@Override
  protected E get(E element) {
    return keyedElements.get(element.getDriverTaskId());
  }
Init the queue with max capacity and specified comparator.

@see IndexedBlockingQueue
@param maxCapacity the max capacity of the queue.
@param comparator the comparator for comparing the elements.
@param queryHolder the query holder instance.
@throws IllegalArgumentException if maxCapacity <= 0.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/execution/schedule/queue/L1PriorityQueue.java