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595 lines
16 KiB
595 lines
16 KiB
3 years ago
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/*-
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* See the file LICENSE for redistribution information.
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*
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* Copyright (c) 1996, 1997, 1998, 1999
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* Sleepycat Software. All rights reserved.
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*/
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/*
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* Copyright (c) 1990, 1993, 1994, 1995, 1996
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* Keith Bostic. All rights reserved.
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*/
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/*
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* Copyright (c) 1990, 1993, 1994, 1995
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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. 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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#include "db_config.h"
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#ifndef lint
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static const char sccsid[] = "@(#)bt_delete.c 11.6 (Sleepycat) 9/9/99";
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#endif /* not lint */
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#ifndef NO_SYSTEM_INCLUDES
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#include <sys/types.h>
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#include <string.h>
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#endif
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#include "db_int.h"
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#include "db_page.h"
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#include "db_shash.h"
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#include "btree.h"
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#include "lock.h"
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/*
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* CDB___bam_delete --
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* Delete the items referenced by a key.
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*
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* PUBLIC: int CDB___bam_delete __P((DB *, DB_TXN *, DBT *, u_int32_t));
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*/
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int
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CDB___bam_delete(dbp, txn, key, flags)
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DB *dbp;
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DB_TXN *txn;
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DBT *key;
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u_int32_t flags;
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{
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DBC *dbc;
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DBT lkey;
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DBT data;
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u_int32_t f_init, f_next;
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int ret, t_ret;
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PANIC_CHECK(dbp->dbenv);
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DB_ILLEGAL_BEFORE_OPEN(dbp, "DB->del");
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/* Check for invalid flags. */
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if ((ret =
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CDB___db_delchk(dbp, key, flags, F_ISSET(dbp, DB_AM_RDONLY))) != 0)
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return (ret);
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/* Allocate a cursor. */
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if ((ret = dbp->cursor(dbp, txn, &dbc, DB_WRITELOCK)) != 0)
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return (ret);
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DEBUG_LWRITE(dbc, txn, "bam_delete", key, NULL, flags);
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/*
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* Walk a cursor through the key/data pairs, deleting as we go. Set
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* the DB_DBT_USERMEM flag, as this might be a threaded application
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* and the flags checking will catch us. We don't actually want the
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* keys or data, so request a partial of length 0.
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*/
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memset(&lkey, 0, sizeof(lkey));
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F_SET(&lkey, DB_DBT_USERMEM | DB_DBT_PARTIAL);
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memset(&data, 0, sizeof(data));
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F_SET(&data, DB_DBT_USERMEM | DB_DBT_PARTIAL);
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/* If locking, set read-modify-write flag. */
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f_init = DB_SET;
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f_next = DB_NEXT_DUP;
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if (F_ISSET(dbp->dbenv, DB_ENV_LOCKING)) {
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f_init |= DB_RMW;
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f_next |= DB_RMW;
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}
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/* Walk through the set of key/data pairs, deleting as we go. */
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if ((ret = dbc->c_get(dbc, key, &data, f_init)) != 0)
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goto err;
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for (;;) {
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if ((ret = dbc->c_del(dbc, 0)) != 0)
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goto err;
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if ((ret = dbc->c_get(dbc, &lkey, &data, f_next)) != 0) {
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if (ret == DB_NOTFOUND) {
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ret = 0;
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break;
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}
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goto err;
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}
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}
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err: /* Discard the cursor. */
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if ((t_ret = dbc->c_close(dbc)) != 0 && ret == 0)
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ret = t_ret;
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return (ret);
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}
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/*
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* CDB___bam_ditem --
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* Delete one or more entries from a page.
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*
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* PUBLIC: int CDB___bam_ditem __P((DBC *, PAGE *, u_int32_t));
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*/
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int
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CDB___bam_ditem(dbc, h, indx)
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DBC *dbc;
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PAGE *h;
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u_int32_t indx;
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{
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BINTERNAL *bi;
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BKEYDATA *bk;
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BOVERFLOW *bo;
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DB *dbp;
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u_int32_t nbytes;
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int ret;
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dbp = dbc->dbp;
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switch (TYPE(h)) {
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case P_IBTREE:
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bi = GET_BINTERNAL(h, indx);
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switch (B_TYPE(bi->type)) {
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case B_DUPLICATE:
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case B_OVERFLOW:
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nbytes = BINTERNAL_SIZE(bi->len);
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bo = (BOVERFLOW *)bi->data;
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goto offpage;
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case B_KEYDATA:
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nbytes = BINTERNAL_SIZE(bi->len);
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break;
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default:
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return (CDB___db_pgfmt(dbp, h->pgno));
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}
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break;
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case P_IRECNO:
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nbytes = RINTERNAL_SIZE;
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break;
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case P_LBTREE:
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/*
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* If it's a duplicate key, discard the index and don't touch
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* the actual page item.
