time::{Duration, Instant};
+
+#[tokio::test(start_paused = true)]
+async fn test_start_paused() {
+    let now = Instant::now();
+
+    // Pause a few times w/ std sleep and ensure `now` stays the same
+    for _ in 0..5 {
+        std::thread::sleep(Duration::from_millis(1));
+        assert_eq!(now, Instant::now());
+    }
+}
diff --git a/vendor/tokio/tests/signal_no_rt.rs b/vendor/tokio/tests/signal_no_rt.rs
index b0f32b2d1..ffcc6651c 100644
--- a/vendor/tokio/tests/signal_no_rt.rs
+++ b/vendor/tokio/tests/signal_no_rt.rs
@@ -4,6 +4,7 @@
 
 use tokio::signal::unix::{signal, SignalKind};
 
+#[cfg_attr(tokio_wasi, ignore = "Wasi does not support panic recovery")]
 #[test]
 #[should_panic]
 fn no_runtime_panics_creating_signals() {
diff --git a/vendor/tokio/tests/signal_panic.rs b/vendor/tokio/tests/signal_panic.rs
new file mode 100644
index 000000000..ce1ec3e4a
--- /dev/null
+++ b/vendor/tokio/tests/signal_panic.rs
@@ -0,0 +1,29 @@
+#![warn(rust_2018_idioms)]
+#![cfg(feature = "full")]
+#![cfg(unix)]
+
+use std::error::Error;
+use tokio::runtime::Builder;
+use tokio::signal::unix::{signal, SignalKind};
+
+mod support {
+    pub mod panic;
+}
+use support::panic::test_panic;
+
+#[test]
+fn signal_panic_caller() -> Result<(), Box<dyn Error>> {
+    let panic_location_file = test_panic(|| {
+        let rt = Builder::new_current_thread().build().unwrap();
+
+        rt.block_on(async {
+            let kind = SignalKind::from_raw(-1);
+            let _ = signal(kind);
+        });
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
diff --git a/vendor/tokio/tests/support/leaked_buffers.rs b/vendor/tokio/tests/support/leaked_buffers.rs
new file mode 100644
index 000000000..a6079fb70
--- /dev/null
+++ b/vendor/tokio/tests/support/leaked_buffers.rs
@@ -0,0 +1,26 @@
+/// Can create buffers of arbitrary lifetime.
+/// Frees created buffers when dropped.
+///
+/// This struct is of course unsafe and the fact that
+/// it must outlive the created slices has to be ensured by
+/// the programmer.
+///
+/// Used at certain test scenarios as a safer version of
+/// Vec::leak, to satisfy the address sanitizer.
+pub struct LeakedBuffers {
+    leaked_vecs: Vec<Box<[u8]>>,
+}
+
+impl LeakedBuffers {
+    pub fn new() -> Self {
+        Self {
+            leaked_vecs: vec![],
+        }
+    }
+    pub unsafe fn create<'a>(&mut self, size: usize) -> &'a mut [u8] {
+        let new_mem = vec![0u8; size].into_boxed_slice();
+        self.leaked_vecs.push(new_mem);
+        let new_mem = self.leaked_vecs.last_mut().unwrap();
+        std::slice::from_raw_parts_mut(new_mem.as_mut_ptr(), new_mem.len())
+    }
+}
diff --git a/vendor/tokio/tests/support/panic.rs b/vendor/tokio/tests/support/panic.rs
new file mode 100644
index 000000000..df2f59d30
--- /dev/null
+++ b/vendor/tokio/tests/support/panic.rs
@@ -0,0 +1,34 @@
+use std::panic;
+use std::sync::{Arc, Mutex};
+
+pub fn test_panic<Func: FnOnce() + panic::UnwindSafe>(func: Func) -> Option<String> {
+    static PANIC_MUTEX: Mutex<()> = Mutex::new(());
+
+    {
+        let _guard = PANIC_MUTEX.lock();
+        let panic_file: Arc<Mutex<Option<String>>> = Arc::new(Mutex::new(None));
+
+        let prev_hook = panic::take_hook();
+        {
+            let panic_file = panic_file.clone();
+            panic::set_hook(Box::new(move |panic_info| {
+                let panic_location = panic_info.location().unwrap();
+                panic_file
+                    .lock()
+                    .unwrap()
+                    .clone_from(&Some(panic_location.file().to_string()));
+            }));
+        }
+
+        let result = panic::catch_unwind(func);
+        // Return to the previously set panic hook (maybe default) so that we get nice error
+        // messages in the tests.
+        panic::set_hook(prev_hook);
+
+        if result.is_err() {
+            panic_file.lock().unwrap().clone()
+        } else {
+            None
+        }
+    }
+}
diff --git a/vendor/tokio/tests/sync_barrier.rs b/vendor/tokio/tests/sync_barrier.rs
index f280fe860..2001c3598 100644
--- a/vendor/tokio/tests/sync_barrier.rs
+++ b/vendor/tokio/tests/sync_barrier.rs
@@ -1,6 +1,9 @@
 #![allow(clippy::unnecessary_operation)]
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+#![cfg(feature = "sync")]
+
+#[cfg(tokio_wasm_not_wasi)]
+use wasm_bindgen_test::wasm_bindgen_test as test;
 
 use tokio::sync::Barrier;
 
diff --git a/vendor/tokio/tests/sync_broadcast.rs b/vendor/tokio/tests/sync_broadcast.rs
index 5f79800a7..feed03148 100644
--- a/vendor/tokio/tests/sync_broadcast.rs
+++ b/vendor/tokio/tests/sync_broadcast.rs
@@ -2,6 +2,9 @@
 #![warn(rust_2018_idioms)]
 #![cfg(feature = "sync")]
 
+#[cfg(tokio_wasm_not_wasi)]
+use wasm_bindgen_test::wasm_bindgen_test as test;
+
 use tokio::sync::broadcast;
 use tokio_test::task;
 use tokio_test::{
@@ -44,7 +47,7 @@ macro_rules! assert_closed {
     ($e:expr) => {
         match assert_err!($e) {
             broadcast::error::TryRecvError::Closed => {}
-            _ => panic!("did not lag"),
+            _ => panic!("is not closed"),
         }
     };
 }
@@ -273,12 +276,14 @@ fn send_no_rx() {
 
 #[test]
 #[should_panic]
+#[cfg(not(tokio_wasm))] // wasm currently doesn't support unwinding
 fn zero_capacity() {
     broadcast::channel::<()>(0);
 }
 
 #[test]
 #[should_panic]
+#[cfg(not(tokio_wasm))] // wasm currently doesn't support unwinding
 fn capacity_too_big() {
     use std::usize;
 
@@ -286,6 +291,8 @@ fn capacity_too_big() {
 }
 
 #[test]
+#[cfg(panic = "unwind")]
+#[cfg(not(tokio_wasm))] // wasm currently doesn't support unwinding
 fn panic_in_clone() {
     use std::panic::{self, AssertUnwindSafe};
 
@@ -451,6 +458,186 @@ fn lagging_receiver_recovers_after_wrap_open() {
     assert_empty!(rx);
 }
 
+#[test]
+fn receiver_len_with_lagged() {
+    let (tx, mut rx) = broadcast::channel(3);
+
+    tx.send(10).unwrap();
+    tx.send(20).unwrap();
+    tx.send(30).unwrap();
+    tx.send(40).unwrap();
+
+    assert_eq!(rx.len(), 4);
+    assert_eq!(assert_recv!(rx), 10);
+
+    tx.send(50).unwrap();
+    tx.send(60).unwrap();
+
+    assert_eq!(rx.len(), 5);
+    assert_lagged!(rx.try_recv(), 1);
+}
+
 fn is_closed(err: broadcast::error::RecvError) -> bool {
     matches!(err, broadcast::error::RecvError::Closed)
 }
+
+#[test]
+fn resubscribe_points_to_tail() {
+    let (tx, mut rx) = broadcast::channel(3);
+    tx.send(1).unwrap();
+
+    let mut rx_resub = rx.resubscribe();
+
+    // verify we're one behind at the start
+    assert_empty!(rx_resub);
+    assert_eq!(assert_recv!(rx), 1);
+
+    // verify we do not affect rx
+    tx.send(2).unwrap();
+    assert_eq!(assert_recv!(rx_resub), 2);
+    tx.send(3).unwrap();
+    assert_eq!(assert_recv!(rx), 2);
+    assert_eq!(assert_recv!(rx), 3);
+    assert_empty!(rx);
+
+    assert_eq!(assert_recv!(rx_resub), 3);
+    assert_empty!(rx_resub);
+}
+
+#[test]
+fn resubscribe_lagged() {
+    let (tx, mut rx) = broadcast::channel(1);
+    tx.send(1).unwrap();
+    tx.send(2).unwrap();
+
+    let mut rx_resub = rx.resubscribe();
+    assert_lagged!(rx.try_recv(), 1);
+    assert_empty!(rx_resub);
+
+    assert_eq!(assert_recv!(rx), 2);
+    assert_empty!(rx);
+    assert_empty!(rx_resub);
+}
+
+#[test]
+fn resubscribe_to_closed_channel() {
+    let (tx, rx) = tokio::sync::broadcast::channel::<u32>(2);
+    drop(tx);
+
+    let mut rx_resub = rx.resubscribe();
+    assert_closed!(rx_resub.try_recv());
+}
+
+#[test]
+fn sender_len() {
+    let (tx, mut rx1) = broadcast::channel(4);
+    let mut rx2 = tx.subscribe();
+
+    assert_eq!(tx.len(), 0);
+    assert!(tx.is_empty());
+
+    tx.send(1).unwrap();
+    tx.send(2).unwrap();
+    tx.send(3).unwrap();
+
+    assert_eq!(tx.len(), 3);
+    assert!(!tx.is_empty());
+
+    assert_recv!(rx1);
+    assert_recv!(rx1);
+
+    assert_eq!(tx.len(), 3);
+    assert!(!tx.is_empty());
+
+    assert_recv!(rx2);
+
+    assert_eq!(tx.len(), 2);
+    assert!(!tx.is_empty());
+
+    tx.send(4).unwrap();
+    tx.send(5).unwrap();
+    tx.send(6).unwrap();
+
+    assert_eq!(tx.len(), 4);
+    assert!(!tx.is_empty());
+}
+
+#[test]
+#[cfg(not(tokio_wasm_not_wasi))]
+fn sender_len_random() {
+    use rand::Rng;
+
+    let (tx, mut rx1) = broadcast::channel(16);
+    let mut rx2 = tx.subscribe();
+
+    for _ in 0..1000 {
+        match rand::thread_rng().gen_range(0..4) {
+            0 => {
+                let _ = rx1.try_recv();
+            }
+            1 => {
+                let _ = rx2.try_recv();
+            }
+            _ => {
+                tx.send(0).unwrap();
+            }
+        }
+
+        let expected_len = usize::min(usize::max(rx1.len(), rx2.len()), 16);
+        assert_eq!(tx.len(), expected_len);
+    }
+}
+
+#[test]
+fn send_in_waker_drop() {
+    use futures::task::ArcWake;
+    use std::future::Future;
+    use std::task::Context;
+
+    struct SendOnDrop(broadcast::Sender<()>);
+
+    impl Drop for SendOnDrop {
+        fn drop(&mut self) {
+            let _ = self.0.send(());
+        }
+    }
+
+    impl ArcWake for SendOnDrop {
+        fn wake_by_ref(_arc_self: &Arc<Self>) {}
+    }
+
+    // Test if there is no deadlock when replacing the old waker.
+
+    let (tx, mut rx) = broadcast::channel(16);
+
+    let mut fut = Box::pin(async {
+        let _ = rx.recv().await;
+    });
+
+    // Store our special waker in the receiving future.
+    let waker = futures::task::waker(Arc::new(SendOnDrop(tx)));
+    let mut cx = Context::from_waker(&waker);
+    assert!(fut.as_mut().poll(&mut cx).is_pending());
+    drop(waker);
+
+    // Second poll shouldn't deadlock.
+    let mut cx = Context::from_waker(futures::task::noop_waker_ref());
+    let _ = fut.as_mut().poll(&mut cx);
+
+    // Test if there is no deadlock when calling waker.wake().
+
+    let (tx, mut rx) = broadcast::channel(16);
+
+    let mut fut = Box::pin(async {
+        let _ = rx.recv().await;
+    });
+
+    // Store our special waker in the receiving future.
+    let waker = futures::task::waker(Arc::new(SendOnDrop(tx.clone())));
+    let mut cx = Context::from_waker(&waker);
+    assert!(fut.as_mut().poll(&mut cx).is_pending());
+    drop(waker);
+
+    // Shouldn't deadlock.
+    let _ = tx.send(());
+}
diff --git a/vendor/tokio/tests/sync_errors.rs b/vendor/tokio/tests/sync_errors.rs
index 66e8f0c09..bf0a6cf73 100644
--- a/vendor/tokio/tests/sync_errors.rs
+++ b/vendor/tokio/tests/sync_errors.rs
@@ -1,5 +1,8 @@
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+#![cfg(feature = "sync")]
+
+#[cfg(tokio_wasm_not_wasi)]
+use wasm_bindgen_test::wasm_bindgen_test as test;
 
 fn is_error<T: std::error::Error + Send + Sync>() {}
 
diff --git a/vendor/tokio/tests/sync_mpsc.rs b/vendor/tokio/tests/sync_mpsc.rs
index cd43ad438..6e8709641 100644
--- a/vendor/tokio/tests/sync_mpsc.rs
+++ b/vendor/tokio/tests/sync_mpsc.rs
@@ -1,18 +1,21 @@
 #![allow(clippy::redundant_clone)]
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+#![cfg(feature = "sync")]
 
-use std::thread;
-use tokio::runtime::Runtime;
-use tokio::sync::mpsc;
-use tokio::sync::mpsc::error::TrySendError;
-use tokio_test::task;
-use tokio_test::{
-    assert_err, assert_ok, assert_pending, assert_ready, assert_ready_err, assert_ready_ok,
-};
+#[cfg(tokio_wasm_not_wasi)]
+use wasm_bindgen_test::wasm_bindgen_test as test;
+#[cfg(tokio_wasm_not_wasi)]
+use wasm_bindgen_test::wasm_bindgen_test as maybe_tokio_test;
 
+use std::fmt;
 use std::sync::Arc;
+use tokio::sync::mpsc;
+use tokio::sync::mpsc::error::{TryRecvError, TrySendError};
+#[cfg(not(tokio_wasm_not_wasi))]
+use tokio::test as maybe_tokio_test;
+use tokio_test::*;
 
+#[cfg(not(tokio_wasm))]
 mod support {
     pub(crate) mod mpsc_stream;
 }
@@ -21,7 +24,7 @@ trait AssertSend: Send {}
 impl AssertSend for mpsc::Sender<i32> {}
 impl AssertSend for mpsc::Receiver<i32> {}
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn send_recv_with_buffer() {
     let (tx, mut rx) = mpsc::channel::<i32>(16);
 
@@ -46,6 +49,7 @@ async fn send_recv_with_buffer() {
 }
 
 #[tokio::test]
+#[cfg(feature = "full")]
 async fn reserve_disarm() {
     let (tx, mut rx) = mpsc::channel::<i32>(2);
     let tx1 = tx.clone();
@@ -58,10 +62,10 @@ async fn reserve_disarm() {
     let permit2 = assert_ok!(tx2.reserve().await);
 
     // But a third should not be ready
-    let mut r3 = task::spawn(tx3.reserve());
+    let mut r3 = tokio_test::task::spawn(tx3.reserve());
     assert_pending!(r3.poll());
 
-    let mut r4 = task::spawn(tx4.reserve());
+    let mut r4 = tokio_test::task::spawn(tx4.reserve());
     assert_pending!(r4.poll());
 
     // Using one of the reserved slots should allow a new handle to become ready
@@ -78,11 +82,12 @@ async fn reserve_disarm() {
     drop(permit2);
     assert!(r4.is_woken());
 
-    let mut r1 = task::spawn(tx1.reserve());
+    let mut r1 = tokio_test::task::spawn(tx1.reserve());
     assert_pending!(r1.poll());
 }
 
 #[tokio::test]
+#[cfg(all(feature = "full", not(tokio_wasi)))] // Wasi doesn't support threads
 async fn send_recv_stream_with_buffer() {
     use tokio_stream::StreamExt;
 
@@ -100,6 +105,7 @@ async fn send_recv_stream_with_buffer() {
 }
 
 #[tokio::test]
+#[cfg(feature = "full")]
 async fn async_send_recv_with_buffer() {
     let (tx, mut rx) = mpsc::channel(16);
 
@@ -114,10 +120,11 @@ async fn async_send_recv_with_buffer() {
 }
 
 #[tokio::test]
+#[cfg(feature = "full")]
 async fn start_send_past_cap() {
     use std::future::Future;
 
-    let mut t1 = task::spawn(());
+    let mut t1 = tokio_test::task::spawn(());
 
     let (tx1, mut rx) = mpsc::channel(1);
     let tx2 = tx1.clone();
@@ -128,7 +135,7 @@ async fn start_send_past_cap() {
     t1.enter(|cx, _| assert_pending!(r1.as_mut().poll(cx)));
 
     {
-        let mut r2 = task::spawn(tx2.reserve());
+        let mut r2 = tokio_test::task::spawn(tx2.reserve());
         assert_pending!(r2.poll());
 
         drop(r1);
@@ -147,11 +154,12 @@ async fn start_send_past_cap() {
 
 #[test]
 #[should_panic]
+#[cfg(not(tokio_wasm))] // wasm currently doesn't support unwinding
 fn buffer_gteq_one() {
     mpsc::channel::<i32>(0);
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn send_recv_unbounded() {
     let (tx, mut rx) = mpsc::unbounded_channel::<i32>();
 
@@ -168,6 +176,7 @@ async fn send_recv_unbounded() {
 }
 
 #[tokio::test]
+#[cfg(feature = "full")]
 async fn async_send_recv_unbounded() {
     let (tx, mut rx) = mpsc::unbounded_channel();
 
@@ -182,6 +191,7 @@ async fn async_send_recv_unbounded() {
 }
 
 #[tokio::test]
+#[cfg(all(feature = "full", not(tokio_wasi)))] // Wasi doesn't support threads
 async fn send_recv_stream_unbounded() {
     use tokio_stream::StreamExt;
 
@@ -199,32 +209,32 @@ async fn send_recv_stream_unbounded() {
     assert_eq!(None, rx.next().await);
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn no_t_bounds_buffer() {
     struct NoImpls;
 
     let (tx, mut rx) = mpsc::channel(100);
 
     // sender should be Debug even though T isn't Debug
-    println!("{:?}", tx);
+    is_debug(&tx);
     // same with Receiver
-    println!("{:?}", rx);
+    is_debug(&rx);
     // and sender should be Clone even though T isn't Clone
     assert!(tx.clone().try_send(NoImpls).is_ok());
 
     assert!(rx.recv().await.is_some());
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn no_t_bounds_unbounded() {
     struct NoImpls;
 
     let (tx, mut rx) = mpsc::unbounded_channel();
 
     // sender should be Debug even though T isn't Debug
-    println!("{:?}", tx);
+    is_debug(&tx);
     // same with Receiver
-    println!("{:?}", rx);
+    is_debug(&rx);
     // and sender should be Clone even though T isn't Clone
     assert!(tx.clone().send(NoImpls).is_ok());
 
@@ -232,6 +242,7 @@ async fn no_t_bounds_unbounded() {
 }
 
 #[tokio::test]
+#[cfg(feature = "full")]
 async fn send_recv_buffer_limited() {
     let (tx, mut rx) = mpsc::channel::<i32>(1);
 
@@ -242,7 +253,7 @@ async fn send_recv_buffer_limited() {
     p1.send(1);
 
     // Not ready
-    let mut p2 = task::spawn(tx.reserve());
+    let mut p2 = tokio_test::task::spawn(tx.reserve());
     assert_pending!(p2.poll());
 
     // Take the value
@@ -261,7 +272,7 @@ async fn send_recv_buffer_limited() {
     assert!(rx.recv().await.is_some());
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn recv_close_gets_none_idle() {
     let (tx, mut rx) = mpsc::channel::<i32>(10);
 
@@ -273,12 +284,13 @@ async fn recv_close_gets_none_idle() {
 }
 
 #[tokio::test]
+#[cfg(feature = "full")]
 async fn recv_close_gets_none_reserved() {
     let (tx1, mut rx) = mpsc::channel::<i32>(1);
     let tx2 = tx1.clone();
 
     let permit1 = assert_ok!(tx1.reserve().await);
-    let mut permit2 = task::spawn(tx2.reserve());
+    let mut permit2 = tokio_test::task::spawn(tx2.reserve());
     assert_pending!(permit2.poll());
 
     rx.close();
@@ -287,7 +299,7 @@ async fn recv_close_gets_none_reserved() {
     assert_ready_err!(permit2.poll());
 
     {
-        let mut recv = task::spawn(rx.recv());
+        let mut recv = tokio_test::task::spawn(rx.recv());
         assert_pending!(recv.poll());
 
         permit1.send(123);
@@ -300,13 +312,13 @@ async fn recv_close_gets_none_reserved() {
     assert!(rx.recv().await.is_none());
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn tx_close_gets_none() {
     let (_, mut rx) = mpsc::channel::<i32>(10);
     assert!(rx.recv().await.is_none());
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn try_send_fail() {
     let (tx, mut rx) = mpsc::channel(1);
 
@@ -327,7 +339,28 @@ async fn try_send_fail() {
     assert!(rx.recv().await.is_none());
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
+async fn try_send_fail_with_try_recv() {
+    let (tx, mut rx) = mpsc::channel(1);
+
+    tx.try_send("hello").unwrap();
+
+    // This should fail
+    match assert_err!(tx.try_send("fail")) {
+        TrySendError::Full(..) => {}
+        _ => panic!(),
+    }
+
+    assert_eq!(rx.try_recv(), Ok("hello"));
+
+    assert_ok!(tx.try_send("goodbye"));
+    drop(tx);
+
+    assert_eq!(rx.try_recv(), Ok("goodbye"));
+    assert_eq!(rx.try_recv(), Err(TryRecvError::Disconnected));
+}
+
+#[maybe_tokio_test]
 async fn try_reserve_fails() {
     let (tx, mut rx) = mpsc::channel(1);
 
@@ -351,6 +384,7 @@ async fn try_reserve_fails() {
 }
 
 #[tokio::test]
+#[cfg(feature = "full")]
 async fn drop_permit_releases_permit() {
     // poll_ready reserves capacity, ensure that the capacity is released if tx
     // is dropped w/o sending a value.
@@ -359,7 +393,7 @@ async fn drop_permit_releases_permit() {
 
     let permit = assert_ok!(tx1.reserve().await);
 
