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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>try_lock</h1>
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<div id="contentSub"><span class="subpages">&lt; <a href="cpp.html">cpp</a>&lrm; | <a href="cpp-thread.html">thread</a></span></div>
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<div>&#23450;&#20041;&#20110;&#22836;&#25991;&#20214; <code><a href="cpp-header-mutex.html">&lt;mutex&gt;</a></code></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1">&lt;</span> <span class="kw1">class</span> Lockable1, <span class="kw1">class</span> Lockable2, <span class="kw1">class</span>... <span class="me1">LockableN</span> <span class="sy1">&gt;</span><br />
<span class="kw4">int</span> try_lock<span class="br0">(</span> Lockable1<span class="sy3">&amp;</span> lock1, Lockable2<span class="sy3">&amp;</span> lock2, LockableN<span class="sy3">&amp;</span>... <span class="me1">lockn</span> <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 &#36215;)</span></td>
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<p>&#23581;&#35797;&#38145;&#23450;&#27599;&#20010;&#32473;&#23450;&#30340;<a href="cpp-named_req-Lockable.html"><span style="font-style:italic">&#21487;&#38145;&#23450;</span> <span style="font-family: Georgia, &#39;DejaVu Serif&#39;, serif; font-style:italic">(Lockable)</span></a> &#23545;&#35937; <code>lock1</code>&#12289; <code>lock2</code>&#12289; <code>...</code>&#12289; <code>lockn</code> &#65292;&#36890;&#36807;&#20197;&#20174;&#22836;&#24320;&#22987;&#30340;&#39034;&#24207;&#35843;&#29992; <code>try_lock</code> &#12290;</p>
<p>&#33509;&#35843;&#29992; <code>try_lock</code> &#22833;&#36133;&#65292;&#21017;&#19981;&#20877;&#36827;&#19968;&#27493;&#35843;&#29992; <code>try_lock</code> &#65292;&#24182;&#23545;&#20219;&#20309;&#24050;&#38145;&#23545;&#35937;&#35843;&#29992; <code>unlock</code> &#65292;&#36820;&#22238;&#38145;&#23450;&#22833;&#36133;&#23545;&#35937;&#30340; <code>0</code> &#24213;&#19979;&#26631;&#12290;</p>
<p>&#33509;&#35843;&#29992; <code>try_lock</code> &#25243;&#20986;&#24322;&#24120;&#65292;&#21017;&#22312;&#37325;&#25243;&#21069;&#23545;&#20219;&#20309;&#24050;&#38145;&#23545;&#35937;&#35843;&#29992; <code>unlock</code> &#12290;</p>
<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">&#21442;&#25968;</span></h3>
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<td>lock1, lock2, ... , lockn</td>
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<td>&#35201;&#38145;&#23450;&#30340;<a href="cpp-named_req-Lockable.html"><span style="font-style:italic">&#21487;&#38145;&#23450;</span> <span style="font-family: Georgia, &#39;DejaVu Serif&#39;, serif; font-style:italic">(Lockable)</span></a> &#23545;&#35937;</td>
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<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">&#36820;&#22238;&#20540;</span></h3>
<p>&#25104;&#21151;&#26102;&#20026; <code>-1</code> &#65292;&#21542;&#21017;&#20026;&#38145;&#23450;&#22833;&#36133;&#23545;&#35937;&#30340; <code>0</code> &#24213;&#19979;&#26631;&#20540;&#12290;</p>
<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">&#31034;&#20363;</span></h3>
<div class="t-example">
<p>&#19979;&#21015;&#31034;&#20363;&#29992; <code>std::try_lock</code> &#21608;&#26399;&#22320;&#35760;&#24405;&#24182;&#37325;&#32622;&#36816;&#34892;&#20110;&#20998;&#31163;&#32447;&#31243;&#30340;&#35745;&#25968;&#22120;&#12290;</p>
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<pre class="de1"><span class="co2">#include &lt;mutex&gt;</span>
<span class="co2">#include &lt;vector&gt;</span>
<span class="co2">#include &lt;thread&gt;</span>
<span class="co2">#include &lt;iostream&gt;</span>
<span class="co2">#include &lt;functional&gt;</span>
<span class="co2">#include &lt;chrono&gt;</span>
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
<span class="br0">{</span>
<span class="kw4">int</span> foo_count <span class="sy1">=</span> <span class="nu0">0</span><span class="sy4">;</span>
<a href="cpp-thread-mutex.html"><span class="kw2154">std::<span class="me2">mutex</span></span></a> foo_count_mutex<span class="sy4">;</span>
<span class="kw4">int</span> bar_count <span class="sy1">=</span> <span class="nu0">0</span><span class="sy4">;</span>
