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<html>
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<title>basic_signal_set</title>
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<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="asio.reference.basic_signal_set"></a><a class="link" href="basic_signal_set.html" title="basic_signal_set">basic_signal_set</a>
</h3></div></div></div>
<p>
Provides signal functionality.
</p>
<pre class="programlisting">template<
typename <a class="link" href="Executor1.html" title="Executor requirements">Executor</a> = any_io_executor>
class basic_signal_set
</pre>
<h5>
<a name="asio.reference.basic_signal_set.h0"></a>
<span><a name="asio.reference.basic_signal_set.types"></a></span><a class="link" href="basic_signal_set.html#asio.reference.basic_signal_set.types">Types</a>
</h5>
<div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
</colgroup>
<thead><tr>
<th>
<p>
Name
</p>
</th>
<th>
<p>
Description
</p>
</th>
</tr></thead>
<tbody>
<tr>
<td>
<p>
<a class="link" href="basic_signal_set__rebind_executor.html" title="basic_signal_set::rebind_executor"><span class="bold"><strong>rebind_executor</strong></span></a>
</p>
</td>
<td>
<p>
Rebinds the signal set type to another executor.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="basic_signal_set/executor_type.html" title="basic_signal_set::executor_type"><span class="bold"><strong>executor_type</strong></span></a>
</p>
</td>
<td>
<p>
The type of the executor associated with the object.
</p>
</td>
</tr>
</tbody>
</table></div>
<h5>
<a name="asio.reference.basic_signal_set.h1"></a>
<span><a name="asio.reference.basic_signal_set.member_functions"></a></span><a class="link" href="basic_signal_set.html#asio.reference.basic_signal_set.member_functions">Member
Functions</a>
</h5>
<div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
</colgroup>
<thead><tr>
<th>
<p>
Name
</p>
</th>
<th>
<p>
Description
</p>
</th>
</tr></thead>
<tbody>
<tr>
<td>
<p>
<a class="link" href="basic_signal_set/add.html" title="basic_signal_set::add"><span class="bold"><strong>add</strong></span></a>
</p>
</td>
<td>
<p>
Add a signal to a signal_set.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="basic_signal_set/async_wait.html" title="basic_signal_set::async_wait"><span class="bold"><strong>async_wait</strong></span></a>
</p>
</td>
<td>
<p>
Start an asynchronous operation to wait for a signal to be delivered.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="basic_signal_set/basic_signal_set.html" title="basic_signal_set::basic_signal_set"><span class="bold"><strong>basic_signal_set</strong></span></a> <span class="silver">[constructor]</span>
</p>
</td>
<td>
<p>
Construct a signal set without adding any signals. <br> <span class="silver"> —</span><br>
Construct a signal set and add one signal. <br> <span class="silver"> —</span><br> Construct
a signal set and add two signals. <br> <span class="silver"> —</span><br> Construct a signal
set and add three signals.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="basic_signal_set/cancel.html" title="basic_signal_set::cancel"><span class="bold"><strong>cancel</strong></span></a>
</p>
</td>
<td>
<p>
Cancel all operations associated with the signal set.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="basic_signal_set/clear.html" title="basic_signal_set::clear"><span class="bold"><strong>clear</strong></span></a>
</p>
</td>
<td>
<p>
Remove all signals from a signal_set.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="basic_signal_set/get_executor.html" title="basic_signal_set::get_executor"><span class="bold"><strong>get_executor</strong></span></a>
</p>
</td>
<td>
<p>
Get the executor associated with the object.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="basic_signal_set/remove.html" title="basic_signal_set::remove"><span class="bold"><strong>remove</strong></span></a>
</p>
</td>
<td>
<p>
Remove a signal from a signal_set.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="basic_signal_set/_basic_signal_set.html" title="basic_signal_set::~basic_signal_set"><span class="bold"><strong>~basic_signal_set</strong></span></a> <span class="silver">[destructor]</span>
</p>
</td>
<td>
<p>
Destroys the signal set.
</p>
</td>
</tr>
</tbody>
</table></div>
<p>
The <a class="link" href="basic_signal_set.html" title="basic_signal_set"><code class="computeroutput">basic_signal_set</code></a>
class provides the ability to perform an asynchronous wait for one or more
signals to occur.
