master
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#if __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
126# include <__cxx03/__config>
127#else
128# include <__config>
129
130# if _LIBCPP_HAS_THREADS
131
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/throw_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_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_ACQUIRE_CAPABILITY() _LIBCPP_HIDE_FROM_ABI void lock() { return __base_.lock(); }
198 _LIBCPP_TRY_ACQUIRE_CAPABILITY(true) _LIBCPP_HIDE_FROM_ABI bool try_lock() { return __base_.try_lock(); }
199 _LIBCPP_RELEASE_CAPABILITY _LIBCPP_HIDE_FROM_ABI void unlock() { return __base_.unlock(); }
200
201 // Shared ownership
202 _LIBCPP_ACQUIRE_SHARED_CAPABILITY _LIBCPP_HIDE_FROM_ABI void lock_shared() { return __base_.lock_shared(); }
203 _LIBCPP_TRY_ACQUIRE_SHARED_CAPABILITY(true) _LIBCPP_HIDE_FROM_ABI bool try_lock_shared() {
204 return __base_.try_lock_shared();
205 }
206 _LIBCPP_RELEASE_SHARED_CAPABILITY _LIBCPP_HIDE_FROM_ABI void unlock_shared() { return __base_.unlock_shared(); }
207
208 // typedef __shared_mutex_base::native_handle_type native_handle_type;
209 // _LIBCPP_HIDE_FROM_ABI native_handle_type native_handle() { return __base::unlock_shared(); }
210};
211# endif
212
213class _LIBCPP_EXPORTED_FROM_ABI _LIBCPP_CAPABILITY("shared_timed_mutex") shared_timed_mutex {
214 __shared_mutex_base __base_;
215
216public:
217 shared_timed_mutex();
218 _LIBCPP_HIDE_FROM_ABI ~shared_timed_mutex() = default;
219
220 shared_timed_mutex(const shared_timed_mutex&) = delete;
221 shared_timed_mutex& operator=(const shared_timed_mutex&) = delete;
222
223 // Exclusive ownership
224 void lock() _LIBCPP_ACQUIRE_CAPABILITY();
225 _LIBCPP_TRY_ACQUIRE_CAPABILITY(true) bool try_lock();
226 template <class _Rep, class _Period>
227 _LIBCPP_TRY_ACQUIRE_CAPABILITY(true) _LIBCPP_HIDE_FROM_ABI bool
228 try_lock_for(const chrono::duration<_Rep, _Period>& __rel_time) {
229 return try_lock_until(chrono::steady_clock::now() + __rel_time);
230 }
231
232 template <class _Clock, class _Duration>
233 _LIBCPP_TRY_ACQUIRE_CAPABILITY(true) _LIBCPP_HIDE_FROM_ABI bool
234 try_lock_until(const chrono::time_point<_Clock, _Duration>& __abs_time) {
235 unique_lock<mutex> __lk(__base_.__mut_);
236 if (__base_.__state_ & __base_.__write_entered_) {
237 while (true) {
238 cv_status __status = __base_.__gate1_.wait_until(__lk, __abs_time);
239 if ((__base_.__state_ & __base_.__write_entered_) == 0)
240 break;
241 if (__status == cv_status::timeout)
242 return false;
243 }
244 }
245 __base_.__state_ |= __base_.__write_entered_;
246 if (__base_.__state_ & __base_.__n_readers_) {
247 while (true) {
248 cv_status __status = __base_.__gate2_.wait_until(__lk, __abs_time);
249 if ((__base_.__state_ & __base_.__n_readers_) == 0)
250 break;
251 if (__status == cv_status::timeout) {
252 __base_.__state_ &= ~__base_.__write_entered_;
253 __base_.__gate1_.notify_all();
254 return false;
255 }
256 }
257 }
258 return true;
259 }
260
261 _LIBCPP_RELEASE_CAPABILITY void unlock();
262
263 // Shared ownership
264 _LIBCPP_ACQUIRE_SHARED_CAPABILITY void lock_shared();
265 _LIBCPP_TRY_ACQUIRE_SHARED_CAPABILITY(true) bool try_lock_shared();
266 template <class _Rep, class _Period>
