gfx/skia/trunk/include/utils/SkCondVar.h

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1 /*
2 * Copyright 2012 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8 #ifndef SkCondVar_DEFINED
9 #define SkCondVar_DEFINED
10
11 #ifdef SK_USE_POSIX_THREADS
12 #include <pthread.h>
13 #elif defined(SK_BUILD_FOR_WIN32)
14 #include <windows.h>
15 #endif
16
17 /**
18 * Condition variable for blocking access to shared data from other threads and
19 * controlling which threads are awake.
20 *
21 * Currently only supported on platforms with posix threads and Windows Vista and
22 * above.
23 */
24 class SkCondVar {
25 public:
26 SkCondVar();
27 ~SkCondVar();
28
29 /**
30 * Lock a mutex. Must be done before calling the other functions on this object.
31 */
32 void lock();
33
34 /**
35 * Unlock the mutex.
36 */
37 void unlock();
38
39 /**
40 * Pause the calling thread. Will be awoken when signal() or broadcast() is called.
41 * Must be called while lock() is held (but gives it up while waiting). Once awoken,
42 * the calling thread will hold the lock once again.
43 */
44 void wait();
45
46 /**
47 * Wake one thread waiting on this condition. Must be called while lock()
48 * is held.
49 */
50 void signal();
51
52 /**
53 * Wake all threads waiting on this condition. Must be called while lock()
54 * is held.
55 */
56 void broadcast();
57
58 private:
59 #ifdef SK_USE_POSIX_THREADS
60 pthread_mutex_t fMutex;
61 pthread_cond_t fCond;
62 #elif defined(SK_BUILD_FOR_WIN32)
63 CRITICAL_SECTION fCriticalSection;
64 CONDITION_VARIABLE fCondition;
65 #endif
66 };
67
68 #endif

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