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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_H_ | 5 #ifndef BASE_SYNCHRONIZATION_WAITABLE_EVENT_H_ |
6 #define BASE_SYNCHRONIZATION_WAITABLE_EVENT_H_ | 6 #define BASE_SYNCHRONIZATION_WAITABLE_EVENT_H_ |
7 | 7 |
8 #include "base/base_export.h" | 8 #include "base/base_export.h" |
9 #include "base/basictypes.h" | 9 #include "base/basictypes.h" |
10 | 10 |
11 #if defined(OS_WIN) | |
12 #include "base/win/scoped_handle.h" | |
13 #endif | |
14 | |
15 #if defined(OS_POSIX) | 11 #if defined(OS_POSIX) |
16 #include <list> | 12 #include <list> |
17 #include <utility> | 13 #include <utility> |
18 #include "base/memory/ref_counted.h" | 14 #include "base/memory/ref_counted.h" |
19 #include "base/synchronization/lock.h" | 15 #include "base/synchronization/lock.h" |
20 #endif | 16 #endif |
21 | 17 |
22 namespace base { | 18 namespace base { |
23 | 19 |
24 class TimeDelta; | 20 class TimeDelta; |
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39 // specific code and you need other features of a Windows event, then you might | 35 // specific code and you need other features of a Windows event, then you might |
40 // be better off just using an Windows event directly. | 36 // be better off just using an Windows event directly. |
41 class BASE_EXPORT WaitableEvent { | 37 class BASE_EXPORT WaitableEvent { |
42 public: | 38 public: |
43 // If manual_reset is true, then to set the event state to non-signaled, a | 39 // If manual_reset is true, then to set the event state to non-signaled, a |
44 // consumer must call the Reset method. If this parameter is false, then the | 40 // consumer must call the Reset method. If this parameter is false, then the |
45 // system automatically resets the event state to non-signaled after a single | 41 // system automatically resets the event state to non-signaled after a single |
46 // waiting thread has been released. | 42 // waiting thread has been released. |
47 WaitableEvent(bool manual_reset, bool initially_signaled); | 43 WaitableEvent(bool manual_reset, bool initially_signaled); |
48 | 44 |
49 #if defined(OS_WIN) | |
50 // Create a WaitableEvent from an Event HANDLE which has already been | |
51 // created. This objects takes ownership of the HANDLE and will close it when | |
52 // deleted. | |
53 explicit WaitableEvent(win::ScopedHandle event_handle); | |
54 #endif | |
55 | |
56 ~WaitableEvent(); | 45 ~WaitableEvent(); |
57 | 46 |
58 // Put the event in the un-signaled state. | 47 // Put the event in the un-signaled state. |
59 void Reset(); | 48 void Reset(); |
60 | 49 |
61 // Put the event in the signaled state. Causing any thread blocked on Wait | 50 // Put the event in the signaled state. Causing any thread blocked on Wait |
62 // to be woken up. | 51 // to be woken up. |
63 void Signal(); | 52 void Signal(); |
64 | 53 |
65 // Returns true if the event is in the signaled state, else false. If this | 54 // Returns true if the event is in the signaled state, else false. If this |
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76 // delete e; | 65 // delete e; |
77 void Wait(); | 66 void Wait(); |
78 | 67 |
79 // Wait up until max_time has passed for the event to be signaled. Returns | 68 // Wait up until max_time has passed for the event to be signaled. Returns |
80 // true if the event was signaled. If this method returns false, then it | 69 // true if the event was signaled. If this method returns false, then it |
81 // does not necessarily mean that max_time was exceeded. | 70 // does not necessarily mean that max_time was exceeded. |
82 // | 71 // |
83 // TimedWait can synchronise its own destruction like |Wait|. | 72 // TimedWait can synchronise its own destruction like |Wait|. |
84 bool TimedWait(const TimeDelta& max_time); | 73 bool TimedWait(const TimeDelta& max_time); |
85 | 74 |
86 #if defined(OS_WIN) | |
87 HANDLE handle() const { return handle_.Get(); } | |
88 #endif | |
89 | |
90 // Wait, synchronously, on multiple events. | 75 // Wait, synchronously, on multiple events. |