267 _LIBCPP_TRY_ACQUIRE_SHARED_CAPABILITY(true) _LIBCPP_HIDE_FROM_ABI bool
268 try_lock_shared_for(const chrono::duration<_Rep, _Period>& __rel_time) {
269 return try_lock_shared_until(chrono::steady_clock::now() + __rel_time);
270 }
271
272 template <class _Clock, class _Duration>
273 _LIBCPP_TRY_ACQUIRE_SHARED_CAPABILITY(true) _LIBCPP_HIDE_FROM_ABI bool
274 try_lock_shared_until(const chrono::time_point<_Clock, _Duration>& __abs_time) {
275 unique_lock<mutex> __lk(__base_.__mut_);
276 if ((__base_.__state_ & __base_.__write_entered_) ||
277 (__base_.__state_ & __base_.__n_readers_) == __base_.__n_readers_) {
278 while (true) {
279 cv_status __status = __base_.__gate1_.wait_until(__lk, __abs_time);
280 if ((__base_.__state_ & __base_.__write_entered_) == 0 &&
281 (__base_.__state_ & __base_.__n_readers_) < __base_.__n_readers_)
282 break;
283 if (__status == cv_status::timeout)
284 return false;
285 }
286 }
287 unsigned __num_readers = (__base_.__state_ & __base_.__n_readers_) + 1;
288 __base_.__state_ &= ~__base_.__n_readers_;
289 __base_.__state_ |= __num_readers;
290 return true;
291 }
292
293 _LIBCPP_RELEASE_SHARED_CAPABILITY void unlock_shared();
294};
295
296template <class _Mutex>
297class shared_lock {
298public:
299 typedef _Mutex mutex_type;
300
301private:
302 mutex_type* __m_;
303 bool __owns_;
304
305public:
306 _LIBCPP_HIDE_FROM_ABI shared_lock() _NOEXCEPT : __m_(nullptr), __owns_(false) {}
307
308 _LIBCPP_HIDE_FROM_ABI explicit shared_lock(mutex_type& __m) : __m_(std::addressof(__m)), __owns_(true) {
309 __m_->lock_shared();
310 }
311
312 _LIBCPP_HIDE_FROM_ABI shared_lock(mutex_type& __m, defer_lock_t) _NOEXCEPT
313 : __m_(std::addressof(__m)),
314 __owns_(false) {}
315
316 _LIBCPP_HIDE_FROM_ABI shared_lock(mutex_type& __m, try_to_lock_t)
317 : __m_(std::addressof(__m)), __owns_(__m.try_lock_shared()) {}
318
319 _LIBCPP_HIDE_FROM_ABI shared_lock(mutex_type& __m, adopt_lock_t) : __m_(std::addressof(__m)), __owns_(true) {}
320
321 template <class _Clock, class _Duration>
322 _LIBCPP_HIDE_FROM_ABI shared_lock(mutex_type& __m, const chrono::time_point<_Clock, _Duration>& __abs_time)
323 : __m_(std::addressof(__m)), __owns_(__m.try_lock_shared_until(__abs_time)) {}
324
325 template <class _Rep, class _Period>
326 _LIBCPP_HIDE_FROM_ABI shared_lock(mutex_type& __m, const chrono::duration<_Rep, _Period>& __rel_time)
327 : __m_(std::addressof(__m)), __owns_(__m.try_lock_shared_for(__rel_time)) {}
328
329 _LIBCPP_HIDE_FROM_ABI ~shared_lock() {
330 if (__owns_)
331 __m_->unlock_shared();
332 }
333
334 shared_lock(shared_lock const&) = delete;
335 shared_lock& operator=(shared_lock const&) = delete;
336
337 _LIBCPP_HIDE_FROM_ABI shared_lock(shared_lock&& __u) _NOEXCEPT : __m_(__u.__m_), __owns_(__u.__owns_) {
338 __u.__m_ = nullptr;
339 __u.__owns_ = false;
340 }
341
342 _LIBCPP_HIDE_FROM_ABI shared_lock& operator=(shared_lock&& __u) _NOEXCEPT {
343 if (__owns_)
344 __m_->unlock_shared();
345 __m_ = nullptr;
346 __owns_ = false;
347 __m_ = __u.__m_;
348 __owns_ = __u.__owns_;
349 __u.__m_ = nullptr;
350 __u.__owns_ = false;
351 return *this;
352 }
353
354 _LIBCPP_HIDE_FROM_ABI void lock();
355 _LIBCPP_HIDE_FROM_ABI bool try_lock();
356 template <class _Rep, class _Period>
