## root/libdb/bt_page.c(57.html)

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## DEFINITIONS

This source file includes following definitions.

1. __bt_free
2. __bt_new

    /*-
     * Copyright (c) 1990, 1993, 1994
     *      The Regents of the University of California.  All rights reserved.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     */

    #if defined(LIBC_SCCS) && !defined(lint)
    static char sccsid[] = "@(#)bt_page.c   8.3 (Berkeley) 7/14/94";
    #endif /* LIBC_SCCS and not lint */

    #ifdef HAVE_CONFIG_H
    #include <config.h>
    #endif
    #include <sys/types.h>

    #include <stdio.h>

    #include "db.h"
    #include "btree.h"

    /*
     * __bt_free --
     *      Put a page on the freelist.
     *
     * Parameters:
     *      t:      tree
     *      h:      page to free
     *
     * Returns:
     *      RET_ERROR, RET_SUCCESS
     *
     * Side-effect:
     *      mpool_put's the page.
     */
    int
    __bt_free(t, h)
            BTREE *t;
            PAGE *h;
    {
            /* Insert the page at the head of the free list. */
            h->prevpg = P_INVALID;
            h->nextpg = t->bt_free;
            t->bt_free = h->pgno;
            F_SET(t, B_METADIRTY);

            /* Make sure the page gets written back. */
            return (mpool_put(t->bt_mp, h, MPOOL_DIRTY));
    }

    /*
     * __bt_new --
     *      Get a new page, preferably from the freelist.
     *
     * Parameters:
     *      t:      tree
     *      npg:    storage for page number.
     *
     * Returns:
     *      Pointer to a page, NULL on error.
     */
    PAGE *
    __bt_new(t, npg)
            BTREE *t;
            pgno_t *npg;
    {
            PAGE *h;

            if (t->bt_free != P_INVALID &&
                (h = mpool_get(t->bt_mp, t->bt_free, 0)) != NULL) {
                    *npg = t->bt_free;
                    t->bt_free = h->nextpg;
                    F_SET(t, B_METADIRTY);
                    return (h);
            }
            return (mpool_new(t->bt_mp, npg));
    }

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