The networking implementations I've had to do were all made a lot easier moving to async/await from hand-written state machines. It's a reduction in LOC terms of 6x or so, and the logic is much, much easier to follow.
State machines are viable if your transition function is such that effectively every combination of (state, input) leads to a different state. If the transition function is mostly describing "go to the (single) next state or error," then you're essentially asking the user to do a lot of bookkeeping that compilers are good at and users are bad at.
Re:How Rust optimizes async/await
by littlestymaar on Monday August 19, 2019 @02:52PM
(#20740599)
Having ported a full peer-to-peer engine in JavaScript from old-school callbacks to async/await, I strongly disagree with your comment.
Async/await really shines when the complexity arises.
People are doing a lot more with async/await than five-line echo servers. They're converting entire codebases and seeing dramatic reductions in noise.
Probably because you're just looking at examples; that's selection bias. The combinators/manual implementing Future approach to async IO gets even worse at scale, async/await is infinitely easier. If you don't like it, nobody is forcing you to use it.
Cool, you can write a 5 line echo server easier, but good luck with a high performance server handling important transactions.
(If there is documentation on how to do some of these or good example code, please point me to it, because my last attempt at getting send/rcv heartbeats efficiently didn't work.)