hash_dup.c

/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1996-2005
 *      Sleepycat Software.  All rights reserved.
 */
/*
 * 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
 * Margo Seltzer.
 *
 * 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.
 *
 * $Id: hash_dup.c,v 12.3 2005/07/20 16:51:41 bostic Exp $
 */

#include "db_config.h"

/*
 * PACKAGE:  hashing
 *
 * DESCRIPTION:
 *      Manipulation of duplicates for the hash package.
 */

#ifndef NO_SYSTEM_INCLUDES
#include <sys/types.h>

#include <string.h>
#endif

#include "db_int.h"
#include "dbinc/db_page.h"
#include "dbinc/db_shash.h"
#include "dbinc/hash.h"
#include "dbinc/btree.h"
#include "dbinc/mp.h"

static int __ham_c_chgpg __P((DBC *,
    db_pgno_t, u_int32_t, db_pgno_t, u_int32_t));
static int __ham_check_move __P((DBC *, u_int32_t));
static int __ham_dcursor __P((DBC *, db_pgno_t, u_int32_t));
static int __ham_move_offpage __P((DBC *, PAGE *, u_int32_t, db_pgno_t));

/*
 * Called from hash_access to add a duplicate key. nval is the new
 * value that we want to add.  The flags correspond to the flag values
 * to cursor_put indicating where to add the new element.
 * There are 4 cases.
 * Case 1: The existing duplicate set already resides on a separate page.
 *         We return and let the common code handle this.
 * Case 2: The element is small enough to just be added to the existing set.
 * Case 3: The element is large enough to be a big item, so we're going to
 *         have to push the set onto a new page.
 * Case 4: The element is large enough to push the duplicate set onto a
 *         separate page.
 *
 * PUBLIC: int __ham_add_dup __P((DBC *, DBT *, u_int32_t, db_pgno_t *));
 */
int
__ham_add_dup(dbc, nval, flags, pgnop)
        DBC *dbc;
        DBT *nval;
        u_int32_t flags;
        db_pgno_t *pgnop;
{
        DB *dbp;
        DBT pval, tmp_val;
        DB_MPOOLFILE *mpf;
        HASH_CURSOR *hcp;
        u_int32_t add_bytes, new_size;
        int cmp, ret;
        u_int8_t *hk;

        dbp = dbc->dbp;
        mpf = dbp->mpf;
        hcp = (HASH_CURSOR *)dbc->internal;

        DB_ASSERT(flags != DB_CURRENT);

        add_bytes = nval->size +
            (F_ISSET(nval, DB_DBT_PARTIAL) ? nval->doff : 0);
        add_bytes = DUP_SIZE(add_bytes);

        if ((ret = __ham_check_move(dbc, add_bytes)) != 0)
                return (ret);

        /*
         * Check if resulting duplicate set is going to need to go
         * onto a separate duplicate page.  If so, convert the
         * duplicate set and add the new one.  After conversion,
         * hcp->dndx is the first free ndx or the index of the
         * current pointer into the duplicate set.
         */
        hk = H_PAIRDATA(dbp, hcp->page, hcp->indx);
        /* Add the len bytes to the current singleton. */
        if (HPAGE_PTYPE(hk) != H_DUPLICATE)
                add_bytes += DUP_SIZE(0);
        new_size =
            LEN_HKEYDATA(dbp, hcp->page, dbp->pgsize, H_DATAINDEX(hcp->indx)) +
            add_bytes;

        /*
         * We convert to off-page duplicates if the item is a big item,
         * the addition of the new item will make the set large, or
         * if there isn't enough room on this page to add the next item.
         */
        if (HPAGE_PTYPE(hk) != H_OFFDUP &&
            (HPAGE_PTYPE(hk) == H_OFFPAGE || ISBIG(hcp, new_size) ||
            add_bytes > P_FREESPACE(dbp, hcp->page))) {

                if ((ret = __ham_dup_convert(dbc)) != 0)
                        return (ret);
                return (hcp->opd->c_am_put(hcp->opd,
                    NULL, nval, flags, NULL));
        }

