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_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
225_LIBCPP_THREAD_SAFETY_ANNOTATION(__capability__("shared_timed_mutex")) 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
244 template <class _Clock, class _Duration>
245 _LIBCPP_HIDE_FROM_ABI bool try_lock_until(const chrono::time_point<_Clock, _Duration>& __abs_time)
246 _LIBCPP_THREAD_SAFETY_ANNOTATION(__try_acquire_capability__(true)) {
247 unique_lock<mutex> __lk(__base_.__mut_);
248 if (__base_.__state_ & __base_.__write_entered_) {
249 while (true) {
250 cv_status __status = __base_.__gate1_.wait_until(__lk, __abs_time);
251 if ((__base_.__state_ & __base_.__write_entered_) == 0)
252 break;
253 if (__status == cv_status::timeout)
254 return false;
255 }
256 }
257 __base_.__state_ |= __base_.__write_entered_;
258 if (__base_.__state_ & __base_.__n_readers_) {
259 while (true) {
260 cv_status __status = __base_.__gate2_.wait_until(__lk, __abs_time);
261 if ((__base_.__state_ & __base_.__n_readers_) == 0)
262 break;
263 if (__status == cv_status::timeout) {
264 __base_.__state_ &= ~__base_.__write_entered_;
265 __base_.__gate1_.notify_all();
266 return false;
267 }
268 }
269 }
270 return true;
271 }
272
273 void unlock() _LIBCPP_THREAD_SAFETY_ANNOTATION(__release_capability__());
274
275 // Shared ownership
276 void lock_shared() _LIBCPP_THREAD_SAFETY_ANNOTATION(__acquire_shared_capability__());
277 bool try_lock_shared() _LIBCPP_THREAD_SAFETY_ANNOTATION(__try_acquire_shared_capability__(true));
278 template <class _Rep, class _Period>
279 _LIBCPP_HIDE_FROM_ABI bool try_lock_shared_for(const chrono::duration<_Rep, _Period>& __rel_time)
280 _LIBCPP_THREAD_SAFETY_ANNOTATION(__try_acquire_shared_capability__(true)) {
281 return try_lock_shared_until(chrono::steady_clock::now() + __rel_time);
282 }
283
284 template <class _Clock, class _Duration>
285 _LIBCPP_HIDE_FROM_ABI bool try_lock_shared_until(const chrono::time_point<_Clock, _Duration>& __abs_time)
286 _LIBCPP_THREAD_SAFETY_ANNOTATION(__try_acquire_shared_capability__(true)) {
287 unique_lock<mutex> __lk(__base_.__mut_);
288 if ((__base_.__state_ & __base_.__write_entered_) ||
289 (__base_.__state_ & __base_.__n_readers_) == __base_.__n_readers_) {
290 while (true) {
291 cv_status __status = __base_.__gate1_.wait_until(__lk, __abs_time);
292 if ((__base_.__state_ & __base_.__write_entered_) == 0 &&
293 (__base_.__state_ & __base_.__n_readers_) < __base_.__n_readers_)
294 break;
295 if (__status == cv_status::timeout)
296 return false;
297 }
298 }
299 unsigned __num_readers = (__base_.__state_ & __base_.__n_readers_) + 1;
300 __base_.__state_ &= ~__base_.__n_readers_;
301 __base_.__state_ |= __num_readers;
302 return true;
303 }
304
305 void unlock_shared() _LIBCPP_THREAD_SAFETY_ANNOTATION(__release_shared_capability__());
306};
307
308template <class _Mutex>
309class shared_lock {
310public:
311 typedef _Mutex mutex_type;
312
313private:
314 mutex_type* __m_;
315 bool __owns_;
316
317public:
318 _LIBCPP_HIDE_FROM_ABI shared_lock() _NOEXCEPT : __m_(nullptr), __owns_(false) {}
319
320 _LIBCPP_HIDE_FROM_ABI explicit shared_lock(mutex_type& __m) : __m_(std::addressof(__m)), __owns_(true) {
321 __m_->lock_shared();
322 }
323
324 _LIBCPP_HIDE_FROM_ABI shared_lock(mutex_type& __m, defer_lock_t) _NOEXCEPT
325 : __m_(std::addressof(__m)),
326 __owns_(false) {}
327
328 _LIBCPP_HIDE_FROM_ABI shared_lock(mutex_type& __m, try_to_lock_t)
329 : __m_(std::addressof(__m)), __owns_(__m.try_lock_shared()) {}
330
331 _LIBCPP_HIDE_FROM_ABI shared_lock(mutex_type& __m, adopt_lock_t) : __m_(std::addressof(__m)), __owns_(true) {}
332
333 template <class _Clock, class _Duration>
334 _LIBCPP_HIDE_FROM_ABI shared_lock(mutex_type& __m, const chrono::time_point<_Clock, _Duration>& __abs_time)
335 : __m_(std::addressof(__m)), __owns_(__m.try_lock_shared_until(__abs_time)) {}
336
337 template <class _Rep, class _Period>
338 _LIBCPP_HIDE_FROM_ABI shared_lock(mutex_type& __m, const chrono::duration<_Rep, _Period>& __rel_time)
339 : __m_(std::addressof(__m)), __owns_(__m.try_lock_shared_for(__rel_time)) {}
340
