code: /*--------------------------------------------------------------*
    Copyright (C) 2006-2015 OpenSim Ltd.
  
    This file is distributed WITHOUT ANY WARRANTY. See the file
    'License' for details on this and other legal matters.
  *--------------------------------------------------------------*/
  
  package org.omnetpp.common.util;
  
  import org.eclipse.swt.widgets.Display;
  
  /**
   * Run the given job every x milliseconds.
   */
  abstract public class RecurringJob implements Runnable {
      private int delayMillis;
  
      private Runnable internalRunnable;
  
      /**
       * Creates the object, but does not start the timer yet.
       */
      public RecurringJob(int delayMillis) {
          this.delayMillis = delayMillis;
          this.internalRunnable = new Runnable() {
              public void run() {
                  start();
                  RecurringJob.this.run();
              }
          };
      }
  
      /**
       * Starts the timer.
       */
      public void start() {
          // Alas, timerExec() may only be invoked from the UI thread
          if (Display.getCurrent() != null) {
              Display.getDefault().timerExec(-1, internalRunnable);
              Display.getDefault().timerExec(delayMillis, internalRunnable);
          }
          else {
              Display.getDefault().asyncExec(new Runnable() {
                  public void run() {
                      start(); // try again from the UI thread
                  }
              });
          }
      }
  
      /**
       * Stops the currently running timer.
       */
      public void stop() {
          // Alas, timerExec() may only be invoked from the UI thread
          if (Display.getCurrent() != null) {
              Display.getDefault().timerExec(-1, internalRunnable);
          }
          else {
              Display.getDefault().asyncExec(new Runnable() {
                  public void run() {
                      stop(); // try again from the UI thread
                  }
              });
          }
      }
  }
  