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<a href="a00137.html">Go to the documentation of this file.</a><div class="fragment"><div class="line"><a name="l00001"></a><span class="lineno"> 1</span> // <shared_mutex> -*- C++ -*-</div><div class="line"><a name="l00002"></a><span class="lineno"> 2</span> </div><div class="line"><a name="l00003"></a><span class="lineno"> 3</span> // Copyright (C) 2013-2018 Free Software Foundation, Inc.</div><div class="line"><a name="l00004"></a><span class="lineno"> 4</span> //</div><div class="line"><a name="l00005"></a><span class="lineno"> 5</span> // This file is part of the GNU ISO C++ Library. This library is free</div><div class="line"><a name="l00006"></a><span class="lineno"> 6</span> // software; you can redistribute it and/or modify it under the</div><div class="line"><a name="l00007"></a><span class="lineno"> 7</span> // terms of the GNU General Public License as published by the</div><div class="line"><a name="l00008"></a><span class="lineno"> 8</span> // Free Software Foundation; either version 3, or (at your option)</div><div class="line"><a name="l00009"></a><span class="lineno"> 9</span> // any later version.</div><div class="line"><a name="l00010"></a><span class="lineno"> 10</span> </div><div class="line"><a name="l00011"></a><span class="lineno"> 11</span> // This library is distributed in the hope that it will be useful,</div><div class="line"><a name="l00012"></a><span class="lineno"> 12</span> // but WITHOUT ANY WARRANTY; without even the implied warranty of</div><div class="line"><a name="l00013"></a><span class="lineno"> 13</span> // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the</div><div class="line"><a name="l00014"></a><span class="lineno"> 14</span> // GNU General Public License for more details.</div><div class="line"><a name="l00015"></a><span class="lineno"> 15</span> </div><div class="line"><a name="l00016"></a><span class="lineno"> 16</span> // Under Section 7 of GPL version 3, you are granted additional</div><div class="line"><a name="l00017"></a><span class="lineno"> 17</span> // permissions described in the GCC Runtime Library Exception, version</div><div class="line"><a name="l00018"></a><span class="lineno"> 18</span> // 3.1, as published by the Free Software Foundation.</div><div class="line"><a name="l00019"></a><span class="lineno"> 19</span> </div><div class="line"><a name="l00020"></a><span class="lineno"> 20</span> // You should have received a copy of the GNU General Public License and</div><div class="line"><a name="l00021"></a><span class="lineno"> 21</span> // a copy of the GCC Runtime Library Exception along with this program;</div><div class="line"><a name="l00022"></a><span class="lineno"> 22</span> // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see</div><div class="line"><a name="l00023"></a><span class="lineno"> 23</span> // <http://www.gnu.org/licenses/>.</div><div class="line"><a name="l00024"></a><span class="lineno"> 24</span> </div><div class="line"><a name="l00025"></a><span class="lineno"> 25</span> /** @file include/shared_mutex</div><div class="line"><a name="l00026"></a><span class="lineno"> 26</span>  * This is a Standard C++ Library header.</div><div class="line"><a name="l00027"></a><span class="lineno"> 27</span>  */</div><div class="line"><a name="l00028"></a><span class="lineno"> 28</span> </div><div class="line"><a name="l00029"></a><span class="lineno"> 29</span> #ifndef _GLIBCXX_SHARED_MUTEX</div><div class="line"><a name="l00030"></a><span class="lineno"> 30</span> #define _GLIBCXX_SHARED_MUTEX 1</div><div class="line"><a name="l00031"></a><span class="lineno"> 31</span> </div><div class="line"><a name="l00032"></a><span class="lineno"> 32</span> #pragma GCC system_header</div><div class="line"><a name="l00033"></a><span class="lineno"> 33</span> </div><div class="line"><a name="l00034"></a><span class="lineno"> 34</span> #if __cplusplus >= 201402L</div><div class="line"><a name="l00035"></a><span class="lineno"> 35</span> </div><div class="line"><a name="l00036"></a><span class="lineno"> 36</span> #include <bits/c++config.h></div><div class="line"><a name="l00037"></a><span class="lineno"> 37</span> #include <condition_variable></div><div class="line"><a name="l00038"></a><span class="lineno"> 38</span> #include <bits/functexcept.h></div><div class="line"><a name="l00039"></a><span class="lineno"> 39</span> </div><div class="line"><a name="l00040"></a><span class="lineno"> 40</span> namespace std _GLIBCXX_VISIBILITY(default)</div><div class="line"><a name="l00041"></a><span class="lineno"> 41</span> {</div><div class="line"><a name="l00042"></a><span class="lineno"> 42</span> _GLIBCXX_BEGIN_NAMESPACE_VERSION</div><div class="line"><a name="l00043"></a><span class="lineno"> 43</span> </div><div class="line"><a name="l00044"></a><span class="lineno"> 44</span>  /**</div><div class="line"><a name="l00045"></a><span class="lineno"> 45</span>  * @ingroup mutexes</div><div class="line"><a name="l00046"></a><span class="lineno"> 46</span>  * @{</div><div class="line"><a name="l00047"></a><span class="lineno"> 47</span>  */</div><div class="line"><a name="l00048"></a><span class="lineno"> 48</span> </div><div class="line"><a name="l00049"></a><span class="lineno"> 49</span> #ifdef _GLIBCXX_USE_C99_STDINT_TR1</div><div class="line"><a name="l00050"></a><span class="lineno"> 50</span> #ifdef _GLIBCXX_HAS_GTHREADS</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> #if __cplusplus >= 201703L</div><div class="line"><a name="l00053"></a><span class="lineno"> 53</span> #define __cpp_lib_shared_mutex 201505</div><div class="line"><a name="l00054"></a><span class="lineno"> 54</span>  class shared_mutex;</div><div class="line"><a name="l00055"></a><span class="lineno"> 55</span> #endif</div><div class="line"><a name="l00056"></a><span class="lineno"> 56</span> </div><div class="line"><a name="l00057"></a><span class="lineno"> 57</span> #define __cpp_lib_shared_timed_mutex 201402</div><div class="line"><a name="l00058"></a><span class="lineno"> 58</span>  class shared_timed_mutex;</div><div class="line"><a name="l00059"></a><span class="lineno"> 59</span> </div><div class="line"><a name="l00060"></a><span class="lineno"> 60</span> #if _GLIBCXX_USE_PTHREAD_RWLOCK_T</div><div class="line"><a name="l00061"></a><span class="lineno"> 61</span>  /// A shared mutex type implemented using pthread_rwlock_t.</div><div class="line"><a name="l00062"></a><span class="lineno"> 62</span>  class __shared_mutex_pthread</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>  friend class shared_timed_mutex;</div><div class="line"><a name="l00065"></a><span class="lineno"> 65</span> </div><div class="line"><a name="l00066"></a><span class="lineno"> 66</span> #ifdef PTHREAD_RWLOCK_INITIALIZER</div><div class="line"><a name="l00067"></a><span class="lineno"> 67</span>  pthread_rwlock_t _M_rwlock = PTHREAD_RWLOCK_INITIALIZER;</div><div class="line"><a name="l00068"></a><span class="lineno"> 68</span> </div><div class="line"><a name="l00069"></a><span class="lineno"> 69</span>  public:</div><div class="line"><a name="l00070"></a><span class="lineno"> 70</span>  __shared_mutex_pthread() = default;</div><div class="line"><a name="l00071"></a><span class="lineno"> 71</span>  ~__shared_mutex_pthread() = default;</div><div class="line"><a name="l00072"></a><span class="lineno"> 72</span> #else</div><div class="line"><a name="l00073"></a><span class="lineno"> 73</span>  pthread_rwlock_t _M_rwlock;</div><div class="line"><a name="l00074"></a><span class="lineno"> 74</span> </div><div class="line"><a name="l00075"></a><span class="lineno"> 75</span>  public:</div><div class="line"><a name="l00076"></a><span class="lineno"> 76</span>  __shared_mutex_pthread()</div><div class="line"><a name="l00077"></a><span class="lineno"> 77</span>  {</div><div class="line"><a name="l00078"></a><span class="lineno"> 78</span>  int __ret = pthread_rwlock_init(&_M_rwlock, NULL);</div><div class="line"><a name="l00079"></a><span class="lineno"> 79</span>  if (__ret == ENOMEM)</div><div class="line"><a name="l00080"></a><span class="lineno"> 80</span>  __throw_bad_alloc();</div><div class="line"><a name="l00081"></a><span class="lineno"> 81</span>  else if (__ret == EAGAIN)</div><div class="line"><a name="l00082"></a><span class="lineno"> 82</span>  __throw_system_error(int(errc::resource_unavailable_try_again));</div><div class="line"><a name="l00083"></a><span class="lineno"> 83</span>  else if (__ret == EPERM)</div><div class="line"><a name="l00084"></a><span class="lineno"> 84</span>  __throw_system_error(int(errc::operation_not_permitted));</div><div class="line"><a name="l00085"></a><span class="lineno"> 85</span>  // Errors not handled: EBUSY, EINVAL</div><div class="line"><a name="l00086"></a><span class="lineno"> 86</span>  __glibcxx_assert(__ret == 0);</div><div class="line"><a name="l00087"></a><span class="lineno"> 87</span>  }</div><div class="line"><a name="l00088"></a><span class="lineno"> 88</span> </div><div class="line"><a name="l00089"></a><span class="lineno"> 89</span>  ~__shared_mutex_pthread()</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>  int __ret __attribute((__unused__)) = pthread_rwlock_destroy(&_M_rwlock);</div><div class="line"><a name="l00092"></a><span class="lineno"> 92</span>  // Errors not handled: EBUSY, EINVAL</div><div class="line"><a name="l00093"></a><span class="lineno"> 93</span>  __glibcxx_assert(__ret == 0);</div><div class="line"><a name="l00094"></a><span class="lineno"> 94</span>  }</div><div class="line"><a name="l00095"></a><span class="lineno"> 95</span> #endif</div><div class="line"><a name="l00096"></a><span class="lineno"> 96</span> </div><div class="line"><a name="l00097"></a><span class="lineno"> 97</span>  __shared_mutex_pthread(const __shared_mutex_pthread&) = delete;</div><div class="line"><a name="l00098"></a><span class="lineno"> 98</span>  __shared_mutex_pthread& operator=(const __shared_mutex_pthread&) = delete;</div><div class="line"><a name="l00099"></a><span class="lineno"> 99</span> </div><div class="line"><a name="l00100"></a><span class="lineno"> 100</span>  void</div><div class="line"><a name="l00101"></a><span class="lineno"> 101</span>  lock()</div><div class="line"><a name="l00102"></a><span class="lineno"> 102</span>  {</div><div class="line"><a name="l00103"></a><span class="lineno"> 103</span>  int __ret = pthread_rwlock_wrlock(&_M_rwlock);</div><div class="line"><a name="l00104"></a><span class="lineno"> 104</span>  if (__ret == EDEADLK)</div><div class="line"><a name="l00105"></a><span class="lineno"> 105</span>  __throw_system_error(int(errc::resource_deadlock_would_occur));</div><div class="line"><a name="l00106"></a><span class="lineno"> 106</span>  // Errors not handled: EINVAL</div><div class="line"><a name="l00107"></a><span class="lineno"> 107</span>  __glibcxx_assert(__ret == 0);</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>  bool</div><div class="line"><a name="l00111"></a><span class="lineno"> 111</span>  try_lock()</div><div class="line"><a name="l00112"></a><span class="lineno"> 112</span>  {</div><div class="line"><a name="l00113"></a><span class="lineno"> 113</span>  int __ret = pthread_rwlock_trywrlock(&_M_rwlock);</div><div class="line"><a name="l00114"></a><span class="lineno"> 114</span>  if (__ret == EBUSY) return false;</div><div class="line"><a name="l00115"></a><span class="lineno"> 115</span>  // Errors not handled: EINVAL</div><div class="line"><a name="l00116"></a><span class="lineno"> 116</span>  __glibcxx_assert(__ret == 0);</div><div class="line"><a name="l00117"></a><span class="lineno"> 117</span>  return true;</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>  void</div><div class="line"><a name="l00121"></a><span class="lineno"> 121</span>  unlock()</div><div class="line"><a name="l00122"></a><span class="lineno"> 122</span>  {</div><div class="line"><a name="l00123"></a><span class="lineno"> 123</span>  int __ret __attribute((__unused__)) = pthread_rwlock_unlock(&_M_rwlock);</div><div class="line"><a name="l00124"></a><span class="lineno"> 124</span>  // Errors not handled: EPERM, EBUSY, EINVAL</div><div class="line"><a name="l00125"></a><span class="lineno"> 125</span>  __glibcxx_assert(__ret == 0);</div><div class="line"><a name="l00126"></a><span class="lineno"> 126</span>  }</div><div class="line"><a name="l00127"></a><span class="lineno"> 127</span> </div><div class="line"><a name="l00128"></a><span class="lineno"> 128</span>  // Shared ownership</div><div class="line"><a name="l00129"></a><span class="lineno"> 129</span> </div><div class="line"><a name="l00130"></a><span class="lineno"> 130</span>  void</div><div class="line"><a name="l00131"></a><span class="lineno"> 131</span>  lock_shared()</div><div class="line"><a name="l00132"></a><span class="lineno"> 132</span>  {</div><div class="line"><a name="l00133"></a><span class="lineno"> 133</span>  int __ret;</div><div class="line"><a name="l00134"></a><span class="lineno"> 134</span>  // We retry if we exceeded the maximum number of read locks supported by</div><div class="line"><a name="l00135"></a><span class="lineno"> 135</span>  // the POSIX implementation; this can result in busy-waiting, but this</div><div class="line"><a name="l00136"></a><span class="lineno"> 136</span>  // is okay based on the current specification of forward progress</div><div class="line"><a name="l00137"></a><span class="lineno"> 137</span>  // guarantees by the standard.</div><div class="line"><a name="l00138"></a><span class="lineno"> 138</span>  do</div><div class="line"><a name="l00139"></a><span class="lineno"> 139</span>  __ret = pthread_rwlock_rdlock(&_M_rwlock);</div><div class="line"><a name="l00140"></a><span class="lineno"> 140</span>  while (__ret == EAGAIN);</div><div class="line"><a name="l00141"></a><span class="lineno"> 141</span>  if (__ret == EDEADLK)</div><div class="line"><a name="l00142"></a><span class="lineno"> 142</span>  __throw_system_error(int(errc::resource_deadlock_would_occur));</div><div class="line"><a name="l00143"></a><span class="lineno"> 143</span>  // Errors not handled: EINVAL</div><div class="line"><a name="l00144"></a><span class="lineno"> 144</span>  __glibcxx_assert(__ret == 0);</div><div class="line"><a name="l00145"></a><span class="lineno"> 145</span>  }</div><div class="line"><a name="l00146"></a><span class="lineno"> 146</span> </div><div class="line"><a name="l00147"></a><span class="lineno"> 147</span>  bool</div><div class="line"><a name="l00148"></a><span class="lineno"> 148</span>  try_lock_shared()</div><div class="line"><a name="l00149"></a><span class="lineno"> 149</span>  {</div><div class="line"><a name="l00150"></a><span class="lineno"> 150</span>  int __ret = pthread_rwlock_tryrdlock(&_M_rwlock);</div><div class="line"><a name="l00151"></a><span class="lineno"> 151</span>  // If the maximum number of read locks has been exceeded, we just fail</div><div class="line"><a name="l00152"></a><span class="lineno"> 152</span>  // to acquire the lock. Unlike for lock(), we are not allowed to throw</div><div class="line"><a name="l00153"></a><span class="lineno"> 153</span>  // an exception.</div><div class="line"><a name="l00154"></a><span class="lineno"> 154</span>  if (__ret == EBUSY || __ret == EAGAIN) return false;</div><div class="line"><a name="l00155"></a><span class="lineno"> 155</span>  // Errors not handled: EINVAL</div><div class="line"><a name="l00156"></a><span class="lineno"> 156</span>  __glibcxx_assert(__ret == 0);</div><div class="line"><a name="l00157"></a><span class="lineno"> 157</span>  return true;</div><div class="line"><a name="l00158"></a><span class="lineno"> 158</span>  }</div><div class="line"><a name="l00159"></a><span class="lineno"> 159</span> </div><div class="line"><a name="l00160"></a><span class="lineno"> 160</span>  void</div><div class="line"><a name="l00161"></a><span class="lineno"> 161</span>  unlock_shared()</div><div class="line"><a name="l00162"></a><span class="lineno"> 162</span>  {</div><div class="line"><a name="l00163"></a><span class="lineno"> 163</span>  unlock();</div><div class="line"><a name="l00164"></a><span class="lineno"> 164</span>  }</div><div class="line"><a name="l00165"></a><span class="lineno"> 165</span> </div><div class="line"><a name="l00166"></a><span class="lineno"> 166</span>  void* native_handle() { return &_M_rwlock; }</div><div class="line"><a name="l00167"></a><span class="lineno"> 167</span>  };</div><div class="line"><a name="l00168"></a><span class="lineno"> 168</span> #endif</div><div class="line"><a name="l00169"></a><span class="lineno"> 169</span> </div><div class="line"><a name="l00170"></a><span class="lineno"> 170</span> #if ! (_GLIBCXX_USE_PTHREAD_RWLOCK_T && _GTHREAD_USE_MUTEX_TIMEDLOCK)</div><div class="line"><a name="l00171"></a><span class="lineno"> 171</span>  /// A shared mutex type implemented using std::condition_variable.