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<a href="parallel_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) 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> </div>
<div class="line"><a name="l00039"></a><span class="lineno"> 39</span> <span class="preprocessor">#ifndef CGU_PARALLEL_H</span></div>
<div class="line"><a name="l00040"></a><span class="lineno"> 40</span> <span class="preprocessor"></span><span class="preprocessor">#define CGU_PARALLEL_H</span></div>
<div class="line"><a name="l00041"></a><span class="lineno"> 41</span> <span class="preprocessor"></span></div>
<div class="line"><a name="l00042"></a><span class="lineno"> 42</span> <span class="preprocessor">#include <utility></span> <span class="comment">// for std::move, std::forward and std::pair</span></div>
<div class="line"><a name="l00043"></a><span class="lineno"> 43</span> <span class="preprocessor">#include <memory></span> <span class="comment">// for std::unique_ptr</span></div>
<div class="line"><a name="l00044"></a><span class="lineno"> 44</span> <span class="preprocessor">#include <iterator></span> <span class="comment">// for std::iterator_traits and std::distance</span></div>
<div class="line"><a name="l00045"></a><span class="lineno"> 45</span> <span class="preprocessor">#include <exception></span> <span class="comment">// for std::exception</span></div>
<div class="line"><a name="l00046"></a><span class="lineno"> 46</span> <span class="preprocessor">#include <functional></span> <span class="comment">// for std::bind</span></div>
<div class="line"><a name="l00047"></a><span class="lineno"> 47</span> <span class="preprocessor">#include <type_traits></span> <span class="comment">// for std::remove_reference and std::remove_const</span></div>
<div class="line"><a name="l00048"></a><span class="lineno"> 48</span> <span class="preprocessor">#include <limits></span> <span class="comment">// for std::numeric_limits</span></div>
<div class="line"><a name="l00049"></a><span class="lineno"> 49</span> <span class="preprocessor">#include <algorithm></span> <span class="comment">// for std::min</span></div>
<div class="line"><a name="l00050"></a><span class="lineno"> 50</span> <span class="preprocessor">#include <tuple></span></div>
<div class="line"><a name="l00051"></a><span class="lineno"> 51</span> </div>
<div class="line"><a name="l00052"></a><span class="lineno"> 52</span> <span class="preprocessor">#include <<a class="code" href="callback_8h.html" title="This file provides classes for type erasure. ">c++-gtk-utils/callback.h</a>></span></div>
<div class="line"><a name="l00053"></a><span class="lineno"> 53</span> <span class="preprocessor">#include <<a class="code" href="task__manager_8h.html">c++-gtk-utils/task_manager.h</a>></span></div>
<div class="line"><a name="l00054"></a><span class="lineno"> 54</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="l00055"></a><span class="lineno"> 55</span> </div>
<div class="line"><a name="l00056"></a><span class="lineno"> 56</span> <span class="keyword">namespace </span>Cgu {</div>
<div class="line"><a name="l00057"></a><span class="lineno"> 57</span> </div>
<div class="line"><a name="l00058"></a><span class="lineno"> 58</span> <span class="keyword">namespace </span>Thread {</div>
<div class="line"><a name="l00059"></a><span class="lineno"> 59</span> </div>
<div class="line"><a name="l00060"></a><span class="lineno"><a class="code" href="structCgu_1_1Thread_1_1ParallelError.html"> 60</a></span> <span class="keyword">struct </span><a class="code" href="structCgu_1_1Thread_1_1ParallelError.html">ParallelError</a>: <span class="keyword">public</span> std::exception {</div>
<div class="line"><a name="l00061"></a><span class="lineno"><a class="code" href="structCgu_1_1Thread_1_1ParallelError.html#ad435c9e3d7957a3b0c972bf3c103d7fc"> 61</a></span>  <span class="keyword">virtual</span> <span class="keyword">const</span> <span class="keywordtype">char</span>* <a class="code" href="structCgu_1_1Thread_1_1ParallelError.html#ad435c9e3d7957a3b0c972bf3c103d7fc">what</a>() <span class="keyword">const</span> throw() {<span class="keywordflow">return</span> <span class="stringliteral">"ParallelError\n"</span>;}</div>
<div class="line"><a name="l00062"></a><span class="lineno"> 62</span> };</div>
<div class="line"><a name="l00063"></a><span class="lineno"> 63</span> </div>
<div class="line"><a name="l00064"></a><span class="lineno"> 64</span> <span class="preprocessor">#ifndef DOXYGEN_PARSING</span></div>
<div class="line"><a name="l00065"></a><span class="lineno"> 65</span> <span class="preprocessor"></span></div>
<div class="line"><a name="l00066"></a><span class="lineno"> 66</span> <span class="comment">// in version 2.2.2, this was the ParallelHelper namespace. Because</span></div>
<div class="line"><a name="l00067"></a><span class="lineno"> 67</span> <span class="comment">// the meaning of the DiffType* argument of these functions has</span></div>
<div class="line"><a name="l00068"></a><span class="lineno"> 68</span> <span class="comment">// changed in version 2.2.3 (it is incremented rather than</span></div>
<div class="line"><a name="l00069"></a><span class="lineno"> 69</span> <span class="comment">// decremented), this is now the ParallelHelper2 namespace so that no</span></div>
<div class="line"><a name="l00070"></a><span class="lineno"> 70</span> <span class="comment">// ODR issues arise on library linking with old binaries</span></div>
<div class="line"><a name="l00071"></a><span class="lineno"> 71</span> <span class="keyword">namespace </span>ParallelHelper2 {</div>
<div class="line"><a name="l00072"></a><span class="lineno"> 72</span> </div>
<div class="line"><a name="l00073"></a><span class="lineno"> 73</span> <span class="keyword">template</span> <<span class="keyword">class</span> ArgType, <span class="keyword">class</span> DiffType, <span class="keyword">class</span> Iterator></div>
<div class="line"><a name="l00074"></a><span class="lineno"> 74</span> <span class="keywordtype">void</span> for_each_cb_func(<span class="keyword">const</span> <a class="code" href="classCgu_1_1Callback_1_1SafeFunctorArg.html" title="Functor class holding a Callback::CallbackArg object, with thread-safe reference count. ">Cgu::Callback::SafeFunctorArg<ArgType&></a>& s_task,</div>
<div class="line"><a name="l00075"></a><span class="lineno"> 75</span>  Iterator iter,</div>
<div class="line"><a name="l00076"></a><span class="lineno"> 76</span>  Mutex* m, Cond* cond,</div>
<div class="line"><a name="l00077"></a><span class="lineno"> 77</span>  DiffType* done_count) {</div>
<div class="line"><a name="l00078"></a><span class="lineno"> 78</span>  s_task(*iter);</div>
<div class="line"><a name="l00079"></a><span class="lineno"> 79</span>  Mutex::Lock l{*m};</div>
<div class="line"><a name="l00080"></a><span class="lineno"> 80</span>  ++*done_count;</div>
<div class="line"><a name="l00081"></a><span class="lineno"> 81</span>  cond->signal();</div>
<div class="line"><a name="l00082"></a><span class="lineno"> 82</span> }</div>
<div class="line"><a name="l00083"></a><span class="lineno"> 83</span> </div>
<div class="line"><a name="l00084"></a><span class="lineno"> 84</span> <span class="keyword">template</span> <<span class="keyword">class</span> FType, <span class="keyword">class</span> ArgType, <span class="keyword">class</span> DestType></div>
<div class="line"><a name="l00085"></a><span class="lineno"> 85</span> <span class="keywordtype">void</span> transform1_func(<span class="keyword">const</span> FType& func,</div>
<div class="line"><a name="l00086"></a><span class="lineno"> 86</span>  ArgType& arg,</div>
<div class="line"><a name="l00087"></a><span class="lineno"> 87</span>  DestType& res) {</div>
<div class="line"><a name="l00088"></a><span class="lineno"> 88</span>  res = func(arg);</div>
<div class="line"><a name="l00089"></a><span class="lineno"> 89</span> }</div>
<div class="line"><a name="l00090"></a><span class="lineno"> 90</span> </div>
<div class="line"><a name="l00091"></a><span class="lineno"> 91</span> </div>
<div class="line"><a name="l00092"></a><span class="lineno"> 92</span> <span class="keyword">template</span> <<span class="keyword">class</span> ArgType, <span class="keyword">class</span> DestType, <span class="keyword">class</span> DiffType, <span class="keyword">class</span> SourceIterator></div>
<div class="line"><a name="l00093"></a><span class="lineno"> 93</span> <span class="keywordtype">void</span> transform1_cb_func(<span class="keyword">const</span> <a class="code" href="classCgu_1_1Callback_1_1SafeFunctorArg.html" title="Functor class holding a Callback::CallbackArg object, with thread-safe reference count. ">Cgu::Callback::SafeFunctorArg<ArgType&, DestType&></a>& s_task,</div>
<div class="line"><a name="l00094"></a><span class="lineno"> 94</span>  SourceIterator source_iter,</div>
<div class="line"><a name="l00095"></a><span class="lineno"> 95</span>  Mutex* m, Cond* cond,</div>
<div class="line"><a name="l00096"></a><span class="lineno"> 96</span>  DiffType* done_count,</div>
<div class="line"><a name="l00097"></a><span class="lineno"> 97</span>  DestType* results,</div>
<div class="line"><a name="l00098"></a><span class="lineno"> 98</span>  DiffType index) {</div>
<div class="line"><a name="l00099"></a><span class="lineno"> 99</span>  DestType res;</div>
<div class="line"><a name="l00100"></a><span class="lineno"> 100</span>  s_task(*source_iter, res);</div>
<div class="line"><a name="l00101"></a><span class="lineno"> 101</span>  Mutex::Lock l{*m};</div>
<div class="line"><a name="l00102"></a><span class="lineno"> 102</span>  <span class="comment">// move to 'results' within the mutex because g++ <= 4.7 does not</span></div>
<div class="line"><a name="l00103"></a><span class="lineno"> 103</span>  <span class="comment">// correctly implement the C++11 memory model on some 64 bit</span></div>
<div class="line"><a name="l00104"></a><span class="lineno"> 104</span>  <span class="comment">// platforms (this is a slight pessimization for gcc >= 4.8)</span></div>
<div class="line"><a name="l00105"></a><span class="lineno"> 105</span>  results[index] = std::move(res);</div>
<div class="line"><a name="l00106"></a><span class="lineno"> 106</span>  ++*done_count;</div>
<div class="line"><a name="l00107"></a><span class="lineno"> 107</span>  cond->signal();</div>
<div class="line"><a name="l00108"></a><span class="lineno"> 108</span> }</div>
<div class="line"><a name="l00109"></a><span class="lineno"> 109</span> </div>
<div class="line"><a name="l00110"></a><span class="lineno"> 110</span> <span class="keyword">template</span> <<span class="keyword">class </span>FType, <span class="keyword">class </span>Arg1Type,</div>
<div class="line"><a name="l00111"></a><span class="lineno"> 111</span>  <span class="keyword">class </span>Arg2Type, <span class="keyword">class </span>DestType></div>
<div class="line"><a name="l00112"></a><span class="lineno"> 112</span> <span class="keywordtype">void</span> transform2_func(<span class="keyword">const</span> FType& func,</div>
<div class="line"><a name="l00113"></a><span class="lineno"> 113</span>  Arg1Type& arg1,</div>
<div class="line"><a name="l00114"></a><span class="lineno"> 114</span>  Arg2Type& arg2,</div>
<div class="line"><a name="l00115"></a><span class="lineno"> 115</span>  DestType& res) {</div>
<div class="line"><a name="l00116"></a><span class="lineno"> 116</span>  res = func(arg1, arg2);</div>
<div class="line"><a name="l00117"></a><span class="lineno"> 117</span> }</div>
<div class="line"><a name="l00118"></a><span class="lineno"> 118</span> </div>
<div class="line"><a name="l00119"></a><span class="lineno"> 119</span> </div>
<div class="line"><a name="l00120"></a><span class="lineno"> 120</span> <span class="keyword">template</span> <<span class="keyword">class </span>Arg1Type, <span class="keyword">class </span>Arg2Type, <span class="keyword">class </span>DestType,</div>
<div class="line"><a name="l00121"></a><span class="lineno"> 121</span>  <span class="keyword">class </span>DiffType, <span class="keyword">class </span>SourceIterator1, <span class="keyword">class </span>SourceIterator2></div>
<div class="line"><a name="l00122"></a><span class="lineno"> 122</span> <span class="keywordtype">void</span> transform2_cb_func(<span class="keyword">const</span> <a class="code" href="classCgu_1_1Callback_1_1SafeFunctorArg.html" title="Functor class holding a Callback::CallbackArg object, with thread-safe reference count. ">Cgu::Callback::SafeFunctorArg<Arg1Type&, Arg2Type&, DestType&></a>& s_task,</div>
<div class="line"><a name="l00123"></a><span class="lineno"> 123</span>  SourceIterator1 source_iter1,</div>
<div class="line"><a name="l00124"></a><span class="lineno"> 124</span>  SourceIterator2 source_iter2,</div>
<div class="line"><a name="l00125"></a><span class="lineno"> 125</span>  Mutex* m, Cond* cond,</div>
<div class="line"><a name="l00126"></a><span class="lineno"> 126</span>  DiffType* done_count,</div>
<div class="line"><a name="l00127"></a><span class="lineno"> 127</span>  DestType* results,</div>
<div class="line"><a name="l00128"></a><span class="lineno"> 128</span>  DiffType index) {</div>
<div class="line"><a name="l00129"></a><span class="lineno"> 129</span>  DestType res;</div>
<div class="line"><a name="l00130"></a><span class="lineno"> 130</span>  s_task(*source_iter1, *source_iter2, res);</div>
<div class="line"><a name="l00131"></a><span class="lineno"> 131</span>  Mutex::Lock l{*m};</div>
<div class="line"><a name="l00132"></a><span class="lineno"> 132</span>  <span class="comment">// move to 'results' within the mutex because g++ <= 4.7 does not</span></div>
<div class="line"><a name="l00133"></a><span class="lineno"> 133</span>  <span class="comment">// correctly implement the C++11 memory model on some 64 bit</span></div>
<div class="line"><a name="l00134"></a><span class="lineno"> 134</span>  <span class="comment">// platforms (this is a slight pessimization for gcc >= 4.8)</span></div>
<div class="line"><a name="l00135"></a><span class="lineno"> 135</span>  results[index] = std::move(res);</div>
<div class="line"><a name="l00136"></a><span class="lineno"> 136</span>  ++*done_count;</div>
<div class="line"><a name="l00137"></a><span class="lineno"> 137</span>  cond->signal();</div>
<div class="line"><a name="l00138"></a><span class="lineno"> 138</span> }</div>
<div class="line"><a name="l00139"></a><span class="lineno"> 139</span> </div>
<div class="line"><a name="l00140"></a><span class="lineno"> 140</span> <span class="keyword">template</span> <<span class="keyword">class</span> DiffType></div>
<div class="line"><a name="l00141"></a><span class="lineno"> 141</span> <span class="keywordtype">void</span> fail_func(Mutex* m, Cond* cond,</div>
<div class="line"><a name="l00142"></a><span class="lineno"> 142</span>  <span class="keywordtype">bool</span>* error, DiffType* done_count) noexcept {</div>
<div class="line"><a name="l00143"></a><span class="lineno"> 143</span>  Mutex::Lock l{*m};</div>
<div class="line"><a name="l00144"></a><span class="lineno"> 144</span>  ++*done_count;</div>
<div class="line"><a name="l00145"></a><span class="lineno"> 145</span>  *error = <span class="keyword">true</span>;</div>
<div class="line"><a name="l00146"></a><span class="lineno"> 146</span>  cond->signal();</div>
<div class="line"><a name="l00147"></a><span class="lineno"> 147</span> }</div>
<div class="line"><a name="l00148"></a><span class="lineno"> 148</span> </div>
<div class="line"><a name="l00149"></a><span class="lineno"> 149</span> } <span class="comment">// namespace ParallelHelper2</span></div>
<div class="line"><a name="l00150"></a><span class="lineno"> 150</span> </div>
<div class="line"><a name="l00151"></a><span class="lineno"> 151</span> <span class="preprocessor">#endif // DOXYGEN_PARSING</span></div>
<div class="line"><a name="l00152"></a><span class="lineno"> 152</span> <span class="preprocessor"></span><span class="comment"></span></div>
<div class="line"><a name="l00153"></a><span class="lineno"> 153</span> <span class="comment">/**</span></div>
<div class="line"><a name="l00154"></a><span class="lineno"> 154</span> <span class="comment"> * \#include <c++-gtk-utils/parallel.h></span></div>
<div class="line"><a name="l00155"></a><span class="lineno"> 155</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00156"></a><span class="lineno"> 156</span> <span class="comment"> * This function applies a callable object to each element of a</span></div>
<div class="line"><a name="l00157"></a><span class="lineno"> 157</span> <span class="comment"> * container in the range ['first', 'last'), by executing each such</span></div>
<div class="line"><a name="l00158"></a><span class="lineno"> 158</span> <span class="comment"> * application as a task of a Thread::TaskManager object. Tasks are</span></div>
<div class="line"><a name="l00159"></a><span class="lineno"> 159</span> <span class="comment"> * added to the Thread::TaskManager object in the order in which the</span></div>
<div class="line"><a name="l00160"></a><span class="lineno"> 160</span> <span class="comment"> * respective elements appear in the container (and if a task mutates</span></div>
<div class="line"><a name="l00161"></a><span class="lineno"> 161</span> <span class="comment"> * its argument, it will do so in respect of the correct element of</span></div>
<div class="line"><a name="l00162"></a><span class="lineno"> 162</span> <span class="comment"> * the container), but no other ordering arises, and the tasks will</span></div>
<div class="line"><a name="l00163"></a><span class="lineno"> 163</span> <span class="comment"> * execute in parallel to the extent that the Thread::TaskManager</span></div>
<div class="line"><a name="l00164"></a><span class="lineno"> 164</span> <span class="comment"> * object has sufficient threads available to do so.</span></div>
<div class="line"><a name="l00165"></a><span class="lineno"> 165</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00166"></a><span class="lineno"> 166</span> <span class="comment"> * Apart from that, and that this function returns void, it does the</span></div>
<div class="line"><a name="l00167"></a><span class="lineno"> 167</span> <span class="comment"> * same as std::for_each(). It can mutate container elements if the</span></div>
<div class="line"><a name="l00168"></a><span class="lineno"> 168</span> <span class="comment"> * callable object takes its argument by non-const reference. It will</span></div>
<div class="line"><a name="l00169"></a><span class="lineno"> 169</span> <span class="comment"> * not return until the callable object has been applied to all of the</span></div>
<div class="line"><a name="l00170"></a><span class="lineno"> 170</span> <span class="comment"> * elements in the range ['first', 'last').</span></div>
<div class="line"><a name="l00171"></a><span class="lineno"> 171</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00172"></a><span class="lineno"> 172</span> <span class="comment"> * This function can be called by a task running on the same</span></div>
<div class="line"><a name="l00173"></a><span class="lineno"> 173</span> <span class="comment"> * TaskManager object.</span></div>
<div class="line"><a name="l00174"></a><span class="lineno"> 174</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00175"></a><span class="lineno"> 175</span> <span class="comment"> * @param tm The Thread::TaskManager object on which the tasks will</span></div>
<div class="line"><a name="l00176"></a><span class="lineno"> 176</span> <span class="comment"> * run.</span></div>
<div class="line"><a name="l00177"></a><span class="lineno"> 177</span> <span class="comment"> * @param first The beginning of the range to which 'func' is to be</span></div>
<div class="line"><a name="l00178"></a><span class="lineno"> 178</span> <span class="comment"> * applied.</span></div>
<div class="line"><a name="l00179"></a><span class="lineno"> 179</span> <span class="comment"> * @param last One past the last element to which 'func' is to be</span></div>
<div class="line"><a name="l00180"></a><span class="lineno"> 180</span> <span class="comment"> * applied.</span></div>
<div class="line"><a name="l00181"></a><span class="lineno"> 181</span> <span class="comment"> * @param func A callable object to be applied to each element in the</span></div>
<div class="line"><a name="l00182"></a><span class="lineno"> 182</span> <span class="comment"> * range ['first', 'last'), such as formed by a lambda expression or</span></div>
<div class="line"><a name="l00183"></a><span class="lineno"> 183</span> <span class="comment"> * the result of std::bind. It should take a single unbound argument</span></div>
<div class="line"><a name="l00184"></a><span class="lineno"> 184</span> <span class="comment"> * of the value type of the container to which 'first' and 'last'</span></div>
<div class="line"><a name="l00185"></a><span class="lineno"> 185</span> <span class="comment"> * relate or a const or non-const reference to that type. Any return</span></div>
<div class="line"><a name="l00186"></a><span class="lineno"> 186</span> <span class="comment"> * value is discarded. If an exception propagates from 'func', the</span></div>
<div class="line"><a name="l00187"></a><span class="lineno"> 187</span> <span class="comment"> * exception will be consumed while the for each loop is running, and</span></div>
<div class="line"><a name="l00188"></a><span class="lineno"> 188</span> <span class="comment"> * an attempt will still be made to apply 'func' to all remaining</span></div>
<div class="line"><a name="l00189"></a><span class="lineno"> 189</span> <span class="comment"> * elements in the range ['first', 'last'), and only after that</span></div>
<div class="line"><a name="l00190"></a><span class="lineno"> 190</span> <span class="comment"> * attempt has completed will the exception Cgu::Thread::ParallelError</span></div>
<div class="line"><a name="l00191"></a><span class="lineno"> 191</span> <span class="comment"> * be thrown.</span></div>
<div class="line"><a name="l00192"></a><span class="lineno"> 192</span> <span class="comment"> * @exception std::bad_alloc This exception will be thrown if memory</span></div>
<div class="line"><a name="l00193"></a><span class="lineno"> 193</span> <span class="comment"> * is exhausted and the system throws in that case. (On systems with</span></div>
<div class="line"><a name="l00194"></a><span class="lineno"> 194</span> <span class="comment"> * over-commit/lazy-commit combined with virtual memory (swap), it is</span></div>
<div class="line"><a name="l00195"></a><span class="lineno"> 195</span> <span class="comment"> * rarely useful to check for memory exhaustion). If this exception</span></div>
<div class="line"><a name="l00196"></a><span class="lineno"> 196</span> <span class="comment"> * is thrown, some tasks may nonetheless have already started by</span></div>
<div class="line"><a name="l00197"></a><span class="lineno"> 197</span> <span class="comment"> * virtue of the call to this function, but subsequent ones will not.</span></div>
<div class="line"><a name="l00198"></a><span class="lineno"> 198</span> <span class="comment"> * @exception Cgu::Thread::TaskError This exception will be thrown if</span></div>
<div class="line"><a name="l00199"></a><span class="lineno"> 199</span> <span class="comment"> * stop_all() has previously been called on the Thread::TaskManager</span></div>
<div class="line"><a name="l00200"></a><span class="lineno"> 200</span> <span class="comment"> * object, or if another thread calls stop_all() after this method is</span></div>
