376 lines
15 KiB
PHP
376 lines
15 KiB
PHP
<?php
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/**
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* CCache class file.
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*
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* @author Qiang Xue <qiang.xue@gmail.com>
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* @link http://www.yiiframework.com/
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* @copyright 2008-2013 Yii Software LLC
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* @license http://www.yiiframework.com/license/
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*/
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/**
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* CCache is the base class for cache classes with different cache storage implementation.
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*
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* A data item can be stored in cache by calling {@link set} and be retrieved back
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* later by {@link get}. In both operations, a key identifying the data item is required.
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* An expiration time and/or a dependency can also be specified when calling {@link set}.
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* If the data item expires or the dependency changes, calling {@link get} will not
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* return back the data item.
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*
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* Note, by definition, cache does not ensure the existence of a value
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* even if it does not expire. Cache is not meant to be a persistent storage.
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*
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* CCache implements the interface {@link ICache} with the following methods:
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* <ul>
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* <li>{@link get} : retrieve the value with a key (if any) from cache</li>
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* <li>{@link set} : store the value with a key into cache</li>
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* <li>{@link add} : store the value only if cache does not have this key</li>
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* <li>{@link delete} : delete the value with the specified key from cache</li>
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* <li>{@link flush} : delete all values from cache</li>
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* </ul>
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*
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* Child classes must implement the following methods:
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* <ul>
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* <li>{@link getValue}</li>
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* <li>{@link setValue}</li>
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* <li>{@link addValue}</li>
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* <li>{@link deleteValue}</li>
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* <li>{@link getValues} (optional)</li>
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* <li>{@link flushValues} (optional)</li>
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* <li>{@link serializer} (optional)</li>
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* </ul>
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*
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* CCache also implements ArrayAccess so that it can be used like an array.
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*
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* @author Qiang Xue <qiang.xue@gmail.com>
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* @package system.caching
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* @since 1.0
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*/
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abstract class CCache extends CApplicationComponent implements ICache, ArrayAccess
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{
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/**
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* @var string a string prefixed to every cache key so that it is unique. Defaults to null which means
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* to use the {@link CApplication::getId() application ID}. If different applications need to access the same
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* pool of cached data, the same prefix should be set for each of the applications explicitly.
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*/
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public $keyPrefix;
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/**
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* @var boolean whether to md5-hash the cache key for normalization purposes. Defaults to true. Setting this property to false makes sure the cache
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* key will not be tampered when calling the relevant methods {@link get()}, {@link set()}, {@link add()} and {@link delete()}. This is useful if a Yii
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* application as well as an external application need to access the same cache pool (also see description of {@link keyPrefix} regarding this use case).
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* However, without normalization you should make sure the affected cache backend does support the structure (charset, length, etc.) of all the provided
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* cache keys, otherwise there might be unexpected behavior.
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* @since 1.1.11
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**/
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public $hashKey=true;
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/**
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* @var array|boolean the functions used to serialize and unserialize cached data. Defaults to null, meaning
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* using the default PHP `serialize()` and `unserialize()` functions. If you want to use some more efficient
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* serializer (e.g. {@link http://pecl.php.net/package/igbinary igbinary}), you may configure this property with
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* a two-element array. The first element specifies the serialization function, and the second the deserialization
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* function. If this property is set false, data will be directly sent to and retrieved from the underlying
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* cache component without any serialization or deserialization. You should not turn off serialization if
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* you are using {@link CCacheDependency cache dependency}, because it relies on data serialization.
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*/
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public $serializer;
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/**
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* Initializes the application component.
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* This method overrides the parent implementation by setting default cache key prefix.
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*/
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public function init()
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{
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parent::init();
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if($this->keyPrefix===null)
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$this->keyPrefix=Yii::app()->getId();
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}
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/**
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* @param string $key a key identifying a value to be cached
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* @return string a key generated from the provided key which ensures the uniqueness across applications
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*/
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protected function generateUniqueKey($key)
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{
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return $this->hashKey ? md5($this->keyPrefix.$key) : $this->keyPrefix.$key;
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}
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/**
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* Retrieves a value from cache with a specified key.
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* @param string $id a key identifying the cached value
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* @return mixed the value stored in cache, false if the value is not in the cache, expired or the dependency has changed.
