Async Rust

Chapter 9. Design Patterns

Throughout the book, we have covered various async concepts and how to implement async code in multiple ways to solve problems. However, we know that software engineering does not exist in a vacuum. When applying your newfound knowledge of async programming in the wild, you will not be able to apply isolated async code in a perfect environment. You might be applying async code to an existing codebase that is not async. You might be interacting with a third-party service like a server, where you will need to handle variances in the response to the server. In this chapter, we cover design patterns that help you implement async code when solving a range of problems.

By the end of this chapter, you will be able to implement async code in an existing codebase that previously did not support async programming. You will also be able to implement the waterfall design pattern to enable the building of pathways with reusable async components. Instead of altering the code of our async tasks to add features, you will be able to implement the decorator pattern so you can easily slot in extra functionality such as logging by just adding a compilation flag when running or building your program. Finally, you will be able to get the entire async system to adapt to errors by implementing the retry and circuit-breaker patterns.

First of all, we need to be able to implement async code in our system before implementing design patterns. So we should start with building an ...