}

    Closer closer = Closer.create();
    try {
      Reader reader = closer.register(openStream());
      return countBySkipping(reader);
    } catch (Throwable e) {
      throw closer.rethrow(e);
    } finally {
      closer.close();
    }
  }

  private long countBySkipping(Reader reader) throws IOException {
    long count = 0;
    long read;
    while ((read = reader.skip(Long.MAX_VALUE)) != 0) {

    if (sizeIfKnown.isPresent()) {
      return sizeIfKnown.get();
    }

    Closer closer = Closer.create();
    try {
      InputStream in = closer.register(openStream());
      return countBySkipping(in);
    } catch (IOException e) {
      // skip may not be supported... at any rate, try reading
    } finally {
      closer.close();
    }

    closer = Closer.create();
    try {