tri11paragon
/
Insane_DNS
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
Insane_DNS/libraries/asio-1.28.1/doc/asio/reference/Scheduler.html

198 lines
16 KiB
HTML
Raw Permalink Blame History

This file contains invisible Unicode characters!

This file contains invisible Unicode characters that may be processed differently from what appears below. If your use case is intentional and legitimate, you can safely ignore this warning. Use the Escape button to reveal hidden characters.

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Scheduler concept</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="ResolveToken.html" title="Resolve token requirements">
<link rel="next" href="Sender.html" title="Sender concepts">
<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="ResolveToken.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="Sender.html"><img src="../../next.png" alt="Next"></a>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="asio.reference.Scheduler"></a><a class="link" href="Scheduler.html" title="Scheduler concept">Scheduler concept</a>
</h3></div></div></div>
<pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">S</span><span class="special">&gt;</span>
<span class="identifier">concept</span> <span class="identifier">scheduler</span> <span class="special">=</span>
<span class="identifier">copy_constructible</span><span class="special">&lt;</span><span class="identifier">remove_cvref_t</span><span class="special">&lt;</span><span class="identifier">S</span><span class="special">&gt;&gt;</span> <span class="special">&amp;&amp;</span>
<span class="identifier">equality_comparable</span><span class="special">&lt;</span><span class="identifier">remove_cvref_t</span><span class="special">&lt;</span><span class="identifier">S</span><span class="special">&gt;&gt;</span> <span class="special">&amp;&amp;</span>
<span class="identifier">requires</span><span class="special">(</span><span class="identifier">E</span><span class="special">&amp;&amp;</span> <span class="identifier">e</span><span class="special">)</span> <span class="special">{</span>
<span class="identifier">execution</span><span class="special">::</span><span class="identifier">schedule</span><span class="special">((</span><span class="identifier">E</span><span class="special">&amp;&amp;)</span><span class="identifier">e</span><span class="special">);</span>
<span class="special">};</span>
</pre>
<p>
None of a scheduler's copy constructor, destructor, equality comparison,
or <code class="computeroutput"><span class="identifier">swap</span></code> operation shall exit
via an exception.
</p>
<p>
None of these operations, nor a scheduler type's <code class="computeroutput"><span class="identifier">schedule</span></code>
function, or associated query functions shall introduce data races as a result
of concurrent invocations of those functions from different threads.
</p>
<p>
For any two (possibly const) values <code class="computeroutput"><span class="identifier">x1</span></code>
and <code class="computeroutput"><span class="identifier">x2</span></code> of some scheduler
type <code class="computeroutput"><span class="identifier">X</span></code>, <code class="computeroutput"><span class="identifier">x1</span>
<span class="special">==</span> <span class="identifier">x2</span></code>
shall return <code class="computeroutput"><span class="keyword">true</span></code> only if <code class="computeroutput"><span class="identifier">asio</span><span class="special">::</span><span class="identifier">query</span><span class="special">(</span><span class="identifier">x1</span><span class="special">,</span> <span class="identifier">p</span><span class="special">)</span> <span class="special">==</span> <span class="identifier">asio</span><span class="special">::</span><span class="identifier">query</span><span class="special">(</span><span class="identifier">x2</span><span class="special">,</span>
<span class="identifier">p</span><span class="special">)</span></code>
for every property <code class="computeroutput"><span class="identifier">p</span></code> where
both <code class="computeroutput"><span class="identifier">asio</span><span class="special">::</span><span class="identifier">query</span><span class="special">(</span><span class="identifier">x1</span><span class="special">,</span> <span class="identifier">p</span><span class="special">)</span></code> and <code class="computeroutput"><span class="identifier">asio</span><span class="special">::</span><span class="identifier">query</span><span class="special">(</span><span class="identifier">x2</span><span class="special">,</span>
<span class="identifier">p</span><span class="special">)</span></code>
are well-formed and result in a non-void type that is <code class="computeroutput"><span class="identifier">EqualityComparable</span></code>
(C++Std [equalitycomparable]). [<span class="emphasis"><em>Note:</em></span> The above requirements
imply that <code class="computeroutput"><span class="identifier">x1</span> <span class="special">==</span>
<span class="identifier">x2</span></code> returns <code class="computeroutput"><span class="keyword">true</span></code>
if <code class="computeroutput"><span class="identifier">x1</span></code> and <code class="computeroutput"><span class="identifier">x2</span></code>
can be interchanged with identical effects. A scheduler may conceptually
contain additional properties which are not exposed by a named property type
that can be observed via <code class="computeroutput"><span class="identifier">asio</span><span class="special">::</span><span class="identifier">query</span></code>;
in this case, it is up to the concrete scheduler implementation to decide
if these properties affect equality. Returning <code class="computeroutput"><span class="keyword">false</span></code>
does not necessarily imply that the effects are not identical. —<span class="emphasis"><em>end
note</em></span>]
</p>
<p>
A scheduler type's destructor shall not block pending completion of any receivers
submitted to the sender objects returned from <code class="computeroutput"><span class="identifier">schedule</span></code>.
