1 | // <condition_variable> -*- C++ -*-
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2 |
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3 | // Copyright (C) 2008-2021 Free Software Foundation, Inc.
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4 | //
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5 | // This file is part of the GNU ISO C++ Library. This library is free
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6 | // software; you can redistribute it and/or modify it under the
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7 | // terms of the GNU General Public License as published by the
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8 | // Free Software Foundation; either version 3, or (at your option)
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9 | // any later version.
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10 |
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11 | // This library is distributed in the hope that it will be useful,
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12 | // but WITHOUT ANY WARRANTY; without even the implied warranty of
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13 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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14 | // GNU General Public License for more details.
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15 |
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16 | // Under Section 7 of GPL version 3, you are granted additional
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17 | // permissions described in the GCC Runtime Library Exception, version
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18 | // 3.1, as published by the Free Software Foundation.
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19 |
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20 | // You should have received a copy of the GNU General Public License and
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21 | // a copy of the GCC Runtime Library Exception along with this program;
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22 | // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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23 | // <http://www.gnu.org/licenses/>.
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24 |
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25 | /** @file include/condition_variable
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26 | * This is a Standard C++ Library header.
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27 | */
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28 |
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29 | #ifndef _GLIBCXX_CONDITION_VARIABLE
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30 | #define _GLIBCXX_CONDITION_VARIABLE 1
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31 |
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32 | #pragma GCC system_header
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33 |
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34 | #if __cplusplus < 201103L
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35 | # include <bits/c++0x_warning.h>
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36 | #else
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37 |
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38 | #include <chrono>
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39 |
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40 | #include <bits/std_mutex.h>
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41 | #include <bits/unique_lock.h>
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42 | #include <bits/alloc_traits.h>
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43 | #include <bits/shared_ptr.h>
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44 | #include <bits/cxxabi_forced.h>
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45 |
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46 | #if __cplusplus > 201703L
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47 | # include <stop_token>
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48 | #endif
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49 |
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50 | #if defined(_GLIBCXX_HAS_GTHREADS)
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51 |
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52 | namespace std _GLIBCXX_VISIBILITY(default)
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53 | {
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54 | _GLIBCXX_BEGIN_NAMESPACE_VERSION
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55 |
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56 | /**
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57 | * @defgroup condition_variables Condition Variables
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58 | * @ingroup concurrency
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59 | *
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60 | * Classes for condition_variable support.
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61 | * @{
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62 | */
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63 |
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64 | /// cv_status
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65 | enum class cv_status { no_timeout, timeout };
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66 |
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67 | /// condition_variable
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68 | class condition_variable
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69 | {
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70 | using steady_clock = chrono::steady_clock;
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71 | using system_clock = chrono::system_clock;
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72 | #ifdef _GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT
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73 | using __clock_t = steady_clock;
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74 | #else
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75 | using __clock_t = system_clock;
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76 | #endif
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77 |
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78 | __condvar _M_cond;
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79 |
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80 | public:
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81 | typedef __gthread_cond_t* native_handle_type;
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82 |
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83 | condition_variable() noexcept;
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84 | ~condition_variable() noexcept;
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85 |
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86 | condition_variable(const condition_variable&) = delete;
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87 | condition_variable& operator=(const condition_variable&) = delete;
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88 |
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89 | void
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90 | notify_one() noexcept;
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91 |
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92 | void
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93 | notify_all() noexcept;
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94 |
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95 | void
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96 | wait(unique_lock<mutex>& __lock) noexcept;
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97 |
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98 | template<typename _Predicate>
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99 | void
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100 | wait(unique_lock<mutex>& __lock, _Predicate __p)
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101 | {
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102 | while (!__p())
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103 | wait(__lock);
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104 | }
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105 |
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106 | #ifdef _GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT
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107 | template<typename _Duration>
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108 | cv_status
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109 | wait_until(unique_lock<mutex>& __lock,
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110 | const chrono::time_point<steady_clock, _Duration>& __atime)
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111 | { return __wait_until_impl(__lock, __atime); }
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112 | #endif
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113 |
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114 | template<typename _Duration>
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115 | cv_status
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116 | wait_until(unique_lock<mutex>& __lock,
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117 | const chrono::time_point<system_clock, _Duration>& __atime)
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118 | { return __wait_until_impl(__lock, __atime); }
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119 |
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120 | template<typename _Clock, typename _Duration>
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121 | cv_status
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122 | wait_until(unique_lock<mutex>& __lock,
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123 | const chrono::time_point<_Clock, _Duration>& __atime)
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124 | {
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125 | #if __cplusplus > 201703L
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126 | static_assert(chrono::is_clock_v<_Clock>);
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127 | #endif
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128 | using __s_dur = typename __clock_t::duration;
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129 | const typename _Clock::time_point __c_entry = _Clock::now();
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130 | const __clock_t::time_point __s_entry = __clock_t::now();
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131 | const auto __delta = __atime - __c_entry;
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132 | const auto __s_atime = __s_entry +
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133 | chrono::__detail::ceil<__s_dur>(__delta);
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134 |
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135 | if (__wait_until_impl(__lock, __s_atime) == cv_status::no_timeout)
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136 | return cv_status::no_timeout;
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137 | // We got a timeout when measured against __clock_t but
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138 | // we need to check against the caller-supplied clock
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139 | // to tell whether we should return a timeout.
