yii-framework 1.1.10 hinzugefügtHEADmaster

17 files changed, 2405 insertions, 0 deletions

diff --git a/framework/caching/CApcCache.php b/framework/caching/CApcCache.php
new file mode 100644
index 0000000..f098356
--- /dev/null
+++ b/framework/caching/CApcCache.php
@@ -0,0 +1,109 @@
+<?php
+/**
+ * CApcCache class file
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright &copy; 2008-2011 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+/**
+ * CApcCache provides APC caching in terms of an application component.
+ *
+ * The caching is based on {@link http://www.php.net/apc APC}.
+ * To use this application component, the APC PHP extension must be loaded.
+ *
+ * See {@link CCache} manual for common cache operations that are supported by CApcCache.
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @version $Id: CApcCache.php 3515 2011-12-28 12:29:24Z mdomba $
+ * @package system.caching
+ * @since 1.0
+ */
+class CApcCache extends CCache
+{
+	/**
+	 * Initializes this application component.
+	 * This method is required by the {@link IApplicationComponent} interface.
+	 * It checks the availability of memcache.
+	 * @throws CException if APC cache extension is not loaded or is disabled.
+	 */
+	public function init()
+	{
+		parent::init();
+		if(!extension_loaded('apc'))
+			throw new CException(Yii::t('yii','CApcCache requires PHP apc extension to be loaded.'));
+	}
+
+	/**
+	 * Retrieves a value from cache with a specified key.
+	 * This is the implementation of the method declared in the parent class.
+	 * @param string $key a unique key identifying the cached value
+	 * @return string the value stored in cache, false if the value is not in the cache or expired.
+	 */
+	protected function getValue($key)
+	{
+		return apc_fetch($key);
+	}
+
+	/**
+	 * Retrieves multiple values from cache with the specified keys.
+	 * @param array $keys a list of keys identifying the cached values
+	 * @return array a list of cached values indexed by the keys
+	 */
+	protected function getValues($keys)
+	{
+		return apc_fetch($keys);
+	}
+
+	/**
+	 * Stores a value identified by a key in cache.
+	 * This is the implementation of the method declared in the parent class.
+	 *
+	 * @param string $key the key identifying the value to be cached
+	 * @param string $value the value to be cached
+	 * @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire.
+	 * @return boolean true if the value is successfully stored into cache, false otherwise
+	 */
+	protected function setValue($key,$value,$expire)
+	{
+		return apc_store($key,$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 $key the key identifying the value to be cached
+	 * @param string $value the value to be cached
+	 * @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire.
+	 * @return boolean true if the value is successfully stored into cache, false otherwise
+	 */
+	protected function addValue($key,$value,$expire)
+	{
+		return apc_add($key,$value,$expire);
+	}
+
+	/**
+	 * Deletes a value with the specified key from cache
+	 * This is the implementation of the method declared in the parent class.
+	 * @param string $key the key of the value to be deleted
+	 * @return boolean if no error happens during deletion
+	 */
+	protected function deleteValue($key)
+	{
+		return apc_delete($key);
+	}
+
+	/**
+	 * Deletes all values from cache.
+	 * This is the implementation of the method declared in the parent class.
+	 * @return boolean whether the flush operation was successful.
+	 * @since 1.1.5
+	 */
+	protected function flushValues()
+	{
+		return apc_clear_cache('user');
+	}
+}
diff --git a/framework/caching/CCache.php b/framework/caching/CCache.php
new file mode 100644
index 0000000..0d66d4b
--- /dev/null
+++ b/framework/caching/CCache.php
@@ -0,0 +1,332 @@
+<?php
+/**
+ * CCache class file.
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright &copy; 2008-2011 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+/**
+ * CCache is the base class for cache classes with different cache storage implementation.
+ *
+ * A data item can be stored in cache by calling {@link set} and be retrieved back
+ * later by {@link get}. In both operations, a key identifying the data item is required.
+ * An expiration time and/or a dependency can also be specified when calling {@link set}.
+ * If the data item expires or the dependency changes, calling {@link get} will not
+ * return back the data item.
+ *
+ * Note, by definition, cache does not ensure the existence of a value
+ * even if it does not expire. Cache is not meant to be a persistent storage.
+ *
+ * CCache implements the interface {@link ICache} with the following methods:
+ * <ul>
+ * <li>{@link get} : retrieve the value with a key (if any) from cache</li>
+ * <li>{@link set} : store the value with a key into cache</li>
+ * <li>{@link add} : store the value only if cache does not have this key</li>
+ * <li>{@link delete} : delete the value with the specified key from cache</li>
+ * <li>{@link flush} : delete all values from cache</li>
+ * </ul>
+ *
+ * Child classes must implement the following methods:
+ * <ul>
+ * <li>{@link getValue}</li>
+ * <li>{@link setValue}</li>
+ * <li>{@link addValue}</li>
+ * <li>{@link deleteValue}</li>
+ * <li>{@link flush} (optional)</li>
+ * </ul>
+ *
+ * CCache also implements ArrayAccess so that it can be used like an array.
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @version $Id: CCache.php 3515 2011-12-28 12:29:24Z mdomba $
+ * @package system.caching
+ * @since 1.0
+ */
+abstract class CCache extends CApplicationComponent implements ICache, ArrayAccess
+{
+	/**
+	 * @var string a string prefixed to every cache key so that it is unique. Defaults to {@link CApplication::getId() application ID}.
+	 */
+	public $keyPrefix;
+
+	/**
+	 * Initializes the application component.
+	 * This method overrides the parent implementation by setting default cache key prefix.
+	 */
+	public function init()
+	{
+		parent::init();
+		if($this->keyPrefix===null)
+			$this->keyPrefix=Yii::app()->getId();
+	}
+
+	/**
+	 * @param string $key a key identifying a value to be cached
+	 * @return sring a key generated from the provided key which ensures the uniqueness across applications
+	 */
+	protected function generateUniqueKey($key)
+	{
+		return md5($this->keyPrefix.$key);
+	}
+
+	/**
+	 * Retrieves a value from cache with a specified key.
+	 * @param string $id a key identifying the cached value
+	 * @return mixed the value stored in cache, false if the value is not in the cache, expired or the dependency has changed.
+	 */
+	public function get($id)
+	{
+		if(($value=$this->getValue($this->generateUniqueKey($id)))!==false)
+		{
+			$data=unserialize($value);
+			if(!is_array($data))
+				return false;
+			if(!($data[1] instanceof ICacheDependency) || !$data[1]->getHasChanged())
+			{
+				Yii::trace('Serving "'.$id.'" from cache','system.caching.'.get_class($this));
+				return $data[0];
+			}
+		}
+		return false;
+	}
+
+	/**
+	 * Retrieves multiple values from cache with the specified keys.
+	 * Some caches (such as memcache, apc) allow retrieving multiple cached values at one time,
+	 * which may improve the performance since it reduces the communication cost.
+	 * In case a cache doesn't support this feature natively, it will be simulated by this method.
+	 * @param array $ids list of keys identifying the cached values
+	 * @return array list of cached values corresponding to the specified keys. The array
+	 * is returned in terms of (key,value) pairs.
+	 * If a value is not cached or expired, the corresponding array value will be false.
+	 */
+	public function mget($ids)
+	{
+		$uniqueIDs=array();
+		$results=array();
+		foreach($ids as $id)
+		{
+			$uniqueIDs[$id]=$this->generateUniqueKey($id);
+			$results[$id]=false;
+		}
+		$values=$this->getValues($uniqueIDs);
+		foreach($uniqueIDs as $id=>$uniqueID)
+		{
+			if(!isset($values[$uniqueID]))
+				continue;
+			$data=unserialize($values[$uniqueID]);
+			if(is_array($data) && (!($data[1] instanceof ICacheDependency) || !$data[1]->getHasChanged()))
+			{
+				Yii::trace('Serving "'.$id.'" from cache','system.caching.'.get_class($this));
+				$results[$id]=$data[0];
+			}
+		}
+		return $results;
+	}
+
+	/**
+	 * 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 $id the key identifying the value to be cached
+	 * @param mixed $value the value to be cached
+	 * @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire.
+	 * @param ICacheDependency $dependency dependency of the cached item. If the dependency changes, the item is labeled invalid.
+	 * @return boolean true if the value is successfully stored into cache, false otherwise
+	 */
+	public function set($id,$value,$expire=0,$dependency=null)
+	{
+		Yii::trace('Saving "'.$id.'" to cache','system.caching.'.get_class($this));
+		if($dependency!==null)
+			$dependency->evaluateDependency();
+		$data=array($value,$dependency);
+		return $this->setValue($this->generateUniqueKey($id),serialize($data),$expire);
+	}
+
+	/**
+	 * 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 $id the key identifying the value to be cached
+	 * @param mixed $value the value to be cached
+	 * @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire.
+	 * @param ICacheDependency $dependency dependency of the cached item. If the dependency changes, the item is labeled invalid.
+	 * @return boolean true if the value is successfully stored into cache, false otherwise
+	 */
+	public function add($id,$value,$expire=0,$dependency=null)
+	{
+		Yii::trace('Adding "'.$id.'" to cache','system.caching.'.get_class($this));
+		if($dependency!==null)
+			$dependency->evaluateDependency();
+		$data=array($value,$dependency);
+		return $this->addValue($this->generateUniqueKey($id),serialize($data),$expire);
+	}
+
+	/**
+	 * Deletes a value with the specified key from cache
+	 * @param string $id the key of the value to be deleted
+	 * @return boolean if no error happens during deletion
+	 */
+	public function delete($id)
+	{
+		Yii::trace('Deleting "'.$id.'" from cache','system.caching.'.get_class($this));
+		return $this->deleteValue($this->generateUniqueKey($id));
+	}
+
+	/**
+	 * Deletes all values from cache.
+	 * Be careful of performing this operation if the cache is shared by multiple applications.
