private void clearDir(File dir) {
      if (dir.exists()) {
        FileUtils.deleteFileOrDirectoryWithRetry(dir);
      }
      if (dir.mkdirs()) {
        LOGGER.info("Load TsFile dir {} is created.", dir.getPath());
      }
    }
{@link LoadTsFileManager} is used for dealing with {@link LoadTsFilePieceNode} and {@link
LoadCommand}. This class turn the content of a piece of loading TsFile into a new TsFile. When
DataNode finish transfer pieces, this class will flush all TsFile and load them into IoTDB, or
delete all.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/storageengine/load/LoadTsFileManager.java