Merge in WebKit r47029.

1 files changed, 129 insertions, 0 deletions

diff --git a/WebCore/dom/default/PlatformMessagePortChannel.h b/WebCore/dom/default/PlatformMessagePortChannel.h
new file mode 100644
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+++ b/WebCore/dom/default/PlatformMessagePortChannel.h
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+/*
+ * 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