futures-executor-0.3.31/.cargo_vcs_info.json0000644000000001560000000000100144530ustar { "git": { "sha1": "1e052816b09890925cfdfcbe8d390cdaae5e4c38" }, "path_in_vcs": "futures-executor" }futures-executor-0.3.31/Cargo.toml0000644000000035010000000000100124460ustar # THIS FILE IS AUTOMATICALLY GENERATED BY CARGO # # When uploading crates to the registry Cargo will automatically # "normalize" Cargo.toml files for maximal compatibility # with all versions of Cargo and also rewrite `path` dependencies # to registry (e.g., crates.io) dependencies. # # If you are reading this file be aware that the original Cargo.toml # will likely look very different (and much more reasonable). # See Cargo.toml.orig for the original contents. [package] edition = "2018" rust-version = "1.56" name = "futures-executor" version = "0.3.31" build = false autobins = false autoexamples = false autotests = false autobenches = false description = """ Executors for asynchronous tasks based on the futures-rs library. """ homepage = "https://rust-lang.github.io/futures-rs" readme = "README.md" license = "MIT OR Apache-2.0" repository = "https://github.com/rust-lang/futures-rs" [package.metadata.docs.rs] all-features = true rustdoc-args = [ "--cfg", "docsrs", ] [lib] name = "futures_executor" path = "src/lib.rs" [[test]] name = "local_pool" path = "tests/local_pool.rs" [[bench]] name = "thread_notify" path = "benches/thread_notify.rs" [dependencies.futures-core] version = "0.3.31" default-features = false [dependencies.futures-task] version = "0.3.31" default-features = false [dependencies.futures-util] version = "0.3.31" default-features = false [dependencies.num_cpus] version = "1.8.0" optional = true [dev-dependencies] [features] default = ["std"] std = [ "futures-core/std", "futures-task/std", "futures-util/std", ] thread-pool = [ "std", "num_cpus", ] [lints.rust] missing_debug_implementations = "warn" rust_2018_idioms = "warn" single_use_lifetimes = "warn" unreachable_pub = "warn" [lints.rust.unexpected_cfgs] level = "warn" priority = 0 check-cfg = ["cfg(futures_sanitizer)"] futures-executor-0.3.31/Cargo.toml.orig000064400000000000000000000017211046102023000161310ustar 00000000000000[package] name = "futures-executor" version = "0.3.31" edition = "2018" rust-version = "1.56" license = "MIT OR Apache-2.0" repository = "https://github.com/rust-lang/futures-rs" homepage = "https://rust-lang.github.io/futures-rs" description = """ Executors for asynchronous tasks based on the futures-rs library. """ [features] default = ["std"] std = ["futures-core/std", "futures-task/std", "futures-util/std"] thread-pool = ["std", "num_cpus"] [dependencies] futures-core = { path = "../futures-core", version = "0.3.31", default-features = false } futures-task = { path = "../futures-task", version = "0.3.31", default-features = false } futures-util = { path = "../futures-util", version = "0.3.31", default-features = false } num_cpus = { version = "1.8.0", optional = true } [dev-dependencies] futures = { path = "../futures", features = ["thread-pool"] } [package.metadata.docs.rs] all-features = true rustdoc-args = ["--cfg", "docsrs"] [lints] workspace = true futures-executor-0.3.31/LICENSE-APACHE000064400000000000000000000251721046102023000151740ustar 00000000000000 Apache License Version 2.0, January 2004 http://www.apache.org/licenses/ TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 1. Definitions. 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We also recommend that a file or class name and description of purpose be included on the same "printed page" as the copyright notice for easier identification within third-party archives. Copyright (c) 2016 Alex Crichton Copyright (c) 2017 The Tokio Authors Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. futures-executor-0.3.31/LICENSE-MIT000064400000000000000000000021061046102023000146740ustar 00000000000000Copyright (c) 2016 Alex Crichton Copyright (c) 2017 The Tokio Authors Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. futures-executor-0.3.31/README.md000064400000000000000000000011321046102023000145150ustar 00000000000000# futures-executor Executors for asynchronous tasks based on the futures-rs library. ## Usage Add this to your `Cargo.toml`: ```toml [dependencies] futures-executor = "0.3" ``` The current `futures-executor` requires Rust 1.56 or later. ## License Licensed under either of [Apache License, Version 2.0](LICENSE-APACHE) or [MIT license](LICENSE-MIT) at your option. Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions. futures-executor-0.3.31/benches/thread_notify.rs000064400000000000000000000044101046102023000200540ustar 00000000000000#![feature(test)] extern crate test; use crate::test::Bencher; use futures::executor::block_on; use futures::future::Future; use futures::task::{Context, Poll, Waker}; use std::pin::Pin; #[bench] fn thread_yield_single_thread_one_wait(b: &mut Bencher) { const NUM: usize = 10_000; struct Yield { rem: usize, } impl Future for Yield { type Output = (); fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll { if self.rem == 0 { Poll::Ready(()) } else { self.rem -= 1; cx.waker().wake_by_ref(); Poll::Pending } } } b.iter(|| { let y = Yield { rem: NUM }; block_on(y); }); } #[bench] fn thread_yield_single_thread_many_wait(b: &mut Bencher) { const NUM: usize = 10_000; struct Yield { rem: usize, } impl Future for Yield { type Output = (); fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll { if self.rem == 0 { Poll::Ready(()) } else { self.rem -= 1; cx.waker().wake_by_ref(); Poll::Pending } } } b.iter(|| { for _ in 0..NUM { let y = Yield { rem: 1 }; block_on(y); } }); } #[bench] fn thread_yield_multi_thread(b: &mut Bencher) { use std::sync::mpsc; use std::thread; const NUM: usize = 1_000; let (tx, rx) = mpsc::sync_channel::(10_000); struct Yield { rem: usize, tx: mpsc::SyncSender, } impl Unpin for Yield {} impl Future for Yield { type Output = (); fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll { if self.rem == 0 { Poll::Ready(()) } else { self.rem -= 1; self.tx.send(cx.waker().clone()).unwrap(); Poll::Pending } } } thread::spawn(move || { while let Ok(task) = rx.recv() { task.wake(); } }); b.iter(move || { let y = Yield { rem: NUM, tx: tx.clone() }; block_on(y); }); } futures-executor-0.3.31/src/enter.rs000064400000000000000000000035551046102023000155230ustar 00000000000000use std::cell::Cell; use std::fmt; std::thread_local!