1 files changed, 578 insertions, 578 deletions
diff --git a/framework/Caching/TDbCache.php b/framework/Caching/TDbCache.php
index 7a149346..b4ddd086 100644
--- a/framework/Caching/TDbCache.php
+++ b/framework/Caching/TDbCache.php
@@ -1,578 +1,578 @@
-<?php
-/**
- * TDbCache class file
- *
- * @author Qiang Xue <qiang.xue@gmail.com>
- * @link http://www.pradosoft.com/
- * @copyright Copyright &copy; 2005-2012 PradoSoft
- * @license http://www.pradosoft.com/license/
- * @version $Id$
- * @package System.Caching
- */
-
-Prado::using('System.Data.TDbConnection');
-
-/**
- * TDbCache class
- *
- * TDbCache implements a cache application module by storing cached data in a database.
- *
- * TDbCache relies on {@link http://www.php.net/manual/en/ref.pdo.php PDO} to retrieve
- * data from databases. In order to use TDbCache, you need to enable the PDO extension
- * as well as the corresponding PDO DB driver. For example, to use SQLite database
- * to store cached data, you need both php_pdo and php_pdo_sqlite extensions.
- *
- * By default, TDbCache creates and uses an SQLite database under the application
- * runtime directory. You may change this default setting by specifying the following
- * properties:
- * - {@link setConnectionID ConnectionID} or
- * - {@link setConnectionString ConnectionString}, {@link setUsername Username} and {@link setPassword Pasword}.
- *
- * The cached data is stored in a table in the specified database.
- * By default, the name of the table is called 'pradocache'. If the table does not
- * exist in the database, it will be automatically created with the following structure:
- * <code>
- * CREATE TABLE pradocache (itemkey CHAR(128), value BLOB, expire INT)
- * CREATE INDEX IX_itemkey ON pradocache (itemkey)
- * CREATE INDEX IX_expire ON pradocache (expire)
- * </code>
- *
- * Note, some DBMS might not support BLOB type. In this case, replace 'BLOB' with a suitable
- * binary data type (e.g. LONGBLOB in MySQL, BYTEA in PostgreSQL.)
- *
- * Important: Make sure that the indices are non-unique!
- *
- * If you want to change the cache table name, or if you want to create the table by yourself,
- * you may set {@link setCacheTableName CacheTableName} and {@link setAutoCreateCacheTable AutoCreateCacheTableName} properties.
- *
- * {@link setFlushInterval FlushInterval} control how often expired items will be removed from cache.
- * If you prefer to remove expired items manualy e.g. via cronjob you can disable automatic deletion by setting FlushInterval to '0'.
- *
- * The following basic cache operations are implemented:
- * - {@link get} : retrieve the value with a key (if any) from cache
- * - {@link set} : store the value with a key into cache
- * - {@link add} : store the value only if cache does not have this key
- * - {@link delete} : delete the value with the specified key from cache
- * - {@link flush} : delete all values from cache
- *
- * Each value is associated with an expiration time. The {@link get} operation
- * ensures that any expired value will not be returned. The expiration time by
- * the number of seconds. A expiration time 0 represents never expire.
- *
- * 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.
- *
- * Do not use the same database file for multiple applications using TDbCache.
- * Also note, cache is shared by all user sessions of an application.
- *
- * Some usage examples of TDbCache are as follows,
- * <code>
- * $cache=new TDbCache;  // TDbCache may also be loaded as a Prado application module
- * $cache->init(null);
- * $cache->add('object',$object);
- * $object2=$cache->get('object');
- * </code>
- *
- * If loaded, TDbCache will register itself with {@link TApplication} as the
- * cache module. It can be accessed via {@link TApplication::getCache()}.
- *
- * TDbCache may be configured in application configuration file as follows
- * <code>
- * <module id="cache" class="System.Caching.TDbCache" />
- * </code>
- *
- * @author Qiang Xue <qiang.xue@gmail.com>
- * @version $Id$
- * @package System.Caching
- * @since 3.1.0
- */
-class TDbCache extends TCache
-{
-	/**
-	 * @var string the ID of TDataSourceConfig module
-	 */
-	private $_connID='';
-	/**
-	 * @var TDbConnection the DB connection instance
-	 */
-	private $_db;
-	/**
-	 * @var string name of the DB cache table
-	 */
-	private $_cacheTable='pradocache';
-	/**
-	 * @var integer Interval expired items will be removed from cache
-	 */
-	private $_flushInterval=60;
-	/**
-	 * @var boolean
-	 */
-	private $_cacheInitialized = false;
-	/**
-	 * @var boolean
-	 */
-	private $_createCheck= false;
-	/**
-	 * @var boolean whether the cache DB table should be created automatically
-	 */
-	private $_autoCreate=true;
-	private $_username='';
-	private $_password='';
-	private $_connectionString='';
-
-	/**
-	 * Destructor.