        /* There are two separate cases here: on page and off page. */
        if (HPAGE_PTYPE(hk) != H_OFFDUP) {
                if (HPAGE_PTYPE(hk) != H_DUPLICATE) {
                        pval.flags = 0;
                        pval.data = HKEYDATA_DATA(hk);
                        pval.size = LEN_HDATA(dbp, hcp->page, dbp->pgsize,
                            hcp->indx);
                        if ((ret = __ham_make_dup(dbp->dbenv,
                            &pval, &tmp_val, &dbc->my_rdata.data,
                            &dbc->my_rdata.ulen)) != 0 || (ret =
                            __ham_replpair(dbc, &tmp_val, 1)) != 0)
                                return (ret);
                        hk = H_PAIRDATA(dbp, hcp->page, hcp->indx);
                        HPAGE_PTYPE(hk) = H_DUPLICATE;

                        /*
                         * Update the cursor position since we now are in
                         * duplicates.
                         */
                        F_SET(hcp, H_ISDUP);
                        hcp->dup_off = 0;
                        hcp->dup_len = pval.size;
                        hcp->dup_tlen = DUP_SIZE(hcp->dup_len);
                }

                /* Now make the new entry a duplicate. */
                if ((ret = __ham_make_dup(dbp->dbenv, nval,
                    &tmp_val, &dbc->my_rdata.data, &dbc->my_rdata.ulen)) != 0)
                        return (ret);

                tmp_val.dlen = 0;
                switch (flags) {                        /* On page. */
                case DB_KEYFIRST:
                case DB_KEYLAST:
                case DB_NODUPDATA:
                        if (dbp->dup_compare != NULL) {
                                __ham_dsearch(dbc,
                                    nval, &tmp_val.doff, &cmp, flags);

                                /* dup dups are not supported w/ sorted dups */
                                if (cmp == 0)
                                        return (__db_duperr(dbp, flags));
                        } else {
                                hcp->dup_tlen = LEN_HDATA(dbp, hcp->page,
                                    dbp->pgsize, hcp->indx);
                                hcp->dup_len = nval->size;
                                F_SET(hcp, H_ISDUP);
                                if (flags == DB_KEYFIRST)
                                        hcp->dup_off = tmp_val.doff = 0;
                                else
                                        hcp->dup_off =
                                            tmp_val.doff = hcp->dup_tlen;
                        }
                        break;
                case DB_BEFORE:
                        tmp_val.doff = hcp->dup_off;
                        break;
                case DB_AFTER:
                        tmp_val.doff = hcp->dup_off + DUP_SIZE(hcp->dup_len);
                        break;
                default:
                        DB_ASSERT(0);
                        return (EINVAL);
                }

                /* Add the duplicate. */
                ret = __ham_replpair(dbc, &tmp_val, 0);
                if (ret == 0)
                        ret = __memp_fset(mpf, hcp->page, DB_MPOOL_DIRTY);
                if (ret != 0)
                        return (ret);

                /* Now, update the cursor if necessary. */
                switch (flags) {
                case DB_AFTER:
                        hcp->dup_off += DUP_SIZE(hcp->dup_len);
                        hcp->dup_len = nval->size;
                        hcp->dup_tlen += (db_indx_t)DUP_SIZE(nval->size);
                        break;
                case DB_BEFORE:
                case DB_KEYFIRST:
                case DB_KEYLAST:
                case DB_NODUPDATA:
                        hcp->dup_tlen += (db_indx_t)DUP_SIZE(nval->size);
                        hcp->dup_len = nval->size;
                        break;
                default:
                        DB_ASSERT(0);
                        return (EINVAL);
                }
                ret = __ham_c_update(dbc, tmp_val.size, 1, 1);
                return (ret);
        }

