dbm/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. ***REMOVED*** - see
  14  *    ftp://ftp.cs.berkeley.edu/pub/4bsd/README.Impt.License.Change
  15  * 4. Neither the name of the University nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  *
  31  *      @(#)mpool.h     8.2 (Berkeley) 7/14/94
  32  */
  33
  34 #include <sys/queue.h>
  35
  36 /*
  37  * The memory pool scheme is a simple one.  Each in-memory page is referenced
  38  * by a bucket which is threaded in up to two of three ways.  All active pages
  39  * are threaded on a hash chain (hashed by page number) and an lru chain.
  40  * Inactive pages are threaded on a free chain.  Each reference to a memory
  41  * pool is handed an opaque MPOOL cookie which stores all of this information.
  42  */
  43 #define HASHSIZE        128
  44 #define HASHKEY(pgno)   ((pgno - 1) % HASHSIZE)
  45
  46 /* The BKT structures are the elements of the queues. */
  47 typedef struct _bkt {
  48         CIRCLEQ_ENTRY(_bkt) hq;         /* hash queue */
  49         CIRCLEQ_ENTRY(_bkt) q;          /* lru queue */
  50         void    *page;                  /* page */
  51         pgno_t   pgno;                  /* page number */
  52
  53 #define MPOOL_DIRTY     0x01            /* page needs to be written */
  54 #define MPOOL_PINNED    0x02            /* page is pinned into memory */
  55         uint8 flags;                    /* flags */
  56 } BKT;
  57
  58 typedef struct MPOOL {
  59         CIRCLEQ_HEAD(_lqh, _bkt) lqh;   /* lru queue head */
  60                                         /* hash queue array */
  61         CIRCLEQ_HEAD(_hqh, _bkt) hqh[HASHSIZE];
  62         pgno_t  curcache;               /* current number of cached pages */
  63         pgno_t  maxcache;               /* max number of cached pages */
  64         pgno_t  npages;                 /* number of pages in the file */
  65         uint32  pagesize;               /* file page size */
  66         int     fd;                     /* file descriptor */
  67                                         /* page in conversion routine */
  68         void    (*pgin) (void *, pgno_t, void *);
  69                                         /* page out conversion routine */
  70         void    (*pgout) (void *, pgno_t, void *);
  71         void    *pgcookie;              /* cookie for page in/out routines */
  72 #ifdef STATISTICS
  73         uint32  cachehit;
  74         uint32  cachemiss;
  75         uint32  pagealloc;
  76         uint32  pageflush;
  77         uint32  pageget;
  78         uint32  pagenew;
  79         uint32  pageput;
  80         uint32  pageread;
  81         uint32  pagewrite;
  82 #endif
  83 } MPOOL;
  84
  85 __BEGIN_DECLS
  86 MPOOL   *mpool_open (void *, int, pgno_t, pgno_t);
  87 void     mpool_filter (MPOOL *, void (*)(void *, pgno_t, void *),
  88             void (*)(void *, pgno_t, void *), void *);
  89 void    *mpool_new (MPOOL *, pgno_t *);
  90 void    *mpool_get (MPOOL *, pgno_t, uint);
  91 int      mpool_put (MPOOL *, void *, uint);
  92 int      mpool_sync (MPOOL *);
  93 int      mpool_close (MPOOL *);
  94 #ifdef STATISTICS
  95 void     mpool_stat (MPOOL *);
  96 #endif
  97 __END_DECLS