hash_page.c

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/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1996, 1997, 1998, 1999, 2000
 *      Sleepycat Software.  All rights reserved.
 */
/*
 * Copyright (c) 1990, 1993, 1994
 *      Margo Seltzer.  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.
 */

#include "config.h"

#ifndef lint
static const char revid[] = "$Id: hash__page_8c-source.html,v 1.1 2008/06/08 10:19:34 sebdiaz Exp $";
#endif /* not lint */

/*
 * PACKAGE:  hashing
 *
 * DESCRIPTION:
 *      Page manipulation for hashing package.
 *
 * ROUTINES:
 *
 * External
 *      __get_page
 *      __add_ovflpage
 *      __overflow_page
 * Internal
 *      open_temp
 */

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

#include <errno.h>
#include <string.h>
#endif

#include "db_int.h"
#include "db_page.h"
#include "db_shash.h"
#include "hash.h"
#include "lock.h"
#include "txn.h"

/*
 * PUBLIC: int CDB___ham_item __P((DBC *, db_lockmode_t, db_pgno_t *));
 */
int
CDB___ham_item(dbc, mode, pgnop)
        DBC *dbc;
        db_lockmode_t mode;
        db_pgno_t *pgnop;
{
        DB *dbp;
        HASH_CURSOR *hcp;
        db_pgno_t next_pgno;
        int ret;

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

        if (F_ISSET(hcp, H_DELETED)) {
                CDB___db_err(dbp->dbenv, "Attempt to return a deleted item");
                return (EINVAL);
        }
        F_CLR(hcp, H_OK | H_NOMORE);

        /* Check if we need to get a page for this cursor. */
        if ((ret = CDB___ham_get_cpage(dbc, mode)) != 0)
                return (ret);

recheck:
        /* Check if we are looking for space in which to insert an item. */
        if (hcp->seek_size && hcp->seek_found_page == PGNO_INVALID
            && hcp->seek_size < P_FREESPACE(hcp->page))
                hcp->seek_found_page = hcp->pgno;

        /* Check for off-page duplicates. */
        if (hcp->indx < NUM_ENT(hcp->page) &&
            HPAGE_TYPE(hcp->page, H_DATAINDEX(hcp->indx)) == H_OFFDUP) {
                memcpy(pgnop,
                    HOFFDUP_PGNO(H_PAIRDATA(hcp->page, hcp->indx)),
                    sizeof(db_pgno_t));
                F_SET(hcp, H_OK);
                return (0);
        }

        /* Check if we need to go on to the next page. */
        if (F_ISSET(hcp, H_ISDUP))
                /*
                 * ISDUP is set, and offset is at the beginning of the datum.
                 * We need to grab the length of the datum, then set the datum
                 * pointer to be the beginning of the datum.
                 */
                memcpy(&hcp->dup_len,
                    HKEYDATA_DATA(H_PAIRDATA(hcp->page, hcp->indx)) +
                    hcp->dup_off, sizeof(db_indx_t));

        if (hcp->indx >= (db_indx_t)NUM_ENT(hcp->page)) {
                /* Fetch next page. */
                if (NEXT_PGNO(hcp->page) == PGNO_INVALID) {
                        F_SET(hcp, H_NOMORE);
                        return (DB_NOTFOUND);
                }
                next_pgno = NEXT_PGNO(hcp->page);
                hcp->indx = 0;
                if ((ret = CDB___ham_next_cpage(dbc, next_pgno, 0)) != 0)
                        return (ret);
                goto recheck;
        }

        F_SET(hcp, H_OK);
        return (0);
}

/*
 * PUBLIC: int CDB___ham_item_reset __P((DBC *));
 */
int
CDB___ham_item_reset(dbc)
        DBC *dbc;
{
        HASH_CURSOR *hcp;
        DB *dbp;
        int ret;

        ret = 0;
        dbp = dbc->dbp;
        hcp = (HASH_CURSOR *)dbc->internal;
        if (hcp->page != NULL)
                ret = CDB___ham_put_page(dbp, hcp->page, 0);

        CDB___ham_item_init(dbc);
        return (ret);
}

/*
 * PUBLIC: void CDB___ham_item_init __P((DBC *));
 */
void
CDB___ham_item_init(dbc)
        DBC *dbc;
{
        HASH_CURSOR *hcp;

        hcp = (HASH_CURSOR *)dbc->internal;
        /*
         * If this cursor still holds any locks, we must
         * release them if we are not running with transactions.
         */
        if (hcp->lock.off != LOCK_INVALID && dbc->txn == NULL)
            (void)CDB_lock_put(dbc->dbp->dbenv, &hcp->lock);

        /*
         * The following fields must *not* be initialized here
         * because they may have meaning across inits.
         *      hlock, hdr, split_buf, stats
         */
        hcp->bucket = BUCKET_INVALID;
        hcp->lbucket = BUCKET_INVALID;
        hcp->lock.off = LOCK_INVALID;
        hcp->lock_mode = DB_LOCK_NG;
        hcp->dup_off = 0;
        hcp->dup_len = 0;
        hcp->dup_tlen = 0;
        hcp->seek_size = 0;
        hcp->seek_found_page = PGNO_INVALID;
        hcp->flags = 0;

        hcp->pgno = PGNO_INVALID;
        hcp->indx = NDX_INVALID;
        hcp->page = NULL;
}

/*
 * Returns the last item in a bucket.
 *
 * PUBLIC: int CDB___ham_item_last __P((DBC *, db_lockmode_t, db_pgno_t *));
 */
int
CDB___ham_item_last(dbc, mode, pgnop)
        DBC *dbc;
        db_lockmode_t mode;
        db_pgno_t *pgnop;
{
        HASH_CURSOR *hcp;
        int ret;

        hcp = (HASH_CURSOR *)dbc->internal;
        if ((ret = CDB___ham_item_reset(dbc)) != 0)
                return (ret);

        hcp->bucket = hcp->hdr->max_bucket;
        hcp->pgno = BUCKET_TO_PAGE(hcp, hcp->bucket);
        F_SET(hcp, H_OK);
        return (CDB___ham_item_prev(dbc, mode, pgnop));
}

/*
 * PUBLIC: int CDB___ham_item_first __P((DBC *, db_lockmode_t, db_pgno_t *));
 */
int
CDB___ham_item_first(dbc, mode, pgnop)
        DBC *dbc;
        db_lockmode_t mode;
        db_pgno_t *pgnop;
{
        HASH_CURSOR *hcp;
        int ret;

        hcp = (HASH_CURSOR *)dbc->internal;
        if ((ret = CDB___ham_item_reset(dbc)) != 0)
                return (ret);
        F_SET(hcp, H_OK);
        hcp->bucket = 0;
        hcp->pgno = BUCKET_TO_PAGE(hcp, hcp->bucket);
        return (CDB___ham_item_next(dbc, mode, pgnop));
}

/*
 * CDB___ham_item_prev --
 *      Returns a pointer to key/data pair on a page.  In the case of
 *      bigkeys, just returns the page number and index of the bigkey
 *      pointer pair.
 *
 * PUBLIC: int CDB___ham_item_prev __P((DBC *, db_lockmode_t, db_pgno_t *));
 */
int
CDB___ham_item_prev(dbc, mode, pgnop)
        DBC *dbc;
        db_lockmode_t mode;
        db_pgno_t *pgnop;
{
        DB *dbp;
        HASH_CURSOR *hcp;
        db_pgno_t next_pgno;
        int ret;

        dbp = dbc->dbp;
        hcp = (HASH_CURSOR *)dbc->internal;
        /*
         * There are 5 cases for backing up in a hash file.
         * Case 1: In the middle of a page, no duplicates, just dec the index.
         * Case 2: In the middle of a duplicate set, back up one.
         * Case 3: At the beginning of a duplicate set, get out of set and
         *      back up to next key.
         * Case 4: At the beginning of a page; go to previous page.
         * Case 5: At the beginning of a bucket; go to prev bucket.
         */
        F_CLR(hcp, H_OK | H_NOMORE | H_DELETED);

        if ((ret = CDB___ham_get_cpage(dbc, mode)) != 0)
                return (ret);

