Example in MethodRouter::layer documentation doesn't work #2582
Description
The docs for MethodRouter::layer contain this example:
use axum::{routing::get, Router};
use tower::limit::ConcurrencyLimitLayer;
async fn handler() {}
let app = Router::new().route(
"/",
// All requests to `GET /` will be sent through `ConcurrencyLimitLayer`
get(handler).layer(ConcurrencyLimitLayer::new(64)),
);This compiles, but no concurrency limit is enforced. This is because each request to GET / is sent through a different ConcurrencyLimit instance, each with its own semaphore.
Full runnable example (test with hey -n 50 http://localhost:3000/api/test):
use axum::{routing::get, Router};
use std::time::Duration;
use tower::limit::ConcurrencyLimitLayer;
async fn handler() {
eprintln!("/api/test in");
tokio::time::sleep(Duration::from_secs(1)).await;
eprintln!("/api/test out");
}
#[tokio::main]
async fn main() {
let app = Router::new().route(
"/api/test",
get(handler).layer(ConcurrencyLimitLayer::new(5)),
);
// run our app with hyper, listening globally on port 3000
let listener = tokio::net::TcpListener::bind("0.0.0.0:3000").await.unwrap();
axum::serve(listener, app).await.unwrap();
}