-	 * Disconnect the db connection.
-	 */
-	public function __destruct()
-	{
-		if($this->_db!==null)
-			$this->_db->setActive(false);
-	}
-
-	/**
-	 * Initializes this module.
-	 * This method is required by the IModule interface.
-	 * attach {@link doInitializeCache} to TApplication.OnLoadStateComplete event
-	 * attach {@link doFlushCacheExpired} to TApplication.OnSaveState event
-	 *
-	 * @param TXmlElement configuration for this module, can be null
-	 */
-	public function init($config)
-	{
-		$this -> getApplication() -> attachEventHandler('OnLoadStateComplete', array($this, 'doInitializeCache'));
-		$this -> getApplication() -> attachEventHandler('OnSaveState', array($this, 'doFlushCacheExpired'));
-		parent::init($config);
-	}
-
-	/**
-	 * Event listener for TApplication.OnSaveState
-	 * @return void
-	 * @since 3.1.5
-	 * @see flushCacheExpired
-	 */
-	public function doFlushCacheExpired()
-	{
-		$this->flushCacheExpired(false);
-	}
-
-	/**
-	 * Event listener for TApplication.OnLoadStateComplete
-	 *
-	 * @return void
-	 * @since 3.1.5
-	 * @see initializeCache
-	 */
-	public function doInitializeCache()
-	{
-		$this->initializeCache();
-	}
-
-	/**
-	 * Initialize TDbCache
-	 *
-	 * If {@link setAutoCreateCacheTable AutoCreateCacheTableName} is 'true' check existence of cache table
-	 * and create table if does not exist.
-	 *
-	 * @param boolean Force override global state check
-	 * @return void
-	 * @throws TConfigurationException if any error happens during creating database or cache table.
-	 * @since 3.1.5
-	 */
-	protected function initializeCache($force=false)
-	{
-		if($this->_cacheInitialized && !$force) return;
-		$db=$this->getDbConnection();
-		try
-		{
-			$key = 'TDbCache:' . $this->_cacheTable . ':created';
-			if($force)
-				$this -> _createCheck = false;
-			else
-				$this -> _createCheck = $this -> getApplication() -> getGlobalState($key, 0);
-
-			if($this->_autoCreate && !$this -> _createCheck) {
-
-				Prado::trace(($force ? 'Force initializing: ' : 'Initializing: ') . $this -> id . ', ' . $this->_cacheTable, 'System.Caching.TDbCache');
-
-				$sql='SELECT 1 FROM '.$this->_cacheTable.' WHERE 0=1';
-				$db->createCommand($sql)->queryScalar();
-
-				$this -> _createCheck = true;
-				$this -> getApplication() -> setGlobalState($key, time());
-			}
-		}
-		catch(Exception $e)
-		{
-			// DB table not exists
-			if($this->_autoCreate)
-			{
-				Prado::trace('Autocreate: ' . $this->_cacheTable, 'System.Caching.TDbCache');
-
-				$driver=$db->getDriverName();
-				if($driver==='mysql')
-					$blob='LONGBLOB';
-				else if($driver==='pgsql')
-					$blob='BYTEA';
-				else
-					$blob='BLOB';
-
-				$sql='CREATE TABLE '.$this->_cacheTable." (itemkey CHAR(128) PRIMARY KEY, value $blob, expire INTEGER)";
-				$db->createCommand($sql)->execute();
-
-				$sql='CREATE INDEX IX_expire ON ' . $this->_cacheTable . ' (expire)';
-				$db->createCommand($sql)->execute();
-
-				$this -> _createCheck = true;
-				$this -> getApplication() -> setGlobalState($key, time());
-			}
-			else
-				throw new TConfigurationException('db_cachetable_inexistent',$this->_cacheTable);
-		}
-		$this->_cacheInitialized = true;
-	}
-
-	/**
-	 * Flush expired values from cache depending on {@link setFlushInterval FlushInterval}
-	 * @param boolean override {@link setFlushInterval FlushInterval} and force deletion of expired items
-	 * @return void
-	 * @since 3.1.5
-	 */
-	public function flushCacheExpired($force=false)
-	{
-		$interval = $this -> getFlushInterval();
-		if(!$force && $interval === 0) return;
-
-		$key	= 'TDbCache:' . $this->_cacheTable . ':flushed';
-		$now	= time();
-		$next	= $interval + (integer)$this -> getApplication() -> getGlobalState($key, 0);
-
-		if($force || $next <= $now)
-		{
-			if(!$this->_cacheInitialized) $this->initializeCache();
-			Prado::trace(($force ? 'Force flush of expired items: ' : 'Flush expired items: ') . $this -> id . ', ' . $this->_cacheTable, 'System.Caching.TDbCache');
-			$sql='DELETE FROM '.$this->_cacheTable.' WHERE expire<>0 AND expire<'.$now;
-			$this->getDbConnection()->createCommand($sql)->execute();
-			$this -> getApplication() -> setGlobalState($key, $now);
-		}
-	}
-
-	/**
-	 * @return integer Interval in sec expired items will be removed from cache. Default to 60
-	 * @since 3.1.5
-	 */
-	public function getFlushInterval()
-	{
-		return $this->_flushInterval;
-	}
-
-	/**
-	 * Sets interval expired items will be removed from cache
-	 *
-	 * To disable automatic deletion of expired items,
-	 * e.g. for external flushing via cron you can set value to '0'
-	 *
-	 * @param integer Interval in sec
-	 * @since 3.1.5
-	 */
-	public function setFlushInterval($value)
-	{
-		$this->_flushInterval = (integer) $value;
-	}
-
-	/**
-	 * Creates the DB connection.
