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// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/synchronization/waitable_event.h"
#include <windows.h>
#include "base/logging.h"
#include "base/numerics/safe_conversions.h"
#include "base/threading/thread_restrictions.h"
#include "base/time/time.h"
namespace base {
WaitableEvent::WaitableEvent(bool manual_reset, bool signaled)
: handle_(CreateEvent(NULL, manual_reset, signaled, NULL)) {
// We're probably going to crash anyways if this is ever NULL, so we might as
// well make our stack reports more informative by crashing here.
CHECK(handle_.IsValid());
}
WaitableEvent::WaitableEvent(win::ScopedHandle handle)
: handle_(handle.Pass()) {
CHECK(handle_.IsValid()) << "Tried to create WaitableEvent from NULL handle";
}
WaitableEvent::~WaitableEvent() {
}
void WaitableEvent::Reset() {
ResetEvent(handle_.Get());
}
void WaitableEvent::Signal() {
SetEvent(handle_.Get());
}
bool WaitableEvent::IsSignaled() {
return TimedWait(TimeDelta());
}
void WaitableEvent::Wait() {
base::ThreadRestrictions::AssertWaitAllowed();
DWORD result = WaitForSingleObject(handle_.Get(), INFINITE);
// It is most unexpected that this should ever fail. Help consumers learn
// about it if it should ever fail.
DCHECK_EQ(WAIT_OBJECT_0, result) << "WaitForSingleObject failed";
}
bool WaitableEvent::TimedWait(const TimeDelta& max_time) {
base::ThreadRestrictions::AssertWaitAllowed();
DCHECK_GE(max_time, TimeDelta());
// Truncate the timeout to milliseconds. The API specifies that this method
// can return in less than |max_time| (when returning false), as the argument
// is the maximum time that a caller is willing to wait.
DWORD timeout = saturated_cast<DWORD>(max_time.InMilliseconds());
DWORD result = WaitForSingleObject(handle_.Get(), timeout);
switch (result) {
case WAIT_OBJECT_0:
return true;
case WAIT_TIMEOUT:
return false;
}
// It is most unexpected that this should ever fail. Help consumers learn
// about it if it should ever fail.
NOTREACHED() << "WaitForSingleObject failed";
return false;
}
// static
size_t WaitableEvent::WaitMany(WaitableEvent** events, size_t count) {
base::ThreadRestrictions::AssertWaitAllowed();
HANDLE handles[MAXIMUM_WAIT_OBJECTS];
CHECK_LE(count, MAXIMUM_WAIT_OBJECTS)
<< "Can only wait on " << MAXIMUM_WAIT_OBJECTS << " with WaitMany";
for (size_t i = 0; i < count; ++i)
handles[i] = events[i]->handle();
// The cast is safe because count is small - see the CHECK above.
DWORD result =
WaitForMultipleObjects(static_cast<DWORD>(count),
handles,
FALSE, // don't wait for all the objects
INFINITE); // no timeout
if (result >= WAIT_OBJECT_0 + count) {
DPLOG(FATAL) << "WaitForMultipleObjects failed";
return 0;
}
return result - WAIT_OBJECT_0;
}
} // namespace base
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