(static ENTERED: Cell = Cell::new(false)); /// Represents an executor context. /// /// For more details, see [`enter` documentation](enter()). pub struct Enter { _priv: (), } /// An error returned by `enter` if an execution scope has already been /// entered. pub struct EnterError { _priv: (), } impl fmt::Debug for EnterError { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { f.debug_struct("EnterError").finish() } } impl fmt::Display for EnterError { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { write!(f, "an execution scope has already been entered") } } impl std::error::Error for EnterError {} /// Marks the current thread as being within the dynamic extent of an /// executor. /// /// Executor implementations should call this function before beginning to /// execute a task, and drop the returned [`Enter`](Enter) value after /// completing task execution: /// /// ``` /// use futures::executor::enter; /// /// let enter = enter().expect("..."); /// /* run task */ /// drop(enter); /// ``` /// /// Doing so ensures that executors aren't /// accidentally invoked in a nested fashion. /// /// # Error /// /// Returns an error if the current thread is already marked, in which case the /// caller should panic with a tailored error message. pub fn enter() -> Result { ENTERED.with(|c| { if c.get() { Err(EnterError { _priv: () }) } else { c.set(true); Ok(Enter { _priv: () }) } }) } 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()); c.set(false); }); } } futures-executor-0.3.31/src/lib.rs000064400000000000000000000053011046102023000151430ustar 00000000000000//! Built-in executors and related tools. //! //! All asynchronous computation occurs within an executor, which is //! capable of spawning futures as tasks. This module provides several //! built-in executors, as well as tools for building your own. //! //! All items are only available when the `std` feature of this //! library is activated, and it is activated by default. //! //! # Using a thread pool (M:N task scheduling) //! //! Most of the time tasks should be executed on a [thread pool](ThreadPool). //! A small set of worker threads can handle a very large set of spawned tasks //! (which are much lighter weight than threads). Tasks spawned onto the pool //! with the [`spawn_ok`](ThreadPool::spawn_ok) function will run ambiently on //! the created threads. //! //! # Spawning additional tasks //! //! Tasks can be spawned onto a spawner by calling its [`spawn_obj`] method //! directly. In the case of `!Send` futures, [`spawn_local_obj`] can be used //! instead. //! //! # Single-threaded execution //! //! In addition to thread pools, it's possible to run a task (and the tasks //! it spawns) entirely within a single thread via the [`LocalPool`] executor. //! Aside from cutting down on synchronization costs, this executor also makes //! it possible to spawn non-`Send` tasks, via [`spawn_local_obj`]. The //! [`LocalPool`] is best suited for running I/O-bound tasks that do relatively //! little work between I/O operations. //! //! There is also a convenience function [`block_on`] for simply running a //! future to completion on the current thread. //! //! [`spawn_obj`]: https://docs.rs/futures/0.3/futures/task/trait.Spawn.html#tymethod.spawn_obj //! [`spawn_local_obj`]: https://docs.rs/futures/0.3/futures/task/trait.LocalSpawn.html#tymethod.spawn_local_obj #![no_std] #![doc(test( no_crate_inject, attr( deny(warnings, rust_2018_idioms, single_use_lifetimes), allow(dead_code, unused_assignments, unused_variables) ) ))] #![warn(missing_docs, unsafe_op_in_unsafe_fn)] #![cfg_attr(docsrs, feature(doc_cfg))] #[cfg(feature = "std")] extern crate std; #[cfg(feature = "std")] mod local_pool; #[cfg(feature = "std")] pub use crate::local_pool::{block_on, block_on_stream, BlockingStream, LocalPool, LocalSpawner}; #[cfg(feature = "thread-pool")] #[cfg_attr(docsrs, doc(cfg(feature = "thread-pool")))] #[cfg(feature = "std")] mod thread_pool; #[cfg(feature = "thread-pool")] #[cfg(feature = "std")] mod unpark_mutex; #[cfg(feature = "thread-pool")] #[cfg_attr(docsrs, doc(cfg(feature = "thread-pool")))] #[cfg(feature = "std")] pub use crate::thread_pool::{ThreadPool, ThreadPoolBuilder}; #[cfg(feature = "std")] mod enter; #[cfg(feature = "std")] pub use crate::enter::{enter, Enter, EnterError}; futures-executor-0.3.31/src/local_pool.rs000064400000000000000000000323451046102023000165300ustar 00000000000000use crate::enter; use futures_core::future::Future; use futures_core::stream::Stream; use futures_core::task::{Context, Poll}; use futures_task::{waker_ref, ArcWake}; use futures_task::{FutureObj, LocalFutureObj, LocalSpawn, Spawn, SpawnError}; use futures_util::pin_mut; use futures_util::stream::FuturesUnordered; use futures_util::stream::StreamExt; use std::cell::RefCell; use std::ops::{Deref, DerefMut}; use std::rc::{Rc, Weak}; use std::sync::{ atomic::{AtomicBool, Ordering}, Arc, }; use std::thread::{self, Thread}; use