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<a href="async__result_8h.html">Go to the documentation of this file.</a><div class="fragment"><div class="line"><a name="l00001"></a><span class="lineno"> 1</span> <span class="comment">/* Copyright (C) 2012 and 2013 Chris Vine</span></div>
<div class="line"><a name="l00002"></a><span class="lineno"> 2</span> <span class="comment"></span></div>
<div class="line"><a name="l00003"></a><span class="lineno"> 3</span> <span class="comment">The library comprised in this file or of which this file is part is</span></div>
<div class="line"><a name="l00004"></a><span class="lineno"> 4</span> <span class="comment">distributed by Chris Vine under the GNU Lesser General Public</span></div>
<div class="line"><a name="l00005"></a><span class="lineno"> 5</span> <span class="comment">License as follows:</span></div>
<div class="line"><a name="l00006"></a><span class="lineno"> 6</span> <span class="comment"></span></div>
<div class="line"><a name="l00007"></a><span class="lineno"> 7</span> <span class="comment"> This library is free software; you can redistribute it and/or</span></div>
<div class="line"><a name="l00008"></a><span class="lineno"> 8</span> <span class="comment"> modify it under the terms of the GNU Lesser General Public License</span></div>
<div class="line"><a name="l00009"></a><span class="lineno"> 9</span> <span class="comment"> as published by the Free Software Foundation; either version 2.1 of</span></div>
<div class="line"><a name="l00010"></a><span class="lineno"> 10</span> <span class="comment"> the License, or (at your option) any later version.</span></div>
<div class="line"><a name="l00011"></a><span class="lineno"> 11</span> <span class="comment"></span></div>
<div class="line"><a name="l00012"></a><span class="lineno"> 12</span> <span class="comment"> This library is distributed in the hope that it will be useful, but</span></div>
<div class="line"><a name="l00013"></a><span class="lineno"> 13</span> <span class="comment"> WITHOUT ANY WARRANTY; without even the implied warranty of</span></div>
<div class="line"><a name="l00014"></a><span class="lineno"> 14</span> <span class="comment"> MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU</span></div>
<div class="line"><a name="l00015"></a><span class="lineno"> 15</span> <span class="comment"> Lesser General Public License, version 2.1, for more details.</span></div>
<div class="line"><a name="l00016"></a><span class="lineno"> 16</span> <span class="comment"></span></div>
<div class="line"><a name="l00017"></a><span class="lineno"> 17</span> <span class="comment"> You should have received a copy of the GNU Lesser General Public</span></div>
<div class="line"><a name="l00018"></a><span class="lineno"> 18</span> <span class="comment"> License, version 2.1, along with this library (see the file LGPL.TXT</span></div>
<div class="line"><a name="l00019"></a><span class="lineno"> 19</span> <span class="comment"> which came with this source code package in the c++-gtk-utils</span></div>
<div class="line"><a name="l00020"></a><span class="lineno"> 20</span> <span class="comment"> sub-directory); if not, write to the Free Software Foundation, Inc.,</span></div>
<div class="line"><a name="l00021"></a><span class="lineno"> 21</span> <span class="comment"> 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.</span></div>
<div class="line"><a name="l00022"></a><span class="lineno"> 22</span> <span class="comment"></span></div>
<div class="line"><a name="l00023"></a><span class="lineno"> 23</span> <span class="comment">However, it is not intended that the object code of a program whose</span></div>
<div class="line"><a name="l00024"></a><span class="lineno"> 24</span> <span class="comment">source code instantiates a template from this file or uses macros or</span></div>
<div class="line"><a name="l00025"></a><span class="lineno"> 25</span> <span class="comment">inline functions (of any length) should by reason only of that</span></div>
<div class="line"><a name="l00026"></a><span class="lineno"> 26</span> <span class="comment">instantiation or use be subject to the restrictions of use in the GNU</span></div>
<div class="line"><a name="l00027"></a><span class="lineno"> 27</span> <span class="comment">Lesser General Public License. With that in mind, the words "and</span></div>
<div class="line"><a name="l00028"></a><span class="lineno"> 28</span> <span class="comment">macros, inline functions and instantiations of templates (of any</span></div>
<div class="line"><a name="l00029"></a><span class="lineno"> 29</span> <span class="comment">length)" shall be treated as substituted for the words "and small</span></div>
<div class="line"><a name="l00030"></a><span class="lineno"> 30</span> <span class="comment">macros and small inline functions (ten lines or less in length)" in</span></div>
<div class="line"><a name="l00031"></a><span class="lineno"> 31</span> <span class="comment">the fourth paragraph of section 5 of that licence. This does not</span></div>
<div class="line"><a name="l00032"></a><span class="lineno"> 32</span> <span class="comment">affect any other reason why object code may be subject to the</span></div>
<div class="line"><a name="l00033"></a><span class="lineno"> 33</span> <span class="comment">restrictions in that licence (nor for the avoidance of doubt does it</span></div>
<div class="line"><a name="l00034"></a><span class="lineno"> 34</span> <span class="comment">affect the application of section 2 of that licence to modifications</span></div>
<div class="line"><a name="l00035"></a><span class="lineno"> 35</span> <span class="comment">of the source code in this file).</span></div>
<div class="line"><a name="l00036"></a><span class="lineno"> 36</span> <span class="comment"></span></div>
<div class="line"><a name="l00037"></a><span class="lineno"> 37</span> <span class="comment">*/</span></div>
<div class="line"><a name="l00038"></a><span class="lineno"> 38</span> <span class="comment"></span></div>
<div class="line"><a name="l00039"></a><span class="lineno"> 39</span> <span class="comment">/**</span></div>
<div class="line"><a name="l00040"></a><span class="lineno"> 40</span> <span class="comment"> * @file async_result.h</span></div>
<div class="line"><a name="l00041"></a><span class="lineno"> 41</span> <span class="comment"> * @brief This file provides a thread-safe asynchronous result class.</span></div>
<div class="line"><a name="l00042"></a><span class="lineno"> 42</span> <span class="comment"> */</span></div>
<div class="line"><a name="l00043"></a><span class="lineno"> 43</span> </div>
<div class="line"><a name="l00044"></a><span class="lineno"> 44</span> <span class="preprocessor">#ifndef CGU_ASYNC_RESULT_H</span></div>
<div class="line"><a name="l00045"></a><span class="lineno"> 45</span> <span class="preprocessor"></span><span class="preprocessor">#define CGU_ASYNC_RESULT_H</span></div>
<div class="line"><a name="l00046"></a><span class="lineno"> 46</span> <span class="preprocessor"></span></div>
<div class="line"><a name="l00047"></a><span class="lineno"> 47</span> <span class="preprocessor">#include <utility></span> <span class="comment">// for std::move</span></div>
<div class="line"><a name="l00048"></a><span class="lineno"> 48</span> </div>
<div class="line"><a name="l00049"></a><span class="lineno"> 49</span> <span class="preprocessor">#include <<a class="code" href="mutex_8h.html" title="Provides wrapper classes for pthread mutexes and condition variables, and scoped locking classes for ...">c++-gtk-utils/mutex.h</a>></span></div>
<div class="line"><a name="l00050"></a><span class="lineno"> 50</span> <span class="preprocessor">#include <<a class="code" href="thread_8h.html">c++-gtk-utils/thread.h</a>></span></div>
<div class="line"><a name="l00051"></a><span class="lineno"> 51</span> <span class="preprocessor">#include <<a class="code" href="cgu__config_8h.html">c++-gtk-utils/cgu_config.h</a>></span></div>
<div class="line"><a name="l00052"></a><span class="lineno"> 52</span> </div>
<div class="line"><a name="l00053"></a><span class="lineno"> 53</span> </div>
<div class="line"><a name="l00054"></a><span class="lineno"> 54</span> <span class="keyword">namespace </span>Cgu {</div>
<div class="line"><a name="l00055"></a><span class="lineno"> 55</span> <span class="comment"></span></div>
<div class="line"><a name="l00056"></a><span class="lineno"> 56</span> <span class="comment">/**</span></div>
