rec_delete.c revision 14272 
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)
38static char sccsid[] = "@(#)rec_delete.c	8.7 (Berkeley) 7/14/94";
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
50static 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 */
63int
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 (!F_ISSET(&t->bt_cursor, CURS_INIT))
92			goto einval;
93		if (t->bt_nrecs == 0)
94			return (RET_SPECIAL);
95		status = rec_rdelete(t, t->bt_cursor.rcursor - 1);
96		if (status == RET_SUCCESS)
97			--t->bt_cursor.rcursor;
98		break;
99	default:
100einval:		errno = EINVAL;
101		return (RET_ERROR);
102	}
103
104	if (status == RET_SUCCESS)
105		F_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 */
119static int
120rec_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 */
153int
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