std::vec::Vec; /// A single-threaded task pool for polling futures to completion. /// /// This executor allows you to multiplex any number of tasks onto a single /// thread. It's appropriate to poll strictly I/O-bound futures that do very /// little work in between I/O actions. /// /// To get a handle to the pool that implements /// [`Spawn`](futures_task::Spawn), use the /// [`spawner()`](LocalPool::spawner) method. Because the executor is /// single-threaded, it supports a special form of task spawning for non-`Send` /// futures, via [`spawn_local_obj`](futures_task::LocalSpawn::spawn_local_obj). #[derive(Debug)] pub struct LocalPool { pool: FuturesUnordered>, incoming: Rc, } /// A handle to a [`LocalPool`] that implements [`Spawn`](futures_task::Spawn). #[derive(Clone, Debug)] pub struct LocalSpawner { incoming: Weak, } type Incoming = RefCell>>; pub(crate) struct ThreadNotify { /// The (single) executor thread. thread: Thread, /// A flag to ensure a wakeup (i.e. `unpark()`) is not "forgotten" /// before the next `park()`, which may otherwise happen if the code /// being executed as part of the future(s) being polled makes use of /// park / unpark calls of its own, i.e. we cannot assume that no other /// code uses park / unpark on the executing `thread`. unparked: AtomicBool, } std::thread_local! { static CURRENT_THREAD_NOTIFY: Arc = Arc::new(ThreadNotify { thread: thread::current(), unparked: AtomicBool::new(false), }); } impl ArcWake for ThreadNotify { fn wake_by_ref(arc_self: &Arc) { // Make sure the wakeup is remembered until the next `park()`. let unparked = arc_self.unparked.swap(true, Ordering::Release); if !unparked { // If the thread has not been unparked yet, it must be done // now. If it was actually parked, it will run again, // otherwise the token made available by `unpark` // may be consumed before reaching `park()`, but `unparked` // ensures it is not forgotten. arc_self.thread.unpark(); } } } // Set up and run a basic single-threaded spawner loop, invoking `f` on each // turn. fn run_executor) -> Poll>(mut f: F) -> T { let _enter = enter().expect( "cannot execute `LocalPool` executor from within \ another executor", ); CURRENT_THREAD_NOTIFY.with(|thread_notify| { let waker = waker_ref(thread_notify); let mut cx = Context::from_waker(&waker); loop { if let Poll::Ready(t) = f(&mut cx) { return t; } // Wait for a wakeup. while !thread_notify.unparked.swap(false, Ordering::Acquire) { // No wakeup occurred. It may occur now, right before parking, // but in that case the token made available by `unpark()` // is guaranteed to still be available and `park()` is a no-op. thread::park(); } } }) } /// Check for a wakeup, but don't consume it. fn woken() -> bool { CURRENT_THREAD_NOTIFY.with(|thread_notify| thread_notify.unparked.load(Ordering::Acquire)) } impl LocalPool { /// Create a new, empty pool of tasks. pub fn new() -> Self { Self { pool: FuturesUnordered::new(), incoming: Default::default() } } /// Get a clonable handle to the pool as a [`Spawn`]. pub fn spawner(&self) -> LocalSpawner { LocalSpawner { incoming: Rc::downgrade(&self.incoming) } } /// Run all tasks in the pool to completion. /// /// ``` /// use futures::executor::LocalPool; /// /// let mut pool = LocalPool::new(); /// /// // ... spawn some initial tasks using `spawn.spawn()` or `spawn.spawn_local()` /// /// // run *all* tasks in the pool to completion, including any newly-spawned ones. /// pool.run(); /// ``` /// /// The function will block the calling thread until *all* tasks in the pool /// are complete, including any spawned while running existing tasks. pub fn run(&mut self) { run_executor(|cx| self.poll_pool(cx)) } /// Runs all the tasks in the pool until the given future completes. /// /// ``` /// use futures::executor::LocalPool; /// /// let mut pool = LocalPool::new(); /// # let my_app = async {}; /// /// // run tasks in the pool until `my_app` completes /// pool.run_until(my_app); /// ``` /// /// The function will block the calling thread *only* until the future `f` /// completes; there may still be incomplete tasks in the pool, which will /// be inert after the call completes, but can continue with further use of /// one of the pool's run or poll methods. While the function is running, /// however, all tasks in the pool will try to make progress. pub fn run_until(&mut self, future: F) -> F::Output { pin_mut!(future); run_executor(|cx| { { // if our main task is done, so are we let result = future.as_mut().poll(cx); if let Poll::Ready(output) = result { return Poll::Ready(output); } } let _ = self.poll_pool(cx); Poll::Pending }) } /// Runs all tasks and returns after completing one future or until no more progress /// can be made. Returns `true` if one future was completed, `false` otherwise. /// /// ``` /// use futures::executor::LocalPool; /// use futures::task::LocalSpawnExt; /// use futures::future::{ready, pending}; /// /// let mut pool = LocalPool::new(); /// let spawner = pool.spawner(); /// /// spawner.spawn_local(ready(())).unwrap(); /// spawner.spawn_local(ready(())).unwrap(); /// spawner.spawn_local(pending()).unwrap(); /// /// // Run the two ready tasks and return true for them. /// pool.try_run_one(); // returns true after completing one of the ready futures /// pool.try_run_one(); // returns true after completing the other ready future /// /// // the remaining task can not be completed /// assert!