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| <div class="titlepage"><div><div><h4 class="title"> |
| <a name="boost_asio.reference.io_service.notify_fork"></a><a class="link" href="notify_fork.html" title="io_service::notify_fork">io_service::notify_fork</a> |
| </h4></div></div></div> |
| <p> |
| <a class="indexterm" name="idp142096592"></a> |
| Notify the <a class="link" href="../io_service.html" title="io_service"><code class="computeroutput"><span class="identifier">io_service</span></code></a> of a fork-related event. |
| </p> |
| <pre class="programlisting"><span class="keyword">void</span> <span class="identifier">notify_fork</span><span class="special">(</span> |
| <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">io_service</span><span class="special">::</span><span class="identifier">fork_event</span> <span class="identifier">event</span><span class="special">);</span> |
| </pre> |
| <p> |
| This function is used to inform the <a class="link" href="../io_service.html" title="io_service"><code class="computeroutput"><span class="identifier">io_service</span></code></a> that the process is |
| about to fork, or has just forked. This allows the <a class="link" href="../io_service.html" title="io_service"><code class="computeroutput"><span class="identifier">io_service</span></code></a>, and the services it |
| contains, to perform any necessary housekeeping to ensure correct operation |
| following a fork. |
| </p> |
| <p> |
| This function must not be called while any other <a class="link" href="../io_service.html" title="io_service"><code class="computeroutput"><span class="identifier">io_service</span></code></a> function, or any function |
| on an I/O object associated with the <a class="link" href="../io_service.html" title="io_service"><code class="computeroutput"><span class="identifier">io_service</span></code></a>, is being called in |
| another thread. It is, however, safe to call this function from within |
| a completion handler, provided no other thread is accessing the <a class="link" href="../io_service.html" title="io_service"><code class="computeroutput"><span class="identifier">io_service</span></code></a>. |
| </p> |
| <h6> |
| <a name="boost_asio.reference.io_service.notify_fork.h0"></a> |
| <span class="phrase"><a name="boost_asio.reference.io_service.notify_fork.parameters"></a></span><a class="link" href="notify_fork.html#boost_asio.reference.io_service.notify_fork.parameters">Parameters</a> |
| </h6> |
| <div class="variablelist"> |
| <p class="title"><b></b></p> |
| <dl class="variablelist"> |
| <dt><span class="term">event</span></dt> |
| <dd><p> |
| A fork-related event. |
| </p></dd> |
| </dl> |
| </div> |
| <h6> |
| <a name="boost_asio.reference.io_service.notify_fork.h1"></a> |
| <span class="phrase"><a name="boost_asio.reference.io_service.notify_fork.exceptions"></a></span><a class="link" href="notify_fork.html#boost_asio.reference.io_service.notify_fork.exceptions">Exceptions</a> |
| </h6> |
| <div class="variablelist"> |
| <p class="title"><b></b></p> |
| <dl class="variablelist"> |
| <dt><span class="term">boost::system::system_error</span></dt> |
| <dd><p> |
| Thrown on failure. If the notification fails the <a class="link" href="../io_service.html" title="io_service"><code class="computeroutput"><span class="identifier">io_service</span></code></a> object should |
| no longer be used and should be destroyed. |
| </p></dd> |
| </dl> |
| </div> |
| <h6> |
| <a name="boost_asio.reference.io_service.notify_fork.h2"></a> |
| <span class="phrase"><a name="boost_asio.reference.io_service.notify_fork.example"></a></span><a class="link" href="notify_fork.html#boost_asio.reference.io_service.notify_fork.example">Example</a> |
| </h6> |
| <p> |
| The following code illustrates how to incorporate the <code class="computeroutput"><span class="identifier">notify_fork</span><span class="special">()</span></code> function: |
| </p> |
| <pre class="programlisting"><span class="identifier">my_io_service</span><span class="special">.</span><span class="identifier">notify_fork</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">io_service</span><span class="special">::</span><span class="identifier">fork_prepare</span><span class="special">);</span> |
| <span class="keyword">if</span> <span class="special">(</span><span class="identifier">fork</span><span class="special">()</span> <span class="special">==</span> <span class="number">0</span><span class="special">)</span> |
| <span class="special">{</span> |
| <span class="comment">// This is the child process.</span> |
| <span class="identifier">my_io_service</span><span class="special">.</span><span class="identifier">notify_fork</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">io_service</span><span class="special">::</span><span class="identifier">fork_child</span><span class="special">);</span> |
| <span class="special">}</span> |
| <span class="keyword">else</span> |
| <span class="special">{</span> |
| <span class="comment">// This is the parent process.</span> |
| <span class="identifier">my_io_service</span><span class="special">.</span><span class="identifier">notify_fork</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">io_service</span><span class="special">::</span><span class="identifier">fork_parent</span><span class="special">);</span> |
| <span class="special">}</span> |
| </pre> |
| <h6> |
| <a name="boost_asio.reference.io_service.notify_fork.h3"></a> |
| <span class="phrase"><a name="boost_asio.reference.io_service.notify_fork.remarks"></a></span><a class="link" href="notify_fork.html#boost_asio.reference.io_service.notify_fork.remarks">Remarks</a> |
| </h6> |
| <p> |
| For each service object <code class="computeroutput"><span class="identifier">svc</span></code> |
| in the <a class="link" href="../io_service.html" title="io_service"><code class="computeroutput"><span class="identifier">io_service</span></code></a> |
| set, performs <code class="computeroutput"><span class="identifier">svc</span><span class="special">-></span><span class="identifier">fork_service</span><span class="special">();</span></code>. |
| When processing the fork_prepare event, services are visited in reverse |
| order of the beginning of service object lifetime. Otherwise, services |
| are visited in order of the beginning of service object lifetime. |
| </p> |
| </div> |
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| <td align="right"><div class="copyright-footer">Copyright © 2003-2015 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>) |
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