-	 * @param string the module ID for TDataSourceConfig
-	 * @return TDbConnection the created DB connection
-	 * @throws TConfigurationException if module ID is invalid or empty
-	 */
-	protected function createDbConnection()
-	{
-		if($this->_connID!=='')
-		{
-			$config=$this->getApplication()->getModule($this->_connID);
-			if($config instanceof TDataSourceConfig)
-				return $config->getDbConnection();
-			else
-				throw new TConfigurationException('dbcache_connectionid_invalid',$this->_connID);
-		}
-		else
-		{
-			$db=new TDbConnection;
-			if($this->_connectionString!=='')
-			{
-				$db->setConnectionString($this->_connectionString);
-				if($this->_username!=='')
-					$db->setUsername($this->_username);
-				if($this->_password!=='')
-					$db->setPassword($this->_password);
-			}
-			else
-			{
-				// default to SQLite3 database
-				$dbFile=$this->getApplication()->getRuntimePath().'/sqlite3.cache';
-				$db->setConnectionString('sqlite:'.$dbFile);
-			}
-			return $db;
-		}
-	}
-
-	/**
-	 * @return TDbConnection the DB connection instance
-	 */
-	public function getDbConnection()
-	{
-		if($this->_db===null)
-			$this->_db=$this->createDbConnection();
-
-		$this->_db->setActive(true);
-		return $this->_db;
-	}
-
-	/**
-	 * @return string the ID of a {@link TDataSourceConfig} module. Defaults to empty string, meaning not set.
-	 * @since 3.1.1
-	 */
-	public function getConnectionID()
-	{
-		return $this->_connID;
-	}
-
-	/**
-	 * Sets the ID of a TDataSourceConfig module.
-	 * The datasource module will be used to establish the DB connection for this cache module.
-	 * The database connection can also be specified via {@link setConnectionString ConnectionString}.
-	 * When both ConnectionID and ConnectionString are specified, the former takes precedence.
-	 * @param string ID of the {@link TDataSourceConfig} module
-	 * @since 3.1.1
-	 */
-	public function setConnectionID($value)
-	{
-		$this->_connID=$value;
-	}
-
-	/**
-	 * @return string The Data Source Name, or DSN, contains the information required to connect to the database.
-	 */
-	public function getConnectionString()
-	{
-		return $this->_connectionString;
-	}
-
-	/**
-	 * @param string The Data Source Name, or DSN, contains the information required to connect to the database.
-	 * @see http://www.php.net/manual/en/function.pdo-construct.php
-	 */
-	public function setConnectionString($value)
-	{
-		$this->_connectionString=$value;
-	}
-
-	/**
-	 * @return string the username for establishing DB connection. Defaults to empty string.
-	 */
-	public function getUsername()
-	{
-		return $this->_username;
-	}
-
-	/**
-	 * @param string the username for establishing DB connection
-	 */
-	public function setUsername($value)
-	{
-		$this->_username=$value;
-	}
-
-	/**
-	 * @return string the password for establishing DB connection. Defaults to empty string.
-	 */
-	public function getPassword()
-	{
-		return $this->_password;
-	}
-
-	/**
-	 * @param string the password for establishing DB connection
-	 */
-	public function setPassword($value)
-	{
-		$this->_password=$value;
-	}
-
-	/**
-	 * @return string the name of the DB table to store cache content. Defaults to 'pradocache'.
-	 * @see setAutoCreateCacheTable
-	 */
-	public function getCacheTableName()
-	{
-		return $this->_cacheTable;
-	}
-
-	/**
-	 * Sets the name of the DB table to store cache content.
-	 * Note, if {@link setAutoCreateCacheTable AutoCreateCacheTable} is false
-	 * and you want to create the DB table manually by yourself,
-	 * you need to make sure the DB table is of the following structure:
-	 * <code>
-	 * CREATE TABLE pradocache (itemkey CHAR(128), value BLOB, expire INT)
-	 * CREATE INDEX IX_itemkey ON pradocache (itemkey)
-	 * CREATE INDEX IX_expire ON pradocache (expire)
-	 * </code>
-	 *
-	 * Note, some DBMS might not support BLOB type. In this case, replace 'BLOB' with a suitable
-	 * binary data type (e.g. LONGBLOB in MySQL, BYTEA in PostgreSQL.)
