Book Image

Asynchronous Programming in Rust

By : Carl Fredrik Samson
5 (2)
Book Image

Asynchronous Programming in Rust

5 (2)
By: Carl Fredrik Samson

Overview of this book

Step into the world of asynchronous programming with confidence by conquering the challenges of unclear concepts with this hands-on guide. Using functional examples, this book simplifies the trickiest concepts, exploring goroutines, fibers, futures, and callbacks to help you navigate the vast Rust async ecosystem with ease. You’ll start by building a solid foundation in asynchronous programming and explore diverse strategies for modeling program flow. The book then guides you through concepts like epoll, coroutines, green threads, and callbacks using practical examples. The final section focuses on Rust, examining futures, generators, and the reactor-executor pattern. You’ll apply your knowledge to create your own runtime, solidifying expertise in this dynamic domain. Throughout the book, you’ll not only gain proficiency in Rust's async features but also see how Rust models asynchronous program flow. By the end of the book, you'll possess the knowledge and practical skills needed to actively contribute to the Rust async ecosystem.
Table of Contents (16 chapters)
Free Chapter
1
Part 1:Asynchronous Programming Fundamentals
5
Part 2:Event Queues and Green Threads
8
Part 3:Futures and async/await in Rust

A mental model of an async runtime

I find it easier to reason about how futures work by creating a high-level mental model we can use. To do that, I have to introduce the concept of a runtime that will drive our futures to completion.

Note

The mental model I create here is not the only way to drive futures to completion, and Rust’s futures do not impose any restrictions on how you actually accomplish this task.

A fully working async system in Rust can be divided into three parts:

  • Reactor (responsible for notifying about I/O events)
  • Executor (scheduler)
  • Future (a task that can stop and resume at specific points)

So, how do these three parts work together?

Let’s take a look at a diagram that shows a simplified overview of an async runtime:

Figure 6.1 – Reactor, executor, and waker

Figure 6.1 – Reactor, executor, and waker

In step 1 of the figure, an executor holds a list of futures. It will try to run the future by polling it (the poll phase...