|
| 1 | +use std::{ |
| 2 | + collections::hash_map::{Entry, HashMap}, |
| 3 | + sync::Arc, |
| 4 | +}; |
| 5 | + |
| 6 | +use futures::{channel::mpsc, select, FutureExt, SinkExt}; |
| 7 | + |
| 8 | +use async_std::{ |
| 9 | + io::BufReader, |
| 10 | + net::{TcpListener, TcpStream, ToSocketAddrs}, |
| 11 | + prelude::*, |
| 12 | + task, |
| 13 | +}; |
| 14 | + |
| 15 | +type Result<T> = std::result::Result<T, Box<dyn std::error::Error + Send + Sync>>; |
| 16 | +type Sender<T> = mpsc::UnboundedSender<T>; |
| 17 | +type Receiver<T> = mpsc::UnboundedReceiver<T>; |
| 18 | + |
| 19 | +#[derive(Debug)] |
| 20 | +enum Void {} |
| 21 | + |
| 22 | +pub(crate) fn main() -> Result<()> { |
| 23 | + task::block_on(accept_loop("127.0.0.1:8080")) |
| 24 | +} |
| 25 | + |
| 26 | +async fn accept_loop(addr: impl ToSocketAddrs) -> Result<()> { |
| 27 | + let listener = TcpListener::bind(addr).await?; |
| 28 | + |
| 29 | + let (broker_sender, broker_receiver) = mpsc::unbounded(); |
| 30 | + let broker = task::spawn(broker_loop(broker_receiver)); |
| 31 | + let mut incoming = listener.incoming(); |
| 32 | + while let Some(stream) = incoming.next().await { |
| 33 | + let stream = stream?; |
| 34 | + println!("Accepting from: {}", stream.peer_addr()?); |
| 35 | + spawn_and_log_error(connection_loop(broker_sender.clone(), stream)); |
| 36 | + } |
| 37 | + drop(broker_sender); |
| 38 | + broker.await; |
| 39 | + Ok(()) |
| 40 | +} |
| 41 | + |
| 42 | +async fn connection_loop(mut broker: Sender<Event>, stream: TcpStream) -> Result<()> { |
| 43 | + let stream = Arc::new(stream); |
| 44 | + let reader = BufReader::new(&*stream); |
| 45 | + let mut lines = reader.lines(); |
| 46 | + |
| 47 | + let name = match lines.next().await { |
| 48 | + None => Err("peer disconnected immediately")?, |
| 49 | + Some(line) => line?, |
| 50 | + }; |
| 51 | + let (_shutdown_sender, shutdown_receiver) = mpsc::unbounded::<Void>(); |
| 52 | + broker |
| 53 | + .send(Event::NewPeer { |
| 54 | + name: name.clone(), |
| 55 | + stream: Arc::clone(&stream), |
| 56 | + shutdown: shutdown_receiver, |
| 57 | + }) |
| 58 | + .await |
| 59 | + .unwrap(); |
| 60 | + |
| 61 | + while let Some(line) = lines.next().await { |
| 62 | + let line = line?; |
| 63 | + let (dest, msg) = match line.find(':') { |
| 64 | + None => continue, |
| 65 | + Some(idx) => (&line[..idx], line[idx + 1..].trim()), |
| 66 | + }; |
| 67 | + let dest: Vec<String> = dest |
| 68 | + .split(',') |
| 69 | + .map(|name| name.trim().to_string()) |
| 70 | + .collect(); |
| 71 | + let msg: String = msg.trim().to_string(); |
| 72 | + |
| 73 | + broker |
| 74 | + .send(Event::Message { |
| 75 | + from: name.clone(), |
| 76 | + to: dest, |
| 77 | + msg, |
| 78 | + }) |
| 79 | + .await |
| 80 | + .unwrap(); |
| 81 | + } |
| 82 | + |
| 83 | + Ok(()) |
| 84 | +} |
| 85 | + |
| 86 | +async fn connection_writer_loop( |
| 87 | + messages: &mut Receiver<String>, |
| 88 | + stream: Arc<TcpStream>, |
| 89 | + mut shutdown: Receiver<Void>, |
| 90 | +) -> Result<()> { |
| 91 | + let mut stream = &*stream; |