        /*
         * First handle the duplicates.  Either you'll get the key here
         * or you'll exit the duplicate set and drop into the code below
         * to handle backing up through keys.
         */
        if (!F_ISSET(hcp, H_NEXT_NODUP) && F_ISSET(hcp, H_ISDUP)) {
                if (HPAGE_TYPE(hcp->page, H_DATAINDEX(hcp->indx)) == H_OFFDUP) {
                        memcpy(pgnop,
                            HOFFDUP_PGNO(H_PAIRDATA(hcp->page, hcp->indx)),
                            sizeof(db_pgno_t));
                        F_SET(hcp, H_OK);
                        return (0);
                }

                /* Duplicates are on-page. */
                if (hcp->dup_off != 0) {
                        memcpy(&hcp->dup_len, HKEYDATA_DATA(
                            H_PAIRDATA(hcp->page, hcp->indx))
                            + hcp->dup_off - sizeof(db_indx_t),
                            sizeof(db_indx_t));
                        hcp->dup_off -=
                            DUP_SIZE(hcp->dup_len);
                        return (CDB___ham_item(dbc, mode, pgnop));
                }
        }

        /*
         * If we get here, we are not in a duplicate set, and just need
         * to back up the cursor.  There are still three cases:
         * midpage, beginning of page, beginning of bucket.
         */

        if (F_ISSET(hcp, H_DUPONLY)) {
                F_CLR(hcp, H_OK);
                F_SET(hcp, H_NOMORE);
                return (0);
        } else
                /*
                 * We are no longer in a dup set;  flag this so the dup code
                 * will reinitialize should we stumble upon another one.
                 */
                F_CLR(hcp, H_ISDUP);

        if (hcp->indx == 0) {           /* Beginning of page. */
                hcp->pgno = PREV_PGNO(hcp->page);
                if (hcp->pgno == PGNO_INVALID) {
                        /* Beginning of bucket. */
                        F_SET(hcp, H_NOMORE);
                        return (DB_NOTFOUND);
                } else if ((ret =
                    CDB___ham_next_cpage(dbc, hcp->pgno, 0)) != 0)
                        return (ret);
                else
                        hcp->indx = NUM_ENT(hcp->page);
        }

        /*
         * Either we've got the cursor set up to be decremented, or we
         * have to find the end of a bucket.
         */
        if (hcp->indx == NDX_INVALID) {
                DB_ASSERT(hcp->page != NULL);

                hcp->indx = NUM_ENT(hcp->page);
                for (next_pgno = NEXT_PGNO(hcp->page);
                    next_pgno != PGNO_INVALID;
                    next_pgno = NEXT_PGNO(hcp->page)) {
                        if ((ret = CDB___ham_next_cpage(dbc, next_pgno, 0)) != 0)
                                return (ret);
                        hcp->indx = NUM_ENT(hcp->page);
                }

                if (hcp->indx == 0) {
                        /* Bucket was empty. */
                        F_SET(hcp, H_NOMORE);
                        return (DB_NOTFOUND);
                }
        }

        hcp->indx -= 2;

        return (CDB___ham_item(dbc, mode, pgnop));
}

/*
 * Sets the cursor to the next key/data pair on a page.
 *
 * PUBLIC: int CDB___ham_item_next __P((DBC *, db_lockmode_t, db_pgno_t *));
 */
int
CDB___ham_item_next(dbc, mode, pgnop)
        DBC *dbc;
        db_lockmode_t mode;
        db_pgno_t *pgnop;
{
        HASH_CURSOR *hcp;
        int ret;

        hcp = (HASH_CURSOR *)dbc->internal;

        if ((ret = CDB___ham_get_cpage(dbc, mode)) != 0)
                return (ret);

        /*
         * Deleted on-page duplicates are a weird case. If we delete the last
         * one, then our cursor is at the very end of a duplicate set and
         * we actually need to go on to the next key.
         */
        if (F_ISSET(hcp, H_DELETED)) {
                if (hcp->indx != NDX_INVALID &&
                    F_ISSET(hcp, H_ISDUP) &&
                    HPAGE_TYPE(hcp->page, H_DATAINDEX(hcp->indx))
                        == H_DUPLICATE && hcp->dup_tlen == hcp->dup_off) {
                        if (F_ISSET(hcp, H_DUPONLY)) {
                                F_CLR(hcp, H_OK);
                                F_SET(hcp, H_NOMORE);
                                return (0);
                        } else {
                                F_CLR(hcp, H_ISDUP);
                                hcp->indx += 2;
                        }
                } else if (!F_ISSET(hcp, H_ISDUP) && F_ISSET(hcp, H_DUPONLY)) {
                        F_CLR(hcp, H_OK);
                        F_SET(hcp, H_NOMORE);
                        return (0);
                } else if (F_ISSET(hcp, H_ISDUP) &&
                    F_ISSET(hcp, H_NEXT_NODUP)) {
                        F_CLR(hcp, H_ISDUP);
                        hcp->indx += 2;
                }
                F_CLR(hcp, H_DELETED);
        } else if (hcp->indx == NDX_INVALID) {
                hcp->indx = 0;
                F_CLR(hcp, H_ISDUP);
        } else if (F_ISSET(hcp, H_NEXT_NODUP)) {
                hcp->indx += 2;
                F_CLR(hcp, H_ISDUP);
        } else if (F_ISSET(hcp, H_ISDUP) && hcp->dup_tlen != 0) {
                if (hcp->dup_off + DUP_SIZE(hcp->dup_len) >=
                    hcp->dup_tlen && F_ISSET(hcp, H_DUPONLY)) {
                        F_CLR(hcp, H_OK);
                        F_SET(hcp, H_NOMORE);
                        return (0);
                }
                hcp->dup_off += DUP_SIZE(hcp->dup_len);
                if (hcp->dup_off >= hcp->dup_tlen) {
                        F_CLR(hcp, H_ISDUP);
                        hcp->indx += 2;
                }
        } else if (F_ISSET(hcp, H_DUPONLY)) {
                F_CLR(hcp, H_OK);
                F_SET(hcp, H_NOMORE);
                return (0);
        } else {
                hcp->indx += 2;
                F_CLR(hcp, H_ISDUP);
        }

        return (CDB___ham_item(dbc, mode, pgnop));
}

/*
 * PUBLIC: void CDB___ham_putitem __P((PAGE *p, const DBT *, int));
 *
 * This is a little bit sleazy in that we're overloading the meaning
 * of the H_OFFPAGE type here.  When we recover deletes, we have the
 * entire entry instead of having only the DBT, so we'll pass type
 * H_OFFPAGE to mean, "copy the whole entry" as opposed to constructing
 * an H_KEYDATA around it.
 */
void
CDB___ham_putitem(p, dbt, type)
        PAGE *p;
        const DBT *dbt;
        int type;
{
        u_int16_t n, off;

        n = NUM_ENT(p);

