1/*
2 * Copyright (C) 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
3 *
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Library General Public
6 * License as published by the Free Software Foundation; either
7 * version 2 of the License, or (at your option) any later version.
8 *
9 * This library is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12 * Library General Public License for more details.
13 *
14 * You should have received a copy of the GNU Library General Public License
15 * along with this library; see the file COPYING.LIB.  If not, write to
16 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
17 * Boston, MA 02110-1301, USA.
18 *
19 */
20
21#ifndef RefCounted_h
22#define RefCounted_h
23
24#include "Assertions.h"
25#include "FastAllocBase.h"
26#include "Noncopyable.h"
27
28namespace WTF {
29
30// This base class holds the non-template methods and attributes.
31// The RefCounted class inherits from it reducing the template bloat
32// generated by the compiler (technique called template hoisting).
33class RefCountedBase {
34public:
35    void ref()
36    {
37        ASSERT(!m_deletionHasBegun);
38        ASSERT(!m_adoptionIsRequired);
39        ++m_refCount;
40    }
41
42    bool hasOneRef() const
43    {
44        ASSERT(!m_deletionHasBegun);
45        return m_refCount == 1;
46    }
47
48    int refCount() const
49    {
50        return m_refCount;
51    }
52
53    void relaxAdoptionRequirement()
54    {
55#ifndef NDEBUG
56        ASSERT(!m_deletionHasBegun);
57        ASSERT(m_adoptionIsRequired);
58        m_adoptionIsRequired = false;
59#endif
60    }
61
62    // Helper for generating JIT code. Please do not use for non-JIT purposes.
63    const int* addressOfCount() const
64    {
65        return &m_refCount;
66    }
67
68protected:
69    RefCountedBase()
70        : m_refCount(1)
71#ifndef NDEBUG
72        , m_deletionHasBegun(false)
73        , m_adoptionIsRequired(true)
74#endif
75    {
76    }
77
78    ~RefCountedBase()
79    {
80        ASSERT(m_deletionHasBegun);
81        ASSERT(!m_adoptionIsRequired);
82    }
83
84    // Returns whether the pointer should be freed or not.
85    bool derefBase()
86    {
87        ASSERT(!m_deletionHasBegun);
88        ASSERT(!m_adoptionIsRequired);
89
90        ASSERT(m_refCount > 0);
91        if (m_refCount == 1) {
92#ifndef NDEBUG
93            m_deletionHasBegun = true;
94#endif
95            return true;
96        }
97
98        --m_refCount;
99        return false;
100    }
101
102#ifndef NDEBUG
103    bool deletionHasBegun() const
104    {
105        return m_deletionHasBegun;
106    }
107#endif
108
109private:
110    template<typename T> friend class CrossThreadRefCounted;
111
112#ifndef NDEBUG
113    friend void adopted(RefCountedBase*);
114#endif
115
116    int m_refCount;
117#ifndef NDEBUG
118    bool m_deletionHasBegun;
119    bool m_adoptionIsRequired;
120#endif
121};
122
123#ifndef NDEBUG
124
125inline void adopted(RefCountedBase* object)
126{
127    if (!object)
128        return;
129    ASSERT(!object->m_deletionHasBegun);
130    object->m_adoptionIsRequired = false;
131}
132
133#endif
134
135template<typename T> class RefCounted : public RefCountedBase {
136    WTF_MAKE_NONCOPYABLE(RefCounted); WTF_MAKE_FAST_ALLOCATED;
137public:
138    void deref()
139    {
140        if (derefBase())
141            delete static_cast<T*>(this);
142    }
143
144protected:
145    RefCounted() { }
146    ~RefCounted()
147    {
148    }
149};
150
151template<typename T> class RefCountedCustomAllocated : public RefCountedBase {
152    WTF_MAKE_NONCOPYABLE(RefCountedCustomAllocated);
153
154public:
155    void deref()
156    {
157        if (derefBase())
158            delete static_cast<T*>(this);
159    }
160
161protected:
162    ~RefCountedCustomAllocated()
163    {
164    }
165};
166
167} // namespace WTF
168
169using WTF::RefCounted;
170using WTF::RefCountedCustomAllocated;
171
172#endif // RefCounted_h
173