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_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#if __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
122# include <__cxx03/condition_variable>
123#else
124# include <__chrono/duration.h>
125# include <__chrono/steady_clock.h>
126# include <__chrono/time_point.h>
127# include <__condition_variable/condition_variable.h>
128# include <__config>
129# include <__memory/shared_ptr.h>
130# include <__mutex/lock_guard.h>
131# include <__mutex/mutex.h>
132# include <__mutex/tag_types.h>
133# include <__mutex/unique_lock.h>
134# include <__stop_token/stop_callback.h>
135# include <__stop_token/stop_token.h>
136# include <__utility/move.h>
137# include <version>
138
139# if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
140# pragma GCC system_header
141# endif
142
143_LIBCPP_PUSH_MACROS
144# include <__undef_macros>
145
146# if _LIBCPP_HAS_THREADS
147
148_LIBCPP_BEGIN_NAMESPACE_STD
149
150template <class _Lock>
151struct __unlock_guard {
152 _Lock& __lock_;
153
154 _LIBCPP_HIDE_FROM_ABI __unlock_guard(_Lock& __lock) : __lock_(__lock) { __lock_.unlock(); }
155
156 _LIBCPP_HIDE_FROM_ABI ~__unlock_guard() _NOEXCEPT // turns exception to std::terminate
157 {
158 __lock_.lock();
159 }
160
161 __unlock_guard(const __unlock_guard&) = delete;
162 __unlock_guard& operator=(const __unlock_guard&) = delete;
163};
164
165class _LIBCPP_EXPORTED_FROM_ABI condition_variable_any {
166 condition_variable __cv_;
167 shared_ptr<mutex> __mut_;
168
169public:
170 _LIBCPP_HIDE_FROM_ABI condition_variable_any();
171
172 _LIBCPP_HIDE_FROM_ABI void notify_one() _NOEXCEPT;
173 _LIBCPP_HIDE_FROM_ABI void notify_all() _NOEXCEPT;
174
175 template <class _Lock>
176 _LIBCPP_HIDE_FROM_ABI void wait(_Lock& __lock) {
177 shared_ptr<mutex> __mut = __mut_;
178 unique_lock<mutex> __lk(*__mut);
179 __unlock_guard<_Lock> __unlock(__lock);
180 lock_guard<unique_lock<mutex> > __lx(__lk, adopt_lock_t());
181 __cv_.wait(__lk);
182 } // __mut_.unlock(), __lock.lock()
183
184 template <class _Lock, class _Predicate>
185 _LIBCPP_HIDE_FROM_ABI void wait(_Lock& __lock, _Predicate __pred);
186
187 template <class _Lock, class _Clock, class _Duration>
188 _LIBCPP_HIDE_FROM_ABI cv_status wait_until(_Lock& __lock, const chrono::time_point<_Clock, _Duration>& __t) {
189 shared_ptr<mutex> __mut = __mut_;
190 unique_lock<mutex> __lk(*__mut);
191 __unlock_guard<_Lock> __unlock(__lock);
192 lock_guard<unique_lock<mutex> > __lx(__lk, adopt_lock_t());
193 return __cv_.wait_until(__lk, __t);
194 } // __mut_.unlock(), __lock.lock()
195
196 template <class _Lock, class _Clock, class _Duration, class _Predicate>
197 bool _LIBCPP_HIDE_FROM_ABI
198 wait_until(_Lock& __lock, const chrono::time_point<_Clock, _Duration>& __t, _Predicate __pred);
199
200 template <class _Lock, class _Rep, class _Period>
201 cv_status _LIBCPP_HIDE_FROM_ABI wait_for(_Lock& __lock, const chrono::duration<_Rep, _Period>& __d);
202
203 template <class _Lock, class _Rep, class _Period, class _Predicate>
204 bool _LIBCPP_HIDE_FROM_ABI wait_for(_Lock& __lock, const chrono::duration<_Rep, _Period>& __d, _Predicate __pred);
205
206# if _LIBCPP_STD_VER >= 20
207
208 template <class _Lock, class _Predicate>
209 _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI bool wait(_Lock& __lock, stop_token __stoken, _Predicate __pred);
210
211 template <class _Lock, class _Clock, class _Duration, class _Predicate>
212 _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI bool wait_until(
213 _Lock& __lock, stop_token __stoken, const chrono::time_point<_Clock, _Duration>& __abs_time, _Predicate __pred);
214
215 template <class _Lock, class _Rep, class _Period, class _Predicate>
216 _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI bool
217 wait_for(_Lock& __lock, stop_token __stoken, const chrono::duration<_Rep, _Period>& __rel_time, _Predicate __pred);
218
219# endif // _LIBCPP_STD_VER >= 20
220};
221
222inline condition_variable_any::condition_variable_any() : __mut_(make_shared<mutex>()) {}
223
224inline void condition_variable_any::notify_one() _NOEXCEPT {
225 { lock_guard<mutex> __lx(*__mut_); }
226 __cv_.notify_one();
227}
228
229inline void condition_variable_any::notify_all() _NOEXCEPT {
230 { lock_guard<mutex> __lx(*__mut_); }
231 __cv_.notify_all();
232}
233
234template <class _Lock, class _Predicate>
235inline void condition_variable_any::wait(_Lock& __lock, _Predicate __pred) {
236 while (!__pred())
237 wait(__lock);
238}
239
240template <class _Lock, class _Clock, class _Duration, class _Predicate>
241inline bool
