| <!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `/root/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-0.3.28/src/lib.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>lib.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../normalize.css"><link rel="stylesheet" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../ayu.css" disabled><link rel="stylesheet" href="../../dark.css" disabled><link rel="stylesheet" href="../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../storage.js"></script><script defer src="../../source-script.js"></script><script defer src="../../source-files.js"></script><script defer src="../../main.js"></script><noscript><link rel="stylesheet" href="../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../futures/index.html"><div class="logo-container"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../futures/index.html"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span> |
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| </pre><pre class="rust"><code><span class="doccomment">//! Abstractions for asynchronous programming. |
| //! |
| //! This crate provides a number of core abstractions for writing asynchronous |
| //! code: |
| //! |
| //! - [Futures](crate::future) are single eventual values produced by |
| //! asynchronous computations. Some programming languages (e.g. JavaScript) |
| //! call this concept "promise". |
| //! - [Streams](crate::stream) represent a series of values |
| //! produced asynchronously. |
| //! - [Sinks](crate::sink) provide support for asynchronous writing of |
| //! data. |
| //! - [Executors](crate::executor) are responsible for running asynchronous |
| //! tasks. |
| //! |
| //! The crate also contains abstractions for [asynchronous I/O](crate::io) and |
| //! [cross-task communication](crate::channel). |
| //! |
| //! Underlying all of this is the *task system*, which is a form of lightweight |
| //! threading. Large asynchronous computations are built up using futures, |
| //! streams and sinks, and then spawned as independent tasks that are run to |
| //! completion, but *do not block* the thread running them. |
| //! |
| //! The following example describes how the task system context is built and used |
| //! within macros and keywords such as async and await!. |
| //! |
| //! ```rust |
| //! # use futures::channel::mpsc; |
| //! # use futures::executor; ///standard executors to provide a context for futures and streams |
| //! # use futures::executor::ThreadPool; |
| //! # use futures::StreamExt; |
| //! # |
| //! fn main() { |
| //! # { |
| //! let pool = ThreadPool::new().expect("Failed to build pool"); |
| //! let (tx, rx) = mpsc::unbounded::<i32>(); |
| //! |
| //! // Create a future by an async block, where async is responsible for an |
| //! // implementation of Future. At this point no executor has been provided |
| //! // to this future, so it will not be running. |
| //! let fut_values = async { |
| //! // Create another async block, again where the Future implementation |
| //! // is generated by async. Since this is inside of a parent async block, |
| //! // it will be provided with the executor of the parent block when the parent |
| //! // block is executed. |
| //! // |
| //! // This executor chaining is done by Future::poll whose second argument |
| //! // is a std::task::Context. This represents our executor, and the Future |
| //! // implemented by this async block can be polled using the parent async |
| //! // block's executor. |
| //! let fut_tx_result = async move { |
| //! (0..100).for_each(|v| { |
| //! tx.unbounded_send(v).expect("Failed to send"); |
| //! }) |
| //! }; |
| //! |
| //! // Use the provided thread pool to spawn the generated future |
| //! // responsible for transmission |
| //! pool.spawn_ok(fut_tx_result); |
| //! |
| //! let fut_values = rx |
| //! .map(|v| v * 2) |
| //! .collect(); |
| //! |
| //! // Use the executor provided to this async block to wait for the |
| //! // future to complete. |
| //! fut_values.await |
| //! }; |
| //! |
| //! // Actually execute the above future, which will invoke Future::poll and |
| //! // subsequently chain appropriate Future::poll and methods needing executors |
