include/mpool.h

   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  * $FreeBSD: src/include/mpool.h,v 1.9 2002/03/23 17:24:53 imp Exp $
  35  */
  36
  37 #ifndef _MPOOL_H_
  38 #define _MPOOL_H_
  39
  40 #include <sys/queue.h>
  41
  42 /*
  43  * The memory pool scheme is a simple one.  Each in-memory page is referenced
  44  * by a bucket which is threaded in up to two of three ways.  All active pages
  45  * are threaded on a hash chain (hashed by page number) and an lru chain.
  46  * Inactive pages are threaded on a free chain.  Each reference to a memory
  47  * pool is handed an opaque MPOOL cookie which stores all of this information.
  48  */
  49 #define HASHSIZE        128
  50 #define HASHKEY(pgno)   ((pgno - 1) % HASHSIZE)
  51
  52 /* The BKT structures are the elements of the queues. */
  53 typedef struct _bkt {
  54         TAILQ_ENTRY(_bkt) hq;           /* hash queue */
  55         TAILQ_ENTRY(_bkt) q;            /* lru queue */
  56         void    *page;                  /* page */
  57         pgno_t   pgno;                  /* page number */
  58
  59 #define MPOOL_DIRTY     0x01            /* page needs to be written */
  60 #define MPOOL_PINNED    0x02            /* page is pinned into memory */
  61         u_int8_t flags;                 /* flags */
  62 } BKT;
  63
  64 typedef struct MPOOL {
  65         TAILQ_HEAD(_lqh, _bkt) lqh;     /* lru queue head */
  66                                         /* hash queue array */
  67         TAILQ_HEAD(_hqh, _bkt) hqh[HASHSIZE];
  68         pgno_t  curcache;               /* current number of cached pages */
  69         pgno_t  maxcache;               /* max number of cached pages */
  70         pgno_t  npages;                 /* number of pages in the file */
  71         unsigned long   pagesize;       /* file page size */
  72         int     fd;                     /* file descriptor */
  73                                         /* page in conversion routine */
  74         void    (*pgin)(void *, pgno_t, void *);
  75                                         /* page out conversion routine */
  76         void    (*pgout)(void *, pgno_t, void *);
  77         void    *pgcookie;              /* cookie for page in/out routines */
  78 #ifdef STATISTICS
  79         unsigned long   cachehit;
  80         unsigned long   cachemiss;
  81         unsigned long   pagealloc;
  82         unsigned long   pageflush;
  83         unsigned long   pageget;
  84         unsigned long   pagenew;
  85         unsigned long   pageput;
  86         unsigned long   pageread;
  87         unsigned long   pagewrite;
  88 #endif
  89 } MPOOL;
  90
  91 __BEGIN_DECLS
  92 MPOOL   *mpool_open(void *, int, pgno_t, pgno_t);
  93 void     mpool_filter(MPOOL *, void (*)(void *, pgno_t, void *),
  94             void (*)(void *, pgno_t, void *), void *);
  95 void    *mpool_new(MPOOL *, pgno_t *);
  96 void    *mpool_get(MPOOL *, pgno_t, unsigned int);
  97 int      mpool_put(MPOOL *, void *, unsigned int);
  98 int      mpool_sync(MPOOL *);
  99 int      mpool_close(MPOOL *);
 100 #ifdef STATISTICS
 101 void     mpool_stat(MPOOL *);
 102 #endif
 103 __END_DECLS
 104
 105 #endif