xref: /src/lib/libc/db/btree/bt_page.c

/*	$NetBSD: bt_page.c,v 1.6.2.1 1996/09/16 18:39:42 jtc Exp $	*/

/*-
 * Copyright (c) 1990, 1993, 1994
 *	The Regents of the University of California.  All rights reserved.
 *
 * 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)
#if 0
static char sccsid[] = "@(#)bt_page.c	8.3 (Berkeley) 7/14/94";
#else
static char rcsid[] = "$NetBSD: bt_page.c,v 1.6.2.1 1996/09/16 18:39:42 jtc Exp $";
#endif
#endif /* LIBC_SCCS and not lint */

#include "namespace.h"
#include <sys/types.h>

#include <stdio.h>

#include <db.h>
#include "btree.h"

/*
 * __bt_free --
 *	Put a page on the freelist.
 *
 * Parameters:
 *	t:	tree
 *	h:	page to free
 *
 * Returns:
 *	RET_ERROR, RET_SUCCESS
 *
 * Side-effect:
 *	mpool_put's the page.
 */
int
__bt_free(t, h)
	BTREE *t;
	PAGE *h;
{
	/* Insert the page at the head of the free list. */
	h->prevpg = P_INVALID;
	h->nextpg = t->bt_free;
	t->bt_free = h->pgno;

	/* Make sure the page gets written back. */
	return (mpool_put(t->bt_mp, h, MPOOL_DIRTY));
}

/*
 * __bt_new --
 *	Get a new page, preferably from the freelist.
 *
 * Parameters:
 *	t:	tree
 *	npg:	storage for page number.
 *
 * Returns:
 *	Pointer to a page, NULL on error.
 */
PAGE *
__bt_new(t, npg)
	BTREE *t;
	pgno_t *npg;
{
	PAGE *h;

	if (t->bt_free != P_INVALID &&
	    (h = mpool_get(t->bt_mp, t->bt_free, 0)) != NULL) {
		*npg = t->bt_free;
		t->bt_free = h->nextpg;
		return (h);
	}
	return (mpool_new(t->bt_mp, npg));
}