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// Copyright 2014 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 MOJO_EDK_SYSTEM_CHANNEL_ENDPOINT_CLIENT_H_
#define MOJO_EDK_SYSTEM_CHANNEL_ENDPOINT_CLIENT_H_
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/memory/scoped_ptr.h"
#include "mojo/edk/system/system_impl_export.h"
namespace mojo {
namespace system {
class MessageInTransit;
// Interface for receivers of messages from |ChannelEndpoint| (hence from
// |Channel|). |port| is simply the value passed to |ChannelEndpoint| on
// construction, and provides a lightweight way for an object to be the client
// of multiple |ChannelEndpoint|s. (|MessagePipe| implements this interface, in
// which case |port| is the port number for the |ProxyMessagePipeEndpoint|
// corresdponding to the |ChannelEndpoint|.)
//
// Implementations of this class should be thread-safe. |ChannelEndpointClient|
// *precedes* |ChannelEndpoint| in the lock order, so |ChannelEndpoint| should
// never call into this class with its lock held. (Instead, it should take a
// reference under its lock, release its lock, and make any needed call(s).)
//
// Note: As a consequence of this, all the client methods may be called even
// after |ChannelEndpoint::DetachFromClient()| has been called (so the
// |ChannelEndpoint| has apparently relinquished its pointer to the
// |ChannelEndpointClient|).
class MOJO_SYSTEM_IMPL_EXPORT ChannelEndpointClient
: public base::RefCountedThreadSafe<ChannelEndpointClient> {
public:
// Called by |ChannelEndpoint| in response to its |OnReadMessage()|, which is
// called by |Channel| when it receives a message for the |ChannelEndpoint|.
// (|port| is the value passed to |ChannelEndpoint|'s constructor as
// |client_port|.)
//
// This should return true if it accepted (and took ownership of) |message|.
virtual bool OnReadMessage(unsigned port, MessageInTransit* message) = 0;
// Called by |ChannelEndpoint| when the |Channel| is relinquishing its pointer
// to the |ChannelEndpoint| (and vice versa). After this is called,
// |OnReadMessage()| will no longer be called.
virtual void OnDetachFromChannel(unsigned port) = 0;
protected:
ChannelEndpointClient() {}
virtual ~ChannelEndpointClient() {}
friend class base::RefCountedThreadSafe<ChannelEndpointClient>;
private:
DISALLOW_COPY_AND_ASSIGN(ChannelEndpointClient);
};
} // namespace system
} // namespace mojo
#endif // MOJO_EDK_SYSTEM_CHANNEL_ENDPOINT_CLIENT_H_
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