db/recno/rec_delete.c

   1 /*
   2  * Copyright (c) 2003 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23 /*-
  24  * Copyright (c) 1990, 1993, 1994
  25  *      The Regents of the University of California.  All rights reserved.
  26  *
  27  * This code is derived from software contributed to Berkeley by
  28  * Mike Olson.
  29  *
  30  * Redistribution and use in source and binary forms, with or without
  31  * modification, are permitted provided that the following conditions
  32  * are met:
  33  * 1. Redistributions of source code must retain the above copyright
  34  *    notice, this list of conditions and the following disclaimer.
  35  * 2. Redistributions in binary form must reproduce the above copyright
  36  *    notice, this list of conditions and the following disclaimer in the
  37  *    documentation and/or other materials provided with the distribution.
  38  * 3. All advertising materials mentioning features or use of this software
  39  *    must display the following acknowledgement:
  40  *      This product includes software developed by the University of
  41  *      California, Berkeley and its contributors.
  42  * 4. Neither the name of the University nor the names of its contributors
  43  *    may be used to endorse or promote products derived from this software
  44  *    without specific prior written permission.
  45  *
  46  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  47  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  48  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  49  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  50  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  51  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  52  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  53  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  54  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  55  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  56  * SUCH DAMAGE.
  57  */
  58
  59 #if defined(LIBC_SCCS) && !defined(lint)
  60 static char sccsid[] = "@(#)rec_delete.c        8.7 (Berkeley) 7/14/94";
  61 #endif /* LIBC_SCCS and not lint */
  62 #include <sys/cdefs.h>
  63
  64 #include <sys/types.h>
  65
  66 #include <errno.h>
  67 #include <stdio.h>
  68 #include <string.h>
  69
  70 #include <db.h>
  71 #include "recno.h"
  72
  73 static int rec_rdelete(BTREE *, recno_t);
  74
  75 /*
  76  * __REC_DELETE -- Delete the item(s) referenced by a key.
  77  *
  78  * Parameters:
  79  *      dbp:    pointer to access method
  80  *      key:    key to delete
  81  *      flags:  R_CURSOR if deleting what the cursor references
  82  *
  83  * Returns:
  84  *      RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found.
  85  */
  86 int
  87 __rec_delete(dbp, key, flags)
  88         const DB *dbp;
  89         const DBT *key;
  90         u_int flags;
  91 {
  92         BTREE *t;
  93         recno_t nrec;
  94         int status;
  95
  96         t = dbp->internal;
  97
  98         /* Toss any page pinned across calls. */
  99         if (t->bt_pinned != NULL) {
 100                 mpool_put(t->bt_mp, t->bt_pinned, 0);
 101                 t->bt_pinned = NULL;
 102         }
 103
 104         switch(flags) {
 105         case 0:
 106                 if ((nrec = *(recno_t *)key->data) == 0)
 107                         goto einval;
 108                 if (nrec > t->bt_nrecs)
 109                         return (RET_SPECIAL);
 110                 --nrec;
 111                 status = rec_rdelete(t, nrec);
 112                 break;
 113         case R_CURSOR:
 114                 if (!F_ISSET(&t->bt_cursor, CURS_INIT))
 115                         goto einval;
 116                 if (t->bt_nrecs == 0)
 117                         return (RET_SPECIAL);
 118                 status = rec_rdelete(t, t->bt_cursor.rcursor - 1);
 119                 if (status == RET_SUCCESS)
 120                         --t->bt_cursor.rcursor;
 121                 break;
 122         default:
 123 einval:         errno = EINVAL;
 124                 return (RET_ERROR);
 125         }
 126
 127         if (status == RET_SUCCESS)
 128                 F_SET(t, B_MODIFIED | R_MODIFIED);
 129         return (status);
 130 }
 131
 132 /*
 133  * REC_RDELETE -- Delete the data matching the specified key.
 134  *
 135  * Parameters:
 136  *      tree:   tree
 137  *      nrec:   record to delete
 138  *
 139  * Returns:
 140  *      RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found.
 141  */
 142 static int
 143 rec_rdelete(t, nrec)
 144         BTREE *t;
 145         recno_t nrec;
 146 {
 147         EPG *e;
 148         PAGE *h;
 149         int status;
 150
 151         /* Find the record; __rec_search pins the page. */
 152         if ((e = __rec_search(t, nrec, SDELETE)) == NULL)
 153                 return (RET_ERROR);
 154
 155         /* Delete the record. */
 156         h = e->page;
 157         status = __rec_dleaf(t, h, e->index);
 158         if (status != RET_SUCCESS) {
 159                 mpool_put(t->bt_mp, h, 0);
 160                 return (status);
 161         }
 162         mpool_put(t->bt_mp, h, MPOOL_DIRTY);
 163         return (RET_SUCCESS);
 164 }
 165
 166 /*
 167  * __REC_DLEAF -- Delete a single record from a recno leaf page.
 168  *
 169  * Parameters:
 170  *      t:      tree
 171  *      index:  index on current page to delete
 172  *
 173  * Returns:
 174  *      RET_SUCCESS, RET_ERROR.
 175  */
 176 int
 177 __rec_dleaf(t, h, index)
 178         BTREE *t;
 179         PAGE *h;
 180         u_int32_t index;
 181 {
 182         RLEAF *rl;
 183         indx_t *ip, cnt, offset;
 184         u_int32_t nbytes;
 185         char *from;
 186         void *to;
 187
 188         /*
 189          * Delete a record from a recno leaf page.  Internal records are never
 190          * deleted from internal pages, regardless of the records that caused
 191          * them to be added being deleted.  Pages made empty by deletion are
 192          * not reclaimed.  They are, however, made available for reuse.
 193          *
 194          * Pack the remaining entries at the end of the page, shift the indices
 195          * down, overwriting the deleted record and its index.  If the record
 196          * uses overflow pages, make them available for reuse.
 197          */
 198         to = rl = GETRLEAF(h, index);
 199         if (rl->flags & P_BIGDATA && __ovfl_delete(t, rl->bytes) == RET_ERROR)
 200                 return (RET_ERROR);
 201         nbytes = NRLEAF(rl);
 202
 203         /*
 204          * Compress the key/data pairs.  Compress and adjust the [BR]LEAF
 205          * offsets.  Reset the headers.
 206          */
 207         from = (char *)h + h->upper;
 208         memmove(from + nbytes, from, (char *)to - from);
 209         h->upper += nbytes;
 210
 211         offset = h->linp[index];
 212         for (cnt = &h->linp[index] - (ip = &h->linp[0]); cnt--; ++ip)
 213                 if (ip[0] < offset)
 214                         ip[0] += nbytes;
 215         for (cnt = &h->linp[NEXTINDEX(h)] - ip; --cnt; ++ip)
 216                 ip[0] = ip[1] < offset ? ip[1] + nbytes : ip[1];
 217         h->lower -= sizeof(indx_t);
 218         --t->bt_nrecs;
 219         return (RET_SUCCESS);
 220 }