summaryrefslogtreecommitdiffstats
path: root/tools/porting/src/smallobject.h
blob: 8b9f91fac7206613a0c0d10a6aaf15b413ad90b9 (plain)
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
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
/****************************************************************************
**
** Copyright (C) 2001-2004 Roberto Raggi
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the qt3to4 porting application of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** No Commercial Usage
** This file contains pre-release code and may not be distributed.
** You may use this file in accordance with the terms and conditions
** contained in the Technology Preview License Agreement accompanying
** this package.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain
** additional rights.  These rights are described in the Nokia Qt LGPL
** Exception version 1.1, included in the file LGPL_EXCEPTION.txt in this
** package.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
**
**
**
**
**
**
**
**
** $QT_END_LICENSE$
**
****************************************************************************/

#ifndef SMALLOBJECT_H
#define SMALLOBJECT_H

#include <QList>

#include <assert.h>
#include <stdlib.h>
#include <string.h>

QT_BEGIN_NAMESPACE

struct block_t
{
    static int N;

    block_t *chain;
    char *data;
    char *ptr;
    char *end;

    inline void init(int block_size = 256)
    {
        ++N;
        chain = 0;
        data = (char*) malloc(block_size);
        ptr = data;
        end = data + block_size;
    }

    inline void init0(int block_size)
    {
        init();
        memset(data, '0', block_size);
    }

    inline void destroy()
    {
        --N;
        if (chain) {
            chain->destroy();
            free(chain);
        }

        free(data);
    }

    inline void *allocate(size_t size, block_t **right_most)
    {
        const unsigned int block_size = 1 << 16;
        if (end < ptr + size) {
            assert( size < block_size );

            if (!chain) {
                chain = (block_t*) malloc(sizeof(block_t));
                Q_ASSERT(chain);
                chain->init(block_size);
            }

            return chain->allocate(size, right_most);
        }

        char *r = ptr;
        ptr += size;

        if (right_most)
            *right_most = this;

        return r;
    }

};

// a stupid memory pool
struct pool
{
    block_t blk;
    block_t *right_most;

    inline pool() { blk.init(); right_most = &blk; }
    inline ~pool() { blk.destroy(); }

    inline void *allocate(size_t size)
    {
        void *ptr = right_most->allocate(size, &right_most);
        Q_ASSERT(ptr);
        return ptr;

    }
    inline void *reallocate(void *old, size_t old_size, size_t size)
    {
        void *alloc = right_most->allocate(size, &right_most);
        memcpy(alloc, old, old_size);
        return alloc;
    }
private:
   Q_DISABLE_COPY(pool)
};

/*
    A memory pool that calls the destructor for each stored item when memory is
    freed, at the expence storing one BaseType* per item.

    Note that allocations for types that does not inherit BaseType
    is not allowed and will result in a crash when the memory is freed.
*/
template <typename BaseType>
class TypedPool
{
public:
    inline TypedPool() { blk.init(); right_most = &blk; }
    inline ~TypedPool()
    {
        foreach(BaseType *item, allocated)
            item->~BaseType();
        blk.destroy();
    }

    inline void *allocate(size_t size)
    {
        void *memory = right_most->allocate(size, &right_most);
        allocated.append(reinterpret_cast<BaseType *>(memory));
        Q_ASSERT(memory);
        return memory;
    }
private:
    Q_DISABLE_COPY(TypedPool)
    block_t blk;
    block_t *right_most;
    QList<BaseType *> allocated;
};

struct SmallObject
{
    static void *operator new(size_t size);
    static void operator delete(void *p);
};

QT_END_NAMESPACE

#endif