mpool.h revision 25520 
1/*-
2 * Copyright (c) 1991, 1993, 1994
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by the University of
16 *	California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 *	@(#)mpool.h	8.2 (Berkeley) 7/14/94
34 */
35
36#ifndef _MPOOL_H_
37#define _MPOOL_H_
38
39#include <sys/types.h>
40#include <sys/queue.h>
41#include <db.h>
42
43/*
44 * The memory pool scheme is a simple one.  Each in-memory page is referenced
45 * by a bucket which is threaded in up to two of three ways.  All active pages
46 * are threaded on a hash chain (hashed by page number) and an lru chain.
47 * Inactive pages are threaded on a free chain.  Each reference to a memory
48 * pool is handed an opaque MPOOL cookie which stores all of this information.
49 */
50#define	HASHSIZE	128
51#define	HASHKEY(pgno)	((pgno - 1) % HASHSIZE)
52
53/* The BKT structures are the elements of the queues. */
54typedef struct _bkt {
55	CIRCLEQ_ENTRY(_bkt) hq;		/* hash queue */
56	CIRCLEQ_ENTRY(_bkt) q;		/* lru queue */
57	void    *page;			/* page */
58	pgno_t   pgno;			/* page number */
59
60#define	MPOOL_DIRTY	0x01		/* page needs to be written */
61#define	MPOOL_PINNED	0x02		/* page is pinned into memory */
62	u_int8_t flags;			/* flags */
63} BKT;
64
65typedef struct MPOOL {
66	CIRCLEQ_HEAD(_lqh, _bkt) lqh;	/* lru queue head */
67					/* hash queue array */
68	CIRCLEQ_HEAD(_hqh, _bkt) hqh[HASHSIZE];
69	pgno_t	curcache;		/* current number of cached pages */
70	pgno_t	maxcache;		/* max number of cached pages */
71	pgno_t	npages;			/* number of pages in the file */
72	u_long	pagesize;		/* file page size */
73	int	fd;			/* file descriptor */
74					/* page in conversion routine */
75	void    (*pgin) __P((void *, pgno_t, void *));
76					/* page out conversion routine */
77	void    (*pgout) __P((void *, pgno_t, void *));
78	void	*pgcookie;		/* cookie for page in/out routines */
79#ifdef STATISTICS
80	u_long	cachehit;
81	u_long	cachemiss;
82	u_long	pagealloc;
83	u_long	pageflush;
84	u_long	pageget;
85	u_long	pagenew;
86	u_long	pageput;
87	u_long	pageread;
88	u_long	pagewrite;
89#endif
90} MPOOL;
91
92__BEGIN_DECLS
93MPOOL	*mpool_open __P((void *, int, pgno_t, pgno_t));
94void	 mpool_filter __P((MPOOL *, void (*)(void *, pgno_t, void *),
95	    void (*)(void *, pgno_t, void *), void *));
96void	*mpool_new __P((MPOOL *, pgno_t *));
97void	*mpool_get __P((MPOOL *, pgno_t, u_int));
98int	 mpool_put __P((MPOOL *, void *, u_int));
99int	 mpool_sync __P((MPOOL *));
100int	 mpool_close __P((MPOOL *));
101#ifdef STATISTICS
102void	 mpool_stat __P((MPOOL *));
103#endif
104__END_DECLS
105
106#endif
107