db/btree/bt_page.c

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