diff options
Diffstat (limited to 'vendor/rayon-core/src/lib.rs')
| -rw-r--r-- | vendor/rayon-core/src/lib.rs | 24 |
1 files changed, 23 insertions, 1 deletions
diff --git a/vendor/rayon-core/src/lib.rs b/vendor/rayon-core/src/lib.rs index b31a2d7e0..c9694ee16 100644 --- a/vendor/rayon-core/src/lib.rs +++ b/vendor/rayon-core/src/lib.rs @@ -26,7 +26,24 @@ //! [`join()`]: struct.ThreadPool.html#method.join //! [`ThreadPoolBuilder`]: struct.ThreadPoolBuilder.html //! -//! ## Restricting multiple versions +//! # Global fallback when threading is unsupported +//! +//! Rayon uses `std` APIs for threading, but some targets have incomplete implementations that +//! always return `Unsupported` errors. The WebAssembly `wasm32-unknown-unknown` and `wasm32-wasi` +//! targets are notable examples of this. Rather than panicking on the unsupported error when +//! creating the implicit global threadpool, Rayon configures a fallback mode instead. +//! +//! This fallback mode mostly functions as if it were using a single-threaded "pool", like setting +//! `RAYON_NUM_THREADS=1`. For example, `join` will execute its two closures sequentially, since +//! there is no other thread to share the work. However, since the pool is not running independent +//! of the main thread, non-blocking calls like `spawn` may not execute at all, unless a lower- +//! priority call like `broadcast` gives them an opening. The fallback mode does not try to emulate +//! anything like thread preemption or `async` task switching, but `yield_now` or `yield_local` +//! can also volunteer execution time. +//! +//! Explicit `ThreadPoolBuilder` methods always report their error without any fallback. +//! +//! # Restricting multiple versions //! //! In order to ensure proper coordination between threadpools, and especially //! to make sure there's only one global threadpool, `rayon-core` is actively @@ -85,6 +102,7 @@ pub use self::spawn::{spawn, spawn_fifo}; pub use self::thread_pool::current_thread_has_pending_tasks; pub use self::thread_pool::current_thread_index; pub use self::thread_pool::ThreadPool; +pub use self::thread_pool::{yield_local, yield_now, Yield}; use self::registry::{CustomSpawn, DefaultSpawn, ThreadSpawn}; @@ -707,6 +725,10 @@ impl ThreadPoolBuildError { fn new(kind: ErrorKind) -> ThreadPoolBuildError { ThreadPoolBuildError { kind } } + + fn is_unsupported(&self) -> bool { + matches!(&self.kind, ErrorKind::IOError(e) if e.kind() == io::ErrorKind::Unsupported) + } } const GLOBAL_POOL_ALREADY_INITIALIZED: &str = |