357 _LIBCPP_HIDE_FROM_ABI bool try_lock_for(const chrono::duration<_Rep, _Period>& __rel_time);
358 template <class _Clock, class _Duration>
359 _LIBCPP_HIDE_FROM_ABI bool try_lock_until(const chrono::time_point<_Clock, _Duration>& __abs_time);
360 _LIBCPP_HIDE_FROM_ABI void unlock();
361
362 // Setters
363 _LIBCPP_HIDE_FROM_ABI void swap(shared_lock& __u) _NOEXCEPT {
364 std::swap(__m_, __u.__m_);
365 std::swap(__owns_, __u.__owns_);
366 }
367
368 _LIBCPP_HIDE_FROM_ABI mutex_type* release() _NOEXCEPT {
369 mutex_type* __m = __m_;
370 __m_ = nullptr;
371 __owns_ = false;
372 return __m;
373 }
374
375 // Getters
376 _LIBCPP_HIDE_FROM_ABI bool owns_lock() const _NOEXCEPT { return __owns_; }
377
378 _LIBCPP_HIDE_FROM_ABI explicit operator bool() const _NOEXCEPT { return __owns_; }
379
380 _LIBCPP_HIDE_FROM_ABI mutex_type* mutex() const _NOEXCEPT { return __m_; }
381};
382_LIBCPP_CTAD_SUPPORTED_FOR_TYPE(shared_lock);
383
384template <class _Mutex>
385void shared_lock<_Mutex>::lock() {
386 if (__m_ == nullptr)
387 std::__throw_system_error(EPERM, "shared_lock::lock: references null mutex");
388 if (__owns_)
389 std::__throw_system_error(EDEADLK, "shared_lock::lock: already locked");
390 __m_->lock_shared();
391 __owns_ = true;
392}
393
394template <class _Mutex>
395bool shared_lock<_Mutex>::try_lock() {
396 if (__m_ == nullptr)
397 std::__throw_system_error(EPERM, "shared_lock::try_lock: references null mutex");
398 if (__owns_)
399 std::__throw_system_error(EDEADLK, "shared_lock::try_lock: already locked");
400 __owns_ = __m_->try_lock_shared();
401 return __owns_;
402}
403
404template <class _Mutex>
405template <class _Rep, class _Period>
406bool shared_lock<_Mutex>::try_lock_for(const chrono::duration<_Rep, _Period>& __d) {
407 if (__m_ == nullptr)
408 std::__throw_system_error(EPERM, "shared_lock::try_lock_for: references null mutex");
409 if (__owns_)
410 std::__throw_system_error(EDEADLK, "shared_lock::try_lock_for: already locked");
411 __owns_ = __m_->try_lock_shared_for(__d);
412 return __owns_;
413}
414
415template <class _Mutex>
416template <class _Clock, class _Duration>
417bool shared_lock<_Mutex>::try_lock_until(const chrono::time_point<_Clock, _Duration>& __t) {
418 if (__m_ == nullptr)
419 std::__throw_system_error(EPERM, "shared_lock::try_lock_until: references null mutex");
420 if (__owns_)
421 std::__throw_system_error(EDEADLK, "shared_lock::try_lock_until: already locked");
422 __owns_ = __m_->try_lock_shared_until(__t);
423 return __owns_;
424}
425
426template <class _Mutex>
427void shared_lock<_Mutex>::unlock() {
428 if (!__owns_)
429 std::__throw_system_error(EPERM, "shared_lock::unlock: not locked");
430 __m_->unlock_shared();
431 __owns_ = false;
432}
433
434template <class _Mutex>
435inline _LIBCPP_HIDE_FROM_ABI void swap(shared_lock<_Mutex>& __x, shared_lock<_Mutex>& __y) _NOEXCEPT {
436 __x.swap(__y);
437}
438
439_LIBCPP_END_NAMESPACE_STD
440
441# endif // _LIBCPP_STD_VER >= 14
442
443_LIBCPP_POP_MACROS
444
445# endif // _LIBCPP_HAS_THREADS
446
447# if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
448# include <optional>
449# include <system_error>
450# endif
451#endif // __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
452
453#endif // _LIBCPP_SHARED_MUTEX