1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>flat_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__flat_stream.html" title="flat_stream"> 9<link rel="prev" href="read_some/overload2.html" title="flat_stream::read_some (2 of 2 overloads)"> 10<link rel="next" href="write_some.html" title="flat_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__flat_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__flat_stream.async_read_some"></a><a class="link" href="async_read_some.html" title="flat_stream::async_read_some">flat_stream::async_read_some</a> 28</h5></div></div></div> 29<p> 30 <a class="indexterm" name="idm46057536196816"></a> 31 </p> 32<p> 33 Start an asynchronous read. 34 </p> 35<h6> 36<a name="beast.ref.boost__beast__flat_stream.async_read_some.h0"></a> 37 <span class="phrase"><a name="beast.ref.boost__beast__flat_stream.async_read_some.synopsis"></a></span><a class="link" href="async_read_some.html#beast.ref.boost__beast__flat_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="flat_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="flat_stream::executor_type">executor_type</a> <span class="special">>{});</span> 46</pre> 47<h6> 48<a name="beast.ref.boost__beast__flat_stream.async_read_some.h1"></a> 49 <span class="phrase"><a name="beast.ref.boost__beast__flat_stream.async_read_some.description"></a></span><a class="link" href="async_read_some.html#beast.ref.boost__beast__flat_stream.async_read_some.description">Description</a> 50 </h6> 51<p> 52 This function is used to asynchronously read one or more bytes of data 53 from the stream. The function call always returns immediately. 54 </p> 55<h6> 56<a name="beast.ref.boost__beast__flat_stream.async_read_some.h2"></a> 57 <span class="phrase"><a name="beast.ref.boost__beast__flat_stream.async_read_some.parameters"></a></span><a class="link" href="async_read_some.html#beast.ref.boost__beast__flat_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 The buffers into which the data will be read. Although the buffers 86 object may be copied as necessary, ownership of the underlying 87 buffers is retained by the caller, which must guarantee that 88 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 read.</span> 108<span class="special">);</span> 109</pre> 110 <p> 111 Regardless of whether the asynchronous operation completes immediately 112 or not, the handler will not be invoked from within this function. 113 Invocation of the handler will be performed in a manner equivalent 114 to using <code class="computeroutput"><span class="identifier">net</span><span class="special">::</span><span class="identifier">post</span></code>. 115 </p> 116 </td> 117</tr> 118</tbody> 119</table></div> 120<h6> 121<a name="beast.ref.boost__beast__flat_stream.async_read_some.h3"></a> 122 <span class="phrase"><a name="beast.ref.boost__beast__flat_stream.async_read_some.remarks"></a></span><a class="link" href="async_read_some.html#beast.ref.boost__beast__flat_stream.async_read_some.remarks">Remarks</a> 123 </h6> 124<p> 125 The <code class="computeroutput"><span class="identifier">read_some</span></code> operation 126 may not read all of the requested number of bytes. Consider using the function 127 <code class="computeroutput"><span class="identifier">net</span><span class="special">::</span><span class="identifier">async_read</span></code> if you need to ensure that 128 the requested amount of data is read before the asynchronous operation 129 completes. 130 </p> 131</div> 132<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 133<td align="left"></td> 134<td align="right"><div class="copyright-footer">Copyright © 2016-2019 Vinnie 135 Falco<p> 136 Distributed under the Boost Software License, Version 1.0. (See accompanying 137 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>) 138 </p> 139</div></td> 140</tr></table> 141<hr> 142<div class="spirit-nav"> 143<a accesskey="p" href="read_some/overload2.html"><img src="../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../boost__beast__flat_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> 144</div> 145</body> 146</html> 147