        /* Put the item element on the page. */
        if (type == H_OFFPAGE) {
                off = HOFFSET(p) - dbt->size;
                HOFFSET(p) = p->inp[n] = off;
                memcpy(P_ENTRY(p, n), dbt->data, dbt->size);
        } else {
                off = HOFFSET(p) - HKEYDATA_SIZE(dbt->size);
                HOFFSET(p) = p->inp[n] = off;
                PUT_HKEYDATA(P_ENTRY(p, n), dbt->data, dbt->size, type);
        }

        /* Adjust page info. */
        NUM_ENT(p) += 1;
}

/*
 * PUBLIC: void CDB___ham_reputpair
 * PUBLIC:    __P((PAGE *p, u_int32_t, u_int32_t, const DBT *, const DBT *));
 *
 * This is a special case to restore a key/data pair to its original
 * location during recovery.  We are guaranteed that the pair fits
 * on the page and is not the last pair on the page (because if it's
 * the last pair, the normal insert works).
 */
void
CDB___ham_reputpair(p, psize, ndx, key, data)
        PAGE *p;
        u_int32_t psize, ndx;
        const DBT *key, *data;
{
        db_indx_t i, movebytes, newbytes;
        u_int8_t *from;

        /* First shuffle the existing items up on the page.  */
        movebytes =
            (ndx == 0 ? psize : p->inp[H_DATAINDEX(ndx - 2)]) - HOFFSET(p);
        newbytes = key->size + data->size;
        from = (u_int8_t *)p + HOFFSET(p);
        memmove(from - newbytes, from, movebytes);

        /*
         * Adjust the indices and move them up 2 spaces. Note that we
         * have to check the exit condition inside the loop just in case
         * we are dealing with index 0 (db_indx_t's are unsigned).
         */
        for (i = NUM_ENT(p) - 1; ; i-- ) {
                p->inp[i + 2] = p->inp[i] - newbytes;
                if (i == H_KEYINDEX(ndx))
                        break;
        }

        /* Put the key and data on the page. */
        p->inp[H_KEYINDEX(ndx)] =
            (ndx == 0 ? psize : p->inp[H_DATAINDEX(ndx - 2)]) - key->size;
        p->inp[H_DATAINDEX(ndx)] = p->inp[H_KEYINDEX(ndx)] - data->size;
        memcpy(P_ENTRY(p, H_KEYINDEX(ndx)), key->data, key->size);
        memcpy(P_ENTRY(p, H_DATAINDEX(ndx)), data->data, data->size);

        /* Adjust page info. */
        HOFFSET(p) -= newbytes;
        NUM_ENT(p) += 2;
}

/*
 * PUBLIC: int CDB___ham_del_pair __P((DBC *, int));
 */
int
CDB___ham_del_pair(dbc, reclaim_page)
        DBC *dbc;
        int reclaim_page;
{
        DB *dbp;
        HASH_CURSOR *hcp;
        DBT data_dbt, key_dbt;
        DB_ENV *dbenv;
        DB_LSN new_lsn, *n_lsn, tmp_lsn;
        PAGE *p;
        db_indx_t ndx;
        db_pgno_t chg_pgno, pgno;
        int ret, t_ret;

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

        dbenv = dbp->dbenv;
        ndx = hcp->indx;

        if (hcp->page == NULL &&
            (ret = CDB___ham_get_page(dbp, hcp->pgno, (PAGE **)&hcp->page)) != 0)
                return (ret);
        p = hcp->page;

        /*
         * We optimize for the normal case which is when neither the key nor
         * the data are large.  In this case, we write a single log record
         * and do the delete.  If either is large, we'll call __big_delete
         * to remove the big item and then update the page to remove the
         * entry referring to the big item.
         */
        ret = 0;
        if (HPAGE_PTYPE(H_PAIRKEY(p, ndx)) == H_OFFPAGE) {
                memcpy(&pgno, HOFFPAGE_PGNO(P_ENTRY(p, H_KEYINDEX(ndx))),
                    sizeof(db_pgno_t));
                ret = CDB___db_doff(dbc, pgno);
        }

        if (ret == 0)
                switch (HPAGE_PTYPE(H_PAIRDATA(p, ndx))) {
                case H_OFFPAGE:
                        memcpy(&pgno,
                            HOFFPAGE_PGNO(P_ENTRY(p, H_DATAINDEX(ndx))),
                            sizeof(db_pgno_t));
                        ret = CDB___db_doff(dbc, pgno);
                        break;
                case H_OFFDUP:
                case H_DUPLICATE:
                        /*
                         * If we delete a pair that is/was a duplicate, then
                         * we had better clear the flag so that we update the
                         * cursor appropriately.
                         */
                        F_CLR(hcp, H_ISDUP);
                        break;
                }

        if (ret)
                return (ret);

        /* Now log the delete off this page. */
        if (DB_LOGGING(dbc)) {
                key_dbt.data = P_ENTRY(p, H_KEYINDEX(ndx));
                key_dbt.size = LEN_HITEM(p, dbp->pgsize, H_KEYINDEX(ndx));
                data_dbt.data = P_ENTRY(p, H_DATAINDEX(ndx));
                data_dbt.size = LEN_HITEM(p, dbp->pgsize, H_DATAINDEX(ndx));

                if ((ret = CDB___ham_insdel_log(dbenv,
                    dbc->txn, &new_lsn, 0, DELPAIR,
                    dbp->log_fileid, PGNO(p), (u_int32_t)ndx,
                    &LSN(p), &key_dbt, &data_dbt)) != 0)
                        return (ret);

                /* Move lsn onto page. */
                LSN(p) = new_lsn;
        }

        CDB___ham_dpair(dbp, p, ndx);

        /*
         * If we are locking, we will not maintain this, because it is
         * a hot spot.
         *
         * XXX
         * Perhaps we can retain incremental numbers and apply them later.
         */
        if (!STD_LOCKING(dbc))
                --hcp->hdr->nelem;

        /*
         * If we need to reclaim the page, then check if the page is empty.
         * There are two cases.  If it's empty and it's not the first page
         * in the bucket (i.e., the bucket page) then we can simply remove
         * it. If it is the first chain in the bucket, then we need to copy
         * the second page into it and remove the second page.
         */
        if (reclaim_page && NUM_ENT(p) == 0 && PREV_PGNO(p) == PGNO_INVALID &&
            NEXT_PGNO(p) != PGNO_INVALID) {
                PAGE *n_pagep, *nn_pagep;
                db_pgno_t tmp_pgno;

                /*
                 * First page in chain is empty and we know that there
                 * are more pages in the chain.
                 */
                if ((ret =
                    CDB___ham_get_page(dbp, NEXT_PGNO(p), &n_pagep)) != 0)
                        return (ret);

                if (NEXT_PGNO(n_pagep) != PGNO_INVALID) {
                        if ((ret =
                            CDB___ham_get_page(dbp, NEXT_PGNO(n_pagep),
                            &nn_pagep)) != 0) {
                                (void) CDB___ham_put_page(dbp, n_pagep, 0);
                                return (ret);
                        }
                }

                if (DB_LOGGING(dbc)) {
                        key_dbt.data = n_pagep;
                        key_dbt.size = dbp->pgsize;
                        if ((ret = CDB___ham_copypage_log(dbenv,
                            dbc->txn, &new_lsn, 0, dbp->log_fileid, PGNO(p),
                            &LSN(p), PGNO(n_pagep), &LSN(n_pagep),
                            NEXT_PGNO(n_pagep),
                            NEXT_PGNO(n_pagep) == PGNO_INVALID ? NULL :
                            &LSN(nn_pagep), &key_dbt)) != 0)
                                return (ret);

