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
|
/*
* Copyright (C) 2007, 2008, 2010 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.
* 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of
* its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY APPLE 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 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.
*/
#ifndef ThreadSafeRefCounted_h
#define ThreadSafeRefCounted_h
#include "wtf/Atomics.h"
#include "wtf/DynamicAnnotations.h"
#include "wtf/FastAllocBase.h"
#include "wtf/Noncopyable.h"
#include "wtf/WTFExport.h"
namespace WTF {
class WTF_EXPORT ThreadSafeRefCountedBase {
WTF_MAKE_NONCOPYABLE(ThreadSafeRefCountedBase);
WTF_MAKE_FAST_ALLOCATED;
public:
ThreadSafeRefCountedBase(int initialRefCount = 1)
: m_refCount(initialRefCount)
{
}
void ref()
{
atomicIncrement(&m_refCount);
}
bool hasOneRef()
{
return refCount() == 1;
}
int refCount() const
{
return static_cast<int const volatile &>(m_refCount);
}
protected:
// Returns whether the pointer should be freed or not.
bool derefBase()
{
WTF_ANNOTATE_HAPPENS_BEFORE(&m_refCount);
if (atomicDecrement(&m_refCount) <= 0) {
WTF_ANNOTATE_HAPPENS_AFTER(&m_refCount);
return true;
}
return false;
}
private:
int m_refCount;
};
template<class T> class ThreadSafeRefCounted : public ThreadSafeRefCountedBase {
public:
void deref()
{
if (derefBase())
delete static_cast<T*>(this);
}
protected:
ThreadSafeRefCounted()
{
}
};
} // namespace WTF
using WTF::ThreadSafeRefCounted;
#endif // ThreadSafeRefCounted_h
|
