diff --git a/framework/yii/caching/Cache.php b/framework/yii/caching/Cache.php
index fc1027c..a6ee455 100644
--- a/framework/yii/caching/Cache.php
+++ b/framework/yii/caching/Cache.php
@@ -95,16 +95,10 @@ abstract class Cache extends Component implements \ArrayAccess
 	 * then the key will be returned back prefixed with [[keyPrefix]]. Otherwise, a normalized key
 	 * is generated by serializing the given key, applying MD5 hashing, and prefixing with [[keyPrefix]].
 	 * 
-	 * The following example builds a cache key using three parameters:
-	 *
-	 * ~~~
-	 * $key = $cache->buildKey(array($className, $method, $id));
-	 * ~~~
-	 *
 	 * @param mixed $key the key to be normalized
 	 * @return string the generated cache key
 	 */
-	public function buildKey($key)
+	protected function buildKey($key)
 	{
 		if (is_string($key)) {
 			$key = ctype_alnum($key) && StringHelper::strlen($key) <= 32 ? $key : md5($key);
@@ -116,7 +110,8 @@ abstract class Cache extends Component implements \ArrayAccess
 
 	/**
 	 * Retrieves a value from cache with a specified key.
-	 * @param string $key a key identifying the cached value
+	 * @param mixed $key a key identifying the cached value. This can be a simple string or
+	 * a complex data structure consisting of factors representing the key.
 	 * @return mixed the value stored in cache, false if the value is not in the cache, expired,
 	 * or the dependency associated with the cached data has changed.
 	 */
@@ -131,7 +126,7 @@ abstract class Cache extends Component implements \ArrayAccess
 		} else {
 			$value = call_user_func($this->serializer[1], $value);
 		}
-		if (is_array($value) && !($value[1] instanceof Dependency && $value[1]->getHasChanged())) {
+		if (is_array($value) && !($value[1] instanceof Dependency && $value[1]->getHasChanged($this))) {
 			return $value[0];
 		} else {
 			return false;
@@ -165,7 +160,7 @@ abstract class Cache extends Component implements \ArrayAccess
 					$value = $this->serializer === null ? unserialize($values[$newKey])
 							: call_user_func($this->serializer[1], $values[$newKey]);
 
-					if (is_array($value) && !($value[1] instanceof Dependency && $value[1]->getHasChanged())) {
+					if (is_array($value) && !($value[1] instanceof Dependency && $value[1]->getHasChanged($this))) {
 						$results[$key] = $value[0];
 					}
 				}
@@ -179,7 +174,8 @@ abstract class Cache extends Component implements \ArrayAccess
 	 * If the cache already contains such a key, the existing value and
 	 * expiration time will be replaced with the new ones, respectively.
 	 *
-	 * @param string $key the key identifying the value to be cached
+	 * @param mixed $key a key identifying the value to be cached value. This can be a simple string or
+	 * a complex data structure consisting of factors representing the key.
 	 * @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 Dependency $dependency dependency of the cached item. If the dependency changes,
@@ -190,7 +186,7 @@ abstract class Cache extends Component implements \ArrayAccess
 	public function set($key, $value, $expire = 0, $dependency = null)
 	{
 		if ($dependency !== null && $this->serializer !== false) {
-			$dependency->evaluateDependency();
+			$dependency->evaluateDependency($this);
 		}
 		if ($this->serializer === null) {
 			$value = serialize(array($value, $dependency));
@@ -204,7 +200,8 @@ abstract class Cache extends Component implements \ArrayAccess
 	/**
 	 * 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 $key the key identifying the value to be cached
+	 * @param mixed $key a key identifying the value to be cached value. This can be a simple string or
+	 * a complex data structure consisting of factors representing the key.
 	 * @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 Dependency $dependency dependency of the cached item. If the dependency changes,
@@ -215,7 +212,7 @@ abstract class Cache extends Component implements \ArrayAccess
 	public function add($key, $value, $expire = 0, $dependency = null)
 	{
 		if ($dependency !== null && $this->serializer !== false) {
-			$dependency->evaluateDependency();
+			$dependency->evaluateDependency($this);
 		}
 		if ($this->serializer === null) {
 			$value = serialize(array($value, $dependency));
@@ -228,7 +225,8 @@ abstract class Cache extends Component implements \ArrayAccess
 
