You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: concurrency_limiter.rs
    path of file: ./repos/salvo/crates/extra/src
    
    the code of the file until where you have to start completion: //! concurrency limiter middleware.
//!
//! Read more: <https://salvo.rs>

use tokio::sync::Semaphore;

use salvo_core::http::StatusError;
use salvo_core::http::{Request, Respons
    
    async fn handle(&self, req: &mut Request, depot: &mut Depot, res: &mut Response, ctrl: &mut FlowCtrl) {
        match self.semaphore.acquire().await {
            Ok(_) => {
                ctrl.call_next(req, depot, res).await;
            }
            Err(e) => {
                tracing::error!(
                    "Max concurrency semaphore is never closed, acquire should never fail: {}",
                    e
                );
                res.render(StatusError::payload_too_large().brief("Max concurrency reached."));
            }
        }
    }