<!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 `Ordering` enum in crate `core`."> <meta name="keywords" content="rust, rustlang, rust-lang, Ordering"> <title>core::sync::atomic::Ordering - Rust</title> <link rel="stylesheet" type="text/css" href="../../../normalize.css"> <link rel="stylesheet" type="text/css" href="../../../rustdoc.css"> <link rel="stylesheet" type="text/css" href="../../../main.css"> <link rel="shortcut icon" href="https://doc.rust-lang.org/favicon.ico"> </head> <body class="rustdoc enum"> <!--[if lte IE 8]> <div class="warning"> This old browser is unsupported and will most likely display funky things. </div> <![endif]--> <nav class="sidebar"> <a href='../../../core/index.html'><img src='https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png' alt='logo' width='100'></a> <p class='location'>Enum Ordering</p><div class="block items"><ul><li><a href="#variants">Variants</a></li><li><a href="#implementations">Trait Implementations</a></li></ul></div><p class='location'><a href='../../index.html'>core</a>::<wbr><a href='../index.html'>sync</a>::<wbr><a href='index.html'>atomic</a></p><script>window.sidebarCurrent = {name: 'Ordering', ty: 'enum', relpath: ''};</script><script defer src="sidebar-items.js"></script> </nav> <nav class="sub"> <form class="search-form js-only"> <div class="search-container"> <input class="search-input" name="search" autocomplete="off" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"> </div> </form> </nav> <section id='main' class="content"> <h1 class='fqn'><span class='in-band'>Enum <a href='../../index.html'>core</a>::<wbr><a href='../index.html'>sync</a>::<wbr><a href='index.html'>atomic</a>::<wbr><a class="enum" href=''>Ordering</a></span><span class='out-of-band'><span class='since' title='Stable since Rust version 1.0.0'>1.0.0</span><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/core/sync/atomic.rs.html#184-221' title='goto source code'>[src]</a></span></h1> <pre class='rust enum'>pub enum Ordering { Relaxed, Release, Acquire, AcqRel, SeqCst, // some variants omitted }</pre><div class='docblock'><p>Atomic memory orderings</p> <p>Memory orderings limit the ways that both the compiler and CPU may reorder instructions around atomic operations. At its most restrictive, "sequentially consistent" atomics allow neither reads nor writes to be moved either before or after the atomic operation; on the other end "relaxed" atomics allow all reorderings.</p> <p>Rust's memory orderings are <a href="http://llvm.org/docs/LangRef.html#memory-model-for-concurrent-operations">the same as LLVM's</a>.</p> <p>For more information see the <a href="../../../nomicon/atomics.html">nomicon</a>.</p> </div><h2 id='variants' class='variants'>Variants</h2> <span id='variant.Relaxed' class='variant'><span id='Relaxed.v' class='invisible'><code>Relaxed</code></span></span><div class='docblock'><p>No ordering constraints, only atomic operations.</p> <p>Corresponds to LLVM's <a href="http://llvm.org/docs/Atomics.html#monotonic"><code>Monotonic</code></a> ordering.</p> </div><span id='variant.Release' class='variant'><span id='Release.v' class='invisible'><code>Release</code></span></span><div class='docblock'><p>When coupled with a store, all previous writes become visible to the other threads that perform a load with <a href="http://llvm.org/docs/Atomics.html#acquire"><code>Acquire</code></a> ordering on the same value.</p> </div><span id='variant.Acquire' class='variant'><span id='Acquire.v' class='invisible'><code>Acquire</code></span></span><div class='docblock'><p>When coupled with a load, all subsequent loads will see data written before a store with <a href="http://llvm.org/docs/Atomics.html#release"><code>Release</code></a> ordering on the same value in other threads.</p> </div><span id='variant.AcqRel' class='variant'><span id='AcqRel.v' class='invisible'><code>AcqRel</code></span></span><div class='docblock'><p>When coupled with a load, uses <a href="http://llvm.org/docs/Atomics.html#acquire"><code>Acquire</code></a> ordering, and with a store <a href="http://llvm.org/docs/Atomics.html#release"><code>Release</code></a> ordering.