278 lines
14 KiB
HTML
278 lines
14 KiB
HTML
|
<!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_epoch` crate.">
|
|||
|
|
<meta name="keywords" content="rust, rustlang, rust-lang, crossbeam_epoch">
|
|||
|
|
|
|||
|
|
<title>crossbeam_epoch - 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="../main.css" id="themeStyle">
|
|||
|
|
<script src="../storage.js"></script>
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
</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>
|
|||
|
|
|
|||
|
|
<p class='location'>Crate crossbeam_epoch</p><div class="sidebar-elems"><div class="block items"><ul><li><a href="#structs">Structs</a></li><li><a href="#traits">Traits</a></li><li><a href="#functions">Functions</a></li></ul></div><p class='location'></p><script>window.sidebarCurrent = {name: 'crossbeam_epoch', 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">
|
|||
|
|
<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'>Crate <a class="mod" href=''>crossbeam_epoch</a></span><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_epoch/lib.rs.html#1-104' title='goto source code'>[src]</a></span></h1>
|
|||
|
|
<div class='docblock'><p>Epoch-based memory reclamation.</p>
|
|||
|
|
<p>An interesting problem concurrent collections deal with comes from the remove operation.
|
|||
|
|
Suppose that a thread removes an element from a lock-free map, while another thread is reading
|
|||
|
|
that same element at the same time. The first thread must wait until the second thread stops
|
|||
|
|
reading the element. Only then it is safe to destruct it.</p>
|
|||
|
|
<p>Programming languages that come with garbage collectors solve this problem trivially. The
|
|||
|
|
garbage collector will destruct the removed element when no thread can hold a reference to it
|
|||
|
|
anymore.</p>
|
|||
|
|
<p>This crate implements a basic memory reclamation mechanism, which is based on epochs. When an
|
|||
|
|
element gets removed from a concurrent collection, it is inserted into a pile of garbage and
|
|||
|
|
marked with the current epoch. Every time a thread accesses a collection, it checks the current
|
|||
|
|
epoch, attempts to increment it, and destructs some garbage that became so old that no thread
|
|||
|
|
can be referencing it anymore.</p>
|
|||
|
|
<p>That is the general mechanism behind epoch-based memory reclamation, but the details are a bit
|
|||
|
|
more complicated. Anyhow, memory reclamation is designed to be fully automatic and something
|
|||
|
|
users of concurrent collections don't have to worry much about.</p>
|
|||
|
|
<h1 id="pointers" class="section-header"><a href="#pointers">Pointers</a></h1>
|
|||
|
|
<p>Concurrent collections are built using atomic pointers. This module provides <a href="struct.Atomic.html"><code>Atomic</code></a>, which
|
|||
|
|
is just a shared atomic pointer to a heap-allocated object. Loading an <a href="struct.Atomic.html"><code>Atomic</code></a> yields a
|
|||
|
|
<a href="struct.Shared.html"><code>Shared</code></a>, which is an epoch-protected pointer through which the loaded object can be safely
|
|||
|
|
read.</p>
|
|||
|
|
<h1 id="pinning" class="section-header"><a href="#pinning">Pinning</a></h1>
|
|||
|
|
<p>Before an <a href="struct.Atomic.html"><code>Atomic</code></a> can be loaded, a participant must be <a href="fn.pin.html"><code>pin</code></a>ned. By pinning a participant
|
|||
|
|
we declare that any object that gets removed from now on must not be destructed just
|
|||
|
|
yet. Garbage collection of newly removed objects is suspended until the participant gets
