1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>Buffer-oriented asynchronous random-access write device requirements</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="../reference.html" title="Reference"> 9<link rel="prev" href="AsyncRandomAccessReadDevice.html" title="Buffer-oriented asynchronous random-access read device requirements"> 10<link rel="next" href="AsyncReadStream.html" title="Buffer-oriented asynchronous read stream requirements"> 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="AsyncRandomAccessReadDevice.html"><img src="../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../reference.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="AsyncReadStream.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h3 class="title"> 27<a name="boost_asio.reference.AsyncRandomAccessWriteDevice"></a><a class="link" href="AsyncRandomAccessWriteDevice.html" title="Buffer-oriented asynchronous random-access write device requirements">Buffer-oriented 28 asynchronous random-access write device requirements</a> 29</h3></div></div></div> 30<p> 31 In the table below, <code class="computeroutput">a</code> denotes an asynchronous write stream object, 32 <code class="computeroutput">o</code> denotes an offset of type <code class="computeroutput">boost::uint64_t</code>, <code class="computeroutput">cb</code> 33 denotes an object satisfying <a class="link" href="ConstBufferSequence.html" title="Constant buffer sequence requirements">constant 34 buffer sequence</a> requirements, and <code class="computeroutput">h</code> denotes an object 35 satisfying <a class="link" href="WriteHandler.html" title="Write handler requirements">write handler</a> 36 requirements. 37 </p> 38<div class="table"> 39<a name="boost_asio.reference.AsyncRandomAccessWriteDevice.t0"></a><p class="title"><b>Table 3. Buffer-oriented asynchronous random-access write device requirements</b></p> 40<div class="table-contents"><table class="table" summary="Buffer-oriented asynchronous random-access write device requirements"> 41<colgroup> 42<col> 43<col> 44<col> 45</colgroup> 46<thead><tr> 47<th> 48 <p> 49 operation 50 </p> 51 </th> 52<th> 53 <p> 54 type 55 </p> 56 </th> 57<th> 58 <p> 59 semantics, pre/post-conditions 60 </p> 61 </th> 62</tr></thead> 63<tbody> 64<tr> 65<td> 66 <p> 67 <code class="computeroutput">a.get_executor()</code> 68 </p> 69 </td> 70<td> 71 <p> 72 A type satisfying the <a class="link" href="Executor1.html" title="Executor requirements">Executor 73 requirements</a>. 74 </p> 75 </td> 76<td> 77 <p> 78 Returns the associated I/O executor. 79 </p> 80 </td> 81</tr> 82<tr> 83<td> 84 <p> 85 <code class="computeroutput">a.async_write_some_at(o, cb, h);</code> 86 </p> 87 </td> 88<td> 89 <p> 90 <code class="computeroutput">void</code> 91 </p> 92 </td> 93<td> 94 <p> 95 Initiates an asynchronous operation to write one or more bytes 96 of data to the device <code class="computeroutput">a</code> at offset <code class="computeroutput">o</code>. 97 The operation is performed via the <code class="computeroutput">io_service</code> object 98 <code class="computeroutput">a.get_io_service()</code> and behaves according to <a class="link" href="asynchronous_operations.html" title="Requirements on asynchronous operations">asynchronous 99 operation</a> requirements.<br> <br> The constant buffer 100 sequence <code class="computeroutput">cb</code> specifies memory where the data to be 101 written is located. The <code class="computeroutput">async_write_some_at</code> operation 102 shall always write a buffer in the sequence completely before proceeding 103 to the next.<br> <br> The implementation shall maintain one 104 or more copies of <code class="computeroutput">cb</code> until such time as the write 105 operation no longer requires access to the memory specified by 106 the buffers in the sequence. The program must ensure the memory 107 is valid until:<br> <br> — the last copy of <code class="computeroutput">cb</code> is 108 destroyed, or<br> <br> — the handler for the asynchronous write 109 operation is invoked,<br> <br> whichever comes first.<br> 110 <br> If the total size of all buffers in the sequence <code class="computeroutput">cb</code> 111 is <code class="computeroutput">0</code>, the asynchronous write operation shall complete 112 immediately and pass <code class="computeroutput">0</code> as the argument to the handler 113 that specifies the number of bytes written. 114 </p> 115 </td> 116</tr> 117</tbody> 118</table></div> 119</div> 120<br class="table-break"> 121</div> 122<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 123<td align="left"></td> 124<td align="right"><div class="copyright-footer">Copyright © 2003-2020 Christopher M. 125 Kohlhoff<p> 126 Distributed under the Boost Software License, Version 1.0. (See accompanying 127 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>) 128 </p> 129</div></td> 130</tr></table> 131<hr> 132<div class="spirit-nav"> 133<a accesskey="p" href="AsyncRandomAccessReadDevice.html"><img src="../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../reference.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="AsyncReadStream.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a> 134</div> 135</body> 136</html> 137
