Source/core/dom/MessagePortChannel.h

/*
 * Copyright (C) 2009 Google Inc. All rights reserved.
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 * modification, are permitted provided that the following conditions are
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 * 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
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 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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#ifndef MessagePortChannel_h
#define MessagePortChannel_h

#include "bindings/v8/SerializedScriptValue.h"
#include "public/platform/WebMessagePortChannelClient.h"
#include "wtf/Forward.h"
#include "wtf/PassOwnPtr.h"
#include "wtf/RefPtr.h"
#include "wtf/ThreadSafeRefCounted.h"
#include "wtf/ThreadingPrimitives.h"

namespace WebKit {
class WebMessagePortChannel;
}

namespace WebCore {

class MessagePort;
class MessagePortChannel;
class ExecutionContext;
class SerializedScriptValue;

// The overwhelmingly common case is sending a single port, so handle that efficiently with an inline buffer of size 1.
typedef Vector<RefPtr<MessagePortChannel>, 1> MessagePortChannelArray;

// MessagePortChannel is a platform-independent interface to the remote side of a message channel.
class MessagePortChannel : public ThreadSafeRefCounted<MessagePortChannel>, public WebKit::WebMessagePortChannelClient {
    WTF_MAKE_NONCOPYABLE(MessagePortChannel);
public:
    static void createChannel(MessagePort*, MessagePort*);
    static PassRefPtr<MessagePortChannel> create(WebKit::WebMessagePortChannel*);

    virtual ~MessagePortChannel();

    // 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).
    void entangle(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();

    // Sends a message and optional cloned port to the remote port.
    void postMessageToRemote(PassRefPtr<SerializedScriptValue>, PassOwnPtr<MessagePortChannelArray>);

    // Extracts a message from the message queue for this port.
    bool tryGetMessageFromRemote(RefPtr<SerializedScriptValue>&, OwnPtr<MessagePortChannelArray>&);

    // Releases ownership of the contained web channel.
    WebKit::WebMessagePortChannel* webChannelRelease();

private:
    explicit MessagePortChannel(WebKit::WebMessagePortChannel*);

    void setEntangledChannel(PassRefPtr<MessagePortChannel>);

    // WebKit::WebMessagePortChannelClient implementation
    virtual void messageAvailable() OVERRIDE;

    // Mutex used to ensure exclusive access to the object internals.
    Mutex m_mutex;

    // Pointer to our entangled pair - cleared when close() is called.
    RefPtr<MessagePortChannel> m_entangledChannel;

    // The port we are connected to - this is the port that is notified when new messages arrive.
    MessagePort* m_localPort;

    WebKit::WebMessagePortChannel* m_webChannel;
};

} // namespace WebCore

#endif // MessagePortChannel_h