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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 "bindings/v8/SerializedScriptValue.h"
     35 #include "wtf/Forward.h"
     36 #include "wtf/PassOwnPtr.h"
     37 #include "wtf/RefPtr.h"
     38 
     39 namespace WebCore {
     40 
     41     class MessagePort;
     42     class MessagePortChannel;
     43     class PlatformMessagePortChannel;
     44     class ScriptExecutionContext;
     45     class SerializedScriptValue;
     46 
     47     // The overwhelmingly common case is sending a single port, so handle that efficiently with an inline buffer of size 1.
     48     typedef Vector<OwnPtr<MessagePortChannel>, 1> MessagePortChannelArray;
     49 
     50     // MessagePortChannel is a platform-independent interface to the remote side of a message channel.
     51     // It acts as a wrapper around the platform-dependent PlatformMessagePortChannel implementation which ensures that the platform-dependent close() method is invoked before destruction.
     52     class MessagePortChannel {
     53         WTF_MAKE_NONCOPYABLE(MessagePortChannel); WTF_MAKE_FAST_ALLOCATED;
     54     public:
     55         static void createChannel(PassRefPtr<MessagePort>, PassRefPtr<MessagePort>);
     56 
     57         // 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).
     58         // Returns false if the entanglement failed because the port was closed.
     59         bool entangleIfOpen(MessagePort*);
     60 
     61         // 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.
     62         void disentangle();
     63 
     64         // Closes the port (ensures that no further messages can be added to either queue).
     65         void close();
     66 
     67         // Used by MessagePort.postMessage() to prevent callers from passing a port's own entangled port.
     68         bool isConnectedTo(MessagePort*);
     69 
     70         // Returns true if the proxy currently contains messages for this port.
     71         bool hasPendingActivity();
     72 
     73         // Sends a message and optional cloned port to the remote port.
     74         void postMessageToRemote(PassRefPtr<SerializedScriptValue>, PassOwnPtr<MessagePortChannelArray>);
     75 
     76         // Extracts a message from the message queue for this port.
     77         bool tryGetMessageFromRemote(RefPtr<SerializedScriptValue>&, OwnPtr<MessagePortChannelArray>&);
     78 
     79         // Returns the entangled port if run by the same thread (see MessagePort::locallyEntangledPort() for more details).
     80         MessagePort* locallyEntangledPort(const ScriptExecutionContext*);
     81 
     82         ~MessagePortChannel();
     83 
     84         // Creates a new wrapper for the passed channel.
     85         static PassOwnPtr<MessagePortChannel> create(PassRefPtr<PlatformMessagePortChannel>);
     86 
     87         // FIXME: PlatformMessagePortChannel is an implementation detail, and should not be exposed via a public function.
     88         PlatformMessagePortChannel* channel() const { return m_channel.get(); }
     89 
     90     private:
     91         explicit MessagePortChannel(PassRefPtr<PlatformMessagePortChannel>);
     92         RefPtr<PlatformMessagePortChannel> m_channel;
     93     };
     94 
     95 } // namespace WebCore
     96 
     97 #endif // MessagePortChannel_h
     98