db/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  */
  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