Async Programming
Async programming in Rust is a recent development, only having been stabilized in Rust 1.39
. The async ecosystem is rapidly evolving, and SeaORM is one of the first crates built from the ground up with async support in mind.
The first thing to learn is the Future
trait. It's a placeholder for a function that will compute and return some value in the future. It's lazy, meaning .await
must be called for any actual work to be done. Future
allows us to achieve concurrency with little programming effort, e.g. future::join_all
to execute multiple queries in parallel.
Second, async
in Rust is multi-threaded programming with syntactic sugar. A Future
may move between threads, so any variables used in async bodies must be able to travel between threads, i.e. Send
.
Third, there are multiple async runtimes in Rust. async-std
and tokio
are the two most widely used. SeaORM's underlying driver, SQLx
, supports both.
Knowing these concepts is essential to get you up and running in async Rust.