presto-main/src/main/java/io/prestosql/execution/executor/MultilevelSplitQueue.java/MultilevelSplitQueue/getLevelMinPriority
class MultilevelSplitQueue:    public long getLevelMinPriority(int level, long taskThreadUsageNanos)
    {
        levelMinPriority[level].compareAndSet(-1, taskThreadUsageNanos);
        return levelMinPriority[level].get();
    }