libstdc++
condition_variable
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1 // <condition_variable> -*- C++ -*-
2 
3 // Copyright (C) 2008, 2009, 2010, 2011, 2012 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 #ifndef __GXX_EXPERIMENTAL_CXX0X__
35 # include <bits/c++0x_warning.h>
36 #else
37 
38 #include <chrono>
39 #include <mutex> // unique_lock
40 
41 #if defined(_GLIBCXX_HAS_GTHREADS) && defined(_GLIBCXX_USE_C99_STDINT_TR1)
42 
43 namespace std _GLIBCXX_VISIBILITY(default)
44 {
45 _GLIBCXX_BEGIN_NAMESPACE_VERSION
46 
47  /**
48  * @defgroup condition_variables Condition Variables
49  * @ingroup concurrency
50  *
51  * Classes for condition_variable support.
52  * @{
53  */
54 
55  /// cv_status
56  enum class cv_status { no_timeout, timeout };
57 
58  /// condition_variable
60  {
62  typedef __gthread_cond_t __native_type;
63 
64 #ifdef __GTHREAD_COND_INIT
65  __native_type _M_cond = __GTHREAD_COND_INIT;
66 #else
67  __native_type _M_cond;
68 #endif
69 
70  public:
71  typedef __native_type* native_handle_type;
72 
73  condition_variable() noexcept;
74  ~condition_variable() noexcept;
75 
76  condition_variable(const condition_variable&) = delete;
77  condition_variable& operator=(const condition_variable&) = delete;
78 
79  void
80  notify_one() noexcept;
81 
82  void
83  notify_all() noexcept;
84 
85  void
86  wait(unique_lock<mutex>& __lock);
87 
88  template<typename _Predicate>
89  void
90  wait(unique_lock<mutex>& __lock, _Predicate __p)
91  {
92  while (!__p())
93  wait(__lock);
94  }
95 
96  template<typename _Duration>
97  cv_status
98  wait_until(unique_lock<mutex>& __lock,
100  { return __wait_until_impl(__lock, __atime); }
101 
102  template<typename _Clock, typename _Duration>
103  cv_status
104  wait_until(unique_lock<mutex>& __lock,
106  {
107  // DR 887 - Sync unknown clock to known clock.
108  const typename _Clock::time_point __c_entry = _Clock::now();
109  const __clock_t::time_point __s_entry = __clock_t::now();
110  const chrono::nanoseconds __delta = __atime - __c_entry;
111  const __clock_t::time_point __s_atime = __s_entry + __delta;
112 
113  return __wait_until_impl(__lock, __s_atime);
114  }
115 
116  template<typename _Clock, typename _Duration, typename _Predicate>
117  bool
118  wait_until(unique_lock<mutex>& __lock,
120  _Predicate __p)
121  {
122  while (!__p())
123  if (wait_until(__lock, __atime) == cv_status::timeout)
124  return __p();
125  return true;
126  }
127 
128  template<typename _Rep, typename _Period>
129  cv_status
130  wait_for(unique_lock<mutex>& __lock,
131  const chrono::duration<_Rep, _Period>& __rtime)
132  { return wait_until(__lock, __clock_t::now() + __rtime); }
133 
134  template<typename _Rep, typename _Period, typename _Predicate>
135  bool
136  wait_for(unique_lock<mutex>& __lock,
137  const chrono::duration<_Rep, _Period>& __rtime,
138  _Predicate __p)
139  { return wait_until(__lock, __clock_t::now() + __rtime, std::move(__p)); }
140 
141  native_handle_type
142  native_handle()
143  { return &_M_cond; }
144 
145  private:
146  template<typename _Clock, typename _Duration>
147  cv_status
148  __wait_until_impl(unique_lock<mutex>& __lock,
150  {
153 
154  chrono::nanoseconds __ns =
156 
157  __gthread_time_t __ts =
158  {
159  static_cast<std::time_t>(__s.time_since_epoch().count()),
160  static_cast<long>(__ns.count())
161  };
162 
163  __gthread_cond_timedwait(&_M_cond, __lock.mutex()->native_handle(),
164  &__ts);
165 
166  return (_Clock::now() < __atime
167  ? cv_status::no_timeout : cv_status::timeout);
168  }
169  };
170 
171  /// condition_variable_any
172  // Like above, but mutex is not required to have try_lock.
