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/* $NetBSD: mpool.h,v 1.13 2008/08/26 21:18:38 joerg Exp $ */

/*-
* Copyright (c) 1991, 1993, 1994
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)mpool.h 8.2 (Berkeley) 7/14/94
*/

#ifndef _MPOOL_H_
#define _MPOOL_H_

#include <sys/cdefs.h>
#include <sys/queue.h>

/*
* The memory pool scheme is a simple one. Each in-memory page is referenced
* by a bucket which is threaded in up to two of three ways. All active pages
* are threaded on a hash chain (hashed by page number) and an lru chain.
* Inactive pages are threaded on a free chain. Each reference to a memory
* pool is handed an opaque MPOOL cookie which stores all of this information.
*/
#define HASHSIZE 128
#define HASHKEY(pgno) ((pgno - 1) % HASHSIZE)

/* The BKT structures are the elements of the queues. */
typedef struct _bkt {
CIRCLEQ_ENTRY(_bkt) hq; /* hash queue */
CIRCLEQ_ENTRY(_bkt) q; /* lru queue */
void *page; /* page */
pgno_t pgno; /* page number */

#define MPOOL_DIRTY 0x01 /* page needs to be written */
#define MPOOL_PINNED 0x02 /* page is pinned into memory */
uint8_t flags; /* flags */
} BKT;

typedef struct MPOOL {
CIRCLEQ_HEAD(_lqh, _bkt) lqh; /* lru queue head */
/* hash queue array */
CIRCLEQ_HEAD(_hqh, _bkt) hqh[HASHSIZE];
pgno_t curcache; /* current number of cached pages */
pgno_t maxcache; /* max number of cached pages */
pgno_t npages; /* number of pages in the file */
unsigned long pagesize; /* file page size */
int fd; /* file descriptor */
/* page in conversion routine */
void (*pgin)(void *, pgno_t, void *);
/* page out conversion routine */
void (*pgout)(void *, pgno_t, void *);
void *pgcookie; /* cookie for page in/out routines */
#ifdef STATISTICS
unsigned long cachehit;
unsigned long cachemiss;
unsigned long pagealloc;
unsigned long pageflush;
unsigned long pageget;
unsigned long pagenew;
unsigned long pageput;
unsigned long pageread;
unsigned long pagewrite;
#endif
} MPOOL;

__BEGIN_DECLS
MPOOL *mpool_open(void *, int, pgno_t, pgno_t);
void mpool_filter(MPOOL *, void (*)(void *, pgno_t, void *),
void (*)(void *, pgno_t, void *), void *);
void *mpool_new(MPOOL *, pgno_t *);
void *mpool_get(MPOOL *, pgno_t, unsigned int);
int mpool_put(MPOOL *, void *, unsigned int);
int mpool_sync(MPOOL *);
int mpool_close(MPOOL *);
#ifdef STATISTICS
void mpool_stat(MPOOL *);
#endif
__END_DECLS

#endif /* _MPOOL_H_ */
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