OLD | NEW |
1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 // ConditionVariable wraps pthreads condition variable synchronization or, on | 5 // ConditionVariable wraps pthreads condition variable synchronization or, on |
6 // Windows, simulates it. This functionality is very helpful for having | 6 // Windows, simulates it. This functionality is very helpful for having |
7 // several threads wait for an event, as is common with a thread pool managed | 7 // several threads wait for an event, as is common with a thread pool managed |
8 // by a master. The meaning of such an event in the (worker) thread pool | 8 // by a master. The meaning of such an event in the (worker) thread pool |
9 // scenario is that additional tasks are now available for processing. It is | 9 // scenario is that additional tasks are now available for processing. It is |
10 // used in Chrome in the DNS prefetching system to notify worker threads that | 10 // used in Chrome in the DNS prefetching system to notify worker threads that |
(...skipping 75 matching lines...) Expand 10 before | Expand all | Expand 10 after Loading... |
86 class BASE_EXPORT ConditionVariable { | 86 class BASE_EXPORT ConditionVariable { |
87 public: | 87 public: |
88 // Construct a cv for use with ONLY one user lock. | 88 // Construct a cv for use with ONLY one user lock. |
89 explicit ConditionVariable(Lock* user_lock); | 89 explicit ConditionVariable(Lock* user_lock); |
90 | 90 |
91 ~ConditionVariable(); | 91 ~ConditionVariable(); |
92 | 92 |
93 // Wait() releases the caller's critical section atomically as it starts to | 93 // Wait() releases the caller's critical section atomically as it starts to |
94 // sleep, and the reacquires it when it is signaled. | 94 // sleep, and the reacquires it when it is signaled. |
95 void Wait(); | 95 void Wait(); |
96 void TimedWait(const TimeDelta& max_time); | 96 // TimedWait() returns true on timeout, otherwise returns false. |
| 97 bool TimedWait(const TimeDelta& max_time); |
97 | 98 |
98 // Broadcast() revives all waiting threads. | 99 // Broadcast() revives all waiting threads. |
99 void Broadcast(); | 100 void Broadcast(); |
100 // Signal() revives one waiting thread. | 101 // Signal() revives one waiting thread. |
101 void Signal(); | 102 void Signal(); |
102 | 103 |
103 private: | 104 private: |
104 | 105 |
105 #if defined(OS_WIN) | 106 #if defined(OS_WIN) |
106 CONDITION_VARIABLE cv_; | 107 CONDITION_VARIABLE cv_; |
107 SRWLOCK* const srwlock_; | 108 SRWLOCK* const srwlock_; |
108 #elif defined(OS_POSIX) | 109 #elif defined(OS_POSIX) |
109 pthread_cond_t condition_; | 110 pthread_cond_t condition_; |
110 pthread_mutex_t* user_mutex_; | 111 pthread_mutex_t* user_mutex_; |
111 #endif | 112 #endif |
112 | 113 |
113 #if DCHECK_IS_ON() && (defined(OS_WIN) || defined(OS_POSIX)) | 114 #if DCHECK_IS_ON() && (defined(OS_WIN) || defined(OS_POSIX)) |
114 base::Lock* const user_lock_; // Needed to adjust shadow lock state on wait. | 115 base::Lock* const user_lock_; // Needed to adjust shadow lock state on wait. |
115 #endif | 116 #endif |
116 | 117 |
117 DISALLOW_COPY_AND_ASSIGN(ConditionVariable); | 118 DISALLOW_COPY_AND_ASSIGN(ConditionVariable); |
118 }; | 119 }; |
119 | 120 |
120 } // namespace base | 121 } // namespace base |
121 | 122 |
122 #endif // BASE_SYNCHRONIZATION_CONDITION_VARIABLE_H_ | 123 #endif // BASE_SYNCHRONIZATION_CONDITION_VARIABLE_H_ |
OLD | NEW |