include/mpool.h

   1 /*
   2  * Copyright (c) 2003 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, 1994
  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     8.2 (Berkeley) 7/14/94
  58  * $FreeBSD: src/include/mpool.h,v 1.9 2002/03/23 17:24:53 imp Exp $
  59  */
  60
  61 #ifndef _MPOOL_H_
  62 #define _MPOOL_H_
  63
  64 #include <sys/queue.h>
  65
  66 /*
  67  * The memory pool scheme is a simple one.  Each in-memory page is referenced
  68  * by a bucket which is threaded in up to two of three ways.  All active pages
  69  * are threaded on a hash chain (hashed by page number) and an lru chain.
  70  * Inactive pages are threaded on a free chain.  Each reference to a memory
  71  * pool is handed an opaque MPOOL cookie which stores all of this information.
  72  */
  73 #define HASHSIZE        128
  74 #define HASHKEY(pgno)   ((pgno - 1) % HASHSIZE)
  75
  76 /* The BKT structures are the elements of the queues. */
  77 typedef struct _bkt {
  78         TAILQ_ENTRY(_bkt) hq;           /* hash queue */
  79         TAILQ_ENTRY(_bkt) q;            /* lru queue */
  80         void    *page;                  /* page */
  81         pgno_t   pgno;                  /* page number */
  82
  83 #define MPOOL_DIRTY     0x01            /* page needs to be written */
  84 #define MPOOL_PINNED    0x02            /* page is pinned into memory */
  85         u_int8_t flags;                 /* flags */
  86 } BKT;
  87
  88 typedef struct MPOOL {
  89         TAILQ_HEAD(_lqh, _bkt) lqh;     /* lru queue head */
  90                                         /* hash queue array */
  91         TAILQ_HEAD(_hqh, _bkt) hqh[HASHSIZE];
  92         pgno_t  curcache;               /* current number of cached pages */
  93         pgno_t  maxcache;               /* max number of cached pages */
  94         pgno_t  npages;                 /* number of pages in the file */
  95         u_long  pagesize;               /* file page size */
  96         int     fd;                     /* file descriptor */
  97                                         /* page in conversion routine */
  98         void    (*pgin)(void *, pgno_t, void *);
  99                                         /* page out conversion routine */
 100         void    (*pgout)(void *, pgno_t, void *);
 101         void    *pgcookie;              /* cookie for page in/out routines */
 102 #ifdef STATISTICS
 103         u_long  cachehit;
 104         u_long  cachemiss;
 105         u_long  pagealloc;
 106         u_long  pageflush;
 107         u_long  pageget;
 108         u_long  pagenew;
 109         u_long  pageput;
 110         u_long  pageread;
 111         u_long  pagewrite;
 112 #endif
 113 } MPOOL;
 114
 115 __BEGIN_DECLS
 116 MPOOL   *mpool_open(void *, int, pgno_t, pgno_t);
 117 void     mpool_filter(MPOOL *, void (*)(void *, pgno_t, void *),
 118             void (*)(void *, pgno_t, void *), void *);
 119 void    *mpool_new(MPOOL *, pgno_t *);
 120 void    *mpool_get(MPOOL *, pgno_t, u_int);
 121 int      mpool_put(MPOOL *, void *, u_int);
 122 int      mpool_sync(MPOOL *);
 123 int      mpool_close(MPOOL *);
 124 #ifdef STATISTICS
 125 void     mpool_stat(MPOOL *);
 126 #endif
 127 __END_DECLS
 128
 129 #endif