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The C and C++ Include Header Files
/usr/include/c++/13/condition_variable
$ cat -n /usr/include/c++/13/condition_variable 1 // <condition_variable> -*- C++ -*- 2 3 // Copyright (C) 2008-2023 Free Software Foundation, Inc. 4 // 5 // This file is part of the GNU ISO C++ Library. This library is free 6 // software; you can redistribute it and/or modify it under the 7 // terms of the GNU General Public License as published by the 8 // Free Software Foundation; either version 3, or (at your option) 9 // any later version. 10 11 // This library is distributed in the hope that it will be useful, 12 // but WITHOUT ANY WARRANTY; without even the implied warranty of 13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 // GNU General Public License for more details. 15 16 // Under Section 7 of GPL version 3, you are granted additional 17 // permissions described in the GCC Runtime Library Exception, version 18 // 3.1, as published by the Free Software Foundation. 19 20 // You should have received a copy of the GNU General Public License and 21 // a copy of the GCC Runtime Library Exception along with this program; 22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 23 // <http://www.gnu.org/licenses/>. 24 25 /** @file include/condition_variable 26 * This is a Standard C++ Library header. 27 */ 28 29 #ifndef _GLIBCXX_CONDITION_VARIABLE 30 #define _GLIBCXX_CONDITION_VARIABLE 1 31 32 #pragma GCC system_header 33 34 #include <bits/requires_hosted.h> // threading primitive 35 36 #if __cplusplus < 201103L 37 # include <bits/c++0x_warning.h> 38 #else 39 40 #include <bits/chrono.h> 41 #include <bits/error_constants.h> 42 #include <bits/std_mutex.h> 43 #include <bits/unique_lock.h> 44 #include <bits/alloc_traits.h> 45 #include <bits/shared_ptr.h> 46 #include <bits/cxxabi_forced.h> 47 48 #if __cplusplus > 201703L 49 # include <stop_token> 50 #endif 51 52 #if defined(_GLIBCXX_HAS_GTHREADS) 53 54 namespace std _GLIBCXX_VISIBILITY(default) 55 { 56 _GLIBCXX_BEGIN_NAMESPACE_VERSION 57 58 /** 59 * @defgroup condition_variables Condition Variables 60 * @ingroup concurrency 61 * 62 * Classes for condition_variable support. 63 * @{ 64 */ 65 66 /// cv_status 67 enum class cv_status { no_timeout, timeout }; 68 69 /// condition_variable 70 class condition_variable 71 { 72 using steady_clock = chrono::steady_clock; 73 using system_clock = chrono::system_clock; 74 #ifdef _GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT 75 using __clock_t = steady_clock; 76 #else 77 using __clock_t = system_clock; 78 #endif 79 80 __condvar _M_cond; 81 82 public: 83 typedef __gthread_cond_t* native_handle_type; 84 85 condition_variable() noexcept; 86 ~condition_variable() noexcept; 87 88 condition_variable(const condition_variable&) = delete; 89 condition_variable& operator=(const condition_variable&) = delete; 90 91 void 92 notify_one() noexcept; 93 94 void 95 notify_all() noexcept; 96 97 void 98 wait(unique_lock<mutex>& __lock); 99 100 template<typename _Predicate> 101 void 102 wait(unique_lock<mutex>& __lock, _Predicate __p) 103 { 104 while (!