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) 2012 Apple 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 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.
*/
#ifndef WeakBlock_h
#define WeakBlock_h
#include "WeakImpl.h"
#include <wtf/DoublyLinkedList.h>
#include <wtf/StdLibExtras.h>
namespace JSC {
class Heap;
class HeapRootVisitor;
class MarkedBlock;
class WeakBlock : public DoublyLinkedListNode<WeakBlock> {
public:
friend class WTF::DoublyLinkedListNode<WeakBlock>;
static const size_t blockSize = 1 * KB; // 1/16 of MarkedBlock size
struct FreeCell {
FreeCell* next;
};
struct SweepResult {
bool isNull() const;
bool blockIsFree { true };
bool blockIsLogicallyEmpty { true };
FreeCell* freeList { nullptr };
};
static WeakBlock* create(Heap&, MarkedBlock&);
static void destroy(Heap&, WeakBlock*);
static WeakImpl* asWeakImpl(FreeCell*);
bool isEmpty();
bool isLogicallyEmptyButNotFree() const;
void sweep();
SweepResult takeSweepResult();
void visit(HeapRootVisitor&);
void reap();
void lastChanceToFinalize();
void disconnectMarkedBlock() { m_markedBlock = nullptr; }
private:
static FreeCell* asFreeCell(WeakImpl*);
explicit WeakBlock(MarkedBlock&);
void finalize(WeakImpl*);
WeakImpl* weakImpls();
size_t weakImplCount();
void addToFreeList(FreeCell**, WeakImpl*);
MarkedBlock* m_markedBlock;
WeakBlock* m_prev;
WeakBlock* m_next;
SweepResult m_sweepResult;
};
inline bool WeakBlock::SweepResult::isNull() const
{
return blockIsFree && !freeList; // This state is impossible, so we can use it to mean null.
}
inline WeakImpl* WeakBlock::asWeakImpl(FreeCell* freeCell)
{
return reinterpret_cast_ptr<WeakImpl*>(freeCell);
}
inline WeakBlock::SweepResult WeakBlock::takeSweepResult()
{
SweepResult tmp;
std::swap(tmp, m_sweepResult);
ASSERT(m_sweepResult.isNull());
return tmp;
}
inline WeakBlock::FreeCell* WeakBlock::asFreeCell(WeakImpl* weakImpl)
{
return reinterpret_cast_ptr<FreeCell*>(weakImpl);
}
inline WeakImpl* WeakBlock::weakImpls()
{
return reinterpret_cast_ptr<WeakImpl*>(this) + ((sizeof(WeakBlock) + sizeof(WeakImpl) - 1) / sizeof(WeakImpl));
}
inline size_t WeakBlock::weakImplCount()
{
return (blockSize / sizeof(WeakImpl)) - ((sizeof(WeakBlock) + sizeof(WeakImpl) - 1) / sizeof(WeakImpl));
}
inline void WeakBlock::addToFreeList(FreeCell** freeList, WeakImpl* weakImpl)
{
ASSERT(weakImpl->state() == WeakImpl::Deallocated);
FreeCell* freeCell = asFreeCell(weakImpl);
ASSERT(!*freeList || ((char*)*freeList > (char*)this && (char*)*freeList < (char*)this + blockSize));
ASSERT((char*)freeCell > (char*)this && (char*)freeCell < (char*)this + blockSize);
freeCell->next = *freeList;
*freeList = freeCell;
}
inline bool WeakBlock::isEmpty()
{
return !m_sweepResult.isNull() && m_sweepResult.blockIsFree;
}
inline bool WeakBlock::isLogicallyEmptyButNotFree() const
{
return !m_sweepResult.isNull() && !m_sweepResult.blockIsFree && m_sweepResult.blockIsLogicallyEmpty;
}
} // namespace JSC
#endif // WeakBlock_h
|