242condition_variable_any::wait_until(_Lock& __lock, const chrono::time_point<_Clock, _Duration>& __t, _Predicate __pred) {
243 while (!__pred())
244 if (wait_until(__lock, __t) == cv_status::timeout)
245 return __pred();
246 return true;
247}
248
249template <class _Lock, class _Rep, class _Period>
250inline cv_status condition_variable_any::wait_for(_Lock& __lock, const chrono::duration<_Rep, _Period>& __d) {
251 return wait_until(__lock, chrono::steady_clock::now() + __d);
252}
253
254template <class _Lock, class _Rep, class _Period, class _Predicate>
255inline bool
256condition_variable_any::wait_for(_Lock& __lock, const chrono::duration<_Rep, _Period>& __d, _Predicate __pred) {
257 return wait_until(__lock, chrono::steady_clock::now() + __d, std::move(__pred));
258}
259
260# if _LIBCPP_STD_VER >= 20
261
262template <class _Lock, class _Predicate>
263bool condition_variable_any::wait(_Lock& __user_lock, stop_token __stoken, _Predicate __pred) {
264 if (__stoken.stop_requested())
265 return __pred();
266
267 // Per https://eel.is/c++draft/thread.condition.condvarany#general-note-2,
268 // we do need to take a copy of the shared pointer __mut_
269 // This ensures that a thread can call the destructor immediately after calling
270 // notify_all, without waiting all the wait calls.
271 // A thread can also safely call the destructor immediately after calling
272 // request_stop, as the call to request_stop would evaluate the callback,
273 // which accesses the internal condition variable, immediately on the same thread.
274 // In this situation, it is OK even without copying a shared ownership the internal
275 // condition variable. However, this needs the evaluation of stop_callback to
276 // happen-before the destruction.
277 // The spec only says "Only the notification to unblock the wait needs to happen
278 // before destruction". To make this work, we need to copy the shared ownership of
279 // the internal condition variable inside this function, which is not possible
280 // with the current ABI.
281 shared_ptr<mutex> __mut = __mut_;
282
283 stop_callback __cb(__stoken, [this] { notify_all(); });
284
285 while (true) {
286 if (__pred())
287 return true;
288
289 // We need to take the internal lock before checking stop_requested,
290 // so that the notification cannot come in between the stop_requested
291 // check and entering the wait.
292 // Note that the stop_callback takes the same internal lock before notifying
293 unique_lock<mutex> __internal_lock(*__mut);
294 if (__stoken.stop_requested())
295 break;
296
297 __unlock_guard<_Lock> __unlock(__user_lock);
298 unique_lock<mutex> __internal_lock2(
299 std::move(__internal_lock)); // switch unlock order between __internal_lock and __user_lock
300 __cv_.wait(__internal_lock2);
301 } // __internal_lock2.unlock(), __user_lock.lock()
302 return __pred();
303}
304
305template <class _Lock, class _Clock, class _Duration, class _Predicate>
306bool condition_variable_any::wait_until(
307 _Lock& __user_lock,
308 stop_token __stoken,
309 const chrono::time_point<_Clock, _Duration>& __abs_time,
310 _Predicate __pred) {
311 if (__stoken.stop_requested())
312 return __pred();
313
314 shared_ptr<mutex> __mut = __mut_;
315 stop_callback __cb(__stoken, [this] { notify_all(); });
316
317 while (true) {
318 if (__pred())
319 return true;
320
321 unique_lock<mutex> __internal_lock(*__mut);
322 if (__stoken.stop_requested())
323 break;
324
325 __unlock_guard<_Lock> __unlock(__user_lock);
326 unique_lock<mutex> __internal_lock2(
327 std::move(__internal_lock)); // switch unlock order between __internal_lock and __user_lock
328
329 if (__cv_.wait_until(__internal_lock2, __abs_time) == cv_status::timeout)
330 break;
331 } // __internal_lock2.unlock(), __user_lock.lock()
332 return __pred();
333}
334
335template <class _Lock, class _Rep, class _Period, class _Predicate>
336bool condition_variable_any::wait_for(
337 _Lock& __lock, stop_token __stoken, const chrono::duration<_Rep, _Period>& __rel_time, _Predicate __pred) {
338 return wait_until(__lock, std::move(__stoken), chrono::steady_clock::now() + __rel_time, std::move(__pred));
339}
340
341# endif // _LIBCPP_STD_VER >= 20
342
343_LIBCPP_EXPORTED_FROM_ABI void notify_all_at_thread_exit(condition_variable&, unique_lock<mutex>);
344
345_LIBCPP_END_NAMESPACE_STD
346
347# endif // _LIBCPP_HAS_THREADS
348
349_LIBCPP_POP_MACROS
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 <optional>
361# include <stdexcept>
362# include <system_error>
363# include <type_traits>
364# include <typeinfo>
365# endif
366#endif // __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
367
368#endif // _LIBCPP_CONDITION_VARIABLE