code: public void onCancel() {
      mSerializingExecutor.execute(() -> {
        try {
          cancelRequest(mContext);
          replyCancel();
        } catch (Exception e) {
          LogUtils.warnWithException(LOG, "Exception occurred while cancelling write request {}.",
              mContext.getRequest(), e);
          Throwables.throwIfUnchecked(e);
          abort(new Error(AlluxioStatusException.fromCheckedException(e), true));
        }
      });
    }
docs: Handles request cancellation event.