</div><div class="line"><a name="l00172"></a><span class="lineno"> 172</span>  class __shared_mutex_cv</div><div class="line"><a name="l00173"></a><span class="lineno"> 173</span>  {</div><div class="line"><a name="l00174"></a><span class="lineno"> 174</span>  friend class shared_timed_mutex;</div><div class="line"><a name="l00175"></a><span class="lineno"> 175</span> </div><div class="line"><a name="l00176"></a><span class="lineno"> 176</span>  // Based on Howard Hinnant's reference implementation from N2406.</div><div class="line"><a name="l00177"></a><span class="lineno"> 177</span> </div><div class="line"><a name="l00178"></a><span class="lineno"> 178</span>  // The high bit of _M_state is the write-entered flag which is set to</div><div class="line"><a name="l00179"></a><span class="lineno"> 179</span>  // indicate a writer has taken the lock or is queuing to take the lock.</div><div class="line"><a name="l00180"></a><span class="lineno"> 180</span>  // The remaining bits are the count of reader locks.</div><div class="line"><a name="l00181"></a><span class="lineno"> 181</span>  //</div><div class="line"><a name="l00182"></a><span class="lineno"> 182</span>  // To take a reader lock, block on gate1 while the write-entered flag is</div><div class="line"><a name="l00183"></a><span class="lineno"> 183</span>  // set or the maximum number of reader locks is held, then increment the</div><div class="line"><a name="l00184"></a><span class="lineno"> 184</span>  // reader lock count.</div><div class="line"><a name="l00185"></a><span class="lineno"> 185</span>  // To release, decrement the count, then if the write-entered flag is set</div><div class="line"><a name="l00186"></a><span class="lineno"> 186</span>  // and the count is zero then signal gate2 to wake a queued writer,</div><div class="line"><a name="l00187"></a><span class="lineno"> 187</span>  // otherwise if the maximum number of reader locks was held signal gate1</div><div class="line"><a name="l00188"></a><span class="lineno"> 188</span>  // to wake a reader.</div><div class="line"><a name="l00189"></a><span class="lineno"> 189</span>  //</div><div class="line"><a name="l00190"></a><span class="lineno"> 190</span>  // To take a writer lock, block on gate1 while the write-entered flag is</div><div class="line"><a name="l00191"></a><span class="lineno"> 191</span>  // set, then set the write-entered flag to start queueing, then block on</div><div class="line"><a name="l00192"></a><span class="lineno"> 192</span>  // gate2 while the number of reader locks is non-zero.</div><div class="line"><a name="l00193"></a><span class="lineno"> 193</span>  // To release, unset the write-entered flag and signal gate1 to wake all</div><div class="line"><a name="l00194"></a><span class="lineno"> 194</span>  // blocked readers and writers.</div><div class="line"><a name="l00195"></a><span class="lineno"> 195</span>  //</div><div class="line"><a name="l00196"></a><span class="lineno"> 196</span>  // This means that when no reader locks are held readers and writers get</div><div class="line"><a name="l00197"></a><span class="lineno"> 197</span>  // equal priority. When one or more reader locks is held a writer gets</div><div class="line"><a name="l00198"></a><span class="lineno"> 198</span>  // priority and no more reader locks can be taken while the writer is</div><div class="line"><a name="l00199"></a><span class="lineno"> 199</span>  // queued.</div><div class="line"><a name="l00200"></a><span class="lineno"> 200</span> </div><div class="line"><a name="l00201"></a><span class="lineno"> 201</span>  // Only locked when accessing _M_state or waiting on condition variables.</div><div class="line"><a name="l00202"></a><span class="lineno"> 202</span>  mutex _M_mut;</div><div class="line"><a name="l00203"></a><span class="lineno"> 203</span>  // Used to block while write-entered is set or reader count at maximum.</div><div class="line"><a name="l00204"></a><span class="lineno"> 204</span>  condition_variable _M_gate1;</div><div class="line"><a name="l00205"></a><span class="lineno"> 205</span>  // Used to block queued writers while reader count is non-zero.</div><div class="line"><a name="l00206"></a><span class="lineno"> 206</span>  condition_variable _M_gate2;</div><div class="line"><a name="l00207"></a><span class="lineno"> 207</span>  // The write-entered flag and reader count.</div><div class="line"><a name="l00208"></a><span class="lineno"> 208</span>  unsigned _M_state;</div><div class="line"><a name="l00209"></a><span class="lineno"> 209</span> </div><div class="line"><a name="l00210"></a><span class="lineno"> 210</span>  static constexpr unsigned _S_write_entered</div><div class="line"><a name="l00211"></a><span class="lineno"> 211</span>  = 1U << (sizeof(unsigned)*__CHAR_BIT__ - 1);</div><div class="line"><a name="l00212"></a><span class="lineno"> 212</span>  static constexpr unsigned _S_max_readers = ~_S_write_entered;</div><div class="line"><a name="l00213"></a><span class="lineno"> 213</span> </div><div class="line"><a name="l00214"></a><span class="lineno"> 214</span>  // Test whether the write-entered flag is set. _M_mut must be locked.</div><div class="line"><a name="l00215"></a><span class="lineno"> 215</span>  bool _M_write_entered() const { return _M_state & _S_write_entered; }</div><div class="line"><a name="l00216"></a><span class="lineno"> 216</span> </div><div class="line"><a name="l00217"></a><span class="lineno"> 217</span>  // The number of reader locks currently held. _M_mut must be locked.</div><div class="line"><a name="l00218"></a><span class="lineno"> 218</span>  unsigned _M_readers() const { return _M_state & _S_max_readers; }</div><div class="line"><a name="l00219"></a><span class="lineno"> 219</span> </div><div class="line"><a name="l00220"></a><span class="lineno"> 220</span>  public:</div><div class="line"><a name="l00221"></a><span class="lineno"> 221</span>  __shared_mutex_cv() : _M_state(0) {}</div><div class="line"><a name="l00222"></a><span class="lineno"> 222</span> </div><div class="line"><a name="l00223"></a><span class="lineno"> 223</span>  ~__shared_mutex_cv()</div><div class="line"><a name="l00224"></a><span class="lineno"> 224</span>  {</div><div class="line"><a name="l00225"></a><span class="lineno"> 225</span>  __glibcxx_assert( _M_state == 0 );</div><div class="line"><a name="l00226"></a><span class="lineno"> 226</span>  }</div><div class="line"><a name="l00227"></a><span class="lineno"> 227</span> </div><div class="line"><a name="l00228"></a><span class="lineno"> 228</span>  __shared_mutex_cv(const __shared_mutex_cv&) = delete;</div><div class="line"><a name="l00229"></a><span class="lineno"> 229</span>  __shared_mutex_cv& operator=(const __shared_mutex_cv&) = delete;</div><div class="line"><a name="l00230"></a><span class="lineno"> 230</span> </div><div class="line"><a name="l00231"></a><span class="lineno"> 231</span>  // Exclusive ownership</div><div class="line"><a name="l00232"></a><span class="lineno"> 232</span> </div><div class="line"><a name="l00233"></a><span class="lineno"> 233</span>  void</div><div class="line"><a name="l00234"></a><span class="lineno"> 234</span>  lock()</div><div class="line"><a name="l00235"></a><span class="lineno"> 235</span>  {</div><div class="line"><a name="l00236"></a><span class="lineno"> 236</span>  unique_lock<mutex> __lk(_M_mut);</div><div class="line"><a name="l00237"></a><span class="lineno"> 237</span>  // Wait until we can set the write-entered flag.</div><div class="line"><a name="l00238"></a><span class="lineno"> 238</span>  _M_gate1.wait(__lk, [=]{ return !_M_write_entered(); });</div><div class="line"><a name="l00239"></a><span class="lineno"> 239</span>  _M_state |= _S_write_entered;</div><div class="line"><a name="l00240"></a><span class="lineno"> 240</span>  // Then wait until there are no more readers.