Async Counter App
In the previous counter app, we had a purely sequential blocking application. There are times when you may be interested in running IO operations or compute asynchronously.
For this tutorial, we will build a single file version of an async TUI using tokio. This tutorial section is a simplified version of the async ratatui counter app.
Installation
Here’s an example of the Cargo.toml
file required for this tutorial:
[package]name = "ratatui-counter-async-app"version = "0.1.0"edition = "2021"
[dependencies]color-eyre = "0.6.2"crossterm = { version = "0.27.0", features = ["event-stream"] }ratatui = "0.24.0"tokio = { version = "1.32.0", features = ["full"] }tokio-util = "0.7.9"futures = "0.3.28"
Setup
Let’s take the single file multiple function example from the counter app from earlier:
fn main() -> Result<()> { // setup terminal startup()?;
let result = run();
// teardown terminal before unwrapping Result of app run shutdown()?;
result?;
Ok(())}
Tokio is an asynchronous runtime for the Rust programming language. It provides the building blocks needed for writing network applications. We recommend you read the Tokio documentation to learn more.
For the setup for this section of the tutorial, we are going to make just one change. We are going
to make our main
function a tokio
entry point.
#[tokio::main]async fn main() -> Result<()> { // setup terminal startup()?;
let result = run();
// teardown terminal before unwrapping Result of app run shutdown()?;
result?;
Ok(())}
Adding this #[tokio::main]
macro allows us to spawn tokio tasks within main
. At the moment,
there are no async
functions other than main
and we are not using .await
anywhere yet. We will
change that in the following sections. But first, we let us introduce the Action
enum.