174  {
176  condition_variable _M_cond;
177  mutex _M_mutex;
178 
179  // scoped unlock - unlocks in ctor, re-locks in dtor
180  template<typename _Lock>
181  struct _Unlock
182  {
183  explicit _Unlock(_Lock& __lk) : _M_lock(__lk) { __lk.unlock(); }
184 
185  ~_Unlock() noexcept(false)
186  {
187  if (uncaught_exception())
188  __try { _M_lock.lock(); } __catch(...) { }
189  else
190  _M_lock.lock();
191  }
192 
193  _Unlock(const _Unlock&) = delete;
194  _Unlock& operator=(const _Unlock&) = delete;
195 
196  _Lock& _M_lock;
197  };
198 
199  public:
200 
201  condition_variable_any() noexcept;
202  ~condition_variable_any() noexcept;
203 
205  condition_variable_any& operator=(const condition_variable_any&) = delete;
206 
207  void
208  notify_one() noexcept
209  {
210  lock_guard<mutex> __lock(_M_mutex);
211  _M_cond.notify_one();
212  }
213 
214  void
215  notify_all() noexcept
216  {
217  lock_guard<mutex> __lock(_M_mutex);
218  _M_cond.notify_all();
219  }
220 
221  template<typename _Lock>
222  void
223  wait(_Lock& __lock)
224  {
225  unique_lock<mutex> __my_lock(_M_mutex);
226  _Unlock<_Lock> __unlock(__lock);
227  // _M_mutex must be unlocked before re-locking __lock so move
228  // ownership of _M_mutex lock to an object with shorter lifetime.
229  unique_lock<mutex> __my_lock2(std::move(__my_lock));
230  _M_cond.wait(__my_lock2);
231  }
232 
233 
234  template<typename _Lock, typename _Predicate>
235  void
236  wait(_Lock& __lock, _Predicate __p)
237  {
238  while (!__p())
239  wait(__lock);
240  }
241 
242  template<typename _Lock, typename _Clock, typename _Duration>
243  cv_status
244  wait_until(_Lock& __lock,
246  {
247  unique_lock<mutex> __my_lock(_M_mutex);
248  _Unlock<_Lock> __unlock(__lock);
249  // _M_mutex must be unlocked before re-locking __lock so move
250  // ownership of _M_mutex lock to an object with shorter lifetime.
251  unique_lock<mutex> __my_lock2(std::move(__my_lock));
252  return _M_cond.wait_until(__my_lock2, __atime);
253  }
254 
255  template<typename _Lock, typename _Clock,
256  typename _Duration, typename _Predicate>
257  bool
258  wait_until(_Lock& __lock,
260  _Predicate __p)
261  {
262  while (!__p())
263  if (wait_until(__lock, __atime) == cv_status::timeout)
264  return __p();
265  return true;
266  }
267 
268  template<typename _Lock, typename _Rep, typename _Period>
269  cv_status
270  wait_for(_Lock& __lock, const chrono::duration<_Rep, _Period>& __rtime)
271  { return wait_until(__lock, __clock_t::now() + __rtime); }
272 
273  template<typename _Lock, typename _Rep,
274  typename _Period, typename _Predicate>
275  bool
276  wait_for(_Lock& __lock,
277  const chrono::duration<_Rep, _Period>& __rtime, _Predicate __p)
278  { return wait_until(__lock, __clock_t::now() + __rtime, std::move(__p)); }
279  };
280 
281  // @} group condition_variables
282 _GLIBCXX_END_NAMESPACE_VERSION
283 } // namespace
284 
285 #endif // _GLIBCXX_HAS_GTHREADS && _GLIBCXX_USE_C99_STDINT_TR1
286 
287 #endif // __GXX_EXPERIMENTAL_CXX0X__
288 
289 #endif // _GLIBCXX_CONDITION_VARIABLE