diff options
Diffstat (limited to '')
| -rw-r--r-- | third_party/rust/tokio/src/macros/cfg.rs | 457 | ||||
| -rw-r--r-- | third_party/rust/tokio/src/macros/join.rs | 119 | ||||
| -rw-r--r-- | third_party/rust/tokio/src/macros/loom.rs | 12 | ||||
| -rw-r--r-- | third_party/rust/tokio/src/macros/mod.rs | 40 | ||||
| -rw-r--r-- | third_party/rust/tokio/src/macros/pin.rs | 144 | ||||
| -rw-r--r-- | third_party/rust/tokio/src/macros/ready.rs | 8 | ||||
| -rw-r--r-- | third_party/rust/tokio/src/macros/scoped_tls.rs | 77 | ||||
| -rw-r--r-- | third_party/rust/tokio/src/macros/select.rs | 1001 | ||||
| -rw-r--r-- | third_party/rust/tokio/src/macros/support.rs | 9 | ||||
| -rw-r--r-- | third_party/rust/tokio/src/macros/thread_local.rs | 4 | ||||
| -rw-r--r-- | third_party/rust/tokio/src/macros/trace.rs | 26 | ||||
| -rw-r--r-- | third_party/rust/tokio/src/macros/try_join.rs | 171 |
12 files changed, 2068 insertions, 0 deletions
diff --git a/third_party/rust/tokio/src/macros/cfg.rs b/third_party/rust/tokio/src/macros/cfg.rs new file mode 100644 index 0000000000..b6beb3d695 --- /dev/null +++ b/third_party/rust/tokio/src/macros/cfg.rs @@ -0,0 +1,457 @@ +#![allow(unused_macros)] + +macro_rules! feature { + ( + #![$meta:meta] + $($item:item)* + ) => { + $( + #[cfg($meta)] + #[cfg_attr(docsrs, doc(cfg($meta)))] + $item + )* + } +} + +/// Enables enter::block_on. +macro_rules! cfg_block_on { + ($($item:item)*) => { + $( + #[cfg(any( + feature = "fs", + feature = "net", + feature = "io-std", + feature = "rt", + ))] + $item + )* + } +} + +/// Enables internal `AtomicWaker` impl. +macro_rules! cfg_atomic_waker_impl { + ($($item:item)*) => { + $( + #[cfg(any( + feature = "net", + feature = "process", + feature = "rt", + feature = "signal", + feature = "time", + ))] + #[cfg(not(loom))] + $item + )* + } +} + +macro_rules! cfg_aio { + ($($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_attr(docsrs, doc(cfg(feature = "fs")))] + $item + )* + } +} + +macro_rules! cfg_io_blocking { + ($($item:item)*) => { + $( #[cfg(any(feature = "io-std", feature = "fs"))] $item )* + } +} + +macro_rules! cfg_io_driver { + ($($item:item)*) => { + $( + #[cfg(any( + feature = "net", + feature = "process", + all(unix, feature = "signal"), + ))] + #[cfg_attr(docsrs, doc(cfg(any( + feature = "net", + feature = "process", + all(unix, feature = "signal"), + ))))] + $item + )* + } +} + +macro_rules! cfg_io_driver_impl { + ( $( $item:item )* ) => { + $( + #[cfg(any( + feature = "net", + feature = "process", + all(unix, feature = "signal"), + ))] + $item + )* + } +} + +macro_rules! cfg_not_io_driver { + ($($item:item)*) => { + $( + #[cfg(not(any( + feature = "net", + feature = "process", + all(unix, feature = "signal"), + )))] + $item + )* + } +} + +macro_rules! cfg_io_readiness { + ($($item:item)*) => { + $( + #[cfg(feature = "net")] + $item + )* + } +} + +macro_rules! cfg_io_std { + ($($item:item)*) => { + $( + #[cfg(feature = "io-std")] + #[cfg_attr(docsrs, doc(cfg(feature = "io-std")))] + $item + )* + } +} + +macro_rules! cfg_io_util { + ($($item:item)*) => { + $( + #[cfg(feature = "io-util")] + #[cfg_attr(docsrs, doc(cfg(feature = "io-util")))] + $item + )* + } +} + +macro_rules! cfg_not_io_util { + ($($item:item)*) => { + $( #[cfg(not(feature = "io-util"))] $item )* + } +} + +macro_rules! cfg_loom { + ($($item:item)*) => { + $( #[cfg(loom)] $item )* + } +} + +macro_rules! cfg_not_loom { + ($($item:item)*) => { + $( #[cfg(not(loom))] $item )* + } +} + +macro_rules! cfg_macros { + ($($item:item)*) => { + $( + #[cfg(feature = "macros")] + #[cfg_attr(docsrs, doc(cfg(feature = "macros")))] + $item + )* + } +} + +macro_rules! cfg_metrics { + ($($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))))] + $item + )* + } +} + +macro_rules! cfg_net { + ($($item:item)*) => { + $( + #[cfg(feature = "net")] + #[cfg_attr(docsrs, doc(cfg(feature = "net")))] + $item + )* + } +} + +macro_rules! cfg_net_unix { + ($($item:item)*) => { + $( + #[cfg(all(unix, feature = "net"))] + #[cfg_attr(docsrs, doc(cfg(all(unix, feature = "net"))))] + $item + )* + } +} + +macro_rules! cfg_net_windows { + ($($item:item)*) => { + $( + #[cfg(all(any(all(doc, docsrs), windows), feature = "net"))] + #[cfg_attr(docsrs, doc(cfg(all(windows, feature = "net"))))] + $item + )* + } +} + +macro_rules! cfg_process { + ($($item:item)*) => { + $( + #[cfg(feature = "process")] + #[cfg_attr(docsrs, doc(cfg(feature = "process")))] + #[cfg(not(loom))] + $item + )* + } +} + +macro_rules! cfg_process_driver { + ($($item:item)*) => { + #[cfg(unix)] + #[cfg(not(loom))] + cfg_process! { $($item)* } + } +} + +macro_rules! cfg_not_process_driver { + ($($item:item)*) => { + $( + #[cfg(not(all(unix, not(loom), feature = "process")))] + $item + )* + } +} + +macro_rules! cfg_signal { + ($($item:item)*) => { + $( + #[cfg(feature = "signal")] + #[cfg_attr(docsrs, doc(cfg(feature = "signal")))] + #[cfg(not(loom))] + $item + )* + } +} + +macro_rules! cfg_signal_internal { + ($($item:item)*) => { + $( + #[cfg(any(feature = "signal", all(unix, feature = "process")))] + #[cfg(not(loom))] + $item + )* + } +} + +macro_rules! cfg_not_signal_internal { + ($($item:item)*) => { + $( + #[cfg(any(loom, not(unix), not(any(feature = "signal", all(unix, feature = "process")))))] + $item + )* + } +} + +macro_rules! cfg_sync { + ($($item:item)*) => { + $( + #[cfg(feature = "sync")] + #[cfg_attr(docsrs, doc(cfg(feature = "sync")))] + $item + )* + } +} + +macro_rules! cfg_not_sync { + ($($item:item)*) => { + $( #[cfg(not(feature = "sync"))] $item )* + } +} + +macro_rules! cfg_rt { + ($($item:item)*) => { + $( + #[cfg(feature = "rt")] + #[cfg_attr(docsrs, doc(cfg(feature = "rt")))] + $item + )* + } +} + +macro_rules! cfg_not_rt { + ($($item:item)*) => { + $( #[cfg(not(feature = "rt"))] $item )* + } +} + +macro_rules! cfg_rt_multi_thread { + ($($item:item)*) => { + $( + #[cfg(feature = "rt-multi-thread")] + #[cfg_attr(docsrs, doc(cfg(feature = "rt-multi-thread")))] + $item + )* + } +} + +macro_rules! cfg_not_rt_multi_thread { + ($($item:item)*) => { + $( #[cfg(not(feature = "rt-multi-thread"))] $item )* + } +} + +macro_rules! cfg_test_util { + ($($item:item)*) => { + $( + #[cfg(feature = "test-util")] + #[cfg_attr(docsrs, doc(cfg(feature = "test-util")))] + $item + )* + } +} + +macro_rules! cfg_not_test_util { + ($($item:item)*) => { + $( #[cfg(not(feature = "test-util"))] $item )* + } +} + +macro_rules! cfg_time { + ($($item:item)*) => { + $( + #[cfg(feature = "time")] + #[cfg_attr(docsrs, doc(cfg(feature = "time")))] + $item + )* + } +} + +macro_rules! cfg_not_time { + ($($item:item)*) => { + $( #[cfg(not(feature = "time"))] $item )* + } +} + +macro_rules! cfg_trace { + ($($item:item)*) => { + $( + #[cfg(all(tokio_unstable, 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)))] + $item + )* + }; +} + +macro_rules! cfg_not_trace { + ($($item:item)*) => { + $( + #[cfg(any(not(tokio_unstable), not(feature = "tracing")))] + $item + )* + } +} + +macro_rules! cfg_coop { + ($($item:item)*) => { + $( + #[cfg(any( + feature = "fs", + feature = "io-std", + feature = "net", + feature = "process", + feature = "rt", + feature = "signal", + feature = "sync", + feature = "time", + ))] + $item + )* + } +} + +macro_rules! cfg_not_coop { + ($($item:item)*) => { + $( + #[cfg(not(any( + feature = "fs", + feature = "io-std", + feature = "net", + feature = "process", + feature = "rt", + feature = "signal", + feature = "sync", + feature = "time", + )))] + $item + )* + } +} + +macro_rules! cfg_has_atomic_u64 { + ($($item:item)*) => { + $( + #[cfg(not(any( + target_arch = "arm", + target_arch = "mips", + target_arch = "powerpc", + target_arch = "riscv32" + )))] + $item + )* + } +} + +macro_rules! cfg_not_has_atomic_u64 { + ($($item:item)*) => { + $( + #[cfg(any( + target_arch = "arm", + target_arch = "mips", + target_arch = "powerpc", + target_arch = "riscv32" + ))] + $item + )* + } +} diff --git a/third_party/rust/tokio/src/macros/join.rs b/third_party/rust/tokio/src/macros/join.rs new file mode 100644 index 0000000000..f91b5f1914 --- /dev/null +++ b/third_party/rust/tokio/src/macros/join.rs @@ -0,0 +1,119 @@ +/// Waits on multiple concurrent branches, returning when **all** branches +/// complete. +/// +/// The `join!` macro must be used inside of async functions, closures, and +/// blocks. +/// +/// The `join!` macro takes a list of async expressions and evaluates them +/// concurrently on the same task. Each async expression evaluates to a future +/// and the futures from each expression are multiplexed on the current task. +/// +/// When working with async expressions returning `Result`, `join!` will wait +/// 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 +/// +/// # Notes +/// +/// The supplied futures are stored inline and does not require allocating a +/// `Vec`. +/// +/// ### Runtime characteristics +/// +/// By running all async expressions on the current task, the expressions are +/// able to run **concurrently** but not in **parallel**. This means all +/// expressions are run on the same thread and if one branch blocks the thread, +/// all other expressions will be unable to continue. If parallelism is +/// required, spawn each async expression using [`tokio::spawn`] and pass the +/// join handle to `join!`. +/// +/// [`tokio::spawn`]: crate::spawn +/// +/// # Examples +/// +/// Basic join with two branches +/// +/// ``` +/// async fn do_stuff_async() { +/// // async work +/// } +/// +/// async fn more_async_work() { +/// // more here +/// } +/// +/// #[tokio::main] +/// async fn main() { +/// let (first, second) = tokio::join!( +/// do_stuff_async(), +/// more_async_work()); +/// +/// // do something with the values +/// } +/// ``` +#[macro_export] +#[cfg_attr(docsrs, doc(cfg(feature = "macros")))] +macro_rules! join { + (@ { + // One `_` for each branch in the `join!` macro. This is not used once + // normalization is complete. + ( $($count:tt)* ) + + // Normalized join! branches + $( ( $($skip:tt)* ) $e:expr, )* + + }) => {{ + use $crate::macros::support::{maybe_done, poll_fn, Future, Pin}; + use $crate::macros::support::Poll::{Ready, Pending}; + + // Safety: nothing must be moved out of `futures`. This is to satisfy + // the requirement of `Pin::new_unchecked` called below. + let mut futures = ( $( maybe_done($e), )* ); + + poll_fn(move |cx| { + let mut is_pending = false; + + $( + // 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.poll(cx).is_pending() { + is_pending = true; + } + )* + + if is_pending { + Pending + } else { + Ready(($({ + // 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) }; + + fut.take_output().expect("expected completed future") + },)*)) + } + }).await + }}; + + // ===== Normalize ===== + + (@ { ( $($s:tt)* ) $($t:tt)* } $e:expr, $($r:tt)* ) => { + $crate::join!(@{ ($($s)* _) $($t)* ($($s)*) $e, } $($r)*) + }; + + // ===== Entry point ===== + + ( $($e:expr),* $(,)?) => { + $crate::join!(@{ () } $($e,)*) + }; +} diff --git a/third_party/rust/tokio/src/macros/loom.rs b/third_party/rust/tokio/src/macros/loom.rs new file mode 100644 index 0000000000..d57d9fb0f7 --- /dev/null +++ b/third_party/rust/tokio/src/macros/loom.rs @@ -0,0 +1,12 @@ +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/third_party/rust/tokio/src/macros/mod.rs b/third_party/rust/tokio/src/macros/mod.rs new file mode 100644 index 0000000000..a1839c8305 --- /dev/null +++ b/third_party/rust/tokio/src/macros/mod.rs @@ -0,0 +1,40 @@ +#![cfg_attr(not(feature = "full"), allow(unused_macros))] + +#[macro_use] +mod cfg; + +#[macro_use] +mod loom; + +#[macro_use] +mod pin; + +#[macro_use] +mod ready; + +#[macro_use] +mod thread_local; + +cfg_trace! { + #[macro_use] + mod trace; +} + +#[macro_use] +#[cfg(feature = "rt")] +pub(crate) mod scoped_tls; + +cfg_macros! { + #[macro_use] + mod select; + + #[macro_use] + mod join; + + #[macro_use] + mod try_join; +} + +// Includes re-exports needed to implement macros +#[doc(hidden)] +pub mod support; diff --git a/third_party/rust/tokio/src/macros/pin.rs b/third_party/rust/tokio/src/macros/pin.rs new file mode 100644 index 0000000000..7af9ce7d1f --- /dev/null +++ b/third_party/rust/tokio/src/macros/pin.rs @@ -0,0 +1,144 @@ +/// Pins a value on the stack. +/// +/// Calls to `async fn` return anonymous [`Future`] values that are `!Unpin`. +/// These values must be pinned before they can be polled. Calling `.await` will +/// handle this, but consumes the future. If it is required to call `.await` on +/// a `&mut _` reference, the caller is responsible for pinning the future. +/// +/// Pinning may be done by allocating with [`Box::pin`] or by using the stack +/// with the `pin!