content: /**
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You under the Apache License, Version 2.0
   * (the "License"); you may not use this file except in compliance with
   * the License.  You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.activemq.store.kahadb.disk.util;
  
  import java.util.HashMap;
  import java.util.Timer;
  import java.util.TimerTask;
  
  /**
   *
   */
  public final class Scheduler {
  
  
  
      public static final Timer CLOCK_DAEMON = new Timer("KahaDB Scheduler", true);
      private static final HashMap<Runnable, TimerTask> TIMER_TASKS = new HashMap<Runnable, TimerTask>();
  
      private Scheduler() {
      }
  
      public static synchronized void executePeriodically(final Runnable task, long period) {
          TimerTask timerTask = new SchedulerTimerTask(task);
          CLOCK_DAEMON.schedule(timerTask, period, period);
          TIMER_TASKS.put(task, timerTask);
      }
  
      public static synchronized void cancel(Runnable task) {
          TimerTask ticket = TIMER_TASKS.remove(task);
          if (ticket != null) {
              ticket.cancel();
              CLOCK_DAEMON.purge();//remove cancelled TimerTasks
          }
      }
  
      public static void executeAfterDelay(final Runnable task, long redeliveryDelay) {
          TimerTask timerTask = new SchedulerTimerTask(task);
          CLOCK_DAEMON.schedule(timerTask, redeliveryDelay);
      }
  
      public static void shutdown() {
          CLOCK_DAEMON.cancel();
      }
  
  }
  