1// <condition_variable> -*- C++ -*-
2
3// Copyright (C) 2008-2019 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#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>
47
48#if defined(_GLIBCXX_HAS_GTHREADS)
49
50namespace std _GLIBCXX_VISIBILITY(default)
51{
52_GLIBCXX_BEGIN_NAMESPACE_VERSION
53
54 /**
55 * @defgroup condition_variables Condition Variables
56 * @ingroup concurrency
57 *
58 * Classes for condition_variable support.
59 * @{
60 */
61
62 /// cv_status
63 enum class cv_status { no_timeout, timeout };
64
65 /// condition_variable
66 class condition_variable
67 {
68 typedef chrono::system_clock __clock_t;
69 typedef chrono::steady_clock __steady_clock_t;
70 typedef __gthread_cond_t __native_type;
71
72#ifdef __GTHREAD_COND_INIT
73 __native_type _M_cond = __GTHREAD_COND_INIT;
74#else
75 __native_type _M_cond;
76#endif
77
78 public:
79 typedef __native_type* native_handle_type;
80
81 condition_variable() noexcept;
82 ~condition_variable() noexcept;
83
84 condition_variable(const condition_variable&) = delete;
85 condition_variable& operator=(const condition_variable&) = delete;
86
87 void
88 notify_one() noexcept;
89
90 void
91 notify_all() noexcept;
92
93 void
94 wait(unique_lock<mutex>& __lock) noexcept;
95
96 template<typename _Predicate>
97 void
98 wait(unique_lock<mutex>& __lock, _Predicate __p)
99 {
100 while (!__p())
101 wait(__lock);
102 }
103
104 template<typename _Duration>
105 cv_status
106 wait_until(unique_lock<mutex>& __lock,
107 const chrono::time_point<__clock_t, _Duration>& __atime)
108 { return __wait_until_impl(__lock, __atime); }
109
110 template<typename _Clock, typename _Duration>
111 cv_status
112 wait_until(unique_lock<mutex>& __lock,
113 const chrono::time_point<_Clock, _Duration>& __atime)
114 {
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;
120
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;
129 }
130
131 template<typename _Clock, typename _Duration, typename _Predicate>
132 bool
133 wait_until(unique_lock<mutex>& __lock,
134 const chrono::time_point<_Clock, _Duration>& __atime,
135 _Predicate __p)
136 {
137 while (!__p())
138 if (wait_until(__lock, __atime) == cv_status::timeout)
139 return __p();
140 return true;
141 }
142
143 template<typename _Rep, typename _Period>
144 cv_status
145 wait_for(unique_lock<mutex>& __lock,
146 const chrono::duration<_Rep, _Period>& __rtime)
147 {
148 using __dur = typename __steady_clock_t::duration;
149 auto __reltime = chrono::duration_cast<__dur>(__rtime);
150 if (__reltime < __rtime)
151 ++__reltime;
152 return wait_until(__lock, __steady_clock_t::now() + __reltime);
153 }
154
155 template<typename _Rep, typename _Period, typename _Predicate>
156 bool
157 wait_for(unique_lock<mutex>& __lock,
158 const chrono::duration<_Rep, _Period>& __rtime,
159 _Predicate __p)
160 {
161 using __dur = typename __steady_clock_t::duration;
162 auto __reltime = chrono::duration_cast<__dur>(__rtime);
163 if (__reltime < __rtime)
164 ++__reltime;
165 return wait_until(__lock, __steady_clock_t::now() + __reltime,
166 std::move(__p));
167 }
168
169 native_handle_type
170 native_handle()
171 { return &_M_cond; }
172
173 private:
174 template<typename _Dur>
175 cv_status
176 __wait_until_impl(unique_lock<mutex>& __lock,
177 const chrono::time_point<__clock_t, _Dur>& __atime)
178 {
179 auto __s = chrono::time_point_cast<chrono::seconds>(__atime);
180 auto __ns = chrono::duration_cast<chrono::nanoseconds>(__atime - __s);
181
182 __gthread_time_t __ts =
183 {
184 static_cast<std::time_t>(__s.time_since_epoch().count()),
185 static_cast<long>(__ns.count())
186 };
187
188 __gthread_cond_timedwait(&_M_cond, __lock.mutex()->native_handle(),
189 &__ts);
190
191 return (__clock_t::now() < __atime
192 ? cv_status::no_timeout : cv_status::timeout);
193 }
194 };
195
196 void
197 notify_all_at_thread_exit(condition_variable&, unique_lock<mutex>);
198
199 struct __at_thread_exit_elt
200 {
201 __at_thread_exit_elt* _M_next;
202 void (*_M_cb)(void*);
203 };
204
205 inline namespace _V2 {
206
207 /// condition_variable_any
208 // Like above, but mutex is not required to have try_lock.
