CCache

Property Details

hashKey property (available since v1.1.11)

public boolean $hashKey;

whether to md5-hash the cache key for normalization purposes. Defaults to true. Setting this property to false makes sure the cache key will not be tampered when calling the relevant methods get(), set(), add() and delete(). This is useful if a Yii application as well as an external application need to access the same cache pool (also see description of keyPrefix regarding this use case). However, without normalization you should make sure the affected cache backend does support the structure (charset, length, etc.) of all the provided cache keys, otherwise there might be unexpected behavior.

keyPrefix property

public string $keyPrefix;

a string prefixed to every cache key so that it is unique. Defaults to null which means to use the application ID. If different applications need to access the same pool of cached data, the same prefix should be set for each of the applications explicitly.

serializer property

public array|boolean $serializer;

the functions used to serialize and unserialize cached data. Defaults to null, meaning using the default PHP `serialize()` and `unserialize()` functions. If you want to use some more efficient serializer (e.g. igbinary), you may configure this property with a two-element array. The first element specifies the serialization function, and the second the deserialization function. If this property is set false, data will be directly sent to and retrieved from the underlying cache component without any serialization or deserialization. You should not turn off serialization if you are using cache dependency, because it relies on data serialization.

Method Details

add() method

public boolean add(string $id, mixed $value, integer $expire=0, ICacheDependency $dependency=NULL)

public function add($id,$value,$expire=0,$dependency=null)
{
    Yii::trace('Adding "'.$id.'" to cache','system.caching.'.get_class($this));

    if ($dependency !== null && $this->serializer !== false)
        $dependency->evaluateDependency();

    if ($this->serializer === null)
        $value = serialize(array($value,$dependency));
    elseif ($this->serializer !== false)
        $value = call_user_func($this->serializer[0], array($value,$dependency));

    return $this->addValue($this->generateUniqueKey($id), $value, $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.

addValue() method

protected boolean addValue(string $key, string $value, integer $expire)

protected function addValue($key,$value,$expire)
{
    throw new CException(Yii::t('yii','{className} does not support add() functionality.',
        array('{className}'=>get_class($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 add() already. So only the implementation of data storage is needed.

delete() method

public boolean delete(string $id)

public function delete($id)
{
    Yii::trace('Deleting "'.$id.'" from cache','system.caching.'.get_class($this));
    return $this->deleteValue($this->generateUniqueKey($id));
}

Deletes a value with the specified key from cache

deleteValue() method

protected boolean deleteValue(string $key)

protected function deleteValue($key)
{
    throw new CException(Yii::t('yii','{className} does not support delete() functionality.',
        array('{className}'=>get_class($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.

flush() method

public boolean flush()

public function flush()
{
    Yii::trace('Flushing cache','system.caching.'.get_class($this));
    return $this->flushValues();
}

Deletes all values from cache. Be careful of performing this operation if the cache is shared by multiple applications.

flushValues() method (available since v1.1.5)

protected boolean flushValues()

protected function flushValues()
{
    throw new CException(Yii::t('yii','{className} does not support flushValues() functionality.',
        array('{className}'=>get_class($this))));
}

Deletes all values from cache. Child classes may implement this method to realize the flush operation.

generateUniqueKey() method

protected string generateUniqueKey(string $key)

protected function generateUniqueKey($key)
{
    return $this->hashKey ? md5($this->keyPrefix.$key) : $this->keyPrefix.$key;
}

get() method

public mixed get(string $id)

public function get($id)
{
    $value = $this->getValue($this->generateUniqueKey($id));
    if($value===false || $this->serializer===false)
        return $value;
    if($this->serializer===null)
        $value=unserialize($value);
    else
        $value=call_user_func($this->serializer[1], $value);
    if(is_array($value) && (!$value[1] instanceof ICacheDependency || !$value[1]->getHasChanged()))
    {
        Yii::trace('Serving "'.$id.'" from cache','system.caching.'.get_class($this));
        return $value[0];
    }
    else
        return false;
}

Retrieves a value from cache with a specified key.

getValue() method

protected string|boolean getValue(string $key)

protected function getValue($key)
{
    throw new CException(Yii::t('yii','{className} does not support get() functionality.',
        array('{className}'=>get_class($this))));
}

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 get() already. So only the implementation of data retrieval is needed.

getValues() method

protected array getValues(array $keys)

protected function getValues($keys)
{
    $results=array();
    foreach($keys as $key)
        $results[$key]=$this->getValue($key);
    return $results;
}

Retrieves multiple values from cache with the specified keys. The default implementation simply calls 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.

init() method

public void init()

public function init()
{
    parent::init();
    if($this->keyPrefix===null)
        $this->keyPrefix=Yii::app()->getId();
}

Initializes the application component. This method overrides the parent implementation by setting default cache key prefix.

mget() method

public array mget(array $ids)

public function mget($ids)
{
    $uids = array();
    foreach ($ids as $id)
        $uids[$id] = $this->generateUniqueKey($id);

    $values = $this->getValues($uids);
    $results = array();
    if($this->serializer === false)
    {
        foreach ($uids as $id => $uid)
            $results[$id] = isset($values[$uid]) ? $values[$uid] : false;
    }
    else
    {
        foreach($uids as $id => $uid)
        {
            $results[$id] = false;
            if(isset($values[$uid]))
            {
                $value = $this->serializer === null ? unserialize($values[$uid]) : call_user_func($this->serializer[1], $values[$uid]);
                if(is_array($value) && (!$value[1] instanceof ICacheDependency || !$value[1]->getHasChanged()))
                {
                    Yii::trace('Serving "'.$id.'" from cache','system.caching.'.get_class($this));
                    $results[$id] = $value[0];
                }
            }
        }
    }
    return $results;
}

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 does not support this feature natively, it will be simulated by this method.

offsetExists() method

public boolean offsetExists(string $id)

public function offsetExists($id)
{
    return $this->get($id)!==false;
}

Returns whether there is a cache entry with a specified key. This method is required by the interface ArrayAccess.

offsetGet() method

public mixed offsetGet(string $id)

public function offsetGet($id)
{
    return $this->get($id);
}

Retrieves the value from cache with a specified key. This method is required by the interface ArrayAccess.

offsetSet() method

public void offsetSet(string $id, mixed $value)

public function offsetSet($id, $value)
{
    $this->set($id, $value);
}

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.

offsetUnset() method

public boolean offsetUnset(string $id)

public function offsetUnset($id)
{
    $this->delete($id);
}

Deletes the value with the specified key from cache This method is required by the interface ArrayAccess.

set() method

public boolean set(string $id, mixed $value, integer $expire=0, ICacheDependency $dependency=NULL)

public function set($id,$value,$expire=0,$dependency=null)
{
    Yii::trace('Saving "'.$id.'" to cache','system.caching.'.get_class($this));

    if ($dependency !== null && $this->serializer !== false)
        $dependency->evaluateDependency();

    if ($this->serializer === null)
        $value = serialize(array($value,$dependency));
    elseif ($this->serializer !== false)
        $value = call_user_func($this->serializer[0], array($value,$dependency));

    return $this->setValue($this->generateUniqueKey($id), $value, $expire);
}

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.

setValue() method

protected boolean setValue(string $key, string $value, integer $expire)

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 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 set() already. So only the implementation of data storage is needed.