server.rs

use std::error::Error;
use std::net::UdpSocket;
use std::time::{SystemTime, UNIX_EPOCH};

use netem_evaluator::Message;

fn main() -> Result<(), Box<dyn Error>> {
    let socket = UdpSocket::bind("0.0.0.0:6789")?;
    eprintln!("Listening on :6789");

    let mut buffer = [0u8; 1000];

    loop {
        match socket.recv(&mut buffer) {
            Ok(received) => {
                let now = SystemTime::now().duration_since(UNIX_EPOCH)?.as_nanos();

                let mut message: Message = bincode::deserialize(&buffer[..received])?;
                message.timestamp = now - message.timestamp; // Abuse timestamp field to store time difference

                // let time_diff_micros = (now - message.timestamp) as f64 / 1000.;
                // let id = message.id;
                // println!("Received packet #{id} - Time difference: {time_diff_micros:.3} µs");
                println!("{}", serde_json::to_string(&message)?);
                let server_time_per_request =
                    SystemTime::now().duration_since(UNIX_EPOCH)?.as_nanos() - now;
                // println!(
                //     "{} ms time needed for server to handle request",
                //     server_time_per_request as f64 / 1000000.
                // );
                assert!(server_time_per_request < 10000000); // if this bites you, you should choose a higher value for TIME_BETWEEN_MESSAGES_IN_MICRO_SECONDS
            }
            Err(e) => eprintln!("Error receiving: {}", e),
        }
    }
}