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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 PlatformMessagePortChannel_h
     32 #define PlatformMessagePortChannel_h
     33 
     34 #include "MessagePortChannel.h"
     35 
     36 #include <wtf/MessageQueue.h>
     37 #include <wtf/PassRefPtr.h>
     38 #include <wtf/Threading.h>
     39 
     40 namespace WebCore {
     41 
     42     class MessagePort;
     43 
     44     // PlatformMessagePortChannel is a platform-dependent interface to the remote side of a message channel.
     45     // This default implementation supports multiple threads running within a single process. Implementations for multi-process platforms should define these public APIs in their own platform-specific PlatformMessagePortChannel file.
     46     // The goal of this implementation is to eliminate contention except when cloning or closing the port, so each side of the channel has its own separate mutex.
     47     class PlatformMessagePortChannel : public ThreadSafeRefCounted<PlatformMessagePortChannel> {
     48     public:
     49         static void createChannel(PassRefPtr<MessagePort>, PassRefPtr<MessagePort>);
     50 
     51         // APIs delegated from MessagePortChannel.h
     52         bool entangleIfOpen(MessagePort*);
     53         void disentangle();
     54         void postMessageToRemote(PassOwnPtr<MessagePortChannel::EventData>);
     55         bool tryGetMessageFromRemote(OwnPtr<MessagePortChannel::EventData>&);
     56         void close();
     57         bool isConnectedTo(MessagePort*);
     58         bool hasPendingActivity();
     59         MessagePort* locallyEntangledPort(const ScriptExecutionContext*);
     60 
     61         // Wrapper for MessageQueue that allows us to do thread safe sharing by two proxies.
     62         class MessagePortQueue : public ThreadSafeRefCounted<MessagePortQueue> {
     63         public:
     64             static PassRefPtr<MessagePortQueue> create() { return adoptRef(new MessagePortQueue()); }
     65 
     66             PassOwnPtr<MessagePortChannel::EventData> tryGetMessage()
     67             {
     68                 return m_queue.tryGetMessage();
     69             }
     70 
     71             bool appendAndCheckEmpty(PassOwnPtr<MessagePortChannel::EventData> message)
     72             {
     73                 return m_queue.appendAndCheckEmpty(message);
     74             }
     75 
     76             bool isEmpty()
     77             {
     78                 return m_queue.isEmpty();
     79             }
     80 
     81         private:
     82             MessagePortQueue() { }
     83 
     84             MessageQueue<MessagePortChannel::EventData> m_queue;
     85         };
     86 
     87         ~PlatformMessagePortChannel();
     88 
     89     private:
     90         static PassRefPtr<PlatformMessagePortChannel> create(PassRefPtr<MessagePortQueue> incoming, PassRefPtr<MessagePortQueue> outgoing);
     91         PlatformMessagePortChannel(PassRefPtr<MessagePortQueue> incoming, PassRefPtr<MessagePortQueue> outgoing);
     92 
     93         PassRefPtr<PlatformMessagePortChannel> entangledChannel();
     94         void setEntangledChannel(PassRefPtr<PlatformMessagePortChannel>);
     95 
     96         void setRemotePort(MessagePort*);
     97         MessagePort* remotePort();
     98         void closeInternal();
     99 
    100         // Mutex used to ensure exclusive access to the object internals.
    101         Mutex m_mutex;
    102 
    103         // Pointer to our entangled pair - cleared when close() is called.
    104         RefPtr<PlatformMessagePortChannel> m_entangledChannel;
    105 
    106         // Reference to the message queue for the (local) entangled port.
    107         RefPtr<MessagePortQueue> m_incomingQueue;
    108         RefPtr<MessagePortQueue> m_outgoingQueue;
    109 
    110         // The port we are connected to (the remote port) - this is the port that is notified when new messages arrive.
    111         MessagePort* m_remotePort;
    112     };
    113 
    114 } // namespace WebCore
    115 
    116 #endif // PlatformMessagePortChannel_h
    117