gg-broadcast/src/main.rs

@@ -1,6 +1,7 @@
 use std::{
     collections::{HashMap, HashSet},
-    sync::{Arc, Mutex},
+    io::BufRead,
+    sync::{mpsc::channel, Arc, Mutex},
     thread,
     time::Duration,
 };
@@ -9,18 +10,28 @@ use nebkor_maelstrom::{protocol::Payload, Body, Message, Node, Runner};
 use rand::Rng;
 
 fn main() {
+    let out = std::io::stdout();
+    let std_in = Arc::new(std::io::stdin());
+
+    let (tx, rx) = channel();
+    let input = tx.clone();
+
+    let i = thread::spawn(move || {
+        let g = std_in.lock();
+        for line in g.lines().map_while(Result::ok) {
+            if let Ok(msg) = serde_json::from_str::<Message>(&line) {
+                input.send(msg).unwrap();
+            }
+        }
+    });
+
     let node = BCaster::default();
     let node = Arc::new(Mutex::new(node));
 
-    let runner = Runner::new(node);
+    let runner = Runner::new(node, out);
     let runner = &runner;
 
-    runner.run(Some(Box::new(on_init)));
-}
-
-fn on_init(runner: &Runner) {
-    let tx = runner.get_backdoor();
-    thread::spawn(move || loop {
+    let g = thread::spawn(move || loop {
         let millis = rand::thread_rng().gen_range(400..=800);
         thread::sleep(Duration::from_millis(millis));
         let body = Body::from_type("do_gossip");
@@ -30,6 +41,10 @@ fn on_init(runner: &Runner) {
         };
         tx.send(msg).unwrap();
     });
+
+    runner.run(rx, None);
+    let _ = i.join();
+    let _ = g.join();
 }
 
 #[derive(Clone, Default)]

gg-echo/src/main.rs

@@ -1,4 +1,8 @@
-use std::sync::{Arc, Mutex};
+use std::{
+    io::BufRead,
+    sync::{mpsc::channel, Arc, Mutex},
+    thread,
+};
 
 use nebkor_maelstrom::{Body, Message, Node, Runner};
 
@@ -15,11 +19,26 @@ impl Node for Echo {
 }
 
 fn main() {
+    let out = std::io::stdout();
+    let std_in = Arc::new(std::io::stdin());
+
+    let (tx, rx) = channel();
+
+    let i = thread::spawn(move || {
+        let g = std_in.lock();
+        for line in g.lines().map_while(Result::ok) {
+            if let Ok(msg) = serde_json::from_str::<Message>(&line) {
+                tx.send(msg).unwrap();
+            }
+        }
+    });
+
     let node = Echo;
 
     let node = Arc::new(Mutex::new(node));
 
-    let runner = Runner::new(node);
+    let runner = Runner::new(node, out);
 
-    runner.run(None);
+    runner.run(rx, None);
+    i.join().unwrap();
 }

gg-g_counter/src/main.rs

@@ -1,17 +1,17 @@
-use std::sync::{Arc, Mutex};
+use std::{
+    rc::Rc,
+    sync::{Arc, Mutex},
+};
 
-use nebkor_maelstrom::{mk_payload, Body, Message, Node, Runner};
-
-const KEY: &str = "COUNTER";
-
-#[derive(Clone, Default)]
-struct Counter;
+use nebkor_maelstrom::{mk_payload, mk_stdin, Body, Message, Node, Runner};
 
 fn main() {
     let node = Counter;
     let node = Arc::new(Mutex::new(node));
 
-    let runner = Runner::new(node);
+    let runner = Rc::new(Runner::new(node));
+
+    let (i, _, rx) = mk_stdin();
 
     let on_init = |rnr: &Runner| {
         let payload = mk_payload(&[
@@ -26,56 +26,62 @@ fn main() {
 
     let on_init = Box::new(on_init);
 
-    runner.run(Some(on_init));
+    runner.run(rx, Some(on_init));
+    i.join().unwrap();
 }
 
