1/*
2 * Copyright (C) 2013 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#include "config.h"
32#include "modules/device_orientation/DeviceSensorEventDispatcher.h"
33
34namespace WebCore {
35
36DeviceSensorEventDispatcher::DeviceSensorEventDispatcher()
37    : m_needsPurge(false)
38    , m_isDispatching(false)
39{
40}
41
42DeviceSensorEventDispatcher::~DeviceSensorEventDispatcher()
43{
44}
45
46void DeviceSensorEventDispatcher::addController(DeviceSensorEventController* controller)
47{
48    bool wasEmpty = m_controllers.isEmpty();
49    if (!m_controllers.contains(controller))
50        m_controllers.append(controller);
51    if (wasEmpty)
52        startListening();
53}
54
55void DeviceSensorEventDispatcher::removeController(DeviceSensorEventController* controller)
56{
57    // Do not actually remove the controller from the vector, instead zero them out.
58    // The zeros are removed in these two cases:
59    // 1. either immediately if we are not dispatching any events,
60    // 2. or after didChangeDeviceMotion/Orientation has dispatched all events.
61    // This is to correctly handle the re-entrancy case when a controller is destroyed
62    // while in the didChangeDeviceMotion/Orientation method.
63    size_t index = m_controllers.find(controller);
64    if (index == kNotFound)
65        return;
66
67    m_controllers[index] = 0;
68    m_needsPurge = true;
69
70    if (!m_isDispatching)
71        purgeControllers();
72}
73
74void DeviceSensorEventDispatcher::purgeControllers()
75{
76    ASSERT(m_needsPurge);
77
78    size_t i = 0;
79    while (i < m_controllers.size()) {
80        if (!m_controllers[i]) {
81            m_controllers[i] = m_controllers.last();
82            m_controllers.removeLast();
83        } else {
84            ++i;
85        }
86    }
87
88    m_needsPurge = false;
89
90    if (m_controllers.isEmpty())
91        stopListening();
92}
93
94} // namespace WebCore
95