/yii/framework/caching/CCache.php
PHP | 334 lines | 127 code | 19 blank | 188 comment | 11 complexity | f1fec9ed4106f82af3189693fde0539e MD5 | raw file
- <?php
- /**
- * CCache class file.
- *
- * @author Qiang Xue <qiang.xue@gmail.com>
- * @link http://www.yiiframework.com/
- * @copyright Copyright © 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 3001 2011-02-24 16:42:44Z alexander.makarow $
- * @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 $ids list of keys identifying the cached values
- * @return array list of cached values corresponding to the specified keys. The array
- * is returned in terms of (key,value) pairs.
- * If a value is not cached or expired, the corresponding array value will be false.
- * @since 1.0.8
- */
- public function mget($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 $keys a list of keys identifying the cached values
- * @return array a list of cached values indexed by the keys
- * @since 1.0.8
- */
- protected function getValues($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);
- }
- }