        /*
         * If we get here, then we're on duplicate pages; set pgnop and
         * return so the common code can handle it.
         */
        memcpy(pgnop, HOFFDUP_PGNO(H_PAIRDATA(dbp, hcp->page, hcp->indx)),
            sizeof(db_pgno_t));

        return (ret);
}

/*
 * Convert an on-page set of duplicates to an offpage set of duplicates.
 *
 * PUBLIC: int __ham_dup_convert __P((DBC *));
 */
int
__ham_dup_convert(dbc)
        DBC *dbc;
{
        BOVERFLOW bo;
        DB *dbp;
        DBC **hcs;
        DBT dbt;
        DB_LSN lsn;
        DB_MPOOLFILE *mpf;
        HASH_CURSOR *hcp;
        HOFFPAGE ho;
        PAGE *dp;
        db_indx_t i, len, off;
        int c, ret, t_ret;
        u_int8_t *p, *pend;

        dbp = dbc->dbp;
        mpf = dbp->mpf;
        hcp = (HASH_CURSOR *)dbc->internal;

        /*
         * Create a new page for the duplicates.
         */
        if ((ret = __db_new(dbc,
            dbp->dup_compare == NULL ? P_LRECNO : P_LDUP, &dp)) != 0)
                return (ret);
        P_INIT(dp, dbp->pgsize,
            dp->pgno, PGNO_INVALID, PGNO_INVALID, LEAFLEVEL, TYPE(dp));

        /*
         * Get the list of cursors that may need to be updated.
         */
        if ((ret = __ham_get_clist(dbp,
            PGNO(hcp->page), (u_int32_t)hcp->indx, &hcs)) != 0)
                goto err;

        /*
         * Now put the duplicates onto the new page.
         */
        dbt.flags = 0;
        switch (HPAGE_PTYPE(H_PAIRDATA(dbp, hcp->page, hcp->indx))) {
        case H_KEYDATA:
                /* Simple case, one key on page; move it to dup page. */
                dbt.size = LEN_HDATA(dbp, hcp->page, dbp->pgsize, hcp->indx);
                dbt.data = HKEYDATA_DATA(H_PAIRDATA(dbp, hcp->page, hcp->indx));
                ret = __db_pitem(dbc,
                    dp, 0, BKEYDATA_SIZE(dbt.size), NULL, &dbt);
                goto finish;
        case H_OFFPAGE:
                /* Simple case, one key on page; move it to dup page. */
                memcpy(&ho, P_ENTRY(dbp, hcp->page, H_DATAINDEX(hcp->indx)),
                    HOFFPAGE_SIZE);
                UMRW_SET(bo.unused1);
                B_TSET(bo.type, ho.type, 0);
                UMRW_SET(bo.unused2);
                bo.pgno = ho.pgno;
                bo.tlen = ho.tlen;
                dbt.size = BOVERFLOW_SIZE;
                dbt.data = &bo;

                ret = __db_pitem(dbc, dp, 0, dbt.size, &dbt, NULL);
finish:         if (ret == 0) {
                        if ((ret = __memp_fset(mpf, dp, DB_MPOOL_DIRTY)) != 0)
                                break;

                        /* Update any other cursors. */
                        if (hcs != NULL && DBC_LOGGING(dbc) &&
                            IS_SUBTRANSACTION(dbc->txn)) {
                                if ((ret = __ham_chgpg_log(dbp, dbc->txn,
                                    &lsn, 0, DB_HAM_DUP, PGNO(hcp->page),
                                    PGNO(dp), hcp->indx, 0)) != 0)
                                        break;
                        }
                        for (c = 0; hcs != NULL && hcs[c] != NULL; c++)
                                if ((ret = __ham_dcursor(hcs[c],
                                    PGNO(dp), 0)) != 0)
                                        break;
                }
                break;
        case H_DUPLICATE:
                p = HKEYDATA_DATA(H_PAIRDATA(dbp, hcp->page, hcp->indx));
                pend = p +
                    LEN_HDATA(dbp, hcp->page, dbp->pgsize, hcp->indx);