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*
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* XXX
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* This works because no data item can have an index matching
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* any other index so even if the data item is in a key "slot",
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* it won't match any other index.
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*/
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if ((indx % 2) == 0) {
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/*
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* Check for a duplicate after us on the page. NOTE:
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* we have to delete the key item before deleting the
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* data item, otherwise the "indx + P_INDX" calculation
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* won't work!
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*/
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if (indx + P_INDX < (u_int32_t)NUM_ENT(h) &&
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h->inp[indx] == h->inp[indx + P_INDX])
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return (CDB___bam_adjindx(dbc,
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h, indx, indx + O_INDX, 0));
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/*
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* Check for a duplicate before us on the page. It
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* doesn't matter if we delete the key item before or
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* after the data item for the purposes of this one.
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*/
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if (indx > 0 && h->inp[indx] == h->inp[indx - P_INDX])
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return (CDB___bam_adjindx(dbc,
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h, indx, indx - P_INDX, 0));
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}
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/* FALLTHROUGH */
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case P_LRECNO:
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bk = GET_BKEYDATA(h, indx);
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switch (B_TYPE(bk->type)) {
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case B_DUPLICATE:
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case B_OVERFLOW:
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nbytes = BOVERFLOW_SIZE;
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bo = GET_BOVERFLOW(h, indx);
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offpage: /* Delete duplicate/offpage chains. */
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if (B_TYPE(bo->type) == B_DUPLICATE) {
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if ((ret =
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CDB___db_ddup(dbc, bo->pgno)) != 0)
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return (ret);
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} else
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if ((ret =
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CDB___db_doff(dbc, bo->pgno)) != 0)
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return (ret);
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break;
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case B_KEYDATA:
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nbytes = BKEYDATA_SIZE(bk->len);
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break;
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default:
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return (CDB___db_pgfmt(dbp, h->pgno));
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}
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break;
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default:
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return (CDB___db_pgfmt(dbp, h->pgno));
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}
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/* Delete the item and update the cursors. */
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if ((ret = CDB___db_ditem(dbc, h, indx, nbytes)) != 0)
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return (ret);
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CDB___bam_ca_di(dbp, PGNO(h), indx, -1);
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/* Mark the page dirty. */
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return (CDB_memp_fset(dbp->mpf, h, DB_MPOOL_DIRTY));
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}
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/*
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* CDB___bam_adjindx --
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* Adjust an index on the page.
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*
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* PUBLIC: int CDB___bam_adjindx __P((DBC *, PAGE *, u_int32_t, u_int32_t, int));
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*/
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int
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CDB___bam_adjindx(dbc, h, indx, indx_copy, is_insert)
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DBC *dbc;
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PAGE *h;
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u_int32_t indx, indx_copy;
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int is_insert;
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{
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DB *dbp;
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db_indx_t copy;
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int ret;
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dbp = dbc->dbp;
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/* Log the change. */
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if (DB_LOGGING(dbc) &&
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(ret = CDB___bam_adj_log(dbp->dbenv, dbc->txn, &LSN(h),
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0, dbp->log_fileid, PGNO(h), &LSN(h), indx, indx_copy,
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(u_int32_t)is_insert)) != 0)
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return (ret);
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if (is_insert) {
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copy = h->inp[indx_copy];
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if (indx != NUM_ENT(h))
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memmove(&h->inp[indx + O_INDX], &h->inp[indx],
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sizeof(db_indx_t) * (NUM_ENT(h) - indx));
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h->inp[indx] = copy;
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++NUM_ENT(h);
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} else {
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--NUM_ENT(h);
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if (indx != NUM_ENT(h))
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memmove(&h->inp[indx], &h->inp[indx + O_INDX],
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sizeof(db_indx_t) * (NUM_ENT(h) - indx));
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}
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/* Mark the page dirty. */
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ret = CDB_memp_fset(dbp->mpf, h, DB_MPOOL_DIRTY);
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/* Adjust the cursors. */
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CDB___bam_ca_di(dbp, h->pgno, indx, is_insert ? 1 : -1);
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return (0);
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}
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/*
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* CDB___bam_dpage --
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* Delete a page from the tree.
