rec_delete.c revision 1.6
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[] = "@(#)rec_delete.c 8.6 (Berkeley) 6/4/94"; 39 #endif /* LIBC_SCCS and not lint */ 40 41 #include <sys/types.h> 42 43 #include <errno.h> 44 #include <stdio.h> 45 #include <string.h> 46 47 #include <db.h> 48 #include "recno.h" 49 50 static int rec_rdelete __P((BTREE *, recno_t)); 51 52 /* 53 * __REC_DELETE -- Delete the item(s) referenced by a key. 54 * 55 * Parameters: 56 * dbp: pointer to access method 57 * key: key to delete 58 * flags: R_CURSOR if deleting what the cursor references 59 * 60 * Returns: 61 * RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found. 62 */ 63 int 64 __rec_delete(dbp, key, flags) 65 const DB *dbp; 66 const DBT *key; 67 u_int flags; 68 { 69 BTREE *t; 70 recno_t nrec; 71 int status; 72 73 t = dbp->internal; 74 75 /* Toss any page pinned across calls. */ 76 if (t->bt_pinned != NULL) { 77 mpool_put(t->bt_mp, t->bt_pinned, 0); 78 t->bt_pinned = NULL; 79 } 80 81 switch(flags) { 82 case 0: 83 if ((nrec = *(recno_t *)key->data) == 0) 84 goto einval; 85 if (nrec > t->bt_nrecs) 86 return (RET_SPECIAL); 87 --nrec; 88 status = rec_rdelete(t, nrec); 89 break; 90 case R_CURSOR: 91 if (!ISSET(t, B_SEQINIT)) 92 goto einval; 93 if (t->bt_nrecs == 0) 94 return (RET_SPECIAL); 95 status = rec_rdelete(t, t->bt_rcursor - 1); 96 if (status == RET_SUCCESS) 97 --t->bt_rcursor; 98 break; 99 default: 100 einval: errno = EINVAL; 101 return (RET_ERROR); 102 } 103 104 if (status == RET_SUCCESS) 105 SET(t, B_MODIFIED | R_MODIFIED); 106 return (status); 107 } 108 109 /* 110 * REC_RDELETE -- Delete the data matching the specified key. 111 * 112 * Parameters: 113 * tree: tree 114 * nrec: record to delete 115 * 116 * Returns: 117 * RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found. 118 */ 119 static int 120 rec_rdelete(t, nrec) 121 BTREE *t; 122 recno_t nrec; 123 { 124 EPG *e; 125 PAGE *h; 126 int status; 127 128 /* Find the record; __rec_search pins the page. */ 129 if ((e = __rec_search(t, nrec, SDELETE)) == NULL) 130 return (RET_ERROR); 131 132 /* Delete the record. */ 133 h = e->page; 134 status = __rec_dleaf(t, h, e->index); 135 if (status != RET_SUCCESS) { 136 mpool_put(t->bt_mp, h, 0); 137 return (status); 138 } 139 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 140 return (RET_SUCCESS); 141 } 142 143 /* 144 * __REC_DLEAF -- Delete a single record from a recno leaf page. 145 * 146 * Parameters: 147 * t: tree 148 * index: index on current page to delete 149 * 150 * Returns: 151 * RET_SUCCESS, RET_ERROR. 152 */ 153 int 154 __rec_dleaf(t, h, index) 155 BTREE *t; 156 PAGE *h; 157 u_int32_t index; 158 { 159 RLEAF *rl; 160 indx_t *ip, cnt, offset; 161 u_int32_t nbytes; 162 char *from; 163 void *to; 164 165 /* 166 * Delete a record from a recno leaf page. Internal records are never 167 * deleted from internal pages, regardless of the records that caused 168 * them to be added being deleted. Pages made empty by deletion are 169 * not reclaimed. They are, however, made available for reuse. 170 * 171 * Pack the remaining entries at the end of the page, shift the indices 172 * down, overwriting the deleted record and its index. If the record 173 * uses overflow pages, make them available for reuse. 174 */ 175 to = rl = GETRLEAF(h, index); 176 if (rl->flags & P_BIGDATA && __ovfl_delete(t, rl->bytes) == RET_ERROR) 177 return (RET_ERROR); 178 nbytes = NRLEAF(rl); 179 180 /* 181 * Compress the key/data pairs. Compress and adjust the [BR]LEAF 182 * offsets. Reset the headers. 183 */ 184 from = (char *)h + h->upper; 185 memmove(from + nbytes, from, (char *)to - from); 186 h->upper += nbytes; 187 188 offset = h->linp[index]; 189 for (cnt = &h->linp[index] - (ip = &h->linp[0]); cnt--; ++ip) 190 if (ip[0] < offset) 191 ip[0] += nbytes; 192 for (cnt = &h->linp[NEXTINDEX(h)] - ip; --cnt; ++ip) 193 ip[0] = ip[1] < offset ? ip[1] + nbytes : ip[1]; 194 h->lower -= sizeof(indx_t); 195 --t->bt_nrecs; 196 return (RET_SUCCESS); 197 } 198
Indexes created Mon Sep 22 13:09:51 GMT 2025