presto-rcfile/src/main/java/io/prestosql/rcfile/RcFileWriter.java/RcFileWriter/flush
class RcFileWriter:            private void flush()
            {
                if (runLength > 0) {
                    int value = ~runLength;
                    writeVInt(lengthOutput, value);
                }
                previousLength = -1;
                runLength = 0;
            }