                        /* Move lsn onto page. */
                        LSN(p) = new_lsn;       /* Structure assignment. */
                        LSN(n_pagep) = new_lsn;
                        if (NEXT_PGNO(n_pagep) != PGNO_INVALID)
                                LSN(nn_pagep) = new_lsn;
                }
                if (NEXT_PGNO(n_pagep) != PGNO_INVALID) {
                        PREV_PGNO(nn_pagep) = PGNO(p);
                        (void)CDB___ham_put_page(dbp, nn_pagep, 1);
                }

                tmp_pgno = PGNO(p);
                tmp_lsn = LSN(p);
                memcpy(p, n_pagep, dbp->pgsize);
                PGNO(p) = tmp_pgno;
                LSN(p) = tmp_lsn;
                PREV_PGNO(p) = PGNO_INVALID;

                /*
                 * We need to update this cursor and possibly all others.
                 * The ordering of this is critical to avoid marking valid
                 * entries as deleted.
                 * First, we update all the relevant cursors to reflect
                 * this deletion.
                 * Second, we update all the cursors to reflect the fact
                 * that some other entries changed pages.
                 * Finally, we advance this cursor to the next page.
                 */
                CDB___ham_c_update(dbc, PGNO(p), 0, 0, 0);
                CDB___ham_c_chgpg(dbc,
                    PGNO(n_pagep), NDX_INVALID, PGNO(p), NDX_INVALID);
                hcp->indx = 0;
                hcp->pgno = PGNO(p);
                F_SET(hcp, H_DELETED);
                if ((ret = CDB___ham_dirty_page(dbp, p)) != 0 ||
                    (ret = CDB___db_free(dbc, n_pagep)) != 0)
                        return (ret);
                F_CLR(hcp, H_OK);
                return (ret);
        } else if (reclaim_page &&
            NUM_ENT(p) == 0 && PREV_PGNO(p) != PGNO_INVALID) {
                PAGE *n_pagep, *p_pagep;

                if ((ret =
                    CDB___ham_get_page(dbp, PREV_PGNO(p), &p_pagep)) != 0)
                        return (ret);

                if (NEXT_PGNO(p) != PGNO_INVALID) {
                        if ((ret = CDB___ham_get_page(dbp,
                            NEXT_PGNO(p), &n_pagep)) != 0) {
                                (void)CDB___ham_put_page(dbp, p_pagep, 0);
                                return (ret);
                        }
                        n_lsn = &LSN(n_pagep);
                } else {
                        n_pagep = NULL;
                        n_lsn = NULL;
                }

                NEXT_PGNO(p_pagep) = NEXT_PGNO(p);
                if (n_pagep != NULL)
                        PREV_PGNO(n_pagep) = PGNO(p_pagep);

                if (DB_LOGGING(dbc)) {
                        if ((ret = CDB___ham_newpage_log(dbenv,
                            dbc->txn, &new_lsn, 0, DELOVFL,
                            dbp->log_fileid, PREV_PGNO(p), &LSN(p_pagep),
                            PGNO(p), &LSN(p), NEXT_PGNO(p), n_lsn)) != 0)
                                return (ret);

                        /* Move lsn onto page. */
                        LSN(p_pagep) = new_lsn; /* Structure assignment. */
                        if (n_pagep)
                                LSN(n_pagep) = new_lsn;
                        LSN(p) = new_lsn;
                }
                hcp->pgno = NEXT_PGNO(p);
                hcp->indx = 0;
                /*
                 * Since we are about to delete the cursor page and we have
                 * just moved the cursor, we need to make sure that the
                 * old page pointer isn't left hanging around in the cursor.
                 */
                hcp->page = NULL;
                chg_pgno = PGNO(p);
                ret = CDB___db_free(dbc, p);
                if ((t_ret = CDB___ham_put_page(dbp, p_pagep, 1)) != 0 && ret == 0)
                        ret = t_ret;
                if (n_pagep != NULL &&
                    (t_ret = CDB___ham_put_page(dbp, n_pagep, 1)) != 0 && ret == 0)
                        ret = t_ret;
                if (ret != 0)
                        return (ret);
        } else {
                /*
                 * Mark item deleted so that we don't try to return it, and
                 * so that we update the cursor correctly on the next call
                 * to next.
                 */
                F_SET(hcp, H_DELETED);
                chg_pgno = hcp->pgno;
                ret = CDB___ham_dirty_page(dbp, p);
        }
        CDB___ham_c_update(dbc, chg_pgno, 0, 0, 0);

        F_CLR(hcp, H_OK);
        return (ret);
}

/*
 * CDB___ham_replpair --
 *      Given the key data indicated by the cursor, replace part/all of it
 *      according to the fields in the dbt.
 *
 * PUBLIC: int CDB___ham_replpair __P((DBC *, DBT *, u_int32_t));
 */
int
CDB___ham_replpair(dbc, dbt, make_dup)
        DBC *dbc;
        DBT *dbt;
        u_int32_t make_dup;
{
        DB *dbp;
        HASH_CURSOR *hcp;
        DBT old_dbt, tdata, tmp;
        DB_LSN  new_lsn;
        int32_t change;                 /* XXX: Possible overflow. */
        u_int32_t dup, len, memsize;
        int is_big, ret, type;
        u_int8_t *beg, *dest, *end, *hk, *src;
        void *memp;

        /*
         * Big item replacements are handled in generic code.
         * Items that fit on the current page fall into 4 classes.
         * 1. On-page element, same size
         * 2. On-page element, new is bigger (fits)
         * 3. On-page element, new is bigger (does not fit)
         * 4. On-page element, old is bigger
         * Numbers 1, 2, and 4 are essentially the same (and should
         * be the common case).  We handle case 3 as a delete and
         * add.
         */
        dbp = dbc->dbp;
        hcp = (HASH_CURSOR *)dbc->internal;

        /*
         * We need to compute the number of bytes that we are adding or
         * removing from the entry.  Normally, we can simply substract
         * the number of bytes we are replacing (dbt->dlen) from the
         * number of bytes we are inserting (dbt->size).  However, if
         * we are doing a partial put off the end of a record, then this
         * formula doesn't work, because we are essentially adding
         * new bytes.
         */
        change = dbt->size - dbt->dlen;

        hk = H_PAIRDATA(hcp->page, hcp->indx);
        is_big = HPAGE_PTYPE(hk) == H_OFFPAGE;

        if (is_big)
                memcpy(&len, HOFFPAGE_TLEN(hk), sizeof(u_int32_t));
        else
                len = LEN_HKEYDATA(hcp->page,
                    dbp->pgsize, H_DATAINDEX(hcp->indx));

        if (dbt->doff + dbt->dlen > len)
                change += dbt->doff + dbt->dlen - len;

        if (change > (int32_t)P_FREESPACE(hcp->page) || is_big) {
                /*
                 * Case 3 -- two subcases.
                 * A. This is not really a partial operation, but an overwrite.
                 *    Simple del and add works.
                 * B. This is a partial and we need to construct the data that
                 *    we are really inserting (yuck).
                 * In both cases, we need to grab the key off the page (in
                 * some cases we could do this outside of this routine; for
                 * cleanliness we do it here.  If you happen to be on a big
                 * key, this could be a performance hit).
                 */
                memset(&tmp, 0, sizeof(tmp));
                if ((ret =
                    CDB___db_ret(dbp, hcp->page, H_KEYINDEX(hcp->indx),
                    &tmp, &dbc->rkey.data, &dbc->rkey.ulen)) != 0)
                        return (ret);