<a href="cpp-thread-mutex.html"><span class="kw2154">std::<span class="me2">mutex</span></span></a> bar_count_mutex<span class="sy4">;</span>
<span class="kw4">int</span> overall_count <span class="sy1">=</span> <span class="nu0">0</span><span class="sy4">;</span>
<span class="kw4">bool</span> done <span class="sy1">=</span> <span class="kw2">false</span><span class="sy4">;</span>
<a href="cpp-thread-mutex.html"><span class="kw2154">std::<span class="me2">mutex</span></span></a> done_mutex<span class="sy4">;</span>
<span class="kw4">auto</span> increment <span class="sy1">=</span> <span class="br0">[</span><span class="br0">]</span><span class="br0">(</span><span class="kw4">int</span> <span class="sy3">&amp;</span>counter, <a href="cpp-thread-mutex.html"><span class="kw2154">std::<span class="me2">mutex</span></span></a> <span class="sy3">&amp;</span>m, <span class="kw4">const</span> <span class="kw4">char</span> <span class="sy2">*</span>desc<span class="br0">)</span> <span class="br0">{</span>
<span class="kw1">for</span> <span class="br0">(</span><span class="kw4">int</span> i <span class="sy1">=</span> <span class="nu0">0</span><span class="sy4">;</span> i <span class="sy1">&lt;</span> <span class="nu0">10</span><span class="sy4">;</span> <span class="sy2">++</span>i<span class="br0">)</span> <span class="br0">{</span>
<a href="cpp-thread-unique_lock.html"><span class="kw2167">std::<span class="me2">unique_lock</span></span></a><span class="sy1">&lt;</span><a href="cpp-thread-mutex.html"><span class="kw2154">std::<span class="me2">mutex</span></span></a><span class="sy1">&gt;</span> lock<span class="br0">(</span>m<span class="br0">)</span><span class="sy4">;</span>
<span class="sy2">++</span>counter<span class="sy4">;</span>
<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> desc <span class="sy1">&lt;&lt;</span> <span class="st0">&quot;: &quot;</span> <span class="sy1">&lt;&lt;</span> counter <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span><span class="sy4">;</span>
lock.<span class="me1">unlock</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
<a href="cpp-thread-sleep_for.html"><span class="kw2149">std::<span class="me2">this_thread</span><span class="sy4">::</span><span class="me2">sleep_for</span></span></a><span class="br0">(</span><a href="cpp-chrono-duration.html"><span class="kw997">std::<span class="me2">chrono</span><span class="sy4">::</span><span class="me2">seconds</span></span></a><span class="br0">(</span><span class="nu0">1</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
<span class="br0">}</span>
<span class="br0">}</span><span class="sy4">;</span>
<a href="cpp-thread-thread.html"><span class="kw2146">std::<span class="me2">thread</span></span></a> increment_foo<span class="br0">(</span>increment, <a href="cpp-utility-functional-ref.html"><span class="kw1069">std::<span class="me2">ref</span></span></a><span class="br0">(</span>foo_count<span class="br0">)</span>,
<a href="cpp-utility-functional-ref.html"><span class="kw1069">std::<span class="me2">ref</span></span></a><span class="br0">(</span>foo_count_mutex<span class="br0">)</span>, <span class="st0">&quot;foo&quot;</span><span class="br0">)</span><span class="sy4">;</span>
<a href="cpp-thread-thread.html"><span class="kw2146">std::<span class="me2">thread</span></span></a> increment_bar<span class="br0">(</span>increment, <a href="cpp-utility-functional-ref.html"><span class="kw1069">std::<span class="me2">ref</span></span></a><span class="br0">(</span>bar_count<span class="br0">)</span>,
<a href="cpp-utility-functional-ref.html"><span class="kw1069">std::<span class="me2">ref</span></span></a><span class="br0">(</span>bar_count_mutex<span class="br0">)</span>, <span class="st0">&quot;bar&quot;</span><span class="br0">)</span><span class="sy4">;</span>
<a href="cpp-thread-thread.html"><span class="kw2146">std::<span class="me2">thread</span></span></a> update_overall<span class="br0">(</span><span class="br0">[</span><span class="sy3">&amp;</span><span class="br0">]</span><span class="br0">(</span><span class="br0">)</span> <span class="br0">{</span>
done_mutex.<span class="me1">lock</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
<span class="kw1">while</span> <span class="br0">(</span><span class="sy3">!</span>done<span class="br0">)</span> <span class="br0">{</span>