                /*
                 * We need to maintain the duplicate cursor position.
                 * Keep track of where we are in the duplicate set via
                 * the offset, and when it matches the one in the cursor,
                 * set the off-page duplicate cursor index to the current
                 * index.
                 */
                for (off = 0, i = 0; p < pend; i++) {
                        memcpy(&len, p, sizeof(db_indx_t));
                        dbt.size = len;
                        p += sizeof(db_indx_t);
                        dbt.data = p;
                        p += len + sizeof(db_indx_t);
                        if ((ret = __db_pitem(dbc, dp,
                            i, BKEYDATA_SIZE(dbt.size), NULL, &dbt)) != 0)
                                break;

                        /* Update any other cursors */
                        if (hcs != NULL && DBC_LOGGING(dbc) &&
                            IS_SUBTRANSACTION(dbc->txn)) {
                                if ((ret = __ham_chgpg_log(dbp, dbc->txn,
                                    &lsn, 0, DB_HAM_DUP, PGNO(hcp->page),
                                    PGNO(dp), hcp->indx, i)) != 0)
                                        break;
                        }
                        for (c = 0; hcs != NULL && hcs[c] != NULL; c++)
                                if (((HASH_CURSOR *)(hcs[c]->internal))->dup_off
                                    == off && (ret = __ham_dcursor(hcs[c],
                                    PGNO(dp), i)) != 0)
                                        goto err;
                        off += len + 2 * sizeof(db_indx_t);
                }
                break;
        default:
                ret = __db_pgfmt(dbp->dbenv, hcp->pgno);
                break;
        }

        /*
         * Now attach this to the source page in place of the old duplicate
         * item.
         */
        if (ret == 0)
                ret = __ham_move_offpage(dbc, hcp->page,
                    (u_int32_t)H_DATAINDEX(hcp->indx), PGNO(dp));

err:    if (ret == 0)
                ret = __memp_fset(mpf, hcp->page, DB_MPOOL_DIRTY);

        if ((t_ret = __memp_fput(
            mpf, dp, ret == 0 ? DB_MPOOL_DIRTY : 0)) != 0 && ret == 0)
                ret = t_ret;

        if (ret == 0)
                hcp->dup_tlen = hcp->dup_off = hcp->dup_len = 0;

        if (hcs != NULL)
                __os_free(dbp->dbenv, hcs);

        return (ret);
}

/*
 * __ham_make_dup
 *
 * Take a regular dbt and make it into a duplicate item with all the partial
 * information set appropriately. If the incoming dbt is a partial, assume
 * we are creating a new entry and make sure that we do any initial padding.
 *
 * PUBLIC: int __ham_make_dup __P((DB_ENV *,
 * PUBLIC:     const DBT *, DBT *d, void **, u_int32_t *));
 */
int
__ham_make_dup(dbenv, notdup, duplicate, bufp, sizep)
        DB_ENV *dbenv;
        const DBT *notdup;
        DBT *duplicate;
        void **bufp;
        u_int32_t *sizep;
{
        db_indx_t tsize, item_size;
        int ret;
        u_int8_t *p;

        item_size = (db_indx_t)notdup->size;
        if (F_ISSET(notdup, DB_DBT_PARTIAL))
                item_size += notdup->doff;

        tsize = DUP_SIZE(item_size);
        if ((ret = __ham_init_dbt(dbenv, duplicate, tsize, bufp, sizep)) != 0)
                return (ret);

        duplicate->dlen = 0;
        duplicate->flags = notdup->flags;
        F_SET(duplicate, DB_DBT_PARTIAL);

        p = duplicate->data;
        memcpy(p, &item_size, sizeof(db_indx_t));
        p += sizeof(db_indx_t);
        if (F_ISSET(notdup, DB_DBT_PARTIAL)) {
                memset(p, 0, notdup->doff);
                p += notdup->doff;
        }
        memcpy(p, notdup->data, notdup->size);
        p += notdup->size;
        memcpy(p, &item_size, sizeof(db_indx_t));

        duplicate->doff = 0;
        duplicate->dlen = notdup->size;

        return (0);
}

/*
 * __ham_check_move --
 *
 * Check if we can do whatever we need to on this page.  If not,
 * then we'll have to move the current element to a new page.
 */
static int
__ham_check_move(dbc, add_len)
        DBC *dbc;
        u_int32_t add_len;
{
        DB *dbp;
        DBT k, d;
        DB_LSN new_lsn;
        DB_MPOOLFILE *mpf;
        HASH_CURSOR *hcp;
        PAGE *next_pagep;
        db_pgno_t next_pgno;
        u_int32_t new_datalen, old_len, rectype;
        u_int8_t *hk;
        int ret;

        dbp = dbc->dbp;
        mpf = dbp->mpf;
        hcp = (HASH_CURSOR *)dbc->internal;

        hk = H_PAIRDATA(dbp, hcp->page, hcp->indx);

