/* * Copyright (C) 2009 Google Inc. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are * met: * * * Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * Redistributions in binary form must reproduce the above * copyright notice, this list of conditions and the following disclaimer * in the documentation and/or other materials provided with the * distribution. * * Neither the name of Google Inc. nor the names of its * contributors may be used to endorse or promote products derived from * this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #ifndef PlatformMessagePortChannel_h #define PlatformMessagePortChannel_h #include "MessagePortChannel.h" #include <wtf/MessageQueue.h> #include <wtf/PassRefPtr.h> #include <wtf/Threading.h> namespace WebCore { class MessagePort; // PlatformMessagePortChannel is a platform-dependent interface to the remote side of a message channel. // 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. // 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. class PlatformMessagePortChannel : public ThreadSafeShared<PlatformMessagePortChannel> { public: static void createChannel(PassRefPtr<MessagePort>, PassRefPtr<MessagePort>); // APIs delegated from MessagePortChannel.h bool entangleIfOpen(MessagePort*); void disentangle(); void postMessageToRemote(PassOwnPtr<MessagePortChannel::EventData>); bool tryGetMessageFromRemote(OwnPtr<MessagePortChannel::EventData>&); void close(); bool isConnectedTo(MessagePort*); bool hasPendingActivity(); MessagePort* locallyEntangledPort(const ScriptExecutionContext*); // Wrapper for MessageQueue that allows us to do thread safe sharing by two proxies. class MessagePortQueue : public ThreadSafeShared<MessagePortQueue> { public: static PassRefPtr<MessagePortQueue> create() { return adoptRef(new MessagePortQueue()); } bool tryGetMessage(OwnPtr<MessagePortChannel::EventData>& message) { MessagePortChannel::EventData* holder = 0; bool messageAvailable = m_queue.tryGetMessage(holder); if (messageAvailable) message.set(holder); return messageAvailable; } bool appendAndCheckEmpty(PassOwnPtr<MessagePortChannel::EventData> message) { return m_queue.appendAndCheckEmpty(message.release()); } bool isEmpty() { return m_queue.isEmpty(); } ~MessagePortQueue() { // Manually free any items left in the queue, since we can't use OwnPtr internally. MessagePortChannel::EventData* data = 0; while (m_queue.tryGetMessage(data)) delete data; } private: MessagePortQueue() { } // 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. // FIXME: Use a lock-free queue implementation to completely eliminate contention when sending/receiving messages. MessageQueue<MessagePortChannel::EventData*> m_queue; }; ~PlatformMessagePortChannel(); private: static PassRefPtr<PlatformMessagePortChannel> create(PassRefPtr<MessagePortQueue> incoming, PassRefPtr<MessagePortQueue> outgoing); PlatformMessagePortChannel(PassRefPtr<MessagePortQueue> incoming, PassRefPtr<MessagePortQueue> outgoing); PassRefPtr<PlatformMessagePortChannel> entangledChannel(); void setEntangledChannel(PassRefPtr<PlatformMessagePortChannel>); void setRemotePort(MessagePort*); MessagePort* remotePort(); void closeInternal(); // Mutex used to ensure exclusive access to the object internals. Mutex m_mutex; // Pointer to our entangled pair - cleared when close() is called. RefPtr<PlatformMessagePortChannel> m_entangledChannel; // Reference to the message queue for the (local) entangled port. RefPtr<MessagePortQueue> m_incomingQueue; RefPtr<MessagePortQueue> m_outgoingQueue; // The port we are connected to (the remote port) - this is the port that is notified when new messages arrive. MessagePort* m_remotePort; }; } // namespace WebCore #endif // PlatformMessagePortChannel_h