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      1 /*
      2  * Copyright (C) 2009 Google Inc. All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions are
      6  * met:
      7  *
      8  *     * Redistributions of source code must retain the above copyright
      9  * notice, this list of conditions and the following disclaimer.
     10  *     * Redistributions in binary form must reproduce the above
     11  * copyright notice, this list of conditions and the following disclaimer
     12  * in the documentation and/or other materials provided with the
     13  * distribution.
     14  *     * Neither the name of Google Inc. nor the names of its
     15  * contributors may be used to endorse or promote products derived from
     16  * this software without specific prior written permission.
     17  *
     18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     22  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     24  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     29  */
     30 
     31 #ifndef MessagePortChannel_h
     32 #define MessagePortChannel_h
     33 
     34 #include "PlatformString.h"
     35 
     36 #include "SerializedScriptValue.h"
     37 
     38 #include <wtf/OwnPtr.h>
     39 #include <wtf/PassOwnPtr.h>
     40 #include <wtf/PassRefPtr.h>
     41 #include <wtf/RefCounted.h>
     42 #include <wtf/RefPtr.h>
     43 
     44 namespace WebCore {
     45 
     46     class MessagePort;
     47     class MessagePortChannel;
     48     class PlatformMessagePortChannel;
     49     class ScriptExecutionContext;
     50     class SerializedScriptValue;
     51     class String;
     52 
     53     // The overwhelmingly common case is sending a single port, so handle that efficiently with an inline buffer of size 1.
     54     typedef Vector<OwnPtr<MessagePortChannel>, 1> MessagePortChannelArray;
     55 
     56     // MessagePortChannel is a platform-independent interface to the remote side of a message channel.
     57     // It acts as a wrapper around the platform-dependent PlatformMessagePortChannel implementation which ensures that the platform-dependent close() method is invoked before destruction.
     58     class MessagePortChannel : public Noncopyable {
     59     public:
     60         static void createChannel(PassRefPtr<MessagePort>, PassRefPtr<MessagePort>);
     61 
     62         // Creates a new wrapper for the passed channel.
     63         static PassOwnPtr<MessagePortChannel> create(PassRefPtr<PlatformMessagePortChannel>);
     64 
     65         // 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).
     66         // Returns false if the entanglement failed because the port was closed.
     67         bool entangleIfOpen(MessagePort*);
     68 
     69         // 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.
     70         void disentangle();
     71 
     72         // Closes the port (ensures that no further messages can be added to either queue).
     73         void close();
     74 
     75         // Used by MessagePort.postMessage() to prevent callers from passing a port's own entangled port.
     76         bool isConnectedTo(MessagePort*);
     77 
     78         // Returns true if the proxy currently contains messages for this port.
     79         bool hasPendingActivity();
     80 
     81         class EventData : public Noncopyable {
     82         public:
     83             static PassOwnPtr<EventData> create(PassRefPtr<SerializedScriptValue>, PassOwnPtr<MessagePortChannelArray>);
     84 
     85             SerializedScriptValue* message() { return m_message.get(); }
     86             PassOwnPtr<MessagePortChannelArray> channels() { return m_channels.release(); }
     87 
     88         private:
     89             EventData(PassRefPtr<SerializedScriptValue> message, PassOwnPtr<MessagePortChannelArray>);
     90             RefPtr<SerializedScriptValue> m_message;
     91             OwnPtr<MessagePortChannelArray> m_channels;
     92         };
     93 
     94         // Sends a message and optional cloned port to the remote port.
     95         void postMessageToRemote(PassOwnPtr<EventData>);
     96 
     97         // Extracts a message from the message queue for this port.
     98         bool tryGetMessageFromRemote(OwnPtr<EventData>&);
     99 
    100         // Returns the entangled port if run by the same thread (see MessagePort::locallyEntangledPort() for more details).
    101         MessagePort* locallyEntangledPort(const ScriptExecutionContext*);
    102 
    103         ~MessagePortChannel();
    104 
    105         PlatformMessagePortChannel* channel() const { return m_channel.get(); }
    106 
    107     private:
    108         MessagePortChannel(PassRefPtr<PlatformMessagePortChannel>);
    109         RefPtr<PlatformMessagePortChannel> m_channel;
    110     };
    111 
    112 } // namespace WebCore
    113 
    114 #endif // MessagePortChannel_h
    115