<div class="line"><a name="l00057"></a><span class="lineno"> 57</span> <span class="comment"> * @class AsyncResult async_result.h c++-gtk-utils/async_result.h</span></div>
<div class="line"><a name="l00058"></a><span class="lineno"> 58</span> <span class="comment"> * @brief A thread-safe asynchronous result class.</span></div>
<div class="line"><a name="l00059"></a><span class="lineno"> 59</span> <span class="comment"> * @sa AsyncQueueDispatch Thread::Future</span></div>
<div class="line"><a name="l00060"></a><span class="lineno"> 60</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00061"></a><span class="lineno"> 61</span> <span class="comment"> * Cgu::Thread::Future operates on the principle of there being one</span></div>
<div class="line"><a name="l00062"></a><span class="lineno"> 62</span> <span class="comment"> * worker thread per task. In some cases however, it may be better to</span></div>
<div class="line"><a name="l00063"></a><span class="lineno"> 63</span> <span class="comment"> * have a worker thread, or a limited pool of worker threads,</span></div>
<div class="line"><a name="l00064"></a><span class="lineno"> 64</span> <span class="comment"> * executing a larger number of tasks. This can be implemented by</span></div>
<div class="line"><a name="l00065"></a><span class="lineno"> 65</span> <span class="comment"> * having a worker thread or threads waiting on a</span></div>
<div class="line"><a name="l00066"></a><span class="lineno"> 66</span> <span class="comment"> * Cgu::AsyncQueueDispatch object, onto which other threads push tasks</span></div>
<div class="line"><a name="l00067"></a><span class="lineno"> 67</span> <span class="comment"> * represented by std::unique_ptr<const Cgu::Callback::Callback> or</span></div>
<div class="line"><a name="l00068"></a><span class="lineno"> 68</span> <span class="comment"> * Cgu::Callback::SafeFunctor objects.</span></div>
<div class="line"><a name="l00069"></a><span class="lineno"> 69</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00070"></a><span class="lineno"> 70</span> <span class="comment"> * Where this model is adopted, when a task completes it may report</span></div>
<div class="line"><a name="l00071"></a><span class="lineno"> 71</span> <span class="comment"> * its results by dispatching a further callback to a glib main loop</span></div>
<div class="line"><a name="l00072"></a><span class="lineno"> 72</span> <span class="comment"> * using Cgu::Callback::post(). However, there will also be cases</span></div>
<div class="line"><a name="l00073"></a><span class="lineno"> 73</span> <span class="comment"> * where, rather than passing a result as an event to a main loop, a</span></div>
<div class="line"><a name="l00074"></a><span class="lineno"> 74</span> <span class="comment"> * thread is to to wait for the task to complete. This class is</span></div>
<div class="line"><a name="l00075"></a><span class="lineno"> 75</span> <span class="comment"> * intended to facilitate that. It operates in a way which is similar</span></div>
<div class="line"><a name="l00076"></a><span class="lineno"> 76</span> <span class="comment"> * to the std::promise class in C++11. The thread which wishes to</span></div>
<div class="line"><a name="l00077"></a><span class="lineno"> 77</span> <span class="comment"> * extract a result can call the get() method, which will block until</span></div>
<div class="line"><a name="l00078"></a><span class="lineno"> 78</span> <span class="comment"> * the worker thread has called the set() method or posted an error.</span></div>
<div class="line"><a name="l00079"></a><span class="lineno"> 79</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00080"></a><span class="lineno"> 80</span> <span class="comment"> * For safety reasons, the get() method returns by value and so will</span></div>
<div class="line"><a name="l00081"></a><span class="lineno"> 81</span> <span class="comment"> * cause that value to be copied once. From version 2.0.11 a</span></div>
<div class="line"><a name="l00082"></a><span class="lineno"> 82</span> <span class="comment"> * move_get() method is provided which will make a move operation</span></div>
<div class="line"><a name="l00083"></a><span class="lineno"> 83</span> <span class="comment"> * instead of a copy if the value type implements a move constructor,</span></div>
<div class="line"><a name="l00084"></a><span class="lineno"> 84</span> <span class="comment"> * but see the documentation on move_get() for the caveats with</span></div>
<div class="line"><a name="l00085"></a><span class="lineno"> 85</span> <span class="comment"> * respect to its use: in particular, if move_get() is to be called by</span></div>
<div class="line"><a name="l00086"></a><span class="lineno"> 86</span> <span class="comment"> * a thread, then get() may not be called by another thread.</span></div>
<div class="line"><a name="l00087"></a><span class="lineno"> 87</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00088"></a><span class="lineno"> 88</span> <span class="comment"> * Here is a compilable example of a calculator class which runs a</span></div>
<div class="line"><a name="l00089"></a><span class="lineno"> 89</span> <span class="comment"> * dedicated thread on which it carries out all its calculations:</span></div>
<div class="line"><a name="l00090"></a><span class="lineno"> 90</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00091"></a><span class="lineno"> 91</span> <span class="comment"> * @code </span></div>
<div class="line"><a name="l00092"></a><span class="lineno"> 92</span> <span class="comment"> * #include <vector></span></div>
<div class="line"><a name="l00093"></a><span class="lineno"> 93</span> <span class="comment"> * #include <numeric></span></div>
<div class="line"><a name="l00094"></a><span class="lineno"> 94</span> <span class="comment"> * #include <memory></span></div>
<div class="line"><a name="l00095"></a><span class="lineno"> 95</span> <span class="comment"> * #include <ostream></span></div>
<div class="line"><a name="l00096"></a><span class="lineno"> 96</span> <span class="comment"> * #include <iostream></span></div>
<div class="line"><a name="l00097"></a><span class="lineno"> 97</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00098"></a><span class="lineno"> 98</span> <span class="comment"> * #include <c++-gtk-utils/async_result.h></span></div>
<div class="line"><a name="l00099"></a><span class="lineno"> 99</span> <span class="comment"> * #include <c++-gtk-utils/async_queue.h></span></div>
<div class="line"><a name="l00100"></a><span class="lineno"> 100</span> <span class="comment"> * #include <c++-gtk-utils/shared_ptr.h></span></div>
<div class="line"><a name="l00101"></a><span class="lineno"> 101</span> <span class="comment"> * #include <c++-gtk-utils/thread.h></span></div>
<div class="line"><a name="l00102"></a><span class="lineno"> 102</span> <span class="comment"> * #include <c++-gtk-utils/callback.h></span></div>
<div class="line"><a name="l00103"></a><span class="lineno"> 103</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00104"></a><span class="lineno"> 104</span> <span class="comment"> * using namespace Cgu;</span></div>
<div class="line"><a name="l00105"></a><span class="lineno"> 105</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00106"></a><span class="lineno"> 106</span> <span class="comment"> * class Calcs {</span></div>
<div class="line"><a name="l00107"></a><span class="lineno"> 107</span> <span class="comment"> * AsyncQueueDispatch<std::unique_ptr<const Callback::Callback>> jobs;</span></div>
<div class="line"><a name="l00108"></a><span class="lineno"> 108</span> <span class="comment"> * Thread::JoinableHandle t;</span></div>
<div class="line"><a name="l00109"></a><span class="lineno"> 109</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00110"></a><span class="lineno"> 110</span> <span class="comment"> * void do_jobs() {</span></div>
<div class="line"><a name="l00111"></a><span class="lineno"> 111</span> <span class="comment"> * for (;;) {</span></div>
<div class="line"><a name="l00112"></a><span class="lineno"> 112</span> <span class="comment"> * std::unique_ptr<const Callback::Callback> job;</span></div>
<div class="line"><a name="l00113"></a><span class="lineno"> 113</span> <span class="comment"> * jobs.move_pop_dispatch(job);</span></div>
<div class="line"><a name="l00114"></a><span class="lineno"> 114</span> <span class="comment"> * job->dispatch();</span></div>
