Logo Search packages:      
Sourcecode: db2 version File versions  Download package

bt_put.c

/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1996, 1997, 1998
 *    Sleepycat Software.  All rights reserved.
 */
/*
 * Copyright (c) 1990, 1993, 1994, 1995, 1996
 *    Keith Bostic.  All rights reserved.
 */
/*
 * Copyright (c) 1990, 1993, 1994, 1995
 *    The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Mike Olson.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    This product includes software developed by the University of
 *    California, Berkeley and its contributors.
 * 4. 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 sccsid[] = "@(#)bt_put.c      10.45 (Sleepycat) 5/25/98";
#endif /* not lint */

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

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

#include "db_int.h"
#include "db_page.h"
#include "btree.h"

static int __bam_fixed __P((BTREE *, DBT *));
static int __bam_isdeleted __P((DB *, PAGE *, u_int32_t, int *));
static int __bam_lookup __P((DB *, DBT *, int *));
static int __bam_ndup __P((DB *, PAGE *, u_int32_t));
static int __bam_ovput __P((DB *, PAGE *, u_int32_t, DBT *));
static int __bam_partial __P((DB *, DBT *, PAGE *, u_int32_t, u_int32_t));
static u_int32_t __bam_partsize __P((DBT *, PAGE *, u_int32_t));

/*
 * __bam_put --
 *    Add a new key/data pair or replace an existing pair (btree).
 *
 * PUBLIC: int __bam_put __P((DB *, DB_TXN *, DBT *, DBT *, u_int32_t));
 */
int
__bam_put(argdbp, txn, key, data, flags)
      DB *argdbp;
      DB_TXN *txn;
      DBT *key, *data;
      u_int32_t flags;
{
      BTREE *t;
      CURSOR c;
      DB *dbp;
      PAGE *h;
      db_indx_t indx;
      u_int32_t iitem_flags, insert_flags;
      int exact, isdeleted, newkey, ret, stack;

      DEBUG_LWRITE(argdbp, txn, "bam_put", key, data, flags);

      /* Check flags. */
      if ((ret = __db_putchk(argdbp, key, data, flags,
          F_ISSET(argdbp, DB_AM_RDONLY), F_ISSET(argdbp, DB_AM_DUP))) != 0)
            return (ret);

      GETHANDLE(argdbp, txn, &dbp, ret);
      t = dbp->internal;

retry:      /*
       * Find the location at which to insert.  The call to __bam_lookup
       * leaves the returned page pinned.
       */
      if ((ret = __bam_lookup(dbp, key, &exact)) != 0) {
            PUTHANDLE(dbp);
            return (ret);
      }
      h = t->bt_csp->page;
      indx = t->bt_csp->indx;
      stack = 1;

      /*
       * If DB_NOOVERWRITE is set and there's an identical key in the tree,
       * return an error unless the data item has already been marked for
       * deletion, or, all the remaining data items have already been marked
       * for deletion in the case of duplicates.  If all the data items have
       * been marked for deletion, we do a replace, otherwise, it has to be
       * a set of duplicates, and we simply append a new one to the set.
       */
      isdeleted = 0;
      if (exact) {
            if ((ret = __bam_isdeleted(dbp, h, indx, &isdeleted)) != 0)
                  goto err;
            if (isdeleted)
                  __bam_ca_replace(dbp, h->pgno, indx, REPLACE_SETUP);
            else
                  if (flags == DB_NOOVERWRITE) {
                        ret = DB_KEYEXIST;
                        goto err;
                  }
      }

      /*
       * If we're inserting into the first or last page of the tree,
       * remember where we did it so we can do fast lookup next time.
       *
       * XXX
       * Does reverse order still work (did it ever!?!?)
       */
      t->bt_lpgno =
          h->next_pgno == PGNO_INVALID || h->prev_pgno == PGNO_INVALID ?
          h->pgno : PGNO_INVALID;

      /*
       * Select the arguments for __bam_iitem() and do the insert.  If the
       * key is an exact match, we're either adding a new duplicate at the
       * end of the duplicate set, or we're replacing the data item with a
       * new data item.  If the key isn't an exact match, we're inserting
       * a new key/data pair, before the search location.
       */
      newkey = dbp->type == DB_BTREE && !exact;
      if (exact) {
            if (!isdeleted && F_ISSET(dbp, DB_AM_DUP)) {
                  /*
                   * Make sure that we're not looking at a page of
                   * duplicates -- if so, move to the last entry on
                   * that page.
                   */
                  c.page = h;
                  c.pgno = h->pgno;
                  c.indx = indx;
                  c.dpgno = PGNO_INVALID;
                  c.dindx = 0;
                  if ((ret =
                      __bam_ovfl_chk(dbp, &c, indx + O_INDX, 1)) != 0)
                        goto err;
                  if (c.dpgno != PGNO_INVALID) {
                        /*
                         * XXX
                         * The __bam_ovfl_chk() routine memp_fput() the
                         * current page and acquired a new one, but did
                         * not do anything about the lock we're holding.
                         */
                        t->bt_csp->page = h = c.page;
                        indx = c.dindx;
                  }
                  insert_flags = DB_AFTER;
            } else
                  insert_flags = DB_CURRENT;
      } else
            insert_flags = DB_BEFORE;