        /*
         * If the item is already off page duplicates or an offpage item,
         * then we know we can do whatever we need to do in-place
         */
        if (HPAGE_PTYPE(hk) == H_OFFDUP || HPAGE_PTYPE(hk) == H_OFFPAGE)
                return (0);

        old_len =
            LEN_HITEM(dbp, hcp->page, dbp->pgsize, H_DATAINDEX(hcp->indx));
        new_datalen = (old_len - HKEYDATA_SIZE(0)) + add_len;
        if (HPAGE_PTYPE(hk) != H_DUPLICATE)
                new_datalen += DUP_SIZE(0);

        /*
         * We need to add a new page under two conditions:
         * 1. The addition makes the total data length cross the BIG
         *    threshold and the OFFDUP structure won't fit on this page.
         * 2. The addition does not make the total data cross the
         *    threshold, but the new data won't fit on the page.
         * If neither of these is true, then we can return.
         */
        if (ISBIG(hcp, new_datalen) && (old_len > HOFFDUP_SIZE ||
            HOFFDUP_SIZE - old_len <= P_FREESPACE(dbp, hcp->page)))
                return (0);

        if (!ISBIG(hcp, new_datalen) &&
            (new_datalen - old_len) <= P_FREESPACE(dbp, hcp->page))
                return (0);

        /*
         * If we get here, then we need to move the item to a new page.
         * Check if there are more pages in the chain.  We now need to
         * update new_datalen to include the size of both the key and
         * the data that we need to move.
         */

        new_datalen = ISBIG(hcp, new_datalen) ?
            HOFFDUP_SIZE : HKEYDATA_SIZE(new_datalen);
        new_datalen +=
            LEN_HITEM(dbp, hcp->page, dbp->pgsize, H_KEYINDEX(hcp->indx));

        next_pagep = NULL;
        for (next_pgno = NEXT_PGNO(hcp->page); next_pgno != PGNO_INVALID;
            next_pgno = NEXT_PGNO(next_pagep)) {
                if (next_pagep != NULL &&
                    (ret = __memp_fput(mpf, next_pagep, 0)) != 0)
                        return (ret);

                if ((ret = __memp_fget(mpf,
                    &next_pgno, DB_MPOOL_CREATE, &next_pagep)) != 0)
                        return (ret);

                if (P_FREESPACE(dbp, next_pagep) >= new_datalen)
                        break;
        }

        /* No more pages, add one. */
        if (next_pagep == NULL && (ret = __ham_add_ovflpage(dbc,
            hcp->page, 0, &next_pagep)) != 0)
                return (ret);

        /* Add new page at the end of the chain. */
        if (P_FREESPACE(dbp, next_pagep) < new_datalen && (ret =
            __ham_add_ovflpage(dbc, next_pagep, 1, &next_pagep)) != 0) {
                (void)__memp_fput(mpf, next_pagep, 0);
                return (ret);
        }

        /* Copy the item to the new page. */
        if (DBC_LOGGING(dbc)) {
                rectype = PUTPAIR;
                k.flags = 0;
                d.flags = 0;
                if (HPAGE_PTYPE(
                    H_PAIRKEY(dbp, hcp->page, hcp->indx)) == H_OFFPAGE) {
                        rectype |= PAIR_KEYMASK;
                        k.data = H_PAIRKEY(dbp, hcp->page, hcp->indx);
                        k.size = HOFFPAGE_SIZE;
                } else {
                        k.data =
                            HKEYDATA_DATA(H_PAIRKEY(dbp, hcp->page, hcp->indx));
                        k.size =
                            LEN_HKEY(dbp, hcp->page, dbp->pgsize, hcp->indx);
                }