<div class="line"><a name="l00115"></a><span class="lineno"> 115</span> <span class="comment"> * }</span></div>
<div class="line"><a name="l00116"></a><span class="lineno"> 116</span> <span class="comment"> * }</span></div>
<div class="line"><a name="l00117"></a><span class="lineno"> 117</span> <span class="comment"> * public:</span></div>
<div class="line"><a name="l00118"></a><span class="lineno"> 118</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00119"></a><span class="lineno"> 119</span> <span class="comment"> * SharedLockPtr<AsyncResult<double>> mean(const std::vector<double>& nums) {</span></div>
<div class="line"><a name="l00120"></a><span class="lineno"> 120</span> <span class="comment"> * SharedLockPtr<AsyncResult<double>> res(new AsyncResult<double>);</span></div>
<div class="line"><a name="l00121"></a><span class="lineno"> 121</span> <span class="comment"> * jobs.emplace(Callback::lambda<>([=]() {</span></div>
<div class="line"><a name="l00122"></a><span class="lineno"> 122</span> <span class="comment"> * if (nums.empty()) res->set(0.0);</span></div>
<div class="line"><a name="l00123"></a><span class="lineno"> 123</span> <span class="comment"> * else res->set(std::accumulate(nums.begin(), nums.end(), 0.0)/nums.size());</span></div>
<div class="line"><a name="l00124"></a><span class="lineno"> 124</span> <span class="comment"> * }));</span></div>
<div class="line"><a name="l00125"></a><span class="lineno"> 125</span> <span class="comment"> * return res;</span></div>
<div class="line"><a name="l00126"></a><span class="lineno"> 126</span> <span class="comment"> * }</span></div>
<div class="line"><a name="l00127"></a><span class="lineno"> 127</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00128"></a><span class="lineno"> 128</span> <span class="comment"> * // ... other calculation methods here</span></div>
<div class="line"><a name="l00129"></a><span class="lineno"> 129</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00130"></a><span class="lineno"> 130</span> <span class="comment"> * Calcs() {</span></div>
<div class="line"><a name="l00131"></a><span class="lineno"> 131</span> <span class="comment"> * t = Thread::JoinableHandle(Thread::Thread::start(Callback::make(*this, &Calcs::do_jobs), true), </span></div>
<div class="line"><a name="l00132"></a><span class="lineno"> 132</span> <span class="comment"> * Thread::JoinableHandle::join_on_exit);</span></div>
<div class="line"><a name="l00133"></a><span class="lineno"> 133</span> <span class="comment"> * if (!t.is_managing()) throw "Thread start error";</span></div>
<div class="line"><a name="l00134"></a><span class="lineno"> 134</span> <span class="comment"> * }</span></div>
<div class="line"><a name="l00135"></a><span class="lineno"> 135</span> <span class="comment"> * ~Calcs() {</span></div>
<div class="line"><a name="l00136"></a><span class="lineno"> 136</span> <span class="comment"> * jobs.emplace(Callback::lambda<>([]() {throw Thread::Exit();}));</span></div>
<div class="line"><a name="l00137"></a><span class="lineno"> 137</span> <span class="comment"> * t.join();</span></div>
<div class="line"><a name="l00138"></a><span class="lineno"> 138</span> <span class="comment"> * }</span></div>
<div class="line"><a name="l00139"></a><span class="lineno"> 139</span> <span class="comment"> * };</span></div>
<div class="line"><a name="l00140"></a><span class="lineno"> 140</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00141"></a><span class="lineno"> 141</span> <span class="comment"> * int main () {</span></div>
<div class="line"><a name="l00142"></a><span class="lineno"> 142</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00143"></a><span class="lineno"> 143</span> <span class="comment"> * Calcs calcs;</span></div>
<div class="line"><a name="l00144"></a><span class="lineno"> 144</span> <span class="comment"> * auto res1 = calcs.mean({1, 2, 8, 0});</span></div>
<div class="line"><a name="l00145"></a><span class="lineno"> 145</span> <span class="comment"> * auto res2 = calcs.mean({101, 53.7, 87, 1.2});</span></div>
<div class="line"><a name="l00146"></a><span class="lineno"> 146</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00147"></a><span class="lineno"> 147</span> <span class="comment"> * // ... do something else</span></div>
<div class="line"><a name="l00148"></a><span class="lineno"> 148</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00149"></a><span class="lineno"> 149</span> <span class="comment"> * std::cout << res1->get() << std::endl;</span></div>
<div class="line"><a name="l00150"></a><span class="lineno"> 150</span> <span class="comment"> * std::cout << res2->get() << std::endl;</span></div>
<div class="line"><a name="l00151"></a><span class="lineno"> 151</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00152"></a><span class="lineno"> 152</span> <span class="comment"> * }</span></div>
<div class="line"><a name="l00153"></a><span class="lineno"> 153</span> <span class="comment"> * @endcode</span></div>
<div class="line"><a name="l00154"></a><span class="lineno"> 154</span> <span class="comment"> * </span></div>
<div class="line"><a name="l00155"></a><span class="lineno"> 155</span> <span class="comment"> * AsyncResult objects cannot be copied by value, and as they need to</span></div>
<div class="line"><a name="l00156"></a><span class="lineno"> 156</span> <span class="comment"> * be visible both to the set()ing and get()ing threads, it will often</span></div>
<div class="line"><a name="l00157"></a><span class="lineno"> 157</span> <span class="comment"> * be easiest to construct them on free store and copy them by smart</span></div>
<div class="line"><a name="l00158"></a><span class="lineno"> 158</span> <span class="comment"> * pointer, as in the example above. However, if the library is</span></div>
<div class="line"><a name="l00159"></a><span class="lineno"> 159</span> <span class="comment"> * compiled with the \--with-glib-memory-slices-compat or</span></div>
<div class="line"><a name="l00160"></a><span class="lineno"> 160</span> <span class="comment"> * \--with-glib-memory-slices-no-compat configuration options, any</span></div>
<div class="line"><a name="l00161"></a><span class="lineno"> 161</span> <span class="comment"> * AsyncResult object constructed on free store will be constructed in</span></div>
<div class="line"><a name="l00162"></a><span class="lineno"> 162</span> <span class="comment"> * glib memory slices, which are an efficient small object allocator.</span></div>
<div class="line"><a name="l00163"></a><span class="lineno"> 163</span> <span class="comment"> */</span></div>
<div class="line"><a name="l00164"></a><span class="lineno"> 164</span> </div>
<div class="line"><a name="l00165"></a><span class="lineno"><a class="code" href="classCgu_1_1AsyncResult.html"> 165</a></span> <span class="keyword">template</span> <<span class="keyword">class</span> T> <span class="keyword">class </span><a class="code" href="classCgu_1_1AsyncResult.html" title="A thread-safe asynchronous result class. ">AsyncResult</a> {</div>
<div class="line"><a name="l00166"></a><span class="lineno"> 166</span>  T res;</div>
<div class="line"><a name="l00167"></a><span class="lineno"> 167</span>  <span class="keywordtype">bool</span> done;</div>
<div class="line"><a name="l00168"></a><span class="lineno"> 168</span>  <span class="keywordtype">int</span> error;</div>
<div class="line"><a name="l00169"></a><span class="lineno"> 169</span>  <span class="keyword">mutable</span> <a class="code" href="classCgu_1_1Thread_1_1Mutex.html" title="A wrapper class for pthread mutexes. ">Thread::Mutex</a> mutex;</div>
<div class="line"><a name="l00170"></a><span class="lineno"> 170</span>  <span class="keyword">mutable</span> <a class="code" href="classCgu_1_1Thread_1_1Cond.html" title="A wrapper class for pthread condition variables. ">Thread::Cond</a> cond;</div>
<div class="line"><a name="l00171"></a><span class="lineno"> 171</span> </div>
<div class="line"><a name="l00172"></a><span class="lineno"> 172</span> <span class="keyword">public</span>:<span class="comment"></span></div>
<div class="line"><a name="l00173"></a><span class="lineno"> 173</span> <span class="comment">/**</span></div>
<div class="line"><a name="l00174"></a><span class="lineno"> 174</span> <span class="comment"> * @exception Thread::MutexError The constructor might throw this</span></div>
<div class="line"><a name="l00175"></a><span class="lineno"> 175</span> <span class="comment"> * exception if initialisation of the contained mutex fails. (It is</span></div>
