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_SHARED_MUTEX 11#define _LIBCPP_SHARED_MUTEX 12 13/* 14 shared_mutex synopsis 15 16// C++1y 17 18namespace std 19{ 20 21class shared_mutex // C++17 22{ 23public: 24 shared_mutex(); 25 ~shared_mutex(); 26 27 shared_mutex(const shared_mutex&) = delete; 28 shared_mutex& operator=(const shared_mutex&) = delete; 29 30 // Exclusive ownership 31 void lock(); // blocking 32 bool try_lock(); 33 void unlock(); 34 35 // Shared ownership 36 void lock_shared(); // blocking 37 bool try_lock_shared(); 38 void unlock_shared(); 39 40 typedef implementation-defined native_handle_type; // See 30.2.3 41 native_handle_type native_handle(); // See 30.2.3 42}; 43 44class shared_timed_mutex 45{ 46public: 47 shared_timed_mutex(); 48 ~shared_timed_mutex(); 49 50 shared_timed_mutex(const shared_timed_mutex&) = delete; 51 shared_timed_mutex& operator=(const shared_timed_mutex&) = delete; 52 53 // Exclusive ownership 54 void lock(); // blocking 55 bool try_lock(); 56 template <class Rep, class Period> 57 bool try_lock_for(const chrono::duration<Rep, Period>& rel_time); 58 template <class Clock, class Duration> 59 bool try_lock_until(const chrono::time_point<Clock, Duration>& abs_time); 60 void unlock(); 61 62 // Shared ownership 63 void lock_shared(); // blocking 64 bool try_lock_shared(); 65 template <class Rep, class Period> 66 bool 67 try_lock_shared_for(const chrono::duration<Rep, Period>& rel_time); 68 template <class Clock, class Duration> 69 bool 70 try_lock_shared_until(const chrono::time_point<Clock, Duration>& abs_time); 71 void unlock_shared(); 72}; 73 74template <class Mutex> 75class shared_lock 76{ 77public: 78 typedef Mutex mutex_type; 79 80 // Shared locking 81 shared_lock() noexcept; 82 explicit shared_lock(mutex_type& m); // blocking 83 shared_lock(mutex_type& m, defer_lock_t) noexcept; 84 shared_lock(mutex_type& m, try_to_lock_t); 85 shared_lock(mutex_type& m, adopt_lock_t); 86 template <class Clock, class Duration> 87 shared_lock(mutex_type& m, 88 const chrono::time_point<Clock, Duration>& abs_time); 89 template <class Rep, class Period> 90 shared_lock(mutex_type& m, 91 const chrono::duration<Rep, Period>& rel_time); 92 ~shared_lock(); 93 94 shared_lock(shared_lock const&) = delete; 95 shared_lock& operator=(shared_lock const&) = delete; 96 97 shared_lock(shared_lock&& u) noexcept; 98 shared_lock& operator=(shared_lock&& u) noexcept; 99 100 void lock(); // blocking 101 bool try_lock(); 102 template <class Rep, class Period> 103 bool try_lock_for(const chrono::duration<Rep, Period>& rel_time); 104 template <class Clock, class Duration> 105 bool try_lock_until(const chrono::time_point<Clock, Duration>& abs_time); 106 void unlock(); 107 108 // Setters 109 void swap(shared_lock& u) noexcept; 110 mutex_type* release() noexcept; 111 112 // Getters 113 bool owns_lock() const noexcept; 114 explicit operator bool () const noexcept; 115 mutex_type* mutex() const noexcept; 116}; 117 118template <class Mutex> 119 void swap(shared_lock<Mutex>& x, shared_lock<Mutex>& y) noexcept; 120 121} // std 122 123*/ 124 125#include <__config> 126 127#ifdef _LIBCPP_HAS_NO_THREADS 128# error "<shared_mutex> is not supported since libc++ has been configured without support for threads." 