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/* |
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** Copyright (C) 2002 by Kevin L. Mitchell <klmitch@mit.edu> |
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** |
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** This library is free software; you can redistribute it and/or |
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** modify it under the terms of the GNU Library General Public |
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** License as published by the Free Software Foundation; either |
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** version 2 of the License, or (at your option) any later version. |
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** |
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** This library is distributed in the hope that it will be useful, |
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** but WITHOUT ANY WARRANTY; without even the implied warranty of |
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** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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** Library General Public License for more details. |
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** |
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** You should have received a copy of the GNU Library General Public |
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** License along with this library; if not, write to the Free |
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** Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
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** MA 02111-1307, USA |
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** |
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** @(#)$Id: ht_move.c,v 1.2 2003/06/12 01:10:04 klmitch Exp $ |
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*/ |
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#include "dbprim.h" |
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#include "dbprim_int.h" |
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|
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RCSTAG("@(#)$Id: ht_move.c,v 1.2 2003/06/12 01:10:04 klmitch Exp $"); |
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|
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/** \ingroup dbprim_hash |
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* \brief Move an entry in the hash table. |
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* |
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* This function moves an existing entry in the hash table to |
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* correspond to the new key. |
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* |
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* \param table A pointer to a #hash_table_t. |
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* \param entry A pointer to a #hash_entry_t to be moved. It must |
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* already be in the hash table. |
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* \param key A pointer to a #db_key_t describing the new key for |
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* the entry. |
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* |
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* \retval DB_ERR_BADARGS An invalid argument was given. |
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* \retval DB_ERR_UNUSED Entry is not in a hash table. |
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* \retval DB_ERR_WRONGTABLE Entry is not in this hash table. |
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* \retval DB_ERR_FROZEN Hash table is frozen. |
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* \retval DB_ERR_DUPLICATE New key is a duplicate of an existing |
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* key. |
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* \retval DB_ERR_READDFAILED Unable to re-add entry to table. |
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*/ |
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unsigned long |
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ht_move(hash_table_t *table, hash_entry_t *entry, db_key_t *key) |
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{ |
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unsigned long retval; |
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|
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initialize_dbpr_error_table(); /* initialize error table */ |
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|
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if (!ht_verify(table) || !he_verify(entry) || !key) /* verify arguments */ |
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return DB_ERR_BADARGS; |
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|
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if (!entry->he_table) /* it's not in a table */ |
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return DB_ERR_UNUSED; |
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if (entry->he_table != table) /* it's in the wrong table */ |
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return DB_ERR_WRONGTABLE; |
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|
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if (table->ht_flags & HASH_FLAG_FREEZE) /* don't mess with frozen tables */ |
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return DB_ERR_FROZEN; |
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|
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if (!ht_find(table, 0, key)) /* don't permit duplicates */ |
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return DB_ERR_DUPLICATE; |
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|
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/* remove the entry from the table */ |
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if ((retval = ll_remove(&table->ht_table[entry->he_hash], &entry->he_elem))) |
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return retval; |
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|
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/* rekey the entry */ |
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entry->he_key = *key; /* thank goodness for structure copy! */ |
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|
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/* get the new hash value for the entry */ |
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entry->he_hash = |
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(*table->ht_func)(table, &entry->he_key) % table->ht_modulus; |
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|
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/* Now re-add it to the table */ |
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if ((retval = ll_add(&table->ht_table[entry->he_hash], &entry->he_elem, |
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LINK_LOC_HEAD, 0))) { |
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table->ht_count--; /* decrement the count--don't worry about shrinking */ |
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entry->he_table = 0; /* zero the table pointer */ |
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return DB_ERR_READDFAILED; |
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} |
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|
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return 0; |
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} |
