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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::future&lt;T&gt;::</span>wait_until</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>&lrm; | <a href="cpp-thread-future.html">future</a></span></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> Clock, <span class="kw1">class</span> Duration <span class="sy1">&gt;</span><br />
<a href="cpp-thread-future_status.html"><span class="kw2188">std::<span class="me2">future_status</span></span></a> wait_until<span class="br0">(</span> <span class="kw4">const</span> <a href="cpp-chrono-time_point.html"><span class="kw991">std::<span class="me2">chrono</span><span class="sy4">::</span><span class="me2">time_point</span></span></a><span class="sy1">&lt;</span>Clock,Duration<span class="sy1">&gt;</span><span class="sy3">&amp;</span> timeout_time <span class="br0">)</span> <span class="kw4">const</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><code>wait_until</code> &#31561;&#24453;&#32467;&#26524;&#21464;&#20026;&#21487;&#29992;&#12290;&#23427;&#38459;&#22622;&#30452;&#33267;&#25269;&#36798;&#25351;&#23450;&#30340; <code>timeout_time</code> &#65292;&#25110;&#32467;&#26524;&#21464;&#20026;&#21487;&#29992;&#65292;&#20004;&#32773;&#30340;&#20808;&#21040;&#26469;&#32773;&#12290;&#36820;&#22238;&#20540;&#25351;&#31034; <code>wait_until</code> &#20026;&#20309;&#36820;&#22238;&#12290;</p>
<p>&#33509;&#35843;&#29992;&#27492;&#20989;&#25968;&#21069; <span class="t-lc"><a href="cpp-thread-future-valid.html">valid()</a></span> &#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> &#65292;&#25110; <code>Clock</code> &#19981;&#31526;&#21512;<a href="cpp-named_req-Clock.html"><span style="font-style:italic">&#26102;&#38047;</span> <span style="font-family: Georgia, &#39;DejaVu Serif&#39;, serif; font-style:italic">(Clock)</span></a> &#35201;&#27714;&#21017;&#34892;&#20026;&#26410;&#23450;&#20041;&#12290;<span class="t-rev-inl t-since-cxx20"><span>&#33509; <span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">is_clock_v</span><span class="sy1">&lt;</span>Clock<span class="sy1">&gt;</span></span></span> &#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> &#21017;&#31243;&#24207;&#20026;&#38750;&#33391;&#26500;&#12290;</span> <span><span class="t-mark-rev t-since-cxx20">(C++20 &#36215;)</span></span></span></p>
<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">&#21442;&#25968;</span></h3>
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<td>timeout_time</td>
<td>-</td>
<td>&#35201;&#38459;&#22622;&#21040;&#30340;&#26368;&#22823;&#26102;&#38388;&#28857;</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>
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<td>&#24120;&#37327;</td>
<td>&#35299;&#37322;</td>
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<td><a href="cpp-thread-future_status.html"><tt>future_status::deferred</tt></a></td>
<td>&#20849;&#20139;&#29366;&#24577;&#25345;&#26377;&#30340;&#20989;&#25968;&#27491;&#22312;&#24310;&#36831;&#36816;&#34892;&#65292;&#32467;&#26524;&#23558;&#20165;&#22312;&#26174;&#24335;&#35831;&#27714;&#26102;&#35745;&#31639;</td>
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<td><a href="cpp-thread-future_status.html"><tt>future_status::ready</tt></a></td>
<td>&#20849;&#20139;&#29366;&#24577;&#23601;&#32490;</td>
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<td><a href="cpp-thread-future_status.html"><tt>future_status::timeout</tt></a></td>
<td>&#20849;&#20139;&#29366;&#24577;&#22312;&#32463;&#36807;&#25351;&#23450;&#30340;&#31561;&#24453;&#26102;&#38388;&#20869;&#20173;&#26410;&#23601;&#32490;</td>
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<h3><span class="mw-headline" id=".E5.BC.82.E5.B8.B8">&#24322;&#24120;</span></h3>
<p>&#26102;&#38047;&#12289;&#26102;&#38388;&#28857;&#25110;&#26102;&#38271;&#22312;&#25191;&#34892;&#20013;&#21487;&#33021;&#25243;&#30340;&#20219;&#20309;&#24322;&#24120;&#65288;&#26631;&#20934;&#24211;&#25552;&#20379;&#30340;&#26102;&#38047;&#12289;&#26102;&#38388;&#28857;&#21644;&#26102;&#38271;&#20915;&#19981;&#25243;&#20986;&#65289;&#12290;</p>
<h3><span class="mw-headline" id=".E6.B3.A8.E8.A7.A3">&#27880;&#35299;</span></h3>
