private synchronized void start()

in gateway-server/src/main/java/org/apache/knox/gateway/GatewayServer.java [615:724]
69 lines of code
12 McCabe index (conditional complexity)

  private synchronized void start() throws Exception {
    // Create the global context handler.
    contexts = new ContextHandlerCollection();

     // A map to keep track of current deployments by cluster name.
    deployments = new ConcurrentHashMap<>();

    // Create Jetty.
    createJetty();

    // Add Annotations processing into the Jetty server to support JSPs
    Configuration.ClassList classlist = Configuration.ClassList.setServerDefault( jetty );
    classlist.addBefore(
        "org.eclipse.jetty.webapp.JettyWebXmlConfiguration",
        "org.eclipse.jetty.annotations.AnnotationConfiguration" );

    // Load the current topologies.
    // Redeploy autodeploy topologies.
    File topologiesDir = calculateAbsoluteTopologiesDir();
    monitor = services.getService(ServiceType.TOPOLOGY_SERVICE);

    // Shared providers and descriptors should be reloaded before topology reloading at startup, so that any changes to descriptors
    // will be realized before Knox deploys "old" topologies that would have re-deployed anyway in a matter of seconds
    // by the descriptor monitor
    handleHadoopXmlResources();

    // at this point descriptors are supposed to be generated from hxr
    gatewayStatusService = services.getService(ServiceType.GATEWAY_STATUS_SERVICE);
    gatewayStatusService.initTopologiesToCheck();

    monitor.addTopologyChangeListener(listener);
    log.loadingTopologiesFromDirectory(topologiesDir.getAbsolutePath());
    monitor.reloadTopologies();
    List<String> autoDeploys = config.getAutoDeployTopologyNames();
    if (autoDeploys != null) {
      for (String topologyName : autoDeploys) {
        monitor.redeployTopology(topologyName);
      }
    }

    final ServiceDefinitionRegistry serviceDefinitionRegistry = services.getService(ServiceType.SERVICE_DEFINITION_REGISTRY);
    serviceDefinitionRegistry.addServiceDefinitionChangeListener(monitor);

    final Map<String, Integer> topologyPortMap = config.getGatewayPortMappings();

    // List of all the topology that are deployed (or will be deployed soon)
    final Set<String> deployedTopologyList = gatewayStatusService.collectTopologies(config);

    // Check whether the configured topologies for port mapping exist, if not
    // log WARN message and continue
    checkMappedTopologiesExist(topologyPortMap, deployedTopologyList);

    final HandlerCollection handlers = createHandlers( config, services, contexts, topologyPortMap);

     // Check whether a topology wants dedicated port,
     // if yes then we create a connector that listens on the provided port.

    log.gatewayTopologyPortMappingEnabled(config.isGatewayPortMappingEnabled());
    if (config.isGatewayPortMappingEnabled()) {
      for (Map.Entry<String, Integer> entry : topologyPortMap.entrySet()) {
        // Add connector for only valid topologies, i.e. deployed topologies.
        // and NOT for Default Topology listening on standard gateway port.
        if(deployedTopologyList.contains(entry.getKey()) && (entry.getValue() != config.getGatewayPort()) ) {
          log.createJettyConnector(entry.getKey().toLowerCase(Locale.ROOT), convertPortToString(entry.getValue()));
          try {
            List<Connector> connectors = createConnector(jetty, config, entry.getValue(), entry.getKey().toLowerCase(Locale.ROOT));
            for (Connector connector : connectors) {
              jetty.addConnector(connector);
            }
          } catch(final IOException e) {
            /* in case of port conflict we log error and move on */
            if( e.toString().contains("ports for topologies (if defined) have to be unique.") ) {
              log.startedGatewayPortConflict(entry.getKey().toLowerCase(Locale.ROOT), convertPortToString(entry.getValue()));
            } else {
              throw e;
            }
          }
        }
      }
    }

    jetty.setHandler(handlers);
    jetty.addLifeCycleListener(new GatewayServerLifecycleListener(config));

    // Start Jetty.
    try {
      jetty.start();
    }
    catch (IOException e) {
      log.failedToStartGateway( e );
      throw e;
    }

    cleanupTopologyDeployments();

    // Start the topology monitor.
    monitor.startMonitor();

    Runtime.getRuntime().addShutdownHook(new Thread() {

      @Override
      public void run() {
        try {
          server.stop();
        } catch (Exception e) {
          //NOP: error is already logged in the stop() method
        }
      }
    });
  }