1// -*- C++ -*- 2//===----------------------------------------------------------------------===// 3// 4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 5// See https://llvm.org/LICENSE.txt for license information. 6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 7// 8//===----------------------------------------------------------------------===// 9 10#ifndef _LIBCPP_CONDITION_VARIABLE 11#define _LIBCPP_CONDITION_VARIABLE 12 13/* 14 condition_variable synopsis 15 16namespace std 17{ 18 19enum class cv_status { no_timeout, timeout }; 20 21class condition_variable 22{ 23public: 24 condition_variable(); 25 ~condition_variable(); 26 27 condition_variable(const condition_variable&) = delete; 28 condition_variable& operator=(const condition_variable&) = delete; 29 30 void notify_one() noexcept; 31 void notify_all() noexcept; 32 33 void wait(unique_lock<mutex>& lock); 34 template <class Predicate> 35 void wait(unique_lock<mutex>& lock, Predicate pred); 36 37 template <class Clock, class Duration> 38 cv_status 39 wait_until(unique_lock<mutex>& lock, 40 const chrono::time_point<Clock, Duration>& abs_time); 41 42 template <class Clock, class Duration, class Predicate> 43 bool 44 wait_until(unique_lock<mutex>& lock, 45 const chrono::time_point<Clock, Duration>& abs_time, 46 Predicate pred); 47 48 template <class Rep, class Period> 49 cv_status 50 wait_for(unique_lock<mutex>& lock, 51 const chrono::duration<Rep, Period>& rel_time); 52 53 template <class Rep, class Period, class Predicate> 54 bool 55 wait_for(unique_lock<mutex>& lock, 56 const chrono::duration<Rep, Period>& rel_time, 57 Predicate pred); 58 59 typedef pthread_cond_t* native_handle_type; 60 native_handle_type native_handle(); 61}; 62 63void notify_all_at_thread_exit(condition_variable& cond, unique_lock<mutex> lk); 64 65class condition_variable_any 66{ 67public: 68 condition_variable_any(); 69 ~condition_variable_any(); 70 71 condition_variable_any(const condition_variable_any&) = delete; 72 condition_variable_any& operator=(const condition_variable_any&) = delete; 73 74 void notify_one() noexcept; 75 void notify_all() noexcept; 76 77 template <class Lock> 78 void wait(Lock& lock); 79 template <class Lock, class Predicate> 80 void wait(Lock& lock, Predicate pred); 81 82 template <class Lock, class Clock, class Duration> 83 cv_status 84 wait_until(Lock& lock, 85 const chrono::time_point<Clock, Duration>& abs_time); 86 87 template <class Lock, class Clock, class Duration, class Predicate> 88 bool 89 wait_until(Lock& lock, 90 const chrono::time_point<Clock, Duration>& abs_time, 91 Predicate pred); 92 93 template <class Lock, class Rep, class Period> 94 cv_status 95 wait_for(Lock& lock, 96 const chrono::duration<Rep, Period>& rel_time); 97 98 template <class Lock, class Rep, class Period, class Predicate> 99 bool 100 wait_for(Lock& lock, 101 const chrono::duration<Rep, Period>& rel_time, 102 Predicate pred); 103 104 // [thread.condvarany.intwait], interruptible waits 105 template <class Lock, class Predicate> 106 bool wait(Lock& lock, stop_token stoken, Predicate pred); // since C++20 107 108 template <class Lock, class Clock, class Duration, class Predicate> 109 bool wait_until(Lock& lock, stop_token stoken, 110 const chrono::time_point<Clock, Duration>& abs_time, Predicate pred); // since C++20 111 112 template <class Lock, class Rep, class Period, class Predicate> 113 bool wait_for(Lock& lock, stop_token stoken, 114 const chrono::duration<Rep, Period>& rel_time, Predicate pred); // since C++20 115}; 116 117} // std 118 119*/ 120 121#include <__assert> // all public C++ headers provide the assertion handler 122#include <__availability> 123#include <__chrono/duration.h> 124#include <__chrono/steady_clock.h> 125#include <__chrono/time_point.h> 126#include <__condition_variable/condition_variable.h> 127#include <__config> 128#include <__memory/shared_ptr.h> 129#include <__mutex/lock_guard.h> 130#include <__mutex/mutex.h> 131#include <__mutex/tag_types.h> 132#include <__mutex/unique_lock.h> 133#include <__stop_token/stop_callback.h> 134#include <__stop_token/stop_token.h> 135#include <__utility/move.h> 136#include <version> 137 138#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 139# pragma GCC system_header 140#endif 141 142#ifndef _LIBCPP_HAS_NO_THREADS 143 144_LIBCPP_BEGIN_NAMESPACE_STD 145 146class _LIBCPP_EXPORTED_FROM_ABI condition_variable_any { 147 condition_variable __cv_; 148 shared_ptr<mutex> __mut_; 