                if (HPAGE_PTYPE(hk) == H_OFFPAGE) {
                        rectype |= PAIR_DATAMASK;
                        d.data = H_PAIRDATA(dbp, hcp->page, hcp->indx);
                        d.size = HOFFPAGE_SIZE;
                } else {
                        if (HPAGE_PTYPE(H_PAIRDATA(dbp,
                            hcp->page, hcp->indx)) == H_DUPLICATE)
                                rectype |= PAIR_DUPMASK;
                        d.data = HKEYDATA_DATA(
                            H_PAIRDATA(dbp, hcp->page, hcp->indx));
                        d.size = LEN_HDATA(dbp, hcp->page,
                            dbp->pgsize, hcp->indx);
                }

                if ((ret = __ham_insdel_log(dbp,
                    dbc->txn, &new_lsn, 0, rectype, PGNO(next_pagep),
                    (u_int32_t)NUM_ENT(next_pagep), &LSN(next_pagep),
                    &k, &d)) != 0) {
                        (void)__memp_fput(mpf, next_pagep, 0);
                        return (ret);
                }
        } else
                LSN_NOT_LOGGED(new_lsn);

        /* Move lsn onto page. */
        LSN(next_pagep) = new_lsn;      /* Structure assignment. */

        __ham_copy_item(dbp, hcp->page, H_KEYINDEX(hcp->indx), next_pagep);
        __ham_copy_item(dbp, hcp->page, H_DATAINDEX(hcp->indx), next_pagep);

        /*
         * We've just manually inserted a key and set of data onto
         * next_pagep;  however, it's possible that our caller will
         * return without further modifying the new page, for instance
         * if DB_NODUPDATA is set and our new item is a duplicate duplicate.
         * Thus, to be on the safe side, we need to mark the page dirty
         * here. [#2996]
         *
         * Note that __ham_del_pair should dirty the page we're moving
         * the items from, so we need only dirty the new page ourselves.
         */
        if ((ret = __memp_fset(mpf, next_pagep, DB_MPOOL_DIRTY)) != 0)
                goto out;

        /* Update all cursors that used to point to this item. */
        if ((ret = __ham_c_chgpg(dbc, PGNO(hcp->page), H_KEYINDEX(hcp->indx),
            PGNO(next_pagep), NUM_ENT(next_pagep) - 2)) != 0)
                goto out;

        /* Now delete the pair from the current page. */
        ret = __ham_del_pair(dbc, 0);

        /*
         * __ham_del_pair decremented nelem.  This is incorrect;  we
         * manually copied the element elsewhere, so the total number
         * of elements hasn't changed.  Increment it again.
         *
         * !!!
         * Note that we still have the metadata page pinned, and
         * __ham_del_pair dirtied it, so we don't need to set the dirty
         * flag again.
         */
        if (!STD_LOCKING(dbc))
                hcp->hdr->nelem++;

out:
        (void)__memp_fput(mpf, hcp->page, DB_MPOOL_DIRTY);
        hcp->page = next_pagep;
        hcp->pgno = PGNO(hcp->page);
        hcp->indx = NUM_ENT(hcp->page) - 2;
        F_SET(hcp, H_EXPAND);
        F_CLR(hcp, H_DELETED);

        return (ret);
}

/*
 * __ham_move_offpage --
 *      Replace an onpage set of duplicates with the OFFDUP structure
 *      that references the duplicate page.
 *
 * XXX
 * This is really just a special case of __onpage_replace; we should
 * probably combine them.
 *
 */
static int
__ham_move_offpage(dbc, pagep, ndx, pgno)
        DBC *dbc;
        PAGE *pagep;
        u_int32_t ndx;
        db_pgno_t pgno;
{
        DB *dbp;
        DBT new_dbt;
        DBT old_dbt;
        HOFFDUP od;
        db_indx_t i, *inp;
        int32_t difflen;
        u_int8_t *src;
        int ret;

