Examples of com.google.common.eventbus.EventBus

com.google.common.eventbus.EventBus
Dispatches events to listeners, and provides ways for listeners to register themselves.
The EventBus allows publish-subscribe-style communication between components without requiring the components to explicitly register with one another (and thus be aware of each other). It is designed exclusively to replace traditional Java in-process event distribution using explicit registration. It is not a general-purpose publish-subscribe system, nor is it intended for interprocess communication.
Receiving Events
To receive events, an object should:
1. Expose a public method, known as the event handler, which accepts a single argument of the type of event desired;
2. Mark it with a {@link Subscribe} annotation;
3. Pass itself to an EventBus instance's {@link #register(Object)} method.
Posting Events
To post an event, simply provide the event object to the {@link #post(Object)} method. The EventBus instance will determine the typeof event and route it to all registered listeners.
Events are routed based on their type — an event will be delivered to any handler for any type to which the event is assignable. This includes implemented interfaces, all superclasses, and all interfaces implemented by superclasses.
When {@code post} is called, all registered handlers for an event are runin sequence, so handlers should be reasonably quick. If an event may trigger an extended process (such as a database load), spawn a thread or queue it for later. (For a convenient way to do this, use an {@link AsyncEventBus}.)
Handler Methods
Event handler methods must accept only one argument: the event.
Handlers should not, in general, throw. If they do, the EventBus will catch and log the exception. This is rarely the right solution for error handling and should not be relied upon; it is intended solely to help find problems during development.
The EventBus guarantees that it will not call a handler method from multiple threads simultaneously, unless the method explicitly allows it by bearing the {@link AllowConcurrentEvents} annotation. If this annotation isnot present, handler methods need not worry about being reentrant, unless also called from outside the EventBus.
Dead Events
If an event is posted, but no registered handlers can accept it, it is considered "dead." To give the system a second chance to handle dead events, they are wrapped in an instance of {@link DeadEvent} and reposted.
If a handler for a supertype of all events (such as Object) is registered, no event will ever be considered dead, and no DeadEvents will be generated. Accordingly, while DeadEvent extends {@link Object}, a handler registered to receive any Object will never receive a DeadEvent.
This class is safe for concurrent use. @author Cliff Biffle @since Guava release 10

      mockMonitor(null, null, new Function<Object, MonitorStatus>() {
         @Override
         public MonitorStatus apply(final Object input) {
            return MonitorStatus.DONE;
         }
      }, new EventBus());
   }

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      }, new EventBus());
   }


   @Test(expectedExceptions = NullPointerException.class)
   public void testCreateMonitorWithNullFunction() {
      mockMonitor(null, new Object(), null, new EventBus());
   }

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    binder.install(new PubsubEventModule());
  }


  @Override
  protected void configure() {
    final EventBus eventBus = new EventBus("TaskEvents");
    eventBus.register(new Object() {
      @Subscribe public void logDeadEvent(DeadEvent event) {
        LOG.warning("Captured dead event " + event.getEvent());
      }
    });


    bind(EventBus.class).toInstance(eventBus);


    EventSink eventSink = new EventSink() {
      @Override
      public void post(PubsubEvent event) {
        eventBus.post(event);
      }
    };
    bind(EventSink.class).toInstance(eventSink);


    // Ensure at least an empty binding is present.

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            }
        } catch (ApplicationSettingsException e) {
            e.printStackTrace();
        }
        try {
            publisher = new MonitorPublisher(new EventBus());
            BetterGfacImpl.setMonitorPublisher(publisher);
            registry = RegistryFactory.getDefaultRegistry();
            setGatewayProperties();
            BetterGfacImpl.startDaemonHandlers();
            BetterGfacImpl.startStatusUpdators(registry,zk,publisher);

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        this.registry = registry;
        this.airavataAPI = airavataAPI;
        this.airavataRegistry2 = airavataRegistry2;
        daemonHandlers = new ArrayList<ThreadedHandler>();
        activityListeners = new ArrayList<AbstractActivityListener>();
        monitorPublisher = new MonitorPublisher(new EventBus());     // This is a EventBus common for gfac
        startStatusUpdators();
        startDaemonHandlers();
    }