                /* Preserve duplicate info. */
                dup = F_ISSET(hcp, H_ISDUP);
                if (dbt->doff == 0 && dbt->dlen == len) {
                        ret = CDB___ham_del_pair(dbc, 0);
                        if (ret == 0)
                            ret = CDB___ham_add_el(dbc,
                                &tmp, dbt, dup ? H_DUPLICATE : H_KEYDATA);
                } else {                                        /* Case B */
                        type = HPAGE_PTYPE(hk) != H_OFFPAGE ?
                            HPAGE_PTYPE(hk) : H_KEYDATA;
                        memset(&tdata, 0, sizeof(tdata));
                        memp = NULL;
                        memsize = 0;
                        if ((ret = CDB___db_ret(dbp, hcp->page,
                            H_DATAINDEX(hcp->indx), &tdata, &memp, &memsize))
                            != 0)
                                goto err;

                        /* Now we can delete the item. */
                        if ((ret = CDB___ham_del_pair(dbc, 0)) != 0) {
                                CDB___os_free(memp, memsize);
                                goto err;
                        }

                        /* Now shift old data around to make room for new. */
                        if (change > 0) {
                                 if ((ret = CDB___os_realloc(dbp->dbenv,
                                     tdata.size + change,
                                     NULL, &tdata.data)) != 0)
                                        return (ret);
                                memp = tdata.data;
                                memsize = tdata.size + change;
                                memset((u_int8_t *)tdata.data + tdata.size,
                                    0, change);
                        }
                        end = (u_int8_t *)tdata.data + tdata.size;

                        src = (u_int8_t *)tdata.data + dbt->doff + dbt->dlen;
                        if (src < end && tdata.size > dbt->doff + dbt->dlen) {
                                len = tdata.size - dbt->doff - dbt->dlen;
                                dest = src + change;
                                memmove(dest, src, len);
                        }
                        memcpy((u_int8_t *)tdata.data + dbt->doff,
                            dbt->data, dbt->size);
                        tdata.size += change;

                        /* Now add the pair. */
                        ret = CDB___ham_add_el(dbc, &tmp, &tdata, type);
                        CDB___os_free(memp, memsize);
                }
                F_SET(hcp, dup);
err:            return (ret);
        }

        /*
         * Set up pointer into existing data. Do it before the log
         * message so we can use it inside of the log setup.
         */
        beg = HKEYDATA_DATA(H_PAIRDATA(hcp->page, hcp->indx));
        beg += dbt->doff;

        /*
         * If we are going to have to move bytes at all, figure out
         * all the parameters here.  Then log the call before moving
         * anything around.
         */
        if (DB_LOGGING(dbc)) {
                old_dbt.data = beg;
                old_dbt.size = dbt->dlen;
                if ((ret = CDB___ham_replace_log(dbp->dbenv,
                    dbc->txn, &new_lsn, 0, dbp->log_fileid, PGNO(hcp->page),
                    (u_int32_t)H_DATAINDEX(hcp->indx), &LSN(hcp->page),
                    (u_int32_t)dbt->doff, &old_dbt, dbt, make_dup)) != 0)
                        return (ret);

                LSN(hcp->page) = new_lsn;       /* Structure assignment. */
        }

        CDB___ham_onpage_replace(hcp->page, dbp->pgsize,
            (u_int32_t)H_DATAINDEX(hcp->indx), (int32_t)dbt->doff, change, dbt);

        return (0);
}

/*
 * Replace data on a page with new data, possibly growing or shrinking what's
 * there.  This is called on two different occasions. On one (from replpair)
 * we are interested in changing only the data.  On the other (from recovery)
 * we are replacing the entire data (header and all) with a new element.  In
 * the latter case, the off argument is negative.
 * pagep: the page that we're changing
 * ndx: page index of the element that is growing/shrinking.
 * off: Offset at which we are beginning the replacement.
 * change: the number of bytes (+ or -) that the element is growing/shrinking.
 * dbt: the new data that gets written at beg.
 * PUBLIC: void CDB___ham_onpage_replace __P((PAGE *, size_t, u_int32_t, int32_t,
 * PUBLIC:     int32_t,  DBT *));
 */
void
CDB___ham_onpage_replace(pagep, pgsize, ndx, off, change, dbt)
        PAGE *pagep;
        size_t pgsize;
        u_int32_t ndx;
        int32_t off;
        int32_t change;
        DBT *dbt;
{
        db_indx_t i;
        int32_t len;
        u_int8_t *src, *dest;
        int zero_me;

        if (change != 0) {
                zero_me = 0;
                src = (u_int8_t *)(pagep) + HOFFSET(pagep);
                if (off < 0)
                        len = pagep->inp[ndx] - HOFFSET(pagep);
                else if ((u_int32_t)off >= LEN_HKEYDATA(pagep, pgsize, ndx)) {
                        len = HKEYDATA_DATA(P_ENTRY(pagep, ndx)) +
                            LEN_HKEYDATA(pagep, pgsize, ndx) - src;
                        zero_me = 1;
                } else
                        len = (HKEYDATA_DATA(P_ENTRY(pagep, ndx)) + off) - src;
                dest = src - change;
                memmove(dest, src, len);
                if (zero_me)
                        memset(dest + len, 0, change);

                /* Now update the indices. */
                for (i = ndx; i < NUM_ENT(pagep); i++)
                        pagep->inp[i] -= change;
                HOFFSET(pagep) -= change;
        }
        if (off >= 0)
                memcpy(HKEYDATA_DATA(P_ENTRY(pagep, ndx)) + off,
                    dbt->data, dbt->size);
        else
                memcpy(P_ENTRY(pagep, ndx), dbt->data, dbt->size);
}

/*
 * PUBLIC: int CDB___ham_split_page __P((DBC *, u_int32_t, u_int32_t));
 */
int
CDB___ham_split_page(dbc, obucket, nbucket)
        DBC *dbc;
        u_int32_t obucket, nbucket;
{
        DB *dbp;
        DBC **carray;
        HASH_CURSOR *hcp, *cp;
        DBT key, page_dbt;
        DB_ENV *dbenv;
        DB_LSN new_lsn;
        PAGE **pp, *old_pagep, *temp_pagep, *new_pagep;
        db_indx_t n;
        db_pgno_t bucket_pgno, npgno, next_pgno;
        u_int32_t big_len, len;
        int i, ret, t_ret;
        void *big_buf;

        dbp = dbc->dbp;
        hcp = (HASH_CURSOR *)dbc->internal;
        dbenv = dbp->dbenv;
        temp_pagep = old_pagep = new_pagep = NULL;

        if ((ret = CDB___ham_get_clist(dbp, obucket, NDX_INVALID, &carray)) != 0)
                return (ret);

        bucket_pgno = BUCKET_TO_PAGE(hcp, obucket);
        if ((ret = CDB___ham_get_page(dbp, bucket_pgno, &old_pagep)) != 0)
                goto err;

        /* Properly initialize the new bucket page. */
        npgno = BUCKET_TO_PAGE(hcp, nbucket);
        if ((ret = CDB___ham_get_page(dbp, npgno, &new_pagep)) != 0)
                goto err;
        P_INIT(new_pagep,
            dbp->pgsize, npgno, PGNO_INVALID, PGNO_INVALID, 0, P_HASH, dbp->tags);

        temp_pagep = hcp->split_buf;
        memcpy(temp_pagep, old_pagep, dbp->pgsize);

        if (DB_LOGGING(dbc)) {
                page_dbt.size = dbp->pgsize;
                page_dbt.data = old_pagep;
                if ((ret = CDB___ham_splitdata_log(dbenv,
                    dbc->txn, &new_lsn, 0, dbp->log_fileid, SPLITOLD,
                    PGNO(old_pagep), &page_dbt, &LSN(old_pagep))) != 0)
                        goto err;
        }

