db/btree/bt_overflow-fbsd.c

   1 /*-
   2  * Copyright (c) 1990, 1993, 1994
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * This code is derived from software contributed to Berkeley by
   6  * Mike Olson.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by the University of
  19  *      California, Berkeley and its contributors.
  20  * 4. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  */
  36
  37 #if defined(LIBC_SCCS) && !defined(lint)
  38 static char sccsid[] = "@(#)bt_overflow.c       8.5 (Berkeley) 7/16/94";
  39 #endif /* LIBC_SCCS and not lint */
  40 #include <sys/cdefs.h>
  41 __FBSDID("$FreeBSD: src/lib/libc/db/btree/bt_overflow.c,v 1.3 2002/03/22 21:52:01 obrien Exp $");
  42
  43 #include <sys/param.h>
  44
  45 #include <stdio.h>
  46 #include <stdlib.h>
  47 #include <string.h>
  48
  49 #include <db.h>
  50 #include "btree.h"
  51
  52 /*
  53  * Big key/data code.
  54  *
  55  * Big key and data entries are stored on linked lists of pages.  The initial
  56  * reference is byte string stored with the key or data and is the page number
  57  * and size.  The actual record is stored in a chain of pages linked by the
  58  * nextpg field of the PAGE header.
  59  *
  60  * The first page of the chain has a special property.  If the record is used
  61  * by an internal page, it cannot be deleted and the P_PRESERVE bit will be set
  62  * in the header.
  63  *
  64  * XXX
  65  * A single DBT is written to each chain, so a lot of space on the last page
  66  * is wasted.  This is a fairly major bug for some data sets.
  67  */
  68
  69 /*
  70  * __OVFL_GET -- Get an overflow key/data item.
  71  *
  72  * Parameters:
  73  *      t:      tree
  74  *      p:      pointer to { pgno_t, u_int32_t }
  75  *      buf:    storage address
  76  *      bufsz:  storage size
  77  *
  78  * Returns:
  79  *      RET_ERROR, RET_SUCCESS
  80  */
  81 int
  82 __ovfl_get(t, p, ssz, buf, bufsz)
  83         BTREE *t;
  84         void *p;
  85         size_t *ssz;
  86         void **buf;
  87         size_t *bufsz;
  88 {
  89         PAGE *h;
  90         pgno_t pg;
  91         size_t nb, plen;
  92         u_int32_t sz;
  93
  94         memmove(&pg, p, sizeof(pgno_t));
  95         memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(u_int32_t));
  96         *ssz = sz;
  97
  98 #ifdef DEBUG
  99         if (pg == P_INVALID || sz == 0)
 100                 abort();
 101 #endif
 102         /* Make the buffer bigger as necessary. */
 103         if (*bufsz < sz) {
 104                 *buf = (char *)(*buf == NULL ? malloc(sz) : reallocf(*buf, sz));
 105                 if (*buf == NULL)
 106                         return (RET_ERROR);
 107                 *bufsz = sz;
 108         }
 109
 110         /*
 111          * Step through the linked list of pages, copying the data on each one
 112          * into the buffer.  Never copy more than the data's length.
 113          */
 114         plen = t->bt_psize - BTDATAOFF;
 115         for (p = *buf;; p = (char *)p + nb, pg = h->nextpg) {
 116                 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
 117                         return (RET_ERROR);
 118
 119                 nb = MIN(sz, plen);
 120                 memmove(p, (char *)h + BTDATAOFF, nb);
 121                 mpool_put(t->bt_mp, h, 0);
 122
 123                 if ((sz -= nb) == 0)
 124                         break;
 125         }
 126         return (RET_SUCCESS);
 127 }
 128
 129 /*
 130  * __OVFL_PUT -- Store an overflow key/data item.
 131  *
 132  * Parameters:
 133  *      t:      tree
 134  *      data:   DBT to store
 135  *      pgno:   storage page number
 136  *
 137  * Returns:
 138  *      RET_ERROR, RET_SUCCESS
 139  */
 140 int
 141 __ovfl_put(t, dbt, pg)
 142         BTREE *t;
 143         const DBT *dbt;
 144         pgno_t *pg;
 145 {
 146         PAGE *h, *last;
 147         void *p;
 148         pgno_t npg;
 149         size_t nb, plen;
 150         u_int32_t sz;
 151
 152         /*
 153          * Allocate pages and copy the key/data record into them.  Store the
 154          * number of the first page in the chain.
 155          */
 156         plen = t->bt_psize - BTDATAOFF;
 157         for (last = NULL, p = dbt->data, sz = dbt->size;;
 158             p = (char *)p + plen, last = h) {
 159                 if ((h = __bt_new(t, &npg)) == NULL)
 160                         return (RET_ERROR);
 161
 162                 h->pgno = npg;
 163                 h->nextpg = h->prevpg = P_INVALID;
 164                 h->flags = P_OVERFLOW;
 165                 h->lower = h->upper = 0;
 166
 167                 nb = MIN(sz, plen);
 168                 memmove((char *)h + BTDATAOFF, p, nb);
 169
 170                 if (last) {
 171                         last->nextpg = h->pgno;
 172                         mpool_put(t->bt_mp, last, MPOOL_DIRTY);
 173                 } else
 174                         *pg = h->pgno;
 175
 176                 if ((sz -= nb) == 0) {
 177                         mpool_put(t->bt_mp, h, MPOOL_DIRTY);
 178                         break;
 179                 }
 180         }
 181         return (RET_SUCCESS);
 182 }
 183
 184 /*
 185  * __OVFL_DELETE -- Delete an overflow chain.
 186  *
 187  * Parameters:
 188  *      t:      tree
 189  *      p:      pointer to { pgno_t, u_int32_t }
 190  *
 191  * Returns:
 192  *      RET_ERROR, RET_SUCCESS
 193  */
 194 int
 195 __ovfl_delete(t, p)
 196         BTREE *t;
 197         void *p;
 198 {
 199         PAGE *h;
 200         pgno_t pg;
 201         size_t plen;
 202         u_int32_t sz;
 203
 204         memmove(&pg, p, sizeof(pgno_t));
 205         memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(u_int32_t));
 206
 207 #ifdef DEBUG
 208         if (pg == P_INVALID || sz == 0)
 209                 abort();
 210 #endif
 211         if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
 212                 return (RET_ERROR);
 213
 214         /* Don't delete chains used by internal pages. */
 215         if (h->flags & P_PRESERVE) {
 216                 mpool_put(t->bt_mp, h, 0);
 217                 return (RET_SUCCESS);
 218         }
 219
 220         /* Step through the chain, calling the free routine for each page. */
 221         for (plen = t->bt_psize - BTDATAOFF;; sz -= plen) {
 222                 pg = h->nextpg;
 223                 __bt_free(t, h);
 224                 if (sz <= plen)
 225                         break;
 226                 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
 227                         return (RET_ERROR);
 228         }
 229         return (RET_SUCCESS);
 230 }