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395 lines
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<title>basic_deadline_timer</title>
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<table cellpadding="2" width="100%"><tr><td valign="top"><img alt="asio C++ library" width="250" height="60" src="../../asio.png"></td></tr></table>
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<a accesskey="p" href="basic_datagram_socket__rebind_executor/other.html"><img src="../../prev.png" alt="Prev"></a><a accesskey="u" href="../reference.html"><img src="../../up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../home.png" alt="Home"></a><a accesskey="n" href="basic_deadline_timer/async_wait.html"><img src="../../next.png" alt="Next"></a>
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<div class="section">
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<div class="titlepage"><div><div><h3 class="title">
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<a name="asio.reference.basic_deadline_timer"></a><a class="link" href="basic_deadline_timer.html" title="basic_deadline_timer">basic_deadline_timer</a>
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</h3></div></div></div>
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<p>
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<a class="indexterm" name="asio.indexterm.basic_deadline_timer"></a>
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</p>
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<p>
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Provides waitable timer functionality.
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</p>
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<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span>
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<span class="keyword">typename</span> <span class="identifier">Time</span><span class="special">,</span>
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<span class="keyword">typename</span> <a class="link" href="TimeTraits.html" title="Time traits requirements">TimeTraits</a> <span class="special">=</span> <span class="identifier">asio</span><span class="special">::</span><span class="identifier">time_traits</span><span class="special"><</span><span class="identifier">Time</span><span class="special">>,</span>
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<span class="keyword">typename</span> <a class="link" href="Executor1.html" title="Executor requirements">Executor</a> <span class="special">=</span> <span class="identifier">any_io_executor</span><span class="special">></span>
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<span class="keyword">class</span> <span class="identifier">basic_deadline_timer</span>
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</pre>
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<h5>
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<a name="asio.reference.basic_deadline_timer.h0"></a>
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<span><a name="asio.reference.basic_deadline_timer.types"></a></span><a class="link" href="basic_deadline_timer.html#asio.reference.basic_deadline_timer.types">Types</a>
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</h5>
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<div class="informaltable"><table class="table">
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<colgroup>
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<col>
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<col>
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</colgroup>
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<thead><tr>
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<p>
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Name
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</p>
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</th>
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<th>
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<p>
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Description
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</p>
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</th>
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</tr></thead>
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<tbody>
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<tr>
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<td>
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<p>
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<a class="link" href="basic_deadline_timer__rebind_executor.html" title="basic_deadline_timer::rebind_executor"><span class="bold"><strong>rebind_executor</strong></span></a>
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</p>
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</td>
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<td>
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<p>
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Rebinds the timer type to another executor.
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</p>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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<a class="link" href="basic_deadline_timer/duration_type.html" title="basic_deadline_timer::duration_type"><span class="bold"><strong>duration_type</strong></span></a>
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</p>
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</td>
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<td>
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<p>
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The duration type.
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</p>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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<a class="link" href="basic_deadline_timer/executor_type.html" title="basic_deadline_timer::executor_type"><span class="bold"><strong>executor_type</strong></span></a>
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</p>
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</td>
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<td>
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<p>
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The type of the executor associated with the object.
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</p>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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<a class="link" href="basic_deadline_timer/time_type.html" title="basic_deadline_timer::time_type"><span class="bold"><strong>time_type</strong></span></a>
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</p>
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</td>
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<td>
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<p>
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The time type.
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</p>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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<a class="link" href="basic_deadline_timer/traits_type.html" title="basic_deadline_timer::traits_type"><span class="bold"><strong>traits_type</strong></span></a>
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</p>
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</td>
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<td>
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<p>
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The time traits type.