<div class="line"><a name="l00201"></a><span class="lineno"> 201</span> <span class="comment"> * called but before it has returned. It will also be thrown if the</span></div>
<div class="line"><a name="l00202"></a><span class="lineno"> 202</span> <span class="comment"> * Thread::TaskManager object's is_error() method would return true</span></div>
<div class="line"><a name="l00203"></a><span class="lineno"> 203</span> <span class="comment"> * because its internal thread pool loop implementation has thrown</span></div>
<div class="line"><a name="l00204"></a><span class="lineno"> 204</span> <span class="comment"> * std::bad_alloc, or a thread has failed to start correctly because</span></div>
<div class="line"><a name="l00205"></a><span class="lineno"> 205</span> <span class="comment"> * pthread has run out of resources. (On systems with</span></div>
<div class="line"><a name="l00206"></a><span class="lineno"> 206</span> <span class="comment"> * over-commit/lazy-commit combined with virtual memory (swap), it is</span></div>
<div class="line"><a name="l00207"></a><span class="lineno"> 207</span> <span class="comment"> * rarely useful to check for memory exhaustion, and if a reasonable</span></div>
<div class="line"><a name="l00208"></a><span class="lineno"> 208</span> <span class="comment"> * maximum thread count has been chosen for the Thread::TaskManager</span></div>
<div class="line"><a name="l00209"></a><span class="lineno"> 209</span> <span class="comment"> * object pthread should not run out of other resources, but there may</span></div>
<div class="line"><a name="l00210"></a><span class="lineno"> 210</span> <span class="comment"> * be some specialized cases where the return value of is_error() is</span></div>
<div class="line"><a name="l00211"></a><span class="lineno"> 211</span> <span class="comment"> * useful.) If this exception is thrown, some tasks may nonetheless</span></div>
<div class="line"><a name="l00212"></a><span class="lineno"> 212</span> <span class="comment"> * have already started by virtue of the call to this function.</span></div>
<div class="line"><a name="l00213"></a><span class="lineno"> 213</span> <span class="comment"> * @exception Cgu::Thread::ParallelError This exception will be thrown</span></div>
<div class="line"><a name="l00214"></a><span class="lineno"> 214</span> <span class="comment"> * if an exception propagates from the 'func' callable object when it</span></div>
<div class="line"><a name="l00215"></a><span class="lineno"> 215</span> <span class="comment"> * executes on being applied to one or more elements of the container.</span></div>
<div class="line"><a name="l00216"></a><span class="lineno"> 216</span> <span class="comment"> * Such an exception will not stop an attempt being made to apply</span></div>
<div class="line"><a name="l00217"></a><span class="lineno"> 217</span> <span class="comment"> * 'func' (successfully or unsuccessfully) to all elements in the</span></div>
<div class="line"><a name="l00218"></a><span class="lineno"> 218</span> <span class="comment"> * range ['first', 'last'). Cgu::Thread::ParallelError will be thrown</span></div>
<div class="line"><a name="l00219"></a><span class="lineno"> 219</span> <span class="comment"> * after such attempted application has finished.</span></div>
<div class="line"><a name="l00220"></a><span class="lineno"> 220</span> <span class="comment"> * @exception Cgu::Thread::MutexError This exception will be thrown if</span></div>
<div class="line"><a name="l00221"></a><span class="lineno"> 221</span> <span class="comment"> * initialization of a mutex used by this function fails. (It is</span></div>
<div class="line"><a name="l00222"></a><span class="lineno"> 222</span> <span class="comment"> * often not worth checking for this, as it means either memory is</span></div>
<div class="line"><a name="l00223"></a><span class="lineno"> 223</span> <span class="comment"> * exhausted or pthread has run out of other resources to create new</span></div>
<div class="line"><a name="l00224"></a><span class="lineno"> 224</span> <span class="comment"> * mutexes.) If this exception is thrown, no tasks will start.</span></div>
<div class="line"><a name="l00225"></a><span class="lineno"> 225</span> <span class="comment"> * @exception Cgu::Thread::CondError This exception will be thrown if</span></div>
<div class="line"><a name="l00226"></a><span class="lineno"> 226</span> <span class="comment"> * initialization of a condition variable used by this function fails.</span></div>
<div class="line"><a name="l00227"></a><span class="lineno"> 227</span> <span class="comment"> * (It is often not worth checking for this, as it means either memory</span></div>
<div class="line"><a name="l00228"></a><span class="lineno"> 228</span> <span class="comment"> * is exhausted or pthread has run out of other resources to create</span></div>
<div class="line"><a name="l00229"></a><span class="lineno"> 229</span> <span class="comment"> * new condition variables.) If this exception is thrown, no tasks</span></div>
<div class="line"><a name="l00230"></a><span class="lineno"> 230</span> <span class="comment"> * will start.</span></div>
<div class="line"><a name="l00231"></a><span class="lineno"> 231</span> <span class="comment"> * @note An exception might also be thrown if the copy or move</span></div>
<div class="line"><a name="l00232"></a><span class="lineno"> 232</span> <span class="comment"> * constructor of the 'func' callable objects throws. If such an</span></div>
<div class="line"><a name="l00233"></a><span class="lineno"> 233</span> <span class="comment"> * exception is thrown, no tasks will start.</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"> 235</span> <span class="comment"> * Since 2.0.19/2.2.2</span></div>
<div class="line"><a name="l00236"></a><span class="lineno"> 236</span> <span class="comment"> */</span></div>
<div class="line"><a name="l00237"></a><span class="lineno"> 237</span> <span class="keyword">template</span> <<span class="keyword">class</span> Iterator, <span class="keyword">class</span> Func></div>
<div class="line"><a name="l00238"></a><span class="lineno"><a class="code" href="namespaceCgu_1_1Thread.html#a984bbff1392b7e173a8b3ad081e542c2"> 238</a></span> <span class="keywordtype">void</span> <a class="code" href="namespaceCgu_1_1Thread.html#a984bbff1392b7e173a8b3ad081e542c2">parallel_for_each</a>(<a class="code" href="classCgu_1_1Thread_1_1TaskManager.html" title="A thread-pool class for managing tasks in multi-threaded programs. ">TaskManager</a>& tm,</div>
<div class="line"><a name="l00239"></a><span class="lineno"> 239</span>  Iterator first,</div>
<div class="line"><a name="l00240"></a><span class="lineno"> 240</span>  Iterator last,</div>
<div class="line"><a name="l00241"></a><span class="lineno"> 241</span>  Func&& func) {</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="keyword">typedef</span> <span class="keyword">typename</span> std::iterator_traits<Iterator>::value_type ArgType;</div>
<div class="line"><a name="l00244"></a><span class="lineno"> 244</span>  <span class="keyword">typedef</span> <span class="keyword">typename</span> std::iterator_traits<Iterator>::difference_type DiffType;</div>
<div class="line"><a name="l00245"></a><span class="lineno"> 245</span> </div>
<div class="line"><a name="l00246"></a><span class="lineno"> 246</span>  <a class="code" href="classCgu_1_1Thread_1_1Mutex.html" title="A wrapper class for pthread mutexes. ">Mutex</a> mutex;</div>
<div class="line"><a name="l00247"></a><span class="lineno"> 247</span>  <a class="code" href="classCgu_1_1Thread_1_1Cond.html" title="A wrapper class for pthread condition variables. ">Cond</a> cond;</div>
<div class="line"><a name="l00248"></a><span class="lineno"> 248</span>  DiffType start_count = 0;</div>
<div class="line"><a name="l00249"></a><span class="lineno"> 249</span>  DiffType done_count = 0;</div>
<div class="line"><a name="l00250"></a><span class="lineno"> 250</span>  <span class="keywordtype">bool</span> error = <span class="keyword">false</span>;</div>
<div class="line"><a name="l00251"></a><span class="lineno"> 251</span> </div>
<div class="line"><a name="l00252"></a><span class="lineno"> 252</span>  <span class="comment">// construct SafeFunctorArg objects so that they can be shared</span></div>
<div class="line"><a name="l00253"></a><span class="lineno"> 253</span>  <span class="comment">// between different tasks</span></div>
<div class="line"><a name="l00254"></a><span class="lineno"> 254</span>  <a class="code" href="classCgu_1_1Callback_1_1SafeFunctorArg.html" title="Functor class holding a Callback::CallbackArg object, with thread-safe reference count. ">Cgu::Callback::SafeFunctorArg<ArgType&></a> s_task{</div>
<div class="line"><a name="l00255"></a><span class="lineno"> 255</span>  Cgu::Callback::lambda<ArgType&>(std::forward<Func>(func))</div>
<div class="line"><a name="l00256"></a><span class="lineno"> 256</span>  };</div>
<div class="line"><a name="l00257"></a><span class="lineno"> 257</span>  <a class="code" href="classCgu_1_1Callback_1_1SafeFunctorArg.html" title="Functor class holding a Callback::CallbackArg object, with thread-safe reference count. ">Cgu::Callback::SafeFunctor</a> s_fail{</div>
<div class="line"><a name="l00258"></a><span class="lineno"> 258</span>  <a class="code" href="namespaceCgu_1_1Callback.html#a3e32d4f4961c618aa7e03bda00f398b8">Cgu::Callback::make</a>(&ParallelHelper2::fail_func<DiffType>,</div>
<div class="line"><a name="l00259"></a><span class="lineno"> 259</span>  &mutex,</div>
<div class="line"><a name="l00260"></a><span class="lineno"> 260</span>  &cond,</div>
<div class="line"><a name="l00261"></a><span class="lineno"> 261</span>  &error,</div>
<div class="line"><a name="l00262"></a><span class="lineno"> 262</span>  &done_count)</div>
<div class="line"><a name="l00263"></a><span class="lineno"> 263</span>  };</div>
<div class="line"><a name="l00264"></a><span class="lineno"> 264</span> </div>
<div class="line"><a name="l00265"></a><span class="lineno"> 265</span>  <span class="keywordflow">for</span> (; first != last; ++first, ++start_count) {</div>
<div class="line"><a name="l00266"></a><span class="lineno"> 266</span>  std::unique_ptr<const Cgu::Callback::Callback> task_cb(</div>
<div class="line"><a name="l00267"></a><span class="lineno"> 267</span>  <a class="code" href="namespaceCgu_1_1Callback.html#a94b122ac99f423928320240fd48d571b">Cgu::Callback::make_ref</a>(&ParallelHelper2::for_each_cb_func<ArgType, DiffType, Iterator>,</div>
<div class="line"><a name="l00268"></a><span class="lineno"> 268</span>  s_task,</div>
<div class="line"><a name="l00269"></a><span class="lineno"> 269</span>  first,</div>
<div class="line"><a name="l00270"></a><span class="lineno"> 270</span>  &mutex,</div>
<div class="line"><a name="l00271"></a><span class="lineno"> 271</span>  &cond,</div>
<div class="line"><a name="l00272"></a><span class="lineno"> 272</span>  &done_count)</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>  std::unique_ptr<const Cgu::Callback::Callback> fail_cb(</div>
<div class="line"><a name="l00275"></a><span class="lineno"> 275</span>  Cgu::Callback::lambda<>([s_fail] () {s_fail();})</div>
<div class="line"><a name="l00276"></a><span class="lineno"> 276</span>  );</div>
<div class="line"><a name="l00277"></a><span class="lineno"> 277</span> </div>
<div class="line"><a name="l00278"></a><span class="lineno"> 278</span>  tm.<a class="code" href="classCgu_1_1Thread_1_1TaskManager.html#a81f7c8af3295d92c0e19d7f9498a4078">add_task</a>(std::move(task_cb), std::move(fail_cb));</div>
<div class="line"><a name="l00279"></a><span class="lineno"> 279</span>  }</div>
<div class="line"><a name="l00280"></a><span class="lineno"> 280</span>  </div>
<div class="line"><a name="l00281"></a><span class="lineno"> 281</span>  <a class="code" href="classCgu_1_1Thread_1_1Mutex_1_1Lock.html" title="A scoped locking class for exception safe Mutex locking. ">Mutex::Lock</a> l{mutex};</div>
<div class="line"><a name="l00282"></a><span class="lineno"> 282</span>  <span class="keywordflow">while</span> (start_count > done_count) cond.<a class="code" href="classCgu_1_1Thread_1_1Cond.html#a5eda52c227552555102bb45010a8f6c9">wait</a>(mutex);</div>
<div class="line"><a name="l00283"></a><span class="lineno"> 283</span>  <span class="keywordflow">if</span> (error) <span class="keywordflow">throw</span> <a class="code" href="structCgu_1_1Thread_1_1ParallelError.html">ParallelError</a>();</div>
<div class="line"><a name="l00284"></a><span class="lineno"> 284</span> }</div>
<div class="line"><a name="l00285"></a><span class="lineno"> 285</span> <span class="comment"></span></div>
<div class="line"><a name="l00286"></a><span class="lineno"> 286</span> <span class="comment">/**</span></div>
<div class="line"><a name="l00287"></a><span class="lineno"> 287</span> <span class="comment"> * \#include <c++-gtk-utils/parallel.h></span></div>
<div class="line"><a name="l00288"></a><span class="lineno"> 288</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00289"></a><span class="lineno"> 289</span> <span class="comment"> * This function maps over a container in the range ['first', 'last'),</span></div>
<div class="line"><a name="l00290"></a><span class="lineno"> 290</span> <span class="comment"> * applying a unary callable object to each element of the container</span></div>
<div class="line"><a name="l00291"></a><span class="lineno"> 291</span> <span class="comment"> * in that range and storing the result in the destination range, by</span></div>
<div class="line"><a name="l00292"></a><span class="lineno"> 292</span> <span class="comment"> * executing each such application as a task of a Thread::TaskManager</span></div>
<div class="line"><a name="l00293"></a><span class="lineno"> 293</span> <span class="comment"> * object. Tasks are added to the Thread::TaskManager object in the</span></div>
<div class="line"><a name="l00294"></a><span class="lineno"> 294</span> <span class="comment"> * order in which the respective elements appear in the source</span></div>
<div class="line"><a name="l00295"></a><span class="lineno"> 295</span> <span class="comment"> * container, and the final result appears in the destination</span></div>
<div class="line"><a name="l00296"></a><span class="lineno"> 296</span> <span class="comment"> * container in the same order as the source range from which it is</span></div>
<div class="line"><a name="l00297"></a><span class="lineno"> 297</span> <span class="comment"> * generated (including if a back_inserter iterator is used), but no</span></div>
<div class="line"><a name="l00298"></a><span class="lineno"> 298</span> <span class="comment"> * other ordering arises, and the tasks will execute in parallel to</span></div>
<div class="line"><a name="l00299"></a><span class="lineno"> 299</span> <span class="comment"> * the extent that the Thread::TaskManager object has sufficient</span></div>
<div class="line"><a name="l00300"></a><span class="lineno"> 300</span> <span class="comment"> * threads available to do so.</span></div>
<div class="line"><a name="l00301"></a><span class="lineno"> 301</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00302"></a><span class="lineno"> 302</span> <span class="comment"> * Apart from that, this function does the same as the version of</span></div>
<div class="line"><a name="l00303"></a><span class="lineno"> 303</span> <span class="comment"> * std::transform() taking a unary function, except that it returns</span></div>
<div class="line"><a name="l00304"></a><span class="lineno"> 304</span> <span class="comment"> * void (see Thread::parallel_transform_partial() for a function which</span></div>
<div class="line"><a name="l00305"></a><span class="lineno"> 305</span> <span class="comment"> * returns a destination iterator and an iterator to the source</span></div>
<div class="line"><a name="l00306"></a><span class="lineno"> 306</span> <span class="comment"> * range). It will not return until the callable object has been</span></div>
<div class="line"><a name="l00307"></a><span class="lineno"> 307</span> <span class="comment"> * applied to all of the elements in the range ['first', 'last').</span></div>
<div class="line"><a name="l00308"></a><span class="lineno"> 308</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00309"></a><span class="lineno"> 309</span> <span class="comment"> * This function can be called by a task running on the same</span></div>
<div class="line"><a name="l00310"></a><span class="lineno"> 310</span> <span class="comment"> * TaskManager object (a result can therefore be delivered</span></div>
<div class="line"><a name="l00311"></a><span class="lineno"> 311</span> <span class="comment"> * asynchronously by calling this function in a task created by the</span></div>
<div class="line"><a name="l00312"></a><span class="lineno"> 312</span> <span class="comment"> * make_task_when(), make_task_compose() or make_task_when_full()</span></div>
<div class="line"><a name="l00313"></a><span class="lineno"> 313</span> <span class="comment"> * Thread::TaskManager methods). A task can carry out a map-reduce</span></div>
<div class="line"><a name="l00314"></a><span class="lineno"> 314</span> <span class="comment"> * operation by passing the result of calling this function to</span></div>
<div class="line"><a name="l00315"></a><span class="lineno"> 315</span> <span class="comment"> * std::accumulate() to perform a fold-left or fold-right on that</span></div>
<div class="line"><a name="l00316"></a><span class="lineno"> 316</span> <span class="comment"> * result.</span></div>
<div class="line"><a name="l00317"></a><span class="lineno"> 317</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00318"></a><span class="lineno"> 318</span> <span class="comment"> * A separate overload of this function takes a binary callable</span></div>
<div class="line"><a name="l00319"></a><span class="lineno"> 319</span> <span class="comment"> * object.</span></div>
<div class="line"><a name="l00320"></a><span class="lineno"> 320</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00321"></a><span class="lineno"> 321</span> <span class="comment"> * Here is a trivial example of a map-reduce operation which maps over</span></div>
<div class="line"><a name="l00322"></a><span class="lineno"> 322</span> <span class="comment"> * a vector by multiplying each element by 2 in separate tasks, and</span></div>
<div class="line"><a name="l00323"></a><span class="lineno"> 323</span> <span class="comment"> * then folds-left using std::accumulate() (std::accumulate() can fold</span></div>
<div class="line"><a name="l00324"></a><span class="lineno"> 324</span> <span class="comment"> * using any callable object, but in this example the default of</span></div>
<div class="line"><a name="l00325"></a><span class="lineno"> 325</span> <span class="comment"> * addition is used):</span></div>
<div class="line"><a name="l00326"></a><span class="lineno"> 326</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00327"></a><span class="lineno"> 327</span> <span class="comment"> * @code</span></div>
<div class="line"><a name="l00328"></a><span class="lineno"> 328</span> <span class="comment"> * using namespace Cgu;</span></div>
<div class="line"><a name="l00329"></a><span class="lineno"> 329</span> <span class="comment"> * std::vector<int> v{1, 2, 3, 4, 5};</span></div>
<div class="line"><a name="l00330"></a><span class="lineno"> 330</span> <span class="comment"> * Thread::TaskManager tm;</span></div>
<div class="line"><a name="l00331"></a><span class="lineno"> 331</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00332"></a><span class="lineno"> 332</span> <span class="comment"> * Thread::parallel_transform(tm,</span></div>
<div class="line"><a name="l00333"></a><span class="lineno"> 333</span> <span class="comment"> * v.begin(),</span></div>
<div class="line"><a name="l00334"></a><span class="lineno"> 334</span> <span class="comment"> * v.end(),</span></div>
<div class="line"><a name="l00335"></a><span class="lineno"> 335</span> <span class="comment"> * v.begin(),</span></div>
<div class="line"><a name="l00336"></a><span class="lineno"> 336</span> <span class="comment"> * [] (int elt) {return elt * 2;});</span></div>
<div class="line"><a name="l00337"></a><span class="lineno"> 337</span> <span class="comment"> * // res will be equal to 30</span></div>
<div class="line"><a name="l00338"></a><span class="lineno"> 338</span> <span class="comment"> * int res = std::accumulate(v.begin(), v.end(), 0);</span></div>
<div class="line"><a name="l00339"></a><span class="lineno"> 339</span> <span class="comment"> * @endcode</span></div>
<div class="line"><a name="l00340"></a><span class="lineno"> 340</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00341"></a><span class="lineno"> 341</span> <span class="comment"> * @param tm The Thread::TaskManager object on which the tasks will</span></div>
<div class="line"><a name="l00342"></a><span class="lineno"> 342</span> <span class="comment"> * run.</span></div>
<div class="line"><a name="l00343"></a><span class="lineno"> 343</span> <span class="comment"> * @param first The beginning of the range to which 'func' is to be</span></div>
<div class="line"><a name="l00344"></a><span class="lineno"> 344</span> <span class="comment"> * applied.</span></div>
<div class="line"><a name="l00345"></a><span class="lineno"> 345</span> <span class="comment"> * @param last One past the last element to which 'func' is to be</span></div>
<div class="line"><a name="l00346"></a><span class="lineno"> 346</span> <span class="comment"> * applied.</span></div>
<div class="line"><a name="l00347"></a><span class="lineno"> 347</span> <span class="comment"> * @param dest The beginning of the range to which the result of</span></div>
<div class="line"><a name="l00348"></a><span class="lineno"> 348</span> <span class="comment"> * applying 'func' to the elements in the range ['first', 'last') is</span></div>
<div class="line"><a name="l00349"></a><span class="lineno"> 349</span> <span class="comment"> * to be stored. As in the case of std::transform, this can overlap</span></div>
<div class="line"><a name="l00350"></a><span class="lineno"> 350</span> <span class="comment"> * with or be the same as the source range. It may also be an insert</span></div>
<div class="line"><a name="l00351"></a><span class="lineno"> 351</span> <span class="comment"> * iterator.</span></div>
<div class="line"><a name="l00352"></a><span class="lineno"> 352</span> <span class="comment"> * @param func A unary callable object to be applied to each element</span></div>
<div class="line"><a name="l00353"></a><span class="lineno"> 353</span> <span class="comment"> * in the range ['first', 'last'), such as formed by a lambda</span></div>
<div class="line"><a name="l00354"></a><span class="lineno"> 354</span> <span class="comment"> * expression or the result of std::bind. It should take a single</span></div>
<div class="line"><a name="l00355"></a><span class="lineno"> 355</span> <span class="comment"> * unbound argument of the value type of the container to which</span></div>
<div class="line"><a name="l00356"></a><span class="lineno"> 356</span> <span class="comment"> * 'first' and 'last' relate or a const or non-const reference to that</span></div>
<div class="line"><a name="l00357"></a><span class="lineno"> 357</span> <span class="comment"> * type. If an exception propagates from 'func', the exception will</span></div>
<div class="line"><a name="l00358"></a><span class="lineno"> 358</span> <span class="comment"> * be consumed while the transform loop is running, and an attempt</span></div>
