rust tokio

#![feature(async_await)]
use tokio::{prelude::*, net::TcpListener};

#[tokio::main]
#[allow(non_upper_case_globals, deprecated)]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let addr = "0.0.0.0:12345".parse()?;
    let mut listener = TcpListener::bind(&addr).unwrap();

    const num_responses: usize = 64 * 1024;
    const response: &[u8] = b"HTTP/1.1 200 Ok\r\nContent-Length: 11\r\n\r\nHello World";
    let mut data = Vec::with_capacity(num_responses * response.len());
    for _ in 0..num_responses {
        data.extend_from_slice(response);
    }

    loop {
        let (mut socket, _) = listener.accept().await?;
        let data_ptr = data.as_mut_ptr() as usize;
        socket.set_nodelay(true)?;

        tokio::spawn(async move {
            let mut buf = [unsafe { std::mem::uninitialized() }; 64 * 1024];
            let data = unsafe { std::slice::from_raw_parts(data_ptr as *mut u8, num_responses * response.len()) };
            loop {
                match socket.read(&mut buf).await {
                    Ok(0) | Err(_) => return,
                    Ok(_) => if socket.write_all(&data).await.is_err() { return }
                }
            }
        });
    }
}