91 // waitables: an array of WaitableEvent pointers | 76 // waitables: an array of WaitableEvent pointers |
92 // count: the number of elements in @waitables | 77 // count: the number of elements in @waitables |
93 // | 78 // |
94 // returns: the index of a WaitableEvent which has been signaled. | 79 // returns: the index of a WaitableEvent which has been signaled. |
95 // | 80 // |
96 // You MUST NOT delete any of the WaitableEvent objects while this wait is | 81 // You MUST NOT delete any of the WaitableEvent objects while this wait is |
97 // happening, however WaitMany's return "happens after" the |Signal| call | 82 // happening, however WaitMany's return "happens after" the |Signal| call |
98 // that caused it has completed, like |Wait|. | 83 // that caused it has completed, like |Wait|. |
99 static size_t WaitMany(WaitableEvent** waitables, size_t count); | 84 static size_t WaitMany(WaitableEvent** waitables, size_t count); |
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126 // comments in ~Handle for why. | 111 // comments in ~Handle for why. |
127 virtual bool Compare(void* tag) = 0; | 112 virtual bool Compare(void* tag) = 0; |
128 | 113 |
129 protected: | 114 protected: |
130 virtual ~Waiter() {} | 115 virtual ~Waiter() {} |
131 }; | 116 }; |
132 | 117 |
133 private: | 118 private: |
134 friend class WaitableEventWatcher; | 119 friend class WaitableEventWatcher; |
135 | 120 |
136 #if defined(OS_WIN) | |
137 win::ScopedHandle handle_; | |
138 #else | |
139 // On Windows, one can close a HANDLE which is currently being waited on. The | 121 // On Windows, one can close a HANDLE which is currently being waited on. The |
140 // MSDN documentation says that the resulting behaviour is 'undefined', but | 122 // MSDN documentation says that the resulting behaviour is 'undefined', but |
141 // it doesn't crash. However, if we were to include the following members | 123 // it doesn't crash. However, if we were to include the following members |
142 // directly then, on POSIX, one couldn't use WaitableEventWatcher to watch an | 124 // directly then, on POSIX, one couldn't use WaitableEventWatcher to watch an |
143 // event which gets deleted. This mismatch has bitten us several times now, | 125 // event which gets deleted. This mismatch has bitten us several times now, |
144 // so we have a kernel of the WaitableEvent, which is reference counted. | 126 // so we have a kernel of the WaitableEvent, which is reference counted. |
145 // WaitableEventWatchers may then take a reference and thus match the Windows | 127 // WaitableEventWatchers may then take a reference and thus match the Windows |
146 // behaviour. | 128 // behaviour. |
147 struct WaitableEventKernel : | 129 struct WaitableEventKernel : |
148 public RefCountedThreadSafe<WaitableEventKernel> { | 130 public RefCountedThreadSafe<WaitableEventKernel> { |
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169 // second element is the index of the WaitableEvent in the original, | 151 // second element is the index of the WaitableEvent in the original, |
170 // unsorted, array. | 152 // unsorted, array. |
171 static size_t EnqueueMany(WaiterAndIndex* waitables, | 153 static size_t EnqueueMany(WaiterAndIndex* waitables, |
172 size_t count, Waiter* waiter); | 154 size_t count, Waiter* waiter); |
173 | 155 |
174 bool SignalAll(); | 156 bool SignalAll(); |
175 bool SignalOne(); | 157 bool SignalOne(); |
176 void Enqueue(Waiter* waiter); | 158 void Enqueue(Waiter* waiter); |
177 | 159 |
178 scoped_refptr<WaitableEventKernel> kernel_; | 160 scoped_refptr<WaitableEventKernel> kernel_; |
179 #endif | |
180 | 161 |
181 DISALLOW_COPY_AND_ASSIGN(WaitableEvent); | 162 DISALLOW_COPY_AND_ASSIGN(WaitableEvent); |
182 }; | 163 }; |
183 | 164 |
184 } // namespace base | 165 } // namespace base |
185 | 166 |
186 #endif // BASE_SYNCHRONIZATION_WAITABLE_EVENT_H_ | 167 #endif // BASE_SYNCHRONIZATION_WAITABLE_EVENT_H_ |
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