Our catscii program does everything we want it to do, except that it's a command-line application rather than a web server. Let's fix that.

The documentation for the axum crate tells us how to make a basic web server, and we honestly don't need much more than that.

So let's add axum:

amos@miles:~/catscii$ cargo add axum@0.6
    Updating crates.io index
      Adding axum =0.6 to dependencies.
             Features:
             + form
             + http1
             + json
             + matched-path
             + original-uri
             + query
             + tokio
             + tower-log
             - __private_docs
             - headers
             - http2
             - macros
             - multipart
             - w

Back when I wrote this codebase, warp was the best / only alternative for something relatively high-level on top of hyper.

I was never super fond of warp's model — it's a fine crate, just not for me.

The way routing works is essentially building a type that gets larger and larger. One route might look like:

As the popular saying goes, there are only two hard problems in computer science: caching, off-by-one errors, and getting a Rust job that isn't cryptocurrency-related.

Today, we'll discuss caching! Or rather, we'll discuss... "request coalescing", or "request deduplication", or "single-flighting" - there's many names for that concept, which we'll get into fairly soon.