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From git-site-r...@apache.org
Subject [07/10] mesos-site git commit: Updated the website built from mesos SHA: b1eafc0.
Date Sun, 15 Jul 2018 23:22:16 GMT
http://git-wip-us.apache.org/repos/asf/mesos-site/blob/1ce9f4ab/content/api/latest/c++/event__queue_8hpp_source.html
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diff --git a/content/api/latest/c++/event__queue_8hpp_source.html b/content/api/latest/c++/event__queue_8hpp_source.html
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@@ -52,7 +52,8 @@
 <div class="title">event_queue.hpp</div>  </div>
 </div><!--header-->
 <div class="contents">
-<a href="event__queue_8hpp.html">Go to the documentation of this file.</a><div class="fragment"><div class="line"><a name="l00001"></a><span class="lineno">    1</span>&#160;<span class="comment">// Licensed under the Apache License, Version 2.0 (the &quot;License&quot;);</span></div><div class="line"><a name="l00002"></a><span class="lineno">    2</span>&#160;<span class="comment">// you may not use this file except in compliance with the License.</span></div><div class="line"><a name="l00003"></a><span class="lineno">    3</span>&#160;<span class="comment">// You may obtain a copy of the License at</span></div><div class="line"><a name="l00004"></a><span class="lineno">    4</span>&#160;<span class="comment">//</span></div><div class="line"><a name="l00005"></a><span class="lineno">    5</span>&#160;<span class="comment">//     http://www.apache.org/licenses/LICENSE-2.0</span></div><div class="line"><a name="l00006"></a><span class="lineno">    6</span>&#160;<span class="comment">
 //</span></div><div class="line"><a name="l00007"></a><span class="lineno">    7</span>&#160;<span class="comment">// Unless required by applicable law or agreed to in writing, software</span></div><div class="line"><a name="l00008"></a><span class="lineno">    8</span>&#160;<span class="comment">// distributed under the License is distributed on an &quot;AS IS&quot; BASIS,</span></div><div class="line"><a name="l00009"></a><span class="lineno">    9</span>&#160;<span class="comment">// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.</span></div><div class="line"><a name="l00010"></a><span class="lineno">   10</span>&#160;<span class="comment">// See the License for the specific language governing permissions and</span></div><div class="line"><a name="l00011"></a><span class="lineno">   11</span>&#160;<span class="comment">// limitations under the License</span></div><div class="line"><a name="l00012"></a><span class="lineno">   12</span>&#160;</div><div cla
 ss="line"><a name="l00013"></a><span class="lineno">   13</span>&#160;<span class="preprocessor">#ifndef __PROCESS_EVENT_QUEUE_HPP__</span></div><div class="line"><a name="l00014"></a><span class="lineno">   14</span>&#160;<span class="preprocessor">#define __PROCESS_EVENT_QUEUE_HPP__</span></div><div class="line"><a name="l00015"></a><span class="lineno">   15</span>&#160;</div><div class="line"><a name="l00016"></a><span class="lineno">   16</span>&#160;<span class="preprocessor">#include &lt;deque&gt;</span></div><div class="line"><a name="l00017"></a><span class="lineno">   17</span>&#160;<span class="preprocessor">#include &lt;mutex&gt;</span></div><div class="line"><a name="l00018"></a><span class="lineno">   18</span>&#160;<span class="preprocessor">#include &lt;string&gt;</span></div><div class="line"><a name="l00019"></a><span class="lineno">   19</span>&#160;</div><div class="line"><a name="l00020"></a><span class="lineno">   20</span>&#160;<span class="preprocessor">#ifde
 f LOCK_FREE_EVENT_QUEUE</span></div><div class="line"><a name="l00021"></a><span class="lineno">   21</span>&#160;<span class="preprocessor">#include &lt;concurrentqueue.h&gt;</span></div><div class="line"><a name="l00022"></a><span class="lineno">   22</span>&#160;<span class="preprocessor">#endif // LOCK_FREE_EVENT_QUEUE</span></div><div class="line"><a name="l00023"></a><span class="lineno">   23</span>&#160;</div><div class="line"><a name="l00024"></a><span class="lineno">   24</span>&#160;<span class="preprocessor">#include &lt;<a class="code" href="event_8hpp.html">process/event.hpp</a>&gt;</span></div><div class="line"><a name="l00025"></a><span class="lineno">   25</span>&#160;<span class="preprocessor">#include &lt;<a class="code" href="3rdparty_2libprocess_2include_2process_2http_8hpp.html">process/http.hpp</a>&gt;</span></div><div class="line"><a name="l00026"></a><span class="lineno">   26</span>&#160;</div><div class="line"><a name="l00027"></a><span class="lineno">   2
 7</span>&#160;<span class="preprocessor">#include &lt;<a class="code" href="json_8hpp.html">stout/json.hpp</a>&gt;</span></div><div class="line"><a name="l00028"></a><span class="lineno">   28</span>&#160;<span class="preprocessor">#include &lt;<a class="code" href="stringify_8hpp.html">stout/stringify.hpp</a>&gt;</span></div><div class="line"><a name="l00029"></a><span class="lineno">   29</span>&#160;<span class="preprocessor">#include &lt;<a class="code" href="synchronized_8hpp.html">stout/synchronized.hpp</a>&gt;</span></div><div class="line"><a name="l00030"></a><span class="lineno">   30</span>&#160;</div><div class="line"><a name="l00031"></a><span class="lineno">   31</span>&#160;<span class="keyword">namespace </span><a class="code" href="namespaceprocess.html">process</a> {</div><div class="line"><a name="l00032"></a><span class="lineno">   32</span>&#160;</div><div class="line"><a name="l00033"></a><span class="lineno">   33</span>&#160;<span class="comment">// A _multipl
 e_ producer (MP) _single_ consumer (SC) event queue for a</span></div><div class="line"><a name="l00034"></a><span class="lineno">   34</span>&#160;<span class="comment">// process. Note that we don&#39;t _enforce_ the MP/SC semantics during</span></div><div class="line"><a name="l00035"></a><span class="lineno">   35</span>&#160;<span class="comment">// runtime but we have explicitly separated out the `Producer`</span></div><div class="line"><a name="l00036"></a><span class="lineno">   36</span>&#160;<span class="comment">// interface and the `Consumer` interface in order to help avoid</span></div><div class="line"><a name="l00037"></a><span class="lineno">   37</span>&#160;<span class="comment">// incorrect usage.</span></div><div class="line"><a name="l00038"></a><span class="lineno">   38</span>&#160;<span class="comment">//</span></div><div class="line"><a name="l00039"></a><span class="lineno">   39</span>&#160;<span class="comment">// Notable semantics:</span></div><div class
 ="line"><a name="l00040"></a><span class="lineno">   40</span>&#160;<span class="comment">//</span></div><div class="line"><a name="l00041"></a><span class="lineno">   41</span>&#160;<span class="comment">//   * Consumers _must_ call `empty()` before calling</span></div><div class="line"><a name="l00042"></a><span class="lineno">   42</span>&#160;<span class="comment">//     `dequeue()`. Failing to do so may result in undefined behavior.</span></div><div class="line"><a name="l00043"></a><span class="lineno">   43</span>&#160;<span class="comment">//</span></div><div class="line"><a name="l00044"></a><span class="lineno">   44</span>&#160;<span class="comment">//   * After a consumer calls `decomission()` they _must_ not call any</span></div><div class="line"><a name="l00045"></a><span class="lineno">   45</span>&#160;<span class="comment">//     thing else (not even `empty()` and especially not</span></div><div class="line"><a name="l00046"></a><span class="lineno">   46</span>&#16
 0;<span class="comment">//     `dequeue()`). Doing so is undefined behavior.</span></div><div class="line"><a name="l00047"></a><span class="lineno">   47</span>&#160;<span class="comment">//</span></div><div class="line"><a name="l00048"></a><span class="lineno">   48</span>&#160;<span class="comment">// Notes on the lock-free implementation:</span></div><div class="line"><a name="l00049"></a><span class="lineno">   49</span>&#160;<span class="comment">//</span></div><div class="line"><a name="l00050"></a><span class="lineno">   50</span>&#160;<span class="comment">// The SC requirement is necessary for the lock-free implementation</span></div><div class="line"><a name="l00051"></a><span class="lineno">   51</span>&#160;<span class="comment">// because the underlying queue does not provide linearizability which</span></div><div class="line"><a name="l00052"></a><span class="lineno">   52</span>&#160;<span class="comment">// means events can be dequeued &quot;out of order&quot;. Usu
 ally this is not a</span></div><div class="line"><a name="l00053"></a><span class="lineno">   53</span>&#160;<span class="comment">// problem, after all, in most circumstances we won&#39;t know the order</span></div><div class="line"><a name="l00054"></a><span class="lineno">   54</span>&#160;<span class="comment">// in which events might be enqueued in the first place. However, this</span></div><div class="line"><a name="l00055"></a><span class="lineno">   55</span>&#160;<span class="comment">// can be a very bad problem if a single process attempts to enqueue</span></div><div class="line"><a name="l00056"></a><span class="lineno">   56</span>&#160;<span class="comment">// two events in a different process AND THOSE EVENTS ARE</span></div><div class="line"><a name="l00057"></a><span class="lineno">   57</span>&#160;<span class="comment">// REORDERED. To ensure this will never be the case we give every</span></div><div class="line"><a name="l00058"></a><span class="lineno">   58</sp
 an>&#160;<span class="comment">// event a sequence number. That way an event from the same process</span></div><div class="line"><a name="l00059"></a><span class="lineno">   59</span>&#160;<span class="comment">// will always have a happens-before relationship with respect to the</span></div><div class="line"><a name="l00060"></a><span class="lineno">   60</span>&#160;<span class="comment">// events that they enqueue because they&#39;ll have distinct sequence</span></div><div class="line"><a name="l00061"></a><span class="lineno">   61</span>&#160;<span class="comment">// numbers.</span></div><div class="line"><a name="l00062"></a><span class="lineno">   62</span>&#160;<span class="comment">//</span></div><div class="line"><a name="l00063"></a><span class="lineno">   63</span>&#160;<span class="comment">// This makes the consumer implementation more difficult because the</span></div><div class="line"><a name="l00064"></a><span class="lineno">   64</span>&#160;<span class="comment">/
 / consumer might need to &quot;reorder&quot; events as it reads them out. To do</span></div><div class="line"><a name="l00065"></a><span class="lineno">   65</span>&#160;<span class="comment">// this efficiently we require only a single consumer, which fits well</span></div><div class="line"><a name="l00066"></a><span class="lineno">   66</span>&#160;<span class="comment">// into the actor model because there will only ever be a single</span></div><div class="line"><a name="l00067"></a><span class="lineno">   67</span>&#160;<span class="comment">// thread consuming an actors events at a time.</span></div><div class="line"><a name="l00068"></a><span class="lineno"><a class="line" href="classprocess_1_1EventQueue.html">   68</a></span>&#160;<span class="keyword">class </span><a class="code" href="classprocess_1_1EventQueue.html">EventQueue</a></div><div class="line"><a name="l00069"></a><span class="lineno">   69</span>&#160;{</div><div class="line"><a name="l00070"></a><span class="l
