@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
		throws ServletException, IOException {

	logger.info("module start");
	LifecycleManager.getInstance().setShutdownHook(this);
	// ModulesService modulesApi =
	// ModulesServiceFactory.getModulesService();
	// if ("0".equals(modulesApi.getCurrentInstanceId())) {
	//
	// logger.info("module start");
	// LifecycleManager.getInstance().setShutdownHook(this);
	//
	// }

	return;
}
 

private void doHang(HttpServletResponse res) throws IOException {
  res.setContentType("text/plain");
  res.getWriter().println("Starting...");
  final Thread requestThread = Thread.currentThread();
  final boolean[] hookState = new boolean[] {false, false};
  LifecycleManager.getInstance()
      .setShutdownHook(
          new LifecycleManager.ShutdownHook() {
            public void shutdown() {
              hookState[0] = true; // Hook called
              LifecycleManager.getInstance().interruptAllRequests();
              hookState[1] = true;
            }
          });
  hang();
  res.getWriter().println("Hook: " + hookState[0] + " " + hookState[1]);
  res.getWriter().println("Exiting.");
}
 

@Override
public void service(HttpServletRequest request, HttpServletResponse response) throws IOException {
  // Check if the instance is shutting down, in that case return unhealthy (lameduck).
  LifecycleManager lifeCycleManager = LifecycleManager.getInstance();
  if (LifecycleManager.getInstance().isShuttingDown()) {
     long remainingShutdownTime = lifeCycleManager.getRemainingShutdownTime();
     response.sendError(HttpServletResponse.SC_BAD_GATEWAY,
                        "App is shutting down, time remaining: " + remainingShutdownTime + " ms");
     return;
  }
  String expectedVersion = request.getParameter("VersionID");
  String actualVersion = fullVersionId();
  if ((expectedVersion == null) || expectedVersion.equals(actualVersion)){
    response.setContentType("text/plain");
    response.getWriter().write("ok");
  } else {
    response.setContentType("text/plain");
    response.getWriter().write(
        String.format("version mismatch \"%s\" != \"%s\"", expectedVersion, actualVersion));
  }
}
 

private void doPolling() {
  Queue notificationQueue = QueueFactory.getQueue("notification-delivery");

  Worker worker = new Worker(notificationQueue);
  while (!LifecycleManager.getInstance().isShuttingDown()) {
    boolean tasksProcessed = worker.processBatchOfTasks();
    ApiProxy.flushLogs();

    if (!tasksProcessed) {
      // Wait before trying to lease tasks again.
      try {
        Thread.sleep(MILLISECONDS_TO_WAIT_WHEN_NO_TASKS_LEASED);
      } catch (InterruptedException e) {
        return;
      }
    }
  }

  log.info("Instance is shutting down");
}
 

private void doPolling() {
  Queue notificationQueue = QueueFactory.getQueue("notification-delivery");

  Worker worker = new Worker(notificationQueue);
  while (!LifecycleManager.getInstance().isShuttingDown()) {
    boolean tasksProcessed = worker.processBatchOfTasks();
    ApiProxy.flushLogs();

    if (!tasksProcessed) {
      // Wait before trying to lease tasks again.
      try {
        Thread.sleep(MILLISECONDS_TO_WAIT_WHEN_NO_TASKS_LEASED);
      } catch (InterruptedException e) {
        return;
      }
    }
  }

  log.info("Instance is shutting down");
}
 

private void doPolling() {
  Queue notificationQueue = QueueFactory.getQueue("notification-delivery");

  PushNotificationWorker worker = new PushNotificationWorker(notificationQueue);
  while (!LifecycleManager.getInstance().isShuttingDown()) {
    boolean tasksProcessed = worker.processBatchOfTasks();
    ApiProxy.flushLogs();

    if (!tasksProcessed) {
      // Wait before trying to lease tasks again.
      try {
        Thread.sleep(MILLISECONDS_TO_WAIT_WHEN_NO_TASKS_LEASED);
      } catch (InterruptedException e) {
        return;
      }
    }
  }

  log.info("Instance is shutting down");
}
 

public void hang() {
  LifecycleManager runtime = LifecycleManager.getInstance();
  log.info("Shutting down: " + runtime.isShuttingDown());
  while (!runtime.isShuttingDown()) {
    try {
      log.info("Sleeping for 10s");
      Thread.sleep(10000);
    } catch (InterruptedException ex) {
      // expected
    }
    log.info("Shutting down: " + runtime.isShuttingDown());
  }
}
 

private void doHello(HttpServletResponse res) throws IOException {
  log.info("Hello!");
  LifecycleManager.getInstance()
      .setShutdownHook(
          new LifecycleManager.ShutdownHook() {
            public void shutdown() {
              log.info("Goodbye, world!");
              LifecycleManager.getInstance().interruptAllRequests();
              if (Thread.interrupted()) {
                log.info("Interrupted");
              }
            }
          });
  res.getWriter().println("Hello, world!");
}
 

@Override
public void service(HttpServletRequest req, HttpServletResponse res) {
  CountServlet.localCount.getAndAdd(datastoreCount());
  final Key key = KeyFactory.createKey("Counter", getKeyName());
  LifecycleManager.getInstance()
      .setShutdownHook(
          new ShutdownHook() {
            @Override
            public void shutdown() {
              datastoreSave(key);
            }
          });
}
 

/**
 * Handle stop requests.
 *
 * Stop requests are intercepted by this filter and never forwarded to user code.
 */
@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
    throws IOException, ServletException {
  // Requests to /_ah/stop are filtered by the appserver (and soon VM-local nginx). Any stop
  // requests that make it here are from trusted code.
  logger.info("Running shutdown hook");
  long deadline = System.currentTimeMillis() + SHUTDOWN_HOOK_DEADLINE_MILLIS;
  LifecycleManager.getInstance().beginShutdown(deadline);

  response.setContentType("text/plain");
  response.getWriter().write("ok");
}
 

public void registerShutdownHook() {
    LifecycleManager.getInstance().setShutdownHook(new ShutdownHook() {
        public void shutdown() {
            logger.info("App will stop");
            ProcessingQueue.getInstance().setShutdown();
        }
    });
}