209 class condition_variable_any
210 {
211 typedef chrono::system_clock __clock_t;
212 condition_variable _M_cond;
213 shared_ptr<mutex> _M_mutex;
214
215 // scoped unlock - unlocks in ctor, re-locks in dtor
216 template<typename _Lock>
217 struct _Unlock
218 {
219 explicit _Unlock(_Lock& __lk) : _M_lock(__lk) { __lk.unlock(); }
220
221 ~_Unlock() noexcept(false)
222 {
223 if (uncaught_exception())
224 {
225 __try
226 { _M_lock.lock(); }
227 __catch(const __cxxabiv1::__forced_unwind&)
228 { __throw_exception_again; }
229 __catch(...)
230 { }
231 }
232 else
233 _M_lock.lock();
234 }
235
236 _Unlock(const _Unlock&) = delete;
237 _Unlock& operator=(const _Unlock&) = delete;
238
239 _Lock& _M_lock;
240 };
241
242 public:
243 condition_variable_any() : _M_mutex(std::make_shared<mutex>()) { }
244 ~condition_variable_any() = default;
245
246 condition_variable_any(const condition_variable_any&) = delete;
247 condition_variable_any& operator=(const condition_variable_any&) = delete;
248
249 void
250 notify_one() noexcept
251 {
252 lock_guard<mutex> __lock(*_M_mutex);
253 _M_cond.notify_one();
254 }
255
256 void
257 notify_all() noexcept
258 {
259 lock_guard<mutex> __lock(*_M_mutex);
260 _M_cond.notify_all();
261 }
262
263 template<typename _Lock>
264 void
265 wait(_Lock& __lock)
266 {
267 shared_ptr<mutex> __mutex = _M_mutex;
268 unique_lock<mutex> __my_lock(*__mutex);
269 _Unlock<_Lock> __unlock(__lock);
270 // *__mutex must be unlocked before re-locking __lock so move
271 // ownership of *__mutex lock to an object with shorter lifetime.
272 unique_lock<mutex> __my_lock2(std::move(__my_lock));
273 _M_cond.wait(__my_lock2);
274 }
275
276
277 template<typename _Lock, typename _Predicate>
278 void
279 wait(_Lock& __lock, _Predicate __p)
280 {
281 while (!__p())
282 wait(__lock);
283 }
284
285 template<typename _Lock, typename _Clock, typename _Duration>
286 cv_status
287 wait_until(_Lock& __lock,
288 const chrono::time_point<_Clock, _Duration>& __atime)
289 {
290 shared_ptr<mutex> __mutex = _M_mutex;
291 unique_lock<mutex> __my_lock(*__mutex);
292 _Unlock<_Lock> __unlock(__lock);
293 // *__mutex must be unlocked before re-locking __lock so move
294 // ownership of *__mutex lock to an object with shorter lifetime.
295 unique_lock<mutex> __my_lock2(std::move(__my_lock));
296 return _M_cond.wait_until(__my_lock2, __atime);
297 }
298
299 template<typename _Lock, typename _Clock,
300 typename _Duration, typename _Predicate>
301 bool
302 wait_until(_Lock& __lock,
303 const chrono::time_point<_Clock, _Duration>& __atime,
304 _Predicate __p)
305 {
306 while (!__p())
307 if (wait_until(__lock, __atime) == cv_status::timeout)
308 return __p();
309 return true;
310 }
311
312 template<typename _Lock, typename _Rep, typename _Period>
313 cv_status
314 wait_for(_Lock& __lock, const chrono::duration<_Rep, _Period>& __rtime)
315 { return wait_until(__lock, __clock_t::now() + __rtime); }
316
317 template<typename _Lock, typename _Rep,
318 typename _Period, typename _Predicate>
319 bool
320 wait_for(_Lock& __lock,
321 const chrono::duration<_Rep, _Period>& __rtime, _Predicate __p)
322 { return wait_until(__lock, __clock_t::now() + __rtime, std::move(__p)); }
323 };
324
325 } // end inline namespace
326
327 // @} group condition_variables
328_GLIBCXX_END_NAMESPACE_VERSION
329} // namespace
330
331#endif // _GLIBCXX_HAS_GTHREADS
332#endif // C++11
333#endif // _GLIBCXX_CONDITION_VARIABLE
334