presto-benchmark/src/main/java/io/prestosql/benchmark/SimpleLineBenchmarkResultWriter.java/SimpleLineBenchmarkResultWriter/addResults
class SimpleLineBenchmarkResultWriter:    @Override
    public BenchmarkResultHook addResults(Map<String, Long> results)
    {
        requireNonNull(results, "results is null");
        try {
            Joiner.on(",").withKeyValueSeparator(":").appendTo(writer, results);
            writer.write('\n');
            writer.flush();
        }
        catch (IOException e) {
            throw new UncheckedIOException(e);
        }
        return this;
    }