db/recno/rec_delete.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*
  26  * Copyright (c) 1990, 1993
  27  *      The Regents of the University of California.  All rights reserved.
  28  *
  29  * This code is derived from software contributed to Berkeley by
  30  * Mike Olson.
  31  *
  32  * Redistribution and use in source and binary forms, with or without
  33  * modification, are permitted provided that the following conditions
  34  * are met:
  35  * 1. Redistributions of source code must retain the above copyright
  36  *    notice, this list of conditions and the following disclaimer.
  37  * 2. Redistributions in binary form must reproduce the above copyright
  38  *    notice, this list of conditions and the following disclaimer in the
  39  *    documentation and/or other materials provided with the distribution.
  40  * 3. All advertising materials mentioning features or use of this software
  41  *    must display the following acknowledgement:
  42  *      This product includes software developed by the University of
  43  *      California, Berkeley and its contributors.
  44  * 4. Neither the name of the University nor the names of its contributors
  45  *    may be used to endorse or promote products derived from this software
  46  *    without specific prior written permission.
  47  *
  48  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  49  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  50  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  51  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  52  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  53  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  54  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  55  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  56  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  57  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  58  * SUCH DAMAGE.
  59  */
  60
  61
  62 #include <sys/types.h>
  63
  64 #include <errno.h>
  65 #include <stdio.h>
  66 #include <string.h>
  67
  68 #include <db.h>
  69 #include "recno.h"
  70
  71 static int rec_rdelete __P((BTREE *, recno_t));
  72
  73 /*
  74  * __REC_DELETE -- Delete the item(s) referenced by a key.
  75  *
  76  * Parameters:
  77  *      dbp:    pointer to access method
  78  *      key:    key to delete
  79  *      flags:  R_CURSOR if deleting what the cursor references
  80  *
  81  * Returns:
  82  *      RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found.
  83  */
  84 int
  85 __rec_delete(dbp, key, flags)
  86         const DB *dbp;
  87         const DBT *key;
  88         u_int flags;
  89 {
  90         BTREE *t;
  91         recno_t nrec;
  92         int status;
  93
  94         t = dbp->internal;
  95
  96         /* Toss any page pinned across calls. */
  97         if (t->bt_pinned != NULL) {
  98                 mpool_put(t->bt_mp, t->bt_pinned, 0);
  99                 t->bt_pinned = NULL;
 100         }
 101
 102         switch(flags) {
 103         case 0:
 104                 if ((nrec = *(recno_t *)key->data) == 0)
 105                         goto einval;
 106                 if (nrec > t->bt_nrecs)
 107                         return (RET_SPECIAL);
 108                 --nrec;
 109                 status = rec_rdelete(t, nrec);
 110                 break;
 111         case R_CURSOR:
 112                 if (!ISSET(t, B_SEQINIT))
 113                         goto einval;
 114                 if (t->bt_nrecs == 0)
 115                         return (RET_SPECIAL);
 116                 status = rec_rdelete(t, t->bt_rcursor - 1);
 117                 if (status == RET_SUCCESS)
 118                         --t->bt_rcursor;
 119                 break;
 120         default:
 121 einval:         errno = EINVAL;
 122                 return (RET_ERROR);
 123         }
 124
 125         if (status == RET_SUCCESS)
 126                 SET(t, B_MODIFIED | R_MODIFIED);
 127         return (status);
 128 }
 129
 130 /*
 131  * REC_RDELETE -- Delete the data matching the specified key.
 132  *
 133  * Parameters:
 134  *      tree:   tree
 135  *      nrec:   record to delete
 136  *
 137  * Returns:
 138  *      RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found.
 139  */
 140 static int
 141 rec_rdelete(t, nrec)
 142         BTREE *t;
 143         recno_t nrec;
 144 {
 145         EPG *e;
 146         PAGE *h;
 147         int status;
 148
 149         /* Find the record; __rec_search pins the page. */
 150         if ((e = __rec_search(t, nrec, SDELETE)) == NULL)
 151                 return (RET_ERROR);
 152
 153         /* Delete the record. */
 154         h = e->page;
 155         status = __rec_dleaf(t, h, e->index);
 156         if (status != RET_SUCCESS) {
 157                 mpool_put(t->bt_mp, h, 0);
 158                 return (status);
 159         }
 160         mpool_put(t->bt_mp, h, MPOOL_DIRTY);
 161         return (RET_SUCCESS);
 162 }
 163
 164 /*
 165  * __REC_DLEAF -- Delete a single record from a recno leaf page.
 166  *
 167  * Parameters:
 168  *      t:      tree
 169  *      index:  index on current page to delete
 170  *
 171  * Returns:
 172  *      RET_SUCCESS, RET_ERROR.
 173  */
 174 int
 175 __rec_dleaf(t, h, index)
 176         BTREE *t;
 177         PAGE *h;
 178         indx_t index;
 179 {
 180         register RLEAF *rl;
 181         register indx_t *ip, cnt, offset;
 182         register size_t nbytes;
 183         char *from;
 184         void *to;
 185
 186         /*
 187          * Delete a record from a recno leaf page.  Internal records are never
 188          * deleted from internal pages, regardless of the records that caused
 189          * them to be added being deleted.  Pages made empty by deletion are
 190          * not reclaimed.  They are, however, made available for reuse.
 191          *
 192          * Pack the remaining entries at the end of the page, shift the indices
 193          * down, overwriting the deleted record and its index.  If the record
 194          * uses overflow pages, make them available for reuse.
 195          */
 196         to = rl = GETRLEAF(h, index);
 197         if (rl->flags & P_BIGDATA && __ovfl_delete(t, rl->bytes) == RET_ERROR)
 198                 return (RET_ERROR);
 199         nbytes = NRLEAF(rl);
 200
 201         /*
 202          * Compress the key/data pairs.  Compress and adjust the [BR]LEAF
 203          * offsets.  Reset the headers.
 204          */
 205         from = (char *)h + h->upper;
 206         memmove(from + nbytes, from, (char *)to - from);
 207         h->upper += nbytes;
 208
 209         offset = h->linp[index];
 210         for (cnt = &h->linp[index] - (ip = &h->linp[0]); cnt--; ++ip)
 211                 if (ip[0] < offset)
 212                         ip[0] += nbytes;
 213         for (cnt = &h->linp[NEXTINDEX(h)] - ip; --cnt; ++ip)
 214                 ip[0] = ip[1] < offset ? ip[1] + nbytes : ip[1];
 215         h->lower -= sizeof(indx_t);
 216         --t->bt_nrecs;
 217         return (RET_SUCCESS);
 218 }