presto-main/src/main/java/io/prestosql/execution/QueryIdGenerator.java/QueryIdGenerator/nowInMillis
class QueryIdGenerator:    @VisibleForTesting
    protected long nowInMillis()
    {
        // avoid problems with the clock moving backwards
        return BASE_SYSTEM_TIME_MILLIS + TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - BASE_NANO_TIME);
    }