code: func (p *Process) nodeXLogPosition(dsn *DSN) (xlog.Position, error) {
  	db, err := sql.Open("mysql", dsn.String())
  	if err != nil {
  		return p.XLog().Zero(), err
  	}
  	defer db.Close()
  
  	var gtid string
  	if err := db.QueryRow(`SELECT @@gtid_current_pos`).Scan(&gtid); err != nil {
  		return p.XLog().Zero(), err
  	}
  	return xlog.Position(gtid), nil
  
  }
docs: // XLogPosition returns the current XLogPosition of node specified by DSN.