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|
use std::{
collections::hash_map::{Entry, HashMap},
sync::Arc,
};
use futures::{channel::mpsc, select, FutureExt, SinkExt};
use async_std::{
io::BufReader,
net::{TcpListener, TcpStream, ToSocketAddrs},
prelude::*,
task,
};
type Result<T> = std::result::Result<T, Box<dyn std::error::Error + Send + Sync>>;
type Sender<T> = mpsc::UnboundedSender<T>;
type Receiver<T> = mpsc::UnboundedReceiver<T>;
#[derive(Debug)]
enum Void {}
pub(crate) fn main() -> Result<()> {
task::block_on(accept_loop("127.0.0.1:8080"))
}
async fn accept_loop(addr: impl ToSocketAddrs) -> Result<()> {
let listener = TcpListener::bind(addr).await?;
let (broker_sender, broker_receiver) = mpsc::unbounded();
let broker = task::spawn(broker_loop(broker_receiver));
let mut incoming = listener.incoming();
while let Some(stream) = incoming.next().await {
let stream = stream?;
println!("Accepting from: {}", stream.peer_addr()?);
spawn_and_log_error(connection_loop(broker_sender.clone(), stream));
}
drop(broker_sender);
broker.await;
Ok(())
}
async fn connection_loop(mut broker: Sender<Event>, stream: TcpStream) -> Result<()> {
let stream = Arc::new(stream);
let reader = BufReader::new(&*stream);
let mut lines = reader.lines();
let name = match lines.next().await {
None => return Err("peer disconnected immediately".into()),
Some(line) => line?,
};
let (_shutdown_sender, shutdown_receiver) = mpsc::unbounded::<Void>();
broker
.send(Event::NewPeer {
name: name.clone(),
stream: Arc::clone(&stream),
shutdown: shutdown_receiver,
})
.await
.unwrap();
while let Some(line) = lines.next().await {
let line = line?;
let (dest, msg) = match line.find(':') {
None => continue,
Some(idx) => (&line[..idx], line[idx + 1..].trim()),
};
let dest: Vec<String> = dest
.split(',')
.map(|name| name.trim().to_string())
.collect();
let msg: String = msg.trim().to_string();
broker
.send(Event::Message {
from: name.clone(),
to: dest,
msg,
})
.await
.unwrap();
}
Ok(())
}
async fn connection_writer_loop(
messages: &mut Receiver<String>,
stream: Arc<TcpStream>,
mut shutdown: Receiver<Void>,
) -> Result<()> {
let mut stream = &*stream;
loop {
select! {
msg = messages.next().fuse() => match msg {
Some(msg) => stream.write_all(msg.as_bytes()).await?,
None => break,
},
void = shutdown.next().fuse() => match void {
#[allow(unreachable_patterns)]
Some(void) => match void {},
None => break,
}
}
}
Ok(())
}
#[derive(Debug)]
enum Event {
NewPeer {
name: String,
stream: Arc<TcpStream>,
shutdown: Receiver<Void>,
},
Message {
from: String,
to: Vec<String>,
msg: String,
},
}
async fn broker_loop(mut events: Receiver<Event>) {
let (disconnect_sender, mut disconnect_receiver) =
mpsc::unbounded::<(String, Receiver<String>)>();
let mut peers: HashMap<String, Sender<String>> = HashMap::new();
loop {
let event = select! {
event = events.next().fuse() => match event {
None => break,
Some(event) => event,
},
disconnect = disconnect_receiver.next().fuse() => {
let (name, _pending_messages) = disconnect.unwrap();
assert!(peers.remove(&name).is_some());
continue;
},
};
match event {
Event::Message { from, to, msg } => {
for addr in to {
if let Some(peer) = peers.get_mut(&addr) {
let msg = format!("from {}: {}\n", from, msg);
peer.send(msg).await.unwrap();
}
}
}
Event::NewPeer {
name,
stream,
shutdown,
} => match peers.entry(name.clone()) {
Entry::Occupied(..) => (),
Entry::Vacant(entry) => {
let (client_sender, mut client_receiver) = mpsc::unbounded();
entry.insert(client_sender);
let mut disconnect_sender = disconnect_sender.clone();
spawn_and_log_error(async move {
let res =
connection_writer_loop(&mut client_receiver, stream, shutdown).await;
disconnect_sender
.send((name, client_receiver))
.await
.unwrap();
res
});
}
},
}
}
drop(peers);
drop(disconnect_sender);
while let Some((_name, _pending_messages)) = disconnect_receiver.next().await {}
}
fn spawn_and_log_error<F>(fut: F) -> task::JoinHandle<()>
where
F: Future<Output = Result<()>> + Send + 'static,
{
task::spawn(async move {
if let Err(e) = fut.await {
eprintln!("{}", e)
}
})
}
|