+	 * @return boolean whether the flush operation was successful.
+	 */
+	public function flush()
+	{
+		Yii::trace('Flushing cache','system.caching.'.get_class($this));
+		return $this->flushValues();
+	}
+
+	/**
+	 * Retrieves a value from cache with a specified key.
+	 * This method should be implemented by child classes to retrieve the data
+	 * from specific cache storage. The uniqueness and dependency are handled
+	 * in {@link get()} already. So only the implementation of data retrieval
+	 * is needed.
+	 * @param string $key a unique key identifying the cached value
+	 * @return string the value stored in cache, false if the value is not in the cache or expired.
+	 * @throws CException if this method is not overridden by child classes
+	 */
+	protected function getValue($key)
+	{
+		throw new CException(Yii::t('yii','{className} does not support get() functionality.',
+			array('{className}'=>get_class($this))));
+	}
+
+	/**
+	 * Retrieves multiple values from cache with the specified keys.
+	 * The default implementation simply calls {@link getValue} multiple
+	 * times to retrieve the cached values one by one.
+	 * If the underlying cache storage supports multiget, this method should
+	 * be overridden to exploit that feature.
+	 * @param array $keys a list of keys identifying the cached values
+	 * @return array a list of cached values indexed by the keys
+	 */
+	protected function getValues($keys)
+	{
+		$results=array();
+		foreach($keys as $key)
+			$results[$key]=$this->getValue($key);
+		return $results;
+	}
+
+	/**
+	 * Stores a value identified by a key in cache.
+	 * This method should be implemented by child classes to store the data
+	 * in specific cache storage. The uniqueness and dependency are handled
+	 * in {@link set()} already. So only the implementation of data storage
+	 * is needed.
+	 *
+	 * @param string $key the key identifying the value to be cached
+	 * @param string $value the value to be cached
+	 * @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire.
+	 * @return boolean true if the value is successfully stored into cache, false otherwise
+	 * @throws CException if this method is not overridden by child classes
+	 */
+	protected function setValue($key,$value,$expire)
+	{
+		throw new CException(Yii::t('yii','{className} does not support set() functionality.',
+			array('{className}'=>get_class($this))));
+	}
+
+	/**
+	 * Stores a value identified by a key into cache if the cache does not contain this key.
+	 * This method should be implemented by child classes to store the data
+	 * in specific cache storage. The uniqueness and dependency are handled
+	 * in {@link add()} already. So only the implementation of data storage
+	 * is needed.
+	 *
+	 * @param string $key the key identifying the value to be cached
+	 * @param string $value the value to be cached
+	 * @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire.
+	 * @return boolean true if the value is successfully stored into cache, false otherwise
+	 * @throws CException if this method is not overridden by child classes
+	 */
+	protected function addValue($key,$value,$expire)
+	{
+		throw new CException(Yii::t('yii','{className} does not support add() functionality.',
+			array('{className}'=>get_class($this))));
+	}
+
+	/**
+	 * Deletes a value with the specified key from cache
+	 * This method should be implemented by child classes to delete the data from actual cache storage.
+	 * @param string $key the key of the value to be deleted
+	 * @return boolean if no error happens during deletion
+	 * @throws CException if this method is not overridden by child classes
+	 */
+	protected function deleteValue($key)
+	{
+		throw new CException(Yii::t('yii','{className} does not support delete() functionality.',
+			array('{className}'=>get_class($this))));
+	}
+
+	/**
+	 * Deletes all values from cache.
+	 * Child classes may implement this method to realize the flush operation.
+	 * @return boolean whether the flush operation was successful.
+	 * @throws CException if this method is not overridden by child classes
+	 * @since 1.1.5
+	 */
+	protected function flushValues()
+	{
+		throw new CException(Yii::t('yii','{className} does not support flushValues() functionality.',
+			array('{className}'=>get_class($this))));
+	}
+
+	/**
+	 * Returns whether there is a cache entry with a specified key.
+	 * This method is required by the interface ArrayAccess.
+	 * @param string $id a key identifying the cached value
+	 * @return boolean
+	 */
+	public function offsetExists($id)
+	{
+		return $this->get($id)!==false;
+	}
+
+	/**
+	 * Retrieves the value from cache with a specified key.
+	 * This method is required by the interface ArrayAccess.
+	 * @param string $id a key identifying the cached value
+	 * @return mixed the value stored in cache, false if the value is not in the cache or expired.
+	 */
+	public function offsetGet($id)
+	{
+		return $this->get($id);
+	}
+
+	/**
+	 * Stores the value identified by a key into cache.
+	 * If the cache already contains such a key, the existing value will be
+	 * replaced with the new ones. To add expiration and dependencies, use the set() method.
+	 * This method is required by the interface ArrayAccess.
+	 * @param string $id the key identifying the value to be cached
+	 * @param mixed $value the value to be cached
+	 */
+	public function offsetSet($id, $value)
+	{
+		$this->set($id, $value);
+	}
+
+	/**
+	 * Deletes the value with the specified key from cache
+	 * This method is required by the interface ArrayAccess.
+	 * @param string $id the key of the value to be deleted
+	 * @return boolean if no error happens during deletion
+	 */
+	public function offsetUnset($id)
+	{
+		$this->delete($id);
+	}
+}
\ No newline at end of file
diff --git a/framework/caching/CDbCache.php b/framework/caching/CDbCache.php
new file mode 100644
index 0000000..90e5009
--- /dev/null
+++ b/framework/caching/CDbCache.php
@@ -0,0 +1,314 @@
+<?php
+/**
+ * CDbCache class file
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright &copy; 2008-2011 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+/**
+ * CDbCache implements a cache application component by storing cached data in a database.
+ *
+ * CDbCache stores cache data in a DB table named {@link cacheTableName}.
+ * If the table does not exist, it will be automatically created.
+ * By setting {@link autoCreateCacheTable} to false, you can also manually create the DB table.
+ *
+ * CDbCache relies on {@link http://www.php.net/manual/en/ref.pdo.php PDO} to access database.
+ * By default, it will use a SQLite3 database under the application runtime directory.
+ * You can also specify {@link connectionID} so that it makes use of
+ * a DB application component to access database.
+ *
+ * See {@link CCache} manual for common cache operations that are supported by CDbCache.
+ *
+ * @property integer $gCProbability The probability (parts per million) that garbage collection (GC) should be performed
+ * when storing a piece of data in the cache. Defaults to 100, meaning 0.01% chance.
+ * @property CDbConnection $dbConnection The DB connection instance.
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @version $Id: CDbCache.php 3515 2011-12-28 12:29:24Z mdomba $
+ * @package system.caching
+ * @since 1.0
+ */
+class CDbCache extends CCache
+{
+	/**
+	 * @var string the ID of the {@link CDbConnection} application component. If not set,
+	 * a SQLite3 database will be automatically created and used. The SQLite database file
+	 * is <code>protected/runtime/cache-YiiVersion.db</code>.
+	 */
+	public $connectionID;
+	/**
+	 * @var string name of the DB table to store cache content. Defaults to 'YiiCache'.
+	 * Note, if {@link 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:
+	 * <pre>
+	 * (id CHAR(128) PRIMARY KEY, expire INTEGER, value BLOB)
+	 * </pre>
+	 * 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.)
+	 * @see autoCreateCacheTable
+	 */
+	public $cacheTableName='YiiCache';
+	/**
+	 * @var boolean whether the cache DB table should be created automatically if it does not exist. Defaults to true.
+	 * If you already have the table created, it is recommended you set this property to be false to improve performance.
+	 * @see cacheTableName
+	 */
+	public $autoCreateCacheTable=true;
+	/**
+	 * @var CDbConnection the DB connection instance
+	 */
+	private $_db;
+	private $_gcProbability=100;
+	private $_gced=false;
+
+	/**
+	 * Initializes this application component.
+	 *
+	 * This method is required by the {@link IApplicationComponent} interface.
+	 * It ensures the existence of the cache DB table.
+	 * It also removes expired data items from the cache.
+	 */
+	public function init()
+	{
+		parent::init();
+
+		$db=$this->getDbConnection();
+		$db->setActive(true);
+		if($this->autoCreateCacheTable)
+		{
+			$sql="DELETE FROM {$this->cacheTableName} WHERE expire>0 AND expire<".time();
+			try
+			{
+				$db->createCommand($sql)->execute();
+			}
+			catch(Exception $e)
+			{
+				$this->createCacheTable($db,$this->cacheTableName);
+			}
+		}
+	}
+
+	/**
+	 * @return integer the probability (parts per million) that garbage collection (GC) should be performed
+	 * when storing a piece of data in the cache. Defaults to 100, meaning 0.01% chance.
+	 */
+	public function getGCProbability()
+	{
+		return $this->_gcProbability;
+	}
+
+	/**
+	 * @param integer $value the probability (parts per million) that garbage collection (GC) should be performed
+	 * when storing a piece of data in the cache. Defaults to 100, meaning 0.01% chance.
+	 * This number should be between 0 and 1000000. A value 0 meaning no GC will be performed at all.
+	 */
+	public function setGCProbability($value)
+	{
+		$value=(int)$value;
+		if($value<0)
+			$value=0;
+		if($value>1000000)
+			$value=1000000;
+		$this->_gcProbability=$value;
+	}
+
+	/**
+	 * Creates the cache DB table.
+	 * @param CDbConnection $db the database connection
+	 * @param string $tableName the name of the table to be created
+	 */
+	protected function createCacheTable($db,$tableName)
+	{
+		$driver=$db->getDriverName();
+		if($driver==='mysql')
+			$blob='LONGBLOB';
+		else if($driver==='pgsql')
+			$blob='BYTEA';
+		else
+			$blob='BLOB';
+		$sql=<<<EOD
+CREATE TABLE $tableName
+(
+	id CHAR(128) PRIMARY KEY,
+	expire INTEGER,
+	value $blob
+)
+EOD;
+		$db->createCommand($sql)->execute();
+	}
+
+	/**
+	 * @return CDbConnection the DB connection instance
+	 * @throws CException if {@link connectionID} does not point to a valid application component.