|
|||
|
|
unpinned.</p>
|
|||
|
|
<h1 id="garbage" class="section-header"><a href="#garbage">Garbage</a></h1>
|
|||
|
|
<p>Objects that get removed from concurrent collections must be stashed away until all currently
|
|||
|
|
pinned participants get unpinned. Such objects can be stored into a thread-local or global
|
|||
|
|
storage, where they are kept until the right time for their destruction comes.</p>
|
|||
|
|
<p>There is a global shared instance of garbage queue. You can <a href="fn.defer.html"><code>defer</code></a> the execution of an
|
|||
|
|
arbitrary function until the global epoch is advanced enough. Most notably, concurrent data
|
|||
|
|
structures may defer the deallocation of an object.</p>
|
|||
|
|
<h1 id="apis" class="section-header"><a href="#apis">APIs</a></h1>
|
|||
|
|
<p>For majority of use cases, just use the default garbage collector by invoking <a href="fn.pin.html"><code>pin</code></a>. If you
|
|||
|
|
want to create your own garbage collector, use the <a href="struct.Collector.html"><code>Collector</code></a> API.</p>
|
|||
|
|
</div><h2 id='structs' class='section-header'><a href="#structs">Structs</a></h2>
|
|||
|
|
<table>
|
|||
|
|
<tr class=' module-item'>
|
|||
|
|
<td><a class="struct" href="struct.Atomic.html"
|
|||
|
|
title='struct crossbeam_epoch::Atomic'>Atomic</a></td>
|
|||
|
|
<td class='docblock-short'>
|
|||
|
|
<p>An atomic pointer that can be safely shared between threads.</p>
|
|||
|
|
|
|||
|
|
</td>
|
|||
|
|
</tr>
|
|||
|
|
<tr class=' module-item'>
|
|||
|
|
<td><a class="struct" href="struct.Collector.html"
|
|||
|
|
title='struct crossbeam_epoch::Collector'>Collector</a></td>
|
|||
|
|
<td class='docblock-short'>
|
|||
|
|
<p>An epoch-based garbage collector.</p>
|
|||
|
|
|
|||
|
|
</td>
|
|||
|
|
</tr>
|
|||
|
|
<tr class=' module-item'>
|
|||
|
|
<td><a class="struct" href="struct.CompareAndSetError.html"
|
|||
|
|
title='struct crossbeam_epoch::CompareAndSetError'>CompareAndSetError</a></td>
|
|||
|
|
<td class='docblock-short'>
|
|||
|
|
<p>The error returned on failed compare-and-set operation.</p>
|
|||
|
|
|
|||
|
|
</td>
|
|||
|
|
</tr>
|
|||
|
|
<tr class=' module-item'>
|
|||
|
|
<td><a class="struct" href="struct.Guard.html"
|
|||
|
|
title='struct crossbeam_epoch::Guard'>Guard</a></td>
|
|||
|
|
<td class='docblock-short'>
|
|||
|
|
<p>A guard that keeps the current thread pinned.</p>
|
|||
|
|
|
|||
|
|
</td>
|
|||
|
|
</tr>
|
|||
|
|
<tr class=' module-item'>
|
|||
|
|
<td><a class="struct" href="struct.Handle.html"
|
|||
|
|
title='struct crossbeam_epoch::Handle'>Handle</a></td>
|
|||
|
|
<td class='docblock-short'>
|
|||
|
|
<p>A handle to a garbage collector.</p>
|
|||
|
|
|
|||
|
|
</td>
|
|||
|
|
</tr>
|
|||
|
|
<tr class=' module-item'>
|
|||
|
|
<td><a class="struct" href="struct.Owned.html"
|
|||
|
|
title='struct crossbeam_epoch::Owned'>Owned</a></td>
|
|||
|
|
<td class='docblock-short'>
|
|||
|
|
<p>An owned heap-allocated object.</p>
|
|||
|
|
|
|||
|
|
</td>
|
|||
|
|
</tr>
|
|||
|
|
<tr class=' module-item'>
|
|||
|
|
<td><a class="struct" href="struct.Shared.html"
|
|||
|
|
title='struct crossbeam_epoch::Shared'>Shared</a></td>
|
|||
|
|
<td class='docblock-short'>
|
|||
|
|
<p>A pointer to an object protected by the epoch GC.</p>
|
|||
|
|
|
|||
|
|
</td>
|
|||
|
|
</tr></table><h2 id='traits' class='section-header'><a href="#traits">Traits</a></h2>
|
|||
|
|
<table>
|
|||
|
|
<tr class=' module-item'>
|
|||
|
|
<td><a class="trait" href="trait.CompareAndSetOrdering.html"