</div><div class="line"><a name="l00241"></a><span class="lineno"> 241</span>  _M_gate2.wait(__lk, [=]{ return _M_readers() == 0; });</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> </div><div class="line"><a name="l00244"></a><span class="lineno"> 244</span>  bool</div><div class="line"><a name="l00245"></a><span class="lineno"> 245</span>  try_lock()</div><div class="line"><a name="l00246"></a><span class="lineno"> 246</span>  {</div><div class="line"><a name="l00247"></a><span class="lineno"> 247</span>  unique_lock<mutex> __lk(_M_mut, try_to_lock);</div><div class="line"><a name="l00248"></a><span class="lineno"> 248</span>  if (__lk.owns_lock() && _M_state == 0)</div><div class="line"><a name="l00249"></a><span class="lineno"> 249</span>  {</div><div class="line"><a name="l00250"></a><span class="lineno"> 250</span>  _M_state = _S_write_entered;</div><div class="line"><a name="l00251"></a><span class="lineno"> 251</span>  return true;</div><div class="line"><a name="l00252"></a><span class="lineno"> 252</span>  }</div><div class="line"><a name="l00253"></a><span class="lineno"> 253</span>  return false;</div><div class="line"><a name="l00254"></a><span class="lineno"> 254</span>  }</div><div class="line"><a name="l00255"></a><span class="lineno"> 255</span> </div><div class="line"><a name="l00256"></a><span class="lineno"> 256</span>  void</div><div class="line"><a name="l00257"></a><span class="lineno"> 257</span>  unlock()</div><div class="line"><a name="l00258"></a><span class="lineno"> 258</span>  {</div><div class="line"><a name="l00259"></a><span class="lineno"> 259</span>  lock_guard<mutex> __lk(_M_mut);</div><div class="line"><a name="l00260"></a><span class="lineno"> 260</span>  __glibcxx_assert( _M_write_entered() );</div><div class="line"><a name="l00261"></a><span class="lineno"> 261</span>  _M_state = 0;</div><div class="line"><a name="l00262"></a><span class="lineno"> 262</span>  // call notify_all() while mutex is held so that another thread can't</div><div class="line"><a name="l00263"></a><span class="lineno"> 263</span>  // lock and unlock the mutex then destroy *this before we make the call.</div><div class="line"><a name="l00264"></a><span class="lineno"> 264</span>  _M_gate1.notify_all();</div><div class="line"><a name="l00265"></a><span class="lineno"> 265</span>  }</div><div class="line"><a name="l00266"></a><span class="lineno"> 266</span> </div><div class="line"><a name="l00267"></a><span class="lineno"> 267</span>  // Shared ownership</div><div class="line"><a name="l00268"></a><span class="lineno"> 268</span> </div><div class="line"><a name="l00269"></a><span class="lineno"> 269</span>  void</div><div class="line"><a name="l00270"></a><span class="lineno"> 270</span>  lock_shared()</div><div class="line"><a name="l00271"></a><span class="lineno"> 271</span>  {</div><div class="line"><a name="l00272"></a><span class="lineno"> 272</span>  unique_lock<mutex> __lk(_M_mut);</div><div class="line"><a name="l00273"></a><span class="lineno"> 273</span>  _M_gate1.wait(__lk, [=]{ return _M_state < _S_max_readers; });</div><div class="line"><a name="l00274"></a><span class="lineno"> 274</span>  ++_M_state;</div><div class="line"><a name="l00275"></a><span class="lineno"> 275</span>  }</div><div class="line"><a name="l00276"></a><span class="lineno"> 276</span> </div><div class="line"><a name="l00277"></a><span class="lineno"> 277</span>  bool</div><div class="line"><a name="l00278"></a><span class="lineno"> 278</span>  try_lock_shared()</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>  unique_lock<mutex> __lk(_M_mut, try_to_lock);</div><div class="line"><a name="l00281"></a><span class="lineno"> 281</span>  if (!__lk.owns_lock())</div><div class="line"><a name="l00282"></a><span class="lineno"> 282</span>  return false;</div><div class="line"><a name="l00283"></a><span class="lineno"> 283</span>  if (_M_state < _S_max_readers)</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>  ++_M_state;</div><div class="line"><a name="l00286"></a><span class="lineno"> 286</span>  return true;</div><div class="line"><a name="l00287"></a><span class="lineno"> 287</span>  }</div><div class="line"><a name="l00288"></a><span class="lineno"> 288</span>  return false;</div><div class="line"><a name="l00289"></a><span class="lineno"> 289</span>  }</div><div class="line"><a name="l00290"></a><span class="lineno"> 290</span> </div><div class="line"><a name="l00291"></a><span class="lineno"> 291</span>  void</div><div class="line"><a name="l00292"></a><span class="lineno"> 292</span>  unlock_shared()</div><div class="line"><a name="l00293"></a><span class="lineno"> 293</span>  {</div><div class="line"><a name="l00294"></a><span class="lineno"> 294</span>  lock_guard<mutex> __lk(_M_mut);</div><div class="line"><a name="l00295"></a><span class="lineno"> 295</span>  __glibcxx_assert( _M_readers() > 0 );</div><div class="line"><a name="l00296"></a><span class="lineno"> 296</span>  auto __prev = _M_state--;</div><div class="line"><a name="l00297"></a><span class="lineno"> 297</span>  if (_M_write_entered())</div><div class="line"><a name="l00298"></a><span class="lineno"> 298</span>  {</div><div class="line"><a name="l00299"></a><span class="lineno"> 299</span>  // Wake the queued writer if there are no more readers.</div><div class="line"><a name="l00300"></a><span class="lineno"> 300</span>  if (_M_readers() == 0)</div><div class="line"><a name="l00301"></a><span class="lineno"> 301</span>  _M_gate2.notify_one();</div><div class="line"><a name="l00302"></a><span class="lineno"> 302</span>  // No need to notify gate1 because we give priority to the queued</div><div class="line"><a name="l00303"></a><span class="lineno"> 303</span>  // writer, and that writer will eventually notify gate1 after it</div><div class="line"><a name="l00304"></a><span class="lineno"> 304</span>  // clears the write-entered flag.</div><div class="line"><a name="l00305"></a><span class="lineno"> 305</span>  }</div><div class="line"><a name="l00306"></a><span class="lineno"> 306</span>  else</div><div class="line"><a name="l00307"></a><span class="lineno"> 307</span>  {</div><div class="line"><a name="l00308"></a><span class="lineno"> 308</span>  // Wake any thread that was blocked on reader overflow.</div><div class="line"><a name="l00309"></a><span class="lineno"> 309</span>  if (__prev == _S_max_readers)</div><div class="line"><a name="l00310"></a><span class="lineno"> 310</span>  _M_gate1.notify_one();</div><div class="line"><a name="l00311"></a><span class="lineno"> 311</span>  }</div><div class="line"><a name="l00312"></a><span class="lineno"> 312</span>  }</div><div class="line"><a name="l00313"></a><span class="lineno"> 313</span>  };</div><div class="line"><a name="l00314"></a><span class="lineno"> 314</span> #endif</div><div class="line"><a name="l00315"></a><span class="lineno"> 315</span> </div><div class="line"><a name="l00316"></a><span class="lineno"> 316</span> #if __cplusplus > 201402L</div><div class="line"><a name="l00317"></a><span class="lineno"> 317</span>  /// The standard shared mutex type.</div><div class="line"><a name="l00318"></a><span class="lineno"> 318</span>  class shared_mutex</div><div class="line"><a name="l00319"></a><span class="lineno"> 319</span>  {</div><div class="line"><a name="l00320"></a><span class="lineno"> 320</span>  public:</div><div class="line"><a name="l00321"></a><span class="lineno"> 321</span>  shared_mutex() = default;</div><div class="line"><a name="l00322"></a><span class="lineno"> 322</span>  ~shared_mutex() = default;</div><div class="line"><a name="l00323"></a><span class="lineno"> 323</span> </div><div class="line"><a name="l00324"></a><span class="lineno"> 324</span>  shared_mutex(const shared_mutex&) = delete;</div><div class="line"><a name="l00325"></a><span class="lineno"> 325</span>  shared_mutex& operator=(const shared_mutex&) = delete;</div><div class="line"><a name="l00326"></a><span class="lineno"> 326</span> </div><div class="line"><a name="l00327"></a><span class="lineno"> 327</span>  // Exclusive ownership</div><div class="line"><a name="l00328"></a><span class="lineno"> 328</span> </div><div class="line"><a name="l00329"></a><span class="lineno"> 329</span>  void lock() { _M_impl.lock(); }</div><div class="line"><a name="l00330"></a><span class="lineno"> 330</span>  bool try_lock() { return _M_impl.try_lock(); }</div><div class="line"><a name="l00331"></a><span class="lineno"> 331</span>  void unlock() { _M_impl.unlock(); }</div><div class="line"><a name="l00332"></a><span class="lineno"> 332</span> </div><div class="line"><a name="l00333"></a><span class="lineno"> 333</span>  // Shared ownership</div><div class="line"><a name="l00334"></a><span class="lineno"> 334</span> </div><div class="line"><a name="l00335"></a><span class="lineno"> 335</span>  void lock_shared() { _M_impl.lock_shared(); }</div><div class="line"><a name="l00336"></a><span class="lineno"> 336</span>  bool try_lock_shared() { return _M_impl.try_lock_shared(); }</div><div class="line"><a name="l00337"></a><span class="lineno"> 337</span>  void unlock_shared() { _M_impl.unlock_shared(); }</div><div class="line"><a name="l00338"></a><span class="lineno"> 338</span> </div><div class="line"><a name="l00339"></a><span class="lineno"> 339</span> #if _GLIBCXX_USE_PTHREAD_RWLOCK_T</div><div class="line"><a name="l00340"></a><span class="lineno"> 340</span>  typedef void* native_handle_type;</div><div class="line"><a name="l00341"></a><span class="lineno"> 