| //! // to drive all futures. Eventually fut_values will be driven to completion. |
| //! let values: Vec<i32> = executor::block_on(fut_values); |
| //! |
| //! println!("Values={:?}", values); |
| //! # } |
| //! # std::thread::sleep(std::time::Duration::from_millis(500)); // wait for background threads closed: https://github.com/rust-lang/miri/issues/1371 |
| //! } |
| //! ``` |
| //! |
| //! The majority of examples and code snippets in this crate assume that they are |
| //! inside an async block as written above. |
| |
| </span><span class="attribute">#![cfg_attr(not(feature = <span class="string">"std"</span>), no_std)] |
| #![warn( |
| missing_debug_implementations, |
| missing_docs, |
| rust_2018_idioms, |
| single_use_lifetimes, |
| unreachable_pub |
| )] |
| #![doc(test( |
| no_crate_inject, |
| attr( |
| deny(warnings, rust_2018_idioms, single_use_lifetimes), |
| allow(dead_code, unused_assignments, unused_variables) |
| ) |
| ))] |
| #![cfg_attr(docsrs, feature(doc_cfg))] |
| |
| #[cfg(all(feature = <span class="string">"bilock"</span>, not(feature = <span class="string">"unstable"</span>)))] |
| </span><span class="macro">compile_error!</span>(<span class="string">"The `bilock` feature requires the `unstable` feature as an explicit opt-in to unstable features"</span>); |
| |
| <span class="attribute">#[doc(no_inline)] |
| </span><span class="kw">pub use </span>futures_core::future::{Future, TryFuture}; |
| <span class="attribute">#[doc(no_inline)] |
| </span><span class="kw">pub use </span>futures_util::future::{FutureExt, TryFutureExt}; |
| |
| <span class="attribute">#[doc(no_inline)] |
| </span><span class="kw">pub use </span>futures_core::stream::{Stream, TryStream}; |
| <span class="attribute">#[doc(no_inline)] |
| </span><span class="kw">pub use </span>futures_util::stream::{StreamExt, TryStreamExt}; |
| |
| <span class="attribute">#[doc(no_inline)] |
| </span><span class="kw">pub use </span>futures_sink::Sink; |
| <span class="attribute">#[doc(no_inline)] |
| </span><span class="kw">pub use </span>futures_util::sink::SinkExt; |
| |
| <span class="attribute">#[cfg(feature = <span class="string">"std"</span>)] |
| #[doc(no_inline)] |
| </span><span class="kw">pub use </span>futures_io::{AsyncBufRead, AsyncRead, AsyncSeek, AsyncWrite}; |
| <span class="attribute">#[cfg(feature = <span class="string">"std"</span>)] |
| #[doc(no_inline)] |
| </span><span class="kw">pub use </span>futures_util::{AsyncBufReadExt, AsyncReadExt, AsyncSeekExt, AsyncWriteExt}; |
| |
| <span class="comment">// Macro reexports |
| </span><span class="kw">pub use </span>futures_core::ready; <span class="comment">// Readiness propagation |
| </span><span class="kw">pub use </span>futures_util::pin_mut; |
| <span class="attribute">#[cfg(feature = <span class="string">"std"</span>)] |
| #[cfg(feature = <span class="string">"async-await"</span>)] |
| </span><span class="kw">pub use </span>futures_util::select; |
| <span class="attribute">#[cfg(feature = <span class="string">"async-await"</span>)] |
| </span><span class="kw">pub use </span>futures_util::{join, pending, poll, select_biased, try_join}; <span class="comment">// Async-await |
| |
| // Module reexports |
| </span><span class="attribute">#[doc(inline)] |
| </span><span class="kw">pub use </span>futures_util::{future, never, sink, stream, task}; |
| |
| <span class="attribute">#[cfg(feature = <span class="string">"std"</span>)] |
| #[cfg(feature = <span class="string">"async-await"</span>)] |
| </span><span class="kw">pub use </span>futures_util::stream_select; |
| |
| <span class="attribute">#[cfg(feature = <span class="string">"alloc"</span>)] |
| #[doc(inline)] |
| </span><span class="kw">pub use </span>futures_channel <span class="kw">as </span>channel; |
| <span class="attribute">#[cfg(feature = <span class="string">"alloc"</span>)] |
| #[doc(inline)] |
| </span><span class="kw">pub use </span>futures_util::lock; |
| |
| <span class="attribute">#[cfg(feature = <span class="string">"std"</span>)] |
| #[doc(inline)] |
| </span><span class="kw">pub use </span>futures_util::io; |
| |
