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| 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> | |
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