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.fusesource.hawtdb.util;
018    
019    import java.util.HashMap;
020    import java.util.Timer;
021    import java.util.TimerTask;
022    
023    /**
024     */
025    public final class Scheduler {
026    
027        
028    
029            public static final Timer CLOCK_DAEMON = new Timer("ActiveMQ Scheduler", true);
030        private static final HashMap<Runnable, TimerTask> TIMER_TASKS = new HashMap<Runnable, TimerTask>();
031    
032        private Scheduler() {
033        }
034    
035        public static synchronized void executePeriodically(final Runnable task, long period) {
036            TimerTask timerTask = new SchedulerTimerTask(task);
037            CLOCK_DAEMON.scheduleAtFixedRate(timerTask, period, period);
038            TIMER_TASKS.put(task, timerTask);
039        }
040    
041        public static synchronized void cancel(Runnable task) {
042            TimerTask ticket = TIMER_TASKS.remove(task);
043            if (ticket != null) {
044                ticket.cancel();
045                CLOCK_DAEMON.purge();//remove cancelled TimerTasks
046            }
047        }
048    
049        public static void executeAfterDelay(final Runnable task, long redeliveryDelay) {
050            TimerTask timerTask = new SchedulerTimerTask(task);
051            CLOCK_DAEMON.schedule(timerTask, redeliveryDelay);
052        }
053        
054        public static void shutdown() {
055            CLOCK_DAEMON.cancel();
056        }
057    
058    }