+const KEY: &str = "COUNTER";
+
+#[derive(Clone, Default)]
+struct Counter;
+
 impl Node for Counter {
-    fn handle<'slf>(&'slf mut self, runner: &'slf Runner, req: Message) {
-        let read_payload = mk_payload(&[("key", KEY.into())]);
-        let read_body = Body::from_type("read").with_payload(read_payload);
+    fn handle<'slf>(&'slf mut self, runner: &'slf Rc<Runner>, req: Message) {
         let typ = req.body.typ.as_str();
-        //let frm = req.src.clone();
-        //let msg_id = req.body.msg_id.to_owned();
+        let frm = req.src.clone();
+        let msg_id = req.body.msg_id.to_owned();
         match typ {
             "add" => {
+                let read_runner = runner.clone();
+                let cas_runner = runner.clone();
+                let add_req = req.clone();
+
+                let cas_handler = move |_msg: Message| {
+                    let req = add_req;
+                    cas_runner.reply(&req, Body::from_type("add_ok"));
+                };
+
                 let delta = req.body.payload.get("delta").unwrap().as_i64().unwrap();
-                let cur = runner
-                    .rpc("seq-kv", read_body)
-                    .recv()
-                    .unwrap()
-                    .body
-                    .payload
-                    .get("value")
-                    .cloned()
-                    .unwrap()
-                    .as_i64()
-                    .unwrap();
-                let cas_payload = mk_payload(&[
+                let read_handler = move |msg: Message| {
+                    let value = msg.body.payload.get("value").unwrap().as_i64().unwrap();
+                    let payload = mk_payload(&[
+                        ("from", value.into()),
+                        ("to", (value + delta).into()),
                         ("key", KEY.into()),
-                    ("from", cur.into()),
-                    ("to", (cur + delta).into()),
                     ]);
-                // ERRORS BE HERE
-                runner
-                    .rpc("seq-kv", Body::from_type("cas").with_payload(cas_payload))
-                    .recv()
-                    .unwrap();
-                runner.reply(&req, Body::from_type("add_ok"));
-            }
-            "read" => {
+                    let body = Body::from_type("cas").with_payload(payload);
+                    read_runner.rpc("seq-kv", body, Box::new(cas_handler));
+                };
+                // kick it off by calling "read" on seq-kv:
                 let payload = mk_payload(&[("key", KEY.into())]);
                 let body = Body::from_type("read").with_payload(payload);
-                let val = runner
-                    .rpc("seq-kv", body)
-                    .recv()
-                    .unwrap()
-                    .body
-                    .payload
-                    .get("value")
-                    .cloned()
-                    .unwrap();
-                let body = Body::from_type("read_ok").with_payload(mk_payload(&[("value", val)]));
-                runner.reply(&req, body);
+                runner.rpc("seq-kv", body, Box::new(read_handler));
+            }
+            "read" => {
+                let rn = runner.clone();
+                let h = move |msg: Message| {
+                    let src = frm.clone();
+                    let value = msg.body.payload.get("value").unwrap().as_i64().unwrap();
+                    let irt = msg_id;
+                    let payload = mk_payload(&[("value", value.into())]);
+                    let body = Body::from_type("read_ok")
+                        .with_in_reply_to(irt)
+                        .with_payload(payload);
+                    rn.send(&src, body);
+                };
+                let payload = mk_payload(&[("key", KEY.into())]);
+                let body = Body::from_type("read").with_payload(payload);
+                runner.rpc("seq-kv", body, Box::new(h));
             }
             _ => {
                 eprintln!("unknown type: {req:?}");

gg-uid/src/main.rs

@@ -1,14 +1,33 @@
-use std::sync::{Arc, Mutex};
+use std::{
+    io::BufRead,
+    sync::{mpsc::channel, Arc, Mutex},
+    thread,
+};
 
 use nebkor_maelstrom::{protocol::Payload, Body, Message, Node, Runner};
 
 fn main() {
+    let out = std::io::stdout();
+    let std_in = Arc::new(std::io::stdin());
+
+    let (tx, rx) = channel();
+
+    let i = thread::spawn(move || {
+        let g = std_in.lock();
+        for line in g.lines().map_while(Result::ok) {
+            if let Ok(msg) = serde_json::from_str::<Message>(&line) {
+                tx.send(msg).unwrap();
+            }
+        }
+    });
+
     let node = GenUid;
     let node = Arc::new(Mutex::new(node));
 
-    let runner = Runner::new(node);
+    let runner = Runner::new(node, out);
 
