• English

      • Catching Panics in Requests

      Catch Panic is used to capture crashes that occur during request processing in the program. For specific APIs, please refer to the documentation.

      Note: To use CatchPanic, you need to enable the catch-panic feature in Cargo.toml:

      salvo = { version = "xxx", features = ["catch-panic"] }

      Middleware Introduction

      CatchPanic is a middleware designed to catch panics in handlers. When a panic occurs during request processing, it captures the panic and writes a 500 Internal Server Error to the response, preventing the entire server from crashing.

      Important Note: This middleware should be used as the first middleware to ensure it can catch panics from other middlewares or handlers.

      Basic Usage

      use salvo_core::prelude::*;
use salvo_extra::catch_panic::CatchPanic;

#[handler]
async fn hello() {
    panic!("panic error!");
}

#[tokio::main]
async fn main() {
    let router = Router::new().hoop(CatchPanic::new()).get(hello);
    let acceptor = TcpListener::new("0.0.0.0:8698").bind().await;
    Server::new(acceptor).serve(router).await;
}

      Comparison with Other Frameworks for Quick Concept Understanding

      Axum

      Similar to the catch_panic middleware in Axum's Tower:

      use axum::{
    Router,
    routing::get,
    http::StatusCode,
};
use tower::ServiceBuilder;
use tower_http::catch_panic::CatchPanicLayer;

async fn panic_handler() -> &'static str {
    panic!("panic error!");
}

#[tokio::main]
async fn main() {
    let app = Router::new()
        .route("/", get(panic_handler))
        .layer(
            ServiceBuilder::new()
                .layer(CatchPanicLayer::new())
        );
    
    axum::Server::bind(&"0.0.0.0:3000".parse().unwrap())
        .serve(app.into_make_service())
        .await
        .unwrap();
}

      Gin (Go)

      In the Go language's Gin framework, similar to the Recovery middleware:

      package main

import (
    "github.com/gin-gonic/gin"
)

func main() {
    r := gin.Default() // Includes the Recovery middleware by default
    
    r.GET("/", func(c *gin.Context) {
        panic("panic error!")
    })
    
    r.Run(":8080")
}

      Example Code

      main.rs
      Cargo.toml
      use salvo::prelude::*;

// Handler that deliberately panics to demonstrate panic catching
#[handler]
async fn hello() {
    panic!("panic error!");
}

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

    // Set up router with CatchPanic middleware to handle panics gracefully
    // This prevents the server from crashing when a panic occurs in a handler
    let router = Router::new().hoop(CatchPanic::new()).get(hello);

    // Bind server to port 8698 and start serving
    let acceptor = TcpListener::new("0.0.0.0:8698").bind().await;
    Server::new(acceptor).serve(router).await;
}