Source/core/dom/MessagePort.h

/*
 * Copyright (C) 2008 Apple Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``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 APPLE COMPUTER, INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#ifndef MessagePort_h
#define MessagePort_h

#include "bindings/v8/ScriptWrappable.h"
#include "core/dom/EventListener.h"
#include "core/dom/EventTarget.h"
#include "core/dom/MessagePortChannel.h"
#include "wtf/Forward.h"
#include "wtf/OwnPtr.h"
#include "wtf/PassOwnPtr.h"
#include "wtf/PassRefPtr.h"
#include "wtf/RefPtr.h"
#include "wtf/Vector.h"

namespace WebCore {

class Event;
class ExceptionState;
class Frame;
class MessagePort;
class ScriptExecutionContext;

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

class MessagePort : public RefCounted<MessagePort>, public ScriptWrappable, public EventTarget {
public:
    static PassRefPtr<MessagePort> create(ScriptExecutionContext& scriptExecutionContext) { return adoptRef(new MessagePort(scriptExecutionContext)); }
    virtual ~MessagePort();

    void postMessage(PassRefPtr<SerializedScriptValue> message, const MessagePortArray*, ExceptionState&);

    void start();
    void close();

    void entangle(PassOwnPtr<MessagePortChannel>);
    PassOwnPtr<MessagePortChannel> disentangle();

    // Returns 0 if there is an exception, or if the passed-in array is 0/empty.
    static PassOwnPtr<MessagePortChannelArray> disentanglePorts(const MessagePortArray*, ExceptionState&);

    // Returns 0 if the passed array is 0/empty.
    static PassOwnPtr<MessagePortArray> entanglePorts(ScriptExecutionContext&, PassOwnPtr<MessagePortChannelArray>);

    void messageAvailable();
    bool started() const { return m_started; }

    void contextDestroyed();

    virtual const AtomicString& interfaceName() const OVERRIDE;
    virtual ScriptExecutionContext* scriptExecutionContext() const OVERRIDE;
    MessagePort* toMessagePort() OVERRIDE { return this; }

    void dispatchMessages();

    using RefCounted<MessagePort>::ref;
    using RefCounted<MessagePort>::deref;

    bool hasPendingActivity();

    void setOnmessage(PassRefPtr<EventListener> listener, DOMWrapperWorld* world)
    {
        setAttributeEventListener(eventNames().messageEvent, listener, world);
        start();
    }
    EventListener* onmessage(DOMWrapperWorld* world) { return getAttributeEventListener(eventNames().messageEvent, world); }

    // Returns null if there is no entangled port, or if the entangled port is run by a different thread.
    // This is used solely to enable a GC optimization. Some platforms may not be able to determine ownership
    // of the remote port (since it may live cross-process) - those platforms may always return null.
    MessagePort* locallyEntangledPort();

    // A port starts out its life entangled, and remains entangled until it is closed or is cloned.
    bool isEntangled() { return !m_closed && !isNeutered(); }

    // A port gets neutered when it is transferred to a new owner via postMessage().
    bool isNeutered() { return !m_entangledChannel; }

private:
    explicit MessagePort(ScriptExecutionContext&);

    virtual void refEventTarget() OVERRIDE { ref(); }
    virtual void derefEventTarget() OVERRIDE { deref(); }
    virtual EventTargetData* eventTargetData() OVERRIDE;
    virtual EventTargetData* ensureEventTargetData() OVERRIDE;

    OwnPtr<MessagePortChannel> m_entangledChannel;

    bool m_started;
    bool m_closed;

    ScriptExecutionContext* m_scriptExecutionContext;
    EventTargetData m_eventTargetData;
};

} // namespace WebCore

#endif // MessagePort_h