lib/libc/db/btree/bt_page.c

   1 /*      $OpenBSD: bt_page.c,v 1.9 2005/08/05 13:02:59 espie 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/types.h>
  33
  34 #include <stdio.h>
  35
  36 #include <db.h>
  37 #include "btree.h"
  38
  39 /*
  40  * __bt_free --
  41  *      Put a page on the freelist.
  42  *
  43  * Parameters:
  44  *      t:      tree
  45  *      h:      page to free
  46  *
  47  * Returns:
  48  *      RET_ERROR, RET_SUCCESS
  49  *
  50  * Side-effect:
  51  *      mpool_put's the page.
  52  */
  53 int
  54 __bt_free(BTREE *t, PAGE *h)
  55 {
  56         /* Insert the page at the head of the free list. */
  57         h->prevpg = P_INVALID;
  58         h->nextpg = t->bt_free;
  59         t->bt_free = h->pgno;
  60         F_SET(t, B_METADIRTY);
  61
  62         /* Make sure the page gets written back. */
  63         return (mpool_put(t->bt_mp, h, MPOOL_DIRTY));
  64 }
  65
  66 /*
  67  * __bt_new --
  68  *      Get a new page, preferably from the freelist.
  69  *
  70  * Parameters:
  71  *      t:      tree
  72  *      npg:    storage for page number.
  73  *
  74  * Returns:
  75  *      Pointer to a page, NULL on error.
  76  */
  77 PAGE *
  78 __bt_new(BTREE *t, pgno_t *npg)
  79 {
  80         PAGE *h;
  81
  82         if (t->bt_free != P_INVALID &&
  83             (h = mpool_get(t->bt_mp, t->bt_free, 0)) != NULL) {
  84                 *npg = t->bt_free;
  85                 t->bt_free = h->nextpg;
  86                 F_SET(t, B_METADIRTY);
  87                 return (h);
  88         }
  89         return (mpool_new(t->bt_mp, npg, MPOOL_PAGE_NEXT));
  90 }