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R3600/modules/bibformat/lib/core/KBRetriever.inc.php
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<?
## $Id$
## This file is part of the CERN Document Server Software (CDSware).
## Copyright (C) 2002, 2003, 2004, 2005 CERN.
##
## The CDSware is free software; you can redistribute it and/or
## modify it under the terms of the GNU General Public License as
## published by the Free Software Foundation; either version 2 of the
## License, or (at your option) any later version.
##
## The CDSware is distributed in the hope that it will be useful, but
## WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
## General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with CDSware; if not, write to the Free Software Foundation, Inc.,
## 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
//==========================================================================
// File: KBRetriever.inc (flexElink core)
// Classes: KBRetriever
// Requires:
// Includes: DB
//==========================================================================
//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
// Class: KBRetriever
// Purpose: Encapsulates the retrieving of KB values defined in the FlexElink
// consiguration DB. It implements an internal cache in order to minimize
// database accesses and optimize performace. It follows the Singleton
// pattern for ensuring the existence of a single instance of this class
// Attributes:
// db -----------> Persistent MySQL connection
// cache_tables -> Array for keeping in memory kb name-kb table
// correspondence retrieved from the DB
// cache_values -> Array for keeping in memory key-value correspondence
// for a certain KB and that have been already etrieved from the DB
// Methods:
// getInstance (static) --> returns an instance of this class assuring that
// is unique
// getValue --------------> returns the string value mapped for a given
// key value in a given KB configured inseide the flexElink DB. In
// case the key or KB don't exist, an empty string is retruned
//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
class KBRetriever
{
var $db;
var $cache_tables;
var $cache_values;
function KBRetriever()
{
srand((float)microtime()*10000000);
$this->cache_tables=array();
$this->cache_values=array();
include( DB );
$this->db=mysql_pconnect( $DB_HOST, $DB_USER, $DB_PASSWD );
mysql_selectdb( $DB_DB, $this->db );
$qry="select kb_name, kb_table
from flxKBS";
$qh=mysql_query($qry, $this->db);
while($row=mysql_fetch_array($qh))
{
list($kb_name, $kb_value)=$row;
$this->cache_tables["$kb_name"]="$kb_value";
}
}
/*---------------------------------------------------------------------
Method: getInstance
Description:
Parameters:
Return value: (KBRetriever)
---------------------------------------------------------------------*/
function & getInstance()
{
static $instance;
if(!isset($instance))
{
$instance=new KBRetriever();
}
return $instance;
}
/*---------------------------------------------------------------------
Method: getValue
Description:
Parameters:
kb_name (String) --> KB identifier in flexElink database from which the
value is going to be extracted
key (String) ------> Key value to search for inside the KB
Return value: (String) Mapped value corresponding to the KB and key values
given
---------------------------------------------------------------------*/
function getValue( $kb_name, $key )
{
if(!$this->db)
return "";
$kb_name=strtoupper(trim($kb_name));
$kb_table=$this->cache_tables[$kb_name];
if(!$kb_table)
{
return "";
}
$value=$this->cache_values["$kb_table##$key"];
if($value=="")
{
$key=addslashes($key);
$qry="select value from $kb_table where vkey='$key'";
$qh=mysql_query($qry, $this->db);
if(mysql_num_rows($qh)<1)
return "";
list($value)=mysql_fetch_array($qh);
if(count($this->cache_values)>100)
{
$k=array_rand($this->cache_values);
unset($this->cache_values["$k"]);
}
$this->cache_values["$kb_table##$key"]=$value;
}
return $value;
}
}
?>
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