(!pool.try_run_one()); // returns false /// ``` /// /// This function will not block the calling thread and will return the moment /// that there are no tasks left for which progress can be made or after exactly one /// task was completed; Remaining incomplete tasks in the pool can continue with /// further use of one of the pool's run or poll methods. /// Though only one task will be completed, progress may be made on multiple tasks. pub fn try_run_one(&mut self) -> bool { run_executor(|cx| { loop { self.drain_incoming(); match self.pool.poll_next_unpin(cx) { // Success! Poll::Ready(Some(())) => return Poll::Ready(true), // The pool was empty. Poll::Ready(None) => return Poll::Ready(false), Poll::Pending => (), } if !self.incoming.borrow().is_empty() { // New tasks were spawned; try again. continue; } else if woken() { // The pool yielded to us, but there's more progress to be made. return Poll::Pending; } else { return Poll::Ready(false); } } }) } /// Runs all tasks in the pool and returns if no more progress can be made /// on any task. /// /// ``` /// use futures::executor::LocalPool; /// use futures::task::LocalSpawnExt; /// use futures::future::{ready, pending}; /// /// let mut pool = LocalPool::new(); /// let spawner = pool.spawner(); /// /// spawner.spawn_local(ready(())).unwrap(); /// spawner.spawn_local(ready(())).unwrap(); /// spawner.spawn_local(pending()).unwrap(); /// /// // Runs the two ready task and returns. /// // The empty task remains in the pool. /// pool.run_until_stalled(); /// ``` /// /// This function will not block the calling thread and will return the moment /// that there are no tasks left for which progress can be made; /// remaining incomplete tasks in the pool can continue with further use of one /// of the pool's run or poll methods. While the function is running, all tasks /// in the pool will try to make progress. pub fn run_until_stalled(&mut self) { run_executor(|cx| match self.poll_pool(cx) { // The pool is empty. Poll::Ready(()) => Poll::Ready(()), Poll::Pending => { if woken() { Poll::Pending } else { // We're stalled for now. Poll::Ready(()) } } }); } /// Poll `self.pool`, re-filling it with any newly-spawned tasks. /// Repeat until either the pool is empty, or it returns `Pending`. /// /// Returns `Ready` if the pool was empty, and `Pending` otherwise. /// /// NOTE: the pool may call `wake`, so `Pending` doesn't necessarily /// mean that the pool can't make progress. fn poll_pool(&mut self, cx: &mut Context<'_>) -> Poll<()> { loop { self.drain_incoming(); let pool_ret = self.pool.poll_next_unpin(cx); // We queued up some new tasks; add them and poll again. if !self.incoming.borrow().is_empty() { continue; } match pool_ret { Poll::Ready(Some(())) => continue, Poll::Ready(None) => return Poll::Ready(()), Poll::Pending => return Poll::Pending, } } } /// Empty the incoming queue of newly-spawned tasks. fn drain_incoming(&mut self) { let mut incoming = self.incoming.borrow_mut(); for task in incoming.drain(..) { self.pool.push(task) } } } impl Default for LocalPool { fn default() -> Self { Self::new() } } /// Run a future to completion on the current thread. /// /// This function will block the caller until the given future has completed. /// /// Use a [`LocalPool`] if you need finer-grained control over spawned tasks. pub fn block_on(f: F) -> F::Output { pin_mut!(f); run_executor(|cx| f.as_mut().poll(cx)) } /// Turn a stream into a blocking iterator. /// /// When `next` is called on the resulting `BlockingStream`, the caller /// will be blocked until the next element of the `Stream` becomes available. pub fn block_on_stream(stream: S) -> BlockingStream { BlockingStream { stream } } /// An iterator which blocks on values from a stream until they become available. #[derive(Debug)] pub struct BlockingStream { stream: S, } impl Deref for BlockingStream { type Target = S; fn deref(&self) -> &Self::Target { &self.stream } } impl DerefMut for BlockingStream { fn deref_mut(&mut self) -> &mut Self::Target { &mut self.stream } } impl BlockingStream { /// Convert this `BlockingStream` into the inner `Stream` type. pub fn into_inner(self) -> S { self.stream } } impl Iterator for BlockingStream { type Item = S::Item; fn next(&mut self) -> Option { LocalPool::new().run_until(self.stream.next()) } fn size_hint(&self) -> (usize, Option) { self.stream.size_hint() } } impl Spawn for LocalSpawner { fn spawn_obj(&self, future: FutureObj<'static, ()>) -> Result<(), SpawnError> { if let Some(incoming) = self.incoming.upgrade() { incoming.borrow_mut().push(future.into()); Ok(()) } else { Err(SpawnError::shutdown()) } } fn status(&self) -> Result<(), SpawnError> { if self.incoming.upgrade().is_some() { Ok(()) } else { Err(SpawnError::shutdown()) } } } impl LocalSpawn for LocalSpawner { fn spawn_local_obj(&self, future: LocalFutureObj<'static, ()>) -> Result<(), SpawnError> { if let Some(incoming) = self.incoming.upgrade() { incoming.borrow_mut().push(future); Ok(()) } else { Err(SpawnError::shutdown()) } } fn status_local(&self) -> Result<(), SpawnError> { if self.incoming.upgrade().is_some() { Ok(()) } else { Err(SpawnError::shutdown()) } } } futures-executor-0.3.31/src/thread_pool.rs000064400000000000000000000271271046102023000167070ustar 00000000000000use crate::enter; use crate::unpark_mutex::UnparkMutex; use futures_core::future::Future; use futures_core::task::{Context, Poll}; use futures_task::{waker_ref, ArcWake}; use futures_task::{FutureObj, Spawn, SpawnError}; use futures_util::future::FutureExt; use std::boxed::Box; use std::cmp; use std::fmt; use std::format; use std::io; use std::string::String; use std::sync::atomic::{AtomicUsize, Ordering}; use std::sync::mpsc; use std::sync::{Arc, Mutex}; use std::thread; /// A general-purpose thread pool for scheduling tasks that poll futures to /// completion. /// /// The thread pool multiplexes any number of tasks onto a fixed number of /// worker threads. /// /// This type is a clonable handle to