Guava EventBus: don't catch RuntimeException

Question

I use guava's EventBus, unfortunately it catches and logs the InvocationTargetException that occurs when an event-handler throws a RuntimeException. Can i disable this behaviour?

Answer 1

As it stands, this is a deliberate decision, and discussed in the EventBus docs:

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.

Alternative solutions are being considered, though I seriously doubt they'll make it into release 12.

Answer 2

Here is code for lazy

public class Events
{
    public static EventBus createWithExceptionDispatch()
    {
        final EventBus bus;

        MySubscriberExceptionHandler exceptionHandler = new MySubscriberExceptionHandler();
        bus = new EventBus(exceptionHandler);
        exceptionHandler.setBus(bus);
        return bus;
    }

    private static class MySubscriberExceptionHandler implements SubscriberExceptionHandler
    {
        @Setter
        EventBus bus;

        @Override
        public void handleException(Throwable exception, SubscriberExceptionContext context)
        {
            ExceptionEvent event = new ExceptionEvent(exception, context);
            bus.post(event);
        }
    }
}

Now, you can subscribe ExceptionEvent.

Here is my ExceptionEvent for just copy&paste

@Data
@Accessors(chain = true)
public class ExceptionEvent
{
    private final Throwable exception;
    private final SubscriberExceptionContext context;
    private final Object extra;

    public ExceptionEvent(Throwable exception)
    {
        this(exception, null);
    }

    public ExceptionEvent(Throwable exception, Object extra)
    {
        this(exception,null,extra);
    }

    public ExceptionEvent(Throwable exception, SubscriberExceptionContext context)
    {
        this(exception,context,null);
    }

    public ExceptionEvent(Throwable exception, SubscriberExceptionContext context, Object extra)
    {
        this.exception = exception;
        this.context = context;
        this.extra = extra;
    }
}