public function getCache($frontendOptions = null, $backendOptions = null, $backendName = null)
 {
     if (null === $this->_cache) {
         parent::getCache($frontendOptions, $backendOptions, $backendName);
         //Each user have his own cache
         $identity = Centurion_Auth::getInstance()->getIdentity();
         $this->_cache->setCacheSuffix(sprintf('user_%d', $identity === null ? 0 : $identity->id));
     }
     return $this->_cache;
 }