325 lines
9.1 KiB
C
325 lines
9.1 KiB
C
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/*-
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* Copyright (c) 1990, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Mike Olson.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#if defined(LIBC_SCCS) && !defined(lint)
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static char sccsid[] = "@(#)bt_delete.c 8.3 (Berkeley) 2/21/94";
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#endif /* LIBC_SCCS and not lint */
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#include <sys/types.h>
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#include <errno.h>
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#include <stdio.h>
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#include <string.h>
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#include <db.h>
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#include "btree.h"
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static int bt_bdelete __P((BTREE *, const DBT *));
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/*
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* __BT_DELETE -- Delete the item(s) referenced by a key.
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*
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* Parameters:
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* dbp: pointer to access method
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* key: key to delete
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* flags: R_CURSOR if deleting what the cursor references
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*
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* Returns:
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* RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found.
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*/
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int
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__bt_delete(dbp, key, flags)
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const DB *dbp;
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const DBT *key;
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u_int flags;
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{
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BTREE *t;
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int status;
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t = dbp->internal;
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/* Toss any page pinned across calls. */
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if (t->bt_pinned != NULL) {
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mpool_put(t->bt_mp, t->bt_pinned, 0);
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t->bt_pinned = NULL;
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}
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if (ISSET(t, B_RDONLY)) {
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errno = EPERM;
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return (RET_ERROR);
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}
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switch(flags) {
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case 0:
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status = bt_bdelete(t, key);
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break;
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case R_CURSOR:
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/*
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* If flags is R_CURSOR, delete the cursor; must already have
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* started a scan and not have already deleted the record. For
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* the delete cursor bit to have been set requires that the
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* scan be initialized, so no reason to check.
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*/
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if (!ISSET(t, B_SEQINIT))
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goto einval;
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status = ISSET(t, B_DELCRSR) ?
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RET_SPECIAL : __bt_crsrdel(t, &t->bt_bcursor);
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break;
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default:
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einval: errno = EINVAL;
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return (RET_ERROR);
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}
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if (status == RET_SUCCESS)
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SET(t, B_MODIFIED);
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return (status);
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}
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/*
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* BT_BDELETE -- Delete all key/data pairs matching the specified key.
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*
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* Parameters:
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* tree: tree
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* key: key to delete
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*
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* Returns:
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* RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found.
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*/
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static int
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bt_bdelete(t, key)
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BTREE *t;
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const DBT *key;
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{
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EPG *e, save;
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PAGE *h;
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pgno_t cpgno, pg;
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indx_t cindex;
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int deleted, dirty1, dirty2, exact;
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/* Find any matching record; __bt_search pins the page. */
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if ((e = __bt_search(t, key, &exact)) == NULL)
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return (RET_ERROR);
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if (!exact) {
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mpool_put(t->bt_mp, e->page, 0);
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return (RET_SPECIAL);
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}
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/*
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* Delete forward, then delete backward, from the found key. The
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* ordering is so that the deletions don't mess up the page refs.
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* The first loop deletes the key from the original page, the second
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* unpins the original page. In the first loop, dirty1 is set if
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* the original page is modified, and dirty2 is set if any subsequent
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* pages are modified. In the second loop, dirty1 starts off set if
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* the original page has been modified, and is set if any subsequent
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* pages are modified.
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*
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* If find the key referenced by the cursor, don't delete it, just
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* flag it for future deletion. The cursor page number is P_INVALID
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* unless the sequential scan is initialized, so no reason to check.
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* A special case is when the already deleted cursor record was the
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* only record found. If so, then the delete opertion fails as no
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* records were deleted.
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*
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* Cycle in place in the current page until the current record doesn't
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* match the key or the page is empty. If the latter, walk forward,
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* skipping empty pages and repeating until a record doesn't match
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* the key or the end of the tree is reached.
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*/
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cpgno = t->bt_bcursor.pgno;
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cindex = t->bt_bcursor.index;
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save = *e;
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dirty1 = 0;
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for (h = e->page, deleted = 0;;) {
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dirty2 = 0;
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do {
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if (h->pgno == cpgno && e->index == cindex) {
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if (!ISSET(t, B_DELCRSR)) {
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SET(t, B_DELCRSR);
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deleted = 1;
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}
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++e->index;
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} else {
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if (__bt_dleaf(t, h, e->index)) {
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if (h->pgno != save.page->pgno)
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mpool_put(t->bt_mp, h, dirty2);
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mpool_put(t->bt_mp, save.page, dirty1);
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return (RET_ERROR);
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}
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if (h->pgno == save.page->pgno)
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dirty1 = MPOOL_DIRTY;
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else
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dirty2 = MPOOL_DIRTY;
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deleted = 1;
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}
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} while (e->index < NEXTINDEX(h) && __bt_cmp(t, key, e) == 0);
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/*
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* Quit if didn't find a match, no next page, or first key on
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* the next page doesn't match. Don't unpin the original page
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* unless an error occurs.
