db/btree/bt_page.c

   1 /*
   2  * Copyright (c) 2003 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*-
  26  * Copyright (c) 1990, 1993, 1994
  27  *      The Regents of the University of California.  All rights reserved.
  28  *
  29  * Redistribution and use in source and binary forms, with or without
  30  * modification, are permitted provided that the following conditions
  31  * are met:
  32  * 1. Redistributions of source code must retain the above copyright
  33  *    notice, this list of conditions and the following disclaimer.
  34  * 2. Redistributions in binary form must reproduce the above copyright
  35  *    notice, this list of conditions and the following disclaimer in the
  36  *    documentation and/or other materials provided with the distribution.
  37  * 3. All advertising materials mentioning features or use of this software
  38  *    must display the following acknowledgement:
  39  *      This product includes software developed by the University of
  40  *      California, Berkeley and its contributors.
  41  * 4. Neither the name of the University nor the names of its contributors
  42  *    may be used to endorse or promote products derived from this software
  43  *    without specific prior written permission.
  44  *
  45  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  46  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  47  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  48  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  49  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  50  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  51  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  52  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  53  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  54  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  55  * SUCH DAMAGE.
  56  */
  57
  58 #if defined(LIBC_SCCS) && !defined(lint)
  59 static char sccsid[] = "@(#)bt_page.c   8.3 (Berkeley) 7/14/94";
  60 #endif /* LIBC_SCCS and not lint */
  61 #include <sys/cdefs.h>
  62
  63 #include <sys/types.h>
  64
  65 #include <stdio.h>
  66
  67 #include <db.h>
  68 #include "btree.h"
  69
  70 /*
  71  * __bt_free --
  72  *      Put a page on the freelist.
  73  *
  74  * Parameters:
  75  *      t:      tree
  76  *      h:      page to free
  77  *
  78  * Returns:
  79  *      RET_ERROR, RET_SUCCESS
  80  *
  81  * Side-effect:
  82  *      mpool_put's the page.
  83  */
  84 int
  85 __bt_free(t, h)
  86         BTREE *t;
  87         PAGE *h;
  88 {
  89         /* Insert the page at the head of the free list. */
  90         h->prevpg = P_INVALID;
  91         h->nextpg = t->bt_free;
  92         t->bt_free = h->pgno;
  93         F_SET(t, B_METADIRTY);
  94
  95         /* Make sure the page gets written back. */
  96         return (mpool_put(t->bt_mp, h, MPOOL_DIRTY));
  97 }
  98
  99 /*
 100  * __bt_new --
 101  *      Get a new page, preferably from the freelist.
 102  *
 103  * Parameters:
 104  *      t:      tree
 105  *      npg:    storage for page number.
 106  *
 107  * Returns:
 108  *      Pointer to a page, NULL on error.
 109  */
 110 PAGE *
 111 __bt_new(t, npg)
 112         BTREE *t;
 113         pgno_t *npg;
 114 {
 115         PAGE *h;
 116
 117         if (t->bt_free != P_INVALID &&
 118             (h = mpool_get(t->bt_mp, t->bt_free, 0)) != NULL) {
 119                 *npg = t->bt_free;
 120                 t->bt_free = h->nextpg;
 121                 F_SET(t, B_METADIRTY);
 122                 return (h);
 123         }
 124         return (mpool_new(t->bt_mp, npg));
 125 }