      /*
       * The pages we're using may be modified by __bam_iitem(), so make
       * sure we reset the stack.
       */
      iitem_flags = 0;
      if (newkey)
            iitem_flags |= BI_NEWKEY;
      if (isdeleted)
            iitem_flags |= BI_DOINCR;
      ret = __bam_iitem(dbp, &h, &indx, key, data, insert_flags, iitem_flags);
      t->bt_csp->page = h;
      t->bt_csp->indx = indx;

      switch (ret) {
      case 0:
            /* Done.  Clean up the cursor. */
            if (isdeleted)
                  __bam_ca_replace(dbp, h->pgno, indx, REPLACE_SUCCESS);
            break;
      case DB_NEEDSPLIT:
            /*
             * We have to split the page.  Back out the cursor setup,
             * discard the stack of pages, and do the split.
             */
            if (isdeleted)
                  __bam_ca_replace(dbp, h->pgno, indx, REPLACE_FAILED);

            (void)__bam_stkrel(dbp);
            stack = 0;

            if ((ret = __bam_split(dbp, key)) != 0)
                  break;

            goto retry;
            /* NOTREACHED */
      default:
            if (isdeleted)
                  __bam_ca_replace(dbp, h->pgno, indx, REPLACE_FAILED);
            break;
      }

err:  if (stack)
            (void)__bam_stkrel(dbp);

      PUTHANDLE(dbp);
      return (ret);
}

/*
 * __bam_isdeleted --
 *    Return if the only remaining data item for the element has been
 *    deleted.
 */
static int
__bam_isdeleted(dbp, h, indx, isdeletedp)
      DB *dbp;
      PAGE *h;
      u_int32_t indx;
      int *isdeletedp;
{
      BKEYDATA *bk;
      db_pgno_t pgno;
      int ret;

      *isdeletedp = 1;
      for (;;) {
            bk = GET_BKEYDATA(h, indx + O_INDX);
            switch (B_TYPE(bk->type)) {
            case B_KEYDATA:
            case B_OVERFLOW:
                  if (!B_DISSET(bk->type)) {
                        *isdeletedp = 0;
                        return (0);
                  }
                  break;
            case B_DUPLICATE:
                  /*
                   * If the data item referencing the off-page duplicates
                   * is flagged as deleted, we're done.  Else, we have to
                   * walk the chain of duplicate pages.
                   */
                  if (B_DISSET(bk->type))
                        return (0);
                  goto dupchk;
            default:
                  return (__db_pgfmt(dbp, h->pgno));
            }

            /*
             * If there are no more on-page duplicate items, then every
             * data item for this key must have been deleted.
             */
            if (indx + P_INDX >= (u_int32_t)NUM_ENT(h))
                  return (0);
            if (h->inp[indx] != h->inp[indx + P_INDX])
                  return (0);

            /* Check the next item. */
            indx += P_INDX;
      }
      /* NOTREACHED */

dupchk:     /* Check a chain of duplicate pages. */
      pgno = ((BOVERFLOW *)bk)->pgno;
      for (;;) {
            /* Acquire the next page in the duplicate chain. */
            if ((ret = memp_fget(dbp->mpf, &pgno, 0, &h)) != 0)
                  return (ret);

            /* Check each item for a delete flag. */
            for (indx = 0; indx < NUM_ENT(h); ++indx)
                  if (!B_DISSET(GET_BKEYDATA(h, indx)->type)) {
                        *isdeletedp = 0;
                        goto done;
                  }
            /*
             * If we reach the end of the duplicate pages, then every
             * item we reviewed must have been deleted.
             */
            if ((pgno = NEXT_PGNO(h)) == PGNO_INVALID)
                  goto done;

            (void)memp_fput(dbp->mpf, h, 0);
      }
      /* NOTREACHED */

done: (void)memp_fput(dbp->mpf, h, 0);
      return (0);
}

/*
 * __bam_lookup --
 *    Find the right location in the tree for the key.
 */
static int
__bam_lookup(dbp, key, exactp)
      DB *dbp;
      DBT *key;
      int *exactp;
{
      BTREE *t;
      DB_LOCK lock;
      EPG e;
      PAGE *h;
      db_indx_t indx;
      int cmp, ret;

      t = dbp->internal;
      h = NULL;

