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hash_page.c

/*-
 * 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 "db_config.h"

#ifndef lint
static const char revid[] = "$Id: hash_page.c,v 11.46 2001/01/11 18:19:51 bostic 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 <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 __ham_item __P((DBC *, db_lockmode_t, db_pgno_t *));
 */
int
__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)) {
            __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 = __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 = __ham_next_cpage(dbc, next_pgno, 0)) != 0)
                  return (ret);
            goto recheck;
      }

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

/*
 * PUBLIC: int __ham_item_reset __P((DBC *));
 */
int
__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 = memp_fput(dbp->mpf, hcp->page, 0);

      __ham_item_init(dbc);
      return (ret);
}

/*
 * PUBLIC: void __ham_item_init __P((DBC *));
 */
void
__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)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 __ham_item_last __P((DBC *, db_lockmode_t, db_pgno_t *));
 */
int
__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 = __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 (__ham_item_prev(dbc, mode, pgnop));
}

/*
 * PUBLIC: int __ham_item_first __P((DBC *, db_lockmode_t, db_pgno_t *));
 */
int
__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 = __ham_item_reset(dbc)) != 0)
            return (ret);
      F_SET(hcp, H_OK);
      hcp->bucket = 0;
      hcp->pgno = BUCKET_TO_PAGE(hcp, hcp->bucket);
      return (__ham_item_next(dbc, mode, pgnop));
}

/*
 * __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 __ham_item_prev __P((DBC *, db_lockmode_t, db_pgno_t *));
 */
int
__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 = __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 (__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 =
                __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 = __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 (__ham_item(dbc, mode, pgnop));
}

/*
 * Sets the cursor to the next key/data pair on a page.
 *
 * PUBLIC: int __ham_item_next __P((DBC *, db_lockmode_t, db_pgno_t *));
 */
int
__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 = __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 (__ham_item(dbc, mode, pgnop));
}

/*
 * PUBLIC: void __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
__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 __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
__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 __ham_del_pair __P((DBC *, int));
 */
int
__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 *n_pagep, *nn_pagep, *p, *p_pagep;
      db_indx_t ndx;
      db_pgno_t chg_pgno, pgno, tmp_pgno;
      int ret, t_ret;

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

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

      n_pagep = p_pagep = nn_pagep = NULL;

      if (hcp->page == NULL && (ret = memp_fget(dbp->mpf,
          &hcp->pgno, DB_MPOOL_CREATE, &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 = __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 = __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 = __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;
      }

      /* Do the delete. */
      __ham_dpair(dbp, p, ndx);

      /*
       * 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);
      F_CLR(hcp, H_OK);

      /*
       * Update cursors that are on the page where the delete happend.
       */
      if ((ret = __ham_c_update(dbc, 0, 0, 0)) != 0)
            return (ret);

      /*
       * 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 its the only page in the bucket we leave it alone.
       */
      if (!reclaim_page ||
          NUM_ENT(p) != 0 ||
          (PREV_PGNO(p) == PGNO_INVALID && NEXT_PGNO(p) == PGNO_INVALID))
            return (memp_fset(dbp->mpf, p, DB_MPOOL_DIRTY));

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

            if (NEXT_PGNO(n_pagep) != PGNO_INVALID &&
                (ret = memp_fget(dbp->mpf, &NEXT_PGNO(n_pagep), 0,
                &nn_pagep)) != 0)
                  goto err;

            if (DB_LOGGING(dbc)) {
                  key_dbt.data = n_pagep;
                  key_dbt.size = dbp->pgsize;
                  if ((ret = __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),
                      nn_pagep == NULL ? NULL : &LSN(nn_pagep),
                      &key_dbt)) != 0)
                        goto err;

                  /* 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 (nn_pagep != NULL) {
                  PREV_PGNO(nn_pagep) = PGNO(p);
                  if ((ret = memp_fput(dbp->mpf,
                      nn_pagep, DB_MPOOL_DIRTY)) != 0) {
                        nn_pagep = NULL;
                        goto err;
                  }
            }

            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;

            /*
             * Update cursors to reflect the fact that records
             * on the second page have moved to the first page.
             */
            if ((ret = __ham_c_chgpg(dbc,
                PGNO(n_pagep), NDX_INVALID, PGNO(p), NDX_INVALID)) != 0)
                  return (ret);