+	 */
+	public function getDbConnection()
+	{
+		if($this->_db!==null)
+			return $this->_db;
+		else if(($id=$this->connectionID)!==null)
+		{
+			if(($this->_db=Yii::app()->getComponent($id)) instanceof CDbConnection)
+				return $this->_db;
+			else
+				throw new CException(Yii::t('yii','CDbCache.connectionID "{id}" is invalid. Please make sure it refers to the ID of a CDbConnection application component.',
+					array('{id}'=>$id)));
+		}
+		else
+		{
+			$dbFile=Yii::app()->getRuntimePath().DIRECTORY_SEPARATOR.'cache-'.Yii::getVersion().'.db';
+			return $this->_db=new CDbConnection('sqlite:'.$dbFile);
+		}
+	}
+
+	/**
+	 * Sets the DB connection used by the cache component.
+	 * @param CDbConnection $value the DB connection instance
+	 * @since 1.1.5
+	 */
+	public function setDbConnection($value)
+	{
+		$this->_db=$value;
+	}
+
+	/**
+	 * Retrieves a value from cache with a specified key.
+	 * This is the implementation of the method declared in the parent class.
+	 * @param string $key a unique key identifying the cached value
+	 * @return string the value stored in cache, false if the value is not in the cache or expired.
+	 */
+	protected function getValue($key)
+	{
+		$time=time();
+		$sql="SELECT value FROM {$this->cacheTableName} WHERE id='$key' AND (expire=0 OR expire>$time)";
+		$db=$this->getDbConnection();
+		if($db->queryCachingDuration>0)
+		{
+			$duration=$db->queryCachingDuration;
+			$db->queryCachingDuration=0;
+			$result=$db->createCommand($sql)->queryScalar();
+			$db->queryCachingDuration=$duration;
+			return $result;
+		}
+		else
+			return $db->createCommand($sql)->queryScalar();
+	}
+
+	/**
+	 * Retrieves multiple values from cache with the specified keys.
+	 * @param array $keys a list of keys identifying the cached values
+	 * @return array a list of cached values indexed by the keys
+	 */
+	protected function getValues($keys)
+	{
+		if(empty($keys))
+			return array();
+
+		$ids=implode("','",$keys);
+		$time=time();
+		$sql="SELECT id, value FROM {$this->cacheTableName} WHERE id IN ('$ids') AND (expire=0 OR expire>$time)";
+
+		$db=$this->getDbConnection();
+		if($db->queryCachingDuration>0)
+		{
+			$duration=$db->queryCachingDuration;
+			$db->queryCachingDuration=0;
+			$rows=$db->createCommand($sql)->queryAll();
+			$db->queryCachingDuration=$duration;
+		}
+		else
+			$rows=$db->createCommand($sql)->queryAll();
+
+		$results=array();
+		foreach($keys as $key)
+			$results[$key]=false;
+		foreach($rows as $row)
+			$results[$row['id']]=$results[$row['value']];
+		return $results;
+	}
+
+	/**
+	 * Stores a value identified by a key in cache.
+	 * This is the implementation of the method declared in the parent class.
+	 *
+	 * @param string $key the key identifying the value to be cached
+	 * @param string $value the value to be cached
+	 * @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire.
+	 * @return boolean true if the value is successfully stored into cache, false otherwise
+	 */
+	protected function setValue($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 $key the key identifying the value to be cached
+	 * @param string $value the value to be cached
+	 * @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire.
+	 * @return boolean true if the value is successfully stored into cache, false otherwise
+	 */
+	protected function addValue($key,$value,$expire)
+	{
+		if(!$this->_gced && mt_rand(0,1000000)<$this->_gcProbability)
+		{
+			$this->gc();
+			$this->_gced=true;
+		}
+
+		if($expire>0)
+			$expire+=time();
+		else
+			$expire=0;
+		$sql="INSERT INTO {$this->cacheTableName} (id,expire,value) VALUES ('$key',$expire,:value)";
+		try
+		{
+			$command=$this->getDbConnection()->createCommand($sql);
+			$command->bindValue(':value',$value,PDO::PARAM_LOB);
+			$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 $key the key of the value to be deleted
+	 * @return boolean if no error happens during deletion
+	 */
+	protected function deleteValue($key)
+	{
+		$sql="DELETE FROM {$this->cacheTableName} WHERE id='$key'";
+		$this->getDbConnection()->createCommand($sql)->execute();
+		return true;
+	}
+
+	/**
+	 * Removes the expired data values.
+	 */
+	protected function gc()
+	{
+		$this->getDbConnection()->createCommand("DELETE FROM {$this->cacheTableName} WHERE expire>0 AND expire<".time())->execute();
+	}
+
+	/**
+	 * Deletes all values from cache.
+	 * This is the implementation of the method declared in the parent class.
+	 * @return boolean whether the flush operation was successful.
+	 * @since 1.1.5
+	 */
+	protected function flushValues()
+	{
+		$this->getDbConnection()->createCommand("DELETE FROM {$this->cacheTableName}")->execute();
+		return true;
+	}
+}
diff --git a/framework/caching/CDummyCache.php b/framework/caching/CDummyCache.php
new file mode 100644
index 0000000..52bf553
--- /dev/null
+++ b/framework/caching/CDummyCache.php
@@ -0,0 +1,164 @@
+<?php
+/**
+ * CDummyCache class file.
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright &copy; 2008-2011 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+/**
+ * CDummyCache is a placeholder cache component.
+ *
+ * CDummyCache does not cache anything. It is provided so that one can always configure
+ * a 'cache' application component and he does not need to check if Yii::app()->cache is null or not.
+ * By replacing CDummyCache with some other cache component, one can quickly switch from
+ * non-caching mode to caching mode.
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @version $Id: CDummyCache.php 3515 2011-12-28 12:29:24Z mdomba $
+ * @package system.caching
+ * @since 1.0
+ */
+class CDummyCache extends CApplicationComponent implements ICache, ArrayAccess
+{
+	/**
+	 * @var string a string prefixed to every cache key so that it is unique. Defaults to {@link CApplication::getId() application ID}.
+	 */
+	public $keyPrefix;
+
+	/**
+	 * Initializes the application component.
+	 * This method overrides the parent implementation by setting default cache key prefix.
+	 */
+	public function init()
+	{
+		parent::init();
+		if($this->keyPrefix===null)
+			$this->keyPrefix=Yii::app()->getId();
+	}
+
+	/**
+	 * Retrieves a value from cache with a specified key.
+	 * @param string $id a key identifying the cached value
+	 * @return mixed the value stored in cache, false if the value is not in the cache, expired or the dependency has changed.
+	 */
+	public function get($id)
+	{
+		return false;
+	}
+
+	/**
+	 * Retrieves multiple values from cache with the specified keys.
+	 * Some caches (such as memcache, apc) allow retrieving multiple cached values at one time,
+	 * which may improve the performance since it reduces the communication cost.
+	 * In case a cache doesn't support this feature natively, it will be simulated by this method.
+	 * @param array $ids list of keys identifying the cached values
+	 * @return array list of cached values corresponding to the specified keys. The array
+	 * is returned in terms of (key,value) pairs.
+	 * If a value is not cached or expired, the corresponding array value will be false.
+	 */
+	public function mget($ids)
+	{
+		$results=array();
+		foreach($ids as $id)
+			$results[$id]=false;
+		return $results;
+	}
+
+	/**
+	 * 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 $id the key identifying the value to be cached
+	 * @param mixed $value the value to be cached
+	 * @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire.
+	 * @param ICacheDependency $dependency dependency of the cached item. If the dependency changes, the item is labeled invalid.
+	 * @return boolean true if the value is successfully stored into cache, false otherwise
+	 */
+	public function set($id,$value,$expire=0,$dependency=null)
+	{
+		return true;
+	}
+
+	/**
+	 * 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 $id the key identifying the value to be cached
+	 * @param mixed $value the value to be cached
+	 * @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire.
+	 * @param ICacheDependency $dependency dependency of the cached item. If the dependency changes, the item is labeled invalid.
+	 * @return boolean true if the value is successfully stored into cache, false otherwise
+	 */
+	public function add($id,$value,$expire=0,$dependency=null)
+	{
+		return true;
+	}
+
+	/**
+	 * Deletes a value with the specified key from cache
+	 * @param string $id the key of the value to be deleted
+	 * @return boolean if no error happens during deletion
+	 */
+	public function delete($id)
+	{
+		return true;
+	}
+
+	/**
+	 * Deletes all values from cache.
+	 * Be careful of performing this operation if the cache is shared by multiple applications.
+	 * @return boolean whether the flush operation was successful.
+	 * @throws CException if this method is not overridden by child classes
+	 */
+	public function flush()
+	{
+		return true;
+	}
+
+	/**
+	 * Returns whether there is a cache entry with a specified key.
+	 * This method is required by the interface ArrayAccess.
+	 * @param string $id a key identifying the cached value
+	 * @return boolean
+	 */
+	public function offsetExists($id)
+	{
+		return false;
+	}
+
+	/**
+	 * Retrieves the value from cache with a specified key.
+	 * This method is required by the interface ArrayAccess.
+	 * @param string $id a key identifying the cached value
+	 * @return mixed the value stored in cache, false if the value is not in the cache or expired.
+	 */
+	public function offsetGet($id)
+	{
+		return false;
+	}
+
+	/**
+	 * Stores the value identified by a key into cache.
+	 * If the cache already contains such a key, the existing value will be
+	 * replaced with the new ones. To add expiration and dependencies, use the set() method.
+	 * This method is required by the interface ArrayAccess.
