rec_delete.c

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/*-
 * Copyright (c) 1990, 1993, 1994
 *  The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Mike Olson.
 *
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *  This product includes software developed by the University of
 *  California, Berkeley and its contributors.
 * 4. 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[] = "@(#)rec_delete.c    8.7 (Berkeley) 7/14/94";
#endif /* LIBC_SCCS and not lint */
 
#include <sys/types.h>
 
#include <errno.h>
#include <stdio.h>
#include <string.h>
 
#include "../include/db.h"
#include "recno.h"
 
static int rec_rdelete __P((BTREE *, recno_t));
 
/*
 * __REC_DELETE -- Delete the item(s) referenced by a key.
 *
 * Parameters:
 *  dbp:    pointer to access method
 *  key:    key to delete
 *  flags:  R_CURSOR if deleting what the cursor references
 *
 * Returns:
 *  RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found.
 */
int
__rec_delete(dbp, key, flags)
    const DB *dbp;
    const DBT *key;
    u_int flags;
{
    BTREE *t;
    recno_t nrec;
    int status;
 
    t = dbp->internal;
 
    /* Toss any page pinned across calls. */
    if (t->bt_pinned != NULL) {
        mpool_put(t->bt_mp, t->bt_pinned, 0);
        t->bt_pinned = NULL;
    }
 
    switch(flags) {
    case 0:
        if ((nrec = *(recno_t *)key->data) == 0)
            goto einval;
        if (nrec > t->bt_nrecs)
            return (RET_SPECIAL);
        --nrec;
        status = rec_rdelete(t, nrec);
        break;
    case R_CURSOR:
        if (!F_ISSET(&t->bt_cursor, CURS_INIT))
            goto einval;
        if (t->bt_nrecs == 0)
            return (RET_SPECIAL);
        status = rec_rdelete(t, t->bt_cursor.rcursor - 1);
        if (status == RET_SUCCESS)
            --t->bt_cursor.rcursor;
        break;
    default:
einval:     errno = EINVAL;
        return (RET_ERROR);
    }
 
    if (status == RET_SUCCESS)
        F_SET(t, B_MODIFIED | R_MODIFIED);
    return (status);
}
 
/*
 * REC_RDELETE -- Delete the data matching the specified key.
 *
 * Parameters:
 *  tree:   tree
 *  nrec:   record to delete
 *
 * Returns:
 *  RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found.
 */
static int
rec_rdelete(t, nrec)
    BTREE *t;
    recno_t nrec;
{
    EPG *e;
    PAGE *h;
    int status;
 
    /* Find the record; __rec_search pins the page. */
    if ((e = __rec_search(t, nrec, SDELETE)) == NULL)
        return (RET_ERROR);
 
    /* Delete the record. */
    h = e->page;
    status = __rec_dleaf(t, h, e->index);
    if (status != RET_SUCCESS) {
        mpool_put(t->bt_mp, h, 0);
        return (status);
    }
    mpool_put(t->bt_mp, h, MPOOL_DIRTY);
    return (RET_SUCCESS);
}
 
/*
 * __REC_DLEAF -- Delete a single record from a recno leaf page.
 *
 * Parameters:
 *  t:  tree
 *  index:  index on current page to delete
 *
 * Returns:
 *  RET_SUCCESS, RET_ERROR.
 */
int
__rec_dleaf(t, h, idx)
    BTREE *t;
    PAGE *h;
    u_int32_t idx;
{
    RLEAF *rl;
    indx_t *ip, cnt, offset;
    u_int32_t nbytes;
    char *from;
    void *to;
 
    /*
     * Delete a record from a recno leaf page.  Internal records are never
     * deleted from internal pages, regardless of the records that caused
     * them to be added being deleted.  Pages made empty by deletion are
     * not reclaimed.  They are, however, made available for reuse.
     *
     * Pack the remaining entries at the end of the page, shift the indices
     * down, overwriting the deleted record and its index.  If the record
     * uses overflow pages, make them available for reuse.
     */
    to = rl = GETRLEAF(h, idx);
    if (rl->flags & P_BIGDATA && __ovfl_delete(t, rl->bytes) == RET_ERROR)
        return (RET_ERROR);
    nbytes = NRLEAF(rl);
 
    /*
     * Compress the key/data pairs.  Compress and adjust the [BR]LEAF
     * offsets.  Reset the headers.
     */
    from = (char *)h + h->upper;
    memmove(from + nbytes, from, (char *)to - from);
    h->upper += nbytes;
 
    offset = h->linp[idx];
    for (cnt = &h->linp[idx] - (ip = &h->linp[0]); cnt--; ++ip)
        if (ip[0] < offset)
            ip[0] += nbytes;
    for (cnt = &h->linp[NEXTINDEX(h)] - ip; --cnt; ++ip)
        ip[0] = ip[1] < offset ? ip[1] + nbytes : ip[1];
    h->lower -= sizeof(indx_t);
    --t->bt_nrecs;
    return (RET_SUCCESS);
}