<div class="line"><a name="l00176"></a><span class="lineno"> 176</span> <span class="comment"> * often not worth checking for this, as it means either memory is</span></div>
<div class="line"><a name="l00177"></a><span class="lineno"> 177</span> <span class="comment"> * exhausted or pthread has run out of other resources to create new</span></div>
<div class="line"><a name="l00178"></a><span class="lineno"> 178</span> <span class="comment"> * mutexes.) The constructor will also throw if the default</span></div>
<div class="line"><a name="l00179"></a><span class="lineno"> 179</span> <span class="comment"> * constructor of the result type represented by this object throws.</span></div>
<div class="line"><a name="l00180"></a><span class="lineno"> 180</span> <span class="comment"> * @exception Thread::CondError The constructor might throw this</span></div>
<div class="line"><a name="l00181"></a><span class="lineno"> 181</span> <span class="comment"> * exception if initialisation of the contained condition variable</span></div>
<div class="line"><a name="l00182"></a><span class="lineno"> 182</span> <span class="comment"> * fails. (It is often not worth checking for this, as it means</span></div>
<div class="line"><a name="l00183"></a><span class="lineno"> 183</span> <span class="comment"> * either memory is exhausted or pthread has run out of other</span></div>
<div class="line"><a name="l00184"></a><span class="lineno"> 184</span> <span class="comment"> * resources to create new condition variables.) The constructor will</span></div>
<div class="line"><a name="l00185"></a><span class="lineno"> 185</span> <span class="comment"> * also throw if the default constructor of the result type</span></div>
<div class="line"><a name="l00186"></a><span class="lineno"> 186</span> <span class="comment"> * represented by this object throws.</span></div>
<div class="line"><a name="l00187"></a><span class="lineno"> 187</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00188"></a><span class="lineno"> 188</span> <span class="comment"> * Since 2.0.8</span></div>
<div class="line"><a name="l00189"></a><span class="lineno"> 189</span> <span class="comment"> */</span></div>
<div class="line"><a name="l00190"></a><span class="lineno"><a class="code" href="classCgu_1_1AsyncResult.html#a5084b8009e36650c70a1177de9a2f870"> 190</a></span>  <a class="code" href="classCgu_1_1AsyncResult.html#a5084b8009e36650c70a1177de9a2f870">AsyncResult</a>(): res(), done(false), error(0) {}</div>
<div class="line"><a name="l00191"></a><span class="lineno"> 191</span> </div>
<div class="line"><a name="l00192"></a><span class="lineno"><a class="code" href="classCgu_1_1AsyncResult.html#a661e63288175e969c3db641eb3f6f4b5"> 192</a></span>  <a class="code" href="classCgu_1_1AsyncResult.html#a661e63288175e969c3db641eb3f6f4b5">~AsyncResult</a>() {</div>
<div class="line"><a name="l00193"></a><span class="lineno"> 193</span>  <span class="comment">// lock and unlock the mutex in the destructor so that we have an</span></div>
<div class="line"><a name="l00194"></a><span class="lineno"> 194</span>  <span class="comment">// acquire operation to ensure that when this object is destroyed</span></div>
<div class="line"><a name="l00195"></a><span class="lineno"> 195</span>  <span class="comment">// memory is synchronised, so any thread may destroy this object</span></div>
<div class="line"><a name="l00196"></a><span class="lineno"> 196</span>  <a class="code" href="classCgu_1_1Thread_1_1Mutex_1_1Lock.html" title="A scoped locking class for exception safe Mutex locking. ">Thread::Mutex::Lock</a> lock{mutex};</div>
<div class="line"><a name="l00197"></a><span class="lineno"> 197</span>  }</div>
<div class="line"><a name="l00198"></a><span class="lineno"> 198</span> </div>
<div class="line"><a name="l00199"></a><span class="lineno"> 199</span>  <span class="comment">// AsyncResult objects cannot be copied - they are mainly</span></div>
<div class="line"><a name="l00200"></a><span class="lineno"> 200</span>  <span class="comment">// intended to pass a result between two known threads</span><span class="comment"></span></div>
<div class="line"><a name="l00201"></a><span class="lineno"> 201</span> <span class="comment"> /**</span></div>
<div class="line"><a name="l00202"></a><span class="lineno"> 202</span> <span class="comment"> * This class cannot be copied. The copy constructor is deleted.</span></div>
<div class="line"><a name="l00203"></a><span class="lineno"> 203</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00204"></a><span class="lineno"> 204</span> <span class="comment"> * Since 2.0.8</span></div>
<div class="line"><a name="l00205"></a><span class="lineno"> 205</span> <span class="comment"> */</span></div>
<div class="line"><a name="l00206"></a><span class="lineno"> 206</span>  <a class="code" href="classCgu_1_1AsyncResult.html#a5084b8009e36650c70a1177de9a2f870">AsyncResult</a>(<span class="keyword">const</span> <a class="code" href="classCgu_1_1AsyncResult.html" title="A thread-safe asynchronous result class. ">AsyncResult</a>&) = <span class="keyword">delete</span>;</div>
<div class="line"><a name="l00207"></a><span class="lineno"> 207</span> <span class="comment"></span></div>
<div class="line"><a name="l00208"></a><span class="lineno"> 208</span> <span class="comment"> /**</span></div>
<div class="line"><a name="l00209"></a><span class="lineno"> 209</span> <span class="comment"> * This class cannot be copied. The assignment operator is deleted.</span></div>
<div class="line"><a name="l00210"></a><span class="lineno"> 210</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00211"></a><span class="lineno"> 211</span> <span class="comment"> * Since 2.0.8</span></div>
<div class="line"><a name="l00212"></a><span class="lineno"> 212</span> <span class="comment"> */</span></div>
<div class="line"><a name="l00213"></a><span class="lineno"> 213</span>  <a class="code" href="classCgu_1_1AsyncResult.html" title="A thread-safe asynchronous result class. ">AsyncResult</a>& <a class="code" href="classCgu_1_1AsyncResult.html#acbcd3f48526999696101b9d012917067">operator=</a>(<span class="keyword">const</span> <a class="code" href="classCgu_1_1AsyncResult.html" title="A thread-safe asynchronous result class. ">AsyncResult</a>&) = <span class="keyword">delete</span>;</div>
<div class="line"><a name="l00214"></a><span class="lineno"> 214</span> <span class="comment"></span></div>
<div class="line"><a name="l00215"></a><span class="lineno"> 215</span> <span class="comment"> /**</span></div>
<div class="line"><a name="l00216"></a><span class="lineno"> 216</span> <span class="comment"> * This method sets the value represented by the AsyncResult object,</span></div>
<div class="line"><a name="l00217"></a><span class="lineno"> 217</span> <span class="comment"> * provided that set() has not previously been called and</span></div>
<div class="line"><a name="l00218"></a><span class="lineno"> 218</span> <span class="comment"> * set_error() has not previously been called with a value other</span></div>
<div class="line"><a name="l00219"></a><span class="lineno"> 219</span> <span class="comment"> * than 0. If set() has previously been called or set_error()</span></div>
<div class="line"><a name="l00220"></a><span class="lineno"> 220</span> <span class="comment"> * called with a value other than 0 (so that is_done() will return</span></div>
<div class="line"><a name="l00221"></a><span class="lineno"> 221</span> <span class="comment"> * true) this method does nothing. It is thread safe. It is not a</span></div>
<div class="line"><a name="l00222"></a><span class="lineno"> 222</span> <span class="comment"> * cancellation point. It will not throw unless the copy assignment</span></div>
<div class="line"><a name="l00223"></a><span class="lineno"> 223</span> <span class="comment"> * operator of the value type throws.</span></div>
<div class="line"><a name="l00224"></a><span class="lineno"> 224</span> <span class="comment"> * @param val The value which this object is to represent and which</span></div>
<div class="line"><a name="l00225"></a><span class="lineno"> 225</span> <span class="comment"> * calls to get() or a call to move_get() will return. Any thread</span></div>
<div class="line"><a name="l00226"></a><span class="lineno"> 226</span> <span class="comment"> * waiting on get() or move_get() will unblock, and any subsequent</span></div>
