presto-main/src/main/java/io/prestosql/execution/executor/MultilevelSplitQueue.java/MultilevelSplitQueue/getLevel0TargetTime
class MultilevelSplitQueue:    @GuardedBy("lock")
    private long getLevel0TargetTime()
    {
        long level0TargetTime = levelScheduledTime[0].get();
        double currentMultiplier = levelTimeMultiplier;

        for (int level = 0; level < LEVEL_THRESHOLD_SECONDS.length; level++) {
            currentMultiplier /= levelTimeMultiplier;
            long levelTime = levelScheduledTime[level].get();
            level0TargetTime = Math.max(level0TargetTime, (long) (levelTime / currentMultiplier));
        }

        return level0TargetTime;
    }