1// <condition_variable> -*- C++ -*-
2
3// Copyright (C) 2008-2020 Free Software Foundation, Inc.
4//
5// This file is part of the GNU ISO C++ Library.  This library is free
6// software; you can redistribute it and/or modify it under the
7// terms of the GNU General Public License as published by the
8// Free Software Foundation; either version 3, or (at your option)
9// any later version.
10
11// This library is distributed in the hope that it will be useful,
12// but WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14// GNU General Public License for more details.
15
16// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.
19
20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
23// <http://www.gnu.org/licenses/>.
24
25/** @file include/condition_variable
26 *  This is a Standard C++ Library header.
27 */
28
29#ifndef _GLIBCXX_CONDITION_VARIABLE
30#define _GLIBCXX_CONDITION_VARIABLE 1
31
32#pragma GCC system_header
33
34#if __cplusplus < 201103L
35# include <bits/c++0x_warning.h>
36#else
37
38#include <chrono>
39
40#include <bits/std_mutex.h>
41#include <bits/unique_lock.h>
42#include <ext/concurrence.h>
43#include <bits/alloc_traits.h>
44#include <bits/allocator.h>
45#include <bits/unique_ptr.h>
46#include <bits/shared_ptr.h>
47#include <bits/cxxabi_forced.h>
48
49#if __cplusplus > 201703L
50# include <stop_token>
51#endif
52
53#if defined(_GLIBCXX_HAS_GTHREADS)
54
55namespace std _GLIBCXX_VISIBILITY(default)
56{
57_GLIBCXX_BEGIN_NAMESPACE_VERSION
58
59  /**
60   * @defgroup condition_variables Condition Variables
61   * @ingroup concurrency
62   *
63   * Classes for condition_variable support.
64   * @{
65   */
66
67  /// cv_status
68  enum class cv_status { no_timeout, timeout };
69
70  /// condition_variable
71  class condition_variable
72  {
73    using steady_clock = chrono::steady_clock;
74    using system_clock = chrono::system_clock;
75#ifdef _GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT
76    using __clock_t = steady_clock;
77#else
78    using __clock_t = system_clock;
79#endif
80    typedef __gthread_cond_t		__native_type;
81
82#ifdef __GTHREAD_COND_INIT
83    __native_type			_M_cond = __GTHREAD_COND_INIT;
84#else
85    __native_type			_M_cond;
86#endif
87
88  public:
89    typedef __native_type* 		native_handle_type;
90
91    condition_variable() noexcept;
92    ~condition_variable() noexcept;
93
94    condition_variable(const condition_variable&) = delete;
95    condition_variable& operator=(const condition_variable&) = delete;
96
97    void
98    notify_one() noexcept;
99
100    void
101    notify_all() noexcept;
102
103    void
104    wait(unique_lock<mutex>& __lock) noexcept;
105
106    template<typename _Predicate>
107      void
108      wait(unique_lock<mutex>& __lock, _Predicate __p)
109      {
110	while (!__p())
111	  wait(__lock);
112      }
113
114#ifdef _GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT
115    template<typename _Duration>
116      cv_status
117      wait_until(unique_lock<mutex>& __lock,
118		 const chrono::time_point<steady_clock, _Duration>& __atime)
119      { return __wait_until_impl(__lock, __atime); }
120#endif
121
122    template<typename _Duration>
123      cv_status
124      wait_until(unique_lock<mutex>& __lock,
125		 const chrono::time_point<system_clock, _Duration>& __atime)
126      { return __wait_until_impl(__lock, __atime); }
127
128    template<typename _Clock, typename _Duration>
129      cv_status
130      wait_until(unique_lock<mutex>& __lock,
131		 const chrono::time_point<_Clock, _Duration>& __atime)
132      {
133#if __cplusplus > 201703L
134	static_assert(chrono::is_clock_v<_Clock>);
135#endif
136	const typename _Clock::time_point __c_entry = _Clock::now();
137	const __clock_t::time_point __s_entry = __clock_t::now();
138	const auto __delta = __atime - __c_entry;
139	const auto __s_atime = __s_entry + __delta;
140
141	if (__wait_until_impl(__lock, __s_atime) == cv_status::no_timeout)
142	  return cv_status::no_timeout;
143	// We got a timeout when measured against __clock_t but
144	// we need to check against the caller-supplied clock
145	// to tell whether we should return a timeout.
