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.store.kahadb.disk.util;
018
019import java.util.HashMap;
020import java.util.Timer;
021import java.util.TimerTask;
022
023/**
024 *
025 */
026public final class Scheduler {
027
028
029
030    public static final Timer CLOCK_DAEMON = new Timer("KahaDB Scheduler", true);
031    private static final HashMap<Runnable, TimerTask> TIMER_TASKS = new HashMap<Runnable, TimerTask>();
032
033    private Scheduler() {
034    }
035
036    public static synchronized void executePeriodically(final Runnable task, long period) {
037        TimerTask timerTask = new SchedulerTimerTask(task);
038        CLOCK_DAEMON.schedule(timerTask, period, period);
039        TIMER_TASKS.put(task, timerTask);
040    }
041
042    public static synchronized void cancel(Runnable task) {
043        TimerTask ticket = TIMER_TASKS.remove(task);
044        if (ticket != null) {
045            ticket.cancel();
046            CLOCK_DAEMON.purge();//remove cancelled TimerTasks
047        }
048    }
049
050    public static void executeAfterDelay(final Runnable task, long redeliveryDelay) {
051        TimerTask timerTask = new SchedulerTimerTask(task);
052        CLOCK_DAEMON.schedule(timerTask, redeliveryDelay);
053    }
054
055    public static void shutdown() {
056        CLOCK_DAEMON.cancel();
057    }
058
059}