dispose method

@override Future<void> dispose()

Disposes object, stopping polling.

Future returned by start will be completed after this.

Implementation

@override
Future<void> dispose() {
  assert(!_disposed, 'Poller#$debugLabel was disposed.');
  _disposed = true;
  if (_alive) {
    _alive = false;
    return _loopExitConfirmation.future;
  } else {
    return Future.value();
  }
}