class Aws::Plugins::ChecksumAlgorithm::AwsChunkedTrailerDigestIO

def size
  # compute the number of chunks
  # a full chunk has 4 + 4 bytes overhead, a partial chunk is len.to_s(16).size + 4
  orig_body_size = @io.size
  n_full_chunks = orig_body_size / CHUNK_SIZE
  partial_bytes = orig_body_size % CHUNK_SIZE
  chunked_body_size = n_full_chunks * (CHUNK_SIZE + 8)
  chunked_body_size += partial_bytes.to_s(16).size + partial_bytes + 4 unless  partial_bytes.zero?
  trailer_size = ChecksumAlgorithm.trailer_length(@algorithm, @location_name)
  chunked_body_size + trailer_size
end