129#endif 130 131#include <__availability> 132#include <__chrono/duration.h> 133#include <__chrono/steady_clock.h> 134#include <__chrono/time_point.h> 135#include <__condition_variable/condition_variable.h> 136#include <__memory/addressof.h> 137#include <__mutex/mutex.h> 138#include <__mutex/tag_types.h> 139#include <__mutex/unique_lock.h> 140#include <__system_error/system_error.h> 141#include <__utility/swap.h> 142#include <cerrno> 143#include <version> 144 145_LIBCPP_PUSH_MACROS 146#include <__undef_macros> 147 148#if _LIBCPP_STD_VER >= 14 149 150# if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 151# pragma GCC system_header 152# endif 153 154_LIBCPP_BEGIN_NAMESPACE_STD 155 156struct _LIBCPP_EXPORTED_FROM_ABI __shared_mutex_base { 157 mutex __mut_; 158 condition_variable __gate1_; 159 condition_variable __gate2_; 160 unsigned __state_; 161 162 static const unsigned __write_entered_ = 1U << (sizeof(unsigned) * __CHAR_BIT__ - 1); 163 static const unsigned __n_readers_ = ~__write_entered_; 164 165 __shared_mutex_base(); 166 _LIBCPP_HIDE_FROM_ABI ~__shared_mutex_base() = default; 167 168 __shared_mutex_base(const __shared_mutex_base&) = delete; 169 __shared_mutex_base& operator=(const __shared_mutex_base&) = delete; 170 171 // Exclusive ownership 172 void lock(); // blocking 173 bool try_lock(); 174 void unlock(); 175 176 // Shared ownership 177 void lock_shared(); // blocking 178 bool try_lock_shared(); 179 void unlock_shared(); 180 181 // typedef implementation-defined native_handle_type; // See 30.2.3 182 // native_handle_type native_handle(); // See 30.2.3 183}; 184 185# if _LIBCPP_STD_VER >= 17 186class _LIBCPP_EXPORTED_FROM_ABI _LIBCPP_THREAD_SAFETY_ANNOTATION(__capability__("shared_mutex")) shared_mutex { 187 __shared_mutex_base __base_; 188 189public: 190 _LIBCPP_HIDE_FROM_ABI shared_mutex() : __base_() {} 191 _LIBCPP_HIDE_FROM_ABI ~shared_mutex() = default; 192 193 shared_mutex(const shared_mutex&) = delete; 194 shared_mutex& operator=(const shared_mutex&) = delete; 195 196 // Exclusive ownership 197 _LIBCPP_HIDE_FROM_ABI void lock() _LIBCPP_THREAD_SAFETY_ANNOTATION(__acquire_capability__()) { 198 return __base_.lock(); 199 } 200 _LIBCPP_HIDE_FROM_ABI bool try_lock() _LIBCPP_THREAD_SAFETY_ANNOTATION(__try_acquire_capability__(true)) { 201 return __base_.try_lock(); 202 } 203 _LIBCPP_HIDE_FROM_ABI void unlock() _LIBCPP_THREAD_SAFETY_ANNOTATION(__release_capability__()) { 204 return __base_.unlock(); 205 } 206 207 // Shared ownership 208 _LIBCPP_HIDE_FROM_ABI void lock_shared() _LIBCPP_THREAD_SAFETY_ANNOTATION(__acquire_shared_capability__()) { 209 return __base_.lock_shared(); 210 } 211 _LIBCPP_HIDE_FROM_ABI bool try_lock_shared() 212 _LIBCPP_THREAD_SAFETY_ANNOTATION(__try_acquire_shared_capability__(true)) { 213 return __base_.try_lock_shared(); 214 } 215 _LIBCPP_HIDE_FROM_ABI void unlock_shared() _LIBCPP_THREAD_SAFETY_ANNOTATION(__release_shared_capability__()) { 