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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 "core/dom/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         class EventData {
     50             WTF_MAKE_NONCOPYABLE(EventData); WTF_MAKE_FAST_ALLOCATED;
     51         public:
     52             static PassOwnPtr<EventData> create(PassRefPtr<SerializedScriptValue>, PassOwnPtr<MessagePortChannelArray>);
     53 
     54             PassRefPtr<SerializedScriptValue> message() { return m_message; }
     55             PassOwnPtr<MessagePortChannelArray> channels() { return m_channels.release(); }
     56 
     57         private:
     58             EventData(PassRefPtr<SerializedScriptValue> message, PassOwnPtr<MessagePortChannelArray>);
     59             RefPtr<SerializedScriptValue> m_message;
     60             OwnPtr<MessagePortChannelArray> m_channels;
     61         };
     62 
     63         // Wrapper for MessageQueue that allows us to do thread safe sharing by two proxies.
     64         class MessagePortQueue : public ThreadSafeRefCounted<MessagePortQueue> {
     65         public:
     66             static PassRefPtr<MessagePortQueue> create() { return adoptRef(new MessagePortQueue()); }
     67 
     68             PassOwnPtr<PlatformMessagePortChannel::EventData> tryGetMessage()
     69             {
     70                 return m_queue.tryGetMessage();
     71             }
     72 
     73             bool appendAndCheckEmpty(PassOwnPtr<PlatformMessagePortChannel::EventData> message)
     74             {
     75                 return m_queue.appendAndCheckEmpty(message);
     76             }
     77 
     78             bool isEmpty()
     79             {
     80                 return m_queue.isEmpty();
     81             }
     82 
     83         private:
     84             MessagePortQueue() { }
     85 
     86             MessageQueue<PlatformMessagePortChannel::EventData> m_queue;
     87         };
     88 
     89         ~PlatformMessagePortChannel();
     90 
     91         static PassRefPtr<PlatformMessagePortChannel> create(PassRefPtr<MessagePortQueue> incoming, PassRefPtr<MessagePortQueue> outgoing);
     92         PlatformMessagePortChannel(PassRefPtr<MessagePortQueue> incoming, PassRefPtr<MessagePortQueue> outgoing);
     93 
     94         PassRefPtr<PlatformMessagePortChannel> entangledChannel();
     95 
     96         void setRemotePort(MessagePort*);
     97         void closeInternal();
     98 
     99         // Mutex used to ensure exclusive access to the object internals.
    100         Mutex m_mutex;
    101 
    102         // Pointer to our entangled pair - cleared when close() is called.
    103         RefPtr<PlatformMessagePortChannel> m_entangledChannel;
    104 
    105         // Reference to the message queue for the (local) entangled port.
    106         RefPtr<MessagePortQueue> m_incomingQueue;
    107         RefPtr<MessagePortQueue> m_outgoingQueue;
    108 
    109         // The port we are connected to (the remote port) - this is the port that is notified when new messages arrive.
    110         MessagePort* m_remotePort;
    111     };
    112 
    113 } // namespace WebCore
    114 
    115 #endif // PlatformMessagePortChannel_h
    116