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 "SerializedScriptValue.h"
35#include <memory>
36#include <wtf/Forward.h>
37#include <wtf/PassRefPtr.h>
38#include <wtf/RefCounted.h>
39#include <wtf/RefPtr.h>
40#include <wtf/text/WTFString.h>
41
42namespace WebCore {
43
44    class MessagePort;
45    class MessagePortChannel;
46    class PlatformMessagePortChannel;
47    class ScriptExecutionContext;
48    class SerializedScriptValue;
49
50    // The overwhelmingly common case is sending a single port, so handle that efficiently with an inline buffer of size 1.
51    typedef Vector<std::unique_ptr<MessagePortChannel>, 1> MessagePortChannelArray;
52
53    // MessagePortChannel is a platform-independent interface to the remote side of a message channel.
54    // It acts as a wrapper around the platform-dependent PlatformMessagePortChannel implementation which ensures that the platform-dependent close() method is invoked before destruction.
55    class MessagePortChannel {
56        WTF_MAKE_NONCOPYABLE(MessagePortChannel); WTF_MAKE_FAST_ALLOCATED;
57    public:
58        explicit MessagePortChannel(PassRefPtr<PlatformMessagePortChannel>);
59        static void createChannel(PassRefPtr<MessagePort>, PassRefPtr<MessagePort>);
60
61        // 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).
62        // Returns false if the entanglement failed because the port was closed.
63        bool entangleIfOpen(MessagePort*);
64
65        // 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.
66        void disentangle();
67
68        // Closes the port (ensures that no further messages can be added to either queue).
69        void close();
70
71        // Used by MessagePort.postMessage() to prevent callers from passing a port's own entangled port.
72        bool isConnectedTo(MessagePort*);
73
74        // Returns true if the proxy currently contains messages for this port.
75        bool hasPendingActivity();
76
77        // Sends a message and optional cloned port to the remote port.
78        void postMessageToRemote(PassRefPtr<SerializedScriptValue>, std::unique_ptr<MessagePortChannelArray>);
79
80        // Extracts a message from the message queue for this port.
81        bool tryGetMessageFromRemote(RefPtr<SerializedScriptValue>&, std::unique_ptr<MessagePortChannelArray>&);
82
83        // Returns the entangled port if run by the same thread (see MessagePort::locallyEntangledPort() for more details).
84        MessagePort* locallyEntangledPort(const ScriptExecutionContext*);
85
86        ~MessagePortChannel();
87
88    private:
89        RefPtr<PlatformMessagePortChannel> m_channel;
90    };
91
92} // namespace WebCore
93
94#endif // MessagePortChannel_h
95