      /*
       * Record numbers can't be fast-tracked, we have to lock the entire
       * tree.
       */
      if (F_ISSET(dbp, DB_BT_RECNUM))
            goto slow;

      /* Check to see if we've been seeing sorted input. */
      if (t->bt_lpgno == PGNO_INVALID)
            goto slow;

      /*
       * Retrieve the page on which we did the last insert.  It's okay if
       * it doesn't exist, or if it's not the page type we expect, it just
       * means that the world changed.
       */
      if (__bam_lget(dbp, 0, t->bt_lpgno, DB_LOCK_WRITE, &lock))
            goto miss;
      if (__bam_pget(dbp, &h, &t->bt_lpgno, 0)) {
            (void)__BT_LPUT(dbp, lock);
            goto miss;
      }
      if (TYPE(h) != P_LBTREE)
            goto miss;
      if (NUM_ENT(h) == 0)
            goto miss;

      /*
       * We have to be at the end or beginning of the tree to know that
       * we're inserting in a sort order.  If that's the case and we're
       * in the right order in comparison to the first/last key/data pair,
       * we have the right position.
       */
      if (h->next_pgno == PGNO_INVALID) {
            e.page = h;
            e.indx = NUM_ENT(h) - P_INDX;
            if ((cmp = __bam_cmp(dbp, key, &e)) >= 0) {
                  if (cmp > 0)
                        e.indx += P_INDX;
                  goto fast;
            }
      }
      if (h->prev_pgno == PGNO_INVALID) {
            e.page = h;
            e.indx = 0;
            if ((cmp = __bam_cmp(dbp, key, &e)) <= 0) {
                  /*
                   * We're doing a put, so we want to insert as the last
                   * of any set of duplicates.
                   */
                  if (cmp == 0) {
                        for (indx = 0;
                            indx < (db_indx_t)(NUM_ENT(h) - P_INDX) &&
                            h->inp[indx] == h->inp[indx + P_INDX];
                            indx += P_INDX)
                              ;
                        e.indx = indx;
                  }
                  goto fast;
            }
      }
      goto miss;

      /* Set the exact match flag in case we've already inserted this key. */
fast: *exactp = cmp == 0;

      /* Enter the entry in the stack. */
      BT_STK_CLR(t);
      BT_STK_ENTER(t, e.page, e.indx, lock, ret);
      if (ret != 0)
            return (ret);

      ++t->lstat.bt_cache_hit;
      return (0);

miss: ++t->lstat.bt_cache_miss;
      if (h != NULL) {
            (void)memp_fput(dbp->mpf, h, 0);
            (void)__BT_LPUT(dbp, lock);
      }

slow: return (__bam_search(dbp, key, S_INSERT, 1, NULL, exactp));
}

/*
 * __bam_iitem --
 *    Insert an item into the tree.
 *
 * PUBLIC: int __bam_iitem __P((DB *,
 * PUBLIC:    PAGE **, db_indx_t *, DBT *, DBT *, u_int32_t, u_int32_t));
 */
int
__bam_iitem(dbp, hp, indxp, key, data, op, flags)
      DB *dbp;
      PAGE **hp;
      db_indx_t *indxp;
      DBT *key, *data;
      u_int32_t op, flags;
{
      BTREE *t;
      BKEYDATA *bk;
      DBT tdbt;
      PAGE *h;
      db_indx_t indx, nbytes;
      u_int32_t data_size, have_bytes, need_bytes, needed;
      int bigkey, bigdata, dupadjust, replace, ret;

      COMPQUIET(bk, NULL);

      t = dbp->internal;
      h = *hp;
      indx = *indxp;
      dupadjust = replace = 0;

      /*
       * If it's a page of duplicates, call the common code to do the work.
       *
       * !!!
       * Here's where the hp and indxp are important.  The duplicate code
       * may decide to rework/rearrange the pages and indices we're using,
       * so the caller must understand that the page stack may change.
       */
      if (TYPE(h) == P_DUPLICATE) {
            /* Adjust the index for the new item if it's a DB_AFTER op. */
            if (op == DB_AFTER)
                  ++*indxp;

            /* Remove the current item if it's a DB_CURRENT op. */
            if (op == DB_CURRENT) {
                  bk = GET_BKEYDATA(*hp, *indxp);
                  switch (B_TYPE(bk->type)) {
                  case B_KEYDATA:
                        nbytes = BKEYDATA_SIZE(bk->len);
                        break;
                  case B_OVERFLOW:
                        nbytes = BOVERFLOW_SIZE;
                        break;
                  default:
                        return (__db_pgfmt(dbp, h->pgno));
                  }
                  if ((ret = __db_ditem(dbp, *hp, *indxp, nbytes)) != 0)
                        return (ret);
            }

