Paragraph breaks mine:
My take on this is that you cannot use async Rust correctly and fluently without understanding Arc, Mutex, the mutability of variables/references, and how async and await syntax compiles in the end. Rust forces you to understand how and why things are the way they are. It gives you minimal abstraction to do things that could’ve been tedious to do yourself.
I got a chance to work on two projects that drastically forced me to understand how async/await works. The first one is to transform a library that is completely sync and only requires a sync trait to talk to the outside service. This all sounds fine, right? Well, this becomes a problem when we try to port it into browsers. The browser is single-threaded and cannot block the JavaScript runtime at all! It is arguably the most weird environment for Rust users. It is simply impossible to rewrite the whole library, as it has already been shipped to production on other platforms.
What we did instead was rewrite the network part using async syntax, but using our own generator. The idea is simple: the generator produces a future when called, and the produced future can be awaited. But! The produced future contains an arc pointer to the generator. That means we can feed the generator the value we are waiting for, then the caller who holds the reference to the generator can feed the result back to the function and resume it. For the browser, we use the native browser API to derive the network communications; for other platforms, we just use regular blocking network calls. The external interface remains unchanged for other platforms.
Honestly, I don’t think any other language out there could possibly do this. Maybe C or C++, but which will never have the same development speed and developer experience.
I believe people have already mentioned it, but the current asynchronous model of Rust is the most reasonable choice. It does create pain for developers, but on the other hand, there is no better asynchronous model for Embedded or WebAssembly.
https://old.reddit.com/r/rust/comments/1ai1a97/let_futures_be_futures/korxtar/