<p>&#40723;&#21169;&#23454;&#29616;&#22312;&#35843;&#29992;&#21069;&#26816;&#27979; <span class="t-c"><span class="mw-geshi cpp source-cpp">valid<span class="br0">(</span><span class="br0">)</span> <span class="sy1">==</span> <span class="kw2">false</span></span></span> &#30340;&#24773;&#20917;&#24182;&#25243;&#20986;&#20197; <a href="cpp-thread-future_errc.html"><tt>future_errc::no_state</tt></a> &#20026;&#38169;&#35823;&#26465;&#20214;&#30340; <span class="t-lc"><a href="cpp-thread-future_error.html">std::future_error</a></span> &#12290;</p>
<p>&#20351;&#29992;&#20542;&#21521; <code>timeout_time</code> &#30340;&#26102;&#38047;&#65292;&#19981;&#35201;&#27714;&#26159;&#21333;&#35843;&#26102;&#38047;&#12290;&#33509;&#19981;&#36830;&#32493;&#22320;&#35843;&#33410;&#26102;&#38047;&#65292;&#21017;&#19981;&#23545;&#27492;&#20989;&#25968;&#30340;&#34892;&#20026;&#20445;&#35777;&#65292;&#20294;&#26082;&#23384;&#23454;&#29616;&#23558; <code>timeout_time</code> &#20174; <code>Clock</code> &#36716;&#25442;&#21040; <span class="t-lc"><a href="cpp-chrono-system_clock.html">std::chrono::system_clock</a></span> &#65292;&#24182;&#22996;&#25176; POSIX <a rel="nofollow" class="external text" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_cond_timedwait.html"><code>pthread_cond_timedwait</code></a> &#20197;&#20196;&#31561;&#24453;&#24544;&#23454;&#20110;&#31995;&#32479;&#26102;&#38047;&#65292;&#20294;&#38750;&#29992;&#25143;&#25552;&#20379; <code>Clock</code> &#30340;&#35843;&#33410;&#12290;&#20219;&#20309;&#24773;&#20917;&#19979;&#65292;&#30001;&#20110;&#35843;&#24230;&#25110;&#36164;&#28304;&#20105;&#35758;&#24310;&#36831;&#65292;&#20989;&#25968;&#21487;&#33021;&#31561;&#24453;&#38271;&#20110;&#25269;&#36798; <code>timeout_time</code> &#12290;</p>
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<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">&#31034;&#20363;</span></h3>
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<pre class="de1"><span class="co2">#include &lt;iostream&gt;</span>
<span class="co2">#include &lt;future&gt;</span>
<span class="co2">#include &lt;thread&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>
std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">system_clock</span><span class="sy4">::</span><span class="me2">time_point</span> two_seconds_passed
<span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">system_clock</span><span class="sy4">::</span><span class="me2">now</span><span class="br0">(</span><span class="br0">)</span> <span class="sy2">+</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="sy4">;</span>
<span class="co1">// &#20570;&#20986;&#33457; 1 &#31186;&#23436;&#25104;&#30340; future</span>
<a href="cpp-thread-promise.html"><span class="kw2179">std::<span class="me2">promise</span></span></a><span class="sy1">&lt;</span><span class="kw4">int</span><span class="sy1">&gt;</span> p1<span class="sy4">;</span>
<a href="cpp-thread-future.html"><span class="kw2180">std::<span class="me2">future</span></span></a><span class="sy1">&lt;</span><span class="kw4">int</span><span class="sy1">&gt;</span> f_completes <span class="sy1">=</span> p1.<span class="me1">get_future</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><span class="br0">(</span><span class="br0">[</span><span class="br0">]</span><span class="br0">(</span><a href="cpp-thread-promise.html"><span class="kw2179">std::<span class="me2">promise</span></span></a><span class="sy1">&lt;</span><span class="kw4">int</span><span class="sy1">&gt;</span> p1<span class="br0">)</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">1</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
p1.<span class="me1">set_value_at_thread_exit</span><span class="br0">(</span><span class="nu0">9</span><span class="br0">)</span><span class="sy4">;</span>
<span class="br0">}</span>,
std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>p1<span class="br0">)</span>
<span class="br0">)</span>.<span class="me1">detach</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
<span class="co1">// &#20570;&#20986;&#33457; 5 &#31186;&#23436;&#25104;&#30340; future</span>
<a href="cpp-thread-promise.html"><span class="kw2179">std::<span class="me2">promise</span></span></a><span class="sy1">&lt;</span><span class="kw4">int</span><span class="sy1">&gt;</span> p2<span class="sy4">;</span>
