Salvo Request Timeout

This skill helps configure request timeouts in Salvo applications to prevent slow requests from consuming server resources indefinitely.

Why Use Timeouts?

• Prevent resource exhaustion: Long-running requests can consume connections and memory
• Improve reliability: Fail fast rather than hang indefinitely
• Better user experience: Users get quick feedback instead of waiting forever
• Protection against attacks: Slowloris and similar attacks are mitigated

Setup

Timeout is built into Salvo core:

[dependencies]
salvo = "0.89.0"

Basic Timeout

use std::time::Duration;
use salvo::prelude::*;

#[handler]
async fn fast_handler() -> &'static str {
    "Hello, World!"
}

#[handler]
async fn slow_handler() -> &'static str {
    // Simulates a slow operation
    tokio::time::sleep(Duration::from_secs(10)).await;
    "This takes a while..."
}

#[tokio::main]
async fn main() {
    tracing_subscriber::fmt().init();

    let router = Router::new()
        // Apply 5-second timeout to all routes
        .hoop(Timeout::new(Duration::from_secs(5)))
        .push(Router::with_path("fast").get(fast_handler))
        .push(Router::with_path("slow").get(slow_handler));

    let acceptor = TcpListener::new("0.0.0.0:8080").bind().await;
    Server::new(acceptor).serve(router).await;
}

When accessing /slow, the request will timeout after 5 seconds and return a 408 Request Timeout response.

Route-Specific Timeouts

Apply different timeouts to different routes:

use std::time::Duration;
use salvo::prelude::*;

#[tokio::main]
async fn main() {
    let router = Router::new()
        .push(
            Router::with_path("quick")
                .hoop(Timeout::new(Duration::from_secs(2)))
                .get(quick_handler)
        )
        .push(
            Router::with_path("standard")
                .hoop(Timeout::new(Duration::from_secs(30)))
                .get(standard_handler)
        )
        .push(
            Router::with_path("long-running")
                .hoop(Timeout::new(Duration::from_secs(300)))
                .get(long_running_handler)
        );

    let acceptor = TcpListener::new("0.0.0.0:8080").bind().await;
    Server::new(acceptor).serve(router).await;
}

Timeout with API Routes

use std::time::Duration;
use salvo::prelude::*;

#[tokio::main]
async fn main() {
    // Short timeout for API endpoints
    let api_timeout = Timeout::new(Duration::from_secs(10));

    // Longer timeout for file uploads
    let upload_timeout = Timeout::new(Duration::from_secs(120));

    let router = Router::new()
        .push(
            Router::with_path("api")
                .hoop(api_timeout)
                .push(Router::with_path("users").get(list_users))
                .push(Router::with_path("products").get(list_products))
        )
        .push(
            Router::with_path("upload")
                .hoop(upload_timeout)
                .post(handle_upload)
        );

    let acceptor = TcpListener::new("0.0.0.0:8080").bind().await;
    Server::new(acceptor).serve(router).await;
}

Global Timeout with Exceptions

use std::time::Duration;
use salvo::prelude::*;

#[tokio::main]
async fn main() {
    // Default 30-second timeout
    let default_timeout = Timeout::new(Duration::from_secs(30));

    let router = Router::new()
        .hoop(default_timeout)  // Apply to all routes
        .push(Router::with_path("health").get(health_check))
        .push(Router::with_path("api/{**rest}").get(api_handler))
        .push(
            // Override with longer timeout for specific route
            Router::with_path("reports/generate")
                .hoop(Timeout::new(Duration::from_secs(300)))
                .post(generate_report)
        );

    let acceptor = TcpListener::new("0.0.0.0:8080").bind().await;
    Server::new(acceptor).serve(router).await;
}

Timeout with Custom Error Response

Handle timeout errors with a custom catcher:

use std::time::Duration;
use salvo::prelude::*;
use salvo::catcher::Catcher;

#[handler]
async fn handle_timeout(res: &mut Response, ctrl: &mut FlowCtrl) {
    if res.status_code() == Some(StatusCode::REQUEST_TIMEOUT) {
        res.render(Json(serde_json::json!({
            "error": "Request Timeout",
            "message": "The request took too long to process",
            "code": 408
        })));
        ctrl.skip_rest();
    }
}

#[tokio::main]
async fn main() {
    let router = Router::new()
        .hoop(Timeout::new(Duration::from_secs(5)))
        .get(slow_handler);

    let service = Service::new(router).catcher(
        Catcher::default().hoop(handle_timeout)
    );

    let acceptor = TcpListener::new("0.0.0.0:8080").bind().await;
    Server::new(acceptor).serve(service).await;
}

Combining Timeout with Other Middleware

use std::time::Duration;
use salvo::prelude::*;
use salvo::rate_limiter::{BasicQuota, FixedGuard, MokaStore, RateLimiter, RemoteIpIssuer};

#[tokio::main]
async fn main() {
    // Rate limiter
    let limiter = RateLimiter::new(
        FixedGuard::new(),
        MokaStore::new(),
        RemoteIpIssuer,
        BasicQuota::per_second(10),
    );

    // Timeout
    let timeout = Timeout::new(Duration::from_secs(30));

    let router = Router::new()
        .hoop(limiter)   // Rate limit first
        .hoop(timeout)   // Then apply timeout
        .push(Router::with_path("api/{**rest}").get(api_handler));

    let acceptor = TcpListener::new("0.0.0.0:8080").bind().await;
    Server::new(acceptor).serve(router).await;
}

Practical Timeout Values

Example: Microservices Gateway

use std::time::Duration;
use salvo::prelude::*;

#[tokio::main]
async fn main() {
    let router = Router::new()
        // Auth service - should be fast
        .push(
            Router::with_path("auth/{**rest}")
                .hoop(Timeout::new(Duration::from_secs(5)))
                .goal(auth_proxy)
        )
        // User service - moderate
        .push(
            Router::with_path("users/{**rest}")
                .hoop(Timeout::new(Duration::from_secs(15)))
                .goal(users_proxy)
        )
        // Analytics service - can be slow
        .push(
            Router::with_path("analytics/{**rest}")
                .hoop(Timeout::new(Duration::from_secs(60)))
                .goal(analytics_proxy)
        )
        // Report service - long running
        .push(
            Router::with_path("reports/{**rest}")
                .hoop(Timeout::new(Duration::from_secs(300)))
                .goal(reports_proxy)
        );

    let acceptor = TcpListener::new("0.0.0.0:8080").bind().await;
    Server::new(acceptor).serve(router).await;
}

Best Practices

1. Set appropriate timeouts: Match timeout to expected operation duration
2. Use shorter timeouts for public APIs: Prevent abuse and resource exhaustion
3. Longer timeouts for internal services: Trusted services may need more time
4. Log timeouts: Track which requests are timing out for debugging
5. Consider client expectations: Some clients may have their own timeouts
6. Combine with rate limiting: Protect against slowloris attacks
7. Graceful degradation: Return meaningful error messages on timeout
8. No timeout for WebSocket: Long-lived connections shouldn't have request timeouts