1 /*- 2 * Copyright (c) 1990, 1993 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 = "from: @(#)bt_overflow.c 8.1 (Berkeley) 6/4/93";*/ 39 static char *rcsid = "$Id: bt_overflow.c,v 1.3 1993/08/26 00:43:23 jtc Exp $"; 40 #endif /* LIBC_SCCS and not lint */ 41 42 #include <sys/param.h> 43 44 #include <stdio.h> 45 #include <stdlib.h> 46 #include <string.h> 47 48 #include <db.h> 49 #include "btree.h" 50 51 /* 52 * Big key/data code. 53 * 54 * Big key and data entries are stored on linked lists of pages. The initial 55 * reference is byte string stored with the key or data and is the page number 56 * and size. The actual record is stored in a chain of pages linked by the 57 * nextpg field of the PAGE header. 58 * 59 * The first page of the chain has a special property. If the record is used 60 * by an internal page, it cannot be deleted and the P_PRESERVE bit will be set 61 * in the header. 62 * 63 * XXX 64 * A single DBT is written to each chain, so a lot of space on the last page 65 * is wasted. This is a fairly major bug for some data sets. 66 */ 67 68 /* 69 * __OVFL_GET -- Get an overflow key/data item. 70 * 71 * Parameters: 72 * t: tree 73 * p: pointer to { pgno_t, size_t } 74 * buf: storage address 75 * bufsz: storage size 76 * 77 * Returns: 78 * RET_ERROR, RET_SUCCESS 79 */ 80 int 81 __ovfl_get(t, p, ssz, buf, bufsz) 82 BTREE *t; 83 void *p; 84 size_t *ssz; 85 char **buf; 86 size_t *bufsz; 87 { 88 PAGE *h; 89 pgno_t pg; 90 size_t nb, plen, sz; 91 92 memmove(&pg, p, sizeof(pgno_t)); 93 memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(size_t)); 94 *ssz = sz; 95 96 #ifdef DEBUG 97 if (pg == P_INVALID || sz == 0) 98 abort(); 99 #endif 100 /* Make the buffer bigger as necessary. */ 101 if (*bufsz < sz) { 102 if ((*buf = realloc(*buf, sz)) == NULL) 103 return (RET_ERROR); 104 *bufsz = sz; 105 } 106 107 /* 108 * Step through the linked list of pages, copying the data on each one 109 * into the buffer. Never copy more than the data's length. 110 */ 111 plen = t->bt_psize - BTDATAOFF; 112 for (p = *buf;; p = (char *)p + nb, pg = h->nextpg) { 113 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 114 return (RET_ERROR); 115 116 nb = MIN(sz, plen); 117 memmove(p, (char *)h + BTDATAOFF, nb); 118 mpool_put(t->bt_mp, h, 0); 119 120 if ((sz -= nb) == 0) 121 break; 122 } 123 return (RET_SUCCESS); 124 } 125 126 /* 127 * __OVFL_PUT -- Store an overflow key/data item. 128 * 129 * Parameters: 130 * t: tree 131 * data: DBT to store 132 * pgno: storage page number 133 * 134 * Returns: 135 * RET_ERROR, RET_SUCCESS 136 */ 137 int 138 __ovfl_put(t, dbt, pg) 139 BTREE *t; 140 const DBT *dbt; 141 pgno_t *pg; 142 { 143 PAGE *h, *last; 144 void *p; 145 pgno_t npg; 146 size_t nb, plen, sz; 147 148 /* 149 * Allocate pages and copy the key/data record into them. Store the 150 * number of the first page in the chain. 151 */ 152 plen = t->bt_psize - BTDATAOFF; 153 for (last = NULL, p = dbt->data, sz = dbt->size;; 154 p = (char *)p + plen, last = h) { 155 if ((h = __bt_new(t, &npg)) == NULL) 156 return (RET_ERROR); 157 158 h->pgno = npg; 159 h->nextpg = h->prevpg = P_INVALID; 160 h->flags = P_OVERFLOW; 161 h->lower = h->upper = 0; 162 163 nb = MIN(sz, plen); 164 memmove((char *)h + BTDATAOFF, p, nb); 165 166 if (last) { 167 last->nextpg = h->pgno; 168 mpool_put(t->bt_mp, last, MPOOL_DIRTY); 169 } else 170 *pg = h->pgno; 171 172 if ((sz -= nb) == 0) { 173 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 174 break; 175 } 176 } 177 return (RET_SUCCESS); 178 } 179 180 /* 181 * __OVFL_DELETE -- Delete an overflow chain. 182 * 183 * Parameters: 184 * t: tree 185 * p: pointer to { pgno_t, size_t } 186 * 187 * Returns: 188 * RET_ERROR, RET_SUCCESS 189 */ 190 int 191 __ovfl_delete(t, p) 192 BTREE *t; 193 void *p; 194 { 195 PAGE *h; 196 pgno_t pg; 197 size_t plen, sz; 198 199 memmove(&pg, p, sizeof(pgno_t)); 200 memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(size_t)); 201 202 #ifdef DEBUG 203 if (pg == P_INVALID || sz == 0) 204 abort(); 205 #endif 206 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 207 return (RET_ERROR); 208 209 /* Don't delete chains used by internal pages. */ 210 if (h->flags & P_PRESERVE) { 211 mpool_put(t->bt_mp, h, 0); 212 return (RET_SUCCESS); 213 } 214 215 /* Step through the chain, calling the free routine for each page. */ 216 for (plen = t->bt_psize - BTDATAOFF;; sz -= plen) { 217 pg = h->nextpg; 218 __bt_free(t, h); 219 if (sz <= plen) 220 break; 221 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 222 return (RET_ERROR); 223 } 224 return (RET_SUCCESS); 225 } 226