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1 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 #include "base/waitable_event.h" | |
6 | |
7 #include <math.h> | |
8 #include <windows.h> | |
9 | |
10 #include "base/logging.h" | |
11 #include "base/time.h" | |
12 | |
13 namespace base { | |
14 | |
15 WaitableEvent::WaitableEvent(bool manual_reset, bool signaled) | |
16 : handle_(CreateEvent(NULL, manual_reset, signaled, NULL)) { | |
17 // We're probably going to crash anyways if this is ever NULL, so we might as | |
18 // well make our stack reports more informative by crashing here. | |
19 CHECK(handle_); | |
20 } | |
21 | |
22 WaitableEvent::WaitableEvent(HANDLE handle) | |
23 : handle_(handle) { | |
24 CHECK(handle) << "Tried to create WaitableEvent from NULL handle"; | |
25 } | |
26 | |
27 WaitableEvent::~WaitableEvent() { | |
28 CloseHandle(handle_); | |
29 } | |
30 | |
31 HANDLE WaitableEvent::Release() { | |
32 HANDLE rv = handle_; | |
33 handle_ = INVALID_HANDLE_VALUE; | |
34 return rv; | |
35 } | |
36 | |
37 void WaitableEvent::Reset() { | |
38 ResetEvent(handle_); | |
39 } | |
40 | |
41 void WaitableEvent::Signal() { | |
42 SetEvent(handle_); | |
43 } | |
44 | |
45 bool WaitableEvent::IsSignaled() { | |
46 return TimedWait(TimeDelta::FromMilliseconds(0)); | |
47 } | |
48 | |
49 bool WaitableEvent::Wait() { | |
50 DWORD result = WaitForSingleObject(handle_, INFINITE); | |
51 // It is most unexpected that this should ever fail. Help consumers learn | |
52 // about it if it should ever fail. | |
53 DCHECK(result == WAIT_OBJECT_0) << "WaitForSingleObject failed"; | |
54 return result == WAIT_OBJECT_0; | |
55 } | |
56 | |
57 bool WaitableEvent::TimedWait(const TimeDelta& max_time) { | |
58 DCHECK(max_time >= TimeDelta::FromMicroseconds(0)); | |
59 // Be careful here. TimeDelta has a precision of microseconds, but this API | |
60 // is in milliseconds. If there are 5.5ms left, should the delay be 5 or 6? | |
61 // It should be 6 to avoid returning too early. | |
62 double timeout = ceil(max_time.InMillisecondsF()); | |
63 DWORD result = WaitForSingleObject(handle_, static_cast<DWORD>(timeout)); | |
64 switch (result) { | |
65 case WAIT_OBJECT_0: | |
66 return true; | |
67 case WAIT_TIMEOUT: | |
68 return false; | |
69 } | |
70 // It is most unexpected that this should ever fail. Help consumers learn | |
71 // about it if it should ever fail. | |
72 NOTREACHED() << "WaitForSingleObject failed"; | |
73 return false; | |
74 } | |
75 | |
76 // static | |
77 size_t WaitableEvent::WaitMany(WaitableEvent** events, size_t count) { | |
78 HANDLE handles[MAXIMUM_WAIT_OBJECTS]; | |
79 CHECK_LE(count, MAXIMUM_WAIT_OBJECTS) | |
80 << "Can only wait on " << MAXIMUM_WAIT_OBJECTS << " with WaitMany"; | |
81 | |
82 for (size_t i = 0; i < count; ++i) | |
83 handles[i] = events[i]->handle(); | |
84 | |
85 // The cast is safe because count is small - see the CHECK above. | |
86 DWORD result = | |
87 WaitForMultipleObjects(static_cast<DWORD>(count), | |
88 handles, | |
89 FALSE, // don't wait for all the objects | |
90 INFINITE); // no timeout | |
91 if (result >= WAIT_OBJECT_0 + count) { | |
92 NOTREACHED() << "WaitForMultipleObjects failed: " << GetLastError(); | |
93 return 0; | |
94 } | |
95 | |
96 return result - WAIT_OBJECT_0; | |
97 } | |
98 | |
99 } // namespace base | |
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