[<span class="emphasis"><em>Note:</em></span> The ability to wait for completion of submitted
function objects may be provided by the execution context that produced the
scheduler. —<span class="emphasis"><em>end note</em></span>]
</p>
<p>
In addition to the above requirements, type <code class="computeroutput"><span class="identifier">S</span></code>
models <code class="computeroutput"><span class="identifier">scheduler</span></code> only if
it satisfies the requirements in the Table below.
</p>
<p>
In the Table below,
</p>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem">
<code class="computeroutput"><span class="identifier">s</span></code> denotes a (possibly
const) scheduler object of type <code class="computeroutput"><span class="identifier">S</span></code>,
</li>
<li class="listitem">
<code class="computeroutput"><span class="identifier">N</span></code> denotes a type that
models <code class="computeroutput"><span class="identifier">sender</span></code>, and
</li>
<li class="listitem">
<code class="computeroutput"><span class="identifier">n</span></code> denotes a sender object
of type <code class="computeroutput"><span class="identifier">N</span></code>
</li>
</ul></div>
<div class="table">
<a name="asio.reference.Scheduler.t0"></a><p class="title"><b>Table 27. Scheduler requirements</b></p>
<div class="table-contents"><table class="table" summary="Scheduler requirements">
<colgroup>
<col>
<col>
<col>
</colgroup>
<thead><tr>
<th>
<p>
expression
</p>
</th>
<th>
<p>
return type
</p>
</th>
<th>
<p>
operation semantics
</p>
</th>
</tr></thead>
<tbody><tr>
<td>
<p>
<code class="computeroutput"><span class="identifier">execution</span><span class="special">::</span><span class="identifier">schedule</span><span class="special">(</span><span class="identifier">s</span><span class="special">)</span></code>
</p>
</td>
<td>
<p>
<code class="computeroutput"><span class="identifier">N</span></code>
</p>
</td>
<td>
<p>
Evaluates <code class="computeroutput"><span class="identifier">execution</span><span class="special">::</span><span class="identifier">schedule</span><span class="special">(</span><span class="identifier">s</span><span class="special">)</span></code> on the calling thread to create
<code class="computeroutput"><span class="identifier">N</span></code>.
</p>
</td>
</tr></tbody>
</table></div>
</div>
<br class="table-break"><p>
<code class="computeroutput"><span class="identifier">execution</span><span class="special">::</span><span class="identifier">start</span><span class="special">(</span><span class="identifier">o</span><span class="special">)</span></code>, where
<code class="computeroutput"><span class="identifier">o</span></code> is the result of a call
to <code class="computeroutput"><span class="identifier">execution</span><span class="special">::</span><span class="identifier">connect</span><span class="special">(</span><span class="identifier">N</span><span class="special">,</span> <span class="identifier">r</span><span class="special">)</span></code> for some receiver object <code class="computeroutput"><span class="identifier">r</span></code>,
is required to eagerly submit <code class="computeroutput"><span class="identifier">r</span></code>
for execution on an execution agent that <code class="computeroutput"><span class="identifier">s</span></code>
creates for it. Let <code class="computeroutput"><span class="identifier">rc</span></code> be
<code class="computeroutput"><span class="identifier">r</span></code> or an object created by
copy or move construction from <code class="computeroutput"><span class="identifier">r</span></code>.