<div class="line"><a name="l00227"></a><span class="lineno"> 227</span> <span class="comment"> * calls to is_done() will return true.</span></div>
<div class="line"><a name="l00228"></a><span class="lineno"> 228</span> <span class="comment"> * @return true if the call to this method is effective because</span></div>
<div class="line"><a name="l00229"></a><span class="lineno"> 229</span> <span class="comment"> * set() has not previously been called and set_error() has not</span></div>
<div class="line"><a name="l00230"></a><span class="lineno"> 230</span> <span class="comment"> * previously been called with a value other than 0, otherwise</span></div>
<div class="line"><a name="l00231"></a><span class="lineno"> 231</span> <span class="comment"> * false.</span></div>
<div class="line"><a name="l00232"></a><span class="lineno"> 232</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00233"></a><span class="lineno"> 233</span> <span class="comment"> * Since 2.0.8</span></div>
<div class="line"><a name="l00234"></a><span class="lineno"> 234</span> <span class="comment"> */</span></div>
<div class="line"><a name="l00235"></a><span class="lineno"><a class="code" href="classCgu_1_1AsyncResult.html#a3cf99fc76547e0155a2d5d1608c22de7"> 235</a></span>  <span class="keywordtype">bool</span> <a class="code" href="classCgu_1_1AsyncResult.html#a3cf99fc76547e0155a2d5d1608c22de7">set</a>(<span class="keyword">const</span> T& val) {</div>
<div class="line"><a name="l00236"></a><span class="lineno"> 236</span>  <a class="code" href="classCgu_1_1Thread_1_1Mutex_1_1Lock.html" title="A scoped locking class for exception safe Mutex locking. ">Thread::Mutex::Lock</a> lock{mutex};</div>
<div class="line"><a name="l00237"></a><span class="lineno"> 237</span>  <span class="keywordflow">if</span> (!done) {</div>
<div class="line"><a name="l00238"></a><span class="lineno"> 238</span>  res = val;</div>
<div class="line"><a name="l00239"></a><span class="lineno"> 239</span>  done = <span class="keyword">true</span>;</div>
<div class="line"><a name="l00240"></a><span class="lineno"> 240</span>  cond.<a class="code" href="classCgu_1_1Thread_1_1Cond.html#a88f86501defc0d4b648c11c0e9b7b8cf">broadcast</a>();</div>
<div class="line"><a name="l00241"></a><span class="lineno"> 241</span>  <span class="keywordflow">return</span> <span class="keyword">true</span>;</div>
<div class="line"><a name="l00242"></a><span class="lineno"> 242</span>  }</div>
<div class="line"><a name="l00243"></a><span class="lineno"> 243</span>  <span class="keywordflow">return</span> <span class="keyword">false</span>;</div>
<div class="line"><a name="l00244"></a><span class="lineno"> 244</span>  }</div>
<div class="line"><a name="l00245"></a><span class="lineno"> 245</span> <span class="comment"></span></div>
<div class="line"><a name="l00246"></a><span class="lineno"> 246</span> <span class="comment"> /**</span></div>
<div class="line"><a name="l00247"></a><span class="lineno"> 247</span> <span class="comment"> * This method sets the value represented by the AsyncResult object,</span></div>
<div class="line"><a name="l00248"></a><span class="lineno"> 248</span> <span class="comment"> * provided that set() has not previously been called and</span></div>
<div class="line"><a name="l00249"></a><span class="lineno"> 249</span> <span class="comment"> * set_error() has not previously been called with a value other</span></div>
<div class="line"><a name="l00250"></a><span class="lineno"> 250</span> <span class="comment"> * than 0. If set() has previously been called or set_error()</span></div>
<div class="line"><a name="l00251"></a><span class="lineno"> 251</span> <span class="comment"> * called with a value other than 0 (so that is_done() will return</span></div>
<div class="line"><a name="l00252"></a><span class="lineno"> 252</span> <span class="comment"> * true) this method does nothing. It is thread safe. It is not a</span></div>
<div class="line"><a name="l00253"></a><span class="lineno"> 253</span> <span class="comment"> * cancellation point. It will not throw unless the copy or move</span></div>
<div class="line"><a name="l00254"></a><span class="lineno"> 254</span> <span class="comment"> * assignment operator of the value type throws.</span></div>
<div class="line"><a name="l00255"></a><span class="lineno"> 255</span> <span class="comment"> * @param val The value which this object is to represent and which</span></div>
<div class="line"><a name="l00256"></a><span class="lineno"> 256</span> <span class="comment"> * calls to get() or a call to move_get() will return. Any thread</span></div>
<div class="line"><a name="l00257"></a><span class="lineno"> 257</span> <span class="comment"> * waiting on get() or move_get() will unblock, and any subsequent</span></div>
<div class="line"><a name="l00258"></a><span class="lineno"> 258</span> <span class="comment"> * calls to is_done() will return true.</span></div>
<div class="line"><a name="l00259"></a><span class="lineno"> 259</span> <span class="comment"> * @return true if the call to this method is effective because</span></div>
<div class="line"><a name="l00260"></a><span class="lineno"> 260</span> <span class="comment"> * set() has not previously been called and set_error() has not</span></div>
<div class="line"><a name="l00261"></a><span class="lineno"> 261</span> <span class="comment"> * previously been called with a value other than 0, otherwise</span></div>
<div class="line"><a name="l00262"></a><span class="lineno"> 262</span> <span class="comment"> * false.</span></div>
<div class="line"><a name="l00263"></a><span class="lineno"> 263</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00264"></a><span class="lineno"> 264</span> <span class="comment"> * Since 2.0.8</span></div>
<div class="line"><a name="l00265"></a><span class="lineno"> 265</span> <span class="comment"> */</span></div>
<div class="line"><a name="l00266"></a><span class="lineno"><a class="code" href="classCgu_1_1AsyncResult.html#ad47b2edf239d0153a84f590798f8ae62"> 266</a></span>  <span class="keywordtype">bool</span> <a class="code" href="classCgu_1_1AsyncResult.html#ad47b2edf239d0153a84f590798f8ae62">set</a>(T&& val) {</div>
<div class="line"><a name="l00267"></a><span class="lineno"> 267</span>  <a class="code" href="classCgu_1_1Thread_1_1Mutex_1_1Lock.html" title="A scoped locking class for exception safe Mutex locking. ">Thread::Mutex::Lock</a> lock{mutex};</div>
<div class="line"><a name="l00268"></a><span class="lineno"> 268</span>  <span class="keywordflow">if</span> (!done) {</div>
<div class="line"><a name="l00269"></a><span class="lineno"> 269</span>  res = std::move(val);</div>
<div class="line"><a name="l00270"></a><span class="lineno"> 270</span>  done = <span class="keyword">true</span>;</div>
<div class="line"><a name="l00271"></a><span class="lineno"> 271</span>  cond.<a class="code" href="classCgu_1_1Thread_1_1Cond.html#a88f86501defc0d4b648c11c0e9b7b8cf">broadcast</a>();</div>
<div class="line"><a name="l00272"></a><span class="lineno"> 272</span>  <span class="keywordflow">return</span> <span class="keyword">true</span>;</div>
<div class="line"><a name="l00273"></a><span class="lineno"> 273</span>  }</div>
<div class="line"><a name="l00274"></a><span class="lineno"> 274</span>  <span class="keywordflow">return</span> <span class="keyword">false</span>;</div>
<div class="line"><a name="l00275"></a><span class="lineno"> 275</span>  }</div>
<div class="line"><a name="l00276"></a><span class="lineno"> 276</span> <span class="comment"></span></div>
<div class="line"><a name="l00277"></a><span class="lineno"> 277</span> <span class="comment"> /**</span></div>
<div class="line"><a name="l00278"></a><span class="lineno"> 278</span> <span class="comment"> * This method gets the stored value represented by the AsyncResult</span></div>
<div class="line"><a name="l00279"></a><span class="lineno"> 279</span> <span class="comment"> * object. It is thread safe. It is a cancellation point if it</span></div>
<div class="line"><a name="l00280"></a><span class="lineno"> 280</span> <span class="comment"> * blocks, and is cancellation safe if the stack unwinds on</span></div>
<div class="line"><a name="l00281"></a><span class="lineno"> 281</span> <span class="comment"> * cancellation. Any number of threads may call this method and</span></div>
<div class="line"><a name="l00282"></a><span class="lineno"> 282</span> <span class="comment"> * block on it. It will not throw unless the copy constructor of</span></div>