` macro. +/// +/// The following will **fail to compile**: +/// +/// ```compile_fail +/// async fn my_async_fn() { +/// // async logic here +/// } +/// +/// #[tokio::main] +/// async fn main() { +/// let mut future = my_async_fn(); +/// (&mut future).await; +/// } +/// ``` +/// +/// To make this work requires pinning: +/// +/// ``` +/// use tokio::pin; +/// +/// async fn my_async_fn() { +/// // async logic here +/// } +/// +/// #[tokio::main] +/// async fn main() { +/// let future = my_async_fn(); +/// pin!(future); +/// +/// (&mut future).await; +/// } +/// ``` +/// +/// Pinning is useful when using `select!` and stream operators that require `T: +/// Stream + Unpin`. +/// +/// [`Future`]: trait@std::future::Future +/// [`Box::pin`]: std::boxed::Box::pin +/// +/// # Usage +/// +/// The `pin!` macro takes **identifiers** as arguments. It does **not** work +/// with expressions. +/// +/// The following does not compile as an expression is passed to `pin!`. +/// +/// ```compile_fail +/// async fn my_async_fn() { +/// // async logic here +/// } +/// +/// #[tokio::main] +/// async fn main() { +/// let mut future = pin!(my_async_fn()); +/// (&mut future).await; +/// } +/// ``` +/// +/// # Examples +/// +/// Using with select: +/// +/// ``` +/// use tokio::{pin, select}; +/// use tokio_stream::{self as stream, StreamExt}; +/// +/// async fn my_async_fn() { +/// // async logic here +/// } +/// +/// #[tokio::main] +/// async fn main() { +/// let mut stream = stream::iter(vec![1, 2, 3, 4]); +/// +/// let future = my_async_fn(); +/// pin!(future); +/// +/// loop { +/// select! { +/// _ = &mut future => { +/// // Stop looping `future` will be polled after completion +/// break; +/// } +/// Some(val) = stream.next() => { +/// println!("got value = {}", val); +/// } +/// } +/// } +/// } +/// ``` +/// +/// Because assigning to a variable followed by pinning is common, there is also +/// a variant of the macro that supports doing both in one go. +/// +/// ``` +/// use tokio::{pin, select}; +/// +/// async fn my_async_fn() { +/// // async logic here +/// } +/// +/// #[tokio::main] +/// async fn main() { +/// pin! { +/// let future1 = my_async_fn(); +/// let future2 = my_async_fn(); +/// } +/// +/// select! { +/// _ = &mut future1 => {} +/// _ = &mut future2 => {} +/// } +/// } +/// ``` +#[macro_export] +macro_rules! pin { + ($($x:ident),*) => { $( + // Move the value to ensure that it is owned + let mut $x = $x; + // Shadow the original binding so that it can't be directly accessed + // ever again. + #[allow(unused_mut)] + let mut $x = unsafe { + $crate::macros::support::Pin::new_unchecked(&mut $x) + }; + )* }; + ($( + let $x:ident = $init:expr; + )*) => { + $( + let $x = $init; + $crate::pin!($x); + )* + }; +} diff --git a/third_party/rust/tokio/src/macros/ready.rs b/third_party/rust/tokio/src/macros/ready.rs new file mode 100644 index 0000000000..1f48623b80 --- /dev/null +++ b/third_party/rust/tokio/src/macros/ready.rs @@ -0,0 +1,8 @@ +macro_rules! ready { + ($e:expr $(,)?) => { + match $e { + std::task::Poll::Ready(t) => t, + std::task::Poll::Pending => return std::task::Poll::Pending, + } + }; +} diff --git a/third_party/rust/tokio/src/macros/scoped_tls.rs b/third_party/rust/tokio/src/macros/scoped_tls.rs new file mode 100644 index 0000000000..f2504cbadf --- /dev/null +++ b/third_party/rust/tokio/src/macros/scoped_tls.rs @@ -0,0 +1,77 @@ +use crate::loom::thread::LocalKey; + +use std::cell::Cell; +use std::marker; + +/// Sets a reference as a thread-local. +macro_rules! scoped_thread_local { + ($(#[$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/third_party/rust/tokio/src/macros/select.rs b/third_party/rust/tokio/src/macros/select.rs new file mode 100644 index 0000000000..051f8cb72a --- /dev/null +++ b/third_party/rust/tokio/src/macros/select.rs @@ -0,0 +1,1001 @@ +/// 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 +/// blocks. +/// +/// The `select!` macro accepts one or more branches with the following pattern: +/// +/// ```text +/// <pattern> = <async expression> (, if <precondition>)? => <handler>, +/// ``` +/// +/// Additionally, the `select!` macro may include a single, optional `else` +/// branch, which evaluates if none of the other branches match their patterns: +/// +/// ```text +/// else => <expression> +/// ``` +/// +/// The macro aggregates all `<async expression>` expressions and runs them +/// concurrently on the **current** task. Once the **first** expression +/// completes with a value that matches its `<pattern>`, the `select!` macro +/// returns the result of evaluating the completed branch's `<handler>` +/// expression. +/// +/// Additionally, each branch may include an optional `if` precondition. If the +/// precondition returns `false`, then the branch is disabled. The provided +/// `<async expression>` is still evaluated but the resulting future is never +/// polled. This capability is useful when using `select!` within a loop. +/// +/// The complete lifecycle of a `select!` expression is as follows: +/// +/// 1. Evaluate all provided `<precondition>` expressions. If the precondition +/// returns `false`, disable the branch for the remainder of the current call +/// to `select!`. Re-entering `select!