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1 /* | 1 /* |
2 * Copyright (C) 2012 Google Inc. All rights reserved. | 2 * Copyright (C) 2012 Google Inc. All rights reserved. |
3 * | 3 * |
4 * Redistribution and use in source and binary forms, with or without | 4 * Redistribution and use in source and binary forms, with or without |
5 * modification, are permitted provided that the following conditions | 5 * modification, are permitted provided that the following conditions |
6 * are met: | 6 * are met: |
7 * | 7 * |
8 * 1. Redistributions of source code must retain the above copyright | 8 * 1. Redistributions of source code must retain the above copyright |
9 * notice, this list of conditions and the following disclaimer. | 9 * notice, this list of conditions and the following disclaimer. |
10 * 2. Redistributions in binary form must reproduce the above copyright | 10 * 2. Redistributions in binary form must reproduce the above copyright |
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54 void MediaStreamSource::setReadyState(ReadyState readyState) { | 54 void MediaStreamSource::setReadyState(ReadyState readyState) { |
55 if (m_readyState != ReadyStateEnded && m_readyState != readyState) { | 55 if (m_readyState != ReadyStateEnded && m_readyState != readyState) { |
56 m_readyState = readyState; | 56 m_readyState = readyState; |
57 | 57 |
58 // Observers may dispatch events which create and add new Observers; | 58 // Observers may dispatch events which create and add new Observers; |
59 // take a snapshot so as to safely iterate. | 59 // take a snapshot so as to safely iterate. |
60 HeapVector<Member<Observer>> observers; | 60 HeapVector<Member<Observer>> observers; |
61 copyToVector(m_observers, observers); | 61 copyToVector(m_observers, observers); |
62 for (auto observer : observers) | 62 for (auto observer : observers) |
63 observer->sourceChangedState(); | 63 observer->sourceChangedState(); |
| 64 |
| 65 // setReadyState() will be invoked via the MediaStreamComponent::dispose() |
| 66 // prefinalizer, allocating |observers|. Which means that |observers| will |
| 67 // live until the next GC (but be unreferenced by other heap objects), |
| 68 // _but_ it will potentially contain references to Observers that were |
| 69 // GCed after the MediaStreamComponent prefinalizer had completed. |
| 70 // |
| 71 // So, if the next GC is a conservative one _and_ it happens to find |
| 72 // a reference to |observers| when scanning the stack, we're in trouble |
| 73 // as it contains references to now-dead objects. |
| 74 // |
| 75 // Work around this by explicitly clearing the vector backing store. |
| 76 // |
| 77 // TODO(sof): consider adding run-time checks that disallows this kind |
| 78 // of dead object revivification by default. |
| 79 for (size_t i = 0; i < observers.size(); ++i) |
| 80 observers[i] = nullptr; |
64 } | 81 } |
65 } | 82 } |
66 | 83 |
67 void MediaStreamSource::addObserver(MediaStreamSource::Observer* observer) { | 84 void MediaStreamSource::addObserver(MediaStreamSource::Observer* observer) { |
68 m_observers.insert(observer); | 85 m_observers.insert(observer); |
69 } | 86 } |
70 | 87 |
71 void MediaStreamSource::addAudioConsumer(AudioDestinationConsumer* consumer) { | 88 void MediaStreamSource::addAudioConsumer(AudioDestinationConsumer* consumer) { |
72 ASSERT(m_requiresConsumer); | 89 ASSERT(m_requiresConsumer); |
73 MutexLocker locker(m_audioConsumersLock); | 90 MutexLocker locker(m_audioConsumersLock); |
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102 MutexLocker locker(m_audioConsumersLock); | 119 MutexLocker locker(m_audioConsumersLock); |
103 for (AudioDestinationConsumer* consumer : m_audioConsumers) | 120 for (AudioDestinationConsumer* consumer : m_audioConsumers) |
104 consumer->consumeAudio(bus, numberOfFrames); | 121 consumer->consumeAudio(bus, numberOfFrames); |
105 } | 122 } |
106 | 123 |
107 DEFINE_TRACE(MediaStreamSource) { | 124 DEFINE_TRACE(MediaStreamSource) { |
108 visitor->trace(m_observers); | 125 visitor->trace(m_observers); |
109 } | 126 } |
110 | 127 |
111 } // namespace blink | 128 } // namespace blink |
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