-    let mut reserve2 = task::spawn(tx2.reserve());
+    let mut reserve2 = tokio_test::task::spawn(tx2.reserve());
     assert_pending!(reserve2.poll());
 
     drop(permit);
@@ -368,7 +402,7 @@ async fn drop_permit_releases_permit() {
     assert_ready_ok!(reserve2.poll());
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn dropping_rx_closes_channel() {
     let (tx, rx) = mpsc::channel(100);
 
@@ -389,13 +423,15 @@ fn dropping_rx_closes_channel_for_try() {
 
     drop(rx);
 
-    {
-        let err = assert_err!(tx.try_send(msg.clone()));
-        match err {
-            TrySendError::Closed(..) => {}
-            _ => panic!(),
-        }
-    }
+    assert!(matches!(
+        tx.try_send(msg.clone()),
+        Err(TrySendError::Closed(_))
+    ));
+    assert!(matches!(tx.try_reserve(), Err(TrySendError::Closed(_))));
+    assert!(matches!(
+        tx.try_reserve_owned(),
+        Err(TrySendError::Closed(_))
+    ));
 
     assert_eq!(1, Arc::strong_count(&msg));
 }
@@ -416,48 +452,57 @@ fn unconsumed_messages_are_dropped() {
 }
 
 #[test]
+#[cfg(all(feature = "full", not(tokio_wasi)))] // Wasi doesn't support threads
 fn blocking_recv() {
     let (tx, mut rx) = mpsc::channel::<u8>(1);
 
-    let sync_code = thread::spawn(move || {
+    let sync_code = std::thread::spawn(move || {
         assert_eq!(Some(10), rx.blocking_recv());
     });
 
-    Runtime::new().unwrap().block_on(async move {
-        let _ = tx.send(10).await;
-    });
+    tokio::runtime::Runtime::new()
+        .unwrap()
+        .block_on(async move {
+            let _ = tx.send(10).await;
+        });
     sync_code.join().unwrap()
 }
 
 #[tokio::test]
 #[should_panic]
+#[cfg(not(tokio_wasm))] // wasm currently doesn't support unwinding
 async fn blocking_recv_async() {
     let (_tx, mut rx) = mpsc::channel::<()>(1);
     let _ = rx.blocking_recv();
 }
 
 #[test]
+#[cfg(all(feature = "full", not(tokio_wasi)))] // Wasi doesn't support threads
 fn blocking_send() {
     let (tx, mut rx) = mpsc::channel::<u8>(1);
 
-    let sync_code = thread::spawn(move || {
+    let sync_code = std::thread::spawn(move || {
         tx.blocking_send(10).unwrap();
     });
 
-    Runtime::new().unwrap().block_on(async move {
-        assert_eq!(Some(10), rx.recv().await);
-    });
+    tokio::runtime::Runtime::new()
+        .unwrap()
+        .block_on(async move {
+            assert_eq!(Some(10), rx.recv().await);
+        });
     sync_code.join().unwrap()
 }
 
 #[tokio::test]
 #[should_panic]
+#[cfg(not(tokio_wasm))] // wasm currently doesn't support unwinding
 async fn blocking_send_async() {
     let (tx, _rx) = mpsc::channel::<()>(1);
     let _ = tx.blocking_send(());
 }
 
 #[tokio::test]
+#[cfg(feature = "full")]
 async fn ready_close_cancel_bounded() {
     let (tx, mut rx) = mpsc::channel::<()>(100);
     let _tx2 = tx.clone();
@@ -466,7 +511,7 @@ async fn ready_close_cancel_bounded() {
 
     rx.close();
 
-    let mut recv = task::spawn(rx.recv());
+    let mut recv = tokio_test::task::spawn(rx.recv());
     assert_pending!(recv.poll());
 
     drop(permit);
@@ -477,13 +522,14 @@ async fn ready_close_cancel_bounded() {
 }
 
 #[tokio::test]
+#[cfg(feature = "full")]
 async fn permit_available_not_acquired_close() {
     let (tx1, mut rx) = mpsc::channel::<()>(1);
     let tx2 = tx1.clone();
 
     let permit1 = assert_ok!(tx1.reserve().await);
 
-    let mut permit2 = task::spawn(tx2.reserve());
+    let mut permit2 = tokio_test::task::spawn(tx2.reserve());
     assert_pending!(permit2.poll());
 
     rx.close();
@@ -494,3 +540,140 @@ async fn permit_available_not_acquired_close() {
     drop(permit2);
     assert!(rx.recv().await.is_none());
 }
+
+#[test]
+fn try_recv_bounded() {
+    let (tx, mut rx) = mpsc::channel(5);
+
+    tx.try_send("hello").unwrap();
+    tx.try_send("hello").unwrap();
+    tx.try_send("hello").unwrap();
+    tx.try_send("hello").unwrap();
+    tx.try_send("hello").unwrap();
+    assert!(tx.try_send("hello").is_err());
+
+    assert_eq!(Ok("hello"), rx.try_recv());
+    assert_eq!(Ok("hello"), rx.try_recv());
+    assert_eq!(Ok("hello"), rx.try_recv());
+    assert_eq!(Ok("hello"), rx.try_recv());
+    assert_eq!(Ok("hello"), rx.try_recv());
+    assert_eq!(Err(TryRecvError::Empty), rx.try_recv());
+
+    tx.try_send("hello").unwrap();
+    tx.try_send("hello").unwrap();
+    tx.try_send("hello").unwrap();
+    tx.try_send("hello").unwrap();
+    assert_eq!(Ok("hello"), rx.try_recv());
+    tx.try_send("hello").unwrap();
+    tx.try_send("hello").unwrap();
+    assert!(tx.try_send("hello").is_err());
+    assert_eq!(Ok("hello"), rx.try_recv());
+    assert_eq!(Ok("hello"), rx.try_recv());
+    assert_eq!(Ok("hello"), rx.try_recv());
+    assert_eq!(Ok("hello"), rx.try_recv());
+    assert_eq!(Ok("hello"), rx.try_recv());
+    assert_eq!(Err(TryRecvError::Empty), rx.try_recv());
+
+    tx.try_send("hello").unwrap();
+    tx.try_send("hello").unwrap();
+    tx.try_send("hello").unwrap();
+    drop(tx);
+    assert_eq!(Ok("hello"), rx.try_recv());
+    assert_eq!(Ok("hello"), rx.try_recv());
+    assert_eq!(Ok("hello"), rx.try_recv());
+    assert_eq!(Err(TryRecvError::Disconnected), rx.try_recv());
+}
+
+#[test]
+fn try_recv_unbounded() {
+    for num in 0..100 {
+        let (tx, mut rx) = mpsc::unbounded_channel();
+
+        for i in 0..num {
+            tx.send(i).unwrap();
+        }
+
+        for i in 0..num {
+            assert_eq!(rx.try_recv(), Ok(i));
+        }
+
+        assert_eq!(rx.try_recv(), Err(TryRecvError::Empty));
+        drop(tx);
+        assert_eq!(rx.try_recv(), Err(TryRecvError::Disconnected));
+    }
+}
+
+#[test]
+fn try_recv_close_while_empty_bounded() {
+    let (tx, mut rx) = mpsc::channel::<()>(5);
+
+    assert_eq!(Err(TryRecvError::Empty), rx.try_recv());
+    drop(tx);
+    assert_eq!(Err(TryRecvError::Disconnected), rx.try_recv());
+}
+
+#[test]
+fn try_recv_close_while_empty_unbounded() {
+    let (tx, mut rx) = mpsc::unbounded_channel::<()>();
+
+    assert_eq!(Err(TryRecvError::Empty), rx.try_recv());
+    drop(tx);
+    assert_eq!(Err(TryRecvError::Disconnected), rx.try_recv());
+}
+
+#[tokio::test(start_paused = true)]
+#[cfg(feature = "full")]
+async fn recv_timeout() {
+    use tokio::sync::mpsc::error::SendTimeoutError::{Closed, Timeout};
+    use tokio::time::Duration;
+
+    let (tx, rx) = mpsc::channel(5);
+
+    assert_eq!(tx.send_timeout(10, Duration::from_secs(1)).await, Ok(()));
+    assert_eq!(tx.send_timeout(20, Duration::from_secs(1)).await, Ok(()));
+    assert_eq!(tx.send_timeout(30, Duration::from_secs(1)).await, Ok(()));
+    assert_eq!(tx.send_timeout(40, Duration::from_secs(1)).await, Ok(()));
+    assert_eq!(tx.send_timeout(50, Duration::from_secs(1)).await, Ok(()));
+    assert_eq!(
+        tx.send_timeout(60, Duration::from_secs(1)).await,
+        Err(Timeout(60))
+    );
+
+    drop(rx);
+    assert_eq!(
+        tx.send_timeout(70, Duration::from_secs(1)).await,
+        Err(Closed(70))
+    );
+}
+
+#[test]
+#[should_panic = "there is no reactor running, must be called from the context of a Tokio 1.x runtime"]
+#[cfg(not(tokio_wasm))] // wasm currently doesn't support unwinding
+fn recv_timeout_panic() {
+    use futures::future::FutureExt;
+    use tokio::time::Duration;
+
+    let (tx, _rx) = mpsc::channel(5);
+    tx.send_timeout(10, Duration::from_secs(1)).now_or_never();
+}
+
+// Tests that channel `capacity` changes and `max_capacity` stays the same
+#[tokio::test]
+async fn test_tx_capacity() {
+    let (tx, _rx) = mpsc::channel::<()>(10);
+    // both capacities are same before
+    assert_eq!(tx.capacity(), 10);
+    assert_eq!(tx.max_capacity(), 10);
+
+    let _permit = tx.reserve().await.unwrap();
+    // after reserve, only capacity should drop by one
+    assert_eq!(tx.capacity(), 9);
+    assert_eq!(tx.max_capacity(), 10);
+
+    tx.send(()).await.unwrap();
+    // after send, capacity should drop by one again
+    assert_eq!(tx.capacity(), 8);
+    assert_eq!(tx.max_capacity(), 10);
+}
+
+fn is_debug<T: fmt::Debug>(_: &T) {}
diff --git a/vendor/tokio/tests/sync_mpsc_weak.rs b/vendor/tokio/tests/sync_mpsc_weak.rs
new file mode 100644
index 000000000..0fdfc0070
--- /dev/null
+++ b/vendor/tokio/tests/sync_mpsc_weak.rs
@@ -0,0 +1,513 @@
+#![allow(clippy::redundant_clone)]
+#![warn(rust_2018_idioms)]
+#![cfg(feature = "sync")]
+
+#[cfg(tokio_wasm_not_wasi)]
+use wasm_bindgen_test::wasm_bindgen_test as test;
+
+use std::sync::atomic::AtomicUsize;
+use std::sync::atomic::Ordering::{Acquire, Release};
+use tokio::sync::mpsc::{self, channel, unbounded_channel};
+use tokio::sync::oneshot;
+
+#[tokio::test]
+async fn weak_sender() {
+    let (tx, mut rx) = channel(11);
+
+    let tx_weak = tokio::spawn(async move {
+        let tx_weak = tx.clone().downgrade();
+
+        for i in 0..10 {
+            if tx.send(i).await.is_err() {
+                return None;
+            }
+        }
+
+        let tx2 = tx_weak
+            .upgrade()
+            .expect("expected to be able to upgrade tx_weak");
+        let _ = tx2.send(20).await;
+        let tx_weak = tx2.downgrade();
+
+        Some(tx_weak)
+    })
+    .await
+    .unwrap();
+
+    for i in 0..12 {
+        let recvd = rx.recv().await;
+
+        match recvd {
+            Some(msg) => {
+                if i == 10 {
+                    assert_eq!(msg, 20);
+                }
+            }
+            None => {
+                assert_eq!(i, 11);
+                break;
+            }
+        }
+    }
+
+    let tx_weak = tx_weak.unwrap();
+    let upgraded = tx_weak.upgrade();
+    assert!(upgraded.is_none());
+}
+
+#[tokio::test]
+async fn actor_weak_sender() {
+    pub struct MyActor {
+        receiver: mpsc::Receiver<ActorMessage>,
+        sender: mpsc::WeakSender<ActorMessage>,
+        next_id: u32,
+        pub received_self_msg: bool,
+    }
+
+    enum ActorMessage {
+        GetUniqueId { respond_to: oneshot::Sender<u32> },
+        SelfMessage {},
+    }
+
+    impl MyActor {
+        fn new(
+            receiver: mpsc::Receiver<ActorMessage>,
+            sender: mpsc::WeakSender<ActorMessage>,
+        ) -> Self {
+            MyActor {
+                receiver,
+                sender,
+                next_id: 0,
+                received_self_msg: false,
+            }
+        }
+
+        fn handle_message(&mut self, msg: ActorMessage) {
+            match msg {
+                ActorMessage::GetUniqueId { respond_to } => {
+                    self.next_id += 1;
+
+                    // The `let _ =` ignores any errors when sending.
+                    //
+                    // This can happen if the `select!` macro is used
+                    // to cancel waiting for the response.
+                    let _ = respond_to.send(self.next_id);
+                }
+                ActorMessage::SelfMessage { .. } => {
+                    self.received_self_msg = true;
+                }
+            }
+        }
+
+        async fn send_message_to_self(&mut self) {
+            let msg = ActorMessage::SelfMessage {};
+
+            let sender = self.sender.clone();
+
+            // cannot move self.sender here
+            if let Some(sender) = sender.upgrade() {
+                let _ = sender.send(msg).await;
+                self.sender = sender.downgrade();
+            }
+        }
+
+        async fn run(&mut self) {
+            let mut i = 0;
+            while let Some(msg) = self.receiver.recv().await {
+                self.handle_message(msg);
+
+                if i == 0 {
+                    self.send_message_to_self().await;
+                }
+
+                i += 1
+            }
+
+            assert!(self.received_self_msg);
+        }
+    }
+
+    #[derive(Clone)]
+    pub struct MyActorHandle {
+        sender: mpsc::Sender<ActorMessage>,
+    }
+
+    impl MyActorHandle {
+        pub fn new() -> (Self, MyActor) {
+            let (sender, receiver) = mpsc::channel(8);
+            let actor = MyActor::new(receiver, sender.clone().downgrade());
+
+            (Self { sender }, actor)
+        }
+
+        pub async fn get_unique_id(&self) -> u32 {
+            let (send, recv) = oneshot::channel();
+            let msg = ActorMessage::GetUniqueId { respond_to: send };
+
+            // Ignore send errors. If this send fails, so does the
+            // recv.await below. There's no reason to check the
+            // failure twice.
+            let _ = self.sender.send(msg).await;
+            recv.await.expect("Actor task has been killed")
+        }
+    }
+
+    let (handle, mut actor) = MyActorHandle::new();
+
+    let actor_handle = tokio::spawn(async move { actor.run().await });
+
+    let _ = tokio::spawn(async move {
+        let _ = handle.get_unique_id().await;
+        drop(handle);
+    })
+    .await;
+
+    let _ = actor_handle.await;
+}
+
+static NUM_DROPPED: AtomicUsize = AtomicUsize::new(0);
+
+#[derive(Debug)]
+struct Msg;
+
+impl Drop for Msg {
+    fn drop(&mut self) {
+        NUM_DROPPED.fetch_add(1, Release);
+    }
+}
+
+// Tests that no pending messages are put onto the channel after `Rx` was
+// dropped.
+//
+// Note: After the introduction of `WeakSender`, which internally
+// used `Arc` and doesn't call a drop of the channel after the last strong
+// `Sender` was dropped while more than one `WeakSender` remains, we want to
+// ensure that no messages are kept in the channel, which were sent after
+// the receiver was dropped.
+#[tokio::test]
+async fn test_msgs_dropped_on_rx_drop() {
+    let (tx, mut rx) = mpsc::channel(3);
+
+    tx.send(Msg {}).await.unwrap();
+    tx.send(Msg {}).await.unwrap();
+
+    // This msg will be pending and should be dropped when `rx` is dropped
+    let sent_fut = tx.send(Msg {});
+
+    let _ = rx.recv().await.unwrap();
+    let _ = rx.recv().await.unwrap();
+
+    sent_fut.await.unwrap();
+
+    drop(rx);
+
+    assert_eq!(NUM_DROPPED.load(Acquire), 3);
+
+    // This msg will not be put onto `Tx` list anymore, since `Rx` is closed.
+    assert!(tx.send(Msg {}).await.is_err());
+
+    assert_eq!(NUM_DROPPED.load(Acquire), 4);
+}
+
+// Tests that a `WeakSender` is upgradeable when other `Sender`s exist.
+#[test]
+fn downgrade_upgrade_sender_success() {
+    let (tx, _rx) = mpsc::channel::<i32>(1);
+    let weak_tx = tx.downgrade();
+    assert!(weak_tx.upgrade().is_some());
+}
+
+// Tests that a `WeakSender` fails to upgrade when no other `Sender` exists.
+#[test]
+fn downgrade_upgrade_sender_failure() {
+    let (tx, _rx) = mpsc::channel::<i32>(1);
+    let weak_tx = tx.downgrade();
+    drop(tx);
+    assert!(weak_tx.upgrade().is_none());
+}
+
+// Tests that a `WeakSender` cannot be upgraded after a `Sender` was dropped,
+// which existed at the time of the `downgrade` call.
+#[test]
+fn downgrade_drop_upgrade() {
+    let (tx, _rx) = mpsc::channel::<i32>(1);
+
+    // the cloned `Tx` is dropped right away
+    let weak_tx = tx.clone().downgrade();
+    drop(tx);
+    assert!(weak_tx.upgrade().is_none());
+}
+
+// Tests that we can upgrade a weak sender with an outstanding permit
+// but no other strong senders.
+#[tokio::test]
+async fn downgrade_get_permit_upgrade_no_senders() {
+    let (tx, _rx) = mpsc::channel::<i32>(1);
+    let weak_tx = tx.downgrade();
+    let _permit = tx.reserve_owned().await.unwrap();
+    assert!(weak_tx.upgrade().is_some());
+}
+
+// Tests that you can downgrade and upgrade a sender with an outstanding permit
+// but no other senders left.
+#[tokio::test]
+async fn downgrade_upgrade_get_permit_no_senders() {
+    let (tx, _rx) = mpsc::channel::<i32>(1);
+    let tx2 = tx.clone();
+    let _permit = tx.reserve_owned().await.unwrap();
+    let weak_tx = tx2.downgrade();
+    drop(tx2);
+    assert!(weak_tx.upgrade().is_some());
+}
+
+// Tests that `downgrade` does not change the `tx_count` of the channel.
+#[test]
+fn test_tx_count_weak_sender() {
+    let (tx, _rx) = mpsc::channel::<i32>(1);
+    let tx_weak = tx.downgrade();
+    let tx_weak2 = tx.downgrade();
+    drop(tx);
+
+    assert!(tx_weak.upgrade().is_none() && tx_weak2.upgrade().is_none());
+}
+
+#[tokio::test]
+async fn weak_unbounded_sender() {
+    let (tx, mut rx) = unbounded_channel();
+
+    let tx_weak = tokio::spawn(async move {
+        let tx_weak = tx.clone().downgrade();
+
+        for i in 0..10 {
+            if tx.send(i).is_err() {
+                return None;
+            }
+        }
+
+        let tx2 = tx_weak
+            .upgrade()
+            .expect("expected to be able to upgrade tx_weak");
+        let _ = tx2.send(20);
+        let tx_weak = tx2.downgrade();
+
+        Some(tx_weak)
+    })
+    .await
+    .unwrap();
+
+    for i in 0..12 {
+        let recvd = rx.recv().await;
+
+        match recvd {
+            Some(msg) => {
+                if i == 10 {
+                    assert_eq!(msg, 20);
+                }
+            }
+            None => {
+                assert_eq!(i, 11);
+                break;
+            }
+        }
+    }
+
+    let tx_weak = tx_weak.unwrap();
+    let upgraded = tx_weak.upgrade();
+    assert!(upgraded.is_none());
+}
+
+#[tokio::test]
+async fn actor_weak_unbounded_sender() {
+    pub struct MyActor {
+        receiver: mpsc::UnboundedReceiver<ActorMessage>,
+        sender: mpsc::WeakUnboundedSender<ActorMessage>,
+        next_id: u32,
+        pub received_self_msg: bool,
+    }
+
+    enum ActorMessage {
+        GetUniqueId { respond_to: oneshot::Sender<u32> },
+        SelfMessage {},
+    }
+
+    impl MyActor {
+        fn new(
+            receiver: mpsc::UnboundedReceiver<ActorMessage>,
+            sender: mpsc::WeakUnboundedSender<ActorMessage>,
+        ) -> Self {
+            MyActor {
+                receiver,
+                sender,
+                next_id: 0,
+                received_self_msg: false,
+            }
+        }
+
+        fn handle_message(&mut self, msg: ActorMessage) {
+            match msg {
+                ActorMessage::GetUniqueId { respond_to } => {
+                    self.next_id += 1;
+
+                    // The `let _ =` ignores any errors when sending.
+                    //
+                    // This can happen if the `select!` macro is used
+                    // to cancel waiting for the response.
+                    let _ = respond_to.send(self.next_id);
+                }
+                ActorMessage::SelfMessage { .. } => {
+                    self.received_self_msg = true;
+                }
+            }
+        }
+
+        async fn send_message_to_self(&mut self) {
+            let msg = ActorMessage::SelfMessage {};
+
+            let sender = self.sender.clone();
+
+            // cannot move self.sender here
+            if let Some(sender) = sender.upgrade() {
+                let _ = sender.send(msg);
+                self.sender = sender.downgrade();
+            }
+        }
+
+        async fn run(&mut self) {
+            let mut i = 0;
+            while let Some(msg) = self.receiver.recv().await {
+                self.handle_message(msg);
+
+                if i == 0 {
+                    self.send_message_to_self().await;
+                }
+
+                i += 1
+            }
+
+            assert!(self.received_self_msg);
+        }
+    }
+
+    #[derive(Clone)]
+    pub struct MyActorHandle {
+        sender: mpsc::UnboundedSender<ActorMessage>,
+    }
+
+    impl MyActorHandle {
+        pub fn new() -> (Self, MyActor) {
+            let (sender, receiver) = mpsc::unbounded_channel();
+            let actor = MyActor::new(receiver, sender.clone().downgrade());
+
+            (Self { sender }, actor)
+        }
+
+        pub async fn get_unique_id(&self) -> u32 {
+            let (send, recv) = oneshot::channel();
+            let msg = ActorMessage::GetUniqueId { respond_to: send };
+
+            // Ignore send errors. If this send fails, so does the
+            // recv.await below. There's no reason to check the
+            // failure twice.
+            let _ = self.sender.send(msg);
+            recv.await.expect("Actor task has been killed")
+        }
+    }
+
+    let (handle, mut actor) = MyActorHandle::new();
+
+    let actor_handle = tokio::spawn(async move { actor.run().await });
+
+    let _ = tokio::spawn(async move {
+        let _ = handle.get_unique_id().await;
+        drop(handle);
+    })
+    .await;
+
+    let _ = actor_handle.await;
+}
+
+static NUM_DROPPED_UNBOUNDED: AtomicUsize = AtomicUsize::new(0);
+
+#[derive(Debug)]
+struct MsgUnbounded;
+
+impl Drop for MsgUnbounded {
+    fn drop(&mut self) {
+        NUM_DROPPED_UNBOUNDED.fetch_add(1, Release);
+    }
+}
+
+// Tests that no pending messages are put onto the channel after `Rx` was
+// dropped.
+//
+// Note: After the introduction of `UnboundedWeakSender`, which internally
+// used `Arc` and doesn't call a drop of the channel after the last strong
+// `UnboundedSender` was dropped while more than one `UnboundedWeakSender`
+// remains, we want to ensure that no messages are kept in the channel, which
+// were sent after the receiver was dropped.
+#[tokio::test]
+async fn test_msgs_dropped_on_unbounded_rx_drop() {
+    let (tx, mut rx) = mpsc::unbounded_channel();
+
+    tx.send(MsgUnbounded {}).unwrap();
+    tx.send(MsgUnbounded {}).unwrap();
+
+    // This msg will be pending and should be dropped when `rx` is dropped
+    let sent = tx.send(MsgUnbounded {});
+
+    let _ = rx.recv().await.unwrap();
+    let _ = rx.recv().await.unwrap();
+
+    sent.unwrap();
+
+    drop(rx);
+
+    assert_eq!(NUM_DROPPED_UNBOUNDED.load(Acquire), 3);
+
+    // This msg will not be put onto `Tx` list anymore, since `Rx` is closed.
+    assert!(tx.send(MsgUnbounded {}).is_err());
+
+    assert_eq!(NUM_DROPPED_UNBOUNDED.load(Acquire), 4);
+}
+
+// Tests that an `WeakUnboundedSender` is upgradeable when other
+// `UnboundedSender`s exist.
+#[test]
+fn downgrade_upgrade_unbounded_sender_success() {
+    let (tx, _rx) = mpsc::unbounded_channel::<i32>();
+    let weak_tx = tx.downgrade();
+    assert!(weak_tx.upgrade().is_some());
+}
+
+// Tests that a `WeakUnboundedSender` fails to upgrade when no other
+// `UnboundedSender` exists.
+#[test]
+fn downgrade_upgrade_unbounded_sender_failure() {
+    let (tx, _rx) = mpsc::unbounded_channel::<i32>();
+    let weak_tx = tx.downgrade();
+    drop(tx);
+    assert!(weak_tx.upgrade().is_none());
+}
+
+// Tests that an `WeakUnboundedSender` cannot be upgraded after an
+// `UnboundedSender` was dropped, which existed at the time of the `downgrade` call.
+#[test]
+fn downgrade_drop_upgrade_unbounded() {
+    let (tx, _rx) = mpsc::unbounded_channel::<i32>();
+
+    // the cloned `Tx` is dropped right away
+    let weak_tx = tx.clone().downgrade();
+    drop(tx);
+    assert!(weak_tx.upgrade().is_none());
+}
+
+// Tests that `downgrade` does not change the `tx_count` of the channel.
+#[test]
+fn test_tx_count_weak_unbounded_sender() {
+    let (tx, _rx) = mpsc::unbounded_channel::<i32>();
+    let tx_weak = tx.downgrade();
+    let tx_weak2 = tx.downgrade();
+    drop(tx);
+
+    assert!(tx_weak.upgrade().is_none() && tx_weak2.upgrade().is_none());
+}
diff --git a/vendor/tokio/tests/sync_mutex.rs b/vendor/tokio/tests/sync_mutex.rs
index 0ddb203d8..1e35a558c 100644
--- a/vendor/tokio/tests/sync_mutex.rs
+++ b/vendor/tokio/tests/sync_mutex.rs
@@ -1,13 +1,19 @@
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+#![cfg(feature = "sync")]
+
+#[cfg(tokio_wasm_not_wasi)]
+use wasm_bindgen_test::wasm_bindgen_test as test;
+#[cfg(tokio_wasm_not_wasi)]
+use wasm_bindgen_test::wasm_bindgen_test as maybe_tokio_test;
+
+#[cfg(not(tokio_wasm_not_wasi))]
+use tokio::test as maybe_tokio_test;
 