        dbp = dbc->dbp;
        od.type = H_OFFDUP;
        UMRW_SET(od.unused[0]);
        UMRW_SET(od.unused[1]);
        UMRW_SET(od.unused[2]);
        od.pgno = pgno;
        ret = 0;

        if (DBC_LOGGING(dbc)) {
                new_dbt.data = &od;
                new_dbt.size = HOFFDUP_SIZE;
                old_dbt.data = P_ENTRY(dbp, pagep, ndx);
                old_dbt.size = LEN_HITEM(dbp, pagep, dbp->pgsize, ndx);
                if ((ret = __ham_replace_log(dbp, dbc->txn, &LSN(pagep), 0,
                    PGNO(pagep), (u_int32_t)ndx, &LSN(pagep), -1,
                    &old_dbt, &new_dbt, 0)) != 0)
                        return (ret);
        } else
                LSN_NOT_LOGGED(LSN(pagep));

        /*
         * difflen is the difference in the lengths, and so may be negative.
         * We know that the difference between two unsigned lengths from a
         * database page will fit into an int32_t.
         */
        difflen =
            (int32_t)LEN_HITEM(dbp, pagep, dbp->pgsize, ndx) -
            (int32_t)HOFFDUP_SIZE;
        if (difflen != 0) {
                /* Copy data. */
                inp = P_INP(dbp, pagep);
                src = (u_int8_t *)(pagep) + HOFFSET(pagep);
                memmove(src + difflen, src, inp[ndx] - HOFFSET(pagep));
                HOFFSET(pagep) += difflen;

                /* Update index table. */
                for (i = ndx; i < NUM_ENT(pagep); i++)
                        inp[i] += difflen;
        }

        /* Now copy the offdup entry onto the page. */
        memcpy(P_ENTRY(dbp, pagep, ndx), &od, HOFFDUP_SIZE);
        return (ret);
}

/*
 * __ham_dsearch:
 *      Locate a particular duplicate in a duplicate set.  Make sure that
 *      we exit with the cursor set appropriately.
 *
 * PUBLIC: void __ham_dsearch
 * PUBLIC:     __P((DBC *, DBT *, u_int32_t *, int *, u_int32_t));
 */
void
__ham_dsearch(dbc, dbt, offp, cmpp, flags)
        DBC *dbc;
        DBT *dbt;
        u_int32_t *offp, flags;
        int *cmpp;
{
        DB *dbp;
        HASH_CURSOR *hcp;
        DBT cur;
        db_indx_t i, len;
        int (*func) __P((DB *, const DBT *, const DBT *));
        u_int8_t *data;

        dbp = dbc->dbp;
        hcp = (HASH_CURSOR *)dbc->internal;
        func = dbp->dup_compare == NULL ? __bam_defcmp : dbp->dup_compare;

        i = F_ISSET(hcp, H_CONTINUE) ? hcp->dup_off: 0;
        data = HKEYDATA_DATA(H_PAIRDATA(dbp, hcp->page, hcp->indx)) + i;
        hcp->dup_tlen = LEN_HDATA(dbp, hcp->page, dbp->pgsize, hcp->indx);
        len = hcp->dup_len;
        while (i < hcp->dup_tlen) {
                memcpy(&len, data, sizeof(db_indx_t));
                data += sizeof(db_indx_t);
                cur.data = data;
                cur.size = (u_int32_t)len;

                /*
                 * If we find an exact match, we're done.  If in a sorted
                 * duplicate set and the item is larger than our test item,
                 * we're done.  In the latter case, if permitting partial
                 * matches, it's not a failure.
                 */
                *cmpp = func(dbp, dbt, &cur);
                if (*cmpp == 0)
                        break;
                if (*cmpp < 0 && dbp->dup_compare != NULL) {
                        if (flags == DB_GET_BOTH_RANGE)
                                *cmpp = 0;
                        break;
                }

                i += len + 2 * sizeof(db_indx_t);
                data += len + sizeof(db_indx_t);
        }

        *offp = i;
        hcp->dup_off = i;
        hcp->dup_len = len;
        F_SET(hcp, H_ISDUP);
}

