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// Copyright 2011 The Chromium Authors
// 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_watcher.h"
#include <windows.h>
#include "base/compiler_specific.h"
#include "base/synchronization/waitable_event.h"
#include "base/win/object_watcher.h"
namespace base {
WaitableEventWatcher::WaitableEventWatcher() = default;
WaitableEventWatcher::~WaitableEventWatcher() = default;
bool WaitableEventWatcher::StartWatching(
WaitableEvent* event,
EventCallback callback,
scoped_refptr<SequencedTaskRunner> task_runner) {
DCHECK(event);
callback_ = std::move(callback);
event_ = event;
// Duplicate and hold the event handle until a callback is returned or
// waiting is stopped.
HANDLE handle = nullptr;
if (!::DuplicateHandle(::GetCurrentProcess(), // hSourceProcessHandle
event->handle(),
::GetCurrentProcess(), // hTargetProcessHandle
&handle,
0, // dwDesiredAccess ignored due to SAME_ACCESS
FALSE, // !bInheritHandle
DUPLICATE_SAME_ACCESS)) {
return false;
}
duplicated_event_handle_.Set(handle);
return watcher_.StartWatchingOnce(handle, this);
}
void WaitableEventWatcher::StopWatching() {
callback_.Reset();
event_ = nullptr;
watcher_.StopWatching();
duplicated_event_handle_.Close();
}
void WaitableEventWatcher::OnObjectSignaled(HANDLE h) {
DCHECK_EQ(duplicated_event_handle_.get(), h);
WaitableEvent* event = event_;
EventCallback callback = std::move(callback_);
event_ = nullptr;
duplicated_event_handle_.Close();
DCHECK(event);
std::move(callback).Run(event);
}
} // namespace base
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