1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>execution_context::notify_fork</title> 5<link rel="stylesheet" href="../../../../../doc/src/boostbook.css" type="text/css"> 6<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 7<link rel="home" href="../../../boost_asio.html" title="Boost.Asio"> 8<link rel="up" href="../execution_context.html" title="execution_context"> 9<link rel="prev" href="make_service.html" title="execution_context::make_service"> 10<link rel="next" href="shutdown.html" title="execution_context::shutdown"> 11</head> 12<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 13<table cellpadding="2" width="100%"><tr> 14<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../boost.png"></td> 15<td align="center"><a href="../../../../../index.html">Home</a></td> 16<td align="center"><a href="../../../../../libs/libraries.htm">Libraries</a></td> 17<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> 18<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> 19<td align="center"><a href="../../../../../more/index.htm">More</a></td> 20</tr></table> 21<hr> 22<div class="spirit-nav"> 23<a accesskey="p" href="make_service.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../execution_context.html"><img src="../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../boost_asio.html"><img src="../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="shutdown.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h4 class="title"> 27<a name="boost_asio.reference.execution_context.notify_fork"></a><a class="link" href="notify_fork.html" title="execution_context::notify_fork">execution_context::notify_fork</a> 28</h4></div></div></div> 29<p> 30 <a class="indexterm" name="boost_asio.indexterm.execution_context.notify_fork"></a> 31Notify 32 the <a class="link" href="../execution_context.html" title="execution_context"><code class="computeroutput">execution_context</code></a> 33 of a fork-related event. 34 </p> 35<pre class="programlisting">void notify_fork( 36 fork_event event); 37</pre> 38<p> 39 This function is used to inform the <a class="link" href="../execution_context.html" title="execution_context"><code class="computeroutput">execution_context</code></a> 40 that the process is about to fork, or has just forked. This allows the 41 <a class="link" href="../execution_context.html" title="execution_context"><code class="computeroutput">execution_context</code></a>, 42 and the services it contains, to perform any necessary housekeeping to 43 ensure correct operation following a fork. 44 </p> 45<p> 46 This function must not be called while any other <a class="link" href="../execution_context.html" title="execution_context"><code class="computeroutput">execution_context</code></a> 47 function, or any function associated with the execution_context's derived 48 class, is being called in another thread. It is, however, safe to call 49 this function from within a completion handler, provided no other thread 50 is accessing the <a class="link" href="../execution_context.html" title="execution_context"><code class="computeroutput">execution_context</code></a> 51 or its derived class. 52 </p> 53<h6> 54<a name="boost_asio.reference.execution_context.notify_fork.h0"></a> 55 <span class="phrase"><a name="boost_asio.reference.execution_context.notify_fork.parameters"></a></span><a class="link" href="notify_fork.html#boost_asio.reference.execution_context.notify_fork.parameters">Parameters</a> 56 </h6> 57<div class="variablelist"> 58<p class="title"><b></b></p> 59<dl class="variablelist"> 60<dt><span class="term">event</span></dt> 61<dd><p> 62 A fork-related event. 63 </p></dd> 64</dl> 65</div> 66<h6> 67<a name="boost_asio.reference.execution_context.notify_fork.h1"></a> 68 <span class="phrase"><a name="boost_asio.reference.execution_context.notify_fork.exceptions"></a></span><a class="link" href="notify_fork.html#boost_asio.reference.execution_context.notify_fork.exceptions">Exceptions</a> 69 </h6> 70<div class="variablelist"> 71<p class="title"><b></b></p> 72<dl class="variablelist"> 73<dt><span class="term">boost::system::system_error</span></dt> 74<dd><p> 75 Thrown on failure. If the notification fails the <a class="link" href="../execution_context.html" title="execution_context"><code class="computeroutput">execution_context</code></a> 76 object should no longer be used and should be destroyed. 77 </p></dd> 78</dl> 79</div> 80<h6> 81<a name="boost_asio.reference.execution_context.notify_fork.h2"></a> 82 <span class="phrase"><a name="boost_asio.reference.execution_context.notify_fork.example"></a></span><a class="link" href="notify_fork.html#boost_asio.reference.execution_context.notify_fork.example">Example</a> 83 </h6> 84<p> 85 The following code illustrates how to incorporate the <code class="computeroutput">notify_fork()</code> 86 function: 87 </p> 88<pre class="programlisting">my_execution_context.notify_fork(execution_context::fork_prepare); 89if (fork() == 0) 90{ 91 // This is the child process. 92 my_execution_context.notify_fork(execution_context::fork_child); 93} 94else 95{ 96 // This is the parent process. 97 my_execution_context.notify_fork(execution_context::fork_parent); 98} 99</pre> 100<h6> 101<a name="boost_asio.reference.execution_context.notify_fork.h3"></a> 102 <span class="phrase"><a name="boost_asio.reference.execution_context.notify_fork.remarks"></a></span><a class="link" href="notify_fork.html#boost_asio.reference.execution_context.notify_fork.remarks">Remarks</a> 103 </h6> 104<p> 105 For each service object <code class="computeroutput">svc</code> in the <a class="link" href="../execution_context.html" title="execution_context"><code class="computeroutput">execution_context</code></a> 106 set, performs <code class="computeroutput">svc->notify_fork();</code>. When processing the 107 fork_prepare event, services are visited in reverse order of the beginning 108 of service object lifetime. Otherwise, services are visited in order of 109 the beginning of service object lifetime. 110 </p> 111</div> 112<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 113<td align="left"></td> 114<td align="right"><div class="copyright-footer">Copyright © 2003-2020 Christopher M. 115 Kohlhoff<p> 116 Distributed under the Boost Software License, Version 1.0. (See accompanying 117 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>) 118 </p> 119</div></td> 120</tr></table> 121<hr> 122<div class="spirit-nav"> 123<a accesskey="p" href="make_service.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../execution_context.html"><img src="../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../boost_asio.html"><img src="../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="shutdown.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a> 124</div> 125</body> 126</html> 127