 ineno">   70</span>&#160;<span class="keyword">public</span>:</div><div class="line"><a name="l00071"></a><span class="lineno"><a class="line" href="classprocess_1_1EventQueue.html#ad2d51d8a2a80f473de0bcf2e08e48d90">   71</a></span>&#160;  <a class="code" href="classprocess_1_1EventQueue.html#ad2d51d8a2a80f473de0bcf2e08e48d90">EventQueue</a>() : <a class="code" href="classprocess_1_1EventQueue.html#aa95046266e731af49ccfb9d689cb1eca">producer</a>(this), <a class="code" href="classprocess_1_1EventQueue.html#a73f44b10f6d09ead6bdf3ab11cba4d06">consumer</a>(this) {}</div><div class="line"><a name="l00072"></a><span class="lineno">   72</span>&#160;</div><div class="line"><a name="l00073"></a><span class="lineno"><a class="line" href="classprocess_1_1EventQueue_1_1Producer.html">   73</a></span>&#160;  <span class="keyword">class </span><a class="code" href="classprocess_1_1EventQueue_1_1Producer.html">Producer</a></div><div class="line"><a name="l00074"></a><span class="lineno">   74</sp
 an>&#160;  {</div><div class="line"><a name="l00075"></a><span class="lineno">   75</span>&#160;  <span class="keyword">public</span>:</div><div class="line"><a name="l00076"></a><span class="lineno"><a class="line" href="classprocess_1_1EventQueue_1_1Producer.html#a30a6a96aad51b429e48eba775a4a002d">   76</a></span>&#160;    <span class="keywordtype">void</span> <a class="code" href="classprocess_1_1EventQueue_1_1Producer.html#a30a6a96aad51b429e48eba775a4a002d">enqueue</a>(<a class="code" href="structprocess_1_1Event.html">Event</a>* event) { queue-&gt;enqueue(event); }</div><div class="line"><a name="l00077"></a><span class="lineno">   77</span>&#160;</div><div class="line"><a name="l00078"></a><span class="lineno">   78</span>&#160;  <span class="keyword">private</span>:</div><div class="line"><a name="l00079"></a><span class="lineno"><a class="line" href="classprocess_1_1EventQueue_1_1Producer.html#a3b1787a64e5e97ce075c05a58303d58c">   79</a></span>&#160;    <span class="keyword"
 >friend</span> <span class="keyword">class </span><a class="code" href="classprocess_1_1EventQueue.html">EventQueue</a>;</div><div class="line"><a name="l00080"></a><span class="lineno">   80</span>&#160;</div><div class="line"><a name="l00081"></a><span class="lineno">   81</span>&#160;    <a class="code" href="classprocess_1_1EventQueue_1_1Producer.html">Producer</a>(<a class="code" href="classprocess_1_1EventQueue.html">EventQueue</a>* queue) : queue(queue) {}</div><div class="line"><a name="l00082"></a><span class="lineno">   82</span>&#160;</div><div class="line"><a name="l00083"></a><span class="lineno">   83</span>&#160;    <a class="code" href="classprocess_1_1EventQueue.html">EventQueue</a>* queue;</div><div class="line"><a name="l00084"></a><span class="lineno">   84</span>&#160;  } <a class="code" href="classprocess_1_1EventQueue.html#aa95046266e731af49ccfb9d689cb1eca">producer</a>;</div><div class="line"><a name="l00085"></a><span class="lineno">   85</span>&#160;</div><
 div class="line"><a name="l00086"></a><span class="lineno"><a class="line" href="classprocess_1_1EventQueue_1_1Consumer.html">   86</a></span>&#160;  <span class="keyword">class </span><a class="code" href="classprocess_1_1EventQueue_1_1Consumer.html">Consumer</a></div><div class="line"><a name="l00087"></a><span class="lineno">   87</span>&#160;  {</div><div class="line"><a name="l00088"></a><span class="lineno">   88</span>&#160;  <span class="keyword">public</span>:</div><div class="line"><a name="l00089"></a><span class="lineno"><a class="line" href="classprocess_1_1EventQueue_1_1Consumer.html#a0947a38c4933c27cc6b422ce9171a400">   89</a></span>&#160;    <a class="code" href="structprocess_1_1Event.html">Event</a>* <a class="code" href="classprocess_1_1EventQueue_1_1Consumer.html#a0947a38c4933c27cc6b422ce9171a400">dequeue</a>() { <span class="keywordflow">return</span> queue-&gt;dequeue(); }</div><div class="line"><a name="l00090"></a><span class="lineno"><a class="line" href="cl
 assprocess_1_1EventQueue_1_1Consumer.html#aa42de8d3e7ba7c56362a36efa773790d">   90</a></span>&#160;    <span class="keywordtype">bool</span> <a class="code" href="classprocess_1_1EventQueue_1_1Consumer.html#aa42de8d3e7ba7c56362a36efa773790d">empty</a>() { <span class="keywordflow">return</span> queue-&gt;empty(); }</div><div class="line"><a name="l00091"></a><span class="lineno"><a class="line" href="classprocess_1_1EventQueue_1_1Consumer.html#a7976eeb2b9ff88c5f03551c63764a162">   91</a></span>&#160;    <span class="keywordtype">void</span> <a class="code" href="classprocess_1_1EventQueue_1_1Consumer.html#a7976eeb2b9ff88c5f03551c63764a162">decomission</a>() { queue-&gt;decomission(); }</div><div class="line"><a name="l00092"></a><span class="lineno">   92</span>&#160;    <span class="keyword">template</span> &lt;<span class="keyword">typename</span> T&gt;</div><div class="line"><a name="l00093"></a><span class="lineno"><a class="line" href="classprocess_1_1EventQueue_1_1Consumer.htm
 l#a8d998919af90a6146e6745a1217be3ce">   93</a></span>&#160;    <span class="keywordtype">size_t</span> <a class="code" href="classprocess_1_1EventQueue_1_1Consumer.html#a8d998919af90a6146e6745a1217be3ce">count</a>() { <span class="keywordflow">return</span> queue-&gt;count&lt;T&gt;(); }</div><div class="line"><a name="l00094"></a><span class="lineno"><a class="line" href="classprocess_1_1EventQueue_1_1Consumer.html#a307aaa062d7b5feee064e0361a3cb166">   94</a></span>&#160;    <span class="keyword">operator</span> <a class="code" href="structJSON_1_1Array.html">JSON::Array</a>() { <span class="keywordflow">return</span> queue-&gt;operator <a class="code" href="structJSON_1_1Array.html">JSON::Array</a>(); }</div><div class="line"><a name="l00095"></a><span class="lineno">   95</span>&#160;</div><div class="line"><a name="l00096"></a><span class="lineno">   96</span>&#160;  <span class="keyword">private</span>:</div><div class="line"><a name="l00097"></a><span class="lineno"><a class="l
 ine" href="classprocess_1_1EventQueue_1_1Consumer.html#a3b1787a64e5e97ce075c05a58303d58c">   97</a></span>&#160;    <span class="keyword">friend</span> <span class="keyword">class </span><a class="code" href="classprocess_1_1EventQueue.html">EventQueue</a>;</div><div class="line"><a name="l00098"></a><span class="lineno">   98</span>&#160;</div><div class="line"><a name="l00099"></a><span class="lineno">   99</span>&#160;    <a class="code" href="classprocess_1_1EventQueue.html#a11390aaa07bced511a5b7fe4c94e97fd">Consumer</a>(<a class="code" href="classprocess_1_1EventQueue.html">EventQueue</a>* queue) : queue(queue) {}</div><div class="line"><a name="l00100"></a><span class="lineno">  100</span>&#160;</div><div class="line"><a name="l00101"></a><span class="lineno">  101</span>&#160;    <a class="code" href="classprocess_1_1EventQueue.html">EventQueue</a>* queue;</div><div class="line"><a name="l00102"></a><span class="lineno">  102</span>&#160;  } <a class="code" href="classprocess
 _1_1EventQueue.html#a73f44b10f6d09ead6bdf3ab11cba4d06">consumer</a>;</div><div class="line"><a name="l00103"></a><span class="lineno">  103</span>&#160;</div><div class="line"><a name="l00104"></a><span class="lineno">  104</span>&#160;<span class="keyword">private</span>:</div><div class="line"><a name="l00105"></a><span class="lineno"><a class="line" href="classprocess_1_1EventQueue.html#aaf00b363e56ec3a72a6f775a3814d6a0">  105</a></span>&#160;  <span class="keyword">friend</span> <span class="keyword">class </span><a class="code" href="classprocess_1_1EventQueue_1_1Producer.html">Producer</a>;</div><div class="line"><a name="l00106"></a><span class="lineno"><a class="line" href="classprocess_1_1EventQueue.html#a11390aaa07bced511a5b7fe4c94e97fd">  106</a></span>&#160;  <span class="keyword">friend</span> <span class="keyword">class </span><a class="code" href="classprocess_1_1EventQueue_1_1Consumer.html">Consumer</a>;</div><div class="line"><a name="l00107"></a><span class="lineno
 ">  107</span>&#160;</div><div class="line"><a name="l00108"></a><span class="lineno">  108</span>&#160;<span class="preprocessor">#ifndef LOCK_FREE_EVENT_QUEUE</span></div><div class="line"><a name="l00109"></a><span class="lineno">  109</span>&#160;  <span class="keywordtype">void</span> <a class="code" href="classprocess_1_1EventQueue_1_1Producer.html#a30a6a96aad51b429e48eba775a4a002d">enqueue</a>(<a class="code" href="structprocess_1_1Event.html">Event</a>* event)</div><div class="line"><a name="l00110"></a><span class="lineno">  110</span>&#160;  {</div><div class="line"><a name="l00111"></a><span class="lineno">  111</span>&#160;    <span class="keywordtype">bool</span> enqueued = <span class="keyword">false</span>;</div><div class="line"><a name="l00112"></a><span class="lineno">  112</span>&#160;    <span class="keyword">synchronized</span> (mutex) {</div><div class="line"><a name="l00113"></a><span class="lineno">  113</span>&#160;      <span class="keywordflow">if</span> (
 comissioned) {</div><div class="line"><a name="l00114"></a><span class="lineno">  114</span>&#160;        events.push_back(event);</div><div class="line"><a name="l00115"></a><span class="lineno">  115</span>&#160;        enqueued = <span class="keyword">true</span>;</div><div class="line"><a name="l00116"></a><span class="lineno">  116</span>&#160;      }</div><div class="line"><a name="l00117"></a><span class="lineno">  117</span>&#160;    }</div><div class="line"><a name="l00118"></a><span class="lineno">  118</span>&#160;</div><div class="line"><a name="l00119"></a><span class="lineno">  119</span>&#160;    <span class="keywordflow">if</span> (!enqueued) {</div><div class="line"><a name="l00120"></a><span class="lineno">  120</span>&#160;      <span class="keyword">delete</span> event;</div><div class="line"><a name="l00121"></a><span class="lineno">  121</span>&#160;    }</div><div class="line"><a name="l00122"></a><span class="lineno">  122</span>&#160;  }</div><div class="lin
 e"><a name="l00123"></a><span class="lineno">  123</span>&#160;</div><div class="line"><a name="l00124"></a><span class="lineno">  124</span>&#160;  <a class="code" href="structprocess_1_1Event.html">Event</a>* dequeue()</div><div class="line"><a name="l00125"></a><span class="lineno">  125</span>&#160;  {</div><div class="line"><a name="l00126"></a><span class="lineno">  126</span>&#160;    <a class="code" href="structprocess_1_1Event.html">Event</a>* <span class="keyword">event</span> = <span class="keyword">nullptr</span>;</div><div class="line"><a name="l00127"></a><span class="lineno">  127</span>&#160;</div><div class="line"><a name="l00128"></a><span class="lineno">  128</span>&#160;    <span class="keyword">synchronized</span> (mutex) {</div><div class="line"><a name="l00129"></a><span class="lineno">  129</span>&#160;      <span class="keywordflow">if</span> (events.size() &gt; 0) {</div><div class="line"><a name="l00130"></a><span class="lineno">  130</span>&#160;        <