-	 *
-	 * Important: Make sure that the indices are non-unique!
-	 *
-	 * @param string the name of the DB table to store cache content
-	 * @see setAutoCreateCacheTable
-	 */
-	public function setCacheTableName($value)
-	{
-		$this->_cacheTable=$value;
-	}
-
-	/**
-	 * @return boolean whether the cache DB table should be automatically created if not exists. Defaults to true.
-	 * @see setAutoCreateCacheTable
-	 */
-	public function getAutoCreateCacheTable()
-	{
-		return $this->_autoCreate;
-	}
-
-	/**
-	 * @param boolean whether the cache DB table should be automatically created if not exists.
-	 * @see setCacheTableName
-	 */
-	public function setAutoCreateCacheTable($value)
-	{
-		$this->_autoCreate=TPropertyValue::ensureBoolean($value);
-	}
-
-	/**
-	 * Retrieves a value from cache with a specified key.
-	 * This is the implementation of the method declared in the parent class.
-	 * @param string a unique key identifying the cached value
-	 * @return string the value stored in cache, false if the value is not in the cache or expired.
-	 */
-	protected function getValue($key)
-	{
-		if(!$this->_cacheInitialized) $this->initializeCache();
-		try {
-			$sql='SELECT value FROM '.$this->_cacheTable.' WHERE itemkey=\''.$key.'\' AND (expire=0 OR expire>'.time().') ORDER BY expire DESC';
-			$command=$this->getDbConnection()->createCommand($sql);
-			return Prado::unserialize($command->queryScalar());
-		}
-		catch(Exception $e)
-		{
-			$this->initializeCache(true);
-			return Prado::unserialize($command->queryScalar());
-		}
-	}
-
-	/**
-	 * Stores a value identified by a key in cache.
-	 * This is the implementation of the method declared in the parent class.
-	 *
-	 * @param string the key identifying the value to be cached
-	 * @param string the value to be cached
-	 * @param integer the number of seconds in which the cached value will expire. 0 means never expire.
-	 * @return boolean true if the value is successfully stored into cache, false otherwise
-	 */
-	protected function setValue($key,$value,$expire)
-	{
-		$this->deleteValue($key);
-		return $this->addValue($key,$value,$expire);
-	}
-
-	/**
-	 * Stores a value identified by a key into cache if the cache does not contain this key.
-	 * This is the implementation of the method declared in the parent class.
-	 *
-	 * @param string the key identifying the value to be cached
-	 * @param string the value to be cached
-	 * @param integer the number of seconds in which the cached value will expire. 0 means never expire.
-	 * @return boolean true if the value is successfully stored into cache, false otherwise
-	 */
-	protected function addValue($key,$value,$expire)
-	{
-		if(!$this->_cacheInitialized) $this->initializeCache();
-		$expire=($expire<=0)?0:time()+$expire;
-		$sql="INSERT INTO {$this->_cacheTable} (itemkey,value,expire) VALUES(:key,:value,$expire)";
-		try
-		{
-			$command=$this->getDbConnection()->createCommand($sql);
-			$command->bindValue(':key',$key,PDO::PARAM_STR);
-			$command->bindValue(':value',Prado::serialize($value),PDO::PARAM_LOB);
-			$command->execute();
-			return true;
-		}
-		catch(Exception $e)
-		{
-			try
-			{
-				$this->initializeCache(true);
-				$command->execute();
-				return true;
-			}
-			catch(Exception $e)
-			{
-				return false;
-			}
-		}
-	}
-
-	/**
-	 * Deletes a value with the specified key from cache
-	 * This is the implementation of the method declared in the parent class.
-	 * @param string the key of the value to be deleted
-	 * @return boolean if no error happens during deletion
-	 */
-	protected function deleteValue($key)
-	{
-		if(!$this->_cacheInitialized) $this->initializeCache();
-		try
-		{
-			$command=$this->getDbConnection()->createCommand("DELETE FROM {$this->_cacheTable} WHERE itemkey=:key");
-			$command->bindValue(':key',$key,PDO::PARAM_STR);
-			$command->execute();
-			return true;
-		}
-		catch(Exception $e)
-		{
-			$this->initializeCache(true);
-			$command->execute();
-			return true;
-		}
-	}
-
-	/**
-	 * Deletes all values from cache.
-	 * Be careful of performing this operation if the cache is shared by multiple applications.