216 return __base_.unlock_shared(); 217 } 218 219 // typedef __shared_mutex_base::native_handle_type native_handle_type; 220 // _LIBCPP_HIDE_FROM_ABI native_handle_type native_handle() { return __base::unlock_shared(); } 221}; 222# endif 223 224class _LIBCPP_EXPORTED_FROM_ABI _LIBCPP_THREAD_SAFETY_ANNOTATION(__capability__("shared_timed_mutex")) 225 shared_timed_mutex { 226 __shared_mutex_base __base_; 227 228public: 229 shared_timed_mutex(); 230 _LIBCPP_HIDE_FROM_ABI ~shared_timed_mutex() = default; 231 232 shared_timed_mutex(const shared_timed_mutex&) = delete; 233 shared_timed_mutex& operator=(const shared_timed_mutex&) = delete; 234 235 // Exclusive ownership 236 void lock() _LIBCPP_THREAD_SAFETY_ANNOTATION(__acquire_capability__()); 237 bool try_lock() _LIBCPP_THREAD_SAFETY_ANNOTATION(__try_acquire_capability__(true)); 238 template <class _Rep, class _Period> 239 _LIBCPP_HIDE_FROM_ABI bool try_lock_for(const chrono::duration<_Rep, _Period>& __rel_time) 240 _LIBCPP_THREAD_SAFETY_ANNOTATION(__try_acquire_capability__(true)) { 241 return try_lock_until(chrono::steady_clock::now() + __rel_time); 242 } 243 template <class _Clock, class _Duration> 244 _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS bool 245 try_lock_until(const chrono::time_point<_Clock, _Duration>& __abs_time) 246 _LIBCPP_THREAD_SAFETY_ANNOTATION(__try_acquire_capability__(true)); 247 void unlock() _LIBCPP_THREAD_SAFETY_ANNOTATION(__release_capability__()); 248 249 // Shared ownership 250 void lock_shared() _LIBCPP_THREAD_SAFETY_ANNOTATION(__acquire_shared_capability__()); 251 bool try_lock_shared() _LIBCPP_THREAD_SAFETY_ANNOTATION(__try_acquire_shared_capability__(true)); 252 template <class _Rep, class _Period> 253 _LIBCPP_HIDE_FROM_ABI bool try_lock_shared_for(const chrono::duration<_Rep, _Period>& __rel_time) 254 _LIBCPP_THREAD_SAFETY_ANNOTATION(__try_acquire_shared_capability__(true)) { 255 return try_lock_shared_until(chrono::steady_clock::now() + __rel_time); 256 } 257 template <class _Clock, class _Duration> 258 _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS bool 259 try_lock_shared_until(const chrono::time_point<_Clock, _Duration>& __abs_time) 260 _LIBCPP_THREAD_SAFETY_ANNOTATION(__try_acquire_shared_capability__(true)); 261 void unlock_shared() _LIBCPP_THREAD_SAFETY_ANNOTATION(__release_shared_capability__()); 262}; 263 264template <class _Clock, class _Duration> 265bool shared_timed_mutex::try_lock_until(const chrono::time_point<_Clock, _Duration>& __abs_time) { 266 unique_lock<mutex> __lk(__base_.__mut_); 267 if (__base_.__state_ & __base_.__write_entered_) { 268 while (true) { 269 cv_status __status = __base_.__gate1_.wait_until(__lk, __abs_time); 270 if ((__base_.__state_ & __base_.__write_entered_) == 0) 271 break; 272 if (__status == cv_status::timeout) 273 return false; 274 } 275 } 276 __base_.__state_ |= __base_.__write_entered_; 277 if (__base_.__state_ & __base_.__n_readers_) { 278 while (true) { 279 cv_status __status = __base_.__gate2_.wait_until(__lk, __abs_time); 280 if ((__base_.__state_ & __base_.