<div class="line"><a name="l00359"></a><span class="lineno"> 359</span> <span class="comment"> * will still be made to apply 'func' to all remaining elements in the</span></div>
<div class="line"><a name="l00360"></a><span class="lineno"> 360</span> <span class="comment"> * range ['first', 'last'), and only after that attempt has completed</span></div>
<div class="line"><a name="l00361"></a><span class="lineno"> 361</span> <span class="comment"> * will the exception Cgu::Thread::ParallelError be thrown.</span></div>
<div class="line"><a name="l00362"></a><span class="lineno"> 362</span> <span class="comment"> * @exception std::bad_alloc This exception will be thrown if memory</span></div>
<div class="line"><a name="l00363"></a><span class="lineno"> 363</span> <span class="comment"> * is exhausted and the system throws in that case. (On systems with</span></div>
<div class="line"><a name="l00364"></a><span class="lineno"> 364</span> <span class="comment"> * over-commit/lazy-commit combined with virtual memory (swap), it is</span></div>
<div class="line"><a name="l00365"></a><span class="lineno"> 365</span> <span class="comment"> * rarely useful to check for memory exhaustion). If this exception</span></div>
<div class="line"><a name="l00366"></a><span class="lineno"> 366</span> <span class="comment"> * is thrown, some tasks may nonetheless have already started by</span></div>
<div class="line"><a name="l00367"></a><span class="lineno"> 367</span> <span class="comment"> * virtue of the call to this function, but subsequent ones will not.</span></div>
<div class="line"><a name="l00368"></a><span class="lineno"> 368</span> <span class="comment"> * @exception Cgu::Thread::TaskError This exception will be thrown if</span></div>
<div class="line"><a name="l00369"></a><span class="lineno"> 369</span> <span class="comment"> * stop_all() has previously been called on the Thread::TaskManager</span></div>
<div class="line"><a name="l00370"></a><span class="lineno"> 370</span> <span class="comment"> * object, or if another thread calls stop_all() after this method is</span></div>
<div class="line"><a name="l00371"></a><span class="lineno"> 371</span> <span class="comment"> * called but before it has returned. It will also be thrown if the</span></div>
<div class="line"><a name="l00372"></a><span class="lineno"> 372</span> <span class="comment"> * Thread::TaskManager object's is_error() method would return true</span></div>
<div class="line"><a name="l00373"></a><span class="lineno"> 373</span> <span class="comment"> * because its internal thread pool loop implementation has thrown</span></div>
<div class="line"><a name="l00374"></a><span class="lineno"> 374</span> <span class="comment"> * std::bad_alloc, or a thread has failed to start correctly because</span></div>
<div class="line"><a name="l00375"></a><span class="lineno"> 375</span> <span class="comment"> * pthread has run out of resources. (On systems with</span></div>
<div class="line"><a name="l00376"></a><span class="lineno"> 376</span> <span class="comment"> * over-commit/lazy-commit combined with virtual memory (swap), it is</span></div>
<div class="line"><a name="l00377"></a><span class="lineno"> 377</span> <span class="comment"> * rarely useful to check for memory exhaustion, and if a reasonable</span></div>
<div class="line"><a name="l00378"></a><span class="lineno"> 378</span> <span class="comment"> * maximum thread count has been chosen for the Thread::TaskManager</span></div>
<div class="line"><a name="l00379"></a><span class="lineno"> 379</span> <span class="comment"> * object pthread should not run out of other resources, but there may</span></div>
<div class="line"><a name="l00380"></a><span class="lineno"> 380</span> <span class="comment"> * be some specialized cases where the return value of is_error() is</span></div>
<div class="line"><a name="l00381"></a><span class="lineno"> 381</span> <span class="comment"> * useful.) If this exception is thrown, some tasks may nonetheless</span></div>
<div class="line"><a name="l00382"></a><span class="lineno"> 382</span> <span class="comment"> * have already started by virtue of the call to this function.</span></div>
<div class="line"><a name="l00383"></a><span class="lineno"> 383</span> <span class="comment"> * @exception Cgu::Thread::ParallelError This exception will be thrown</span></div>
<div class="line"><a name="l00384"></a><span class="lineno"> 384</span> <span class="comment"> * if an exception propagates from the 'func' callable object when it</span></div>
<div class="line"><a name="l00385"></a><span class="lineno"> 385</span> <span class="comment"> * executes on being applied to one or more elements of the source</span></div>
<div class="line"><a name="l00386"></a><span class="lineno"> 386</span> <span class="comment"> * container. Such an exception will not stop an attempt being made</span></div>
<div class="line"><a name="l00387"></a><span class="lineno"> 387</span> <span class="comment"> * to apply 'func' (successfully or unsuccessfully) to all elements in</span></div>
<div class="line"><a name="l00388"></a><span class="lineno"> 388</span> <span class="comment"> * the range ['first', 'last'). Cgu::Thread::ParallelError will be</span></div>
<div class="line"><a name="l00389"></a><span class="lineno"> 389</span> <span class="comment"> * thrown after such attempted application has finished.</span></div>
<div class="line"><a name="l00390"></a><span class="lineno"> 390</span> <span class="comment"> * @exception Cgu::Thread::MutexError This exception will be thrown if</span></div>
<div class="line"><a name="l00391"></a><span class="lineno"> 391</span> <span class="comment"> * initialization of a mutex used by this function fails. (It is</span></div>
<div class="line"><a name="l00392"></a><span class="lineno"> 392</span> <span class="comment"> * often not worth checking for this, as it means either memory is</span></div>
<div class="line"><a name="l00393"></a><span class="lineno"> 393</span> <span class="comment"> * exhausted or pthread has run out of other resources to create new</span></div>
<div class="line"><a name="l00394"></a><span class="lineno"> 394</span> <span class="comment"> * mutexes.) If this exception is thrown, no tasks will start.</span></div>
<div class="line"><a name="l00395"></a><span class="lineno"> 395</span> <span class="comment"> * @exception Cgu::Thread::CondError This exception will be thrown if</span></div>
<div class="line"><a name="l00396"></a><span class="lineno"> 396</span> <span class="comment"> * initialization of a condition variable used by this function fails.</span></div>
<div class="line"><a name="l00397"></a><span class="lineno"> 397</span> <span class="comment"> * (It is often not worth checking for this, as it means either memory</span></div>
<div class="line"><a name="l00398"></a><span class="lineno"> 398</span> <span class="comment"> * is exhausted or pthread has run out of other resources to create</span></div>
<div class="line"><a name="l00399"></a><span class="lineno"> 399</span> <span class="comment"> * new condition variables.) If this exception is thrown, no tasks</span></div>
<div class="line"><a name="l00400"></a><span class="lineno"> 400</span> <span class="comment"> * will start.</span></div>
<div class="line"><a name="l00401"></a><span class="lineno"> 401</span> <span class="comment"> * @note An exception might also be thrown if the copy or move</span></div>
<div class="line"><a name="l00402"></a><span class="lineno"> 402</span> <span class="comment"> * constructor of the 'func' callable objects throws. If such an</span></div>
<div class="line"><a name="l00403"></a><span class="lineno"> 403</span> <span class="comment"> * exception is thrown, no tasks will start.</span></div>
<div class="line"><a name="l00404"></a><span class="lineno"> 404</span> <span class="comment"> * </span></div>
<div class="line"><a name="l00405"></a><span class="lineno"> 405</span> <span class="comment"> * Since 2.0.19/2.2.2</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="keyword">template</span> <<span class="keyword">class</span> SourceIterator, <span class="keyword">class</span> DestIterator, <span class="keyword">class</span> Func></div>
<div class="line"><a name="l00408"></a><span class="lineno"><a class="code" href="namespaceCgu_1_1Thread.html#a497aa47446b79c87f1a404e11151a942"> 408</a></span> <span class="keywordtype">void</span> <a class="code" href="namespaceCgu_1_1Thread.html#a497aa47446b79c87f1a404e11151a942">parallel_transform</a>(<a class="code" href="classCgu_1_1Thread_1_1TaskManager.html" title="A thread-pool class for managing tasks in multi-threaded programs. ">TaskManager</a>& tm,</div>
<div class="line"><a name="l00409"></a><span class="lineno"> 409</span>  SourceIterator first,</div>
<div class="line"><a name="l00410"></a><span class="lineno"> 410</span>  SourceIterator last,</div>
<div class="line"><a name="l00411"></a><span class="lineno"> 411</span>  DestIterator dest,</div>
<div class="line"><a name="l00412"></a><span class="lineno"> 412</span>  Func&& func) {</div>
<div class="line"><a name="l00413"></a><span class="lineno"> 413</span> </div>
<div class="line"><a name="l00414"></a><span class="lineno"> 414</span>  <span class="keywordflow">if</span> (first == last) <span class="keywordflow">return</span>;</div>
<div class="line"><a name="l00415"></a><span class="lineno"> 415</span> </div>
<div class="line"><a name="l00416"></a><span class="lineno"> 416</span>  <span class="keyword">typedef</span> <span class="keyword">typename</span> std::iterator_traits<SourceIterator>::value_type ArgType;</div>
<div class="line"><a name="l00417"></a><span class="lineno"> 417</span>  <span class="keyword">typedef</span> <span class="keyword">typename</span> std::iterator_traits<SourceIterator>::difference_type DiffType;</div>
<div class="line"><a name="l00418"></a><span class="lineno"> 418</span>  <span class="keyword">typedef</span> <span class="keyword">typename</span> std::remove_const<typename std::remove_reference<Func>::type>::type FType;</div>
<div class="line"><a name="l00419"></a><span class="lineno"> 419</span>  <span class="keyword">typedef</span> decltype(func(*first)) DestType;</div>
<div class="line"><a name="l00420"></a><span class="lineno"> 420</span> </div>
<div class="line"><a name="l00421"></a><span class="lineno"> 421</span>  <a class="code" href="classCgu_1_1Thread_1_1Mutex.html" title="A wrapper class for pthread mutexes. ">Mutex</a> mutex;</div>
<div class="line"><a name="l00422"></a><span class="lineno"> 422</span>  <a class="code" href="classCgu_1_1Thread_1_1Cond.html" title="A wrapper class for pthread condition variables. ">Cond</a> cond;</div>
<div class="line"><a name="l00423"></a><span class="lineno"> 423</span>  DiffType start_count = 0;</div>
<div class="line"><a name="l00424"></a><span class="lineno"> 424</span>  DiffType done_count = 0;</div>
<div class="line"><a name="l00425"></a><span class="lineno"> 425</span>  <span class="keywordtype">bool</span> error = <span class="keyword">false</span>;</div>
<div class="line"><a name="l00426"></a><span class="lineno"> 426</span> </div>
<div class="line"><a name="l00427"></a><span class="lineno"> 427</span>  <span class="comment">// intermediate results have to be held in an array so destination</span></div>
<div class="line"><a name="l00428"></a><span class="lineno"> 428</span>  <span class="comment">// ordering can be enforced when using insert interators. This</span></div>
<div class="line"><a name="l00429"></a><span class="lineno"> 429</span>  <span class="comment">// causes some inefficiency for non-random access iterators</span></div>
<div class="line"><a name="l00430"></a><span class="lineno"> 430</span>  std::unique_ptr<DestType[]> results(<span class="keyword">new</span> DestType[std::distance(first, last)]);</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>  <span class="comment">// construct SafeFunctorArg objects so that they can be shared</span></div>
<div class="line"><a name="l00433"></a><span class="lineno"> 433</span>  <span class="comment">// between different tasks</span></div>
<div class="line"><a name="l00434"></a><span class="lineno"> 434</span>  <a class="code" href="classCgu_1_1Callback_1_1SafeFunctorArg.html" title="Functor class holding a Callback::CallbackArg object, with thread-safe reference count. ">Cgu::Callback::SafeFunctorArg<ArgType&, DestType&></a> s_task{</div>
<div class="line"><a name="l00435"></a><span class="lineno"> 435</span>  <a class="code" href="namespaceCgu_1_1Callback.html#a94b122ac99f423928320240fd48d571b">Cgu::Callback::make_ref</a>(&ParallelHelper2::transform1_func<FType, ArgType, DestType>,</div>
<div class="line"><a name="l00436"></a><span class="lineno"> 436</span>  std::forward<Func>(func))</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>  <a class="code" href="classCgu_1_1Callback_1_1SafeFunctorArg.html" title="Functor class holding a Callback::CallbackArg object, with thread-safe reference count. ">Cgu::Callback::SafeFunctor</a> s_fail{</div>
<div class="line"><a name="l00439"></a><span class="lineno"> 439</span>  <a class="code" href="namespaceCgu_1_1Callback.html#a3e32d4f4961c618aa7e03bda00f398b8">Cgu::Callback::make</a>(&ParallelHelper2::fail_func<DiffType>,</div>
<div class="line"><a name="l00440"></a><span class="lineno"> 440</span>  &mutex,</div>
<div class="line"><a name="l00441"></a><span class="lineno"> 441</span>  &cond,</div>
<div class="line"><a name="l00442"></a><span class="lineno"> 442</span>  &error,</div>
<div class="line"><a name="l00443"></a><span class="lineno"> 443</span>  &done_count)</div>
<div class="line"><a name="l00444"></a><span class="lineno"> 444</span>  };</div>
<div class="line"><a name="l00445"></a><span class="lineno"> 445</span> </div>
<div class="line"><a name="l00446"></a><span class="lineno"> 446</span>  <span class="keywordflow">for</span> (; first != last; ++first, ++start_count) {</div>
<div class="line"><a name="l00447"></a><span class="lineno"> 447</span>  std::unique_ptr<const Cgu::Callback::Callback> task_cb(</div>
<div class="line"><a name="l00448"></a><span class="lineno"> 448</span>  Cgu::Callback::lambda<>(std::bind(&ParallelHelper2::transform1_cb_func<ArgType, DestType, DiffType, SourceIterator>,</div>
<div class="line"><a name="l00449"></a><span class="lineno"> 449</span>  s_task,</div>
<div class="line"><a name="l00450"></a><span class="lineno"> 450</span>  first,</div>
<div class="line"><a name="l00451"></a><span class="lineno"> 451</span>  &mutex,</div>
<div class="line"><a name="l00452"></a><span class="lineno"> 452</span>  &cond,</div>
<div class="line"><a name="l00453"></a><span class="lineno"> 453</span>  &done_count,</div>
<div class="line"><a name="l00454"></a><span class="lineno"> 454</span>  results.get(),</div>
<div class="line"><a name="l00455"></a><span class="lineno"> 455</span>  start_count))</div>
<div class="line"><a name="l00456"></a><span class="lineno"> 456</span>  );</div>
<div class="line"><a name="l00457"></a><span class="lineno"> 457</span>  std::unique_ptr<const Cgu::Callback::Callback> fail_cb(</div>
<div class="line"><a name="l00458"></a><span class="lineno"> 458</span>  Cgu::Callback::lambda<>([s_fail] () {s_fail();})</div>
<div class="line"><a name="l00459"></a><span class="lineno"> 459</span>  );</div>
<div class="line"><a name="l00460"></a><span class="lineno"> 460</span> </div>
<div class="line"><a name="l00461"></a><span class="lineno"> 461</span>  tm.<a class="code" href="classCgu_1_1Thread_1_1TaskManager.html#a81f7c8af3295d92c0e19d7f9498a4078">add_task</a>(std::move(task_cb), std::move(fail_cb));</div>
<div class="line"><a name="l00462"></a><span class="lineno"> 462</span>  }</div>
<div class="line"><a name="l00463"></a><span class="lineno"> 463</span>  </div>
<div class="line"><a name="l00464"></a><span class="lineno"> 464</span>  <a class="code" href="classCgu_1_1Thread_1_1Mutex_1_1Lock.html" title="A scoped locking class for exception safe Mutex locking. ">Mutex::Lock</a> l{mutex};</div>
<div class="line"><a name="l00465"></a><span class="lineno"> 465</span>  <span class="keywordflow">while</span> (start_count > done_count) cond.<a class="code" href="classCgu_1_1Thread_1_1Cond.html#a5eda52c227552555102bb45010a8f6c9">wait</a>(mutex);</div>
<div class="line"><a name="l00466"></a><span class="lineno"> 466</span>  <span class="keywordflow">if</span> (error) <span class="keywordflow">throw</span> <a class="code" href="structCgu_1_1Thread_1_1ParallelError.html">ParallelError</a>();</div>
<div class="line"><a name="l00467"></a><span class="lineno"> 467</span>  <span class="keywordflow">for</span> (DiffType index = 0; index < start_count; ++dest, ++index) {</div>
<div class="line"><a name="l00468"></a><span class="lineno"> 468</span>  *dest = std::move(results[index]);</div>
<div class="line"><a name="l00469"></a><span class="lineno"> 469</span>  }</div>
<div class="line"><a name="l00470"></a><span class="lineno"> 470</span> }</div>
<div class="line"><a name="l00471"></a><span class="lineno"> 471</span> <span class="comment"></span></div>
<div class="line"><a name="l00472"></a><span class="lineno"> 472</span> <span class="comment">/**</span></div>
<div class="line"><a name="l00473"></a><span class="lineno"> 473</span> <span class="comment"> * \#include <c++-gtk-utils/parallel.h></span></div>
<div class="line"><a name="l00474"></a><span class="lineno"> 474</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00475"></a><span class="lineno"> 475</span> <span class="comment"> * This function maps over two containers, one in the range ['first1',</span></div>
<div class="line"><a name="l00476"></a><span class="lineno"> 476</span> <span class="comment"> * 'last1') and the other beginning at 'first2', applying a binary</span></div>
<div class="line"><a name="l00477"></a><span class="lineno"> 477</span> <span class="comment"> * callable object to each element of the containers in those ranges</span></div>
<div class="line"><a name="l00478"></a><span class="lineno"> 478</span> <span class="comment"> * and storing the result in the destination range, by executing each</span></div>
<div class="line"><a name="l00479"></a><span class="lineno"> 479</span> <span class="comment"> * such application as a task of a Thread::TaskManager object. Tasks</span></div>
<div class="line"><a name="l00480"></a><span class="lineno"> 480</span> <span class="comment"> * are added to the Thread::TaskManager object in the order in which</span></div>
<div class="line"><a name="l00481"></a><span class="lineno"> 481</span> <span class="comment"> * the respective elements appear in the source containers, and the</span></div>
<div class="line"><a name="l00482"></a><span class="lineno"> 482</span> <span class="comment"> * final result appears in the destination container in the same order</span></div>
<div class="line"><a name="l00483"></a><span class="lineno"> 483</span> <span class="comment"> * as the source ranges from which it is generated (including if a</span></div>
<div class="line"><a name="l00484"></a><span class="lineno"> 484</span> <span class="comment"> * back_inserter iterator is used), but no other ordering arises, and</span></div>
<div class="line"><a name="l00485"></a><span class="lineno"> 485</span> <span class="comment"> * the tasks will execute in parallel to the extent that the</span></div>
<div class="line"><a name="l00486"></a><span class="lineno"> 486</span> <span class="comment"> * Thread::TaskManager object has sufficient threads available to do</span></div>
<div class="line"><a name="l00487"></a><span class="lineno"> 487</span> <span class="comment"> * so.</span></div>
<div class="line"><a name="l00488"></a><span class="lineno"> 488</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00489"></a><span class="lineno"> 489</span> <span class="comment"> * Apart from that, this function does the same as the version of</span></div>
<div class="line"><a name="l00490"></a><span class="lineno"> 490</span> <span class="comment"> * std::transform() taking a binary function, except that it returns</span></div>
<div class="line"><a name="l00491"></a><span class="lineno"> 491</span> <span class="comment"> * void (see Thread::parallel_transform_partial() for a function which</span></div>
<div class="line"><a name="l00492"></a><span class="lineno"> 492</span> <span class="comment"> * returns a destination iterator and iterators to the source ranges).</span></div>
<div class="line"><a name="l00493"></a><span class="lineno"> 493</span> <span class="comment"> * It will not return until the callable object has been applied to</span></div>
<div class="line"><a name="l00494"></a><span class="lineno"> 494</span> <span class="comment"> * all of the elements in the source ranges.</span></div>
<div class="line"><a name="l00495"></a><span class="lineno"> 495</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00496"></a><span class="lineno"> 496</span> <span class="comment"> * This function can be called by a task running on the same</span></div>
<div class="line"><a name="l00497"></a><span class="lineno"> 497</span> <span class="comment"> * TaskManager object (a result can therefore be delivered</span></div>
<div class="line"><a name="l00498"></a><span class="lineno"> 498</span> <span class="comment"> * asynchronously by calling this function in a task created by the</span></div>
<div class="line"><a name="l00499"></a><span class="lineno"> 499</span> <span class="comment"> * make_task_when(), make_task_compose() or make_task_when_full()</span></div>
<div class="line"><a name="l00500"></a><span class="lineno"> 500</span> <span class="comment"> * Thread::TaskManager methods). A task can carry out a map-reduce</span></div>
<div class="line"><a name="l00501"></a><span class="lineno"> 501</span> <span class="comment"> * operation by passing the result of calling this function to</span></div>
<div class="line"><a name="l00502"></a><span class="lineno"> 502</span> <span class="comment"> * std::accumulate() to perform a fold-left or fold-right on that</span></div>
<div class="line"><a name="l00503"></a><span class="lineno"> 503</span> <span class="comment"> * result.</span></div>
<div class="line"><a name="l00504"></a><span class="lineno"> 504</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00505"></a><span class="lineno"> 505</span> <span class="comment"> * A separate overload of this function takes a unary callable object.</span></div>
<div class="line"><a name="l00506"></a><span class="lineno"> 506</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00507"></a><span class="lineno"> 507</span> <span class="comment"> * Here is a trivial example of a map-reduce operation which maps over</span></div>
<div class="line"><a name="l00508"></a><span class="lineno"> 508</span> <span class="comment"> * two vectors by adding respective elements of the vectors in</span></div>
<div class="line"><a name="l00509"></a><span class="lineno"> 509</span> <span class="comment"> * separate tasks, and then folds-left using std::accumulate()</span></div>
<div class="line"><a name="l00510"></a><span class="lineno"> 510</span> <span class="comment"> * (std::accumulate() can fold using any callable object, but in this</span></div>
<div class="line"><a name="l00511"></a><span class="lineno"> 511</span> <span class="comment"> * example the default of addition is used):</span></div>
<div class="line"><a name="l00512"></a><span class="lineno"> 512</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00513"></a><span class="lineno"> 513</span> <span class="comment"> * @code</span></div>
<div class="line"><a name="l00514"></a><span class="lineno"> 514</span> <span class="comment"> * using namespace Cgu;</span></div>