            /*
             * Update the cursor to reflect its new position.
             */
            hcp->indx = 0;
            hcp->pgno = PGNO(p);
            if ((ret = memp_fset(dbp->mpf, p, DB_MPOOL_DIRTY)) != 0 ||
                (ret = __db_free(dbc, n_pagep)) != 0)
                  return (ret);
      } else {
            if ((ret =
                memp_fget(dbp->mpf, &PREV_PGNO(p), 0, &p_pagep)) != 0)
                  goto err;

            if (NEXT_PGNO(p) != PGNO_INVALID) {
                  if ((ret = memp_fget(dbp->mpf,
                      &NEXT_PGNO(p), 0, &n_pagep)) != 0)
                        goto err;
                  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 = __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)
                        goto err;

                  /* Move lsn onto page. */
                  LSN(p_pagep) = new_lsn; /* Structure assignment. */
                  if (n_pagep)
                        LSN(n_pagep) = new_lsn;
                  LSN(p) = new_lsn;
            }
            if (NEXT_PGNO(p) == PGNO_INVALID) {
                  /*
                   * There is no next page; put the cursor on the
                   * previous page as if we'd deleted the last item
                   * on that page; index greater than number of
                   * valid entries and H_DELETED set.
                   */
                  hcp->pgno = PGNO(p_pagep);
                  hcp->indx = NUM_ENT(p_pagep);
                  F_SET(hcp, H_DELETED);
            } else {
                  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 = __db_free(dbc, p);
            if ((t_ret = memp_fput(dbp->mpf, p_pagep, DB_MPOOL_DIRTY)) != 0
                && ret == 0)
                  ret = t_ret;
            if (n_pagep != NULL && (t_ret = memp_fput(dbp->mpf,
                n_pagep, DB_MPOOL_DIRTY)) != 0 && ret == 0)
                  ret = t_ret;
            if (ret != 0)
                  return (ret);
            ret = __ham_c_chgpg(dbc,
                chg_pgno, 0, hcp->pgno, hcp->indx);
      }
      return (ret);

err:  /* Clean up any pages. */
      if (n_pagep != NULL)
            (void)memp_fput(dbp->mpf, n_pagep, 0);
      if (nn_pagep != NULL)
            (void)memp_fput(dbp->mpf, nn_pagep, 0);
      if (p_pagep != NULL)
            (void)memp_fput(dbp->mpf, p_pagep, 0);
      return (ret);
}

/*
 * __ham_replpair --
 *    Given the key data indicated by the cursor, replace part/all of it
 *    according to the fields in the dbt.
 *
 * PUBLIC: int __ham_replpair __P((DBC *, DBT *, u_int32_t));
 */
int
__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 =
                __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 = __ham_del_pair(dbc, 0);
                  if (ret == 0)
                      ret = __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 = __db_ret(dbp, hcp->page,
                      H_DATAINDEX(hcp->indx), &tdata, &memp, &memsize))
                      != 0)
                        goto err;

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

                  /* Now shift old data around to make room for new. */
                  if (change > 0) {
                         if ((ret = __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 = __ham_add_el(dbc, &tmp, &tdata, type);
                  __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 = __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. */
      }

      __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 __ham_onpage_replace __P((PAGE *, size_t, u_int32_t, int32_t,
 * PUBLIC:     int32_t,  DBT *));
 */
void
__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 __ham_split_page __P((DBC *, u_int32_t, u_int32_t));
 */
int
__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 found, 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 = __ham_get_clist(dbp, obucket, NDX_INVALID, &carray)) != 0)
            return (ret);

      bucket_pgno = BUCKET_TO_PAGE(hcp, obucket);
      if ((ret = memp_fget(dbp->mpf,
          &bucket_pgno, DB_MPOOL_CREATE, &old_pagep)) != 0)
            goto err;

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

      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 = __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);

      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 =
                      __db_ret(dbp, temp_pagep, H_KEYINDEX(n),
                      &key, &big_buf, &big_len)) != 0)
                        goto err;

                  if (__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 = __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 =
                            __ham_add_ovflpage(dbc, *pp, 1, pp)) != 0)
                              goto err;
                  }

