Mio demo with rust

mio-demo.rs

// [dependencies]
// mio = { version = "0.8", features = ["net", "os-ext", "os-poll"] }

use mio::{
    event::Event,
    net::{TcpListener, TcpStream},
    Events, Interest, Poll, Token,
};
use std::{cell::RefCell, collections::HashMap, io::Read, net::SocketAddr, rc::Rc};

const SERVER: Token = Token(0);

struct MyServer {
    listener: TcpListener,
    connections: HashMap<Token, TcpStream>,
    event_loop: Rc<RefCell<Poll>>,
    last_token: usize,
}

#[derive(Debug)]
pub struct SErr(pub &'static str);

impl std::fmt::Display for SErr {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        std::fmt::Display::fmt(self.0, f)
    }
}

impl std::error::Error for SErr {}

impl MyServer {
    fn new(listener: TcpListener, event_loop: Rc<RefCell<Poll>>) -> MyServer {
        MyServer {
            listener,
            connections: HashMap::new(),
            event_loop,
            last_token: SERVER.0,
        }
    }

    fn new_token(&mut self) -> Token {
        self.last_token += 1;
        Token(self.last_token)
    }

    fn handle_event(&mut self, event: &Event) -> Result<(), Box<dyn std::error::Error>> {
        match event.token() {
            SERVER => {
                // 有新連接進來
                loop {
                    match self.listener.accept() {
                        Ok((mut stream, _)) => {
                            let token = self.new_token();
                            println!("New connection from: {}", stream.peer_addr()?);
                            self.event_loop
                                .borrow_mut()
                                .registry()
                                .register(&mut stream, token, Interest::READABLE)?;
                            self.connections.insert(token, stream);
                        }
                        Err(ref e) if e.kind() == std::io::ErrorKind::WouldBlock => return Ok(()),
                        Err(e) => return Err(e.into()),
                    }
                }
            }
            token => {
                // 有數據可讀
                let mut buffer = [0; 1024];
                loop {
                    match self.connections.get_mut(&token).ok_or(SErr("error"))?.read(&mut buffer) {
                        Ok(0) => {
                            // 客戶端斷開連接
                            println!("Connection closed: {:?}", self.connections[&token].peer_addr()?);
                            let mut stream = self.connections.remove(&token).ok_or(SErr("Connection not found"))?;
                            self.event_loop.borrow_mut().registry().deregister(&mut stream)?;
                            return Ok(());
                        }
                        Ok(n) => {
                            // 輸出收到的數據
                            let data = String::from_utf8_lossy(&buffer[..n]);
                            println!("Received data from {}: {}", self.connections[&token].peer_addr()?, data);
                        }
                        Err(ref e) if e.kind() == std::io::ErrorKind::WouldBlock => return Ok(()),
                        Err(e) => return Err(e.into()),
                    }
                }
            }
        }
    }
}

fn main() -> Result<(), Box<dyn std::error::Error>> {
    // 建立事件循環
    let event_loop = Rc::new(RefCell::new(Poll::new()?));

    // 建立 TCP 監聽器
    let address = "127.0.0.1:8080".parse::<SocketAddr>()?;
    let mut listener = TcpListener::bind(address)?;
    event_loop
        .borrow_mut()
        .registry()
        .register(&mut listener, SERVER, Interest::READABLE)?;

    let mut my_server = MyServer::new(listener, event_loop.clone());

    println!("Server listening on {}", address);

    let mut events = Events::with_capacity(1024);

    loop {
        if let Err(err) = event_loop.borrow_mut().poll(&mut events, None) {
            if err.kind() == std::io::ErrorKind::Interrupted {
                continue;
            }
            return Err(err.into());
        }

        println!("new event");
        for event in &events {
            my_server.handle_event(event)?;
        }
    }
}