presto-rcfile/src/main/java/io/prestosql/rcfile/binary/DoubleEncoding.java/DoubleEncoding/encodeColumn
class DoubleEncoding:    @Override
    public void encodeColumn(Block block, SliceOutput output, EncodeOutput encodeOutput)
    {
        for (int position = 0; position < block.getPositionCount(); position++) {
            if (!block.isNull(position)) {
                encodeValueInto(block, position, output);
            }
            encodeOutput.closeEntry();
        }
    }