                  /* Check if we need to update a cursor. */
                  if (carray != NULL) {
                        found = 0;
                        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);
                                    found = 1;
                              }
                        }
                        if (found && DB_LOGGING(dbc)
                            && IS_SUBTRANSACTION(dbc->txn)) {
                              if ((ret =
                                  __ham_chgpg_log(dbp->dbenv,
                                  dbc->txn, &new_lsn, 0,
                                  dbp->log_fileid,
                                  DB_HAM_SPLIT, PGNO(temp_pagep),
                                  PGNO(*pp), n, NUM_ENT(*pp))) != 0)
                                    goto err;
                        }
                  }
                  __ham_copy_item(dbp->pgsize,
                      temp_pagep, H_KEYINDEX(n), *pp);
                  __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 =
                __db_free(dbc, temp_pagep)) != 0) {
                  temp_pagep = NULL;
                  goto err;
            }

            if (next_pgno == PGNO_INVALID)
                  temp_pagep = NULL;
            else if ((ret = memp_fget(dbp->mpf,
                &next_pgno, DB_MPOOL_CREATE, &temp_pagep)) != 0)
                  goto err;

            if (temp_pagep != NULL && DB_LOGGING(dbc)) {
                  page_dbt.size = dbp->pgsize;
                  page_dbt.data = temp_pagep;
                  if ((ret = __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)
            __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 = __db_free(dbc, temp_pagep)) != 0) {
            temp_pagep = NULL;
            goto err;
      }

      /*
       * Write new buckets out.
       */
      if (DB_LOGGING(dbc)) {
            page_dbt.size = dbp->pgsize;
            page_dbt.data = old_pagep;
            if ((ret = __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 = __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 = memp_fput(dbp->mpf, old_pagep, DB_MPOOL_DIRTY);
      if ((t_ret = memp_fput(dbp->mpf, new_pagep, DB_MPOOL_DIRTY)) != 0
          && ret == 0)
            ret = t_ret;

      if (0) {
err:        if (old_pagep != NULL)
                  (void)memp_fput(dbp->mpf, old_pagep, DB_MPOOL_DIRTY);
            if (new_pagep != NULL)
                  (void)memp_fput(dbp->mpf, new_pagep, DB_MPOOL_DIRTY);
            if (temp_pagep != NULL && PGNO(temp_pagep) != bucket_pgno)
                  (void)memp_fput(dbp->mpf, temp_pagep, DB_MPOOL_DIRTY);
      }
      if (carray != NULL)           /* We never knew its size. */
            __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 __ham_add_el __P((DBC *, const DBT *, const DBT *, int));
 */
int
__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, 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;

      pgno = hcp->seek_found_page != PGNO_INVALID ?  hcp->seek_found_page :
          hcp->pgno;
      if (hcp->page == NULL && (ret = memp_fget(dbp->mpf, &pgno,
          DB_MPOOL_CREATE, &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 =
                __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 = __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_SET(koff.unused[0]);
            UMRW_SET(koff.unused[1]);
            UMRW_SET(koff.unused[2]);
            if ((ret = __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_SET(doff.unused[0]);
            UMRW_SET(doff.unused[1]);
            UMRW_SET(doff.unused[2]);
            if ((ret = __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 = __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. */
      }

      __ham_putitem(hcp->page, pkey, key_type);
      __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 __ham_copy_item __P((size_t, PAGE *, u_int32_t, PAGE *));
 */
void
__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 __ham_add_ovflpage __P((DBC *, PAGE *, int, PAGE **));
 */
int
__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 = __db_new(dbc, P_HASH, &new_pagep)) != 0)
            return (ret);

      if (DB_LOGGING(dbc)) {
            if ((ret = __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 = memp_fput(dbp->mpf, pagep, DB_MPOOL_DIRTY);

      *pp = new_pagep;
      return (ret);
}

/*
 * PUBLIC: int __ham_get_cpage __P((DBC *, db_lockmode_t));
 */
int
__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 = 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 = __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 = 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 = memp_fget(dbp->mpf,
                &hcp->pgno, DB_MPOOL_CREATE, &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 main page.
 *
 * PUBLIC: int __ham_next_cpage __P((DBC *, db_pgno_t, int));
 */
int
__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 = memp_fput(dbp->mpf,
          hcp->page, dirty ? DB_MPOOL_DIRTY : 0)) != 0)
            return (ret);

      if ((ret = memp_fget(dbp->mpf, &pgno, DB_MPOOL_CREATE, &p)) != 0)
            return (ret);

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

      return (0);
}

/*
 * __ham_lock_bucket --
 *    Get the lock on a particular bucket.
 *
 * PUBLIC: int __ham_lock_bucket __P((DBC *, db_lockmode_t));
 */
int
__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 = __ham_get_meta(dbc)) != 0)
                  return (ret);
      dbc->lock.pgno = BUCKET_TO_PAGE(hcp, hcp->bucket);
      if (gotmeta)
            if ((ret = __ham_release_meta(dbc)) != 0)
                  return (ret);

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

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

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

/*
 * __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 __ham_dpair __P((DB *, PAGE *, u_int32_t));
 */
void
__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;

}

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