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// Copyright 2008, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#ifndef BASE_OBJECT_WATCHER_H_
#define BASE_OBJECT_WATCHER_H_
#include <windows.h>
#include <map>
#include "base/linked_ptr.h"
#include "base/tracked.h"
class Task;
namespace base {
// A class that enables support for asynchronously waiting for Windows objects
// to become signaled. Supports waiting on more than 64 objects.
class ObjectWatcher {
public:
ObjectWatcher();
~ObjectWatcher();
// When the object is signaled, the given task is run on the thread where
// Watch is called. The ObjectWatcher assumes ownership of the task and
// will ensure that it gets deleted eventually.
//
// NOTE: It is an error to call this method on an object that is already
// being watched by this ObjectWatcher.
//
// Returns true if the watch was added. Otherwise, false is returned.
//
bool AddWatch(const tracked_objects::Location& from_here, HANDLE object,
Task* task);
// Stops watching the given object. Does nothing if the watch has already
// completed. If the watch is still active, then it is canceled, and the
// associated task is deleted.
//
// Returns true if the watch was canceled. Otherwise, false is returned.
//
bool CancelWatch(HANDLE object);
private:
// Called on a background thread when done waiting.
static void CALLBACK DoneWaiting(void* param, BOOLEAN timed_out);
// Passed as the param argument to the above methods.
struct Watch;
typedef std::map<HANDLE, linked_ptr<Watch>> WatchMap;
WatchMap watches_;
};
} // namespace base
#endif // BASE_OBJECT_WATCHER_H_
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