the threadpool itself. /// Cloning it will only create a new reference, not a new threadpool. /// /// This type is only available when the `thread-pool` feature of this /// library is activated. #[cfg_attr(docsrs, doc(cfg(feature = "thread-pool")))] pub struct ThreadPool { state: Arc, } /// Thread pool configuration object. /// /// This type is only available when the `thread-pool` feature of this /// library is activated. #[cfg_attr(docsrs, doc(cfg(feature = "thread-pool")))] pub struct ThreadPoolBuilder { pool_size: usize, stack_size: usize, name_prefix: Option, after_start: Option>, before_stop: Option>, } #[allow(dead_code)] trait AssertSendSync: Send + Sync {} impl AssertSendSync for ThreadPool {} struct PoolState { tx: Mutex>, rx: Mutex>, cnt: AtomicUsize, size: usize, } impl fmt::Debug for ThreadPool { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { f.debug_struct("ThreadPool").field("size", &self.state.size).finish() } } impl fmt::Debug for ThreadPoolBuilder { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { f.debug_struct("ThreadPoolBuilder") .field("pool_size", &self.pool_size) .field("name_prefix", &self.name_prefix) .finish() } } enum Message { Run(Task), Close, } impl ThreadPool { /// Creates a new thread pool with the default configuration. /// /// See documentation for the methods in /// [`ThreadPoolBuilder`](ThreadPoolBuilder) for details on the default /// configuration. pub fn new() -> Result { ThreadPoolBuilder::new().create() } /// Create a default thread pool configuration, which can then be customized. /// /// See documentation for the methods in /// [`ThreadPoolBuilder`](ThreadPoolBuilder) for details on the default /// configuration. pub fn builder() -> ThreadPoolBuilder { ThreadPoolBuilder::new() } /// Spawns a future that will be run to completion. /// /// > **Note**: This method is similar to `Spawn::spawn_obj`, except that /// > it is guaranteed to always succeed. pub fn spawn_obj_ok(&self, future: FutureObj<'static, ()>) { let task = Task { future, wake_handle: Arc::new(WakeHandle { exec: self.clone(), mutex: UnparkMutex::new() }), exec: self.clone(), }; self.state.send(Message::Run(task)); } /// Spawns a task that polls the given future with output `()` to /// completion. /// /// ``` /// # { /// use futures::executor::ThreadPool; /// /// let pool = ThreadPool::new().unwrap(); /// /// let future = async { /* ... */ }; /// pool.spawn_ok(future); /// # } /// # std::thread::sleep(std::time::Duration::from_millis(500)); // wait for background threads closed: https://github.com/rust-lang/miri/issues/1371 /// ``` /// /// > **Note**: This method is similar to `SpawnExt::spawn`, except that /// > it is guaranteed to always succeed. pub fn spawn_ok(&self, future: Fut) where Fut: Future + Send + 'static, { self.spawn_obj_ok(FutureObj::new(Box::new(future))) } } impl Spawn for ThreadPool { fn spawn_obj(&self, future: FutureObj<'static, ()>) -> Result<(), SpawnError> { self.spawn_obj_ok(future); Ok(()) } } impl PoolState { fn send(&self, msg: Message) { self.tx.lock().unwrap().send(msg).unwrap(); } fn work( &self, idx: usize, after_start: Option>, before_stop: Option>, ) { let _scope = enter().unwrap(); if let Some(after_start) = after_start { after_start(idx); } loop { let msg = self.rx.lock().unwrap().recv().unwrap(); match msg { Message::Run(task) => task.run(), Message::Close => break, } } if let Some(before_stop) = before_stop { before_stop(idx); } } } impl Clone for ThreadPool { fn clone(&self) -> Self { self.state.cnt.fetch_add(1, Ordering::Relaxed); Self { state: self.state.clone() } } } impl Drop for ThreadPool { fn drop(&mut self) { if self.state.cnt.fetch_sub(1, Ordering::Relaxed) == 1 { for _ in 0..self.state.size { self.state.send(Message::Close); } } } } impl ThreadPoolBuilder { /// Create a default thread pool configuration. /// /// See the other methods on this type for details on the defaults. pub fn new() -> Self { Self { pool_size: cmp::max(1, num_cpus::get()), stack_size: 0, name_prefix: None, after_start: None, before_stop: None, } } /// Set size of a future ThreadPool /// /// The size of a thread pool is the number of worker threads spawned. By /// default, this is equal to the number of CPU cores. /// /// # Panics /// /// Panics if `pool_size == 0`. pub fn pool_size(&mut self, size: usize) -> &mut Self { assert!(size > 0); self.pool_size = size; self } /// Set stack size of threads in the pool, in bytes. /// /// By default, worker threads use Rust's standard stack size. pub fn stack_size(&mut self, stack_size: usize) -> &mut Self { self.stack_size = stack_size; self } /// Set thread name prefix of a future ThreadPool. /// /// Thread name prefix is used for generating thread names. For example, if prefix is /// `my-pool-`, then threads in the pool will get names like `my-pool-1` etc. /// /// By default, worker threads are assigned Rust's standard thread name. pub fn name_prefix>(&mut self, name_prefix: S) -> &mut Self { self.name_prefix = Some(name_prefix.into()); self } /// Execute the closure `f` immediately after each worker thread is started, /// but before running any tasks on it. /// /// This hook is intended for bookkeeping and monitoring. /// The closure `f` will be dropped after the `builder` is dropped /// and all worker threads in the pool have executed it. /// /// The closure provided will receive an index corresponding to the worker /// thread it's running on. pub fn after_start(&mut self, f: F) -> &mut Self where F: Fn(usize) + Send + Sync + 'static, { self.after_start = Some(Arc::new(f)); self } /// Execute closure `f` just prior to shutting down each worker thread. /// /// This hook is intended for bookkeeping and