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bt_put.c

/*-
 * 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
 * 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.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)bt_put.c      8.8 (Berkeley) 7/26/94";
#endif /* LIBC_SCCS and not lint */

#include <sys/types.h>

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <db.h>
#include "btree.h"

static EPG *bt_fast __P((BTREE *, const DBT *, const DBT *, int *));

/*
 * __BT_PUT -- Add a btree item to the tree.
 *
 * Parameters:
 *    dbp:  pointer to access method
 *    key:  key
 *    data: data
 *    flag: R_NOOVERWRITE
 *
 * Returns:
 *    RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key is already in the
 *    tree and R_NOOVERWRITE specified.
 */
int
__bt_put(dbp, key, data, flags)
      const DB *dbp;
      DBT *key;
      const DBT *data;
      u_int flags;
{
      BTREE *t;
      DBT tkey, tdata;
      EPG *e;
      PAGE *h;
      indx_t index, nxtindex;
      pgno_t pg;
      u_int32_t nbytes;
      int dflags, exact, status;
      char *dest, db[NOVFLSIZE], kb[NOVFLSIZE];

      t = dbp->internal;

      /* Toss any page pinned across calls. */
      if (t->bt_pinned != NULL) {
            mpool_put(t->bt_mp, t->bt_pinned, 0);
            t->bt_pinned = NULL;
      }

      /* Check for change to a read-only tree. */
      if (F_ISSET(t, B_RDONLY)) {
            errno = EPERM;
            return (RET_ERROR);
      }

      switch (flags) {
      case 0:
      case R_NOOVERWRITE:
            break;
      case R_CURSOR:
            /*
             * If flags is R_CURSOR, put the cursor.  Must already
             * have started a scan and not have already deleted it.
             */
            if (F_ISSET(&t->bt_cursor, CURS_INIT) &&
                !F_ISSET(&t->bt_cursor,
                    CURS_ACQUIRE | CURS_AFTER | CURS_BEFORE))
                  break;
            /* FALLTHROUGH */
      default:
            errno = EINVAL;
            return (RET_ERROR);
      }

      /*
       * If the key/data pair won't fit on a page, store it on overflow
       * pages.  Only put the key on the overflow page if the pair are
       * still too big after moving the data to an overflow page.
       *
       * XXX
       * If the insert fails later on, the overflow pages aren't recovered.
       */
      dflags = 0;
      if (key->size + data->size > t->bt_ovflsize) {
            if (key->size > t->bt_ovflsize) {
storekey:         if (__ovfl_put(t, key, &pg) == RET_ERROR)
                        return (RET_ERROR);
                  tkey.data = kb;
                  tkey.size = NOVFLSIZE;
                  memmove(kb, &pg, sizeof(pgno_t));
                  memmove(kb + sizeof(pgno_t),
                      &key->size, sizeof(u_int32_t));
                  dflags |= P_BIGKEY;
                  key = &tkey;
            }
            if (key->size + data->size > t->bt_ovflsize) {
                  if (__ovfl_put(t, data, &pg) == RET_ERROR)
                        return (RET_ERROR);
                  tdata.data = db;
                  tdata.size = NOVFLSIZE;
                  memmove(db, &pg, sizeof(pgno_t));
                  memmove(db + sizeof(pgno_t),
                      &data->size, sizeof(u_int32_t));
                  dflags |= P_BIGDATA;
                  data = &tdata;
            }
            if (key->size + data->size > t->bt_ovflsize)
                  goto storekey;
      }

      /* Replace the cursor. */
      if (flags == R_CURSOR) {
            if ((h = mpool_get(t->bt_mp, t->bt_cursor.pg.pgno, 0)) == NULL)
                  return (RET_ERROR);
            index = t->bt_cursor.pg.index;
            goto delete;
      }

      /*
       * Find the key to delete, or, the location at which to insert.
       * Bt_fast and __bt_search both pin the returned page.
       */
      if (t->bt_order == NOT || (e = bt_fast(t, key, data, &exact)) == NULL)
            if ((e = __bt_search(t, key, &exact)) == NULL)
                  return (RET_ERROR);
      h = e->page;
      index = e->index;

      /*
       * Add the key/data pair to the tree.  If an identical key is already
       * in the tree, and R_NOOVERWRITE is set, an error is returned.  If
       * R_NOOVERWRITE is not set, the key is either added (if duplicates are
       * permitted) or an error is returned.
       */
      switch (flags) {
      case R_NOOVERWRITE:
            if (!exact)
                  break;
            mpool_put(t->bt_mp, h, 0);
            return (RET_SPECIAL);
      default:
            if (!exact || !F_ISSET(t, B_NODUPS))
                  break;
            /*
             * !!!
             * Note, the delete may empty the page, so we need to put a
             * new entry into the page immediately.
             */
delete:           if (__bt_dleaf(t, key, h, index) == RET_ERROR) {
                  mpool_put(t->bt_mp, h, 0);
                  return (RET_ERROR);
            }
            break;
      }

      /*
       * If not enough room, or the user has put a ceiling on the number of
       * keys permitted in the page, split the page.  The split code will
       * insert the key and data and unpin the current page.  If inserting
       * into the offset array, shift the pointers up.
       */
      nbytes = NBLEAFDBT(key->size, data->size);
      if (h->upper - h->lower < nbytes + sizeof(indx_t)) {
            if ((status = __bt_split(t, h, key,
                data, dflags, nbytes, index)) != RET_SUCCESS)
                  return (status);
            goto success;
      }

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

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

      /* If the cursor is on this page, adjust it as necessary. */
      if (F_ISSET(&t->bt_cursor, CURS_INIT) &&
          !F_ISSET(&t->bt_cursor, CURS_ACQUIRE) &&
          t->bt_cursor.pg.pgno == h->pgno && t->bt_cursor.pg.index >= index)
            ++t->bt_cursor.pg.index;

      if (t->bt_order == NOT)
            if (h->nextpg == P_INVALID) {
                  if (index == NEXTINDEX(h) - 1) {
                        t->bt_order = FORWARD;
                        t->bt_last.index = index;
                        t->bt_last.pgno = h->pgno;
                  }
            } else if (h->prevpg == P_INVALID) {
                  if (index == 0) {
                        t->bt_order = BACK;
                        t->bt_last.index = 0;
                        t->bt_last.pgno = h->pgno;
                  }
            }

      mpool_put(t->bt_mp, h, MPOOL_DIRTY);

success:
      if (flags == R_SETCURSOR)
            __bt_setcur(t, e->page->pgno, e->index);

      F_SET(t, B_MODIFIED);
      return (RET_SUCCESS);
}

#ifdef STATISTICS
u_long bt_cache_hit, bt_cache_miss;
#endif

/*
 * BT_FAST -- Do a quick check for sorted data.
 *
 * Parameters:
 *    t:    tree
 *    key:  key to insert
 *
 * Returns:
 *    EPG for new record or NULL if not found.
 */
static EPG *
bt_fast(t, key, data, exactp)
      BTREE *t;
      const DBT *key, *data;
      int *exactp;
{
      PAGE *h;
      u_int32_t nbytes;
      int cmp;

      if ((h = mpool_get(t->bt_mp, t->bt_last.pgno, 0)) == NULL) {
            t->bt_order = NOT;
            return (NULL);
      }
      t->bt_cur.page = h;
      t->bt_cur.index = t->bt_last.index;

      /*
       * If won't fit in this page or have too many keys in this page,
       * have to search to get split stack.
       */
      nbytes = NBLEAFDBT(key->size, data->size);
      if (h->upper - h->lower < nbytes + sizeof(indx_t))
            goto miss;

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

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

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