| <!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/crossbeam-deque-0.8.3/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="../../crossbeam_deque/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="../../crossbeam_deque/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">//! Concurrent work-stealing deques. |
| //! |
| //! These data structures are most commonly used in work-stealing schedulers. The typical setup |
| //! involves a number of threads, each having its own FIFO or LIFO queue (*worker*). There is also |
| //! one global FIFO queue (*injector*) and a list of references to *worker* queues that are able to |
| //! steal tasks (*stealers*). |
| //! |
| //! We spawn a new task onto the scheduler by pushing it into the *injector* queue. Each worker |
| //! thread waits in a loop until it finds the next task to run and then runs it. To find a task, it |
| //! first looks into its local *worker* queue, and then into the *injector* and *stealers*. |
| //! |
| //! # Queues |
| //! |
| //! [`Injector`] is a FIFO queue, where tasks are pushed and stolen from opposite ends. It is |
| //! shared among threads and is usually the entry point for new tasks. |
| //! |
| //! [`Worker`] has two constructors: |
| //! |
| //! * [`new_fifo()`] - Creates a FIFO queue, in which tasks are pushed and popped from opposite |
| //! ends. |
| //! * [`new_lifo()`] - Creates a LIFO queue, in which tasks are pushed and popped from the same |
| //! end. |
| //! |
| //! Each [`Worker`] is owned by a single thread and supports only push and pop operations. |
| //! |
| //! Method [`stealer()`] creates a [`Stealer`] that may be shared among threads and can only steal |
| //! tasks from its [`Worker`]. Tasks are stolen from the end opposite to where they get pushed. |
| //! |
| //! # Stealing |
| //! |
| //! Steal operations come in three flavors: |
| //! |
| //! 1. [`steal()`] - Steals one task. |
| //! 2. [`steal_batch()`] - Steals a batch of tasks and moves them into another worker. |
| //! 3. [`steal_batch_and_pop()`] - Steals a batch of tasks, moves them into another queue, and pops |
| //! one task from that worker. |
| //! |
| //! In contrast to push and pop operations, stealing can spuriously fail with [`Steal::Retry`], in |
| //! which case the steal operation needs to be retried. |
| //! |
| //! # Examples |
| //! |
| //! Suppose a thread in a work-stealing scheduler is idle and looking for the next task to run. To |
| //! find an available task, it might do the following: |
| //! |
| //! 1. Try popping one task from the local worker queue. |
| //! 2. Try stealing a batch of tasks from the global injector queue. |
| //! 3. Try stealing one task from another thread using the stealer list. |
| //! |
| //! An implementation of this work-stealing strategy: |
| //! |
| //! ``` |
| //! use crossbeam_deque::{Injector, Stealer, Worker}; |
| //! use std::iter; |
| //! |
| //! fn find_task<T>( |
| //! local: &Worker<T>, |
| //! global: &Injector<T>, |
| //! stealers: &[Stealer<T>], |
| //! ) -> Option<T> { |
| //! // Pop a task from the local queue, if not empty. |
| //! local.pop().or_else(|| { |
| //! // Otherwise, we need to look for a task elsewhere. |
| //! iter::repeat_with(|| { |
| //! // Try stealing a batch of tasks from the global queue. |
| //! global.steal_batch_and_pop(local) |
| //! // Or try stealing a task from one of the other threads. |
| //! .or_else(|| stealers.iter().map(|s| s.steal()).collect()) |
| //! }) |
| //! // Loop while no task was stolen and any steal operation needs to be retried. |
| //! .find(|s| !s.is_retry()) |
| //! // Extract the stolen task, if there is one. |
| //! .and_then(|s| s.success()) |
| //! }) |
| //! } |
| //! ``` |
| //! |
| //! [`new_fifo()`]: Worker::new_fifo |
| //! [`new_lifo()`]: Worker::new_lifo |
| //! [`stealer()`]: Worker::stealer |
| //! [`steal()`]: Stealer::steal |
| //! [`steal_batch()`]: Stealer::steal_batch |
| //! [`steal_batch_and_pop()`]: Stealer::steal_batch_and_pop |
| |
| </span><span class="attribute">#![doc(test( |
| no_crate_inject, |
| attr( |
| deny(warnings, rust_2018_idioms), |
| allow(dead_code, unused_assignments, unused_variables) |
| ) |
| ))] |
| #![warn( |
| missing_docs, |
| missing_debug_implementations, |
| rust_2018_idioms, |
| unreachable_pub |
| )] |
| #![cfg_attr(not(feature = <span class="string">"std"</span>), no_std)] |
| |
| </span><span class="kw">use </span>cfg_if::cfg_if; |
| |
| <span class="macro">cfg_if! </span>{ |
| <span class="kw">if </span><span class="attribute">#[cfg(feature = <span class="string">"std"</span>)] </span>{ |
| <span class="kw">use </span>crossbeam_epoch <span class="kw">as </span>epoch; |
| <span class="kw">use </span>crossbeam_utils <span class="kw">as </span>utils; |
| |
| <span class="kw">mod </span>deque; |
| <span class="kw">pub use </span><span class="kw">crate</span>::deque::{Injector, Steal, Stealer, Worker}; |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="crossbeam_deque" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
