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// Copyright 2015 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 BLIMP_NET_BLIMP_MESSAGE_THREAD_PIPE_H_
#define BLIMP_NET_BLIMP_MESSAGE_THREAD_PIPE_H_
#include "base/memory/ref_counted.h"
#include "base/memory/scoped_ptr.h"
#include "base/memory/weak_ptr.h"
#include "blimp/net/blimp_net_export.h"
namespace base {
class SequencedTaskRunner;
}
namespace blimp {
class BlimpMessage;
class BlimpMessageProcessor;
// Uni-directional MessageProcessor "pipe" that accepts messages on
// one thread and dispatches them to a MessageProcessor on a different
// thread.
//
// Typical usage involves:
// 1. Create the pipe on the "main" thread, specifying the target thread's
// task runner.
// 2. Take one or more MessageProcessor proxies from it.
// 3. Post a task to the target thread to set the target MessageProcessor.
// 4. Start using the MessageProcessor proxy(/ies) on the main thread.
// 5. When the target MessageProcessor is about to be destroyed on the
// target thread, destroy the pipe instance immediately beforehand.
// Any messages that are subsequently passed to a proxy, or are already
// in-flight to the pipe, will be silently dropped.
class BLIMP_NET_EXPORT BlimpMessageThreadPipe {
public:
explicit BlimpMessageThreadPipe(
const scoped_refptr<base::SequencedTaskRunner>& task_runner);
~BlimpMessageThreadPipe();
// Creates a proxy MessageProcessor that routes messages to
// the outgoing MessageProcessor on |task_runner|.
// Proxies are safe to create before the outgoing MessageProcessor
// has been set, but cannot be used until it has after been set -
// see the class-level comment on usage.
// Proxies must be deleted on the thread on which they are used.
scoped_ptr<BlimpMessageProcessor> CreateProxy();
// Sets/gets the target MessageProcessor on the target thread.
void set_target_processor(BlimpMessageProcessor* processor);
BlimpMessageProcessor* target_processor() const;
private:
// Target MessageProcessor & TaskRunner to process messages with.
BlimpMessageProcessor* target_processor_ = nullptr;
scoped_refptr<base::SequencedTaskRunner> target_task_runner_;
// Allows |this| to be safely detached from existing proxies on deletion.
base::WeakPtrFactory<BlimpMessageThreadPipe> weak_factory_;
DISALLOW_COPY_AND_ASSIGN(BlimpMessageThreadPipe);
};
} // namespace blimp
#endif // BLIMP_NET_BLIMP_MESSAGE_THREAD_PIPE_H_
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