            /* Put the new/replacement item onto the page. */
            if ((ret = __db_dput(dbp, data, hp, indxp, __bam_new)) != 0)
                  return (ret);

            goto done;
      }

      /* Handle fixed-length records: build the real record. */
      if (F_ISSET(dbp, DB_RE_FIXEDLEN) && data->size != t->bt_recno->re_len) {
            tdbt = *data;
            if ((ret = __bam_fixed(t, &tdbt)) != 0)
                  return (ret);
            data = &tdbt;
      }

      /*
       * Figure out how much space the data will take, including if it's a
       * partial record.  If either of the key or data items won't fit on
       * a page, we'll have to store them on overflow pages.
       */
      bigkey = LF_ISSET(BI_NEWKEY) && key->size > t->bt_ovflsize;
      data_size = F_ISSET(data, DB_DBT_PARTIAL) ?
          __bam_partsize(data, h, indx) : data->size;
      bigdata = data_size > t->bt_ovflsize;

      needed = 0;
      if (LF_ISSET(BI_NEWKEY)) {
            /* If BI_NEWKEY is set we're adding a new key and data pair. */
            if (bigkey)
                  needed += BOVERFLOW_PSIZE;
            else
                  needed += BKEYDATA_PSIZE(key->size);
            if (bigdata)
                  needed += BOVERFLOW_PSIZE;
            else
                  needed += BKEYDATA_PSIZE(data_size);
      } else {
            /*
             * We're either overwriting the data item of a key/data pair
             * or we're adding the data item only, i.e. a new duplicate.
             */
            if (op == DB_CURRENT) {
                  bk = GET_BKEYDATA(h,
                      indx + (TYPE(h) == P_LBTREE ? O_INDX : 0));
                  if (B_TYPE(bk->type) == B_KEYDATA)
                        have_bytes = BKEYDATA_PSIZE(bk->len);
                  else
                        have_bytes = BOVERFLOW_PSIZE;
                  need_bytes = 0;
            } else {
                  have_bytes = 0;
                  need_bytes = sizeof(db_indx_t);
            }
            if (bigdata)
                  need_bytes += BOVERFLOW_PSIZE;
            else
                  need_bytes += BKEYDATA_PSIZE(data_size);

            if (have_bytes < need_bytes)
                  needed += need_bytes - have_bytes;
      }

      /*
       * If there's not enough room, or the user has put a ceiling on the
       * number of keys permitted in the page, split the page.
       *
       * XXX
       * The t->bt_maxkey test here may be insufficient -- do we have to
       * check in the btree split code, so we don't undo it there!?!?
       */
      if (P_FREESPACE(h) < needed ||
          (t->bt_maxkey != 0 && NUM_ENT(h) > t->bt_maxkey))
            return (DB_NEEDSPLIT);

      /* Handle partial puts: build the real record. */
      if (F_ISSET(data, DB_DBT_PARTIAL)) {
            tdbt = *data;
            if ((ret = __bam_partial(dbp, &tdbt, h, indx, data_size)) != 0)
                  return (ret);
            data = &tdbt;
      }

      /*
       * The code breaks it up into six cases:
       *
       * 1. Append a new key/data pair.
       * 2. Insert a new key/data pair.
       * 3. Append a new data item (a new duplicate).
       * 4. Insert a new data item (a new duplicate).
       * 5. Overflow item: delete and re-add the data item.
       * 6. Replace the data item.
       */
      if (LF_ISSET(BI_NEWKEY)) {
            switch (op) {
            case DB_AFTER:          /* 1. Append a new key/data pair. */
                  indx += 2;
                  *indxp += 2;
                  break;
            case DB_BEFORE:         /* 2. Insert a new key/data pair. */
                  break;
            default:
                  return (EINVAL);
            }

            /* Add the key. */
            if (bigkey) {
                  if ((ret = __bam_ovput(dbp, h, indx, key)) != 0)
                        return (ret);
            } else
                  if ((ret = __db_pitem(dbp, h, indx,
                      BKEYDATA_SIZE(key->size), NULL, key)) != 0)
                        return (ret);
            ++indx;
      } else {
            switch (op) {
            case DB_AFTER:          /* 3. Append a new data item. */
                  if (TYPE(h) == P_LBTREE) {
                        /*
                         * Adjust the cursor and copy in the key for
                         * the duplicate.
                         */
                        if ((ret = __bam_adjindx(dbp,
                            h, indx + P_INDX, indx, 1)) != 0)
                              return (ret);

