1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1991, 1993, 1994
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 *    may be used to endorse or promote products derived from this software
17 *    without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32#ifndef _MPOOL_H_
33#define _MPOOL_H_
34
35#include <sys/queue.h>
36
37/*
38 * The memory pool scheme is a simple one.  Each in-memory page is referenced
39 * by a bucket which is threaded in up to two of three ways.  All active pages
40 * are threaded on a hash chain (hashed by page number) and an lru chain.
41 * Inactive pages are threaded on a free chain.  Each reference to a memory
42 * pool is handed an opaque MPOOL cookie which stores all of this information.
43 */
44#define	HASHSIZE	128
45#define	HASHKEY(pgno)	((pgno - 1 + HASHSIZE) % HASHSIZE)
46
47/* The BKT structures are the elements of the queues. */
48typedef struct _bkt {
49	TAILQ_ENTRY(_bkt) hq;		/* hash queue */
50	TAILQ_ENTRY(_bkt) q;		/* lru queue */
51	void    *page;			/* page */
52	pgno_t   pgno;			/* page number */
53
54#define	MPOOL_DIRTY	0x01		/* page needs to be written */
55#define	MPOOL_PINNED	0x02		/* page is pinned into memory */
56#define	MPOOL_INUSE	0x04		/* page address is valid */
57	u_int8_t flags;			/* flags */
58} BKT;
59
60typedef struct MPOOL {
61	TAILQ_HEAD(_lqh, _bkt) lqh;	/* lru queue head */
62					/* hash queue array */
63	TAILQ_HEAD(_hqh, _bkt) hqh[HASHSIZE];
64	pgno_t	curcache;		/* current number of cached pages */
65	pgno_t	maxcache;		/* max number of cached pages */
66	pgno_t	npages;			/* number of pages in the file */
67	unsigned long	pagesize;	/* file page size */
68	int	fd;			/* file descriptor */
69					/* page in conversion routine */
70	void    (*pgin)(void *, pgno_t, void *);
71					/* page out conversion routine */
72	void    (*pgout)(void *, pgno_t, void *);
73	void	*pgcookie;		/* cookie for page in/out routines */
74#ifdef STATISTICS
75	unsigned long	cachehit;
76	unsigned long	cachemiss;
77	unsigned long	pagealloc;
78	unsigned long	pageflush;
79	unsigned long	pageget;
80	unsigned long	pagenew;
81	unsigned long	pageput;
82	unsigned long	pageread;
83	unsigned long	pagewrite;
84#endif
85} MPOOL;
86
87#define	MPOOL_IGNOREPIN	0x01		/* Ignore if the page is pinned. */
88#define	MPOOL_PAGE_REQUEST	0x01	/* Allocate a new page with a
89					   specific page number. */
90#define	MPOOL_PAGE_NEXT		0x02	/* Allocate a new page with the next
91					  page number. */
92
93__BEGIN_DECLS
94MPOOL	*mpool_open(void *, int, pgno_t, pgno_t);
95void	 mpool_filter(MPOOL *, void (*)(void *, pgno_t, void *),
96	    void (*)(void *, pgno_t, void *), void *);
97void	*mpool_new(MPOOL *, pgno_t *, unsigned int);
98void	*mpool_get(MPOOL *, pgno_t, unsigned int);
99int	 mpool_delete(MPOOL *, void *);
100int	 mpool_put(MPOOL *, void *, unsigned int);
101int	 mpool_sync(MPOOL *);
102int	 mpool_close(MPOOL *);
103#ifdef STATISTICS
104void	 mpool_stat(MPOOL *);
105#endif
106__END_DECLS
107
108#endif
109