 use tokio::sync::Mutex;
-use tokio::time::{interval, timeout};
 use tokio_test::task::spawn;
 use tokio_test::{assert_pending, assert_ready};
 
 use std::sync::Arc;
-use std::time::Duration;
 
 #[test]
 fn straight_execution() {
@@ -47,7 +53,7 @@ fn readiness() {
     // But once g unlocks, we can acquire it
     drop(g);
     assert!(t2.is_woken());
-    assert_ready!(t2.poll());
+    let _t2 = assert_ready!(t2.poll());
 }
 
 /*
@@ -82,10 +88,14 @@ fn lock() {
 }
 */
 
-#[tokio::test]
 /// Ensure a mutex is unlocked if a future holding the lock
 /// is aborted prematurely.
+#[tokio::test]
+#[cfg(feature = "full")]
 async fn aborted_future_1() {
+    use std::time::Duration;
+    use tokio::time::{interval, timeout};
+
     let m1: Arc<Mutex<usize>> = Arc::new(Mutex::new(0));
     {
         let m2 = m1.clone();
@@ -93,7 +103,7 @@ async fn aborted_future_1() {
         timeout(Duration::from_millis(1u64), async move {
             let iv = interval(Duration::from_millis(1000));
             tokio::pin!(iv);
-            m2.lock().await;
+            let _g = m2.lock().await;
             iv.as_mut().tick().await;
             iv.as_mut().tick().await;
         })
@@ -102,16 +112,20 @@ async fn aborted_future_1() {
     }
     // This should succeed as there is no lock left for the mutex.
     timeout(Duration::from_millis(1u64), async move {
-        m1.lock().await;
+        let _g = m1.lock().await;
     })
     .await
     .expect("Mutex is locked");
 }
 
-#[tokio::test]
 /// This test is similar to `aborted_future_1` but this time the
 /// aborted future is waiting for the lock.
+#[tokio::test]
+#[cfg(feature = "full")]
 async fn aborted_future_2() {
+    use std::time::Duration;
+    use tokio::time::timeout;
+
     let m1: Arc<Mutex<usize>> = Arc::new(Mutex::new(0));
     {
         // Lock mutex
@@ -120,7 +134,7 @@ async fn aborted_future_2() {
             let m2 = m1.clone();
             // Try to lock mutex in a future that is aborted prematurely
             timeout(Duration::from_millis(1u64), async move {
-                m2.lock().await;
+                let _g = m2.lock().await;
             })
             .await
             .unwrap_err();
@@ -128,7 +142,7 @@ async fn aborted_future_2() {
     }
     // This should succeed as there is no lock left for the mutex.
     timeout(Duration::from_millis(1u64), async move {
-        m1.lock().await;
+        let _g = m1.lock().await;
     })
     .await
     .expect("Mutex is locked");
@@ -139,22 +153,22 @@ fn try_lock() {
     let m: Mutex<usize> = Mutex::new(0);
     {
         let g1 = m.try_lock();
-        assert_eq!(g1.is_ok(), true);
+        assert!(g1.is_ok());
         let g2 = m.try_lock();
-        assert_eq!(g2.is_ok(), false);
+        assert!(g2.is_err());
     }
     let g3 = m.try_lock();
-    assert_eq!(g3.is_ok(), true);
+    assert!(g3.is_ok());
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn debug_format() {
     let s = "debug";
     let m = Mutex::new(s.to_string());
     assert_eq!(format!("{:?}", s), format!("{:?}", m.lock().await));
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn mutex_debug() {
     let s = "data";
     let m = Mutex::new(s.to_string());
diff --git a/vendor/tokio/tests/sync_mutex_owned.rs b/vendor/tokio/tests/sync_mutex_owned.rs
index 0f1399c43..ba472fee7 100644
--- a/vendor/tokio/tests/sync_mutex_owned.rs
+++ b/vendor/tokio/tests/sync_mutex_owned.rs
@@ -1,13 +1,19 @@
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+#![cfg(feature = "sync")]
+
+#[cfg(tokio_wasm_not_wasi)]
+use wasm_bindgen_test::wasm_bindgen_test as test;
+#[cfg(tokio_wasm_not_wasi)]
+use wasm_bindgen_test::wasm_bindgen_test as maybe_tokio_test;
+
+#[cfg(not(tokio_wasm_not_wasi))]
+use tokio::test as maybe_tokio_test;
 
 use tokio::sync::Mutex;
-use tokio::time::{interval, timeout};
 use tokio_test::task::spawn;
 use tokio_test::{assert_pending, assert_ready};
 
 use std::sync::Arc;
-use std::time::Duration;
 
 #[test]
 fn straight_execution() {
@@ -49,10 +55,14 @@ fn readiness() {
     assert_ready!(t2.poll());
 }
 
-#[tokio::test]
 /// Ensure a mutex is unlocked if a future holding the lock
 /// is aborted prematurely.
+#[tokio::test]
+#[cfg(feature = "full")]
 async fn aborted_future_1() {
+    use std::time::Duration;
+    use tokio::time::{interval, timeout};
+
     let m1: Arc<Mutex<usize>> = Arc::new(Mutex::new(0));
     {
         let m2 = m1.clone();
@@ -75,10 +85,14 @@ async fn aborted_future_1() {
     .expect("Mutex is locked");
 }
 
-#[tokio::test]
 /// This test is similar to `aborted_future_1` but this time the
 /// aborted future is waiting for the lock.
+#[tokio::test]
+#[cfg(feature = "full")]
 async fn aborted_future_2() {
+    use std::time::Duration;
+    use tokio::time::timeout;
+
     let m1: Arc<Mutex<usize>> = Arc::new(Mutex::new(0));
     {
         // Lock mutex
@@ -106,15 +120,15 @@ fn try_lock_owned() {
     let m: Arc<Mutex<usize>> = Arc::new(Mutex::new(0));
     {
         let g1 = m.clone().try_lock_owned();
-        assert_eq!(g1.is_ok(), true);
+        assert!(g1.is_ok());
         let g2 = m.clone().try_lock_owned();
-        assert_eq!(g2.is_ok(), false);
+        assert!(g2.is_err());
     }
     let g3 = m.try_lock_owned();
-    assert_eq!(g3.is_ok(), true);
+    assert!(g3.is_ok());
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn debug_format() {
     let s = "debug";
     let m = Arc::new(Mutex::new(s.to_string()));
diff --git a/vendor/tokio/tests/sync_notify.rs b/vendor/tokio/tests/sync_notify.rs
index 6c6620b2f..aa58039fa 100644
--- a/vendor/tokio/tests/sync_notify.rs
+++ b/vendor/tokio/tests/sync_notify.rs
@@ -1,5 +1,8 @@
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+#![cfg(feature = "sync")]
+
+#[cfg(tokio_wasm_not_wasi)]
+use wasm_bindgen_test::wasm_bindgen_test as test;
 
 use tokio::sync::Notify;
 use tokio_test::task::spawn;
@@ -151,3 +154,74 @@ fn notify_one_after_dropped_all() {
 
     assert_ready!(notified2.poll());
 }
+
+#[test]
+fn test_notify_one_not_enabled() {
+    let notify = Notify::new();
+    let mut future = spawn(notify.notified());
+
+    notify.notify_one();
+    assert_ready!(future.poll());
+}
+
+#[test]
+fn test_notify_one_after_enable() {
+    let notify = Notify::new();
+    let mut future = spawn(notify.notified());
+
+    future.enter(|_, fut| assert!(!fut.enable()));
+
+    notify.notify_one();
+    assert_ready!(future.poll());
+    future.enter(|_, fut| assert!(fut.enable()));
+}
+
+#[test]
+fn test_poll_after_enable() {
+    let notify = Notify::new();
+    let mut future = spawn(notify.notified());
+
+    future.enter(|_, fut| assert!(!fut.enable()));
+    assert_pending!(future.poll());
+}
+
+#[test]
+fn test_enable_after_poll() {
+    let notify = Notify::new();
+    let mut future = spawn(notify.notified());
+
+    assert_pending!(future.poll());
+    future.enter(|_, fut| assert!(!fut.enable()));
+}
+
+#[test]
+fn test_enable_consumes_permit() {
+    let notify = Notify::new();
+
+    // Add a permit.
+    notify.notify_one();
+
+    let mut future1 = spawn(notify.notified());
+    future1.enter(|_, fut| assert!(fut.enable()));
+
+    let mut future2 = spawn(notify.notified());
+    future2.enter(|_, fut| assert!(!fut.enable()));
+}
+
+#[test]
+fn test_waker_update() {
+    use futures::task::noop_waker;
+    use std::future::Future;
+    use std::task::Context;
+
+    let notify = Notify::new();
+    let mut future = spawn(notify.notified());
+
+    let noop = noop_waker();
+    future.enter(|_, fut| assert_pending!(fut.poll(&mut Context::from_waker(&noop))));
+
+    assert_pending!(future.poll());
+    notify.notify_one();
+
+    assert!(future.is_woken());
+}
diff --git a/vendor/tokio/tests/sync_once_cell.rs b/vendor/tokio/tests/sync_once_cell.rs
index 18eaf9382..38dfa7ca0 100644
--- a/vendor/tokio/tests/sync_once_cell.rs
+++ b/vendor/tokio/tests/sync_once_cell.rs
@@ -4,178 +4,7 @@
 use std::mem;
 use std::ops::Drop;
 use std::sync::atomic::{AtomicU32, Ordering};
-use std::time::Duration;
-use tokio::runtime;
-use tokio::sync::{OnceCell, SetError};
-use tokio::time;
-
-async fn func1() -> u32 {
-    5
-}
-
-async fn func2() -> u32 {
-    time::sleep(Duration::from_millis(1)).await;
-    10
-}
-
-async fn func_err() -> Result<u32, ()> {
-    Err(())
-}
-
-async fn func_ok() -> Result<u32, ()> {
-    Ok(10)
-}
-
-async fn func_panic() -> u32 {
-    time::sleep(Duration::from_millis(1)).await;
-    panic!();
-}
-
-async fn sleep_and_set() -> u32 {
-    // Simulate sleep by pausing time and waiting for another thread to
-    // resume clock when calling `set`, then finding the cell being initialized
-    // by this call
-    time::sleep(Duration::from_millis(2)).await;
-    5
-}
-
-async fn advance_time_and_set(cell: &'static OnceCell<u32>, v: u32) -> Result<(), SetError<u32>> {
-    time::advance(Duration::from_millis(1)).await;
-    cell.set(v)
-}
-
-#[test]
-fn get_or_init() {
-    let rt = runtime::Builder::new_current_thread()
-        .enable_time()
-        .start_paused(true)
-        .build()
-        .unwrap();
-
-    static ONCE: OnceCell<u32> = OnceCell::const_new();
-
-    rt.block_on(async {
-        let handle1 = rt.spawn(async { ONCE.get_or_init(func1).await });
-        let handle2 = rt.spawn(async { ONCE.get_or_init(func2).await });
-
-        time::advance(Duration::from_millis(1)).await;
-        time::resume();
-
-        let result1 = handle1.await.unwrap();
-        let result2 = handle2.await.unwrap();
-
-        assert_eq!(*result1, 5);
-        assert_eq!(*result2, 5);
-    });
-}
-
-#[test]
-fn get_or_init_panic() {
-    let rt = runtime::Builder::new_current_thread()
-        .enable_time()
-        .build()
-        .unwrap();
-
-    static ONCE: OnceCell<u32> = OnceCell::const_new();
-
-    rt.block_on(async {
-        time::pause();
-
-        let handle1 = rt.spawn(async { ONCE.get_or_init(func1).await });
-        let handle2 = rt.spawn(async { ONCE.get_or_init(func_panic).await });
-
-        time::advance(Duration::from_millis(1)).await;
-
-        let result1 = handle1.await.unwrap();
-        let result2 = handle2.await.unwrap();
-
-        assert_eq!(*result1, 5);
-        assert_eq!(*result2, 5);
-    });
-}
-
-#[test]
-fn set_and_get() {
-    let rt = runtime::Builder::new_current_thread()
-        .enable_time()
-        .build()
-        .unwrap();
-
-    static ONCE: OnceCell<u32> = OnceCell::const_new();
-
-    rt.block_on(async {
-        let _ = rt.spawn(async { ONCE.set(5) }).await;
-        let value = ONCE.get().unwrap();
-        assert_eq!(*value, 5);
-    });
-}
-
-#[test]
-fn get_uninit() {
-    static ONCE: OnceCell<u32> = OnceCell::const_new();
-    let uninit = ONCE.get();
-    assert!(uninit.is_none());
-}
-
-#[test]
-fn set_twice() {
-    static ONCE: OnceCell<u32> = OnceCell::const_new();
-
-    let first = ONCE.set(5);
-    assert_eq!(first, Ok(()));
-    let second = ONCE.set(6);
-    assert!(second.err().unwrap().is_already_init_err());
-}
-
-#[test]
-fn set_while_initializing() {
-    let rt = runtime::Builder::new_current_thread()
-        .enable_time()
-        .build()
-        .unwrap();
-
-    static ONCE: OnceCell<u32> = OnceCell::const_new();
-
-    rt.block_on(async {
-        time::pause();
-
-        let handle1 = rt.spawn(async { ONCE.get_or_init(sleep_and_set).await });
-        let handle2 = rt.spawn(async { advance_time_and_set(&ONCE, 10).await });
-
-        time::advance(Duration::from_millis(2)).await;
-
-        let result1 = handle1.await.unwrap();
-        let result2 = handle2.await.unwrap();
-
-        assert_eq!(*result1, 5);
-        assert!(result2.err().unwrap().is_initializing_err());
-    });
-}
-
-#[test]
-fn get_or_try_init() {
-    let rt = runtime::Builder::new_current_thread()
-        .enable_time()
-        .start_paused(true)
-        .build()
-        .unwrap();
-
-    static ONCE: OnceCell<u32> = OnceCell::const_new();
-
-    rt.block_on(async {
-        let handle1 = rt.spawn(async { ONCE.get_or_try_init(func_err).await });
-        let handle2 = rt.spawn(async { ONCE.get_or_try_init(func_ok).await });
-
-        time::advance(Duration::from_millis(1)).await;
-        time::resume();
-
-        let result1 = handle1.await.unwrap();
-        assert!(result1.is_err());
-
-        let result2 = handle2.await.unwrap();
-        assert_eq!(*result2.unwrap(), 10);
-    });
-}
+use tokio::sync::OnceCell;
 
 #[test]
 fn drop_cell() {
@@ -272,3 +101,185 @@ fn from() {
     let cell = OnceCell::from(2);
     assert_eq!(*cell.get().unwrap(), 2);
 }
+
+#[cfg(feature = "parking_lot")]
+mod parking_lot {
+    use super::*;
+
+    use tokio::runtime;
+    use tokio::sync::SetError;
+    use tokio::time;
+
+    use std::time::Duration;
+
+    async fn func1() -> u32 {
+        5
+    }
+
+    async fn func2() -> u32 {
+        time::sleep(Duration::from_millis(1)).await;
+        10
+    }
+
+    async fn func_err() -> Result<u32, ()> {
+        Err(())
+    }
+
+    async fn func_ok() -> Result<u32, ()> {
+        Ok(10)
+    }
+
+    async fn func_panic() -> u32 {
+        time::sleep(Duration::from_millis(1)).await;
+        panic!();
+    }
+
+    async fn sleep_and_set() -> u32 {
+        // Simulate sleep by pausing time and waiting for another thread to
+        // resume clock when calling `set`, then finding the cell being initialized
+        // by this call
+        time::sleep(Duration::from_millis(2)).await;
+        5
+    }
+
+    async fn advance_time_and_set(
+        cell: &'static OnceCell<u32>,
+        v: u32,
+    ) -> Result<(), SetError<u32>> {
+        time::advance(Duration::from_millis(1)).await;
+        cell.set(v)
+    }
+
+    #[test]
+    fn get_or_init() {
+        let rt = runtime::Builder::new_current_thread()
+            .enable_time()
+            .start_paused(true)
+            .build()
+            .unwrap();
+
+        static ONCE: OnceCell<u32> = OnceCell::const_new();
+
+        rt.block_on(async {
+            let handle1 = rt.spawn(async { ONCE.get_or_init(func1).await });
+            let handle2 = rt.spawn(async { ONCE.get_or_init(func2).await });
+
+            time::advance(Duration::from_millis(1)).await;
+            time::resume();
+
+            let result1 = handle1.await.unwrap();
+            let result2 = handle2.await.unwrap();
+
+            assert_eq!(*result1, 5);
+            assert_eq!(*result2, 5);
+        });
+    }
+
+    #[test]
+    fn get_or_init_panic() {
+        let rt = runtime::Builder::new_current_thread()
+            .enable_time()
+            .build()
+            .unwrap();
+
+        static ONCE: OnceCell<u32> = OnceCell::const_new();
+
+        rt.block_on(async {
+            time::pause();
+
+            let handle1 = rt.spawn(async { ONCE.get_or_init(func1).await });
+            let handle2 = rt.spawn(async { ONCE.get_or_init(func_panic).await });
+
+            time::advance(Duration::from_millis(1)).await;
+
+            let result1 = handle1.await.unwrap();
+            let result2 = handle2.await.unwrap();
+
+            assert_eq!(*result1, 5);
+            assert_eq!(*result2, 5);
+        });
+    }
+
+    #[test]
+    fn set_and_get() {
+        let rt = runtime::Builder::new_current_thread()
+            .enable_time()
+            .build()
+            .unwrap();
+
+        static ONCE: OnceCell<u32> = OnceCell::const_new();
+
+        rt.block_on(async {
+            let _ = rt.spawn(async { ONCE.set(5) }).await;
+            let value = ONCE.get().unwrap();
+            assert_eq!(*value, 5);
+        });
+    }
+
+    #[test]
+    fn get_uninit() {
+        static ONCE: OnceCell<u32> = OnceCell::const_new();
+        let uninit = ONCE.get();
+        assert!(uninit.is_none());
+    }
+
+    #[test]
+    fn set_twice() {
+        static ONCE: OnceCell<u32> = OnceCell::const_new();
+
+        let first = ONCE.set(5);
+        assert_eq!(first, Ok(()));
+        let second = ONCE.set(6);
+        assert!(second.err().unwrap().is_already_init_err());
+    }
+
+    #[test]
+    fn set_while_initializing() {
+        let rt = runtime::Builder::new_current_thread()
+            .enable_time()
+            .build()
+            .unwrap();
+
+        static ONCE: OnceCell<u32> = OnceCell::const_new();
+
+        rt.block_on(async {
+            time::pause();
+
+            let handle1 = rt.spawn(async { ONCE.get_or_init(sleep_and_set).await });
+            let handle2 = rt.spawn(async { advance_time_and_set(&ONCE, 10).await });
+
+            time::advance(Duration::from_millis(2)).await;
+
+            let result1 = handle1.await.unwrap();
+            let result2 = handle2.await.unwrap();
+
+            assert_eq!(*result1, 5);
+            assert!(result2.err().unwrap().is_initializing_err());
+        });
+    }
+
+    #[test]
+    fn get_or_try_init() {
+        let rt = runtime::Builder::new_current_thread()
+            .enable_time()
+            .start_paused(true)
+            .build()
+            .unwrap();
+
+        static ONCE: OnceCell<u32> = OnceCell::const_new();
+
+        rt.block_on(async {
+            let handle1 = rt.spawn(async { ONCE.get_or_try_init(func_err).await });
+            let handle2 = rt.spawn(async { ONCE.get_or_try_init(func_ok).await });
+
+            time::advance(Duration::from_millis(1)).await;
+            time::resume();
+
+            let result1 = handle1.await.unwrap();
+            assert!(result1.is_err());
+
+            let result2 = handle2.await.unwrap();
+            assert_eq!(*result2.unwrap(), 10);
+        });
+    }
+}
diff --git a/vendor/tokio/tests/sync_oneshot.rs b/vendor/tokio/tests/sync_oneshot.rs
index 1aab810e1..15b692370 100644
--- a/vendor/tokio/tests/sync_oneshot.rs
+++ b/vendor/tokio/tests/sync_oneshot.rs
@@ -1,5 +1,13 @@
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+#![cfg(feature = "sync")]
+
+#[cfg(tokio_wasm_not_wasi)]
+use wasm_bindgen_test::wasm_bindgen_test as test;
+#[cfg(tokio_wasm_not_wasi)]
+use wasm_bindgen_test::wasm_bindgen_test as maybe_tokio_test;
+
+#[cfg(not(tokio_wasm_not_wasi))]
+use tokio::test as maybe_tokio_test;
 
 use tokio::sync::oneshot;
 use tokio::sync::oneshot::error::TryRecvError;
@@ -40,7 +48,7 @@ fn send_recv() {
     assert_eq!(val, 1);
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn async_send_recv() {
     let (tx, rx) = oneshot::channel();
 
