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bt_page.c revision 1.12 
      1 /*	$NetBSD: bt_page.c,v 1.12 2008/09/10 17:52:35 joerg Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1990, 1993, 1994
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. Neither the name of the University nor the names of its contributors
     16  *    may be used to endorse or promote products derived from this software
     17  *    without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     29  * SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 __RCSID("$NetBSD: bt_page.c,v 1.12 2008/09/10 17:52:35 joerg Exp $");
     34 
     35 #include "namespace.h"
     36 #include <sys/types.h>
     37 
     38 #include <assert.h>
     39 #include <stdio.h>
     40 
     41 #include <db.h>
     42 #include "btree.h"
     43 
     44 /*
     45  * __bt_free --
     46  *	Put a page on the freelist.
     47  *
     48  * Parameters:
     49  *	t:	tree
     50  *	h:	page to free
     51  *
     52  * Returns:
     53  *	RET_ERROR, RET_SUCCESS
     54  *
     55  * Side-effect:
     56  *	mpool_put's the page.
     57  */
     58 int
     59 __bt_free(BTREE *t, PAGE *h)
     60 {
     61 	/* Insert the page at the head of the free list. */
     62 	h->prevpg = P_INVALID;
     63 	h->nextpg = t->bt_free;
     64 	t->bt_free = h->pgno;
     65 	F_SET(t, B_METADIRTY);
     66 
     67 	/* Make sure the page gets written back. */
     68 	return (mpool_put(t->bt_mp, h, MPOOL_DIRTY));
     69 }
     70 
     71 /*
     72  * __bt_new --
     73  *	Get a new page, preferably from the freelist.
     74  *
     75  * Parameters:
     76  *	t:	tree
     77  *	npg:	storage for page number.
     78  *
     79  * Returns:
     80  *	Pointer to a page, NULL on error.
     81  */
     82 PAGE *
     83 __bt_new(BTREE *t, pgno_t *npg)
     84 {
     85 	PAGE *h;
     86 
     87 	if (t->bt_free != P_INVALID &&
     88 	    (h = mpool_get(t->bt_mp, t->bt_free, 0)) != NULL) {
     89 		*npg = t->bt_free;
     90 		t->bt_free = h->nextpg;
     91 		F_SET(t, B_METADIRTY);
     92 		return (h);
     93 	}
     94 	return (mpool_new(t->bt_mp, npg));
     95 }
     96