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// Copyright 2008, Google Inc.
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are met:
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// 1. Redistributions of source code must retain the above copyright notice,
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// this list of conditions and the following disclaimer.
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// 2. Redistributions in binary form must reproduce the above copyright notice,
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// this list of conditions and the following disclaimer in the documentation
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// and/or other materials provided with the distribution.
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// 3. Neither the name of Google Inc. nor the names of its contributors may be
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// used to endorse or promote products derived from this software without
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// specific prior written permission.
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// THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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// WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
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// EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
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// OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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// WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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// OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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// ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#ifndef GEARS_BASE_COMMON_ASYNC_ROUTER_H__
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#define GEARS_BASE_COMMON_ASYNC_ROUTER_H__
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#include "gears/base/common/basictypes.h" // for DISALLOW_EVIL_CONSTRUCTORS
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#include "gears/base/common/message_queue.h"
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// Clients implement this interface to receive an asynchronous call.
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class AsyncFunctor : public MessageData {
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virtual void Run() = 0;
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// Clients implement this interface to receive a synchronous call.
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// WARNING: Make certain Run does minimal work. If this results in a sync call
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// back to the source thread, it will deadlock.
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class SyncFunctor : public MessageData {
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virtual void Run() = 0;
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friend class AsyncRouter;
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void SignalHandledEvent() {
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handled_event_->Signal();
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void SetHandledEvent(Event *handled_event) {
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handled_event_ = handled_event;
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Event *handled_event_;
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// This is a simple class that facilitates running a method asynchronously on
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// a target thread. The ThreadMessageQueue with the given thread_id must be
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class AsyncRouter : public ThreadMessageQueue::HandlerInterface {
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// Returns a pointer to the AsyncRouter singleton.
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static AsyncRouter *GetInstance();
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// Calls the functor's Run() method from the thread specified by thread_id.
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// Ownership of the functor is transferred to the AsyncRouter.
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bool CallAsync(ThreadId thread_id, AsyncFunctor *functor);
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bool CallSync(ThreadId thread_id, SyncFunctor *functor);
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// ThreadMessageQueue::HandlerInterface override
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virtual void HandleThreadMessage(int message_type, MessageData *message_data);
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DISALLOW_EVIL_CONSTRUCTORS(AsyncRouter);
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#endif // GEARS_BASE_COMMON_ASYNC_ROUTER_H__