I'm currently working on a project with @HamishDotNet & @LordHanson where we make heavy use of Rx (Reactive Extensions) for processing streams of data which are generated asynchronously. We have multiple pipeline processes based around an Rx stream, they look something like this: The method Sequence returns an instance of IObservable<T> which is then acted upon by 4 or 5 methods before the Subscriber is called, some of these methods might mutate the state along the way. The important part is the idea of the pipeline to process the Rx stream as it is generated by the asynchronous Sequence method. So what I wanted to do is log what's going on - how long each step takes (in the pipeline) as well as how long the Rx stream is alive and when the stream generates a value. The issue we have is we don't want to overly modify the code just support such logging\telemetry. I don't want to end up with something like this: Don't get me wrong, if I had only ...