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

Thanks to Lee Campbell (of Intro To Rx fame), I now have a working solution using this extension method:

public static IObservable ObserveLatestOn(this IObservable source, IScheduler scheduler)
{
    return Observable.Create(observer =>
    {
        Notification outsideNotification = null;
        var gate = new object();
        bool active = false;
        var cancelable = new MultipleAssignmentDisposable();
        var disposable = source.Materialize().Subscribe(thisNotification =>
        {
            bool alreadyActive;
            lock (gate)
            {
                alreadyActive = active;
                active = true;
                outsideNotification = thisNotification;
            }

            if (!alreadyActive)
            {
                cancelable.Disposable = scheduler.Schedule(self =>
                {
                    Notification localNotification = null;
                    lock (gate)
                    {
                        localNotification = outsideNotification;
                        outsideNotification = null;
                    }
                    localNotification.Accept(observer);
                    bool hasPendingNotification = false;
                    lock (gate)
                    {
                        hasPendingNotification = active = (outsideNotification != null);
                    }
                    if (hasPendingNotification)
                    {
                        self();
                    }
                });
            }
        });
        return new CompositeDisposable(disposable, cancelable);
    });
}