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</p>
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</td>
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</tr>
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</tbody>
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</table></div>
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<h5>
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<a name="asio.reference.basic_deadline_timer.h1"></a>
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<span><a name="asio.reference.basic_deadline_timer.member_functions"></a></span><a class="link" href="basic_deadline_timer.html#asio.reference.basic_deadline_timer.member_functions">Member Functions</a>
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</h5>
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<div class="informaltable"><table class="table">
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<colgroup>
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<col>
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<col>
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</colgroup>
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<thead><tr>
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<th>
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<p>
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Name
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</p>
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</th>
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<th>
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<p>
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Description
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</p>
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</th>
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</tr></thead>
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<tbody>
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<tr>
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<td>
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<p>
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<a class="link" href="basic_deadline_timer/async_wait.html" title="basic_deadline_timer::async_wait"><span class="bold"><strong>async_wait</strong></span></a>
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</p>
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</td>
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<td>
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<p>
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Start an asynchronous wait on the timer.
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</p>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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<a class="link" href="basic_deadline_timer/basic_deadline_timer.html" title="basic_deadline_timer::basic_deadline_timer"><span class="bold"><strong>basic_deadline_timer</strong></span></a> <span class="silver">[constructor]</span>
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</p>
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</td>
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<td>
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<p>
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Constructor. <br> <span class="silver"> —</span><br> Constructor to set a particular expiry
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time as an absolute time. <br> <span class="silver"> —</span><br> Constructor to set a particular
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expiry time relative to now. <br> <span class="silver"> —</span><br> Move-construct a basic_deadline_timer
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from another.
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</p>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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<a class="link" href="basic_deadline_timer/cancel.html" title="basic_deadline_timer::cancel"><span class="bold"><strong>cancel</strong></span></a>
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</p>
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</td>
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<td>
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<p>
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Cancel any asynchronous operations that are waiting on the timer.
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</p>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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<a class="link" href="basic_deadline_timer/cancel_one.html" title="basic_deadline_timer::cancel_one"><span class="bold"><strong>cancel_one</strong></span></a>
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</p>
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</td>
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<td>
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<p>
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Cancels one asynchronous operation that is waiting on the timer.
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</p>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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<a class="link" href="basic_deadline_timer/expires_at.html" title="basic_deadline_timer::expires_at"><span class="bold"><strong>expires_at</strong></span></a>
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</p>
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</td>
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<td>
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<p>
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Get the timer's expiry time as an absolute time. <br> <span class="silver"> —</span><br>
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Set the timer's expiry time as an absolute time.
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</p>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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<a class="link" href="basic_deadline_timer/expires_from_now.html" title="basic_deadline_timer::expires_from_now"><span class="bold"><strong>expires_from_now</strong></span></a>
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</p>
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</td>
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<td>
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<p>
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Get the timer's expiry time relative to now. <br> <span class="silver"> —</span><br> Set
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the timer's expiry time relative to now.
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</p>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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<a class="link" href="basic_deadline_timer/get_executor.html" title="basic_deadline_timer::get_executor"><span class="bold"><strong>get_executor</strong></span></a>
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</p>
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</td>
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<td>
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<p>
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Get the executor associated with the object.
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</p>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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<a class="link" href="basic_deadline_timer/operator_eq_.html" title="basic_deadline_timer::operator="><span class="bold"><strong>operator=</strong></span></a>
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</p>
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</td>
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<td>
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<p>
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Move-assign a basic_deadline_timer from another.
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</p>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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<a class="link" href="basic_deadline_timer/wait.html" title="basic_deadline_timer::wait"><span class="bold"><strong>wait</strong></span></a>
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</p>
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</td>
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<td>
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<p>
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Perform a blocking wait on the timer.
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</p>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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<a class="link" href="basic_deadline_timer/_basic_deadline_timer.html" title="basic_deadline_timer::~basic_deadline_timer"><span class="bold"><strong>~basic_deadline_timer</strong></span></a> <span class="silver">[destructor]</span>
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</p>
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</td>
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<td>
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<p>
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Destroys the timer.
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</p>
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</td>
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</tr>
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</tbody>
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</table></div>
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<p>
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The <a class="link" href="basic_deadline_timer.html" title="basic_deadline_timer"><code class="computeroutput"><span class="identifier">basic_deadline_timer</span></code></a>
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class template provides the ability to perform a blocking or asynchronous
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wait for a timer to expire.
