* Wait for a given replica DB to catch up to the master pos stored in $this
* @param int $index Server index
* @param bool $open Check the server even if a new connection has to be made
- * @param int $timeout Max seconds to wait; default is "waitTimeout" given to __construct()
+ * @param int|null $timeout Max seconds to wait; default is "waitTimeout" given to __construct()
* @return bool
*/
protected function doWait( $index, $open = false, $timeout = null ) {