                        indx += 3;
                        dupadjust = 1;

                        *indxp += 2;
                  } else {
                        ++indx;
                        __bam_ca_di(dbp, h->pgno, indx, 1);

                        *indxp += 1;
                  }
                  break;
            case DB_BEFORE:         /* 4. Insert a new data item. */
                  if (TYPE(h) == P_LBTREE) {
                        /*
                         * Adjust the cursor and copy in the key for
                         * the duplicate.
                         */
                        if ((ret =
                            __bam_adjindx(dbp, h, indx, indx, 1)) != 0)
                              return (ret);

                        ++indx;
                        dupadjust = 1;
                  } else
                        __bam_ca_di(dbp, h->pgno, indx, 1);
                  break;
            case DB_CURRENT:
                  if (TYPE(h) == P_LBTREE)
                        ++indx;

                  /*
                   * 5. Delete/re-add the data item.
                   *
                   * If we're dealing with offpage items, we have to
                   * delete and then re-add the item.
                   */
                  if (bigdata || B_TYPE(bk->type) != B_KEYDATA) {
                        if ((ret = __bam_ditem(dbp, h, indx)) != 0)
                              return (ret);
                        break;
                  }

                  /* 6. Replace the data item. */
                  replace = 1;
                  break;
            default:
                  return (EINVAL);
            }
      }

      /* Add the data. */
      if (bigdata) {
            if ((ret = __bam_ovput(dbp, h, indx, data)) != 0)
                  return (ret);
      } else {
            BKEYDATA __bk;
            DBT __hdr;

            if (LF_ISSET(BI_DELETED)) {
                  B_TSET(__bk.type, B_KEYDATA, 1);
                  __bk.len = data->size;
                  __hdr.data = &__bk;
                  __hdr.size = SSZA(BKEYDATA, data);
                  ret = __db_pitem(dbp, h, indx,
                      BKEYDATA_SIZE(data->size), &__hdr, data);
            } else if (replace)
                  ret = __bam_ritem(dbp, h, indx, data);
            else
                  ret = __db_pitem(dbp, h, indx,
                      BKEYDATA_SIZE(data->size), NULL, data);
            if (ret != 0)
                  return (ret);
      }

      if ((ret = memp_fset(dbp->mpf, h, DB_MPOOL_DIRTY)) != 0)
            return (ret);

      /*
       * If the page is at least 50% full, and we added a duplicate, see if
       * that set of duplicates takes up at least 25% of the space.  If it
       * does, move it off onto its own page.
       */
      if (dupadjust && P_FREESPACE(h) <= dbp->pgsize / 2) {
            --indx;
            if ((ret = __bam_ndup(dbp, h, indx)) != 0)
                  return (ret);
      }

      /*
       * If we've changed the record count, update the tree.  Record counts
       * need to be updated in recno databases and in btree databases where
       * we are supporting records.  In both cases, adjust the count if the
       * operation wasn't performed on the current record or when the caller
       * overrides and wants the adjustment made regardless.
       */
done: if (LF_ISSET(BI_DOINCR) ||
          (op != DB_CURRENT &&
          (F_ISSET(dbp, DB_BT_RECNUM) || dbp->type == DB_RECNO)))
            if ((ret = __bam_adjust(dbp, t, 1)) != 0)
                  return (ret);

      /* If we've modified a recno file, set the flag */
      if (t->bt_recno != NULL)
            F_SET(t->bt_recno, RECNO_MODIFIED);

      ++t->lstat.bt_added;

      return (ret);
}

/*
 * __bam_partsize --
 *    Figure out how much space a partial data item is in total.
 */
static u_int32_t
__bam_partsize(data, h, indx)
      DBT *data;
      PAGE *h;
      u_int32_t indx;
{
      BKEYDATA *bk;
      u_int32_t nbytes;

      /*
       * Figure out how much total space we'll need.  If the record doesn't
       * already exist, it's simply the data we're provided.
       */
      if (indx >= NUM_ENT(h))
            return (data->doff + data->size);

      /*
       * Otherwise, it's the data provided plus any already existing data
       * that we're not replacing.
       */
      bk = GET_BKEYDATA(h, indx + (TYPE(h) == P_LBTREE ? O_INDX : 0));
      nbytes =
          B_TYPE(bk->type) == B_OVERFLOW ? ((BOVERFLOW *)bk)->tlen : bk->len;

