cancel method

void cancel()

取消正在进行的任务

Implementation

void cancel() {
  log(_tag, 'cancel');
  if (_isCanceled) {
    log(_tag, 'work has been canceled');
    return;
  }
  if (_completer.isCompleted) {
    log(_tag, 'work finished');
    return;
  }
  _isCanceled = true;
  onCanceled();
}