I'm not sure how an actor would solve that problem. You're describing the way a system call works, which is not relevant to how your userland asynchrony works. In either case you're always "leaking" (I'd say "holding") the resource while you wait for the kernel to give it back to you.
Indeed I was merely describing how it behaves within the context of future + ioloop with tokio. I didn't take a stance on future vs actor.
In Rust my instinct tells me the difference between actor and future is negligible. Because it compiles down to almost the same thing. But I wouldn't bet my life on it.
Note that my understanding of what an actor is might be wrong. I assume an actor is a sort of thread with a main ioloop receiving and sending messages. Which is basically what a tokio ioloop thread is. Atop of which the futures give you an abstractions to compose IO functions more easily.