      /*
       * There are really two cases here:
       *
       * Case 1: We are replacing some bytes that do not exist (i.e., they
       * are past the end of the record).  In this case the number of bytes
       * we are replacing is irrelevant and all we care about is how many
       * bytes we are going to add from offset.  So, the new record length
       * is going to be the size of the new bytes (size) plus wherever those
       * new bytes begin (doff).
       *
       * Case 2: All the bytes we are replacing exist.  Therefore, the new
       * size is the oldsize (nbytes) minus the bytes we are replacing (dlen)
       * plus the bytes we are adding (size).
       */
      if (nbytes < data->doff + data->dlen)           /* Case 1 */
            return (data->doff + data->size);

      return (nbytes + data->size - data->dlen);      /* Case 2 */
}

/*
 * OVPUT --
 *    Copy an overflow item onto a page.
 */
#undef      OVPUT
#define     OVPUT(h, indx, bo) do {                               \
      DBT __hdr;                                      \
      memset(&__hdr, 0, sizeof(__hdr));                     \
      __hdr.data = &bo;                               \
      __hdr.size = BOVERFLOW_SIZE;                          \
      if ((ret = __db_pitem(dbp,                            \
          h, indx, BOVERFLOW_SIZE, &__hdr, NULL)) != 0)           \
            return (ret);                                   \
} while (0)

/*
 * __bam_ovput --
 *    Build an overflow item and put it on the page.
 */
static int
__bam_ovput(dbp, h, indx, item)
      DB *dbp;
      PAGE *h;
      u_int32_t indx;
      DBT *item;
{
      BOVERFLOW bo;
      int ret;

      B_TSET(bo.type, B_OVERFLOW, 0);
      bo.tlen = item->size;
      if ((ret = __db_poff(dbp, item, &bo.pgno, __bam_new)) != 0)
            return (ret);

      OVPUT(h, indx, bo);

      return (0);
}

/*
 * __bam_ritem --
 *    Replace an item on a page.
 *
 * PUBLIC: int __bam_ritem __P((DB *, PAGE *, u_int32_t, DBT *));
 */
int
__bam_ritem(dbp, h, indx, data)
      DB *dbp;
      PAGE *h;
      u_int32_t indx;
      DBT *data;
{
      BKEYDATA *bk;
      DBT orig, repl;
      db_indx_t cnt, lo, ln, min, off, prefix, suffix;
      int32_t nbytes;
      int ret;
      u_int8_t *p, *t;

      /*
       * Replace a single item onto a page.  The logic figuring out where
       * to insert and whether it fits is handled in the caller.  All we do
       * here is manage the page shuffling.
       */
      bk = GET_BKEYDATA(h, indx);

      /* Log the change. */
      if (DB_LOGGING(dbp)) {
            /*
             * We might as well check to see if the two data items share
             * a common prefix and suffix -- it can save us a lot of log
             * message if they're large.
             */
            min = data->size < bk->len ? data->size : bk->len;
            for (prefix = 0,
                p = bk->data, t = data->data;
                prefix < min && *p == *t; ++prefix, ++p, ++t)
                  ;

            min -= prefix;
            for (suffix = 0,
                p = (u_int8_t *)bk->data + bk->len - 1,
                t = (u_int8_t *)data->data + data->size - 1;
                suffix < min && *p == *t; ++suffix, --p, --t)
                  ;

            /* We only log the parts of the keys that have changed. */
            orig.data = (u_int8_t *)bk->data + prefix;
            orig.size = bk->len - (prefix + suffix);
            repl.data = (u_int8_t *)data->data + prefix;
            repl.size = data->size - (prefix + suffix);
            if ((ret = __bam_repl_log(dbp->dbenv->lg_info, dbp->txn,
                &LSN(h), 0, dbp->log_fileid, PGNO(h), &LSN(h),
                (u_int32_t)indx, (u_int32_t)B_DISSET(bk->type),
                &orig, &repl, (u_int32_t)prefix, (u_int32_t)suffix)) != 0)
                  return (ret);
      }

      /*
       * Set references to the first in-use byte on the page and the
       * first byte of the item being replaced.
       */
      p = (u_int8_t *)h + HOFFSET(h);
      t = (u_int8_t *)bk;

      /*
       * If the entry is growing in size, shift the beginning of the data
       * part of the page down.  If the entry is shrinking in size, shift
       * the beginning of the data part of the page up.  Use memmove(3),
       * the regions overlap.
       */
      lo = BKEYDATA_SIZE(bk->len);
      ln = BKEYDATA_SIZE(data->size);
      if (lo != ln) {
            nbytes = lo - ln;       /* Signed difference. */
            if (p == t)             /* First index is fast. */
                  h->inp[indx] += nbytes;
            else {                        /* Else, shift the page. */
                  memmove(p + nbytes, p, t - p);

                  /* Adjust the indices' offsets. */
                  off = h->inp[indx];
                  for (cnt = 0; cnt < NUM_ENT(h); ++cnt)
                        if (h->inp[cnt] <= off)
                              h->inp[cnt] += nbytes;
            }