149 150public: 151 _LIBCPP_HIDE_FROM_ABI condition_variable_any(); 152 153 _LIBCPP_HIDE_FROM_ABI void notify_one() _NOEXCEPT; 154 _LIBCPP_HIDE_FROM_ABI void notify_all() _NOEXCEPT; 155 156 template <class _Lock> 157 _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS void wait(_Lock& __lock); 158 template <class _Lock, class _Predicate> 159 _LIBCPP_HIDE_FROM_ABI void wait(_Lock& __lock, _Predicate __pred); 160 161 template <class _Lock, class _Clock, class _Duration> 162 _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS cv_status 163 wait_until(_Lock& __lock, const chrono::time_point<_Clock, _Duration>& __t); 164 165 template <class _Lock, class _Clock, class _Duration, class _Predicate> 166 bool _LIBCPP_HIDE_FROM_ABI 167 wait_until(_Lock& __lock, const chrono::time_point<_Clock, _Duration>& __t, _Predicate __pred); 168 169 template <class _Lock, class _Rep, class _Period> 170 cv_status _LIBCPP_HIDE_FROM_ABI wait_for(_Lock& __lock, const chrono::duration<_Rep, _Period>& __d); 171 172 template <class _Lock, class _Rep, class _Period, class _Predicate> 173 bool _LIBCPP_HIDE_FROM_ABI wait_for(_Lock& __lock, const chrono::duration<_Rep, _Period>& __d, _Predicate __pred); 174 175# if _LIBCPP_STD_VER >= 20 && !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_STOP_TOKEN) 176 177 template <class _Lock, class _Predicate> 178 _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI bool wait(_Lock& __lock, stop_token __stoken, _Predicate __pred); 179 180 template <class _Lock, class _Clock, class _Duration, class _Predicate> 181 _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI bool wait_until( 182 _Lock& __lock, stop_token __stoken, const chrono::time_point<_Clock, _Duration>& __abs_time, _Predicate __pred); 183 184 template <class _Lock, class _Rep, class _Period, class _Predicate> 185 _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI bool 186 wait_for(_Lock& __lock, stop_token __stoken, const chrono::duration<_Rep, _Period>& __rel_time, _Predicate __pred); 187 188# endif // _LIBCPP_STD_VER >= 20 && !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_STOP_TOKEN) 189}; 190 191inline condition_variable_any::condition_variable_any() : __mut_(make_shared<mutex>()) {} 192 193inline void condition_variable_any::notify_one() _NOEXCEPT { 194 { lock_guard<mutex> __lx(*__mut_); } 195 __cv_.notify_one(); 196} 197 198inline void condition_variable_any::notify_all() _NOEXCEPT { 199 { lock_guard<mutex> __lx(*__mut_); } 200 __cv_.notify_all(); 201} 202 203template <class _Lock> 204struct __unlock_guard { 205 _Lock& __lock_; 206 207 _LIBCPP_HIDE_FROM_ABI __unlock_guard(_Lock& __lock) : __lock_(__lock) { __lock_.unlock(); } 208 209 _LIBCPP_HIDE_FROM_ABI ~__unlock_guard() _NOEXCEPT // turns exception to std::terminate 210 { 211 __lock_.lock(); 212 } 213 214 __unlock_guard(const __unlock_guard&) = delete; 215 __unlock_guard& operator=(const __unlock_guard&) = delete; 216}; 217 218template <class _Lock> 219void condition_variable_any::wait(_Lock& __lock) { 220 shared_ptr<mutex> __mut = __mut_; 221 unique_lock<mutex> __lk(*__mut); 222 __unlock_guard<_Lock> __unlock(__lock); 223 lock_guard<unique_lock<mutex> > __lx(__lk, adopt_lock_t()); 224 __cv_.wait(__lk); 225} // __mut_.unlock(), __lock.lock() 226 227template <class _Lock, class _Predicate> 228inline void condition_variable_any::wait(_Lock& __lock, _Predicate __pred) { 229 while (!__pred()) 230 wait(__lock); 231} 232 233template <class _Lock, class _Clock, class _Duration> 234cv_status condition_variable_any::wait_until(_Lock& __lock, const chrono::time_point<_Clock, _Duration>& __t) { 235 shared_ptr<mutex> __mut = __mut_; 236 unique_lock<mutex> __lk(*__mut); 237 __unlock_guard<_Lock> __unlock(__lock); 238 lock_guard<unique_lock<mutex> > __lx(__lk, adopt_lock_t()); 239 return __cv_.wait_until(__lk, __t); 240} // __mut_.unlock(), __lock.lock() 241 242template <class _Lock, class _Clock, class _Duration, class _Predicate> 243inline bool 244condition_variable_any::wait_until(_Lock& __lock, const chrono::time_point<_Clock, _Duration>& __t, _Predicate __pred) { 245 while (!