private function connect()
 {
     $this->redis = new \Redis();
     $success = $this->redis->connect($this->host, $this->port, $this->timeout, null, 100);
     if ($success && !empty($this->password)) {
         $success = $this->redis->auth($this->password);
     }
     if (!empty($this->database) || 0 === $this->database) {
         $this->redis->select($this->database);
     }
     return $success;
 }