private final Object lock = new Object();

    /*
     * Conceptually, these two variables describe the executor being in
     * one of three states:
     *   - Active: shutdown == false
     *   - Shutdown: runningTasks > 0 and shutdown == true
     *   - Terminated: runningTasks == 0 and shutdown == true
     */
    @GuardedBy("lock")

    public abstract Object execute(String scriptType, String script);

    public void shutdown() {
        shutdownListener.onShutdown();
    }

    public void addShutdownListener(final ShutdownListener listener) {
        shutdownListener = listener;
    }

    public interface ShutdownListener {
        void onShutdown();
    }

    assertTrue(future.isDone());

    assertTrue(successLatch.await(200, MILLISECONDS));
    assertTrue(listenerLatch.await(200, MILLISECONDS));

    latch.countDown();

    exec.shutdown();
    exec.awaitTermination(100, MILLISECONDS);
  }

  /**
   * Tests that all listeners complete, even if they were added before or after the future was

    application.addDelayedShutdownHook(service, 2, TimeUnit.SECONDS);
    verify(service, Mockito.never()).shutdown();
    application.shutdown();
    InOrder shutdownFirst = Mockito.inOrder(service);
    shutdownFirst.verify(service).shutdown();
    shutdownFirst.verify(service).awaitTermination(2, TimeUnit.SECONDS);
  }

    Request request = new Request.Builder()
        .url("ws://echo.websocket.org")
        .build();
    client.newWebSocket(request, this);

    // Trigger shutdown of the dispatcher's executor so this process exits immediately.
    client.dispatcher().executorService().shutdown();
  }

  @Override public void onOpen(WebSocket webSocket, Response response) {
    webSocket.send("Hello...");
    webSocket.send("...World!");

  public void testStop_failed() {
    final Exception exception = new Exception("deliberate");
    TestService service =
        new TestService() {
          @Override
          protected void shutDown() throws Exception {
            super.shutDown();
            throw exception;
          }
        };
    service.startAsync().awaitRunning();
    assertEquals(1, service.startUpCalled);
    assertEquals(0, service.shutDownCalled);

        this.repositorySystemProvider = requireNonNull(repositorySystemProvider);
    }

    @PreDestroy
    public void shutdown() {
        repositorySystemProvider.get().shutdown();
    }

    application.addDelayedShutdownHook(service, 2, TimeUnit.SECONDS);
    verify(service, Mockito.never()).shutdown();
    application.shutdown();
    InOrder shutdownFirst = Mockito.inOrder(service);
    shutdownFirst.verify(service).shutdown();
    shutdownFirst.verify(service).awaitTermination(2, TimeUnit.SECONDS);
  }

 * the "running" state need to perform a periodic task. Subclasses can implement {@link #startUp},
 * {@link #shutDown} and also a {@link #runOneIteration} method that will be executed periodically.
 *
 * <p>This class uses the {@link ScheduledExecutorService} returned from {@link #executor} to run
 * the {@link #startUp} and {@link #shutDown} methods and also uses that service to schedule the

              }
            }
          });
      this.shutdown = shutdown;
      start();
    }

    void shutdown() {
      shutdown.set(true);
      while (this.isAlive()) {
        Thread.yield();
      }
    }
  }

  void assertWrapsInterruptedException(RuntimeException e) {
    assertThat(e).hasMessageThat().contains("Unexpected interrupt");