+	 * @param string $id the key identifying the value to be cached
+	 * @param mixed $value the value to be cached
+	 */
+	public function offsetSet($id, $value)
+	{
+	}
+
+	/**
+	 * Deletes the value with the specified key from cache
+	 * This method is required by the interface ArrayAccess.
+	 * @param string $id the key of the value to be deleted
+	 * @return boolean if no error happens during deletion
+	 */
+	public function offsetUnset($id)
+	{
+	}
+}
diff --git a/framework/caching/CEAcceleratorCache.php b/framework/caching/CEAcceleratorCache.php
new file mode 100644
index 0000000..d02545d
--- /dev/null
+++ b/framework/caching/CEAcceleratorCache.php
@@ -0,0 +1,107 @@
+<?php
+/**
+ * CEAcceleratorCache class file
+ *
+ * @author Steffen Dietz <steffo.dietz[at]googlemail[dot]com>
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright &copy; 2008-2011 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+/**
+ * CEAcceleratorCache implements a cache application module based on {@link http://eaccelerator.net/ eaccelerator}.
+ *
+ * To use this application component, the eAccelerator PHP extension must be loaded.
+ *
+ * See {@link CCache} manual for common cache operations that are supported by CEAccelerator.
+ *
+ * Please note that as of v0.9.6, eAccelerator no longer supports data caching.
+ * This means if you still want to use this component, your eAccelerator should be of 0.9.5.x or lower version.
+ *
+ * @author Steffen Dietz <steffo.dietz[at]googlemail[dot]com>
+ * @version $Id: CEAcceleratorCache.php 3515 2011-12-28 12:29:24Z mdomba $
+ * @package system.caching
+ */
+class CEAcceleratorCache extends CCache
+{
+	/**
+	 * Initializes this application component.
+	 * This method is required by the {@link IApplicationComponent} interface.
+	 * It checks the availability of eAccelerator.
+	 * @throws CException if eAccelerator extension is not loaded, is disabled or the cache functions are not compiled in.
+	 */
+	public function init()
+	{
+		parent::init();
+		if(!function_exists('eaccelerator_get'))
+			throw new CException(Yii::t('yii','CEAcceleratorCache requires PHP eAccelerator extension to be loaded, enabled or compiled with the "--with-eaccelerator-shared-memory" option.'));
+	}
+
+	/**
+	 * Retrieves a value from cache with a specified key.
+	 * This is the implementation of the method declared in the parent class.
+	 * @param string $key a unique key identifying the cached value
+	 * @return string the value stored in cache, false if the value is not in the cache or expired.
+	 */
+	protected function getValue($key)
+	{
+		$result = eaccelerator_get($key);
+		return $result !== NULL ? $result : false;
+	}
+
+	/**
+	 * Stores a value identified by a key in cache.
+	 * This is the implementation of the method declared in the parent class.
+	 *
+	 * @param string $key the key identifying the value to be cached
+	 * @param string $value the value to be cached
+	 * @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire.
+	 * @return boolean true if the value is successfully stored into cache, false otherwise
+	 */
+	protected function setValue($key,$value,$expire)
+	{
+		return eaccelerator_put($key,$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 $key the key identifying the value to be cached
+	 * @param string $value the value to be cached
+	 * @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire.
+	 * @return boolean true if the value is successfully stored into cache, false otherwise
+	 */
+	protected function addValue($key,$value,$expire)
+	{
+		return (NULL === eaccelerator_get($key)) ? $this->setValue($key,$value,$expire) : false;
+	}
+
+	/**
+	 * Deletes a value with the specified key from cache
+	 * This is the implementation of the method declared in the parent class.
+	 * @param string $key the key of the value to be deleted
+	 * @return boolean if no error happens during deletion
+	 */
+	protected function deleteValue($key)
+	{
+		return eaccelerator_rm($key);
+	}
+
+	/**
+	 * Deletes all values from cache.
+	 * This is the implementation of the method declared in the parent class.
+	 * @return boolean whether the flush operation was successful.
+	 * @since 1.1.5
+	 */
+	protected function flushValues()
+	{
+		// first, remove expired content from cache
+		eaccelerator_gc();
+		// now, remove leftover cache-keys
+		$keys = eaccelerator_list_keys();
+		foreach($keys as $key)
+			$this->deleteValue(substr($key['name'], 1));
+		return true;
+	}
+}
diff --git a/framework/caching/CFileCache.php b/framework/caching/CFileCache.php
new file mode 100644
index 0000000..a339699
--- /dev/null
+++ b/framework/caching/CFileCache.php
@@ -0,0 +1,222 @@
+<?php
+/**
+ * CFileCache class file
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright &copy; 2008-2011 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+/**
+ * CFileCache provides a file-based caching mechanism.
+ *
+ * For each data value being cached, CFileCache will use store it in a separate file
+ * under {@link cachePath} which defaults to 'protected/runtime/cache'.
+ * CFileCache will perform garbage collection automatically to remove expired cache files.
+ *
+ * See {@link CCache} manual for common cache operations that are supported by CFileCache.
+ *
+ * @property integer $gCProbability The probability (parts per million) that garbage collection (GC) should be performed
+ * when storing a piece of data in the cache. Defaults to 100, meaning 0.01% chance.
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @version $Id: CFileCache.php 3515 2011-12-28 12:29:24Z mdomba $
+ * @package system.caching
+ */
+class CFileCache extends CCache
+{
+	/**
+	 * @var string the directory to store cache files. Defaults to null, meaning
+	 * using 'protected/runtime/cache' as the directory.
+	 */
+	public $cachePath;
+	/**
+	 * @var string cache file suffix. Defaults to '.bin'.
+	 */
+	public $cacheFileSuffix='.bin';
+	/**
+	 * @var integer the level of sub-directories to store cache files. Defaults to 0,
+	 * meaning no sub-directories. If the system has huge number of cache files (e.g. 10K+),
+	 * you may want to set this value to be 1 or 2 so that the file system is not over burdened.
+	 * The value of this property should not exceed 16 (less than 3 is recommended).
+	 */
+	public $directoryLevel=0;
+
+	private $_gcProbability=100;
+	private $_gced=false;
+
+	/**
+	 * Initializes this application component.
+	 * This method is required by the {@link IApplicationComponent} interface.
+	 * It checks the availability of memcache.
+	 * @throws CException if APC cache extension is not loaded or is disabled.
+	 */
+	public function init()
+	{
+		parent::init();
+		if($this->cachePath===null)
+			$this->cachePath=Yii::app()->getRuntimePath().DIRECTORY_SEPARATOR.'cache';
+		if(!is_dir($this->cachePath))
+			mkdir($this->cachePath,0777,true);
+	}
+
+	/**
+	 * @return integer the probability (parts per million) that garbage collection (GC) should be performed
+	 * when storing a piece of data in the cache. Defaults to 100, meaning 0.01% chance.
+	 */
+	public function getGCProbability()
+	{
+		return $this->_gcProbability;
+	}
+
+	/**
+	 * @param integer $value the probability (parts per million) that garbage collection (GC) should be performed
+	 * when storing a piece of data in the cache. Defaults to 100, meaning 0.01% chance.
+	 * This number should be between 0 and 1000000. A value 0 meaning no GC will be performed at all.
+	 */
+	public function setGCProbability($value)
+	{
+		$value=(int)$value;
+		if($value<0)
+			$value=0;
+		if($value>1000000)
+			$value=1000000;
+		$this->_gcProbability=$value;
+	}
+
+	/**
+	 * Deletes all values from cache.
+	 * This is the implementation of the method declared in the parent class.
+	 * @return boolean whether the flush operation was successful.
+	 * @since 1.1.5
+	 */
+	protected function flushValues()
+	{
+		$this->gc(false);
+		return true;
+	}
+
+	/**
+	 * Retrieves a value from cache with a specified key.
+	 * This is the implementation of the method declared in the parent class.
+	 * @param string $key a unique key identifying the cached value
+	 * @return string the value stored in cache, false if the value is not in the cache or expired.
+	 */
+	protected function getValue($key)
+	{
+		$cacheFile=$this->getCacheFile($key);
+		if(($time=@filemtime($cacheFile))>time())
+			return @file_get_contents($cacheFile);
+		else if($time>0)
+			@unlink($cacheFile);
+		return false;
+	}
+
+	/**
+	 * Stores a value identified by a key in cache.
+	 * This is the implementation of the method declared in the parent class.
+	 *
+	 * @param string $key the key identifying the value to be cached
+	 * @param string $value the value to be cached
+	 * @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire.
+	 * @return boolean true if the value is successfully stored into cache, false otherwise
+	 */
+	protected function setValue($key,$value,$expire)
+	{
+		if(!$this->_gced && mt_rand(0,1000000)<$this->_gcProbability)
+		{
+			$this->gc();
+			$this->_gced=true;
+		}
+
+		if($expire<=0)
+			$expire=31536000; // 1 year
+		$expire+=time();
+
+		$cacheFile=$this->getCacheFile($key);
+		if($this->directoryLevel>0)
+			@mkdir(dirname($cacheFile),0777,true);
+		if(@file_put_contents($cacheFile,$value,LOCK_EX)!==false)
+		{
+			@chmod($cacheFile,0777);
+			return @touch($cacheFile,$expire);
+		}
+		else
+			return false;
+	}
+
+	/**
+	 * 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 $key the key identifying the value to be cached
+	 * @param string $value the value to be cached
+	 * @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire.
+	 * @return boolean true if the value is successfully stored into cache, false otherwise
+	 */
+	protected function addValue($key,$value,$expire)
+	{
+		$cacheFile=$this->getCacheFile($key);
+		if(@filemtime($cacheFile)>time())
+			return false;
+		return $this->setValue($key,$value,$expire);
+	}
+
+	/**
+	 * Deletes a value with the specified key from cache
+	 * This is the implementation of the method declared in the parent class.