146	if (_Clock::now() < __atime)
147	  return cv_status::no_timeout;
148	return cv_status::timeout;
149      }
150
151    template<typename _Clock, typename _Duration, typename _Predicate>
152      bool
153      wait_until(unique_lock<mutex>& __lock,
154		 const chrono::time_point<_Clock, _Duration>& __atime,
155		 _Predicate __p)
156      {
157	while (!__p())
158	  if (wait_until(__lock, __atime) == cv_status::timeout)
159	    return __p();
160	return true;
161      }
162
163    template<typename _Rep, typename _Period>
164      cv_status
165      wait_for(unique_lock<mutex>& __lock,
166	       const chrono::duration<_Rep, _Period>& __rtime)
167      {
168	using __dur = typename steady_clock::duration;
169	auto __reltime = chrono::duration_cast<__dur>(__rtime);
170	if (__reltime < __rtime)
171	  ++__reltime;
172	return wait_until(__lock, steady_clock::now() + __reltime);
173      }
174
175    template<typename _Rep, typename _Period, typename _Predicate>
176      bool
177      wait_for(unique_lock<mutex>& __lock,
178	       const chrono::duration<_Rep, _Period>& __rtime,
179	       _Predicate __p)
180      {
181	using __dur = typename steady_clock::duration;
182	auto __reltime = chrono::duration_cast<__dur>(__rtime);
183	if (__reltime < __rtime)
184	  ++__reltime;
185	return wait_until(__lock, steady_clock::now() + __reltime,
186			  std::move(__p));
187      }
188
189    native_handle_type
190    native_handle()
191    { return &_M_cond; }
192
193  private:
194#ifdef _GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT
195    template<typename _Dur>
196      cv_status
197      __wait_until_impl(unique_lock<mutex>& __lock,
198			const chrono::time_point<steady_clock, _Dur>& __atime)
199      {
200	auto __s = chrono::time_point_cast<chrono::seconds>(__atime);
201	auto __ns = chrono::duration_cast<chrono::nanoseconds>(__atime - __s);
202
203	__gthread_time_t __ts =
204	  {
205	    static_cast<std::time_t>(__s.time_since_epoch().count()),
206	    static_cast<long>(__ns.count())
207	  };
208
209	pthread_cond_clockwait(&_M_cond, __lock.mutex()->native_handle(),
210					 CLOCK_MONOTONIC,
211					 &__ts);
212
213	return (steady_clock::now() < __atime
214		? cv_status::no_timeout : cv_status::timeout);
215      }
216#endif
217
218    template<typename _Dur>
219      cv_status
220      __wait_until_impl(unique_lock<mutex>& __lock,
221			const chrono::time_point<system_clock, _Dur>& __atime)
222      {
223	auto __s = chrono::time_point_cast<chrono::seconds>(__atime);
224	auto __ns = chrono::duration_cast<chrono::nanoseconds>(__atime - __s);
225
226	__gthread_time_t __ts =
227	  {
228	    static_cast<std::time_t>(__s.time_since_epoch().count()),
229	    static_cast<long>(__ns.count())
230	  };
231
232	__gthread_cond_timedwait(&_M_cond, __lock.mutex()->native_handle(),
233				 &__ts);
234
235	return (system_clock::now() < __atime
236		? cv_status::no_timeout : cv_status::timeout);
237      }
238  };
239
240  void
241  notify_all_at_thread_exit(condition_variable&, unique_lock<mutex>);
242
243  struct __at_thread_exit_elt
244  {
245    __at_thread_exit_elt* _M_next;
246    void (*_M_cb)(void*);
247  };
248
249  inline namespace _V2 {
250
251  /// condition_variable_any
252  // Like above, but mutex is not required to have try_lock.
253  class condition_variable_any
254  {
255#ifdef _GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT
256    using __clock_t = chrono::steady_clock;
257#else
258    using __clock_t = chrono::system_clock;
259#endif
260    condition_variable			_M_cond;
261    shared_ptr<mutex>			_M_mutex;
262
263    // scoped unlock - unlocks in ctor, re-locks in dtor
264    template<typename _Lock>
265      struct _Unlock
266      {
267	explicit _Unlock(_Lock& __lk) : _M_lock(__lk) { __lk.unlock(); }
268
269#pragma GCC diagnostic push
270#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
271	~_Unlock() noexcept(false)
272	{
273	  if (uncaught_exception())
274	    {
275	      __try
276	      { _M_lock.lock(); }
277	      __catch(const __cxxabiv1::__forced_unwind&)
278	      { __throw_exception_again; }
279	      __catch(...)
280	      { }
281	    }
282	  else
283	    _M_lock.lock();
284	}
285#pragma GCC diagnostic pop
286
287	_Unlock(const _Unlock&) = delete;
288	_Unlock& operator=(const _Unlock&) = delete;
289
290	_Lock& _M_lock;
291      };
292
293  public:
294    condition_variable_any() : _M_mutex(std::make_shared<mutex>()) { }
295    ~condition_variable_any() = default;
296
297    condition_variable_any(const condition_variable_any&) = delete;
298    condition_variable_any& operator=(const condition_variable_any&) = delete;
299
300    void
301    notify_one() noexcept
302    {
303      lock_guard<mutex> __lock(*_M_mutex);
304      _M_cond.notify_one();
305    }
306
307    void
308    notify_all() noexcept
309    {
310      lock_guard<mutex> __lock(*_M_mutex);
311      _M_cond.notify_all();
312    }
313
314    template<typename _Lock>
315      void
316      wait(_Lock& __lock)
317      {
318	shared_ptr<mutex> __mutex = _M_mutex;
319	unique_lock<mutex> __my_lock(*__mutex);
320	_Unlock<_Lock> __unlock(__lock);
321	// *__mutex must be unlocked before re-locking __lock so move
322	// ownership of *__mutex lock to an object with shorter lifetime.
