asio_handler_allocate.html
4.79 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>asio_handler_allocate</title>
<link rel="stylesheet" href="../../boostbook.css" type="text/css">
<meta name="generator" content="DocBook XSL Stylesheets V1.75.2">
<link rel="home" href="../../index.html" title="Asio">
<link rel="up" href="../reference.html" title="Reference">
<link rel="prev" href="any_io_executor.html" title="any_io_executor">
<link rel="next" href="asio_handler_deallocate.html" title="asio_handler_deallocate">
</head>
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
<table cellpadding="2" width="100%"><tr><td valign="top"><img alt="asio C++ library" width="250" height="60" src="../../asio.png"></td></tr></table>
<hr>
<div class="spirit-nav">
<a accesskey="p" href="any_io_executor.html"><img src="../../prev.png" alt="Prev"></a><a accesskey="u" href="../reference.html"><img src="../../up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../home.png" alt="Home"></a><a accesskey="n" href="asio_handler_deallocate.html"><img src="../../next.png" alt="Next"></a>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="asio.reference.asio_handler_allocate"></a><a class="link" href="asio_handler_allocate.html" title="asio_handler_allocate">asio_handler_allocate</a>
</h3></div></div></div>
<p>
<a class="indexterm" name="asio.indexterm.asio_handler_allocate"></a>
(Deprecated: Use
the <a class="link" href="associated_allocator.html" title="associated_allocator"><code class="computeroutput">associated_allocator</code></a>
trait.) Default allocation function for handlers.
</p>
<pre class="programlisting">asio_handler_allocate_is_deprecated asio_handler_allocate(
std::size_t size,
... );
</pre>
<p>
Asynchronous operations may need to allocate temporary objects. Since asynchronous
operations have a handler function object, these temporary objects can be
said to be associated with the handler.
</p>
<p>
Implement asio_handler_allocate and asio_handler_deallocate for your own
handlers to provide custom allocation for these temporary objects.
</p>
<p>
The default implementation of these allocation hooks uses <code class="computeroutput">operator
new</code> and <code class="computeroutput">operator delete</code>.
</p>
<h5>
<a name="asio.reference.asio_handler_allocate.h0"></a>
<span><a name="asio.reference.asio_handler_allocate.remarks"></a></span><a class="link" href="asio_handler_allocate.html#asio.reference.asio_handler_allocate.remarks">Remarks</a>
</h5>
<p>
All temporary objects associated with a handler will be deallocated before
the upcall to the handler is performed. This allows the same memory to be
reused for a subsequent asynchronous operation initiated by the handler.
</p>
<h5>
<a name="asio.reference.asio_handler_allocate.h1"></a>
<span><a name="asio.reference.asio_handler_allocate.example"></a></span><a class="link" href="asio_handler_allocate.html#asio.reference.asio_handler_allocate.example">Example</a>
</h5>
<pre class="programlisting">class my_handler;
void* asio_handler_allocate(std::size_t size, my_handler* context)
{
return ::operator new(size);
}
void asio_handler_deallocate(void* pointer, std::size_t size,
my_handler* context)
{
::operator delete(pointer);
}
</pre>
<h5>
<a name="asio.reference.asio_handler_allocate.h2"></a>
<span><a name="asio.reference.asio_handler_allocate.requirements"></a></span><a class="link" href="asio_handler_allocate.html#asio.reference.asio_handler_allocate.requirements">Requirements</a>
</h5>
<p>
<span class="emphasis"><em>Header: </em></span><code class="literal">asio/handler_alloc_hook.hpp</code>
</p>
<p>
<span class="emphasis"><em>Convenience header: </em></span><code class="literal">asio.hpp</code>
</p>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
<td align="left"></td>
<td align="right"><div class="copyright-footer">Copyright © 2003-2020 Christopher M.
Kohlhoff<p>
Distributed under the Boost Software License, Version 1.0. (See accompanying
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>)
</p>
</div></td>
</tr></table>
<hr>
<div class="spirit-nav">
<a accesskey="p" href="any_io_executor.html"><img src="../../prev.png" alt="Prev"></a><a accesskey="u" href="../reference.html"><img src="../../up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../home.png" alt="Home"></a><a accesskey="n" href="asio_handler_deallocate.html"><img src="../../next.png" alt="Next"></a>
</div>
</body>
</html>