 a class="code" href="structprocess_1_1Event.html">Event</a>* <span class="keyword">event</span> = events.front();</div><div class="line"><a name="l00131"></a><span class="lineno">  131</span>&#160;        events.pop_front();</div><div class="line"><a name="l00132"></a><span class="lineno">  132</span>&#160;        <span class="keywordflow">return</span> event;</div><div class="line"><a name="l00133"></a><span class="lineno">  133</span>&#160;      }</div><div class="line"><a name="l00134"></a><span class="lineno">  134</span>&#160;    }</div><div class="line"><a name="l00135"></a><span class="lineno">  135</span>&#160;</div><div class="line"><a name="l00136"></a><span class="lineno">  136</span>&#160;    <span class="comment">// Semantics are the consumer _must_ call `empty()` before calling</span></div><div class="line"><a name="l00137"></a><span class="lineno">  137</span>&#160;    <span class="comment">// `dequeue()` which means an event must be present.</span></div><div class="l
 ine"><a name="l00138"></a><span class="lineno">  138</span>&#160;    <span class="keywordflow">return</span> CHECK_NOTNULL(event);</div><div class="line"><a name="l00139"></a><span class="lineno">  139</span>&#160;  }</div><div class="line"><a name="l00140"></a><span class="lineno">  140</span>&#160;</div><div class="line"><a name="l00141"></a><span class="lineno">  141</span>&#160;  <span class="keywordtype">bool</span> empty()</div><div class="line"><a name="l00142"></a><span class="lineno">  142</span>&#160;  {</div><div class="line"><a name="l00143"></a><span class="lineno">  143</span>&#160;    <span class="keyword">synchronized</span> (mutex) {</div><div class="line"><a name="l00144"></a><span class="lineno">  144</span>&#160;      <span class="keywordflow">return</span> events.size() == 0;</div><div class="line"><a name="l00145"></a><span class="lineno">  145</span>&#160;    }</div><div class="line"><a name="l00146"></a><span class="lineno">  146</span>&#160;  }</div><div cla
 ss="line"><a name="l00147"></a><span class="lineno">  147</span>&#160;</div><div class="line"><a name="l00148"></a><span class="lineno">  148</span>&#160;  <span class="keywordtype">void</span> decomission()</div><div class="line"><a name="l00149"></a><span class="lineno">  149</span>&#160;  {</div><div class="line"><a name="l00150"></a><span class="lineno">  150</span>&#160;    <span class="keyword">synchronized</span> (mutex) {</div><div class="line"><a name="l00151"></a><span class="lineno">  151</span>&#160;      comissioned = <span class="keyword">false</span>;</div><div class="line"><a name="l00152"></a><span class="lineno">  152</span>&#160;      <span class="keywordflow">while</span> (!events.empty()) {</div><div class="line"><a name="l00153"></a><span class="lineno">  153</span>&#160;        <a class="code" href="structprocess_1_1Event.html">Event</a>* <span class="keyword">event</span> = events.front();</div><div class="line"><a name="l00154"></a><span class="lineno">  154
 </span>&#160;        events.pop_front();</div><div class="line"><a name="l00155"></a><span class="lineno">  155</span>&#160;        <span class="keyword">delete</span> event;</div><div class="line"><a name="l00156"></a><span class="lineno">  156</span>&#160;      }</div><div class="line"><a name="l00157"></a><span class="lineno">  157</span>&#160;    }</div><div class="line"><a name="l00158"></a><span class="lineno">  158</span>&#160;  }</div><div class="line"><a name="l00159"></a><span class="lineno">  159</span>&#160;</div><div class="line"><a name="l00160"></a><span class="lineno">  160</span>&#160;  <span class="keyword">template</span> &lt;<span class="keyword">typename</span> T&gt;</div><div class="line"><a name="l00161"></a><span class="lineno">  161</span>&#160;  <span class="keywordtype">size_t</span> count()</div><div class="line"><a name="l00162"></a><span class="lineno">  162</span>&#160;  {</div><div class="line"><a name="l00163"></a><span class="lineno">  163</span>&#1
 60;    <span class="keyword">synchronized</span> (mutex) {</div><div class="line"><a name="l00164"></a><span class="lineno">  164</span>&#160;      <span class="keywordflow">return</span> std::count_if(</div><div class="line"><a name="l00165"></a><span class="lineno">  165</span>&#160;          events.begin(),</div><div class="line"><a name="l00166"></a><span class="lineno">  166</span>&#160;          events.end(),</div><div class="line"><a name="l00167"></a><span class="lineno">  167</span>&#160;          [](<span class="keyword">const</span> <a class="code" href="structprocess_1_1Event.html">Event</a>* event) {</div><div class="line"><a name="l00168"></a><span class="lineno">  168</span>&#160;            <span class="keywordflow">return</span> <span class="keyword">event</span>-&gt;is&lt;T&gt;();</div><div class="line"><a name="l00169"></a><span class="lineno">  169</span>&#160;          });</div><div class="line"><a name="l00170"></a><span class="lineno">  170</span>&#160;    }</
 div><div class="line"><a name="l00171"></a><span class="lineno">  171</span>&#160;  }</div><div class="line"><a name="l00172"></a><span class="lineno">  172</span>&#160;</div><div class="line"><a name="l00173"></a><span class="lineno">  173</span>&#160;  <span class="keyword">operator</span> <a class="code" href="structJSON_1_1Array.html">JSON::Array</a>()</div><div class="line"><a name="l00174"></a><span class="lineno">  174</span>&#160;  {</div><div class="line"><a name="l00175"></a><span class="lineno">  175</span>&#160;    <a class="code" href="structJSON_1_1Array.html">JSON::Array</a> array;</div><div class="line"><a name="l00176"></a><span class="lineno">  176</span>&#160;    <span class="keyword">synchronized</span> (mutex) {</div><div class="line"><a name="l00177"></a><span class="lineno">  177</span>&#160;      <span class="keywordflow">foreach</span> (<a class="code" href="structprocess_1_1Event.html">Event</a>* event, events) {</div><div class="line"><a name="l00178"></a>
 <span class="lineno">  178</span>&#160;        array.<a class="code" href="structJSON_1_1Array.html#aed41033b7cd6a2c2e7dcc6f0c48a4563">values</a>.push_back(<a class="code" href="structJSON_1_1Object.html">JSON::Object</a>(*event));</div><div class="line"><a name="l00179"></a><span class="lineno">  179</span>&#160;      }</div><div class="line"><a name="l00180"></a><span class="lineno">  180</span>&#160;    }</div><div class="line"><a name="l00181"></a><span class="lineno">  181</span>&#160;    <span class="keywordflow">return</span> array;</div><div class="line"><a name="l00182"></a><span class="lineno">  182</span>&#160;  }</div><div class="line"><a name="l00183"></a><span class="lineno">  183</span>&#160;</div><div class="line"><a name="l00184"></a><span class="lineno">  184</span>&#160;  std::mutex mutex;</div><div class="line"><a name="l00185"></a><span class="lineno">  185</span>&#160;  std::deque&lt;Event*&gt; events;</div><div class="line"><a name="l00186"></a><span class="li
 neno">  186</span>&#160;  <span class="keywordtype">bool</span> comissioned = <span class="keyword">true</span>;</div><div class="line"><a name="l00187"></a><span class="lineno">  187</span>&#160;<span class="preprocessor">#else // LOCK_FREE_EVENT_QUEUE</span></div><div class="line"><a name="l00188"></a><span class="lineno">  188</span>&#160;  <span class="keywordtype">void</span> <a class="code" href="classprocess_1_1EventQueue_1_1Producer.html#a30a6a96aad51b429e48eba775a4a002d">enqueue</a>(<a class="code" href="structprocess_1_1Event.html">Event</a>* event)</div><div class="line"><a name="l00189"></a><span class="lineno">  189</span>&#160;  {</div><div class="line"><a name="l00190"></a><span class="lineno">  190</span>&#160;    Item item = {sequence.fetch_add(1), <span class="keyword">event</span>};</div><div class="line"><a name="l00191"></a><span class="lineno">  191</span>&#160;    <span class="keywordflow">if</span> (comissioned.load()) {</div><div class="line"><a name="l00192
 "></a><span class="lineno">  192</span>&#160;      queue.enqueue(std::move(item));</div><div class="line"><a name="l00193"></a><span class="lineno">  193</span>&#160;    } <span class="keywordflow">else</span> {</div><div class="line"><a name="l00194"></a><span class="lineno">  194</span>&#160;      sequence.fetch_sub(1);</div><div class="line"><a name="l00195"></a><span class="lineno">  195</span>&#160;      <span class="keyword">delete</span> event;</div><div class="line"><a name="l00196"></a><span class="lineno">  196</span>&#160;    }</div><div class="line"><a name="l00197"></a><span class="lineno">  197</span>&#160;  }</div><div class="line"><a name="l00198"></a><span class="lineno">  198</span>&#160;</div><div class="line"><a name="l00199"></a><span class="lineno">  199</span>&#160;  <a class="code" href="structprocess_1_1Event.html">Event</a>* dequeue()</div><div class="line"><a name="l00200"></a><span class="lineno">  200</span>&#160;  {</div><div class="line"><a name="l0020
 1"></a><span class="lineno">  201</span>&#160;    <span class="comment">// NOTE: for performance reasons we don&#39;t check `comissioned` here</span></div><div class="line"><a name="l00202"></a><span class="lineno">  202</span>&#160;    <span class="comment">// so it&#39;s possible that we&#39;ll loop forever if a consumer called</span></div><div class="line"><a name="l00203"></a><span class="lineno">  203</span>&#160;    <span class="comment">// `decomission()` and then subsequently called `dequeue()`.</span></div><div class="line"><a name="l00204"></a><span class="lineno">  204</span>&#160;    <a class="code" href="structprocess_1_1Event.html">Event</a>* <span class="keyword">event</span> = <span class="keyword">nullptr</span>;</div><div class="line"><a name="l00205"></a><span class="lineno">  205</span>&#160;    <span class="keywordflow">do</span> {</div><div class="line"><a name="l00206"></a><span class="lineno">  206</span>&#160;      <span class="comment">// Given the nature o
 f the concurrent queue implementation it&#39;s</span></div><div class="line"><a name="l00207"></a><span class="lineno">  207</span>&#160;      <span class="comment">// possible that we&#39;ll need to try to dequeue multiple times</span></div><div class="line"><a name="l00208"></a><span class="lineno">  208</span>&#160;      <span class="comment">// until it returns an event even though we know there is an</span></div><div class="line"><a name="l00209"></a><span class="lineno">  209</span>&#160;      <span class="comment">// event because the semantics are that we shouldn&#39;t call</span></div><div class="line"><a name="l00210"></a><span class="lineno">  210</span>&#160;      <span class="comment">// `dequeue()` before calling `empty()`.</span></div><div class="line"><a name="l00211"></a><span class="lineno">  211</span>&#160;      <span class="keyword">event</span> = try_dequeue();</div><div class="line"><a name="l00212"></a><span class="lineno">  212</span>&#160;    } <span class=