<div class="line"><a name="l00515"></a><span class="lineno"> 515</span> <span class="comment"> * std::vector<int> v1{2, 4, 6, 8, 10};</span></div>
<div class="line"><a name="l00516"></a><span class="lineno"> 516</span> <span class="comment"> * std::vector<int> v2{10, 20, 30, 40, 50};</span></div>
<div class="line"><a name="l00517"></a><span class="lineno"> 517</span> <span class="comment"> * std::vector<int> v3;</span></div>
<div class="line"><a name="l00518"></a><span class="lineno"> 518</span> <span class="comment"> * Thread::TaskManager tm;</span></div>
<div class="line"><a name="l00519"></a><span class="lineno"> 519</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00520"></a><span class="lineno"> 520</span> <span class="comment"> * Thread::parallel_transform(tm,</span></div>
<div class="line"><a name="l00521"></a><span class="lineno"> 521</span> <span class="comment"> * v1.begin(),</span></div>
<div class="line"><a name="l00522"></a><span class="lineno"> 522</span> <span class="comment"> * v1.end(),</span></div>
<div class="line"><a name="l00523"></a><span class="lineno"> 523</span> <span class="comment"> * v2.begin(),</span></div>
<div class="line"><a name="l00524"></a><span class="lineno"> 524</span> <span class="comment"> * std::back_inserter(v3),</span></div>
<div class="line"><a name="l00525"></a><span class="lineno"> 525</span> <span class="comment"> * std::plus<int>());</span></div>
<div class="line"><a name="l00526"></a><span class="lineno"> 526</span> <span class="comment"> * // res will be equal to 180</span></div>
<div class="line"><a name="l00527"></a><span class="lineno"> 527</span> <span class="comment"> * int res = std::accumulate(v3.begin(), v3.end(), 0);</span></div>
<div class="line"><a name="l00528"></a><span class="lineno"> 528</span> <span class="comment"> * @endcode</span></div>
<div class="line"><a name="l00529"></a><span class="lineno"> 529</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00530"></a><span class="lineno"> 530</span> <span class="comment"> * @param tm The Thread::TaskManager object on which the tasks will</span></div>
<div class="line"><a name="l00531"></a><span class="lineno"> 531</span> <span class="comment"> * run.</span></div>
<div class="line"><a name="l00532"></a><span class="lineno"> 532</span> <span class="comment"> * @param first1 The beginning of the range which is to be passed as</span></div>
<div class="line"><a name="l00533"></a><span class="lineno"> 533</span> <span class="comment"> * the first argument of 'func'.</span></div>
<div class="line"><a name="l00534"></a><span class="lineno"> 534</span> <span class="comment"> * @param last1 One past the last element of the range which is to be</span></div>
<div class="line"><a name="l00535"></a><span class="lineno"> 535</span> <span class="comment"> * passed as the first argument of 'func'.</span></div>
<div class="line"><a name="l00536"></a><span class="lineno"> 536</span> <span class="comment"> * @param first2 The beginning of the range which is to be passed as</span></div>
<div class="line"><a name="l00537"></a><span class="lineno"> 537</span> <span class="comment"> * the second argument of 'func'.</span></div>
<div class="line"><a name="l00538"></a><span class="lineno"> 538</span> <span class="comment"> * @param dest The beginning of the range to which the result of</span></div>
<div class="line"><a name="l00539"></a><span class="lineno"> 539</span> <span class="comment"> * applying 'func' to the elements in the source ranges is to be</span></div>
<div class="line"><a name="l00540"></a><span class="lineno"> 540</span> <span class="comment"> * stored. As in the case of std::transform, this can overlap with or</span></div>
<div class="line"><a name="l00541"></a><span class="lineno"> 541</span> <span class="comment"> * be the same as one of the source ranges. It may also be an insert</span></div>
<div class="line"><a name="l00542"></a><span class="lineno"> 542</span> <span class="comment"> * iterator.</span></div>
<div class="line"><a name="l00543"></a><span class="lineno"> 543</span> <span class="comment"> * @param func A binary callable object to be applied to each element</span></div>
<div class="line"><a name="l00544"></a><span class="lineno"> 544</span> <span class="comment"> * in the source ranges, such as formed by a lambda expression or the</span></div>
<div class="line"><a name="l00545"></a><span class="lineno"> 545</span> <span class="comment"> * result of std::bind. It should take two unbound arguments of the</span></div>
<div class="line"><a name="l00546"></a><span class="lineno"> 546</span> <span class="comment"> * value types of the containers to which 'first1' and 'first2' relate</span></div>
<div class="line"><a name="l00547"></a><span class="lineno"> 547</span> <span class="comment"> * or const or non-const references to those types. If an exception</span></div>
<div class="line"><a name="l00548"></a><span class="lineno"> 548</span> <span class="comment"> * propagates from 'func', the exception will be consumed while the</span></div>
<div class="line"><a name="l00549"></a><span class="lineno"> 549</span> <span class="comment"> * transform loop is running, and an attempt will still be made to</span></div>
<div class="line"><a name="l00550"></a><span class="lineno"> 550</span> <span class="comment"> * apply 'func' to all remaining elements of the source ranges, and</span></div>
<div class="line"><a name="l00551"></a><span class="lineno"> 551</span> <span class="comment"> * only after that attempt has completed will the exception</span></div>
<div class="line"><a name="l00552"></a><span class="lineno"> 552</span> <span class="comment"> * Cgu::Thread::ParallelError be thrown.</span></div>
<div class="line"><a name="l00553"></a><span class="lineno"> 553</span> <span class="comment"> * @exception std::bad_alloc This exception will be thrown if memory</span></div>
<div class="line"><a name="l00554"></a><span class="lineno"> 554</span> <span class="comment"> * is exhausted and the system throws in that case. (On systems with</span></div>
<div class="line"><a name="l00555"></a><span class="lineno"> 555</span> <span class="comment"> * over-commit/lazy-commit combined with virtual memory (swap), it is</span></div>
<div class="line"><a name="l00556"></a><span class="lineno"> 556</span> <span class="comment"> * rarely useful to check for memory exhaustion). If this exception</span></div>
<div class="line"><a name="l00557"></a><span class="lineno"> 557</span> <span class="comment"> * is thrown, some tasks may nonetheless have already started by</span></div>
<div class="line"><a name="l00558"></a><span class="lineno"> 558</span> <span class="comment"> * virtue of the call to this function, but subsequent ones will not.</span></div>
<div class="line"><a name="l00559"></a><span class="lineno"> 559</span> <span class="comment"> * @exception Cgu::Thread::TaskError This exception will be thrown if</span></div>
<div class="line"><a name="l00560"></a><span class="lineno"> 560</span> <span class="comment"> * stop_all() has previously been called on the Thread::TaskManager</span></div>
<div class="line"><a name="l00561"></a><span class="lineno"> 561</span> <span class="comment"> * object, or if another thread calls stop_all() after this method is</span></div>
<div class="line"><a name="l00562"></a><span class="lineno"> 562</span> <span class="comment"> * called but before it has returned. It will also be thrown if the</span></div>
<div class="line"><a name="l00563"></a><span class="lineno"> 563</span> <span class="comment"> * Thread::TaskManager object's is_error() method would return true</span></div>
<div class="line"><a name="l00564"></a><span class="lineno"> 564</span> <span class="comment"> * because its internal thread pool loop implementation has thrown</span></div>
<div class="line"><a name="l00565"></a><span class="lineno"> 565</span> <span class="comment"> * std::bad_alloc, or a thread has failed to start correctly because</span></div>
<div class="line"><a name="l00566"></a><span class="lineno"> 566</span> <span class="comment"> * pthread has run out of resources. (On systems with</span></div>
<div class="line"><a name="l00567"></a><span class="lineno"> 567</span> <span class="comment"> * over-commit/lazy-commit combined with virtual memory (swap), it is</span></div>
<div class="line"><a name="l00568"></a><span class="lineno"> 568</span> <span class="comment"> * rarely useful to check for memory exhaustion, and if a reasonable</span></div>
<div class="line"><a name="l00569"></a><span class="lineno"> 569</span> <span class="comment"> * maximum thread count has been chosen for the Thread::TaskManager</span></div>
<div class="line"><a name="l00570"></a><span class="lineno"> 570</span> <span class="comment"> * object pthread should not run out of other resources, but there may</span></div>
<div class="line"><a name="l00571"></a><span class="lineno"> 571</span> <span class="comment"> * be some specialized cases where the return value of is_error() is</span></div>
<div class="line"><a name="l00572"></a><span class="lineno"> 572</span> <span class="comment"> * useful.) If this exception is thrown, some tasks may nonetheless</span></div>
<div class="line"><a name="l00573"></a><span class="lineno"> 573</span> <span class="comment"> * have already started by virtue of the call to this function.</span></div>
<div class="line"><a name="l00574"></a><span class="lineno"> 574</span> <span class="comment"> * @exception Cgu::Thread::ParallelError This exception will be thrown</span></div>
<div class="line"><a name="l00575"></a><span class="lineno"> 575</span> <span class="comment"> * if an exception propagates from the 'func' callable object when it</span></div>
<div class="line"><a name="l00576"></a><span class="lineno"> 576</span> <span class="comment"> * executes on being applied to one or more elements of the source</span></div>
<div class="line"><a name="l00577"></a><span class="lineno"> 577</span> <span class="comment"> * ranges. Such an exception will not stop an attempt being made to</span></div>
<div class="line"><a name="l00578"></a><span class="lineno"> 578</span> <span class="comment"> * apply 'func' (successfully or unsuccessfully) to all elements in</span></div>
<div class="line"><a name="l00579"></a><span class="lineno"> 579</span> <span class="comment"> * the source ranges. Cgu::Thread::ParallelError will be thrown after</span></div>
<div class="line"><a name="l00580"></a><span class="lineno"> 580</span> <span class="comment"> * such attempted application has finished.</span></div>
<div class="line"><a name="l00581"></a><span class="lineno"> 581</span> <span class="comment"> * @exception Cgu::Thread::MutexError This exception will be thrown if</span></div>
<div class="line"><a name="l00582"></a><span class="lineno"> 582</span> <span class="comment"> * initialization of a mutex used by this function fails. (It is</span></div>
<div class="line"><a name="l00583"></a><span class="lineno"> 583</span> <span class="comment"> * often not worth checking for this, as it means either memory is</span></div>
<div class="line"><a name="l00584"></a><span class="lineno"> 584</span> <span class="comment"> * exhausted or pthread has run out of other resources to create new</span></div>
<div class="line"><a name="l00585"></a><span class="lineno"> 585</span> <span class="comment"> * mutexes.) If this exception is thrown, no tasks will start.</span></div>
<div class="line"><a name="l00586"></a><span class="lineno"> 586</span> <span class="comment"> * @exception Cgu::Thread::CondError This exception will be thrown if</span></div>
<div class="line"><a name="l00587"></a><span class="lineno"> 587</span> <span class="comment"> * initialization of a condition variable used by this function fails.</span></div>
<div class="line"><a name="l00588"></a><span class="lineno"> 588</span> <span class="comment"> * (It is often not worth checking for this, as it means either memory</span></div>
<div class="line"><a name="l00589"></a><span class="lineno"> 589</span> <span class="comment"> * is exhausted or pthread has run out of other resources to create</span></div>
<div class="line"><a name="l00590"></a><span class="lineno"> 590</span> <span class="comment"> * new condition variables.) If this exception is thrown, no tasks</span></div>
<div class="line"><a name="l00591"></a><span class="lineno"> 591</span> <span class="comment"> * will start.</span></div>
<div class="line"><a name="l00592"></a><span class="lineno"> 592</span> <span class="comment"> * @note An exception might also be thrown if the copy or move</span></div>
<div class="line"><a name="l00593"></a><span class="lineno"> 593</span> <span class="comment"> * constructor of the 'func' callable objects throws. If such an</span></div>
<div class="line"><a name="l00594"></a><span class="lineno"> 594</span> <span class="comment"> * exception is thrown, no tasks will start.</span></div>
<div class="line"><a name="l00595"></a><span class="lineno"> 595</span> <span class="comment"> * </span></div>
<div class="line"><a name="l00596"></a><span class="lineno"> 596</span> <span class="comment"> * Since 2.0.19/2.2.2</span></div>
<div class="line"><a name="l00597"></a><span class="lineno"> 597</span> <span class="comment"> */</span></div>
<div class="line"><a name="l00598"></a><span class="lineno"> 598</span> <span class="keyword">template</span> <<span class="keyword">class</span> SourceIterator1, <span class="keyword">class</span> SourceIterator2, <span class="keyword">class</span> DestIterator, <span class="keyword">class</span> Func></div>
<div class="line"><a name="l00599"></a><span class="lineno"><a class="code" href="namespaceCgu_1_1Thread.html#a219127851a3a7578668b7ac0e155441d"> 599</a></span> <span class="keywordtype">void</span> <a class="code" href="namespaceCgu_1_1Thread.html#a497aa47446b79c87f1a404e11151a942">parallel_transform</a>(<a class="code" href="classCgu_1_1Thread_1_1TaskManager.html" title="A thread-pool class for managing tasks in multi-threaded programs. ">TaskManager</a>& tm,</div>
<div class="line"><a name="l00600"></a><span class="lineno"> 600</span>  SourceIterator1 first1,</div>
<div class="line"><a name="l00601"></a><span class="lineno"> 601</span>  SourceIterator1 last1,</div>
<div class="line"><a name="l00602"></a><span class="lineno"> 602</span>  SourceIterator2 first2,</div>
<div class="line"><a name="l00603"></a><span class="lineno"> 603</span>  DestIterator dest,</div>
<div class="line"><a name="l00604"></a><span class="lineno"> 604</span>  Func&& func) {</div>
<div class="line"><a name="l00605"></a><span class="lineno"> 605</span> </div>
<div class="line"><a name="l00606"></a><span class="lineno"> 606</span>  <span class="keywordflow">if</span> (first1 == last1) <span class="keywordflow">return</span>;</div>
<div class="line"><a name="l00607"></a><span class="lineno"> 607</span> </div>
<div class="line"><a name="l00608"></a><span class="lineno"> 608</span>  <span class="keyword">typedef</span> <span class="keyword">typename</span> std::iterator_traits<SourceIterator1>::value_type Arg1Type;</div>
<div class="line"><a name="l00609"></a><span class="lineno"> 609</span>  <span class="keyword">typedef</span> <span class="keyword">typename</span> std::iterator_traits<SourceIterator1>::difference_type DiffType;</div>
<div class="line"><a name="l00610"></a><span class="lineno"> 610</span>  <span class="keyword">typedef</span> <span class="keyword">typename</span> std::iterator_traits<SourceIterator2>::value_type Arg2Type;</div>
<div class="line"><a name="l00611"></a><span class="lineno"> 611</span>  <span class="keyword">typedef</span> <span class="keyword">typename</span> std::remove_const<typename std::remove_reference<Func>::type>::type FType;</div>
<div class="line"><a name="l00612"></a><span class="lineno"> 612</span>  <span class="keyword">typedef</span> decltype(func(*first1, *first2)) DestType;</div>
<div class="line"><a name="l00613"></a><span class="lineno"> 613</span> </div>
<div class="line"><a name="l00614"></a><span class="lineno"> 614</span>  <a class="code" href="classCgu_1_1Thread_1_1Mutex.html" title="A wrapper class for pthread mutexes. ">Mutex</a> mutex;</div>
<div class="line"><a name="l00615"></a><span class="lineno"> 615</span>  <a class="code" href="classCgu_1_1Thread_1_1Cond.html" title="A wrapper class for pthread condition variables. ">Cond</a> cond;</div>
<div class="line"><a name="l00616"></a><span class="lineno"> 616</span>  DiffType start_count = 0;</div>
<div class="line"><a name="l00617"></a><span class="lineno"> 617</span>  DiffType done_count = 0;</div>
<div class="line"><a name="l00618"></a><span class="lineno"> 618</span>  <span class="keywordtype">bool</span> error = <span class="keyword">false</span>;</div>
<div class="line"><a name="l00619"></a><span class="lineno"> 619</span> </div>
<div class="line"><a name="l00620"></a><span class="lineno"> 620</span>  <span class="comment">// intermediate results have to be held in an array so destination</span></div>
<div class="line"><a name="l00621"></a><span class="lineno"> 621</span>  <span class="comment">// ordering can be enforced when using insert interators. This</span></div>
<div class="line"><a name="l00622"></a><span class="lineno"> 622</span>  <span class="comment">// causes some inefficiency for non-random access iterators</span></div>
<div class="line"><a name="l00623"></a><span class="lineno"> 623</span>  std::unique_ptr<DestType[]> results(<span class="keyword">new</span> DestType[std::distance(first1, last1)]);</div>
<div class="line"><a name="l00624"></a><span class="lineno"> 624</span> </div>
<div class="line"><a name="l00625"></a><span class="lineno"> 625</span>  <span class="comment">// construct SafeFunctorArg objects so that they can be shared</span></div>
<div class="line"><a name="l00626"></a><span class="lineno"> 626</span>  <span class="comment">// between different tasks</span></div>
<div class="line"><a name="l00627"></a><span class="lineno"> 627</span>  <a class="code" href="classCgu_1_1Callback_1_1SafeFunctorArg.html" title="Functor class holding a Callback::CallbackArg object, with thread-safe reference count. ">Cgu::Callback::SafeFunctorArg<Arg1Type&, Arg2Type&, DestType&></a> s_task{</div>
<div class="line"><a name="l00628"></a><span class="lineno"> 628</span>  <a class="code" href="namespaceCgu_1_1Callback.html#a94b122ac99f423928320240fd48d571b">Cgu::Callback::make_ref</a>(&ParallelHelper2::transform2_func<FType, Arg1Type, Arg2Type, DestType>,</div>
<div class="line"><a name="l00629"></a><span class="lineno"> 629</span>  std::forward<Func>(func))</div>
<div class="line"><a name="l00630"></a><span class="lineno"> 630</span>  };</div>
<div class="line"><a name="l00631"></a><span class="lineno"> 631</span>  <a class="code" href="classCgu_1_1Callback_1_1SafeFunctorArg.html" title="Functor class holding a Callback::CallbackArg object, with thread-safe reference count. ">Cgu::Callback::SafeFunctor</a> s_fail{</div>
<div class="line"><a name="l00632"></a><span class="lineno"> 632</span>  <a class="code" href="namespaceCgu_1_1Callback.html#a3e32d4f4961c618aa7e03bda00f398b8">Cgu::Callback::make</a>(&ParallelHelper2::fail_func<DiffType>,</div>
<div class="line"><a name="l00633"></a><span class="lineno"> 633</span>  &mutex,</div>
<div class="line"><a name="l00634"></a><span class="lineno"> 634</span>  &cond,</div>
<div class="line"><a name="l00635"></a><span class="lineno"> 635</span>  &error,</div>
<div class="line"><a name="l00636"></a><span class="lineno"> 636</span>  &done_count)</div>
<div class="line"><a name="l00637"></a><span class="lineno"> 637</span>  };</div>
<div class="line"><a name="l00638"></a><span class="lineno"> 638</span> </div>
<div class="line"><a name="l00639"></a><span class="lineno"> 639</span>  <span class="keywordflow">for</span> (; first1 != last1; ++first1, ++first2, ++start_count) {</div>
<div class="line"><a name="l00640"></a><span class="lineno"> 640</span>  std::unique_ptr<const Cgu::Callback::Callback> task_cb(</div>
<div class="line"><a name="l00641"></a><span class="lineno"> 641</span>  Cgu::Callback::lambda<>(std::bind(&ParallelHelper2::transform2_cb_func<Arg1Type, Arg2Type, DestType, DiffType, SourceIterator1, SourceIterator2>,</div>
<div class="line"><a name="l00642"></a><span class="lineno"> 642</span>  s_task,</div>
<div class="line"><a name="l00643"></a><span class="lineno"> 643</span>  first1,</div>
<div class="line"><a name="l00644"></a><span class="lineno"> 644</span>  first2,</div>
<div class="line"><a name="l00645"></a><span class="lineno"> 645</span>  &mutex,</div>
<div class="line"><a name="l00646"></a><span class="lineno"> 646</span>  &cond,</div>
<div class="line"><a name="l00647"></a><span class="lineno"> 647</span>  &done_count,</div>
<div class="line"><a name="l00648"></a><span class="lineno"> 648</span>  results.get(),</div>
<div class="line"><a name="l00649"></a><span class="lineno"> 649</span>  start_count))</div>
<div class="line"><a name="l00650"></a><span class="lineno"> 650</span>  );</div>
<div class="line"><a name="l00651"></a><span class="lineno"> 651</span>  std::unique_ptr<const Cgu::Callback::Callback> fail_cb(</div>
<div class="line"><a name="l00652"></a><span class="lineno"> 652</span>  Cgu::Callback::lambda<>([s_fail] () {s_fail();})</div>
<div class="line"><a name="l00653"></a><span class="lineno"> 653</span>  );</div>
<div class="line"><a name="l00654"></a><span class="lineno"> 654</span> </div>
<div class="line"><a name="l00655"></a><span class="lineno"> 655</span>  tm.<a class="code" href="classCgu_1_1Thread_1_1TaskManager.html#a81f7c8af3295d92c0e19d7f9498a4078">add_task</a>(std::move(task_cb), std::move(fail_cb));</div>
<div class="line"><a name="l00656"></a><span class="lineno"> 656</span>  }</div>
<div class="line"><a name="l00657"></a><span class="lineno"> 657</span>  </div>
<div class="line"><a name="l00658"></a><span class="lineno"> 658</span>  <a class="code" href="classCgu_1_1Thread_1_1Mutex_1_1Lock.html" title="A scoped locking class for exception safe Mutex locking. ">Mutex::Lock</a> l{mutex};</div>
<div class="line"><a name="l00659"></a><span class="lineno"> 659</span>  <span class="keywordflow">while</span> (start_count > done_count) cond.<a class="code" href="classCgu_1_1Thread_1_1Cond.html#a5eda52c227552555102bb45010a8f6c9">wait</a>(mutex);</div>
<div class="line"><a name="l00660"></a><span class="lineno"> 660</span>  <span class="keywordflow">if</span> (error) <span class="keywordflow">throw</span> <a class="code" href="structCgu_1_1Thread_1_1ParallelError.html">ParallelError</a>();</div>
<div class="line"><a name="l00661"></a><span class="lineno"> 661</span>  <span class="keywordflow">for</span> (DiffType index = 0; index < start_count; ++dest, ++index) {</div>
<div class="line"><a name="l00662"></a><span class="lineno"> 662</span>  *dest = std::move(results[index]);</div>
<div class="line"><a name="l00663"></a><span class="lineno"> 663</span>  }</div>
<div class="line"><a name="l00664"></a><span class="lineno"> 664</span> }</div>
<div class="line"><a name="l00665"></a><span class="lineno"> 665</span> <span class="comment"></span></div>
<div class="line"><a name="l00666"></a><span class="lineno"> 666</span> <span class="comment">/**</span></div>
<div class="line"><a name="l00667"></a><span class="lineno"> 667</span> <span class="comment"> * \#include <c++-gtk-utils/parallel.h></span></div>
<div class="line"><a name="l00668"></a><span class="lineno"> 668</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00669"></a><span class="lineno"> 669</span> <span class="comment"> * This function applies a callable object to each element of a</span></div>
