Rust挺简单的，就是头有点冷

异步支持库

tokio

老牌集装箱

[dependencies]
# An event-driven, non-blocking I/O platform for writing asynchronous I/O backed applications. 
tokio = { version = "1.5.0", features = ["full"] }

async_std

语法更接近现代Rust

以同步的思维编写异步逻辑

async fn tcp_serv() -> ! {
    let listener = tokio::net::TcpListener::bind("0.0.0.0:2222").await.unwrap();
    loop {
        println!("wait a conn...");
        let (stream, addr) = listener.accept().await.unwrap();
        let task = async move {
            println!("user {} connected.", addr);

            let intro_time = std::time::SystemTime::now().duration_since(std::time::UNIX_EPOCH).unwrap();
            tokio::time::sleep(std::time::Duration::from_millis(8000)).await;
            let end_time = std::time::SystemTime::now().duration_since(std::time::UNIX_EPOCH).unwrap();
            let time = end_time - intro_time;

            let id = std::thread::current().id();
            stream.try_write(format!("id: {:?}, time: {:?}", id, time).to_string().as_bytes()).unwrap();
            println!("{} done.", addr);
        };
        tokio::spawn(task);
    }
}

#[tokio::main]
async fn main() -> std::io::Result<()> {
    tcp_serv().await;
    println!("Done.");
    Ok(())
}

异步有什么用

https://fasterthanli.me/articles/pin-and-suffering

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