-	 */
-	public function flush()
-	{
-		if(!$this->_cacheInitialized) $this->initializeCache();
-		try
-		{
-			$command = $this->getDbConnection()->createCommand("DELETE FROM {$this->_cacheTable}");
-			$command->execute();
-		}
-		catch(Exception $e)
-		{
-			try
-			{
-				$this->initializeCache(true);
-				$command->execute();
-				return true;
-			}
-			catch(Exception $e)
-			{
-				return false;
-			}
-		}
-		return true;
-	}
-}
+<?php
+/**
+ * TDbCache class file
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @link http://www.pradosoft.com/
+ * @copyright Copyright &copy; 2005-2012 PradoSoft
+ * @license http://www.pradosoft.com/license/
+ * @version $Id$
+ * @package System.Caching
+ */
+
+Prado::using('System.Data.TDbConnection');
+
+/**
+ * TDbCache class
+ *
+ * TDbCache implements a cache application module by storing cached data in a database.
+ *
+ * TDbCache relies on {@link http://www.php.net/manual/en/ref.pdo.php PDO} to retrieve
+ * data from databases. In order to use TDbCache, you need to enable the PDO extension
+ * as well as the corresponding PDO DB driver. For example, to use SQLite database
+ * to store cached data, you need both php_pdo and php_pdo_sqlite extensions.
+ *
+ * By default, TDbCache creates and uses an SQLite database under the application
+ * runtime directory. You may change this default setting by specifying the following
+ * properties:
+ * - {@link setConnectionID ConnectionID} or
+ * - {@link setConnectionString ConnectionString}, {@link setUsername Username} and {@link setPassword Pasword}.
+ *
+ * The cached data is stored in a table in the specified database.
+ * By default, the name of the table is called 'pradocache'. If the table does not
+ * exist in the database, it will be automatically created with the following structure:
+ * <code>
+ * CREATE TABLE pradocache (itemkey CHAR(128), value BLOB, expire INT)
+ * CREATE INDEX IX_itemkey ON pradocache (itemkey)
+ * CREATE INDEX IX_expire ON pradocache (expire)
+ * </code>
+ *
+ * Note, some DBMS might not support BLOB type. In this case, replace 'BLOB' with a suitable
+ * binary data type (e.g. LONGBLOB in MySQL, BYTEA in PostgreSQL.)
+ *
+ * Important: Make sure that the indices are non-unique!
+ *
+ * If you want to change the cache table name, or if you want to create the table by yourself,
+ * you may set {@link setCacheTableName CacheTableName} and {@link setAutoCreateCacheTable AutoCreateCacheTableName} properties.
+ *
+ * {@link setFlushInterval FlushInterval} control how often expired items will be removed from cache.
+ * If you prefer to remove expired items manualy e.g. via cronjob you can disable automatic deletion by setting FlushInterval to '0'.
+ *
+ * The following basic cache operations are implemented:
+ * - {@link get} : retrieve the value with a key (if any) from cache
+ * - {@link set} : store the value with a key into cache
+ * - {@link add} : store the value only if cache does not have this key
+ * - {@link delete} : delete the value with the specified key from cache
+ * - {@link flush} : delete all values from cache
+ *
+ * Each value is associated with an expiration time. The {@link get} operation
+ * ensures that any expired value will not be returned. The expiration time by
+ * the number of seconds. A expiration time 0 represents never expire.
+ *
+ * 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.
+ *
+ * Do not use the same database file for multiple applications using TDbCache.
+ * Also note, cache is shared by all user sessions of an application.
+ *
+ * Some usage examples of TDbCache are as follows,
+ * <code>
+ * $cache=new TDbCache;  // TDbCache may also be loaded as a Prado application module
+ * $cache->init(null);
+ * $cache->add('object',$object);
+ * $object2=$cache->get('object');
+ * </code>
+ *
+ * If loaded, TDbCache will register itself with {@link TApplication} as the
+ * cache module. It can be accessed via {@link TApplication::getCache()}.
+ *
+ * TDbCache may be configured in application configuration file as follows
+ * <code>
+ * <module id="cache" class="System.Caching.TDbCache" />
+ * </code>
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @version $Id$
+ * @package System.Caching
+ * @since 3.1.0
+ */
+class TDbCache extends TCache
+{
+	/**
+	 * @var string the ID of TDataSourceConfig module
+	 */
+	private $_connID='';
+	/**
+	 * @var TDbConnection the DB connection instance
+	 */
+	private $_db;
+	/**
+	 * @var string name of the DB cache table
+	 */
+	private $_cacheTable='pradocache';
+	/**
+	 * @var integer Interval expired items will be removed from cache
+	 */
+	private $_flushInterval=60;
+	/**
+	 * @var boolean
+	 */
+	private $_cacheInitialized = false;
+	/**
+	 * @var boolean
+	 */
+	private $_createCheck= false;
+	/**
+	 * @var boolean whether the cache DB table should be created automatically
+	 */
+	private $_autoCreate=true;
+	private $_username='';
+	private $_password='';
+	private $_connectionString='';
+
+	/**
+	 * Destructor.
+	 * Disconnect the db connection.
+	 */
+	public function __destruct()
+	{
+		if($this->_db!==null)
+			$this->_db->setActive(false);
+	}
+
+	/**
+	 * Initializes this module.
