001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.camel.bam;
018
019 import org.apache.camel.bam.model.TimerEvent;
020 import org.apache.camel.impl.ServiceSupport;
021 import org.apache.commons.logging.Log;
022 import org.apache.commons.logging.LogFactory;
023 import org.springframework.orm.jpa.JpaCallback;
024 import org.springframework.orm.jpa.JpaTemplate;
025
026 import javax.persistence.EntityManager;
027 import javax.persistence.LockModeType;
028 import javax.persistence.PersistenceException;
029 import java.util.Date;
030 import java.util.List;
031 import java.util.concurrent.ExecutorService;
032
033 /**
034 * @version $Revision: $
035 */
036 public class TimerEngine extends ServiceSupport implements Runnable {
037 private static final Log log = LogFactory.getLog(TimerEngine.class);
038
039 private JpaTemplate template;
040 private ExecutorService executor;
041 private long windowMillis = 1000L;
042 private Thread thread;
043
044 public void run() {
045 while (!isStopped()) {
046 long nextPoll = System.currentTimeMillis() + windowMillis;
047
048 Date window = new Date(nextPoll);
049 List<TimerEvent> list = template.find("select x from " + TimerEvent.class.getName() + " where x.time < ?1 order by x.time", window);
050 for (TimerEvent event : list) {
051 fireEvent(event);
052 }
053
054 long timeToSleep = nextPoll - System.currentTimeMillis();
055 if (timeToSleep > 0) {
056 log.debug("Sleeping for " + timeToSleep + " millis");
057 try {
058 Thread.sleep(timeToSleep);
059 }
060 catch (InterruptedException e) {
061 log.debug("Caught: " + e, e);
062 }
063 }
064 }
065 }
066
067 protected void fireEvent(final TimerEvent event) {
068 // lets try lock the object first
069
070 template.execute(new JpaCallback() {
071 public Object doInJpa(EntityManager entityManager) throws PersistenceException {
072 entityManager.lock(event, LockModeType.WRITE);
073 event.fire();
074 entityManager.remove(event);
075 return null;
076 }
077 });
078
079 }
080
081 protected void doStart() throws Exception {
082 thread = new Thread(this, "TimerEngine");
083 thread.start();
084 }
085
086 protected void doStop() throws Exception {
087 if (thread != null) {
088 thread = null;
089 }
090 }
091 }