1// Copyright (C) 2021 The Qt Company Ltd.
2// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
3
4#ifndef QQMLJSMEMORYPOOL_P_H
5#define QQMLJSMEMORYPOOL_P_H
6
7//
8// W A R N I N G
9// -------------
10//
11// This file is not part of the Qt API. It exists purely as an
12// implementation detail. This header file may change from version to
13// version without notice, or even be removed.
14//
15// We mean it.
16//
17
18#include <QtCore/private/qglobal_p.h>
19#include <QtCore/qstring.h>
20#include <QtCore/qvector.h>
21
22#include <cstdlib>
23
24QT_BEGIN_NAMESPACE
25
26namespace QQmlJS {
27
28class Managed;
29
30class MemoryPool
31{
32 Q_DISABLE_COPY_MOVE(MemoryPool);
33
34public:
35 MemoryPool() = default;
36 ~MemoryPool()
37 {
38 if (_blocks) {
39 for (int i = 0; i < _allocatedBlocks; ++i) {
40 if (char *b = _blocks[i])
41 free(ptr: b);
42 }
43
44 free(ptr: _blocks);
45 }
46 }
47
48 inline void *allocate(size_t size)
49 {
50 size = (size + 7) & ~size_t(7);
51 if (Q_LIKELY(_ptr && size < size_t(_end - _ptr))) {
52 void *addr = _ptr;
53 _ptr += size;
54 return addr;
55 }
56 return allocate_helper(size);
57 }
58
59 void reset()
60 {
61 _blockCount = -1;
62 _ptr = _end = nullptr;
63 }
64
65 template <typename Tp> Tp *New() { return new (this->allocate(size: sizeof(Tp))) Tp(); }
66 template <typename Tp, typename... Ta> Tp *New(Ta... args)
67 { return new (this->allocate(size: sizeof(Tp))) Tp(args...); }
68
69 QStringView newString(QString string) {
70 return strings.emplace_back(args: std::move(string));
71 }
72
73private:
74 Q_NEVER_INLINE void *allocate_helper(size_t size)
75 {
76 size_t currentBlockSize = DEFAULT_BLOCK_SIZE;
77 while (Q_UNLIKELY(size >= currentBlockSize))
78 currentBlockSize *= 2;
79
80 if (++_blockCount == _allocatedBlocks) {
81 if (! _allocatedBlocks)
82 _allocatedBlocks = DEFAULT_BLOCK_COUNT;
83 else
84 _allocatedBlocks *= 2;
85
86 _blocks = reinterpret_cast<char **>(realloc(ptr: _blocks, size: sizeof(char *) * size_t(_allocatedBlocks)));
87 Q_CHECK_PTR(_blocks);
88
89 for (int index = _blockCount; index < _allocatedBlocks; ++index)
90 _blocks[index] = nullptr;
91 }
92
93 char *&block = _blocks[_blockCount];
94
95 if (! block) {
96 block = reinterpret_cast<char *>(malloc(size: currentBlockSize));
97 Q_CHECK_PTR(block);
98 }
99
100 _ptr = block;
101 _end = _ptr + currentBlockSize;
102
103 void *addr = _ptr;
104 _ptr += size;
105 return addr;
106 }
107
108private:
109 char **_blocks = nullptr;
110 int _allocatedBlocks = 0;
111 int _blockCount = -1;
112 char *_ptr = nullptr;
113 char *_end = nullptr;
114 QStringList strings;
115
116 enum
117 {
118 DEFAULT_BLOCK_SIZE = 8 * 1024,
119 DEFAULT_BLOCK_COUNT = 8
120 };
121};
122
123class Managed
124{
125 Q_DISABLE_COPY(Managed)
126public:
127 Managed() = default;
128 ~Managed() = default;
129
130 void *operator new(size_t size, MemoryPool *pool) { return pool->allocate(size); }
131 void operator delete(void *) {}
132 void operator delete(void *, MemoryPool *) {}
133};
134
135} // namespace QQmlJS
136
137QT_END_NAMESPACE
138
139#endif
140

source code of qtdeclarative/src/qml/common/qqmljsmemorypool_p.h