+	 * This method is required by the IModule interface.
+	 * attach {@link doInitializeCache} to TApplication.OnLoadStateComplete event
+	 * attach {@link doFlushCacheExpired} to TApplication.OnSaveState event
+	 *
+	 * @param TXmlElement configuration for this module, can be null
+	 */
+	public function init($config)
+	{
+		$this -> getApplication() -> attachEventHandler('OnLoadStateComplete', array($this, 'doInitializeCache'));
+		$this -> getApplication() -> attachEventHandler('OnSaveState', array($this, 'doFlushCacheExpired'));
+		parent::init($config);
+	}
+
+	/**
+	 * Event listener for TApplication.OnSaveState
+	 * @return void
+	 * @since 3.1.5
+	 * @see flushCacheExpired
+	 */
+	public function doFlushCacheExpired()
+	{
+		$this->flushCacheExpired(false);
+	}
+
+	/**
+	 * Event listener for TApplication.OnLoadStateComplete
+	 *
+	 * @return void
+	 * @since 3.1.5
+	 * @see initializeCache
+	 */
+	public function doInitializeCache()
+	{
+		$this->initializeCache();
+	}
+
+	/**
+	 * Initialize TDbCache
+	 *
+	 * If {@link setAutoCreateCacheTable AutoCreateCacheTableName} is 'true' check existence of cache table
+	 * and create table if does not exist.
+	 *
+	 * @param boolean Force override global state check
+	 * @return void
+	 * @throws TConfigurationException if any error happens during creating database or cache table.
+	 * @since 3.1.5
+	 */
+	protected function initializeCache($force=false)
+	{
+		if($this->_cacheInitialized && !$force) return;
+		$db=$this->getDbConnection();
+		try
+		{
+			$key = 'TDbCache:' . $this->_cacheTable . ':created';
+			if($force)
+				$this -> _createCheck = false;
+			else
+				$this -> _createCheck = $this -> getApplication() -> getGlobalState($key, 0);
+
+			if($this->_autoCreate && !$this -> _createCheck) {
+
+				Prado::trace(($force ? 'Force initializing: ' : 'Initializing: ') . $this -> id . ', ' . $this->_cacheTable, 'System.Caching.TDbCache');
+
+				$sql='SELECT 1 FROM '.$this->_cacheTable.' WHERE 0=1';
+				$db->createCommand($sql)->queryScalar();
+
+				$this -> _createCheck = true;
+				$this -> getApplication() -> setGlobalState($key, time());
+			}
+		}
+		catch(Exception $e)
+		{
+			// DB table not exists
+			if($this->_autoCreate)
+			{
+				Prado::trace('Autocreate: ' . $this->_cacheTable, 'System.Caching.TDbCache');
+
+				$driver=$db->getDriverName();
+				if($driver==='mysql')
+					$blob='LONGBLOB';
+				else if($driver==='pgsql')
+					$blob='BYTEA';
+				else
+					$blob='BLOB';
+
+				$sql='CREATE TABLE '.$this->_cacheTable." (itemkey CHAR(128) PRIMARY KEY, value $blob, expire INTEGER)";
+				$db->createCommand($sql)->execute();
+
+				$sql='CREATE INDEX IX_expire ON ' . $this->_cacheTable . ' (expire)';
+				$db->createCommand($sql)->execute();
+
+				$this -> _createCheck = true;
+				$this -> getApplication() -> setGlobalState($key, time());
+			}
+			else
+				throw new TConfigurationException('db_cachetable_inexistent',$this->_cacheTable);
+		}
+		$this->_cacheInitialized = true;
+	}
+
+	/**
+	 * Flush expired values from cache depending on {@link setFlushInterval FlushInterval}
+	 * @param boolean override {@link setFlushInterval FlushInterval} and force deletion of expired items
+	 * @return void
+	 * @since 3.1.5
+	 */
+	public function flushCacheExpired($force=false)
+	{
+		$interval = $this -> getFlushInterval();
+		if(!$force && $interval === 0) return;
+
+		$key	= 'TDbCache:' . $this->_cacheTable . ':flushed';
+		$now	= time();
+		$next	= $interval + (integer)$this -> getApplication() -> getGlobalState($key, 0);
+
+		if($force || $next <= $now)
+		{
+			if(!$this->_cacheInitialized) $this->initializeCache();
+			Prado::trace(($force ? 'Force flush of expired items: ' : 'Flush expired items: ') . $this -> id . ', ' . $this->_cacheTable, 'System.Caching.TDbCache');
+			$sql='DELETE FROM '.$this->_cacheTable.' WHERE expire<>0 AND expire<'.$now;
+			$this->getDbConnection()->createCommand($sql)->execute();
+			$this -> getApplication() -> setGlobalState($key, $now);
+		}
+	}
+
+	/**
+	 * @return integer Interval in sec expired items will be removed from cache. Default to 60
+	 * @since 3.1.5
+	 */
+	public function getFlushInterval()
+	{
+		return $this->_flushInterval;
+	}
+
+	/**
+	 * Sets interval expired items will be removed from cache
+	 *
+	 * To disable automatic deletion of expired items,
+	 * e.g. for external flushing via cron you can set value to '0'
+	 *
+	 * @param integer Interval in sec
+	 * @since 3.1.5
+	 */
+	public function setFlushInterval($value)
+	{
+		$this->_flushInterval = (integer) $value;
+	}
+
+	/**
+	 * Creates the DB connection.