monitoring. /// The closure `f` will be dropped after the `builder` is dropped /// and all threads in the pool have executed it. /// /// The closure provided will receive an index corresponding to the worker /// thread it's running on. pub fn before_stop(&mut self, f: F) -> &mut Self where F: Fn(usize) + Send + Sync + 'static, { self.before_stop = Some(Arc::new(f)); self } /// Create a [`ThreadPool`](ThreadPool) with the given configuration. pub fn create(&mut self) -> Result { let (tx, rx) = mpsc::channel(); let pool = ThreadPool { state: Arc::new(PoolState { tx: Mutex::new(tx), rx: Mutex::new(rx), cnt: AtomicUsize::new(1), size: self.pool_size, }), }; for counter in 0..self.pool_size { let state = pool.state.clone(); let after_start = self.after_start.clone(); let before_stop = self.before_stop.clone(); let mut thread_builder = thread::Builder::new(); if let Some(ref name_prefix) = self.name_prefix { thread_builder = thread_builder.name(format!("{}{}", name_prefix, counter)); } if self.stack_size > 0 { thread_builder = thread_builder.stack_size(self.stack_size); } thread_builder.spawn(move || state.work(counter, after_start, before_stop))?; } Ok(pool) } } impl Default for ThreadPoolBuilder { fn default() -> Self { Self::new() } } /// A task responsible for polling a future to completion. struct Task { future: FutureObj<'static, ()>, exec: ThreadPool, wake_handle: Arc, } struct WakeHandle { mutex: UnparkMutex, exec: ThreadPool, } impl Task { /// Actually run the task (invoking `poll` on the future) on the current /// thread. fn run(self) { let Self { mut future, wake_handle, mut exec } = self; let waker = waker_ref(&wake_handle); let mut cx = Context::from_waker(&waker); // Safety: The ownership of this `Task` object is evidence that // we are in the `POLLING`/`REPOLL` state for the mutex. unsafe { wake_handle.mutex.start_poll(); loop { let res = future.poll_unpin(&mut cx); match res { Poll::Pending => {} Poll::Ready(()) => return wake_handle.mutex.complete(), } let task = Self { future, wake_handle: wake_handle.clone(), exec }; match wake_handle.mutex.wait(task) { Ok(()) => return, // we've waited Err(task) => { // someone's notified us future = task.future; exec = task.exec; } } } } } } impl fmt::Debug for Task { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { f.debug_struct("Task").field("contents", &"...").finish() } } impl ArcWake for WakeHandle { fn wake_by_ref(arc_self: &Arc) { if let Ok(task) = arc_self.mutex.notify() { arc_self.exec.state.send(Message::Run(task)) } } } #[cfg(test)] mod tests { use super::*; #[test] fn test_drop_after_start() { { let (tx, rx) = mpsc::sync_channel(2); let _cpu_pool = ThreadPoolBuilder::new() .pool_size(2) .after_start(move |_| tx.send(1).unwrap()) .create() .unwrap(); // After ThreadPoolBuilder is deconstructed, the tx should be dropped // so that we can use rx as an iterator. let count = rx.into_iter().count(); assert_eq!(count, 2); } std::thread::sleep(std::time::Duration::from_millis(500)); // wait for background threads closed: https://github.com/rust-lang/miri/issues/1371 } } futures-executor-0.3.31/src/unpark_mutex.rs000064400000000000000000000125361046102023000171270ustar 00000000000000use std::cell::UnsafeCell; use std::sync::atomic::AtomicUsize; use std::sync::atomic::Ordering::SeqCst; /// A "lock" around data `D`, which employs a *helping* strategy. /// /// Used to ensure that concurrent `unpark` invocations lead to (1) `poll` being /// invoked on only a single thread at a time (2) `poll` being invoked at least /// once after each `unpark` (unless the future has completed). pub(crate) struct UnparkMutex { // The state of task execution (state machine described below) status: AtomicUsize, // The actual task data, accessible only in the POLLING state inner: UnsafeCell>, } // `UnparkMutex` functions in many ways like a `Mutex`, except that on // acquisition failure, the current lock holder performs the desired work -- // re-polling. // // As such, these impls mirror those for `Mutex`. In particular, a reference // to `UnparkMutex` can be used to gain `&mut` access to the inner data, which // must therefore be `Send`. unsafe impl Send for UnparkMutex {} unsafe impl Sync for UnparkMutex {} // There are four possible task states, listed below with their possible // transitions: // The task is blocked, waiting on an event const WAITING: usize = 0; // --> POLLING // The task is actively being polled by a thread; arrival of additional events // of interest should move it to the REPOLL state const POLLING: usize = 1; // --> WAITING, REPOLL, or COMPLETE // The task is actively being polled, but will need to be re-polled upon // completion to ensure that all events were observed. const REPOLL: usize = 2; // --> POLLING // The task has finished executing (either successfully or with an error/panic) const COMPLETE: usize = 3; // No transitions out impl UnparkMutex { pub(crate) fn new() -> Self { Self { status: AtomicUsize::new(WAITING), inner: UnsafeCell::new(None) } } /// Attempt to "notify" the mutex that a poll should occur. /// /// An `Ok` result indicates that the `POLLING` state has been entered, and /// the caller can proceed to poll the future. An `Err` result indicates /// that polling is not necessary (because the task is finished or the /// polling has been delegated). pub(crate) fn notify(&self) -> Result { let mut status = self.status.load(SeqCst); loop { match status { // The task is idle, so try to run it immediately. WAITING => { match self.status.compare_exchange(WAITING, POLLING, SeqCst, SeqCst) { Ok(_) => { let data = unsafe { // SAFETY: we've ensured mutual exclusion via // the status protocol; we are the only thread // that has transitioned to the POLLING state, // and we won't transition back to QUEUED until // the lock is "released" by this thread. See // the protocol diagram above. (*self.inner.get()).take().unwrap() }; return Ok(data); } Err(cur) => status = cur, } } // The task is being polled, so we need to record that it should // be *repolled* when complete. POLLING => match self.status.compare_exchange(POLLING, REPOLL, SeqCst, SeqCst) { Ok(_) => return Err(()), Err(cur) => status = cur, }, // The task is already scheduled for polling, or is complete, so // we've got nothing to do. _ => return Err(()), } } } /// Alert the mutex that polling is about to begin, clearing any accumulated /// re-poll requests. /// /// # Safety /// /// Callable only from the `POLLING`/`REPOLL` states, i.e. between /// successful calls to `notify` and `wait`/`complete`. pub(crate) unsafe fn start_poll(&self) { self.status.store(POLLING, SeqCst); } /// Alert the mutex that polling completed with `Pending`. /// /// # Safety /// /// Callable only from the `POLLING`/`REPOLL` states, i.e. between /// successful calls to `notify` and `wait`/`complete`. pub(crate) unsafe fn wait(&self, data: D) -> Result<(), D> { unsafe { *self.inner.get() = Some(data) } match self.status.compare_exchange(POLLING, WAITING, SeqCst, SeqCst) { // no unparks came in while we were running Ok(_) => Ok(()), // guaranteed to be in REPOLL state; just clobber the // state and run again. Err(status) => { assert_eq!(status, REPOLL); self.status.store(POLLING, SeqCst); Err(unsafe { (*self.inner.get()).take().unwrap() }) } } } /// Alert the mutex that the task has completed execution and should not be /// notified again. /// /// # Safety /// /// Callable only from the `POLLING`/`REPOLL` states, i.e. between /// successful calls to `notify` and `wait`/`complete`. pub(crate) unsafe fn complete(&self) { self.status.store(COMPLETE, SeqCst); } } futures-executor-0.3.31/tests/local_pool.rs000064400000000000000000000277641046102023000171140ustar 00000000000000use futures::channel::oneshot; use futures::executor::LocalPool; use futures::future::{self, lazy, poll_fn, Future}; use futures::task::{Context, LocalSpawn, LocalSpawnExt, Poll, Spawn, SpawnExt, Waker}; use std::cell::{Cell, RefCell}; use std::marker::PhantomData; use std::pin::Pin; use std::rc::Rc; use std::sync::atomic::{AtomicBool, Ordering}; use std::sync::Arc; use std::thread; use std::time::Duration; struct Pending(PhantomData>); impl Future for Pending { type Output = (); fn poll(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<()> { Poll::Pending } } fn pending() -> Pending { Pending(PhantomData) } #[test] fn run_until_single_future() { let mut cnt = 0; { let mut pool = LocalPool::new(); let fut = lazy(|_| { cnt += 1; }); pool.run_until(fut); } assert_eq!(cnt, 1); } #[test] fn run_until_ignores_spawned() { let mut pool = LocalPool::new(); let spawn = pool.spawner(); spawn.spawn_local_obj(Box::pin(pending()).into()).unwrap(); pool.run_until(lazy(|_| ())); } #[test] fn run_until_executes_spawned() { let (tx, rx) = oneshot::channel(); let mut pool = LocalPool::new(); let spawn = pool.spawner(); spawn .spawn_local_obj( Box::pin(lazy(move |_| { tx.send(()).unwrap(); })) .into(), ) .unwrap(); pool.run_until(rx).unwrap(); } #[test] fn run_returns_if_empty() { let mut pool = LocalPool::new(); pool.run(); pool.run(); } #[test] fn run_executes_spawned() { let cnt = Rc::new(Cell::new(0)); let cnt2 = cnt.clone(); let mut pool = LocalPool::new(); let spawn = pool.spawner(); let spawn2 = pool.spawner(); spawn .spawn_local_obj( Box::pin(lazy(move |_| { spawn2 .spawn_local_obj( Box::pin(lazy(move |_| { cnt2.set(cnt2.get() + 1); })) .into(), ) .unwrap(); })) .into(), ) .unwrap(); pool.run(); assert_eq!(cnt.get(), 1); } #[test] fn run_spawn_many() { const ITER: usize = 200; let cnt = Rc::new(Cell::new(0)); let mut pool = LocalPool::new(); let spawn = pool.spawner(); for _ in 0..ITER { let cnt = cnt.clone(); spawn .spawn_local_obj( Box::pin(lazy(move |_| { cnt.set(cnt.get() + 1); })) .into(), ) .unwrap(); } pool.run(); assert_eq!(cnt.get(), ITER); } #[test] fn try_run_one_returns_if_empty() { let mut pool = LocalPool::new(); assert!(!pool.try_run_one()); } #[test] fn try_run_one_executes_one_ready() { const ITER: usize = 200; let cnt = Rc::new(Cell::new(0)); let mut pool = LocalPool::new(); let spawn = pool.spawner(); for _ in 0..ITER { spawn.spawn_local_obj(Box::pin(pending()).into()).unwrap(); let cnt = cnt.clone(); spawn .spawn_local_obj( Box::pin(lazy(move |_| { cnt.set(cnt.get() + 1); })) .into(), ) .unwrap(); spawn.spawn_local_obj(Box::pin(pending()).into()).unwrap(); } for i in 0..ITER { assert_eq!(cnt.get(), i); assert!(pool.try_run_one()); assert_eq!(cnt.get(), i + 1); } assert!(!pool.try_run_one()); } #[test] fn try_run_one_returns_on_no_progress() { const ITER: usize = 10; let cnt = Rc::new(Cell::new(0)); let mut pool = LocalPool::new(); let spawn = pool.spawner(); let waker: Rc>> = Rc::new(Cell::new(None)); { let cnt = cnt.clone(); let waker = waker.clone(); spawn .spawn_local_obj( Box::pin(poll_fn(move |ctx| { cnt.set(cnt.get() + 1); waker.set(Some(ctx.waker().clone())); if cnt.get() == ITER { Poll::Ready(()) } else { Poll::Pending } })) .into(), ) .unwrap(); } for i in 0..ITER - 1 { assert_eq!(cnt.get(), i); assert!(!pool.try_run_one()); assert_eq!(cnt.get(), i + 1); let w = waker.take(); assert!(w.is_some()); w.unwrap().wake(); } assert!(pool.try_run_one()); assert_eq!