include/mpool.h

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*-
  26  * Copyright (c) 1991, 1993
  27  *      The Regents of the University of California.  All rights reserved.
  28  *
  29  * Redistribution and use in source and binary forms, with or without
  30  * modification, are permitted provided that the following conditions
  31  * are met:
  32  * 1. Redistributions of source code must retain the above copyright
  33  *    notice, this list of conditions and the following disclaimer.
  34  * 2. Redistributions in binary form must reproduce the above copyright
  35  *    notice, this list of conditions and the following disclaimer in the
  36  *    documentation and/or other materials provided with the distribution.
  37  * 3. All advertising materials mentioning features or use of this software
  38  *    must display the following acknowledgement:
  39  *      This product includes software developed by the University of
  40  *      California, Berkeley and its contributors.
  41  * 4. Neither the name of the University nor the names of its contributors
  42  *    may be used to endorse or promote products derived from this software
  43  *    without specific prior written permission.
  44  *
  45  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  46  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  47  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  48  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  49  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  50  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  51  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  52  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  53  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  54  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  55  * SUCH DAMAGE.
  56  *
  57  *      @(#)mpool.h     8.1 (Berkeley) 6/2/93
  58  */
  59
  60 /*
  61  * The memory pool scheme is a simple one.  Each in memory page is referenced
  62  * by a bucket which is threaded in three ways.  All active pages are threaded
  63  * on a hash chain (hashed by the page number) and an lru chain.  Inactive
  64  * pages are threaded on a free chain.  Each reference to a memory pool is
  65  * handed an MPOOL which is the opaque cookie passed to all of the memory
  66  * routines.
  67  */
  68 #define HASHSIZE        128
  69 #define HASHKEY(pgno)   ((pgno - 1) % HASHSIZE)
  70
  71 /* The BKT structures are the elements of the lists. */
  72 typedef struct BKT {
  73         struct BKT      *hnext;         /* next hash bucket */
  74         struct BKT      *hprev;         /* previous hash bucket */
  75         struct BKT      *cnext;         /* next free/lru bucket */
  76         struct BKT      *cprev;         /* previous free/lru bucket */
  77         void            *page;          /* page */
  78         pgno_t          pgno;           /* page number */
  79
  80 #define MPOOL_DIRTY     0x01            /* page needs to be written */
  81 #define MPOOL_PINNED    0x02            /* page is pinned into memory */
  82         unsigned long   flags;          /* flags */
  83 } BKT;
  84
  85 /* The BKTHDR structures are the heads of the lists. */
  86 typedef struct BKTHDR {
  87         struct BKT      *hnext;         /* next hash bucket */
  88         struct BKT      *hprev;         /* previous hash bucket */
  89         struct BKT      *cnext;         /* next free/lru bucket */
  90         struct BKT      *cprev;         /* previous free/lru bucket */
  91 } BKTHDR;
  92
  93 typedef struct MPOOL {
  94         BKTHDR  free;                   /* The free list. */
  95         BKTHDR  lru;                    /* The LRU list. */
  96         BKTHDR  hashtable[HASHSIZE];    /* Hashed list by page number. */
  97         pgno_t  curcache;               /* Current number of cached pages. */
  98         pgno_t  maxcache;               /* Max number of cached pages. */
  99         pgno_t  npages;                 /* Number of pages in the file. */
 100         u_long  pagesize;               /* File page size. */
 101         int     fd;                     /* File descriptor. */
 102                                         /* Page in conversion routine. */
 103         void    (*pgin) __P((void *, pgno_t, void *));
 104                                         /* Page out conversion routine. */
 105         void    (*pgout) __P((void *, pgno_t, void *));
 106         void    *pgcookie;              /* Cookie for page in/out routines. */
 107 #ifdef STATISTICS
 108         unsigned long   cachehit;
 109         unsigned long   cachemiss;
 110         unsigned long   pagealloc;
 111         unsigned long   pageflush;
 112         unsigned long   pageget;
 113         unsigned long   pagenew;
 114         unsigned long   pageput;
 115         unsigned long   pageread;
 116         unsigned long   pagewrite;
 117 #endif
 118 } MPOOL;
 119
 120 #ifdef __MPOOLINTERFACE_PRIVATE
 121 /* Macros to insert/delete into/from hash chain. */
 122 #define rmhash(bp) { \
 123         (bp)->hprev->hnext = (bp)->hnext; \
 124         (bp)->hnext->hprev = (bp)->hprev; \
 125 }
 126 #define inshash(bp, pg) { \
 127         hp = &mp->hashtable[HASHKEY(pg)]; \
 128         (bp)->hnext = hp->hnext; \
 129         (bp)->hprev = (struct BKT *)hp; \
 130         hp->hnext->hprev = (bp); \
 131         hp->hnext = (bp); \
 132 }
 133
 134 /* Macros to insert/delete into/from lru and free chains. */
 135 #define rmchain(bp) { \
 136         (bp)->cprev->cnext = (bp)->cnext; \
 137         (bp)->cnext->cprev = (bp)->cprev; \
 138 }
 139 #define inschain(bp, dp) { \
 140         (bp)->cnext = (dp)->cnext; \
 141         (bp)->cprev = (struct BKT *)(dp); \
 142         (dp)->cnext->cprev = (bp); \
 143         (dp)->cnext = (bp); \
 144 }
 145 #endif
 146
 147 __BEGIN_DECLS
 148 MPOOL   *mpool_open __P((DBT *, int, pgno_t, pgno_t));
 149 void     mpool_filter __P((MPOOL *, void (*)(void *, pgno_t, void *),
 150             void (*)(void *, pgno_t, void *), void *));
 151 void    *mpool_new __P((MPOOL *, pgno_t *));
 152 void    *mpool_get __P((MPOOL *, pgno_t, u_int));
 153 int      mpool_put __P((MPOOL *, void *, u_int));
 154 int      mpool_sync __P((MPOOL *));
 155 int      mpool_close __P((MPOOL *));
 156 #ifdef STATISTICS
 157 void     mpool_stat __P((MPOOL *));
 158 #endif
 159 __END_DECLS