001/**
002 * Copyright 2005-2017 The Kuali Foundation
003 *
004 * Licensed under the Educational Community License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.opensource.org/licenses/ecl2.php
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016package org.kuali.rice.ksb.messaging.threadpool;
017
018import org.kuali.rice.ksb.messaging.MessageServiceInvoker;
019import org.kuali.rice.ksb.messaging.PersistedMessageBO;
020
021import java.util.Comparator;
022import java.util.concurrent.PriorityBlockingQueue;
023
024/**
025 * A comparator to put into the {@link PriorityBlockingQueue} used in the {@link KSBThreadPoolImpl}.
026 * 
027 *  Determines execution order by priority and create date.
028 * 
029 * @author Kuali Rice Team (rice.collab@kuali.org)
030 *
031 */
032public class PriorityBlockingQueuePersistedMessageComparator implements Comparator {
033
034    
035    public int compare(Object arg0, Object arg1) {
036        if (! (arg0 instanceof MessageServiceInvoker) || ! (arg1 instanceof MessageServiceInvoker) ) {
037            return 0;
038        }
039        PersistedMessageBO message0 = ((MessageServiceInvoker)arg0).getMessage();
040        PersistedMessageBO message1 = ((MessageServiceInvoker)arg1).getMessage();
041        
042        if (message0.getQueuePriority() < message1.getQueuePriority()) {
043            return -1;
044        } else if (message0.getQueuePriority() > message1.getQueuePriority()) {
045            return 1;
046        }
047        
048        if (message0.getQueueDate().before(message1.getQueueDate())) {
049            return -1;
050        } else if (message0.getQueueDate().after(message1.getQueueDate())) {
051            return 1;
052        }
053        
054        return 0;
055    }
056
057}