bt_page.c

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00001 /*-
00002  * Copyright (c) 1990, 1993, 1994
00003  * The Regents of the University of California.  All rights reserved.
00004  *
00005  * Redistribution and use in source and binary forms, with or without
00006  * modification, are permitted provided that the following conditions
00007  * are met:
00008  * 1. Redistributions of source code must retain the above copyright
00009  *    notice, this list of conditions and the following disclaimer.
00010  * 2. Redistributions in binary form must reproduce the above copyright
00011  *    notice, this list of conditions and the following disclaimer in the
00012  *    documentation and/or other materials provided with the distribution.
00013  * 3. All advertising materials mentioning features or use of this software
00014  *    must display the following acknowledgement:
00015  * This product includes software developed by the University of
00016  * California, Berkeley and its contributors.
00017  * 4. Neither the name of the University nor the names of its contributors
00018  *    may be used to endorse or promote products derived from this software
00019  *    without specific prior written permission.
00020  *
00021  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
00022  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
00023  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
00024  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
00025  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
00026  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
00027  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
00028  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
00029  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
00030  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
00031  * SUCH DAMAGE.
00032  */
00033 
00034 #if defined(LIBC_SCCS) && !defined(lint)
00035 static char sccsid[] = "@(#)bt_page.c  8.3 (Berkeley) 7/14/94";
00036 #endif /* LIBC_SCCS and not lint */
00037 
00038 #include <sys/types.h>
00039 
00040 #include <stdio.h>
00041 
00042 #include "../include/db.h"
00043 #include "btree.h"
00044 
00045 /*
00046  * __bt_free --
00047  * Put a page on the freelist.
00048  *
00049  * Parameters:
00050  * t: tree
00051  * h: page to free
00052  *
00053  * Returns:
00054  * RET_ERROR, RET_SUCCESS
00055  *
00056  * Side-effect:
00057  * mpool_put's the page.
00058  */
00059 int
00060 __bt_free(t, h)
00061    BTREE *t;
00062    PAGE *h;
00063 {
00064    /* Insert the page at the head of the free list. */
00065    h->prevpg = P_INVALID;
00066    h->nextpg = t->bt_free;
00067    t->bt_free = h->pgno;
00068    F_SET(t, B_METADIRTY);
00069 
00070    /* Make sure the page gets written back. */
00071    return (mpool_put(t->bt_mp, h, MPOOL_DIRTY));
00072 }
00073 
00074 /*
00075  * __bt_new --
00076  * Get a new page, preferably from the freelist.
00077  *
00078  * Parameters:
00079  * t: tree
00080  * npg:  storage for page number.
00081  *
00082  * Returns:
00083  * Pointer to a page, NULL on error.
00084  */
00085 PAGE *
00086 __bt_new(t, npg)
00087    BTREE *t;
00088    pgno_t *npg;
00089 {
00090    PAGE *h;
00091 
00092    if (t->bt_free != P_INVALID &&
00093        (h = mpool_get(t->bt_mp, t->bt_free, 0)) != NULL) {
00094       *npg = t->bt_free;
00095       t->bt_free = h->nextpg;
00096       F_SET(t, B_METADIRTY);
00097       return (h);
00098    }
00099    return (mpool_new(t->bt_mp, npg));
00100 }

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