1// -*- C++ -*- 2//===------------------------ shared_mutex --------------------------------===// 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 <__availability> 126#include <__config> 127#include <version> 128 129_LIBCPP_PUSH_MACROS 130#include <__undef_macros> 131 132 133#if _LIBCPP_STD_VER > 11 || defined(_LIBCPP_BUILDING_LIBRARY) 134 135#include <__mutex_base> 136 137#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 138#pragma GCC system_header 139#endif 140 141#ifdef _LIBCPP_HAS_NO_THREADS 142#error <shared_mutex> is not supported on this single threaded system 143#else // !_LIBCPP_HAS_NO_THREADS 144 145_LIBCPP_BEGIN_NAMESPACE_STD 146 147struct _LIBCPP_TYPE_VIS _LIBCPP_AVAILABILITY_SHARED_MUTEX _LIBCPP_THREAD_SAFETY_ANNOTATION(capability("shared_mutex")) 148__shared_mutex_base 149{ 150 mutex __mut_; 151 condition_variable __gate1_; 152 condition_variable __gate2_; 153 unsigned __state_; 154 155 static const unsigned __write_entered_ = 1U << (sizeof(unsigned)*__CHAR_BIT__ - 1); 156 static const unsigned __n_readers_ = ~__write_entered_; 157 158 __shared_mutex_base(); 159 _LIBCPP_INLINE_VISIBILITY ~__shared_mutex_base() = default; 160 161 __shared_mutex_base(const __shared_mutex_base&) = delete; 162 __shared_mutex_base& operator=(const __shared_mutex_base&) = delete; 163 164 // Exclusive ownership 165 void lock() _LIBCPP_THREAD_SAFETY_ANNOTATION(acquire_capability()); // blocking 166 bool try_lock() _LIBCPP_THREAD_SAFETY_ANNOTATION(try_acquire_capability(true)); 167 void unlock() _LIBCPP_THREAD_SAFETY_ANNOTATION(release_capability()); 168 169 // Shared ownership 170 void lock_shared() _LIBCPP_THREAD_SAFETY_ANNOTATION(acquire_shared_capability()); // blocking 171 bool try_lock_shared() _LIBCPP_THREAD_SAFETY_ANNOTATION(try_acquire_shared_capability(true)); 172 void unlock_shared() _LIBCPP_THREAD_SAFETY_ANNOTATION(release_shared_capability()); 173 174// typedef implementation-defined native_handle_type; // See 30.2.3 175// native_handle_type native_handle(); // See 30.2.3 176}; 177 178 179#if _LIBCPP_STD_VER > 14 180class _LIBCPP_TYPE_VIS _LIBCPP_AVAILABILITY_SHARED_MUTEX shared_mutex 181{ 182 __shared_mutex_base __base; 183public: 184 _LIBCPP_INLINE_VISIBILITY shared_mutex() : __base() {} 185 _LIBCPP_INLINE_VISIBILITY ~shared_mutex() = default; 186 187 shared_mutex(const shared_mutex&) = delete; 188 shared_mutex& operator=(const shared_mutex&) = delete; 189 190 // Exclusive ownership 191 _LIBCPP_INLINE_VISIBILITY void lock() { return __base.lock(); } 192 _LIBCPP_INLINE_VISIBILITY bool try_lock() { return __base.try_lock(); } 193 _LIBCPP_INLINE_VISIBILITY void unlock() { return __base.unlock(); } 194 195 // Shared ownership 196 _LIBCPP_INLINE_VISIBILITY void lock_shared() { return __base.lock_shared(); } 197 _LIBCPP_INLINE_VISIBILITY bool try_lock_shared() { return __base.try_lock_shared(); } 198 _LIBCPP_INLINE_VISIBILITY void unlock_shared() { return __base.unlock_shared(); } 199 200// typedef __shared_mutex_base::native_handle_type native_handle_type; 201// _LIBCPP_INLINE_VISIBILITY native_handle_type native_handle() { return __base::unlock_shared(); } 202}; 203#endif 204 205 206class _LIBCPP_TYPE_VIS _LIBCPP_AVAILABILITY_SHARED_MUTEX shared_timed_mutex 207{ 208 __shared_mutex_base __base; 209public: 210 shared_timed_mutex(); 211 _LIBCPP_INLINE_VISIBILITY ~shared_timed_mutex() = default; 212 213 shared_timed_mutex(const shared_timed_mutex&) = delete; 214 shared_timed_mutex& operator=(const shared_timed_mutex&) = delete; 215 216 // Exclusive ownership 217 void lock(); 218 bool try_lock(); 219 template <class _Rep, class _Period> 220 _LIBCPP_INLINE_VISIBILITY 221 bool 222 try_lock_for(const chrono::duration<_Rep, _Period>& __rel_time) 223 { 224 return try_lock_until(chrono::steady_clock::now() + __rel_time); 225 } 226 template <class _Clock, class _Duration> 227 _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS 228 bool 229 try_lock_until(const chrono::time_point<_Clock, _Duration>& __abs_time); 230 void unlock(); 231 232 // Shared ownership 233 void lock_shared(); 234 bool try_lock_shared(); 235 template <class _Rep, class _Period> 236 _LIBCPP_INLINE_VISIBILITY 237 bool 238 try_lock_shared_for(const chrono::duration<_Rep, _Period>& __rel_time) 239 { 240 return try_lock_shared_until(chrono::steady_clock::now() + __rel_time); 241 } 242 template <class _Clock, class _Duration> 243 _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS 244 bool 245 try_lock_shared_until(const chrono::time_point<_Clock, _Duration>& __abs_time); 246 void unlock_shared(); 247}; 248 249template <class _Clock, class _Duration> 250bool 251shared_timed_mutex::try_lock_until( 252 const chrono::time_point<_Clock, _Duration>& __abs_time) 253{ 254 unique_lock<mutex> __lk(__base.__mut_); 255 if (__base.__state_ & __base.__write_entered_) 256 { 257 while (true) 258 { 259 cv_status __status = __base.__gate1_.wait_until(__lk, __abs_time); 260 if ((__base.__state_ & __base.__write_entered_) == 0) 261 break; 262 if (__status == cv_status::timeout) 263 return false; 264 } 265 } 266 __base.__state_ |= __base.__write_entered_; 267 if (__base.__state_ & __base.__n_readers_) 268 { 269 while (true) 270 { 271 cv_status __status = __base.__gate2_.wait_until(__lk, __abs_time); 272 if ((__base.__state_ & __base.__n_readers_) == 0) 273 break; 274 if (__status == cv_status::timeout) 275 { 276 __base.__state_ &= ~__base.__write_entered_; 277 __base.__gate1_.notify_all(); 278 return false; 279 } 280 } 281 } 282 return true; 283} 284 285template <class _Clock, class _Duration> 286bool 287shared_timed_mutex::try_lock_shared_until( 288 const chrono::time_point<_Clock, _Duration>& __abs_time) 289{ 290 unique_lock<mutex> __lk(__base.__mut_); 291 if ((__base.__state_ & __base.__write_entered_) || (__base.__state_ & __base.__n_readers_) == __base.__n_readers_) 292 { 293 while (true) 294 { 295 cv_status status = __base.__gate1_.wait_until(__lk, __abs_time); 296 if ((__base.__state_ & __base.__write_entered_) == 0 && 297 (__base.__state_ & __base.__n_readers_) < __base.__n_readers_) 298 break; 299 if (status == cv_status::timeout) 300 return false; 301 } 302 } 303 unsigned __num_readers = (__base.__state_ & __base.__n_readers_) + 1; 304 __base.__state_ &= ~__base.__n_readers_; 305 __base.__state_ |= __num_readers; 306 return true; 307} 308 309template <class _Mutex> 310class shared_lock 311{ 312public: 313 typedef _Mutex mutex_type; 314 315private: 316 mutex_type* __m_; 317 bool __owns_; 318 319public: 320 _LIBCPP_INLINE_VISIBILITY 321 shared_lock() _NOEXCEPT 322 : __m_(nullptr), 323 __owns_(false) 324 {} 325 326 _LIBCPP_INLINE_VISIBILITY 327 explicit shared_lock(mutex_type& __m) 328 : __m_(_VSTD::addressof(__m)), 329 __owns_(true) 330 {__m_->lock_shared();} 331 332 _LIBCPP_INLINE_VISIBILITY 333 shared_lock(mutex_type& __m, defer_lock_t) _NOEXCEPT 334 : __m_(_VSTD::addressof(__m)), 335 __owns_(false) 336 {} 337 338 _LIBCPP_INLINE_VISIBILITY 339 shared_lock(mutex_type& __m, try_to_lock_t) 340 : __m_(_VSTD::addressof(__m)), 341 __owns_(__m.try_lock_shared()) 342 {} 343 344 _LIBCPP_INLINE_VISIBILITY 345 shared_lock(mutex_type& __m, adopt_lock_t) 346 : __m_(_VSTD::addressof(__m)), 347 __owns_(true) 348 {} 349 350 template <class _Clock, class _Duration> 351 _LIBCPP_INLINE_VISIBILITY 352 shared_lock(mutex_type& __m, 353 const chrono::time_point<_Clock, _Duration>& __abs_time) 354 : __m_(_VSTD::addressof(__m)), 355 __owns_(__m.try_lock_shared_until(__abs_time)) 356 {} 357 358 template <class _Rep, class _Period> 359 _LIBCPP_INLINE_VISIBILITY 360 shared_lock(mutex_type& __m, 361 const chrono::duration<_Rep, _Period>& __rel_time) 362 : __m_(_VSTD::addressof(__m)), 363 __owns_(__m.try_lock_shared_for(__rel_time)) 364 {} 365 366 _LIBCPP_INLINE_VISIBILITY 367 ~shared_lock() 368 { 369 if (__owns_) 370 __m_->unlock_shared(); 371 } 372 373 shared_lock(shared_lock const&) = delete; 374 shared_lock& operator=(shared_lock const&) = delete; 375 376 _LIBCPP_INLINE_VISIBILITY 377 shared_lock(shared_lock&& __u) _NOEXCEPT 378 : __m_(__u.