-    runner.run(None);
+    runner.run(rx, None);
+    i.join().unwrap();
 }
 
 #[derive(Clone, Default)]

nebkor-maelstrom/src/lib.rs

@@ -1,12 +1,13 @@
 use std::{
     collections::HashMap,
-    io::{BufRead, Write},
+    io::{BufRead, Stdout, Write},
+    rc::Rc,
     sync::{
         atomic::{AtomicU64, AtomicUsize, Ordering},
         mpsc::{channel, Receiver, Sender},
-        Arc, Mutex, OnceLock,
+        Arc, LazyLock, Mutex, OnceLock,
     },
-    thread::{self},
+    thread::{self, JoinHandle},
 };
 
 pub mod protocol;
@@ -17,57 +18,25 @@ use serde_json::Value;
 pub mod kv;
 
 pub type DynNode = Arc<Mutex<dyn Node>>;
+pub type Handler = Box<dyn FnOnce(Message)>; // -> Result<Option<Value>>>;
 pub type OnInit = Box<dyn Fn(&Runner)>;
 
 pub type Result<T> = std::result::Result<T, ErrorCode>;
 
-pub type RpcPromise = Receiver<Message>;
-
 static MSG_ID: AtomicU64 = AtomicU64::new(0);
+static OUTPUT: LazyLock<Stdout> = LazyLock::new(std::io::stdout);
 
 pub trait Node {
-    fn handle(&mut self, runner: &Runner, msg: Message);
-}
-
-#[derive(Debug, Clone)]
-pub struct Network {
-    promises: Arc<Mutex<HashMap<u64, Sender<Message>>>>,
-    node_output_tx: Sender<Message>,
-}
-
-impl Network {
-    pub fn new() -> (Self, Receiver<Message>) {
-        let (node_output_tx, node_output_rx) = channel();
-        let net = Self {
-            node_output_tx,
-            promises: Arc::new(Mutex::new(HashMap::default())),
-        };
-        (net, node_output_rx)
-    }
-
-    pub fn send(&self, msg: Message) {
-        self.node_output_tx.send(msg).unwrap();
-    }
-
-    pub fn rpc(&self, msg: Message) -> RpcPromise {
-        let (tx, rx) = channel();
-        {
-            let msg_id = msg.body.msg_id;
-            let mut g = self.promises.lock().unwrap();
-            g.insert(msg_id, tx);
-        }
-        self.send(msg);
-        rx
-    }
+    fn handle(&mut self, runner: &Rc<Runner>, msg: Message);
 }
 
+#[derive(Clone)]
 pub struct Runner {
     node: DynNode,
     node_id: OnceLock<String>,
     nodes: OnceLock<Vec<String>>,
-    network: OnceLock<Network>,
-    backdoor: OnceLock<Sender<Message>>,
     steps: Arc<AtomicUsize>,
+    handlers: Arc<Mutex<HashMap<u64, Handler>>>,
 }
 
 impl Runner {
@@ -76,87 +45,44 @@ impl Runner {
             node,
             nodes: OnceLock::new(),
             node_id: OnceLock::new(),
-            network: OnceLock::new(),
-            backdoor: OnceLock::new(),
             steps: Arc::new(AtomicUsize::new(0)),
+            handlers: Default::default(),
         }
     }
 
-    pub fn run(&self, on_init: Option<OnInit>) {
-        let (stdin_tx, stdin_rx) = channel();
-        let (stdout_tx, stdout_rx) = channel();
-
-        thread::spawn(move || {
-            let stdin = std::io::stdin().lock().lines();
-            for line in stdin {
-                stdin_tx.send(line.unwrap()).unwrap();
-            }
-        });
-
-        thread::spawn(move || {
-            let mut stdout = std::io::stdout().lock();
-            for msg in stdout_rx {
-                writeln!(&mut stdout, "{msg}").unwrap();
-            }
-        });
-
-        self.run_internal(stdout_tx, stdin_rx, on_init);
-    }
-
-    fn run_internal(
-        &self,
-        stdout_tx: Sender<String>,
-        stdin_rx: Receiver<String>,
-        on_init: Option<OnInit>,
-    ) {
-        let (network, node_receiver) = Network::new();
-        let _ = self.network.get_or_init(|| network.clone());
-        self.run_output(stdout_tx, node_receiver);
-        self.run_input(stdin_rx, network, on_init);
-    }
-
-    fn run_input(&self, stdin_rx: Receiver<String>, network: Network, on_init: Option<OnInit>) {
-        let (json_tx, json_rx) = channel();
-        let _ = self.backdoor.get_or_init(|| json_tx.clone());
-
-        thread::spawn(move || {
-            for line in stdin_rx {
-                let msg: Message = serde_json::from_str(&line).unwrap();
-                let irt = msg.body.in_reply_to;
-                if let Some(tx) = network.promises.lock().unwrap().remove(&irt) {
-                    tx.send(msg).unwrap();
-                } else {
-                    json_tx.send(msg).unwrap();
-                }
-            }
-        });
-
-        for msg in json_rx {
-            let mut node = self.node.lock().unwrap();
-            if msg.body.typ.as_str() == "init" {
+    pub fn run(self: &Rc<Self>, input: Receiver<Message>, on_init: Option<OnInit>) {
+        for msg in input.iter() {
+            let typ = &msg.body.typ;
+            if let "init" = typ.as_str() {
                 self.init(&msg);
                 let body = Body::from_type("init_ok");
                 self.reply(&msg, body);
-                if let Some(ref on_init) = on_init {
-                    on_init(self);
+                if let Some(ref h) = on_init {
+                    h(self);
                 }
             } else {
-                node.handle(self, msg);
+                let irt = msg.body.in_reply_to;
+                {
+                    let mut g = self.handlers.lock().unwrap();
+                    if let Some(h) = g.remove(&irt) {
+                        h(msg.clone());
+                    }
+                }
+                let mut n = self.node.lock().unwrap();
+                n.handle(self, msg);
             }
         }
     }
 