+	 * @param string the module ID for TDataSourceConfig
+	 * @return TDbConnection the created DB connection
+	 * @throws TConfigurationException if module ID is invalid or empty
+	 */
+	protected function createDbConnection()
+	{
+		if($this->_connID!=='')
+		{
+			$config=$this->getApplication()->getModule($this->_connID);
+			if($config instanceof TDataSourceConfig)
+				return $config->getDbConnection();
+			else
+				throw new TConfigurationException('dbcache_connectionid_invalid',$this->_connID);
+		}
+		else
+		{
+			$db=new TDbConnection;
+			if($this->_connectionString!=='')
+			{
+				$db->setConnectionString($this->_connectionString);
+				if($this->_username!=='')
+					$db->setUsername($this->_username);
+				if($this->_password!=='')
+					$db->setPassword($this->_password);
+			}
+			else
+			{
+				// default to SQLite3 database
+				$dbFile=$this->getApplication()->getRuntimePath().'/sqlite3.cache';
+				$db->setConnectionString('sqlite:'.$dbFile);
+			}
+			return $db;
+		}
+	}
+
+	/**
+	 * @return TDbConnection the DB connection instance
+	 */
+	public function getDbConnection()
+	{
+		if($this->_db===null)
+			$this->_db=$this->createDbConnection();
+
+		$this->_db->setActive(true);
+		return $this->_db;
+	}
+
+	/**
+	 * @return string the ID of a {@link TDataSourceConfig} module. Defaults to empty string, meaning not set.
+	 * @since 3.1.1
+	 */
+	public function getConnectionID()
+	{
+		return $this->_connID;
+	}
+
+	/**
+	 * Sets the ID of a TDataSourceConfig module.
+	 * The datasource module will be used to establish the DB connection for this cache module.
+	 * The database connection can also be specified via {@link setConnectionString ConnectionString}.
+	 * When both ConnectionID and ConnectionString are specified, the former takes precedence.
+	 * @param string ID of the {@link TDataSourceConfig} module
+	 * @since 3.1.1
+	 */
+	public function setConnectionID($value)
+	{
+		$this->_connID=$value;
+	}
+
+	/**
+	 * @return string The Data Source Name, or DSN, contains the information required to connect to the database.
+	 */
+	public function getConnectionString()
+	{
+		return $this->_connectionString;
+	}
+
+	/**
+	 * @param string The Data Source Name, or DSN, contains the information required to connect to the database.
+	 * @see http://www.php.net/manual/en/function.pdo-construct.php
+	 */
+	public function setConnectionString($value)
+	{
+		$this->_connectionString=$value;
+	}
+
+	/**
+	 * @return string the username for establishing DB connection. Defaults to empty string.
+	 */
+	public function getUsername()
+	{
+		return $this->_username;
+	}
+
+	/**
+	 * @param string the username for establishing DB connection
+	 */
+	public function setUsername($value)
+	{
+		$this->_username=$value;
+	}
+
+	/**
+	 * @return string the password for establishing DB connection. Defaults to empty string.
+	 */
+	public function getPassword()
+	{
+		return $this->_password;
+	}
+
+	/**
+	 * @param string the password for establishing DB connection
+	 */
+	public function setPassword($value)
+	{
+		$this->_password=$value;
+	}
+
+	/**
+	 * @return string the name of the DB table to store cache content. Defaults to 'pradocache'.
+	 * @see setAutoCreateCacheTable
+	 */
+	public function getCacheTableName()
+	{
+		return $this->_cacheTable;
+	}
+
+	/**
+	 * Sets the name of the DB table to store cache content.
+	 * Note, if {@link setAutoCreateCacheTable AutoCreateCacheTable} is false
+	 * and you want to create the DB table manually by yourself,
+	 * you need to make sure the DB table is of the following structure:
+	 * <code>
+	 * CREATE TABLE pradocache (itemkey CHAR(128), value BLOB, expire INT)
+	 * CREATE INDEX IX_itemkey ON pradocache (itemkey)
+	 * CREATE INDEX IX_expire ON pradocache (expire)
+	 * </code>
+	 *
+	 * Note, some DBMS might not support BLOB type. In this case, replace 'BLOB' with a suitable
+	 * binary data type (e.g. LONGBLOB in MySQL, BYTEA in PostgreSQL.)
