/**
* @brief Delete the item from cache.
* For all intents and purposes this is the same as setting the expiry date
* to before now.
* @return TRUE on success, FALSE if the item never existed in the cache.
*/
public function delete()
{
// update the isHit cache
$this->isHit = false;
// handle through the pool implementation
return $this->pool->getAdapter()->delete($this->getKey());
}