 	/**
 	 * Deletes a value with the specified key from cache
-	 * @param string $key the key of the value to be deleted
+	 * @param mixed $key a key identifying the value to be deleted from cache. This can be a simple string or
+	 * a complex data structure consisting of factors representing the key.
 	 * @return boolean if no error happens during deletion
 	 */
 	public function delete($key)
diff --git a/framework/yii/caching/ChainedDependency.php b/framework/yii/caching/ChainedDependency.php
index 7c7058e..87debfe 100644
--- a/framework/yii/caching/ChainedDependency.php
+++ b/framework/yii/caching/ChainedDependency.php
@@ -48,20 +48,22 @@ class ChainedDependency extends Dependency
 
 	/**
 	 * Evaluates the dependency by generating and saving the data related with dependency.
+	 * @param Cache $cache the cache component that is currently evaluating this dependency
 	 */
-	public function evaluateDependency()
+	public function evaluateDependency($cache)
 	{
 		foreach ($this->dependencies as $dependency) {
-			$dependency->evaluateDependency();
+			$dependency->evaluateDependency($cache);
 		}
 	}
 
 	/**
 	 * Generates the data needed to determine if dependency has been changed.
 	 * This method does nothing in this class.
+	 * @param Cache $cache the cache component that is currently evaluating this dependency
 	 * @return mixed the data needed to determine if dependency has been changed.
 	 */
-	protected function generateDependencyData()
+	protected function generateDependencyData($cache)
 	{
 		return null;
 	}
@@ -70,14 +72,15 @@ class ChainedDependency extends Dependency
 	 * Performs the actual dependency checking.
 	 * This method returns true if any of the dependency objects
 	 * reports a dependency change.
+	 * @param Cache $cache the cache component that is currently evaluating this dependency
 	 * @return boolean whether the dependency is changed or not.
 	 */
-	public function getHasChanged()
+	public function getHasChanged($cache)
 	{
 		foreach ($this->dependencies as $dependency) {
-			if ($this->dependOnAll && $dependency->getHasChanged()) {
+			if ($this->dependOnAll && $dependency->getHasChanged($cache)) {
 				return true;
-			} elseif (!$this->dependOnAll && !$dependency->getHasChanged()) {
+			} elseif (!$this->dependOnAll && !$dependency->getHasChanged($cache)) {
 				return false;
 			}
 		}
diff --git a/framework/yii/caching/DbDependency.php b/framework/yii/caching/DbDependency.php
index fd92aea..da6f20b 100644
--- a/framework/yii/caching/DbDependency.php
+++ b/framework/yii/caching/DbDependency.php
@@ -52,10 +52,11 @@ class DbDependency extends Dependency
 	/**
 	 * Generates the data needed to determine if dependency has been changed.
 	 * This method returns the value of the global state.
-	 * @throws InvalidConfigException
+	 * @param Cache $cache the cache component that is currently evaluating this dependency
 	 * @return mixed the data needed to determine if dependency has been changed.
+	 * @throws InvalidConfigException if [[db]] is not a valid application component ID
 	 */
-	protected function generateDependencyData()
+	protected function generateDependencyData($cache)
 	{
 		$db = Yii::$app->getComponent($this->db);
 		if (!$db instanceof Connection) {
diff --git a/framework/yii/caching/Dependency.php b/framework/yii/caching/Dependency.php
index 5c7249a..1a8770b 100644
--- a/framework/yii/caching/Dependency.php
+++ b/framework/yii/caching/Dependency.php
@@ -46,35 +46,38 @@ abstract class Dependency extends \yii\base\Object
 	/**
 	 * Evaluates the dependency by generating and saving the data related with dependency.
 	 * This method is invoked by cache before writing data into it.
+	 * @param Cache $cache the cache component that is currently evaluating this dependency
 	 */
-	public function evaluateDependency()
+	public function evaluateDependency($cache)
 	{
 		if (!$this->reusable) {
-			$this->data = $this->generateDependencyData();
+			$this->data = $this->generateDependencyData($cache);
 		} else {
 			if ($this->_hash === null) {
 				$this->_hash = sha1(serialize($this));
 			}
 			if (!array_key_exists($this->_hash, self::$_reusableData)) {
-				self::$_reusableData[$this->_hash] = $this->generateDependencyData();
+				self::$_reusableData[$this->_hash] = $this->generateDependencyData($cache);
 			}
 			$this->data = self::$_reusableData[$this->_hash];
 		}
 	}
 
