How to handle library callbacks in Grains

[burgerTo]

Hi,
i started analyzing my GrainCode and also logged the current TaskScheduler in many parts of the code. I wanted to make sure, that all graincode is exexuted on Scheduler:ActivationTaskScheduler.

In some rare cases this is not the case. I came to the conclusion that a external library makes some trouble here. I'm using stateless to implement statemachines in my grains. Simplfied it works like:

(Grain Code)                           (stateless library)                  (grain code)
statemachine.FireAsync(someEvent)  -> handle Statemachine logic async ->   async callback 

Is there a elegant way to prevent this? One idea was, to wrap each callback in an internal GrainInterface. But the hole statemachine structure relies on callbacks ... so this will look very confusing.

Generall speaking ... is there a good way how to deal with library callbacks in orleans? :)

Thanks a lot.
Toni

[JorgeCandeias]

The library is responsible for defining what scheduler to use for callbacks.

Some libraries, for example, Polly, have an argument in their methods such bool continueOnCapturedContext. Check if your library has something similar.

If you have no other option, you can always externally call a grain method from the callback, for example with:

this.AsReference<IMyGrainInterface>().MyGrainMethod();

This ensures that the method code interleaves properly with other methods, as per whatever interleaving rules defined.

This call will show up in the dashboard and telemetry, given it is an external call and therefore measured the same as other external calls.