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mdeloof / statig

Hierarchical state machines for designing event-driven systems
https://crates.io/crates/statig
MIT License
560 stars 18 forks source link

Refactor async functionality for `no_std`/`no_alloc` #20

Open pperanich opened 4 months ago

pperanich commented 4 months ago

Looking to continue the discussion from https://github.com/mdeloof/statig/issues/3 for refactoring the async implementation to work in both no_std and no_alloc environments. In particular, I would like to use this crate within an embassy-rs project.

In the previous issue, you said you had thoughts as to how you could statically allocate space for the futures. Do you still view this as a viable approach? I have not had luck in finding this done elsewhere.

deltronix commented 4 months ago

Similarly I would like to use this crate within an rtic project, while I do not need my state machines to be async currently it would be a very nice to have feature in the future :smirk:.

schphil commented 4 months ago

Same here! If I can be of any help let me know.

mdeloof commented 4 months ago

So I've been thinking about this for a while, and although I initially thought I'd be able to statically allocate the space for the futures, I currently don't see how that could work and frankly I'm not familiar enough with how futures work under the hood to say if it's even possible or not.

But! I've also realised recently that I could create an implementation of statig that doesn't use async recursion and that should work on no_std. I've tried making an initial version today and things looked good until I hit https://github.com/rust-lang/rust/issues/100013 and I'm not sure if there's anything I could for the moment to circumvent this issue. So it could be I'll have to wait until this issue is resolved, but the good news is that eventually async on no_std should be possible.

pperanich commented 4 months ago

Awesome to hear that you have a refactor in mind to circumvent this issue. Do you plan on pushing that working branch? I'd like to see what direction you plan on taking things. Thanks!

mdeloof commented 2 months ago

I found some time to work on this today. I've been able to resolve the bug and now have something that seems to work (code is on no_std_async). I plan on testing it with embassy but I haven't had a chance yet. Feel free to try it out though :)