` due to a loop clears the "disabled" +/// state. +/// 2. Aggregate the `<async expression>`s from each branch, including the +/// disabled ones. If the branch is disabled, `<async expression>` is still +/// evaluated, but the resulting future is not polled. +/// 3. Concurrently await on the results for all remaining `<async expression>`s. +/// 4. Once an `<async expression>` returns a value, attempt to apply the value +/// to the provided `<pattern>`, if the pattern matches, evaluate `<handler>` +/// and return. If the pattern **does not** match, disable the current branch +/// and for the remainder of the current call to `select!`. Continue from step 3. +/// 5. If **all** branches are disabled, evaluate the `else` expression. If no +/// else branch is provided, panic. +/// +/// # Runtime characteristics +/// +/// By running all async expressions on the current task, the expressions are +/// able to run **concurrently** but not in **parallel**. This means all +/// expressions are run on the same thread and if one branch blocks the thread, +/// all other expressions will be unable to continue. If parallelism is +/// required, spawn each async expression using [`tokio::spawn`] and pass the +/// join handle to `select!`. +/// +/// [`tokio::spawn`]: crate::spawn +/// +/// # Fairness +/// +/// By default, `select!` randomly picks a branch to check first. This provides +/// some level of fairness when calling `select!` in a loop with branches that +/// are always ready. +/// +/// This behavior can be overridden by adding `biased;` to the beginning of the +/// macro usage. See the examples for details. This will cause `select` to poll +/// the futures in the order they appear from top to bottom. There are a few +/// reasons you may want this: +/// +/// - The random number generation of `tokio::select!` has a non-zero CPU cost +/// - Your futures may interact in a way where known polling order is significant +/// +/// But there is an important caveat to this mode. It becomes your responsibility +/// to ensure that the polling order of your futures is fair. If for example you +/// are selecting between a stream and a shutdown future, and the stream has a +/// huge volume of messages and zero or nearly zero time between them, you should +/// place the shutdown future earlier in the `select!` list to ensure that it is +/// always polled, and will not be ignored due to the stream being constantly +/// ready. +/// +/// # Panics +/// +/// The `select!` macro panics if all branches are disabled **and** there is no +/// provided `else` branch. A branch is disabled when the provided `if` +/// precondition returns `false` **or** when the pattern does not match the +/// result of `<async expression>`. +/// +/// # Cancellation safety +/// +/// When using `select!` in a loop to receive messages from multiple sources, +/// you should make sure that the receive call is cancellation safe to avoid +/// losing messages. This section goes through various common methods and +/// describes whether they are cancel safe. The lists in this section are not +/// exhaustive. +/// +/// The following methods are cancellation safe: +/// +/// * [`tokio::sync::mpsc::Receiver::recv`](crate::sync::mpsc::Receiver::recv) +/// * [`tokio::sync::mpsc::UnboundedReceiver::recv`](crate::sync::mpsc::UnboundedReceiver::recv) +/// * [`tokio::sync::broadcast::Receiver::recv`](crate::sync::broadcast::Receiver::recv) +/// * [`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::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` +/// * [`tokio::io::AsyncWriteExt::write_buf`](crate::io::AsyncWriteExt::write_buf) on any `AsyncWrite` +/// * [`tokio_stream::StreamExt::next`](https://docs.rs/tokio-stream/0.1/tokio_stream/trait.StreamExt.html#method.next) on any `Stream` +/// * [`futures::stream::StreamExt::next`](https://docs.rs/futures/0.3/futures/stream/trait.StreamExt.html#method.next) on any `Stream` +/// +/// The following methods are not cancellation safe and can lead to loss of data: +/// +/// * [`tokio::io::AsyncReadExt::read_exact`](crate::io::AsyncReadExt::read_exact) +/// * [`tokio::io::AsyncReadExt::read_to_end`](crate::io::AsyncReadExt::read_to_end) +/// * [`tokio::io::AsyncReadExt::read_to_string`](crate::io::AsyncReadExt::read_to_string) +/// * [`tokio::io::AsyncWriteExt::write_all`](crate::io::AsyncWriteExt::write_all) +/// +/// The following methods are not cancellation safe because they use a queue for +/// fairness and cancellation makes you lose your place in the queue: +/// +/// * [`tokio::sync::Mutex::lock`](crate::sync::Mutex::lock) +/// * [`tokio::sync::RwLock::read`](crate::sync::RwLock::read) +/// * [`tokio::sync::RwLock::write`](crate::sync::RwLock::write) +/// * [`tokio::sync::Semaphore::acquire`](crate::sync::Semaphore::acquire) +/// * [`tokio::sync::Notify::notified`](crate::sync::Notify::notified) +/// +/// To determine whether your own methods are cancellation safe, look for the +/// location of uses of `.await`. This is because when an asynchronous method is +/// cancelled, that always happens at an `.await`. If your function behaves +/// correctly even if it is restarted while waiting at an `.await`, then it is +/// cancellation safe. +/// +/// 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 +/// read data is lost. +/// +/// # Examples +/// +/// Basic select with two branches. +/// +/// ``` +/// async fn do_stuff_async() { +/// // async work +/// } +/// +/// async fn more_async_work() { +/// // more here +/// } +/// +/// #[tokio::main] +/// async fn main() { +/// tokio::select! { +/// _ = do_stuff_async() => { +/// println!("do_stuff_async() completed first") +/// } +/// _ = more_async_work() => { +/// println!("more_async_work() completed first") +/// } +/// }; +/// } +/// ``` +/// +/// Basic stream selecting. +/// +/// ``` +/// use tokio_stream::{self as stream, StreamExt}; +/// +/// #[tokio::main] +/// async fn main() { +/// let mut stream1 = stream::iter(vec![1, 2, 3]); +/// let mut stream2 = stream::iter(vec![4, 5, 6]); +/// +/// let next = tokio::select! { +/// v = stream1.next() => v.unwrap(), +/// v = stream2.next() => v.unwrap(), +/// }; +/// +/// assert!