__p()) 105 wait(__lock); 106 } 107 108 #ifdef _GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT 109 template<typename _Duration> 110 cv_status 111 wait_until(unique_lock<mutex>& __lock, 112 const chrono::time_point<steady_clock, _Duration>& __atime) 113 { return __wait_until_impl(__lock, __atime); } 114 #endif 115 116 template<typename _Duration> 117 cv_status 118 wait_until(unique_lock<mutex>& __lock, 119 const chrono::time_point<system_clock, _Duration>& __atime) 120 { return __wait_until_impl(__lock, __atime); } 121 122 template<typename _Clock, typename _Duration> 123 cv_status 124 wait_until(unique_lock<mutex>& __lock, 125 const chrono::time_point<_Clock, _Duration>& __atime) 126 { 127 #if __cplusplus > 201703L 128 static_assert(chrono::is_clock_v<_Clock>); 129 #endif 130 using __s_dur = typename __clock_t::duration; 131 const typename _Clock::time_point __c_entry = _Clock::now(); 132 const __clock_t::time_point __s_entry = __clock_t::now(); 133 const auto __delta = __atime - __c_entry; 134 const auto __s_atime = __s_entry + 135 chrono::__detail::ceil<__s_dur>(__delta); 136 137 if (__wait_until_impl(__lock, __s_atime) == cv_status::no_timeout) 138 return cv_status::no_timeout; 139 // We got a timeout when measured against __clock_t but 140 // we need to check against the caller-supplied clock 141 // to tell whether we should return a timeout. 142 if (_Clock::now() < __atime) 143 return cv_status::no_timeout; 144 return cv_status::timeout; 145 } 146 147 template<typename _Clock, typename _Duration, typename _Predicate> 148 bool 149 wait_until(unique_lock<mutex>& __lock, 150 const chrono::time_point<_Clock, _Duration>& __atime, 151 _Predicate __p) 152 { 153 while (!__p()) 154 if (wait_until(__lock, __atime) == cv_status::timeout) 155 return __p(); 156 return true; 157 } 158 159 template<typename _Rep, typename _Period> 160 cv_status 161 wait_for(unique_lock<mutex>& __lock, 162 const chrono::duration<_Rep, _Period>& __rtime) 163 { 164 using __dur = typename steady_clock::duration; 165 return wait_until(__lock, 166 steady_clock::now() + 167 chrono::__detail::ceil<__dur>(__rtime)); 168 } 169 170 template<typename _Rep, typename _Period, typename _Predicate> 171 bool 172 wait_for(unique_lock<mutex>& __lock, 173 const chrono::duration<_Rep, _Period>& __rtime, 174 _Predicate __p) 175 { 176 using __dur = typename steady_clock::duration; 177 return wait_until(__lock, 178 steady_clock::now() + 179 chrono::__detail::ceil<__dur>(__rtime), 180 std::move(__p)); 181 } 182 183 native_handle_type 184 native_handle() 185 { return _M_cond.native_handle(); } 186 187 private: 188 #ifdef _GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT 189 template<typename _Dur> 190 cv_status 191 __wait_until_impl(unique_lock<mutex>& __lock, 192 const chrono::time_point<steady_clock, _Dur>& __atime) 193 { 194 auto __s = chrono::time_point_cast<chrono::seconds>(__atime); 195 auto __ns = chrono::duration_cast<chrono::nanoseconds>(__atime - __s); 196 197 __gthread_time_t __ts = 198 { 199 static_cast<std::time_t>(__s.time_since_epoch().count()), 200 static_cast<long>(__ns.count()) 201 }; 202 203 _M_cond.wait_until(*__lock.mutex(), CLOCK_MONOTONIC, __ts); 204 205 return (steady_clock::now() < __atime 206 ? cv_status::no_timeout : cv_status::timeout); 207 } 208 #endif 209 210 template<typename _Dur> 211 cv_status 212 __wait_until_impl(unique_lock<mutex>& __lock, 213 const chrono::time_point<system_clock, _Dur>& __atime) 214 { 