rust - How can I check the error kind from Warp's try_bind_with_graceful_shutdown?

Question

How can I check if the error from try_bind_with_graceful_shutdown is std::io::ErrorKind::AddrInUse?

Answer 1

如果您warp从存储库（而不是 crates.io）使用，您可以结合Error::source()使用Error::downcast_ref()来做您想做的事情：

let hello = warp::path!("hello" / String)
    .map(|name| format!("Hello, {}!", name));

match warp::serve(hello).try_bind_with_graceful_shutdown(SocketAddrV4::new(Ipv4Addr::new(0, 0, 0, 0), 8081), std::future::pending()) {
    Ok((_, future)) => future.await,
    Err(error) => {
        use std::error::Error;
        let mut current_error: &dyn Error = &error;
        let is_because_of_addr_in_use = loop {
            // get source of the error...
            current_error = match current_error.source() {
                // if there is one, continue
                Some(source) => source,
                // else, this error is not because of AddrInUse
                None => break false
            };
            //if the source is of type `std::io::Error`
            if let Some(io_error) = current_error.downcast_ref::<std::io::Error>() {
                break io_error.kind() == std::io::ErrorKind::AddrInUse;
            }
        };
            
        println!("Failed. is_because_of_addr_in_use == {}", is_because_of_addr_in_use);
    }
};

Failed. is_because_of_addr_in_use == true当且仅当由于它已在使用中而warp未能绑定到时，才会打印。SocketAddr

请注意，这不适用于已发布的版本，warp因为实现的拉取请求Error::sourcewarp::Error尚未发布。如果您使用的warp是.DebugDisplaywarp::Error