<div class="line"><a name="l00283"></a><span class="lineno"> 283</span> <span class="comment"> * the return type throws. It is strongly exception safe.</span></div>
<div class="line"><a name="l00284"></a><span class="lineno"> 284</span> <span class="comment"> * @return the value represented by this object as set by a call to</span></div>
<div class="line"><a name="l00285"></a><span class="lineno"> 285</span> <span class="comment"> * set(). If no such value has been set (and no error has been set)</span></div>
<div class="line"><a name="l00286"></a><span class="lineno"> 286</span> <span class="comment"> * so that is_done() will return false, this method will block until</span></div>
<div class="line"><a name="l00287"></a><span class="lineno"> 287</span> <span class="comment"> * either a value or an error has been set. If an error has been</span></div>
<div class="line"><a name="l00288"></a><span class="lineno"> 288</span> <span class="comment"> * set, this method will return a default constructed object of the</span></div>
<div class="line"><a name="l00289"></a><span class="lineno"> 289</span> <span class="comment"> * template type (and the error can be obtained with get_error()).</span></div>
<div class="line"><a name="l00290"></a><span class="lineno"> 290</span> <span class="comment"> * @note Question: Couldn't this method return the stored value by</span></div>
<div class="line"><a name="l00291"></a><span class="lineno"> 291</span> <span class="comment"> * lvalue reference to const? Answer: It could. However, because</span></div>
<div class="line"><a name="l00292"></a><span class="lineno"> 292</span> <span class="comment"> * of return value optimization, which will be implemented by any</span></div>
<div class="line"><a name="l00293"></a><span class="lineno"> 293</span> <span class="comment"> * compiler capable of compiling this library, no advantage would be</span></div>
<div class="line"><a name="l00294"></a><span class="lineno"> 294</span> <span class="comment"> * gained by doing so when initializing a local variable with the</span></div>
<div class="line"><a name="l00295"></a><span class="lineno"> 295</span> <span class="comment"> * return value of this method (the copy constructor will only be</span></div>
<div class="line"><a name="l00296"></a><span class="lineno"> 296</span> <span class="comment"> * called once whether returning by value or const reference). The</span></div>
<div class="line"><a name="l00297"></a><span class="lineno"> 297</span> <span class="comment"> * advantage of returning by value is that the call to the copy</span></div>
<div class="line"><a name="l00298"></a><span class="lineno"> 298</span> <span class="comment"> * constructor is forced to be within the AsyncResult object's</span></div>
<div class="line"><a name="l00299"></a><span class="lineno"> 299</span> <span class="comment"> * mutex, so different threads' calls to the copy constructor are</span></div>
<div class="line"><a name="l00300"></a><span class="lineno"> 300</span> <span class="comment"> * serialized, and also with blocked cancellation, so this method is</span></div>
<div class="line"><a name="l00301"></a><span class="lineno"> 301</span> <span class="comment"> * cancellation safe. All calls to this method by different threads</span></div>
<div class="line"><a name="l00302"></a><span class="lineno"> 302</span> <span class="comment"> * are therefore isolated and we do not have to worry about the</span></div>
<div class="line"><a name="l00303"></a><span class="lineno"> 303</span> <span class="comment"> * thread safety of direct access to the stored value via its const</span></div>
<div class="line"><a name="l00304"></a><span class="lineno"> 304</span> <span class="comment"> * methods outside the mutex (which would not be thread safe if the</span></div>
<div class="line"><a name="l00305"></a><span class="lineno"> 305</span> <span class="comment"> * stored value has data members declared mutable) nor about the</span></div>
<div class="line"><a name="l00306"></a><span class="lineno"> 306</span> <span class="comment"> * cancellation safety of the copy constructor. Of course, for</span></div>
<div class="line"><a name="l00307"></a><span class="lineno"> 307</span> <span class="comment"> * objects which do not have mutable data, a hit arises by returning</span></div>
<div class="line"><a name="l00308"></a><span class="lineno"> 308</span> <span class="comment"> * by value in cases where it is not intended to initialize a local</span></div>
<div class="line"><a name="l00309"></a><span class="lineno"> 309</span> <span class="comment"> * variable at all nor to cancel a thread: where, say, only const</span></div>
<div class="line"><a name="l00310"></a><span class="lineno"> 310</span> <span class="comment"> * methods are to be called on the return value (which could be done</span></div>
<div class="line"><a name="l00311"></a><span class="lineno"> 311</span> <span class="comment"> * directly if this method returned by const reference). However,</span></div>
<div class="line"><a name="l00312"></a><span class="lineno"> 312</span> <span class="comment"> * in many use cases this will be mitigated by the move_get()</span></div>
<div class="line"><a name="l00313"></a><span class="lineno"> 313</span> <span class="comment"> * method.</span></div>
<div class="line"><a name="l00314"></a><span class="lineno"> 314</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00315"></a><span class="lineno"> 315</span> <span class="comment"> * Since 2.0.8</span></div>
<div class="line"><a name="l00316"></a><span class="lineno"> 316</span> <span class="comment"> */</span></div>
<div class="line"><a name="l00317"></a><span class="lineno"><a class="code" href="classCgu_1_1AsyncResult.html#a8cf43f604c42a48d1a6fa61640c06637"> 317</a></span>  T <span class="keyword">get</span>() <span class="keyword">const</span> {</div>
<div class="line"><a name="l00318"></a><span class="lineno"> 318</span>  <a class="code" href="classCgu_1_1Thread_1_1Mutex_1_1Lock.html" title="A scoped locking class for exception safe Mutex locking. ">Thread::Mutex::Lock</a> lock{mutex};</div>
<div class="line"><a name="l00319"></a><span class="lineno"> 319</span>  <span class="keywordflow">while</span> (!done) cond.<a class="code" href="classCgu_1_1Thread_1_1Cond.html#a5eda52c227552555102bb45010a8f6c9">wait</a>(mutex);</div>
<div class="line"><a name="l00320"></a><span class="lineno"> 320</span>  <a class="code" href="classCgu_1_1Thread_1_1CancelBlock.html" title="A class enabling the cancellation state of a thread to be controlled. ">Thread::CancelBlock</a> b;</div>
<div class="line"><a name="l00321"></a><span class="lineno"> 321</span>  <span class="keywordflow">return</span> res;</div>
<div class="line"><a name="l00322"></a><span class="lineno"> 322</span>  }</div>
<div class="line"><a name="l00323"></a><span class="lineno"> 323</span> <span class="comment"></span></div>
<div class="line"><a name="l00324"></a><span class="lineno"> 324</span> <span class="comment"> /**</span></div>
<div class="line"><a name="l00325"></a><span class="lineno"> 325</span> <span class="comment"> * This method gets the stored value represented by the AsyncResult</span></div>
<div class="line"><a name="l00326"></a><span class="lineno"> 326</span> <span class="comment"> * object by a move operation, if the type of that value implements</span></div>
<div class="line"><a name="l00327"></a><span class="lineno"> 327</span> <span class="comment"> * a move constructor (otherwise this method does the same as the</span></div>
<div class="line"><a name="l00328"></a><span class="lineno"> 328</span> <span class="comment"> * get() method). It is provided as an option for cases where a</span></div>
<div class="line"><a name="l00329"></a><span class="lineno"> 329</span> <span class="comment"> * move is required for efficiency reasons, but although it may be</span></div>
<div class="line"><a name="l00330"></a><span class="lineno"> 330</span> <span class="comment"> * called by any thread, a move operation may normally only be made</span></div>
<div class="line"><a name="l00331"></a><span class="lineno"> 331</span> <span class="comment"> * once (except where the return type has been designed to be moved</span></div>
<div class="line"><a name="l00332"></a><span class="lineno"> 332</span> <span class="comment"> * more than once for the limited purpose of inspecting a flag</span></div>
<div class="line"><a name="l00333"></a><span class="lineno"> 333</span> <span class="comment"> * indicating whether its value is valid or not). If this method is</span></div>