The semantic constraints on the <code class="computeroutput"><span class="identifier">sender</span></code>
<code class="computeroutput"><span class="identifier">N</span></code> returned from a scheduler
<code class="computeroutput"><span class="identifier">s</span></code>'s <code class="computeroutput"><span class="identifier">schedule</span></code>
function are as follows:
</p>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem">
If <code class="computeroutput"><span class="identifier">rc</span></code>'s <code class="computeroutput"><span class="identifier">set_error</span></code> function is called in response
to a submission error, scheduling error, or other internal error, let
<code class="computeroutput"><span class="identifier">E</span></code> be an expression that
refers to that error if <code class="computeroutput"><span class="identifier">set_error</span><span class="special">(</span><span class="identifier">rc</span><span class="special">,</span> <span class="identifier">E</span><span class="special">)</span></code> is well-formed; otherwise, let <code class="computeroutput"><span class="identifier">E</span></code> be an <code class="computeroutput"><span class="identifier">exception_ptr</span></code>
that refers to that error. [Note: <code class="computeroutput"><span class="identifier">E</span></code>
could be the result of calling <code class="computeroutput"><span class="identifier">current_exception</span></code>
or <code class="computeroutput"><span class="identifier">make_exception_ptr</span></code>.]
The scheduler calls <code class="computeroutput"><span class="identifier">set_error</span><span class="special">(</span><span class="identifier">rc</span><span class="special">,</span> <span class="identifier">E</span><span class="special">)</span></code> on an unspecified weakly-parallel execution
agent ([Note: An invocation of <code class="computeroutput"><span class="identifier">set_error</span></code>
on a receiver is required to be <code class="computeroutput"><span class="keyword">noexcept</span></code>]),
and
</li>
<li class="listitem">
If <code class="computeroutput"><span class="identifier">rc</span></code>'s <code class="computeroutput"><span class="identifier">set_error</span></code> function is called in response
to an exception that propagates out of the invocation of <code class="computeroutput"><span class="identifier">set_value</span></code> on <code class="computeroutput"><span class="identifier">rc</span></code>,
let <code class="computeroutput"><span class="identifier">E</span></code> be <code class="computeroutput"><span class="identifier">make_exception_ptr</span><span class="special">(</span><span class="identifier">receiver_invocation_error</span><span class="special">{})</span></code>
invoked from within a catch clause that has caught the exception. The
executor calls <code class="computeroutput"><span class="identifier">set_error</span><span class="special">(</span><span class="identifier">rc</span><span class="special">,</span> <span class="identifier">E</span><span class="special">)</span></code> on an unspecified weakly-parallel execution
agent, and
</li>
<li class="listitem">
A call to <code class="computeroutput"><span class="identifier">set_done</span><span class="special">(</span><span class="identifier">rc</span><span class="special">)</span></code>
is made on an unspecified weakly-parallel execution agent ([Note: An
invocation of a receiver's <code class="computeroutput"><span class="identifier">set_done</span></code>
function is required to be <code class="computeroutput"><span class="keyword">noexcept</span></code>]).
</li>
</ul></div>
<p>
[<span class="emphasis"><em>Note:</em></span> The senders returned from a scheduler's <code class="computeroutput"><span class="identifier">schedule</span></code> function have wide discretion
when deciding which of the three receiver functions to call upon submission.
—<span class="emphasis"><em>end note</em></span>]
</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="ResolveToken.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="Sender.html"><img src="../../next.png" alt="Next"></a>
</div>
</body>
</html>
Reference in New Issue View Git Blame Copy Permalink