@@ -86,6 +94,7 @@ fn close_rx() {
 }
 
 #[tokio::test]
+#[cfg(feature = "full")]
 async fn async_rx_closed() {
     let (mut tx, rx) = oneshot::channel::<()>();
 
@@ -170,6 +179,7 @@ fn explicit_close_try_recv() {
 
 #[test]
 #[should_panic]
+#[cfg(not(tokio_wasm))] // wasm currently doesn't support unwinding
 fn close_try_recv_poll() {
     let (_tx, rx) = oneshot::channel::<i32>();
     let mut rx = task::spawn(rx);
@@ -203,6 +213,18 @@ fn try_recv_after_completion() {
 }
 
 #[test]
+fn try_recv_after_completion_await() {
+    let (tx, rx) = oneshot::channel::<i32>();
+    let mut rx = task::spawn(rx);
+
+    tx.send(17).unwrap();
+
+    assert_eq!(Ok(17), assert_ready!(rx.poll()));
+    assert_eq!(Err(TryRecvError::Closed), rx.try_recv());
+    rx.close();
+}
+
+#[test]
 fn drops_tasks() {
     let (mut tx, mut rx) = oneshot::channel::<i32>();
     let mut tx_task = task::spawn(());
diff --git a/vendor/tokio/tests/sync_panic.rs b/vendor/tokio/tests/sync_panic.rs
new file mode 100644
index 000000000..6c2366499
--- /dev/null
+++ b/vendor/tokio/tests/sync_panic.rs
@@ -0,0 +1,197 @@
+#![warn(rust_2018_idioms)]
+#![cfg(all(feature = "full", not(tokio_wasi)))]
+
+use std::{error::Error, sync::Arc};
+use tokio::{
+    runtime::{Builder, Runtime},
+    sync::{broadcast, mpsc, oneshot, Mutex, RwLock, Semaphore},
+};
+
+mod support {
+    pub mod panic;
+}
+use support::panic::test_panic;
+
+#[test]
+fn broadcast_channel_panic_caller() -> Result<(), Box<dyn Error>> {
+    let panic_location_file = test_panic(|| {
+        let (_, _) = broadcast::channel::<u32>(0);
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+fn mutex_blocking_lock_panic_caller() -> Result<(), Box<dyn Error>> {
+    let panic_location_file = test_panic(|| {
+        let rt = current_thread();
+        rt.block_on(async {
+            let mutex = Mutex::new(5_u32);
+            let _g = mutex.blocking_lock();
+        });
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+fn oneshot_blocking_recv_panic_caller() -> Result<(), Box<dyn Error>> {
+    let panic_location_file = test_panic(|| {
+        let rt = current_thread();
+        rt.block_on(async {
+            let (_tx, rx) = oneshot::channel::<u8>();
+            let _ = rx.blocking_recv();
+        });
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+fn rwlock_with_max_readers_panic_caller() -> Result<(), Box<dyn Error>> {
+    let panic_location_file = test_panic(|| {
+        let _ = RwLock::<u8>::with_max_readers(0, (u32::MAX >> 3) + 1);
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+fn rwlock_blocking_read_panic_caller() -> Result<(), Box<dyn Error>> {
+    let panic_location_file = test_panic(|| {
+        let rt = current_thread();
+        rt.block_on(async {
+            let lock = RwLock::<u8>::new(0);
+            let _ = lock.blocking_read();
+        });
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+fn rwlock_blocking_write_panic_caller() -> Result<(), Box<dyn Error>> {
+    let panic_location_file = test_panic(|| {
+        let rt = current_thread();
+        rt.block_on(async {
+            let lock = RwLock::<u8>::new(0);
+            let _ = lock.blocking_write();
+        });
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+fn mpsc_bounded_channel_panic_caller() -> Result<(), Box<dyn Error>> {
+    let panic_location_file = test_panic(|| {
+        let (_, _) = mpsc::channel::<u8>(0);
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+fn mpsc_bounded_receiver_blocking_recv_panic_caller() -> Result<(), Box<dyn Error>> {
+    let panic_location_file = test_panic(|| {
+        let rt = current_thread();
+        let (_tx, mut rx) = mpsc::channel::<u8>(1);
+        rt.block_on(async {
+            let _ = rx.blocking_recv();
+        });
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+fn mpsc_bounded_sender_blocking_send_panic_caller() -> Result<(), Box<dyn Error>> {
+    let panic_location_file = test_panic(|| {
+        let rt = current_thread();
+        let (tx, _rx) = mpsc::channel::<u8>(1);
+        rt.block_on(async {
+            let _ = tx.blocking_send(3);
+        });
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+fn mpsc_unbounded_receiver_blocking_recv_panic_caller() -> Result<(), Box<dyn Error>> {
+    let panic_location_file = test_panic(|| {
+        let rt = current_thread();
+        let (_tx, mut rx) = mpsc::unbounded_channel::<u8>();
+        rt.block_on(async {
+            let _ = rx.blocking_recv();
+        });
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+fn semaphore_merge_unrelated_owned_permits() -> Result<(), Box<dyn Error>> {
+    let panic_location_file = test_panic(|| {
+        let sem1 = Arc::new(Semaphore::new(42));
+        let sem2 = Arc::new(Semaphore::new(42));
+        let mut p1 = sem1.try_acquire_owned().unwrap();
+        let p2 = sem2.try_acquire_owned().unwrap();
+        p1.merge(p2);
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+fn semaphore_merge_unrelated_permits() -> Result<(), Box<dyn Error>> {
+    let panic_location_file = test_panic(|| {
+        let sem1 = Semaphore::new(42);
+        let sem2 = Semaphore::new(42);
+        let mut p1 = sem1.try_acquire().unwrap();
+        let p2 = sem2.try_acquire().unwrap();
+        p1.merge(p2);
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+fn current_thread() -> Runtime {
+    Builder::new_current_thread().enable_all().build().unwrap()
+}
diff --git a/vendor/tokio/tests/sync_rwlock.rs b/vendor/tokio/tests/sync_rwlock.rs
index 7d05086bf..667f62172 100644
--- a/vendor/tokio/tests/sync_rwlock.rs
+++ b/vendor/tokio/tests/sync_rwlock.rs
@@ -1,13 +1,19 @@
 #![warn(rust_2018_idioms)]
+#![cfg(feature = "sync")]
+
+#[cfg(tokio_wasm_not_wasi)]
+use wasm_bindgen_test::wasm_bindgen_test as test;
+#[cfg(tokio_wasm_not_wasi)]
+use wasm_bindgen_test::wasm_bindgen_test as maybe_tokio_test;
+
+#[cfg(not(tokio_wasm_not_wasi))]
+use tokio::test as maybe_tokio_test;
 
-use std::sync::Arc;
 use std::task::Poll;
 
 use futures::future::FutureExt;
-use futures::stream;
-use futures::stream::StreamExt;
 
-use tokio::sync::{Barrier, RwLock};
+use tokio::sync::{RwLock, RwLockWriteGuard};
 use tokio_test::task::spawn;
 use tokio_test::{assert_pending, assert_ready};
 
@@ -25,7 +31,7 @@ fn read_shared() {
     let mut t1 = spawn(rwlock.read());
     let _g1 = assert_ready!(t1.poll());
     let mut t2 = spawn(rwlock.read());
-    assert_ready!(t2.poll());
+    let _g2 = assert_ready!(t2.poll());
 }
 
 // When there is an active shared owner, exclusive access should not be possible
@@ -69,7 +75,7 @@ fn exhaust_reading() {
     let g2 = reads.pop().unwrap();
     drop(g2);
     assert!(t1.is_woken());
-    assert_ready!(t1.poll());
+    let _g1 = assert_ready!(t1.poll());
 }
 
 // When there is an active exclusive owner, subsequent exclusive access should not be possible
@@ -94,7 +100,7 @@ fn write_shared_drop() {
     assert_pending!(t2.poll());
     drop(g1);
     assert!(t2.is_woken());
-    assert_ready!(t2.poll());
+    let _g2 = assert_ready!(t2.poll());
 }
 
 // when there is an active shared owner, and exclusive access is triggered,
@@ -106,7 +112,7 @@ fn write_read_shared_pending() {
     let _g1 = assert_ready!(t1.poll());
 
     let mut t2 = spawn(rwlock.read());
-    assert_ready!(t2.poll());
+    let _g2 = assert_ready!(t2.poll());
 
     let mut t3 = spawn(rwlock.write());
     assert_pending!(t3.poll());
@@ -131,11 +137,11 @@ fn write_read_shared_drop_pending() {
     drop(t2);
 
     assert!(t3.is_woken());
-    assert_ready!(t3.poll());
+    let _t3 = assert_ready!(t3.poll());
 }
 
 // Acquire an RwLock nonexclusively by a single task
-#[tokio::test]
+#[maybe_tokio_test]
 async fn read_uncontested() {
     let rwlock = RwLock::new(100);
     let result = *rwlock.read().await;
@@ -144,7 +150,7 @@ async fn read_uncontested() {
 }
 
 // Acquire an uncontested RwLock in exclusive mode
-#[tokio::test]
+#[maybe_tokio_test]
 async fn write_uncontested() {
     let rwlock = RwLock::new(100);
     let mut result = rwlock.write().await;
@@ -153,7 +159,7 @@ async fn write_uncontested() {
 }
 
 // RwLocks should be acquired in the order that their Futures are waited upon.
-#[tokio::test]
+#[maybe_tokio_test]
 async fn write_order() {
     let rwlock = RwLock::<Vec<u32>>::new(vec![]);
     let fut2 = rwlock.write().map(|mut guard| guard.push(2));
@@ -166,8 +172,13 @@ async fn write_order() {
 }
 
 // A single RwLock is contested by tasks in multiple threads
+#[cfg(all(feature = "full", not(tokio_wasi)))] // Wasi doesn't support threads
 #[tokio::test(flavor = "multi_thread", worker_threads = 8)]
 async fn multithreaded() {
+    use futures::stream::{self, StreamExt};
+    use std::sync::Arc;
+    use tokio::sync::Barrier;
+
     let barrier = Arc::new(Barrier::new(5));
     let rwlock = Arc::new(RwLock::<u32>::new(0));
     let rwclone1 = rwlock.clone();
@@ -236,7 +247,7 @@ async fn multithreaded() {
     assert_eq!(*g, 17_000);
 }
 
-#[tokio::test]
+#[maybe_tokio_test]
 async fn try_write() {
     let lock = RwLock::new(0);
     let read_guard = lock.read().await;
@@ -268,3 +279,53 @@ fn try_read_try_write() {
 
     assert_eq!(*lock.try_read().unwrap(), 1515);
 }
+
+#[maybe_tokio_test]
+async fn downgrade_map() {
+    let lock = RwLock::new(0);
+    let write_guard = lock.write().await;
+    let mut read_t = spawn(lock.read());
+
+    // We can't create a read when a write exists
+    assert_pending!(read_t.poll());
+
+    // During the call to `f`, `read_t` doesn't have access yet.
+    let read_guard1 = RwLockWriteGuard::downgrade_map(write_guard, |v| {
+        assert_pending!(read_t.poll());
+        v
+    });
+
+    // After the downgrade, `read_t` got the lock
+    let read_guard2 = assert_ready!(read_t.poll());
+
+    // Ensure they're equal, as we return the original value
+    assert_eq!(&*read_guard1 as *const _, &*read_guard2 as *const _);
+}
+
+#[maybe_tokio_test]
+async fn try_downgrade_map() {
+    let lock = RwLock::new(0);
+    let write_guard = lock.write().await;
+    let mut read_t = spawn(lock.read());
+
+    // We can't create a read when a write exists
+    assert_pending!(read_t.poll());
+
+    // During the call to `f`, `read_t` doesn't have access yet.
+    let write_guard = RwLockWriteGuard::try_downgrade_map(write_guard, |_| {
+        assert_pending!(read_t.poll());
+        None::<&()>
+    })
+    .expect_err("downgrade didn't fail");
+
+    // After `f` returns `None`, `read_t` doesn't have access
+    assert_pending!(read_t.poll());
+
+    // After `f` returns `Some`, `read_t` does have access
+    let read_guard1 = RwLockWriteGuard::try_downgrade_map(write_guard, |v| Some(v))
+        .expect("downgrade didn't succeed");
+    let read_guard2 = assert_ready!(read_t.poll());
+
+    // Ensure they're equal, as we return the original value
+    assert_eq!(&*read_guard1 as *const _, &*read_guard2 as *const _);
+}
diff --git a/vendor/tokio/tests/sync_semaphore.rs b/vendor/tokio/tests/sync_semaphore.rs
index a33b878b3..3d47ed0ed 100644
--- a/vendor/tokio/tests/sync_semaphore.rs
+++ b/vendor/tokio/tests/sync_semaphore.rs
@@ -1,4 +1,7 @@
-#![cfg(feature = "full")]
+#![cfg(feature = "sync")]
+
+#[cfg(tokio_wasm_not_wasi)]
+use wasm_bindgen_test::wasm_bindgen_test as test;
 
 use std::sync::Arc;
 use tokio::sync::Semaphore;
@@ -23,6 +26,7 @@ fn try_acquire() {
 }
 
 #[tokio::test]
+#[cfg(feature = "full")]
 async fn acquire() {
     let sem = Arc::new(Semaphore::new(1));
     let p1 = sem.try_acquire().unwrap();
@@ -35,6 +39,7 @@ async fn acquire() {
 }
 
 #[tokio::test]
+#[cfg(feature = "full")]
 async fn add_permits() {
     let sem = Arc::new(Semaphore::new(0));
     let sem_clone = sem.clone();
@@ -58,8 +63,34 @@ fn forget() {
     assert!(sem.try_acquire().is_err());
 }
 
+#[test]
+fn merge() {
+    let sem = Arc::new(Semaphore::new(3));
+    {
+        let mut p1 = sem.try_acquire().unwrap();
+        assert_eq!(sem.available_permits(), 2);
+        let p2 = sem.try_acquire_many(2).unwrap();
+        assert_eq!(sem.available_permits(), 0);
+        p1.merge(p2);
+        assert_eq!(sem.available_permits(), 0);
+    }
+    assert_eq!(sem.available_permits(), 3);
+}
+
+#[test]
+#[cfg(not(tokio_wasm))] // No stack unwinding on wasm targets
+#[should_panic]
+fn merge_unrelated_permits() {
+    let sem1 = Arc::new(Semaphore::new(3));
+    let sem2 = Arc::new(Semaphore::new(3));
+    let mut p1 = sem1.try_acquire().unwrap();
+    let p2 = sem2.try_acquire().unwrap();
+    p1.merge(p2);
+}
+
 #[tokio::test]
-async fn stresstest() {
+#[cfg(feature = "full")]
+async fn stress_test() {
     let sem = Arc::new(Semaphore::new(5));
     let mut join_handles = Vec::new();
     for _ in 0..1000 {
@@ -83,13 +114,37 @@ async fn stresstest() {
 #[test]
 fn add_max_amount_permits() {
     let s = tokio::sync::Semaphore::new(0);
-    s.add_permits(usize::MAX >> 3);
-    assert_eq!(s.available_permits(), usize::MAX >> 3);
+    s.add_permits(tokio::sync::Semaphore::MAX_PERMITS);
+    assert_eq!(s.available_permits(), tokio::sync::Semaphore::MAX_PERMITS);
 }
 
+#[cfg(not(tokio_wasm))] // wasm currently doesn't support unwinding
 #[test]
 #[should_panic]
-fn add_more_than_max_amount_permits() {
+fn add_more_than_max_amount_permits1() {
     let s = tokio::sync::Semaphore::new(1);
-    s.add_permits(usize::MAX >> 3);
+    s.add_permits(tokio::sync::Semaphore::MAX_PERMITS);
+}
+
+#[cfg(not(tokio_wasm))] // wasm currently doesn't support unwinding
+#[test]
+#[should_panic]
+fn add_more_than_max_amount_permits2() {
+    let s = Semaphore::new(Semaphore::MAX_PERMITS - 1);
+    s.add_permits(1);
+    s.add_permits(1);
+}
+
+#[cfg(not(tokio_wasm))] // wasm currently doesn't support unwinding
+#[test]
+#[should_panic]
+fn panic_when_exceeds_maxpermits() {
+    let _ = Semaphore::new(Semaphore::MAX_PERMITS + 1);
+}
+
+#[test]
+fn no_panic_at_maxpermits() {
+    let _ = Semaphore::new(Semaphore::MAX_PERMITS);
+    let s = Semaphore::new(Semaphore::MAX_PERMITS - 1);
+    s.add_permits(1);
 }
diff --git a/vendor/tokio/tests/sync_semaphore_owned.rs b/vendor/tokio/tests/sync_semaphore_owned.rs
index 478c3a332..f69457647 100644
--- a/vendor/tokio/tests/sync_semaphore_owned.rs
+++ b/vendor/tokio/tests/sync_semaphore_owned.rs
@@ -1,4 +1,7 @@
-#![cfg(feature = "full")]
+#![cfg(feature = "sync")]
+
+#[cfg(tokio_wasm_not_wasi)]
+use wasm_bindgen_test::wasm_bindgen_test as test;
 
 use std::sync::Arc;
 use tokio::sync::Semaphore;
@@ -33,6 +36,7 @@ fn try_acquire_many() {
 }
 
 #[tokio::test]
+#[cfg(feature = "full")]
 async fn acquire() {
     let sem = Arc::new(Semaphore::new(1));
     let p1 = sem.clone().try_acquire_owned().unwrap();
@@ -45,6 +49,7 @@ async fn acquire() {
 }
 
 #[tokio::test]
+#[cfg(feature = "full")]
 async fn acquire_many() {
     let semaphore = Arc::new(Semaphore::new(42));
     let permit32 = semaphore.clone().try_acquire_many_owned(32).unwrap();
@@ -60,6 +65,7 @@ async fn acquire_many() {
 }
 
 #[tokio::test]
+#[cfg(feature = "full")]
 async fn add_permits() {
     let sem = Arc::new(Semaphore::new(0));
     let sem_clone = sem.clone();
@@ -83,8 +89,34 @@ fn forget() {
     assert!(sem.try_acquire_owned().is_err());
 }
 
+#[test]
+fn merge() {
+    let sem = Arc::new(Semaphore::new(3));
+    {
+        let mut p1 = sem.clone().try_acquire_owned().unwrap();
+        assert_eq!(sem.available_permits(), 2);
+        let p2 = sem.clone().try_acquire_many_owned(2).unwrap();
+        assert_eq!(sem.available_permits(), 0);
+        p1.merge(p2);
+        assert_eq!(sem.available_permits(), 0);
+    }
+    assert_eq!(sem.available_permits(), 3);
+}
+
+#[test]
+#[cfg(not(tokio_wasm))] // No stack unwinding on wasm targets
+#[should_panic]
+fn merge_unrelated_permits() {
+    let sem1 = Arc::new(Semaphore::new(3));
+    let sem2 = Arc::new(Semaphore::new(3));
+    let mut p1 = sem1.try_acquire_owned().unwrap();
+    let p2 = sem2.try_acquire_owned().unwrap();
+    p1.merge(p2)
+}
+
 #[tokio::test]
-async fn stresstest() {
+#[cfg(feature = "full")]
+async fn stress_test() {
     let sem = Arc::new(Semaphore::new(5));
     let mut join_handles = Vec::new();
     for _ in 0..1000 {
diff --git a/vendor/tokio/tests/sync_watch.rs b/vendor/tokio/tests/sync_watch.rs
index a2a276d8b..d4f8ce87d 100644
--- a/vendor/tokio/tests/sync_watch.rs
+++ b/vendor/tokio/tests/sync_watch.rs
@@ -1,6 +1,9 @@
 #![allow(clippy::cognitive_complexity)]
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+#![cfg(feature = "sync")]
+
+#[cfg(tokio_wasm_not_wasi)]
+use wasm_bindgen_test::wasm_bindgen_test as test;
 
 use tokio::sync::watch;
 use tokio_test::task::spawn;
@@ -174,15 +177,67 @@ fn poll_close() {
 fn borrow_and_update() {
     let (tx, mut rx) = watch::channel("one");
 