<div class="line"><a name="l00334"></a><span class="lineno"> 334</span> <span class="comment"> * to be called then no calls to get() by another thread should</span></div>
<div class="line"><a name="l00335"></a><span class="lineno"> 335</span> <span class="comment"> * normally be made. This method is a cancellation point if it</span></div>
<div class="line"><a name="l00336"></a><span class="lineno"> 336</span> <span class="comment"> * blocks, and is cancellation safe if the stack unwinds on</span></div>
<div class="line"><a name="l00337"></a><span class="lineno"> 337</span> <span class="comment"> * cancellation. It will not throw unless the copy or move</span></div>
<div class="line"><a name="l00338"></a><span class="lineno"> 338</span> <span class="comment"> * constructor of the return type throws. It is only exception safe</span></div>
<div class="line"><a name="l00339"></a><span class="lineno"> 339</span> <span class="comment"> * if the return type's move constructor is exception safe.</span></div>
<div class="line"><a name="l00340"></a><span class="lineno"> 340</span> <span class="comment"> * @return The value represented by this object as set by a call to</span></div>
<div class="line"><a name="l00341"></a><span class="lineno"> 341</span> <span class="comment"> * set(). If no such value has been set (and no error has been set)</span></div>
<div class="line"><a name="l00342"></a><span class="lineno"> 342</span> <span class="comment"> * so that is_done() will return false, this method will block until</span></div>
<div class="line"><a name="l00343"></a><span class="lineno"> 343</span> <span class="comment"> * either a value or an error has been set. If an error has been</span></div>
<div class="line"><a name="l00344"></a><span class="lineno"> 344</span> <span class="comment"> * set, until a move operation has been carried out this method will</span></div>
<div class="line"><a name="l00345"></a><span class="lineno"> 345</span> <span class="comment"> * return a default constructed object of the template type (and the</span></div>
<div class="line"><a name="l00346"></a><span class="lineno"> 346</span> <span class="comment"> * error can be obtained with get_error()).</span></div>
<div class="line"><a name="l00347"></a><span class="lineno"> 347</span> <span class="comment"> * @note Question: Couldn't this method return the stored value by</span></div>
<div class="line"><a name="l00348"></a><span class="lineno"> 348</span> <span class="comment"> * rvalue reference? Answer: It could. However, because of return</span></div>
<div class="line"><a name="l00349"></a><span class="lineno"> 349</span> <span class="comment"> * value optimization, which will be implemented by any compiler</span></div>
<div class="line"><a name="l00350"></a><span class="lineno"> 350</span> <span class="comment"> * capable of compiling this library, no advantage would be gained</span></div>
<div class="line"><a name="l00351"></a><span class="lineno"> 351</span> <span class="comment"> * by doing so when initializing a local variable with the return</span></div>
<div class="line"><a name="l00352"></a><span class="lineno"> 352</span> <span class="comment"> * value of this method (the move constructor will only be called</span></div>
<div class="line"><a name="l00353"></a><span class="lineno"> 353</span> <span class="comment"> * once, and no call will be made to the copy constructor, whether</span></div>
<div class="line"><a name="l00354"></a><span class="lineno"> 354</span> <span class="comment"> * returning by value or rvalue reference). The advantage of</span></div>
<div class="line"><a name="l00355"></a><span class="lineno"> 355</span> <span class="comment"> * returning by value is that the call to the move constructor is</span></div>
<div class="line"><a name="l00356"></a><span class="lineno"> 356</span> <span class="comment"> * forced to be within the AsyncResult object's mutex, so different</span></div>
<div class="line"><a name="l00357"></a><span class="lineno"> 357</span> <span class="comment"> * threads' calls to the move constructor are serialized, and also</span></div>
<div class="line"><a name="l00358"></a><span class="lineno"> 358</span> <span class="comment"> * with blocked cancellation, so this method is cancellation safe.</span></div>
<div class="line"><a name="l00359"></a><span class="lineno"> 359</span> <span class="comment"> * All calls to this method by different threads are therefore</span></div>
<div class="line"><a name="l00360"></a><span class="lineno"> 360</span> <span class="comment"> * isolated and we do not have to worry about the thread safety of</span></div>
<div class="line"><a name="l00361"></a><span class="lineno"> 361</span> <span class="comment"> * the mutating first call to this method, nor about direct access</span></div>
<div class="line"><a name="l00362"></a><span class="lineno"> 362</span> <span class="comment"> * to the stored value via a rvalue reference outside the mutex nor</span></div>
<div class="line"><a name="l00363"></a><span class="lineno"> 363</span> <span class="comment"> * the cancellation safety of the move constructor.</span></div>
<div class="line"><a name="l00364"></a><span class="lineno"> 364</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00365"></a><span class="lineno"> 365</span> <span class="comment"> * Since 2.0.11</span></div>
<div class="line"><a name="l00366"></a><span class="lineno"> 366</span> <span class="comment"> */</span></div>
<div class="line"><a name="l00367"></a><span class="lineno"><a class="code" href="classCgu_1_1AsyncResult.html#acc4835c1722a3d5ce0da50ddd91103d1"> 367</a></span>  T <a class="code" href="classCgu_1_1AsyncResult.html#acc4835c1722a3d5ce0da50ddd91103d1">move_get</a>() {</div>
<div class="line"><a name="l00368"></a><span class="lineno"> 368</span>  <a class="code" href="classCgu_1_1Thread_1_1Mutex_1_1Lock.html" title="A scoped locking class for exception safe Mutex locking. ">Thread::Mutex::Lock</a> lock{mutex};</div>
<div class="line"><a name="l00369"></a><span class="lineno"> 369</span>  <span class="keywordflow">while</span> (!done) cond.<a class="code" href="classCgu_1_1Thread_1_1Cond.html#a5eda52c227552555102bb45010a8f6c9">wait</a>(mutex);</div>
<div class="line"><a name="l00370"></a><span class="lineno"> 370</span>  <a class="code" href="classCgu_1_1Thread_1_1CancelBlock.html" title="A class enabling the cancellation state of a thread to be controlled. ">Thread::CancelBlock</a> b;</div>
<div class="line"><a name="l00371"></a><span class="lineno"> 371</span>  <span class="keywordflow">return</span> std::move(res);</div>
<div class="line"><a name="l00372"></a><span class="lineno"> 372</span>  }</div>
<div class="line"><a name="l00373"></a><span class="lineno"> 373</span> <span class="comment"></span></div>
<div class="line"><a name="l00374"></a><span class="lineno"> 374</span> <span class="comment"> /**</span></div>
<div class="line"><a name="l00375"></a><span class="lineno"> 375</span> <span class="comment"> * This method sets an error if called with a value other than 0,</span></div>
<div class="line"><a name="l00376"></a><span class="lineno"> 376</span> <span class="comment"> * provided that set() has not previously been called and this</span></div>
<div class="line"><a name="l00377"></a><span class="lineno"> 377</span> <span class="comment"> * method has not previously been called with a value other than 0.</span></div>
<div class="line"><a name="l00378"></a><span class="lineno"> 378</span> <span class="comment"> * If set() has been called or this method previously called with a</span></div>
<div class="line"><a name="l00379"></a><span class="lineno"> 379</span> <span class="comment"> * value other than 0 (so that is_done() will return true), this</span></div>
<div class="line"><a name="l00380"></a><span class="lineno"> 380</span> <span class="comment"> * method does nothing. This method is thread safe. It is not a</span></div>
<div class="line"><a name="l00381"></a><span class="lineno"> 381</span> <span class="comment"> * cancellation point. It will not throw.</span></div>
<div class="line"><a name="l00382"></a><span class="lineno"> 382</span> <span class="comment"> * @param err The value which subsequent calls to get_error() will</span></div>
<div class="line"><a name="l00383"></a><span class="lineno"> 383</span> <span class="comment"> * report. If the value of err is 0, or if this method has been</span></div>