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*
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* PUBLIC: int CDB___bam_dpage __P((DBC *, const DBT *));
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*/
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int
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CDB___bam_dpage(dbc, key)
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DBC *dbc;
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const DBT *key;
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{
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BTREE_CURSOR *cp;
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DB *dbp;
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DB_LOCK lock;
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PAGE *h;
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db_pgno_t pgno, root_pgno;
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int level; /* !!!: has to hold number of tree levels. */
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int exact, ret;
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dbp = dbc->dbp;
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cp = dbc->internal;
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ret = 0;
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/*
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* The locking protocol is that we acquire locks by walking down the
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* tree, to avoid the obvious deadlocks.
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*
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* Call CDB___bam_search to reacquire the empty leaf page, but this time
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* get both the leaf page and it's parent, locked. Walk back up the
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* tree, until we have the top pair of pages that we want to delete.
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* Once we have the top page that we want to delete locked, lock the
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* underlying pages and check to make sure they're still empty. If
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* they are, delete them.
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*/
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root_pgno = ((BTREE *)dbp->bt_internal)->bt_root;
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for (level = LEAFLEVEL;; ++level) {
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/* Acquire a page and its parent, locked. */
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if ((ret =
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CDB___bam_search(dbc, key, S_WRPAIR, level, NULL, &exact)) != 0)
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return (ret);
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/*
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* If we reach the root or the page isn't going to be empty
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* when we delete one record, quit.
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*/
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h = cp->csp[-1].page;
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if (h->pgno == root_pgno || NUM_ENT(h) != 1)
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break;
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/* Release the two locked pages. */
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(void)CDB_memp_fput(dbp->mpf, cp->csp[-1].page, 0);
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(void)__TLPUT(dbc, cp->csp[-1].lock);
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(void)CDB_memp_fput(dbp->mpf, cp->csp[0].page, 0);
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(void)__TLPUT(dbc, cp->csp[0].lock);
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}
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/*
|
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* Leave the stack pointer one after the last entry, we may be about
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* to push more items on the stack.
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*/
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++cp->csp;
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|
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/*
|
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|
* cp->csp[-2].page is the top page, which we're not going to delete,
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* and cp->csp[-1].page is the first page we are going to delete.
|
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|
*
|
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|
* Walk down the chain, acquiring the rest of the pages until we've
|
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* retrieved the leaf page. If we find any pages that aren't going
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* to be emptied by the delete, someone else added something while we
|
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|
* were walking the tree, and we discontinue the delete.
|
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|
*/
|
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for (h = cp->csp[-1].page;;) {
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|
if (ISLEAF(h)) {
|
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|
if (NUM_ENT(h) != 0)
|
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|
goto release;
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|
break;
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|
} else
|
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|
if (NUM_ENT(h) != 1)
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|
goto release;
|
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|
|
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|
/*
|
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|
* Get the next page, write lock it and push it onto the stack.
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* We know it's index 0, because it can only have one element.
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*/
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pgno = TYPE(h) == P_IBTREE ?
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GET_BINTERNAL(h, 0)->pgno : GET_RINTERNAL(h, 0)->pgno;
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|
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|
if ((ret =
|
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|
CDB___db_lget(dbc, 0, pgno, DB_LOCK_WRITE, 0, &lock)) != 0)
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goto release;
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|
if ((ret = CDB_memp_fget(dbp->mpf, &pgno, 0, &h)) != 0)
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goto release;
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BT_STK_PUSH(cp, h, 0, lock, DB_LOCK_WRITE, ret);
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}
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/* Adjust back to reference the last page on the stack. */
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BT_STK_POP(cp);
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/* Delete the pages. */
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return (CDB___bam_dpages(dbc));
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|
release:
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/* Adjust back to reference the last page on the stack. */
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BT_STK_POP(cp);
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/* Discard any locked pages and return. */
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CDB___bam_stkrel(dbc, 0);
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return (ret);
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}
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/*
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* CDB___bam_dpages --
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* Delete a set of locked pages.