+	 * @param string $key the key of the value to be deleted
+	 * @return boolean if no error happens during deletion
+	 */
+	protected function deleteValue($key)
+	{
+		$cacheFile=$this->getCacheFile($key);
+		return @unlink($cacheFile);
+	}
+
+	/**
+	 * Returns the cache file path given the cache key.
+	 * @param string $key cache key
+	 * @return string the cache file path
+	 */
+	protected function getCacheFile($key)
+	{
+		if($this->directoryLevel>0)
+		{
+			$base=$this->cachePath;
+			for($i=0;$i<$this->directoryLevel;++$i)
+			{
+				if(($prefix=substr($key,$i+$i,2))!==false)
+					$base.=DIRECTORY_SEPARATOR.$prefix;
+			}
+			return $base.DIRECTORY_SEPARATOR.$key.$this->cacheFileSuffix;
+		}
+		else
+			return $this->cachePath.DIRECTORY_SEPARATOR.$key.$this->cacheFileSuffix;
+	}
+
+	/**
+	 * Removes expired cache files.
+	 * @param boolean $expiredOnly whether to removed expired cache files only. If true, all cache files under {@link cachePath} will be removed.
+	 * @param string $path the path to clean with. If null, it will be {@link cachePath}.
+	 */
+	public function gc($expiredOnly=true,$path=null)
+	{
+		if($path===null)
+			$path=$this->cachePath;
+		if(($handle=opendir($path))===false)
+			return;
+		while(($file=readdir($handle))!==false)
+		{
+			if($file[0]==='.')
+				continue;
+			$fullPath=$path.DIRECTORY_SEPARATOR.$file;
+			if(is_dir($fullPath))
+				$this->gc($expiredOnly,$fullPath);
+			else if($expiredOnly && @filemtime($fullPath)<time() || !$expiredOnly)
+				@unlink($fullPath);
+		}
+		closedir($handle);
+	}
+}
diff --git a/framework/caching/CMemCache.php b/framework/caching/CMemCache.php
new file mode 100644
index 0000000..b18d939
--- /dev/null
+++ b/framework/caching/CMemCache.php
@@ -0,0 +1,276 @@
+<?php
+/**
+ * CMemCache class file
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright &copy; 2008-2011 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+/**
+ * CMemCache implements a cache application component based on {@link http://memcached.org/ memcached}.
+ *
+ * CMemCache can be configured with a list of memcache servers by settings
+ * its {@link setServers servers} property. By default, CMemCache assumes
+ * there is a memcache server running on localhost at port 11211.
+ *
+ * See {@link CCache} manual for common cache operations that are supported by CMemCache.
+ *
+ * Note, there is no security measure to protected data in memcache.
+ * All data in memcache can be accessed by any process running in the system.
+ *
+ * To use CMemCache as the cache application component, configure the application as follows,
+ * <pre>
+ * array(
+ *     'components'=>array(
+ *         'cache'=>array(
+ *             'class'=>'CMemCache',
+ *             'servers'=>array(
+ *                 array(
+ *                     'host'=>'server1',
+ *                     'port'=>11211,
+ *                     'weight'=>60,
+ *                 ),
+ *                 array(
+ *                     'host'=>'server2',
+ *                     'port'=>11211,
+ *                     'weight'=>40,
+ *                 ),
+ *             ),
+ *         ),
+ *     ),
+ * )
+ * </pre>
+ * In the above, two memcache servers are used: server1 and server2.
+ * You can configure more properties of every server, including:
+ * host, port, persistent, weight, timeout, retryInterval, status.
+ * See {@link http://www.php.net/manual/en/function.memcache-addserver.php}
+ * for more details.
+ *
+ * CMemCache can also be used with {@link http://pecl.php.net/package/memcached memcached}.
+ * To do so, set {@link useMemcached} to be true.
+ *
+ * @property mixed $memCache The memcache instance (or memcached if {@link useMemcached} is true) used by this component.
+ * @property array $servers List of memcache server configurations. Each element is a {@link CMemCacheServerConfiguration}.
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @version $Id: CMemCache.php 3515 2011-12-28 12:29:24Z mdomba $
+ * @package system.caching
+ * @since 1.0
+ */
+class CMemCache extends CCache
+{
+	/**
+	 * @var boolean whether to use memcached or memcache as the underlying caching extension.
+	 * If true {@link http://pecl.php.net/package/memcached memcached} will be used.
+	 * If false {@link http://pecl.php.net/package/memcache memcache}. will be used.
+	 * Defaults to false.
+	 */
+	public $useMemcached=false;
+	/**
+	 * @var Memcache the Memcache instance
+	 */
+	private $_cache=null;
+	/**
+	 * @var array list of memcache server configurations
+	 */
+	private $_servers=array();
+
+	/**
+	 * Initializes this application component.
+	 * This method is required by the {@link IApplicationComponent} interface.
+	 * It creates the memcache instance and adds memcache servers.
+	 * @throws CException if memcache extension is not loaded
+	 */
+	public function init()
+	{
+		parent::init();
+		$servers=$this->getServers();
+		$cache=$this->getMemCache();
+		if(count($servers))
+		{
+			foreach($servers as $server)
+			{
+				if($this->useMemcached)
+					$cache->addServer($server->host,$server->port,$server->weight);
+				else
+					$cache->addServer($server->host,$server->port,$server->persistent,$server->weight,$server->timeout,$server->status);
+			}
+		}
+		else
+			$cache->addServer('localhost',11211);
+	}
+
+	/**
+	 * @return mixed the memcache instance (or memcached if {@link useMemcached} is true) used by this component.
+	 */
+	public function getMemCache()
+	{
+		if($this->_cache!==null)
+			return $this->_cache;
+		else
+			return $this->_cache=$this->useMemcached ? new Memcached : new Memcache;
+	}
+
+	/**
+	 * @return array list of memcache server configurations. Each element is a {@link CMemCacheServerConfiguration}.
+	 */
+	public function getServers()
+	{
+		return $this->_servers;
+	}
+
+	/**
+	 * @param array $config list of memcache server configurations. Each element must be an array
+	 * with the following keys: host, port, persistent, weight, timeout, retryInterval, status.
+	 * @see http://www.php.net/manual/en/function.Memcache-addServer.php
+	 */
+	public function setServers($config)
+	{
+		foreach($config as $c)
+			$this->_servers[]=new CMemCacheServerConfiguration($c);
+	}
+
+	/**
+	 * Retrieves a value from cache with a specified key.
+	 * This is the implementation of the method declared in the parent class.
+	 * @param string $key a unique key identifying the cached value
+	 * @return string the value stored in cache, false if the value is not in the cache or expired.
+	 */
+	protected function getValue($key)
+	{
+		return $this->_cache->get($key);
+	}
+
+	/**
+	 * Retrieves multiple values from cache with the specified keys.
+	 * @param array $keys a list of keys identifying the cached values
+	 * @return array a list of cached values indexed by the keys
+	 */
+	protected function getValues($keys)
+	{
+		return $this->useMemcached ? $this->_cache->getMulti($keys) : $this->_cache->get($keys);
+	}
+
+	/**
+	 * Stores a value identified by a key in cache.
+	 * This is the implementation of the method declared in the parent class.
+	 *
+	 * @param string $key the key identifying the value to be cached
+	 * @param string $value the value to be cached
+	 * @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire.
+	 * @return boolean true if the value is successfully stored into cache, false otherwise
+	 */
+	protected function setValue($key,$value,$expire)
+	{
+		if($expire>0)
+			$expire+=time();
+		else
+			$expire=0;
+
+		return $this->useMemcached ? $this->_cache->set($key,$value,$expire) : $this->_cache->set($key,$value,0,$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 $key the key identifying the value to be cached
+	 * @param string $value the value to be cached
+	 * @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire.
+	 * @return boolean true if the value is successfully stored into cache, false otherwise
+	 */
+	protected function addValue($key,$value,$expire)
+	{
+		if($expire>0)
+			$expire+=time();
+		else
+			$expire=0;
+
+		return $this->useMemcached ? $this->_cache->add($key,$value,$expire) : $this->_cache->add($key,$value,0,$expire);
+	}
+
+	/**
+	 * Deletes a value with the specified key from cache
+	 * This is the implementation of the method declared in the parent class.
+	 * @param string $key the key of the value to be deleted
+	 * @return boolean if no error happens during deletion
+	 */
+	protected function deleteValue($key)
+	{
+		return $this->_cache->delete($key, 0);
+	}
+
+	/**
+	 * Deletes all values from cache.
+	 * This is the implementation of the method declared in the parent class.
+	 * @return boolean whether the flush operation was successful.
+	 * @since 1.1.5
+	 */
+	protected function flushValues()
+	{
+		return $this->_cache->flush();
+	}
+}
+
+/**
+ * CMemCacheServerConfiguration represents the configuration data for a single memcache server.
+ *
+ * See {@link http://www.php.net/manual/en/function.Memcache-addServer.php}
+ * for detailed explanation of each configuration property.
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @version $Id: CMemCache.php 3515 2011-12-28 12:29:24Z mdomba $
+ * @package system.caching
+ * @since 1.0
+ */
+class CMemCacheServerConfiguration extends CComponent
+{
+	/**
+	 * @var string memcache server hostname or IP address
+	 */
+	public $host;
+	/**
+	 * @var integer memcache server port
+	 */
+	public $port=11211;
+	/**
+	 * @var boolean whether to use a persistent connection
+	 */
+	public $persistent=true;
+	/**
+	 * @var integer probability of using this server among all servers.
+	 */
+	public $weight=1;
+	/**
+	 * @var integer value in seconds which will be used for connecting to the server
+	 */
+	public $timeout=15;
+	/**
+	 * @var integer how often a failed server will be retried (in seconds)
+	 */
+	public $retryInterval=15;
+	/**
+	 * @var boolean if the server should be flagged as online upon a failure
+	 */
+	public $status=true;
+
+	/**
+	 * Constructor.
+	 * @param array $config list of memcache server configurations.
