xref: /freebsd/contrib/llvm-project/libcxx/include/condition_variable (revision a90b9d0159070121c221b966469c3e36d912bf82)
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#include <__assert> // all public C++ headers provide the assertion handler
122#include <__availability>
123#include <__chrono/duration.h>
124#include <__chrono/steady_clock.h>
125#include <__chrono/time_point.h>
126#include <__condition_variable/condition_variable.h>
127#include <__config>
128#include <__memory/shared_ptr.h>
129#include <__mutex/lock_guard.h>
130#include <__mutex/mutex.h>
131#include <__mutex/tag_types.h>
132#include <__mutex/unique_lock.h>
133#include <__stop_token/stop_callback.h>
134#include <__stop_token/stop_token.h>
135#include <__utility/move.h>
136#include <version>
137
138#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
139#  pragma GCC system_header
140#endif
141
142_LIBCPP_PUSH_MACROS
143#include <__undef_macros>
144
145#ifndef _LIBCPP_HAS_NO_THREADS
146
147_LIBCPP_BEGIN_NAMESPACE_STD
148
149class _LIBCPP_EXPORTED_FROM_ABI condition_variable_any {
150  condition_variable __cv_;
151  shared_ptr<mutex> __mut_;
152
153public:
154  _LIBCPP_HIDE_FROM_ABI condition_variable_any();
155
156  _LIBCPP_HIDE_FROM_ABI void notify_one() _NOEXCEPT;
157  _LIBCPP_HIDE_FROM_ABI void notify_all() _NOEXCEPT;
158
159  template <class _Lock>
160  _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS void wait(_Lock& __lock);
161  template <class _Lock, class _Predicate>
162  _LIBCPP_HIDE_FROM_ABI void wait(_Lock& __lock, _Predicate __pred);
163
164  template <class _Lock, class _Clock, class _Duration>
165  _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS cv_status
166  wait_until(_Lock& __lock, const chrono::time_point<_Clock, _Duration>& __t);
167
168  template <class _Lock, class _Clock, class _Duration, class _Predicate>
169  bool _LIBCPP_HIDE_FROM_ABI
170  wait_until(_Lock& __lock, const chrono::time_point<_Clock, _Duration>& __t, _Predicate __pred);
171
172  template <class _Lock, class _Rep, class _Period>
173  cv_status _LIBCPP_HIDE_FROM_ABI wait_for(_Lock& __lock, const chrono::duration<_Rep, _Period>& __d);
174
175  template <class _Lock, class _Rep, class _Period, class _Predicate>
176  bool _LIBCPP_HIDE_FROM_ABI wait_for(_Lock& __lock, const chrono::duration<_Rep, _Period>& __d, _Predicate __pred);
177
178#  if _LIBCPP_STD_VER >= 20 && !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_STOP_TOKEN)
179
180  template <class _Lock, class _Predicate>
181  _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI bool wait(_Lock& __lock, stop_token __stoken, _Predicate __pred);
182
183  template <class _Lock, class _Clock, class _Duration, class _Predicate>
184  _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI bool wait_until(
185      _Lock& __lock, stop_token __stoken, const chrono::time_point<_Clock, _Duration>& __abs_time, _Predicate __pred);
186
187  template <class _Lock, class _Rep, class _Period, class _Predicate>
188  _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI bool
189  wait_for(_Lock& __lock, stop_token __stoken, const chrono::duration<_Rep, _Period>& __rel_time, _Predicate __pred);
190
191#  endif // _LIBCPP_STD_VER >= 20 && !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_STOP_TOKEN)
192};
193
194inline condition_variable_any::condition_variable_any() : __mut_(make_shared<mutex>()) {}
195
196inline void condition_variable_any::notify_one() _NOEXCEPT {
197  { lock_guard<mutex> __lx(*__mut_); }
198  __cv_.notify_one();
199}
200
201inline void condition_variable_any::notify_all() _NOEXCEPT {
202  { lock_guard<mutex> __lx(*__mut_); }
203  __cv_.notify_all();
204}
205
206template <class _Lock>
207struct __unlock_guard {
208  _Lock& __lock_;
209
210  _LIBCPP_HIDE_FROM_ABI __unlock_guard(_Lock& __lock) : __lock_(__lock) { __lock_.unlock(); }
211
212  _LIBCPP_HIDE_FROM_ABI ~__unlock_guard() _NOEXCEPT // turns exception to std::terminate
213  {
214    __lock_.lock();
215  }
216
217  __unlock_guard(const __unlock_guard&)            = delete;
218  __unlock_guard& operator=(const __unlock_guard&) = delete;
219};
220
221template <class _Lock>
222void condition_variable_any::wait(_Lock& __lock) {
223  shared_ptr<mutex> __mut = __mut_;
224  unique_lock<mutex> __lk(*__mut);
225  __unlock_guard<_Lock> __unlock(__lock);
226  lock_guard<unique_lock<mutex> > __lx(__lk, adopt_lock_t());
227  __cv_.wait(__lk);
228} // __mut_.unlock(), __lock.lock()
229
230template <class _Lock, class _Predicate>
231inline void condition_variable_any::wait(_Lock& __lock, _Predicate __pred) {
232  while (!__pred())
233    wait(__lock);
234}
235
236template <class _Lock, class _Clock, class _Duration>
237cv_status condition_variable_any::wait_until(_Lock& __lock, const chrono::time_point<_Clock, _Duration>& __t) {
238  shared_ptr<mutex> __mut = __mut_;
239  unique_lock<mutex> __lk(*__mut);
240  __unlock_guard<_Lock> __unlock(__lock);
241  lock_guard<unique_lock<mutex> > __lx(__lk, adopt_lock_t());
242  return __cv_.wait_until(__lk, __t);
243} // __mut_.unlock(), __lock.lock()
244
245template <class _Lock, class _Clock, class _Duration, class _Predicate>