<div class="line"><a name="l00670"></a><span class="lineno"> 670</span> <span class="comment"> * container in the range ['first', 'last') subject to a maximum, by</span></div>
<div class="line"><a name="l00671"></a><span class="lineno"> 671</span> <span class="comment"> * executing each such application as a task of a Thread::TaskManager</span></div>
<div class="line"><a name="l00672"></a><span class="lineno"> 672</span> <span class="comment"> * object. Tasks are added to the Thread::TaskManager object in the</span></div>
<div class="line"><a name="l00673"></a><span class="lineno"> 673</span> <span class="comment"> * order in which the respective elements appear in the container (and</span></div>
<div class="line"><a name="l00674"></a><span class="lineno"> 674</span> <span class="comment"> * if a task mutates its argument, it will do so in respect of the</span></div>
<div class="line"><a name="l00675"></a><span class="lineno"> 675</span> <span class="comment"> * correct element of the container), but no other ordering arises,</span></div>
<div class="line"><a name="l00676"></a><span class="lineno"> 676</span> <span class="comment"> * and the tasks will execute in parallel to the extent that the</span></div>
<div class="line"><a name="l00677"></a><span class="lineno"> 677</span> <span class="comment"> * Thread::TaskManager object has sufficient threads available to do</span></div>
<div class="line"><a name="l00678"></a><span class="lineno"> 678</span> <span class="comment"> * so.</span></div>
<div class="line"><a name="l00679"></a><span class="lineno"> 679</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00680"></a><span class="lineno"> 680</span> <span class="comment"> * This function does the same as Thread::parallel_for_each(), except</span></div>
<div class="line"><a name="l00681"></a><span class="lineno"> 681</span> <span class="comment"> * that it returns an iterator to the element past the last element to</span></div>
<div class="line"><a name="l00682"></a><span class="lineno"> 682</span> <span class="comment"> * which the callable object has been applied, and it has a 'max'</span></div>
<div class="line"><a name="l00683"></a><span class="lineno"> 683</span> <span class="comment"> * parameter to limit the maximum number of elements to which the</span></div>
<div class="line"><a name="l00684"></a><span class="lineno"> 684</span> <span class="comment"> * callable object will be applied on any one call to this function</span></div>
<div class="line"><a name="l00685"></a><span class="lineno"> 685</span> <span class="comment"> * even if the range ['first', 'last') is greater than this maximum.</span></div>
<div class="line"><a name="l00686"></a><span class="lineno"> 686</span> <span class="comment"> * Whether this limitation has had effect on any one call can be</span></div>
<div class="line"><a name="l00687"></a><span class="lineno"> 687</span> <span class="comment"> * tested by checking whether the return value is equal to the 'last'</span></div>
<div class="line"><a name="l00688"></a><span class="lineno"> 688</span> <span class="comment"> * parameter. If it is not, a further call to this function can be</span></div>
<div class="line"><a name="l00689"></a><span class="lineno"> 689</span> <span class="comment"> * made.</span></div>
<div class="line"><a name="l00690"></a><span class="lineno"> 690</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00691"></a><span class="lineno"> 691</span> <span class="comment"> * The main purpose of this additional function is to enable the</span></div>
<div class="line"><a name="l00692"></a><span class="lineno"> 692</span> <span class="comment"> * application of the callable object to the elements of a container</span></div>
<div class="line"><a name="l00693"></a><span class="lineno"> 693</span> <span class="comment"> * to be dealt with in chunks, possibly to enable other tasks to be</span></div>
<div class="line"><a name="l00694"></a><span class="lineno"> 694</span> <span class="comment"> * interleaved at reasonable intervals. For a container which does</span></div>
<div class="line"><a name="l00695"></a><span class="lineno"> 695</span> <span class="comment"> * not support random access iterators, the 'last' parameter can be</span></div>
<div class="line"><a name="l00696"></a><span class="lineno"> 696</span> <span class="comment"> * set to, say, the end of the container and the chunk size set with</span></div>
<div class="line"><a name="l00697"></a><span class="lineno"> 697</span> <span class="comment"> * the 'max' paramater, with the return value being used as the</span></div>
<div class="line"><a name="l00698"></a><span class="lineno"> 698</span> <span class="comment"> * 'first' parameter for subsequent calls to this function. This</span></div>
<div class="line"><a name="l00699"></a><span class="lineno"> 699</span> <span class="comment"> * avoids having to increment the iterator for each "chunk" by</span></div>
<div class="line"><a name="l00700"></a><span class="lineno"> 700</span> <span class="comment"> * stepping through the container by hand. In this usage, it</span></div>
<div class="line"><a name="l00701"></a><span class="lineno"> 701</span> <span class="comment"> * therefore represents a minor efficiency improvement.</span></div>
<div class="line"><a name="l00702"></a><span class="lineno"> 702</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00703"></a><span class="lineno"> 703</span> <span class="comment"> * @param tm The Thread::TaskManager object on which the tasks will</span></div>
<div class="line"><a name="l00704"></a><span class="lineno"> 704</span> <span class="comment"> * run.</span></div>
<div class="line"><a name="l00705"></a><span class="lineno"> 705</span> <span class="comment"> * @param first The beginning of the range to which 'func' is to be</span></div>
<div class="line"><a name="l00706"></a><span class="lineno"> 706</span> <span class="comment"> * applied.</span></div>
<div class="line"><a name="l00707"></a><span class="lineno"> 707</span> <span class="comment"> * @param last One past the last element to which 'func' is to be</span></div>
<div class="line"><a name="l00708"></a><span class="lineno"> 708</span> <span class="comment"> * applied, subject to any maximum specified as the 'max' parameter.</span></div>
<div class="line"><a name="l00709"></a><span class="lineno"> 709</span> <span class="comment"> * @param max The maximum number of elements of the source container</span></div>
<div class="line"><a name="l00710"></a><span class="lineno"> 710</span> <span class="comment"> * to which 'func' will be applied on this call. It is not an error</span></div>
<div class="line"><a name="l00711"></a><span class="lineno"> 711</span> <span class="comment"> * if it is greater than the distance between 'first' and 'last'. If</span></div>
<div class="line"><a name="l00712"></a><span class="lineno"> 712</span> <span class="comment"> * it is equal to or greater than that distance, it follows that the</span></div>
<div class="line"><a name="l00713"></a><span class="lineno"> 713</span> <span class="comment"> * iterator returned will be equal to 'last'. The same results if</span></div>
<div class="line"><a name="l00714"></a><span class="lineno"> 714</span> <span class="comment"> * 'max' is a negative number (in that case no maximum will take</span></div>
<div class="line"><a name="l00715"></a><span class="lineno"> 715</span> <span class="comment"> * effect and each element in the range ['first', 'last') will have</span></div>
<div class="line"><a name="l00716"></a><span class="lineno"> 716</span> <span class="comment"> * 'func' applied to it).</span></div>
<div class="line"><a name="l00717"></a><span class="lineno"> 717</span> <span class="comment"> * @param func A callable object to be applied (subject to the</span></div>
<div class="line"><a name="l00718"></a><span class="lineno"> 718</span> <span class="comment"> * maximum) to each element in the range ['first', 'last'), such as</span></div>
<div class="line"><a name="l00719"></a><span class="lineno"> 719</span> <span class="comment"> * formed by a lambda expression or the result of std::bind. It</span></div>
<div class="line"><a name="l00720"></a><span class="lineno"> 720</span> <span class="comment"> * should take a single unbound argument of the value type of the</span></div>
<div class="line"><a name="l00721"></a><span class="lineno"> 721</span> <span class="comment"> * container to which 'first' and 'last' relate or a const or</span></div>
<div class="line"><a name="l00722"></a><span class="lineno"> 722</span> <span class="comment"> * non-const reference to that type. Any return value is discarded.</span></div>
<div class="line"><a name="l00723"></a><span class="lineno"> 723</span> <span class="comment"> * If an exception propagates from 'func', the exception will be</span></div>
<div class="line"><a name="l00724"></a><span class="lineno"> 724</span> <span class="comment"> * consumed while the for each loop is running, and an attempt will</span></div>
<div class="line"><a name="l00725"></a><span class="lineno"> 725</span> <span class="comment"> * still be made to apply 'func' to all remaining elements in the</span></div>
<div class="line"><a name="l00726"></a><span class="lineno"> 726</span> <span class="comment"> * range ['first', 'last') subject to the maximum, and only after that</span></div>
<div class="line"><a name="l00727"></a><span class="lineno"> 727</span> <span class="comment"> * attempt has completed will the exception Cgu::Thread::ParallelError</span></div>
<div class="line"><a name="l00728"></a><span class="lineno"> 728</span> <span class="comment"> * be thrown.</span></div>
<div class="line"><a name="l00729"></a><span class="lineno"> 729</span> <span class="comment"> * @return An iterator representing the element past the last element</span></div>
<div class="line"><a name="l00730"></a><span class="lineno"> 730</span> <span class="comment"> * of the range to which 'func' was applied, which may be passed as</span></div>
<div class="line"><a name="l00731"></a><span class="lineno"> 731</span> <span class="comment"> * the 'first' argument of a subsequent call to this function.</span></div>
<div class="line"><a name="l00732"></a><span class="lineno"> 732</span> <span class="comment"> * @exception std::bad_alloc This exception will be thrown if memory</span></div>
<div class="line"><a name="l00733"></a><span class="lineno"> 733</span> <span class="comment"> * is exhausted and the system throws in that case. (On systems with</span></div>
<div class="line"><a name="l00734"></a><span class="lineno"> 734</span> <span class="comment"> * over-commit/lazy-commit combined with virtual memory (swap), it is</span></div>
<div class="line"><a name="l00735"></a><span class="lineno"> 735</span> <span class="comment"> * rarely useful to check for memory exhaustion). If this exception</span></div>
<div class="line"><a name="l00736"></a><span class="lineno"> 736</span> <span class="comment"> * is thrown, some tasks may nonetheless have already started by</span></div>
<div class="line"><a name="l00737"></a><span class="lineno"> 737</span> <span class="comment"> * virtue of the call to this function, but subsequent ones will not.</span></div>
<div class="line"><a name="l00738"></a><span class="lineno"> 738</span> <span class="comment"> * @exception Cgu::Thread::TaskError This exception will be thrown if</span></div>
<div class="line"><a name="l00739"></a><span class="lineno"> 739</span> <span class="comment"> * stop_all() has previously been called on the Thread::TaskManager</span></div>
<div class="line"><a name="l00740"></a><span class="lineno"> 740</span> <span class="comment"> * object, or if another thread calls stop_all() after this method is</span></div>
<div class="line"><a name="l00741"></a><span class="lineno"> 741</span> <span class="comment"> * called but before it has returned. It will also be thrown if the</span></div>
<div class="line"><a name="l00742"></a><span class="lineno"> 742</span> <span class="comment"> * Thread::TaskManager object's is_error() method would return true</span></div>
<div class="line"><a name="l00743"></a><span class="lineno"> 743</span> <span class="comment"> * because its internal thread pool loop implementation has thrown</span></div>
<div class="line"><a name="l00744"></a><span class="lineno"> 744</span> <span class="comment"> * std::bad_alloc, or a thread has failed to start correctly because</span></div>
<div class="line"><a name="l00745"></a><span class="lineno"> 745</span> <span class="comment"> * pthread has run out of resources. (On systems with</span></div>
<div class="line"><a name="l00746"></a><span class="lineno"> 746</span> <span class="comment"> * over-commit/lazy-commit combined with virtual memory (swap), it is</span></div>
<div class="line"><a name="l00747"></a><span class="lineno"> 747</span> <span class="comment"> * rarely useful to check for memory exhaustion, and if a reasonable</span></div>
<div class="line"><a name="l00748"></a><span class="lineno"> 748</span> <span class="comment"> * maximum thread count has been chosen for the Thread::TaskManager</span></div>
<div class="line"><a name="l00749"></a><span class="lineno"> 749</span> <span class="comment"> * object pthread should not run out of other resources, but there may</span></div>
<div class="line"><a name="l00750"></a><span class="lineno"> 750</span> <span class="comment"> * be some specialized cases where the return value of is_error() is</span></div>
<div class="line"><a name="l00751"></a><span class="lineno"> 751</span> <span class="comment"> * useful.) If this exception is thrown, some tasks may nonetheless</span></div>
<div class="line"><a name="l00752"></a><span class="lineno"> 752</span> <span class="comment"> * have already started by virtue of the call to this function.</span></div>
<div class="line"><a name="l00753"></a><span class="lineno"> 753</span> <span class="comment"> * @exception Cgu::Thread::ParallelError This exception will be thrown</span></div>
<div class="line"><a name="l00754"></a><span class="lineno"> 754</span> <span class="comment"> * if an exception propagates from the 'func' callable object when it</span></div>
<div class="line"><a name="l00755"></a><span class="lineno"> 755</span> <span class="comment"> * executes on being applied to one or more elements of the container.</span></div>
<div class="line"><a name="l00756"></a><span class="lineno"> 756</span> <span class="comment"> * Such an exception will not stop an attempt being made to apply</span></div>
<div class="line"><a name="l00757"></a><span class="lineno"> 757</span> <span class="comment"> * 'func' (successfully or unsuccessfully) to all elements in the</span></div>
<div class="line"><a name="l00758"></a><span class="lineno"> 758</span> <span class="comment"> * range ['first', 'last') subject to the maximum.</span></div>
<div class="line"><a name="l00759"></a><span class="lineno"> 759</span> <span class="comment"> * Cgu::Thread::ParallelError will be thrown after such attempted</span></div>
<div class="line"><a name="l00760"></a><span class="lineno"> 760</span> <span class="comment"> * application has finished.</span></div>
<div class="line"><a name="l00761"></a><span class="lineno"> 761</span> <span class="comment"> * @exception Cgu::Thread::MutexError This exception will be thrown if</span></div>
<div class="line"><a name="l00762"></a><span class="lineno"> 762</span> <span class="comment"> * initialization of a mutex used by this function fails. (It is</span></div>
<div class="line"><a name="l00763"></a><span class="lineno"> 763</span> <span class="comment"> * often not worth checking for this, as it means either memory is</span></div>
<div class="line"><a name="l00764"></a><span class="lineno"> 764</span> <span class="comment"> * exhausted or pthread has run out of other resources to create new</span></div>
<div class="line"><a name="l00765"></a><span class="lineno"> 765</span> <span class="comment"> * mutexes.) If this exception is thrown, no tasks will start.</span></div>
<div class="line"><a name="l00766"></a><span class="lineno"> 766</span> <span class="comment"> * @exception Cgu::Thread::CondError This exception will be thrown if</span></div>
<div class="line"><a name="l00767"></a><span class="lineno"> 767</span> <span class="comment"> * initialization of a condition variable used by this function fails.</span></div>
<div class="line"><a name="l00768"></a><span class="lineno"> 768</span> <span class="comment"> * (It is often not worth checking for this, as it means either memory</span></div>
<div class="line"><a name="l00769"></a><span class="lineno"> 769</span> <span class="comment"> * is exhausted or pthread has run out of other resources to create</span></div>
<div class="line"><a name="l00770"></a><span class="lineno"> 770</span> <span class="comment"> * new condition variables.) If this exception is thrown, no tasks</span></div>
<div class="line"><a name="l00771"></a><span class="lineno"> 771</span> <span class="comment"> * will start.</span></div>
<div class="line"><a name="l00772"></a><span class="lineno"> 772</span> <span class="comment"> * @note An exception might also be thrown if the copy or move</span></div>
<div class="line"><a name="l00773"></a><span class="lineno"> 773</span> <span class="comment"> * constructor of the 'func' callable objects throws. If such an</span></div>
<div class="line"><a name="l00774"></a><span class="lineno"> 774</span> <span class="comment"> * exception is thrown, no tasks will start.</span></div>
<div class="line"><a name="l00775"></a><span class="lineno"> 775</span> <span class="comment"> * </span></div>
<div class="line"><a name="l00776"></a><span class="lineno"> 776</span> <span class="comment"> * Since 2.0.20/2.2.3</span></div>
<div class="line"><a name="l00777"></a><span class="lineno"> 777</span> <span class="comment"> */</span></div>
<div class="line"><a name="l00778"></a><span class="lineno"> 778</span> <span class="keyword">template</span> <<span class="keyword">class</span> Iterator, <span class="keyword">class</span> Func></div>
<div class="line"><a name="l00779"></a><span class="lineno"><a class="code" href="namespaceCgu_1_1Thread.html#a7a920c9b1ec2ee80e0c798204f1a5553"> 779</a></span> Iterator <a class="code" href="namespaceCgu_1_1Thread.html#a7a920c9b1ec2ee80e0c798204f1a5553">parallel_for_each_partial</a>(<a class="code" href="classCgu_1_1Thread_1_1TaskManager.html" title="A thread-pool class for managing tasks in multi-threaded programs. ">TaskManager</a>& tm,</div>
<div class="line"><a name="l00780"></a><span class="lineno"> 780</span>  Iterator first,</div>
<div class="line"><a name="l00781"></a><span class="lineno"> 781</span>  Iterator last,</div>
<div class="line"><a name="l00782"></a><span class="lineno"> 782</span>  <span class="keywordtype">int</span> max,</div>
<div class="line"><a name="l00783"></a><span class="lineno"> 783</span>  Func&& func) {</div>
<div class="line"><a name="l00784"></a><span class="lineno"> 784</span> </div>
<div class="line"><a name="l00785"></a><span class="lineno"> 785</span>  <span class="keywordflow">if</span> (first == last || !max) <span class="keywordflow">return</span> first;</div>
<div class="line"><a name="l00786"></a><span class="lineno"> 786</span> </div>
<div class="line"><a name="l00787"></a><span class="lineno"> 787</span>  <span class="keyword">typedef</span> <span class="keyword">typename</span> std::iterator_traits<Iterator>::value_type ArgType;</div>
<div class="line"><a name="l00788"></a><span class="lineno"> 788</span>  <span class="keyword">typedef</span> <span class="keyword">typename</span> std::iterator_traits<Iterator>::difference_type DiffType;</div>
<div class="line"><a name="l00789"></a><span class="lineno"> 789</span> </div>
<div class="line"><a name="l00790"></a><span class="lineno"> 790</span>  <a class="code" href="classCgu_1_1Thread_1_1Mutex.html" title="A wrapper class for pthread mutexes. ">Mutex</a> mutex;</div>
<div class="line"><a name="l00791"></a><span class="lineno"> 791</span>  <a class="code" href="classCgu_1_1Thread_1_1Cond.html" title="A wrapper class for pthread condition variables. ">Cond</a> cond;</div>
<div class="line"><a name="l00792"></a><span class="lineno"> 792</span>  DiffType start_count = 0;</div>
<div class="line"><a name="l00793"></a><span class="lineno"> 793</span>  DiffType done_count = 0;</div>
<div class="line"><a name="l00794"></a><span class="lineno"> 794</span>  <span class="keywordtype">bool</span> error = <span class="keyword">false</span>;</div>
<div class="line"><a name="l00795"></a><span class="lineno"> 795</span> </div>
<div class="line"><a name="l00796"></a><span class="lineno"> 796</span>  <span class="comment">// a specialization of std::numeric_limits::max() for all arithmetic</span></div>
<div class="line"><a name="l00797"></a><span class="lineno"> 797</span>  <span class="comment">// types is required by §3.9.1/8 of the standard. The iterator</span></div>
<div class="line"><a name="l00798"></a><span class="lineno"> 798</span>  <span class="comment">// difference type must be a signed integer type (§24.2.1/1). All</span></div>
<div class="line"><a name="l00799"></a><span class="lineno"> 799</span>  <span class="comment">// signed integer types are arithmetic types (§3.9.1/2, §3.9.1/7 and</span></div>
<div class="line"><a name="l00800"></a><span class="lineno"> 800</span>  <span class="comment">// §3.9.1/8).</span></div>
<div class="line"><a name="l00801"></a><span class="lineno"> 801</span>  <span class="keyword">const</span> DiffType local_max =</div>
<div class="line"><a name="l00802"></a><span class="lineno"> 802</span>  (max >= 0) ? max : std::numeric_limits<DiffType>::max();</div>
<div class="line"><a name="l00803"></a><span class="lineno"> 803</span> </div>
<div class="line"><a name="l00804"></a><span class="lineno"> 804</span>  <span class="comment">// construct SafeFunctorArg objects so that they can be shared</span></div>
<div class="line"><a name="l00805"></a><span class="lineno"> 805</span>  <span class="comment">// between different tasks</span></div>
<div class="line"><a name="l00806"></a><span class="lineno"> 806</span>  <a class="code" href="classCgu_1_1Callback_1_1SafeFunctorArg.html" title="Functor class holding a Callback::CallbackArg object, with thread-safe reference count. ">Cgu::Callback::SafeFunctorArg<ArgType&></a> s_task{</div>
<div class="line"><a name="l00807"></a><span class="lineno"> 807</span>  Cgu::Callback::lambda<ArgType&>(std::forward<Func>(func))</div>
<div class="line"><a name="l00808"></a><span class="lineno"> 808</span>  };</div>
<div class="line"><a name="l00809"></a><span class="lineno"> 809</span>  <a class="code" href="classCgu_1_1Callback_1_1SafeFunctorArg.html" title="Functor class holding a Callback::CallbackArg object, with thread-safe reference count. ">Cgu::Callback::SafeFunctor</a> s_fail{</div>
<div class="line"><a name="l00810"></a><span class="lineno"> 810</span>  <a class="code" href="namespaceCgu_1_1Callback.html#a3e32d4f4961c618aa7e03bda00f398b8">Cgu::Callback::make</a>(&ParallelHelper2::fail_func<DiffType>,</div>
<div class="line"><a name="l00811"></a><span class="lineno"> 811</span>  &mutex,</div>
<div class="line"><a name="l00812"></a><span class="lineno"> 812</span>  &cond,</div>
<div class="line"><a name="l00813"></a><span class="lineno"> 813</span>  &error,</div>
<div class="line"><a name="l00814"></a><span class="lineno"> 814</span>  &done_count)</div>
<div class="line"><a name="l00815"></a><span class="lineno"> 815</span>  };</div>