+	 * @throws CException if the configuration is not an array
+	 */
+	public function __construct($config)
+	{
+		if(is_array($config))
+		{
+			foreach($config as $key=>$value)
+				$this->$key=$value;
+			if($this->host===null)
+				throw new CException(Yii::t('yii','CMemCache server configuration must have "host" value.'));
+		}
+		else
+			throw new CException(Yii::t('yii','CMemCache server configuration must be an array.'));
+	}
+}
\ No newline at end of file
diff --git a/framework/caching/CWinCache.php b/framework/caching/CWinCache.php
new file mode 100644
index 0000000..82b0acf
--- /dev/null
+++ b/framework/caching/CWinCache.php
@@ -0,0 +1,109 @@
+<?php
+/**
+ * CWinCache class file
+ *
+ * @author Alexander Makarov <sam@rmcreative.ru>
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright &copy; 2008-2011 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+/**
+ * CWinCache implements a cache application component based on {@link http://www.iis.net/expand/wincacheforphp WinCache}.
+ *
+ * To use this application component, the WinCache PHP extension must be loaded.
+ *
+ * See {@link CCache} manual for common cache operations that are supported by CWinCache.
+ *
+ * @author Alexander Makarov <sam@rmcreative.ru>
+ * @version $Id: CWinCache.php 2799 2011-01-01 19:31:13Z qiang.xue $
+ * @package system.caching
+ * @since 1.1.2
+ */
+class CWinCache extends CCache {
+	/**
+	 * Initializes this application component.
+	 * This method is required by the {@link IApplicationComponent} interface.
+	 * It checks the availability of WinCache extension and WinCache user cache.
+	 * @throws CException if WinCache extension is not loaded or user cache is disabled
+	 */
+	public function init()
+	{
+		parent::init();
+		if(!extension_loaded('wincache'))
+			throw new CException(Yii::t('yii', 'CWinCache requires PHP wincache extension to be loaded.'));
+		if(!ini_get('wincache.ucenabled'))
+			throw new CException(Yii::t('yii', 'CWinCache user cache is disabled. Please set wincache.ucenabled to On in your php.ini.'));
+	}
+
+	/**
+	 * Retrieves a value from cache with a specified key.
+	 * This is the implementation of the method declared in the parent class.
+	 * @param string $key a unique key identifying the cached value
+	 * @return string the value stored in cache, false if the value is not in the cache or expired.
+	 */
+	protected function getValue($key)
+	{
+		return wincache_ucache_get($key);
+	}
+
+	/**
+	 * Retrieves multiple values from cache with the specified keys.
+	 * @param array $keys a list of keys identifying the cached values
+	 * @return array a list of cached values indexed by the keys	 
+	 */
+	protected function getValues($keys)
+	{
+		return wincache_ucache_get($keys);
+	}
+
+	/**
+	 * Stores a value identified by a key in cache.
+	 * This is the implementation of the method declared in the parent class.
+	 *
+	 * @param string $key the key identifying the value to be cached
+	 * @param string $value the value to be cached
+	 * @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire.
+	 * @return boolean true if the value is successfully stored into cache, false otherwise
+	 */
+	protected function setValue($key,$value,$expire)
+	{
+		return wincache_ucache_set($key,$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 $key the key identifying the value to be cached
+	 * @param string $value the value to be cached
+	 * @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire.
+	 * @return boolean true if the value is successfully stored into cache, false otherwise
+	 */
+	protected function addValue($key,$value,$expire)
+	{
+		return wincache_ucache_add($key,$value,$expire);
+	}
+
+	/**
+	 * Deletes a value with the specified key from cache
+	 * This is the implementation of the method declared in the parent class.
+	 * @param string $key the key of the value to be deleted
+	 * @return boolean if no error happens during deletion
+	 */
+	protected function deleteValue($key)
+	{
+		return wincache_ucache_delete($key);
+	}
+
+	/**
+	 * Deletes all values from cache.
+	 * This is the implementation of the method declared in the parent class.
+	 * @return boolean whether the flush operation was successful.
+	 * @since 1.1.5
+	 */
+	protected function flushValues()
+	{
+		return wincache_ucache_clear();
+	}
+}
\ No newline at end of file
diff --git a/framework/caching/CXCache.php b/framework/caching/CXCache.php
new file mode 100644
index 0000000..129c8bb
--- /dev/null
+++ b/framework/caching/CXCache.php
@@ -0,0 +1,103 @@
+<?php
+/**
+ * CXCache class file
+ *
+ * @author Wei Zhuo <weizhuo[at]gmail[dot]com>
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright &copy; 2008-2011 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+/**
+ * CXCache implements a cache application module based on {@link http://xcache.lighttpd.net/ xcache}.
+ *
+ * To use this application component, the XCache PHP extension must be loaded.
+ *
+ * See {@link CCache} manual for common cache operations that are supported by CXCache.
+ *
+ * @author Wei Zhuo <weizhuo[at]gmail[dot]com>
+ * @version $Id: CXCache.php 3515 2011-12-28 12:29:24Z mdomba $
+ * @package system.caching
+ */
+class CXCache extends CCache
+{
+	/**
+	 * Initializes this application component.
+	 * This method is required by the {@link IApplicationComponent} interface.
+	 * It checks the availability of memcache.
+	 * @throws CException if memcache extension is not loaded or is disabled.
+	 */
+	public function init()
+	{
+		parent::init();
+		if(!function_exists('xcache_isset'))
+			throw new CException(Yii::t('yii','CXCache requires PHP XCache extension to be loaded.'));
+	}
+
+	/**
+	 * Retrieves a value from cache with a specified key.
+	 * This is the implementation of the method declared in the parent class.
+	 * @param string $key a unique key identifying the cached value
+	 * @return string the value stored in cache, false if the value is not in the cache or expired.
+	 */
+	protected function getValue($key)
+	{
+		return xcache_isset($key) ? xcache_get($key) : false;
+	}
+
+	/**
+	 * Stores a value identified by a key in cache.
+	 * This is the implementation of the method declared in the parent class.
+	 *
+	 * @param string $key the key identifying the value to be cached
+	 * @param string $value the value to be cached
+	 * @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire.
+	 * @return boolean true if the value is successfully stored into cache, false otherwise
+	 */
+	protected function setValue($key,$value,$expire)
+	{
+		return xcache_set($key,$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 $key the key identifying the value to be cached
+	 * @param string $value the value to be cached
+	 * @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire.
+	 * @return boolean true if the value is successfully stored into cache, false otherwise
+	 */
+	protected function addValue($key,$value,$expire)
+	{
+		return !xcache_isset($key) ? $this->setValue($key,$value,$expire) : false;
+	}
+
+	/**
+	 * Deletes a value with the specified key from cache
+	 * This is the implementation of the method declared in the parent class.
+	 * @param string $key the key of the value to be deleted
+	 * @return boolean if no error happens during deletion
+	 */
+	protected function deleteValue($key)
+	{
+		return xcache_unset($key);
+	}
+
+	/**
+	 * Deletes all values from cache.
+	 * This is the implementation of the method declared in the parent class.
+	 * @return boolean whether the flush operation was successful.
+	 * @since 1.1.5
+	 */
+	protected function flushValues()
+	{
+		for($i=0, $max=xcache_count(XC_TYPE_VAR); $i<$max; $i++)
+		{
+			if(xcache_clear_cache(XC_TYPE_VAR, $i)===false)
+				return false;
+		}
+		return true;
+	}
+}
+
diff --git a/framework/caching/CZendDataCache.php b/framework/caching/CZendDataCache.php
new file mode 100644
index 0000000..c1a341d
--- /dev/null
+++ b/framework/caching/CZendDataCache.php
@@ -0,0 +1,99 @@
+<?php
+/**
+ * CZendDataCache class file
+ *
+ * @author Steffen Dietz <steffo.dietz[at]googlemail[dot]com>
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright &copy; 2008-2011 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+/**
+ * CZendDataCache implements a cache application module based on the Zend Data Cache
+ * delivered with {@link http://www.zend.com/en/products/server/ ZendServer}.
+ *
+ * To use this application component, the Zend Data Cache PHP extension must be loaded.
+ *
+ * See {@link CCache} manual for common cache operations that are supported by CZendDataCache.
+ *
+ * @author Steffen Dietz <steffo.dietz[at]googlemail[dot]com>
+ * @version $Id: CZendDataCache.php 3515 2011-12-28 12:29:24Z mdomba $
+ * @package system.caching
+ */
+class CZendDataCache extends CCache
+{
+	/**
+	 * Initializes this application component.
+	 * This method is required by the {@link IApplicationComponent} interface.
+	 * It checks the availability of Zend Data Cache.
+	 * @throws CException if Zend Data Cache extension is not loaded.
+	 */
+	public function init()
+	{
+		parent::init();
+		if(!function_exists('zend_shm_cache_store'))
+			throw new CException(Yii::t('yii','CZendDataCache requires PHP Zend Data Cache extension to be loaded.'));
+	}
+
+	/**
+	 * Retrieves a value from cache with a specified key.
+	 * This is the implementation of the method declared in the parent class.
+	 * @param string $key a unique key identifying the cached value
+	 * @return string the value stored in cache, false if the value is not in the cache or expired.
+	 */
+	protected function getValue($key)
+	{
+		$result = zend_shm_cache_fetch($key);
+		return $result !== NULL ? $result : false;
+	}
+
+	/**
+	 * Stores a value identified by a key in cache.
+	 * This is the implementation of the method declared in the parent class.
+	 *
+	 * @param string $key the key identifying the value to be cached
+	 * @param string $value the value to be cached
+	 * @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire.
+	 * @return boolean true if the value is successfully stored into cache, false otherwise
+	 */
+	protected function setValue($key,$value,$expire)
+	{
+		return zend_shm_cache_store($key,$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 $key the key identifying the value to be cached
+	 * @param string $value the value to be cached
+	 * @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire.