__n_readers_) == 0) 281 break; 282 if (__status == cv_status::timeout) { 283 __base_.__state_ &= ~__base_.__write_entered_; 284 __base_.__gate1_.notify_all(); 285 return false; 286 } 287 } 288 } 289 return true; 290} 291 292template <class _Clock, class _Duration> 293bool shared_timed_mutex::try_lock_shared_until(const chrono::time_point<_Clock, _Duration>& __abs_time) { 294 unique_lock<mutex> __lk(__base_.__mut_); 295 if ((__base_.__state_ & __base_.__write_entered_) || 296 (__base_.__state_ & __base_.__n_readers_) == __base_.__n_readers_) { 297 while (true) { 298 cv_status __status = __base_.__gate1_.wait_until(__lk, __abs_time); 299 if ((__base_.__state_ & __base_.__write_entered_) == 0 && 300 (__base_.__state_ & __base_.__n_readers_) < __base_.__n_readers_) 301 break; 302 if (__status == cv_status::timeout) 303 return false; 304 } 305 } 306 unsigned __num_readers = (__base_.__state_ & __base_.__n_readers_) + 1; 307 __base_.__state_ &= ~__base_.__n_readers_; 308 __base_.__state_ |= __num_readers; 309 return true; 310} 311 312template <class _Mutex> 313class shared_lock { 314public: 315 typedef _Mutex mutex_type; 316 317private: 318 mutex_type* __m_; 319 bool __owns_; 320 321public: 322 _LIBCPP_HIDE_FROM_ABI shared_lock() _NOEXCEPT : __m_(nullptr), __owns_(false) {} 323 324 _LIBCPP_HIDE_FROM_ABI explicit shared_lock(mutex_type& __m) : __m_(std::addressof(__m)), __owns_(true) { 325 __m_->lock_shared(); 326 } 327 328 _LIBCPP_HIDE_FROM_ABI shared_lock(mutex_type& __m, defer_lock_t) _NOEXCEPT 329 : __m_(std::addressof(__m)), 330 __owns_(false) {} 331 332 _LIBCPP_HIDE_FROM_ABI shared_lock(mutex_type& __m, try_to_lock_t) 333 : __m_(std::addressof(__m)), __owns_(__m.try_lock_shared()) {} 334 335 _LIBCPP_HIDE_FROM_ABI shared_lock(mutex_type& __m, adopt_lock_t) : __m_(std::addressof(__m)), __owns_(true) {} 336 337 template <class _Clock, class _Duration> 338 _LIBCPP_HIDE_FROM_ABI shared_lock(mutex_type& __m, const chrono::time_point<_Clock, _Duration>& __abs_time) 339 : __m_(std::addressof(__m)), __owns_(__m.try_lock_shared_until(__abs_time)) {} 340 341 template <class _Rep, class _Period> 342 _LIBCPP_HIDE_FROM_ABI shared_lock(mutex_type& __m, const chrono::duration<_Rep, _Period>& __rel_time) 343 : __m_(std::addressof(__m)), __owns_(__m.try_lock_shared_for(__rel_time)) {} 344 345 _LIBCPP_HIDE_FROM_ABI ~shared_lock() { 346 if (__owns_) 347 __m_->unlock_shared(); 348 } 349 350 shared_lock(shared_lock const&) = delete; 351 shared_lock& operator=(shared_lock const&) = delete; 352 353 _LIBCPP_HIDE_FROM_ABI shared_lock(shared_lock&& __u) _NOEXCEPT : __m_(__u.__m_), __owns_(__u.__owns_) { 354 __u.__m_ = nullptr; 355 __u.__owns_ = false; 356 } 357 358 _LIBCPP_HIDE_FROM_ABI shared_lock& operator=(shared_lock&& __u) _NOEXCEPT { 359 if (__owns_) 360 __m_->unlock_shared(); 361 __m_ = nullptr; 362 __owns_ = false; 363 __m_ = __u.__m_; 364 __owns_ = __u.__owns_; 365 __u.__m_ = nullptr; 366 __u.