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 ThreadSafeShared<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 ThreadSafeShared<MessagePortQueue> { 63 public: create()64 static PassRefPtr<MessagePortQueue> create() { return adoptRef(new MessagePortQueue()); } 65 tryGetMessage(OwnPtr<MessagePortChannel::EventData> & message)66 bool tryGetMessage(OwnPtr<MessagePortChannel::EventData>& message) 67 { 68 MessagePortChannel::EventData* holder = 0; 69 bool messageAvailable = m_queue.tryGetMessage(holder); 70 if (messageAvailable) 71 message.set(holder); 72 return messageAvailable; 73 } 74 appendAndCheckEmpty(PassOwnPtr<MessagePortChannel::EventData> message)75 bool appendAndCheckEmpty(PassOwnPtr<MessagePortChannel::EventData> message) 76 { 77 return m_queue.appendAndCheckEmpty(message.release()); 78 } 79 isEmpty()80 bool isEmpty() 81 { 82 return m_queue.isEmpty(); 83 } 84 ~MessagePortQueue()85 ~MessagePortQueue() 86 { 87 // Manually free any items left in the queue, since we can't use OwnPtr internally. 88 MessagePortChannel::EventData* data = 0; 89 while (m_queue.tryGetMessage(data)) 90 delete data; 91 } 92 private: MessagePortQueue()93 MessagePortQueue() { } 94 95 // OwnPtr is Noncopyable, so we can't use it as the template type in a MessageQueue. So we just store a pointer to EventData and manually free it in the destructor. 96 // FIXME: Use a lock-free queue implementation to completely eliminate contention when sending/receiving messages. 97 MessageQueue<MessagePortChannel::EventData*> m_queue; 98 }; 99 100 ~PlatformMessagePortChannel(); 101 102 private: 103 static PassRefPtr<PlatformMessagePortChannel> create(PassRefPtr<MessagePortQueue> incoming, PassRefPtr<MessagePortQueue> outgoing); 104 PlatformMessagePortChannel(PassRefPtr<MessagePortQueue> incoming, PassRefPtr<MessagePortQueue> outgoing); 105 106 PassRefPtr<PlatformMessagePortChannel> entangledChannel(); 107 void setEntangledChannel(PassRefPtr<PlatformMessagePortChannel>); 108 109 void setRemotePort(MessagePort*); 110 MessagePort* remotePort(); 111 void closeInternal(); 112 113 // Mutex used to ensure exclusive access to the object internals. 114 Mutex m_mutex; 115 116 // Pointer to our entangled pair - cleared when close() is called. 117 RefPtr<PlatformMessagePortChannel> m_entangledChannel; 118 119 // Reference to the message queue for the (local) entangled port. 120 RefPtr<MessagePortQueue> m_incomingQueue; 121 RefPtr<MessagePortQueue> m_outgoingQueue; 122 123 // The port we are connected to (the remote port) - this is the port that is notified when new messages arrive. 124 MessagePort* m_remotePort; 125 }; 126 127 } // namespace WebCore 128 129 #endif // PlatformMessagePortChannel_h 130