+    assert!(!rx.has_changed().unwrap());
+
     tx.send("two").unwrap();
+    assert!(rx.has_changed().unwrap());
     assert_ready!(spawn(rx.changed()).poll()).unwrap();
     assert_pending!(spawn(rx.changed()).poll());
+    assert!(!rx.has_changed().unwrap());
 
     tx.send("three").unwrap();
+    assert!(rx.has_changed().unwrap());
     assert_eq!(*rx.borrow_and_update(), "three");
     assert_pending!(spawn(rx.changed()).poll());
+    assert!(!rx.has_changed().unwrap());
 
     drop(tx);
     assert_eq!(*rx.borrow_and_update(), "three");
     assert_ready!(spawn(rx.changed()).poll()).unwrap_err();
+    assert!(rx.has_changed().is_err());
+}
+
+#[test]
+fn reopened_after_subscribe() {
+    let (tx, rx) = watch::channel("one");
+    assert!(!tx.is_closed());
+
+    drop(rx);
+    assert!(tx.is_closed());
+
+    let rx = tx.subscribe();
+    assert!(!tx.is_closed());
+
+    drop(rx);
+    assert!(tx.is_closed());
+}
+
+#[test]
+#[cfg(panic = "unwind")]
+#[cfg(not(tokio_wasm))] // wasm currently doesn't support unwinding
+fn send_modify_panic() {
+    let (tx, mut rx) = watch::channel("one");
+
+    tx.send_modify(|old| *old = "two");
+    assert_eq!(*rx.borrow_and_update(), "two");
+
+    let mut rx2 = rx.clone();
+    assert_eq!(*rx2.borrow_and_update(), "two");
+
+    let mut task = spawn(rx2.changed());
+
+    let result = std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| {
+        tx.send_modify(|old| {
+            *old = "panicked";
+            panic!();
+        })
+    }));
+    assert!(result.is_err());
+
+    assert_pending!(task.poll());
+    assert_eq!(*rx.borrow(), "panicked");
+
+    tx.send_modify(|old| *old = "three");
+    assert_ready_ok!(task.poll());
+    assert_eq!(*rx.borrow_and_update(), "three");
 }
diff --git a/vendor/tokio/tests/task_abort.rs b/vendor/tokio/tests/task_abort.rs
index cdaa405b8..492f8b551 100644
--- a/vendor/tokio/tests/task_abort.rs
+++ b/vendor/tokio/tests/task_abort.rs
@@ -1,9 +1,9 @@
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi doesn't support panic recovery
 
 use std::sync::Arc;
 use std::thread::sleep;
-use std::time::Duration;
+use tokio::time::Duration;
 
 use tokio::runtime::Builder;
 
@@ -26,13 +26,10 @@ fn test_abort_without_panic_3157() {
         .unwrap();
 
     rt.block_on(async move {
-        let handle = tokio::spawn(async move {
-            println!("task started");
-            tokio::time::sleep(std::time::Duration::new(100, 0)).await
-        });
+        let handle = tokio::spawn(async move { tokio::time::sleep(Duration::new(100, 0)).await });
 
         // wait for task to sleep.
-        tokio::time::sleep(std::time::Duration::new(1, 0)).await;
+        tokio::time::sleep(Duration::from_millis(10)).await;
 
         handle.abort();
         let _ = handle.await;
@@ -89,7 +86,7 @@ fn test_abort_without_panic_3662() {
         // Note: We do the following to trigger a deferred task cleanup.
         //
         // The relevant piece of code you want to look at is in:
-        // `Inner::block_on` of `basic_scheduler.rs`.
+        // `Inner::block_on` of `scheduler/current_thread.rs`.
         //
         // We cause the cleanup to happen by having a poll return Pending once
         // so that the scheduler can go into the "auxiliary tasks" mode, at
@@ -138,7 +135,7 @@ fn remote_abort_local_set_3929() {
     });
 
     let jh2 = std::thread::spawn(move || {
-        sleep(Duration::from_millis(50));
+        sleep(Duration::from_millis(10));
         jh.abort();
     });
 
@@ -159,18 +156,17 @@ fn test_abort_wakes_task_3964() {
         let handle = tokio::spawn(async move {
             // Make sure the Arc is moved into the task
             let _notify_dropped = notify_dropped;
-            println!("task started");
-            tokio::time::sleep(std::time::Duration::new(100, 0)).await
+            tokio::time::sleep(Duration::new(100, 0)).await
         });
 
         // wait for task to sleep.
-        tokio::time::sleep(std::time::Duration::from_millis(10)).await;
+        tokio::time::sleep(Duration::from_millis(10)).await;
 
         handle.abort();
         drop(handle);
 
         // wait for task to abort.
-        tokio::time::sleep(std::time::Duration::from_millis(10)).await;
+        tokio::time::sleep(Duration::from_millis(10)).await;
 
         // Check that the Arc has been dropped.
         assert!(weak_notify_dropped.upgrade().is_none());
@@ -187,18 +183,17 @@ fn test_abort_task_that_panics_on_drop_contained() {
         let handle = tokio::spawn(async move {
             // Make sure the Arc is moved into the task
             let _panic_dropped = PanicOnDrop;
-            println!("task started");
-            tokio::time::sleep(std::time::Duration::new(100, 0)).await
+            tokio::time::sleep(Duration::new(100, 0)).await
         });
 
         // wait for task to sleep.
-        tokio::time::sleep(std::time::Duration::from_millis(10)).await;
+        tokio::time::sleep(Duration::from_millis(10)).await;
 
         handle.abort();
         drop(handle);
 
         // wait for task to abort.
-        tokio::time::sleep(std::time::Duration::from_millis(10)).await;
+        tokio::time::sleep(Duration::from_millis(10)).await;
     });
 }
 
@@ -211,12 +206,11 @@ fn test_abort_task_that_panics_on_drop_returned() {
         let handle = tokio::spawn(async move {
             // Make sure the Arc is moved into the task
             let _panic_dropped = PanicOnDrop;
-            println!("task started");
-            tokio::time::sleep(std::time::Duration::new(100, 0)).await
+            tokio::time::sleep(Duration::new(100, 0)).await
         });
 
         // wait for task to sleep.
-        tokio::time::sleep(std::time::Duration::from_millis(10)).await;
+        tokio::time::sleep(Duration::from_millis(10)).await;
 
         handle.abort();
         assert!(handle.await.unwrap_err().is_panic());
diff --git a/vendor/tokio/tests/task_blocking.rs b/vendor/tokio/tests/task_blocking.rs
index ee7e78ad4..2999758ff 100644
--- a/vendor/tokio/tests/task_blocking.rs
+++ b/vendor/tokio/tests/task_blocking.rs
@@ -1,7 +1,7 @@
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi doesn't support threads
 
-use tokio::{runtime, task};
+use tokio::{runtime, task, time};
 use tokio_test::assert_ok;
 
 use std::thread;
@@ -77,7 +77,7 @@ async fn block_in_block() {
 
 #[tokio::test(flavor = "current_thread")]
 #[should_panic]
-async fn no_block_in_basic_scheduler() {
+async fn no_block_in_current_thread_scheduler() {
     task::block_in_place(|| {});
 }
 
@@ -91,7 +91,7 @@ fn yes_block_in_threaded_block_on() {
 
 #[test]
 #[should_panic]
-fn no_block_in_basic_block_on() {
+fn no_block_in_current_thread_block_on() {
     let rt = runtime::Builder::new_current_thread().build().unwrap();
     rt.block_on(async {
         task::block_in_place(|| {});
@@ -99,7 +99,7 @@ fn no_block_in_basic_block_on() {
 }
 
 #[test]
-fn can_enter_basic_rt_from_within_block_in_place() {
+fn can_enter_current_thread_rt_from_within_block_in_place() {
     let outer = tokio::runtime::Runtime::new().unwrap();
 
     outer.block_on(async {
@@ -226,3 +226,84 @@ fn coop_disabled_in_block_in_place_in_block_on() {
 
     done_rx.recv().unwrap().unwrap();
 }
+
+#[cfg(feature = "test-util")]
+#[tokio::test(start_paused = true)]
+async fn blocking_when_paused() {
+    // Do not auto-advance time when we have started a blocking task that has
+    // not yet finished.
+    time::timeout(
+        Duration::from_secs(3),
+        task::spawn_blocking(|| thread::sleep(Duration::from_millis(1))),
+    )
+    .await
+    .expect("timeout should not trigger")
+    .expect("blocking task should finish");
+
+    // Really: Do not auto-advance time, even if the timeout is short and the
+    // blocking task runs for longer than that. It doesn't matter: Tokio time
+    // is paused; system time is not.
+    time::timeout(
+        Duration::from_millis(1),
+        task::spawn_blocking(|| thread::sleep(Duration::from_millis(50))),
+    )
+    .await
+    .expect("timeout should not trigger")
+    .expect("blocking task should finish");
+}
+
+#[cfg(feature = "test-util")]
+#[tokio::test(start_paused = true)]
+async fn blocking_task_wakes_paused_runtime() {
+    let t0 = std::time::Instant::now();
+    time::timeout(
+        Duration::from_secs(15),
+        task::spawn_blocking(|| thread::sleep(Duration::from_millis(1))),
+    )
+    .await
+    .expect("timeout should not trigger")
+    .expect("blocking task should finish");
+    assert!(
+        t0.elapsed() < Duration::from_secs(10),
+        "completing a spawn_blocking should wake the scheduler if it's parked while time is paused"
+    );
+}
+
+#[cfg(feature = "test-util")]
+#[tokio::test(start_paused = true)]
+async fn unawaited_blocking_task_wakes_paused_runtime() {
+    let t0 = std::time::Instant::now();
+
+    // When this task finishes, time should auto-advance, even though the
+    // JoinHandle has not been awaited yet.
+    let a = task::spawn_blocking(|| {
+        thread::sleep(Duration::from_millis(1));
+    });
+
+    crate::time::sleep(Duration::from_secs(15)).await;
+    a.await.expect("blocking task should finish");
+    assert!(
+        t0.elapsed() < Duration::from_secs(10),
+        "completing a spawn_blocking should wake the scheduler if it's parked while time is paused"
+    );
+}
+
+#[cfg(feature = "test-util")]
+#[tokio::test(start_paused = true)]
+async fn panicking_blocking_task_wakes_paused_runtime() {
+    let t0 = std::time::Instant::now();
+    let result = time::timeout(
+        Duration::from_secs(15),
+        task::spawn_blocking(|| {
+            thread::sleep(Duration::from_millis(1));
+            panic!("blocking task panicked");
+        }),
+    )
+    .await
+    .expect("timeout should not trigger");
+    assert!(result.is_err(), "blocking task should have panicked");
+    assert!(
+        t0.elapsed() < Duration::from_secs(10),
+        "completing a spawn_blocking should wake the scheduler if it's parked while time is paused"
+    );
+}
diff --git a/vendor/tokio/tests/task_builder.rs b/vendor/tokio/tests/task_builder.rs
index 1499abf19..78329ff26 100644
--- a/vendor/tokio/tests/task_builder.rs
+++ b/vendor/tokio/tests/task_builder.rs
@@ -11,6 +11,7 @@ mod tests {
         let result = Builder::new()
             .name("name")
             .spawn(async { "task executed" })
+            .unwrap()
             .await;
 
         assert_eq!(result.unwrap(), "task executed");
@@ -21,6 +22,7 @@ mod tests {
         let result = Builder::new()
             .name("name")
             .spawn_blocking(|| "task executed")
+            .unwrap()
             .await;
 
         assert_eq!(result.unwrap(), "task executed");
@@ -34,6 +36,7 @@ mod tests {
                 Builder::new()
                     .name("name")
                     .spawn_local(async move { unsend_data })
+                    .unwrap()
                     .await
             })
             .await;
@@ -43,14 +46,20 @@ mod tests {
 
     #[test]
     async fn spawn_without_name() {
-        let result = Builder::new().spawn(async { "task executed" }).await;
+        let result = Builder::new()
+            .spawn(async { "task executed" })
+            .unwrap()
+            .await;
 
         assert_eq!(result.unwrap(), "task executed");
     }
 
     #[test]
     async fn spawn_blocking_without_name() {
-        let result = Builder::new().spawn_blocking(|| "task executed").await;
+        let result = Builder::new()
+            .spawn_blocking(|| "task executed")
+            .unwrap()
+            .await;
 
         assert_eq!(result.unwrap(), "task executed");
     }
@@ -59,7 +68,12 @@ mod tests {
     async fn spawn_local_without_name() {
         let unsend_data = Rc::new("task executed");
         let result = LocalSet::new()
-            .run_until(async move { Builder::new().spawn_local(async move { unsend_data }).await })
+            .run_until(async move {
+                Builder::new()
+                    .spawn_local(async move { unsend_data })
+                    .unwrap()
+                    .await
+            })
             .await;
 
         assert_eq!(*result.unwrap(), "task executed");
diff --git a/vendor/tokio/tests/task_id.rs b/vendor/tokio/tests/task_id.rs
new file mode 100644
index 000000000..d7b7c0cd8
--- /dev/null
+++ b/vendor/tokio/tests/task_id.rs
@@ -0,0 +1,303 @@
+#![warn(rust_2018_idioms)]
+#![allow(clippy::declare_interior_mutable_const)]
+#![cfg(all(feature = "full", tokio_unstable))]
+
+#[cfg(not(tokio_wasi))]
+use std::error::Error;
+use std::future::Future;
+use std::pin::Pin;
+use std::task::{Context, Poll};
+#[cfg(not(tokio_wasi))]
+use tokio::runtime::{Builder, Runtime};
+use tokio::sync::oneshot;
+use tokio::task::{self, Id, LocalSet};
+
+#[cfg(not(tokio_wasi))]
+mod support {
+    pub mod panic;
+}
+#[cfg(not(tokio_wasi))]
+use support::panic::test_panic;
+
+#[tokio::test(flavor = "current_thread")]
+async fn task_id_spawn() {
+    tokio::spawn(async { println!("task id: {}", task::id()) })
+        .await
+        .unwrap();
+}
+
+#[cfg(not(tokio_wasi))]
+#[tokio::test(flavor = "current_thread")]
+async fn task_id_spawn_blocking() {
+    task::spawn_blocking(|| println!("task id: {}", task::id()))
+        .await
+        .unwrap();
+}
+
+#[tokio::test(flavor = "current_thread")]
+async fn task_id_collision_current_thread() {
+    let handle1 = tokio::spawn(async { task::id() });
+    let handle2 = tokio::spawn(async { task::id() });
+
+    let (id1, id2) = tokio::join!(handle1, handle2);
+    assert_ne!(id1.unwrap(), id2.unwrap());
+}
+
+#[cfg(not(tokio_wasi))]
+#[tokio::test(flavor = "multi_thread")]
+async fn task_id_collision_multi_thread() {
+    let handle1 = tokio::spawn(async { task::id() });
+    let handle2 = tokio::spawn(async { task::id() });
+
+    let (id1, id2) = tokio::join!(handle1, handle2);
+    assert_ne!(id1.unwrap(), id2.unwrap());
+}
+
+#[tokio::test(flavor = "current_thread")]
+async fn task_ids_match_current_thread() {
+    let (tx, rx) = oneshot::channel();
+    let handle = tokio::spawn(async {
+        let id = rx.await.unwrap();
+        assert_eq!(id, task::id());
+    });
+    tx.send(handle.id()).unwrap();
+    handle.await.unwrap();
+}
+
+#[cfg(not(tokio_wasi))]
+#[tokio::test(flavor = "multi_thread")]
+async fn task_ids_match_multi_thread() {
+    let (tx, rx) = oneshot::channel();
+    let handle = tokio::spawn(async {
+        let id = rx.await.unwrap();
+        assert_eq!(id, task::id());
+    });
+    tx.send(handle.id()).unwrap();
+    handle.await.unwrap();
+}
+
+#[cfg(not(tokio_wasi))]
+#[tokio::test(flavor = "multi_thread")]
+async fn task_id_future_destructor_completion() {
+    struct MyFuture {
+        tx: Option<oneshot::Sender<Id>>,
+    }
+
+    impl Future for MyFuture {
+        type Output = ();
+
+        fn poll(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<()> {
+            Poll::Ready(())
+        }
+    }
+
+    impl Drop for MyFuture {
+        fn drop(&mut self) {
+            let _ = self.tx.take().unwrap().send(task::id());
+        }
+    }
+
+    let (tx, rx) = oneshot::channel();
+    let handle = tokio::spawn(MyFuture { tx: Some(tx) });
+    let id = handle.id();
+    handle.await.unwrap();
+    assert_eq!(rx.await.unwrap(), id);
+}
+
+#[cfg(not(tokio_wasi))]
+#[tokio::test(flavor = "multi_thread")]
+async fn task_id_future_destructor_abort() {
+    struct MyFuture {
+        tx: Option<oneshot::Sender<Id>>,
+    }
+
+    impl Future for MyFuture {
+        type Output = ();
+
+        fn poll(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<()> {
+            Poll::Pending
+        }
+    }
+    impl Drop for MyFuture {
+        fn drop(&mut self) {
+            let _ = self.tx.take().unwrap().send(task::id());
+        }
+    }
+
+    let (tx, rx) = oneshot::channel();
+    let handle = tokio::spawn(MyFuture { tx: Some(tx) });
+    let id = handle.id();
+    handle.abort();
+    assert!(handle.await.unwrap_err().is_cancelled());
+    assert_eq!(rx.await.unwrap(), id);
+}
+
+#[tokio::test(flavor = "current_thread")]
+async fn task_id_output_destructor_handle_dropped_before_completion() {
+    struct MyOutput {
+        tx: Option<oneshot::Sender<Id>>,
+    }
+
+    impl Drop for MyOutput {
+        fn drop(&mut self) {
+            let _ = self.tx.take().unwrap().send(task::id());
+        }
+    }
+
+    struct MyFuture {
+        tx: Option<oneshot::Sender<Id>>,
+    }
+
+    impl Future for MyFuture {
+        type Output = MyOutput;
+
+        fn poll(mut self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Self::Output> {
+            Poll::Ready(MyOutput { tx: self.tx.take() })
+        }
+    }
+
+    let (tx, mut rx) = oneshot::channel();
+    let handle = tokio::spawn(MyFuture { tx: Some(tx) });
+    let id = handle.id();
+    drop(handle);
+    assert!(rx.try_recv().is_err());
+    assert_eq!(rx.await.unwrap(), id);
+}
+
+#[tokio::test(flavor = "current_thread")]
+async fn task_id_output_destructor_handle_dropped_after_completion() {
+    struct MyOutput {
+        tx: Option<oneshot::Sender<Id>>,
+    }
+
+    impl Drop for MyOutput {
+        fn drop(&mut self) {
+            let _ = self.tx.take().unwrap().send(task::id());
+        }
+    }
+
+    struct MyFuture {
+        tx_output: Option<oneshot::Sender<Id>>,
+        tx_future: Option<oneshot::Sender<()>>,
+    }
+
+    impl Future for MyFuture {
+        type Output = MyOutput;
+
+        fn poll(mut self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Self::Output> {
+            let _ = self.tx_future.take().unwrap().send(());
+            Poll::Ready(MyOutput {
+                tx: self.tx_output.take(),
+            })
+        }
+    }
+
+    let (tx_output, mut rx_output) = oneshot::channel();
+    let (tx_future, rx_future) = oneshot::channel();
+    let handle = tokio::spawn(MyFuture {
+        tx_output: Some(tx_output),
+        tx_future: Some(tx_future),
+    });
+    let id = handle.id();
+    rx_future.await.unwrap();
+    assert!(rx_output.try_recv().is_err());
+    drop(handle);
+    assert_eq!(rx_output.await.unwrap(), id);
+}
+
+#[test]
+fn task_try_id_outside_task() {
+    assert_eq!(None, task::try_id());
+}
+
+#[cfg(not(tokio_wasi))]
+#[test]
+fn task_try_id_inside_block_on() {
+    let rt = Runtime::new().unwrap();
+    rt.block_on(async {
+        assert_eq!(None, task::try_id());
+    });
+}
+
+#[tokio::test(flavor = "current_thread")]
+async fn task_id_spawn_local() {
+    LocalSet::new()
+        .run_until(async {
+            task::spawn_local(async { println!("task id: {}", task::id()) })
+                .await
+                .unwrap();
+        })
+        .await
+}
+
+#[tokio::test(flavor = "current_thread")]
+async fn task_id_nested_spawn_local() {
+    LocalSet::new()
+        .run_until(async {
+            task::spawn_local(async {
+                let parent_id = task::id();
+                LocalSet::new()
+                    .run_until(async {
+                        task::spawn_local(async move {
+                            assert_ne!(parent_id, task::id());
+                        })
+                        .await
+                        .unwrap();
+                    })
+                    .await;
+                assert_eq!(parent_id, task::id());
+            })
+            .await
+            .unwrap();
+        })
+        .await;
+}
+
+#[cfg(not(tokio_wasi))]
+#[tokio::test(flavor = "multi_thread")]
+async fn task_id_block_in_place_block_on_spawn() {
+    task::spawn(async {
+        let parent_id = task::id();
+
+        task::block_in_place(move || {
+            let rt = Builder::new_current_thread().build().unwrap();
+            rt.block_on(rt.spawn(async move {
+                assert_ne!(parent_id, task::id());
+            }))
+            .unwrap();
+        });
+
+        assert_eq!(parent_id, task::id());
+    })
+    .await
+    .unwrap();
+}
+
+#[cfg(not(tokio_wasi))]
+#[test]
+fn task_id_outside_task_panic_caller() -> Result<(), Box<dyn Error>> {
+    let panic_location_file = test_panic(|| {
+        let _ = task::id();
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[cfg(not(tokio_wasi))]
+#[test]
+fn task_id_inside_block_on_panic_caller() -> Result<(), Box<dyn Error>> {
+    let panic_location_file = test_panic(|| {
+        let rt = Runtime::new().unwrap();
+        rt.block_on(async {
+            task::id();
+        });
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
diff --git a/vendor/tokio/tests/task_join_set.rs b/vendor/tokio/tests/task_join_set.rs
new file mode 100644
index 000000000..b1b6cf966
--- /dev/null
+++ b/vendor/tokio/tests/task_join_set.rs
@@ -0,0 +1,235 @@
+#![warn(rust_2018_idioms)]
+#![cfg(all(feature = "full"))]
+
+use tokio::sync::oneshot;
+use tokio::task::JoinSet;
+use tokio::time::Duration;
+
+fn rt() -> tokio::runtime::Runtime {
+    tokio::runtime::Builder::new_current_thread()
+        .build()
+        .unwrap()
+}
+
+#[tokio::test(start_paused = true)]
+async fn test_with_sleep() {
+    let mut set = JoinSet::new();
+
+    for i in 0..10 {
+        set.spawn(async move { i });
+        assert_eq!(set.len(), 1 + i);
+    }
+    set.detach_all();
+    assert_eq!(set.len(), 0);
+
+    assert!(matches!(set.join_next().await, None));
+
+    for i in 0..10 {
+        set.spawn(async move {
+            tokio::time::sleep(Duration::from_secs(i as u64)).await;
+            i
+        });
+        assert_eq!(set.len(), 1 + i);
+    }
+
+    let mut seen = [false; 10];
+    while let Some(res) = set.join_next().await.transpose().unwrap() {
+        seen[res] = true;
+    }
+
+    for was_seen in &seen {
+        assert!(was_seen);
+    }
+    assert!(matches!(set.join_next().await, None));
+
+    // Do it again.
+    for i in 0..10 {
+        set.spawn(async move {
+            tokio::time::sleep(Duration::from_secs(i as u64)).await;
+            i
+        });
+    }
+
+    let mut seen = [false; 10];
+    while let Some(res) = set.join_next().await.transpose().unwrap() {
+        seen[res] = true;
+    }
+
+    for was_seen in &seen {
+        assert!(was_seen);
+    }
+    assert!(matches!(set.join_next().await, None));
+}
+
+#[tokio::test]
+async fn test_abort_on_drop() {
+    let mut set = JoinSet::new();
+
+    let mut recvs = Vec::new();
+
+    for _ in 0..16 {
+        let (send, recv) = oneshot::channel::<()>();
+        recvs.push(recv);
+
+        set.spawn(async {
+            // This task will never complete on its own.
+            futures::future::pending::<()>().await;
+            drop(send);
+        });
+    }
+
+    drop(set);
+
+    for recv in recvs {
+        // The task is aborted soon and we will receive an error.
+        assert!(recv.await.is_err());
+    }
+}
+
+#[tokio::test]
+async fn alternating() {
+    let mut set = JoinSet::new();
+
+    assert_eq!(set.len(), 0);
+    set.spawn(async {});
+    assert_eq!(set.len(), 1);
+    set.spawn(async {});
+    assert_eq!(set.len(), 2);
+
+    for _ in 0..16 {
+        let () = set.join_next().await.unwrap().unwrap();
+        assert_eq!(set.len(), 1);
+        set.spawn(async {});
+        assert_eq!(set.len(), 2);
+    }
+}
+
+#[tokio::test(start_paused = true)]
+async fn abort_tasks() {
+    let mut set = JoinSet::new();
+    let mut num_canceled = 0;
+    let mut num_completed = 0;
+    for i in 0..16 {
+        let abort = set.spawn(async move {
+            tokio::time::sleep(Duration::from_secs(i as u64)).await;
+            i
+        });
+
+        if i % 2 != 0 {
+            // abort odd-numbered tasks.
+            abort.abort();
+        }
+    }
+    loop {
+        match set.join_next().await {
+            Some(Ok(res)) => {
+                num_completed += 1;
+                assert_eq!(res % 2, 0);
+            }
+            Some(Err(e)) => {
+                assert!(e.is_cancelled());
+                num_canceled += 1;
+            }
+            None => break,
+        }
+    }
+
+    assert_eq!(num_canceled, 8);
+    assert_eq!(num_completed, 8);
+}
+
+#[test]
+fn runtime_gone() {
+    let mut set = JoinSet::new();
+    {
+        let rt = rt();
+        set.spawn_on(async { 1 }, rt.handle());
+        drop(rt);
+    }
+
+    assert!(rt()
+        .block_on(set.join_next())
+        .unwrap()
+        .unwrap_err()
+        .is_cancelled());
+}
+
+#[tokio::test(start_paused = true)]
+async fn abort_all() {
+    let mut set: JoinSet<()> = JoinSet::new();
+
+    for _ in 0..5 {
+        set.spawn(futures::future::pending());
+    }
+    for _ in 0..5 {
+        set.spawn(async {
+            tokio::time::sleep(Duration::from_secs(1)).await;
+        });
+    }
+
+    // The join set will now have 5 pending tasks and 5 ready tasks.
+    tokio::time::sleep(Duration::from_secs(2)).await;
+
+    set.abort_all();
+    assert_eq!(set.len(), 10);
+
+    let mut count = 0;
+    while let Some(res) = set.join_next().await {
+        if let Err(err) = res {
+            assert!(err.is_cancelled());
+        }
+        count += 1;
+    }
+    assert_eq!(count, 10);
+    assert_eq!(set.len(), 0);
+}
+
+#[cfg(feature = "parking_lot")]
+mod parking_lot {
+    use super::*;
+
+    use futures::future::FutureExt;
+
+    // This ensures that `join_next` works correctly when the coop budget is
+    // exhausted.
+    #[tokio::test(flavor = "current_thread")]
+    async fn join_set_coop() {
+        // Large enough to trigger coop.
+        const TASK_NUM: u32 = 1000;
+
+        static SEM: tokio::sync::Semaphore = tokio::sync::Semaphore::const_new(0);
+
+        let mut set = JoinSet::new();
+
+        for _ in 0..TASK_NUM {
+            set.spawn(async {
+                SEM.add_permits(1);
+            });
+        }
+
+        // Wait for all tasks to complete.
+        //
+        // Since this is a `current_thread` runtime, there's no race condition
+        // between the last permit being added and the task completing.
+        let _ = SEM.acquire_many(TASK_NUM).await.unwrap();
+
+        let mut count = 0;
+        let mut coop_count = 0;
+        loop {
+            match set.join_next().now_or_never() {
+                Some(Some(Ok(()))) => {}
+                Some(Some(Err(err))) => panic!("failed: {}", err),
+                None => {
+                    coop_count += 1;
+                    tokio::task::yield_now().await;
+                    continue;
+                }
+                Some(None) => break,
+            }
+
+            count += 1;
+        }
+        assert!(coop_count >= 1);
+        assert_eq!(count, TASK_NUM);
+    }
+}
diff --git a/vendor/tokio/tests/task_local.rs b/vendor/tokio/tests/task_local.rs
index 998153242..949a40c2a 100644
--- a/vendor/tokio/tests/task_local.rs
+++ b/vendor/tokio/tests/task_local.rs
@@ -1,10 +1,17 @@
-tokio::task_local! {
-    static REQ_ID: u32;
-    pub static FOO: bool;
-}
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi doesn't support threads
+#![allow(clippy::declare_interior_mutable_const)]
+use std::future::Future;
+use std::pin::Pin;
+use std::task::{Context, Poll};
+use tokio::sync::oneshot;
 
