1/*
2 * Copyright (C) 2007, 2008, 2010, 2013, 2014 Apple Inc. All rights reserved.
3 * Copyright (C) 2007 Justin Haygood (jhaygood@reaktix.com)
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY
15 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
16 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
17 * DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY
18 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
19 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
20 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
21 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
23 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#ifndef ThreadSafeRefCounted_h
27#define ThreadSafeRefCounted_h
28
29#include <atomic>
30#include <wtf/FastMalloc.h>
31#include <wtf/Noncopyable.h>
32
33namespace WTF {
34
35class ThreadSafeRefCountedBase {
36 WTF_MAKE_NONCOPYABLE(ThreadSafeRefCountedBase);
37 WTF_MAKE_FAST_ALLOCATED;
38public:
39 ThreadSafeRefCountedBase(int initialRefCount = 1)
40 : m_refCount(initialRefCount)
41 {
42 }
43
44 void ref()
45 {
46 ++m_refCount;
47 }
48
49 bool hasOneRef()
50 {
51 return refCount() == 1;
52 }
53
54 int refCount() const
55 {
56 return m_refCount;
57 }
58
59protected:
60 // Returns whether the pointer should be freed or not.
61 bool derefBase()
62 {
63 if (--m_refCount <= 0) {
64 return true;
65 }
66
67 return false;
68 }
69
70private:
71 std::atomic<int> m_refCount;
72};
73
74template<class T> class ThreadSafeRefCounted : public ThreadSafeRefCountedBase {
75public:
76 void deref()
77 {
78 if (derefBase())
79 delete static_cast<T*>(this);
80 }
81
82protected:
83 ThreadSafeRefCounted()
84 {
85 }
86};
87
88} // namespace WTF
89
90using WTF::ThreadSafeRefCounted;
91
92#endif // ThreadSafeRefCounted_h
93