            /* Clean up the page and adjust the item's reference. */
            HOFFSET(h) += nbytes;
            t += nbytes;
      }

      /* Copy the new item onto the page. */
      bk = (BKEYDATA *)t;
      B_TSET(bk->type, B_KEYDATA, 0);
      bk->len = data->size;
      memcpy(bk->data, data->data, data->size);

      return (0);
}

/*
 * __bam_ndup --
 *    Check to see if the duplicate set at indx should have its own page.
 *    If it should, create it.
 */
static int
__bam_ndup(dbp, h, indx)
      DB *dbp;
      PAGE *h;
      u_int32_t indx;
{
      BKEYDATA *bk;
      BOVERFLOW bo;
      DBT hdr;
      PAGE *cp;
      db_indx_t cnt, cpindx, first, sz;
      int ret;

      while (indx > 0 && h->inp[indx] == h->inp[indx - P_INDX])
            indx -= P_INDX;
      for (cnt = 0, sz = 0, first = indx;; ++cnt, indx += P_INDX) {
            if (indx >= NUM_ENT(h) || h->inp[first] != h->inp[indx])
                  break;
            bk = GET_BKEYDATA(h, indx);
            sz += B_TYPE(bk->type) == B_KEYDATA ?
                BKEYDATA_PSIZE(bk->len) : BOVERFLOW_PSIZE;
            bk = GET_BKEYDATA(h, indx + O_INDX);
            sz += B_TYPE(bk->type) == B_KEYDATA ?
                BKEYDATA_PSIZE(bk->len) : BOVERFLOW_PSIZE;
      }

      /*
       * If this set of duplicates is using more than 25% of the page, move
       * them off.  The choice of 25% is a WAG, but it has to be small enough
       * that we can always split regardless of the presence of duplicates.
       */
      if (sz < dbp->pgsize / 4)
            return (0);

      /* Get a new page. */
      if ((ret = __bam_new(dbp, P_DUPLICATE, &cp)) != 0)
            return (ret);

      /*
       * Move this set of duplicates off the page.  First points to the first
       * key of the first duplicate key/data pair, cnt is the number of pairs
       * we're dealing with.
       */
      memset(&hdr, 0, sizeof(hdr));
      for (indx = first + O_INDX, cpindx = 0;; ++cpindx) {
            /* Copy the entry to the new page. */
            bk = GET_BKEYDATA(h, indx);
            hdr.data = bk;
            hdr.size = B_TYPE(bk->type) == B_KEYDATA ?
                BKEYDATA_SIZE(bk->len) : BOVERFLOW_SIZE;
            if ((ret =
                __db_pitem(dbp, cp, cpindx, hdr.size, &hdr, NULL)) != 0)
                  goto err;

            /*
             * Move cursors referencing the old entry to the new entry.
             * Done after the page put because __db_pitem() adjusts
             * cursors on the new page, and before the delete because
             * __db_ditem adjusts cursors on the old page.
             */
            __bam_ca_dup(dbp,
                PGNO(h), first, indx - O_INDX, PGNO(cp), cpindx);

            /* Delete the data item. */
            if ((ret = __db_ditem(dbp, h, indx, hdr.size)) != 0)
                  goto err;

            /* Delete all but the first reference to the key. */
            if (--cnt == 0)
                  break;
            if ((ret = __bam_adjindx(dbp, h, indx, first, 0)) != 0)
                  goto err;
      }

      /* Put in a new data item that points to the duplicates page. */
      B_TSET(bo.type, B_DUPLICATE, 0);
      bo.pgno = cp->pgno;
      bo.tlen = 0;

      OVPUT(h, indx, bo);

      return (memp_fput(dbp->mpf, cp, DB_MPOOL_DIRTY));

err:  (void)__bam_free(dbp, cp);
      return (ret);
}

/*
 * __bam_fixed --
 *    Build the real record for a fixed length put.
 */
static int
__bam_fixed(t, dbt)
      BTREE *t;
      DBT *dbt;
{
      RECNO *rp;

      rp = t->bt_recno;

      /*
       * If database contains fixed-length records, and the record is long,
       * return EINVAL.
       */
      if (dbt->size > rp->re_len)
            return (EINVAL);