 	/**
+	 * Returns a value indicating whether the dependency has changed.
+	 * @param Cache $cache the cache component that is currently evaluating this dependency
 	 * @return boolean whether the dependency has changed.
 	 */
-	public function getHasChanged()
+	public function getHasChanged($cache)
 	{
 		if (!$this->reusable) {
-			return $this->generateDependencyData() !== $this->data;
+			return $this->generateDependencyData($cache) !== $this->data;
 		} else {
 			if ($this->_hash === null) {
 				$this->_hash = sha1(serialize($this));
 			}
 			if (!array_key_exists($this->_hash, self::$_reusableData)) {
-				self::$_reusableData[$this->_hash] = $this->generateDependencyData();
+				self::$_reusableData[$this->_hash] = $this->generateDependencyData($cache);
 			}
 			return self::$_reusableData[$this->_hash] !== $this->data;
 		}
@@ -91,7 +94,8 @@ abstract class Dependency extends \yii\base\Object
 	/**
 	 * Generates the data needed to determine if dependency has been changed.
 	 * Derived classes should override this method to generate the actual dependency data.
+	 * @param Cache $cache the cache component that is currently evaluating this dependency
 	 * @return mixed the data needed to determine if dependency has been changed.
 	 */
-	abstract protected function generateDependencyData();
+	abstract protected function generateDependencyData($cache);
 }
diff --git a/framework/yii/caching/ExpressionDependency.php b/framework/yii/caching/ExpressionDependency.php
index 9300995..533c2ab 100644
--- a/framework/yii/caching/ExpressionDependency.php
+++ b/framework/yii/caching/ExpressionDependency.php
@@ -50,9 +50,10 @@ class ExpressionDependency extends Dependency
 	/**
 	 * Generates the data needed to determine if dependency has been changed.
 	 * This method returns the result of the PHP expression.
+	 * @param Cache $cache the cache component that is currently evaluating this dependency
 	 * @return mixed the data needed to determine if dependency has been changed.
 	 */
-	protected function generateDependencyData()
+	protected function generateDependencyData($cache)
 	{
 		return eval("return {$this->expression};");
 	}
diff --git a/framework/yii/caching/FileDependency.php b/framework/yii/caching/FileDependency.php
index 3797dde..bcc48a8 100644
--- a/framework/yii/caching/FileDependency.php
+++ b/framework/yii/caching/FileDependency.php
@@ -38,9 +38,10 @@ class FileDependency extends Dependency
 	/**
 	 * Generates the data needed to determine if dependency has been changed.
 	 * This method returns the file's last modification time.
+	 * @param Cache $cache the cache component that is currently evaluating this dependency
 	 * @return mixed the data needed to determine if dependency has been changed.
 	 */
-	protected function generateDependencyData()
+	protected function generateDependencyData($cache)
 	{
 		return @filemtime($this->fileName);
 	}