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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 | |
3 // found in the LICENSE file. | |
4 | |
5 #include "base/synchronization/waitable_event.h" | |
6 | |
7 #include <windows.h> | |
8 | |
9 #include "base/logging.h" | |
10 #include "base/numerics/safe_conversions.h" | |
11 #include "base/threading/thread_restrictions.h" | |
12 #include "base/time/time.h" | |
13 | |
14 namespace base { | |
15 | |
16 WaitableEvent::WaitableEvent(bool manual_reset, bool signaled) | |
17 : handle_(CreateEvent(NULL, manual_reset, signaled, NULL)) { | |
18 // We're probably going to crash anyways if this is ever NULL, so we might as | |
19 // well make our stack reports more informative by crashing here. | |
20 CHECK(handle_.IsValid()); | |
21 } | |
22 | |
23 WaitableEvent::WaitableEvent(win::ScopedHandle handle) | |
24 : handle_(handle.Pass()) { | |
25 CHECK(handle_.IsValid()) << "Tried to create WaitableEvent from NULL handle"; | |
26 } | |
27 | |
28 WaitableEvent::~WaitableEvent() { | |
29 } | |
30 | |
31 void WaitableEvent::Reset() { | |
32 ResetEvent(handle_.Get()); | |
33 } | |
34 | |
35 void WaitableEvent::Signal() { | |
36 SetEvent(handle_.Get()); | |
37 } | |
38 | |
39 bool WaitableEvent::IsSignaled() { | |
40 return TimedWait(TimeDelta()); | |
41 } | |
42 | |
43 void WaitableEvent::Wait() { | |
44 base::ThreadRestrictions::AssertWaitAllowed(); | |
45 DWORD result = WaitForSingleObject(handle_.Get(), INFINITE); | |
46 // It is most unexpected that this should ever fail. Help consumers learn | |
47 // about it if it should ever fail. | |
48 DCHECK_EQ(WAIT_OBJECT_0, result) << "WaitForSingleObject failed"; | |
49 } | |
50 | |
51 bool WaitableEvent::TimedWait(const TimeDelta& max_time) { | |
52 base::ThreadRestrictions::AssertWaitAllowed(); | |
53 DCHECK_GE(max_time, TimeDelta()); | |
54 // Truncate the timeout to milliseconds. The API specifies that this method | |
55 // can return in less than |max_time| (when returning false), as the argument | |
56 // is the maximum time that a caller is willing to wait. | |
57 DWORD timeout = saturated_cast<DWORD>(max_time.InMilliseconds()); | |
58 | |
59 DWORD result = WaitForSingleObject(handle_.Get(), timeout); | |
60 switch (result) { | |
61 case WAIT_OBJECT_0: | |
62 return true; | |
63 case WAIT_TIMEOUT: | |
64 return false; | |
65 } | |
66 // It is most unexpected that this should ever fail. Help consumers learn | |
67 // about it if it should ever fail. | |
68 NOTREACHED() << "WaitForSingleObject failed"; | |
69 return false; | |
70 } | |
71 | |
72 // static | |
73 size_t WaitableEvent::WaitMany(WaitableEvent** events, size_t count) { | |
74 base::ThreadRestrictions::AssertWaitAllowed(); | |
75 HANDLE handles[MAXIMUM_WAIT_OBJECTS]; | |
76 CHECK_LE(count, MAXIMUM_WAIT_OBJECTS) | |
77 << "Can only wait on " << MAXIMUM_WAIT_OBJECTS << " with WaitMany"; | |
78 | |
79 for (size_t i = 0; i < count; ++i) | |
80 handles[i] = events[i]->handle(); | |
81 | |
82 // The cast is safe because count is small - see the CHECK above. | |
83 DWORD result = | |
84 WaitForMultipleObjects(static_cast<DWORD>(count), | |
85 handles, | |
86 FALSE, // don't wait for all the objects | |
87 INFINITE); // no timeout | |
88 if (result >= WAIT_OBJECT_0 + count) { | |
89 DPLOG(FATAL) << "WaitForMultipleObjects failed"; | |
90 return 0; | |
91 } | |
92 | |
93 return result - WAIT_OBJECT_0; | |
94 } | |
95 | |
96 } // namespace base | |
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