## 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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