<div class="line"><a name="l00816"></a><span class="lineno"> 816</span> </div>
<div class="line"><a name="l00817"></a><span class="lineno"> 817</span>  <span class="keywordflow">for</span> (; first != last && start_count < local_max; ++first, ++start_count) {</div>
<div class="line"><a name="l00818"></a><span class="lineno"> 818</span>  std::unique_ptr<const Cgu::Callback::Callback> task_cb(</div>
<div class="line"><a name="l00819"></a><span class="lineno"> 819</span>  <a class="code" href="namespaceCgu_1_1Callback.html#a94b122ac99f423928320240fd48d571b">Cgu::Callback::make_ref</a>(&ParallelHelper2::for_each_cb_func<ArgType, DiffType, Iterator>,</div>
<div class="line"><a name="l00820"></a><span class="lineno"> 820</span>  s_task,</div>
<div class="line"><a name="l00821"></a><span class="lineno"> 821</span>  first,</div>
<div class="line"><a name="l00822"></a><span class="lineno"> 822</span>  &mutex,</div>
<div class="line"><a name="l00823"></a><span class="lineno"> 823</span>  &cond,</div>
<div class="line"><a name="l00824"></a><span class="lineno"> 824</span>  &done_count)</div>
<div class="line"><a name="l00825"></a><span class="lineno"> 825</span>  );</div>
<div class="line"><a name="l00826"></a><span class="lineno"> 826</span>  std::unique_ptr<const Cgu::Callback::Callback> fail_cb(</div>
<div class="line"><a name="l00827"></a><span class="lineno"> 827</span>  Cgu::Callback::lambda<>([s_fail] () {s_fail();})</div>
<div class="line"><a name="l00828"></a><span class="lineno"> 828</span>  );</div>
<div class="line"><a name="l00829"></a><span class="lineno"> 829</span> </div>
<div class="line"><a name="l00830"></a><span class="lineno"> 830</span>  tm.<a class="code" href="classCgu_1_1Thread_1_1TaskManager.html#a81f7c8af3295d92c0e19d7f9498a4078">add_task</a>(std::move(task_cb), std::move(fail_cb));</div>
<div class="line"><a name="l00831"></a><span class="lineno"> 831</span>  }</div>
<div class="line"><a name="l00832"></a><span class="lineno"> 832</span>  </div>
<div class="line"><a name="l00833"></a><span class="lineno"> 833</span>  <a class="code" href="classCgu_1_1Thread_1_1Mutex_1_1Lock.html" title="A scoped locking class for exception safe Mutex locking. ">Mutex::Lock</a> l{mutex};</div>
<div class="line"><a name="l00834"></a><span class="lineno"> 834</span>  <span class="keywordflow">while</span> (start_count > done_count) cond.<a class="code" href="classCgu_1_1Thread_1_1Cond.html#a5eda52c227552555102bb45010a8f6c9">wait</a>(mutex);</div>
<div class="line"><a name="l00835"></a><span class="lineno"> 835</span>  <span class="keywordflow">if</span> (error) <span class="keywordflow">throw</span> <a class="code" href="structCgu_1_1Thread_1_1ParallelError.html">ParallelError</a>();</div>
<div class="line"><a name="l00836"></a><span class="lineno"> 836</span>  <span class="keywordflow">return</span> first;</div>
<div class="line"><a name="l00837"></a><span class="lineno"> 837</span> }</div>
<div class="line"><a name="l00838"></a><span class="lineno"> 838</span> <span class="comment"></span></div>
<div class="line"><a name="l00839"></a><span class="lineno"> 839</span> <span class="comment">/**</span></div>
<div class="line"><a name="l00840"></a><span class="lineno"> 840</span> <span class="comment"> * \#include <c++-gtk-utils/parallel.h></span></div>
<div class="line"><a name="l00841"></a><span class="lineno"> 841</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00842"></a><span class="lineno"> 842</span> <span class="comment"> * This function maps over a container in the range ['first', 'last')</span></div>
<div class="line"><a name="l00843"></a><span class="lineno"> 843</span> <span class="comment"> * subject to a maximum, applying a unary callable object to each</span></div>
<div class="line"><a name="l00844"></a><span class="lineno"> 844</span> <span class="comment"> * element of the container in that range (subject to the maximum) and</span></div>
<div class="line"><a name="l00845"></a><span class="lineno"> 845</span> <span class="comment"> * storing the result in the destination range, by executing each such</span></div>
<div class="line"><a name="l00846"></a><span class="lineno"> 846</span> <span class="comment"> * application as a task of a Thread::TaskManager object. Tasks are</span></div>
<div class="line"><a name="l00847"></a><span class="lineno"> 847</span> <span class="comment"> * added to the Thread::TaskManager object in the order in which the</span></div>
<div class="line"><a name="l00848"></a><span class="lineno"> 848</span> <span class="comment"> * respective elements appear in the source container, and the final</span></div>
<div class="line"><a name="l00849"></a><span class="lineno"> 849</span> <span class="comment"> * result appears in the destination container in the same order as</span></div>
<div class="line"><a name="l00850"></a><span class="lineno"> 850</span> <span class="comment"> * the source range from which it is generated (including if a</span></div>
<div class="line"><a name="l00851"></a><span class="lineno"> 851</span> <span class="comment"> * back_inserter iterator is used), but no other ordering arises, and</span></div>
<div class="line"><a name="l00852"></a><span class="lineno"> 852</span> <span class="comment"> * the tasks will execute in parallel to the extent that the</span></div>
<div class="line"><a name="l00853"></a><span class="lineno"> 853</span> <span class="comment"> * Thread::TaskManager object has sufficient threads available to do</span></div>
<div class="line"><a name="l00854"></a><span class="lineno"> 854</span> <span class="comment"> * so.</span></div>
<div class="line"><a name="l00855"></a><span class="lineno"> 855</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00856"></a><span class="lineno"> 856</span> <span class="comment"> * A separate overload of this function takes a binary callable</span></div>
<div class="line"><a name="l00857"></a><span class="lineno"> 857</span> <span class="comment"> * object.</span></div>
<div class="line"><a name="l00858"></a><span class="lineno"> 858</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00859"></a><span class="lineno"> 859</span> <span class="comment"> * This function does the same as the version of</span></div>
<div class="line"><a name="l00860"></a><span class="lineno"> 860</span> <span class="comment"> * Thread::parallel_transform() taking a unary callable object, except</span></div>
<div class="line"><a name="l00861"></a><span class="lineno"> 861</span> <span class="comment"> * that it returns a std::pair object containing an iterator to the</span></div>
<div class="line"><a name="l00862"></a><span class="lineno"> 862</span> <span class="comment"> * element past the last element of the source range transformed, and</span></div>
<div class="line"><a name="l00863"></a><span class="lineno"> 863</span> <span class="comment"> * a destination iterator to the element past the last element stored</span></div>
<div class="line"><a name="l00864"></a><span class="lineno"> 864</span> <span class="comment"> * in the destination range, and it has a 'max' parameter to limit the</span></div>
<div class="line"><a name="l00865"></a><span class="lineno"> 865</span> <span class="comment"> * maximum number of elements which will be so transformed on any one</span></div>
<div class="line"><a name="l00866"></a><span class="lineno"> 866</span> <span class="comment"> * call to this function. Whether this limitation has had effect on</span></div>
<div class="line"><a name="l00867"></a><span class="lineno"> 867</span> <span class="comment"> * any one call can be tested by checking whether the first value of</span></div>
<div class="line"><a name="l00868"></a><span class="lineno"> 868</span> <span class="comment"> * the pair returned is equal to the 'last' parameter. If it is not,</span></div>
<div class="line"><a name="l00869"></a><span class="lineno"> 869</span> <span class="comment"> * a further call to this function can be made.</span></div>
<div class="line"><a name="l00870"></a><span class="lineno"> 870</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00871"></a><span class="lineno"> 871</span> <span class="comment"> * The main purpose of this additional function is to enable the</span></div>
<div class="line"><a name="l00872"></a><span class="lineno"> 872</span> <span class="comment"> * parallel transform of the elements of a container to be dealt with</span></div>
<div class="line"><a name="l00873"></a><span class="lineno"> 873</span> <span class="comment"> * in chunks, possibly to enable other tasks to be interleaved at</span></div>
<div class="line"><a name="l00874"></a><span class="lineno"> 874</span> <span class="comment"> * reasonable intervals. For source or destination containers which</span></div>
<div class="line"><a name="l00875"></a><span class="lineno"> 875</span> <span class="comment"> * do not support random access iterators, the 'last' parameter can be</span></div>
<div class="line"><a name="l00876"></a><span class="lineno"> 876</span> <span class="comment"> * set to, say, the end of the container and the chunk size set with</span></div>
<div class="line"><a name="l00877"></a><span class="lineno"> 877</span> <span class="comment"> * the 'max' paramater, with the values of the returned pair being</span></div>
<div class="line"><a name="l00878"></a><span class="lineno"> 878</span> <span class="comment"> * used as the 'first' and 'dest' parameters for subsequent calls to</span></div>
<div class="line"><a name="l00879"></a><span class="lineno"> 879</span> <span class="comment"> * this function. This avoids having to increment the source and</span></div>
<div class="line"><a name="l00880"></a><span class="lineno"> 880</span> <span class="comment"> * destination iterators for each "chunk" by stepping through the</span></div>
<div class="line"><a name="l00881"></a><span class="lineno"> 881</span> <span class="comment"> * respective containers by hand. In this usage, it therefore</span></div>
<div class="line"><a name="l00882"></a><span class="lineno"> 882</span> <span class="comment"> * represents a minor efficiency improvement.</span></div>
<div class="line"><a name="l00883"></a><span class="lineno"> 883</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00884"></a><span class="lineno"> 884</span> <span class="comment"> * @param tm The Thread::TaskManager object on which the tasks will</span></div>
<div class="line"><a name="l00885"></a><span class="lineno"> 885</span> <span class="comment"> * run.</span></div>
<div class="line"><a name="l00886"></a><span class="lineno"> 886</span> <span class="comment"> * @param first The beginning of the range to which 'func' is to be</span></div>
<div class="line"><a name="l00887"></a><span class="lineno"> 887</span> <span class="comment"> * applied.</span></div>
<div class="line"><a name="l00888"></a><span class="lineno"> 888</span> <span class="comment"> * @param last One past the last element to which 'func' is to be</span></div>
<div class="line"><a name="l00889"></a><span class="lineno"> 889</span> <span class="comment"> * applied, subject to any maximum specified as the 'max' parameter.</span></div>
<div class="line"><a name="l00890"></a><span class="lineno"> 890</span> <span class="comment"> * @param dest The beginning of the range to which the result of</span></div>
<div class="line"><a name="l00891"></a><span class="lineno"> 891</span> <span class="comment"> * applying 'func' to the elements in the source range is to be</span></div>
<div class="line"><a name="l00892"></a><span class="lineno"> 892</span> <span class="comment"> * stored. As in the case of std::transform, this can overlap with or</span></div>
<div class="line"><a name="l00893"></a><span class="lineno"> 893</span> <span class="comment"> * be the same as the source range. It may also be an insert</span></div>
<div class="line"><a name="l00894"></a><span class="lineno"> 894</span> <span class="comment"> * iterator.</span></div>
<div class="line"><a name="l00895"></a><span class="lineno"> 895</span> <span class="comment"> * @param max The maximum number of elements of the source container</span></div>
<div class="line"><a name="l00896"></a><span class="lineno"> 896</span> <span class="comment"> * which will be transformed on this call. It is not an error if it</span></div>
<div class="line"><a name="l00897"></a><span class="lineno"> 897</span> <span class="comment"> * is greater than the distance between 'first' and 'last'. If it is</span></div>
<div class="line"><a name="l00898"></a><span class="lineno"> 898</span> <span class="comment"> * equal to or greater than that distance, it follows that the first</span></div>
<div class="line"><a name="l00899"></a><span class="lineno"> 899</span> <span class="comment"> * value of the pair returned by this function will be equal to</span></div>
<div class="line"><a name="l00900"></a><span class="lineno"> 900</span> <span class="comment"> * 'last'. The same results if 'max' is a negative number (in that</span></div>
<div class="line"><a name="l00901"></a><span class="lineno"> 901</span> <span class="comment"> * case no maximum will take effect and all elements in the range</span></div>
<div class="line"><a name="l00902"></a><span class="lineno"> 902</span> <span class="comment"> * ['first', 'last') will be transformed), so passing -1 might be</span></div>
<div class="line"><a name="l00903"></a><span class="lineno"> 903</span> <span class="comment"> * useful as a means of obtaining a destination iterator (the second</span></div>
<div class="line"><a name="l00904"></a><span class="lineno"> 904</span> <span class="comment"> * value) for other purposes, particularly where it is not a random</span></div>
<div class="line"><a name="l00905"></a><span class="lineno"> 905</span> <span class="comment"> * access iterator).</span></div>
<div class="line"><a name="l00906"></a><span class="lineno"> 906</span> <span class="comment"> * @param func A unary callable object to be applied (subject to the</span></div>
<div class="line"><a name="l00907"></a><span class="lineno"> 907</span> <span class="comment"> * maximum) to each element in the range ['first', 'last'), such as</span></div>
<div class="line"><a name="l00908"></a><span class="lineno"> 908</span> <span class="comment"> * formed by a lambda expression or the result of std::bind. It</span></div>
<div class="line"><a name="l00909"></a><span class="lineno"> 909</span> <span class="comment"> * should take a single unbound argument of the value type of the</span></div>
<div class="line"><a name="l00910"></a><span class="lineno"> 910</span> <span class="comment"> * container to which 'first' and 'last' relate or a const or</span></div>
<div class="line"><a name="l00911"></a><span class="lineno"> 911</span> <span class="comment"> * non-const reference to that type. If an exception propagates from</span></div>
<div class="line"><a name="l00912"></a><span class="lineno"> 912</span> <span class="comment"> * 'func', the exception will be consumed while the transform loop is</span></div>
<div class="line"><a name="l00913"></a><span class="lineno"> 913</span> <span class="comment"> * running, and an attempt will still be made to apply 'func' to all</span></div>
<div class="line"><a name="l00914"></a><span class="lineno"> 914</span> <span class="comment"> * remaining elements in the range ['first', 'last') subject to the</span></div>
<div class="line"><a name="l00915"></a><span class="lineno"> 915</span> <span class="comment"> * maximum, and only after that attempt has completed will the</span></div>
<div class="line"><a name="l00916"></a><span class="lineno"> 916</span> <span class="comment"> * exception Cgu::Thread::ParallelError be thrown.</span></div>
<div class="line"><a name="l00917"></a><span class="lineno"> 917</span> <span class="comment"> * @return A std::pair object. Its first member is an iterator</span></div>
<div class="line"><a name="l00918"></a><span class="lineno"> 918</span> <span class="comment"> * representing the element past the last element of the source range</span></div>
<div class="line"><a name="l00919"></a><span class="lineno"> 919</span> <span class="comment"> * transformed, which may be passed as the 'first' argument of a</span></div>
<div class="line"><a name="l00920"></a><span class="lineno"> 920</span> <span class="comment"> * subsequent call to this function; and its second member is an</span></div>
<div class="line"><a name="l00921"></a><span class="lineno"> 921</span> <span class="comment"> * iterator representing the element past the last element stored in</span></div>
<div class="line"><a name="l00922"></a><span class="lineno"> 922</span> <span class="comment"> * the destination range, which may be passed as the 'dest' argument</span></div>
<div class="line"><a name="l00923"></a><span class="lineno"> 923</span> <span class="comment"> * of the subsequent call.</span></div>
<div class="line"><a name="l00924"></a><span class="lineno"> 924</span> <span class="comment"> * @exception std::bad_alloc This exception will be thrown if memory</span></div>
<div class="line"><a name="l00925"></a><span class="lineno"> 925</span> <span class="comment"> * is exhausted and the system throws in that case. (On systems with</span></div>
<div class="line"><a name="l00926"></a><span class="lineno"> 926</span> <span class="comment"> * over-commit/lazy-commit combined with virtual memory (swap), it is</span></div>
<div class="line"><a name="l00927"></a><span class="lineno"> 927</span> <span class="comment"> * rarely useful to check for memory exhaustion). If this exception</span></div>
<div class="line"><a name="l00928"></a><span class="lineno"> 928</span> <span class="comment"> * is thrown, some tasks may nonetheless have already started by</span></div>
<div class="line"><a name="l00929"></a><span class="lineno"> 929</span> <span class="comment"> * virtue of the call to this function, but subsequent ones will not.</span></div>
<div class="line"><a name="l00930"></a><span class="lineno"> 930</span> <span class="comment"> * @exception Cgu::Thread::TaskError This exception will be thrown if</span></div>
<div class="line"><a name="l00931"></a><span class="lineno"> 931</span> <span class="comment"> * stop_all() has previously been called on the Thread::TaskManager</span></div>
<div class="line"><a name="l00932"></a><span class="lineno"> 932</span> <span class="comment"> * object, or if another thread calls stop_all() after this method is</span></div>
<div class="line"><a name="l00933"></a><span class="lineno"> 933</span> <span class="comment"> * called but before it has returned. It will also be thrown if the</span></div>
<div class="line"><a name="l00934"></a><span class="lineno"> 934</span> <span class="comment"> * Thread::TaskManager object's is_error() method would return true</span></div>
<div class="line"><a name="l00935"></a><span class="lineno"> 935</span> <span class="comment"> * because its internal thread pool loop implementation has thrown</span></div>
<div class="line"><a name="l00936"></a><span class="lineno"> 936</span> <span class="comment"> * std::bad_alloc, or a thread has failed to start correctly because</span></div>
<div class="line"><a name="l00937"></a><span class="lineno"> 937</span> <span class="comment"> * pthread has run out of resources. (On systems with</span></div>
<div class="line"><a name="l00938"></a><span class="lineno"> 938</span> <span class="comment"> * over-commit/lazy-commit combined with virtual memory (swap), it is</span></div>
<div class="line"><a name="l00939"></a><span class="lineno"> 939</span> <span class="comment"> * rarely useful to check for memory exhaustion, and if a reasonable</span></div>
<div class="line"><a name="l00940"></a><span class="lineno"> 940</span> <span class="comment"> * maximum thread count has been chosen for the Thread::TaskManager</span></div>
<div class="line"><a name="l00941"></a><span class="lineno"> 941</span> <span class="comment"> * object pthread should not run out of other resources, but there may</span></div>
<div class="line"><a name="l00942"></a><span class="lineno"> 942</span> <span class="comment"> * be some specialized cases where the return value of is_error() is</span></div>
<div class="line"><a name="l00943"></a><span class="lineno"> 943</span> <span class="comment"> * useful.) If this exception is thrown, some tasks may nonetheless</span></div>
<div class="line"><a name="l00944"></a><span class="lineno"> 944</span> <span class="comment"> * have already started by virtue of the call to this function.</span></div>
<div class="line"><a name="l00945"></a><span class="lineno"> 945</span> <span class="comment"> * @exception Cgu::Thread::ParallelError This exception will be thrown</span></div>
<div class="line"><a name="l00946"></a><span class="lineno"> 946</span> <span class="comment"> * if an exception propagates from the 'func' callable object when it</span></div>
<div class="line"><a name="l00947"></a><span class="lineno"> 947</span> <span class="comment"> * executes on being applied to one or more elements of the source</span></div>
<div class="line"><a name="l00948"></a><span class="lineno"> 948</span> <span class="comment"> * container. Such an exception will not stop an attempt being made</span></div>
<div class="line"><a name="l00949"></a><span class="lineno"> 949</span> <span class="comment"> * to apply 'func' (successfully or unsuccessfully) to all elements in</span></div>
<div class="line"><a name="l00950"></a><span class="lineno"> 950</span> <span class="comment"> * the range ['first', 'last') subject to the maximum.</span></div>
<div class="line"><a name="l00951"></a><span class="lineno"> 951</span> <span class="comment"> * Cgu::Thread::ParallelError will be thrown after such attempted</span></div>
<div class="line"><a name="l00952"></a><span class="lineno"> 952</span> <span class="comment"> * application has finished.</span></div>
<div class="line"><a name="l00953"></a><span class="lineno"> 953</span> <span class="comment"> * @exception Cgu::Thread::MutexError This exception will be thrown if</span></div>
<div class="line"><a name="l00954"></a><span class="lineno"> 954</span> <span class="comment"> * initialization of a mutex used by this function fails. (It is</span></div>
<div class="line"><a name="l00955"></a><span class="lineno"> 955</span> <span class="comment"> * often not worth checking for this, as it means either memory is</span></div>
<div class="line"><a name="l00956"></a><span class="lineno"> 956</span> <span class="comment"> * exhausted or pthread has run out of other resources to create new</span></div>
<div class="line"><a name="l00957"></a><span class="lineno"> 957</span> <span class="comment"> * mutexes.) If this exception is thrown, no tasks will start.</span></div>
<div class="line"><a name="l00958"></a><span class="lineno"> 958</span> <span class="comment"> * @exception Cgu::Thread::CondError This exception will be thrown if</span></div>
<div class="line"><a name="l00959"></a><span class="lineno"> 959</span> <span class="comment"> * initialization of a condition variable used by this function fails.</span></div>
<div class="line"><a name="l00960"></a><span class="lineno"> 960</span> <span class="comment"> * (It is often not worth checking for this, as it means either memory</span></div>
<div class="line"><a name="l00961"></a><span class="lineno"> 961</span> <span class="comment"> * is exhausted or pthread has run out of other resources to create</span></div>
<div class="line"><a name="l00962"></a><span class="lineno"> 962</span> <span class="comment"> * new condition variables.) If this exception is thrown, no tasks</span></div>
<div class="line"><a name="l00963"></a><span class="lineno"> 963</span> <span class="comment"> * will start.</span></div>