 #[tokio::test(flavor = "multi_thread")]
 async fn local() {
+    tokio::task_local! {
+        static REQ_ID: u32;
+        pub static FOO: bool;
+    }
+
     let j1 = tokio::spawn(REQ_ID.scope(1, async move {
         assert_eq!(REQ_ID.get(), 1);
         assert_eq!(REQ_ID.get(), 1);
@@ -29,3 +36,84 @@ async fn local() {
     j2.await.unwrap();
     j3.await.unwrap();
 }
+
+#[tokio::test]
+async fn task_local_available_on_abort() {
+    tokio::task_local! {
+        static KEY: u32;
+    }
+
+    struct MyFuture {
+        tx_poll: Option<oneshot::Sender<()>>,
+        tx_drop: Option<oneshot::Sender<u32>>,
+    }
+    impl Future for MyFuture {
+        type Output = ();
+
+        fn poll(mut self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<()> {
+            if let Some(tx_poll) = self.tx_poll.take() {
+                let _ = tx_poll.send(());
+            }
+            Poll::Pending
+        }
+    }
+    impl Drop for MyFuture {
+        fn drop(&mut self) {
+            let _ = self.tx_drop.take().unwrap().send(KEY.get());
+        }
+    }
+
+    let (tx_drop, rx_drop) = oneshot::channel();
+    let (tx_poll, rx_poll) = oneshot::channel();
+
+    let h = tokio::spawn(KEY.scope(
+        42,
+        MyFuture {
+            tx_poll: Some(tx_poll),
+            tx_drop: Some(tx_drop),
+        },
+    ));
+
+    rx_poll.await.unwrap();
+    h.abort();
+    assert_eq!(rx_drop.await.unwrap(), 42);
+
+    let err = h.await.unwrap_err();
+    if !err.is_cancelled() {
+        if let Ok(panic) = err.try_into_panic() {
+            std::panic::resume_unwind(panic);
+        } else {
+            panic!();
+        }
+    }
+}
+
+#[tokio::test]
+async fn task_local_available_on_completion_drop() {
+    tokio::task_local! {
+        static KEY: u32;
+    }
+
+    struct MyFuture {
+        tx: Option<oneshot::Sender<u32>>,
+    }
+    impl Future for MyFuture {
+        type Output = ();
+
+        fn poll(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<()> {
+            Poll::Ready(())
+        }
+    }
+    impl Drop for MyFuture {
+        fn drop(&mut self) {
+            let _ = self.tx.take().unwrap().send(KEY.get());
+        }
+    }
+
+    let (tx, rx) = oneshot::channel();
+
+    let h = tokio::spawn(KEY.scope(42, MyFuture { tx: Some(tx) }));
+
+    assert_eq!(rx.await.unwrap(), 42);
+    h.await.unwrap();
+}
diff --git a/vendor/tokio/tests/task_local_set.rs b/vendor/tokio/tests/task_local_set.rs
index 58d510948..2da87f5ae 100644
--- a/vendor/tokio/tests/task_local_set.rs
+++ b/vendor/tokio/tests/task_local_set.rs
@@ -6,18 +6,23 @@ use futures::{
     FutureExt,
 };
 
-use tokio::runtime::{self, Runtime};
+use tokio::runtime;
 use tokio::sync::{mpsc, oneshot};
 use tokio::task::{self, LocalSet};
 use tokio::time;
 
+#[cfg(not(tokio_wasi))]
 use std::cell::Cell;
-use std::sync::atomic::Ordering::{self, SeqCst};
-use std::sync::atomic::{AtomicBool, AtomicUsize};
+use std::sync::atomic::AtomicBool;
+#[cfg(not(tokio_wasi))]
+use std::sync::atomic::AtomicUsize;
+use std::sync::atomic::Ordering;
+#[cfg(not(tokio_wasi))]
+use std::sync::atomic::Ordering::SeqCst;
 use std::time::Duration;
 
 #[tokio::test(flavor = "current_thread")]
-async fn local_basic_scheduler() {
+async fn local_current_thread_scheduler() {
     LocalSet::new()
         .run_until(async {
             task::spawn_local(async {}).await.unwrap();
@@ -25,6 +30,7 @@ async fn local_basic_scheduler() {
         .await;
 }
 
+#[cfg(not(tokio_wasi))] // Wasi doesn't support threads
 #[tokio::test(flavor = "multi_thread")]
 async fn local_threadpool() {
     thread_local! {
@@ -45,6 +51,7 @@ async fn local_threadpool() {
         .await;
 }
 
+#[cfg(not(tokio_wasi))] // Wasi doesn't support threads
 #[tokio::test(flavor = "multi_thread")]
 async fn localset_future_threadpool() {
     thread_local! {
@@ -60,6 +67,7 @@ async fn localset_future_threadpool() {
     local.await;
 }
 
+#[cfg(not(tokio_wasi))] // Wasi doesn't support threads
 #[tokio::test(flavor = "multi_thread")]
 async fn localset_future_timers() {
     static RAN1: AtomicBool = AtomicBool::new(false);
@@ -67,11 +75,11 @@ async fn localset_future_timers() {
 
     let local = LocalSet::new();
     local.spawn_local(async move {
-        time::sleep(Duration::from_millis(10)).await;
+        time::sleep(Duration::from_millis(5)).await;
         RAN1.store(true, Ordering::SeqCst);
     });
     local.spawn_local(async move {
-        time::sleep(Duration::from_millis(20)).await;
+        time::sleep(Duration::from_millis(10)).await;
         RAN2.store(true, Ordering::SeqCst);
     });
     local.await;
@@ -104,6 +112,7 @@ async fn localset_future_drives_all_local_futs() {
     assert!(RAN3.load(Ordering::SeqCst));
 }
 
+#[cfg(not(tokio_wasi))] // Wasi doesn't support threads
 #[tokio::test(flavor = "multi_thread")]
 async fn local_threadpool_timer() {
     // This test ensures that runtime services like the timer are properly
@@ -126,7 +135,23 @@ async fn local_threadpool_timer() {
         })
         .await;
 }
+#[test]
+fn enter_guard_spawn() {
+    let local = LocalSet::new();
+    let _guard = local.enter();
+    // Run the local task set.
+
+    let join = task::spawn_local(async { true });
+    let rt = runtime::Builder::new_current_thread()
+        .enable_all()
+        .build()
+        .unwrap();
+    local.block_on(&rt, async move {
+        assert!(join.await.unwrap());
+    });
+}
 
+#[cfg(not(tokio_wasi))] // Wasi doesn't support panic recovery
 #[test]
 // This will panic, since the thread that calls `block_on` cannot use
 // in-place blocking inside of `block_on`.
@@ -153,6 +178,7 @@ fn local_threadpool_blocking_in_place() {
     });
 }
 
+#[cfg(not(tokio_wasi))] // Wasi doesn't support threads
 #[tokio::test(flavor = "multi_thread")]
 async fn local_threadpool_blocking_run() {
     thread_local! {
@@ -181,6 +207,7 @@ async fn local_threadpool_blocking_run() {
         .await;
 }
 
+#[cfg(not(tokio_wasi))] // Wasi doesn't support threads
 #[tokio::test(flavor = "multi_thread")]
 async fn all_spawns_are_local() {
     use futures::future;
@@ -207,6 +234,7 @@ async fn all_spawns_are_local() {
         .await;
 }
 
+#[cfg(not(tokio_wasi))] // Wasi doesn't support threads
 #[tokio::test(flavor = "multi_thread")]
 async fn nested_spawn_is_local() {
     thread_local! {
@@ -242,6 +270,7 @@ async fn nested_spawn_is_local() {
         .await;
 }
 
+#[cfg(not(tokio_wasi))] // Wasi doesn't support threads
 #[test]
 fn join_local_future_elsewhere() {
     thread_local! {
@@ -255,14 +284,12 @@ fn join_local_future_elsewhere() {
     local.block_on(&rt, async move {
         let (tx, rx) = oneshot::channel();
         let join = task::spawn_local(async move {
-            println!("hello world running...");
             assert!(
                 ON_RT_THREAD.with(|cell| cell.get()),
                 "local task must run on local thread, no matter where it is awaited"
             );
             rx.await.unwrap();
 
-            println!("hello world task done");
             "hello world"
         });
         let join2 = task::spawn(async move {
@@ -272,16 +299,34 @@ fn join_local_future_elsewhere() {
             );
 
             tx.send(()).expect("task shouldn't have ended yet");
-            println!("waking up hello world...");
 
             join.await.expect("task should complete successfully");
-
-            println!("hello world task joined");
         });
         join2.await.unwrap()
     });
 }
 
+// Tests for <https://github.com/tokio-rs/tokio/issues/4973>
+#[cfg(not(tokio_wasi))] // Wasi doesn't support threads
+#[tokio::test(flavor = "multi_thread")]
+async fn localset_in_thread_local() {
+    thread_local! {
+        static LOCAL_SET: LocalSet = LocalSet::new();
+    }
+
+    // holds runtime thread until end of main fn.
+    let (_tx, rx) = oneshot::channel::<()>();
+    let handle = tokio::runtime::Handle::current();
+
+    std::thread::spawn(move || {
+        LOCAL_SET.with(|local_set| {
+            handle.block_on(local_set.run_until(async move {
+                let _ = rx.await;
+            }))
+        });
+    });
+}
+
 #[test]
 fn drop_cancels_tasks() {
     use std::rc::Rc;
@@ -299,9 +344,7 @@ fn drop_cancels_tasks() {
         let _rc2 = rc2;
 
         started_tx.send(()).unwrap();
-        loop {
-            time::sleep(Duration::from_secs(3600)).await;
-        }
+        futures::future::pending::<()>().await;
     });
 
     local.block_on(&rt, async {
@@ -347,9 +390,7 @@ fn with_timeout(timeout: Duration, f: impl FnOnce() + Send + 'static) {
         ),
         // Did the test thread panic? We'll find out for sure when we `join`
         // with it.
-        Err(RecvTimeoutError::Disconnected) => {
-            println!("done_rx dropped, did the test thread panic?");
-        }
+        Err(RecvTimeoutError::Disconnected) => {}
         // Test completed successfully!
         Ok(()) => {}
     }
@@ -357,6 +398,7 @@ fn with_timeout(timeout: Duration, f: impl FnOnce() + Send + 'static) {
     thread.join().expect("test thread should not panic!")
 }
 
+#[cfg_attr(tokio_wasi, ignore = "`unwrap()` in `with_timeout()` panics on Wasi")]
 #[test]
 fn drop_cancels_remote_tasks() {
     // This test reproduces issue #1885.
@@ -379,6 +421,10 @@ fn drop_cancels_remote_tasks() {
     });
 }
 
+#[cfg_attr(
+    tokio_wasi,
+    ignore = "FIXME: `task::spawn_local().await.unwrap()` panics on Wasi"
+)]
 #[test]
 fn local_tasks_wake_join_all() {
     // This test reproduces issue #2460.
@@ -400,13 +446,34 @@ fn local_tasks_wake_join_all() {
     });
 }
 
-#[tokio::test]
-async fn local_tasks_are_polled_after_tick() {
+#[cfg(not(tokio_wasi))] // Wasi doesn't support panic recovery
+#[test]
+fn local_tasks_are_polled_after_tick() {
+    // This test depends on timing, so we run it up to five times.
+    for _ in 0..4 {
+        let res = std::panic::catch_unwind(local_tasks_are_polled_after_tick_inner);
+        if res.is_ok() {
+            // success
+            return;
+        }
+    }
+
+    // Test failed 4 times. Try one more time without catching panics. If it
+    // fails again, the test fails.
+    local_tasks_are_polled_after_tick_inner();
+}
+
+#[cfg(not(tokio_wasi))] // Wasi doesn't support panic recovery
+#[tokio::main(flavor = "current_thread")]
+async fn local_tasks_are_polled_after_tick_inner() {
     // Reproduces issues #1899 and #1900
 
     static RX1: AtomicUsize = AtomicUsize::new(0);
     static RX2: AtomicUsize = AtomicUsize::new(0);
-    static EXPECTED: usize = 500;
+    const EXPECTED: usize = 500;
+
+    RX1.store(0, SeqCst);
+    RX2.store(0, SeqCst);
 
     let (tx, mut rx) = mpsc::unbounded_channel();
 
@@ -416,7 +483,7 @@ async fn local_tasks_are_polled_after_tick() {
         .run_until(async {
             let task2 = task::spawn(async move {
                 // Wait a bit
-                time::sleep(Duration::from_millis(100)).await;
+                time::sleep(Duration::from_millis(10)).await;
 
                 let mut oneshots = Vec::with_capacity(EXPECTED);
 
@@ -427,18 +494,21 @@ async fn local_tasks_are_polled_after_tick() {
                     tx.send(oneshot_rx).unwrap();
                 }
 
-                time::sleep(Duration::from_millis(100)).await;
+                time::sleep(Duration::from_millis(10)).await;
 
                 for tx in oneshots.drain(..) {
                     tx.send(()).unwrap();
                 }
 
-                time::sleep(Duration::from_millis(300)).await;
-                let rx1 = RX1.load(SeqCst);
-                let rx2 = RX2.load(SeqCst);
-                println!("EXPECT = {}; RX1 = {}; RX2 = {}", EXPECTED, rx1, rx2);
-                assert_eq!(EXPECTED, rx1);
-                assert_eq!(EXPECTED, rx2);
+                loop {
+                    time::sleep(Duration::from_millis(20)).await;
+                    let rx1 = RX1.load(SeqCst);
+                    let rx2 = RX2.load(SeqCst);
+
+                    if rx1 == EXPECTED && rx2 == EXPECTED {
+                        break;
+                    }
+                }
             });
 
             while let Some(oneshot) = rx.recv().await {
@@ -500,7 +570,122 @@ async fn spawn_wakes_localset() {
     }
 }
 
-fn rt() -> Runtime {
+#[test]
+fn store_local_set_in_thread_local_with_runtime() {
+    use tokio::runtime::Runtime;
+
+    thread_local! {
+        static CURRENT: RtAndLocalSet = RtAndLocalSet::new();
+    }
+
+    struct RtAndLocalSet {
+        rt: Runtime,
+        local: LocalSet,
+    }
+
+    impl RtAndLocalSet {
+        fn new() -> RtAndLocalSet {
+            RtAndLocalSet {
+                rt: tokio::runtime::Builder::new_current_thread()
+                    .enable_all()
+                    .build()
+                    .unwrap(),
+                local: LocalSet::new(),
+            }
+        }
+
+        async fn inner_method(&self) {
+            self.local
+                .run_until(async move {
+                    tokio::task::spawn_local(async {});
+                })
+                .await
+        }
+
+        fn method(&self) {
+            self.rt.block_on(self.inner_method());
+        }
+    }
+
+    CURRENT.with(|f| {
+        f.method();
+    });
+}
+
+#[cfg(tokio_unstable)]
+mod unstable {
+    use tokio::runtime::UnhandledPanic;
+    use tokio::task::LocalSet;
+
+    #[tokio::test]
+    #[should_panic(
+        expected = "a spawned task panicked and the LocalSet is configured to shutdown on unhandled panic"
+    )]
+    async fn shutdown_on_panic() {
+        LocalSet::new()
+            .unhandled_panic(UnhandledPanic::ShutdownRuntime)
+            .run_until(async {
+                tokio::task::spawn_local(async {
+                    panic!("boom");
+                });
+
+                futures::future::pending::<()>().await;
+            })
+            .await;
+    }
+
+    // This test compares that, when the task driving `run_until` has already
+    // consumed budget, the `run_until` future has less budget than a "spawned"
+    // task.
+    //
+    // "Budget" is a fuzzy metric as the Tokio runtime is able to change values
+    // internally. This is why the test uses indirection to test this.
+    #[tokio::test]
+    async fn run_until_does_not_get_own_budget() {
+        // Consume some budget
+        tokio::task::consume_budget().await;
+
+        LocalSet::new()
+            .run_until(async {
+                let spawned = tokio::spawn(async {
+                    let mut spawned_n = 0;
+
+                    {
+                        let mut spawned = tokio_test::task::spawn(async {
+                            loop {
+                                spawned_n += 1;
+                                tokio::task::consume_budget().await;
+                            }
+                        });
+                        // Poll once
+                        assert!(!spawned.poll().is_ready());
+                    }
+
+                    spawned_n
+                });
+
+                let mut run_until_n = 0;
+                {
+                    let mut run_until = tokio_test::task::spawn(async {
+                        loop {
+                            run_until_n += 1;
+                            tokio::task::consume_budget().await;
+                        }
+                    });
+                    // Poll once
+                    assert!(!run_until.poll().is_ready());
+                }
+
+                let spawned_n = spawned.await.unwrap();
+                assert_ne!(spawned_n, 0);
+                assert_ne!(run_until_n, 0);
+                assert!(spawned_n > run_until_n);
+            })
+            .await
+    }
+}
+
+fn rt() -> runtime::Runtime {
     tokio::runtime::Builder::new_current_thread()
         .enable_all()
         .build()
diff --git a/vendor/tokio/tests/task_panic.rs b/vendor/tokio/tests/task_panic.rs
new file mode 100644
index 000000000..e4cedce27
--- /dev/null
+++ b/vendor/tokio/tests/task_panic.rs
@@ -0,0 +1,123 @@
+#![warn(rust_2018_idioms)]
+#![allow(clippy::declare_interior_mutable_const)]
+#![cfg(all(feature = "full", not(tokio_wasi)))]
+
+use futures::future;
+use std::error::Error;
+use tokio::runtime::Builder;
+use tokio::task::{self, block_in_place};
+
+mod support {
+    pub mod panic;
+}
+use support::panic::test_panic;
+
+#[test]
+fn block_in_place_panic_caller() -> Result<(), Box<dyn Error>> {
+    let panic_location_file = test_panic(|| {
+        let rt = Builder::new_current_thread().enable_all().build().unwrap();
+        rt.block_on(async {
+            block_in_place(|| {});
+        });
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+fn local_set_spawn_local_panic_caller() -> Result<(), Box<dyn Error>> {
+    let panic_location_file = test_panic(|| {
+        let _local = task::LocalSet::new();
+
+        let _ = task::spawn_local(async {});
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+fn local_set_block_on_panic_caller() -> Result<(), Box<dyn Error>> {
+    let panic_location_file = test_panic(|| {
+        let rt = Builder::new_current_thread().enable_all().build().unwrap();
+        let local = task::LocalSet::new();
+
+        rt.block_on(async {
+            local.block_on(&rt, future::pending::<()>());
+        });
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+fn spawn_panic_caller() -> Result<(), Box<dyn Error>> {
+    let panic_location_file = test_panic(|| {
+        tokio::spawn(future::pending::<()>());
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+fn local_key_sync_scope_panic_caller() -> Result<(), Box<dyn Error>> {
+    tokio::task_local! {
+        static NUMBER: u32;
+    }
+
+    let panic_location_file = test_panic(|| {
+        NUMBER.sync_scope(1, || {
+            NUMBER.with(|_| {
+                NUMBER.sync_scope(1, || {});
+            });
+        });
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+fn local_key_with_panic_caller() -> Result<(), Box<dyn Error>> {
+    tokio::task_local! {
+        static NUMBER: u32;
+    }
+
+    let panic_location_file = test_panic(|| {
+        NUMBER.with(|_| {});
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+fn local_key_get_panic_caller() -> Result<(), Box<dyn Error>> {
+    tokio::task_local! {
+        static NUMBER: u32;
+    }
+
+    let panic_location_file = test_panic(|| {
+        NUMBER.get();
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
diff --git a/vendor/tokio/tests/task_yield_now.rs b/vendor/tokio/tests/task_yield_now.rs
new file mode 100644
index 000000000..b16bca528
--- /dev/null
+++ b/vendor/tokio/tests/task_yield_now.rs
@@ -0,0 +1,16 @@
+#![cfg(all(feature = "full", tokio_unstable))]
+
+use tokio::task;
+use tokio_test::task::spawn;
+
+// `yield_now` is tested within the runtime in `rt_common`.
+#[test]
+fn yield_now_outside_of_runtime() {
+    let mut task = spawn(async {
+        task::yield_now().await;
+    });
+
+    assert!(task.poll().is_pending());
+    assert!(task.is_woken());
+    assert!(task.poll().is_ready());
+}
diff --git a/vendor/tokio/tests/tcp_accept.rs b/vendor/tokio/tests/tcp_accept.rs
index 5ffb946f3..ba4a498d1 100644
--- a/vendor/tokio/tests/tcp_accept.rs
+++ b/vendor/tokio/tests/tcp_accept.rs
@@ -1,5 +1,5 @@
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi doesn't support bind
 
