diff options
Diffstat (limited to 'lib/libc/db/btree/bt_stack.c')
| -rw-r--r-- | lib/libc/db/btree/bt_stack.c | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/lib/libc/db/btree/bt_stack.c b/lib/libc/db/btree/bt_stack.c new file mode 100644 index 0000000..5c7fab9 --- /dev/null +++ b/lib/libc/db/btree/bt_stack.c @@ -0,0 +1,92 @@ +/*- + * 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); +} |