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*/
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public function get($id)
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{
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$value = $this->getValue($this->generateUniqueKey($id));
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if($value===false || $this->serializer===false)
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return $value;
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if($this->serializer===null)
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$value=unserialize($value);
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else
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$value=call_user_func($this->serializer[1], $value);
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if(is_array($value) && (!$value[1] instanceof ICacheDependency || !$value[1]->getHasChanged()))
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{
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Yii::trace('Serving "'.$id.'" from cache','system.caching.'.get_class($this));
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return $value[0];
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}
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else
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return false;
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}
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/**
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* Retrieves multiple values from cache with the specified keys.
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* Some caches (such as memcache, apc) allow retrieving multiple cached values at one time,
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* which may improve the performance since it reduces the communication cost.
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* In case a cache does not support this feature natively, it will be simulated by this method.
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* @param array $ids list of keys identifying the cached values
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* @return array list of cached values corresponding to the specified keys. The array
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* is returned in terms of (key,value) pairs.
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* If a value is not cached or expired, the corresponding array value will be false.
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*/
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public function mget($ids)
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{
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$uids = array();
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foreach ($ids as $id)
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$uids[$id] = $this->generateUniqueKey($id);
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$values = $this->getValues($uids);
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$results = array();
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if($this->serializer === false)
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{
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foreach ($uids as $id => $uid)
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$results[$id] = isset($values[$uid]) ? $values[$uid] : false;
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}
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else
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{
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foreach($uids as $id => $uid)
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{
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$results[$id] = false;
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if(isset($values[$uid]))
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{
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$value = $this->serializer === null ? unserialize($values[$uid]) : call_user_func($this->serializer[1], $values[$uid]);
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if(is_array($value) && (!$value[1] instanceof ICacheDependency || !$value[1]->getHasChanged()))
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{
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Yii::trace('Serving "'.$id.'" from cache','system.caching.'.get_class($this));
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$results[$id] = $value[0];
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}
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}
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}
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}
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return $results;
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}
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/**
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* Stores a value identified by a key into cache.
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* If the cache already contains such a key, the existing value and
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* expiration time will be replaced with the new ones.
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*
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* @param string $id the key identifying the value to be cached
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* @param mixed $value the value to be cached
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* @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire.
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* @param ICacheDependency $dependency dependency of the cached item. If the dependency changes, the item is labeled invalid.
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* @return boolean true if the value is successfully stored into cache, false otherwise
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*/
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public function set($id,$value,$expire=0,$dependency=null)
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{
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Yii::trace('Saving "'.$id.'" to cache','system.caching.'.get_class($this));
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if ($dependency !== null && $this->serializer !== false)
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$dependency->evaluateDependency();
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if ($this->serializer === null)
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$value = serialize(array($value,$dependency));
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elseif ($this->serializer !== false)
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$value = call_user_func($this->serializer[0], array($value,$dependency));
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return $this->setValue($this->generateUniqueKey($id), $value, $expire);
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}
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/**
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* Stores a value identified by a key into cache if the cache does not contain this key.
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* Nothing will be done if the cache already contains the key.
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* @param string $id the key identifying the value to be cached
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* @param mixed $value the value to be cached
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* @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire.
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* @param ICacheDependency $dependency dependency of the cached item. If the dependency changes, the item is labeled invalid.
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* @return boolean true if the value is successfully stored into cache, false otherwise
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*/
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public function add($id,$value,$expire=0,$dependency=null)
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{
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Yii::trace('Adding "'.$id.'" to cache','system.caching.'.get_class($this));
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if ($dependency !== null && $this->serializer !== false)
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$dependency->evaluateDependency();
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if ($this->serializer === null)
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$value = serialize(array($value,$dependency));
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elseif ($this->serializer !== false)
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$value = call_user_func($this->serializer[0], array($value,$dependency));
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return $this->addValue($this->generateUniqueKey($id), $value, $expire);
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}
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/**
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* Deletes a value with the specified key from cache
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* @param string $id the key of the value to be deleted
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* @return boolean if no error happens during deletion
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*/
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public function delete($id)
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{
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Yii::trace('Deleting "'.$id.'" from cache','system.caching.'.get_class($this));
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return $this->deleteValue($this->generateUniqueKey($id));
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}
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/**
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* Deletes all values from cache.
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* Be careful of performing this operation if the cache is shared by multiple applications.
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* @return boolean whether the flush operation was successful.
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*/
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public function flush()
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{
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Yii::trace('Flushing cache','system.caching.'.get_class($this));
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return $this->flushValues();
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}
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/**
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* Retrieves a value from cache with a specified key.