323	unique_lock<mutex> __my_lock2(std::move(__my_lock));
324	_M_cond.wait(__my_lock2);
325      }
326
327
328    template<typename _Lock, typename _Predicate>
329      void
330      wait(_Lock& __lock, _Predicate __p)
331      {
332	while (!__p())
333	  wait(__lock);
334      }
335
336    template<typename _Lock, typename _Clock, typename _Duration>
337      cv_status
338      wait_until(_Lock& __lock,
339		 const chrono::time_point<_Clock, _Duration>& __atime)
340      {
341	shared_ptr<mutex> __mutex = _M_mutex;
342	unique_lock<mutex> __my_lock(*__mutex);
343	_Unlock<_Lock> __unlock(__lock);
344	// *__mutex must be unlocked before re-locking __lock so move
345	// ownership of *__mutex lock to an object with shorter lifetime.
346	unique_lock<mutex> __my_lock2(std::move(__my_lock));
347	return _M_cond.wait_until(__my_lock2, __atime);
348      }
349
350    template<typename _Lock, typename _Clock,
351	     typename _Duration, typename _Predicate>
352      bool
353      wait_until(_Lock& __lock,
354		 const chrono::time_point<_Clock, _Duration>& __atime,
355		 _Predicate __p)
356      {
357	while (!__p())
358	  if (wait_until(__lock, __atime) == cv_status::timeout)
359	    return __p();
360	return true;
361      }
362
363    template<typename _Lock, typename _Rep, typename _Period>
364      cv_status
365      wait_for(_Lock& __lock, const chrono::duration<_Rep, _Period>& __rtime)
366      { return wait_until(__lock, __clock_t::now() + __rtime); }
367
368    template<typename _Lock, typename _Rep,
369	     typename _Period, typename _Predicate>
370      bool
371      wait_for(_Lock& __lock,
372	       const chrono::duration<_Rep, _Period>& __rtime, _Predicate __p)
373      { return wait_until(__lock, __clock_t::now() + __rtime, std::move(__p)); }
374
375#ifdef __cpp_lib_jthread
376    template <class _Lock, class _Predicate>
377    bool wait(_Lock& __lock,
378              stop_token __stoken,
379              _Predicate __p)
380    {
381      if (__stoken.stop_requested())
382        {
383          return __p();
384        }
385
386      std::stop_callback __cb(__stoken, [this] { notify_all(); });
387      shared_ptr<mutex> __mutex = _M_mutex;
388      while (!__p())
389        {
390          unique_lock<mutex> __my_lock(*__mutex);
391          if (__stoken.stop_requested())
392            {
393              return false;
394            }
395          // *__mutex must be unlocked before re-locking __lock so move
396          // ownership of *__mutex lock to an object with shorter lifetime.
397          _Unlock<_Lock> __unlock(__lock);
398          unique_lock<mutex> __my_lock2(std::move(__my_lock));
399          _M_cond.wait(__my_lock2);
400        }
401      return true;
402    }
403
404    template <class _Lock, class _Clock, class _Duration, class _Predicate>
405    bool wait_until(_Lock& __lock,
406                    stop_token __stoken,
407                    const chrono::time_point<_Clock, _Duration>& __abs_time,
408                    _Predicate __p)
409    {
410      if (__stoken.stop_requested())
411        {
412          return __p();
413        }
414
415      std::stop_callback __cb(__stoken, [this] { notify_all(); });
416      shared_ptr<mutex> __mutex = _M_mutex;
417      while (!__p())
418        {
419          bool __stop;
420          {
421            unique_lock<mutex> __my_lock(*__mutex);
422            if (__stoken.stop_requested())
423              {
424                return false;
425              }
426            _Unlock<_Lock> __u(__lock);
427            unique_lock<mutex> __my_lock2(std::move(__my_lock));
428            const auto __status = _M_cond.wait_until(__my_lock2, __abs_time);
429            __stop = (__status == std::cv_status::timeout) || __stoken.stop_requested();
430          }
431          if (__stop)
432            {
433              return __p();
434            }
435        }
436      return true;
437    }
438
439    template <class _Lock, class _Rep, class _Period, class _Predicate>
440    bool wait_for(_Lock& __lock,
441                  stop_token __stoken,
442                  const chrono::duration<_Rep, _Period>& __rel_time,
443                  _Predicate __p)
444    {
445      auto __abst = std::chrono::steady_clock::now() + __rel_time;
446      return wait_until(__lock,
447                        std::move(__stoken),
448                        __abst,
449                        std::move(__p));
450    }
451#endif
452  };
453
454  } // end inline namespace
455
456  /// @} group condition_variables
457_GLIBCXX_END_NAMESPACE_VERSION
458} // namespace
459
460#endif // _GLIBCXX_HAS_GTHREADS
461#endif // C++11
462#endif // _GLIBCXX_CONDITION_VARIABLE
463