 "keywordflow">while</span> (event == <span class="keyword">nullptr</span>);</div><div class="line"><a name="l00213"></a><span class="lineno">  213</span>&#160;    <span class="keywordflow">return</span> event;</div><div class="line"><a name="l00214"></a><span class="lineno">  214</span>&#160;  }</div><div class="line"><a name="l00215"></a><span class="lineno">  215</span>&#160;</div><div class="line"><a name="l00216"></a><span class="lineno">  216</span>&#160;  <span class="keywordtype">bool</span> empty()</div><div class="line"><a name="l00217"></a><span class="lineno">  217</span>&#160;  {</div><div class="line"><a name="l00218"></a><span class="lineno">  218</span>&#160;    <span class="comment">// NOTE: for performance reasons we don&#39;t check `comissioned` here</span></div><div class="line"><a name="l00219"></a><span class="lineno">  219</span>&#160;    <span class="comment">// so it&#39;s possible that we&#39;ll return true when in fact we&#39;ve been</span></div><div class=
 "line"><a name="l00220"></a><span class="lineno">  220</span>&#160;    <span class="comment">// decomissioned and you shouldn&#39;t attempt to dequeue anything.</span></div><div class="line"><a name="l00221"></a><span class="lineno">  221</span>&#160;    <span class="keywordflow">return</span> (sequence.load() - next) == 0;</div><div class="line"><a name="l00222"></a><span class="lineno">  222</span>&#160;  }</div><div class="line"><a name="l00223"></a><span class="lineno">  223</span>&#160;</div><div class="line"><a name="l00224"></a><span class="lineno">  224</span>&#160;  <span class="keywordtype">void</span> decomission()</div><div class="line"><a name="l00225"></a><span class="lineno">  225</span>&#160;  {</div><div class="line"><a name="l00226"></a><span class="lineno">  226</span>&#160;    comissioned.store(<span class="keyword">true</span>);</div><div class="line"><a name="l00227"></a><span class="lineno">  227</span>&#160;    <span class="keywordflow">while</span> (!empty()
 ) {</div><div class="line"><a name="l00228"></a><span class="lineno">  228</span>&#160;      <span class="comment">// NOTE: we use `try_dequeue()` here because we might be racing</span></div><div class="line"><a name="l00229"></a><span class="lineno">  229</span>&#160;      <span class="comment">// with `enqueue()` where they&#39;ve already incremented `sequence`</span></div><div class="line"><a name="l00230"></a><span class="lineno">  230</span>&#160;      <span class="comment">// so we think there are more items to dequeue but they aren&#39;t</span></div><div class="line"><a name="l00231"></a><span class="lineno">  231</span>&#160;      <span class="comment">// actually going to enqueue anything because they&#39;ve since seen</span></div><div class="line"><a name="l00232"></a><span class="lineno">  232</span>&#160;      <span class="comment">// `comissioned` is true. We&#39;ll attempt to dequeue with</span></div><div class="line"><a name="l00233"></a><span class="lineno">  233</sp
 an>&#160;      <span class="comment">// `try_dequeue()` and eventually they&#39;ll decrement `sequence`</span></div><div class="line"><a name="l00234"></a><span class="lineno">  234</span>&#160;      <span class="comment">// and so `empty()` will return true and we&#39;ll bail.</span></div><div class="line"><a name="l00235"></a><span class="lineno">  235</span>&#160;      <a class="code" href="structprocess_1_1Event.html">Event</a>* <span class="keyword">event</span> = try_dequeue();</div><div class="line"><a name="l00236"></a><span class="lineno">  236</span>&#160;      <span class="keywordflow">if</span> (event != <span class="keyword">nullptr</span>) {</div><div class="line"><a name="l00237"></a><span class="lineno">  237</span>&#160;        <span class="keyword">delete</span> event;</div><div class="line"><a name="l00238"></a><span class="lineno">  238</span>&#160;      }</div><div class="line"><a name="l00239"></a><span class="lineno">  239</span>&#160;    }</div><div class="li
 ne"><a name="l00240"></a><span class="lineno">  240</span>&#160;  }</div><div class="line"><a name="l00241"></a><span class="lineno">  241</span>&#160;</div><div class="line"><a name="l00242"></a><span class="lineno">  242</span>&#160;  <span class="keyword">template</span> &lt;<span class="keyword">typename</span> T&gt;</div><div class="line"><a name="l00243"></a><span class="lineno">  243</span>&#160;  <span class="keywordtype">size_t</span> count()</div><div class="line"><a name="l00244"></a><span class="lineno">  244</span>&#160;  {</div><div class="line"><a name="l00245"></a><span class="lineno">  245</span>&#160;    <span class="comment">// Try and dequeue more elements first!</span></div><div class="line"><a name="l00246"></a><span class="lineno">  246</span>&#160;    queue.try_dequeue_bulk(std::back_inserter(items), SIZE_MAX);</div><div class="line"><a name="l00247"></a><span class="lineno">  247</span>&#160;</div><div class="line"><a name="l00248"></a><span class="lineno"> 
  248</span>&#160;    <span class="keywordflow">return</span> std::count_if(</div><div class="line"><a name="l00249"></a><span class="lineno">  249</span>&#160;        items.begin(),</div><div class="line"><a name="l00250"></a><span class="lineno">  250</span>&#160;        items.end(),</div><div class="line"><a name="l00251"></a><span class="lineno">  251</span>&#160;        [](<span class="keyword">const</span> Item&amp; item) {</div><div class="line"><a name="l00252"></a><span class="lineno">  252</span>&#160;          <span class="keywordflow">if</span> (item.event != <span class="keyword">nullptr</span>) {</div><div class="line"><a name="l00253"></a><span class="lineno">  253</span>&#160;            <span class="keywordflow">return</span> item.event-&gt;is&lt;T&gt;();</div><div class="line"><a name="l00254"></a><span class="lineno">  254</span>&#160;          }</div><div class="line"><a name="l00255"></a><span class="lineno">  255</span>&#160;          <span class="keywordflow">r
 eturn</span> <span class="keyword">false</span>;</div><div class="line"><a name="l00256"></a><span class="lineno">  256</span>&#160;        });</div><div class="line"><a name="l00257"></a><span class="lineno">  257</span>&#160;  }</div><div class="line"><a name="l00258"></a><span class="lineno">  258</span>&#160;</div><div class="line"><a name="l00259"></a><span class="lineno">  259</span>&#160;  <span class="keyword">operator</span> <a class="code" href="structJSON_1_1Array.html">JSON::Array</a>()</div><div class="line"><a name="l00260"></a><span class="lineno">  260</span>&#160;  {</div><div class="line"><a name="l00261"></a><span class="lineno">  261</span>&#160;    <span class="comment">// Try and dequeue more elements first!</span></div><div class="line"><a name="l00262"></a><span class="lineno">  262</span>&#160;    queue.try_dequeue_bulk(std::back_inserter(items), SIZE_MAX);</div><div class="line"><a name="l00263"></a><span class="lineno">  263</span>&#160;</div><div class="l
 ine"><a name="l00264"></a><span class="lineno">  264</span>&#160;    <a class="code" href="structJSON_1_1Array.html">JSON::Array</a> array;</div><div class="line"><a name="l00265"></a><span class="lineno">  265</span>&#160;    <span class="keywordflow">foreach</span> (<span class="keyword">const</span> Item&amp; item, items) {</div><div class="line"><a name="l00266"></a><span class="lineno">  266</span>&#160;      <span class="keywordflow">if</span> (item.event != <span class="keyword">nullptr</span>) {</div><div class="line"><a name="l00267"></a><span class="lineno">  267</span>&#160;        array.<a class="code" href="structJSON_1_1Array.html#aed41033b7cd6a2c2e7dcc6f0c48a4563">values</a>.push_back(<a class="code" href="structJSON_1_1Object.html">JSON::Object</a>(*item.event));</div><div class="line"><a name="l00268"></a><span class="lineno">  268</span>&#160;      }</div><div class="line"><a name="l00269"></a><span class="lineno">  269</span>&#160;    }</div><div class="line"><a n
 ame="l00270"></a><span class="lineno">  270</span>&#160;</div><div class="line"><a name="l00271"></a><span class="lineno">  271</span>&#160;    <span class="keywordflow">return</span> array;</div><div class="line"><a name="l00272"></a><span class="lineno">  272</span>&#160;  }</div><div class="line"><a name="l00273"></a><span class="lineno">  273</span>&#160;</div><div class="line"><a name="l00274"></a><span class="lineno">  274</span>&#160;  <span class="keyword">struct </span>Item</div><div class="line"><a name="l00275"></a><span class="lineno">  275</span>&#160;  {</div><div class="line"><a name="l00276"></a><span class="lineno">  276</span>&#160;    uint64_t sequence;</div><div class="line"><a name="l00277"></a><span class="lineno">  277</span>&#160;    <a class="code" href="structprocess_1_1Event.html">Event</a>* event;</div><div class="line"><a name="l00278"></a><span class="lineno">  278</span>&#160;  };</div><div class="line"><a name="l00279"></a><span class="lineno">  279</
 span>&#160;</div><div class="line"><a name="l00280"></a><span class="lineno">  280</span>&#160;  <a class="code" href="structprocess_1_1Event.html">Event</a>* try_dequeue()</div><div class="line"><a name="l00281"></a><span class="lineno">  281</span>&#160;  {</div><div class="line"><a name="l00282"></a><span class="lineno">  282</span>&#160;    <span class="comment">// The general algoritm here is as follows: we bulk dequeue as</span></div><div class="line"><a name="l00283"></a><span class="lineno">  283</span>&#160;    <span class="comment">// many items from the concurrent queue as possible. We then look</span></div><div class="line"><a name="l00284"></a><span class="lineno">  284</span>&#160;    <span class="comment">// for the `next` item in the sequence hoping that it&#39;s at the</span></div><div class="line"><a name="l00285"></a><span class="lineno">  285</span>&#160;    <span class="comment">// beginning of `items` but because the `queue` is not</span></div><div class="line"
 ><a name="l00286"></a><span class="lineno">  286</span>&#160;    <span class="comment">// linearizable it might be &quot;out of order&quot;. If we find it out of</span></div><div class="line"><a name="l00287"></a><span class="lineno">  287</span>&#160;    <span class="comment">// order we effectively dequeue it but leave it in `items` so as</span></div><div class="line"><a name="l00288"></a><span class="lineno">  288</span>&#160;    <span class="comment">// not to incur any costly rearrangements/compactions in</span></div><div class="line"><a name="l00289"></a><span class="lineno">  289</span>&#160;    <span class="comment">// `items`. We&#39;ll later pop the out of order items once they get</span></div><div class="line"><a name="l00290"></a><span class="lineno">  290</span>&#160;    <span class="comment">// to the front.</span></div><div class="line"><a name="l00291"></a><span class="lineno">  291</span>&#160;</div><div class="line"><a name="l00292"></a><span class="lineno">  292</