-    fn run_output(&self, stdout_tx: Sender<String>, node_output_rx: Receiver<Message>) {
-        thread::spawn(move || {
-            while let Ok(msg) = node_output_rx.recv() {
-                let msg = serde_json::to_string(&msg).unwrap();
-                stdout_tx.send(msg).unwrap();
+    pub fn rpc(&self, dest: &str, body: Body, handler: Handler) {
+        let mut body = body;
+        let msg_id = self.next_msg_id();
+        body.msg_id = msg_id;
+        {
+            let mut g = self.handlers.lock().unwrap();
+            g.insert(msg_id, handler);
         }
-        });
-    }
-
-    pub fn get_backdoor(&self) -> Sender<Message> {
-        self.backdoor.get().unwrap().clone()
+        self.send(dest, body);
     }
 
     pub fn node_id(&self) -> String {
@@ -198,10 +124,10 @@ impl Runner {
             .unwrap()
             .iter()
             .map(|s| s.as_str().unwrap().to_string())
-            .collect();
+            .collect::<Vec<_>>();
 
-        let _ = self.node_id.get_or_init(|| node_id);
-        let _ = self.nodes.get_or_init(|| nodes);
+        let _ = self.node_id.get_or_init(|| node_id.to_owned());
+        let _ = self.nodes.get_or_init(|| nodes.to_vec());
     }
 
     pub fn reply(&self, req: &Message, body: Body) {
@@ -222,21 +148,36 @@ impl Runner {
             dest: dest.to_string(),
             body,
         };
-        self.network.get().unwrap().send(msg);
+        let msg = serde_json::to_string(&msg).unwrap();
+        self.writeln(&msg);
     }
 
-    pub fn rpc(&self, dest: &str, body: Body) -> RpcPromise {
-        let mut body = body;
-        if body.msg_id == 0 {
-            body.msg_id = self.next_msg_id();
+    fn writeln(&self, msg: &str) {
+        let mut out = OUTPUT.lock();
+        let msg = format!("{msg}\n");
+        out.write_all(msg.as_bytes()).unwrap();
+        out.flush().unwrap();
     }
-        let msg = Message {
-            src: self.node_id().to_string(),
-            dest: dest.to_string(),
-            body,
-        };
-        self.network.get().unwrap().rpc(msg)
 }
+
+/// Feeds lines from stdin to the MPSC Sender, so that the Receiver can be used
+/// in the Runner::run() method. Clone the Sender if you want to inject messages
+/// into the Runner. Join the handle after `run()`.
+pub fn mk_stdin() -> (JoinHandle<()>, Sender<Message>, Receiver<Message>) {
+    let stdin = std::io::stdin();
+    let (tx, rx) = channel();
+    let xtra_input = tx.clone();
+
+    let join = thread::spawn(move || {
+        let g = stdin.lock();
+        for line in g.lines().map_while(std::result::Result::ok) {
+            if let Ok(msg) = serde_json::from_str(&line) {
+                tx.send(msg).unwrap();
+            }
+        }
+    });
+
+    (join, xtra_input, rx)
 }
 
 pub fn mk_payload(payload: &[(&str, Value)]) -> Payload {