+	 * @return boolean true if the value is successfully stored into cache, false otherwise
+	 */
+	protected function addValue($key,$value,$expire)
+	{
+		return (NULL === zend_shm_cache_fetch($key)) ? $this->setValue($key,$value,$expire) : false;
+	}
+
+	/**
+	 * Deletes a value with the specified key from cache
+	 * This is the implementation of the method declared in the parent class.
+	 * @param string $key the key of the value to be deleted
+	 * @return boolean if no error happens during deletion
+	 */
+	protected function deleteValue($key)
+	{
+		return zend_shm_cache_delete($key);
+	}
+
+	/**
+	 * Deletes all values from cache.
+	 * This is the implementation of the method declared in the parent class.
+	 * @return boolean whether the flush operation was successful.
+	 * @since 1.1.5
+	 */
+	protected function flushValues()
+	{
+		return zend_shm_cache_clear();
+	}
+}
diff --git a/framework/caching/dependencies/CCacheDependency.php b/framework/caching/dependencies/CCacheDependency.php
new file mode 100644
index 0000000..ca0f318
--- /dev/null
+++ b/framework/caching/dependencies/CCacheDependency.php
@@ -0,0 +1,66 @@
+<?php
+/**
+ * CCacheDependency class file.
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright &copy; 2008-2011 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+/**
+ * CCacheDependency is the base class for cache dependency classes.
+ *
+ * CCacheDependency implements the {@link ICacheDependency} interface.
+ * Child classes should override its {@link generateDependentData} for
+ * actual dependency checking.
+ *
+ * @property boolean $hasChanged Whether the dependency has changed.
+ * @property mixed $dependentData The data used to determine if dependency has been changed.
+ * This data is available after {@link evaluateDependency} is called.
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @version $Id: CCacheDependency.php 3426 2011-10-25 00:01:09Z alexander.makarow $
+ * @package system.caching.dependencies
+ * @since 1.0
+ */
+class CCacheDependency extends CComponent implements ICacheDependency
+{
+	private $_data;
+
+	/**
+	 * Evaluates the dependency by generating and saving the data related with dependency.
+	 * This method is invoked by cache before writing data into it.
+	 */
+	public function evaluateDependency()
+	{
+		$this->_data=$this->generateDependentData();
+	}
+
+	/**
+	 * @return boolean whether the dependency has changed.
+	 */
+	public function getHasChanged()
+	{
+		return $this->generateDependentData()!=$this->_data;
+	}
+
+	/**
+	 * @return mixed the data used to determine if dependency has been changed.
+	 * This data is available after {@link evaluateDependency} is called.
+	 */
+	public function getDependentData()
+	{
+		return $this->_data;
+	}
+
+	/**
+	 * Generates the data needed to determine if dependency has been changed.
+	 * Derived classes should override this method to generate actual dependent data.
+	 * @return mixed the data needed to determine if dependency has been changed.
+	 */
+	protected function generateDependentData()
+	{
+		return null;
+	}
+}
\ No newline at end of file
diff --git a/framework/caching/dependencies/CChainedCacheDependency.php b/framework/caching/dependencies/CChainedCacheDependency.php
new file mode 100644
index 0000000..a7b985f
--- /dev/null
+++ b/framework/caching/dependencies/CChainedCacheDependency.php
@@ -0,0 +1,98 @@
+<?php
+/**
+ * CChainedCacheDependency class file.
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright &copy; 2008-2011 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+/**
+ * CChainedCacheDependency represents a list of cache dependencies.
+ *
+ * If any of the dependencies reports a dependency change, CChainedCacheDependency
+ * will return true for the checking.
+ *
+ * To add dependencies to CChainedCacheDependency, use {@link getDependencies Dependencies}
+ * which gives a {@link CTypedList} instance and can be used like an array
+ * (see {@link CList} for more details}).
+ *
+ * @property CTypedList $dependencies List of dependency objects.
+ * @property boolean $hasChanged Whether the dependency is changed or not.
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @version $Id: CChainedCacheDependency.php 3515 2011-12-28 12:29:24Z mdomba $
+ * @package system.caching.dependencies
+ * @since 1.0
+ */
+class CChainedCacheDependency extends CComponent implements ICacheDependency
+{
+	private $_dependencies=null;
+
+	/**
+	 * Constructor.
+	 * @param array $dependencies the dependencies to be added to this chain.
+	 * @since 1.1.4
+	 */
+	public function __construct($dependencies=array())
+	{
+		if(!empty($dependencies))
+			$this->setDependencies($dependencies);
+	}
+
+	/**
+	 * @return CTypedList list of dependency objects
+	 */
+	public function getDependencies()
+	{
+		if($this->_dependencies===null)
+			$this->_dependencies=new CTypedList('ICacheDependency');
+		return $this->_dependencies;
+	}
+
+	/**
+	 * @param array $values list of dependency objects or configurations to be added to this chain.
+	 * If a depedency is specified as a configuration, it must be an array that can be recognized
+	 * by {@link YiiBase::createComponent}.
+	 */
+	public function setDependencies($values)
+	{
+		$dependencies=$this->getDependencies();
+		foreach($values as $value)
+		{
+			if(is_array($value))
+				$value=Yii::createComponent($value);
+			$dependencies->add($value);
+		}
+	}
+
+	/**
+	 * Evaluates the dependency by generating and saving the data related with dependency.
+	 */
+	public function evaluateDependency()
+	{
+		if($this->_dependencies!==null)
+		{
+			foreach($this->_dependencies as $dependency)
+				$dependency->evaluateDependency();
+		}
+	}
+
+	/**
+	 * Performs the actual dependency checking.
+	 * This method returns true if any of the dependency objects
+	 * reports a dependency change.
+	 * @return boolean whether the dependency is changed or not.
+	 */
+	public function getHasChanged()
+	{
+		if($this->_dependencies!==null)
+		{
+			foreach($this->_dependencies as $dependency)
+				if($dependency->getHasChanged())
+					return true;
+		}
+		return false;
+	}
+}
diff --git a/framework/caching/dependencies/CDbCacheDependency.php b/framework/caching/dependencies/CDbCacheDependency.php
new file mode 100644
index 0000000..98b8e8d
--- /dev/null
+++ b/framework/caching/dependencies/CDbCacheDependency.php
@@ -0,0 +1,112 @@
+<?php
+/**
+ * CDbCacheDependency class file.
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright &copy; 2008-2011 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+/**
+ * CDbCacheDependency represents a dependency based on the query result of a SQL statement.
+ *
+ * If the query result (a scalar) changes, the dependency is considered as changed.
+ * To specify the SQL statement, set {@link sql} property.
+ * The {@link connectionID} property specifies the ID of a {@link CDbConnection} application
+ * component. It is this DB connection that is used to perform the query.
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @version $Id: CDbCacheDependency.php 3204 2011-05-05 21:36:32Z alexander.makarow $
+ * @package system.caching.dependencies
+ * @since 1.0
+ */
+class CDbCacheDependency extends CCacheDependency
+{
+	/**
+	 * @var string the ID of a {@link CDbConnection} application component. Defaults to 'db'.
+	 */
+	public $connectionID='db';
+	/**
+	 * @var string the SQL statement whose result is used to determine if the dependency has been changed.
+	 * Note, the SQL statement should return back a single value.
+	 */
+	public $sql;
+	/**
+	 * @var array parameters (name=>value) to be bound to the SQL statement specified by {@link sql}.
+	 * @since 1.1.4
+	 */
+	public $params;
+
+	private $_db;
+
+	/**
+	 * Constructor.
+	 * @param string $sql the SQL statement whose result is used to determine if the dependency has been changed.
+	 */
+	public function __construct($sql=null)
+	{
+		$this->sql=$sql;
+	}
+
+	/**
+	 * PHP sleep magic method.
+	 * This method ensures that the database instance is set null because it contains resource handles.
+	 * @return array
+	 */
+	public function __sleep()
+	{
+		$this->_db=null;
+		return array_keys((array)$this);
+	}
+
+	/**
+	 * Generates the data needed to determine if dependency has been changed.
+	 * This method returns the value of the global state.
+	 * @return mixed the data needed to determine if dependency has been changed.
+	 */
+	protected function generateDependentData()
+	{
+		if($this->sql!==null)
+		{
+			$db=$this->getDbConnection();
+			$command=$db->createCommand($this->sql);
+			if(is_array($this->params))
+			{
+				foreach($this->params as $name=>$value)
+					$command->bindValue($name,$value);
+			}
+			if($db->queryCachingDuration>0)
+			{
+				// temporarily disable and re-enable query caching
+				$duration=$db->queryCachingDuration;
+				$db->queryCachingDuration=0;
+				$result=$command->queryRow();
+				$db->queryCachingDuration=$duration;
+			}
+			else
+				$result=$command->queryRow();
+			return $result;
+		}
+		else
+			throw new CException(Yii::t('yii','CDbCacheDependency.sql cannot be empty.'));
+	}
+
+	/**
+	 * @return CDbConnection the DB connection instance
+	 * @throws CException if {@link connectionID} does not point to a valid application component.
+	 */
+	protected function getDbConnection()
+	{
+		if($this->_db!==null)
+			return $this->_db;
+		else
+		{
+			if(($this->_db=Yii::app()->getComponent($this->connectionID)) instanceof CDbConnection)
+				return $this->_db;
+			else
+				throw new CException(Yii::t('yii','CDbCacheDependency.connectionID "{id}" is invalid. Please make sure it refers to the ID of a CDbConnection application component.',
+					array('{id}'=>$this->connectionID)));
+		}
+	}
+}
diff --git a/framework/caching/dependencies/CDirectoryCacheDependency.php b/framework/caching/dependencies/CDirectoryCacheDependency.php
new file mode 100644
index 0000000..2ebab9c
--- /dev/null
+++ b/framework/caching/dependencies/CDirectoryCacheDependency.php
@@ -0,0 +1,134 @@
+<?php
+/**
+ * CDirectoryCacheDependency class file.
