cancel method

void cancel()

取消当前执行

Implementation

void cancel() {
  _log('[CANCEL] ========== 收到取消请求 ==========');
  if (_tracker.state != PreloadManagerState.running) {
    _log('[CANCEL] 当前状态不是 running，无法取消，状态: ${_tracker.state}');
    return;
  }

  _getEngine().cancel();
  _log('[CANCEL] 状态设置为: cancelled');
}