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kevinmehall / nusb

A new pure-Rust library for cross-platform low-level access to USB devices.
Apache License 2.0
228 stars 28 forks source link

WebUSB backend #83

Open kevinmehall opened 2 months ago

kevinmehall commented 2 months ago

https://github.com/G2-Games/cross-usb wraps nusb and WebUSB with a subset of the API, but WebUSB could be an nusb backend in-tree instead of requiring a wrapper library.

This is probably not something I'll get to soon, but the API implications are worth considering, mainly that all WebUSB operations are async, while nusb currently has many blocking methods where the underlying OS operations are blocking.

For non-Wasm, it looks like cross_usb just calls the nusb blocking methods from an async fn, blocking the async runtime. Probably fine for a lot of use cases, but not ideal if your application is primarily async. Doing that right would require depending on blocking or tokio::spawn_blocking. So far nusb has managed to avoid depending on an async executor.

(cc @G2-Games)

G2-Games commented 2 months ago

I thought about looking into including WASM support in nusb originally, but I thought it would be best to do in a separate crate for the moment as my main use case was just a single library I'm working on (minidisc-rs). However, if you're interested in it that's very cool! I'm happy to help or modify my code to be better/work properly, but I haven't looked into the internals of nusb.

As you've already said, WASM cannot block (in an async context), which actually led to the refactoring of the entirety of minidisc-rs to async due to how cross_usb works.

Thank you for your awesome work on nusb!

TroyNeubauer commented 1 month ago

Going to hold off on https://github.com/G2-Games/cross-usb/issues/2 if wasm support is coming to nusb in the near future