Creating Multiple Timers with Reactive Extensions

Question

I\'ve got a very simple class that I am using to poll a directory for new files. It\'s got the location, a time to start monitoring that location, and an interval (in hours

Answer 1

This is the clearest method I can think of:

foreach (var thing in things)
{
    Scheduler.ThreadPool.Schedule(
        thing.StartTime,
        () => {
                DoWork(thing.Uri); 
                Observable.Interval(TimeSpan.FromHours(thing.Interval))
                          .Subscribe(_ => DoWork(thing.Uri)));
              }
}

The following one is more functional:

things.ToObservable()
    .SelectMany(t => Observable.Timer(t.StartTime).Select(_ => t))
    .SelectMany(t => Observable.Return(t).Concat(
        Observable.Interval(TimeSpan.FromHours(t.Interval)).Select(_ => t)))
    .Subscribe(t => DoWork(t.Uri));

The First SelectMany creates a stream of things at their scheduled times. The second SelectMany takes this stream and creates a new one that repeats every interval. This needs to be joined to the Observable.Return which produces a value immediately as Observable.Interval's first value is delayed.

*Note, the first solution requires c#5 or else this will bite you.