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
40namespace 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