GitLab Incubation Engineering, 18 Aug 2022

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From YouTube: Incubation Engineering Real-time updates of issue descriptions – Update 2022-08-18

Description

- Awareness about to ship behind a feature flag
- A little intro into Ruby + Rust bindings

A

Friends and welcome to another update of real-time editing of issue descriptions um this week. I want to give you a short update on how the awareness widget is doing. uh It has officially moved into the review process.

A

So, as you can see on my screen, all the good chess here on the top is going to be added to the issue sidebar, so the empty state currently is shared to collaborate link. If you click on it, it gets automatically automatically added to your to your clipboard on this, mr, you can see all the potential states like single collaborator when you hover over the collaborator. What the current state is, uh two collaborators, etc etc so uh includes all the active states includes all um you know.

A

If there's any overflow of users, like more than four users, are kind of like put into the um the more collaborate this um uh you get. A pop over inactive states are also there um yeah, hopefully, the last week before the ships uh was uh took, took quite a while to get there um yeah.

A

Another thing I want to show you is like how the ruby rust binding um is actually is actually working, as uh some of you know we're relying relying on a library that is written in rust, called y c or crdt or wires, and this is a crd.

A

This is a crtt implementation that is quite popular because it's based off of one of the most popular javascript library libraries used in that space named ygs and what we are doing in order to bring crdts to gitlab, which is a ruby application, is we need to provide a ruby version or a ruby binding for those crttts, and so this is why we ended up like building this by rubygem, and this is why rubychamp is nothing else than a finn wrapper around the rust library, but the actual implementation of them jam is quite interesting, because there's many there's a couple of ways to do that and um ruby is somewhat known to deal with natick's at native extensions, a lot like even when you install or when you create a new rails application from scratch.

A

You have to install a couple of native extensions, but most of them are written in c and not in rust. Rust is a relatively I mean it's not a completely new language, but it's a relatively new language used for ruby native extensions and those native extensions um can be written in several ways like you could expose rust functions directly. We wired a c for a function. Interface like this is supported, but it's not super comfortable and I want to show like how we are doing it and what we are using for it.

A

um So this is the why ruby repository and the library repository um is not terribly complex. uh It's basically like two source folder. We have the lib folder, which is you know your regular rubygem structure. It's not super exciting. You know it's just a few ruby files and we have this nice little extension folder here and it contains all the native extensions that are built in rust. We have a single one.

A

It's the by ruby native extension and this particular structure is set up by a library called magnus and magnus is a high level framework or library that allows us to write ruby to rust bindings in a relatively convenient way. um There is already a by ruby where uh railroad gem published, which isn't using magnus it's actually relying on rooty, which is another um great tool to write this kind of gems, but magnus has a few features that I really like, and I want to show you what what exactly I mean by that.

A

So, let's just take a look at the array class here, which is you know, you're kind of like familiar with an area in ruby. I assume- and you can you know, get a specific item at a specific index. You can insert an item at a specific index. You can iterate over an array and um all those operations somehow need also somehow need to be supported by the crdt version of an area as well, and we want to make it as easy as possible for ruby developers to interact with crdt.

A

So there should not be any inconveniences or unfamiliar concepts, and this is this is the primary goal of the ruby wrapper. It should make crtts accessible for ruby developers.

A

So what we see here is that the the insert like when we're inserting at a specific index, we actually call a y array insert method or function, but this method doesn't really exist here because it exists in rus and it's just a binding between the ruby and rust library. And if we go to the ras code here, we can see this y array insert method and how it is structured- and this is kind of interesting because we can see the index here is an unsigned integer, and um this is not really.

A

This is a lot there's a lot of matching in order to make this work so magnus automatically automatically converts that, for us, we expect the index to be a number and particular integer, and therefore we can assume that the index here is of the correct type and if it's not of the correct type magnus we'll make sure that it raises an error and automatically for you type error in this case.

A

But there's also this magic value here, which is a ruby value which can be literally any valid ruby valley, because you can't, you know technically insert anything into an array and yeah. This was a short journey or a short um intro into like ruby and rust bindings are done. I hope you've somewhat, like the additional technical detail and yeah see you soon.