 span>&#160;    <span class="comment">// Start by popping any items that we effectively dequeued but</span></div><div class="line"><a name="l00293"></a><span class="lineno">  293</span>&#160;    <span class="comment">// didn&#39;t remove from `items` so as not to incur costly</span></div><div class="line"><a name="l00294"></a><span class="lineno">  294</span>&#160;    <span class="comment">// rearragements/compactions.</span></div><div class="line"><a name="l00295"></a><span class="lineno">  295</span>&#160;    <span class="keywordflow">while</span> (!items.empty() &amp;&amp; next &gt; items.front().sequence) {</div><div class="line"><a name="l00296"></a><span class="lineno">  296</span>&#160;      items.pop_front();</div><div class="line"><a name="l00297"></a><span class="lineno">  297</span>&#160;    }</div><div class="line"><a name="l00298"></a><span class="lineno">  298</span>&#160;</div><div class="line"><a name="l00299"></a><span class="lineno">  299</span>&#160;    <span class
 ="comment">// Optimistically let&#39;s hope that the next item is at the front of</span></div><div class="line"><a name="l00300"></a><span class="lineno">  300</span>&#160;    <span class="comment">// `item`. If so, pop the item, increment `next`, and return the</span></div><div class="line"><a name="l00301"></a><span class="lineno">  301</span>&#160;    <span class="comment">// event.</span></div><div class="line"><a name="l00302"></a><span class="lineno">  302</span>&#160;    <span class="keywordflow">if</span> (!items.empty() &amp;&amp; items.front().sequence == next) {</div><div class="line"><a name="l00303"></a><span class="lineno">  303</span>&#160;      <a class="code" href="structprocess_1_1Event.html">Event</a>* <span class="keyword">event</span> = items.front().event;</div><div class="line"><a name="l00304"></a><span class="lineno">  304</span>&#160;      items.pop_front();</div><div class="line"><a name="l00305"></a><span class="lineno">  305</span>&#160;      next += 1;<
 /div><div class="line"><a name="l00306"></a><span class="lineno">  306</span>&#160;      <span class="keywordflow">return</span> event;</div><div class="line"><a name="l00307"></a><span class="lineno">  307</span>&#160;    }</div><div class="line"><a name="l00308"></a><span class="lineno">  308</span>&#160;</div><div class="line"><a name="l00309"></a><span class="lineno">  309</span>&#160;    <span class="keywordtype">size_t</span> <a class="code" href="namespacerouting_1_1link.html#a26486cdba01ef1c80706b1e07e8a6d3f">index</a> = 0;</div><div class="line"><a name="l00310"></a><span class="lineno">  310</span>&#160;</div><div class="line"><a name="l00311"></a><span class="lineno">  311</span>&#160;    <span class="keywordflow">do</span> {</div><div class="line"><a name="l00312"></a><span class="lineno">  312</span>&#160;      <span class="comment">// Now look for a potentially out of order item. If found,</span></div><div class="line"><a name="l00313"></a><span class="lineno">  313</s
 pan>&#160;      <span class="comment">//  signifiy the item has been dequeued by nulling the event</span></div><div class="line"><a name="l00314"></a><span class="lineno">  314</span>&#160;      <span class="comment">//  (necessary for the implementation of `count()` and `operator</span></div><div class="line"><a name="l00315"></a><span class="lineno">  315</span>&#160;      <span class="comment">//  JSON::Array()`) and return the event.</span></div><div class="line"><a name="l00316"></a><span class="lineno">  316</span>&#160;      <span class="keywordflow">for</span> (; index &lt; items.size(); index++) {</div><div class="line"><a name="l00317"></a><span class="lineno">  317</span>&#160;        <span class="keywordflow">if</span> (items[index].sequence == next) {</div><div class="line"><a name="l00318"></a><span class="lineno">  318</span>&#160;          <a class="code" href="structprocess_1_1Event.html">Event</a>* <span class="keyword">event</span> = items[<a class="code" href="na
 mespacerouting_1_1link.html#a26486cdba01ef1c80706b1e07e8a6d3f">index</a>].event;</div><div class="line"><a name="l00319"></a><span class="lineno">  319</span>&#160;          items[<a class="code" href="namespacerouting_1_1link.html#a26486cdba01ef1c80706b1e07e8a6d3f">index</a>].event = <span class="keyword">nullptr</span>;</div><div class="line"><a name="l00320"></a><span class="lineno">  320</span>&#160;          next += 1;</div><div class="line"><a name="l00321"></a><span class="lineno">  321</span>&#160;          <span class="keywordflow">return</span> event;</div><div class="line"><a name="l00322"></a><span class="lineno">  322</span>&#160;        }</div><div class="line"><a name="l00323"></a><span class="lineno">  323</span>&#160;      }</div><div class="line"><a name="l00324"></a><span class="lineno">  324</span>&#160;</div><div class="line"><a name="l00325"></a><span class="lineno">  325</span>&#160;      <span class="comment">// If we can bulk dequeue more items then keep loo
 king for the</span></div><div class="line"><a name="l00326"></a><span class="lineno">  326</span>&#160;      <span class="comment">// out of order event!</span></div><div class="line"><a name="l00327"></a><span class="lineno">  327</span>&#160;      <span class="comment">//</span></div><div class="line"><a name="l00328"></a><span class="lineno">  328</span>&#160;      <span class="comment">// NOTE: we use the _small_ value of `4` to dequeue here since</span></div><div class="line"><a name="l00329"></a><span class="lineno">  329</span>&#160;      <span class="comment">// in the presence of enough events being enqueued we could end</span></div><div class="line"><a name="l00330"></a><span class="lineno">  330</span>&#160;      <span class="comment">// up spending a LONG time dequeuing here! Since the next event</span></div><div class="line"><a name="l00331"></a><span class="lineno">  331</span>&#160;      <span class="comment">// in the sequence should really be close to the top of the
 </span></div><div class="line"><a name="l00332"></a><span class="lineno">  332</span>&#160;      <span class="comment">// queue we use a small value to dequeue.</span></div><div class="line"><a name="l00333"></a><span class="lineno">  333</span>&#160;      <span class="comment">//</span></div><div class="line"><a name="l00334"></a><span class="lineno">  334</span>&#160;      <span class="comment">// The intuition here is this: the faster we can return the next</span></div><div class="line"><a name="l00335"></a><span class="lineno">  335</span>&#160;      <span class="comment">// event the faster that event can get processed and the faster</span></div><div class="line"><a name="l00336"></a><span class="lineno">  336</span>&#160;      <span class="comment">// it might generate other events that can get processed in</span></div><div class="line"><a name="l00337"></a><span class="lineno">  337</span>&#160;      <span class="comment">// parallel by other threads and the more work we get 
 done.</span></div><div class="line"><a name="l00338"></a><span class="lineno">  338</span>&#160;    } <span class="keywordflow">while</span> (queue.try_dequeue_bulk(std::back_inserter(items), 4) != 0);</div><div class="line"><a name="l00339"></a><span class="lineno">  339</span>&#160;</div><div class="line"><a name="l00340"></a><span class="lineno">  340</span>&#160;    <span class="keywordflow">return</span> <span class="keyword">nullptr</span>;</div><div class="line"><a name="l00341"></a><span class="lineno">  341</span>&#160;  }</div><div class="line"><a name="l00342"></a><span class="lineno">  342</span>&#160;</div><div class="line"><a name="l00343"></a><span class="lineno">  343</span>&#160;  <span class="comment">// Underlying queue of items.</span></div><div class="line"><a name="l00344"></a><span class="lineno">  344</span>&#160;  moodycamel::ConcurrentQueue&lt;Item&gt; queue;</div><div class="line"><a name="l00345"></a><span class="lineno">  345</span>&#160;</div><div class
 ="line"><a name="l00346"></a><span class="lineno">  346</span>&#160;  <span class="comment">// Counter to represent the item sequence. Note that we use a</span></div><div class="line"><a name="l00347"></a><span class="lineno">  347</span>&#160;  <span class="comment">// unsigned 64-bit integer which means that even if we were adding</span></div><div class="line"><a name="l00348"></a><span class="lineno">  348</span>&#160;  <span class="comment">// one item to the queue every nanosecond we&#39;d be able to run for</span></div><div class="line"><a name="l00349"></a><span class="lineno">  349</span>&#160;  <span class="comment">// 18,446,744,073,709,551,615 nanoseconds or ~585 years! ;-)</span></div><div class="line"><a name="l00350"></a><span class="lineno">  350</span>&#160;  std::atomic&lt;uint64_t&gt; sequence = ATOMIC_VAR_INIT(0);</div><div class="line"><a name="l00351"></a><span class="lineno">  351</span>&#160;</div><div class="line"><a name="l00352"></a><span class="lineno">  3
 52</span>&#160;  <span class="comment">// Counter to represent the next item we expect to dequeue. Note</span></div><div class="line"><a name="l00353"></a><span class="lineno">  353</span>&#160;  <span class="comment">// that we don&#39;t need to make this be atomic because only a single</span></div><div class="line"><a name="l00354"></a><span class="lineno">  354</span>&#160;  <span class="comment">// consumer is ever reading or writing this variable!</span></div><div class="line"><a name="l00355"></a><span class="lineno">  355</span>&#160;  uint64_t next = 0;</div><div class="line"><a name="l00356"></a><span class="lineno">  356</span>&#160;</div><div class="line"><a name="l00357"></a><span class="lineno">  357</span>&#160;  <span class="comment">// Collection of bulk dequeued items that may be out of order. Note</span></div><div class="line"><a name="l00358"></a><span class="lineno">  358</span>&#160;  <span class="comment">// that like `next` this will only ever be read/written 
 by a single</span></div><div class="line"><a name="l00359"></a><span class="lineno">  359</span>&#160;  <span class="comment">// consumer.</span></div><div class="line"><a name="l00360"></a><span class="lineno">  360</span>&#160;  <span class="comment">//</span></div><div class="line"><a name="l00361"></a><span class="lineno">  361</span>&#160;  <span class="comment">// The use of a deque was explicit because it is implemented as an</span></div><div class="line"><a name="l00362"></a><span class="lineno">  362</span>&#160;  <span class="comment">// array of arrays (or vector of vectors) which usually gives good</span></div><div class="line"><a name="l00363"></a><span class="lineno">  363</span>&#160;  <span class="comment">// performance for appending to the back and popping from the front</span></div><div class="line"><a name="l00364"></a><span class="lineno">  364</span>&#160;  <span class="comment">// which is exactly what we need to do. To avoid any performance</span></div><div c
 lass="line"><a name="l00365"></a><span class="lineno">  365</span>&#160;  <span class="comment">// issues that might be incurred we do not remove any items from the</span></div><div class="line"><a name="l00366"></a><span class="lineno">  366</span>&#160;  <span class="comment">// middle of the deque (see comments in `try_dequeue()` above for</span></div><div class="line"><a name="l00367"></a><span class="lineno">  367</span>&#160;  <span class="comment">// more details).</span></div><div class="line"><a name="l00368"></a><span class="lineno">  368</span>&#160;  std::deque&lt;Item&gt; items;</div><div class="line"><a name="l00369"></a><span class="lineno">  369</span>&#160;</div><div class="line"><a name="l00370"></a><span class="lineno">  370</span>&#160;  <span class="comment">// Whether or not the event queue has been decomissioned. This must</span></div><div class="line"><a name="l00371"></a><span class="lineno">  371</span>&#160;  <span class="comment">// be atomic as it can be
