bt_put.c

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/*-
 * 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 "../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 = 0;
   PAGE *h;
   indx_t idx, 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);
      idx = 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;
   idx = 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, idx) == 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 ((u_int32_t) (h->upper - h->lower) < nbytes + sizeof(indx_t)) {
      if ((status = __bt_split(t, h, key,
          data, dflags, nbytes, idx)) != RET_SUCCESS)
         return (status);
      goto success;
   }

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

   h->linp[idx] = 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 >= idx)
      ++t->bt_cursor.pg.index;

   if (t->bt_order == NOT) {
      if (h->nextpg == P_INVALID) {
         if (idx == NEXTINDEX(h) - 1) {
            t->bt_order = FORWARD;
            t->bt_last.index = idx;
            t->bt_last.pgno = h->pgno;
         }
      } else if (h->prevpg == P_INVALID) {
         if (idx == 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 ((u_int32_t) (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);
}