bt_put.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[] = "@(#)bt_put.c    8.8 (Berkeley) 7/26/94";
#endif /* LIBC_SCCS and not lint */
 
#include <sys/types.h>
 
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
#include "../include/db.h"
#include "btree.h"
 
static EPG *bt_fast __P((BTREE *, const DBT *, const DBT *, int *));
 
/*
 * __BT_PUT -- Add a btree item to the tree.
 *
 * Parameters:
 *  dbp:    pointer to access method
 *  key:    key
 *  data:   data
 *  flag:   R_NOOVERWRITE
 *
 * Returns:
 *  RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key is already in the
 *  tree and R_NOOVERWRITE specified.
 */
int
__bt_put(dbp, key, data, flags)
    const DB *dbp;
    DBT *key;
    const DBT *data;
    u_int flags;
{
    BTREE *t;
    DBT tkey, tdata;
    EPG *e = 0;
    PAGE *h;
    indx_t idx, nxtindex;
    pgno_t pg;
    u_int32_t nbytes;
    int dflags, exact, status;
    char *dest, db[NOVFLSIZE], kb[NOVFLSIZE];
 
    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;
    }
 
    /* Check for change to a read-only tree. */
    if (F_ISSET(t, B_RDONLY)) {
        errno = EPERM;
        return (RET_ERROR);
    }
 
    switch (flags) {
    case 0:
    case R_NOOVERWRITE:
        break;
    case R_CURSOR:
        /*
         * If flags is R_CURSOR, put the cursor.  Must already
         * have started a scan and not have already deleted it.
         */
        if (F_ISSET(&t->bt_cursor, CURS_INIT) &&
            !F_ISSET(&t->bt_cursor,
                CURS_ACQUIRE | CURS_AFTER | CURS_BEFORE))
            break;
        /* FALLTHROUGH */
    default:
        errno = EINVAL;
        return (RET_ERROR);
    }
 
    /*
     * If the key/data pair won't fit on a page, store it on overflow
     * pages.  Only put the key on the overflow page if the pair are
     * still too big after moving the data to an overflow page.
     *
     * XXX
     * If the insert fails later on, the overflow pages aren't recovered.
     */
    dflags = 0;
    if (key->size + data->size > t->bt_ovflsize) {
        if (key->size > t->bt_ovflsize) {
storekey:       if (__ovfl_put(t, key, &pg) == RET_ERROR)
                return (RET_ERROR);
            tkey.data = kb;
            tkey.size = NOVFLSIZE;
            memmove(kb, &pg, sizeof(pgno_t));
            memmove(kb + sizeof(pgno_t),
                &key->size, sizeof(u_int32_t));
            dflags |= P_BIGKEY;
            key = &tkey;
        }
        if (key->size + data->size > t->bt_ovflsize) {
            if (__ovfl_put(t, data, &pg) == RET_ERROR)
                return (RET_ERROR);
            tdata.data = db;
            tdata.size = NOVFLSIZE;
            memmove(db, &pg, sizeof(pgno_t));
            memmove(db + sizeof(pgno_t),
                &data->size, sizeof(u_int32_t));
            dflags |= P_BIGDATA;
            data = &tdata;
        }
        if (key->size + data->size > t->bt_ovflsize)
            goto storekey;
    }
 
    /* Replace the cursor. */
    if (flags == R_CURSOR) {
        if ((h = mpool_get(t->bt_mp, t->bt_cursor.pg.pgno, 0)) == NULL)
            return (RET_ERROR);
        idx = t->bt_cursor.pg.index;
        goto delete;
    }
 
    /*
     * Find the key to delete, or, the location at which to insert.
     * Bt_fast and __bt_search both pin the returned page.
     */
    if (t->bt_order == NOT || (e = bt_fast(t, key, data, &exact)) == NULL)
        if ((e = __bt_search(t, key, &exact)) == NULL)
            return (RET_ERROR);
    h = e->page;
    idx = e->index;
 
    /*
     * Add the key/data pair to the tree.  If an identical key is already
     * in the tree, and R_NOOVERWRITE is set, an error is returned.  If
     * R_NOOVERWRITE is not set, the key is either added (if duplicates are
     * permitted) or an error is returned.
     */
    switch (flags) {
    case R_NOOVERWRITE:
        if (!exact)
            break;
        mpool_put(t->bt_mp, h, 0);
        return (RET_SPECIAL);
    default:
        if (!exact || !F_ISSET(t, B_NODUPS))
            break;
        /*
         * !!!
         * Note, the delete may empty the page, so we need to put a
         * new entry into the page immediately.
         */
delete:     if (__bt_dleaf(t, key, h, idx) == RET_ERROR) {
            mpool_put(t->bt_mp, h, 0);
            return (RET_ERROR);
        }
        break;
    }
 