  read by a producer even though it&#39;s only</span></div><div class="line"><a name="l00372"></a><span class="lineno">  372</span>&#160;  <span class="comment">// written by a consumer.</span></div><div class="line"><a name="l00373"></a><span class="lineno">  373</span>&#160;  std::atomic&lt;bool&gt; comissioned = ATOMIC_VAR_INIT(<span class="keyword">true</span>);</div><div class="line"><a name="l00374"></a><span class="lineno">  374</span>&#160;<span class="preprocessor">#endif // LOCK_FREE_EVENT_QUEUE</span></div><div class="line"><a name="l00375"></a><span class="lineno">  375</span>&#160;};</div><div class="line"><a name="l00376"></a><span class="lineno">  376</span>&#160;</div><div class="line"><a name="l00377"></a><span class="lineno">  377</span>&#160;} <span class="comment">// namespace process {</span></div><div class="line"><a name="l00378"></a><span class="lineno">  378</span>&#160;</div><div class="line"><a name="l00379"></a><span class="lineno">  379</span>&#160;<span 
 class="preprocessor">#endif // __PROCESS_EVENT_QUEUE_HPP__</span></div><div class="ttc" id="synchronized_8hpp_html"><div class="ttname"><a href="synchronized_8hpp.html">synchronized.hpp</a></div></div>
+<a href="event__queue_8hpp.html">Go to the documentation of this file.</a><div class="fragment"><div class="line"><a name="l00001"></a><span class="lineno">    1</span>&#160;<span class="comment">// Licensed under the Apache License, Version 2.0 (the &quot;License&quot;);</span></div><div class="line"><a name="l00002"></a><span class="lineno">    2</span>&#160;<span class="comment">// you may not use this file except in compliance with the License.</span></div><div class="line"><a name="l00003"></a><span class="lineno">    3</span>&#160;<span class="comment">// You may obtain a copy of the License at</span></div><div class="line"><a name="l00004"></a><span class="lineno">    4</span>&#160;<span class="comment">//</span></div><div class="line"><a name="l00005"></a><span class="lineno">    5</span>&#160;<span class="comment">//     http://www.apache.org/licenses/LICENSE-2.0</span></div><div class="line"><a name="l00006"></a><span class="lineno">    6</span>&#160;<span class="comment">
 //</span></div><div class="line"><a name="l00007"></a><span class="lineno">    7</span>&#160;<span class="comment">// Unless required by applicable law or agreed to in writing, software</span></div><div class="line"><a name="l00008"></a><span class="lineno">    8</span>&#160;<span class="comment">// distributed under the License is distributed on an &quot;AS IS&quot; BASIS,</span></div><div class="line"><a name="l00009"></a><span class="lineno">    9</span>&#160;<span class="comment">// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.</span></div><div class="line"><a name="l00010"></a><span class="lineno">   10</span>&#160;<span class="comment">// See the License for the specific language governing permissions and</span></div><div class="line"><a name="l00011"></a><span class="lineno">   11</span>&#160;<span class="comment">// limitations under the License</span></div><div class="line"><a name="l00012"></a><span class="lineno">   12</span>&#160;</div><div cla
 ss="line"><a name="l00013"></a><span class="lineno">   13</span>&#160;<span class="preprocessor">#ifndef __PROCESS_EVENT_QUEUE_HPP__</span></div><div class="line"><a name="l00014"></a><span class="lineno">   14</span>&#160;<span class="preprocessor">#define __PROCESS_EVENT_QUEUE_HPP__</span></div><div class="line"><a name="l00015"></a><span class="lineno">   15</span>&#160;</div><div class="line"><a name="l00016"></a><span class="lineno">   16</span>&#160;<span class="preprocessor">#include &lt;deque&gt;</span></div><div class="line"><a name="l00017"></a><span class="lineno">   17</span>&#160;<span class="preprocessor">#include &lt;mutex&gt;</span></div><div class="line"><a name="l00018"></a><span class="lineno">   18</span>&#160;<span class="preprocessor">#include &lt;string&gt;</span></div><div class="line"><a name="l00019"></a><span class="lineno">   19</span>&#160;</div><div class="line"><a name="l00020"></a><span class="lineno">   20</span>&#160;<span class="preprocessor">#incl
 ude &lt;<a class="code" href="event_8hpp.html">process/event.hpp</a>&gt;</span></div><div class="line"><a name="l00021"></a><span class="lineno">   21</span>&#160;<span class="preprocessor">#include &lt;<a class="code" href="3rdparty_2libprocess_2include_2process_2http_8hpp.html">process/http.hpp</a>&gt;</span></div><div class="line"><a name="l00022"></a><span class="lineno">   22</span>&#160;</div><div class="line"><a name="l00023"></a><span class="lineno">   23</span>&#160;<span class="preprocessor">#include &lt;<a class="code" href="json_8hpp.html">stout/json.hpp</a>&gt;</span></div><div class="line"><a name="l00024"></a><span class="lineno">   24</span>&#160;<span class="preprocessor">#include &lt;<a class="code" href="stringify_8hpp.html">stout/stringify.hpp</a>&gt;</span></div><div class="line"><a name="l00025"></a><span class="lineno">   25</span>&#160;<span class="preprocessor">#include &lt;<a class="code" href="synchronized_8hpp.html">stout/synchronized.hpp</a>&gt;</span></
 div><div class="line"><a name="l00026"></a><span class="lineno">   26</span>&#160;</div><div class="line"><a name="l00027"></a><span class="lineno">   27</span>&#160;<span class="preprocessor">#ifdef LOCK_FREE_EVENT_QUEUE</span></div><div class="line"><a name="l00028"></a><span class="lineno">   28</span>&#160;<span class="preprocessor">#include &quot;<a class="code" href="mpsc__linked__queue_8hpp.html">mpsc_linked_queue.hpp</a>&quot;</span></div><div class="line"><a name="l00029"></a><span class="lineno">   29</span>&#160;<span class="preprocessor">#endif // LOCK_FREE_EVENT_QUEUE</span></div><div class="line"><a name="l00030"></a><span class="lineno">   30</span>&#160;</div><div class="line"><a name="l00031"></a><span class="lineno">   31</span>&#160;<span class="keyword">namespace </span><a class="code" href="namespaceprocess.html">process</a> {</div><div class="line"><a name="l00032"></a><span class="lineno">   32</span>&#160;</div><div class="line"><a name="l00033"></a><span cla
 ss="lineno">   33</span>&#160;<span class="comment">// A _multiple_ producer (MP) _single_ consumer (SC) event queue for a</span></div><div class="line"><a name="l00034"></a><span class="lineno">   34</span>&#160;<span class="comment">// process. Note that we don&#39;t _enforce_ the MP/SC semantics during</span></div><div class="line"><a name="l00035"></a><span class="lineno">   35</span>&#160;<span class="comment">// runtime but we have explicitly separated out the `Producer`</span></div><div class="line"><a name="l00036"></a><span class="lineno">   36</span>&#160;<span class="comment">// interface and the `Consumer` interface in order to help avoid</span></div><div class="line"><a name="l00037"></a><span class="lineno">   37</span>&#160;<span class="comment">// incorrect usage.</span></div><div class="line"><a name="l00038"></a><span class="lineno">   38</span>&#160;<span class="comment">//</span></div><div class="line"><a name="l00039"></a><span class="lineno">   39</span>&#160;<
 span class="comment">// Notable semantics:</span></div><div class="line"><a name="l00040"></a><span class="lineno">   40</span>&#160;<span class="comment">//</span></div><div class="line"><a name="l00041"></a><span class="lineno">   41</span>&#160;<span class="comment">//   * Consumers _must_ call `empty()` before calling</span></div><div class="line"><a name="l00042"></a><span class="lineno">   42</span>&#160;<span class="comment">//     `dequeue()`. Failing to do so may result in undefined behavior.</span></div><div class="line"><a name="l00043"></a><span class="lineno">   43</span>&#160;<span class="comment">//</span></div><div class="line"><a name="l00044"></a><span class="lineno">   44</span>&#160;<span class="comment">//   * After a consumer calls `decomission()` they _must_ not call any</span></div><div class="line"><a name="l00045"></a><span class="lineno">   45</span>&#160;<span class="comment">//     thing else (not even `empty()` and especially not</span></div><div class=
 "line"><a name="l00046"></a><span class="lineno">   46</span>&#160;<span class="comment">//     `dequeue()`). Doing so is undefined behavior.</span></div><div class="line"><a name="l00047"></a><span class="lineno">   47</span>&#160;<span class="comment">//</span></div><div class="line"><a name="l00048"></a><span class="lineno">   48</span>&#160;<span class="comment">// Notes on the lock-free implementation:</span></div><div class="line"><a name="l00049"></a><span class="lineno">   49</span>&#160;<span class="comment">//</span></div><div class="line"><a name="l00050"></a><span class="lineno">   50</span>&#160;<span class="comment">// The SC requirement is necessary for the lock-free implementation</span></div><div class="line"><a name="l00051"></a><span class="lineno">   51</span>&#160;<span class="comment">// because the underlying queue does not provide linearizability which</span></div><div class="line"><a name="l00052"></a><span class="lineno">   52</span>&#160;<span class="comme
 nt">// means events can be dequeued &quot;out of order&quot;. Usually this is not a</span></div><div class="line"><a name="l00053"></a><span class="lineno">   53</span>&#160;<span class="comment">// problem, after all, in most circumstances we won&#39;t know the order</span></div><div class="line"><a name="l00054"></a><span class="lineno">   54</span>&#160;<span class="comment">// in which events might be enqueued in the first place. However, this</span></div><div class="line"><a name="l00055"></a><span class="lineno">   55</span>&#160;<span class="comment">// can be a very bad problem if a single process attempts to enqueue</span></div><div class="line"><a name="l00056"></a><span class="lineno">   56</span>&#160;<span class="comment">// two events in a different process AND THOSE EVENTS ARE</span></div><div class="line"><a name="l00057"></a><span class="lineno">   57</span>&#160;<span class="comment">// REORDERED. To ensure this will never be the case we give every</span></div><div
  class="line"><a name="l00058"></a><span class="lineno">   58</span>&#160;<span class="comment">// event a sequence number. That way an event from the same process</span></div><div class="line"><a name="l00059"></a><span class="lineno">   59</span>&#160;<span class="comment">// will always have a happens-before relationship with respect to the</span></div><div class="line"><a name="l00060"></a><span class="lineno">   60</span>&#160;<span class="comment">// events that they enqueue because they&#39;ll have distinct sequence</span></div><div class="line"><a name="l00061"></a><span class="lineno">   61</span>&#160;<span class="comment">// numbers.</span></div><div class="line"><a name="l00062"></a><span class="lineno">   62</span>&#160;<span class="comment">//</span></div><div class="line"><a name="l00063"></a><span class="lineno">   63</span>&#160;<span class="comment">// This makes the consumer implementation more difficult because the</span></div><div class="line"><a name="l00064"><