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*/
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if (e->index < NEXTINDEX(h))
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break;
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for (;;) {
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if ((pg = h->nextpg) == P_INVALID)
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goto done1;
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if (h->pgno != save.page->pgno)
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mpool_put(t->bt_mp, h, dirty2);
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if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) {
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mpool_put(t->bt_mp, save.page, dirty1);
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return (RET_ERROR);
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}
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if (NEXTINDEX(h) != 0) {
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e->page = h;
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e->index = 0;
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break;
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}
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}
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if (__bt_cmp(t, key, e) != 0)
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break;
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}
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/*
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* Reach here with the original page and the last page referenced
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* pinned (they may be the same). Release it if not the original.
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*/
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done1: if (h->pgno != save.page->pgno)
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mpool_put(t->bt_mp, h, dirty2);
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/*
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* Walk backwards from the record previous to the record returned by
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* __bt_search, skipping empty pages, until a record doesn't match
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* the key or reach the beginning of the tree.
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*/
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*e = save;
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for (;;) {
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if (e->index)
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--e->index;
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for (h = e->page; e->index; --e->index) {
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if (__bt_cmp(t, key, e) != 0)
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goto done2;
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if (h->pgno == cpgno && e->index == cindex) {
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if (!ISSET(t, B_DELCRSR)) {
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SET(t, B_DELCRSR);
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deleted = 1;
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}
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} else {
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if (__bt_dleaf(t, h, e->index) == RET_ERROR) {
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mpool_put(t->bt_mp, h, dirty1);
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return (RET_ERROR);
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}
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if (h->pgno == save.page->pgno)
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dirty1 = MPOOL_DIRTY;
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deleted = 1;
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}
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}
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if ((pg = h->prevpg) == P_INVALID)
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goto done2;
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mpool_put(t->bt_mp, h, dirty1);
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dirty1 = 0;
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if ((e->page = mpool_get(t->bt_mp, pg, 0)) == NULL)
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return (RET_ERROR);
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e->index = NEXTINDEX(e->page);
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}
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/*
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* Reach here with the last page that was looked at pinned. Release
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* it.
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*/
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done2: mpool_put(t->bt_mp, h, dirty1);
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return (deleted ? RET_SUCCESS : RET_SPECIAL);
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}
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/*
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* __BT_DLEAF -- Delete a single record from a leaf page.
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*
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* Parameters:
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* t: tree
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* index: index on current page to delete
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*
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* Returns:
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* RET_SUCCESS, RET_ERROR.
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*/
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int
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__bt_dleaf(t, h, index)
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BTREE *t;
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PAGE *h;
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indx_t index;
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{
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register BLEAF *bl;
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register indx_t cnt, *ip, offset;
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register size_t nbytes;
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char *from;
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void *to;
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/*
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* Delete a record from a btree leaf page. Internal records are never
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* deleted from internal pages, regardless of the records that caused
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* them to be added being deleted. Pages made empty by deletion are
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* not reclaimed. They are, however, made available for reuse.
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*
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* Pack the remaining entries at the end of the page, shift the indices
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* down, overwriting the deleted record and its index. If the record
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* uses overflow pages, make them available for reuse.
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*/
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to = bl = GETBLEAF(h, index);
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if (bl->flags & P_BIGKEY && __ovfl_delete(t, bl->bytes) == RET_ERROR)
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return (RET_ERROR);
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if (bl->flags & P_BIGDATA &&
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__ovfl_delete(t, bl->bytes + bl->ksize) == RET_ERROR)
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return (RET_ERROR);
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nbytes = NBLEAF(bl);
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/*
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* Compress the key/data pairs. Compress and adjust the [BR]LEAF
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* offsets. Reset the headers.
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*/
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from = (char *)h + h->upper;
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memmove(from + nbytes, from, (char *)to - from);
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h->upper += nbytes;
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offset = h->linp[index];
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for (cnt = index, ip = &h->linp[0]; cnt--; ++ip)
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if (ip[0] < offset)
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ip[0] += nbytes;
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for (cnt = NEXTINDEX(h) - index; --cnt; ++ip)
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ip[0] = ip[1] < offset ? ip[1] + nbytes : ip[1];
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h->lower -= sizeof(indx_t);
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return (RET_SUCCESS);
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}
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