341</span>  native_handle_type native_handle() { return _M_impl.native_handle(); }</div><div class="line"><a name="l00342"></a><span class="lineno"> 342</span> </div><div class="line"><a name="l00343"></a><span class="lineno"> 343</span>  private:</div><div class="line"><a name="l00344"></a><span class="lineno"> 344</span>  __shared_mutex_pthread _M_impl;</div><div class="line"><a name="l00345"></a><span class="lineno"> 345</span> #else</div><div class="line"><a name="l00346"></a><span class="lineno"> 346</span>  private:</div><div class="line"><a name="l00347"></a><span class="lineno"> 347</span>  __shared_mutex_cv _M_impl;</div><div class="line"><a name="l00348"></a><span class="lineno"> 348</span> #endif</div><div class="line"><a name="l00349"></a><span class="lineno"> 349</span>  };</div><div class="line"><a name="l00350"></a><span class="lineno"> 350</span> #endif // C++17</div><div class="line"><a name="l00351"></a><span class="lineno"> 351</span> </div><div class="line"><a name="l00352"></a><span class="lineno"> 352</span> #if _GLIBCXX_USE_PTHREAD_RWLOCK_T && _GTHREAD_USE_MUTEX_TIMEDLOCK</div><div class="line"><a name="l00353"></a><span class="lineno"> 353</span>  using __shared_timed_mutex_base = __shared_mutex_pthread;</div><div class="line"><a name="l00354"></a><span class="lineno"> 354</span> #else</div><div class="line"><a name="l00355"></a><span class="lineno"> 355</span>  using __shared_timed_mutex_base = __shared_mutex_cv;</div><div class="line"><a name="l00356"></a><span class="lineno"> 356</span> #endif</div><div class="line"><a name="l00357"></a><span class="lineno"> 357</span> </div><div class="line"><a name="l00358"></a><span class="lineno"> 358</span>  /// The standard shared timed mutex type.</div><div class="line"><a name="l00359"></a><span class="lineno"> 359</span>  class shared_timed_mutex</div><div class="line"><a name="l00360"></a><span class="lineno"> 360</span>  : private __shared_timed_mutex_base</div><div class="line"><a name="l00361"></a><span class="lineno"> 361</span>  {</div><div class="line"><a name="l00362"></a><span class="lineno"> 362</span>  using _Base = __shared_timed_mutex_base;</div><div class="line"><a name="l00363"></a><span class="lineno"> 363</span> </div><div class="line"><a name="l00364"></a><span class="lineno"> 364</span>  // Must use the same clock as condition_variable for __shared_mutex_cv.</div><div class="line"><a name="l00365"></a><span class="lineno"> 365</span>  typedef chrono::system_clock __clock_t;</div><div class="line"><a name="l00366"></a><span class="lineno"> 366</span> </div><div class="line"><a name="l00367"></a><span class="lineno"> 367</span>  public:</div><div class="line"><a name="l00368"></a><span class="lineno"> 368</span>  shared_timed_mutex() = default;</div><div class="line"><a name="l00369"></a><span class="lineno"> 369</span>  ~shared_timed_mutex() = default;</div><div class="line"><a name="l00370"></a><span class="lineno"> 370</span> </div><div class="line"><a name="l00371"></a><span class="lineno"> 371</span>  shared_timed_mutex(const shared_timed_mutex&) = delete;</div><div class="line"><a name="l00372"></a><span class="lineno"> 372</span>  shared_timed_mutex& operator=(const shared_timed_mutex&) = delete;</div><div class="line"><a name="l00373"></a><span class="lineno"> 373</span> </div><div class="line"><a name="l00374"></a><span class="lineno"> 374</span>  // Exclusive ownership</div><div class="line"><a name="l00375"></a><span class="lineno"> 375</span> </div><div class="line"><a name="l00376"></a><span class="lineno"> 376</span>  void lock() { _Base::lock(); }</div><div class="line"><a name="l00377"></a><span class="lineno"> 377</span>  bool try_lock() { return _Base::try_lock(); }</div><div class="line"><a name="l00378"></a><span class="lineno"> 378</span>  void unlock() { _Base::unlock(); }</div><div class="line"><a name="l00379"></a><span class="lineno"> 379</span> </div><div class="line"><a name="l00380"></a><span class="lineno"> 380</span>  template<typename _Rep, typename _Period></div><div class="line"><a name="l00381"></a><span class="lineno"> 381</span>  bool</div><div class="line"><a name="l00382"></a><span class="lineno"> 382</span>  try_lock_for(const chrono::duration<_Rep, _Period>& __rel_time)</div><div class="line"><a name="l00383"></a><span class="lineno"> 383</span>  {</div><div class="line"><a name="l00384"></a><span class="lineno"> 384</span>  return try_lock_until(__clock_t::now() + __rel_time);</div><div class="line"><a name="l00385"></a><span class="lineno"> 385</span>  }</div><div class="line"><a name="l00386"></a><span class="lineno"> 386</span> </div><div class="line"><a name="l00387"></a><span class="lineno"> 387</span>  // Shared ownership</div><div class="line"><a name="l00388"></a><span class="lineno"> 388</span> </div><div class="line"><a name="l00389"></a><span class="lineno"> 389</span>  void lock_shared() { _Base::lock_shared(); }</div><div class="line"><a name="l00390"></a><span class="lineno"> 390</span>  bool try_lock_shared() { return _Base::try_lock_shared(); }</div><div class="line"><a name="l00391"></a><span class="lineno"> 391</span>  void unlock_shared() { _Base::unlock_shared(); }</div><div class="line"><a name="l00392"></a><span class="lineno"> 392</span> </div><div class="line"><a name="l00393"></a><span class="lineno"> 393</span>  template<typename _Rep, typename _Period></div><div class="line"><a name="l00394"></a><span class="lineno"> 394</span>  bool</div><div class="line"><a name="l00395"></a><span class="lineno"> 395</span>  try_lock_shared_for(const chrono::duration<_Rep, _Period>& __rel_time)</div><div class="line"><a name="l00396"></a><span class="lineno"> 396</span>  {</div><div class="line"><a name="l00397"></a><span class="lineno"> 397</span>  return try_lock_shared_until(__clock_t::now() + __rel_time);</div><div class="line"><a name="l00398"></a><span class="lineno"> 398</span>  }</div><div class="line"><a name="l00399"></a><span class="lineno"> 399</span> </div><div class="line"><a name="l00400"></a><span class="lineno"> 400</span> #if _GLIBCXX_USE_PTHREAD_RWLOCK_T && _GTHREAD_USE_MUTEX_TIMEDLOCK</div><div class="line"><a name="l00401"></a><span class="lineno"> 401</span> </div><div class="line"><a name="l00402"></a><span class="lineno"> 402</span>  // Exclusive ownership</div><div class="line"><a name="l00403"></a><span class="lineno"> 403</span> </div><div class="line"><a name="l00404"></a><span class="lineno"> 404</span>  template<typename _Duration></div><div class="line"><a name="l00405"></a><span class="lineno"> 405</span>  bool</div><div class="line"><a name="l00406"></a><span class="lineno"> 406</span>  try_lock_until(const chrono::time_point<__clock_t, _Duration>& __atime)</div><div class="line"><a name="l00407"></a><span class="lineno"> 407</span>  {</div><div class="line"><a name="l00408"></a><span class="lineno"> 408</span>  auto __s = chrono::time_point_cast<chrono::seconds>(__atime);</div><div class="line"><a name="l00409"></a><span class="lineno"> 409</span>  auto __ns = chrono::duration_cast<chrono::nanoseconds>(__atime - __s);</div><div class="line"><a name="l00410"></a><span class="lineno"> 410</span> </div><div class="line"><a name="l00411"></a><span class="lineno"> 411</span>  __gthread_time_t __ts =</div><div class="line"><a name="l00412"></a><span class="lineno"> 412</span>  {</div><div class="line"><a name="l00413"></a><span class="lineno"> 413</span>  static_cast<std::time_t>(__s.time_since_epoch().count()),</div><div class="line"><a name="l00414"></a><span class="lineno"> 414</span>  static_cast<long>(__ns.count())</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> </div><div class="line"><a name="l00417"></a><span class="lineno"> 417</span>  int __ret = pthread_rwlock_timedwrlock(&_M_rwlock, &__ts);</div><div class="line"><a name="l00418"></a><span class="lineno"> 418</span>  // On self-deadlock, we just fail to acquire the lock. Technically,</div><div class="line"><a name="l00419"></a><span class="lineno"> 419</span>  // the program violated the precondition.