root/libdb/mpool.h

/* */

INCLUDED FROM

   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. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  *      @(#)mpool.h     8.2 (Berkeley) 7/14/94
  30  */
  31 
  32 #include "queue.h"
  33 
  34 /**
  35  * The memory pool scheme is a simple one.  Each in-memory page is referenced
  36  * by a bucket which is threaded in up to two of three ways.  All active pages
  37  * are threaded on a hash chain (hashed by page number) and an lru chain.
  38  * Inactive pages are threaded on a free chain.  Each reference to a memory
  39  * pool is handed an opaque #MPOOL cookie which stores all of this information.
  40  */
  41 #define HASHSIZE        128
  42 #define HASHKEY(pgno)   ((pgno - 1) % HASHSIZE)
  43 
  44 /** The BKT structures are the elements of the queues. */
  45 typedef struct _bkt {
  46 
  47 #ifndef IS__DOXYGEN_
  48         CIRCLEQ_ENTRY(_bkt) hq;         /**< hash queue */
  49         CIRCLEQ_ENTRY(_bkt) q;          /**< lru queue */
  50 #else
  51         struct {
  52                 struct _bkt *cqe_next;
  53                 struct _bkt *cqe_prev;
  54         } hq;                                           /**< hash queue */
  55         struct {
  56                 struct _bkt *cqe_next;
  57                 struct _bkt *cqe_prev;
  58         } q;                                            /**< lru queue */
  59 #endif
  60         void    *page;                  /**< page */
  61         pgno_t   pgno;                  /**< page number */
  62 
  63                         /** page needs to be written */
  64 #define MPOOL_DIRTY     0x01
  65                         /** page is pinned into memory */
  66 #define MPOOL_PINNED    0x02
  67         u_int8_t flags;                 /**< flags */
  68 } BKT;
  69 
  70 typedef struct MPOOL {
  71 
  72 #ifndef IS__DOXYGEN_
  73         CIRCLEQ_HEAD(_lqh, _bkt) lqh;   /**< lru queue head */
  74                                         /** hash queue array */
  75         CIRCLEQ_HEAD(_hqh, _bkt) hqh[HASHSIZE];
  76 #else
  77         struct _lqh {
  78                 struct _bkt *cqh_first;
  79                 struct _bkt *cqh_last;
  80         } lqh;                                                  /**< lru queue head */
  81         struct _hqh {
  82                 struct _bkt *cqh_first;
  83                 struct _bkt *cqh_last;
  84         } hqh[HASHSIZE];                                /**< hash queue array */
  85 #endif
  86         pgno_t  curcache;               /**< current number of cached pages */
  87         pgno_t  maxcache;               /**< max number of cached pages */
  88         pgno_t  npages;                 /**< number of pages in the file */
  89         u_long  pagesize;               /**< file page size */
  90         int     fd;                     /**< file descriptor */
  91                                         /** page in conversion routine */
  92         void    (*pgin)(void *, pgno_t, void *);
  93                                         /** page out conversion routine */
  94         void    (*pgout)(void *, pgno_t, void *);
  95         void    *pgcookie;              /**< cookie for page in/out routines */
  96 #ifdef STATISTICS
  97         u_long  cachehit;
  98         u_long  cachemiss;
  99         u_long  pagealloc;
 100         u_long  pageflush;
 101         u_long  pageget;
 102         u_long  pagenew;
 103         u_long  pageput;
 104         u_long  pageread;
 105         u_long  pagewrite;
 106 #endif
 107 } MPOOL;
 108 
 109 MPOOL   *mpool_open(void *, int, pgno_t, pgno_t);
 110 void     mpool_filter(MPOOL *, void (*)(void *, pgno_t, void *),
 111             void (*)(void *, pgno_t, void *), void *);
 112 void    *mpool_new(MPOOL *, pgno_t *);
 113 void    *mpool_get(MPOOL *, pgno_t, u_int);
 114 int      mpool_put(MPOOL *, void *, u_int);
 115 int      mpool_sync(MPOOL *);
 116 int      mpool_close(MPOOL *);
 117 #ifdef STATISTICS
 118 void     mpool_stat(MPOOL *);
 119 #endif

/* */