</p>
<h5>
<a name="asio.reference.basic_signal_set.h2"></a>
<span><a name="asio.reference.basic_signal_set.thread_safety"></a></span><a class="link" href="basic_signal_set.html#asio.reference.basic_signal_set.thread_safety">Thread
Safety</a>
</h5>
<p>
<span class="emphasis"><em>Distinct</em></span> <span class="emphasis"><em>objects:</em></span> Safe.
</p>
<p>
<span class="emphasis"><em>Shared</em></span> <span class="emphasis"><em>objects:</em></span> Unsafe.
</p>
<h5>
<a name="asio.reference.basic_signal_set.h3"></a>
<span><a name="asio.reference.basic_signal_set.example"></a></span><a class="link" href="basic_signal_set.html#asio.reference.basic_signal_set.example">Example</a>
</h5>
<p>
Performing an asynchronous wait:
</p>
<pre class="programlisting">void handler(
const asio::error_code& error,
int signal_number)
{
if (!error)
{
// A signal occurred.
}
}
...
// Construct a signal set registered for process termination.
asio::signal_set signals(my_context, SIGINT, SIGTERM);
// Start an asynchronous wait for one of the signals to occur.
signals.async_wait(handler);
</pre>
<h5>
<a name="asio.reference.basic_signal_set.h4"></a>
<span><a name="asio.reference.basic_signal_set.queueing_of_signal_notifications"></a></span><a class="link" href="basic_signal_set.html#asio.reference.basic_signal_set.queueing_of_signal_notifications">Queueing
of signal notifications</a>
</h5>
<p>
If a signal is registered with a signal_set, and the signal occurs when there
are no waiting handlers, then the signal notification is queued. The next
async_wait operation on that signal_set will dequeue the notification. If
multiple notifications are queued, subsequent async_wait operations dequeue
them one at a time. Signal notifications are dequeued in order of ascending
signal number.
</p>
<p>
If a signal number is removed from a signal_set (using the <code class="computeroutput">remove</code>
or <code class="computeroutput">erase</code> member functions) then any queued notifications for
that signal are discarded.
</p>
<h5>
<a name="asio.reference.basic_signal_set.h5"></a>
<span><a name="asio.reference.basic_signal_set.multiple_registration_of_signals"></a></span><a class="link" href="basic_signal_set.html#asio.reference.basic_signal_set.multiple_registration_of_signals">Multiple
registration of signals</a>
</h5>
<p>
The same signal number may be registered with different signal_set objects.
When the signal occurs, one handler is called for each signal_set object.
</p>
<p>
Note that multiple registration only works for signals that are registered
using Asio. The application must not also register a signal handler using
functions such as <code class="computeroutput">signal()</code> or <code class="computeroutput">sigaction()</code>.
</p>
<h5>
<a name="asio.reference.basic_signal_set.h6"></a>
<span><a name="asio.reference.basic_signal_set.signal_masking_on_posix_platforms"></a></span><a class="link" href="basic_signal_set.html#asio.reference.basic_signal_set.signal_masking_on_posix_platforms">Signal
masking on POSIX platforms</a>
</h5>
<p>
POSIX allows signals to be blocked using functions such as <code class="computeroutput">sigprocmask()</code>
and <code class="computeroutput">pthread_sigmask()</code>. For signals to be delivered, programs
must ensure that any signals registered using signal_set objects are unblocked
in at least one thread.
</p>
<h5>
<a name="asio.reference.basic_signal_set.h7"></a>
<span><a name="asio.reference.basic_signal_set.requirements"></a></span><a class="link" href="basic_signal_set.html#asio.reference.basic_signal_set.requirements">Requirements</a>
</h5>
<p>
<span class="emphasis"><em>Header: </em></span><code class="literal">asio/basic_signal_set.hpp</code>
</p>
<p>
<span class="emphasis"><em>Convenience header: </em></span><code class="literal">asio.hpp</code>
</p>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
<td align="left"></td>
<td align="right"><div class="copyright-footer">Copyright © 2003-2020 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>
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