1 // <condition_variable> -*- C++ -*-
3 // Copyright (C) 2008-2018 Free Software Foundation, Inc.
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)
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.
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.
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/>.
25 /** @file include/condition_variable
26 * This is a Standard C++ Library header.
29 #ifndef _GLIBCXX_CONDITION_VARIABLE
30 #define _GLIBCXX_CONDITION_VARIABLE 1
32 #pragma GCC system_header
34 #if __cplusplus < 201103L
35 # include <bits/c++0x_warning.h>
39 #include <bits/std_mutex.h>
40 #include <bits/unique_lock.h>
41 #include <ext/concurrence.h>
42 #include <bits/alloc_traits.h>
43 #include <bits/allocator.h>
44 #include <bits/unique_ptr.h>
45 #include <bits/shared_ptr.h>
46 #include <bits/cxxabi_forced.h>
48 #if defined(_GLIBCXX_HAS_GTHREADS)
50 namespace std _GLIBCXX_VISIBILITY(default)
52 _GLIBCXX_BEGIN_NAMESPACE_VERSION
55 * @defgroup condition_variables Condition Variables
56 * @ingroup concurrency
58 * Classes for condition_variable support.
63 enum class cv_status { no_timeout, timeout };
65 /// condition_variable
66 class condition_variable
68 typedef chrono::system_clock __clock_t;
69 typedef chrono::steady_clock __steady_clock_t;
70 typedef __gthread_cond_t __native_type;
72 #ifdef __GTHREAD_COND_INIT
73 __native_type _M_cond = __GTHREAD_COND_INIT;
75 __native_type _M_cond;
79 typedef __native_type* native_handle_type;
81 condition_variable() noexcept;
82 ~condition_variable() noexcept;
84 condition_variable(const condition_variable&) = delete;
85 condition_variable& operator=(const condition_variable&) = delete;
88 notify_one() noexcept;
91 notify_all() noexcept;
94 wait(unique_lock<mutex>& __lock) noexcept;
96 template<typename _Predicate>
98 wait(unique_lock<mutex>& __lock, _Predicate __p)
104 template<typename _Duration>
106 wait_until(unique_lock<mutex>& __lock,
107 const chrono::time_point<__clock_t, _Duration>& __atime)
108 { return __wait_until_impl(__lock, __atime); }
110 template<typename _Clock, typename _Duration>
112 wait_until(unique_lock<mutex>& __lock,
113 const chrono::time_point<_Clock, _Duration>& __atime)
115 // DR 887 - Sync unknown clock to known clock.
116 const typename _Clock::time_point __c_entry = _Clock::now();
117 const __clock_t::time_point __s_entry = __clock_t::now();
118 const auto __delta = __atime - __c_entry;
119 const auto __s_atime = __s_entry + __delta;
121 if (__wait_until_impl(__lock, __s_atime) == cv_status::no_timeout)
122 return cv_status::no_timeout;
123 // We got a timeout when measured against __clock_t but
124 // we need to check against the caller-supplied clock
125 // to tell whether we should return a timeout.
126 if (_Clock::now() < __atime)
127 return cv_status::no_timeout;
128 return cv_status::timeout;
131 template<typename _Clock, typename _Duration, typename _Predicate>
133 wait_until(unique_lock<mutex>& __lock,
134 const chrono::time_point<_Clock, _Duration>& __atime,
138 if (wait_until(__lock, __atime) == cv_status::timeout)
143 template<typename _Rep, typename _Period>
145 wait_for(unique_lock<mutex>& __lock,
146 const chrono::duration<_Rep, _Period>& __rtime)
148 using __dur = typename __steady_clock_t::duration;
149 auto __reltime = chrono::duration_cast<__dur>(__rtime);
150 if (__reltime < __rtime)
152 return wait_until(__lock, __steady_clock_t::now() + __reltime);
155 template<typename _Rep, typename _Period, typename _Predicate>
157 wait_for(unique_lock<mutex>& __lock,
158 const chrono::duration<_Rep, _Period>& __rtime,
161 using __dur = typename __clock_t::duration;
162 auto __reltime = chrono::duration_cast<__dur>(__rtime);
163 if (__reltime < __rtime)
165 return wait_until(__lock, __clock_t::now() + __reltime, std::move(__p));
173 template<typename _Dur>
175 __wait_until_impl(unique_lock<mutex>& __lock,
176 const chrono::time_point<__clock_t, _Dur>& __atime)
178 auto __s = chrono::time_point_cast<chrono::seconds>(__atime);
179 auto __ns = chrono::duration_cast<chrono::nanoseconds>(__atime - __s);
181 __gthread_time_t __ts =
183 static_cast<std::time_t>(__s.time_since_epoch().count()),
184 static_cast<long>(__ns.count())
187 __gthread_cond_timedwait(&_M_cond, __lock.mutex()->native_handle(),
190 return (__clock_t::now() < __atime
191 ? cv_status::no_timeout : cv_status::timeout);
196 notify_all_at_thread_exit(condition_variable&, unique_lock<mutex>);
198 struct __at_thread_exit_elt
200 __at_thread_exit_elt* _M_next;
201 void (*_M_cb)(void*);
204 inline namespace _V2 {
206 /// condition_variable_any
207 // Like above, but mutex is not required to have try_lock.