<div class="line"><a name="l00964"></a><span class="lineno"> 964</span> <span class="comment"> * @note An exception might also be thrown if the copy or move</span></div>
<div class="line"><a name="l00965"></a><span class="lineno"> 965</span> <span class="comment"> * constructor of the 'func' callable objects throws. If such an</span></div>
<div class="line"><a name="l00966"></a><span class="lineno"> 966</span> <span class="comment"> * exception is thrown, no tasks will start.</span></div>
<div class="line"><a name="l00967"></a><span class="lineno"> 967</span> <span class="comment"> * </span></div>
<div class="line"><a name="l00968"></a><span class="lineno"> 968</span> <span class="comment"> * Since 2.0.20/2.2.3</span></div>
<div class="line"><a name="l00969"></a><span class="lineno"> 969</span> <span class="comment"> */</span></div>
<div class="line"><a name="l00970"></a><span class="lineno"> 970</span> <span class="keyword">template</span> <<span class="keyword">class</span> SourceIterator, <span class="keyword">class</span> DestIterator, <span class="keyword">class</span> Func></div>
<div class="line"><a name="l00971"></a><span class="lineno"> 971</span> std::pair<SourceIterator, DestIterator></div>
<div class="line"><a name="l00972"></a><span class="lineno"><a class="code" href="namespaceCgu_1_1Thread.html#ad03d1d6f6b0718a0b63a850b05fae623"> 972</a></span>  <a class="code" href="namespaceCgu_1_1Thread.html#ad03d1d6f6b0718a0b63a850b05fae623">parallel_transform_partial</a>(<a class="code" href="classCgu_1_1Thread_1_1TaskManager.html" title="A thread-pool class for managing tasks in multi-threaded programs. ">TaskManager</a>& tm,</div>
<div class="line"><a name="l00973"></a><span class="lineno"> 973</span>  SourceIterator first,</div>
<div class="line"><a name="l00974"></a><span class="lineno"> 974</span>  SourceIterator last,</div>
<div class="line"><a name="l00975"></a><span class="lineno"> 975</span>  DestIterator dest,</div>
<div class="line"><a name="l00976"></a><span class="lineno"> 976</span>  <span class="keywordtype">int</span> max,</div>
<div class="line"><a name="l00977"></a><span class="lineno"> 977</span>  Func&& func) {</div>
<div class="line"><a name="l00978"></a><span class="lineno"> 978</span> </div>
<div class="line"><a name="l00979"></a><span class="lineno"> 979</span>  <span class="keywordflow">if</span> (first == last || !max) <span class="keywordflow">return</span> {first, dest};</div>
<div class="line"><a name="l00980"></a><span class="lineno"> 980</span> </div>
<div class="line"><a name="l00981"></a><span class="lineno"> 981</span>  <span class="keyword">typedef</span> <span class="keyword">typename</span> std::iterator_traits<SourceIterator>::value_type ArgType;</div>
<div class="line"><a name="l00982"></a><span class="lineno"> 982</span>  <span class="keyword">typedef</span> <span class="keyword">typename</span> std::iterator_traits<SourceIterator>::difference_type DiffType;</div>
<div class="line"><a name="l00983"></a><span class="lineno"> 983</span>  <span class="keyword">typedef</span> <span class="keyword">typename</span> std::remove_const<typename std::remove_reference<Func>::type>::type FType;</div>
<div class="line"><a name="l00984"></a><span class="lineno"> 984</span>  <span class="keyword">typedef</span> decltype(func(*first)) DestType;</div>
<div class="line"><a name="l00985"></a><span class="lineno"> 985</span> </div>
<div class="line"><a name="l00986"></a><span class="lineno"> 986</span>  <a class="code" href="classCgu_1_1Thread_1_1Mutex.html" title="A wrapper class for pthread mutexes. ">Mutex</a> mutex;</div>
<div class="line"><a name="l00987"></a><span class="lineno"> 987</span>  <a class="code" href="classCgu_1_1Thread_1_1Cond.html" title="A wrapper class for pthread condition variables. ">Cond</a> cond;</div>
<div class="line"><a name="l00988"></a><span class="lineno"> 988</span>  DiffType start_count = 0;</div>
<div class="line"><a name="l00989"></a><span class="lineno"> 989</span>  DiffType done_count = 0;</div>
<div class="line"><a name="l00990"></a><span class="lineno"> 990</span>  <span class="keywordtype">bool</span> error = <span class="keyword">false</span>;</div>
<div class="line"><a name="l00991"></a><span class="lineno"> 991</span> </div>
<div class="line"><a name="l00992"></a><span class="lineno"> 992</span>  <span class="comment">// a specialization of std::numeric_limits::max() for all arithmetic</span></div>
<div class="line"><a name="l00993"></a><span class="lineno"> 993</span>  <span class="comment">// types is required by §3.9.1/8 of the standard. The iterator</span></div>
<div class="line"><a name="l00994"></a><span class="lineno"> 994</span>  <span class="comment">// difference type must be a signed integer type (§24.2.1/1). All</span></div>
<div class="line"><a name="l00995"></a><span class="lineno"> 995</span>  <span class="comment">// signed integer types are arithmetic types (§3.9.1/2, §3.9.1/7 and</span></div>
<div class="line"><a name="l00996"></a><span class="lineno"> 996</span>  <span class="comment">// §3.9.1/8).</span></div>
<div class="line"><a name="l00997"></a><span class="lineno"> 997</span>  <span class="keyword">const</span> DiffType local_max =</div>
<div class="line"><a name="l00998"></a><span class="lineno"> 998</span>  (max >= 0) ? max : std::numeric_limits<DiffType>::max();</div>
<div class="line"><a name="l00999"></a><span class="lineno"> 999</span> </div>
<div class="line"><a name="l01000"></a><span class="lineno"> 1000</span>  <span class="comment">// intermediate results have to be held in an array so destination</span></div>
<div class="line"><a name="l01001"></a><span class="lineno"> 1001</span>  <span class="comment">// ordering can be enforced when using insert interators. This</span></div>
<div class="line"><a name="l01002"></a><span class="lineno"> 1002</span>  <span class="comment">// causes some inefficiency for non-random access iterators</span></div>
<div class="line"><a name="l01003"></a><span class="lineno"> 1003</span>  std::unique_ptr<DestType[]> results(<span class="keyword">new</span> DestType[std::min(local_max,</div>
<div class="line"><a name="l01004"></a><span class="lineno"> 1004</span>  std::distance(first, last))]);</div>
<div class="line"><a name="l01005"></a><span class="lineno"> 1005</span> </div>
<div class="line"><a name="l01006"></a><span class="lineno"> 1006</span>  <span class="comment">// construct SafeFunctorArg objects so that they can be shared</span></div>
<div class="line"><a name="l01007"></a><span class="lineno"> 1007</span>  <span class="comment">// between different tasks</span></div>
<div class="line"><a name="l01008"></a><span class="lineno"> 1008</span>  <a class="code" href="classCgu_1_1Callback_1_1SafeFunctorArg.html" title="Functor class holding a Callback::CallbackArg object, with thread-safe reference count. ">Cgu::Callback::SafeFunctorArg<ArgType&, DestType&></a> s_task{</div>
<div class="line"><a name="l01009"></a><span class="lineno"> 1009</span>  <a class="code" href="namespaceCgu_1_1Callback.html#a94b122ac99f423928320240fd48d571b">Cgu::Callback::make_ref</a>(&ParallelHelper2::transform1_func<FType, ArgType, DestType>,</div>
<div class="line"><a name="l01010"></a><span class="lineno"> 1010</span>  std::forward<Func>(func))</div>
<div class="line"><a name="l01011"></a><span class="lineno"> 1011</span>  };</div>
<div class="line"><a name="l01012"></a><span class="lineno"> 1012</span>  <a class="code" href="classCgu_1_1Callback_1_1SafeFunctorArg.html" title="Functor class holding a Callback::CallbackArg object, with thread-safe reference count. ">Cgu::Callback::SafeFunctor</a> s_fail{</div>
<div class="line"><a name="l01013"></a><span class="lineno"> 1013</span>  <a class="code" href="namespaceCgu_1_1Callback.html#a3e32d4f4961c618aa7e03bda00f398b8">Cgu::Callback::make</a>(&ParallelHelper2::fail_func<DiffType>,</div>
<div class="line"><a name="l01014"></a><span class="lineno"> 1014</span>  &mutex,</div>
<div class="line"><a name="l01015"></a><span class="lineno"> 1015</span>  &cond,</div>
<div class="line"><a name="l01016"></a><span class="lineno"> 1016</span>  &error,</div>
<div class="line"><a name="l01017"></a><span class="lineno"> 1017</span>  &done_count)</div>
<div class="line"><a name="l01018"></a><span class="lineno"> 1018</span>  };</div>
<div class="line"><a name="l01019"></a><span class="lineno"> 1019</span> </div>
<div class="line"><a name="l01020"></a><span class="lineno"> 1020</span>  <span class="keywordflow">for</span> (; first != last && start_count < local_max; ++first, ++start_count) {</div>
<div class="line"><a name="l01021"></a><span class="lineno"> 1021</span>  std::unique_ptr<const Cgu::Callback::Callback> task_cb(</div>
<div class="line"><a name="l01022"></a><span class="lineno"> 1022</span>  Cgu::Callback::lambda<>(std::bind(&ParallelHelper2::transform1_cb_func<ArgType, DestType, DiffType, SourceIterator>,</div>
<div class="line"><a name="l01023"></a><span class="lineno"> 1023</span>  s_task,</div>
<div class="line"><a name="l01024"></a><span class="lineno"> 1024</span>  first,</div>
<div class="line"><a name="l01025"></a><span class="lineno"> 1025</span>  &mutex,</div>
<div class="line"><a name="l01026"></a><span class="lineno"> 1026</span>  &cond,</div>
<div class="line"><a name="l01027"></a><span class="lineno"> 1027</span>  &done_count,</div>
<div class="line"><a name="l01028"></a><span class="lineno"> 1028</span>  results.get(),</div>
<div class="line"><a name="l01029"></a><span class="lineno"> 1029</span>  start_count))</div>
<div class="line"><a name="l01030"></a><span class="lineno"> 1030</span>  );</div>
<div class="line"><a name="l01031"></a><span class="lineno"> 1031</span>  std::unique_ptr<const Cgu::Callback::Callback> fail_cb(</div>
<div class="line"><a name="l01032"></a><span class="lineno"> 1032</span>  Cgu::Callback::lambda<>([s_fail] () {s_fail();})</div>
<div class="line"><a name="l01033"></a><span class="lineno"> 1033</span>  );</div>
<div class="line"><a name="l01034"></a><span class="lineno"> 1034</span> </div>
<div class="line"><a name="l01035"></a><span class="lineno"> 1035</span>  tm.<a class="code" href="classCgu_1_1Thread_1_1TaskManager.html#a81f7c8af3295d92c0e19d7f9498a4078">add_task</a>(std::move(task_cb), std::move(fail_cb));</div>
<div class="line"><a name="l01036"></a><span class="lineno"> 1036</span>  }</div>
<div class="line"><a name="l01037"></a><span class="lineno"> 1037</span>  </div>
<div class="line"><a name="l01038"></a><span class="lineno"> 1038</span>  <a class="code" href="classCgu_1_1Thread_1_1Mutex_1_1Lock.html" title="A scoped locking class for exception safe Mutex locking. ">Mutex::Lock</a> l{mutex};</div>
<div class="line"><a name="l01039"></a><span class="lineno"> 1039</span>  <span class="keywordflow">while</span> (start_count > done_count) cond.<a class="code" href="classCgu_1_1Thread_1_1Cond.html#a5eda52c227552555102bb45010a8f6c9">wait</a>(mutex);</div>
<div class="line"><a name="l01040"></a><span class="lineno"> 1040</span>  <span class="keywordflow">if</span> (error) <span class="keywordflow">throw</span> <a class="code" href="structCgu_1_1Thread_1_1ParallelError.html">ParallelError</a>();</div>
<div class="line"><a name="l01041"></a><span class="lineno"> 1041</span>  <span class="keywordflow">for</span> (DiffType index = 0; index < start_count; ++dest, ++index) {</div>
<div class="line"><a name="l01042"></a><span class="lineno"> 1042</span>  *dest = std::move(results[index]);</div>
<div class="line"><a name="l01043"></a><span class="lineno"> 1043</span>  }</div>
<div class="line"><a name="l01044"></a><span class="lineno"> 1044</span>  <span class="keywordflow">return</span> {first, dest};</div>
<div class="line"><a name="l01045"></a><span class="lineno"> 1045</span> }</div>
<div class="line"><a name="l01046"></a><span class="lineno"> 1046</span> <span class="comment"></span></div>
<div class="line"><a name="l01047"></a><span class="lineno"> 1047</span> <span class="comment">/**</span></div>
<div class="line"><a name="l01048"></a><span class="lineno"> 1048</span> <span class="comment"> * \#include <c++-gtk-utils/parallel.h></span></div>
<div class="line"><a name="l01049"></a><span class="lineno"> 1049</span> <span class="comment"> *</span></div>
<div class="line"><a name="l01050"></a><span class="lineno"> 1050</span> <span class="comment"> * This function maps over two containers, one in the range ['first1',</span></div>
<div class="line"><a name="l01051"></a><span class="lineno"> 1051</span> <span class="comment"> * 'last1') subject to a maximum, and the other beginning at 'first2',</span></div>
<div class="line"><a name="l01052"></a><span class="lineno"> 1052</span> <span class="comment"> * applying a binary callable object to each element of the containers</span></div>
<div class="line"><a name="l01053"></a><span class="lineno"> 1053</span> <span class="comment"> * in those ranges (subject to the maximum) and storing the result in</span></div>
<div class="line"><a name="l01054"></a><span class="lineno"> 1054</span> <span class="comment"> * the destination range, by executing each such application as a task</span></div>
<div class="line"><a name="l01055"></a><span class="lineno"> 1055</span> <span class="comment"> * of a Thread::TaskManager object. Tasks are added to the</span></div>
<div class="line"><a name="l01056"></a><span class="lineno"> 1056</span> <span class="comment"> * Thread::TaskManager object in the order in which the respective</span></div>
<div class="line"><a name="l01057"></a><span class="lineno"> 1057</span> <span class="comment"> * elements appear in the source containers, and the final result</span></div>
<div class="line"><a name="l01058"></a><span class="lineno"> 1058</span> <span class="comment"> * appears in the destination container in the same order as the</span></div>
<div class="line"><a name="l01059"></a><span class="lineno"> 1059</span> <span class="comment"> * source ranges from which it is generated (including if a</span></div>
<div class="line"><a name="l01060"></a><span class="lineno"> 1060</span> <span class="comment"> * back_inserter iterator is used), but no other ordering arises, and</span></div>
<div class="line"><a name="l01061"></a><span class="lineno"> 1061</span> <span class="comment"> * the tasks will execute in parallel to the extent that the</span></div>
<div class="line"><a name="l01062"></a><span class="lineno"> 1062</span> <span class="comment"> * Thread::TaskManager object has sufficient threads available to do</span></div>
<div class="line"><a name="l01063"></a><span class="lineno"> 1063</span> <span class="comment"> * so.</span></div>
<div class="line"><a name="l01064"></a><span class="lineno"> 1064</span> <span class="comment"> *</span></div>
<div class="line"><a name="l01065"></a><span class="lineno"> 1065</span> <span class="comment"> * A separate overload of this function takes a unary callable object.</span></div>
<div class="line"><a name="l01066"></a><span class="lineno"> 1066</span> <span class="comment"> *</span></div>
<div class="line"><a name="l01067"></a><span class="lineno"> 1067</span> <span class="comment"> * This function does the same as the version of</span></div>
<div class="line"><a name="l01068"></a><span class="lineno"> 1068</span> <span class="comment"> * Thread::parallel_transform() taking a binary callable object,</span></div>
<div class="line"><a name="l01069"></a><span class="lineno"> 1069</span> <span class="comment"> * except that it returns a std::tuple object containing iterators to</span></div>
<div class="line"><a name="l01070"></a><span class="lineno"> 1070</span> <span class="comment"> * the element past the last elements of the source ranges</span></div>
<div class="line"><a name="l01071"></a><span class="lineno"> 1071</span> <span class="comment"> * transformed, and a destination iterator to the element past the</span></div>
<div class="line"><a name="l01072"></a><span class="lineno"> 1072</span> <span class="comment"> * last element stored in the destination range, and it has a 'max'</span></div>
<div class="line"><a name="l01073"></a><span class="lineno"> 1073</span> <span class="comment"> * parameter to limit the maximum number of elements which will be so</span></div>
<div class="line"><a name="l01074"></a><span class="lineno"> 1074</span> <span class="comment"> * transformed on any one call to this function. Whether this</span></div>
<div class="line"><a name="l01075"></a><span class="lineno"> 1075</span> <span class="comment"> * limitation has had effect on any one call can be tested by checking</span></div>
<div class="line"><a name="l01076"></a><span class="lineno"> 1076</span> <span class="comment"> * whether the first value of the tuple returned is equal to the</span></div>
<div class="line"><a name="l01077"></a><span class="lineno"> 1077</span> <span class="comment"> * 'last' parameter. If it is not, a further call to this function</span></div>
<div class="line"><a name="l01078"></a><span class="lineno"> 1078</span> <span class="comment"> * can be made.</span></div>
<div class="line"><a name="l01079"></a><span class="lineno"> 1079</span> <span class="comment"> *</span></div>
<div class="line"><a name="l01080"></a><span class="lineno"> 1080</span> <span class="comment"> * The main purpose of this additional function is to enable the</span></div>
<div class="line"><a name="l01081"></a><span class="lineno"> 1081</span> <span class="comment"> * parallel transform of the elements of a container to be dealt with</span></div>
<div class="line"><a name="l01082"></a><span class="lineno"> 1082</span> <span class="comment"> * in chunks, possibly to enable other tasks to be interleaved at</span></div>
<div class="line"><a name="l01083"></a><span class="lineno"> 1083</span> <span class="comment"> * reasonable intervals. For source or destination containers which</span></div>
<div class="line"><a name="l01084"></a><span class="lineno"> 1084</span> <span class="comment"> * do not support random access iterators, the 'last' parameter can be</span></div>
<div class="line"><a name="l01085"></a><span class="lineno"> 1085</span> <span class="comment"> * set to, say, the end of the container and the chunk size set with</span></div>
<div class="line"><a name="l01086"></a><span class="lineno"> 1086</span> <span class="comment"> * the 'max' paramater, with the values of the returned tuple being</span></div>
<div class="line"><a name="l01087"></a><span class="lineno"> 1087</span> <span class="comment"> * used as the 'first1', 'first2' and 'dest' parameters for subsequent</span></div>
<div class="line"><a name="l01088"></a><span class="lineno"> 1088</span> <span class="comment"> * calls to this function. This avoids having to increment the source</span></div>
<div class="line"><a name="l01089"></a><span class="lineno"> 1089</span> <span class="comment"> * and destination iterators for each "chunk" by stepping through the</span></div>
<div class="line"><a name="l01090"></a><span class="lineno"> 1090</span> <span class="comment"> * respective containers by hand. In this usage, it therefore</span></div>
<div class="line"><a name="l01091"></a><span class="lineno"> 1091</span> <span class="comment"> * represents a minor efficiency improvement.</span></div>
<div class="line"><a name="l01092"></a><span class="lineno"> 1092</span> <span class="comment"> *</span></div>
<div class="line"><a name="l01093"></a><span class="lineno"> 1093</span> <span class="comment"> * @param tm The Thread::TaskManager object on which the tasks will</span></div>
<div class="line"><a name="l01094"></a><span class="lineno"> 1094</span> <span class="comment"> * run.</span></div>
<div class="line"><a name="l01095"></a><span class="lineno"> 1095</span> <span class="comment"> * @param first1 The beginning of the range which is to be passed as</span></div>
<div class="line"><a name="l01096"></a><span class="lineno"> 1096</span> <span class="comment"> * the first argument of 'func'.</span></div>
<div class="line"><a name="l01097"></a><span class="lineno"> 1097</span> <span class="comment"> * @param last1 One past the last element of the range which is to be</span></div>
<div class="line"><a name="l01098"></a><span class="lineno"> 1098</span> <span class="comment"> * passed as the first argument of 'func', subject to any maximum</span></div>
<div class="line"><a name="l01099"></a><span class="lineno"> 1099</span> <span class="comment"> * specified as the 'max' parameter.</span></div>
<div class="line"><a name="l01100"></a><span class="lineno"> 1100</span> <span class="comment"> * @param first2 The beginning of the range which is to be passed as</span></div>
<div class="line"><a name="l01101"></a><span class="lineno"> 1101</span> <span class="comment"> * the second argument of 'func'.</span></div>
<div class="line"><a name="l01102"></a><span class="lineno"> 1102</span> <span class="comment"> * @param dest The beginning of the range to which the result of</span></div>
<div class="line"><a name="l01103"></a><span class="lineno"> 1103</span> <span class="comment"> * applying 'func' to the elements in the source ranges is to be</span></div>
<div class="line"><a name="l01104"></a><span class="lineno"> 1104</span> <span class="comment"> * stored. As in the case of std::transform, this can overlap with or</span></div>
<div class="line"><a name="l01105"></a><span class="lineno"> 1105</span> <span class="comment"> * be the same as one of the source ranges. It may also be an insert</span></div>
<div class="line"><a name="l01106"></a><span class="lineno"> 1106</span> <span class="comment"> * iterator.</span></div>
<div class="line"><a name="l01107"></a><span class="lineno"> 1107</span> <span class="comment"> * @param max The maximum number of elements of the source containers</span></div>
<div class="line"><a name="l01108"></a><span class="lineno"> 1108</span> <span class="comment"> * which will be transformed on this call. It is not an error if it</span></div>
<div class="line"><a name="l01109"></a><span class="lineno"> 1109</span> <span class="comment"> * is greater than the distance between 'first1' and 'last1'. If it</span></div>
<div class="line"><a name="l01110"></a><span class="lineno"> 1110</span> <span class="comment"> * is equal to or greater than that distance, it follows that the</span></div>
<div class="line"><a name="l01111"></a><span class="lineno"> 1111</span> <span class="comment"> * first value of the tuple returned by this function will be equal to</span></div>
<div class="line"><a name="l01112"></a><span class="lineno"> 1112</span> <span class="comment"> * 'last1'. The same results if 'max' is a negative number (in that</span></div>
<div class="line"><a name="l01113"></a><span class="lineno"> 1113</span> <span class="comment"> * case no maximum will take effect and all elements in the range</span></div>
<div class="line"><a name="l01114"></a><span class="lineno"> 1114</span> <span class="comment"> * ['first1', 'last1') will be transformed), so passing -1 might be</span></div>
<div class="line"><a name="l01115"></a><span class="lineno"> 1115</span> <span class="comment"> * useful as a means of obtaining a second source iterator (the second</span></div>
<div class="line"><a name="l01116"></a><span class="lineno"> 1116</span> <span class="comment"> * value of the tuple) or destination iterator (the third value) for</span></div>
<div class="line"><a name="l01117"></a><span class="lineno"> 1117</span> <span class="comment"> * other purposes, particularly where they are not random access</span></div>
<div class="line"><a name="l01118"></a><span class="lineno"> 1118</span> <span class="comment"> * iterators.</span></div>