+	 *
+	 * Important: Make sure that the indices are non-unique!
+	 *
+	 * @param string the name of the DB table to store cache content
+	 * @see setAutoCreateCacheTable
+	 */
+	public function setCacheTableName($value)
+	{
+		$this->_cacheTable=$value;
+	}
+
+	/**
+	 * @return boolean whether the cache DB table should be automatically created if not exists. Defaults to true.
+	 * @see setAutoCreateCacheTable
+	 */
+	public function getAutoCreateCacheTable()
+	{
+		return $this->_autoCreate;
+	}
+
+	/**
+	 * @param boolean whether the cache DB table should be automatically created if not exists.
+	 * @see setCacheTableName
+	 */
+	public function setAutoCreateCacheTable($value)
+	{
+		$this->_autoCreate=TPropertyValue::ensureBoolean($value);
+	}
+
+	/**
+	 * Retrieves a value from cache with a specified key.
+	 * This is the implementation of the method declared in the parent class.
+	 * @param string a unique key identifying the cached value
+	 * @return string the value stored in cache, false if the value is not in the cache or expired.
+	 */
+	protected function getValue($key)
+	{
+		if(!$this->_cacheInitialized) $this->initializeCache();
+		try {
+			$sql='SELECT value FROM '.$this->_cacheTable.' WHERE itemkey=\''.$key.'\' AND (expire=0 OR expire>'.time().') ORDER BY expire DESC';
+			$command=$this->getDbConnection()->createCommand($sql);
+			return Prado::unserialize($command->queryScalar());
+		}
+		catch(Exception $e)
+		{
+			$this->initializeCache(true);
+			return Prado::unserialize($command->queryScalar());
+		}
+	}
+
+	/**
+	 * Stores a value identified by a key in cache.
+	 * This is the implementation of the method declared in the parent class.
+	 *
+	 * @param string the key identifying the value to be cached
+	 * @param string the value to be cached
+	 * @param integer the number of seconds in which the cached value will expire. 0 means never expire.
+	 * @return boolean true if the value is successfully stored into cache, false otherwise
+	 */
+	protected function setValue($key,$value,$expire)
+	{
+		$this->deleteValue($key);
+		return $this->addValue($key,$value,$expire);
+	}
+
+	/**
+	 * Stores a value identified by a key into cache if the cache does not contain this key.
+	 * This is the implementation of the method declared in the parent class.
+	 *
+	 * @param string the key identifying the value to be cached
+	 * @param string the value to be cached
+	 * @param integer the number of seconds in which the cached value will expire. 0 means never expire.
+	 * @return boolean true if the value is successfully stored into cache, false otherwise
+	 */
+	protected function addValue($key,$value,$expire)
+	{
+		if(!$this->_cacheInitialized) $this->initializeCache();
+		$expire=($expire<=0)?0:time()+$expire;
+		$sql="INSERT INTO {$this->_cacheTable} (itemkey,value,expire) VALUES(:key,:value,$expire)";
+		try
+		{
+			$command=$this->getDbConnection()->createCommand($sql);
+			$command->bindValue(':key',$key,PDO::PARAM_STR);
+			$command->bindValue(':value',Prado::serialize($value),PDO::PARAM_LOB);
+			$command->execute();
+			return true;
+		}
+		catch(Exception $e)
+		{
+			try
+			{
+				$this->initializeCache(true);
+				$command->execute();
+				return true;
+			}
+			catch(Exception $e)
+			{
+				return false;
+			}
+		}
+	}
+
+	/**
+	 * Deletes a value with the specified key from cache
+	 * This is the implementation of the method declared in the parent class.
+	 * @param string the key of the value to be deleted
+	 * @return boolean if no error happens during deletion
+	 */
+	protected function deleteValue($key)
+	{
+		if(!$this->_cacheInitialized) $this->initializeCache();
+		try
+		{
+			$command=$this->getDbConnection()->createCommand("DELETE FROM {$this->_cacheTable} WHERE itemkey=:key");
+			$command->bindValue(':key',$key,PDO::PARAM_STR);
+			$command->execute();
+			return true;
+		}
+		catch(Exception $e)
+		{
+			$this->initializeCache(true);
+			$command->execute();
+			return true;
+		}
+	}
+
+	/**
+	 * Deletes all values from cache.
+	 * Be careful of performing this operation if the cache is shared by multiple applications.
+	 */
+	public function flush()
+	{
+		if(!$this->_cacheInitialized) $this->initializeCache();
+		try
+		{
+			$command = $this->getDbConnection()->createCommand("DELETE FROM {$this->_cacheTable}");
+			$command->execute();
+		}
+		catch(Exception $e)
+		{
+			try
+			{
+				$this->initializeCache(true);
+				$command->execute();
+				return true;
+			}
+			catch(Exception $e)
+			{
+				return false;
+			}
+		}
+		return true;
+	}
+}