1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>posix::basic_stream_descriptor::async_wait</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="../posix__basic_stream_descriptor.html" title="posix::basic_stream_descriptor"> 9<link rel="prev" href="async_read_some.html" title="posix::basic_stream_descriptor::async_read_some"> 10<link rel="next" href="async_write_some.html" title="posix::basic_stream_descriptor::async_write_some"> 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="async_read_some.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../posix__basic_stream_descriptor.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="async_write_some.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.posix__basic_stream_descriptor.async_wait"></a><a class="link" href="async_wait.html" title="posix::basic_stream_descriptor::async_wait">posix::basic_stream_descriptor::async_wait</a> 28</h4></div></div></div> 29<p> 30 <span class="emphasis"><em>Inherited from posix::basic_descriptor.</em></span> 31 </p> 32<p> 33 <a class="indexterm" name="boost_asio.indexterm.posix__basic_stream_descriptor.async_wait"></a> 34Asynchronously 35 wait for the descriptor to become ready to read, ready to write, or to 36 have pending error conditions. 37 </p> 38<pre class="programlisting">template< 39 typename <a class="link" href="../WaitHandler.html" title="Wait handler requirements">WaitHandler</a> = <a class="link" href="../asynchronous_operations.html#boost_asio.reference.asynchronous_operations.default_completion_tokens"><span class="emphasis"><em>DEFAULT</em></span></a>> 40<a class="link" href="../asynchronous_operations.html#boost_asio.reference.asynchronous_operations.automatic_deduction_of_initiating_function_return_type"><span class="emphasis"><em>DEDUCED</em></span></a> async_wait( 41 wait_type w, 42 WaitHandler && handler = <a class="link" href="../asynchronous_operations.html#boost_asio.reference.asynchronous_operations.default_completion_tokens"><span class="emphasis"><em>DEFAULT</em></span></a>); 43</pre> 44<p> 45 This function is used to perform an asynchronous wait for a descriptor 46 to enter a ready to read, write or error condition state. 47 </p> 48<h6> 49<a name="boost_asio.reference.posix__basic_stream_descriptor.async_wait.h0"></a> 50 <span class="phrase"><a name="boost_asio.reference.posix__basic_stream_descriptor.async_wait.parameters"></a></span><a class="link" href="async_wait.html#boost_asio.reference.posix__basic_stream_descriptor.async_wait.parameters">Parameters</a> 51 </h6> 52<div class="variablelist"> 53<p class="title"><b></b></p> 54<dl class="variablelist"> 55<dt><span class="term">w</span></dt> 56<dd><p> 57 Specifies the desired descriptor state. 58 </p></dd> 59<dt><span class="term">handler</span></dt> 60<dd> 61<p> 62 The handler to be called when the wait operation completes. Copies 63 will be made of the handler as required. The function signature of 64 the handler must be: 65</p> 66<pre class="programlisting">void handler( 67 const boost::system::error_code& error // Result of operation 68); 69</pre> 70<p> 71 Regardless of whether the asynchronous operation completes immediately 72 or not, the handler will not be invoked from within this function. 73 On immediate completion, invocation of the handler will be performed 74 in a manner equivalent to using <a class="link" href="../post.html" title="post"><code class="computeroutput">post</code></a>. 75 </p> 76</dd> 77</dl> 78</div> 79<h6> 80<a name="boost_asio.reference.posix__basic_stream_descriptor.async_wait.h1"></a> 81 <span class="phrase"><a name="boost_asio.reference.posix__basic_stream_descriptor.async_wait.example"></a></span><a class="link" href="async_wait.html#boost_asio.reference.posix__basic_stream_descriptor.async_wait.example">Example</a> 82 </h6> 83<pre class="programlisting">void wait_handler(const boost::system::error_code& error) 84{ 85 if (!error) 86 { 87 // Wait succeeded. 88 } 89} 90 91... 92 93boost::asio::posix::stream_descriptor descriptor(my_context); 94... 95descriptor.async_wait( 96 boost::asio::posix::stream_descriptor::wait_read, 97 wait_handler); 98</pre> 99</div> 100<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 101<td align="left"></td> 102<td align="right"><div class="copyright-footer">Copyright © 2003-2020 Christopher M. 103 Kohlhoff<p> 104 Distributed under the Boost Software License, Version 1.0. (See accompanying 105 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>) 106 </p> 107</div></td> 108</tr></table> 109<hr> 110<div class="spirit-nav"> 111<a accesskey="p" href="async_read_some.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../posix__basic_stream_descriptor.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="async_write_some.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a> 112</div> 113</body> 114</html> 115