(cnt.get(), ITER); } #[test] fn try_run_one_runs_sub_futures() { let mut pool = LocalPool::new(); let spawn = pool.spawner(); let cnt = Rc::new(Cell::new(0)); let inner_spawner = spawn.clone(); let cnt1 = cnt.clone(); spawn .spawn_local_obj( Box::pin(poll_fn(move |_| { cnt1.set(cnt1.get() + 1); let cnt2 = cnt1.clone(); inner_spawner .spawn_local_obj(Box::pin(lazy(move |_| cnt2.set(cnt2.get() + 1))).into()) .unwrap(); Poll::Pending })) .into(), ) .unwrap(); pool.try_run_one(); assert_eq!(cnt.get(), 2); } #[test] fn run_until_stalled_returns_if_empty() { let mut pool = LocalPool::new(); pool.run_until_stalled(); pool.run_until_stalled(); } #[test] fn run_until_stalled_returns_multiple_times() { let mut pool = LocalPool::new(); let spawn = pool.spawner(); let cnt = Rc::new(Cell::new(0)); let cnt1 = cnt.clone(); spawn.spawn_local_obj(Box::pin(lazy(move |_| cnt1.set(cnt1.get() + 1))).into()).unwrap(); pool.run_until_stalled(); assert_eq!(cnt.get(), 1); let cnt2 = cnt.clone(); spawn.spawn_local_obj(Box::pin(lazy(move |_| cnt2.set(cnt2.get() + 1))).into()).unwrap(); pool.run_until_stalled(); assert_eq!(cnt.get(), 2); } #[test] fn run_until_stalled_runs_spawned_sub_futures() { let mut pool = LocalPool::new(); let spawn = pool.spawner(); let cnt = Rc::new(Cell::new(0)); let inner_spawner = spawn.clone(); let cnt1 = cnt.clone(); spawn .spawn_local_obj( Box::pin(poll_fn(move |_| { cnt1.set(cnt1.get() + 1); let cnt2 = cnt1.clone(); inner_spawner .spawn_local_obj(Box::pin(lazy(move |_| cnt2.set(cnt2.get() + 1))).into()) .unwrap(); Poll::Pending })) .into(), ) .unwrap(); pool.run_until_stalled(); assert_eq!(cnt.get(), 2); } #[test] fn run_until_stalled_executes_all_ready() { const ITER: usize = if cfg!(miri) { 50 } else { 200 }; const PER_ITER: usize = 3; let cnt = Rc::new(Cell::new(0)); let mut pool = LocalPool::new(); let spawn = pool.spawner(); for i in 0..ITER { for _ in 0..PER_ITER { spawn.spawn_local_obj(Box::pin(pending()).into()).unwrap(); let cnt = cnt.clone(); spawn .spawn_local_obj( Box::pin(lazy(move |_| { cnt.set(cnt.get() + 1); })) .into(), ) .unwrap(); // also add some pending tasks to test if they are ignored spawn.spawn_local_obj(Box::pin(pending()).into()).unwrap(); } assert_eq!(cnt.get(), i * PER_ITER); pool.run_until_stalled(); assert_eq!(cnt.get(), (i + 1) * PER_ITER); } } #[test] #[should_panic] fn nesting_run() { let mut pool = LocalPool::new(); let spawn = pool.spawner(); spawn .spawn_obj( Box::pin(lazy(|_| { let mut pool = LocalPool::new(); pool.run(); })) .into(), ) .unwrap(); pool.run(); } #[test] #[should_panic] fn nesting_run_run_until_stalled() { let mut pool = LocalPool::new(); let spawn = pool.spawner(); spawn .spawn_obj( Box::pin(lazy(|_| { let mut pool = LocalPool::new(); pool.run_until_stalled(); })) .into(), ) .unwrap(); pool.run(); } #[test] fn tasks_are_scheduled_fairly() { let state = Rc::new(RefCell::new([0, 0])); struct Spin { state: Rc>, idx: usize, } impl Future for Spin { type Output = (); fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<()> { let mut state = self.state.borrow_mut(); if self.idx == 0 { let diff = state[0] - state[1]; assert!(diff.abs() <= 1); if state[0] >= 50 { return Poll::Ready(()); } } state[self.idx] += 1; if state[self.idx] >= 100 { return Poll::Ready(()); } cx.waker().wake_by_ref(); Poll::Pending } } let mut pool = LocalPool::new(); let spawn = pool.spawner(); spawn.spawn_local_obj(Box::pin(Spin { state: state.clone(), idx: 0 }).into()).unwrap(); spawn.spawn_local_obj(Box::pin(Spin { state, idx: 1 }).into()).unwrap(); pool.run(); } // Tests that the use of park/unpark in user-code has no // effect on the expected behavior of the executor. #[test] fn park_unpark_independence() { let mut done = false; let future = future::poll_fn(move |cx| { if done { return Poll::Ready(()); } done = true; cx.waker().clone().wake(); // (*) // some user-code that temporarily parks the thread let test = thread::current(); let latch = Arc::new(AtomicBool::new(false)); let signal = latch.clone(); thread::spawn(move || { thread::sleep(Duration::from_millis(10)); signal.store(true, Ordering::SeqCst); test.unpark() }); while !latch.load(Ordering::Relaxed) { thread::park(); } Poll::Pending // Expect to be called again due to (*). }); futures::executor::block_on(future) } struct SelfWaking { wakeups_remaining: Rc>, } impl Future for SelfWaking { type Output = (); fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll { if *self.wakeups_remaining.borrow() != 0 { *self.wakeups_remaining.borrow_mut() -= 1; cx.waker().wake_by_ref(); } Poll::Pending } } /// Regression test for https://github.com/rust-lang/futures-rs/pull/2593 /// /// The issue was that self-waking futures could cause `run_until_stalled` /// to exit early, even when progress could still be made. #[test] fn self_waking_run_until_stalled() { let wakeups_remaining = Rc::new(RefCell::new(10)); let mut pool = LocalPool::new(); let spawner = pool.spawner(); for _ in 0..3 { let wakeups_remaining = Rc::clone(&wakeups_remaining); spawner.spawn_local(SelfWaking { wakeups_remaining }).unwrap(); } // This should keep polling until there are no more wakeups. pool.run_until_stalled(); assert_eq!(*wakeups_remaining.borrow(), 0); } /// Regression test for https://github.com/rust-lang/futures-rs/pull/2593 /// /// The issue was that self-waking futures could cause `try_run_one` /// to exit early, even when progress could still be made. #[test] fn self_waking_try_run_one() { let wakeups_remaining = Rc::new(RefCell::new(10)); let mut pool = LocalPool::new(); let spawner = pool.spawner(); for _ in 0..3 { let wakeups_remaining = Rc::clone(&wakeups_remaining); spawner.spawn_local(SelfWaking { wakeups_remaining }).unwrap(); } spawner.spawn(future::ready(())).unwrap(); // The `ready` future should complete. assert!(pool.try_run_one()); // The self-waking futures are each polled once. assert_eq!(*wakeups_remaining.borrow(), 7); }