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</p>
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<p>
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A deadline timer is always in one of two states: "expired" or "not
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expired". If the <code class="computeroutput"><span class="identifier">wait</span><span class="special">()</span></code> or <code class="computeroutput"><span class="identifier">async_wait</span><span class="special">()</span></code> function is called on an expired timer,
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the wait operation will complete immediately.
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</p>
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<p>
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Most applications will use the <a class="link" href="deadline_timer.html" title="deadline_timer"><code class="computeroutput"><span class="identifier">deadline_timer</span></code></a> typedef.
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</p>
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<h5>
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<a name="asio.reference.basic_deadline_timer.h2"></a>
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<span><a name="asio.reference.basic_deadline_timer.thread_safety"></a></span><a class="link" href="basic_deadline_timer.html#asio.reference.basic_deadline_timer.thread_safety">Thread
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Safety</a>
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</h5>
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<p>
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<span class="emphasis"><em>Distinct</em></span> <span class="emphasis"><em>objects:</em></span> Safe.
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</p>
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<p>
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<span class="emphasis"><em>Shared</em></span> <span class="emphasis"><em>objects:</em></span> Unsafe.
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</p>
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<h5>
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<a name="asio.reference.basic_deadline_timer.h3"></a>
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<span><a name="asio.reference.basic_deadline_timer.examples"></a></span><a class="link" href="basic_deadline_timer.html#asio.reference.basic_deadline_timer.examples">Examples</a>
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</h5>
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<p>
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Performing a blocking wait:
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</p>
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<pre class="programlisting"><span class="comment">// Construct a timer without setting an expiry time.</span>
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<span class="identifier">asio</span><span class="special">::</span><span class="identifier">deadline_timer</span> <span class="identifier">timer</span><span class="special">(</span><span class="identifier">my_context</span><span class="special">);</span>
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<span class="comment">// Set an expiry time relative to now.</span>
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<span class="identifier">timer</span><span class="special">.</span><span class="identifier">expires_from_now</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">posix_time</span><span class="special">::</span><span class="identifier">seconds</span><span class="special">(</span><span class="number">5</span><span class="special">));</span>
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<span class="comment">// Wait for the timer to expire.</span>
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<span class="identifier">timer</span><span class="special">.</span><span class="identifier">wait</span><span class="special">();</span>
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</pre>
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<p>
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Performing an asynchronous wait:
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</p>
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<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">handler</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">asio</span><span class="special">::</span><span class="identifier">error_code</span><span class="special">&</span> <span class="identifier">error</span><span class="special">)</span>
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<span class="special">{</span>
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<span class="keyword">if</span> <span class="special">(!</span><span class="identifier">error</span><span class="special">)</span>
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<span class="special">{</span>
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<span class="comment">// Timer expired.</span>
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<span class="special">}</span>
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<span class="special">}</span>
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<span class="special">...</span>
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<span class="comment">// Construct a timer with an absolute expiry time.</span>
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<span class="identifier">asio</span><span class="special">::</span><span class="identifier">deadline_timer</span> <span class="identifier">timer</span><span class="special">(</span><span class="identifier">my_context</span><span class="special">,</span>
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<span class="identifier">boost</span><span class="special">::</span><span class="identifier">posix_time</span><span class="special">::</span><span class="identifier">time_from_string</span><span class="special">(</span><span class="string">"2005-12-07 23:59:59.000"</span><span class="special">));</span>
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<span class="comment">// Start an asynchronous wait.</span>