        P_INIT(old_pagep, dbp->pgsize, PGNO(old_pagep), PGNO_INVALID,
            PGNO_INVALID, 0, P_HASH, dbp->tags);

        if (DB_LOGGING(dbc))
                LSN(old_pagep) = new_lsn;       /* Structure assignment. */

        big_len = 0;
        big_buf = NULL;
        key.flags = 0;
        while (temp_pagep != NULL) {
                for (n = 0; n < (db_indx_t)NUM_ENT(temp_pagep); n += 2) {
                        if ((ret =
                            CDB___db_ret(dbp, temp_pagep, H_KEYINDEX(n),
                            &key, &big_buf, &big_len)) != 0)
                                goto err;

                        if (CDB___ham_call_hash(dbc, key.data, key.size)
                            == obucket)
                                pp = &old_pagep;
                        else
                                pp = &new_pagep;

                        /*
                         * Figure out how many bytes we need on the new
                         * page to store the key/data pair.
                         */

                        len = LEN_HITEM(temp_pagep, dbp->pgsize,
                            H_DATAINDEX(n)) +
                            LEN_HITEM(temp_pagep, dbp->pgsize,
                            H_KEYINDEX(n)) +
                            2 * sizeof(db_indx_t);

                        if (P_FREESPACE(*pp) < len) {
                                if (DB_LOGGING(dbc)) {
                                        page_dbt.size = dbp->pgsize;
                                        page_dbt.data = *pp;
                                        if ((ret = CDB___ham_splitdata_log(
                                            dbenv, dbc->txn,
                                            &new_lsn, 0, dbp->log_fileid,
                                            SPLITNEW, PGNO(*pp), &page_dbt,
                                            &LSN(*pp))) != 0)
                                                goto err;
                                        LSN(*pp) = new_lsn;
                                }
                                if ((ret =
                                    CDB___ham_add_ovflpage(dbc, *pp, 1, pp)) != 0)
                                        goto err;
                        }

                        /* Check if we need to update a cursor. */
                        if (carray != NULL) {
                                for (i = 0; carray[i] != NULL; i++) {
                                        cp =
                                            (HASH_CURSOR *)carray[i]->internal;
                                        if (cp->pgno == PGNO(temp_pagep)
                                            && cp->indx == n) {
                                                cp->pgno = PGNO(*pp);
                                                cp->indx = NUM_ENT(*pp);
                                        }
                                }
                        }
                        CDB___ham_copy_item(dbp->pgsize,
                            temp_pagep, H_KEYINDEX(n), *pp);
                        CDB___ham_copy_item(dbp->pgsize,
                            temp_pagep, H_DATAINDEX(n), *pp);
                }
                next_pgno = NEXT_PGNO(temp_pagep);

                /* Clear temp_page; if it's a link overflow page, free it. */
                if (PGNO(temp_pagep) != bucket_pgno && (ret =
                    CDB___db_free(dbc, temp_pagep)) != 0)
                        goto err;

                if (next_pgno == PGNO_INVALID)
                        temp_pagep = NULL;
                else if ((ret =
                    CDB___ham_get_page(dbp, next_pgno, &temp_pagep)) != 0)
                        goto err;

                if (temp_pagep != NULL && DB_LOGGING(dbc)) {
                        page_dbt.size = dbp->pgsize;
                        page_dbt.data = temp_pagep;
                        if ((ret = CDB___ham_splitdata_log(dbenv,
                            dbc->txn, &new_lsn, 0, dbp->log_fileid,
                            SPLITOLD, PGNO(temp_pagep),
                            &page_dbt, &LSN(temp_pagep))) != 0)
                                goto err;
                        LSN(temp_pagep) = new_lsn;
                }
        }
        if (big_buf != NULL)
                CDB___os_free(big_buf, big_len);

        /*
         * If the original bucket spanned multiple pages, then we've got
         * a pointer to a page that used to be on the bucket chain.  It
         * should be deleted.
         */
        if (temp_pagep != NULL && PGNO(temp_pagep) != bucket_pgno &&
            (ret = CDB___db_free(dbc, temp_pagep)) != 0)
                goto err;

        /*
         * Write new buckets out.
         */
        if (DB_LOGGING(dbc)) {
                page_dbt.size = dbp->pgsize;
                page_dbt.data = old_pagep;
                if ((ret = CDB___ham_splitdata_log(dbenv, dbc->txn, &new_lsn, 0,
                    dbp->log_fileid, SPLITNEW, PGNO(old_pagep), &page_dbt,
                    &LSN(old_pagep))) != 0)
                        goto err;
                LSN(old_pagep) = new_lsn;

                page_dbt.data = new_pagep;
                if ((ret = CDB___ham_splitdata_log(dbenv, dbc->txn, &new_lsn, 0,
                    dbp->log_fileid, SPLITNEW, PGNO(new_pagep), &page_dbt,
                    &LSN(new_pagep))) != 0)
                        goto err;
                LSN(new_pagep) = new_lsn;
        }
        ret = CDB___ham_put_page(dbp, old_pagep, 1);
        if ((t_ret = CDB___ham_put_page(dbp, new_pagep, 1)) != 0 && ret == 0)
                ret = t_ret;

        if (0) {
err:            if (old_pagep != NULL)
                        (void)CDB___ham_put_page(dbp, old_pagep, 1);
                if (new_pagep != NULL)
                        (void)CDB___ham_put_page(dbp, new_pagep, 1);
                if (temp_pagep != NULL && PGNO(temp_pagep) != bucket_pgno)
                        (void)CDB___ham_put_page(dbp, temp_pagep, 1);
        }
        if (carray != NULL)             /* We never knew its size. */
                CDB___os_free(carray, 0);
        return (ret);
}

/*
 * Add the given pair to the page.  The page in question may already be
 * held (i.e. it was already gotten).  If it is, then the page is passed
 * in via the pagep parameter.  On return, pagep will contain the page
 * to which we just added something.  This allows us to link overflow
 * pages and return the new page having correctly put the last page.
 *
 * PUBLIC: int CDB___ham_add_el __P((DBC *, const DBT *, const DBT *, int));
 */
int
CDB___ham_add_el(dbc, key, val, type)
        DBC *dbc;
        const DBT *key, *val;
        int type;
{
        DB *dbp;
        HASH_CURSOR *hcp;
        const DBT *pkey, *pdata;
        DBT key_dbt, data_dbt;
        DB_LSN new_lsn;
        HOFFPAGE doff, koff;
        db_pgno_t next_pgno;
        u_int32_t data_size, key_size, pairsize, rectype;
        int do_expand, is_keybig, is_databig, ret;
        int key_type, data_type;

        dbp = dbc->dbp;
        hcp = (HASH_CURSOR *)dbc->internal;
        do_expand = 0;

        if (hcp->page == NULL && (ret = CDB___ham_get_page(dbp,
            hcp->seek_found_page != PGNO_INVALID ?  hcp->seek_found_page :
            hcp->pgno, (PAGE **)&hcp->page)) != 0)
                return (ret);

        key_size = HKEYDATA_PSIZE(key->size);
        data_size = HKEYDATA_PSIZE(val->size);
        is_keybig = ISBIG(hcp, key->size);
        is_databig = ISBIG(hcp, val->size);
        if (is_keybig)
                key_size = HOFFPAGE_PSIZE;
        if (is_databig)
                data_size = HOFFPAGE_PSIZE;

        pairsize = key_size + data_size;

