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mpool.h revision 1.1.1.2 
      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 #include <sys/queue.h>
     37 
     38 /*
     39  * The memory pool scheme is a simple one.  Each in-memory page is referenced
     40  * by a bucket which is threaded in up to two of three ways.  All active pages
     41  * are threaded on a hash chain (hashed by page number) and an lru chain.
     42  * Inactive pages are threaded on a free chain.  Each reference to a memory
     43  * pool is handed an opaque MPOOL cookie which stores all of this information.
     44  */
     45 #define	HASHSIZE	128
     46 #define	HASHKEY(pgno)	((pgno - 1) % HASHSIZE)
     47 
     48 /* The BKT structures are the elements of the queues. */
     49 typedef struct _bkt {
     50 	CIRCLEQ_ENTRY(_bkt) hq;		/* hash queue */
     51 	CIRCLEQ_ENTRY(_bkt) q;		/* lru queue */
     52 	void    *page;			/* page */
     53 	pgno_t   pgno;			/* page number */
     54 
     55 #define	MPOOL_DIRTY	0x01		/* page needs to be written */
     56 #define	MPOOL_PINNED	0x02		/* page is pinned into memory */
     57 	u_int8_t flags;			/* flags */
     58 } BKT;
     59 
     60 typedef struct MPOOL {
     61 	CIRCLEQ_HEAD(_lqh, _bkt) lqh;	/* lru queue head */
     62 					/* hash queue array */
     63 	CIRCLEQ_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 	u_long	pagesize;		/* file page size */
     68 	int	fd;			/* file descriptor */
     69 					/* page in conversion routine */
     70 	void    (*pgin) __P((void *, pgno_t, void *));
     71 					/* page out conversion routine */
     72 	void    (*pgout) __P((void *, pgno_t, void *));
     73 	void	*pgcookie;		/* cookie for page in/out routines */
     74 #ifdef STATISTICS
     75 	u_long	cachehit;
     76 	u_long	cachemiss;
     77 	u_long	pagealloc;
     78 	u_long	pageflush;
     79 	u_long	pageget;
     80 	u_long	pagenew;
     81 	u_long	pageput;
     82 	u_long	pageread;
     83 	u_long	pagewrite;
     84 #endif
     85 } MPOOL;
     86 
     87 __BEGIN_DECLS
     88 MPOOL	*mpool_open __P((void *, int, pgno_t, pgno_t));
     89 void	 mpool_filter __P((MPOOL *, void (*)(void *, pgno_t, void *),
     90 	    void (*)(void *, pgno_t, void *), void *));
     91 void	*mpool_new __P((MPOOL *, pgno_t *));
     92 void	*mpool_get __P((MPOOL *, pgno_t, u_int));
     93 int	 mpool_put __P((MPOOL *, void *, u_int));
     94 int	 mpool_sync __P((MPOOL *));
     95 int	 mpool_close __P((MPOOL *));
     96 #ifdef STATISTICS
     97 void	 mpool_stat __P((MPOOL *));
     98 #endif
     99 __END_DECLS
    100