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 1.5.6.2 2001/03/05 23:05:08 obrien Exp $
  35  * $DragonFly: src/include/mpool.h,v 1.3 2003/11/14 01:01:43 dillon Exp $
  36  */
  37
  38 #ifndef _MPOOL_H_
  39 #define _MPOOL_H_
  40
  41 #include <sys/queue.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. */
  54 typedef struct _bkt {
  55         TAILQ_ENTRY(_bkt) hq;           /* hash queue */
  56         TAILQ_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
  65 typedef struct MPOOL {
  66         TAILQ_HEAD(_lqh, _bkt) lqh;     /* lru queue head */
  67                                         /* hash queue array */
  68         TAILQ_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) (void *, pgno_t, void *);
  76                                         /* page out conversion routine */
  77         void    (*pgout) (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
  93 MPOOL   *mpool_open (void *, int, pgno_t, pgno_t);
  94 void     mpool_filter (MPOOL *, void (*)(void *, pgno_t, void *),
  95             void (*)(void *, pgno_t, void *), void *);
  96 void    *mpool_new (MPOOL *, pgno_t *);
  97 void    *mpool_get (MPOOL *, pgno_t, u_int);
  98 int      mpool_put (MPOOL *, void *, u_int);
  99 int      mpool_sync (MPOOL *);
 100 int      mpool_close (MPOOL *);
 101 #ifdef STATISTICS
 102 void     mpool_stat (MPOOL *);
 103 #endif
 104 __END_DECLS
 105
 106 #endif