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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/Forward.h>
     40 #include <wtf/PassOwnPtr.h>
     41 #include <wtf/PassRefPtr.h>
     42 #include <wtf/RefCounted.h>
     43 #include <wtf/RefPtr.h>
     44 
     45 namespace WebCore {
     46 
     47     class MessagePort;
     48     class MessagePortChannel;
     49     class PlatformMessagePortChannel;
     50     class ScriptExecutionContext;
     51     class SerializedScriptValue;
     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 {
     59         WTF_MAKE_NONCOPYABLE(MessagePortChannel); WTF_MAKE_FAST_ALLOCATED;
     60     public:
     61         static void createChannel(PassRefPtr<MessagePort>, PassRefPtr<MessagePort>);
     62 
     63         // Creates a new wrapper for the passed channel.
     64         static PassOwnPtr<MessagePortChannel> create(PassRefPtr<PlatformMessagePortChannel>);
     65 
     66         // 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).
     67         // Returns false if the entanglement failed because the port was closed.
     68         bool entangleIfOpen(MessagePort*);
     69 
     70         // 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.
     71         void disentangle();
     72 
     73         // Closes the port (ensures that no further messages can be added to either queue).
     74         void close();
     75 
     76         // Used by MessagePort.postMessage() to prevent callers from passing a port's own entangled port.
     77         bool isConnectedTo(MessagePort*);
     78 
     79         // Returns true if the proxy currently contains messages for this port.
     80         bool hasPendingActivity();
     81 
     82         class EventData {
     83             WTF_MAKE_NONCOPYABLE(EventData); WTF_MAKE_FAST_ALLOCATED;
     84         public:
     85             static PassOwnPtr<EventData> create(PassRefPtr<SerializedScriptValue>, PassOwnPtr<MessagePortChannelArray>);
     86 
     87             SerializedScriptValue* message() { return m_message.get(); }
     88             PassOwnPtr<MessagePortChannelArray> channels() { return m_channels.release(); }
     89 
     90         private:
     91             EventData(PassRefPtr<SerializedScriptValue> message, PassOwnPtr<MessagePortChannelArray>);
     92             RefPtr<SerializedScriptValue> m_message;
     93             OwnPtr<MessagePortChannelArray> m_channels;
     94         };
     95 
     96         // Sends a message and optional cloned port to the remote port.
     97         void postMessageToRemote(PassOwnPtr<EventData>);
     98 
     99         // Extracts a message from the message queue for this port.
    100         bool tryGetMessageFromRemote(OwnPtr<EventData>&);
    101 
    102         // Returns the entangled port if run by the same thread (see MessagePort::locallyEntangledPort() for more details).
    103         MessagePort* locallyEntangledPort(const ScriptExecutionContext*);
    104 
    105         ~MessagePortChannel();
    106 
    107         PlatformMessagePortChannel* channel() const { return m_channel.get(); }
    108 
    109     private:
    110         MessagePortChannel(PassRefPtr<PlatformMessagePortChannel>);
    111         RefPtr<PlatformMessagePortChannel> m_channel;
    112     };
    113 
    114 } // namespace WebCore
    115 
    116 #endif // MessagePortChannel_h
    117