      /*
       * The caller checked to see if it was just right, so we know it's
       * short.  Pad it out.  We use the record data return memory, it's
       * only a short-term use.
       */
      if (t->bt_rdata.ulen < rp->re_len) {
            t->bt_rdata.data = t->bt_rdata.data == NULL ?
                (void *)__db_malloc(rp->re_len) :
                (void *)__db_realloc(t->bt_rdata.data, rp->re_len);
            if (t->bt_rdata.data == NULL) {
                  t->bt_rdata.ulen = 0;
                  return (ENOMEM);
            }
            t->bt_rdata.ulen = rp->re_len;
      }
      memcpy(t->bt_rdata.data, dbt->data, dbt->size);
      memset((u_int8_t *)t->bt_rdata.data + dbt->size,
          rp->re_pad, rp->re_len - dbt->size);

      /*
       * Clean up our flags and other information just in case, and
       * change the caller's DBT to reference our created record.
       */
      t->bt_rdata.size = rp->re_len;
      t->bt_rdata.dlen = 0;
      t->bt_rdata.doff = 0;
      t->bt_rdata.flags = 0;
      *dbt = t->bt_rdata;

      return (0);
}

/*
 * __bam_partial --
 *    Build the real record for a partial put.
 */
static int
__bam_partial(dbp, dbt, h, indx, nbytes)
      DB *dbp;
      DBT *dbt;
      PAGE *h;
      u_int32_t indx, nbytes;
{
      BTREE *t;
      BKEYDATA *bk, tbk;
      BOVERFLOW *bo;
      DBT copy;
      u_int32_t len, tlen;
      u_int8_t *p;
      int ret;

      COMPQUIET(bo, NULL);

      t = dbp->internal;

      /* We use the record data return memory, it's only a short-term use. */
      if (t->bt_rdata.ulen < nbytes) {
            t->bt_rdata.data = t->bt_rdata.data == NULL ?
                (void *)__db_malloc(nbytes) :
                (void *)__db_realloc(t->bt_rdata.data, nbytes);
            if (t->bt_rdata.data == NULL) {
                  t->bt_rdata.ulen = 0;
                  return (ENOMEM);
            }
            t->bt_rdata.ulen = nbytes;
      }

      /* Find the current record. */
      if (indx < NUM_ENT(h)) {
            bk = GET_BKEYDATA(h, indx + (TYPE(h) == P_LBTREE ? O_INDX : 0));
            bo = (BOVERFLOW *)bk;
      } else {
            bk = &tbk;
            B_TSET(bk->type, B_KEYDATA, 0);
            bk->len = 0;
      }

      /*
       * We use nul bytes for any part of the record that isn't specified,
       * get it over with.
       */
      memset(t->bt_rdata.data, 0, nbytes);

      if (B_TYPE(bk->type) == B_OVERFLOW) {
            /*
             * In the case of an overflow record, we shift things around
             * in the current record rather than allocate a separate copy.
             */
            memset(&copy, 0, sizeof(copy));
            if ((ret = __db_goff(dbp, &copy, bo->tlen,
                bo->pgno, &t->bt_rdata.data, &t->bt_rdata.ulen)) != 0)
                  return (ret);

            /* Skip any leading data from the original record. */
            tlen = dbt->doff;
            p = (u_int8_t *)t->bt_rdata.data + dbt->doff;

            /*
             * Copy in any trailing data from the original record.
             *
             * If the original record was larger than the original offset
             * plus the bytes being deleted, there is trailing data in the
             * original record we need to preserve.  If we aren't deleting
             * the same number of bytes as we're inserting, copy it up or
             * down, into place.
             *
             * Use memmove(), the regions may overlap.
             */
            if (bo->tlen > dbt->doff + dbt->dlen) {
                  len = bo->tlen - (dbt->doff + dbt->dlen);
                  if (dbt->dlen != dbt->size)
                        memmove(p + dbt->size, p + dbt->dlen, len);
                  tlen += len;
            }

            /* Copy in the application provided data. */
            memcpy(p, dbt->data, dbt->size);
            tlen += dbt->size;
      } else {
            /* Copy in any leading data from the original record. */
            memcpy(t->bt_rdata.data,
                bk->data, dbt->doff > bk->len ? bk->len : dbt->doff);
            tlen = dbt->doff;
            p = (u_int8_t *)t->bt_rdata.data + dbt->doff;

            /* Copy in the application provided data. */
            memcpy(p, dbt->data, dbt->size);
            tlen += dbt->size;

            /* Copy in any trailing data from the original record. */
            len = dbt->doff + dbt->dlen;
            if (bk->len > len) {
                  memcpy(p + dbt->size, bk->data + len, bk->len - len);
                  tlen += bk->len - len;
            }
      }

      /* Set the DBT to reference our new record. */
      t->bt_rdata.size = tlen;
      t->bt_rdata.dlen = 0;
      t->bt_rdata.doff = 0;
      t->bt_rdata.flags = 0;
      *dbt = t->bt_rdata;
      return (0);
}

Generated by  Doxygen 1.6.0   Back to index