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25 | <div class="section"> | |
26 | <div class="titlepage"><div><div><h4 class="title"> | |
27 | <a name="fiber.when_any.when_all_functionality.when_all_until_first_exception"></a><a class="link" href="when_all_until_first_exception.html" title="when_all until first exception">when_all | |
28 | until first exception</a> | |
29 | </h4></div></div></div> | |
30 | <p> | |
31 | Naturally, just as with <a class="link" href="../when_any/when_any__produce_first_outcome__whether_result_or_exception.html#wait_first_outcome"><code class="computeroutput"><span class="identifier">wait_first_outcome</span><span class="special">()</span></code></a>, | |
32 | we can elaborate <a class="link" href="when_all__return_values.html#wait_all_values"><code class="computeroutput"><span class="identifier">wait_all_values</span><span class="special">()</span></code></a> and <a class="link" href="when_all__return_values.html#wait_all_values_source"><code class="computeroutput"><span class="identifier">wait_all_values_source</span><span class="special">()</span></code></a> | |
33 | by passing <code class="computeroutput"><span class="identifier">future</span><span class="special"><</span> | |
34 | <span class="identifier">T</span> <span class="special">></span></code> | |
35 | instead of plain <code class="computeroutput"><span class="identifier">T</span></code>. | |
36 | </p> | |
37 | <p> | |
38 | <a name="wait_all_until_error"></a><code class="computeroutput"><span class="identifier">wait_all_until_error</span><span class="special">()</span></code> pops that <code class="computeroutput"><span class="identifier">future</span><span class="special"><</span> <span class="identifier">T</span> <span class="special">></span></code> and calls its <a class="link" href="../../synchronization/futures/future.html#future_get"><code class="computeroutput">future::get()</code></a>: | |
39 | </p> | |
40 | <p> | |
41 | </p> | |
42 | <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> | |
43 | <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">result_of</span><span class="special"><</span> <span class="identifier">Fn</span><span class="special">()</span> <span class="special">>::</span><span class="identifier">type</span> <span class="special">></span> | |
44 | <span class="identifier">wait_all_until_error</span><span class="special">(</span> <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> | |
45 | <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="number">1</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> | |
46 | <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">result_of</span><span class="special"><</span> <span class="identifier">Fn</span><span class="special">()</span> <span class="special">>::</span><span class="identifier">type</span> <span class="identifier">return_t</span><span class="special">;</span> | |
47 | <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">fibers</span><span class="special">::</span><span class="identifier">future</span><span class="special"><</span> <span class="identifier">return_t</span> <span class="special">></span> <span class="identifier">future_t</span><span class="special">;</span> | |
48 | <span class="keyword">typedef</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span> <span class="identifier">return_t</span> <span class="special">></span> <span class="identifier">vector_t</span><span class="special">;</span> | |
49 | <span class="identifier">vector_t</span> <span class="identifier">results</span><span class="special">;</span> | |
50 | <span class="identifier">results</span><span class="special">.</span><span class="identifier">reserve</span><span class="special">(</span> <span class="identifier">count</span><span class="special">);</span> | |
51 | ||
52 | <span class="comment">// get channel</span> | |
53 | <span class="identifier">std</span><span class="special">::</span><span class="identifier">shared_ptr</span><span class="special"><</span> | |
54 | <span class="identifier">boost</span><span class="special">::</span><span class="identifier">fibers</span><span class="special">::</span><span class="identifier">unbounded_channel</span><span class="special"><</span> <span class="identifier">future_t</span> <span class="special">></span> <span class="special">></span> <span class="identifier">channel</span><span class="special">(</span> | |
55 | <span class="identifier">wait_all_until_error_source</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">Fn</span> <span class="special">>(</span> <span class="identifier">function</span><span class="special">),</span> | |
56 | <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> <span class="special">);</span> | |
57 | <span class="comment">// fill results vector</span> | |
58 | <span class="identifier">future_t</span> <span class="identifier">future</span><span class="special">;</span> | |
59 | <span class="keyword">while</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">channel_op_status</span><span class="special">::</span><span class="identifier">success</span> <span class="special">==</span> <span class="identifier">channel</span><span class="special">-></span><span class="identifier">pop</span><span class="special">(</span> <span class="identifier">future</span><span class="special">)</span> <span class="special">)</span> <span class="special">{</span> | |
60 | <span class="identifier">results</span><span class="special">.</span><span class="identifier">push_back</span><span class="special">(</span> <span class="identifier">future</span><span class="special">.</span><span class="identifier">get</span><span class="special">()</span> <span class="special">);</span> | |
61 | <span class="special">}</span> | |
62 | <span class="comment">// return vector to caller</span> | |
63 | <span class="keyword">return</span> <span class="identifier">results</span><span class="special">;</span> | |
