1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>when_all, simple completion</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="../../../index.html" title="Chapter 1. Fiber"> 8<link rel="up" href="../when_all_functionality.html" title="when_all functionality"> 9<link rel="prev" href="../when_all_functionality.html" title="when_all functionality"> 10<link rel="next" href="when_all__return_values.html" title="when_all, return values"> 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="../when_all_functionality.html"><img src="../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../when_all_functionality.html"><img src="../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../index.html"><img src="../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="when_all__return_values.html"><img src="../../../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h4 class="title"> 27<a name="fiber.when_any.when_all_functionality.when_all__simple_completion"></a><a class="link" href="when_all__simple_completion.html" title="when_all, simple completion">when_all, 28 simple completion</a> 29</h4></div></div></div> 30<p> 31 For the case in which we must wait for <span class="emphasis"><em>all</em></span> task functions 32 to complete — but we don't need results (or expect exceptions) from any of 33 them — we can write <code class="computeroutput"><span class="identifier">wait_all_simple</span><span class="special">()</span></code> that looks remarkably like <a class="link" href="../when_any/when_any__simple_completion.html#wait_first_simple"><code class="computeroutput"><span class="identifier">wait_first_simple</span><span class="special">()</span></code></a>. 34 The difference is that instead of our <a class="link" href="../when_any/when_any__simple_completion.html#wait_done"><code class="computeroutput"><span class="identifier">Done</span></code></a> class, we instantiate a <a class="link" href="../../synchronization/barriers.html#class_barrier"><code class="computeroutput">barrier</code></a> and 35 call its <a class="link" href="../../synchronization/barriers.html#barrier_wait"><code class="computeroutput">barrier::wait()</code></a>. 36 </p> 37<p> 38 We initialize the <code class="computeroutput"><span class="identifier">barrier</span></code> 39 with <code class="computeroutput"><span class="special">(</span><span class="identifier">count</span><span class="special">+</span><span class="number">1</span><span class="special">)</span></code> 40 because we are launching <code class="computeroutput"><span class="identifier">count</span></code> 41 fibers, plus the <code class="computeroutput"><span class="identifier">wait</span><span class="special">()</span></code> 42 call within <code class="computeroutput"><span class="identifier">wait_all_simple</span><span class="special">()</span></code> itself. 43 </p> 44<p> 45</p> 46<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="special">...</span> <span class="identifier">Fns</span> <span class="special">></span> 47<span class="keyword">void</span> <span class="identifier">wait_all_simple</span><span class="special">(</span> <span class="identifier">Fns</span> <span class="special">&&</span> <span class="special">...</span> <span class="identifier">functions</span><span class="special">)</span> <span class="special">{</span> 48 <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">count</span><span class="special">(</span> <span class="keyword">sizeof</span> <span class="special">...</span> <span class="special">(</span> <span class="identifier">functions</span><span class="special">)</span> <span class="special">);</span> 49 <span class="comment">// Initialize a barrier(count+1) because we'll immediately wait on it. We</span> 50 <span class="comment">// don't want to wake up until 'count' more fibers wait on it. Even though</span> 51 <span class="comment">// we'll stick around until the last of them completes, use shared_ptr</span> 52 <span class="comment">// anyway because it's easier to be confident about lifespan issues.</span> 53 <span class="keyword">auto</span> <span class="identifier">barrier</span><span class="special">(</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">make_shared</span><span class="special"><</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">fibers</span><span class="special">::</span><span class="identifier">barrier</span> <span class="special">>(</span> <span class="identifier">count</span> <span class="special">+</span> <span class="number">1</span><span class="special">)</span> <span class="special">);</span> 54 <span class="identifier">wait_all_simple_impl</span><span class="special">(</span> <span class="identifier">barrier</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">forward</span><span class="special"><</span> <span class="identifier">Fns</span> <span class="special">>(</span> <span class="identifier">functions</span><span class="special">)</span> <span class="special">...</span> <span class="special">);</span> 55 <span class="identifier">barrier</span><span class="special">-></span><span class="identifier">wait</span><span class="special">();</span> 56<span class="special">}</span> 57</pre> 58<p> 59 </p> 60<p> 61 As stated above, the only difference between <code class="computeroutput"><span class="identifier">wait_all_simple_impl</span><span class="special">()</span></code> and <a class="link" href="../when_any/when_any__simple_completion.html#wait_first_simple_impl"><code class="computeroutput"><span class="identifier">wait_first_simple_impl</span><span class="special">()</span></code></a> 62 is that the former calls <code class="computeroutput"><span class="identifier">barrier</span><span class="special">::</span><span class="identifier">wait</span><span class="special">()</span></code> rather than <code class="computeroutput"><span class="identifier">Done</span><span class="special">::</span><span class="identifier">notify</span><span class="special">()</span></code>: 63 </p> 64<p> 65</p> 66<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">Fn</span><span class="special">,</span> <span class="keyword">typename</span> <span class="special">...