private boolean isWritingFileAvailable() {
    final boolean isWritingFileAvailable =
        writingFile != null && writingFile.exists() && writingFileWriter != null;
    if (!isWritingFileAvailable) {
      LOGGER.info(
          "Receiver id = {}: Writing file {} is not available. "
              + "Writing file is null: {}, writing file exists: {}, writing file writer is null: {}.",
          receiverId.get(),
          writingFile,
          writingFile == null,
          writingFile != null && writingFile.exists(),
          writingFileWriter == null);
    }
    return isWritingFileAvailable;
  }
{@link IoTDBFileReceiver} is the parent class of receiver on both configNode and DataNode,
handling all the logic of parallel file receiving.
iotdb-core/node-commons/src/main/java/org/apache/iotdb/commons/pipe/receiver/IoTDBFileReceiver.java