Async Rust and Node SerialPort
This year I took some time around the holidays to do some learning. Like last year I dove into rust but I didn’t go into it cold this time. I was gifted a “live book” called Rust In Motion which has audio, slides and text all mixed together. It was fun and covered the basics in a very approachable way. So I had that base which I had been building up over a few weeks, and my SerialPort co-maintainer Nick Hehr sent me a text about NAPI.rs. I don’t know if he meant to nerd snipe me but it sent me down a rabbit hole that took the rest of my week building a rust bindings prototype for node Serial Port.
First off I had no idea what I was doing, I’ve never explored or used async in rust. I understand N-API for nodejs but haven’t used it much. But I have a use case, Node SerialPort has been stagnant and the bugs are mostly due to needing to use N-API and stay away from the ever changing ever v8 api. I have a whole host of electron users who deserve better. Additionally I think performance could be better and I think allowing for the use of workers, and maintaining our own thread pool would go a long way in that department. So can rust help?
Of course it can help! After a bunch of work I was able to release rust serialport binding prototype working. It does a non blocking cross platform Binding.list() that lists available serial ports. And it’s the smallest shippable surface area I could approach. It’s a pretty fundamental shift from the JS and C++ I’ve been using, so each layer of this prototype was an education.
The serialport crate is a blocking library for serialport access. It works! It’s a little hard to distribute as it requires some c++ libraries for serialport listing but I think I can overcome that. The blocking nature however leaves it not entirely usable on it’s own. There’s a wrapper library called tokio-serial which writes some async reading and writing but it’s a bit out of date and is actually a wrapper of a mio-serialport which is by the same author and is a lower level async serialport library. mio-serialport looks pretty familiar to node SerialPort’s c++ code for both windows and unix and frankly that’s fantastic. I feel like I need to fork and maintain some of these projects for our uses, but I’m not thrilled to fracture the ecosystem or take on the maintenance burden.
I have some notes about different ways this project could go. There is still a lot of exploration and experimentation to do but this was an exciting deep dive. Looking forward to more!