code: public function init()
      {
          parent::init();
          $this->redis = Instance::ensure($this->redis, Connection::className());
          if ($this->keyPrefix === null) {
              $this->keyPrefix = substr(md5(Yii::$app->id), 0, 5);
          }
      }
docs: Initializes the redis Mutex component.
  This method will initialize the [[redis]] property to make sure it refers to a valid redis connection.
  @throws InvalidConfigException if [[redis]] is invalid.