208 class condition_variable_any
210 typedef chrono::system_clock __clock_t;
211 condition_variable _M_cond;
212 shared_ptr<mutex> _M_mutex;
214 // scoped unlock - unlocks in ctor, re-locks in dtor
215 template<typename _Lock>
218 explicit _Unlock(_Lock& __lk) : _M_lock(__lk) { __lk.unlock(); }
220 ~_Unlock() noexcept(false)
222 if (uncaught_exception())
226 __catch(const __cxxabiv1::__forced_unwind&)
227 { __throw_exception_again; }
235 _Unlock(const _Unlock&) = delete;
236 _Unlock& operator=(const _Unlock&) = delete;
242 condition_variable_any() : _M_mutex(std::make_shared<mutex>()) { }
243 ~condition_variable_any() = default;
245 condition_variable_any(const condition_variable_any&) = delete;
246 condition_variable_any& operator=(const condition_variable_any&) = delete;
249 notify_one() noexcept
251 lock_guard<mutex> __lock(*_M_mutex);
252 _M_cond.notify_one();
256 notify_all() noexcept
258 lock_guard<mutex> __lock(*_M_mutex);
259 _M_cond.notify_all();
262 template<typename _Lock>
266 shared_ptr<mutex> __mutex = _M_mutex;
267 unique_lock<mutex> __my_lock(*__mutex);
268 _Unlock<_Lock> __unlock(__lock);
269 // *__mutex must be unlocked before re-locking __lock so move
270 // ownership of *__mutex lock to an object with shorter lifetime.
271 unique_lock<mutex> __my_lock2(std::move(__my_lock));
272 _M_cond.wait(__my_lock2);
276 template<typename _Lock, typename _Predicate>
278 wait(_Lock& __lock, _Predicate __p)
284 template<typename _Lock, typename _Clock, typename _Duration>
286 wait_until(_Lock& __lock,
287 const chrono::time_point<_Clock, _Duration>& __atime)
289 shared_ptr<mutex> __mutex = _M_mutex;
290 unique_lock<mutex> __my_lock(*__mutex);
291 _Unlock<_Lock> __unlock(__lock);
292 // *__mutex must be unlocked before re-locking __lock so move
293 // ownership of *__mutex lock to an object with shorter lifetime.
294 unique_lock<mutex> __my_lock2(std::move(__my_lock));
295 return _M_cond.wait_until(__my_lock2, __atime);
298 template<typename _Lock, typename _Clock,
299 typename _Duration, typename _Predicate>
301 wait_until(_Lock& __lock,
302 const chrono::time_point<_Clock, _Duration>& __atime,
306 if (wait_until(__lock, __atime) == cv_status::timeout)
311 template<typename _Lock, typename _Rep, typename _Period>
313 wait_for(_Lock& __lock, const chrono::duration<_Rep, _Period>& __rtime)
314 { return wait_until(__lock, __clock_t::now() + __rtime); }
316 template<typename _Lock, typename _Rep,
317 typename _Period, typename _Predicate>
319 wait_for(_Lock& __lock,
320 const chrono::duration<_Rep, _Period>& __rtime, _Predicate __p)
321 { return wait_until(__lock, __clock_t::now() + __rtime, std::move(__p)); }
324 } // end inline namespace
326 // @} group condition_variables
327 _GLIBCXX_END_NAMESPACE_VERSION
330 #endif // _GLIBCXX_HAS_GTHREADS
332 #endif // _GLIBCXX_CONDITION_VARIABLE