new ListenerCallQueue.Event<Listener>() {
        @Override
        public void call(Listener listener) {
          listener.stopped();
        }

        @Override
        public String toString() {
          return "stopped()";
        }
      };

  /**
   * A listener for the aggregate state changes of the services that are under management. Users

    manager.awaitStopped(5, SECONDS); // no exception thrown
  }

  /**
   * This covers a case where if the last service to stop failed then the stopped callback would
   * never be called.
   */
  public void testSingleFailedServiceCallsStopped() {
    Service a = new FailStartService();
    ServiceManager manager = new ServiceManager(asList(a));

        } catch (final ContainerNotAvailableException e) {
            if (logger.isDebugEnabled()) {
                logger.debug("SuggestCreator is stopped.", e);
            } else if (logger.isInfoEnabled()) {
                logger.info("SuggestCreator is stopped.");
            }
            exitCode = Constants.EXIT_FAIL;
        } catch (final Throwable t) {

        } catch (final ContainerNotAvailableException e) {
            if (logger.isDebugEnabled()) {
                logger.debug("ThumbnailGenerator is stopped.", e);
            } else if (logger.isInfoEnabled()) {
                logger.info("ThumbnailGenerator is stopped.");
            }
            exitCode = Constants.EXIT_FAIL;
        } catch (final Throwable t) {

   */
  @CanIgnoreReturnValue
  public Stopwatch stop() {
    long tick = ticker.read();
    checkState(isRunning, "This stopwatch is already stopped.");
    isRunning = false;
    elapsedNanos += tick - startTick;
    return this;
  }

  /**
   * Sets the elapsed time for this stopwatch to zero, and places it in a stopped state.
   *

   */
  @CanIgnoreReturnValue
  public Stopwatch stop() {
    long tick = ticker.read();
    checkState(isRunning, "This stopwatch is already stopped.");
    isRunning = false;
    elapsedNanos += tick - startTick;
    return this;
  }

  /**
   * Sets the elapsed time for this stopwatch to zero, and places it in a stopped state.
   *

      finalizeReferentCalled = true;
    }
  }

  /**
   * Keeps a weak reference to the underlying reference queue. When this reference is cleared, we
   * know that the background thread has stopped and released its strong reference.
   */
  private WeakReference<ReferenceQueue<Object>> queueReference;

  @Test
  public void testThatFinalizerStops() {
    weaklyReferenceQueue();

    manager.awaitStopped(5, SECONDS); // no exception thrown
  }

  /**
   * This covers a case where if the last service to stop failed then the stopped callback would
   * never be called.
   */
  public void testSingleFailedServiceCallsStopped() {
    Service a = new FailStartService();
    ServiceManager manager = new ServiceManager(asList(a));

        } catch (final ContainerNotAvailableException e) {
            if (logger.isDebugEnabled()) {
                logger.debug("Crawler is stopped.", e);
            } else if (logger.isInfoEnabled()) {
                logger.info("Crawler is stopped.");
            }
            exitCode = Constants.EXIT_FAIL;
        } catch (final Throwable t) {
            logger.error("Crawler terminated unexpectedly.", t);

        }

        try {
            dataIndexHelper.crawl("test-session-force-stop");
            assertTrue("Should exit quickly when force stopped", true);
        } catch (Exception e) {
            assertTrue("Force stop should handle exceptions quickly", true);
        }
    }

    @Test
    public void test_crawl_with_short_intervals() {