Home | History | Annotate | Line # | Download | only in btree
bt_page.c revision 1.4.2.2
      1  1.4.2.2  cgd /*-
      2  1.4.2.2  cgd  * Copyright (c) 1990, 1993
      3  1.4.2.2  cgd  *	The Regents of the University of California.  All rights reserved.
      4  1.4.2.2  cgd  *
      5  1.4.2.2  cgd  * Redistribution and use in source and binary forms, with or without
      6  1.4.2.2  cgd  * modification, are permitted provided that the following conditions
      7  1.4.2.2  cgd  * are met:
      8  1.4.2.2  cgd  * 1. Redistributions of source code must retain the above copyright
      9  1.4.2.2  cgd  *    notice, this list of conditions and the following disclaimer.
     10  1.4.2.2  cgd  * 2. Redistributions in binary form must reproduce the above copyright
     11  1.4.2.2  cgd  *    notice, this list of conditions and the following disclaimer in the
     12  1.4.2.2  cgd  *    documentation and/or other materials provided with the distribution.
     13  1.4.2.2  cgd  * 3. All advertising materials mentioning features or use of this software
     14  1.4.2.2  cgd  *    must display the following acknowledgement:
     15  1.4.2.2  cgd  *	This product includes software developed by the University of
     16  1.4.2.2  cgd  *	California, Berkeley and its contributors.
     17  1.4.2.2  cgd  * 4. Neither the name of the University nor the names of its contributors
     18  1.4.2.2  cgd  *    may be used to endorse or promote products derived from this software
     19  1.4.2.2  cgd  *    without specific prior written permission.
     20  1.4.2.2  cgd  *
     21  1.4.2.2  cgd  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     22  1.4.2.2  cgd  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     23  1.4.2.2  cgd  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     24  1.4.2.2  cgd  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     25  1.4.2.2  cgd  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     26  1.4.2.2  cgd  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     27  1.4.2.2  cgd  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     28  1.4.2.2  cgd  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     29  1.4.2.2  cgd  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     30  1.4.2.2  cgd  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     31  1.4.2.2  cgd  * SUCH DAMAGE.
     32  1.4.2.2  cgd  */
     33  1.4.2.2  cgd 
     34  1.4.2.2  cgd #if defined(LIBC_SCCS) && !defined(lint)
     35  1.4.2.2  cgd static char sccsid[] = "@(#)bt_page.c	8.2 (Berkeley) 2/21/94";
     36  1.4.2.2  cgd #endif /* LIBC_SCCS and not lint */
     37  1.4.2.2  cgd 
     38  1.4.2.2  cgd #include <sys/types.h>
     39  1.4.2.2  cgd 
     40  1.4.2.2  cgd #include <stdio.h>
     41  1.4.2.2  cgd 
     42  1.4.2.2  cgd #include <db.h>
     43  1.4.2.2  cgd #include "btree.h"
     44  1.4.2.2  cgd 
     45  1.4.2.2  cgd /*
     46  1.4.2.2  cgd  * __BT_FREE -- Put a page on the freelist.
     47  1.4.2.2  cgd  *
     48  1.4.2.2  cgd  * Parameters:
     49  1.4.2.2  cgd  *	t:	tree
     50  1.4.2.2  cgd  *	h:	page to free
     51  1.4.2.2  cgd  *
     52  1.4.2.2  cgd  * Returns:
     53  1.4.2.2  cgd  *	RET_ERROR, RET_SUCCESS
     54  1.4.2.2  cgd  */
     55  1.4.2.2  cgd int
     56  1.4.2.2  cgd __bt_free(t, h)
     57  1.4.2.2  cgd 	BTREE *t;
     58  1.4.2.2  cgd 	PAGE *h;
     59  1.4.2.2  cgd {
     60  1.4.2.2  cgd 	/* Insert the page at the start of the free list. */
     61  1.4.2.2  cgd 	h->prevpg = P_INVALID;
     62  1.4.2.2  cgd 	h->nextpg = t->bt_free;
     63  1.4.2.2  cgd 	t->bt_free = h->pgno;
     64  1.4.2.2  cgd 
     65  1.4.2.2  cgd 	/* Make sure the page gets written back. */
     66  1.4.2.2  cgd 	return (mpool_put(t->bt_mp, h, MPOOL_DIRTY));
     67  1.4.2.2  cgd }
     68  1.4.2.2  cgd 
     69  1.4.2.2  cgd /*
     70  1.4.2.2  cgd  * __BT_NEW -- Get a new page, preferably from the freelist.
     71  1.4.2.2  cgd  *
     72  1.4.2.2  cgd  * Parameters:
     73  1.4.2.2  cgd  *	t:	tree
     74  1.4.2.2  cgd  *	npg:	storage for page number.
     75  1.4.2.2  cgd  *
     76  1.4.2.2  cgd  * Returns:
     77  1.4.2.2  cgd  *	Pointer to a page, NULL on error.
     78  1.4.2.2  cgd  */
     79  1.4.2.2  cgd PAGE *
     80  1.4.2.2  cgd __bt_new(t, npg)
     81  1.4.2.2  cgd 	BTREE *t;
     82  1.4.2.2  cgd 	pgno_t *npg;
     83  1.4.2.2  cgd {
     84  1.4.2.2  cgd 	PAGE *h;
     85  1.4.2.2  cgd 
     86  1.4.2.2  cgd 	if (t->bt_free != P_INVALID &&
     87  1.4.2.2  cgd 	    (h = mpool_get(t->bt_mp, t->bt_free, 0)) != NULL) {
     88  1.4.2.2  cgd 			*npg = t->bt_free;
     89  1.4.2.2  cgd 			t->bt_free = h->nextpg;
     90  1.4.2.2  cgd 			return (h);
     91  1.4.2.2  cgd 	}
     92  1.4.2.2  cgd 	return (mpool_new(t->bt_mp, npg));
     93  1.4.2.2  cgd }
     94