RustTokioBenchmark VS Umpire

> If you ever pull up a debugger and step through an async Rust/tokio codebase, you'll get a good sense for what the overhead here we're talking about is.

So I didn't quite do that, but the overhead was interesting to me anyway, and as I was unable to find existing benchmarks (surely they exist?), I instructed computer to create one for me: https://github.com/eras/RustTokioBenchmark

On this wee laptop the numbers are 532 vs 6381 cpu cycles when sending a message (one way) from one async thread to another (tokio) or one kernel thread to another (std::mpsc), when limited to one CPU. (It's limited to one CPU as rdtscp numbers are not comparable between different CPUs; I suppose pinning both threads to their own CPUs and actually measuring end-to-end delay would solve that, but this is what I have now.)

So this was eye-opening to me, as I expected tokio to be even faster! But still, it's 10x as fast as the thread-based method.. Straight up callback would still be a lot faster, of course, but it will affect the way you structure your code.

Improvements to methodology accepted via pull requests :).

* https://github.com/joshhansen/Umpire

The reason for this is that I'd like to use an RAII pattern to control player turns in Umpire. When the struct is initialized, it starts the player's turn, and when the struct is dropped, it ends the player's turn.

Wound up with some time so I figured I'd port my Umpire military strategy game to a client-server architecture so people can play it online. This will give me some experience with Tokio, tarpc, and async Rust generally, since I'm eyeing a possible Rust dev gig in my future.

I've done a little bit of Rust development on Windows and had a good experience. I ported my (still unfinished) Umpire game to Windows pretty easily. I had to rename some files that had colons in the filename which Windows didn't like. The actual hard part was the terminal library, but switching to crossterm was pretty straightforward. All in all it was pretty painless.