code: // from gee.cs.oswego.edu/home/jsr166/jsr166
  
  package jsr166tests.jtreg.util.concurrent.ThreadPoolExecutor;
  
  /*
   * Copyright 2006 Sun Microsystems, Inc.  All Rights Reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.
   *
   * This code is distributed in the hope that it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   * version 2 for more details (a copy is included in the LICENSE file that
   * accompanied this code).
   *
   * You should have received a copy of the GNU General Public License version
   * 2 along with this work; if not, write to the Free Software Foundation,
   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
   * CA 95054 USA or visit www.sun.com if you need additional information or
   * have any questions.
   */
  
  /*
   * @test
   * @bug 6362121
   * @summary Test one ScheduledThreadPoolExecutor extension scenario
   * @author Martin Buchholz
   */
  
  // based on a test kindly provided by Holger Hoffstaette <holger@wizards.de>
  
  import java.util.concurrent.*;
  import static java.util.concurrent.TimeUnit.MILLISECONDS;
  
  public class ScheduledTickleService {
  
      // We get intermittent ClassCastException if greater than 1
      // because of calls to compareTo
      private final static int concurrency = 2;
  
      // Record when tasks are done
      public final static CountDownLatch done = new CountDownLatch(concurrency);
  
      public static void realMain(String... args) throws InterruptedException {
          // our tickle service
          ScheduledExecutorService tickleService =
              new ScheduledThreadPoolExecutor(concurrency) {
                  // We override decorateTask() to return a custom
                  // RunnableScheduledFuture which explicitly removes
                  // itself from the queue after cancellation.
                  protected <V> RunnableScheduledFuture<V>
                      decorateTask(Runnable runnable,
                                   RunnableScheduledFuture<V> task) {
                      final ScheduledThreadPoolExecutor exec = this;
                      return new CustomRunnableScheduledFuture<V>(task) {
                          // delegate to wrapped task, except for:
                          public boolean cancel(boolean b) {
                              // cancel wrapped task & remove myself from the queue
                              return (task().cancel(b)
                                      && exec.remove(this));}};}};
  
          for (int i = 0; i < concurrency; i++)
              new ScheduledTickle(i, tickleService)
                  .setUpdateInterval(25, MILLISECONDS);
  
          done.await();
          tickleService.shutdown();
          pass();
      }
  
      // our Runnable
      static class ScheduledTickle implements Runnable {
          public volatile int failures = 0;
  
          // my tickle service
          private final ScheduledExecutorService service;
  
          // remember my own scheduled ticket
          private ScheduledFuture ticket = null;
  
          // remember the number of times I've been tickled
          private int numTickled = 0;
  
          // my private name
          private final String name;
  
          public ScheduledTickle(int i, ScheduledExecutorService service) {
              super();
              this.name = "Tickler-"+i;
              this.service = service;
          }
  
          // set my tickle interval; 0 to disable further tickling.
          public synchronized void setUpdateInterval(long interval,
                                                     TimeUnit unit) {
              // cancel & remove previously created ticket
              if (ticket != null) {
                  ticket.cancel(false);
                  ticket = null;
              }
  
              if (interval > 0 && ! service.isShutdown()) {
                  // requeue with new interval
                  ticket = service.scheduleAtFixedRate(this, interval,
                                                       interval, unit);
              }
          }
  
          public synchronized void run() {
              try {
                  check(numTickled < 6);
                  numTickled++;
                  System.out.println(name + ": Run " + numTickled);
  
                  // tickle 3 times and then slow down
                  if (numTickled == 3) {
                      System.out.println(name + ": slower please!");
                      this.setUpdateInterval(100, MILLISECONDS);
                  }
                  // ..but only 5 times max.
                  else if (numTickled == 5) {
                      System.out.println(name + ": OK that's enough.");
                      this.setUpdateInterval(0, MILLISECONDS);
                      ScheduledTickleService.done.countDown();
                  }
              } catch (Throwable t) { unexpected(t); }
          }
      }
  
      // This is just a generic wrapper to make up for the private ScheduledFutureTask
      static class CustomRunnableScheduledFuture<V>
          implements RunnableScheduledFuture<V> {
          // the wrapped future
          private RunnableScheduledFuture<V> task;
  
          public CustomRunnableScheduledFuture(RunnableScheduledFuture<V> task) {
              super();
              this.task = task;
          }
  
          public RunnableScheduledFuture<V> task() { return task; }
  
          // Forwarding methods
          public boolean isPeriodic()         { return task.isPeriodic(); }
          public boolean isCancelled()        { return task.isCancelled(); }
          public boolean isDone()             { return task.isDone(); }
          public boolean cancel(boolean b)    { return task.cancel(b); }
          public long getDelay(TimeUnit unit) { return task.getDelay(unit); }
          public void run()                   {        task.run(); }
  
          public V get()
              throws InterruptedException, ExecutionException {
              return task.get();
          }
  
          public V get(long timeout, TimeUnit unit)
              throws InterruptedException, ExecutionException, TimeoutException {
              return task.get(timeout, unit);
          }
  
          public int compareTo(Delayed other) {
              if (this == other)
                  return 0;
              else if (other instanceof CustomRunnableScheduledFuture)
                  return task.compareTo(((CustomRunnableScheduledFuture)other).task());
              else
                  return task.compareTo(other);
          }
      }
  
      //--------------------- Infrastructure ---------------------------
      static volatile int passed = 0, failed = 0;
      static void pass() {passed++;}
      static void fail() {failed++; Thread.dumpStack();}
      static void fail(String msg) {System.out.println(msg); fail();}
      static void unexpected(Throwable t) {failed++; t.printStackTrace();}
      static void check(boolean cond) {if (cond) pass(); else fail();}
      static void equal(Object x, Object y) {
          if (x == null ? y == null : x.equals(y)) pass();
          else fail(x + " not equal to " + y);}
      public static void main(String[] args) throws Throwable {
          try {realMain(args);} catch (Throwable t) {unexpected(t);}
          System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
          if (failed > 0) throw new AssertionError("Some tests failed");}
  }
  