83 lines
5.7 KiB
HTML
83 lines
5.7 KiB
HTML
<html>
|
|
<head>
|
|
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
|
|
<title>Customising Immediate Completion</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="../composition.html" title="Composition and Completion Tokens">
|
|
<link rel="prev" href="type_erasure.html" title="Type Erasure, Separate Compilation and Virtual Functions">
|
|
<link rel="next" href="../networking.html" title="Networking">
|
|
<meta name="viewport" content="width=device-width, initial-scale=1">
|
|
</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="type_erasure.html"><img src="../../../prev.png" alt="Prev"></a><a accesskey="u" href="../composition.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="../networking.html"><img src="../../../next.png" alt="Next"></a>
|
|
</div>
|
|
<div class="section">
|
|
<div class="titlepage"><div><div><h4 class="title">
|
|
<a name="asio.overview.composition.immediate_completion"></a><a class="link" href="immediate_completion.html" title="Customising Immediate Completion">Customising
|
|
Immediate Completion</a>
|
|
</h4></div></div></div>
|
|
<p>
|
|
The <code class="computeroutput"><span class="identifier">associated_immediate_executor</span></code>
|
|
associator trait, along with the <code class="computeroutput"><span class="identifier">bind_immediate_executor</span></code>
|
|
function, provide the ability to customise the execution of a completion
|
|
handler when an asynchronous operation completes immediately.
|
|
</p>
|
|
<p>
|
|
When a supported operation completes immediately (that is, within the initiating
|
|
function) the associated immmediate executor is obtained, and the completion
|
|
handler is delivered through that executor as if by using <code class="computeroutput"><span class="identifier">asio</span><span class="special">::</span><span class="identifier">dispatch</span></code> on that executor. By default,
|
|
the immediate executor delivers the completion handler as if using <code class="computeroutput"><span class="identifier">asio</span><span class="special">::</span><span class="identifier">post</span></code> via the operation's I/O executor.
|
|
</p>
|
|
<p>
|
|
For example, to allow a recursive call to the completion handler of an
|
|
<code class="computeroutput"><span class="identifier">async_read_some</span></code> operation,
|
|
we may specify that immediate completion is delivered via a <code class="computeroutput"><span class="identifier">system_executor</span></code>:
|
|
</p>
|
|
<pre class="programlisting"><span class="identifier">my_socket</span><span class="special">.</span><span class="identifier">async_read_some</span><span class="special">(</span><span class="identifier">my_buffer</span><span class="special">,</span>
|
|
<span class="identifier">bind_immediate_executor</span><span class="special">(</span>
|
|
<span class="identifier">system_executor</span><span class="special">(),</span>
|
|
<span class="special">[](</span><span class="identifier">error_code</span> <span class="identifier">e</span><span class="special">,</span> <span class="identifier">size_t</span> <span class="identifier">n</span><span class="special">)</span>
|
|
<span class="special">{</span>
|
|
<span class="comment">// ...</span>
|
|
<span class="special">}</span>
|
|
<span class="special">)</span>
|
|
<span class="special">);</span>
|
|
</pre>
|
|
<p>
|
|
Immediate execution is currently supported for asynchronous operations
|
|
on reactor-based sockets and descriptors, and for asynchronous operations
|
|
on channels.
|
|
</p>
|
|
<p>
|
|
<span class="bold"><strong>Note:</strong></span> When enabling the immediate execution
|
|
of completion handlers, care must be taken to ensure that unbounded recursion
|
|
and stack overflow do not occur. Furthermore, use of immediate completion
|
|
may impact the fairness of completion handler scheduling, with a potential
|
|
for starvation for other pending work.
|
|
</p>
|
|
<h6>
|
|
<a name="asio.overview.composition.immediate_completion.h0"></a>
|
|
<span><a name="asio.overview.composition.immediate_completion.see_also"></a></span><a class="link" href="immediate_completion.html#asio.overview.composition.immediate_completion.see_also">See Also</a>
|
|
</h6>
|
|
<p>
|
|
<a class="link" href="../../reference/associated_immediate_executor.html" title="associated_immediate_executor">associated_immediate_executor</a>,
|
|
<a class="link" href="../../reference/bind_immediate_executor.html" title="bind_immediate_executor">bind_immediate_executor</a>.
|
|
</p>
|
|
</div>
|
|
<div class="copyright-footer">Copyright © 2003-2023 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>
|
|
<hr>
|
|
<div class="spirit-nav">
|
|
<a accesskey="p" href="type_erasure.html"><img src="../../../prev.png" alt="Prev"></a><a accesskey="u" href="../composition.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="../networking.html"><img src="../../../next.png" alt="Next"></a>
|
|
</div>
|
|
</body>
|
|
</html>
|