64 | <span class="special">}</span> | |
65 | </pre> | |
66 | <p> | |
67 | </p> | |
68 | <p> | |
69 | For example: | |
70 | </p> | |
71 | <p> | |
72 | </p> | |
73 | <pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="identifier">thrown</span><span class="special">;</span> | |
74 | <span class="keyword">try</span> <span class="special">{</span> | |
75 | <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="special">></span> <span class="identifier">values</span> <span class="special">=</span> <span class="identifier">wait_all_until_error</span><span class="special">(</span> | |
76 | <span class="special">[](){</span> <span class="keyword">return</span> <span class="identifier">sleeper</span><span class="special">(</span><span class="string">"waue_late"</span><span class="special">,</span> <span class="number">150</span><span class="special">);</span> <span class="special">},</span> | |
77 | <span class="special">[](){</span> <span class="keyword">return</span> <span class="identifier">sleeper</span><span class="special">(</span><span class="string">"waue_middle"</span><span class="special">,</span> <span class="number">100</span><span class="special">,</span> <span class="keyword">true</span><span class="special">);</span> <span class="special">},</span> | |
78 | <span class="special">[](){</span> <span class="keyword">return</span> <span class="identifier">sleeper</span><span class="special">(</span><span class="string">"waue_early"</span><span class="special">,</span> <span class="number">50</span><span class="special">);</span> <span class="special">});</span> | |
79 | <span class="special">}</span> <span class="keyword">catch</span> <span class="special">(</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">exception</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">e</span><span class="special">)</span> <span class="special">{</span> | |
80 | <span class="identifier">thrown</span> <span class="special">=</span> <span class="identifier">e</span><span class="special">.</span><span class="identifier">what</span><span class="special">();</span> | |
81 | <span class="special">}</span> | |
82 | <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"wait_all_until_error(fail) threw '"</span> <span class="special"><<</span> <span class="identifier">thrown</span> | |
83 | <span class="special"><<</span> <span class="string">"'"</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> | |
84 | </pre> | |
85 | <p> | |
86 | </p> | |
87 | <p> | |
88 | <a name="wait_all_until_error_source"></a>Naturally this complicates the | |
89 | API for <code class="computeroutput"><span class="identifier">wait_all_until_error_source</span><span class="special">()</span></code>. The caller must both retrieve a <code class="computeroutput"><span class="identifier">future</span><span class="special"><</span> | |
90 | <span class="identifier">T</span> <span class="special">></span></code> | |
91 | and call its <code class="computeroutput"><span class="identifier">get</span><span class="special">()</span></code> | |
92 | method. It would, of course, be possible to return a façade over the consumer | |
93 | end of the channel that would implicitly perform the <code class="computeroutput"><span class="identifier">get</span><span class="special">()</span></code> and return a simple <code class="computeroutput"><span class="identifier">T</span></code> | |
94 | (or throw). | |
95 | </p> | |
96 | <p> | |
97 | The implementation is just as you would expect. Notice, however, that we | |
98 | can reuse <a class="link" href="../when_any/when_any__produce_first_outcome__whether_result_or_exception.html#wait_first_outcome_impl"><code class="computeroutput"><span class="identifier">wait_first_outcome_impl</span><span class="special">()</span></code></a>, passing the <code class="computeroutput"><span class="identifier">nchannel</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span></code> rather than <code class="computeroutput"><span class="identifier">unbounded_channel</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span></code>. | |
99 | </p> | |
100 | <p> | |
101 | </p> | |
102 | <pre class="programlisting"><span class="comment">// Return a shared_ptr<unbounded_channel<future<T>>> from which the caller can</span> | |
103 | <span class="comment">// get() each new result as it arrives, until 'closed'.</span> | |
104 | <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> | |
105 | <span class="identifier">std</span><span class="special">::</span><span class="identifier">shared_ptr</span><span class="special"><</span> | |
106 | <span class="identifier">boost</span><span class="special">::</span><span class="identifier">fibers</span><span class="special">::</span><span class="identifier">unbounded_channel</span><span class="special"><</span> | |
107 | <span class="identifier">boost</span><span class="special">::</span><span class="identifier">fibers</span><span class="special">::</span><span class="identifier">future</span><span class="special"><</span> | |
108 | <span class="keyword">typename</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">result_of</span><span class="special"><</span> <span class="identifier">Fn</span><span class="special">()</span> <span class="special">>::</span><span class="identifier">type</span> <span class="special">></span> <span class="special">></span> <span class="special">></span> | |
109 | <span class="identifier">wait_all_until_error_source</span><span class="special">(</span> <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> | |
110 | <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="number">1</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> | |
111 | <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">result_of</span><span class="special"><</span> <span class="identifier">Fn</span><span class="special">()</span> <span class="special">>::</span><span class="identifier">type</span> <span class="identifier">return_t</span><span class="special">;</span> | |