| <span class="attribute">#[cfg(feature = <span class="string">"executor"</span>)] |
| #[cfg_attr(docsrs, doc(cfg(feature = <span class="string">"executor"</span>)))] |
| </span><span class="kw">pub mod </span>executor { |
| <span class="doccomment">//! 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. |
| //! |
| //! |
| //! This module is only available when the `executor` feature of this |
| //! library is activated. |
| //! |
| //! # 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 |
| |
| </span><span class="kw">pub use </span>futures_executor::{ |
| block_on, block_on_stream, enter, BlockingStream, Enter, EnterError, LocalPool, |
| LocalSpawner, |
| }; |
| |
| <span class="attribute">#[cfg(feature = <span class="string">"thread-pool"</span>)] |
| #[cfg_attr(docsrs, doc(cfg(feature = <span class="string">"thread-pool"</span>)))] |
| </span><span class="kw">pub use </span>futures_executor::{ThreadPool, ThreadPoolBuilder}; |
| } |
| |
| <span class="attribute">#[cfg(feature = <span class="string">"compat"</span>)] |
| #[cfg_attr(docsrs, doc(cfg(feature = <span class="string">"compat"</span>)))] |
| </span><span class="kw">pub mod </span>compat { |
| <span class="doccomment">//! Interop between `futures` 0.1 and 0.3. |
| //! |
| //! This module is only available when the `compat` feature of this |
| //! library is activated. |
| |
| </span><span class="kw">pub use </span>futures_util::compat::{ |
| Compat, Compat01As03, Compat01As03Sink, CompatSink, Executor01As03, Executor01CompatExt, |
| Executor01Future, Future01CompatExt, Sink01CompatExt, Stream01CompatExt, |
| }; |
| |
| <span class="attribute">#[cfg(feature = <span class="string">"io-compat"</span>)] |
| #[cfg_attr(docsrs, doc(cfg(feature = <span class="string">"io-compat"</span>)))] |
| </span><span class="kw">pub use </span>futures_util::compat::{AsyncRead01CompatExt, AsyncWrite01CompatExt}; |
| } |
| |
| <span class="kw">pub mod </span>prelude { |
| <span class="doccomment">//! A "prelude" for crates using the `futures` crate. |
| //! |
| //! This prelude is similar to the standard library's prelude in that you'll |
| //! almost always want to import its entire contents, but unlike the |
| //! standard library's prelude you'll have to do so manually: |
| //! |
| //! ``` |
| //! # #[allow(unused_imports)] |
| //! use futures::prelude::*; |
| //! ``` |
| //! |
| //! The prelude may grow over time as additional items see ubiquitous use. |
| |
| </span><span class="kw">pub use </span><span class="kw">crate</span>::future::{<span class="self">self</span>, Future, TryFuture}; |
| <span class="kw">pub use </span><span class="kw">crate</span>::sink::{<span class="self">self</span>, Sink}; |
| <span class="kw">pub use </span><span class="kw">crate</span>::stream::{<span class="self">self</span>, Stream, TryStream}; |
| |
| <span class="attribute">#[doc(no_inline)] |
| #[allow(unreachable_pub)] |
| </span><span class="kw">pub use </span><span class="kw">crate</span>::future::{FutureExt <span class="kw">as _</span>, TryFutureExt <span class="kw">as _</span>}; |
| <span class="attribute">#[doc(no_inline)] |
| </span><span class="kw">pub use </span><span class="kw">crate</span>::sink::SinkExt <span class="kw">as _</span>; |
| <span class="attribute">#[doc(no_inline)] |
| #[allow(unreachable_pub)] |
| </span><span class="kw">pub use </span><span class="kw">crate</span>::stream::{StreamExt <span class="kw">as _</span>, TryStreamExt <span class="kw">as _</span>}; |
| |
| <span class="attribute">#[cfg(feature = <span class="string">"std"</span>)] |
| </span><span class="kw">pub use </span><span class="kw">crate</span>::io::{AsyncBufRead, AsyncRead, AsyncSeek, AsyncWrite}; |
| |
| <span class="attribute">#[cfg(feature = <span class="string">"std"</span>)] |
| #[doc(no_inline)] |
| #[allow(unreachable_pub)] |
| </span><span class="kw">pub use </span><span class="kw">crate</span>::io::{ |
| AsyncBufReadExt <span class="kw">as _</span>, AsyncReadExt <span class="kw">as _</span>, AsyncSeekExt <span class="kw">as _</span>, AsyncWriteExt <span class="kw">as _</span>, |
| }; |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="futures" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
