92 lines
7.4 KiB
HTML
92 lines
7.4 KiB
HTML
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<html lang="zh" dir="ltr" class="client-nojs" xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh">
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<title>std::this_thread::yield</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_thread_yield skin-cppreference2 action-view cpp-navbar">
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::this_thread::</span>yield</h1>
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<div id="bodyContent">
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-thread.html">thread</a></span></div>
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<div>定义于头文件 <code><a href="cpp-header-thread.html"><thread></a></code></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">void</span> yield<span class="br0">(</span><span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
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<p>提供提示给实现,以重调度线程的执行,允许其他线程运行。</p>
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<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">参数</span></h3>
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<p>(无)</p>
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<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">返回值</span></h3>
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<p>(无)</p>
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<h3><span class="mw-headline" id=".E6.B3.A8.E6.84.8F">注意</span></h3>
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<p>此函数的准确性为依赖于实现,特别是使用中的 OS 调度器机制和系统状态。例如,先进先出实时调度器( Linux 的 <code>SCHED_FIFO</code> )将悬挂当前线程并将它放到准备运行的同优先级线程的队列尾(而若无其他线程在同优先级,则 <code>yield</code> 无效果)。</p>
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<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
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<div class="cpp source-cpp">
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<pre class="de1"><span class="co2">#include <iostream></span>
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<span class="co2">#include <chrono></span>
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<span class="co2">#include <thread></span>
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<span class="co1">// 建议其他线程运行一小段时间的“忙睡眠”</span>
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<span class="kw4">void</span> little_sleep<span class="br0">(</span><a href="cpp-chrono-duration.html"><span class="kw995">std::<span class="me2">chrono</span><span class="sy4">::</span><span class="me2">microseconds</span></span></a> us<span class="br0">)</span>
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<span class="br0">{</span>
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<span class="kw4">auto</span> start <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">high_resolution_clock</span><span class="sy4">::</span><span class="me2">now</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw4">auto</span> end <span class="sy1">=</span> start <span class="sy2">+</span> us<span class="sy4">;</span>
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<span class="kw1">do</span> <span class="br0">{</span>
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std<span class="sy4">::</span><span class="me2">this_thread</span><span class="sy4">::</span><span class="me2">yield</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="br0">}</span> <span class="kw1">while</span> <span class="br0">(</span>std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">high_resolution_clock</span><span class="sy4">::</span><span class="me2">now</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1"><</span> end<span class="br0">)</span><span class="sy4">;</span>
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<span class="br0">}</span>
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<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
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<span class="br0">{</span>
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<span class="kw4">auto</span> start <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">high_resolution_clock</span><span class="sy4">::</span><span class="me2">now</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
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little_sleep<span class="br0">(</span><a href="cpp-chrono-duration.html"><span class="kw995">std::<span class="me2">chrono</span><span class="sy4">::</span><span class="me2">microseconds</span></span></a><span class="br0">(</span><span class="nu0">100</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw4">auto</span> elapsed <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">high_resolution_clock</span><span class="sy4">::</span><span class="me2">now</span><span class="br0">(</span><span class="br0">)</span> <span class="sy2">-</span> start<span class="sy4">;</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"waited for "</span>
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<span class="sy1"><<</span> <a href="cpp-chrono-duration-duration_cast.html"><span class="kw1000">std::<span class="me2">chrono</span><span class="sy4">::</span><span class="me2">duration_cast</span></span></a><span class="sy1"><</span><a href="cpp-chrono-duration.html"><span class="kw995">std::<span class="me2">chrono</span><span class="sy4">::</span><span class="me2">microseconds</span></span></a><span class="sy1">></span><span class="br0">(</span>elapsed<span class="br0">)</span>.<span class="me1">count</span><span class="br0">(</span><span class="br0">)</span>
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<span class="sy1"><<</span> <span class="st0">" microseconds<span class="es1">\n</span>"</span><span class="sy4">;</span>
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<span class="br0">}</span></pre></div>
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<p>可能的输出:</p>
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
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<div class="text source-text">
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<pre class="de1">waited for 128 microseconds</pre></div>
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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</span></h3>
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