1/*
2 * Copyright (C) 2012, 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
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
15 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
16 * DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY
17 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
18 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
19 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
20 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
22 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
23 */
24
25#pragma once
26
27#include "AudioBus.h"
28#include <wtf/HashSet.h>
29#include <wtf/Vector.h>
30
31namespace WebCore {
32
33class AudioContext;
34class AudioNodeOutput;
35
36// An AudioSummingJunction represents a point where zero, one, or more AudioNodeOutputs connect.
37
38class AudioSummingJunction {
39public:
40 explicit AudioSummingJunction(AudioContext&);
41 virtual ~AudioSummingJunction();
42
43 // Can be called from any thread.
44 AudioContext& context() { return m_context.get(); }
45
46 // This must be called whenever we modify m_outputs.
47 void changedOutputs();
48
49 // This copies m_outputs to m_renderingOutputs. Please see comments for these lists below.
50 // This must be called when we own the context's graph lock in the audio thread at the very start or end of the render quantum.
51 void updateRenderingState();
52
53 // Rendering code accesses its version of the current connections here.
54 unsigned numberOfRenderingConnections() const { return m_renderingOutputs.size(); }
55 AudioNodeOutput* renderingOutput(unsigned i) { return m_renderingOutputs[i]; }
56 const AudioNodeOutput* renderingOutput(unsigned i) const { return m_renderingOutputs[i]; }
57 bool isConnected() const { return numberOfRenderingConnections() > 0; }
58
59 virtual bool canUpdateState() = 0;
60 virtual void didUpdate() = 0;
61
62protected:
63 Ref<AudioContext> m_context;
64
65 // m_outputs contains the AudioNodeOutputs representing current connections which are not disabled.
66 // The rendering code should never use this directly, but instead uses m_renderingOutputs.
67 HashSet<AudioNodeOutput*> m_outputs;
68
69 // numberOfConnections() should never be called from the audio rendering thread.
70 // Instead numberOfRenderingConnections() and renderingOutput() should be used.
71 unsigned numberOfConnections() const { return m_outputs.size(); }
72
73 // m_renderingOutputs is a copy of m_outputs which will never be modified during the graph rendering on the audio thread.
74 // This is the list which is used by the rendering code.
75 // Whenever m_outputs is modified, the context is told so it can later update m_renderingOutputs from m_outputs at a safe time.
76 // Most of the time, m_renderingOutputs is identical to m_outputs.
77 Vector<AudioNodeOutput*> m_renderingOutputs;
78
79 // m_renderingStateNeedUpdating keeps track if m_outputs is modified.
80 bool m_renderingStateNeedUpdating;
81};
82
83} // namespace WebCore
84