(next == 1 || next == 4); +/// } +/// ``` +/// +/// Collect the contents of two streams. In this example, we rely on pattern +/// matching and the fact that `stream::iter` is "fused", i.e. once the stream +/// is complete, all calls to `next()` return `None`. +/// +/// ``` +/// use tokio_stream::{self as stream, StreamExt}; +/// +/// #[tokio::main] +/// async fn main() { +/// let mut stream1 = stream::iter(vec![1, 2, 3]); +/// let mut stream2 = stream::iter(vec![4, 5, 6]); +/// +/// let mut values = vec![]; +/// +/// loop { +/// tokio::select! { +/// Some(v) = stream1.next() => values.push(v), +/// Some(v) = stream2.next() => values.push(v), +/// else => break, +/// } +/// } +/// +/// values.sort(); +/// assert_eq!(&[1, 2, 3, 4, 5, 6], &values[..]); +/// } +/// ``` +/// +/// Using the same future in multiple `select!` expressions can be done by passing +/// a reference to the future. Doing so requires the future to be [`Unpin`]. A +/// future can be made [`Unpin`] by either using [`Box::pin`] or stack pinning. +/// +/// [`Unpin`]: std::marker::Unpin +/// [`Box::pin`]: std::boxed::Box::pin +/// +/// Here, a stream is consumed for at most 1 second. +/// +/// ``` +/// use tokio_stream::{self as stream, StreamExt}; +/// use tokio::time::{self, Duration}; +/// +/// #[tokio::main] +/// async fn main() { +/// let mut stream = stream::iter(vec![1, 2, 3]); +/// let sleep = time::sleep(Duration::from_secs(1)); +/// tokio::pin!(sleep); +/// +/// loop { +/// tokio::select! { +/// maybe_v = stream.next() => { +/// if let Some(v) = maybe_v { +/// println!("got = {}", v); +/// } else { +/// break; +/// } +/// } +/// _ = &mut sleep => { +/// println!("timeout"); +/// break; +/// } +/// } +/// } +/// } +/// ``` +/// +/// Joining two values using `select!`. +/// +/// ``` +/// use tokio::sync::oneshot; +/// +/// #[tokio::main] +/// async fn main() { +/// let (tx1, mut rx1) = oneshot::channel(); +/// let (tx2, mut rx2) = oneshot::channel(); +/// +/// tokio::spawn(async move { +/// tx1.send("first").unwrap(); +/// }); +/// +/// tokio::spawn(async move { +/// tx2.send("second").unwrap(); +/// }); +/// +/// let mut a = None; +/// let mut b = None; +/// +/// while a.is_none() || b.is_none() { +/// tokio::select! { +/// v1 = (&mut rx1), if a.is_none() => a = Some(v1.unwrap()), +/// v2 = (&mut rx2), if b.is_none() => b = Some(v2.unwrap()), +/// } +/// } +/// +/// let res = (a.unwrap(), b.unwrap()); +/// +/// assert_eq!(res.0, "first"); +/// assert_eq!(res.1, "second"); +/// } +/// ``` +/// +/// Using the `biased;` mode to control polling order. +/// +/// ``` +/// #[tokio::main] +/// async fn main() { +/// let mut count = 0u8; +/// +/// loop { +/// tokio::select! { +/// // If you run this example without `biased;`, the polling order is +/// // pseudo-random, and the assertions on the value of count will +/// // (probably) fail. +/// biased; +/// +/// _ = async {}, if count < 1 => { +/// count += 1; +/// assert_eq!(count, 1); +/// } +/// _ = async {}, if count < 2 => { +/// count += 1; +/// assert_eq!(count, 2); +/// } +/// _ = async {}, if count < 3 => { +/// count += 1; +/// assert_eq!(count, 3); +/// } +/// _ = async {}, if count < 4 => { +/// count += 1; +/// assert_eq!(count, 4); +/// } +/// +/// else => { +/// break; +/// } +/// }; +/// } +/// } +/// ``` +/// +/// ## Avoid racy `if` preconditions +/// +/// Given that `if` preconditions are used to disable `select!` branches, some +/// caution must be used to avoid missing values. +/// +/// For example, here is **incorrect** usage of `sleep` with `if`. The objective +/// is to repeatedly run an asynchronous task for up to 50 milliseconds. +/// However, there is a potential for the `sleep` completion to be missed. +/// +/// ```no_run,should_panic +/// use tokio::time::{self, Duration}; +/// +/// async fn some_async_work() { +/// // do work +/// } +/// +/// #[tokio::main] +/// async fn main() { +/// let sleep = time::sleep(Duration::from_millis(50)); +/// tokio::pin!(sleep); +/// +/// while !sleep.is_elapsed() { +/// tokio::select! { +/// _ = &mut sleep, if !sleep.is_elapsed() => { +/// println!("operation timed out"); +/// } +/// _ = some_async_work() => { +/// println!("operation completed"); +/// } +/// } +/// } +/// +/// panic!("This example shows how not to do it!"); +/// } +/// ``` +/// +/// In the above example, `sleep.is_elapsed()` may return `true` even if +/// `sleep.poll()` never returned `Ready`. This opens up a potential race +/// condition where `sleep` expires between the `while !sleep.is_elapsed()` +/// check and the call to `select!` resulting in the `some_async_work()` call to +/// run uninterrupted despite the sleep having elapsed. +/// +/// One way to write the above example without the race would be: +/// +/// ``` +/// use tokio::time::{self, Duration}; +/// +/// async fn some_async_work() { +/// # time::sleep(Duration::from_millis(10)).await; +/// // do work +/// } +/// +/// #[tokio::main] +/// async fn main() { +/// let sleep = time::sleep(Duration::from_millis(50)); +/// tokio::pin!(sleep); +/// +/// loop { +/// tokio::select! { +/// _ = &mut sleep => { +/// println!("operation timed out"); +/// break; +/// } +/// _ = some_async_work() => { +/// println!("operation completed"); +/// } +/// } +/// } +/// } +/// ``` +#[macro_export] +#[cfg_attr(docsrs, doc(cfg(feature = "macros")))] +macro_rules! select { + // Uses a declarative macro to do **most** of the work. While it is possible + // to implement fully with a declarative macro, a procedural macro is used + // to enable improved error messages. + // + // The macro is structured as a tt-muncher. All branches are processed and + // normalized. Once the input is normalized, it is passed to the top-most + // rule. When entering the macro, `@{ }` is inserted at the front. This is + // used to collect the normalized input. + // + // The macro only recurses once per branch. This allows using `select!