    /*
     * If not enough room, or the user has put a ceiling on the number of
     * keys permitted in the page, split the page.  The split code will
     * insert the key and data and unpin the current page.  If inserting
     * into the offset array, shift the pointers up.
     */
    nbytes = NBLEAFDBT(key->size, data->size);
    if ((u_int32_t) (h->upper - h->lower) < nbytes + sizeof(indx_t)) {
        if ((status = __bt_split(t, h, key,
            data, dflags, nbytes, idx)) != RET_SUCCESS)
            return (status);
        goto success;
    }
 
    if (idx < (nxtindex = NEXTINDEX(h)))
        memmove(h->linp + idx + 1, h->linp + idx,
            (nxtindex - idx) * sizeof(indx_t));
    h->lower += sizeof(indx_t);
 
    h->linp[idx] = h->upper -= nbytes;
    dest = (char *)h + h->upper;
    WR_BLEAF(dest, key, data, dflags);
 
    /* If the cursor is on this page, adjust it as necessary. */
    if (F_ISSET(&t->bt_cursor, CURS_INIT) &&
        !F_ISSET(&t->bt_cursor, CURS_ACQUIRE) &&
        t->bt_cursor.pg.pgno == h->pgno && t->bt_cursor.pg.index >= idx)
        ++t->bt_cursor.pg.index;
 
    if (t->bt_order == NOT) {
        if (h->nextpg == P_INVALID) {
            if (idx == NEXTINDEX(h) - 1) {
                t->bt_order = FORWARD;
                t->bt_last.index = idx;
                t->bt_last.pgno = h->pgno;
            }
        } else if (h->prevpg == P_INVALID) {
            if (idx == 0) {
                t->bt_order = BACK;
                t->bt_last.index = 0;
                t->bt_last.pgno = h->pgno;
            }
        }
    }
 
    mpool_put(t->bt_mp, h, MPOOL_DIRTY);
 
success:
    if (flags == R_SETCURSOR)
        __bt_setcur(t, e->page->pgno, e->index);
 
    F_SET(t, B_MODIFIED);
    return (RET_SUCCESS);
}
 
#ifdef STATISTICS
u_long bt_cache_hit, bt_cache_miss;
#endif
 
/*
 * BT_FAST -- Do a quick check for sorted data.
 *
 * Parameters:
 *  t:  tree
 *  key:    key to insert
 *
 * Returns:
 *  EPG for new record or NULL if not found.
 */
static EPG *
bt_fast(t, key, data, exactp)
    BTREE *t;
    const DBT *key, *data;
    int *exactp;
{
    PAGE *h;
    u_int32_t nbytes;
    int cmp;
 
    if ((h = mpool_get(t->bt_mp, t->bt_last.pgno, 0)) == NULL) {
        t->bt_order = NOT;
        return (NULL);
    }
    t->bt_cur.page = h;
    t->bt_cur.index = t->bt_last.index;
 
    /*
     * If won't fit in this page or have too many keys in this page,
     * have to search to get split stack.
     */
    nbytes = NBLEAFDBT(key->size, data->size);
    if ((u_int32_t) (h->upper - h->lower) < nbytes + sizeof(indx_t))
        goto miss;
 
    if (t->bt_order == FORWARD) {
        if (t->bt_cur.page->nextpg != P_INVALID)
            goto miss;
        if (t->bt_cur.index != NEXTINDEX(h) - 1)
            goto miss;
        if ((cmp = __bt_cmp(t, key, &t->bt_cur)) < 0)
            goto miss;
        t->bt_last.index = cmp ? ++t->bt_cur.index : t->bt_cur.index;
    } else {
        if (t->bt_cur.page->prevpg != P_INVALID)
            goto miss;
        if (t->bt_cur.index != 0)
            goto miss;
        if ((cmp = __bt_cmp(t, key, &t->bt_cur)) > 0)
            goto miss;
        t->bt_last.index = 0;
    }
    *exactp = cmp == 0;
#ifdef STATISTICS
    ++bt_cache_hit;
#endif
    return (&t->bt_cur);
 
miss:
#ifdef STATISTICS
    ++bt_cache_miss;
#endif
    t->bt_order = NOT;
    mpool_put(t->bt_mp, h, 0);
    return (NULL);
}