Summary

So, what a ride! As I said in the introduction for this chapter, this is one of the biggest ones in this book, but even though you might not realize it, you’ve already got a better grasp of how asynchronous Rust works than most people do. Great work!

In this chapter, you learned a lot about runtimes and why Rust designed the Future trait and the Waker the way it did. You also learned about reactors and executors, Waker types, Futures traits, and different ways of achieving concurrency through the join_all function and spawning new top-level futures on the executor.

By now, you also have an idea of how we can achieve both concurrency and parallelism by combining our own runtime with OS threads.

Now, we’ve created our own async universe consisting of coro/wait, our own Future trait, our own Waker definition, and our own runtime. I’ve made sure that we don’t stray away from the core ideas behind asynchronous programming in Rust so that everything...