tokio/examples/echo.rs

//! An echo server that just writes back everything that's written to it.

extern crate env_logger;
extern crate futures;
extern crate tokio_core;

use std::env;
use std::net::SocketAddr;

use futures::Future;
use futures::stream::Stream;
use tokio_core::Loop;
use tokio_core::io::{copy, TaskIo};

fn main() {
    env_logger::init().unwrap();
    let addr = env::args().nth(1).unwrap_or("127.0.0.1:8080".to_string());
    let addr = addr.parse::<SocketAddr>().unwrap();

    // Create the event loop that will drive this server
    let mut l = Loop::new().unwrap();
    let pin = l.pin();

    // Create a TCP listener which will listen for incoming connections
    let server = l.handle().tcp_listen(&addr);

    let done = server.and_then(move |socket| {
        // Once we've got the TCP listener, inform that we have it
        println!("Listening on: {}", addr);

        // Pull out the stream of incoming connections and then for each new
        // one spin up a new task copying data.
        //
        // We use the `io::copy` future to copy all data from the
        // reading half onto the writing half.
        socket.incoming().for_each(move |(socket, addr)| {
            let socket = futures::lazy(|| futures::finished(TaskIo::new(socket)));
            let pair = socket.map(|s| s.split());
            let amt = pair.and_then(|(reader, writer)| copy(reader, writer));

            // Once all that is done we print out how much we wrote, and then
            // critically we *spawn* this future which allows it to run
            // concurrently with other connections.
            let msg = amt.map(move |amt| {
                println!("wrote {} bytes to {}", amt, addr)
            }).map_err(|e| {
                panic!("error: {}", e);
            });
            pin.spawn(msg);

            Ok(())
        })
    });
    l.run(done).unwrap();
}