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140 | if (_Clock::now() < __atime)
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141 | return cv_status::no_timeout;
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142 | return cv_status::timeout;
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143 | }
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144 |
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145 | template<typename _Clock, typename _Duration, typename _Predicate>
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146 | bool
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147 | wait_until(unique_lock<mutex>& __lock,
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148 | const chrono::time_point<_Clock, _Duration>& __atime,
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149 | _Predicate __p)
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150 | {
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151 | while (!__p())
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152 | if (wait_until(__lock, __atime) == cv_status::timeout)
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153 | return __p();
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154 | return true;
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155 | }
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156 |
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157 | template<typename _Rep, typename _Period>
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158 | cv_status
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159 | wait_for(unique_lock<mutex>& __lock,
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160 | const chrono::duration<_Rep, _Period>& __rtime)
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161 | {
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162 | using __dur = typename steady_clock::duration;
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163 | return wait_until(__lock,
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164 | steady_clock::now() +
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165 | chrono::__detail::ceil<__dur>(__rtime));
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166 | }
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167 |
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168 | template<typename _Rep, typename _Period, typename _Predicate>
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169 | bool
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170 | wait_for(unique_lock<mutex>& __lock,
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171 | const chrono::duration<_Rep, _Period>& __rtime,
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172 | _Predicate __p)
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173 | {
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174 | using __dur = typename steady_clock::duration;
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175 | return wait_until(__lock,
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176 | steady_clock::now() +
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177 | chrono::__detail::ceil<__dur>(__rtime),
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178 | std::move(__p));
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179 | }
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180 |
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181 | native_handle_type
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182 | native_handle()
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183 | { return _M_cond.native_handle(); }
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184 |
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185 | private:
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186 | #ifdef _GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT
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187 | template<typename _Dur>
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188 | cv_status
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189 | __wait_until_impl(unique_lock<mutex>& __lock,
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190 | const chrono::time_point<steady_clock, _Dur>& __atime)
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191 | {
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192 | auto __s = chrono::time_point_cast<chrono::seconds>(__atime);
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193 | auto __ns = chrono::duration_cast<chrono::nanoseconds>(__atime - __s);
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194 |
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195 | __gthread_time_t __ts =
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196 | {
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197 | static_cast<std::time_t>(__s.time_since_epoch().count()),
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198 | static_cast<long>(__ns.count())
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199 | };
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200 |
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201 | _M_cond.wait_until(*__lock.mutex(), CLOCK_MONOTONIC, __ts);
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202 |
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203 | return (steady_clock::now() < __atime
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204 | ? cv_status::no_timeout : cv_status::timeout);
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205 | }
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206 | #endif
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207 |
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208 | template<typename _Dur>
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209 | cv_status
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210 | __wait_until_impl(unique_lock<mutex>& __lock,
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211 | const chrono::time_point<system_clock, _Dur>& __atime)
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212 | {
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213 | auto __s = chrono::time_point_cast<chrono::seconds>(__atime);
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214 | auto __ns = chrono::duration_cast<chrono::nanoseconds>(__atime - __s);
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215 |
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216 | __gthread_time_t __ts =
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217 | {
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218 | static_cast<std::time_t>(__s.time_since_epoch().count()),
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219 | static_cast<long>(__ns.count())
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220 | };
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221 |
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222 | _M_cond.wait_until(*__lock.mutex(), __ts);
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223 |
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224 | return (system_clock::now() < __atime
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225 | ? cv_status::no_timeout : cv_status::timeout);
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226 | }
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227 | };
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228 |
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229 | void
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230 | notify_all_at_thread_exit(condition_variable&, unique_lock<mutex>);
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231 |
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232 | struct __at_thread_exit_elt
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233 | {
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234 | __at_thread_exit_elt* _M_next;
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235 | void (*_M_cb)(void*);
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236 | };
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237 |
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238 | inline namespace _V2 {
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239 |
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240 | /// condition_variable_any
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241 | // Like above, but mutex is not required to have try_lock.