</div><div class="line"><a name="l00420"></a><span class="lineno"> 420</span>  if (__ret == ETIMEDOUT || __ret == EDEADLK)</div><div class="line"><a name="l00421"></a><span class="lineno"> 421</span>  return false;</div><div class="line"><a name="l00422"></a><span class="lineno"> 422</span>  // Errors not handled: EINVAL</div><div class="line"><a name="l00423"></a><span class="lineno"> 423</span>  __glibcxx_assert(__ret == 0);</div><div class="line"><a name="l00424"></a><span class="lineno"> 424</span>  return true;</div><div class="line"><a name="l00425"></a><span class="lineno"> 425</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>  template<typename _Clock, typename _Duration></div><div class="line"><a name="l00428"></a><span class="lineno"> 428</span>  bool</div><div class="line"><a name="l00429"></a><span class="lineno"> 429</span>  try_lock_until(const chrono::time_point<_Clock, _Duration>& __abs_time)</div><div class="line"><a name="l00430"></a><span class="lineno"> 430</span>  {</div><div class="line"><a name="l00431"></a><span class="lineno"> 431</span>  // DR 887 - Sync unknown clock to known clock.</div><div class="line"><a name="l00432"></a><span class="lineno"> 432</span>  const typename _Clock::time_point __c_entry = _Clock::now();</div><div class="line"><a name="l00433"></a><span class="lineno"> 433</span>  const __clock_t::time_point __s_entry = __clock_t::now();</div><div class="line"><a name="l00434"></a><span class="lineno"> 434</span>  const auto __delta = __abs_time - __c_entry;</div><div class="line"><a name="l00435"></a><span class="lineno"> 435</span>  const auto __s_atime = __s_entry + __delta;</div><div class="line"><a name="l00436"></a><span class="lineno"> 436</span>  return try_lock_until(__s_atime);</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> </div><div class="line"><a name="l00439"></a><span class="lineno"> 439</span>  // Shared ownership</div><div class="line"><a name="l00440"></a><span class="lineno"> 440</span> </div><div class="line"><a name="l00441"></a><span class="lineno"> 441</span>  template<typename _Duration></div><div class="line"><a name="l00442"></a><span class="lineno"> 442</span>  bool</div><div class="line"><a name="l00443"></a><span class="lineno"> 443</span>  try_lock_shared_until(const chrono::time_point<__clock_t,</div><div class="line"><a name="l00444"></a><span class="lineno"> 444</span>  _Duration>& __atime)</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>  auto __s = chrono::time_point_cast<chrono::seconds>(__atime);</div><div class="line"><a name="l00447"></a><span class="lineno"> 447</span>  auto __ns = chrono::duration_cast<chrono::nanoseconds>(__atime - __s);</div><div class="line"><a name="l00448"></a><span class="lineno"> 448</span> </div><div class="line"><a name="l00449"></a><span class="lineno"> 449</span>  __gthread_time_t __ts =</div><div class="line"><a name="l00450"></a><span class="lineno"> 450</span>  {</div><div class="line"><a name="l00451"></a><span class="lineno"> 451</span>  static_cast<std::time_t>(__s.time_since_epoch().count()),</div><div class="line"><a name="l00452"></a><span class="lineno"> 452</span>  static_cast<long>(__ns.count())</div><div class="line"><a name="l00453"></a><span class="lineno"> 453</span>  };</div><div class="line"><a name="l00454"></a><span class="lineno"> 454</span> </div><div class="line"><a name="l00455"></a><span class="lineno"> 455</span>  int __ret;</div><div class="line"><a name="l00456"></a><span class="lineno"> 456</span>  // Unlike for lock(), we are not allowed to throw an exception so if</div><div class="line"><a name="l00457"></a><span class="lineno"> 457</span>  // the maximum number of read locks has been exceeded, or we would</div><div class="line"><a name="l00458"></a><span class="lineno"> 458</span>  // deadlock, we just try to acquire the lock again (and will time out</div><div class="line"><a name="l00459"></a><span class="lineno"> 459</span>  // eventually).</div><div class="line"><a name="l00460"></a><span class="lineno"> 460</span>  // In cases where we would exceed the maximum number of read locks</div><div class="line"><a name="l00461"></a><span class="lineno"> 461</span>  // throughout the whole time until the timeout, we will fail to</div><div class="line"><a name="l00462"></a><span class="lineno"> 462</span>  // acquire the lock even if it would be logically free; however, this</div><div class="line"><a name="l00463"></a><span class="lineno"> 463</span>  // is allowed by the standard, and we made a "strong effort"</div><div class="line"><a name="l00464"></a><span class="lineno"> 464</span>  // (see C++14 30.4.1.4p26).</div><div class="line"><a name="l00465"></a><span class="lineno"> 465</span>  // For cases where the implementation detects a deadlock we</div><div class="line"><a name="l00466"></a><span class="lineno"> 466</span>  // intentionally block and timeout so that an early return isn't</div><div class="line"><a name="l00467"></a><span class="lineno"> 467</span>  // mistaken for a spurious failure, which might help users realise</div><div class="line"><a name="l00468"></a><span class="lineno"> 468</span>  // there is a deadlock.</div><div class="line"><a name="l00469"></a><span class="lineno"> 469</span>  do</div><div class="line"><a name="l00470"></a><span class="lineno"> 470</span>  __ret = pthread_rwlock_timedrdlock(&_M_rwlock, &__ts);</div><div class="line"><a name="l00471"></a><span class="lineno"> 471</span>  while (__ret == EAGAIN || __ret == EDEADLK);</div><div class="line"><a name="l00472"></a><span class="lineno"> 472</span>  if (__ret == ETIMEDOUT)</div><div class="line"><a name="l00473"></a><span class="lineno"> 473</span>  return false;</div><div class="line"><a name="l00474"></a><span class="lineno"> 474</span>  // Errors not handled: EINVAL</div><div class="line"><a name="l00475"></a><span class="lineno"> 475</span>  __glibcxx_assert(__ret == 0);</div><div class="line"><a name="l00476"></a><span class="lineno"> 476</span>  return true;</div><div class="line"><a name="l00477"></a><span class="lineno"> 477</span>  }</div><div class="line"><a name="l00478"></a><span class="lineno"> 478</span> </div><div class="line"><a name="l00479"></a><span class="lineno"> 479</span>  template<typename _Clock, typename _Duration></div><div class="line"><a name="l00480"></a><span class="lineno"> 480</span>  bool</div><div class="line"><a name="l00481"></a><span class="lineno"> 481</span>  try_lock_shared_until(const chrono::time_point<_Clock,</div><div class="line"><a name="l00482"></a><span class="lineno"> 482</span>  _Duration>& __abs_time)</div><div class="line"><a name="l00483"></a><span class="lineno"> 483</span>  {</div><div class="line"><a name="l00484"></a><span class="lineno"> 484</span>  // DR 887 - Sync unknown clock to known clock.</div><div class="line"><a name="l00485"></a><span class="lineno"> 485</span>  const typename _Clock::time_point __c_entry = _Clock::now();</div><div class="line"><a name="l00486"></a><span class="lineno"> 486</span>  const __clock_t::time_point __s_entry = __clock_t::now();</div><div class="line"><a name="l00487"></a><span class="lineno"> 487</span>  const auto __delta = __abs_time - __c_entry;</div><div class="line"><a name="l00488"></a><span class="lineno"> 488</span>  const auto __s_atime = __s_entry + __delta;</div><div class="line"><a name="l00489"></a><span class="lineno"> 489</span>  return try_lock_shared_until(__s_atime);</div><div class="line"><a name="l00490"></a><span class="lineno"> 490</span>  }</div><div class="line"><a name="l00491"></a><span class="lineno"> 491</span> </div><div class="line"><a name="l00492"></a><span class="lineno"> 492</span> #else // ! (_GLIBCXX_USE_PTHREAD_RWLOCK_T && _GTHREAD_USE_MUTEX_TIMEDLOCK)</div><div class="line"><a name="l00493"></a><span class="lineno"> 493</span> </div><div class="line"><a name="l00494"></a><span class="lineno"> 494</span>  // Exclusive ownership</div><div class="line"><a name="l00495"></a><span class="lineno"> 495</span> </div><div class="line"><a name="l00496"></a><span class="lineno"> 496</span>  template<typename _Clock, typename _Duration></div><div class="line"><a name="l00497"></a><span class="lineno"> 497</span>  bool</div><div class="line"><a name="l00498"></a><span class="lineno"> 498</span>  try_lock_until(const chrono::time_point<_Clock, _Duration>& __abs_time)</div><div class="line"><a name="l00499"></a><span class="lineno"> 499</span>  {</div><div class="line"><a name="l00500"></a><span class="lineno"> 500</span>  unique_lock<mutex> __lk(_M_mut);</div><div class="line"><a name="l00501"></a><span class="lineno"> 501</span>  if (!_M_gate1.wait_until(__lk, __abs_time,</div><div class="line"><a name="l00502"></a><span class="lineno"> 502</span>  [=]{ return !_M_write_entered(); }))</div><div class="line"><a name="l00503"></a><span class="lineno"> 503</span>  {</div><div class="line"><a name="l00504"></a><span class="lineno"> 504</span>  return false;</div><div class="line"><a name="l00505"></a><span class="lineno"> 505</span>  }</div><div class="line"><a name="l00506"></a><span class="lineno"> 506</span>  _M_state |= _S_write_entered;</div><div class="line"><a name="l00507"></a><span class="lineno"> 507</span>  if (!