done_mutex.<span class="me1">unlock</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
<span class="kw4">int</span> result <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">try_lock</span><span class="br0">(</span>foo_count_mutex, bar_count_mutex<span class="br0">)</span><span class="sy4">;</span>
<span class="kw1">if</span> <span class="br0">(</span>result <span class="sy1">==</span> <span class="sy2">-</span><span class="nu0">1</span><span class="br0">)</span> <span class="br0">{</span>
overall_count <span class="sy2">+</span><span class="sy1">=</span> foo_count <span class="sy2">+</span> bar_count<span class="sy4">;</span>
foo_count <span class="sy1">=</span> <span class="nu0">0</span><span class="sy4">;</span>
bar_count <span class="sy1">=</span> <span class="nu0">0</span><span class="sy4">;</span>
<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> <span class="st0">&quot;overall: &quot;</span> <span class="sy1">&lt;&lt;</span> overall_count <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span><span class="sy4">;</span>
foo_count_mutex.<span class="me1">unlock</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
bar_count_mutex.<span class="me1">unlock</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
<span class="br0">}</span>
<a href="cpp-thread-sleep_for.html"><span class="kw2149">std::<span class="me2">this_thread</span><span class="sy4">::</span><span class="me2">sleep_for</span></span></a><span class="br0">(</span><a href="cpp-chrono-duration.html"><span class="kw997">std::<span class="me2">chrono</span><span class="sy4">::</span><span class="me2">seconds</span></span></a><span class="br0">(</span><span class="nu0">2</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
done_mutex.<span class="me1">lock</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
<span class="br0">}</span>
done_mutex.<span class="me1">unlock</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
<span class="br0">}</span><span class="br0">)</span><span class="sy4">;</span>
increment_foo.<span class="me1">join</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
increment_bar.<span class="me1">join</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
done_mutex.<span class="me1">lock</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
done <span class="sy1">=</span> <span class="kw2">true</span><span class="sy4">;</span>
done_mutex.<span class="me1">unlock</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
update_overall.<span class="me1">join</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> <span class="st0">&quot;Done processing<span class="es1">\n</span>&quot;</span>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot;foo: &quot;</span> <span class="sy1">&lt;&lt;</span> foo_count <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot;bar: &quot;</span> <span class="sy1">&lt;&lt;</span> bar_count <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot;overall: &quot;</span> <span class="sy1">&lt;&lt;</span> overall_count <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span><span class="sy4">;</span>
<span class="br0">}</span></pre></div>
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<p>&#21487;&#33021;&#30340;&#36755;&#20986;&#65306;</p>
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<pre class="de1">bar: 1
foo: 1
foo: 2
bar: 2
foo: 3
overall: 5
bar: 1
foo: 1
bar: 2
foo: 2
bar: 3
overall: 10
bar: 1
foo: 1
bar: 2
foo: 2
overall: 14
bar: 1
foo: 1
bar: 2
overall: 17
foo: 1
bar: 1
foo: 2
overall: 20
Done processing
foo: 0
bar: 0
overall: 20</pre></div>
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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">&#21442;&#38405;</span></h3>
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<div><a href="cpp-thread-lock.html"><span class="t-lines"><span>lock</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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<td>&#38145;&#23450;&#25351;&#23450;&#30340;&#20114;&#26021;&#20307;&#65292;&#33509;&#20219;&#20309;&#19968;&#20010;&#19981;&#21487;&#29992;&#21017;&#38459;&#22622;<br />
<span class="t-mark">(&#20989;&#25968;&#27169;&#26495;)</span></td>
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