<div class="line"><a name="l01119"></a><span class="lineno"> 1119</span> <span class="comment"> * @param func A binary callable object to be applied (subject to the</span></div>
<div class="line"><a name="l01120"></a><span class="lineno"> 1120</span> <span class="comment"> * maximum) to each element in the source ranges, such as formed by a</span></div>
<div class="line"><a name="l01121"></a><span class="lineno"> 1121</span> <span class="comment"> * lambda expression or the result of std::bind. It should take two</span></div>
<div class="line"><a name="l01122"></a><span class="lineno"> 1122</span> <span class="comment"> * unbound arguments of the value types of the containers to which</span></div>
<div class="line"><a name="l01123"></a><span class="lineno"> 1123</span> <span class="comment"> * 'first1' and 'first2' relate or const or non-const references to</span></div>
<div class="line"><a name="l01124"></a><span class="lineno"> 1124</span> <span class="comment"> * those types. If an exception propagates from 'func', the exception</span></div>
<div class="line"><a name="l01125"></a><span class="lineno"> 1125</span> <span class="comment"> * will be consumed while the transform loop is running, and an</span></div>
<div class="line"><a name="l01126"></a><span class="lineno"> 1126</span> <span class="comment"> * attempt will still be made to apply 'func' to all remaining</span></div>
<div class="line"><a name="l01127"></a><span class="lineno"> 1127</span> <span class="comment"> * elements of the source ranges subject to the maximum, and only</span></div>
<div class="line"><a name="l01128"></a><span class="lineno"> 1128</span> <span class="comment"> * after that attempt has completed will the exception</span></div>
<div class="line"><a name="l01129"></a><span class="lineno"> 1129</span> <span class="comment"> * Cgu::Thread::ParallelError be thrown.</span></div>
<div class="line"><a name="l01130"></a><span class="lineno"> 1130</span> <span class="comment"> * @return A std::tuple object. Its first value is an iterator</span></div>
<div class="line"><a name="l01131"></a><span class="lineno"> 1131</span> <span class="comment"> * representing the element past the last element of the first source</span></div>
<div class="line"><a name="l01132"></a><span class="lineno"> 1132</span> <span class="comment"> * range transformed, which may be passed as the 'first1' argument of</span></div>
<div class="line"><a name="l01133"></a><span class="lineno"> 1133</span> <span class="comment"> * a subsequent call to this function; its second value is an iterator</span></div>
<div class="line"><a name="l01134"></a><span class="lineno"> 1134</span> <span class="comment"> * representing the element past the last element of the second source</span></div>
<div class="line"><a name="l01135"></a><span class="lineno"> 1135</span> <span class="comment"> * range transformed, which may be passed as the 'first2' argument of</span></div>
<div class="line"><a name="l01136"></a><span class="lineno"> 1136</span> <span class="comment"> * the subsequent call; and its third value is an iterator</span></div>
<div class="line"><a name="l01137"></a><span class="lineno"> 1137</span> <span class="comment"> * representing the element past the last element stored in the</span></div>
<div class="line"><a name="l01138"></a><span class="lineno"> 1138</span> <span class="comment"> * destination range, which may be passed as the 'dest' argument of</span></div>
<div class="line"><a name="l01139"></a><span class="lineno"> 1139</span> <span class="comment"> * the subsequent call.</span></div>
<div class="line"><a name="l01140"></a><span class="lineno"> 1140</span> <span class="comment"> * @exception std::bad_alloc This exception will be thrown if memory</span></div>
<div class="line"><a name="l01141"></a><span class="lineno"> 1141</span> <span class="comment"> * is exhausted and the system throws in that case. (On systems with</span></div>
<div class="line"><a name="l01142"></a><span class="lineno"> 1142</span> <span class="comment"> * over-commit/lazy-commit combined with virtual memory (swap), it is</span></div>
<div class="line"><a name="l01143"></a><span class="lineno"> 1143</span> <span class="comment"> * rarely useful to check for memory exhaustion). If this exception</span></div>
<div class="line"><a name="l01144"></a><span class="lineno"> 1144</span> <span class="comment"> * is thrown, some tasks may nonetheless have already started by</span></div>
<div class="line"><a name="l01145"></a><span class="lineno"> 1145</span> <span class="comment"> * virtue of the call to this function, but subsequent ones will not.</span></div>
<div class="line"><a name="l01146"></a><span class="lineno"> 1146</span> <span class="comment"> * @exception Cgu::Thread::TaskError This exception will be thrown if</span></div>
<div class="line"><a name="l01147"></a><span class="lineno"> 1147</span> <span class="comment"> * stop_all() has previously been called on the Thread::TaskManager</span></div>
<div class="line"><a name="l01148"></a><span class="lineno"> 1148</span> <span class="comment"> * object, or if another thread calls stop_all() after this method is</span></div>
<div class="line"><a name="l01149"></a><span class="lineno"> 1149</span> <span class="comment"> * called but before it has returned. It will also be thrown if the</span></div>
<div class="line"><a name="l01150"></a><span class="lineno"> 1150</span> <span class="comment"> * Thread::TaskManager object's is_error() method would return true</span></div>
<div class="line"><a name="l01151"></a><span class="lineno"> 1151</span> <span class="comment"> * because its internal thread pool loop implementation has thrown</span></div>
<div class="line"><a name="l01152"></a><span class="lineno"> 1152</span> <span class="comment"> * std::bad_alloc, or a thread has failed to start correctly because</span></div>
<div class="line"><a name="l01153"></a><span class="lineno"> 1153</span> <span class="comment"> * pthread has run out of resources. (On systems with</span></div>
<div class="line"><a name="l01154"></a><span class="lineno"> 1154</span> <span class="comment"> * over-commit/lazy-commit combined with virtual memory (swap), it is</span></div>
<div class="line"><a name="l01155"></a><span class="lineno"> 1155</span> <span class="comment"> * rarely useful to check for memory exhaustion, and if a reasonable</span></div>
<div class="line"><a name="l01156"></a><span class="lineno"> 1156</span> <span class="comment"> * maximum thread count has been chosen for the Thread::TaskManager</span></div>
<div class="line"><a name="l01157"></a><span class="lineno"> 1157</span> <span class="comment"> * object pthread should not run out of other resources, but there may</span></div>
<div class="line"><a name="l01158"></a><span class="lineno"> 1158</span> <span class="comment"> * be some specialized cases where the return value of is_error() is</span></div>
<div class="line"><a name="l01159"></a><span class="lineno"> 1159</span> <span class="comment"> * useful.) If this exception is thrown, some tasks may nonetheless</span></div>
<div class="line"><a name="l01160"></a><span class="lineno"> 1160</span> <span class="comment"> * have already started by virtue of the call to this function.</span></div>
<div class="line"><a name="l01161"></a><span class="lineno"> 1161</span> <span class="comment"> * @exception Cgu::Thread::ParallelError This exception will be thrown</span></div>
<div class="line"><a name="l01162"></a><span class="lineno"> 1162</span> <span class="comment"> * if an exception propagates from the 'func' callable object when it</span></div>
<div class="line"><a name="l01163"></a><span class="lineno"> 1163</span> <span class="comment"> * executes on being applied to one or more elements of the source</span></div>
<div class="line"><a name="l01164"></a><span class="lineno"> 1164</span> <span class="comment"> * ranges. Such an exception will not stop an attempt being made to</span></div>
<div class="line"><a name="l01165"></a><span class="lineno"> 1165</span> <span class="comment"> * apply 'func' (successfully or unsuccessfully) to all elements in</span></div>
<div class="line"><a name="l01166"></a><span class="lineno"> 1166</span> <span class="comment"> * the source ranges subject to the maximum.</span></div>
<div class="line"><a name="l01167"></a><span class="lineno"> 1167</span> <span class="comment"> * Cgu::Thread::ParallelError will be thrown after such attempted</span></div>
<div class="line"><a name="l01168"></a><span class="lineno"> 1168</span> <span class="comment"> * application has finished.</span></div>
<div class="line"><a name="l01169"></a><span class="lineno"> 1169</span> <span class="comment"> * @exception Cgu::Thread::MutexError This exception will be thrown if</span></div>
<div class="line"><a name="l01170"></a><span class="lineno"> 1170</span> <span class="comment"> * initialization of a mutex used by this function fails. (It is</span></div>
<div class="line"><a name="l01171"></a><span class="lineno"> 1171</span> <span class="comment"> * often not worth checking for this, as it means either memory is</span></div>
<div class="line"><a name="l01172"></a><span class="lineno"> 1172</span> <span class="comment"> * exhausted or pthread has run out of other resources to create new</span></div>
<div class="line"><a name="l01173"></a><span class="lineno"> 1173</span> <span class="comment"> * mutexes.) If this exception is thrown, no tasks will start.</span></div>
<div class="line"><a name="l01174"></a><span class="lineno"> 1174</span> <span class="comment"> * @exception Cgu::Thread::CondError This exception will be thrown if</span></div>
<div class="line"><a name="l01175"></a><span class="lineno"> 1175</span> <span class="comment"> * initialization of a condition variable used by this function fails.</span></div>
<div class="line"><a name="l01176"></a><span class="lineno"> 1176</span> <span class="comment"> * (It is often not worth checking for this, as it means either memory</span></div>
<div class="line"><a name="l01177"></a><span class="lineno"> 1177</span> <span class="comment"> * is exhausted or pthread has run out of other resources to create</span></div>
<div class="line"><a name="l01178"></a><span class="lineno"> 1178</span> <span class="comment"> * new condition variables.) If this exception is thrown, no tasks</span></div>
<div class="line"><a name="l01179"></a><span class="lineno"> 1179</span> <span class="comment"> * will start.</span></div>
<div class="line"><a name="l01180"></a><span class="lineno"> 1180</span> <span class="comment"> * @note An exception might also be thrown if the copy or move</span></div>
<div class="line"><a name="l01181"></a><span class="lineno"> 1181</span> <span class="comment"> * constructor of the 'func' callable objects throws. If such an</span></div>
<div class="line"><a name="l01182"></a><span class="lineno"> 1182</span> <span class="comment"> * exception is thrown, no tasks will start.</span></div>
<div class="line"><a name="l01183"></a><span class="lineno"> 1183</span> <span class="comment"> * </span></div>
<div class="line"><a name="l01184"></a><span class="lineno"> 1184</span> <span class="comment"> * Since 2.0.20/2.2.3</span></div>
<div class="line"><a name="l01185"></a><span class="lineno"> 1185</span> <span class="comment"> */</span></div>
<div class="line"><a name="l01186"></a><span class="lineno"> 1186</span> <span class="keyword">template</span> <<span class="keyword">class</span> SourceIterator1, <span class="keyword">class</span> SourceIterator2, <span class="keyword">class</span> DestIterator, <span class="keyword">class</span> Func></div>
<div class="line"><a name="l01187"></a><span class="lineno"> 1187</span> std::tuple<SourceIterator1, SourceIterator2, DestIterator></div>
<div class="line"><a name="l01188"></a><span class="lineno"><a class="code" href="namespaceCgu_1_1Thread.html#a1548f422f99e63b0eaf53019e5114b34"> 1188</a></span>  <a class="code" href="namespaceCgu_1_1Thread.html#ad03d1d6f6b0718a0b63a850b05fae623">parallel_transform_partial</a>(<a class="code" href="classCgu_1_1Thread_1_1TaskManager.html" title="A thread-pool class for managing tasks in multi-threaded programs. ">TaskManager</a>& tm,</div>
<div class="line"><a name="l01189"></a><span class="lineno"> 1189</span>  SourceIterator1 first1,</div>
<div class="line"><a name="l01190"></a><span class="lineno"> 1190</span>  SourceIterator1 last1,</div>
<div class="line"><a name="l01191"></a><span class="lineno"> 1191</span>  SourceIterator2 first2,</div>
<div class="line"><a name="l01192"></a><span class="lineno"> 1192</span>  DestIterator dest,</div>
<div class="line"><a name="l01193"></a><span class="lineno"> 1193</span>  <span class="keywordtype">int</span> max,</div>
<div class="line"><a name="l01194"></a><span class="lineno"> 1194</span>  Func&& func) {</div>
<div class="line"><a name="l01195"></a><span class="lineno"> 1195</span> </div>
<div class="line"><a name="l01196"></a><span class="lineno"> 1196</span>  <span class="keywordflow">if</span> (first1 == last1 || !max) <span class="keywordflow">return</span> std::make_tuple(first1, first2, dest);</div>
<div class="line"><a name="l01197"></a><span class="lineno"> 1197</span> </div>
<div class="line"><a name="l01198"></a><span class="lineno"> 1198</span>  <span class="keyword">typedef</span> <span class="keyword">typename</span> std::iterator_traits<SourceIterator1>::value_type Arg1Type;</div>
<div class="line"><a name="l01199"></a><span class="lineno"> 1199</span>  <span class="keyword">typedef</span> <span class="keyword">typename</span> std::iterator_traits<SourceIterator1>::difference_type DiffType;</div>
<div class="line"><a name="l01200"></a><span class="lineno"> 1200</span>  <span class="keyword">typedef</span> <span class="keyword">typename</span> std::iterator_traits<SourceIterator2>::value_type Arg2Type;</div>
<div class="line"><a name="l01201"></a><span class="lineno"> 1201</span>  <span class="keyword">typedef</span> <span class="keyword">typename</span> std::remove_const<typename std::remove_reference<Func>::type>::type FType;</div>
<div class="line"><a name="l01202"></a><span class="lineno"> 1202</span>  <span class="keyword">typedef</span> decltype(func(*first1, *first2)) DestType;</div>
<div class="line"><a name="l01203"></a><span class="lineno"> 1203</span> </div>
<div class="line"><a name="l01204"></a><span class="lineno"> 1204</span>  <a class="code" href="classCgu_1_1Thread_1_1Mutex.html" title="A wrapper class for pthread mutexes. ">Mutex</a> mutex;</div>
<div class="line"><a name="l01205"></a><span class="lineno"> 1205</span>  <a class="code" href="classCgu_1_1Thread_1_1Cond.html" title="A wrapper class for pthread condition variables. ">Cond</a> cond;</div>
<div class="line"><a name="l01206"></a><span class="lineno"> 1206</span>  DiffType start_count = 0;</div>
<div class="line"><a name="l01207"></a><span class="lineno"> 1207</span>  DiffType done_count = 0;</div>
<div class="line"><a name="l01208"></a><span class="lineno"> 1208</span>  <span class="keywordtype">bool</span> error = <span class="keyword">false</span>;</div>
<div class="line"><a name="l01209"></a><span class="lineno"> 1209</span> </div>
<div class="line"><a name="l01210"></a><span class="lineno"> 1210</span>  <span class="comment">// a specialization of std::numeric_limits::max() for all arithmetic</span></div>
<div class="line"><a name="l01211"></a><span class="lineno"> 1211</span>  <span class="comment">// types is required by §3.9.1/8 of the standard. The iterator</span></div>
<div class="line"><a name="l01212"></a><span class="lineno"> 1212</span>  <span class="comment">// difference type must be a signed integer type (§24.2.1/1). All</span></div>
<div class="line"><a name="l01213"></a><span class="lineno"> 1213</span>  <span class="comment">// signed integer types are arithmetic types (§3.9.1/2, §3.9.1/7 and</span></div>
<div class="line"><a name="l01214"></a><span class="lineno"> 1214</span>  <span class="comment">// §3.9.1/8).</span></div>
<div class="line"><a name="l01215"></a><span class="lineno"> 1215</span>  <span class="keyword">const</span> DiffType local_max =</div>
<div class="line"><a name="l01216"></a><span class="lineno"> 1216</span>  (max >= 0) ? max : std::numeric_limits<DiffType>::max();</div>
<div class="line"><a name="l01217"></a><span class="lineno"> 1217</span> </div>
<div class="line"><a name="l01218"></a><span class="lineno"> 1218</span>  <span class="comment">// intermediate results have to be held in an array so destination</span></div>
<div class="line"><a name="l01219"></a><span class="lineno"> 1219</span>  <span class="comment">// ordering can be enforced when using insert interators. This</span></div>
<div class="line"><a name="l01220"></a><span class="lineno"> 1220</span>  <span class="comment">// causes some inefficiency for non-random access iterators</span></div>
<div class="line"><a name="l01221"></a><span class="lineno"> 1221</span>  std::unique_ptr<DestType[]> results(<span class="keyword">new</span> DestType[std::min(local_max,</div>
<div class="line"><a name="l01222"></a><span class="lineno"> 1222</span>  std::distance(first1, last1))]);</div>
<div class="line"><a name="l01223"></a><span class="lineno"> 1223</span> </div>
<div class="line"><a name="l01224"></a><span class="lineno"> 1224</span>  <span class="comment">// construct SafeFunctorArg objects so that they can be shared</span></div>
<div class="line"><a name="l01225"></a><span class="lineno"> 1225</span>  <span class="comment">// between different tasks</span></div>
<div class="line"><a name="l01226"></a><span class="lineno"> 1226</span>  <a class="code" href="classCgu_1_1Callback_1_1SafeFunctorArg.html" title="Functor class holding a Callback::CallbackArg object, with thread-safe reference count. ">Cgu::Callback::SafeFunctorArg<Arg1Type&, Arg2Type&, DestType&></a> s_task{</div>
<div class="line"><a name="l01227"></a><span class="lineno"> 1227</span>  <a class="code" href="namespaceCgu_1_1Callback.html#a94b122ac99f423928320240fd48d571b">Cgu::Callback::make_ref</a>(&ParallelHelper2::transform2_func<FType, Arg1Type, Arg2Type, DestType>,</div>
<div class="line"><a name="l01228"></a><span class="lineno"> 1228</span>  std::forward<Func>(func))</div>
<div class="line"><a name="l01229"></a><span class="lineno"> 1229</span>  };</div>
<div class="line"><a name="l01230"></a><span class="lineno"> 1230</span>  <a class="code" href="classCgu_1_1Callback_1_1SafeFunctorArg.html" title="Functor class holding a Callback::CallbackArg object, with thread-safe reference count. ">Cgu::Callback::SafeFunctor</a> s_fail{</div>
<div class="line"><a name="l01231"></a><span class="lineno"> 1231</span>  <a class="code" href="namespaceCgu_1_1Callback.html#a3e32d4f4961c618aa7e03bda00f398b8">Cgu::Callback::make</a>(&ParallelHelper2::fail_func<DiffType>,</div>
<div class="line"><a name="l01232"></a><span class="lineno"> 1232</span>  &mutex,</div>
<div class="line"><a name="l01233"></a><span class="lineno"> 1233</span>  &cond,</div>
<div class="line"><a name="l01234"></a><span class="lineno"> 1234</span>  &error,</div>
<div class="line"><a name="l01235"></a><span class="lineno"> 1235</span>  &done_count)</div>
<div class="line"><a name="l01236"></a><span class="lineno"> 1236</span>  };</div>
<div class="line"><a name="l01237"></a><span class="lineno"> 1237</span> </div>
<div class="line"><a name="l01238"></a><span class="lineno"> 1238</span>  <span class="keywordflow">for</span> (; first1 != last1 && start_count < local_max; ++first1, ++first2, ++start_count) {</div>
<div class="line"><a name="l01239"></a><span class="lineno"> 1239</span>  std::unique_ptr<const Cgu::Callback::Callback> task_cb(</div>
<div class="line"><a name="l01240"></a><span class="lineno"> 1240</span>  Cgu::Callback::lambda<>(std::bind(&ParallelHelper2::transform2_cb_func<Arg1Type, Arg2Type, DestType, DiffType, SourceIterator1, SourceIterator2>,</div>
<div class="line"><a name="l01241"></a><span class="lineno"> 1241</span>  s_task,</div>
<div class="line"><a name="l01242"></a><span class="lineno"> 1242</span>  first1,</div>
<div class="line"><a name="l01243"></a><span class="lineno"> 1243</span>  first2,</div>
<div class="line"><a name="l01244"></a><span class="lineno"> 1244</span>  &mutex,</div>
<div class="line"><a name="l01245"></a><span class="lineno"> 1245</span>  &cond,</div>
<div class="line"><a name="l01246"></a><span class="lineno"> 1246</span>  &done_count,</div>
<div class="line"><a name="l01247"></a><span class="lineno"> 1247</span>  results.get(),</div>
<div class="line"><a name="l01248"></a><span class="lineno"> 1248</span>  start_count))</div>
<div class="line"><a name="l01249"></a><span class="lineno"> 1249</span>  );</div>
<div class="line"><a name="l01250"></a><span class="lineno"> 1250</span>  std::unique_ptr<const Cgu::Callback::Callback> fail_cb(</div>
<div class="line"><a name="l01251"></a><span class="lineno"> 1251</span>  Cgu::Callback::lambda<>([s_fail] () {s_fail();})</div>
<div class="line"><a name="l01252"></a><span class="lineno"> 1252</span>  );</div>
<div class="line"><a name="l01253"></a><span class="lineno"> 1253</span> </div>
<div class="line"><a name="l01254"></a><span class="lineno"> 1254</span>  tm.<a class="code" href="classCgu_1_1Thread_1_1TaskManager.html#a81f7c8af3295d92c0e19d7f9498a4078">add_task</a>(std::move(task_cb), std::move(fail_cb));</div>
<div class="line"><a name="l01255"></a><span class="lineno"> 1255</span>  }</div>
<div class="line"><a name="l01256"></a><span class="lineno"> 1256</span>  </div>
<div class="line"><a name="l01257"></a><span class="lineno"> 1257</span>  <a class="code" href="classCgu_1_1Thread_1_1Mutex_1_1Lock.html" title="A scoped locking class for exception safe Mutex locking. ">Mutex::Lock</a> l{mutex};</div>
<div class="line"><a name="l01258"></a><span class="lineno"> 1258</span>  <span class="keywordflow">while</span> (start_count > done_count) cond.<a class="code" href="classCgu_1_1Thread_1_1Cond.html#a5eda52c227552555102bb45010a8f6c9">wait</a>(mutex);</div>
<div class="line"><a name="l01259"></a><span class="lineno"> 1259</span>  <span class="keywordflow">if</span> (error) <span class="keywordflow">throw</span> <a class="code" href="structCgu_1_1Thread_1_1ParallelError.html">ParallelError</a>();</div>
<div class="line"><a name="l01260"></a><span class="lineno"> 1260</span>  <span class="keywordflow">for</span> (DiffType index = 0; index < start_count; ++dest, ++index) {</div>
<div class="line"><a name="l01261"></a><span class="lineno"> 1261</span>  *dest = std::move(results[index]);</div>
<div class="line"><a name="l01262"></a><span class="lineno"> 1262</span>  }</div>
<div class="line"><a name="l01263"></a><span class="lineno"> 1263</span>  <span class="keywordflow">return</span> std::make_tuple(first1, first2, dest);</div>
<div class="line"><a name="l01264"></a><span class="lineno"> 1264</span> }</div>
<div class="line"><a name="l01265"></a><span class="lineno"> 1265</span> </div>
<div class="line"><a name="l01266"></a><span class="lineno"> 1266</span> } <span class="comment">// namespace Thread</span></div>
<div class="line"><a name="l01267"></a><span class="lineno"> 1267</span> </div>
<div class="line"><a name="l01268"></a><span class="lineno"> 1268</span> } <span class="comment">// namespace Cgu</span></div>
<div class="line"><a name="l01269"></a><span class="lineno"> 1269</span> </div>
<div class="line"><a name="l01270"></a><span class="lineno"> 1270</span> <span class="preprocessor">#endif // CGU_PARALLEL_H</span></div>
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