private void removeFromListAndUnlock(LlapCacheableBuffer buffer) {
    try {
      if (buffer.indexInHeap != LlapCacheableBuffer.IN_LIST) {
        return;
      }
      removeFromListUnderLock(buffer);
    } finally {
      listLock.unlock();
    }
  }
Moves the minimum child of targetPos block up to targetPos; optionally compares priorities
and terminates if targetPos element has lesser value than either of its children.
@return the index of the child that was moved up; -1 if nothing was moved due to absence
        of the children, or a failed priority check.
llap-server/src/java/org/apache/hadoop/hive/llap/cache/LowLevelLrfuCachePolicy.java