246inline bool
247condition_variable_any::wait_until(_Lock& __lock, const chrono::time_point<_Clock, _Duration>& __t, _Predicate __pred) {
248  while (!__pred())
249    if (wait_until(__lock, __t) == cv_status::timeout)
250      return __pred();
251  return true;
252}
253
254template <class _Lock, class _Rep, class _Period>
255inline cv_status condition_variable_any::wait_for(_Lock& __lock, const chrono::duration<_Rep, _Period>& __d) {
256  return wait_until(__lock, chrono::steady_clock::now() + __d);
257}
258
259template <class _Lock, class _Rep, class _Period, class _Predicate>
260inline bool
261condition_variable_any::wait_for(_Lock& __lock, const chrono::duration<_Rep, _Period>& __d, _Predicate __pred) {
262  return wait_until(__lock, chrono::steady_clock::now() + __d, std::move(__pred));
263}
264
265#  if _LIBCPP_STD_VER >= 20 && !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_STOP_TOKEN)
266
267template <class _Lock, class _Predicate>
268bool condition_variable_any::wait(_Lock& __user_lock, stop_token __stoken, _Predicate __pred) {
269  if (__stoken.stop_requested())
270    return __pred();
271
272  // Per https://eel.is/c++draft/thread.condition.condvarany#general-note-2,
273  // we do need to take a copy of the shared pointer __mut_
274  // This ensures that a thread can call the destructor immediately after calling
275  // notify_all, without waiting all the wait calls.
276  // A thread can also safely call the destructor immediately after calling
277  // request_stop, as the call to request_stop would evaluate the callback,
278  // which accesses the internal condition variable, immediately on the same thread.
279  // In this situation, it is OK even without copying a shared ownership the internal
280  // condition variable. However, this needs the evaluation of stop_callback to
281  // happen-before the destruction.
282  // The spec only says "Only the notification to unblock the wait needs to happen
283  // before destruction". To make this work, we need to copy the shared ownership of
284  // the internal condition variable inside this function, which is not possible
285  // with the current ABI.
286  shared_ptr<mutex> __mut = __mut_;
287
288  stop_callback __cb(__stoken, [this] { notify_all(); });
289
290  while (true) {
291    if (__pred())
292      return true;
293
294    // We need to take the internal lock before checking stop_requested,
295    // so that the notification cannot come in between the stop_requested
296    // check and entering the wait.
297    // Note that the stop_callback takes the same internal lock before notifying
298    unique_lock<mutex> __internal_lock(*__mut);
299    if (__stoken.stop_requested())
300      break;
301
302    __unlock_guard<_Lock> __unlock(__user_lock);
303    unique_lock<mutex> __internal_lock2(
304        std::move(__internal_lock)); // switch unlock order between __internal_lock and __user_lock
305    __cv_.wait(__internal_lock2);
306  } // __internal_lock2.unlock(), __user_lock.lock()
307  return __pred();
308}
309
310template <class _Lock, class _Clock, class _Duration, class _Predicate>
311bool condition_variable_any::wait_until(
312    _Lock& __user_lock,
313    stop_token __stoken,
314    const chrono::time_point<_Clock, _Duration>& __abs_time,
315    _Predicate __pred) {
316  if (__stoken.stop_requested())
317    return __pred();
318
319  shared_ptr<mutex> __mut = __mut_;
320  stop_callback __cb(__stoken, [this] { notify_all(); });
321
322  while (true) {
323    if (__pred())
324      return true;
325
326    unique_lock<mutex> __internal_lock(*__mut);
327    if (__stoken.stop_requested())
328      break;
329
330    __unlock_guard<_Lock> __unlock(__user_lock);
331    unique_lock<mutex> __internal_lock2(
332        std::move(__internal_lock)); // switch unlock order between __internal_lock and __user_lock
333
334    if (__cv_.wait_until(__internal_lock2, __abs_time) == cv_status::timeout)
335      break;
336  } // __internal_lock2.unlock(), __user_lock.lock()
337  return __pred();
338}
339
340template <class _Lock, class _Rep, class _Period, class _Predicate>
341bool condition_variable_any::wait_for(
342    _Lock& __lock, stop_token __stoken, const chrono::duration<_Rep, _Period>& __rel_time, _Predicate __pred) {
343  return wait_until(__lock, std::move(__stoken), chrono::steady_clock::now() + __rel_time, std::move(__pred));
344}
345
346#  endif // _LIBCPP_STD_VER >= 20 && !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_STOP_TOKEN)
347
348_LIBCPP_EXPORTED_FROM_ABI void notify_all_at_thread_exit(condition_variable&, unique_lock<mutex>);
349
350_LIBCPP_END_NAMESPACE_STD
351
352#endif // !_LIBCPP_HAS_NO_THREADS
353
354_LIBCPP_POP_MACROS
355
356#if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
357#  include <atomic>
358#  include <concepts>
359#  include <cstdint>
360#  include <cstdlib>
361#  include <cstring>
362#  include <initializer_list>
363#  include <iosfwd>
364#  include <new>
365#  include <stdexcept>
366#  include <system_error>
367#  include <type_traits>
368#  include <typeinfo>
369#endif
370
371#endif // _LIBCPP_CONDITION_VARIABLE
372