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 */
017package org.apache.activemq.thread;
018
019import java.util.HashMap;
020import java.util.Timer;
021import java.util.TimerTask;
022import org.apache.activemq.util.ServiceStopper;
023import org.apache.activemq.util.ServiceSupport;
024
025/**
026 *
027 */
028public final class Scheduler extends ServiceSupport {
029    private final String name;
030    private Timer timer;
031    private final HashMap<Runnable, TimerTask> timerTasks = new HashMap<Runnable, TimerTask>();
032
033    public Scheduler (String name) {
034        this.name = name;
035    }
036
037    public void executePeriodically(final Runnable task, long period) {
038        TimerTask timerTask = new SchedulerTimerTask(task);
039        timer.schedule(timerTask, period, period);
040        timerTasks.put(task, timerTask);
041    }
042
043    /*
044     * execute on rough schedule based on termination of last execution. There is no
045     * compensation (two runs in quick succession) for delays
046     */
047    public synchronized void schedualPeriodically(final Runnable task, long period) {
048        TimerTask timerTask = new SchedulerTimerTask(task);
049        timer.schedule(timerTask, period, period);
050        timerTasks.put(task, timerTask);
051    }
052
053    public synchronized void cancel(Runnable task) {
054        TimerTask ticket = timerTasks.remove(task);
055        if (ticket != null) {
056            ticket.cancel();
057            timer.purge();//remove cancelled TimerTasks
058        }
059    }
060
061    public synchronized void executeAfterDelay(final Runnable task, long redeliveryDelay) {
062        TimerTask timerTask = new SchedulerTimerTask(task);
063        timer.schedule(timerTask, redeliveryDelay);
064    }
065
066    public void shutdown() {
067        timer.cancel();
068    }
069
070    @Override
071    protected synchronized void doStart() throws Exception {
072        this.timer = new Timer(name, true);
073
074    }
075
076    @Override
077    protected synchronized void doStop(ServiceStopper stopper) throws Exception {
078       if (this.timer != null) {
079           this.timer.cancel();
080       }
081
082    }
083
084    public String getName() {
085        return name;
086    }
087}