Hands-On Microservices with Rust

Adding a shared state

You may have already heard that shared data is a bad thing and a potential cause of bottlenecks, if it has to be changed from separate threads. However, shared data can be useful if we want to share the address of a channel or if we don't need frequent access to it. In this section, we need a user database. In the following example, I'll show you how to add a shared state to our generator function. This approach can be used for a variety of reasons, such as keeping a connection to a database.

A user database will obviously hold data about users. Let's add some types to handle this:

type UserId = u64;struct UserData;

UserId represents the user's unique identifier. UserData represents the stored data, but we use an empty ...