<div class="line"><a name="l00384"></a><span class="lineno"> 384</span> <span class="comment"> * called with a value other than 0 or set() has previously been</span></div>
<div class="line"><a name="l00385"></a><span class="lineno"> 385</span> <span class="comment"> * called, this method will do nothing. Otherwise, any thread</span></div>
<div class="line"><a name="l00386"></a><span class="lineno"> 386</span> <span class="comment"> * waiting on get() or move_get() will unblock (they will return a</span></div>
<div class="line"><a name="l00387"></a><span class="lineno"> 387</span> <span class="comment"> * default constructed object of the template type), and any</span></div>
<div class="line"><a name="l00388"></a><span class="lineno"> 388</span> <span class="comment"> * subsequent calls to is_done() will return true.</span></div>
<div class="line"><a name="l00389"></a><span class="lineno"> 389</span> <span class="comment"> * @return true if the call to this method is effective because the</span></div>
<div class="line"><a name="l00390"></a><span class="lineno"> 390</span> <span class="comment"> * error value passed is not 0, set() has not previously been called</span></div>
<div class="line"><a name="l00391"></a><span class="lineno"> 391</span> <span class="comment"> * and this method has not previously been called with a value other</span></div>
<div class="line"><a name="l00392"></a><span class="lineno"> 392</span> <span class="comment"> * than 0, otherwise false.</span></div>
<div class="line"><a name="l00393"></a><span class="lineno"> 393</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00394"></a><span class="lineno"> 394</span> <span class="comment"> * Since 2.0.8</span></div>
<div class="line"><a name="l00395"></a><span class="lineno"> 395</span> <span class="comment"> */</span></div>
<div class="line"><a name="l00396"></a><span class="lineno"><a class="code" href="classCgu_1_1AsyncResult.html#aabb4ca29e0367f8e279c8b20be3221e0"> 396</a></span>  <span class="keywordtype">bool</span> <a class="code" href="classCgu_1_1AsyncResult.html#aabb4ca29e0367f8e279c8b20be3221e0">set_error</a>(<span class="keywordtype">int</span> err = -1) {</div>
<div class="line"><a name="l00397"></a><span class="lineno"> 397</span>  <a class="code" href="classCgu_1_1Thread_1_1Mutex_1_1Lock.html" title="A scoped locking class for exception safe Mutex locking. ">Thread::Mutex::Lock</a> lock{mutex};</div>
<div class="line"><a name="l00398"></a><span class="lineno"> 398</span>  <span class="keywordflow">if</span> (err && !done) {</div>
<div class="line"><a name="l00399"></a><span class="lineno"> 399</span>  error = err;</div>
<div class="line"><a name="l00400"></a><span class="lineno"> 400</span>  done = <span class="keyword">true</span>;</div>
<div class="line"><a name="l00401"></a><span class="lineno"> 401</span>  cond.<a class="code" href="classCgu_1_1Thread_1_1Cond.html#a88f86501defc0d4b648c11c0e9b7b8cf">broadcast</a>();</div>
<div class="line"><a name="l00402"></a><span class="lineno"> 402</span>  <span class="keywordflow">return</span> <span class="keyword">true</span>;</div>
<div class="line"><a name="l00403"></a><span class="lineno"> 403</span>  }</div>
<div class="line"><a name="l00404"></a><span class="lineno"> 404</span>  <span class="keywordflow">return</span> <span class="keyword">false</span>;</div>
<div class="line"><a name="l00405"></a><span class="lineno"> 405</span>  }</div>
<div class="line"><a name="l00406"></a><span class="lineno"> 406</span> <span class="comment"></span></div>
<div class="line"><a name="l00407"></a><span class="lineno"> 407</span> <span class="comment"> /**</span></div>
<div class="line"><a name="l00408"></a><span class="lineno"> 408</span> <span class="comment"> * This method is thread safe. It is not a cancellation point. It</span></div>
<div class="line"><a name="l00409"></a><span class="lineno"> 409</span> <span class="comment"> * will not throw.</span></div>
<div class="line"><a name="l00410"></a><span class="lineno"> 410</span> <span class="comment"> * @return the error value set by a call to set_error(), or 0 if no</span></div>
<div class="line"><a name="l00411"></a><span class="lineno"> 411</span> <span class="comment"> * error has been set.</span></div>
<div class="line"><a name="l00412"></a><span class="lineno"> 412</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00413"></a><span class="lineno"> 413</span> <span class="comment"> * Since 2.0.8</span></div>
<div class="line"><a name="l00414"></a><span class="lineno"> 414</span> <span class="comment"> */</span></div>
<div class="line"><a name="l00415"></a><span class="lineno"><a class="code" href="classCgu_1_1AsyncResult.html#af2c45b2b9b16319c10d35de7a4061727"> 415</a></span>  <span class="keywordtype">int</span> <a class="code" href="classCgu_1_1AsyncResult.html#af2c45b2b9b16319c10d35de7a4061727">get_error</a>()<span class="keyword"> const </span>{</div>
<div class="line"><a name="l00416"></a><span class="lineno"> 416</span>  <a class="code" href="classCgu_1_1Thread_1_1Mutex_1_1Lock.html" title="A scoped locking class for exception safe Mutex locking. ">Thread::Mutex::Lock</a> lock{mutex};</div>
<div class="line"><a name="l00417"></a><span class="lineno"> 417</span>  <span class="keywordflow">return</span> error;</div>
<div class="line"><a name="l00418"></a><span class="lineno"> 418</span>  }</div>
<div class="line"><a name="l00419"></a><span class="lineno"> 419</span> <span class="comment"></span></div>
<div class="line"><a name="l00420"></a><span class="lineno"> 420</span> <span class="comment"> /**</span></div>
<div class="line"><a name="l00421"></a><span class="lineno"> 421</span> <span class="comment"> * This method is thread safe. It is not a cancellation point. It</span></div>
<div class="line"><a name="l00422"></a><span class="lineno"> 422</span> <span class="comment"> * will not throw.</span></div>
<div class="line"><a name="l00423"></a><span class="lineno"> 423</span> <span class="comment"> * @return true if set() has been called, or set_error() has been</span></div>
<div class="line"><a name="l00424"></a><span class="lineno"> 424</span> <span class="comment"> * called with a value other than 0, otherwise false.</span></div>
<div class="line"><a name="l00425"></a><span class="lineno"> 425</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00426"></a><span class="lineno"> 426</span> <span class="comment"> * Since 2.0.8</span></div>
<div class="line"><a name="l00427"></a><span class="lineno"> 427</span> <span class="comment"> */</span></div>
<div class="line"><a name="l00428"></a><span class="lineno"><a class="code" href="classCgu_1_1AsyncResult.html#af5f425d599a8a4343d1642b65f5a346e"> 428</a></span>  <span class="keywordtype">bool</span> <a class="code" href="classCgu_1_1AsyncResult.html#af5f425d599a8a4343d1642b65f5a346e">is_done</a>()<span class="keyword"> const </span>{</div>
<div class="line"><a name="l00429"></a><span class="lineno"> 429</span>  <a class="code" href="classCgu_1_1Thread_1_1Mutex_1_1Lock.html" title="A scoped locking class for exception safe Mutex locking. ">Thread::Mutex::Lock</a> lock{mutex};</div>
<div class="line"><a name="l00430"></a><span class="lineno"> 430</span>  <span class="keywordflow">return</span> done;</div>
<div class="line"><a name="l00431"></a><span class="lineno"> 431</span>  }</div>
<div class="line"><a name="l00432"></a><span class="lineno"> 432</span> </div>
<div class="line"><a name="l00433"></a><span class="lineno"> 433</span> <span class="comment">/* Only has effect if --with-glib-memory-slices-compat or</span></div>
<div class="line"><a name="l00434"></a><span class="lineno"> 434</span> <span class="comment"> * --with-glib-memory-slices-no-compat option picked */</span></div>
<div class="line"><a name="l00435"></a><span class="lineno"> 435</span>  <a class="code" href="cgu__config_8h.html#a13241741f6a47356f61508faea37c35a">CGU_GLIB_MEMORY_SLICES_FUNCS</a></div>
<div class="line"><a name="l00436"></a><span class="lineno"> 436</span> };</div>
<div class="line"><a name="l00437"></a><span class="lineno"> 437</span> </div>
<div class="line"><a name="l00438"></a><span class="lineno"> 438</span> } <span class="comment">// namespace Cgu</span></div>
<div class="line"><a name="l00439"></a><span class="lineno"> 439</span> </div>
<div class="line"><a name="l00440"></a><span class="lineno"> 440</span> <span class="preprocessor">#endif</span></div>
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