` + // without requiring the user to increase the recursion limit. + + // All input is normalized, now transform. + (@ { + // The index of the future to poll first (in bias mode), or the RNG + // expression to use to pick a future to poll first. + start=$start:expr; + + // One `_` for each branch in the `select!` macro. Passing this to + // `count!` converts $skip to an integer. + ( $($count:tt)* ) + + // Normalized select branches. `( $skip )` is a set of `_` characters. + // There is one `_` for each select branch **before** this one. Given + // that all input futures are stored in a tuple, $skip is useful for + // generating a pattern to reference the future for the current branch. + // $skip is also used as an argument to `count!`, returning the index of + // the current select branch. + $( ( $($skip:tt)* ) $bind:pat = $fut:expr, if $c:expr => $handle:expr, )+ + + // Fallback expression used when all select branches have been disabled. + ; $else:expr + + }) => {{ + // Enter a context where stable "function-like" proc macros can be used. + // + // This module is defined within a scope and should not leak out of this + // macro. + mod util { + // Generate an enum with one variant per select branch + $crate::select_priv_declare_output_enum!( ( $($count)* ) ); + } + + // `tokio::macros::support` is a public, but doc(hidden) module + // including a re-export of all types needed by this macro. + use $crate::macros::support::Future; + use $crate::macros::support::Pin; + use $crate::macros::support::Poll::{Ready, Pending}; + + const BRANCHES: u32 = $crate::count!( $($count)* ); + + let mut disabled: 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)* ); + disabled |= mask; + } + )* + + // Create a scope to separate polling from handling the output. This + // adds borrow checker flexibility when using the macro. + let mut output = { + // Safety: Nothing must be moved out of `futures`. This is to + // satisfy the requirement of `Pin::new_unchecked` called below. + let mut futures = ( $( $fut , )+ ); + + $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 + // disabled. + let mut is_pending = false; + + // Choose a starting index to begin polling the futures at. In + // practice, this will either be a pseudo-randomly generated + // number by default, or the constant 0 if `biased;` is + // supplied. + let start = $start; + + for i in 0..BRANCHES { + let branch; + #[allow(clippy::modulo_one)] + { + branch = (start + i) % BRANCHES; + } + match branch { + $( + #[allow(unreachable_code)] + $crate::count!( $($skip)* ) => { + // First, if the future has previously been + // disabled, do not poll it again. This is done + // by checking the associated bit in the + // `disabled` bit field. + let mask = 1 << branch; + + if disabled & mask == mask { + // The future has been disabled. + continue; + } + + // 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 it + let out = match Future::poll(fut, cx) { + Ready(out) => out, + Pending => { + // Track that at least one future is + // still pending and continue polling. + is_pending = true; + continue; + } + }; + + // Disable the future from future polling. + disabled |= mask; + + // The future returned a value, check if matches + // the specified pattern. + #[allow(unused_variables)] + #[allow(unused_mut)] + match &out { + $crate::select_priv_clean_pattern!($bind) => {} + _ => continue, + } + + // The select is complete, return the value + return Ready($crate::select_variant!(util::Out, ($($skip)*))(out)); + } + )* + _ => unreachable!("reaching this means there probably is an off by one bug"), + } + } + + if is_pending { + Pending + } else { + // All branches have been disabled. + Ready(util::Out::Disabled) + } + }).await + }; + + match output { + $( + $crate::select_variant!(util::Out, ($($skip)*) ($bind)) => $handle, + )* + util::Out::Disabled => $else, + _ => unreachable!("failed to match bind"), + } + }}; + + // ==== Normalize ===== + + // These rules match a single `select!` branch and normalize it for + // processing by the first rule. + + (@ { start=$start:expr; $($t:tt)* } ) => { + // No `else` branch + $crate::select!(@{ start=$start; $($t)*; panic!("all branches are disabled and there is no else branch") }) + }; + (@ { start=$start:expr; $($t:tt)* } else => $else:expr $(,)?) => { + $crate::select!(@{ start=$start; $($t)*; $else }) + }; + (@ { start=$start:expr; ( $($s:tt)* ) $($t:tt)* } $p:pat = $f:expr, if $c:expr => $h:block, $($r:tt)* ) => { + $crate::select!(@{ start=$start; ($($s)* _) $($t)* ($($s)*) $p = $f, if $c => $h, } $($r)*) + }; + (@ { start=$start:expr; ( $($s:tt)* ) $($t:tt)* } $p:pat = $f:expr => $h:block, $($r:tt)* ) => { + $crate::select!(@{ start=$start; ($($s)* _) $($t)* ($($s)*) $p = $f, if true => $h, } $($r)*) + }; + (@ { start=$start:expr; ( $($s:tt)* ) $($t:tt)* } $p:pat = $f:expr, if $c:expr => $h:block $($r:tt)* ) => { + $crate::select!(@{ start=$start; ($($s)* _) $($t)* ($($s)*) $p = $f, if $c => $h, } $($r)*) + }; + (@ { start=$start:expr; ( $($s:tt)* ) $($t:tt)* } $p:pat = $f:expr => $h:block $($r:tt)* ) => { + $crate::select!(@{ start=$start; ($($s)* _) $($t)* ($($s)*) $p = $f, if true => $h, } $($r)*) + }; + (@ { start=$start:expr; ( $($s:tt)* ) $($t:tt)* } $p:pat = $f:expr, if $c:expr => $h:expr ) => { + $crate::select!(@{ start=$start; ($($s)* _) $($t)* ($($s)*) $p = $f, if $c => $h, }) + }; + (@ { start=$start:expr; ( $($s:tt)* ) $($t:tt)* } $p:pat = $f:expr => $h:expr ) => { + $crate::select!(@{ start=$start; ($($s)* _) $($t)* ($($s)*) $p = $f, if true => $h, }) + }; + (@ { start=$start:expr; ( $($s:tt)* ) $($t:tt)* } $p:pat = $f:expr, if $c:expr => $h:expr, $($r:tt)* ) => { + $crate::select!(@{ start=$start; ($($s)* _) $($t)* ($($s)*) $p = $f, if $c => $h, } $($r)*) + }; + (@ { start=$start:expr; ( $($s:tt)* ) $($t:tt)* } $p:pat = $f:expr => $h:expr, $($r:tt)* ) => { + $crate::select!(@{ start=$start; ($($s)* _) $($t)* ($($s)*) $p = $f, if true => $h, } $($r)*) + }; + + // ===== Entry point ===== + + (biased; $p:pat = $($t:tt)* ) => { + $crate::select!