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390 lines
11 KiB
390 lines
11 KiB
/*-
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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_search.c 11.8 (Sleepycat) 10/21/99";
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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_search --
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* Search a btree for a key.
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*
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* PUBLIC: int CDB___bam_search __P((DBC *,
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* PUBLIC: const DBT *, u_int32_t, int, db_recno_t *, int *));
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*/
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int
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CDB___bam_search(dbc, key, flags, stop, recnop, exactp)
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DBC *dbc;
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const DBT *key;
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u_int32_t flags;
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int stop, *exactp;
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db_recno_t *recnop;
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{
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BTREE *t;
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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_indx_t base, i, indx, lim;
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db_lockmode_t lock_mode;
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db_pgno_t pg;
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db_recno_t recno;
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int cmp, jump, ret, stack;
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dbp = dbc->dbp;
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cp = dbc->internal;
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t = dbp->bt_internal;
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recno = 0;
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BT_STK_CLR(cp);
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/*
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* There are several ways we search a btree tree. The flags argument
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* specifies if we're acquiring read or write locks, if we position
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* to the first or last item in a set of duplicates, if we return
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* deleted items, and if we are locking pairs of pages. In addition,
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* if we're modifying record numbers, we have to lock the entire tree
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* regardless. See btree.h for more details.
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*
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* If write-locking pages, we need to know whether or not to acquire a
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* write lock on a page before getting it. This depends on how deep it
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* is in tree, which we don't know until we acquire the root page. So,
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* if we need to lock the root page we may have to upgrade it later,
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* because we won't get the correct lock initially.
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*
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* Retrieve the root page.
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*/
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pg = ((BTREE *)dbp->bt_internal)->bt_root;
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stack = F_ISSET(dbp, DB_BT_RECNUM) && LF_ISSET(S_STACK);
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lock_mode = stack ? DB_LOCK_WRITE : DB_LOCK_READ;
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if ((ret = CDB___db_lget(dbc, 0, pg, lock_mode, 0, &lock)) != 0)
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return (ret);
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if ((ret = CDB_memp_fget(dbp->mpf, &pg, 0, &h)) != 0) {
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/* Did not read it, so we can release the lock */
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(void)__LPUT(dbc, lock);
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return (ret);
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}
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/*
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* Decide if we need to save this page; if we do, write lock it.
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* We deliberately don't lock-couple on this call. If the tree
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* is tiny, i.e., one page, and two threads are busily updating
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* the root page, we're almost guaranteed deadlocks galore, as
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* each one gets a read lock and then blocks the other's attempt
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* for a write lock.
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*/
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if (!stack &&
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((LF_ISSET(S_PARENT) && (u_int8_t)(stop + 1) >= h->level) ||
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(LF_ISSET(S_WRITE) && h->level == LEAFLEVEL))) {
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(void)CDB_memp_fput(dbp->mpf, h, 0);
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(void)__LPUT(dbc, lock);
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lock_mode = DB_LOCK_WRITE;
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if ((ret = CDB___db_lget(dbc, 0, pg, lock_mode, 0, &lock)) != 0)
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return (ret);
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if ((ret = CDB_memp_fget(dbp->mpf, &pg, 0, &h)) != 0) {
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/* Did not read it, so we can release the lock */
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(void)__LPUT(dbc, lock);
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return (ret);
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}
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stack = 1;
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}
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for (;;) {
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/*
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* Do a binary search on the current page. If we're searching
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* a leaf page, we have to manipulate the indices in groups of
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* two. If we're searching an internal page, they're an index
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* per page item. If we find an exact match on a leaf page,
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* we're done.
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*/
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jump = TYPE(h) == P_LBTREE ? P_INDX : O_INDX;
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for (base = 0,
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lim = NUM_ENT(h) / (db_indx_t)jump; lim != 0; lim >>= 1) {
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indx = base + ((lim >> 1) * jump);
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if ((cmp = CDB___bam_cmp(dbp,
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key, h, indx, t->bt_compare)) == 0) {
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if (TYPE(h) == P_LBTREE)
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goto match;
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goto next;
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}
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if (cmp > 0) {
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base = indx + jump;
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--lim;
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}
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}
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/*
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* No match found. Base is the smallest index greater than
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* key and may be zero or a last + O_INDX index.
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*
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* If it's a leaf page, return base as the "found" value.
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* Delete only deletes exact matches.
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*/
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if (TYPE(h) == P_LBTREE) {
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*exactp = 0;
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if (LF_ISSET(S_EXACT))
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goto notfound;
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/*
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* !!!
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* Possibly returning a deleted record -- DB_SET_RANGE,
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* DB_KEYFIRST and DB_KEYLAST don't require an exact
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* match, and we don't want to walk multiple pages here
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* to find an undeleted record. This is handled by the
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* calling routine.
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*/
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BT_STK_ENTER(cp, h, base, lock, lock_mode, ret);
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return (ret);
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}
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/*
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* If it's not a leaf page, record the internal page (which is
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* a parent page for the key). Decrement the base by 1 if it's
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* non-zero so that if a split later occurs, the inserted page
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* will be to the right of the saved page.
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*/
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indx = base > 0 ? base - O_INDX : base;
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/*
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* If we're trying to calculate the record number, sum up
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* all the record numbers on this page up to the indx point.
