Refactoring analysis: Executor prioritisation

[andresilva]

Analyse what kind of prioritisation we need (e.g. block authoring, off-chain workers, RPC calls) when sending requests to the executor. How is the implementation done in regards of prioritisation?

(will be updated with more details, mostly placeholder for planning/roadmap)

[koute]

So I think this maybe could be split into two parts:

1. Refactor and extend our low-level executor interface/cache which we use to instantiate a runtime and call into it with a given priority.
2. Integrate it with higher-level APIs (which abstract over the low-level details of how we're calling into the runtime) and actually use it in specific places (block authoring, RPC calls, etc.)

The first part is also necessary for #57, since you need an asynchronous queue to prioritize executor invocations anyway. (So essentially the executor will be always asynchronous; it's just the non-async methods will call the async ones and block.) I was already planning on tackling this soon and I have some rough idea on how to go about it (as I've said at the very end of this comment paritytech/substrate#11232 (comment) and also this issue here is related paritytech/substrate#8846) so I don't think this part actually requires much planning.

I've also tagged this issue and the other one with the I7-optimisation tag since this might have performance implications (it might improve the performance since there will be potentially less blocking on the critical paths).

[bkchr]

The first part is also necessary for #57, since you need an asynchronous queue to prioritize executor invocations anyway.

This issue is really more just about making runtime calls async. So you call call_in_runtime().await. That doesn't really require prioritization.

also this issue here is related paritytech/substrate#8846

This issue is exactly something that we then can fix when we have some central component that owns the cache and the execution :)

And in general good that you already had thought about this stuff, as I had this planed for you :D