(@{ start=0; () } $p = $($t)*) + }; + + ( $p:pat = $($t:tt)* ) => { + // Randomly generate a starting point. This makes `select!` a bit more + // fair and avoids always polling the first future. + $crate::select!(@{ start={ $crate::macros::support::thread_rng_n(BRANCHES) }; () } $p = $($t)*) + }; + () => { + compile_error!("select! requires at least one branch.") + }; +} + +// And here... we manually list out matches for up to 64 branches... I'm not +// happy about it either, but this is how we manage to use a declarative macro! + +#[macro_export] +#[doc(hidden)] +macro_rules! count { + () => { + 0 + }; + (_) => { + 1 + }; + (_ _) => { + 2 + }; + (_ _ _) => { + 3 + }; + (_ _ _ _) => { + 4 + }; + (_ _ _ _ _) => { + 5 + }; + (_ _ _ _ _ _) => { + 6 + }; + (_ _ _ _ _ _ _) => { + 7 + }; + (_ _ _ _ _ _ _ _) => { + 8 + }; + (_ _ _ _ _ _ _ _ _) => { + 9 + }; + (_ _ _ _ _ _ _ _ _ _) => { + 10 + }; + (_ _ _ _ _ _ _ _ _ _ _) => { + 11 + }; + (_ _ _ _ _ _ _ _ _ _ _ _) => { + 12 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _) => { + 13 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 14 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 15 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 16 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 17 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 18 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 19 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 20 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 21 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 22 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 23 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 24 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 25 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 26 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 27 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 28 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 29 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 30 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 31 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 32 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 33 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 34 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 35 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 36 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 37 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 38 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 39 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 40 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 41 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 42 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 43 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 44 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 45 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 46 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 47 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 48 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 49 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 50 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 51 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 52 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 53 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 54 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 55 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 56 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 57 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 58 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 59 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 60 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 61 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 62 + }; + (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) => { + 63 + }; +} + +#[macro_export] +#[doc(hidden)] +macro_rules! select_variant { + ($($p:ident)::*, () $($t:tt)*) => { + $($p)::*::_0 $($t)* + }; + ($($p:ident)::*, (_) $($t:tt)*) => { + $($p)::*::_1 $($t)* + }; + ($($p:ident)::*, (_ _) $($t:tt)*) => { + $($p)::*::_2 $($t)* + }; + ($($p:ident)::*, (_ _ _) $($t:tt)*) => { + $($p)::*::_3 $($t)* + }; + ($($p:ident)::*, (_ _ _ _) $($t:tt)*) => { + $($p)::*::_4 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _) $($t:tt)*) => { + $($p)::*::_5 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_6 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_7 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_8 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_9 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_10 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_11 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_12 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_13 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_14 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_15 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_16 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_17 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_18 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_19 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_20 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_21 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_22 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_23 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_24 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_25 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_26 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_27 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_28 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_29 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_30 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_31 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_32 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_33 