<a href="cpp-thread-future.html"><span class="kw2180">std::<span class="me2">future</span></span></a><span class="sy1">&lt;</span><span class="kw4">int</span><span class="sy1">&gt;</span> f_times_out <span class="sy1">=</span> p2.<span class="me1">get_future</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><span class="br0">(</span><span class="br0">[</span><span class="br0">]</span><span class="br0">(</span><a href="cpp-thread-promise.html"><span class="kw2179">std::<span class="me2">promise</span></span></a><span class="sy1">&lt;</span><span class="kw4">int</span><span class="sy1">&gt;</span> p2<span class="br0">)</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">5</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
p2.<span class="me1">set_value_at_thread_exit</span><span class="br0">(</span><span class="nu0">8</span><span class="br0">)</span><span class="sy4">;</span>
<span class="br0">}</span>,
std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>p2<span class="br0">)</span>
<span class="br0">)</span>.<span class="me1">detach</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;Waiting for 2 seconds...&quot;</span> <span class="sy1">&lt;&lt;</span> <a href="cpp-io-manip-endl.html"><span class="kw1791">std::<span class="me2">endl</span></span></a><span class="sy4">;</span>
<span class="kw1">if</span><span class="br0">(</span><a href="cpp-thread-future_status.html"><span class="kw2189">std::<span class="me2">future_status</span><span class="sy4">::</span><span class="me2">ready</span></span></a> <span class="sy1">==</span> f_completes.<span class="me1">wait_until</span><span class="br0">(</span>two_seconds_passed<span class="br0">)</span><span class="br0">)</span>
<span class="br0">{</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;f_completes: &quot;</span> <span class="sy1">&lt;&lt;</span> f_completes.<span class="me1">get</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&quot;<span class="es1">\n</span>&quot;</span><span class="sy4">;</span> <span class="br0">}</span>
<span class="kw1">else</span>
<span class="br0">{</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;f_completes did not complete!<span class="es1">\n</span>&quot;</span><span class="sy4">;</span> <span class="br0">}</span>
<span class="kw1">if</span><span class="br0">(</span><a href="cpp-thread-future_status.html"><span class="kw2189">std::<span class="me2">future_status</span><span class="sy4">::</span><span class="me2">ready</span></span></a> <span class="sy1">==</span> f_times_out.<span class="me1">wait_until</span><span class="br0">(</span>two_seconds_passed<span class="br0">)</span><span class="br0">)</span>
<span class="br0">{</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;f_times_out: &quot;</span> <span class="sy1">&lt;&lt;</span> f_times_out.<span class="me1">get</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&quot;<span class="es1">\n</span>&quot;</span><span class="sy4">;</span> <span class="br0">}</span>
<span class="kw1">else</span>
<span class="br0">{</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;f_times_out did not complete!<span class="es1">\n</span>&quot;</span><span class="sy4">;</span> <span class="br0">}</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!<span class="es1">\n</span>&quot;</span><span class="sy4">;</span>
<span class="br0">}</span></pre></div>
</div>
<p>&#21487;&#33021;&#30340;&#36755;&#20986;&#65306;</p>
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<div class="text source-text">
<pre class="de1">Waiting for 2 seconds...
f_completes: 9
f_times_out did not complete!
Done!</pre></div>
</div>
</div>
<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-future-wait.html"><span class="t-lines"><span>wait</span></span></a></div>
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<td>&#31561;&#24453;&#32467;&#26524;&#21464;&#24471;&#21487;&#29992;<br />
<span class="t-mark">(&#20844;&#24320;&#25104;&#21592;&#20989;&#25968;)</span></td>
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<td>
<div class="t-dsc-member-div">
<div><a href="cpp-thread-future-wait_for.html"><span class="t-lines"><span>wait_for</span></span></a></div>
</div>
</td>
<td>&#31561;&#24453;&#32467;&#26524;&#65292;&#22914;&#26524;&#22312;&#25351;&#23450;&#30340;&#36229;&#26102;&#38388;&#38548;&#21518;&#20173;&#28982;&#26080;&#27861;&#24471;&#21040;&#32467;&#26524;&#65292;&#21017;&#36820;&#22238;&#12290;<br />
<span class="t-mark">(&#20844;&#24320;&#25104;&#21592;&#20989;&#25968;)</span></td>
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