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242 | class condition_variable_any
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243 | {
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244 | #ifdef _GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT
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245 | using __clock_t = chrono::steady_clock;
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246 | #else
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247 | using __clock_t = chrono::system_clock;
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248 | #endif
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249 | condition_variable _M_cond;
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250 | shared_ptr<mutex> _M_mutex;
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251 |
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252 | // scoped unlock - unlocks in ctor, re-locks in dtor
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253 | template<typename _Lock>
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254 | struct _Unlock
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255 | {
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256 | explicit _Unlock(_Lock& __lk) : _M_lock(__lk) { __lk.unlock(); }
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257 |
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258 | #pragma GCC diagnostic push
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259 | #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
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260 | ~_Unlock() noexcept(false)
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261 | {
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262 | if (uncaught_exception())
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263 | {
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264 | __try
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265 | { _M_lock.lock(); }
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266 | __catch(const __cxxabiv1::__forced_unwind&)
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267 | { __throw_exception_again; }
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268 | __catch(...)
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269 | { }
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270 | }
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271 | else
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272 | _M_lock.lock();
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273 | }
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274 | #pragma GCC diagnostic pop
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275 |
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276 | _Unlock(const _Unlock&) = delete;
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277 | _Unlock& operator=(const _Unlock&) = delete;
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278 |
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279 | _Lock& _M_lock;
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280 | };
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281 |
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282 | public:
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283 | condition_variable_any() : _M_mutex(std::make_shared<mutex>()) { }
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284 | ~condition_variable_any() = default;
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285 |
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286 | condition_variable_any(const condition_variable_any&) = delete;
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287 | condition_variable_any& operator=(const condition_variable_any&) = delete;
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288 |
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289 | void
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290 | notify_one() noexcept
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291 | {
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292 | lock_guard<mutex> __lock(*_M_mutex);
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293 | _M_cond.notify_one();
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294 | }
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295 |
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296 | void
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297 | notify_all() noexcept
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298 | {
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299 | lock_guard<mutex> __lock(*_M_mutex);
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300 | _M_cond.notify_all();
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301 | }
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302 |
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303 | template<typename _Lock>
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304 | void
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305 | wait(_Lock& __lock)
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306 | {
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307 | shared_ptr<mutex> __mutex = _M_mutex;
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308 | unique_lock<mutex> __my_lock(*__mutex);
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309 | _Unlock<_Lock> __unlock(__lock);
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310 | // *__mutex must be unlocked before re-locking __lock so move
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311 | // ownership of *__mutex lock to an object with shorter lifetime.
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312 | unique_lock<mutex> __my_lock2(std::move(__my_lock));
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313 | _M_cond.wait(__my_lock2);
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314 | }
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315 |
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316 |
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317 | template<typename _Lock, typename _Predicate>
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318 | void
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319 | wait(_Lock& __lock, _Predicate __p)
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320 | {
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321 | while (!__p())
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322 | wait(__lock);
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323 | }
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324 |
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325 | template<typename _Lock, typename _Clock, typename _Duration>
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326 | cv_status
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327 | wait_until(_Lock& __lock,
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328 | const chrono::time_point<_Clock, _Duration>& __atime)
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329 | {
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330 | shared_ptr<mutex> __mutex = _M_mutex;
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331 | unique_lock<mutex> __my_lock(*__mutex);
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332 | _Unlock<_Lock> __unlock(__lock);
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333 | // *__mutex must be unlocked before re-locking __lock so move
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334 | // ownership of *__mutex lock to an object with shorter lifetime.
