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1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2012 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 #ifndef BASE_SYNCHRONIZATION_WAITABLE_EVENT_WATCHER_H_ | 5 #ifndef BASE_SYNCHRONIZATION_WAITABLE_EVENT_WATCHER_H_ |
6 #define BASE_SYNCHRONIZATION_WAITABLE_EVENT_WATCHER_H_ | 6 #define BASE_SYNCHRONIZATION_WAITABLE_EVENT_WATCHER_H_ |
7 | 7 |
8 #include "base/base_export.h" | 8 #include "base/base_export.h" |
9 #include "build/build_config.h" | |
10 | |
11 #if defined(OS_WIN) | |
12 #include "base/win/object_watcher.h" | |
13 #else | |
14 #include "base/callback.h" | 9 #include "base/callback.h" |
15 #include "base/message_loop/message_loop.h" | 10 #include "base/message_loop/message_loop.h" |
16 #include "base/synchronization/waitable_event.h" | 11 #include "base/synchronization/waitable_event.h" |
17 #endif | 12 #include "build/build_config.h" |
18 | 13 |
19 namespace base { | 14 namespace base { |
20 | 15 |
21 class Flag; | 16 class Flag; |
22 class AsyncWaiter; | 17 class AsyncWaiter; |
23 class AsyncCallbackTask; | 18 class AsyncCallbackTask; |
24 class WaitableEvent; | 19 class WaitableEvent; |
25 | 20 |
26 // This class provides a way to wait on a WaitableEvent asynchronously. | 21 // This class provides a way to wait on a WaitableEvent asynchronously. |
27 // | 22 // |
(...skipping 24 matching lines...) Expand all Loading... |
52 // | 47 // |
53 // BEWARE: With automatically reset WaitableEvents, a signal may be lost if it | 48 // BEWARE: With automatically reset WaitableEvents, a signal may be lost if it |
54 // occurs just before a WaitableEventWatcher is deleted. There is currently no | 49 // occurs just before a WaitableEventWatcher is deleted. There is currently no |
55 // safe way to stop watching an automatic reset WaitableEvent without possibly | 50 // safe way to stop watching an automatic reset WaitableEvent without possibly |
56 // missing a signal. | 51 // missing a signal. |
57 // | 52 // |
58 // NOTE: you /are/ allowed to delete the WaitableEvent while still waiting on | 53 // NOTE: you /are/ allowed to delete the WaitableEvent while still waiting on |
59 // it with a Watcher. It will act as if the event was never signaled. | 54 // it with a Watcher. It will act as if the event was never signaled. |
60 | 55 |
61 class BASE_EXPORT WaitableEventWatcher | 56 class BASE_EXPORT WaitableEventWatcher |
62 #if defined(OS_WIN) | |
63 : public win::ObjectWatcher::Delegate { | |
64 #else | |
65 : public MessageLoop::DestructionObserver { | 57 : public MessageLoop::DestructionObserver { |
66 #endif | |
67 public: | 58 public: |
68 typedef Callback<void(WaitableEvent*)> EventCallback; | 59 typedef Callback<void(WaitableEvent*)> EventCallback; |
69 WaitableEventWatcher(); | 60 WaitableEventWatcher(); |
70 ~WaitableEventWatcher() override; | 61 ~WaitableEventWatcher() override; |
71 | 62 |
72 // When @event is signaled, the given callback is called on the thread of the | 63 // When @event is signaled, the given callback is called on the thread of the |
73 // current message loop when StartWatching is called. | 64 // current message loop when StartWatching is called. |
74 bool StartWatching(WaitableEvent* event, const EventCallback& callback); | 65 bool StartWatching(WaitableEvent* event, const EventCallback& callback); |
75 | 66 |
76 // Cancel the current watch. Must be called from the same thread which | 67 // Cancel the current watch. Must be called from the same thread which |
77 // started the watch. | 68 // started the watch. |
78 // | 69 // |
79 // Does nothing if no event is being watched, nor if the watch has completed. | 70 // Does nothing if no event is being watched, nor if the watch has completed. |
80 // The callback will *not* be called for the current watch after this | 71 // The callback will *not* be called for the current watch after this |
81 // function returns. Since the callback runs on the same thread as this | 72 // function returns. Since the callback runs on the same thread as this |
82 // function, it cannot be called during this function either. | 73 // function, it cannot be called during this function either. |
83 void StopWatching(); | 74 void StopWatching(); |
84 | 75 |
85 // Return the currently watched event, or NULL if no object is currently being | 76 // Return the currently watched event, or NULL if no object is currently being |
86 // watched. | 77 // watched. |
87 WaitableEvent* GetWatchedEvent(); | 78 WaitableEvent* GetWatchedEvent(); |
88 | 79 |
89 // Return the callback that will be invoked when the event is | 80 // Return the callback that will be invoked when the event is |
90 // signaled. | 81 // signaled. |
91 const EventCallback& callback() const { return callback_; } | 82 const EventCallback& callback() const { return callback_; } |
92 | 83 |
93 private: | 84 private: |
94 #if defined(OS_WIN) | |
95 void OnObjectSignaled(HANDLE h) override; | |
96 win::ObjectWatcher watcher_; | |
97 #else | |
98 // Implementation of MessageLoop::DestructionObserver | 85 // Implementation of MessageLoop::DestructionObserver |
99 void WillDestroyCurrentMessageLoop() override; | 86 void WillDestroyCurrentMessageLoop() override; |
100 | 87 |
101 MessageLoop* message_loop_; | 88 MessageLoop* message_loop_; |
102 scoped_refptr<Flag> cancel_flag_; | 89 scoped_refptr<Flag> cancel_flag_; |
103 AsyncWaiter* waiter_; | 90 AsyncWaiter* waiter_; |
104 base::Closure internal_callback_; | 91 base::Closure internal_callback_; |
105 scoped_refptr<WaitableEvent::WaitableEventKernel> kernel_; | 92 scoped_refptr<WaitableEvent::WaitableEventKernel> kernel_; |
106 #endif | |
107 | 93 |
108 WaitableEvent* event_; | 94 WaitableEvent* event_; |
109 EventCallback callback_; | 95 EventCallback callback_; |
110 }; | 96 }; |
111 | 97 |
112 } // namespace base | 98 } // namespace base |
113 | 99 |
114 #endif // BASE_SYNCHRONIZATION_WAITABLE_EVENT_WATCHER_H_ | 100 #endif // BASE_SYNCHRONIZATION_WAITABLE_EVENT_WATCHER_H_ |
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