private void putHeaderLong(int offset,
                             long value) {
    assert (0 <= offset && offset <= HeaderLayout.HEADER_SIZE - Long.BYTES)
      : "header offset(=" + offset + ") must be in [0," + (HeaderLayout.HEADER_SIZE - Long.BYTES) + "]";
    headerPage.rawPageBuffer().putLong(offset, value);
  }
private void putHeaderLong(int offset,
                             long value)