usr/src/lib/libc/db/btree/bt_put.c

/*-
 * Copyright (c) 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Mike Olson.
 *
 * %sccs.include.redist.c%
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)bt_put.c    5.8 (Berkeley) %G%";
#endif /* LIBC_SCCS and not lint */

#include <sys/types.h>

#include <db.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.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;
        PAGE *h;
        index_t index, nxtindex;
        pgno_t pg;
        size_t nbytes;
        int dflags, exact, status;
        char *dest, db[NOVFLSIZE], kb[NOVFLSIZE];

        t = dbp->internal;

        switch (flags) {
        case R_CURSOR:
                if (ISSET(t, BTF_DELCRSR)) {
                        errno = EINVAL;
                        return (RET_ERROR);
                }
                break;
        case 0:
        case R_NOOVERWRITE:
                break;
        default:
                errno = EINVAL;
                return (RET_ERROR);
        }

        if (ISSET(t, BTF_RDONLY)) {
                errno = EPERM;
                return (RET_ERROR);
        }

        /*
         * If the key/data won't fit on a page, store it on indirect pages.
         * Only store the key on the overflow page if it's too big after the
         * data is on an overflow page.
         *
         * XXX
         * If the insert fails later on, these 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;
                        bcopy(&pg, kb, sizeof(pgno_t));
                        bcopy(&key->size, kb + sizeof(pgno_t), sizeof(size_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;
                        bcopy(&pg, db, sizeof(pgno_t));
                        bcopy(&data->size, db + sizeof(pgno_t), sizeof(size_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_bcursor.pgno, 0)) == NULL)
                        return (RET_ERROR);
                index = t->bt_bcursor.index;
                goto delete;
        }

        /*
         * Find the key to delete, or, the location at which to insert.  Bt_fast
         * and __bt_search 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 specified 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.
         *
         * Pages are split as required.
         */
        switch (flags) {
        case R_NOOVERWRITE:
                if (!exact)
                        break;
                /*
                 * One special case is if the cursor references the record and
                 * it's been flagged for deletion.  Then, we delete the record,
                 * leaving the cursor there -- this means that the inserted
                 * record will not be seen in a cursor scan.
                 */
                if (ISSET(t, BTF_DELCRSR) && t->bt_bcursor.pgno == h->pgno &&
                    t->bt_bcursor.index == index) {
                        CLR(t, BTF_DELCRSR);
                        goto delete;
                }
                BT_CLR(t);
                mpool_put(t->bt_mp, h, 0);
                return (RET_SPECIAL);
        default:
                if (!exact || !ISSET(t, BTF_NODUPS))
                        break;
delete:         if (__bt_dleaf(t, h, index) == RET_ERROR) {
                        BT_CLR(t);
                        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(index_t)) {
                if ((status = __bt_split(t, h, key,
                    data, dflags, nbytes, index)) != RET_SUCCESS)
                        return (status);
                goto success;
        }

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

        h->linp[index] = h->upper -= nbytes;
        dest = (char *)h + h->upper;
        WR_BLEAF(dest, key, data, dflags);

        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);
        BT_CLR(t);

success:
        if (flags == R_SETCURSOR) {
                t->bt_bcursor.pgno = e->page->pgno;
                t->bt_bcursor.index = e->index;
        }
        SET(t, BTF_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;
{
        EPG e;
        PAGE *h;
        size_t nbytes;
        int cmp;

        if ((h = mpool_get(t->bt_mp, t->bt_last.pgno, 0)) == NULL) {
                t->bt_order = NOT;
                return (NULL);
        }
        e.page = h;
        e.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(index_t))
                goto miss;

        if (t->bt_order == FORWARD) {
                if (e.page->nextpg != P_INVALID)
                        goto miss;
                if (e.index != NEXTINDEX(h) - 1)
                        goto miss;
                if ((cmp = __bt_cmp(t, key, &e)) < 0)
                        goto miss;
                t->bt_last.index = cmp ? ++e.index : e.index;
        } else {
                if (e.page->prevpg != P_INVALID)
                        goto miss;
                if (e.index != 0)
                        goto miss;
                if ((cmp = __bt_cmp(t, key, &e)) > 0)
                        goto miss;
                t->bt_last.index = 0;
        }
        *exactp = cmp == 0;
#ifdef STATISTICS
        ++bt_cache_hit;
#endif
        return (&e);

miss:
#ifdef STATISTICS
        ++bt_cache_miss;
#endif
        t->bt_order = NOT;
        mpool_put(t->bt_mp, h, 0);
        return (NULL);
}