1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
|
/*
* Copyright (C) 2008 Apple Inc. All Rights Reserved.
* Copyright (C) 2013 Google Inc. All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE COMPUTER, INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
#ifndef LifecycleNotifier_h
#define LifecycleNotifier_h
#include "platform/heap/Handle.h"
#include "wtf/HashSet.h"
#include "wtf/TemporaryChange.h"
namespace blink {
template<typename T, typename Observer>
class LifecycleNotifier : public virtual WillBeGarbageCollectedMixin {
public:
virtual ~LifecycleNotifier();
void addObserver(Observer*);
void removeObserver(Observer*);
// notifyContextDestroyed() should be explicitly dispatched from an
// observed context to notify observers that contextDestroyed().
//
// When contextDestroyed() is called, the observer's lifecycleContext()
// is still valid and safe to use during the notification.
virtual void notifyContextDestroyed();
DEFINE_INLINE_VIRTUAL_TRACE()
{
#if ENABLE(OILPAN)
visitor->trace(m_observers);
#endif
}
bool isIteratingOverObservers() const { return m_iterating != IteratingNone; }
protected:
LifecycleNotifier()
: m_iterating(IteratingNone)
, m_didCallContextDestroyed(false)
{
}
enum IterationType {
IteratingNone,
IteratingOverAll,
};
IterationType m_iterating;
protected:
using ObserverSet = WillBeHeapHashSet<RawPtrWillBeWeakMember<Observer>>;
ObserverSet m_observers;
#if ENABLE(ASSERT)
T* context() { return static_cast<T*>(this); }
#endif
private:
bool m_didCallContextDestroyed;
};
template<typename T, typename Observer>
inline LifecycleNotifier<T, Observer>::~LifecycleNotifier()
{
// FIXME: Enable the following ASSERT. Also see a FIXME in Document::detach().
// ASSERT(!m_observers.size() || m_didCallContextDestroyed);
#if !ENABLE(OILPAN)
TemporaryChange<IterationType> scope(m_iterating, IteratingOverAll);
for (Observer* observer : m_observers) {
observer->clearLifecycleContext();
}
#endif
}
template<typename T, typename Observer>
inline void LifecycleNotifier<T, Observer>::notifyContextDestroyed()
{
// Don't notify contextDestroyed() twice.
if (m_didCallContextDestroyed)
return;
TemporaryChange<IterationType> scope(m_iterating, IteratingOverAll);
Vector<RawPtrWillBeUntracedMember<Observer>> snapshotOfObservers;
copyToVector(m_observers, snapshotOfObservers);
for (Observer* observer : snapshotOfObservers) {
// FIXME: Oilpan: At the moment, it's possible that the Observer is
// destructed during the iteration.
// Once we enable Oilpan by default for Observers *and*
// Observer::contextDestroyed() does not call removeObserver(),
// we can remove the hack by making m_observers
// a HeapHashSet<WeakMember<Observers>>. (i.e., we can just iterate
// m_observers without taking a snapshot).
if (m_observers.contains(observer)) {
ASSERT(observer->lifecycleContext() == context());
observer->contextDestroyed();
}
}
m_didCallContextDestroyed = true;
}
template<typename T, typename Observer>
inline void LifecycleNotifier<T, Observer>::addObserver(Observer* observer)
{
RELEASE_ASSERT(m_iterating != IteratingOverAll);
m_observers.add(observer);
}
template<typename T, typename Observer>
inline void LifecycleNotifier<T, Observer>::removeObserver(Observer* observer)
{
m_observers.remove(observer);
}
} // namespace blink
#endif // LifecycleNotifier_h
|