</p> </div><span id='variant.SeqCst' class='variant'><span id='SeqCst.v' class='invisible'><code>SeqCst</code></span></span><div class='docblock'><p>Like <code>AcqRel</code> with the additional guarantee that all threads see all sequentially consistent operations in the same order.</p> </div><h2 id='implementations'>Trait Implementations</h2><h3 class='impl'><span class='in-band'><code>impl <a class="trait" href="../../../core/marker/trait.Copy.html" title="trait core::marker::Copy">Copy</a> for <a class="enum" href="../../../core/sync/atomic/enum.Ordering.html" title="enum core::sync::atomic::Ordering">Ordering</a></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../../src/core/sync/atomic.rs.html#183' title='goto source code'>[src]</a></span></h3> <div class='impl-items'></div><h3 class='impl'><span class='in-band'><code>impl <a class="trait" href="../../../core/clone/trait.Clone.html" title="trait core::clone::Clone">Clone</a> for <a class="enum" href="../../../core/sync/atomic/enum.Ordering.html" title="enum core::sync::atomic::Ordering">Ordering</a></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../../src/core/sync/atomic.rs.html#183' title='goto source code'>[src]</a></span></h3> <div class='impl-items'><h4 id='method.clone' class="method"><span id='clone.v' class='invisible'><code>fn <a href='../../../core/clone/trait.Clone.html#tymethod.clone' class='fnname'>clone</a>(&self) -> <a class="enum" href="../../../core/sync/atomic/enum.Ordering.html" title="enum core::sync::atomic::Ordering">Ordering</a></code></span></h4> <div class='docblock'><p>Returns a copy of the value. <a href="../../../core/clone/trait.Clone.html#tymethod.clone">Read more</a></p> </div><h4 id='method.clone_from' class="method"><span id='clone_from.v' class='invisible'><code>fn <a href='../../../core/clone/trait.Clone.html#method.clone_from' class='fnname'>clone_from</a>(&mut self, source: &Self)</code></span></h4> <div class='docblock'><p>Performs copy-assignment from <code>source</code>. <a href="../../../core/clone/trait.Clone.html#method.clone_from">Read more</a></p> </div></div><h3 class='impl'><span class='in-band'><code>impl <a class="trait" href="../../../core/fmt/trait.Debug.html" title="trait core::fmt::Debug">Debug</a> for <a class="enum" href="../../../core/sync/atomic/enum.Ordering.html" title="enum core::sync::atomic::Ordering">Ordering</a></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../../src/core/sync/atomic.rs.html#183' title='goto source code'>[src]</a></span></h3> <div class='impl-items'><h4 id='method.fmt' class="method"><span id='fmt.v' class='invisible'><code>fn <a href='../../../core/fmt/trait.Debug.html#tymethod.fmt' class='fnname'>fmt</a>(&self, __arg_0: &mut <a class="struct" href="../../../core/fmt/struct.Formatter.html" title="struct core::fmt::Formatter">Formatter</a>) -> <a class="type" href="../../../core/fmt/type.Result.html" title="type core::fmt::Result">Result</a></code></span></h4> <div class='docblock'><p>Formats the value using the given formatter.</p> </div></div></section> <section id='search' class="content hidden"></section> <section class="footer"></section> <aside id="help" class="hidden"> <div> <h1 class="hidden">Help</h1> <div class="shortcuts"> <h2>Keyboard Shortcuts</h2> <dl> <dt>?</dt> <dd>Show this help dialog</dd> <dt>S</dt> <dd>Focus the search field</dd> <dt>⇤</dt> <dd>Move up in search results</dd> <dt>⇥</dt> <dd>Move down in search results</dd> <dt>⏎</dt> <dd>Go to active search result</dd> <dt>+</dt> <dd>Collapse/expand all sections</dd> </dl> </div> <div class="infos"> <h2>Search Tricks</h2> <p> Prefix searches with a type followed by a colon (e.g. <code>fn:</code>) to restrict the search to a given type. </p> <p> Accepted types are: <code>fn</code>, <code>mod</code>, <code>struct</code>, <code>enum</code>, <code>trait</code>, <code>type</code>, <code>macro</code>, and <code>const</code>. </p> 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