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*
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* PUBLIC: int CDB___bam_dpages __P((DBC *));
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|
*/
|
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|
int
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CDB___bam_dpages(dbc)
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DBC *dbc;
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|
{
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BTREE_CURSOR *cp;
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DB *dbp;
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DBT a, b;
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DB_LOCK c_lock, p_lock;
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EPG *epg;
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PAGE *child, *parent;
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||
|
db_indx_t nitems;
|
||
|
db_pgno_t pgno, root_pgno;
|
||
|
db_recno_t rcnt;
|
||
|
int done, ret;
|
||
|
|
||
|
dbp = dbc->dbp;
|
||
|
cp = dbc->internal;
|
||
|
root_pgno = ((BTREE *)dbp->bt_internal)->bt_root;
|
||
|
epg = cp->sp;
|
||
|
|
||
|
/*
|
||
|
* !!!
|
||
|
* There is an interesting deadlock situation here. We have to relink
|
||
|
* the leaf page chain around the leaf page being deleted. Consider
|
||
|
* a cursor walking through the leaf pages, that has the previous page
|
||
|
* read-locked and is waiting on a lock for the page we're deleting.
|
||
|
* It will deadlock here. This is a problem, because if our process is
|
||
|
* selected to resolve the deadlock, we'll leave an empty leaf page
|
||
|
* that we can never again access by walking down the tree. So, before
|
||
|
* we unlink the subtree, we relink the leaf page chain.
|
||
|
*/
|
||
|
if ((ret = CDB___db_relink(dbc, DB_REM_PAGE, cp->csp->page, NULL, 1)) != 0)
|
||
|
goto release;
|
||
|
|
||
|
/*
|
||
|
* We have the entire stack of deletable pages locked.
|
||
|
*
|
||
|
* Delete the highest page in the tree's reference to the underlying
|
||
|
* stack of pages. Then, release that page, letting the rest of the
|
||
|
* tree get back to business.
|
||
|
*/
|
||
|
if ((ret = CDB___bam_ditem(dbc, epg->page, epg->indx)) != 0) {
|
||
|
release: (void)CDB___bam_stkrel(dbc, 0);
|
||
|
return (ret);
|
||
|
}
|
||
|
|
||
|
pgno = epg->page->pgno;
|
||
|
nitems = NUM_ENT(epg->page);
|
||
|
|
||
|
(void)CDB_memp_fput(dbp->mpf, epg->page, 0);
|
||
|
(void)__TLPUT(dbc, epg->lock);
|
||
|
|
||
|
/*
|
||
|
* Free the rest of the stack of pages.
|
||
|
*
|
||
|
* !!!
|
||
|
* Don't bother checking for errors. We've unlinked the subtree from
|
||
|
* the tree, and there's no possibility of recovery outside of doing
|
||
|
* TXN rollback.
|
||
|
*/
|
||
|
while (++epg <= cp->csp) {
|
||
|
/*
|
||
|
* Delete page entries so they will be restored as part of
|
||
|
* recovery.
|
||
|
*/
|
||
|
if (NUM_ENT(epg->page) != 0)
|
||
|
(void)CDB___bam_ditem(dbc, epg->page, epg->indx);
|
||
|
|
||
|
(void)CDB___db_free(dbc, epg->page);
|
||
|
(void)__TLPUT(dbc, epg->lock);
|
||
|
}
|
||
|
BT_STK_CLR(cp);
|
||
|
|
||
|
/*
|
||
|
* Try and collapse the tree a level -- this is only applicable
|
||
|
* if we've deleted the next-to-last element from the root page.
|
||
|
*
|
||
|
* There are two cases when collapsing a tree.
|
||
|
*
|
||
|
* If we've just deleted the last item from the root page, there is no
|
||
|
* further work to be done. The code above has emptied the root page
|
||
|
* and freed all pages below it.
|
||
|
*/
|
||
|
if (pgno != root_pgno || nitems != 1)
|
||
|
return (0);
|
||
|
|
||
|
/*
|
||
|
* If we just deleted the next-to-last item from the root page, the
|
||
|
* tree can collapse one or more levels. While there remains only a
|
||
|
* single item on the root page, write lock the last page referenced
|
||
|
* by the root page and copy it over the root page. If we can't get a
|
||
|
* write lock, that's okay, the tree just stays deeper than we'd like.
|
||
|
*/
|
||
|
for (done = 0; !done;) {
|
||
|
/* Initialize. */
|
||
|
parent = child = NULL;
|
||
|
p_lock.off = c_lock.off = LOCK_INVALID;
|
||
|
|
||
|
/* Lock the root. */
|
||
|
pgno = root_pgno;
|
||
|
if ((ret =
|
||
|
CDB___db_lget(dbc, 0, pgno, DB_LOCK_WRITE, 0, &p_lock)) != 0)
|
||
|
goto stop;
|
||
|
if ((ret = CDB_memp_fget(dbp->mpf, &pgno, 0, &parent)) != 0)
|
||
|
goto stop;
|
||
|
|
||
|
if (NUM_ENT(parent) != 1 ||
|
||
|
(TYPE(parent) != P_IBTREE && TYPE(parent) != P_IRECNO))
|
||
|
goto stop;
|
||
|
|
||
|
pgno = TYPE(parent) == P_IBTREE ?
