ericpai commented on a change in pull request #5294: URL: https://github.com/apache/iotdb/pull/5294#discussion_r831709408
########## File path: server/src/main/java/org/apache/iotdb/db/mpp/schedule/queue/L2PriorityQueue.java ########## @@ -0,0 +1,104 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, + * software distributed under the License is distributed on an + * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + * KIND, either express or implied. See the License for the + * specific language governing permissions and limitations + * under the License. + */ +package org.apache.iotdb.db.mpp.schedule.queue; + +import java.util.Comparator; +import java.util.SortedMap; +import java.util.TreeMap; + +/** + * An efficient subclass of {@link IndexedBlockingQueue} with 2-level priority groups. The + * advantages compared to {@link L1PriorityQueue} are that each element in this queue will not be + * starved to death by its low sequence order. + * + * <p>The time complexity of operations are: + * + * <ul> + * <li><b>{@link #remove(IDIndexedAccessible)} ()}: </b> O(logN). + * <li><b>{@link #push(IDIndexedAccessible)}: </b> O(logN). + * <li><b>{@link #poll()}: </b> O(logN). + * <li><b>{@link #get(ID)}}: </b> O(1). + * </ul> + */ +public class L2PriorityQueue<E extends IDIndexedAccessible> extends IndexedBlockingQueue<E> { + + // Here we use a map not a set to act as a queue because we need to get the element reference + // after it was removed. + private SortedMap<E, E> workingElements; + private SortedMap<E, E> idleElements; + + /** + * 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. + */ + public L2PriorityQueue(int maxCapacity, Comparator<E> comparator, E queryHolder) { + super(maxCapacity, queryHolder); + this.workingElements = new TreeMap<>(comparator); + this.idleElements = new TreeMap<>(comparator); + } + + @Override + protected boolean isEmpty() { + return workingElements.isEmpty() && idleElements.isEmpty(); + } + + @Override + protected E pollFirst() { + if (workingElements.isEmpty()) { + SortedMap<E, E> tmp = workingElements; + workingElements = idleElements; + idleElements = tmp; + } + return workingElements.remove(workingElements.firstKey()); + } + + @Override + protected void pushToQueue(E element) { + workingElements.remove(element); + idleElements.put(element, element); Review comment: Fixed with `assert`. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