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335 | unique_lock<mutex> __my_lock2(std::move(__my_lock));
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336 | return _M_cond.wait_until(__my_lock2, __atime);
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337 | }
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338 |
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339 | template<typename _Lock, typename _Clock,
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340 | typename _Duration, typename _Predicate>
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341 | bool
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342 | wait_until(_Lock& __lock,
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343 | const chrono::time_point<_Clock, _Duration>& __atime,
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344 | _Predicate __p)
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345 | {
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346 | while (!__p())
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347 | if (wait_until(__lock, __atime) == cv_status::timeout)
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348 | return __p();
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349 | return true;
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350 | }
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351 |
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352 | template<typename _Lock, typename _Rep, typename _Period>
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353 | cv_status
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354 | wait_for(_Lock& __lock, const chrono::duration<_Rep, _Period>& __rtime)
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355 | { return wait_until(__lock, __clock_t::now() + __rtime); }
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356 |
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357 | template<typename _Lock, typename _Rep,
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358 | typename _Period, typename _Predicate>
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359 | bool
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360 | wait_for(_Lock& __lock,
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361 | const chrono::duration<_Rep, _Period>& __rtime, _Predicate __p)
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362 | { return wait_until(__lock, __clock_t::now() + __rtime, std::move(__p)); }
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363 |
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364 | #ifdef __cpp_lib_jthread
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365 | template <class _Lock, class _Predicate>
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366 | bool wait(_Lock& __lock,
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367 | stop_token __stoken,
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368 | _Predicate __p)
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369 | {
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370 | if (__stoken.stop_requested())
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371 | {
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372 | return __p();
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373 | }
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374 |
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375 | std::stop_callback __cb(__stoken, [this] { notify_all(); });
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376 | shared_ptr<mutex> __mutex = _M_mutex;
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377 | while (!__p())
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378 | {
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379 | unique_lock<mutex> __my_lock(*__mutex);
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380 | if (__stoken.stop_requested())
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381 | {
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382 | return false;
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383 | }
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384 | // *__mutex must be unlocked before re-locking __lock so move
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385 | // ownership of *__mutex lock to an object with shorter lifetime.
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386 | _Unlock<_Lock> __unlock(__lock);
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387 | unique_lock<mutex> __my_lock2(std::move(__my_lock));
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388 | _M_cond.wait(__my_lock2);
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389 | }
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390 | return true;
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391 | }
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392 |
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393 | template <class _Lock, class _Clock, class _Duration, class _Predicate>
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394 | bool wait_until(_Lock& __lock,
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395 | stop_token __stoken,
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396 | const chrono::time_point<_Clock, _Duration>& __abs_time,
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397 | _Predicate __p)
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398 | {
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399 | if (__stoken.stop_requested())
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400 | {
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401 | return __p();
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402 | }
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403 |
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404 | std::stop_callback __cb(__stoken, [this] { notify_all(); });
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405 | shared_ptr<mutex> __mutex = _M_mutex;
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406 | while (!__p())
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407 | {
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408 | bool __stop;
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409 | {
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410 | unique_lock<mutex> __my_lock(*__mutex);
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411 | if (__stoken.stop_requested())
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412 | {
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413 | return false;
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414 | }
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415 | _Unlock<_Lock> __u(__lock);
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416 | unique_lock<mutex> __my_lock2(std::move(__my_lock));
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417 | const auto __status = _M_cond.wait_until(__my_lock2, __abs_time);
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418 | __stop = (__status == std::cv_status::timeout) || __stoken.stop_requested();
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419 | }
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420 | if (__stop)
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421 | {
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422 | return __p();
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423 | }
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424 | }
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425 | return true;
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426 | }
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427 |
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428 | template <class _Lock, class _Rep, class _Period, class _Predicate>
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429 | bool wait_for(_Lock& __lock,
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430 | stop_token __stoken,
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431 | const chrono::duration<_Rep, _Period>& __rel_time,
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432 | _Predicate __p)
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433 | {
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434 | auto __abst = std::chrono::steady_clock::now() + __rel_time;
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435 | return wait_until(__lock,
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436 | std::move(__stoken),
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437 | __abst,
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438 | std::move(__p));
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439 | }
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440 | #endif
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441 | };
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442 |
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443 | } // end inline namespace
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444 |
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445 | /// @} group condition_variables
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446 | _GLIBCXX_END_NAMESPACE_VERSION
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447 | } // namespace
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448 |
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449 | #endif // _GLIBCXX_HAS_GTHREADS
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450 | #endif // C++11
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451 | #endif // _GLIBCXX_CONDITION_VARIABLE
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