 use tokio::net::{TcpListener, TcpStream};
 use tokio::sync::{mpsc, oneshot};
diff --git a/vendor/tokio/tests/tcp_connect.rs b/vendor/tokio/tests/tcp_connect.rs
index cbe68fa27..f2384420e 100644
--- a/vendor/tokio/tests/tcp_connect.rs
+++ b/vendor/tokio/tests/tcp_connect.rs
@@ -1,5 +1,5 @@
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi doesn't support bind
 
 use tokio::net::{TcpListener, TcpStream};
 use tokio::sync::oneshot;
@@ -35,6 +35,7 @@ async fn connect_v4() {
 }
 
 #[tokio::test]
+#[cfg(not(tokio_no_ipv6))]
 async fn connect_v6() {
     let srv = assert_ok!(TcpListener::bind("[::1]:0").await);
     let addr = assert_ok!(srv.local_addr());
diff --git a/vendor/tokio/tests/tcp_echo.rs b/vendor/tokio/tests/tcp_echo.rs
index 5bb7ff0ac..f47d4ac18 100644
--- a/vendor/tokio/tests/tcp_echo.rs
+++ b/vendor/tokio/tests/tcp_echo.rs
@@ -1,5 +1,5 @@
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi doesn't support bind
 
 use tokio::io::{self, AsyncReadExt, AsyncWriteExt};
 use tokio::net::{TcpListener, TcpStream};
diff --git a/vendor/tokio/tests/tcp_into_split.rs b/vendor/tokio/tests/tcp_into_split.rs
index b4bb2eeb9..010984af8 100644
--- a/vendor/tokio/tests/tcp_into_split.rs
+++ b/vendor/tokio/tests/tcp_into_split.rs
@@ -1,5 +1,5 @@
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi doesn't support bind
 
 use std::io::{Error, ErrorKind, Result};
 use std::io::{Read, Write};
@@ -116,7 +116,7 @@ async fn drop_write() -> Result<()> {
 
     // drop it while the read is in progress
     std::thread::spawn(move || {
-        thread::sleep(std::time::Duration::from_millis(50));
+        thread::sleep(std::time::Duration::from_millis(10));
         drop(write_half);
     });
 
diff --git a/vendor/tokio/tests/tcp_into_std.rs b/vendor/tokio/tests/tcp_into_std.rs
index 4bf24c14d..320d9946e 100644
--- a/vendor/tokio/tests/tcp_into_std.rs
+++ b/vendor/tokio/tests/tcp_into_std.rs
@@ -1,5 +1,5 @@
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi doesn't support bind
 
 use std::io::Read;
 use std::io::Result;
diff --git a/vendor/tokio/tests/tcp_peek.rs b/vendor/tokio/tests/tcp_peek.rs
index aecc0ac19..a5fd6ba4f 100644
--- a/vendor/tokio/tests/tcp_peek.rs
+++ b/vendor/tokio/tests/tcp_peek.rs
@@ -1,5 +1,5 @@
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi doesn't support bind
 
 use tokio::io::AsyncReadExt;
 use tokio::net::TcpStream;
@@ -7,7 +7,7 @@ use tokio::net::TcpStream;
 use tokio_test::assert_ok;
 
 use std::thread;
-use std::{convert::TryInto, io::Write, net};
+use std::{io::Write, net};
 
 #[tokio::test]
 async fn peek() {
@@ -15,7 +15,7 @@ async fn peek() {
     let addr = listener.local_addr().unwrap();
     let t = thread::spawn(move || assert_ok!(listener.accept()).0);
 
-    let left = net::TcpStream::connect(&addr).unwrap();
+    let left = net::TcpStream::connect(addr).unwrap();
     let mut right = t.join().unwrap();
     let _ = right.write(&[1, 2, 3, 4]).unwrap();
 
diff --git a/vendor/tokio/tests/tcp_shutdown.rs b/vendor/tokio/tests/tcp_shutdown.rs
index 536a16130..1d477f37c 100644
--- a/vendor/tokio/tests/tcp_shutdown.rs
+++ b/vendor/tokio/tests/tcp_shutdown.rs
@@ -1,5 +1,5 @@
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi doesn't support bind
 
 use tokio::io::{self, AsyncReadExt, AsyncWriteExt};
 use tokio::net::{TcpListener, TcpStream};
diff --git a/vendor/tokio/tests/tcp_socket.rs b/vendor/tokio/tests/tcp_socket.rs
index 9258864d4..66309d304 100644
--- a/vendor/tokio/tests/tcp_socket.rs
+++ b/vendor/tokio/tests/tcp_socket.rs
@@ -1,6 +1,7 @@
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi doesn't support bind
 
+use std::time::Duration;
 use tokio::net::TcpSocket;
 use tokio_test::assert_ok;
 
@@ -23,6 +24,7 @@ async fn basic_usage_v4() {
 }
 
 #[tokio::test]
+#[cfg(not(tokio_no_ipv6))]
 async fn basic_usage_v6() {
     // Create server
     let addr = assert_ok!("[::1]:0".parse());
@@ -58,3 +60,16 @@ async fn bind_before_connect() {
     // Accept
     let _ = assert_ok!(srv.accept().await);
 }
+
+#[tokio::test]
+async fn basic_linger() {
+    // Create server
+    let addr = assert_ok!("127.0.0.1:0".parse());
+    let srv = assert_ok!(TcpSocket::new_v4());
+    assert_ok!(srv.bind(addr));
+
+    assert!(srv.linger().unwrap().is_none());
+
+    srv.set_linger(Some(Duration::new(0, 0))).unwrap();
+    assert_eq!(srv.linger().unwrap(), Some(Duration::new(0, 0)));
+}
diff --git a/vendor/tokio/tests/tcp_split.rs b/vendor/tokio/tests/tcp_split.rs
index 7171dac46..335b21f29 100644
--- a/vendor/tokio/tests/tcp_split.rs
+++ b/vendor/tokio/tests/tcp_split.rs
@@ -1,5 +1,5 @@
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi doesn't support bind
 
 use std::io::Result;
 use std::io::{Read, Write};
@@ -36,7 +36,7 @@ async fn split() -> Result<()> {
     assert_eq!(peek_len1, read_len);
     assert_eq!(&read_buf[..read_len], MSG);
 
-    write_half.write(MSG).await?;
+    assert_eq!(write_half.write(MSG).await?, MSG.len());
     handle.join().unwrap();
     Ok(())
 }
diff --git a/vendor/tokio/tests/tcp_stream.rs b/vendor/tokio/tests/tcp_stream.rs
index 0b5d12ae8..31fe3baa2 100644
--- a/vendor/tokio/tests/tcp_stream.rs
+++ b/vendor/tokio/tests/tcp_stream.rs
@@ -1,5 +1,5 @@
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi doesn't support bind
 
 use tokio::io::{AsyncReadExt, AsyncWriteExt, Interest};
 use tokio::net::{TcpListener, TcpStream};
@@ -254,30 +254,34 @@ async fn create_pair() -> (TcpStream, TcpStream) {
     (client, server)
 }
 
-fn read_until_pending(stream: &mut TcpStream) {
+fn read_until_pending(stream: &mut TcpStream) -> usize {
     let mut buf = vec![0u8; 1024 * 1024];
+    let mut total = 0;
     loop {
         match stream.try_read(&mut buf) {
-            Ok(_) => (),
+            Ok(n) => total += n,
             Err(err) => {
                 assert_eq!(err.kind(), io::ErrorKind::WouldBlock);
                 break;
             }
         }
     }
+    total
 }
 
-fn write_until_pending(stream: &mut TcpStream) {
+fn write_until_pending(stream: &mut TcpStream) -> usize {
     let buf = vec![0u8; 1024 * 1024];
+    let mut total = 0;
     loop {
         match stream.try_write(&buf) {
-            Ok(_) => (),
+            Ok(n) => total += n,
             Err(err) => {
                 assert_eq!(err.kind(), io::ErrorKind::WouldBlock);
                 break;
             }
         }
     }
+    total
 }
 
 #[tokio::test]
@@ -357,3 +361,40 @@ async fn try_read_buf() {
         }
     }
 }
+
+// read_closed is a best effort event, so test only for no false positives.
+#[tokio::test]
+async fn read_closed() {
+    let (client, mut server) = create_pair().await;
+
+    let mut ready_fut = task::spawn(client.ready(Interest::READABLE));
+    assert_pending!(ready_fut.poll());
+
+    assert_ok!(server.write_all(b"ping").await);
+
+    let ready_event = assert_ok!(ready_fut.await);
+
+    assert!(!ready_event.is_read_closed());
+}
+
+// write_closed is a best effort event, so test only for no false positives.
+#[tokio::test]
+async fn write_closed() {
+    let (mut client, mut server) = create_pair().await;
+
+    // Fill the write buffer.
+    let write_size = write_until_pending(&mut client);
+    let mut ready_fut = task::spawn(client.ready(Interest::WRITABLE));
+    assert_pending!(ready_fut.poll());
+
+    // Drain the socket to make client writable.
+    let mut read_size = 0;
+    while read_size < write_size {
+        server.readable().await.unwrap();
+        read_size += read_until_pending(&mut server);
+    }
+
+    let ready_event = assert_ok!(ready_fut.await);
+
+    assert!(!ready_event.is_write_closed());
+}
diff --git a/vendor/tokio/tests/time_interval.rs b/vendor/tokio/tests/time_interval.rs
index 5f7bf55f2..42285364a 100644
--- a/vendor/tokio/tests/time_interval.rs
+++ b/vendor/tokio/tests/time_interval.rs
@@ -1,10 +1,12 @@
 #![warn(rust_2018_idioms)]
 #![cfg(feature = "full")]
 
-use tokio::time::{self, Duration, Instant, MissedTickBehavior};
-use tokio_test::{assert_pending, assert_ready_eq, task};
+use std::pin::Pin;
+use std::task::{Context, Poll};
 
-use std::task::Poll;
+use futures::{Stream, StreamExt};
+use tokio::time::{self, Duration, Instant, Interval, MissedTickBehavior};
+use tokio_test::{assert_pending, assert_ready_eq, task};
 
 // Takes the `Interval` task, `start` variable, and optional time deltas
 // For each time delta, it polls the `Interval` and asserts that the result is
@@ -166,6 +168,42 @@ async fn skip() {
     check_interval_poll!(i, start, 1800);
 }
 
+#[tokio::test(start_paused = true)]
+async fn reset() {
+    let start = Instant::now();
+
+    // This is necessary because the timer is only so granular, and in order for
+    // all our ticks to resolve, the time needs to be 1ms ahead of what we
+    // expect, so that the runtime will see that it is time to resolve the timer
+    time::advance(ms(1)).await;
+
+    let mut i = task::spawn(time::interval_at(start, ms(300)));
+
+    check_interval_poll!(i, start, 0);
+
+    time::advance(ms(100)).await;
+    check_interval_poll!(i, start);
+
+    time::advance(ms(200)).await;
+    check_interval_poll!(i, start, 300);
+
+    time::advance(ms(100)).await;
+    check_interval_poll!(i, start);
+
+    i.reset();
+
+    time::advance(ms(250)).await;
+    check_interval_poll!(i, start);
+
+    time::advance(ms(50)).await;
+    // We add one because when using `reset` method, `Interval` adds the
+    // `period` from `Instant::now()`, which will always be off by one
+    check_interval_poll!(i, start, 701);
+
+    time::advance(ms(300)).await;
+    check_interval_poll!(i, start, 1001);
+}
+
 fn poll_next(interval: &mut task::Spawn<time::Interval>) -> Poll<Instant> {
     interval.enter(|cx, mut interval| interval.poll_tick(cx))
 }
@@ -173,3 +211,113 @@ fn poll_next(interval: &mut task::Spawn<time::Interval>) -> Poll<Instant> {
 fn ms(n: u64) -> Duration {
     Duration::from_millis(n)
 }
+
+/// Helper struct to test the [tokio::time::Interval::poll_tick()] method.
+///
+/// `poll_tick()` should register the waker in the context only if it returns
+/// `Poll::Pending`, not when returning `Poll::Ready`. This struct contains an
+/// interval timer and counts up on every tick when used as stream. When the
+/// counter is a multiple of four, it yields the current counter value.
+/// Depending on the value for `wake_on_pending`, it will reschedule itself when
+/// it returns `Poll::Pending` or not. When used with `wake_on_pending=false`,
+/// we expect that the stream stalls because the timer will **not** reschedule
+/// the next wake-up itself once it returned `Poll::Ready`.
+struct IntervalStreamer {
+    counter: u32,
+    timer: Interval,
+    wake_on_pending: bool,
+}
+
+impl Stream for IntervalStreamer {
+    type Item = u32;
+
+    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
+        let this = Pin::into_inner(self);
+
+        if this.counter > 12 {
+            return Poll::Ready(None);
+        }
+
+        match this.timer.poll_tick(cx) {
+            Poll::Pending => Poll::Pending,
+            Poll::Ready(_) => {
+                this.counter += 1;
+                if this.counter % 4 == 0 {
+                    Poll::Ready(Some(this.counter))
+                } else {
+                    if this.wake_on_pending {
+                        // Schedule this task for wake-up
+                        cx.waker().wake_by_ref();
+                    }
+                    Poll::Pending
+                }
+            }
+        }
+    }
+}
+
+#[tokio::test(start_paused = true)]
+async fn stream_with_interval_poll_tick_self_waking() {
+    let stream = IntervalStreamer {
+        counter: 0,
+        timer: tokio::time::interval(tokio::time::Duration::from_millis(10)),
+        wake_on_pending: true,
+    };
+
+    let (res_tx, mut res_rx) = tokio::sync::mpsc::channel(12);
+
+    // Wrap task in timeout so that it will finish eventually even if the stream
+    // stalls.
+    tokio::spawn(tokio::time::timeout(
+        tokio::time::Duration::from_millis(150),
+        async move {
+            tokio::pin!(stream);
+
+            while let Some(item) = stream.next().await {
+                res_tx.send(item).await.ok();
+            }
+        },
+    ));
+
+    let mut items = Vec::with_capacity(3);
+    while let Some(result) = res_rx.recv().await {
+        items.push(result);
+    }
+
+    // We expect the stream to yield normally and thus three items.
+    assert_eq!(items, vec![4, 8, 12]);
+}
+
+#[tokio::test(start_paused = true)]
+async fn stream_with_interval_poll_tick_no_waking() {
+    let stream = IntervalStreamer {
+        counter: 0,
+        timer: tokio::time::interval(tokio::time::Duration::from_millis(10)),
+        wake_on_pending: false,
+    };
+
+    let (res_tx, mut res_rx) = tokio::sync::mpsc::channel(12);
+
+    // Wrap task in timeout so that it will finish eventually even if the stream
+    // stalls.
+    tokio::spawn(tokio::time::timeout(
+        tokio::time::Duration::from_millis(150),
+        async move {
+            tokio::pin!(stream);
+
+            while let Some(item) = stream.next().await {
+                res_tx.send(item).await.ok();
+            }
+        },
+    ));
+
+    let mut items = Vec::with_capacity(0);
+    while let Some(result) = res_rx.recv().await {
+        items.push(result);
+    }
+
+    // We expect the stream to stall because it does not reschedule itself on
+    // `Poll::Pending` and neither does [tokio::time::Interval] reschedule the
+    // task when returning `Poll::Ready`.
+    assert_eq!(items, vec![]);
+}
diff --git a/vendor/tokio/tests/time_panic.rs b/vendor/tokio/tests/time_panic.rs
new file mode 100644
index 000000000..aaff11bb4
--- /dev/null
+++ b/vendor/tokio/tests/time_panic.rs
@@ -0,0 +1,93 @@
+#![warn(rust_2018_idioms)]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi doesn't support panic recovery
+
+use futures::future;
+use std::error::Error;
+use std::time::Duration;
+use tokio::runtime::{Builder, Runtime};
+use tokio::time::{self, interval, interval_at, timeout, Instant};
+
+mod support {
+    pub mod panic;
+}
+use support::panic::test_panic;
+
+#[test]
+fn pause_panic_caller() -> Result<(), Box<dyn Error>> {
+    let panic_location_file = test_panic(|| {
+        let rt = current_thread();
+
+        rt.block_on(async {
+            time::pause();
+            time::pause();
+        });
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+fn resume_panic_caller() -> Result<(), Box<dyn Error>> {
+    let panic_location_file = test_panic(|| {
+        let rt = current_thread();
+
+        rt.block_on(async {
+            time::resume();
+        });
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+fn interval_panic_caller() -> Result<(), Box<dyn Error>> {
+    let panic_location_file = test_panic(|| {
+        let _ = interval(Duration::from_millis(0));
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+fn interval_at_panic_caller() -> Result<(), Box<dyn Error>> {
+    let panic_location_file = test_panic(|| {
+        let _ = interval_at(Instant::now(), Duration::from_millis(0));
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+#[test]
+fn timeout_panic_caller() -> Result<(), Box<dyn Error>> {
+    let panic_location_file = test_panic(|| {
+        // Runtime without `enable_time` so it has no current timer set.
+        let rt = Builder::new_current_thread().build().unwrap();
+        rt.block_on(async {
+            let _ = timeout(Duration::from_millis(5), future::pending::<()>());
+        });
+    });
+
+    // The panic location should be in this file
+    assert_eq!(&panic_location_file.unwrap(), file!());
+
+    Ok(())
+}
+
+fn current_thread() -> Runtime {
+    tokio::runtime::Builder::new_current_thread()
+        .enable_all()
+        .build()
+        .unwrap()
+}
diff --git a/vendor/tokio/tests/time_pause.rs b/vendor/tokio/tests/time_pause.rs
index 02e050a2d..c772e3873 100644
--- a/vendor/tokio/tests/time_pause.rs
+++ b/vendor/tokio/tests/time_pause.rs
@@ -4,7 +4,10 @@
 use rand::SeedableRng;
 use rand::{rngs::StdRng, Rng};
 use tokio::time::{self, Duration, Instant, Sleep};
-use tokio_test::{assert_elapsed, assert_err, assert_pending, assert_ready, assert_ready_eq, task};
+use tokio_test::{assert_elapsed, assert_pending, assert_ready, assert_ready_eq, task};
+
+#[cfg(not(tokio_wasi))]
+use tokio_test::assert_err;
 
 use std::{
     future::Future,
@@ -26,12 +29,14 @@ async fn pause_time_in_task() {
     t.await.unwrap();
 }
 
+#[cfg(all(feature = "full", not(tokio_wasi)))] // Wasi doesn't support threads
 #[tokio::test(flavor = "multi_thread", worker_threads = 1)]
 #[should_panic]
 async fn pause_time_in_main_threads() {
     tokio::time::pause();
 }
 
+#[cfg(all(feature = "full", not(tokio_wasi)))] // Wasi doesn't support threads
 #[tokio::test(flavor = "multi_thread", worker_threads = 1)]
 async fn pause_time_in_spawn_threads() {
     let t = tokio::spawn(async {
diff --git a/vendor/tokio/tests/time_rt.rs b/vendor/tokio/tests/time_rt.rs
index 077534352..20f9e181b 100644
--- a/vendor/tokio/tests/time_rt.rs
+++ b/vendor/tokio/tests/time_rt.rs
@@ -5,6 +5,7 @@ use tokio::time::*;
 
 use std::sync::mpsc;
 
+#[cfg(all(feature = "rt-multi-thread", not(tokio_wasi)))] // Wasi doesn't support threads
 #[test]
 fn timer_with_threaded_runtime() {
     use tokio::runtime::Runtime;
@@ -13,7 +14,7 @@ fn timer_with_threaded_runtime() {
     let (tx, rx) = mpsc::channel();
 
     rt.spawn(async move {
-        let when = Instant::now() + Duration::from_millis(100);
+        let when = Instant::now() + Duration::from_millis(10);
 
         sleep_until(when).await;
         assert!(Instant::now() >= when);
@@ -25,14 +26,14 @@ fn timer_with_threaded_runtime() {
 }
 