215 auto __s = chrono::time_point_cast<chrono::seconds>(__atime); 216 auto __ns = chrono::duration_cast<chrono::nanoseconds>(__atime - __s); 217 218 __gthread_time_t __ts = 219 { 220 static_cast<std::time_t>(__s.time_since_epoch().count()), 221 static_cast<long>(__ns.count()) 222 }; 223 224 _M_cond.wait_until(*__lock.mutex(), __ts); 225 226 return (system_clock::now() < __atime 227 ? cv_status::no_timeout : cv_status::timeout); 228 } 229 }; 230 231 void 232 notify_all_at_thread_exit(condition_variable&, unique_lock<mutex>); 233 234 struct __at_thread_exit_elt 235 { 236 __at_thread_exit_elt* _M_next; 237 void (*_M_cb)(void*); 238 }; 239 240 _GLIBCXX_BEGIN_INLINE_ABI_NAMESPACE(_V2) 241 242 /// condition_variable_any 243 // Like above, but mutex is not required to have try_lock. 244 class condition_variable_any 245 { 246 #ifdef _GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT 247 using __clock_t = chrono::steady_clock; 248 #else 249 using __clock_t = chrono::system_clock; 250 #endif 251 condition_variable _M_cond; 252 shared_ptr<mutex> _M_mutex; 253 254 // scoped unlock - unlocks in ctor, re-locks in dtor 255 template<typename _Lock> 256 struct _Unlock 257 { 258 explicit _Unlock(_Lock& __lk) : _M_lock(__lk) { __lk.unlock(); } 259 260 #pragma GCC diagnostic push 261 #pragma GCC diagnostic ignored "-Wdeprecated-declarations" 262 ~_Unlock() noexcept(false) 263 { 264 if (uncaught_exception()) 265 { 266 __try 267 { _M_lock.lock(); } 268 __catch(const __cxxabiv1::__forced_unwind&) 269 { __throw_exception_again; } 270 __catch(...) 271 { } 272 } 273 else 274 _M_lock.lock(); 275 } 276 #pragma GCC diagnostic pop 277 278 _Unlock(const _Unlock&) = delete; 279 _Unlock& operator=(const _Unlock&) = delete; 280 281 _Lock& _M_lock; 282 }; 283 284 public: 285 condition_variable_any() : _M_mutex(std::make_shared<mutex>()) { } 286 ~condition_variable_any() = default; 287 288 condition_variable_any(const condition_variable_any&) = delete; 289 condition_variable_any& operator=(const condition_variable_any&) = delete; 290 291 void 292 notify_one() noexcept 293 { 294 lock_guard<mutex> __lock(*_M_mutex); 295 _M_cond.notify_one(); 296 } 297 298 void 299 notify_all() noexcept 300 { 301 lock_guard<mutex> __lock(*_M_mutex); 302 _M_cond.notify_all(); 303 } 304 305 template<typename _Lock> 306 void 307 wait(_Lock& __lock) 308 { 309 shared_ptr<mutex> __mutex = _M_mutex; 310 unique_lock<mutex> __my_lock(*__mutex); 311 _Unlock<_Lock> __unlock(__lock); 312 // *__mutex must be unlocked before re-locking __lock so move 313 // ownership of *__mutex lock to an object with shorter lifetime. 314 unique_lock<mutex> __my_lock2(std::move(__my_lock)); 315 _M_cond.wait(__my_lock2); 316 } 317 318 319 template<typename _Lock, typename _Predicate> 320 void 321 wait(_Lock& __lock, _Predicate __p) 322 { 323 while (!__p()) 324 wait(__lock); 325 } 326 327 template<typename _Lock, typename _Clock, typename _Duration> 328 cv_status 329 wait_until(_Lock& __lock, 330 const chrono::time_point<_Clock, _Duration>& __atime) 331 { 332 shared_ptr<mutex> __mutex = _M_mutex; 333 unique_lock<mutex> __my_lock(*__mutex); 334 _Unlock<_Lock> __unlock(__lock); 335 // *__mutex must be unlocked before re-locking __lock so move 336 // ownership of *__mutex lock to an object with shorter lifetime. 