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; 022 023import org.apache.activemq.util.ServiceStopper; 024import org.apache.activemq.util.ServiceSupport; 025import org.slf4j.Logger; 026import org.slf4j.LoggerFactory; 027 028/** 029 * 030 */ 031public final class Scheduler extends ServiceSupport { 032 033 private static final Logger LOG = LoggerFactory.getLogger(Scheduler.class); 034 private final String name; 035 private Timer timer; 036 private final HashMap<Runnable, TimerTask> timerTasks = new HashMap<Runnable, TimerTask>(); 037 038 public Scheduler(String name) { 039 this.name = name; 040 } 041 042 public synchronized void executePeriodically(final Runnable task, long period) { 043 TimerTask existing = timerTasks.get(task); 044 if (existing != null) { 045 LOG.debug("Task {} already scheduled, cancelling and rescheduling", task); 046 cancel(task); 047 } 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 @Override 076 protected synchronized void doStop(ServiceStopper stopper) throws Exception { 077 if (this.timer != null) { 078 this.timer.cancel(); 079 } 080 } 081 082 public String getName() { 083 return name; 084 } 085}