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<span class="identifier">timer</span><span class="special">.</span><span class="identifier">async_wait</span><span class="special">(</span><span class="identifier">handler</span><span class="special">);</span>
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</pre>
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<h5>
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<a name="asio.reference.basic_deadline_timer.h4"></a>
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<span><a name="asio.reference.basic_deadline_timer.changing_an_active_deadline_timer_s_expiry_time"></a></span><a class="link" href="basic_deadline_timer.html#asio.reference.basic_deadline_timer.changing_an_active_deadline_timer_s_expiry_time">Changing
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an active deadline_timer's expiry time</a>
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</h5>
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<p>
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Changing the expiry time of a timer while there are pending asynchronous
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waits causes those wait operations to be cancelled. To ensure that the action
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associated with the timer is performed only once, use something like this:
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used:
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</p>
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<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">on_some_event</span><span class="special">()</span>
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<span class="special">{</span>
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<span class="keyword">if</span> <span class="special">(</span><span class="identifier">my_timer</span><span class="special">.</span><span class="identifier">expires_from_now</span><span class="special">(</span><span class="identifier">seconds</span><span class="special">(</span><span class="number">5</span><span class="special">))</span> <span class="special">></span> <span class="number">0</span><span class="special">)</span>
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<span class="special">{</span>
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<span class="comment">// We managed to cancel the timer. Start new asynchronous wait.</span>
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<span class="identifier">my_timer</span><span class="special">.</span><span class="identifier">async_wait</span><span class="special">(</span><span class="identifier">on_timeout</span><span class="special">);</span>
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<span class="special">}</span>
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<span class="keyword">else</span>
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||
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<span class="special">{</span>
|
||
|
<span class="comment">// Too late, timer has already expired!</span>
|
||
|
<span class="special">}</span>
|
||
|
<span class="special">}</span>
|
||
|
|
||
|
<span class="keyword">void</span> <span class="identifier">on_timeout</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">asio</span><span class="special">::</span><span class="identifier">error_code</span><span class="special">&</span> <span class="identifier">e</span><span class="special">)</span>
|
||
|
<span class="special">{</span>
|
||
|
<span class="keyword">if</span> <span class="special">(</span><span class="identifier">e</span> <span class="special">!=</span> <span class="identifier">asio</span><span class="special">::</span><span class="identifier">error</span><span class="special">::</span><span class="identifier">operation_aborted</span><span class="special">)</span>
|
||
|
<span class="special">{</span>
|
||
|
<span class="comment">// Timer was not cancelled, take necessary action.</span>
|
||
|
<span class="special">}</span>
|
||
|
<span class="special">}</span>
|
||
|
</pre>
|
||
|
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
|
||
|
<li class="listitem">
|
||
|
The <code class="computeroutput"><span class="identifier">asio</span><span class="special">::</span><span class="identifier">basic_deadline_timer</span><span class="special">::</span><span class="identifier">expires_from_now</span><span class="special">()</span></code>
|
||
|
function cancels any pending asynchronous waits, and returns the number
|
||
|
of asynchronous waits that were cancelled. If it returns 0 then you were
|
||
|
too late and the wait handler has already been executed, or will soon
|
||
|
be executed. If it returns 1 then the wait handler was successfully cancelled.
|
||
|
</li>
|
||
|
<li class="listitem">
|
||
|
If a wait handler is cancelled, the <a class="link" href="error_code.html" title="error_code"><code class="computeroutput"><span class="identifier">error_code</span></code></a> passed to it contains
|
||
|
the value <code class="computeroutput"><span class="identifier">asio</span><span class="special">::</span><span class="identifier">error</span><span class="special">::</span><span class="identifier">operation_aborted</span></code>.
|
||
|
</li>
|
||
|
</ul></div>
|
||
|
<h5>
|
||
|
<a name="asio.reference.basic_deadline_timer.h5"></a>
|
||
|
<span><a name="asio.reference.basic_deadline_timer.requirements"></a></span><a class="link" href="basic_deadline_timer.html#asio.reference.basic_deadline_timer.requirements">Requirements</a>
|
||
|
</h5>
|
||
|
<p>
|
||
|
<span class="emphasis"><em>Header: </em></span><code class="literal">asio/basic_deadline_timer.hpp</code>
|
||
|
</p>
|
||
|
<p>
|
||
|
<span class="emphasis"><em>Convenience header: </em></span><code class="literal">asio.hpp</code>
|
||
|
</p>
|
||
|
</div>
|
||
|
<div class="copyright-footer">Copyright © 2003-2023 Christopher M. Kohlhoff<p>
|
||
|
Distributed under the Boost Software License, Version 1.0. (See accompanying
|
||
|
file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
|
||
|
</p>
|
||
|
</div>
|
||
|
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|
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