# File lib/innodb/lsn.rb, line 35
  def delta(length)
    fragment = (@lsn_no % LOG_BLOCK_SIZE) - LOG_BLOCK_HEADER_SIZE
    raise "Invalid fragment #{fragment} for LSN #{@lsn_no}" unless
      fragment.between?(0, LOG_BLOCK_DATA_SIZE - 1)
    length + (fragment + length) / LOG_BLOCK_DATA_SIZE * LOG_BLOCK_FRAME_SIZE
  end