Tokio
Tokio provides:
- A multi-threaded runtime for executing asynchronous code.
- An asynchronous version of the standard library.
- A large ecosystem of libraries.
use tokio::time; async fn count_to(count: i32) { for i in 0..count { println!("Count in task: {i}!"); time::sleep(time::Duration::from_millis(5)).await; } } #[tokio::main] async fn main() { tokio::spawn(count_to(10)); for i in 0..5 { println!("Main task: {i}"); time::sleep(time::Duration::from_millis(5)).await; } }
-
With the
tokio::main
macro we can now makemain
async. -
The
spawn
function creates a new, concurrent "task". -
Note:
spawn
takes aFuture
, you don't call.await
oncount_to
.
Further exploration:
-
Why does
count_to
not (usually) get to 10? This is an example of async cancellation.tokio::spawn
returns a handle which can be awaited to wait until it finishes. -
Try
count_to(10).await
instead of spawning. -
Try awaiting the task returned from
tokio::spawn
.