        /* Advance to first page in chain with room for item. */
        while (H_NUMPAIRS(hcp->page) && NEXT_PGNO(hcp->page) != PGNO_INVALID) {
                /*
                 * This may not be the end of the chain, but the pair may fit
                 * anyway.  Check if it's a bigpair that fits or a regular
                 * pair that fits.
                 */
                if (P_FREESPACE(hcp->page) >= pairsize)
                        break;
                next_pgno = NEXT_PGNO(hcp->page);
                if ((ret =
                    CDB___ham_next_cpage(dbc, next_pgno, 0)) != 0)
                        return (ret);
        }

        /*
         * Check if we need to allocate a new page.
         */
        if (P_FREESPACE(hcp->page) < pairsize) {
                do_expand = 1;
                if ((ret = CDB___ham_add_ovflpage(dbc,
                    (PAGE *)hcp->page, 1, (PAGE **)&hcp->page)) !=  0)
                        return (ret);
                hcp->pgno = PGNO(hcp->page);
        }

        /*
         * Update cursor.
         */
        hcp->indx = NUM_ENT(hcp->page);
        F_CLR(hcp, H_DELETED);
        if (is_keybig) {
                koff.type = H_OFFPAGE;
                UMRW(koff.unused[0]);
                UMRW(koff.unused[1]);
                UMRW(koff.unused[2]);
                if ((ret = CDB___db_poff(dbc, key, &koff.pgno)) != 0)
                        return (ret);
                koff.tlen = key->size;
                key_dbt.data = &koff;
                key_dbt.size = sizeof(koff);
                pkey = &key_dbt;
                key_type = H_OFFPAGE;
        } else {
                pkey = key;
                key_type = H_KEYDATA;
        }

        if (is_databig) {
                doff.type = H_OFFPAGE;
                UMRW(doff.unused[0]);
                UMRW(doff.unused[1]);
                UMRW(doff.unused[2]);
                if ((ret = CDB___db_poff(dbc, val, &doff.pgno)) != 0)
                        return (ret);
                doff.tlen = val->size;
                data_dbt.data = &doff;
                data_dbt.size = sizeof(doff);
                pdata = &data_dbt;
                data_type = H_OFFPAGE;
        } else {
                pdata = val;
                data_type = type;
        }

        if (DB_LOGGING(dbc)) {
                rectype = PUTPAIR;
                if (is_databig)
                        rectype |= PAIR_DATAMASK;
                if (is_keybig)
                        rectype |= PAIR_KEYMASK;
                if (type == H_DUPLICATE)
                        rectype |= PAIR_DUPMASK;

                if ((ret = CDB___ham_insdel_log(dbp->dbenv, dbc->txn, &new_lsn, 0,
                    rectype, dbp->log_fileid, PGNO(hcp->page),
                    (u_int32_t)NUM_ENT(hcp->page), &LSN(hcp->page), pkey,
                    pdata)) != 0)
                        return (ret);

                /* Move lsn onto page. */
                LSN(hcp->page) = new_lsn;       /* Structure assignment. */
        }

        CDB___ham_putitem(hcp->page, pkey, key_type);
        CDB___ham_putitem(hcp->page, pdata, data_type);

        /*
         * For splits, we are going to update item_info's page number
         * field, so that we can easily return to the same page the
         * next time we come in here.  For other operations, this shouldn't
         * matter, since odds are this is the last thing that happens before
         * we return to the user program.
         */
        hcp->pgno = PGNO(hcp->page);

        /*
         * XXX
         * Maybe keep incremental numbers here.
         */
        if (!STD_LOCKING(dbc))
                hcp->hdr->nelem++;

        if (do_expand || (hcp->hdr->ffactor != 0 &&
            (u_int32_t)H_NUMPAIRS(hcp->page) > hcp->hdr->ffactor))
                F_SET(hcp, H_EXPAND);
        return (0);
}

/*
 * Special __putitem call used in splitting -- copies one entry to
 * another.  Works for all types of hash entries (H_OFFPAGE, H_KEYDATA,
 * H_DUPLICATE, H_OFFDUP).  Since we log splits at a high level, we
 * do not need to do any logging here.
 *
 * PUBLIC: void CDB___ham_copy_item __P((size_t, PAGE *, u_int32_t, PAGE *));
 */
void
CDB___ham_copy_item(pgsize, src_page, src_ndx, dest_page)
        size_t pgsize;
        PAGE *src_page;
        u_int32_t src_ndx;
        PAGE *dest_page;
{
        u_int32_t len;
        void *src, *dest;

        /*
         * Copy the key and data entries onto this new page.
         */
        src = P_ENTRY(src_page, src_ndx);

        /* Set up space on dest. */
        len = LEN_HITEM(src_page, pgsize, src_ndx);
        HOFFSET(dest_page) -= len;
        dest_page->inp[NUM_ENT(dest_page)] = HOFFSET(dest_page);
        dest = P_ENTRY(dest_page, NUM_ENT(dest_page));
        NUM_ENT(dest_page)++;

        memcpy(dest, src, len);
}

/*
 *
 * Returns:
 *      pointer on success
 *      NULL on error
 *
 * PUBLIC: int CDB___ham_add_ovflpage __P((DBC *, PAGE *, int, PAGE **));
 */
int
CDB___ham_add_ovflpage(dbc, pagep, release, pp)
        DBC *dbc;
        PAGE *pagep;
        int release;
        PAGE **pp;
{
        DB *dbp;
        HASH_CURSOR *hcp;
        DB_LSN new_lsn;
        PAGE *new_pagep;
        int ret;

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

        if ((ret = CDB___db_new(dbc, (P_HASH | dbp->tags), &new_pagep)) != 0)
                return (ret);

        if (DB_LOGGING(dbc)) {
                if ((ret = CDB___ham_newpage_log(dbp->dbenv, dbc->txn, &new_lsn, 0,
                    PUTOVFL, dbp->log_fileid, PGNO(pagep), &LSN(pagep),
                    PGNO(new_pagep), &LSN(new_pagep), PGNO_INVALID, NULL)) != 0)
                        return (ret);

                /* Move lsn onto page. */
                LSN(pagep) = LSN(new_pagep) = new_lsn;
        }
        NEXT_PGNO(pagep) = PGNO(new_pagep);
        PREV_PGNO(new_pagep) = PGNO(pagep);

        if (release)
                ret = CDB___ham_put_page(dbp, pagep, 1);

        *pp = new_pagep;
        return (ret);
}

/*
 * PUBLIC: int CDB___ham_put_page __P((DB *, PAGE *, int32_t));
 */
int
CDB___ham_put_page(dbp, pagep, is_dirty)
        DB *dbp;
        PAGE *pagep;
        int32_t is_dirty;
{
        return (CDB_memp_fput(dbp->mpf, pagep, (is_dirty ? DB_MPOOL_DIRTY : 0)));
}

/*
 * CDB___ham_dirty_page --
 *      Mark a page dirty.
 *
 * PUBLIC: int CDB___ham_dirty_page __P((DB *, PAGE *));
 */
int
CDB___ham_dirty_page(dbp, pagep)
        DB *dbp;
        PAGE *pagep;
{
        return (CDB_memp_fset(dbp->mpf, pagep, DB_MPOOL_DIRTY));
}