__pred()) 246 if (wait_until(__lock, __t) == cv_status::timeout) 247 return __pred(); 248 return true; 249} 250 251template <class _Lock, class _Rep, class _Period> 252inline cv_status condition_variable_any::wait_for(_Lock& __lock, const chrono::duration<_Rep, _Period>& __d) { 253 return wait_until(__lock, chrono::steady_clock::now() + __d); 254} 255 256template <class _Lock, class _Rep, class _Period, class _Predicate> 257inline bool 258condition_variable_any::wait_for(_Lock& __lock, const chrono::duration<_Rep, _Period>& __d, _Predicate __pred) { 259 return wait_until(__lock, chrono::steady_clock::now() + __d, std::move(__pred)); 260} 261 262# if _LIBCPP_STD_VER >= 20 && !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_STOP_TOKEN) 263 264template <class _Lock, class _Predicate> 265bool condition_variable_any::wait(_Lock& __user_lock, stop_token __stoken, _Predicate __pred) { 266 if (__stoken.stop_requested()) 267 return __pred(); 268 269 // Per https://eel.is/c++draft/thread.condition.condvarany#general-note-2, 270 // we do need to take a copy of the shared pointer __mut_ 271 // This ensures that a thread can call the destructor immediately after calling 272 // notify_all, without waiting all the wait calls. 273 // A thread can also safely call the destructor immediately after calling 274 // request_stop, as the call to request_stop would evaluate the callback, 275 // which accesses the internal condition variable, immediately on the same thread. 276 // In this situation, it is OK even without copying a shared ownership the internal 277 // condition variable. However, this needs the evaluation of stop_callback to 278 // happen-before the destruction. 279 // The spec only says "Only the notification to unblock the wait needs to happen 280 // before destruction". To make this work, we need to copy the shared ownership of 281 // the internal condition variable inside this function, which is not possible 282 // with the current ABI. 283 shared_ptr<mutex> __mut = __mut_; 284 285 stop_callback __cb(__stoken, [this] { notify_all(); }); 286 287 while (true) { 288 if (__pred()) 289 return true; 290 291 // We need to take the internal lock before checking stop_requested, 292 // so that the notification cannot come in between the stop_requested 293 // check and entering the wait. 294 // Note that the stop_callback takes the same internal lock before notifying 295 unique_lock<mutex> __internal_lock(*__mut); 296 if (__stoken.stop_requested()) 297 break; 298 299 __unlock_guard<_Lock> __unlock(__user_lock); 300 unique_lock<mutex> __internal_lock2( 301 std::move(__internal_lock)); // switch unlock order between __internal_lock and __user_lock 302 __cv_.wait(__internal_lock2); 303 } // __internal_lock2.unlock(), __user_lock.lock() 304 return __pred(); 305} 306 307template <class _Lock, class _Clock, class _Duration, class _Predicate> 308bool condition_variable_any::wait_until( 309 _Lock& __user_lock, 310 stop_token __stoken, 311 const chrono::time_point<_Clock, _Duration>& __abs_time, 312 _Predicate __pred) { 313 if (__stoken.stop_requested()) 314 return __pred(); 315 316 shared_ptr<mutex> __mut = __mut_; 317 stop_callback __cb(__stoken, [this] { notify_all(); }); 318 319 while (true) { 320 if (__pred()) 321 return true; 322 323 unique_lock<mutex> __internal_lock(*__mut); 324 if (__stoken.stop_requested()) 325 break; 326 327 __unlock_guard<_Lock> __unlock(__user_lock); 328 unique_lock<mutex> __internal_lock2( 329 std::move(__internal_lock)); // switch unlock order between __internal_lock and __user_lock 330 331 if (__cv_.wait_until(__internal_lock2, __abs_time) == cv_status::timeout) 332 break; 333 } // __internal_lock2.unlock(), __user_lock.lock() 334 return __pred(); 335} 336 337template <class _Lock, class _Rep, class _Period, class _Predicate> 338bool condition_variable_any::wait_for( 339 _Lock& __lock, stop_token __stoken, const chrono::duration<_Rep, _Period>& __rel_time, _Predicate __pred) { 340 return wait_until(__lock, std::move(__stoken), chrono::steady_clock::now() + __rel_time, std::move(__pred)); 341} 342 343# endif // _LIBCPP_STD_VER >= 20 && !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_STOP_TOKEN) 344 345_LIBCPP_EXPORTED_FROM_ABI void notify_all_at_thread_exit(condition_variable&, unique_lock<mutex>); 346 347_LIBCPP_END_NAMESPACE_STD 348 349#endif // !_LIBCPP_HAS_NO_THREADS 350 351#if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20 352# include <atomic> 353# include <concepts> 354# include <cstdint> 355# include <cstdlib> 356# include <cstring> 357# include <initializer_list> 358# include <iosfwd> 359# include <new> 360# include <stdexcept> 361# include <system_error> 362# include <type_traits> 363# include <typeinfo> 364#endif 365 366#endif // _LIBCPP_CONDITION_VARIABLE 367