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
144
145
146
147
148
149
150
151
152
153
154
155
|
/*
* Copyright (C) 2007, 2008, 2010, 2013, 2014 Apple Inc. All rights reserved.
* Copyright (C) 2007 Justin Haygood (jhaygood@reaktix.com)
*
* 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 INC. AND ITS CONTRIBUTORS ``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 INC. OR ITS 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.
*/
#pragma once
#include <wtf/ThreadSafeRefCounted.h>
namespace WTF {
// FIXME: Safer CPP Checking cannot perform analysis globally, and it does not work well
// with some of lifetime model, in particular JSC::VM which is retained before entering
// JSC world. This class is introduced to suppress these warnings since it does not use
// ref / deref functions. Except for the function names, implementation is the copy of
// ThreadSafeRefCounted. We would like to drop this class once Safer CPP Checking supports
// suppression mechanism for the classes which cannot be handled well with the checker, or
// the checker introduces a solution which works well with JSC::VM.
class ThreadSafeRefCountedWithSuppressingSaferCPPCheckingBase {
WTF_MAKE_NONCOPYABLE(ThreadSafeRefCountedWithSuppressingSaferCPPCheckingBase);
WTF_MAKE_FAST_ALLOCATED;
public:
ThreadSafeRefCountedWithSuppressingSaferCPPCheckingBase() = default;
#if CHECK_THREAD_SAFE_REF_COUNTED_LIFECYCLE
~ThreadSafeRefCountedWithSuppressingSaferCPPCheckingBase();
#endif
void refSuppressingSaferCPPChecking() const
{
applyRefDuringDestructionCheck();
++m_refCount;
}
bool hasOneRef() const
{
return refCount() == 1;
}
unsigned refCount() const
{
return m_refCount;
}
protected:
// Returns whether the pointer should be freed or not.
bool derefBaseWithoutDeletionCheck() const
{
ASSERT(m_refCount);
if (UNLIKELY(!--m_refCount)) {
// Setting m_refCount to 1 here prevents double delete within the destructor but not from another thread
// since such a thread could have ref'ed this object long after it had been deleted. See webkit.org/b/201576.
m_refCount = 1;
#if CHECK_THREAD_SAFE_REF_COUNTED_LIFECYCLE
m_deletionHasBegun = true;
#endif
return true;
}
return false;
}
// Returns whether the pointer should be freed or not.
bool derefBase() const
{
return derefBaseWithoutDeletionCheck();
}
void applyRefDuringDestructionCheck() const
{
#if CHECK_THREAD_SAFE_REF_COUNTED_LIFECYCLE
if (!m_deletionHasBegun)
return;
RefCountedBase::logRefDuringDestruction(this);
#endif
}
private:
mutable std::atomic<unsigned> m_refCount { 1 };
#if ASSERT_ENABLED
// Match the layout of RefCounted, which has flag bits for threading checks.
UNUSED_MEMBER_VARIABLE bool m_unused1;
UNUSED_MEMBER_VARIABLE bool m_unused2;
#endif
#if CHECK_THREAD_SAFE_REF_COUNTED_LIFECYCLE
mutable std::atomic<bool> m_deletionHasBegun { false };
// Match the layout of RefCounted.
UNUSED_MEMBER_VARIABLE bool m_unused3;
#endif
};
#if CHECK_THREAD_SAFE_REF_COUNTED_LIFECYCLE
inline ThreadSafeRefCountedWithSuppressingSaferCPPCheckingBase::~ThreadSafeRefCountedWithSuppressingSaferCPPCheckingBase()
{
// When this ThreadSafeRefCountedWithSuppressingSaferCPPChecking object is a part of another object, derefBase() is never called on this object.
m_deletionHasBegun = true;
// FIXME: Test performance, then add a RELEASE_ASSERT for this too.
if (m_refCount != 1)
RefCountedBase::printRefDuringDestructionLogAndCrash(this);
}
#endif
template<class T, DestructionThread destructionThread = DestructionThread::Any> class ThreadSafeRefCountedWithSuppressingSaferCPPChecking : public ThreadSafeRefCountedWithSuppressingSaferCPPCheckingBase {
public:
void derefSuppressingSaferCPPChecking() const
{
if (!derefBase())
return;
if constexpr (destructionThread == DestructionThread::Any) {
delete static_cast<const T*>(this);
} else if constexpr (destructionThread == DestructionThread::Main) {
ensureOnMainThread([this] {
delete static_cast<const T*>(this);
});
} else if constexpr (destructionThread == DestructionThread::MainRunLoop) {
ensureOnMainRunLoop([this] {
delete static_cast<const T*>(this);
});
} else
STATIC_ASSERT_NOT_REACHED_FOR_VALUE(destructionThread, "Unexpected destructionThread enumerator value");
}
protected:
ThreadSafeRefCountedWithSuppressingSaferCPPChecking() = default;
};
} // namespace WTF
using WTF::ThreadSafeRefCountedWithSuppressingSaferCPPChecking;
|