_M_gate2.wait_until(__lk, __abs_time,</div><div class="line"><a name="l00508"></a><span class="lineno"> 508</span>  [=]{ return _M_readers() == 0; }))</div><div class="line"><a name="l00509"></a><span class="lineno"> 509</span>  {</div><div class="line"><a name="l00510"></a><span class="lineno"> 510</span>  _M_state ^= _S_write_entered;</div><div class="line"><a name="l00511"></a><span class="lineno"> 511</span>  // Wake all threads blocked while the write-entered flag was set.</div><div class="line"><a name="l00512"></a><span class="lineno"> 512</span>  _M_gate1.notify_all();</div><div class="line"><a name="l00513"></a><span class="lineno"> 513</span>  return false;</div><div class="line"><a name="l00514"></a><span class="lineno"> 514</span>  }</div><div class="line"><a name="l00515"></a><span class="lineno"> 515</span>  return true;</div><div class="line"><a name="l00516"></a><span class="lineno"> 516</span>  }</div><div class="line"><a name="l00517"></a><span class="lineno"> 517</span> </div><div class="line"><a name="l00518"></a><span class="lineno"> 518</span>  // Shared ownership</div><div class="line"><a name="l00519"></a><span class="lineno"> 519</span> </div><div class="line"><a name="l00520"></a><span class="lineno"> 520</span>  template <typename _Clock, typename _Duration></div><div class="line"><a name="l00521"></a><span class="lineno"> 521</span>  bool</div><div class="line"><a name="l00522"></a><span class="lineno"> 522</span>  try_lock_shared_until(const chrono::time_point<_Clock,</div><div class="line"><a name="l00523"></a><span class="lineno"> 523</span>  _Duration>& __abs_time)</div><div class="line"><a name="l00524"></a><span class="lineno"> 524</span>  {</div><div class="line"><a name="l00525"></a><span class="lineno"> 525</span>  unique_lock<mutex> __lk(_M_mut);</div><div class="line"><a name="l00526"></a><span class="lineno"> 526</span>  if (!_M_gate1.wait_until(__lk, __abs_time,</div><div class="line"><a name="l00527"></a><span class="lineno"> 527</span>  [=]{ return _M_state < _S_max_readers; }))</div><div class="line"><a name="l00528"></a><span class="lineno"> 528</span>  {</div><div class="line"><a name="l00529"></a><span class="lineno"> 529</span>  return false;</div><div class="line"><a name="l00530"></a><span class="lineno"> 530</span>  }</div><div class="line"><a name="l00531"></a><span class="lineno"> 531</span>  ++_M_state;</div><div class="line"><a name="l00532"></a><span class="lineno"> 532</span>  return true;</div><div class="line"><a name="l00533"></a><span class="lineno"> 533</span>  }</div><div class="line"><a name="l00534"></a><span class="lineno"> 534</span> </div><div class="line"><a name="l00535"></a><span class="lineno"> 535</span> #endif // _GLIBCXX_USE_PTHREAD_RWLOCK_T && _GTHREAD_USE_MUTEX_TIMEDLOCK</div><div class="line"><a name="l00536"></a><span class="lineno"> 536</span>  };</div><div class="line"><a name="l00537"></a><span class="lineno"> 537</span> #endif // _GLIBCXX_HAS_GTHREADS</div><div class="line"><a name="l00538"></a><span class="lineno"> 538</span> </div><div class="line"><a name="l00539"></a><span class="lineno"> 539</span>  /// shared_lock</div><div class="line"><a name="l00540"></a><span class="lineno"> 540</span>  template<typename _Mutex></div><div class="line"><a name="l00541"></a><span class="lineno"> 541</span>  class shared_lock</div><div class="line"><a name="l00542"></a><span class="lineno"> 542</span>  {</div><div class="line"><a name="l00543"></a><span class="lineno"> 543</span>  public:</div><div class="line"><a name="l00544"></a><span class="lineno"> 544</span>  typedef _Mutex mutex_type;</div><div class="line"><a name="l00545"></a><span class="lineno"> 545</span> </div><div class="line"><a name="l00546"></a><span class="lineno"> 546</span>  // Shared locking</div><div class="line"><a name="l00547"></a><span class="lineno"> 547</span> </div><div class="line"><a name="l00548"></a><span class="lineno"> 548</span>  shared_lock() noexcept : _M_pm(nullptr), _M_owns(false) { }</div><div class="line"><a name="l00549"></a><span class="lineno"> 549</span> </div><div class="line"><a name="l00550"></a><span class="lineno"> 550</span>  explicit</div><div class="line"><a name="l00551"></a><span class="lineno"> 551</span>  shared_lock(mutex_type& __m)</div><div class="line"><a name="l00552"></a><span class="lineno"> 552</span>  : _M_pm(std::__addressof(__m)), _M_owns(true)</div><div class="line"><a name="l00553"></a><span class="lineno"> 553</span>  { __m.lock_shared(); }</div><div class="line"><a name="l00554"></a><span class="lineno"> 554</span> </div><div class="line"><a name="l00555"></a><span class="lineno"> 555</span>  shared_lock(mutex_type& __m, defer_lock_t) noexcept</div><div class="line"><a name="l00556"></a><span class="lineno"> 556</span>  : _M_pm(std::__addressof(__m)), _M_owns(false) { }</div><div class="line"><a name="l00557"></a><span class="lineno"> 557</span> </div><div class="line"><a name="l00558"></a><span class="lineno"> 558</span>  shared_lock(mutex_type& __m, try_to_lock_t)</div><div class="line"><a name="l00559"></a><span class="lineno"> 559</span>  : _M_pm(std::__addressof(__m)), _M_owns(__m.try_lock_shared()) { }</div><div class="line"><a name="l00560"></a><span class="lineno"> 560</span> </div><div class="line"><a name="l00561"></a><span class="lineno"> 561</span>  shared_lock(mutex_type& __m, adopt_lock_t)</div><div class="line"><a name="l00562"></a><span class="lineno"> 562</span>  : _M_pm(std::__addressof(__m)), _M_owns(true) { }</div><div class="line"><a name="l00563"></a><span class="lineno"> 563</span> </div><div class="line"><a name="l00564"></a><span class="lineno"> 564</span>  template<typename _Clock, typename _Duration></div><div class="line"><a name="l00565"></a><span class="lineno"> 565</span>  shared_lock(mutex_type& __m,</div><div class="line"><a name="l00566"></a><span class="lineno"> 566</span>  const chrono::time_point<_Clock, _Duration>& __abs_time)</div><div class="line"><a name="l00567"></a><span class="lineno"> 567</span>  : _M_pm(std::__addressof(__m)),</div><div class="line"><a name="l00568"></a><span class="lineno"> 568</span>  _M_owns(__m.try_lock_shared_until(__abs_time)) { }</div><div class="line"><a name="l00569"></a><span class="lineno"> 569</span> </div><div class="line"><a name="l00570"></a><span class="lineno"> 570</span>  template<typename _Rep, typename _Period></div><div class="line"><a name="l00571"></a><span class="lineno"> 571</span>  shared_lock(mutex_type& __m,</div><div class="line"><a name="l00572"></a><span class="lineno"> 572</span>  const chrono::duration<_Rep, _Period>& __rel_time)</div><div class="line"><a name="l00573"></a><span class="lineno"> 573</span>  : _M_pm(std::__addressof(__m)),</div><div class="line"><a name="l00574"></a><span class="lineno"> 574</span>  _M_owns(__m.try_lock_shared_for(__rel_time)) { }</div><div class="line"><a name="l00575"></a><span class="lineno"> 575</span> </div><div class="line"><a name="l00576"></a><span class="lineno"> 576</span>  ~shared_lock()</div><div class="line"><a name="l00577"></a><span class="lineno"> 577</span>  {</div><div class="line"><a name="l00578"></a><span class="lineno"> 578</span>  if (_M_owns)</div><div class="line"><a name="l00579"></a><span class="lineno"> 579</span>  _M_pm->unlock_shared();</div><div class="line"><a name="l00580"></a><span class="lineno"> 580</span>  }</div><div class="line"><a name="l00581"></a><span class="lineno"> 581</span> </div><div class="line"><a name="l00582"></a><span class="lineno"> 582</span>  shared_lock(shared_lock const&) = delete;</div><div class="line"><a name="l00583"></a><span class="lineno"> 583</span>  shared_lock& operator=(shared_lock const&) = delete;</div><div class="line"><a name="l00584"></a><span class="lineno"> 584</span> </div><div class="line"><a name="l00585"></a><span class="lineno"> 585</span>  shared_lock(shared_lock&& __sl) noexcept : shared_lock()</div><div class="line"><a name="l00586"></a><span class="lineno"> 586</span>  { swap(__sl); }</div><div class="line"><a name="l00587"></a><span class="lineno"> 587</span> </div><div class="line"><a name="l00588"></a><span class="lineno"> 588</span>  shared_lock&</div><div class="line"><a name="l00589"></a><span class="lineno"> 589</span>  operator=(shared_lock&& __sl) noexcept</div><div class="line"><a name="l00590"></a><span class="lineno"> 590</span>  {</div><div class="line"><a name="l00591"></a><span class="lineno"> 591</span>  