With Rx, how do I ignore all-except-the-latest value when my Subscribe method is running

Question

Using Reactive Extensions, I want to ignore messages coming from my event stream that occur while my Subscribe method is running. I.e. it sometimes takes me lon

Answer 1

I've written a blog post about this with a solution that uses CAS instead of locks and avoids recursion. The code is below, but you can find a complete explanation here: http://www.zerobugbuild.com/?p=192

public static IObservable ObserveLatestOn(
    this IObservable source,
    IScheduler scheduler)
{
    return Observable.Create(observer =>
    {
        Notification pendingNotification = null;
        var cancelable = new MultipleAssignmentDisposable();

        var sourceSubscription = source.Materialize()
            .Subscribe(notification =>
            {
                var previousNotification = Interlocked.Exchange(
                    ref pendingNotification, notification);

                if (previousNotification != null) return;

                cancelable.Disposable = scheduler.Schedule(() =>
                    {
                        var notificationToSend = Interlocked.Exchange(
                            ref pendingNotification, null);
                        notificationToSend.Accept(observer);
                    });
            });
            return new CompositeDisposable(sourceSubscription, cancelable);
    });
}