|
||
|
GET_BINTERNAL(parent, 0)->pgno :
|
||
|
GET_RINTERNAL(parent, 0)->pgno;
|
||
|
|
||
|
/* Lock the child page. */
|
||
|
if ((ret =
|
||
|
CDB___db_lget(dbc, 0, pgno, DB_LOCK_WRITE, 0, &c_lock)) != 0)
|
||
|
goto stop;
|
||
|
if ((ret = CDB_memp_fget(dbp->mpf, &pgno, 0, &child)) != 0)
|
||
|
goto stop;
|
||
|
|
||
|
/* Log the change. */
|
||
|
if (DB_LOGGING(dbc)) {
|
||
|
memset(&a, 0, sizeof(a));
|
||
|
a.data = child;
|
||
|
a.size = dbp->pgsize;
|
||
|
memset(&b, 0, sizeof(b));
|
||
|
b.data = P_ENTRY(parent, 0);
|
||
|
b.size = BINTERNAL_SIZE(((BINTERNAL *)b.data)->len);
|
||
|
CDB___bam_rsplit_log(dbp->dbenv, dbc->txn,
|
||
|
&child->lsn, 0, dbp->log_fileid, child->pgno, &a,
|
||
|
RE_NREC(parent), &b, &parent->lsn);
|
||
|
}
|
||
|
|
||
|
/*
|
||
|
* Make the switch.
|
||
|
*
|
||
|
* One fixup -- if the tree has record numbers and we're not
|
||
|
* converting to a leaf page, we have to preserve the total
|
||
|
* record count. Note that we are about to overwrite everything
|
||
|
* on the parent, including its LSN. This is actually OK,
|
||
|
* because the above log message, which describes this update,
|
||
|
* stores its LSN on the child page. When the child is copied
|
||
|
* to the parent, the correct LSN is going to copied into
|
||
|
* place in the parent.
|
||
|
*/
|
||
|
COMPQUIET(rcnt, 0);
|
||
|
if (TYPE(child) == P_IRECNO ||
|
||
|
(TYPE(child) == P_IBTREE && F_ISSET(dbp, DB_BT_RECNUM)))
|
||
|
rcnt = RE_NREC(parent);
|
||
|
memcpy(parent, child, dbp->pgsize);
|
||
|
parent->pgno = root_pgno;
|
||
|
if (TYPE(child) == P_IRECNO ||
|
||
|
(TYPE(child) == P_IBTREE && F_ISSET(dbp, DB_BT_RECNUM)))
|
||
|
RE_NREC_SET(parent, rcnt);
|
||
|
|
||
|
/* Mark the pages dirty. */
|
||
|
CDB_memp_fset(dbp->mpf, parent, DB_MPOOL_DIRTY);
|
||
|
CDB_memp_fset(dbp->mpf, child, DB_MPOOL_DIRTY);
|
||
|
|
||
|
/* Adjust the cursors. */
|
||
|
CDB___bam_ca_rsplit(dbp, child->pgno, root_pgno);
|
||
|
|
||
|
/*
|
||
|
* Free the page copied onto the root page and discard its
|
||
|
* lock. (The call to CDB___db_free() discards our reference
|
||
|
* to the page.)
|
||
|
*/
|
||
|
(void)CDB___db_free(dbc, child);
|
||
|
child = NULL;
|
||
|
|
||
|
if (0) {
|
||
|
stop: done = 1;
|
||
|
}
|
||
|
if (p_lock.off != LOCK_INVALID)
|
||
|
(void)__TLPUT(dbc, p_lock);
|
||
|
if (parent != NULL)
|
||
|
CDB_memp_fput(dbp->mpf, parent, 0);
|
||
|
if (c_lock.off != LOCK_INVALID)
|
||
|
(void)__TLPUT(dbc, c_lock);
|
||
|
if (child != NULL)
|
||
|
CDB_memp_fput(dbp->mpf, child, 0);
|
||
|
}
|
||
|
|
||
|
return (0);
|
||
|
}
|