kpx_cpu/include/block-alloc.hpp

/*
 *  block_alloc.hpp - Memory allocation in blocks
 *
 *  Kheperix (C) 2003 Gwenole Beauchesne
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#ifndef BLOCK_ALLOC_H
#define BLOCK_ALLOC_H

/**
 *      Slow memory allocator
 *
 *              Each time a DATA item is requested (resp. released), the block
 *              is immediately allocated (resp. free'd).
 **/

template< class data >
struct slow_allocator
{
        data * acquire() const { return new data; }
        void release(data * const x) const { delete x; }
};

/**
 *      Lazy memory allocator
 *
 *              Allocate a big memory block, typically larger than a page,
 *              that contains up to POOL_COUNT data items of type DATA.
 **/

template< class data >
class lazy_allocator
{
        static const int pool_size = 4096;
        static const int pool_count = 1 + pool_size / sizeof(data);

        struct chunk
        {
                data    value;
                chunk * next;
        };

        struct pool
        {
                chunk  chunks[pool_count];
                pool * next;
        };

        pool *  pools;
        chunk * chunks;

public:
        lazy_allocator() : pools(0), chunks(0) { }
        ~lazy_allocator();
        data * acquire();
        void release(data * const);
};

template< class data >
lazy_allocator<data>::~lazy_allocator()
{
        pool * p = pools;
        while (p) {
                pool * d = p;
                p = p->next;
                delete d;
        }
}

template< class data >
data * lazy_allocator<data>::acquire()
{
        if (!chunks) {
                // There is no chunk left, allocate a new pool and link the
                // chunks into the free list
                pool * p = new pool;
                for (chunk * c = &p->chunks[0]; c < &p->chunks[pool_count]; c++) {
                        c->next = chunks;
                        chunks = c;
                }
                p->next = pools;
                pools = p;
        }
        chunk * c = chunks;
        chunks = c->next;
        return &c->value;
}

template< class data >
void lazy_allocator<data>::release(data * const d)
{
        chunk *c = (chunk *)d;
        c->next = chunks;
        chunks = c;
}

/**
 *              Helper memory allocator
 **/

template< class data_type, template< class > class allocator_type = lazy_allocator >
class allocator_helper
{
        static allocator_type<data_type> allocator;
public:
        static inline void *allocate()
                { return allocator.acquire(); }
        static inline void deallocate(void * p)
                { allocator.release((data_type *)p); }
};

#endif /* BLOCK_ALLOC_H */
Revision:	1.2
Committed:	2006-01-28T21:59:41Z (18 years, 7 months ago) by gbeauche
Branch:	MAIN
CVS Tags:	HEAD
Changes since 1.1:	+3 -3 lines
Log Message:	fix new/delete mismatch in slow_allocator, also use that for lazy_allocator
#	User	Rev	Content
1	gbeauche	1.1	/*
2			* block_alloc.hpp - Memory allocation in blocks
3			*
4			* Kheperix (C) 2003 Gwenole Beauchesne
5			*
6			* This program is free software; you can redistribute it and/or modify
7			* it under the terms of the GNU General Public License as published by
8			* the Free Software Foundation; either version 2 of the License, or
9			* (at your option) any later version.
10			*
11			* This program is distributed in the hope that it will be useful,
12			* but WITHOUT ANY WARRANTY; without even the implied warranty of
13			* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14			* GNU General Public License for more details.
15			*
16			* You should have received a copy of the GNU General Public License
17			* along with this program; if not, write to the Free Software
18			* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19			*/
20
21			#ifndef BLOCK_ALLOC_H
22			#define BLOCK_ALLOC_H
23
24			/**
25			* Slow memory allocator
26			*
27			* Each time a DATA item is requested (resp. released), the block
28			* is immediately allocated (resp. free'd).
29			**/
30
31			template< class data >
32			struct slow_allocator
33			{
34			data * acquire() const { return new data; }
35	gbeauche	1.2	void release(data * const x) const { delete x; }
36	gbeauche	1.1	};
37
38			/**
39			* Lazy memory allocator
40			*
41			* Allocate a big memory block, typically larger than a page,
42			* that contains up to POOL_COUNT data items of type DATA.
43			**/
44
45			template< class data >
46			class lazy_allocator
47			{
48			static const int pool_size = 4096;
49			static const int pool_count = 1 + pool_size / sizeof(data);
50
51			struct chunk
52			{
53			data value;
54			chunk * next;
55			};
56
57			struct pool
58			{
59			chunk chunks[pool_count];
60			pool * next;
61			};
62
63			pool * pools;
64			chunk * chunks;
65
66			public:
67			lazy_allocator() : pools(0), chunks(0) { }
68			~lazy_allocator();
69			data * acquire();
70			void release(data * const);
71			};
72
73			template< class data >
74			lazy_allocator<data>::~lazy_allocator()
75			{
76			pool * p = pools;
77			while (p) {
78			pool * d = p;
79			p = p->next;
80	gbeauche	1.2	delete d;
81	gbeauche	1.1	}
82			}
83
84			template< class data >
85			data * lazy_allocator<data>::acquire()
86			{
87			if (!chunks) {
88			// There is no chunk left, allocate a new pool and link the
89			// chunks into the free list
90	gbeauche	1.2	pool * p = new pool;
91	gbeauche	1.1	for (chunk * c = &p->chunks[0]; c < &p->chunks[pool_count]; c++) {
92			c->next = chunks;
93			chunks = c;
94			}
95			p->next = pools;
96			pools = p;
97			}
98			chunk * c = chunks;
99			chunks = c->next;
100			return &c->value;
101			}
102
103			template< class data >
104			void lazy_allocator<data>::release(data * const d)
105			{
106			chunk c = (chunk )d;
107			c->next = chunks;
108			chunks = c;
109			}
110
111			/**
112			* Helper memory allocator
113			**/
114
115			template< class data_type, template< class > class allocator_type = lazy_allocator >
116			class allocator_helper
117			{
118			static allocator_type<data_type> allocator;
119			public:
120			static inline void *allocate()
121			{ return allocator.acquire(); }
122			static inline void deallocate(void * p)
123			{ allocator.release((data_type *)p); }
124			};
125
126			#endif /* BLOCK_ALLOC_H */