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<!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="API documentation for the Rust `crossbeam_deque` crate."><meta name="keywords" content="rust, rustlang, rust-lang, crossbeam_deque"><title>crossbeam_deque - Rust</title><link rel="stylesheet" type="text/css" href="../normalize.css"><link rel="stylesheet" type="text/css" href="../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../dark.css"><link rel="stylesheet" type="text/css" href="../light.css" id="themeStyle"><script src="../storage.js"></script><noscript><link rel="stylesheet" href="../noscript.css"></noscript><link rel="shortcut icon" href="../favicon.ico"><style type="text/css">#crate-search{background-image:url("../down-arrow.svg");}</style></head><body class="rustdoc mod"><!--[if lte IE 8]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><div class="sidebar-menu">☰</div><a href='../crossbeam_deque/index.html'><div class='logo-container'><img src='../rust-logo.png' alt='logo'></div></a><p class='location'>Crate crossbeam_deque</p><div class="sidebar-elems"><a id='all-types' href='all.html'><p>See all crossbeam_deque's items</p></a><div class="block items"><ul><li><a href="#structs">Structs</a></li><li><a href="#enums">Enums</a></li><li><a href="#functions">Functions</a></li></ul></div><p class='location'></p><script>window.sidebarCurrent = {name: 'crossbeam_deque', ty: 'mod', relpath: '../'};</script></div></nav><div class="theme-picker"><button id="theme-picker" aria-label="Pick another theme!"><img src="../brush.svg" width="18" alt="Pick another theme!"></button><div id="theme-choices"></div></div><script src="../theme.js"></script><nav class="sub"><form class="search-form js-only"><div class="search-container"><div><select id="crate-search"><option value="All crates">All crates</option></select><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"></div><a id="settings-menu" href="../settings.html"><img src="../wheel.svg" width="18" alt="Change settings"></a></div></form></nav><section id="main" class="content"><h1 class='fqn'><span class='out-of-band'><span id='render-detail'><a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class='inner'>−</span>]</a></span><a class='srclink' href='../src/crossbeam_deque/lib.rs.html#1-879' title='goto source code'>[src]</a></span><span class='in-band'>Crate <a class="mod" href=''>crossbeam_deque</a></span></h1><div class='docblock'><p>A concurrent work-stealing deque.</p>
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<p>This data structure is most commonly used in schedulers. The typical setup involves a number of
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threads where each thread has its own deque containing tasks. A thread may push tasks into its
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deque as well as pop tasks from it. Once it runs out of tasks, it may steal some from other
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threads to help complete tasks more quickly. Therefore, work-stealing deques supports three
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essential operations: <em>push</em>, <em>pop</em>, and <em>steal</em>.</p>
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<h1 id="types-of-deques" class="section-header"><a href="#types-of-deques">Types of deques</a></h1>
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<p>There are two types of deques, differing only in which order tasks get pushed and popped. The
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two task ordering strategies are:</p>
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<ul>
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<li>First-in first-out (FIFO)</li>
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<li>Last-in first-out (LIFO)</li>
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</ul>
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<p>A deque is a buffer with two ends, front and back. In a FIFO deque, tasks are pushed into the
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back, popped from the front, and stolen from the front. However, in a LIFO deque, tasks are
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popped from the back instead - that is the only difference.</p>
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<h1 id="workers-and-stealers" class="section-header"><a href="#workers-and-stealers">Workers and stealers</a></h1>
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<p>There are two functions that construct a deque: <a href="fn.fifo.html"><code>fifo</code></a> and <a href="fn.lifo.html"><code>lifo</code></a>. These functions return a
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<a href="struct.Worker.html"><code>Worker</code></a> and a <a href="struct.Stealer.html"><code>Stealer</code></a>. The thread which owns the deque is usually called <em>worker</em>, while
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all other threads are <em>stealers</em>.</p>
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<p><a href="struct.Worker.html"><code>Worker</code></a> is able to push and pop tasks. It cannot be shared among multiple threads - only
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one thread owns it.</p>