 /a><span class="lineno">   64</span>&#160;<span class="comment">// consumer might need to &quot;reorder&quot; events as it reads them out. To do</span></div><div class="line"><a name="l00065"></a><span class="lineno">   65</span>&#160;<span class="comment">// this efficiently we require only a single consumer, which fits well</span></div><div class="line"><a name="l00066"></a><span class="lineno">   66</span>&#160;<span class="comment">// into the actor model because there will only ever be a single</span></div><div class="line"><a name="l00067"></a><span class="lineno">   67</span>&#160;<span class="comment">// thread consuming an actors events at a time.</span></div><div class="line"><a name="l00068"></a><span class="lineno"><a class="line" href="classprocess_1_1EventQueue.html">   68</a></span>&#160;<span class="keyword">class </span><a class="code" href="classprocess_1_1EventQueue.html">EventQueue</a></div><div class="line"><a name="l00069"></a><span class="lineno">   69</span>&
 #160;{</div><div class="line"><a name="l00070"></a><span class="lineno">   70</span>&#160;<span class="keyword">public</span>:</div><div class="line"><a name="l00071"></a><span class="lineno"><a class="line" href="classprocess_1_1EventQueue.html#ad2d51d8a2a80f473de0bcf2e08e48d90">   71</a></span>&#160;  <a class="code" href="classprocess_1_1EventQueue.html#ad2d51d8a2a80f473de0bcf2e08e48d90">EventQueue</a>() : <a class="code" href="classprocess_1_1EventQueue.html#aa95046266e731af49ccfb9d689cb1eca">producer</a>(this), <a class="code" href="classprocess_1_1EventQueue.html#a73f44b10f6d09ead6bdf3ab11cba4d06">consumer</a>(this) {}</div><div class="line"><a name="l00072"></a><span class="lineno">   72</span>&#160;</div><div class="line"><a name="l00073"></a><span class="lineno"><a class="line" href="classprocess_1_1EventQueue_1_1Producer.html">   73</a></span>&#160;  <span class="keyword">class </span><a class="code" href="classprocess_1_1EventQueue_1_1Producer.html">Producer</a></div><div
  class="line"><a name="l00074"></a><span class="lineno">   74</span>&#160;  {</div><div class="line"><a name="l00075"></a><span class="lineno">   75</span>&#160;  <span class="keyword">public</span>:</div><div class="line"><a name="l00076"></a><span class="lineno"><a class="line" href="classprocess_1_1EventQueue_1_1Producer.html#a30a6a96aad51b429e48eba775a4a002d">   76</a></span>&#160;    <span class="keywordtype">void</span> <a class="code" href="classprocess_1_1EventQueue_1_1Producer.html#a30a6a96aad51b429e48eba775a4a002d">enqueue</a>(<a class="code" href="structprocess_1_1Event.html">Event</a>* event) { queue-&gt;enqueue(event); }</div><div class="line"><a name="l00077"></a><span class="lineno">   77</span>&#160;</div><div class="line"><a name="l00078"></a><span class="lineno">   78</span>&#160;  <span class="keyword">private</span>:</div><div class="line"><a name="l00079"></a><span class="lineno"><a class="line" href="classprocess_1_1EventQueue_1_1Producer.html#a3b1787a64e5e97ce
 075c05a58303d58c">   79</a></span>&#160;    <span class="keyword">friend</span> <span class="keyword">class </span><a class="code" href="classprocess_1_1EventQueue.html">EventQueue</a>;</div><div class="line"><a name="l00080"></a><span class="lineno">   80</span>&#160;</div><div class="line"><a name="l00081"></a><span class="lineno">   81</span>&#160;    <a class="code" href="classprocess_1_1EventQueue_1_1Producer.html">Producer</a>(<a class="code" href="classprocess_1_1EventQueue.html">EventQueue</a>* queue) : queue(queue) {}</div><div class="line"><a name="l00082"></a><span class="lineno">   82</span>&#160;</div><div class="line"><a name="l00083"></a><span class="lineno">   83</span>&#160;    <a class="code" href="classprocess_1_1EventQueue.html">EventQueue</a>* queue;</div><div class="line"><a name="l00084"></a><span class="lineno">   84</span>&#160;  } <a class="code" href="classprocess_1_1EventQueue.html#aa95046266e731af49ccfb9d689cb1eca">producer</a>;</div><div class="line"><a
  name="l00085"></a><span class="lineno">   85</span>&#160;</div><div class="line"><a name="l00086"></a><span class="lineno"><a class="line" href="classprocess_1_1EventQueue_1_1Consumer.html">   86</a></span>&#160;  <span class="keyword">class </span><a class="code" href="classprocess_1_1EventQueue_1_1Consumer.html">Consumer</a></div><div class="line"><a name="l00087"></a><span class="lineno">   87</span>&#160;  {</div><div class="line"><a name="l00088"></a><span class="lineno">   88</span>&#160;  <span class="keyword">public</span>:</div><div class="line"><a name="l00089"></a><span class="lineno"><a class="line" href="classprocess_1_1EventQueue_1_1Consumer.html#a0947a38c4933c27cc6b422ce9171a400">   89</a></span>&#160;    <a class="code" href="structprocess_1_1Event.html">Event</a>* <a class="code" href="classprocess_1_1EventQueue_1_1Consumer.html#a0947a38c4933c27cc6b422ce9171a400">dequeue</a>() { <span class="keywordflow">return</span> queue-&gt;dequeue(); }</div><div class="line"><
 a name="l00090"></a><span class="lineno"><a class="line" href="classprocess_1_1EventQueue_1_1Consumer.html#aa42de8d3e7ba7c56362a36efa773790d">   90</a></span>&#160;    <span class="keywordtype">bool</span> <a class="code" href="classprocess_1_1EventQueue_1_1Consumer.html#aa42de8d3e7ba7c56362a36efa773790d">empty</a>() { <span class="keywordflow">return</span> queue-&gt;empty(); }</div><div class="line"><a name="l00091"></a><span class="lineno"><a class="line" href="classprocess_1_1EventQueue_1_1Consumer.html#a7976eeb2b9ff88c5f03551c63764a162">   91</a></span>&#160;    <span class="keywordtype">void</span> <a class="code" href="classprocess_1_1EventQueue_1_1Consumer.html#a7976eeb2b9ff88c5f03551c63764a162">decomission</a>() { queue-&gt;decomission(); }</div><div class="line"><a name="l00092"></a><span class="lineno">   92</span>&#160;    <span class="keyword">template</span> &lt;<span class="keyword">typename</span> T&gt;</div><div class="line"><a name="l00093"></a><span class="lineno"
 ><a class="line" href="classprocess_1_1EventQueue_1_1Consumer.html#a8d998919af90a6146e6745a1217be3ce">   93</a></span>&#160;    <span class="keywordtype">size_t</span> <a class="code" href="classprocess_1_1EventQueue_1_1Consumer.html#a8d998919af90a6146e6745a1217be3ce">count</a>() { <span class="keywordflow">return</span> queue-&gt;count&lt;T&gt;(); }</div><div class="line"><a name="l00094"></a><span class="lineno"><a class="line" href="classprocess_1_1EventQueue_1_1Consumer.html#a307aaa062d7b5feee064e0361a3cb166">   94</a></span>&#160;    <span class="keyword">operator</span> <a class="code" href="structJSON_1_1Array.html">JSON::Array</a>() { <span class="keywordflow">return</span> queue-&gt;operator <a class="code" href="structJSON_1_1Array.html">JSON::Array</a>(); }</div><div class="line"><a name="l00095"></a><span class="lineno">   95</span>&#160;</div><div class="line"><a name="l00096"></a><span class="lineno">   96</span>&#160;  <span class="keyword">private</span>:</div><div c
 lass="line"><a name="l00097"></a><span class="lineno"><a class="line" href="classprocess_1_1EventQueue_1_1Consumer.html#a3b1787a64e5e97ce075c05a58303d58c">   97</a></span>&#160;    <span class="keyword">friend</span> <span class="keyword">class </span><a class="code" href="classprocess_1_1EventQueue.html">EventQueue</a>;</div><div class="line"><a name="l00098"></a><span class="lineno">   98</span>&#160;</div><div class="line"><a name="l00099"></a><span class="lineno">   99</span>&#160;    <a class="code" href="classprocess_1_1EventQueue.html#a11390aaa07bced511a5b7fe4c94e97fd">Consumer</a>(<a class="code" href="classprocess_1_1EventQueue.html">EventQueue</a>* queue) : queue(queue) {}</div><div class="line"><a name="l00100"></a><span class="lineno">  100</span>&#160;</div><div class="line"><a name="l00101"></a><span class="lineno">  101</span>&#160;    <a class="code" href="classprocess_1_1EventQueue.html">EventQueue</a>* queue;</div><div class="line"><a name="l00102"></a><span class=
 "lineno">  102</span>&#160;  } <a class="code" href="classprocess_1_1EventQueue.html#a73f44b10f6d09ead6bdf3ab11cba4d06">consumer</a>;</div><div class="line"><a name="l00103"></a><span class="lineno">  103</span>&#160;</div><div class="line"><a name="l00104"></a><span class="lineno">  104</span>&#160;<span class="keyword">private</span>:</div><div class="line"><a name="l00105"></a><span class="lineno"><a class="line" href="classprocess_1_1EventQueue.html#aaf00b363e56ec3a72a6f775a3814d6a0">  105</a></span>&#160;  <span class="keyword">friend</span> <span class="keyword">class </span><a class="code" href="classprocess_1_1EventQueue_1_1Producer.html">Producer</a>;</div><div class="line"><a name="l00106"></a><span class="lineno"><a class="line" href="classprocess_1_1EventQueue.html#a11390aaa07bced511a5b7fe4c94e97fd">  106</a></span>&#160;  <span class="keyword">friend</span> <span class="keyword">class </span><a class="code" href="classprocess_1_1EventQueue_1_1Consumer.html">Consumer</a>
 ;</div><div class="line"><a name="l00107"></a><span class="lineno">  107</span>&#160;</div><div class="line"><a name="l00108"></a><span class="lineno">  108</span>&#160;<span class="preprocessor">#ifndef LOCK_FREE_EVENT_QUEUE</span></div><div class="line"><a name="l00109"></a><span class="lineno">  109</span>&#160;  <span class="keywordtype">void</span> <a class="code" href="classprocess_1_1EventQueue_1_1Producer.html#a30a6a96aad51b429e48eba775a4a002d">enqueue</a>(<a class="code" href="structprocess_1_1Event.html">Event</a>* event)</div><div class="line"><a name="l00110"></a><span class="lineno">  110</span>&#160;  {</div><div class="line"><a name="l00111"></a><span class="lineno">  111</span>&#160;    <span class="keywordtype">bool</span> enqueued = <span class="keyword">false</span>;</div><div class="line"><a name="l00112"></a><span class="lineno">  112</span>&#160;    <span class="keyword">synchronized</span> (mutex) {</div><div class="line"><a name="l00113"></a><span class="line
 no">  113</span>&#160;      <span class="keywordflow">if</span> (comissioned) {</div><div class="line"><a name="l00114"></a><span class="lineno">  114</span>&#160;        events.push_back(event);</div><div class="line"><a name="l00115"></a><span class="lineno">  115</span>&#160;        enqueued = <span class="keyword">true</span>;</div><div class="line"><a name="l00116"></a><span class="lineno">  116</span>&#160;      }</div><div class="line"><a name="l00117"></a><span class="lineno">  117</span>&#160;    }</div><div class="line"><a name="l00118"></a><span class="lineno">  118</span>&#160;</div><div class="line"><a name="l00119"></a><span class="lineno">  119</span>&#160;    <span class="keywordflow">if</span> (!enqueued) {</div><div class="line"><a name="l00120"></a><span class="lineno">  120</span>&#160;      <span class="keyword">delete</span> event;</div><div class="line"><a name="l00121"></a><span class="lineno">  121</span>&#160;    }</div><div class="line"><a name="l00122"></