/*
 * __ham_dcursor --
 *
 *      Create an off page duplicate cursor for this cursor.
 */
static int
__ham_dcursor(dbc, pgno, indx)
        DBC *dbc;
        db_pgno_t pgno;
        u_int32_t indx;
{
        DB *dbp;
        HASH_CURSOR *hcp;
        BTREE_CURSOR *dcp;
        int ret;

        dbp = dbc->dbp;
        hcp = (HASH_CURSOR *)dbc->internal;

        if ((ret = __db_c_newopd(dbc, pgno, hcp->opd, &hcp->opd)) != 0)
                return (ret);

        dcp = (BTREE_CURSOR *)hcp->opd->internal;
        dcp->pgno = pgno;
        dcp->indx = indx;

        if (dbp->dup_compare == NULL) {
                /*
                 * Converting to off-page Recno trees is tricky.  The
                 * record number for the cursor is the index + 1 (to
                 * convert to 1-based record numbers).
                 */
                dcp->recno = indx + 1;
        }

        /*
         * Transfer the deleted flag from the top-level cursor to the
         * created one.
         */
        if (F_ISSET(hcp, H_DELETED)) {
                F_SET(dcp, C_DELETED);
                F_CLR(hcp, H_DELETED);
        }

        return (0);
}

/*
 * __ham_c_chgpg --
 *      Adjust the cursors after moving an item to a new page.  We only
 *      move cursors that are pointing at this one item and are not
 *      deleted;  since we only touch non-deleted cursors, and since
 *      (by definition) no item existed at the pgno/indx we're moving the
 *      item to, we're guaranteed that all the cursors we affect here or
 *      on abort really do refer to this one item.
 */
static int
__ham_c_chgpg(dbc, old_pgno, old_index, new_pgno, new_index)
        DBC *dbc;
        db_pgno_t old_pgno, new_pgno;
        u_int32_t old_index, new_index;
{
        DB *dbp, *ldbp;
        DB_ENV *dbenv;
        DB_LSN lsn;
        DB_TXN *my_txn;
        DBC *cp;
        HASH_CURSOR *hcp;
        int found, ret;

        dbp = dbc->dbp;
        dbenv = dbp->dbenv;

        my_txn = IS_SUBTRANSACTION(dbc->txn) ? dbc->txn : NULL;
        found = 0;

        MUTEX_LOCK(dbenv, dbenv->mtx_dblist);
        for (ldbp = __dblist_get(dbenv, dbp->adj_fileid);
            ldbp != NULL && ldbp->adj_fileid == dbp->adj_fileid;
            ldbp = LIST_NEXT(ldbp, dblistlinks)) {
                MUTEX_LOCK(dbenv, dbp->mutex);
                for (cp = TAILQ_FIRST(&ldbp->active_queue); cp != NULL;
                    cp = TAILQ_NEXT(cp, links)) {
                        if (cp == dbc || cp->dbtype != DB_HASH)
                                continue;

                        hcp = (HASH_CURSOR *)cp->internal;

                        /*
                         * If a cursor is deleted, it doesn't refer to this
                         * item--it just happens to have the same indx, but
                         * it points to a former neighbor.  Don't move it.
                         */
                        if (F_ISSET(hcp, H_DELETED))
                                continue;

                        if (hcp->pgno == old_pgno) {
                                if (hcp->indx == old_index) {
                                        hcp->pgno = new_pgno;
                                        hcp->indx = new_index;
                                } else
                                        continue;
                                if (my_txn != NULL && cp->txn != my_txn)
                                        found = 1;
                        }
                }
                MUTEX_UNLOCK(dbenv, dbp->mutex);
        }
        MUTEX_UNLOCK(dbenv, dbenv->mtx_dblist);

        if (found != 0 && DBC_LOGGING(dbc)) {
                if ((ret = __ham_chgpg_log(dbp, my_txn, &lsn, 0, DB_HAM_CHGPG,
                    old_pgno, new_pgno, old_index, new_index)) != 0)
                        return (ret);
        }
        return (0);
}

---