1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>buffered_read_stream::async_read_some</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="../../../index.html" title="Chapter 1. Boost.Beast"> 8<link rel="up" href="../boost__beast__buffered_read_stream.html" title="buffered_read_stream"> 9<link rel="prev" href="read_some/overload2.html" title="buffered_read_stream::read_some (2 of 2 overloads)"> 10<link rel="next" href="write_some.html" title="buffered_read_stream::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="read_some/overload2.html"><img src="../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../boost__beast__buffered_read_stream.html"><img src="../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../index.html"><img src="../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="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><h5 class="title"> 27<a name="beast.ref.boost__beast__buffered_read_stream.async_read_some"></a><a class="link" href="async_read_some.html" title="buffered_read_stream::async_read_some">buffered_read_stream::async_read_some</a> 28</h5></div></div></div> 29<p> 30 <a class="indexterm" name="idm46057543449008"></a> 31 </p> 32<p> 33 Start an asynchronous read. 34 </p> 35<h6> 36<a name="beast.ref.boost__beast__buffered_read_stream.async_read_some.h0"></a> 37 <span class="phrase"><a name="beast.ref.boost__beast__buffered_read_stream.async_read_some.synopsis"></a></span><a class="link" href="async_read_some.html#beast.ref.boost__beast__buffered_read_stream.async_read_some.synopsis">Synopsis</a> 38 </h6> 39<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span> 40 <span class="keyword">class</span> <a href="../../../../../../../doc/html/boost_asio/reference/MutableBufferSequence.html" target="_top"><span class="emphasis"><em>MutableBufferSequence</em></span></a><span class="special">,</span> 41 <span class="keyword">class</span> <a href="../../../../../../../doc/html/boost_asio/reference/ReadHandler.html" target="_top"><span class="emphasis"><em>ReadHandler</em></span></a> <span class="special">=</span> <span class="identifier">net</span><span class="special">::</span><span class="identifier">default_completion_token_t</span><span class="special"><</span><a class="link" href="executor_type.html" title="buffered_read_stream::executor_type">executor_type</a><span class="special">>></span> 42<a href="../../../../../../../doc/html/boost_asio/reference/asynchronous_operations.html#boost_asio.reference.asynchronous_operations.automatic_deduction_of_initiating_function_return_type" target="_top"><span class="emphasis"><em>DEDUCED</em></span></a> 43<span class="identifier">async_read_some</span><span class="special">(</span> 44 <span class="identifier">MutableBufferSequence</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">buffers</span><span class="special">,</span> 45 <span class="identifier">ReadHandler</span><span class="special">&&</span> <span class="identifier">handler</span> <span class="special">=</span> <span class="identifier">net</span><span class="special">::</span><span class="identifier">default_completion_token_t</span><span class="special"><</span> <a class="link" href="executor_type.html" title="buffered_read_stream::executor_type">executor_type</a> <span class="special">>{});</span> 46</pre> 47<h6> 48<a name="beast.ref.boost__beast__buffered_read_stream.async_read_some.h1"></a> 49 <span class="phrase"><a name="beast.ref.boost__beast__buffered_read_stream.async_read_some.description"></a></span><a class="link" href="async_read_some.html#beast.ref.boost__beast__buffered_read_stream.async_read_some.description">Description</a> 50 </h6> 51<p> 52 This function is used to asynchronously read data from the stream. The 53 function call always returns immediately. 54 </p> 55<h6> 56<a name="beast.ref.boost__beast__buffered_read_stream.async_read_some.h2"></a> 57 <span class="phrase"><a name="beast.ref.boost__beast__buffered_read_stream.async_read_some.parameters"></a></span><a class="link" href="async_read_some.html#beast.ref.boost__beast__buffered_read_stream.async_read_some.parameters">Parameters</a> 58 </h6> 59<div class="informaltable"><table class="table"> 60<colgroup> 61<col> 62<col> 63</colgroup> 64<thead><tr> 65<th> 66 <p> 67 Name 68 </p> 69 </th> 70<th> 71 <p> 72 Description 73 </p> 74 </th> 75</tr></thead> 76<tbody> 77<tr> 78<td> 79 <p> 80 <code class="computeroutput"><span class="identifier">buffers</span></code> 81 </p> 82 </td> 83<td> 84 <p> 85 One or more buffers into which the data will be read. Although 86 the buffers object may be copied as necessary, ownership of the 87 underlying memory blocks is retained by the caller, which must 88 guarantee that they remain valid until the handler is called. 89 </p> 90 </td> 91</tr> 92<tr> 93<td> 94 <p> 95 <code class="computeroutput"><span class="identifier">handler</span></code> 96 </p> 97 </td> 98<td> 99 <p> 100 The completion handler to invoke when the operation completes. 101 The implementation takes ownership of the handler by performing 102 a decay-copy. The equivalent function signature of the handler 103 must be: 104 </p> 105<pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="keyword">void</span> <span class="identifier">handler</span><span class="special">(</span> 106 <span class="identifier">error_code</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">error</span><span class="special">,</span> <span class="comment">// result of operation</span> 107 <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">bytes_transferred</span> <span class="comment">// number of bytes transferred</span> 108<span class="special">);</span> 109</pre> 110 </td> 111</tr> 112</tbody> 113</table></div> 114<p> 115 Regardless of whether the asynchronous operation completes immediately 116 or not, the handler will not be invoked from within this function. Invocation 117 of the handler will be performed in a manner equivalent to using <code class="computeroutput"><span class="identifier">net</span><span class="special">::</span><span class="identifier">post</span></code>. 118 </p> 119</div> 120<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 121<td align="left"></td> 122<td align="right"><div class="copyright-footer">Copyright © 2016-2019 Vinnie 123 Falco<p> 124 Distributed under the Boost Software License, Version 1.0. (See accompanying 125 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>) 126 </p> 127</div></td> 128</tr></table> 129<hr> 130<div class="spirit-nav"> 131<a accesskey="p" href="read_some/overload2.html"><img src="../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../boost__beast__buffered_read_stream.html"><img src="../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../index.html"><img src="../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="write_some.html"><img src="../../../../../../../doc/src/images/next.png" alt="Next"></a> 132</div> 133</body> 134</html> 135