 #[test]
-fn timer_with_basic_scheduler() {
+fn timer_with_current_thread_scheduler() {
     use tokio::runtime::Builder;
 
     let rt = Builder::new_current_thread().enable_all().build().unwrap();
     let (tx, rx) = mpsc::channel();
 
     rt.block_on(async move {
-        let when = Instant::now() + Duration::from_millis(100);
+        let when = Instant::now() + Duration::from_millis(10);
 
         sleep_until(when).await;
         assert!(Instant::now() >= when);
@@ -67,7 +68,7 @@ async fn starving() {
         }
     }
 
-    let when = Instant::now() + Duration::from_millis(20);
+    let when = Instant::now() + Duration::from_millis(10);
     let starve = Starve(Box::pin(sleep_until(when)), 0);
 
     starve.await;
@@ -81,7 +82,7 @@ async fn timeout_value() {
     let (_tx, rx) = oneshot::channel::<()>();
 
     let now = Instant::now();
-    let dur = Duration::from_millis(20);
+    let dur = Duration::from_millis(10);
 
     let res = timeout(dur, rx).await;
     assert!(res.is_err());
diff --git a/vendor/tokio/tests/time_sleep.rs b/vendor/tokio/tests/time_sleep.rs
index e3e27b0c9..94022e3c0 100644
--- a/vendor/tokio/tests/time_sleep.rs
+++ b/vendor/tokio/tests/time_sleep.rs
@@ -24,7 +24,7 @@ async fn immediate_sleep() {
 async fn is_elapsed() {
     time::pause();
 
-    let sleep = time::sleep(Duration::from_millis(50));
+    let sleep = time::sleep(Duration::from_millis(10));
 
     tokio::pin!(sleep);
 
@@ -168,6 +168,7 @@ async fn reset_sleep_to_past() {
     assert_ready!(sleep.poll());
 }
 
+#[cfg(not(tokio_wasi))] // Wasi doesn't support panic recovery
 #[test]
 #[should_panic]
 fn creating_sleep_outside_of_context() {
@@ -188,10 +189,7 @@ async fn greater_than_max() {
 
 #[tokio::test]
 async fn short_sleeps() {
-    for i in 0..10000 {
-        if (i % 10) == 0 {
-            eprintln!("=== {}", i);
-        }
+    for _ in 0..10000 {
         tokio::time::sleep(std::time::Duration::from_millis(0)).await;
     }
 }
@@ -236,22 +234,6 @@ async fn long_sleeps() {
 }
 
 #[tokio::test]
-#[should_panic(expected = "Duration too far into the future")]
-async fn very_long_sleeps() {
-    tokio::time::pause();
-
-    // Some platforms (eg macos) can't represent times this far in the future
-    if let Some(deadline) = tokio::time::Instant::now().checked_add(Duration::from_secs(1u64 << 62))
-    {
-        tokio::time::sleep_until(deadline).await;
-    } else {
-        // make it pass anyway (we can't skip/ignore the test based on the
-        // result of checked_add)
-        panic!("Duration too far into the future (test ignored)")
-    }
-}
-
-#[tokio::test]
 async fn reset_after_firing() {
     let timer = tokio::time::sleep(std::time::Duration::from_millis(1));
     tokio::pin!(timer);
@@ -286,6 +268,20 @@ async fn exactly_max() {
 }
 
 #[tokio::test]
+async fn issue_5183() {
+    time::pause();
+
+    let big = std::time::Duration::from_secs(u64::MAX / 10);
+    // This is a workaround since awaiting sleep(big) will never finish.
+    #[rustfmt::skip]
+    tokio::select! {
+	biased;
+        _ = tokio::time::sleep(big) => {}
+        _ = tokio::time::sleep(std::time::Duration::from_nanos(1)) => {}
+    }
+}
+
+#[tokio::test]
 async fn no_out_of_bounds_close_to_max() {
     time::pause();
     time::sleep(ms(MAX_DURATION - 1)).await;
@@ -333,18 +329,18 @@ async fn drop_from_wake() {
 
     tokio::time::pause();
 
-    let mut lock = list.lock().unwrap();
+    {
+        let mut lock = list.lock().unwrap();
 
-    for _ in 0..100 {
-        let mut timer = Box::pin(tokio::time::sleep(Duration::from_millis(10)));
+        for _ in 0..100 {
+            let mut timer = Box::pin(tokio::time::sleep(Duration::from_millis(10)));
 
-        let _ = timer.as_mut().poll(&mut Context::from_waker(&arc_wake));
+            let _ = timer.as_mut().poll(&mut Context::from_waker(&arc_wake));
 
-        lock.push(timer);
+            lock.push(timer);
+        }
     }
 
-    drop(lock);
-
     tokio::time::sleep(Duration::from_millis(11)).await;
 
     assert!(
diff --git a/vendor/tokio/tests/time_timeout.rs b/vendor/tokio/tests/time_timeout.rs
index dbd80eb8a..be6b8fb44 100644
--- a/vendor/tokio/tests/time_timeout.rs
+++ b/vendor/tokio/tests/time_timeout.rs
@@ -17,6 +17,7 @@ async fn simultaneous_deadline_future_completion() {
     assert_ready_ok!(fut.poll());
 }
 
+#[cfg_attr(tokio_wasi, ignore = "FIXME: `fut.poll()` panics on Wasi")]
 #[tokio::test]
 async fn completed_future_past_deadline() {
     // Wrap it with a deadline
@@ -135,3 +136,16 @@ async fn deadline_future_elapses() {
 fn ms(n: u64) -> Duration {
     Duration::from_millis(n)
 }
+
+#[tokio::test]
+async fn timeout_is_not_exhausted_by_future() {
+    let fut = timeout(ms(1), async {
+        let mut buffer = [0u8; 1];
+        loop {
+            use tokio::io::AsyncReadExt;
+            let _ = tokio::io::empty().read(&mut buffer).await;
+        }
+    });
+
+    assert!(fut.await.is_err());
+}
diff --git a/vendor/tokio/tests/udp.rs b/vendor/tokio/tests/udp.rs
index 715d8ebe2..565323b37 100644
--- a/vendor/tokio/tests/udp.rs
+++ b/vendor/tokio/tests/udp.rs
@@ -1,10 +1,11 @@
 #![warn(rust_2018_idioms)]
-#![cfg(feature = "full")]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi does not support bind or UDP
 
 use futures::future::poll_fn;
 use std::io;
 use std::sync::Arc;
 use tokio::{io::ReadBuf, net::UdpSocket};
+use tokio_test::assert_ok;
 
 const MSG: &[u8] = b"hello";
 const MSG_LEN: usize = MSG.len();
@@ -38,7 +39,7 @@ async fn send_recv_poll() -> std::io::Result<()> {
 
     let mut recv_buf = [0u8; 32];
     let mut read = ReadBuf::new(&mut recv_buf);
-    let _len = poll_fn(|cx| receiver.poll_recv(cx, &mut read)).await?;
+    poll_fn(|cx| receiver.poll_recv(cx, &mut read)).await?;
 
     assert_eq!(read.filled(), MSG);
     Ok(())
@@ -106,6 +107,45 @@ async fn send_to_peek_from() -> std::io::Result<()> {
 }
 
 #[tokio::test]
+async fn send_to_try_peek_from() -> std::io::Result<()> {
+    let sender = UdpSocket::bind("127.0.0.1:0").await?;
+    let receiver = UdpSocket::bind("127.0.0.1:0").await?;
+
+    let receiver_addr = receiver.local_addr()?;
+    poll_fn(|cx| sender.poll_send_to(cx, MSG, receiver_addr)).await?;
+
+    // peek
+    let mut recv_buf = [0u8; 32];
+
+    loop {
+        match receiver.try_peek_from(&mut recv_buf) {
+            Ok((n, addr)) => {
+                assert_eq!(&recv_buf[..n], MSG);
+                assert_eq!(addr, sender.local_addr()?);
+                break;
+            }
+            Err(e) if e.kind() == io::ErrorKind::WouldBlock => {
+                receiver.readable().await?;
+            }
+            Err(e) => return Err(e),
+        }
+    }
+
+    // peek
+    let mut recv_buf = [0u8; 32];
+    let (n, addr) = receiver.peek_from(&mut recv_buf).await?;
+    assert_eq!(&recv_buf[..n], MSG);
+    assert_eq!(addr, sender.local_addr()?);
+
+    let mut recv_buf = [0u8; 32];
+    let (n, addr) = receiver.recv_from(&mut recv_buf).await?;
+    assert_eq!(&recv_buf[..n], MSG);
+    assert_eq!(addr, sender.local_addr()?);
+
+    Ok(())
+}
+
+#[tokio::test]
 async fn send_to_peek_from_poll() -> std::io::Result<()> {
     let sender = UdpSocket::bind("127.0.0.1:0").await?;
     let receiver = UdpSocket::bind("127.0.0.1:0").await?;
@@ -134,6 +174,92 @@ async fn send_to_peek_from_poll() -> std::io::Result<()> {
 }
 
 #[tokio::test]
+async fn peek_sender() -> std::io::Result<()> {
+    let sender = UdpSocket::bind("127.0.0.1:0").await?;
+    let receiver = UdpSocket::bind("127.0.0.1:0").await?;
+
+    let sender_addr = sender.local_addr()?;
+    let receiver_addr = receiver.local_addr()?;
+
+    let msg = b"Hello, world!";
+    sender.send_to(msg, receiver_addr).await?;
+
+    let peeked_sender = receiver.peek_sender().await?;
+    assert_eq!(peeked_sender, sender_addr);
+
+    // Assert that `peek_sender()` returns the right sender but
+    // doesn't remove from the receive queue.
+    let mut recv_buf = [0u8; 32];
+    let (read, received_sender) = receiver.recv_from(&mut recv_buf).await?;
+
+    assert_eq!(&recv_buf[..read], msg);
+    assert_eq!(received_sender, peeked_sender);
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn poll_peek_sender() -> std::io::Result<()> {
+    let sender = UdpSocket::bind("127.0.0.1:0").await?;
+    let receiver = UdpSocket::bind("127.0.0.1:0").await?;
+
+    let sender_addr = sender.local_addr()?;
+    let receiver_addr = receiver.local_addr()?;
+
+    let msg = b"Hello, world!";
+    poll_fn(|cx| sender.poll_send_to(cx, msg, receiver_addr)).await?;
+
+    let peeked_sender = poll_fn(|cx| receiver.poll_peek_sender(cx)).await?;
+    assert_eq!(peeked_sender, sender_addr);
+
+    // Assert that `poll_peek_sender()` returns the right sender but
+    // doesn't remove from the receive queue.
+    let mut recv_buf = [0u8; 32];
+    let mut read = ReadBuf::new(&mut recv_buf);
+    let received_sender = poll_fn(|cx| receiver.poll_recv_from(cx, &mut read)).await?;
+
+    assert_eq!(read.filled(), msg);
+    assert_eq!(received_sender, peeked_sender);
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn try_peek_sender() -> std::io::Result<()> {
+    let sender = UdpSocket::bind("127.0.0.1:0").await?;
+    let receiver = UdpSocket::bind("127.0.0.1:0").await?;
+
+    let sender_addr = sender.local_addr()?;
+    let receiver_addr = receiver.local_addr()?;
+
+    let msg = b"Hello, world!";
+    sender.send_to(msg, receiver_addr).await?;
+
+    let peeked_sender = loop {
+        match receiver.try_peek_sender() {
+            Ok(peeked_sender) => break peeked_sender,
+            Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
+                receiver.readable().await?;
+            }
+            Err(e) => return Err(e),
+        }
+    };
+
+    assert_eq!(peeked_sender, sender_addr);
+
+    // Assert that `try_peek_sender()` returns the right sender but
+    // didn't remove from the receive queue.
+    let mut recv_buf = [0u8; 32];
+    // We already peeked the sender so there must be data in the receive queue.
+    let (read, received_sender) = receiver.try_recv_from(&mut recv_buf).unwrap();
+
+    assert_eq!(&recv_buf[..read], msg);
+    assert_eq!(received_sender, peeked_sender);
+
+    Ok(())
+}
+
+#[tokio::test]
 async fn split() -> std::io::Result<()> {
     let socket = UdpSocket::bind("127.0.0.1:0").await?;
     let s = Arc::new(socket);
@@ -399,6 +525,23 @@ async fn try_recv_buf() {
 }
 
 #[tokio::test]
+async fn recv_buf() -> std::io::Result<()> {
+    let sender = UdpSocket::bind("127.0.0.1:0").await?;
+    let receiver = UdpSocket::bind("127.0.0.1:0").await?;
+
+    sender.connect(receiver.local_addr()?).await?;
+    receiver.connect(sender.local_addr()?).await?;
+
+    sender.send(MSG).await?;
+    let mut recv_buf = Vec::with_capacity(32);
+    let len = receiver.recv_buf(&mut recv_buf).await?;
+
+    assert_eq!(len, MSG_LEN);
+    assert_eq!(&recv_buf[..len], MSG);
+    Ok(())
+}
+
+#[tokio::test]
 async fn try_recv_buf_from() {
     // Create listener
     let server = UdpSocket::bind("127.0.0.1:0").await.unwrap();
@@ -440,3 +583,63 @@ async fn try_recv_buf_from() {
         }
     }
 }
+
+#[tokio::test]
+async fn recv_buf_from() -> std::io::Result<()> {
+    let sender = UdpSocket::bind("127.0.0.1:0").await?;
+    let receiver = UdpSocket::bind("127.0.0.1:0").await?;
+
+    sender.connect(receiver.local_addr()?).await?;
+
+    sender.send(MSG).await?;
+    let mut recv_buf = Vec::with_capacity(32);
+    let (len, caddr) = receiver.recv_buf_from(&mut recv_buf).await?;
+
+    assert_eq!(len, MSG_LEN);
+    assert_eq!(&recv_buf[..len], MSG);
+    assert_eq!(caddr, sender.local_addr()?);
+    Ok(())
+}
+
+#[tokio::test]
+async fn poll_ready() {
+    // Create listener
+    let server = UdpSocket::bind("127.0.0.1:0").await.unwrap();
+    let saddr = server.local_addr().unwrap();
+
+    // Create socket pair
+    let client = UdpSocket::bind("127.0.0.1:0").await.unwrap();
+    let caddr = client.local_addr().unwrap();
+
+    for _ in 0..5 {
+        loop {
+            assert_ok!(poll_fn(|cx| client.poll_send_ready(cx)).await);
+
+            match client.try_send_to(b"hello world", saddr) {
+                Ok(n) => {
+                    assert_eq!(n, 11);
+                    break;
+                }
+                Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => continue,
+                Err(e) => panic!("{:?}", e),
+            }
+        }
+
+        loop {
+            assert_ok!(poll_fn(|cx| server.poll_recv_ready(cx)).await);
+
+            let mut buf = Vec::with_capacity(512);
+
+            match server.try_recv_buf_from(&mut buf) {
+                Ok((n, addr)) => {
+                    assert_eq!(n, 11);
+                    assert_eq!(addr, caddr);
+                    assert_eq!(&buf[0..11], &b"hello world"[..]);
+                    break;
+                }
+                Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => continue,
+                Err(e) => panic!("{:?}", e),
+            }
+        }
+    }
+}
diff --git a/vendor/tokio/tests/uds_datagram.rs b/vendor/tokio/tests/uds_datagram.rs
index 4d2846865..ad22a0b99 100644
--- a/vendor/tokio/tests/uds_datagram.rs
+++ b/vendor/tokio/tests/uds_datagram.rs
@@ -29,9 +29,7 @@ async fn echo() -> io::Result<()> {
     let server_socket = UnixDatagram::bind(server_path.clone())?;
 
     tokio::spawn(async move {
-        if let Err(e) = echo_server(server_socket).await {
-            eprintln!("Error in echo server: {}", e);
-        }
+        let _ = echo_server(server_socket).await;
     });
 
     {
@@ -55,9 +53,7 @@ async fn echo_from() -> io::Result<()> {
     let server_socket = UnixDatagram::bind(server_path.clone())?;
 
     tokio::spawn(async move {
-        if let Err(e) = echo_server(server_socket).await {
-            eprintln!("Error in echo server: {}", e);
-        }
+        let _ = echo_server(server_socket).await;
     });
 
     {
@@ -181,7 +177,7 @@ async fn send_recv_poll() -> std::io::Result<()> {
 
     let mut recv_buf = [0u8; 32];
     let mut read = ReadBuf::new(&mut recv_buf);
-    let _len = poll_fn(|cx| receiver.poll_recv(cx, &mut read)).await?;
+    poll_fn(|cx| receiver.poll_recv(cx, &mut read)).await?;
 
     assert_eq!(read.filled(), msg);
     Ok(())
@@ -281,6 +277,28 @@ async fn try_recv_buf_from() -> std::io::Result<()> {
     Ok(())
 }
 
+#[tokio::test]
+async fn recv_buf_from() -> std::io::Result<()> {
+    let tmp = tempfile::tempdir()?;
+
+    // Bind each socket to a filesystem path
+    let tx_path = tmp.path().join("tx");
+    let tx = UnixDatagram::bind(&tx_path)?;
+    let rx_path = tmp.path().join("rx");
+    let rx = UnixDatagram::bind(&rx_path)?;
+
+    let bytes = b"hello world";
+    tx.send_to(bytes, &rx_path).await?;
+
+    let mut buf = Vec::with_capacity(24);
+    let (size, addr) = rx.recv_buf_from(&mut buf).await?;
+
+    let dgram = &buf[..size];
+    assert_eq!(dgram, bytes);
+    assert_eq!(addr.as_pathname().unwrap(), &tx_path);
+    Ok(())
+}
+
 // Even though we use sync non-blocking io we still need a reactor.
 #[tokio::test]
 async fn try_recv_buf_never_block() -> io::Result<()> {
@@ -328,3 +346,68 @@ async fn try_recv_buf_never_block() -> io::Result<()> {
 
     Ok(())
 }
+
+#[tokio::test]
+async fn recv_buf() -> std::io::Result<()> {
+    // Create the pair of sockets
+    let (sock1, sock2) = UnixDatagram::pair()?;
+
+    // Since the sockets are paired, the paired send/recv
+    // functions can be used
+    let bytes = b"hello world";
+    sock1.send(bytes).await?;
+
+    let mut buff = Vec::with_capacity(24);
+    let size = sock2.recv_buf(&mut buff).await?;
+
+    let dgram = &buff[..size];
+    assert_eq!(dgram, bytes);
+    Ok(())
+}
+
+#[tokio::test]
+async fn poll_ready() -> io::Result<()> {
+    let dir = tempfile::tempdir().unwrap();
+    let server_path = dir.path().join("server.sock");
+    let client_path = dir.path().join("client.sock");
+
+    // Create listener
+    let server = UnixDatagram::bind(&server_path)?;
+
+    // Create socket pair
+    let client = UnixDatagram::bind(&client_path)?;
+
+    for _ in 0..5 {
+        loop {
+            poll_fn(|cx| client.poll_send_ready(cx)).await?;
+
+            match client.try_send_to(b"hello world", &server_path) {
+                Ok(n) => {
+                    assert_eq!(n, 11);
+                    break;
+                }
+                Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => continue,
+                Err(e) => panic!("{:?}", e),
+            }
+        }
+
+        loop {
+            poll_fn(|cx| server.poll_recv_ready(cx)).await?;
+
+            let mut buf = Vec::with_capacity(512);
+
+            match server.try_recv_buf_from(&mut buf) {
+                Ok((n, addr)) => {
+                    assert_eq!(n, 11);
+                    assert_eq!(addr.as_pathname(), Some(client_path.as_ref()));
+                    assert_eq!(&buf[0..11], &b"hello world"[..]);
+                    break;
+                }
+                Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => continue,
+                Err(e) => panic!("{:?}", e),
+            }
+        }
+    }
+
+    Ok(())
+}
diff --git a/vendor/tokio/tests/uds_stream.rs b/vendor/tokio/tests/uds_stream.rs
index 5f1b4cffb..b8c4e6a8e 100644
--- a/vendor/tokio/tests/uds_stream.rs
+++ b/vendor/tokio/tests/uds_stream.rs
@@ -25,13 +25,13 @@ async fn accept_read_write() -> std::io::Result<()> {
     let connect = UnixStream::connect(&sock_path);
     let ((mut server, _), mut client) = try_join(accept, connect).await?;
 
-    // Write to the client. TODO: Switch to write_all.
-    let write_len = client.write(b"hello").await?;
-    assert_eq!(write_len, 5);
+    // Write to the client.
+    client.write_all(b"hello").await?;
     drop(client);
-    // Read from the server. TODO: Switch to read_to_end.
-    let mut buf = [0u8; 5];
-    server.read_exact(&mut buf).await?;
+
+    // Read from the server.
+    let mut buf = vec![];
+    server.read_to_end(&mut buf).await?;
     assert_eq!(&buf, b"hello");
     let len = server.read(&mut buf).await?;
     assert_eq!(len, 0);
diff --git a/vendor/tokio/tests/unwindsafe.rs b/vendor/tokio/tests/unwindsafe.rs
new file mode 100644
index 000000000..3e6382086
--- /dev/null
+++ b/vendor/tokio/tests/unwindsafe.rs
@@ -0,0 +1,42 @@
+#![warn(rust_2018_idioms)]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi does not support panic recovery
+
+use std::panic::{RefUnwindSafe, UnwindSafe};
+
+#[test]
+fn notify_is_unwind_safe() {
+    is_unwind_safe::<tokio::sync::Notify>();
+}
+
+#[test]
+fn join_handle_is_unwind_safe() {
+    is_unwind_safe::<tokio::task::JoinHandle<()>>();
+}
+
+#[test]
+fn net_types_are_unwind_safe() {
+    is_unwind_safe::<tokio::net::TcpListener>();
+    is_unwind_safe::<tokio::net::TcpSocket>();
+    is_unwind_safe::<tokio::net::TcpStream>();
+    is_unwind_safe::<tokio::net::UdpSocket>();
+}
+
+#[test]
+#[cfg(unix)]
+fn unix_net_types_are_unwind_safe() {
+    is_unwind_safe::<tokio::net::UnixDatagram>();
+    is_unwind_safe::<tokio::net::UnixListener>();
+    is_unwind_safe::<tokio::net::UnixStream>();
+}
+
+#[test]
+#[cfg(windows)]
+fn windows_net_types_are_unwind_safe() {
+    use tokio::net::windows::named_pipe::NamedPipeClient;
+    use tokio::net::windows::named_pipe::NamedPipeServer;
+
+    is_unwind_safe::<NamedPipeClient>();
+    is_unwind_safe::<NamedPipeServer>();
+}
+
+fn is_unwind_safe<T: UnwindSafe + RefUnwindSafe>() {}