/*

 * Copyright (C) 2009 Google Inc. All rights reserved.

 *

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 * 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.

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 * 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,

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 */

#ifndef MessagePortChannel_h

#define MessagePortChannel_h

#include "PlatformString.h"

#include "SerializedScriptValue.h"

#include <wtf/OwnPtr.h>

#include <wtf/PassOwnPtr.h>

#include <wtf/PassRefPtr.h>

#include <wtf/RefCounted.h>

#include <wtf/RefPtr.h>

namespace WebCore {

    class MessagePort;

    class MessagePortChannel;

    class PlatformMessagePortChannel;

    class ScriptExecutionContext;

    class SerializedScriptValue;

    class String;

    // The overwhelmingly common case is sending a single port, so handle that efficiently with an inline buffer of size 1.

    typedef Vector<OwnPtr<MessagePortChannel>, 1> MessagePortChannelArray;

    // MessagePortChannel is a platform-independent interface to the remote side of a message channel.

    // It acts as a wrapper around the platform-dependent PlatformMessagePortChannel implementation which ensures that the platform-dependent close() method is invoked before destruction.

    class MessagePortChannel : public Noncopyable {

    public:

        static void createChannel(PassRefPtr<MessagePort>, PassRefPtr<MessagePort>);

        // Creates a new wrapper for the passed channel.

        static PassOwnPtr<MessagePortChannel> create(PassRefPtr<PlatformMessagePortChannel>);

        // Entangles the channel with a port (called when a port has been cloned, after the clone has been marshaled to its new owning thread and is ready to receive messages).

        // Returns false if the entanglement failed because the port was closed.

        bool entangleIfOpen(MessagePort*);

        // Disentangles the channel from a given port so it no longer forwards messages to the port. Called when the port is being cloned and no new owning thread has yet been established.

        void disentangle();

        // Closes the port (ensures that no further messages can be added to either queue).

        void close();

        // Used by MessagePort.postMessage() to prevent callers from passing a port's own entangled port.

        bool isConnectedTo(MessagePort*);

        // Returns true if the proxy currently contains messages for this port.

        bool hasPendingActivity();

        class EventData : public Noncopyable {

        public:

            static PassOwnPtr<EventData> create(PassRefPtr<SerializedScriptValue>, PassOwnPtr<MessagePortChannelArray>);

            SerializedScriptValue* message() { return m_message.get(); }

            PassOwnPtr<MessagePortChannelArray> channels() { return m_channels.release(); }

        private:

            EventData(PassRefPtr<SerializedScriptValue> message, PassOwnPtr<MessagePortChannelArray>);

            RefPtr<SerializedScriptValue> m_message;

            OwnPtr<MessagePortChannelArray> m_channels;

        };

        // Sends a message and optional cloned port to the remote port.

        void postMessageToRemote(PassOwnPtr<EventData>);

        // Extracts a message from the message queue for this port.

        bool tryGetMessageFromRemote(OwnPtr<EventData>&);

        // Returns the entangled port if run by the same thread (see MessagePort::locallyEntangledPort() for more details).

        MessagePort* locallyEntangledPort(const ScriptExecutionContext*);

        ~MessagePortChannel();

        PlatformMessagePortChannel* channel() const { return m_channel.get(); }

    private:

        MessagePortChannel(PassRefPtr<PlatformMessagePortChannel>);

        RefPtr<PlatformMessagePortChannel> m_channel;

    };

} // namespace WebCore

#endif // MessagePortChannel_h