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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=
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29 </h4></div></div></div>
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>.
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.
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>
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>:
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>
85 You might call it like this:
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>
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
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>)
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