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* This method should be implemented by child classes to retrieve the data
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* from specific cache storage. The uniqueness and dependency are handled
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* in {@link get()} already. So only the implementation of data retrieval
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* is needed.
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* @param string $key a unique key identifying the cached value
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* @return string|boolean the value stored in cache, false if the value is not in the cache or expired.
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* @throws CException if this method is not overridden by child classes
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*/
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protected function getValue($key)
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{
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throw new CException(Yii::t('yii','{className} does not support get() functionality.',
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array('{className}'=>get_class($this))));
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}
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/**
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* Retrieves multiple values from cache with the specified keys.
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* The default implementation simply calls {@link getValue} multiple
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* times to retrieve the cached values one by one.
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* If the underlying cache storage supports multiget, this method should
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* be overridden to exploit that feature.
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* @param array $keys a list of keys identifying the cached values
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* @return array a list of cached values indexed by the keys
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*/
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protected function getValues($keys)
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{
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$results=array();
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foreach($keys as $key)
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$results[$key]=$this->getValue($key);
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return $results;
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}
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/**
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* Stores a value identified by a key in cache.
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* This method should be implemented by child classes to store the data
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* in specific cache storage. The uniqueness and dependency are handled
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* in {@link set()} already. So only the implementation of data storage
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* is needed.
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*
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* @param string $key the key identifying the value to be cached
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* @param string $value the value to be cached
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* @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire.
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* @return boolean true if the value is successfully stored into cache, false otherwise
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* @throws CException if this method is not overridden by child classes
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*/
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protected function setValue($key,$value,$expire)
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{
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throw new CException(Yii::t('yii','{className} does not support set() functionality.',
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array('{className}'=>get_class($this))));
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}
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/**
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* Stores a value identified by a key into cache if the cache does not contain this key.
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* This method should be implemented by child classes to store the data
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* in specific cache storage. The uniqueness and dependency are handled
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* in {@link add()} already. So only the implementation of data storage
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* is needed.
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*
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* @param string $key the key identifying the value to be cached
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* @param string $value the value to be cached
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* @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire.
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* @return boolean true if the value is successfully stored into cache, false otherwise
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* @throws CException if this method is not overridden by child classes
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*/
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protected function addValue($key,$value,$expire)
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{
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throw new CException(Yii::t('yii','{className} does not support add() functionality.',
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array('{className}'=>get_class($this))));
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}
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/**
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* Deletes a value with the specified key from cache
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* This method should be implemented by child classes to delete the data from actual cache storage.
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* @param string $key the key of the value to be deleted
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* @return boolean if no error happens during deletion
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* @throws CException if this method is not overridden by child classes
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*/
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protected function deleteValue($key)
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{
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throw new CException(Yii::t('yii','{className} does not support delete() functionality.',
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array('{className}'=>get_class($this))));
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}
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/**
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* Deletes all values from cache.
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* Child classes may implement this method to realize the flush operation.
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* @return boolean whether the flush operation was successful.
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* @throws CException if this method is not overridden by child classes
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* @since 1.1.5
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*/
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protected function flushValues()
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{
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throw new CException(Yii::t('yii','{className} does not support flushValues() functionality.',
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array('{className}'=>get_class($this))));
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}
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/**
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* Returns whether there is a cache entry with a specified key.
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* This method is required by the interface ArrayAccess.
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* @param string $id a key identifying the cached value
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* @return boolean
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*/
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public function offsetExists($id)
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{
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return $this->get($id)!==false;
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}
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/**
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* Retrieves the value from cache with a specified key.
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* This method is required by the interface ArrayAccess.
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* @param string $id a key identifying the cached value
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* @return mixed the value stored in cache, false if the value is not in the cache or expired.
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*/
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public function offsetGet($id)
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{
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return $this->get($id);
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}
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/**
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* Stores the value identified by a key into cache.
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* If the cache already contains such a key, the existing value will be
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* replaced with the new ones. To add expiration and dependencies, use the set() method.
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* This method is required by the interface ArrayAccess.
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* @param string $id the key identifying the value to be cached
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* @param mixed $value the value to be cached
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*/
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public function offsetSet($id, $value)
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{
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$this->set($id, $value);
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}
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/**
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* Deletes the value with the specified key from cache
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* This method is required by the interface ArrayAccess.
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* @param string $id the key of the value to be deleted
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* @return boolean if no error happens during deletion
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*/
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public function offsetUnset($id)
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{
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$this->delete($id);
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}
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} |