protected final void doMain()

in twill-yarn/src/main/java/org/apache/twill/internal/ServiceMain.java [74:123]
41 lines of code
6 McCabe index (conditional complexity)

  protected final void doMain(final Service mainService,
                              Service...prerequisites) throws ExecutionException, InterruptedException {
    configureLogger();

    Service requiredServices = new CompositeService(prerequisites);
    Runtime.getRuntime().addShutdownHook(new Thread() {
      @Override
      public void run() {
        mainService.stopAndWait();
      }
    });

    // Listener for state changes of the service
    ListenableFuture<Service.State> completion = Services.getCompletionFuture(mainService);
    Throwable initFailure = null;

    try {
      try {
        // Starts the service
        LOG.info("Starting service {}.", mainService);
        Futures.allAsList(Services.chainStart(requiredServices, mainService).get()).get();
        LOG.info("Service {} started.", mainService);
      } catch (Throwable t) {
        LOG.error("Exception when starting service {}.", mainService, t);
        initFailure = t;
      }

      try {
        if (initFailure == null) {
          completion.get();
          LOG.info("Service {} completed.", mainService);
        }
      } catch (Throwable t) {
        LOG.error("Exception thrown from service {}.", mainService, t);
        throw Throwables.propagate(t);
      }
    } finally {
      requiredServices.stopAndWait();

      ILoggerFactory loggerFactory = LoggerFactory.getILoggerFactory();
      if (loggerFactory instanceof LoggerContext) {
        ((LoggerContext) loggerFactory).stop();
      }

      if (initFailure != null) {
        // Exit with the init fail exit code.
        System.exit(ContainerExitCodes.INIT_FAILED);
      }
    }
  }