presto-main/src/main/java/io/prestosql/execution/executor/PrioritizedSplitRunner.java/PrioritizedSplitRunner/updateLevelPriority
class PrioritizedSplitRunner:    public boolean updateLevelPriority()
    {
        Priority newPriority = taskHandle.getPriority();
        Priority oldPriority = priority.getAndSet(newPriority);
        return newPriority.getLevel() != oldPriority.getLevel();
    }