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    @Test
    public void testLocalProvider() throws GFacException,GFacProviderException {
        LocalDirectorySetupHandler localDirectorySetupHandler = new LocalDirectorySetupHandler();
        localDirectorySetupHandler.invoke(jobExecutionContext);
        LocalProvider localProvider = new LocalProvider();
        localProvider.setMonitorPublisher(new MonitorPublisher(new EventBus()));
        localProvider.initialize(jobExecutionContext);
        localProvider.execute(jobExecutionContext);
        localProvider.dispose(jobExecutionContext);
    }

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    private AuthenticationInfo authenticationInfo;


    public HPCPullMonitor() {
        connections = new HashMap<String, ResourceConnection>();
        this.queue = new LinkedBlockingDeque<UserMonitorData>();
        publisher = new MonitorPublisher(new EventBus());
    }

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    * Provides asynchronous {@link EventBus}.
    */
   @Provides
   @Singleton
   EventBus provideSyncEventBus(DeadEventLoggingHandler deadEventsHandler) { // NO_UCD
      EventBus syncBus = new EventBus("jclouds-sync-event-bus");
      syncBus.register(deadEventsHandler);
      return syncBus;
   }

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    }


    @Override
    protected void setUp() throws Exception {
      subscriber = createSubscriber();
      EventBus bus = new EventBus();
      bus.register(subscriber);
      bus.post(EVENT);
    }

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    // Process test classes and resources.
    long start = System.currentTimeMillis();    
    final List<String> testClassNames = processTestResources();


    final EventBus aggregatedBus = new EventBus("aggregated");
    final TestsSummaryEventListener summaryListener = new TestsSummaryEventListener();
    aggregatedBus.register(summaryListener);
    
    for (Object o : listeners) {
      if (o instanceof ProjectComponent) {
        ((ProjectComponent) o).setProject(getProject());
      }
      if (o instanceof AggregatedEventListener) {
        ((AggregatedEventListener) o).setOuter(this);
      }
      aggregatedBus.register(o);
    }


    if (testClassNames.isEmpty()) {
      aggregatedBus.post(new AggregatedQuitEvent());
    } else {
      start = System.currentTimeMillis();
      
      final int slaveCount = determineSlaveCount(testClassNames.size());
      final List<SlaveInfo> slaveInfos = Lists.newArrayList();
      for (int slave = 0; slave < slaveCount; slave++) {
        final SlaveInfo slaveInfo = new SlaveInfo(slave, slaveCount);
        slaveInfos.add(slaveInfo);
      }


      // Order test class names identically for balancers.
      Collections.sort(testClassNames);
      
      // Prepare a pool of suites dynamically dispatched to slaves as they become idle.
      final Deque<String> stealingQueue = 
          new ArrayDeque<String>(loadBalanceSuites(slaveInfos, testClassNames, balancers));
      aggregatedBus.register(new Object() {
        @Subscribe @SuppressWarnings("unused")
        public void onSlaveIdle(SlaveIdle slave) {
          if (stealingQueue.isEmpty()) {
            slave.finished();
          } else {
            String suiteName = stealingQueue.pop();
            slave.newSuite(suiteName);
          }
        }
      });


      // Create callables for the executor.
      final List<Callable<Void>> slaves = Lists.newArrayList();
      for (int slave = 0; slave < slaveCount; slave++) {
        final SlaveInfo slaveInfo = slaveInfos.get(slave);
        slaves.add(new Callable<Void>() {
          @Override
          public Void call() throws Exception {
            executeSlave(slaveInfo, aggregatedBus);
            return null;
          }
        });
      }


      ExecutorService executor = Executors.newCachedThreadPool();
      aggregatedBus.post(new AggregatedStartEvent(slaves.size(), testClassNames.size()));


      try {
        List<Future<Void>> all = executor.invokeAll(slaves);
        executor.shutdown();


        for (int i = 0; i < slaves.size(); i++) {
          Future<Void> f = all.get(i);
          try {
            f.get();
          } catch (ExecutionException e) {
            slaveInfos.get(i).executionError = e.getCause();
          }
        }
      } catch (InterruptedException e) {
        log("Master interrupted? Weird.", Project.MSG_ERR);
      }
      aggregatedBus.post(new AggregatedQuitEvent());


      for (SlaveInfo si : slaveInfos) {
        if (si.start > 0 && si.end > 0) {
          log(String.format(Locale.ENGLISH, "JVM J%d: %8.2f .. %8.2f = %8.2fs",
              si.id,

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Examples of com.google.common.eventbus.EventBus

Receiving Events

Posting Events

Handler Methods

Dead Events

Related Classes of com.google.common.eventbus.EventBus