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<p><a href="struct.Stealer.html"><code>Stealer</code></a> can only steal tasks. It can be shared among multiple threads by reference or by
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cloning. Cloning a <a href="struct.Stealer.html"><code>Stealer</code></a> simply creates another one associated with the same deque.</p>
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<h1 id="examples" class="section-header"><a href="#examples">Examples</a></h1>
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<div class="example-wrap"><pre class="rust rust-example-rendered">
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<span class="kw">use</span> <span class="ident">crossbeam_deque</span>::{<span class="self">self</span> <span class="kw">as</span> <span class="ident">deque</span>, <span class="ident">Pop</span>, <span class="ident">Steal</span>};
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<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">thread</span>;
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<span class="comment">// Create a LIFO deque.</span>
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<span class="kw">let</span> (<span class="ident">w</span>, <span class="ident">s</span>) <span class="op">=</span> <span class="ident">deque</span>::<span class="ident">lifo</span>();
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<span class="comment">// Push several elements into the back.</span>
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<span class="ident">w</span>.<span class="ident">push</span>(<span class="number">1</span>);
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<span class="ident">w</span>.<span class="ident">push</span>(<span class="number">2</span>);
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<span class="ident">w</span>.<span class="ident">push</span>(<span class="number">3</span>);
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<span class="comment">// This is a LIFO deque, which means an element is popped from the back.</span>
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<span class="comment">// If it was a FIFO deque, `w.pop()` would return `Some(1)`.</span>
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<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">w</span>.<span class="ident">pop</span>(), <span class="ident">Pop</span>::<span class="ident">Data</span>(<span class="number">3</span>));
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<span class="comment">// Create a stealer thread.</span>
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<span class="ident">thread</span>::<span class="ident">spawn</span>(<span class="kw">move</span> <span class="op">|</span><span class="op">|</span> {
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<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">s</span>.<span class="ident">steal</span>(), <span class="ident">Steal</span>::<span class="ident">Data</span>(<span class="number">1</span>));
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<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">s</span>.<span class="ident">steal</span>(), <span class="ident">Steal</span>::<span class="ident">Data</span>(<span class="number">2</span>));
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}).<span class="ident">join</span>().<span class="ident">unwrap</span>();</pre></div>
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</div><h2 id='structs' class='section-header'><a href="#structs">Structs</a></h2>
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<table><tr class='module-item'><td><a class="struct" href="struct.Stealer.html" title='crossbeam_deque::Stealer struct'>Stealer</a></td><td class='docblock-short'><p>The stealer side of a deque.</p>
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</td></tr><tr class='module-item'><td><a class="struct" href="struct.Worker.html" title='crossbeam_deque::Worker struct'>Worker</a></td><td class='docblock-short'><p>The worker side of a deque.</p>
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</td></tr></table><h2 id='enums' class='section-header'><a href="#enums">Enums</a></h2>
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<table><tr class='module-item'><td><a class="enum" href="enum.Pop.html" title='crossbeam_deque::Pop enum'>Pop</a></td><td class='docblock-short'><p>Possible outcomes of a pop operation.</p>
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</td></tr><tr class='module-item'><td><a class="enum" href="enum.Steal.html" title='crossbeam_deque::Steal enum'>Steal</a></td><td class='docblock-short'><p>Possible outcomes of a steal operation.</p>
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</td></tr></table><h2 id='functions' class='section-header'><a href="#functions">Functions</a></h2>
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<table><tr class='module-item'><td><a class="fn" href="fn.fifo.html" title='crossbeam_deque::fifo fn'>fifo</a></td><td class='docblock-short'><p>Creates a work-stealing deque with the first-in first-out strategy.</p>
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</td></tr><tr class='module-item'><td><a class="fn" href="fn.lifo.html" title='crossbeam_deque::lifo fn'>lifo</a></td><td class='docblock-short'><p>Creates a work-stealing deque with the last-in first-out strategy.</p>
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