shared_lock(std::move(__sl)).swap(*this);</div><div class="line"><a name="l00592"></a><span class="lineno"> 592</span>  return *this;</div><div class="line"><a name="l00593"></a><span class="lineno"> 593</span>  }</div><div class="line"><a name="l00594"></a><span class="lineno"> 594</span> </div><div class="line"><a name="l00595"></a><span class="lineno"> 595</span>  void</div><div class="line"><a name="l00596"></a><span class="lineno"> 596</span>  lock()</div><div class="line"><a name="l00597"></a><span class="lineno"> 597</span>  {</div><div class="line"><a name="l00598"></a><span class="lineno"> 598</span>  _M_lockable();</div><div class="line"><a name="l00599"></a><span class="lineno"> 599</span>  _M_pm->lock_shared();</div><div class="line"><a name="l00600"></a><span class="lineno"> 600</span>  _M_owns = true;</div><div class="line"><a name="l00601"></a><span class="lineno"> 601</span>  }</div><div class="line"><a name="l00602"></a><span class="lineno"> 602</span> </div><div class="line"><a name="l00603"></a><span class="lineno"> 603</span>  bool</div><div class="line"><a name="l00604"></a><span class="lineno"> 604</span>  try_lock()</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>  _M_lockable();</div><div class="line"><a name="l00607"></a><span class="lineno"> 607</span>  return _M_owns = _M_pm->try_lock_shared();</div><div class="line"><a name="l00608"></a><span class="lineno"> 608</span>  }</div><div class="line"><a name="l00609"></a><span class="lineno"> 609</span> </div><div class="line"><a name="l00610"></a><span class="lineno"> 610</span>  template<typename _Rep, typename _Period></div><div class="line"><a name="l00611"></a><span class="lineno"> 611</span>  bool</div><div class="line"><a name="l00612"></a><span class="lineno"> 612</span>  try_lock_for(const chrono::duration<_Rep, _Period>& __rel_time)</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>  _M_lockable();</div><div class="line"><a name="l00615"></a><span class="lineno"> 615</span>  return _M_owns = _M_pm->try_lock_shared_for(__rel_time);</div><div class="line"><a name="l00616"></a><span class="lineno"> 616</span>  }</div><div class="line"><a name="l00617"></a><span class="lineno"> 617</span> </div><div class="line"><a name="l00618"></a><span class="lineno"> 618</span>  template<typename _Clock, typename _Duration></div><div class="line"><a name="l00619"></a><span class="lineno"> 619</span>  bool</div><div class="line"><a name="l00620"></a><span class="lineno"> 620</span>  try_lock_until(const chrono::time_point<_Clock, _Duration>& __abs_time)</div><div class="line"><a name="l00621"></a><span class="lineno"> 621</span>  {</div><div class="line"><a name="l00622"></a><span class="lineno"> 622</span>  _M_lockable();</div><div class="line"><a name="l00623"></a><span class="lineno"> 623</span>  return _M_owns = _M_pm->try_lock_shared_until(__abs_time);</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> </div><div class="line"><a name="l00626"></a><span class="lineno"> 626</span>  void</div><div class="line"><a name="l00627"></a><span class="lineno"> 627</span>  unlock()</div><div class="line"><a name="l00628"></a><span class="lineno"> 628</span>  {</div><div class="line"><a name="l00629"></a><span class="lineno"> 629</span>  if (!_M_owns)</div><div class="line"><a name="l00630"></a><span class="lineno"> 630</span>  __throw_system_error(int(errc::resource_deadlock_would_occur));</div><div class="line"><a name="l00631"></a><span class="lineno"> 631</span>  _M_pm->unlock_shared();</div><div class="line"><a name="l00632"></a><span class="lineno"> 632</span>  _M_owns = false;</div><div class="line"><a name="l00633"></a><span class="lineno"> 633</span>  }</div><div class="line"><a name="l00634"></a><span class="lineno"> 634</span> </div><div class="line"><a name="l00635"></a><span class="lineno"> 635</span>  // Setters</div><div class="line"><a name="l00636"></a><span class="lineno"> 636</span> </div><div class="line"><a name="l00637"></a><span class="lineno"> 637</span>  void</div><div class="line"><a name="l00638"></a><span class="lineno"> 638</span>  swap(shared_lock& __u) noexcept</div><div class="line"><a name="l00639"></a><span class="lineno"> 639</span>  {</div><div class="line"><a name="l00640"></a><span class="lineno"> 640</span>  std::swap(_M_pm, __u._M_pm);</div><div class="line"><a name="l00641"></a><span class="lineno"> 641</span>  std::swap(_M_owns, __u._M_owns);</div><div class="line"><a name="l00642"></a><span class="lineno"> 642</span>  }</div><div class="line"><a name="l00643"></a><span class="lineno"> 643</span> </div><div class="line"><a name="l00644"></a><span class="lineno"> 644</span>  mutex_type*</div><div class="line"><a name="l00645"></a><span class="lineno"> 645</span>  release() noexcept</div><div class="line"><a name="l00646"></a><span class="lineno"> 646</span>  {</div><div class="line"><a name="l00647"></a><span class="lineno"> 647</span>  _M_owns = false;</div><div class="line"><a name="l00648"></a><span class="lineno"> 648</span>  return std::exchange(_M_pm, nullptr);</div><div class="line"><a name="l00649"></a><span class="lineno"> 649</span>  }</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>  // Getters</div><div class="line"><a name="l00652"></a><span class="lineno"> 652</span> </div><div class="line"><a name="l00653"></a><span class="lineno"> 653</span>  bool owns_lock() const noexcept { return _M_owns; }</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>  explicit operator bool() const noexcept { return _M_owns; }</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>  mutex_type* mutex() const noexcept { return _M_pm; }</div><div class="line"><a name="l00658"></a><span class="lineno"> 658</span> </div><div class="line"><a name="l00659"></a><span class="lineno"> 659</span>  private:</div><div class="line"><a name="l00660"></a><span class="lineno"> 660</span>  void</div><div class="line"><a name="l00661"></a><span class="lineno"> 661</span>  _M_lockable() const</div><div class="line"><a name="l00662"></a><span class="lineno"> 662</span>  {</div><div class="line"><a name="l00663"></a><span class="lineno"> 663</span>  if (_M_pm == nullptr)</div><div class="line"><a name="l00664"></a><span class="lineno"> 664</span>  __throw_system_error(int(errc::operation_not_permitted));</div><div class="line"><a name="l00665"></a><span class="lineno"> 665</span>  if (_M_owns)</div><div class="line"><a name="l00666"></a><span class="lineno"> 666</span>  __throw_system_error(int(errc::resource_deadlock_would_occur));</div><div class="line"><a name="l00667"></a><span class="lineno"> 667</span>  }</div><div class="line"><a name="l00668"></a><span class="lineno"> 668</span> </div><div class="line"><a name="l00669"></a><span class="lineno"> 669</span>  mutex_type* _M_pm;</div><div class="line"><a name="l00670"></a><span class="lineno"> 670</span>  bool _M_owns;</div><div class="line"><a name="l00671"></a><span class="lineno"> 671</span>  };</div><div class="line"><a name="l00672"></a><span class="lineno"> 672</span> </div><div class="line"><a name="l00673"></a><span class="lineno"> 673</span>  /// Swap specialization for shared_lock</div><div class="line"><a name="l00674"></a><span class="lineno"> 674</span>  template<typename _Mutex></div><div class="line"><a name="l00675"></a><span class="lineno"> 675</span>  void</div><div class="line"><a name="l00676"></a><span class="lineno"> 676</span>  swap(shared_lock<_Mutex>& __x, shared_lock<_Mutex>& __y) noexcept</div><div class="line"><a name="l00677"></a><span class="lineno"> 677</span>  { __x.swap(__y); }</div><div class="line"><a name="l00678"></a><span class="lineno"> 678</span> </div><div class="line"><a name="l00679"></a><span class="lineno"> 679</span> #endif // _GLIBCXX_USE_C99_STDINT_TR1</div><div class="line"><a name="l00680"></a><span class="lineno"> 680</span> </div><div class="line"><a name="l00681"></a><span class="lineno"> 681</span>  // @} group mutexes</div><div class="line"><a name="l00682"></a><span class="lineno"> 682</span> _GLIBCXX_END_NAMESPACE_VERSION</div><div class="line"><a name="l00683"></a><span class="lineno"> 683</span> } // namespace</div><div class="line"><a name="l00684"></a><span class="lineno"> 684</span> </div><div class="line"><a name="l00685"></a><span class="lineno"> 685</span> #endif // C++14</div><div class="line"><a name="l00686"></a><span class="lineno"> 686</span> </div><div class="line"><a name="l00687"></a><span class="lineno"> 687</span> #endif // _GLIBCXX_SHARED_MUTEX</div></div><!-- fragment --></div><!-- contents -->
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