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 * @(#)bt_overflow.c 8.5 (Berkeley) 7/16/94 37 */ 38 39 #include <sys/param.h> 40 41 #include <stdio.h> 42 #include <stdlib.h> 43 #include <string.h> 44 45 #include <db.h> 46 #include "btree.h" 47 48 /* 49 * Big key/data code. 50 * 51 * Big key and data entries are stored on linked lists of pages. The initial 52 * reference is byte string stored with the key or data and is the page number 53 * and size. The actual record is stored in a chain of pages linked by the 54 * nextpg field of the PAGE header. 55 * 56 * The first page of the chain has a special property. If the record is used 57 * by an internal page, it cannot be deleted and the P_PRESERVE bit will be set 58 * in the header. 59 * 60 * XXX 61 * A single DBT is written to each chain, so a lot of space on the last page 62 * is wasted. This is a fairly major bug for some data sets. 63 */ 64 65 /* 66 * __OVFL_GET -- Get an overflow key/data item. 67 * 68 * Parameters: 69 * t: tree 70 * p: pointer to { pgno_t, u_int32_t } 71 * buf: storage address 72 * bufsz: storage size 73 * 74 * Returns: 75 * RET_ERROR, RET_SUCCESS 76 */ 77 int 78 __ovfl_get(t, p, ssz, buf, bufsz) 79 BTREE *t; 80 void *p; 81 size_t *ssz; 82 void **buf; 83 size_t *bufsz; 84 { 85 PAGE *h; 86 pgno_t pg; 87 size_t nb, plen; 88 u_int32_t sz; 89 90 memmove(&pg, p, sizeof(pgno_t)); 91 memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(u_int32_t)); 92 *ssz = sz; 93 94 #ifdef DEBUG 95 if (pg == P_INVALID || sz == 0) 96 abort(); 97 #endif 98 /* Make the buffer bigger as necessary. */ 99 if (*bufsz < sz) { 100 *buf = (char *)(*buf == NULL ? malloc(sz) : reallocf(*buf, sz)); 101 if (*buf == NULL) 102 return (RET_ERROR); 103 *bufsz = sz; 104 } 105 106 /* 107 * Step through the linked list of pages, copying the data on each one 108 * into the buffer. Never copy more than the data's length. 109 */ 110 plen = t->bt_psize - BTDATAOFF; 111 for (p = *buf;; p = (char *)p + nb, pg = h->nextpg) { 112 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 113 return (RET_ERROR); 114 115 nb = MIN(sz, plen); 116 memmove(p, (char *)h + BTDATAOFF, nb); 117 mpool_put(t->bt_mp, h, 0); 118 119 if ((sz -= nb) == 0) 120 break; 121 } 122 return (RET_SUCCESS); 123 } 124 125 /* 126 * __OVFL_PUT -- Store an overflow key/data item. 127 * 128 * Parameters: 129 * t: tree 130 * data: DBT to store 131 * pgno: storage page number 132 * 133 * Returns: 134 * RET_ERROR, RET_SUCCESS 135 */ 136 int 137 __ovfl_put(t, dbt, pg) 138 BTREE *t; 139 const DBT *dbt; 140 pgno_t *pg; 141 { 142 PAGE *h, *last; 143 void *p; 144 pgno_t npg; 145 size_t nb, plen; 146 u_int32_t 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, u_int32_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; 198 u_int32_t sz; 199 200 memmove(&pg, p, sizeof(pgno_t)); 201 memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(u_int32_t)); 202 203 #ifdef DEBUG 204 if (pg == P_INVALID || sz == 0) 205 abort(); 206 #endif 207 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 208 return (RET_ERROR); 209 210 /* Don't delete chains used by internal pages. */ 211 if (h->flags & P_PRESERVE) { 212 mpool_put(t->bt_mp, h, 0); 213 return (RET_SUCCESS); 214 } 215 216 /* Step through the chain, calling the free routine for each page. */ 217 for (plen = t->bt_psize - BTDATAOFF;; sz -= plen) { 218 pg = h->nextpg; 219 __bt_free(t, h); 220 if (sz <= plen) 221 break; 222 if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 223 return (RET_ERROR); 224 } 225 return (RET_SUCCESS); 226 } 227