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_34 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_35 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_36 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_37 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_38 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_39 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_40 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_41 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_42 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_43 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_44 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_45 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_46 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_47 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_48 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_49 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_50 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_51 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_52 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_53 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_54 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_55 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_56 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_57 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_58 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_59 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_60 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_61 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_62 $($t)* + }; + ($($p:ident)::*, (_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _) $($t:tt)*) => { + $($p)::*::_63 $($t)* + }; +} diff --git a/third_party/rust/tokio/src/macros/support.rs b/third_party/rust/tokio/src/macros/support.rs new file mode 100644 index 0000000000..7f11bc6800 --- /dev/null +++ b/third_party/rust/tokio/src/macros/support.rs @@ -0,0 +1,9 @@ +cfg_macros! { + pub use crate::future::poll_fn; + pub use crate::future::maybe_done::maybe_done; + pub use crate::util::thread_rng_n; +} + +pub use std::future::Future; +pub use std::pin::Pin; +pub use std::task::Poll; diff --git a/third_party/rust/tokio/src/macros/thread_local.rs b/third_party/rust/tokio/src/macros/thread_local.rs new file mode 100644 index 0000000000..d848947350 --- /dev/null +++ b/third_party/rust/tokio/src/macros/thread_local.rs @@ -0,0 +1,4 @@ +#[cfg(all(loom, test))] +macro_rules! thread_local { + ($($tts:tt)+) => { loom::thread_local!{ $($tts)+ } } +} diff --git a/third_party/rust/tokio/src/macros/trace.rs b/third_party/rust/tokio/src/macros/trace.rs new file mode 100644 index 0000000000..80a257e189 --- /dev/null +++ b/third_party/rust/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/third_party/rust/tokio/src/macros/try_join.rs b/third_party/rust/tokio/src/macros/try_join.rs new file mode 100644 index 0000000000..6d3a893b7e --- /dev/null +++ b/third_party/rust/tokio/src/macros/try_join.rs @@ -0,0 +1,171 @@ +/// 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 +/// blocks. +/// +/// Similar to [`join!`], the `try_join!` macro takes a list of async +/// expressions and evaluates them concurrently on the same task. Each async +/// expression evaluates to a future and the futures from each expression are +/// multiplexed on the current task. The `try_join!` macro returns when **all** +/// branches return with `Ok` or when the **first** branch returns with `Err`. +/// +/// [`join!`]: macro@join +/// +/// # Notes +/// +/// The supplied futures are stored inline and does not require allocating a +/// `Vec`. +/// +/// ### Runtime characteristics +/// +/// By running all async expressions on the current task, the expressions are +/// able to run **concurrently** but not in **parallel**. This means all +/// expressions are run on the same thread and if one branch blocks the thread, +/// all other expressions will be unable to continue. If parallelism is +/// required, spawn each async expression using [`tokio::spawn`] and pass the +/// join handle to `try_join!`. +/// +/// [`tokio::spawn`]: crate::spawn +/// +/// # Examples +/// +/// Basic try_join with two branches. +/// +/// ``` +/// async fn do_stuff_async() -> Result<(), &'static str> { +/// // async work +/// # Ok(()) +/// } +/// +/// async fn more_async_work() -> Result<(), &'static str> { +/// // more here +/// # Ok(()) +/// } +/// +/// #[tokio::main] +/// async fn main() { +/// let res = tokio::try_join!( +/// do_stuff_async(), +/// more_async_work()); +/// +/// match res { +/// Ok((first, second)) => { +/// // do something with the values +/// } +/// Err(err) => { +/// println!("processing failed; error = {}", err); +/// } +/// } +/// } +/// ``` +/// +/// 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 { + (@ { + // One `_` for each branch in the `try_join!` macro. This is not used once + // normalization is complete. + ( $($count:tt)* ) + + // Normalized try_join! branches + $( ( $($skip:tt)* ) $e:expr, )* + + }) => {{ + use $crate::macros::support::{maybe_done, poll_fn, Future, Pin}; + use $crate::macros::support::Poll::{Ready, Pending}; + + // Safety: nothing must be moved out of `futures`. This is to satisfy + // the requirement of `Pin::new_unchecked` called below. + let mut futures = ( $( maybe_done($e), )* ); + + poll_fn(move |cx| { + let mut is_pending = false; + + $( + // 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 is_pending { + Pending + } else { + Ready(Ok(($({ + // 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) }; + + fut + .take_output() + .expect("expected completed future") + .ok() + .expect("expected Ok(_)") + },)*))) + } + }).await + }}; + + // ===== Normalize ===== + + (@ { ( $($s:tt)* ) $($t:tt)* } $e:expr, $($r:tt)* ) => { + $crate::try_join!(@{ ($($s)* _) $($t)* ($($s)*) $e, } $($r)*) + }; + + // ===== Entry point ===== + + ( $($e:expr),* $(,)?) => { + $crate::try_join!(@{ () } $($e,)*) + }; +} |