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 MessagePortChannel_h
32#define MessagePortChannel_h
33
34#include "PlatformString.h"
35
36#include "SerializedScriptValue.h"
37
38#include <wtf/OwnPtr.h>
39#include <wtf/Forward.h>
40#include <wtf/PassOwnPtr.h>
41#include <wtf/PassRefPtr.h>
42#include <wtf/RefCounted.h>
43#include <wtf/RefPtr.h>
44
45namespace WebCore {
46
47    class MessagePort;
48    class MessagePortChannel;
49    class PlatformMessagePortChannel;
50    class ScriptExecutionContext;
51    class SerializedScriptValue;
52
53    // The overwhelmingly common case is sending a single port, so handle that efficiently with an inline buffer of size 1.
54    typedef Vector<OwnPtr<MessagePortChannel>, 1> MessagePortChannelArray;
55
56    // MessagePortChannel is a platform-independent interface to the remote side of a message channel.
57    // It acts as a wrapper around the platform-dependent PlatformMessagePortChannel implementation which ensures that the platform-dependent close() method is invoked before destruction.
58    class MessagePortChannel {
59        WTF_MAKE_NONCOPYABLE(MessagePortChannel); WTF_MAKE_FAST_ALLOCATED;
60    public:
61        static void createChannel(PassRefPtr<MessagePort>, PassRefPtr<MessagePort>);
62
63        // Creates a new wrapper for the passed channel.
64        static PassOwnPtr<MessagePortChannel> create(PassRefPtr<PlatformMessagePortChannel>);
65
66        // Entangles the channel with a port (called when a port has been cloned, after the clone has been marshaled to its new owning thread and is ready to receive messages).
67        // Returns false if the entanglement failed because the port was closed.
68        bool entangleIfOpen(MessagePort*);
69
70        // Disentangles the channel from a given port so it no longer forwards messages to the port. Called when the port is being cloned and no new owning thread has yet been established.
71        void disentangle();
72
73        // Closes the port (ensures that no further messages can be added to either queue).
74        void close();
75
76        // Used by MessagePort.postMessage() to prevent callers from passing a port's own entangled port.
77        bool isConnectedTo(MessagePort*);
78
79        // Returns true if the proxy currently contains messages for this port.
80        bool hasPendingActivity();
81
82        class EventData {
83            WTF_MAKE_NONCOPYABLE(EventData); WTF_MAKE_FAST_ALLOCATED;
84        public:
85            static PassOwnPtr<EventData> create(PassRefPtr<SerializedScriptValue>, PassOwnPtr<MessagePortChannelArray>);
86
87            SerializedScriptValue* message() { return m_message.get(); }
88            PassOwnPtr<MessagePortChannelArray> channels() { return m_channels.release(); }
89
90        private:
91            EventData(PassRefPtr<SerializedScriptValue> message, PassOwnPtr<MessagePortChannelArray>);
92            RefPtr<SerializedScriptValue> m_message;
93            OwnPtr<MessagePortChannelArray> m_channels;
94        };
95
96        // Sends a message and optional cloned port to the remote port.
97        void postMessageToRemote(PassOwnPtr<EventData>);
98
99        // Extracts a message from the message queue for this port.
100        bool tryGetMessageFromRemote(OwnPtr<EventData>&);
101
102        // Returns the entangled port if run by the same thread (see MessagePort::locallyEntangledPort() for more details).
103        MessagePort* locallyEntangledPort(const ScriptExecutionContext*);
104
105        ~MessagePortChannel();
106
107        PlatformMessagePortChannel* channel() const { return m_channel.get(); }
108
109    private:
110        MessagePortChannel(PassRefPtr<PlatformMessagePortChannel>);
111        RefPtr<PlatformMessagePortChannel> m_channel;
112    };
113
114} // namespace WebCore
115
116#endif // MessagePortChannel_h
117