337 unique_lock<mutex> __my_lock2(std::move(__my_lock)); 338 return _M_cond.wait_until(__my_lock2, __atime); 339 } 340 341 template<typename _Lock, typename _Clock, 342 typename _Duration, typename _Predicate> 343 bool 344 wait_until(_Lock& __lock, 345 const chrono::time_point<_Clock, _Duration>& __atime, 346 _Predicate __p) 347 { 348 while (!__p()) 349 if (wait_until(__lock, __atime) == cv_status::timeout) 350 return __p(); 351 return true; 352 } 353 354 template<typename _Lock, typename _Rep, typename _Period> 355 cv_status 356 wait_for(_Lock& __lock, const chrono::duration<_Rep, _Period>& __rtime) 357 { return wait_until(__lock, __clock_t::now() + __rtime); } 358 359 template<typename _Lock, typename _Rep, 360 typename _Period, typename _Predicate> 361 bool 362 wait_for(_Lock& __lock, 363 const chrono::duration<_Rep, _Period>& __rtime, _Predicate __p) 364 { return wait_until(__lock, __clock_t::now() + __rtime, std::move(__p)); } 365 366 #ifdef __cpp_lib_jthread 367 template <class _Lock, class _Predicate> 368 bool wait(_Lock& __lock, 369 stop_token __stoken, 370 _Predicate __p) 371 { 372 if (__stoken.stop_requested()) 373 { 374 return __p(); 375 } 376 377 std::stop_callback __cb(__stoken, [this] { notify_all(); }); 378 shared_ptr<mutex> __mutex = _M_mutex; 379 while (!__p()) 380 { 381 unique_lock<mutex> __my_lock(*__mutex); 382 if (__stoken.stop_requested()) 383 { 384 return false; 385 } 386 // *__mutex must be unlocked before re-locking __lock so move 387 // ownership of *__mutex lock to an object with shorter lifetime. 388 _Unlock<_Lock> __unlock(__lock); 389 unique_lock<mutex> __my_lock2(std::move(__my_lock)); 390 _M_cond.wait(__my_lock2); 391 } 392 return true; 393 } 394 395 template <class _Lock, class _Clock, class _Duration, class _Predicate> 396 bool wait_until(_Lock& __lock, 397 stop_token __stoken, 398 const chrono::time_point<_Clock, _Duration>& __abs_time, 399 _Predicate __p) 400 { 401 if (__stoken.stop_requested()) 402 { 403 return __p(); 404 } 405 406 std::stop_callback __cb(__stoken, [this] { notify_all(); }); 407 shared_ptr<mutex> __mutex = _M_mutex; 408 while (!__p()) 409 { 410 bool __stop; 411 { 412 unique_lock<mutex> __my_lock(*__mutex); 413 if (__stoken.stop_requested()) 414 { 415 return false; 416 } 417 _Unlock<_Lock> __u(__lock); 418 unique_lock<mutex> __my_lock2(std::move(__my_lock)); 419 const auto __status = _M_cond.wait_until(__my_lock2, __abs_time); 420 __stop = (__status == std::cv_status::timeout) || __stoken.stop_requested(); 421 } 422 if (__stop) 423 { 424 return __p(); 425 } 426 } 427 return true; 428 } 429 430 template <class _Lock, class _Rep, class _Period, class _Predicate> 431 bool wait_for(_Lock& __lock, 432 stop_token __stoken, 433 const chrono::duration<_Rep, _Period>& __rel_time, 434 _Predicate __p) 435 { 436 auto __abst = std::chrono::steady_clock::now() + __rel_time; 437 return wait_until(__lock, 438 std::move(__stoken), 439 __abst, 440 std::move(__p)); 441 } 442 #endif 443 }; 444 445 _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2) 446 447 /// @} group condition_variables 448 _GLIBCXX_END_NAMESPACE_VERSION 449 } // namespace 450 451 #endif // _GLIBCXX_HAS_GTHREADS 452 #endif // C++11 453 #endif // _GLIBCXX_CONDITION_VARIABLE
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