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async-tungstenite/examples/server.rs

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//! A chat server that broadcasts a message to all connections.
//!
//! This is a simple line-based server which accepts WebSocket connections,
//! reads lines from those connections, and broadcasts the lines to all other
//! connected clients.
//!
//! You can test this out by running:
//!
//! cargo run --example server 127.0.0.1:12345
//!
//! And then in another window run:
//!
//! cargo run --example client ws://127.0.0.1:12345/
//!
//! You can run the second command in multiple windows and then chat between the
//! two, seeing the messages from the other client as they're received. For all
//! connected clients they'll all join the same room and see everyone else's
//! messages.
extern crate futures;
extern crate tokio_core;
extern crate tokio_tungstenite;
extern crate tungstenite;
use std::cell::RefCell;
use std::collections::HashMap;
use std::env;
use std::io::{Error, ErrorKind};
use std::rc::Rc;
use futures::stream::Stream;
use futures::Future;
use tokio_core::net::TcpListener;
use tokio_core::reactor::Core;
use tungstenite::protocol::Message;
use tokio_tungstenite::accept_async;
fn main() {
let addr = env::args().nth(1).unwrap_or("127.0.0.1:8080".to_string());
let addr = addr.parse().unwrap();
// Create the event loop and TCP listener we'll accept connections on.
let mut core = Core::new().unwrap();
let handle = core.handle();
let socket = TcpListener::bind(&addr, &handle).unwrap();
println!("Listening on: {}", addr);
// This is a single-threaded server, so we can just use Rc and RefCell to
// store the map of all connections we know about.
let connections = Rc::new(RefCell::new(HashMap::new()));
let srv = socket.incoming().for_each(|(stream, addr)| {
// We have to clone both of these values, because the `and_then`
// function billow constructs a new future, `and_then` requires
// `FnOnce`, so we construct a move closure to move the
// environment inside the future (AndThen future may overlive our
// `for_each` future).
let connections_inner = connections.clone();
let handle_inner = handle.clone();
accept_async(stream).and_then(move |ws_stream| {
println!("New WebSocket connection: {}", addr);
// Create a channel for our stream, which other sockets will use to
// send us messages. Then register our address with the stream to send
// data to us.
let (tx, rx) = futures::sync::mpsc::unbounded();
connections_inner.borrow_mut().insert(addr, tx);
// Let's split the WebSocket stream, so we can work with the
// reading and writing halves separately.
let (sink, stream) = ws_stream.split();
// Whenever we receive a message from the client, we print it and
// send to other clients, excluding the sender.
let connections = connections_inner.clone();
let ws_reader = stream.for_each(move |message: Message| {
println!("Received a message from {}: {}", addr, message);
// For each open connection except the sender, send the
// string via the channel.
let mut conns = connections.borrow_mut();
let iter = conns.iter_mut()
.filter(|&(&k, _)| k != addr)
.map(|(_, v)| v);
for tx in iter {
tx.send(message.clone()).unwrap();
}
Ok(())
});
// Whenever we receive a string on the Receiver, we write it to
// `WriteHalf<WebSocketStream>`.
let ws_writer = rx.fold(sink, |mut sink, msg| {
use futures::Sink;
sink.start_send(msg).unwrap();
Ok(sink)
});
// Now that we've got futures representing each half of the socket, we
// use the `select` combinator to wait for either half to be done to
// tear down the other. Then we spawn off the result.
let connection = ws_reader.map(|_| ()).map_err(|_| ())
.select(ws_writer.map(|_| ()).map_err(|_| ()));
handle_inner.spawn(connection.then(move |_| {
connections_inner.borrow_mut().remove(&addr);
println!("Connection {} closed.", addr);
Ok(())
}));
Ok(())
}).map_err(|e| {
println!("Error during the websocket handshake occurred: {}", e);
Error::new(ErrorKind::Other, e)
})
});
// Execute server.
core.run(srv).unwrap();
}