| 92 | + loop { |
| 93 | + select! { |
| 94 | + msg = messages.next().fuse() => match msg { |
| 95 | + Some(msg) => stream.write_all(msg.as_bytes()).await?, |
| 96 | + None => break, |
| 97 | + }, |
| 98 | + void = shutdown.next().fuse() => match void { |
| 99 | + Some(void) => match void {}, |
| 100 | + None => break, |
| 101 | + } |
| 102 | + } |
| 103 | + } |
| 104 | + Ok(()) |
| 105 | +} |
| 106 | + |
| 107 | +#[derive(Debug)] |
| 108 | +enum Event { |
| 109 | + NewPeer { |
| 110 | + name: String, |
| 111 | + stream: Arc<TcpStream>, |
| 112 | + shutdown: Receiver<Void>, |
| 113 | + }, |
| 114 | + Message { |
| 115 | + from: String, |
| 116 | + to: Vec<String>, |
| 117 | + msg: String, |
| 118 | + }, |
| 119 | +} |
| 120 | + |
| 121 | +async fn broker_loop(mut events: Receiver<Event>) { |
| 122 | + let (disconnect_sender, mut disconnect_receiver) = |
| 123 | + mpsc::unbounded::<(String, Receiver<String>)>(); |
| 124 | + let mut peers: HashMap<String, Sender<String>> = HashMap::new(); |
| 125 | + |
| 126 | + loop { |
| 127 | + let event = select! { |
| 128 | + event = events.next().fuse() => match event { |
| 129 | + None => break, |
| 130 | + Some(event) => event, |
| 131 | + }, |
| 132 | + disconnect = disconnect_receiver.next().fuse() => { |
| 133 | + let (name, _pending_messages) = disconnect.unwrap(); |
| 134 | + assert!(peers.remove(&name).is_some()); |
| 135 | + continue; |
| 136 | + }, |
| 137 | + }; |
| 138 | + match event { |
| 139 | + Event::Message { from, to, msg } => { |
| 140 | + for addr in to { |
| 141 | + if let Some(peer) = peers.get_mut(&addr) { |
| 142 | + peer.send(format!("from {}: {}\n", from, msg)) |
| 143 | + .await |
| 144 | + .unwrap() |
| 145 | + } |
| 146 | + } |
| 147 | + } |
| 148 | + Event::NewPeer { |
| 149 | + name, |
| 150 | + stream, |
| 151 | + shutdown, |
| 152 | + } => match peers.entry(name.clone()) { |
| 153 | + Entry::Occupied(..) => (), |
| 154 | + Entry::Vacant(entry) => { |
| 155 | + let (client_sender, mut client_receiver) = mpsc::unbounded(); |
| 156 | + entry.insert(client_sender); |
| 157 | + let mut disconnect_sender = disconnect_sender.clone(); |
| 158 | + spawn_and_log_error(async move { |
| 159 | + let res = |
| 160 | + connection_writer_loop(&mut client_receiver, stream, shutdown).await; |
| 161 | + disconnect_sender |
| 162 | + .send((name, client_receiver)) |
| 163 | + .await |
| 164 | + .unwrap(); |
| 165 | + res |
| 166 | + }); |
| 167 | + } |
| 168 | + }, |
| 169 | + } |
| 170 | + } |
| 171 | + drop(peers); |
| 172 | + drop(disconnect_sender); |
| 173 | + while let Some((_name, _pending_messages)) = disconnect_receiver.next().await {} |
| 174 | +} |
| 175 | + |
| 176 | +fn spawn_and_log_error<F>(fut: F) -> task::JoinHandle<()> |
| 177 | +where |
| 178 | + F: Future<Output = Result<()>> + Send + 'static, |
| 179 | +{ |
| 180 | + task::spawn(async move { |
| 181 | + if let Err(e) = fut.await { |
| 182 | + eprintln!("{}", e) |
| 183 | + } |
| 184 | + }) |
| 185 | +} |
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