__owns_ = false; 367 return *this; 368 } 369 370 _LIBCPP_HIDE_FROM_ABI void lock(); 371 _LIBCPP_HIDE_FROM_ABI bool try_lock(); 372 template <class _Rep, class _Period> 373 _LIBCPP_HIDE_FROM_ABI bool try_lock_for(const chrono::duration<_Rep, _Period>& __rel_time); 374 template <class _Clock, class _Duration> 375 _LIBCPP_HIDE_FROM_ABI bool try_lock_until(const chrono::time_point<_Clock, _Duration>& __abs_time); 376 _LIBCPP_HIDE_FROM_ABI void unlock(); 377 378 // Setters 379 _LIBCPP_HIDE_FROM_ABI void swap(shared_lock& __u) _NOEXCEPT { 380 std::swap(__m_, __u.__m_); 381 std::swap(__owns_, __u.__owns_); 382 } 383 384 _LIBCPP_HIDE_FROM_ABI mutex_type* release() _NOEXCEPT { 385 mutex_type* __m = __m_; 386 __m_ = nullptr; 387 __owns_ = false; 388 return __m; 389 } 390 391 // Getters 392 _LIBCPP_HIDE_FROM_ABI bool owns_lock() const _NOEXCEPT { return __owns_; } 393 394 _LIBCPP_HIDE_FROM_ABI explicit operator bool() const _NOEXCEPT { return __owns_; } 395 396 _LIBCPP_HIDE_FROM_ABI mutex_type* mutex() const _NOEXCEPT { return __m_; } 397}; 398_LIBCPP_CTAD_SUPPORTED_FOR_TYPE(shared_lock); 399 400template <class _Mutex> 401void shared_lock<_Mutex>::lock() { 402 if (__m_ == nullptr) 403 __throw_system_error(EPERM, "shared_lock::lock: references null mutex"); 404 if (__owns_) 405 __throw_system_error(EDEADLK, "shared_lock::lock: already locked"); 406 __m_->lock_shared(); 407 __owns_ = true; 408} 409 410template <class _Mutex> 411bool shared_lock<_Mutex>::try_lock() { 412 if (__m_ == nullptr) 413 __throw_system_error(EPERM, "shared_lock::try_lock: references null mutex"); 414 if (__owns_) 415 __throw_system_error(EDEADLK, "shared_lock::try_lock: already locked"); 416 __owns_ = __m_->try_lock_shared(); 417 return __owns_; 418} 419 420template <class _Mutex> 421template <class _Rep, class _Period> 422bool shared_lock<_Mutex>::try_lock_for(const chrono::duration<_Rep, _Period>& __d) { 423 if (__m_ == nullptr) 424 __throw_system_error(EPERM, "shared_lock::try_lock_for: references null mutex"); 425 if (__owns_) 426 __throw_system_error(EDEADLK, "shared_lock::try_lock_for: already locked"); 427 __owns_ = __m_->try_lock_shared_for(__d); 428 return __owns_; 429} 430 431template <class _Mutex> 432template <class _Clock, class _Duration> 433bool shared_lock<_Mutex>::try_lock_until(const chrono::time_point<_Clock, _Duration>& __t) { 434 if (__m_ == nullptr) 435 __throw_system_error(EPERM, "shared_lock::try_lock_until: references null mutex"); 436 if (__owns_) 437 __throw_system_error(EDEADLK, "shared_lock::try_lock_until: already locked"); 438 __owns_ = __m_->try_lock_shared_until(__t); 439 return __owns_; 440} 441 442template <class _Mutex> 443void shared_lock<_Mutex>::unlock() { 444 if (!__owns_) 445 __throw_system_error(EPERM, "shared_lock::unlock: not locked"); 446 __m_->unlock_shared(); 447 __owns_ = false; 448} 449 450template <class _Mutex> 451inline _LIBCPP_HIDE_FROM_ABI void swap(shared_lock<_Mutex>& __x, shared_lock<_Mutex>& __y) _NOEXCEPT { 452 __x.swap(__y); 453} 454 455_LIBCPP_END_NAMESPACE_STD 456 457#endif // _LIBCPP_STD_VER >= 14 458 459_LIBCPP_POP_MACROS 460 461#if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20 462# include <system_error> 463#endif 464 465#endif // _LIBCPP_SHARED_MUTEX 466