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<?php
/**
* TAPCCache class file
*
* @author Alban Hanry <compte_messagerie@hotmail.com>
* @link http://www.pradosoft.com/
* @copyright Copyright © 2005 PradoSoft
* @license http://www.pradosoft.com/license/
* @version $Revision: $ $Date: $
* @package System.Data
*/
/**
* TAPCCache class
*
* TAPCCache implements a cache application module based on {@link http://www.php.net/apc APC}.
*
* By definition, cache does not ensure the existence of a value
* even if it never expires. Cache is not meant to be an persistent storage.
*
* To use this module, the APC PHP extension must be loaded.
*
* Some usage examples of TAPCCache are as follows,
* <code>
* $cache=new TAPCCache; // TAPCCache may also be loaded as a Prado application module
* $cache->init(null);
* $cache->add('object',$object);
* $object2=$cache->get('object');
* </code>
*
* If loaded, TAPCCache will register itself with {@link TApplication} as the
* cache module. It can be accessed via {@link TApplication::getCache()}.
*
* TAPCCache may be configured in application configuration file as follows
* <module id="cache" type="System.Data.TAPCCache" Prefix="apc_cache_prefix_key_"/>
*
***********************************************************************************************************
* NOTE: not backward compatible with Prado ICache, you cannot specify a timestamp for expire.
* It could be implemented, but what the point to check for a cache wich is meant to be as quick as possible
***********************************************************************************************************
*
* @author Alban Hanry <compte_messagerie@hotmail.com>
* @version $Revision: $ $Date: $
* @package System.Data
* @since 3.0b
*/
class TAPCCache extends TModule implements ICache
{
const SERIALIZED = "_serialized";
/**
* @var boolean if the module is initialized
*/
private $_initialized=false;
/**
* @var string a unique prefix used to identify this cache instance from the others
*/
protected $_prefix=null;
/**
* Initializes this module.
* This method is required by the IModule interface.
* @param TXmlElement configuration for this module, can be null
* @throws TConfigurationException if apc extension is not installed or not started, check your php.ini
*/
public function init($config)
{
$application=$this->getApplication();
if(!$application || $application->getMode()!==TApplication::STATE_PERFORMANCE)
{
if(!extension_loaded('apc'))
throw new TConfigurationException('apccache_extension_required');
}
if($application) {
if(!$this->_prefix)
$this->_prefix=$application->getUniqueID();
$application->setCache($this);
}
$this->_initialized=true;
}
/**
* @return string prefix used to cache key
*/
public function getPrefix()
{
return $this->_prefix;
}
/**
* @param string prefix to be used for cache key
* @throws TInvalidOperationException if the module is already initialized
*/
public function setPrefix($value)
{
if($this->_initialized)
throw new TInvalidOperationException('apccache_prefix_unchangeable');
else
$this->_prefix=$value;
}
/**
* Retrieves a value from cache with a specified key.
* @return mixed the value stored in cache, false if the value is not in the cache or expired.
*/
public function get($key)
{
$ret=apc_fetch($this->_prefix.$key);
if((boolean)apc_fetch($this->_prefix.$key.self::SERIALIZED))
$ret=unserialize($ret);
return $ret;
}
/**
* Stores a value identified by a key into cache.
* If the cache already contains such a key, the existing value and
* expiration time will be replaced with the new ones.
*
* @param string the key identifying the value to be cached
* @param mixed the value to be cached
* @param integer the expiration time of the value,
* 0 means never expire,
* @return boolean true if the value is successfully stored into cache, false otherwise
*/
public function set($key,$value,$expiry=0)
{
if(!is_string($value)) {
$value=serialize($value);
apc_store($this->_prefix.$key.self::SERIALIZED,1,$expiry);
}
return apc_store($this->_prefix.$key,$value,$expiry);
}
/**
* Stores a value identified by a key into cache if the cache does not contain this key.
* Nothing will be done if the cache already contains the key.
* @param string the key identifying the value to be cached
* @param mixed the value to be cached
* @param integer the expiration time of the value,
* 0 means never expire,
* @return boolean true if the value is successfully stored into cache, false otherwise
*/
public function add($key,$value,$expiry=0)
{
if(!apc_fetch($this->_prefix.$key))
return $this->set($key,$value,$expiry);
else return false;
}
/**
* Stores a value identified by a key into cache only if the cache contains this key.
* The existing value and expiration time will be overwritten with the new ones.
* @param string the key identifying the value to be cached
* @param mixed the value to be cached
* @param integer the expiration time of the value,
* 0 means never expire,
* @return boolean true if the value is successfully stored into cache, false otherwise
*/
public function replace($key,$value,$expiry=0)
{
if(apc_fetch($this->_prefix.$key))
return $this->set($key,$value,$expiry);
else return false;
}
/**
* Deletes a value with the specified key from cache
* @param string the key of the value to be deleted
* @return boolean if no error happens during deletion
*/
public function delete($key)
{
apc_delete($this->_prefix.$key.self::SERIALIZED);
return apc_delete($this->_prefix.$key);
}
/**
* Deletes all values from cache.
*/
public function flush()
{
return apc_clear_cache('user');
}
}
?>
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