112 | <span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">fibers</span><span class="special">::</span><span class="identifier">future</span><span class="special"><</span> <span class="identifier">return_t</span> <span class="special">></span> <span class="identifier">future_t</span><span class="special">;</span> | |
113 | <span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">fibers</span><span class="special">::</span><span class="identifier">unbounded_channel</span><span class="special"><</span> <span class="identifier">future_t</span> <span class="special">></span> <span class="identifier">channel_t</span><span class="special">;</span> | |
114 | <span class="comment">// make the channel</span> | |
115 | <span class="keyword">auto</span> <span class="identifier">channelp</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">channel_t</span> <span class="special">>()</span> <span class="special">);</span> | |
116 | <span class="comment">// and make an nchannel facade to close it after 'count' items</span> | |
117 | <span class="keyword">auto</span> <span class="identifier">ncp</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">nchannel</span><span class="special"><</span> <span class="identifier">future_t</span> <span class="special">></span> <span class="special">>(</span> <span class="identifier">channelp</span><span class="special">,</span> <span class="identifier">count</span><span class="special">)</span> <span class="special">);</span> | |
118 | <span class="comment">// pass that nchannel facade to all the relevant fibers</span> | |
119 | <span class="identifier">wait_first_outcome_impl</span><span class="special"><</span> <span class="identifier">return_t</span> <span class="special">>(</span> <span class="identifier">ncp</span><span class="special">,</span> | |
120 | <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> | |
121 | <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> | |
122 | <span class="comment">// then return the channel for consumer</span> | |
123 | <span class="keyword">return</span> <span class="identifier">channelp</span><span class="special">;</span> | |
124 | <span class="special">}</span> | |
125 | </pre> | |
126 | <p> | |
127 | </p> | |
128 | <p> | |
129 | For example: | |
130 | </p> | |
131 | <p> | |
132 | </p> | |
133 | <pre class="programlisting"><span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">fibers</span><span class="special">::</span><span class="identifier">future</span><span class="special"><</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="special">></span> <span class="identifier">future_t</span><span class="special">;</span> | |
134 | <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">unbounded_channel</span><span class="special"><</span> <span class="identifier">future_t</span> <span class="special">></span> <span class="special">></span> <span class="identifier">channel</span> <span class="special">=</span> | |
135 | <span class="identifier">wait_all_until_error_source</span><span class="special">(</span> | |
136 | <span class="special">[](){</span> <span class="keyword">return</span> <span class="identifier">sleeper</span><span class="special">(</span><span class="string">"wauess_third"</span><span class="special">,</span> <span class="number">150</span><span class="special">);</span> <span class="special">},</span> | |
137 | <span class="special">[](){</span> <span class="keyword">return</span> <span class="identifier">sleeper</span><span class="special">(</span><span class="string">"wauess_second"</span><span class="special">,</span> <span class="number">100</span><span class="special">);</span> <span class="special">},</span> | |
138 | <span class="special">[](){</span> <span class="keyword">return</span> <span class="identifier">sleeper</span><span class="special">(</span><span class="string">"wauess_first"</span><span class="special">,</span> <span class="number">50</span><span class="special">);</span> <span class="special">});</span> | |
139 | <span class="identifier">future_t</span> <span class="identifier">future</span><span class="special">;</span> | |
140 | <span class="keyword">while</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">channel_op_status</span><span class="special">::</span><span class="identifier">success</span> <span class="special">==</span> <span class="identifier">channel</span><span class="special">-></span><span class="identifier">pop</span><span class="special">(</span> <span class="identifier">future</span><span class="special">)</span> <span class="special">)</span> <span class="special">{</span> | |
141 | <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="identifier">value</span><span class="special">(</span> <span class="identifier">future</span><span class="special">.</span><span class="identifier">get</span><span class="special">()</span> <span class="special">);</span> | |
142 | <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"wait_all_until_error_source(success) => '"</span> <span class="special"><<</span> <span class="identifier">value</span> | |
143 | <span class="special"><<</span> <span class="string">"'"</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> | |
144 | <span class="special">}</span> | |
145 | </pre> | |
146 | <p> | |
147 | </p> | |
148 | </div> | |
149 | <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> | |
150 | <td align="left"></td> | |
151 | <td align="right"><div class="copyright-footer">Copyright © 2013 Oliver Kowalke<p> | |
152 | Distributed under the Boost Software License, Version 1.0. (See accompanying | |
153 | 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>) | |
154 | </p> | |
155 | </div></td> | |
156 | </tr></table> | |
157 | <hr> | |
158 | <div class="spirit-nav"> | |
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