lib/libc/db/btree/bt_page.c

   1 /*      $NetBSD: bt_page.c,v 1.13 2008/09/11 12:58:00 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 #if HAVE_NBTOOL_CONFIG_H
  33 #include "nbtool_config.h"
  34 #endif
  35
  36 #include <sys/cdefs.h>
  37 __RCSID("$NetBSD: bt_page.c,v 1.13 2008/09/11 12:58:00 joerg Exp $");
  38
  39 #include "namespace.h"
  40 #include <sys/types.h>
  41
  42 #include <assert.h>
  43 #include <stdio.h>
  44
  45 #include <db.h>
  46 #include "btree.h"
  47
  48 /*
  49  * __bt_free --
  50  *      Put a page on the freelist.
  51  *
  52  * Parameters:
  53  *      t:      tree
  54  *      h:      page to free
  55  *
  56  * Returns:
  57  *      RET_ERROR, RET_SUCCESS
  58  *
  59  * Side-effect:
  60  *      mpool_put's the page.
  61  */
  62 int
  63 __bt_free(BTREE *t, PAGE *h)
  64 {
  65         /* Insert the page at the head of the free list. */
  66         h->prevpg = P_INVALID;
  67         h->nextpg = t->bt_free;
  68         t->bt_free = h->pgno;
  69         F_SET(t, B_METADIRTY);
  70
  71         /* Make sure the page gets written back. */
  72         return (mpool_put(t->bt_mp, h, MPOOL_DIRTY));
  73 }
  74
  75 /*
  76  * __bt_new --
  77  *      Get a new page, preferably from the freelist.
  78  *
  79  * Parameters:
  80  *      t:      tree
  81  *      npg:    storage for page number.
  82  *
  83  * Returns:
  84  *      Pointer to a page, NULL on error.
  85  */
  86 PAGE *
  87 __bt_new(BTREE *t, pgno_t *npg)
  88 {
  89         PAGE *h;
  90
  91         if (t->bt_free != P_INVALID &&
  92             (h = mpool_get(t->bt_mp, t->bt_free, 0)) != NULL) {
  93                 *npg = t->bt_free;
  94                 t->bt_free = h->nextpg;
  95                 F_SET(t, B_METADIRTY);
  96                 return (h);
  97         }
  98         return (mpool_new(t->bt_mp, npg));
  99 }