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*/
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next: if (recnop != NULL)
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for (i = 0; i < indx; ++i)
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recno += GET_BINTERNAL(h, i)->nrecs;
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pg = GET_BINTERNAL(h, indx)->pgno;
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if (stack) {
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/* Return if this is the lowest page wanted. */
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if (LF_ISSET(S_PARENT) && stop == h->level) {
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BT_STK_ENTER(cp, h, indx, lock, lock_mode, ret);
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return (ret);
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}
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BT_STK_PUSH(cp, h, indx, lock, lock_mode, ret);
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if (ret != 0)
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goto err;
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lock_mode = DB_LOCK_WRITE;
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if ((ret =
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CDB___db_lget(dbc, 0, pg, lock_mode, 0, &lock)) != 0)
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goto err;
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} else {
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/*
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* Decide if we want to return a reference to the next
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* page in the return stack. If so, lock it and never
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* unlock it.
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*/
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if ((LF_ISSET(S_PARENT) &&
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(u_int8_t)(stop + 1) >= (u_int8_t)(h->level - 1)) ||
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(h->level - 1) == LEAFLEVEL)
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stack = 1;
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(void)CDB_memp_fput(dbp->mpf, h, 0);
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lock_mode = stack &&
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LF_ISSET(S_WRITE) ? DB_LOCK_WRITE : DB_LOCK_READ;
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if ((ret =
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CDB___db_lget(dbc, 1, pg, lock_mode, 0, &lock)) != 0) {
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/*
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* If we fail, discard the lock we held. This
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* is OK because this only happens when we are
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* descending the tree holding read-locks.
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*/
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__LPUT(dbc, lock);
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goto err;
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}
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}
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if ((ret = CDB_memp_fget(dbp->mpf, &pg, 0, &h)) != 0)
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goto err;
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}
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/* NOTREACHED */
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match: *exactp = 1;
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/*
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* If we're trying to calculate the record number, add in the
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* offset on this page and correct for the fact that records
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* in the tree are 0-based.
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*/
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if (recnop != NULL)
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*recnop = recno + (indx / P_INDX) + 1;
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/*
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* If we got here, we know that we have a btree leaf page.
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*
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* If there are duplicates, go to the first/last one. This is
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* safe because we know that we're not going to leave the page,
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* all duplicate sets that are not on overflow pages exist on a
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* single leaf page.
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*/
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if (LF_ISSET(S_DUPLAST))
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while (indx < (db_indx_t)(NUM_ENT(h) - P_INDX) &&
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h->inp[indx] == h->inp[indx + P_INDX])
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indx += P_INDX;
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else
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while (indx > 0 &&
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h->inp[indx] == h->inp[indx - P_INDX])
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indx -= P_INDX;
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/*
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* Now check if we are allowed to return deleted items; if not, then
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* find the next (or previous) non-deleted duplicate entry. (We do
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* not move from the original found key on the basis of the S_DELNO
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* flag.)
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*/
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if (LF_ISSET(S_DELNO)) {
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if (LF_ISSET(S_DUPLAST))
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while (B_DISSET(GET_BKEYDATA(h, indx + O_INDX)->type) &&
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indx > 0 &&
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h->inp[indx] == h->inp[indx - P_INDX])
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indx -= P_INDX;
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else
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while (B_DISSET(GET_BKEYDATA(h, indx + O_INDX)->type) &&
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indx < (db_indx_t)(NUM_ENT(h) - P_INDX) &&
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h->inp[indx] == h->inp[indx + P_INDX])
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indx += P_INDX;
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/*
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* If we weren't able to find a non-deleted duplicate, return
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* DB_NOTFOUND.
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*/
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if (B_DISSET(GET_BKEYDATA(h, indx + O_INDX)->type))
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goto notfound;
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}
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BT_STK_ENTER(cp, h, indx, lock, lock_mode, ret);
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return (ret);
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notfound:
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/* Keep the page locked for serializability. */
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(void)CDB_memp_fput(dbp->mpf, h, 0);
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(void)__TLPUT(dbc, lock);
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ret = DB_NOTFOUND;
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err: if (cp->csp > cp->sp) {
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BT_STK_POP(cp);
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CDB___bam_stkrel(dbc, 0);
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}
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return (ret);
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}
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/*
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* CDB___bam_stkrel --
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* Release all pages currently held in the stack.
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*
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* The caller must be sure that setting nolocks will not effect either
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* serializability or recoverability.
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*
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* PUBLIC: int CDB___bam_stkrel __P((DBC *, int));
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*/
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int
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CDB___bam_stkrel(dbc, nolocks)
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DBC *dbc;
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int nolocks;
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{
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BTREE_CURSOR *cp;
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DB *dbp;
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EPG *epg;
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dbp = dbc->dbp;
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cp = dbc->internal;
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/* Release inner pages first. */
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for (epg = cp->sp; epg <= cp->csp; ++epg) {
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if (epg->page != NULL)
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(void)CDB_memp_fput(dbp->mpf, epg->page, 0);
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if (epg->lock.off != LOCK_INVALID) {
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if (nolocks)
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(void)__LPUT(dbc, epg->lock);
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else
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(void)__TLPUT(dbc, epg->lock);
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}
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}
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/* Clear the stack, all pages have been released. */
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BT_STK_CLR(cp);
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return (0);
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}
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/*
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* CDB___bam_stkgrow --
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* Grow the stack.
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*
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* PUBLIC: int CDB___bam_stkgrow __P((BTREE_CURSOR *));
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*/
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int
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CDB___bam_stkgrow(cp)
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BTREE_CURSOR *cp;
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{
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EPG *p;
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size_t entries;
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int ret;
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entries = cp->esp - cp->sp;
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if ((ret = CDB___os_calloc(entries * 2, sizeof(EPG), &p)) != 0)
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return (ret);
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memcpy(p, cp->sp, entries * sizeof(EPG));
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if (cp->sp != cp->stack)
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CDB___os_free(cp->sp, entries * sizeof(EPG));
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cp->sp = p;
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cp->csp = p + entries;
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cp->esp = p + entries * 2;
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return (0);
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}
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