1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>asio_handler_allocate</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="any_io_executor.html" title="any_io_executor"> 10<link rel="next" href="asio_handler_deallocate.html" title="asio_handler_deallocate"> 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="any_io_executor.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="asio_handler_deallocate.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.asio_handler_allocate"></a><a class="link" href="asio_handler_allocate.html" title="asio_handler_allocate">asio_handler_allocate</a> 28</h3></div></div></div> 29<p> 30 <a class="indexterm" name="boost_asio.indexterm.asio_handler_allocate"></a> 31(Deprecated: 32 Use the <a class="link" href="associated_allocator.html" title="associated_allocator"><code class="computeroutput">associated_allocator</code></a> 33 trait.) Default allocation function for handlers. 34 </p> 35<pre class="programlisting">asio_handler_allocate_is_deprecated asio_handler_allocate( 36 std::size_t size, 37 ... ); 38</pre> 39<p> 40 Asynchronous operations may need to allocate temporary objects. Since asynchronous 41 operations have a handler function object, these temporary objects can be 42 said to be associated with the handler. 43 </p> 44<p> 45 Implement asio_handler_allocate and asio_handler_deallocate for your own 46 handlers to provide custom allocation for these temporary objects. 47 </p> 48<p> 49 The default implementation of these allocation hooks uses <code class="computeroutput">operator 50 new</code> and <code class="computeroutput">operator delete</code>. 51 </p> 52<h5> 53<a name="boost_asio.reference.asio_handler_allocate.h0"></a> 54 <span class="phrase"><a name="boost_asio.reference.asio_handler_allocate.remarks"></a></span><a class="link" href="asio_handler_allocate.html#boost_asio.reference.asio_handler_allocate.remarks">Remarks</a> 55 </h5> 56<p> 57 All temporary objects associated with a handler will be deallocated before 58 the upcall to the handler is performed. This allows the same memory to be 59 reused for a subsequent asynchronous operation initiated by the handler. 60 </p> 61<h5> 62<a name="boost_asio.reference.asio_handler_allocate.h1"></a> 63 <span class="phrase"><a name="boost_asio.reference.asio_handler_allocate.example"></a></span><a class="link" href="asio_handler_allocate.html#boost_asio.reference.asio_handler_allocate.example">Example</a> 64 </h5> 65<pre class="programlisting">class my_handler; 66 67void* asio_handler_allocate(std::size_t size, my_handler* context) 68{ 69 return ::operator new(size); 70} 71 72void asio_handler_deallocate(void* pointer, std::size_t size, 73 my_handler* context) 74{ 75 ::operator delete(pointer); 76} 77</pre> 78<h5> 79<a name="boost_asio.reference.asio_handler_allocate.h2"></a> 80 <span class="phrase"><a name="boost_asio.reference.asio_handler_allocate.requirements"></a></span><a class="link" href="asio_handler_allocate.html#boost_asio.reference.asio_handler_allocate.requirements">Requirements</a> 81 </h5> 82<p> 83 <span class="emphasis"><em>Header: </em></span><code class="literal">boost/asio/handler_alloc_hook.hpp</code> 84 </p> 85<p> 86 <span class="emphasis"><em>Convenience header: </em></span><code class="literal">boost/asio.hpp</code> 87 </p> 88</div> 89<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 90<td align="left"></td> 91<td align="right"><div class="copyright-footer">Copyright © 2003-2020 Christopher M. 92 Kohlhoff<p> 93 Distributed under the Boost Software License, Version 1.0. (See accompanying 94 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>) 95 </p> 96</div></td> 97</tr></table> 98<hr> 99<div class="spirit-nav"> 100<a accesskey="p" href="any_io_executor.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="asio_handler_deallocate.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a> 101</div> 102</body> 103</html> 104
