clear method

void clear()

清空队列

Implementation

void clear() {
  for (final request in _pendingQueue) {
    if (!request.isCancelled) {
      request.isCancelled = true;
      request.completer.completeError(Exception('Queue cleared'));
    }
  }
  _cancelledCount += _pendingQueue.length;
  _pendingQueue.clear();
  _notifyQueueChange();
}