libs/dbprim/ht_remove.c

   1 /*
   2 ** Copyright (C) 2002 by Kevin L. Mitchell <klmitch@mit.edu>
   3 **
   4 ** This library is free software; you can redistribute it and/or
   5 ** modify it under the terms of the GNU Library General Public
   6 ** License as published by the Free Software Foundation; either
   7 ** version 2 of the License, or (at your option) any later version.
   8 **
   9 ** This library is distributed in the hope that it will be useful,
  10 ** but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12 ** Library General Public License for more details.
  13 **
  14 ** You should have received a copy of the GNU Library General Public
  15 ** License along with this library; if not, write to the Free
  16 ** Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  17 ** MA 02111-1307, USA
  18 **
  19 ** @(#)$Id: ht_remove.c,v 1.1 2003/03/07 02:36:11 klmitch Exp $
  20 */
  21 #include "dbprim.h"
  22 #include "dbprim_int.h"
  23
  24 RCSTAG("@(#)$Id: ht_remove.c,v 1.1 2003/03/07 02:36:11 klmitch Exp $");
  25
  26 /** \ingroup dbprim_hash
  27  * \brief Remove an element from a hash table.
  28  *
  29  * This function removes the given element from the specified hash
  30  * table.
  31  *
  32  * \param table A pointer to a #hash_table_t.
  33  * \param entry A pointer to a #hash_entry_t to be removed from the
  34  *              table.
  35  *
  36  * \retval DB_ERR_BADARGS       An invalid argument was given.
  37  * \retval DB_ERR_UNUSED        Entry is not in a hash table.
  38  * \retval DB_ERR_WRONGTABLE    Entry is not in this hash table.
  39  * \retval DB_ERR_FROZEN        Hash table is frozen.
  40  * \retval DB_ERR_UNRECOVERABLE An unrecoverable error occurred while
  41  *                              resizing the table.
  42  */
  43 unsigned long
  44 ht_remove(hash_table_t *table, hash_entry_t *entry)
  45 {
  46   unsigned long retval = 0;
  47
  48   initialize_dbpr_error_table(); /* initialize error table */
  49
  50   if (!ht_verify(table) || !he_verify(entry)) /* verify arguments */
  51     return DB_ERR_BADARGS;
  52
  53   if (!entry->he_table) /* it's not in a table */
  54     return DB_ERR_UNUSED;
  55   if (entry->he_table != table) /* it's in the wrong table */
  56     return DB_ERR_WRONGTABLE;
  57
  58   if (table->ht_flags & HASH_FLAG_FREEZE) /* don't remove from frozen tables */
  59     return DB_ERR_FROZEN;
  60
  61   /* remove the entry from the table */
  62   if ((retval = ll_remove(&table->ht_table[entry->he_hash], &entry->he_elem)))
  63     return retval;
  64
  65   entry->he_table = 0; /* reset the table */
  66
  67   /* decrement element count and shrink the table if necessary and allowed */
  68   if (--table->ht_count < table->ht_rollunder &&
  69       (table->ht_flags & HASH_FLAG_AUTOSHRINK))
  70     retval = ht_resize(table, 0);
  71
  72   return retval;
  73 }