|
|||
|
|
title='trait crossbeam_epoch::CompareAndSetOrdering'>CompareAndSetOrdering</a></td>
|
|||
|
|
<td class='docblock-short'>
|
|||
|
|
<p>Memory orderings for compare-and-set operations.</p>
|
|||
|
|
|
|||
|
|
</td>
|
|||
|
|
</tr>
|
|||
|
|
<tr class=' module-item'>
|
|||
|
|
<td><a class="trait" href="trait.Pointer.html"
|
|||
|
|
title='trait crossbeam_epoch::Pointer'>Pointer</a></td>
|
|||
|
|
<td class='docblock-short'>
|
|||
|
|
<p>A trait for either <code>Owned</code> or <code>Shared</code> pointers.</p>
|
|||
|
|
|
|||
|
|
</td>
|
|||
|
|
</tr></table><h2 id='functions' class='section-header'><a href="#functions">Functions</a></h2>
|
|||
|
|
<table>
|
|||
|
|
<tr class=' module-item'>
|
|||
|
|
<td><a class="fn" href="fn.default_collector.html"
|
|||
|
|
title='fn crossbeam_epoch::default_collector'>default_collector</a></td>
|
|||
|
|
<td class='docblock-short'>
|
|||
|
|
<p>Returns the default handle associated with the current thread.</p>
|
|||
|
|
|
|||
|
|
</td>
|
|||
|
|
</tr>
|
|||
|
|
<tr class=' module-item'>
|
|||
|
|
<td><a class="fn" href="fn.default_handle.html"
|
|||
|
|
title='fn crossbeam_epoch::default_handle'>default_handle</a></td>
|
|||
|
|
<td class='docblock-short'>
|
|||
|
|
<p>Returns the default handle associated with the current thread.</p>
|
|||
|
|
|
|||
|
|
</td>
|
|||
|
|
</tr>
|
|||
|
|
<tr class=' module-item'>
|
|||
|
|
<td><a class="fn" href="fn.is_pinned.html"
|
|||
|
|
title='fn crossbeam_epoch::is_pinned'>is_pinned</a></td>
|
|||
|
|
<td class='docblock-short'>
|
|||
|
|
<p>Returns <code>true</code> if the current thread is pinned.</p>
|
|||
|
|
|
|||
|
|
</td>
|
|||
|
|
</tr>
|
|||
|
|
<tr class=' module-item'>
|
|||
|
|
<td><a class="fn" href="fn.pin.html"
|
|||
|
|
title='fn crossbeam_epoch::pin'>pin</a></td>
|
|||
|
|
<td class='docblock-short'>
|
|||
|
|
<p>Pins the current thread.</p>
|
|||
|
|
|
|||
|
|
</td>
|
|||
|
|
</tr>
|
|||
|
|
<tr class=' module-item'>
|
|||
|
|
<td><a class="fn" href="fn.unprotected.html"
|
|||
|
|
title='fn crossbeam_epoch::unprotected'>unprotected</a><a title='unsafe function' href='#'><sup>⚠</sup></a></td>
|
|||
|
|
<td class='docblock-short'>
|
|||
|
|
<p>Returns a reference to a dummy guard that allows unprotected access to <a href="struct.Atomic.html"><code>Atomic</code></a>s.</p>
|
|||
|
|
|
|||
|
|
</td>
|
|||
|
|
</tr></table></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><kbd>?</kbd></dt>
|
|||
|
|
<dd>Show this help dialog</dd>
|
|||
|
|
<dt><kbd>S</kbd></dt>
|
|||
|
|
<dd>Focus the search field</dd>
|
|||
|
|
<dt><kbd>↑</kbd></dt>
|
|||
|
|
<dd>Move up in search results</dd>
|
|||
|
|
<dt><kbd>↓</kbd></dt>
|
|||
|
|
<dd>Move down in search results</dd>
|
|||
|
|
<dt><kbd>↹</kbd></dt>
|
|||
|
|
<dd>Switch tab</dd>
|
|||
|
|
<dt><kbd>⏎</kbd></dt>
|
|||
|
|
<dd>Go to active search result</dd>
|
|||
|
|
<dt><kbd>+</kbd></dt>
|
|||
|
|
<dd>Expand all sections</dd>
|
|||
|
|
<dt><kbd>-</kbd></dt>
|
|||
|
|
<dd>Collapse 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>
|
|||
|
|
|
|||
|
|
<p>
|
|||
|
|
Search functions by type signature (e.g.
|
|||
|
|
<code>vec -> usize</code> or <code>* -> vec</code>)
|
|||
|
|
</p>
|
|||
|
|
</div>
|
|||
|
|
</div>
|
|||
|
|
</aside>
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
<script>
|
|||
|
|
window.rootPath = "../";
|
|||
|
|
window.currentCrate = "crossbeam_epoch";
|
|||
|
|
</script>
|
|||
|
|
<script src="../main.js"></script>
|
|||
|
|
<script defer src="../search-index.js"></script>
|
|||
|
|
</body>
|
|||
|
|
</html>
|