/*
 * PUBLIC: int CDB___ham_get_page __P((DB *, db_pgno_t, PAGE **));
 */
int
CDB___ham_get_page(dbp, addr, pagep)
        DB *dbp;
        db_pgno_t addr;
        PAGE **pagep;
{
        return (CDB_memp_fget(dbp->mpf, &addr, DB_MPOOL_CREATE, pagep));
}

/*
 * PUBLIC: db_pgno_t CDB___bucket_to_page __P((HASH_CURSOR *, db_pgno_t));
 */
db_pgno_t
CDB___bucket_to_page(hcp, n)
        HASH_CURSOR *hcp;
        db_pgno_t n;
{
        int ret_val;

        ret_val = n + 1;
        if (n != 0)
                ret_val += hcp->hdr->spares[CDB___db_log2(n + 1) - 1];
        return (ret_val);
}

/*
 * PUBLIC: int CDB___ham_get_cpage __P((DBC *, db_lockmode_t));
 */
int
CDB___ham_get_cpage(dbc, mode)
        DBC *dbc;
        db_lockmode_t mode;
{
        DB *dbp;
        DB_LOCK tmp_lock;
        HASH_CURSOR *hcp;
        int ret;

        dbp = dbc->dbp;
        hcp = (HASH_CURSOR *)dbc->internal;
        ret = 0;

        /*
         * There are four cases with respect to buckets and locks.
         * 1. If there is no lock held, then if we are locking, we should
         *    get the lock.
         * 2. If there is a lock held, it's for the current bucket, and it's
         *    for the right mode, we don't need to do anything.
         * 3. If there is a lock held for the current bucket but it's not
         *    strong enough, we need to upgrade.
         * 4. If there is a lock, but it's for a different bucket, then we need
         *    to release the existing lock and get a new lock.
         */
        tmp_lock.off = LOCK_INVALID;
        if (STD_LOCKING(dbc)) {
                if (hcp->lock.off != LOCK_INVALID &&
                    hcp->lbucket != hcp->bucket) {              /* Case 4 */
                        if (dbc->txn == NULL &&
                            (ret = CDB_lock_put(dbp->dbenv, &hcp->lock)) != 0)
                                return (ret);
                        hcp->lock.off = LOCK_INVALID;
                }
                if ((hcp->lock.off != LOCK_INVALID &&
                    (hcp->lock_mode == DB_LOCK_READ &&
                    mode == DB_LOCK_WRITE))) {
                        /* Case 3. */
                        tmp_lock = hcp->lock;
                        hcp->lock.off = LOCK_INVALID;
                }

                /* Acquire the lock. */
                if (hcp->lock.off == LOCK_INVALID)
                        /* Cases 1, 3, and 4. */
                        if ((ret = CDB___ham_lock_bucket(dbc, mode)) != 0)
                                return (ret);

                if (ret == 0) {
                        hcp->lock_mode = mode;
                        hcp->lbucket = hcp->bucket;
                        if (tmp_lock.off != LOCK_INVALID)
                                /* Case 3: release the original lock. */
                                ret = CDB_lock_put(dbp->dbenv, &tmp_lock);
                } else if (tmp_lock.off != LOCK_INVALID)
                        hcp->lock = tmp_lock;
        }

        if (ret == 0 && hcp->page == NULL) {
                if (hcp->pgno == PGNO_INVALID)
                        hcp->pgno = BUCKET_TO_PAGE(hcp, hcp->bucket);
                if ((ret =
                    CDB___ham_get_page(dbp, hcp->pgno, (PAGE **)&hcp->page)) != 0)
                        return (ret);
        }

        return (0);
}

/*
 * Get a new page at the cursor, putting the last page if necessary.
 * If the flag is set to H_ISDUP, then we are talking about the
 * duplicate page, not the CDB_main page.
 *
 * PUBLIC: int CDB___ham_next_cpage __P((DBC *, db_pgno_t, int));
 */
int
CDB___ham_next_cpage(dbc, pgno, dirty)
        DBC *dbc;
        db_pgno_t pgno;
        int dirty;
{
        DB *dbp;
        HASH_CURSOR *hcp;
        PAGE *p;
        int ret;

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

        if (hcp->page != NULL &&
            (ret = CDB___ham_put_page(dbp, hcp->page, dirty)) != 0)
                return (ret);

        if ((ret = CDB___ham_get_page(dbp, pgno, &p)) != 0)
                return (ret);

        hcp->page = p;
        hcp->pgno = pgno;
        hcp->indx = 0;

        return (0);
}

/*
 * CDB___ham_lock_bucket --
 *      Get the lock on a particular bucket.
 *
 * PUBLIC: int CDB___ham_lock_bucket __P((DBC *, db_lockmode_t));
 */
int
CDB___ham_lock_bucket(dbc, mode)
        DBC *dbc;
        db_lockmode_t mode;
{
        HASH_CURSOR *hcp;
        u_int32_t flags;
        int gotmeta, ret;

        hcp = (HASH_CURSOR *)dbc->internal;
        gotmeta = hcp->hdr == NULL ? 1 : 0;
        if (gotmeta)
                if ((ret = CDB___ham_get_meta(dbc)) != 0)
                        return (ret);
        dbc->lock.pgno = BUCKET_TO_PAGE(hcp, hcp->bucket);
        if (gotmeta)
                if ((ret = CDB___ham_release_meta(dbc)) != 0)
                        return (ret);

        flags = 0;
        if (DB_NONBLOCK(dbc))
                LF_SET(DB_LOCK_NOWAIT);

        ret = CDB_lock_get(dbc->dbp->dbenv,
                    dbc->locker, flags, &dbc->lock_dbt, mode, &hcp->lock);

        hcp->lock_mode = mode;
        return (ret);
}

/*
 * CDB___ham_dpair --
 *      Delete a pair on a page, paying no attention to what the pair
 *      represents.  The caller is responsible for freeing up duplicates
 *      or offpage entries that might be referenced by this pair.
 *
 * PUBLIC: void CDB___ham_dpair __P((DB *, PAGE *, u_int32_t));
 */
void
CDB___ham_dpair(dbp, p, indx)
        DB *dbp;
        PAGE *p;
        u_int32_t indx;
{
        db_indx_t delta, n;
        u_int8_t *dest, *src;

        /*
         * Compute "delta", the amount we have to shift all of the
         * offsets.  To find the delta, we just need to calculate
         * the size of the pair of elements we are removing.
         */
        delta = H_PAIRSIZE(p, dbp->pgsize, indx);

        /*
         * The hard case: we want to remove something other than
         * the last item on the page.  We need to shift data and
         * offsets down.
         */
        if ((db_indx_t)indx != NUM_ENT(p) - 2) {
                /*
                 * Move the data: src is the first occupied byte on
                 * the page. (Length is delta.)
                 */
                src = (u_int8_t *)p + HOFFSET(p);

                /*
                 * Destination is delta bytes beyond src.  This might
                 * be an overlapping copy, so we have to use memmove.
                 */
                dest = src + delta;
                memmove(dest, src, p->inp[H_DATAINDEX(indx)] - HOFFSET(p));
        }

        /* Adjust page metadata. */
        HOFFSET(p) = HOFFSET(p) + delta;
        NUM_ENT(p) = NUM_ENT(p) - 2;

        /* Adjust the offsets. */
        for (n = (db_indx_t)indx; n < (db_indx_t)(NUM_ENT(p)); n++)
                p->inp[n] = p->inp[n + 2] + delta;

}

---