code: public static void persistAndWait(final FileSystem fs, final AlluxioURI uri)
        throws FileDoesNotExistException, IOException, AlluxioException, TimeoutException,
        InterruptedException {
      persistAndWait(fs, uri, -1);
    }
docs: Convenience method for {@code #persistAndWait(fs, uri, -1)}. i.e. wait for an indefinite period
  of time to persist. This will block for an indefinite period of time if the path is never
  persisted. Use with care.
  
  @param fs {@link FileSystem} to carry out Alluxio operations
  @param uri the uri of the file to persist