freebsd-dev/lib/libc/db/btree/bt_stack.c
1994-05-27 05:00:24 +00:00

93 lines
3.2 KiB
C

/*-
* Copyright (c) 1990, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Mike Olson.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)bt_stack.c 8.3 (Berkeley) 2/21/94";
#endif /* LIBC_SCCS and not lint */
#include <sys/types.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <db.h>
#include "btree.h"
/*
* When a page splits, a new record has to be inserted into its parent page.
* This page may have to split as well, all the way up to the root. Since
* parent pointers in each page would be expensive, we maintain a stack of
* parent pages as we descend the tree.
*
* XXX
* This is a concurrency problem -- if user a builds a stack, then user b
* splits the tree, then user a tries to split the tree, there's a new level
* in the tree that user a doesn't know about.
*/
/*
* __BT_PUSH -- Push parent page info onto the stack (LIFO).
*
* Parameters:
* t: tree
* pgno: page
* index: page index
*
* Returns:
* RET_ERROR, RET_SUCCESS
*/
int
__bt_push(t, pgno, index)
BTREE *t;
pgno_t pgno;
indx_t index;
{
if (t->bt_sp == t->bt_maxstack) {
t->bt_maxstack += 50;
if ((t->bt_stack = (EPGNO *)realloc(t->bt_stack,
t->bt_maxstack * sizeof(EPGNO))) == NULL) {
t->bt_maxstack -= 50;
return (RET_ERROR);
}
}
t->bt_stack[t->bt_sp].pgno = pgno;
t->bt_stack[t->bt_sp].index = index;
++t->bt_sp;
return (RET_SUCCESS);
}