341 _LIBCPP_HIDE_FROM_ABI ~shared_lock() {
342 if (__owns_)
343 __m_->unlock_shared();
344 }
345
346 shared_lock(shared_lock const&) = delete;
347 shared_lock& operator=(shared_lock const&) = delete;
348
349 _LIBCPP_HIDE_FROM_ABI shared_lock(shared_lock&& __u) _NOEXCEPT : __m_(__u.__m_), __owns_(__u.__owns_) {
350 __u.__m_ = nullptr;
351 __u.__owns_ = false;
352 }
353
354 _LIBCPP_HIDE_FROM_ABI shared_lock& operator=(shared_lock&& __u) _NOEXCEPT {
355 if (__owns_)
356 __m_->unlock_shared();
357 __m_ = nullptr;
358 __owns_ = false;
359 __m_ = __u.__m_;
360 __owns_ = __u.__owns_;
361 __u.__m_ = nullptr;
362 __u.__owns_ = false;
363 return *this;
364 }
365
366 _LIBCPP_HIDE_FROM_ABI void lock();
367 _LIBCPP_HIDE_FROM_ABI bool try_lock();
368 template <class _Rep, class _Period>
369 _LIBCPP_HIDE_FROM_ABI bool try_lock_for(const chrono::duration<_Rep, _Period>& __rel_time);
370 template <class _Clock, class _Duration>
371 _LIBCPP_HIDE_FROM_ABI bool try_lock_until(const chrono::time_point<_Clock, _Duration>& __abs_time);
372 _LIBCPP_HIDE_FROM_ABI void unlock();
373
374 // Setters
375 _LIBCPP_HIDE_FROM_ABI void swap(shared_lock& __u) _NOEXCEPT {
376 std::swap(__m_, __u.__m_);
377 std::swap(__owns_, __u.__owns_);
378 }
379
380 _LIBCPP_HIDE_FROM_ABI mutex_type* release() _NOEXCEPT {
381 mutex_type* __m = __m_;
382 __m_ = nullptr;
383 __owns_ = false;
384 return __m;
385 }
386
387 // Getters
388 _LIBCPP_HIDE_FROM_ABI bool owns_lock() const _NOEXCEPT { return __owns_; }
389
390 _LIBCPP_HIDE_FROM_ABI explicit operator bool() const _NOEXCEPT { return __owns_; }
391
392 _LIBCPP_HIDE_FROM_ABI mutex_type* mutex() const _NOEXCEPT { return __m_; }
393};
394_LIBCPP_CTAD_SUPPORTED_FOR_TYPE(shared_lock);
395
396template <class _Mutex>
397void shared_lock<_Mutex>::lock() {
398 if (__m_ == nullptr)
399 std::__throw_system_error(EPERM, what_arg: "shared_lock::lock: references null mutex");
400 if (__owns_)
401 std::__throw_system_error(EDEADLK, what_arg: "shared_lock::lock: already locked");
402 __m_->lock_shared();
403 __owns_ = true;
404}
405
406template <class _Mutex>
407bool shared_lock<_Mutex>::try_lock() {
408 if (__m_ == nullptr)
409 std::__throw_system_error(EPERM, what_arg: "shared_lock::try_lock: references null mutex");
410 if (__owns_)
411 std::__throw_system_error(EDEADLK, what_arg: "shared_lock::try_lock: already locked");
412 __owns_ = __m_->try_lock_shared();
413 return __owns_;
414}
415
416template <class _Mutex>
417template <class _Rep, class _Period>
418bool shared_lock<_Mutex>::try_lock_for(const chrono::duration<_Rep, _Period>& __d) {
419 if (__m_ == nullptr)
420 std::__throw_system_error(EPERM, what_arg: "shared_lock::try_lock_for: references null mutex");
421 if (__owns_)
422 std::__throw_system_error(EDEADLK, what_arg: "shared_lock::try_lock_for: already locked");
423 __owns_ = __m_->try_lock_shared_for(__d);
424 return __owns_;
425}
426
427template <class _Mutex>
428template <class _Clock, class _Duration>
429bool shared_lock<_Mutex>::try_lock_until(const chrono::time_point<_Clock, _Duration>& __t) {
430 if (__m_ == nullptr)
431 std::__throw_system_error(EPERM, what_arg: "shared_lock::try_lock_until: references null mutex");
432 if (__owns_)
433 std::__throw_system_error(EDEADLK, what_arg: "shared_lock::try_lock_until: already locked");
434 __owns_ = __m_->try_lock_shared_until(__t);
435 return __owns_;
436}
437
438template <class _Mutex>
439void shared_lock<_Mutex>::unlock() {
440 if (!__owns_)
441 std::__throw_system_error(EPERM, what_arg: "shared_lock::unlock: not locked");
442 __m_->unlock_shared();
443 __owns_ = false;
444}
445
446template <class _Mutex>
447inline _LIBCPP_HIDE_FROM_ABI void swap(shared_lock<_Mutex>& __x, shared_lock<_Mutex>& __y) _NOEXCEPT {
448 __x.swap(__y);
449}
450
451_LIBCPP_END_NAMESPACE_STD
452
453# endif // _LIBCPP_STD_VER >= 14
454
455_LIBCPP_POP_MACROS
456
457# endif // _LIBCPP_HAS_THREADS
458
459# if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
460# include <optional>
461# include <system_error>
462# endif
463#endif // __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
464
465#endif // _LIBCPP_SHARED_MUTEX
466