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// Copyright (c) 2010 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.
#ifndef BASE_MESSAGE_LOOP_PROXY_H_
#define BASE_MESSAGE_LOOP_PROXY_H_
#include "base/basictypes.h"
#include "base/ref_counted.h"
#include "base/task.h"
namespace base {
struct MessageLoopProxyTraits;
// This class provides a thread-safe refcounted interface to the Post* methods
// of a message loop. This class can outlive the target message loop.
class MessageLoopProxy
: public base::RefCountedThreadSafe<MessageLoopProxy,
MessageLoopProxyTraits> {
public:
// These are the same methods in message_loop.h, but are guaranteed to either
// get posted to the MessageLoop if it's still alive, or be deleted otherwise.
// They return true iff the thread existed and the task was posted. Note that
// even if the task is posted, there's no guarantee that it will run, since
// the target thread may already have a Quit message in its queue.
virtual bool PostTask(const tracked_objects::Location& from_here,
Task* task) = 0;
virtual bool PostDelayedTask(const tracked_objects::Location& from_here,
Task* task, int64 delay_ms) = 0;
virtual bool PostNonNestableTask(const tracked_objects::Location& from_here,
Task* task) = 0;
virtual bool PostNonNestableDelayedTask(
const tracked_objects::Location& from_here,
Task* task,
int64 delay_ms) = 0;
// A method which checks if the caller is currently running in the thread that
// this proxy represents.
virtual bool BelongsToCurrentThread() = 0;
template <class T>
bool DeleteSoon(const tracked_objects::Location& from_here,
T* object) {
return PostNonNestableTask(from_here, new DeleteTask<T>(object));
}
template <class T>
bool ReleaseSoon(const tracked_objects::Location& from_here,
T* object) {
return PostNonNestableTask(from_here, new ReleaseTask<T>(object));
}
// Factory method for creating an implementation of MessageLoopProxy
// for the current thread.
static scoped_refptr<MessageLoopProxy> CreateForCurrentThread();
protected:
friend struct MessageLoopProxyTraits;
virtual ~MessageLoopProxy() { }
// Called when the proxy is about to be deleted. Subclasses can override this
// to provide deletion on specific threads.
virtual void OnDestruct() {
delete this;
}
};
struct MessageLoopProxyTraits {
static void Destruct(MessageLoopProxy* proxy) {
proxy->OnDestruct();
}
};
} // namespace base
#endif // BASE_MESSAGE_LOOP_PROXY_H_
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