gistfile1.txt

private IEnumerable<Task> CreateHandlerTasks(IDomainEvent domainEvent)
{
    if (domainEvent == null)
    {
        return new Task[0];
    }

    Func<IDomainEvent, IEnumerable<Task>> handlerCreator;

    var type = domainEvent.GetType();

    if (CachedHandlerCreators.TryGetValue(type, out handlerCreator))
    {
        return handlerCreator(domainEvent);
    }

    var methodInfo = typeof(MultiDomainEventMessageHandler).GetMethod("CreateHandler", BindingFlags.Instance | BindingFlags.NonPublic)
        .MakeGenericMethod(type);

    handlerCreator = Expression.Lambda<Func<IDomainEvent, IEnumerable<Task>>>(
        Expression.Call(Expression.Constant(this), methodInfo)).Compile();

    CachedHandlerCreators.Add(type, handlerCreator);

    return handlerCreator(domainEvent);
}

private IEnumerable<Task> CreateHandler<T>(IDomainEvent domainEvent)
{
    var handlers = _container.GetAllInstances<Rebus.IHandleMessages<T>>();

    Action<object> a = _ =>
    {
        var handlerDomainEventPair = _ as HandlerDomainEventPair<T>;

        if (handlerDomainEventPair != null)
        {
            handlerDomainEventPair.Handler.Handle(handlerDomainEventPair.DomainEvent);
        }
    };

    return handlers.Select(handler => new Task(a, new HandlerDomainEventPair<T>(handler, (T)domainEvent)));
}