</span> <span class="identifier">Fns</span> <span class="special">></span> 67<span class="keyword">void</span> <span class="identifier">wait_all_simple_impl</span><span class="special">(</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">shared_ptr</span><span class="special"><</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">fibers</span><span class="special">::</span><span class="identifier">barrier</span> <span class="special">></span> <span class="identifier">barrier</span><span class="special">,</span> 68 <span class="identifier">Fn</span> <span class="special">&&</span> <span class="identifier">function</span><span class="special">,</span> <span class="identifier">Fns</span> <span class="special">&&</span> <span class="special">...</span> <span class="identifier">functions</span><span class="special">)</span> <span class="special">{</span> 69 <span class="identifier">boost</span><span class="special">::</span><span class="identifier">fibers</span><span class="special">::</span><span class="identifier">fiber</span><span class="special">(</span> 70 <span class="identifier">std</span><span class="special">::</span><span class="identifier">bind</span><span class="special">(</span> 71 <span class="special">[](</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">shared_ptr</span><span class="special"><</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">fibers</span><span class="special">::</span><span class="identifier">barrier</span> <span class="special">></span> <span class="special">&</span> <span class="identifier">barrier</span><span class="special">,</span> 72 <span class="keyword">typename</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">decay</span><span class="special"><</span> <span class="identifier">Fn</span> <span class="special">>::</span><span class="identifier">type</span> <span class="special">&</span> <span class="identifier">function</span><span class="special">)</span> <span class="keyword">mutable</span> <span class="special">{</span> 73 <span class="identifier">function</span><span class="special">();</span> 74 <span class="identifier">barrier</span><span class="special">-></span><span class="identifier">wait</span><span class="special">();</span> 75 <span class="special">},</span> 76 <span class="identifier">barrier</span><span class="special">,</span> 77 <span class="identifier">std</span><span class="special">::</span><span class="identifier">forward</span><span class="special"><</span> <span class="identifier">Fn</span> <span class="special">>(</span> <span class="identifier">function</span><span class="special">)</span> 78 <span class="special">)).</span><span class="identifier">detach</span><span class="special">();</span> 79 <span class="identifier">wait_all_simple_impl</span><span class="special">(</span> <span class="identifier">barrier</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">forward</span><span class="special"><</span> <span class="identifier">Fns</span> <span class="special">>(</span> <span class="identifier">functions</span><span class="special">)</span> <span class="special">...</span> <span class="special">);</span> 80<span class="special">}</span> 81</pre> 82<p> 83 </p> 84<p> 85 You might call it like this: 86 </p> 87<p> 88</p> 89<pre class="programlisting"><span class="identifier">wait_all_simple</span><span class="special">(</span> 90 <span class="special">[](){</span> <span class="identifier">sleeper</span><span class="special">(</span><span class="string">"was_long"</span><span class="special">,</span> <span class="number">150</span><span class="special">);</span> <span class="special">},</span> 91 <span class="special">[](){</span> <span class="identifier">sleeper</span><span class="special">(</span><span class="string">"was_medium"</span><span class="special">,</span> <span class="number">100</span><span class="special">);</span> <span class="special">},</span> 92 <span class="special">[](){</span> <span class="identifier">sleeper</span><span class="special">(</span><span class="string">"was_short"</span><span class="special">,</span> <span class="number">50</span><span class="special">);</span> <span class="special">});</span> 93</pre> 94<p> 95 </p> 96<p> 97 Control will not return from the <code class="computeroutput"><span class="identifier">wait_all_simple</span><span class="special">()</span></code> call until the last of its task functions 98 has completed. 99 </p> 100</div> 101<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 102<td align="left"></td> 103<td align="right"><div class="copyright-footer">Copyright © 2013 Oliver Kowalke<p> 104 Distributed under the Boost Software License, Version 1.0. (See accompanying 105 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>) 106 </p> 107</div></td> 108</tr></table> 109<hr> 110<div class="spirit-nav"> 111<a accesskey="p" href="../when_all_functionality.html"><img src="../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../when_all_functionality.html"><img src="../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../index.html"><img src="../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="when_all__return_values.html"><img src="../../../../../../../doc/src/images/next.png" alt="Next"></a> 112</div> 113</body> 114</html> 115
