TypeDB Client Rust dependencies: async runtimes, tokio-stream

[dmitrii-ubskii]

What is the goal of this PR?

We add dependencies used by TypeDB Client Rust for async runtime independence tests.

What are the changes implemented in this PR?

• tokio-stream: utility, maps tokio mpsc channel receivers to streams;
• http: remove a layer of indirection;
• smol and async-std: popular async runtimes.

[typedb-bot]

PR Review Checklist

Do not edit the content of this comment. The PR reviewer should simply update this comment by ticking each review item below, as they get completed.

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Trivial Change

• This change is trivial and does not require a code or architecture review.

Code

• Packages, classes, and methods have a single domain of responsibility.
• Packages, classes, and methods are grouped into cohesive and consistent domain model.
• The code is canonical and the minimum required to achieve the goal.
• Modules, libraries, and APIs are easy to use, robust (foolproof and not errorprone), and tested.
• Logic and naming has clear narrative that communicates the accurate intent and responsibility of each module (e.g. method, class, etc.).
• The code is algorithmically efficient and scalable for the whole application.

Architecture

• Any required refactoring is completed, and the architecture does not introduce technical debt incidentally.
• Any required build and release automations are updated and/or implemented.
• Any new components follows a consistent style with respect to the pre-existing codebase.
• The architecture intuitively reflects the application domain, and is easy to understand.
• The architecture has a well-defined hierarchy of encapsulated components.
• The architecture is extensible and scalable.

[dmitrii-ubskii]

Crates-universe depends on this Cargo.lock to be present.

[alexjpwalker]

Why? How was it working before we had this?

[dmitrii-ubskii]

.gitignore only affects files that aren't tracked.

[alexjpwalker]

So it was working because we'd generated Cargo.lock files on our local machines and that was allowing the update script to work?

[dmitrii-ubskii]

Because it was already present and tracked, modifications would be detected by git.

I discovered that this was a problem when I removed Cargo.lock through IDEA's project tree view, which runs git rm .... git then promptly ignored the newly generated lockfile, because it was no longer tracked.

[alexjpwalker]

Also, please include a couple of the most important crate names in the PR title so that it's more "unique" (currently the same PR title could be applied to >10 different PRs).

Something like "TypeDB Client Rust dependencies (async-std, tokio-stream, etc.)"

[alexjpwalker]

Why? How was it working before we had this?

[alexjpwalker]

Do we know why Tokio packages their stream library as a separate crate, as opposed to what they normally do, namely shipping it as a feature of tokio crate itself?

[dmitrii-ubskii]

TL;DR: tokio's minimum supported Rust version does not support streams.

https://docs.rs/tokio/latest/tokio/stream/

Originally, we had planned to ship Tokio 1.0 with a stable Stream type but unfortunately the RFC had not been merged in time for Stream to reach std on a stable compiler in time for the 1.0 release of Tokio. <...> [O]nce Stream has made it into the standard library and the MSRV period has passed, we will implement stream for our different types.