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright &copy; 2008-2011 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+/**
+ * CDirectoryCacheDependency represents a dependency based on change of a directory.
+ *
+ * CDirectoryCacheDependency performs dependency checking based on the
+ * modification time of the files contained in the specified directory.
+ * The directory being checked is specified via {@link directory}.
+ *
+ * By default, all files under the specified directory and subdirectories
+ * will be checked. If the last modification time of any of them is changed
+ * or if different number of files are contained in a directory, the dependency
+ * is reported as changed. By specifying {@link recursiveLevel},
+ * one can limit the checking to a certain depth of the directory.
+ *
+ * Note, dependency checking for a directory is expensive because it involves
+ * accessing modification time of multiple files under the directory.
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @version $Id: CDirectoryCacheDependency.php 3500 2011-12-20 16:25:43Z mdomba $
+ * @package system.caching.dependencies
+ * @since 1.0
+ */
+class CDirectoryCacheDependency extends CCacheDependency
+{
+	/**
+	 * @var string the directory whose change is used to determine if the dependency has been changed.
+	 * If any of the files under the directory is changed, the dependency is considered as changed.
+	 */
+	public $directory;
+	/**
+	 * @var integer the depth of the subdirectories to be recursively checked.
+	 * If the value is less than 0, it means unlimited depth.
+	 * If the value is 0, it means checking the files directly under the specified directory.
+	 */
+	public $recursiveLevel=-1;
+	/**
+	 * @var string the regular expression matching valid file/directory names.
+	 * Only the matching files or directories will be checked for changes.
+	 * Defaults to null, meaning all files/directories will qualify.
+	 */
+	public $namePattern;
+
+	/**
+	 * Constructor.
+	 * @param string $directory the directory to be checked
+	 */
+	public function __construct($directory=null)
+	{
+		$this->directory=$directory;
+	}
+
+	/**
+	 * Generates the data needed to determine if dependency has been changed.
+	 * This method returns the modification timestamps for files under the directory.
+	 * @return mixed the data needed to determine if dependency has been changed.
+	 */
+	protected function generateDependentData()
+	{
+		if($this->directory!==null)
+			return $this->generateTimestamps($this->directory);
+		else
+			throw new CException(Yii::t('yii','CDirectoryCacheDependency.directory cannot be empty.'));
+	}
+
+	/**
+	 * Determines the last modification time for files under the directory.
+	 * This method may go recursively into subdirectories if {@link recursiveLevel} is not 0.
+	 * @param string $directory the directory name
+	 * @param integer $level level of the recursion
+	 * @return array list of file modification time indexed by the file path
+	 */
+	protected function generateTimestamps($directory,$level=0)
+	{
+		if(($dir=@opendir($directory))===false)
+			throw new CException(Yii::t('yii','"{path}" is not a valid directory.',
+				array('{path}'=>$directory)));
+		$timestamps=array();
+		while(($file=readdir($dir))!==false)
+		{
+			$path=$directory.DIRECTORY_SEPARATOR.$file;
+			if($file==='.' || $file==='..')
+				continue;
+			if($this->namePattern!==null && !preg_match($this->namePattern,$file))
+				continue;
+			if(is_file($path))
+			{
+				if($this->validateFile($path))
+					$timestamps[$path]=filemtime($path);
+			}
+			else
+			{
+				if(($this->recursiveLevel<0 || $level<$this->recursiveLevel) && $this->validateDirectory($path))
+					$timestamps=array_merge($timestamps, $this->generateTimestamps($path,$level+1));
+			}
+		}
+		closedir($dir);
+		return $timestamps;
+	}
+
+	/**
+	 * Checks to see if the file should be checked for dependency.
+	 * This method is invoked when dependency of the whole directory is being checked.
+	 * By default, it always returns true, meaning the file should be checked.
+	 * You may override this method to check only certain files.
+	 * @param string $fileName the name of the file that may be checked for dependency.
+	 * @return boolean whether this file should be checked.
+	 */
+	protected function validateFile($fileName)
+	{
+		return true;
+	}
+
+	/**
+	 * Checks to see if the specified subdirectory should be checked for dependency.
+	 * This method is invoked when dependency of the whole directory is being checked.
+	 * By default, it always returns true, meaning the subdirectory should be checked.
+	 * You may override this method to check only certain subdirectories.
+	 * @param string $directory the name of the subdirectory that may be checked for dependency.
+	 * @return boolean whether this subdirectory should be checked.
+	 */
+	protected function validateDirectory($directory)
+	{
+		return true;
+	}
+}
diff --git a/framework/caching/dependencies/CExpressionDependency.php b/framework/caching/dependencies/CExpressionDependency.php
new file mode 100644
index 0000000..393ac96
--- /dev/null
+++ b/framework/caching/dependencies/CExpressionDependency.php
@@ -0,0 +1,53 @@
+<?php
+/**
+ * CExpressionDependency class file.
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright &copy; 2008-2011 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+/**
+ * CExpressionDependency represents a dependency based on the result of a PHP expression.
+ *
+ * CExpressionDependency performs dependency checking based on the
+ * result of a PHP {@link expression}.
+ * The dependency is reported as unchanged if and only if the result is
+ * the same as the one evaluated when storing the data to cache.
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @version $Id: CExpressionDependency.php 3515 2011-12-28 12:29:24Z mdomba $
+ * @package system.caching.dependencies
+ * @since 1.0
+ */
+class CExpressionDependency extends CCacheDependency
+{
+	/**
+	 * @var string the PHP expression whose result is used to determine the dependency.
+	 * The expression can also be a valid PHP callback,
+	 * including class method name (array(ClassName/Object, MethodName)),
+	 * or anonymous function (PHP 5.3.0+). The function/method will be passed with a
+	 * parameter which is the dependency object itself.
+	 */
+	public $expression;
+
+	/**
+	 * Constructor.
+	 * @param string $expression the PHP expression whose result is used to determine the dependency.
+	 */
+	public function __construct($expression='true')
+	{
+		$this->expression=$expression;
+	}
+
+	/**
+	 * Generates the data needed to determine if dependency has been changed.
+	 * This method returns the result of the PHP expression.
+	 * @return mixed the data needed to determine if dependency has been changed.
+	 */
+	protected function generateDependentData()
+	{
+		return $this->evaluateExpression($this->expression);
+	}
+}
diff --git a/framework/caching/dependencies/CFileCacheDependency.php b/framework/caching/dependencies/CFileCacheDependency.php
new file mode 100644
index 0000000..44907cd
--- /dev/null
+++ b/framework/caching/dependencies/CFileCacheDependency.php
@@ -0,0 +1,53 @@
+<?php
+/**
+ * CFileCacheDependency class file.
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright &copy; 2008-2011 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+/**
+ * CFileCacheDependency represents a dependency based on a file's last modification time.
+ *
+ * CFileCacheDependency performs dependency checking based on the
+ * last modification time of the file specified via {@link fileName}.
+ * The dependency is reported as unchanged if and only if the file's
+ * last modification time remains unchanged.
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @version $Id: CFileCacheDependency.php 2799 2011-01-01 19:31:13Z qiang.xue $
+ * @package system.caching.dependencies
+ * @since 1.0
+ */
+class CFileCacheDependency extends CCacheDependency
+{
+	/**
+	 * @var string the name of the file whose last modification time is used to
+	 * check if the dependency has been changed.
+	 */
+	public $fileName;
+
+	/**
+	 * Constructor.
+	 * @param string $fileName name of the file whose change is to be checked.
+	 */
+	public function __construct($fileName=null)
+	{
+		$this->fileName=$fileName;
+	}
+
+	/**
+	 * Generates the data needed to determine if dependency has been changed.
+	 * This method returns the file's last modification time.
+	 * @return mixed the data needed to determine if dependency has been changed.
+	 */
+	protected function generateDependentData()
+	{
+		if($this->fileName!==null)
+			return @filemtime($this->fileName);
+		else
+			throw new CException(Yii::t('yii','CFileCacheDependency.fileName cannot be empty.'));
+	}
+}
diff --git a/framework/caching/dependencies/CGlobalStateCacheDependency.php b/framework/caching/dependencies/CGlobalStateCacheDependency.php
new file mode 100644
index 0000000..4775fc6
--- /dev/null
+++ b/framework/caching/dependencies/CGlobalStateCacheDependency.php
@@ -0,0 +1,54 @@
+<?php
+/**
+ * CGlobalStateCacheDependency class file.
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright &copy; 2008-2011 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+/**
+ * CGlobalStateCacheDependency represents a dependency based on a global state value.
+ *
+ * CGlobalStateCacheDependency checks if a global state is changed or not.
+ * If the global state is changed, the dependency is reported as changed.
+ * To specify which global state this dependency should check with,
+ * set {@link stateName} to the name of the global state.
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @version $Id: CGlobalStateCacheDependency.php 2799 2011-01-01 19:31:13Z qiang.xue $
+ * @package system.caching.dependencies
+ * @since 1.0
+ */
+class CGlobalStateCacheDependency extends CCacheDependency
+{
+	/**
+	 * @var string the name of the global state whose value is to check
+	 * if the dependency has changed.
+	 * @see CApplication::setGlobalState
+	 */
+	public $stateName;
+
+	/**
+	 * Constructor.
+	 * @param string $name the name of the global state
+	 */
+	public function __construct($name=null)
+	{
+		$this->stateName=$name;
+	}
+
+	/**
+	 * Generates the data needed to determine if dependency has been changed.
+	 * This method returns the value of the global state.
+	 * @return mixed the data needed to determine if dependency has been changed.
+	 */
+	protected function generateDependentData()
+	{
+		if($this->stateName!==null)
+			return Yii::app()->getGlobalState($this->stateName);
+		else
+			throw new CException(Yii::t('yii','CGlobalStateCacheDependency.stateName cannot be empty.'));
+	}
+}