rec_delete.c revision 1.16
1 /* $NetBSD: rec_delete.c,v 1.16 2008/09/10 17:52:36 joerg Exp $ */ 2 3 /*- 4 * Copyright (c) 1990, 1993, 1994 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Mike Olson. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #include <sys/cdefs.h> 36 __RCSID("$NetBSD: rec_delete.c,v 1.16 2008/09/10 17:52:36 joerg Exp $"); 37 38 #include "namespace.h" 39 #include <sys/types.h> 40 41 #include <assert.h> 42 #include <errno.h> 43 #include <stdio.h> 44 #include <string.h> 45 46 #include <db.h> 47 #include "recno.h" 48 49 static int rec_rdelete(BTREE *, recno_t); 50 51 /* 52 * __REC_DELETE -- Delete the item(s) referenced by a key. 53 * 54 * Parameters: 55 * dbp: pointer to access method 56 * key: key to delete 57 * flags: R_CURSOR if deleting what the cursor references 58 * 59 * Returns: 60 * RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found. 61 */ 62 int 63 __rec_delete(const DB *dbp, const DBT *key, u_int flags) 64 { 65 BTREE *t; 66 recno_t nrec; 67 int status; 68 69 t = dbp->internal; 70 71 /* Toss any page pinned across calls. */ 72 if (t->bt_pinned != NULL) { 73 mpool_put(t->bt_mp, t->bt_pinned, 0); 74 t->bt_pinned = NULL; 75 } 76 77 switch(flags) { 78 case 0: 79 if ((nrec = *(recno_t *)key->data) == 0) 80 goto einval; 81 if (nrec > t->bt_nrecs) 82 return (RET_SPECIAL); 83 --nrec; 84 status = rec_rdelete(t, nrec); 85 break; 86 case R_CURSOR: 87 if (!F_ISSET(&t->bt_cursor, CURS_INIT)) 88 goto einval; 89 if (t->bt_nrecs == 0) 90 return (RET_SPECIAL); 91 status = rec_rdelete(t, t->bt_cursor.rcursor - 1); 92 if (status == RET_SUCCESS) 93 --t->bt_cursor.rcursor; 94 break; 95 default: 96 einval: errno = EINVAL; 97 return (RET_ERROR); 98 } 99 100 if (status == RET_SUCCESS) 101 F_SET(t, B_MODIFIED | R_MODIFIED); 102 return (status); 103 } 104 105 /* 106 * REC_RDELETE -- Delete the data matching the specified key. 107 * 108 * Parameters: 109 * tree: tree 110 * nrec: record to delete 111 * 112 * Returns: 113 * RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found. 114 */ 115 static int 116 rec_rdelete(BTREE *t, recno_t nrec) 117 { 118 EPG *e; 119 PAGE *h; 120 int status; 121 122 /* Find the record; __rec_search pins the page. */ 123 if ((e = __rec_search(t, nrec, SDELETE)) == NULL) 124 return (RET_ERROR); 125 126 /* Delete the record. */ 127 h = e->page; 128 status = __rec_dleaf(t, h, (uint32_t)e->index); 129 if (status != RET_SUCCESS) { 130 mpool_put(t->bt_mp, h, 0); 131 return (status); 132 } 133 mpool_put(t->bt_mp, h, MPOOL_DIRTY); 134 return (RET_SUCCESS); 135 } 136 137 /* 138 * __REC_DLEAF -- Delete a single record from a recno leaf page. 139 * 140 * Parameters: 141 * t: tree 142 * index: index on current page to delete 143 * 144 * Returns: 145 * RET_SUCCESS, RET_ERROR. 146 */ 147 int 148 __rec_dleaf(BTREE *t, PAGE *h, uint32_t idx) 149 { 150 RLEAF *rl; 151 indx_t *ip, cnt, offset; 152 uint32_t nbytes; 153 char *from; 154 void *to; 155 size_t temp; 156 157 /* 158 * Delete a record from a recno leaf page. Internal records are never 159 * deleted from internal pages, regardless of the records that caused 160 * them to be added being deleted. Pages made empty by deletion are 161 * not reclaimed. They are, however, made available for reuse. 162 * 163 * Pack the remaining entries at the end of the page, shift the indices 164 * down, overwriting the deleted record and its index. If the record 165 * uses overflow pages, make them available for reuse. 166 */ 167 to = rl = GETRLEAF(h, idx); 168 if (rl->flags & P_BIGDATA && __ovfl_delete(t, rl->bytes) == RET_ERROR) 169 return (RET_ERROR); 170 nbytes = NRLEAF(rl); 171 172 /* 173 * Compress the key/data pairs. Compress and adjust the [BR]LEAF 174 * offsets. Reset the headers. 175 */ 176 from = (char *)(void *)h + h->upper; 177 memmove(from + nbytes, from, (size_t)((char *)to - from)); 178 h->upper += nbytes; 179 180 offset = h->linp[idx]; 181 temp = &h->linp[idx] - (ip = &h->linp[0]); 182 _DBFIT(temp, uint16_t); 183 for (cnt = (uint16_t)temp; cnt--; ++ip) 184 if (ip[0] < offset) 185 ip[0] += nbytes; 186 temp = &h->linp[NEXTINDEX(h)] - ip; 187 _DBFIT(temp, uint16_t); 188 for (cnt = (uint16_t)temp; --cnt; ++ip) 189 ip[0] = ip[1] < offset ? ip[1] + nbytes : ip[1]; 190 h->lower -= sizeof(indx_t); 191 --t->bt_nrecs; 192 return (RET_SUCCESS); 193 } 194
Indexes created Tue Oct 21 06:10:07 GMT 2025