root/libdb/bt_put.c

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DEFINITIONS

This source file includes following definitions.
  1. __bt_put
  2. bt_fast

/*-
 * 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. 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 */

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

#include <errno.h>
#include <stdio.h>
#ifdef STDC_HEADERS
#include <stdlib.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#else
#include <strings.h>
#endif

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

static EPG *bt_fast(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 = NULL;
        PAGE *h;
        indx_t index, 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);
                index = 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;
        index = 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, index) == 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 (h->upper - h->lower < nbytes + sizeof(indx_t)) {
                if ((status = __bt_split(t, h, key,
                    data, dflags, nbytes, index)) != RET_SUCCESS)
                        return (status);
                goto success;
        }

        if (index < (nxtindex = NEXTINDEX(h)))
                memmove(h->linp + index + 1, h->linp + index,
                    (nxtindex - index) * sizeof(indx_t));
        h->lower += sizeof(indx_t);

        h->linp[index] = 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 >= index)
                ++t->bt_cursor.pg.index;

        if (t->bt_order == NOT) {
                if (h->nextpg == P_INVALID) {
                        if (index == NEXTINDEX(h) - 1) {
                                t->bt_order = FORWARD;
                                t->bt_last.index = index;
                                t->bt_last.pgno = h->pgno;
                        }
                } else if (h->prevpg == P_INVALID) {
                        if (index == 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);
}

u_long bt_cache_hit, bt_cache_miss;

/*
 * 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 (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);
}

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