__m_), 379 __owns_(__u.__owns_) 380 { 381 __u.__m_ = nullptr; 382 __u.__owns_ = false; 383 } 384 385 _LIBCPP_INLINE_VISIBILITY 386 shared_lock& operator=(shared_lock&& __u) _NOEXCEPT 387 { 388 if (__owns_) 389 __m_->unlock_shared(); 390 __m_ = nullptr; 391 __owns_ = false; 392 __m_ = __u.__m_; 393 __owns_ = __u.__owns_; 394 __u.__m_ = nullptr; 395 __u.__owns_ = false; 396 return *this; 397 } 398 399 void lock(); 400 bool try_lock(); 401 template <class Rep, class Period> 402 bool try_lock_for(const chrono::duration<Rep, Period>& rel_time); 403 template <class Clock, class Duration> 404 bool try_lock_until(const chrono::time_point<Clock, Duration>& abs_time); 405 void unlock(); 406 407 // Setters 408 _LIBCPP_INLINE_VISIBILITY 409 void swap(shared_lock& __u) _NOEXCEPT 410 { 411 _VSTD::swap(__m_, __u.__m_); 412 _VSTD::swap(__owns_, __u.__owns_); 413 } 414 415 _LIBCPP_INLINE_VISIBILITY 416 mutex_type* release() _NOEXCEPT 417 { 418 mutex_type* __m = __m_; 419 __m_ = nullptr; 420 __owns_ = false; 421 return __m; 422 } 423 424 // Getters 425 _LIBCPP_INLINE_VISIBILITY 426 bool owns_lock() const _NOEXCEPT {return __owns_;} 427 428 _LIBCPP_INLINE_VISIBILITY 429 explicit operator bool () const _NOEXCEPT {return __owns_;} 430 431 _LIBCPP_INLINE_VISIBILITY 432 mutex_type* mutex() const _NOEXCEPT {return __m_;} 433}; 434 435template <class _Mutex> 436void 437shared_lock<_Mutex>::lock() 438{ 439 if (__m_ == nullptr) 440 __throw_system_error(EPERM, "shared_lock::lock: references null mutex"); 441 if (__owns_) 442 __throw_system_error(EDEADLK, "shared_lock::lock: already locked"); 443 __m_->lock_shared(); 444 __owns_ = true; 445} 446 447template <class _Mutex> 448bool 449shared_lock<_Mutex>::try_lock() 450{ 451 if (__m_ == nullptr) 452 __throw_system_error(EPERM, "shared_lock::try_lock: references null mutex"); 453 if (__owns_) 454 __throw_system_error(EDEADLK, "shared_lock::try_lock: already locked"); 455 __owns_ = __m_->try_lock_shared(); 456 return __owns_; 457} 458 459template <class _Mutex> 460template <class _Rep, class _Period> 461bool 462shared_lock<_Mutex>::try_lock_for(const chrono::duration<_Rep, _Period>& __d) 463{ 464 if (__m_ == nullptr) 465 __throw_system_error(EPERM, "shared_lock::try_lock_for: references null mutex"); 466 if (__owns_) 467 __throw_system_error(EDEADLK, "shared_lock::try_lock_for: already locked"); 468 __owns_ = __m_->try_lock_shared_for(__d); 469 return __owns_; 470} 471 472template <class _Mutex> 473template <class _Clock, class _Duration> 474bool 475shared_lock<_Mutex>::try_lock_until(const chrono::time_point<_Clock, _Duration>& __t) 476{ 477 if (__m_ == nullptr) 478 __throw_system_error(EPERM, "shared_lock::try_lock_until: references null mutex"); 479 if (__owns_) 480 __throw_system_error(EDEADLK, "shared_lock::try_lock_until: already locked"); 481 __owns_ = __m_->try_lock_shared_until(__t); 482 return __owns_; 483} 484 485template <class _Mutex> 486void 487shared_lock<_Mutex>::unlock() 488{ 489 if (!__owns_) 490 __throw_system_error(EPERM, "shared_lock::unlock: not locked"); 491 __m_->unlock_shared(); 492 __owns_ = false; 493} 494 495template <class _Mutex> 496inline _LIBCPP_INLINE_VISIBILITY 497void 498swap(shared_lock<_Mutex>& __x, shared_lock<_Mutex>& __y) _NOEXCEPT 499 {__x.swap(__y);} 500 501_LIBCPP_END_NAMESPACE_STD 502 503#endif // !_LIBCPP_HAS_NO_THREADS 504 505#endif // _LIBCPP_STD_VER > 11 506 507_LIBCPP_POP_MACROS 508 509#endif // _LIBCPP_SHARED_MUTEX 510