 a><span class="lineno">  122</span>&#160;  }</div><div class="line"><a name="l00123"></a><span class="lineno">  123</span>&#160;</div><div class="line"><a name="l00124"></a><span class="lineno">  124</span>&#160;  <a class="code" href="structprocess_1_1Event.html">Event</a>* dequeue()</div><div class="line"><a name="l00125"></a><span class="lineno">  125</span>&#160;  {</div><div class="line"><a name="l00126"></a><span class="lineno">  126</span>&#160;    <a class="code" href="structprocess_1_1Event.html">Event</a>* <span class="keyword">event</span> = <span class="keyword">nullptr</span>;</div><div class="line"><a name="l00127"></a><span class="lineno">  127</span>&#160;</div><div class="line"><a name="l00128"></a><span class="lineno">  128</span>&#160;    <span class="keyword">synchronized</span> (mutex) {</div><div class="line"><a name="l00129"></a><span class="lineno">  129</span>&#160;      <span class="keywordflow">if</span> (events.size() &gt; 0) {</div><div class="line"><a n
 ame="l00130"></a><span class="lineno">  130</span>&#160;        <a class="code" href="structprocess_1_1Event.html">Event</a>* <span class="keyword">event</span> = events.front();</div><div class="line"><a name="l00131"></a><span class="lineno">  131</span>&#160;        events.pop_front();</div><div class="line"><a name="l00132"></a><span class="lineno">  132</span>&#160;        <span class="keywordflow">return</span> event;</div><div class="line"><a name="l00133"></a><span class="lineno">  133</span>&#160;      }</div><div class="line"><a name="l00134"></a><span class="lineno">  134</span>&#160;    }</div><div class="line"><a name="l00135"></a><span class="lineno">  135</span>&#160;</div><div class="line"><a name="l00136"></a><span class="lineno">  136</span>&#160;    <span class="comment">// Semantics are the consumer _must_ call `empty()` before calling</span></div><div class="line"><a name="l00137"></a><span class="lineno">  137</span>&#160;    <span class="comment">// `dequeue()
 ` which means an event must be present.</span></div><div class="line"><a name="l00138"></a><span class="lineno">  138</span>&#160;    <span class="keywordflow">return</span> CHECK_NOTNULL(event);</div><div class="line"><a name="l00139"></a><span class="lineno">  139</span>&#160;  }</div><div class="line"><a name="l00140"></a><span class="lineno">  140</span>&#160;</div><div class="line"><a name="l00141"></a><span class="lineno">  141</span>&#160;  <span class="keywordtype">bool</span> empty()</div><div class="line"><a name="l00142"></a><span class="lineno">  142</span>&#160;  {</div><div class="line"><a name="l00143"></a><span class="lineno">  143</span>&#160;    <span class="keyword">synchronized</span> (mutex) {</div><div class="line"><a name="l00144"></a><span class="lineno">  144</span>&#160;      <span class="keywordflow">return</span> events.size() == 0;</div><div class="line"><a name="l00145"></a><span class="lineno">  145</span>&#160;    }</div><div class="line"><a name="l00
 146"></a><span class="lineno">  146</span>&#160;  }</div><div class="line"><a name="l00147"></a><span class="lineno">  147</span>&#160;</div><div class="line"><a name="l00148"></a><span class="lineno">  148</span>&#160;  <span class="keywordtype">void</span> decomission()</div><div class="line"><a name="l00149"></a><span class="lineno">  149</span>&#160;  {</div><div class="line"><a name="l00150"></a><span class="lineno">  150</span>&#160;    <span class="keyword">synchronized</span> (mutex) {</div><div class="line"><a name="l00151"></a><span class="lineno">  151</span>&#160;      comissioned = <span class="keyword">false</span>;</div><div class="line"><a name="l00152"></a><span class="lineno">  152</span>&#160;      <span class="keywordflow">while</span> (!events.empty()) {</div><div class="line"><a name="l00153"></a><span class="lineno">  153</span>&#160;        <a class="code" href="structprocess_1_1Event.html">Event</a>* <span class="keyword">event</span> = events.front();</div>
 <div class="line"><a name="l00154"></a><span class="lineno">  154</span>&#160;        events.pop_front();</div><div class="line"><a name="l00155"></a><span class="lineno">  155</span>&#160;        <span class="keyword">delete</span> event;</div><div class="line"><a name="l00156"></a><span class="lineno">  156</span>&#160;      }</div><div class="line"><a name="l00157"></a><span class="lineno">  157</span>&#160;    }</div><div class="line"><a name="l00158"></a><span class="lineno">  158</span>&#160;  }</div><div class="line"><a name="l00159"></a><span class="lineno">  159</span>&#160;</div><div class="line"><a name="l00160"></a><span class="lineno">  160</span>&#160;  <span class="keyword">template</span> &lt;<span class="keyword">typename</span> T&gt;</div><div class="line"><a name="l00161"></a><span class="lineno">  161</span>&#160;  <span class="keywordtype">size_t</span> count()</div><div class="line"><a name="l00162"></a><span class="lineno">  162</span>&#160;  {</div><div class
 ="line"><a name="l00163"></a><span class="lineno">  163</span>&#160;    <span class="keyword">synchronized</span> (mutex) {</div><div class="line"><a name="l00164"></a><span class="lineno">  164</span>&#160;      <span class="keywordflow">return</span> std::count_if(</div><div class="line"><a name="l00165"></a><span class="lineno">  165</span>&#160;          events.begin(),</div><div class="line"><a name="l00166"></a><span class="lineno">  166</span>&#160;          events.end(),</div><div class="line"><a name="l00167"></a><span class="lineno">  167</span>&#160;          [](<span class="keyword">const</span> <a class="code" href="structprocess_1_1Event.html">Event</a>* event) {</div><div class="line"><a name="l00168"></a><span class="lineno">  168</span>&#160;            <span class="keywordflow">return</span> <span class="keyword">event</span>-&gt;is&lt;T&gt;();</div><div class="line"><a name="l00169"></a><span class="lineno">  169</span>&#160;          });</div><div class="line"><a
  name="l00170"></a><span class="lineno">  170</span>&#160;    }</div><div class="line"><a name="l00171"></a><span class="lineno">  171</span>&#160;  }</div><div class="line"><a name="l00172"></a><span class="lineno">  172</span>&#160;</div><div class="line"><a name="l00173"></a><span class="lineno">  173</span>&#160;  <span class="keyword">operator</span> <a class="code" href="structJSON_1_1Array.html">JSON::Array</a>()</div><div class="line"><a name="l00174"></a><span class="lineno">  174</span>&#160;  {</div><div class="line"><a name="l00175"></a><span class="lineno">  175</span>&#160;    <a class="code" href="structJSON_1_1Array.html">JSON::Array</a> array;</div><div class="line"><a name="l00176"></a><span class="lineno">  176</span>&#160;    <span class="keyword">synchronized</span> (mutex) {</div><div class="line"><a name="l00177"></a><span class="lineno">  177</span>&#160;      <span class="keywordflow">foreach</span> (<a class="code" href="structprocess_1_1Event.html">Event</
 a>* event, events) {</div><div class="line"><a name="l00178"></a><span class="lineno">  178</span>&#160;        array.<a class="code" href="structJSON_1_1Array.html#aed41033b7cd6a2c2e7dcc6f0c48a4563">values</a>.push_back(<a class="code" href="structJSON_1_1Object.html">JSON::Object</a>(*event));</div><div class="line"><a name="l00179"></a><span class="lineno">  179</span>&#160;      }</div><div class="line"><a name="l00180"></a><span class="lineno">  180</span>&#160;    }</div><div class="line"><a name="l00181"></a><span class="lineno">  181</span>&#160;    <span class="keywordflow">return</span> array;</div><div class="line"><a name="l00182"></a><span class="lineno">  182</span>&#160;  }</div><div class="line"><a name="l00183"></a><span class="lineno">  183</span>&#160;</div><div class="line"><a name="l00184"></a><span class="lineno">  184</span>&#160;  std::mutex mutex;</div><div class="line"><a name="l00185"></a><span class="lineno">  185</span>&#160;  std::deque&lt;Event*&gt; ev
 ents;</div><div class="line"><a name="l00186"></a><span class="lineno">  186</span>&#160;  <span class="keywordtype">bool</span> comissioned = <span class="keyword">true</span>;</div><div class="line"><a name="l00187"></a><span class="lineno">  187</span>&#160;<span class="preprocessor">#else // LOCK_FREE_EVENT_QUEUE</span></div><div class="line"><a name="l00188"></a><span class="lineno">  188</span>&#160;  <span class="keywordtype">void</span> <a class="code" href="classprocess_1_1EventQueue_1_1Producer.html#a30a6a96aad51b429e48eba775a4a002d">enqueue</a>(<a class="code" href="structprocess_1_1Event.html">Event</a>* event)</div><div class="line"><a name="l00189"></a><span class="lineno">  189</span>&#160;  {</div><div class="line"><a name="l00190"></a><span class="lineno">  190</span>&#160;    <span class="keywordflow">if</span> (comissioned.load()) {</div><div class="line"><a name="l00191"></a><span class="lineno">  191</span>&#160;      queue.enqueue(event);</div><div class="line"
 ><a name="l00192"></a><span class="lineno">  192</span>&#160;    } <span class="keywordflow">else</span> {</div><div class="line"><a name="l00193"></a><span class="lineno">  193</span>&#160;      <span class="keyword">delete</span> event;</div><div class="line"><a name="l00194"></a><span class="lineno">  194</span>&#160;    }</div><div class="line"><a name="l00195"></a><span class="lineno">  195</span>&#160;  }</div><div class="line"><a name="l00196"></a><span class="lineno">  196</span>&#160;</div><div class="line"><a name="l00197"></a><span class="lineno">  197</span>&#160;  <a class="code" href="structprocess_1_1Event.html">Event</a>* dequeue()</div><div class="line"><a name="l00198"></a><span class="lineno">  198</span>&#160;  {</div><div class="line"><a name="l00199"></a><span class="lineno">  199</span>&#160;    <span class="keywordflow">return</span> queue.dequeue();</div><div class="line"><a name="l00200"></a><span class="lineno">  200</span>&#160;  }</div><div class="line">
 <a name="l00201"></a><span class="lineno">  201</span>&#160;</div><div class="line"><a name="l00202"></a><span class="lineno">  202</span>&#160;  <span class="keywordtype">bool</span> empty()</div><div class="line"><a name="l00203"></a><span class="lineno">  203</span>&#160;  {</div><div class="line"><a name="l00204"></a><span class="lineno">  204</span>&#160;    <span class="keywordflow">return</span> queue.empty();</div><div class="line"><a name="l00205"></a><span class="lineno">  205</span>&#160;  }</div><div class="line"><a name="l00206"></a><span class="lineno">  206</span>&#160;</div><div class="line"><a name="l00207"></a><span class="lineno">  207</span>&#160;  <span class="keywordtype">void</span> decomission()</div><div class="line"><a name="l00208"></a><span class="lineno">  208</span>&#160;  {</div><div class="line"><a name="l00209"></a><span class="lineno">  209</span>&#160;    comissioned.store(<span class="keyword">true</span>);</div><div class="line

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