uci: threaded setup

Properly (I hope so) thread standard input and engine communications.

src/engine.rs

@@ -23,17 +23,18 @@ pub enum Mode {
     // No mode, sit here and do nothing.
     No,
     // UCI mode: listen to Cmds, send Uci::Cmd::Engine commands.
-    Uci(mpsc::Receiver<Cmd>, mpsc::Sender<uci::Cmd>),
+    Uci(mpsc::Sender<uci::Cmd>, mpsc::Receiver<Cmd>),
 }
 
 #[derive(Debug)]
 pub enum Cmd {
     // Commands that can be received by the engine.
     Ping(String),                         // Test if the engine is responding.
+    UciChannel(mpsc::Sender<Cmd>),        // Provide a sender to UCI to start receiving commands.
     UciPosition(Vec<uci::PositionArgs>),  // UCI "position" command.
 
     // Commands that can be sent by the engine.
-    Pong(String),  // Answer a Ping command with the same payload.
+
 }
 
 pub const CASTLING_WH_K: u8 = 0b00000001;
@@ -43,7 +44,7 @@ pub const CASTLING_BL_Q: u8 = 0b00001000;
 pub const CASTLING_MASK: u8 = 0b00001111;
 
 impl Engine {
-    pub fn new(mode: Mode) -> Engine {
+    pub fn new() -> Engine {
         Engine {
             board: board::new_empty(),
             color: board::SQ_WH,
@@ -51,20 +52,32 @@ impl Engine {
             en_passant: None,
             halfmove: 0,
             fullmove: 1,
-            mode,
+            mode: Mode::No,
         }
     }
 
+    /// Setup engine for UCI communication.
+    pub fn setup_uci(&mut self, uci_s: mpsc::Sender<uci::Cmd>) {
+        // Create a channel to receive commands from Uci.
+        let (engine_s, engine_r) = mpsc::channel();
+        uci_s.send(uci::Cmd::Engine(Cmd::UciChannel(engine_s))).unwrap();
+        self.mode = Mode::Uci(uci_s, engine_r);
+        self.listen();
+    }
+
     /// Listen for incoming commands.
     ///
     /// In UCI mode, read incoming Cmds over the MPSC channel.
     /// In no modes, stop listening immediately.
     pub fn listen(&mut self) {
         loop {
-            match self.mode {
+            match &self.mode {
                 Mode::No => break,
-                Mode::Uci(rx, tx) => {
+                Mode::Uci(tx, rx) => {
-                    self.recv_uci(rx, tx);
+                    match rx.recv() {
+                        Ok(c) => eprintln!("Unhandled command: {:?}", c),
+                        Err(e) => eprintln!("Engine recv failure: {}", e),
+                    }
                 }
             }
         }
@@ -131,13 +144,4 @@ impl Engine {
         let best_move = moves.iter().choose(&mut rng).unwrap();
         *best_move
     }
-
-    /// Receive a command from Uci.
-    pub fn recv_uci(&mut self, rx: mpsc::Receiver<Cmd>, tx: mpsc::Sender<uci::Cmd>) {
-        match rx.recv() {
-            Ok(Cmd::Ping(s)) => tx.send(uci::Cmd::Engine(Cmd::Pong(s))).unwrap(),
-            Ok(c) => eprintln!("Unhandled command: {:?}", c),
-            Err(e) => eprintln!("Engine recv failure: {}", e),
-        }
-    }
 }

src/main.rs

@@ -20,9 +20,9 @@ fn main() {
                 .possible_values(&["w", "white", "b", "black"])))
         .subcommand(SubCommand::with_name("uci")
             .about("Start engine in UCI mode")
-            .arg(Arg::with_name("output")
+            .arg(Arg::with_name("log_file")
-                .help("Log file path")
+                .help("Log file path (default is stderr)")
-                .short("o").long("output").takes_value(true).required(false)))
+                .long("log-file").takes_value(true).required(false)))
         .get_matches();
 
     process::exit(match matches.subcommand() {

src/uci.rs

@@ -66,14 +66,15 @@ impl Uci {
     /// Start a new UCI listening for standard input.
     pub fn start(output: Option<&str>) {
         // Create the UCI queue, both for standard IO and for engine communication.
-        let (uci_tx, uci_rx): (mpsc::Sender<Cmd>, mpsc::Receiver<Cmd>) = mpsc::channel();
+        let (uci_s, uci_r): (mpsc::Sender<Cmd>, mpsc::Receiver<Cmd>) = mpsc::channel();
+        let stdin_tx = uci_s.clone();
         thread::spawn(move || {
-            read_stdin(uci_tx);
+            Uci::read_stdin(stdin_tx);
         });
 
         let mut uci = Uci {
             state: State::Init,
-            cmd_channel: (uci_tx, uci_rx),
+            cmd_channel: (uci_s, uci_r),
             engine_in: None,
             logfile: None,
         };
@@ -93,12 +94,13 @@ impl Uci {
         loop {
             match self.cmd_channel.1.recv() {
                 Ok(Cmd::Stdin(cmd)) => {
+                    self.log(format!("UCI >>> {}", cmd));
                     if !self.handle_command(&parse_command(&cmd)) {
                         break
                     }
                 }
                 Ok(Cmd::Engine(cmd)) => {
-                    // TODO
+                    self.handle_engine_command(&cmd);
                 }
                 Err(e) => self.log(format!("Can't read commands: {}", e))
             }
@@ -118,12 +120,29 @@ impl Uci {
         }
     }
 
-    /// Read a command from the interface.
+    /// Read lines over stdin, notifying over an MPSC channel.
-    fn receive(&mut self) -> Option<String> {
+    ///
+    /// As it is not trivial to add a timeout, or overly complicated
+    /// to break the loop with a second channel, simply stop listening
+    /// when the UCI "quit" command is received.
+    ///
+    /// This is not an Uci method as it does not need to act on the
+    /// instance itself.
+    pub fn read_stdin(tx: mpsc::Sender<Cmd>) {
         let mut s = String::new();
+        loop {
             match io::stdin().read_line(&mut s) {
-            Ok(_) => { self.log(format!(">>> {}", s.trim_end())); Some(s.trim().to_string()) }
+                Ok(_) => {
-            Err(e) => { self.log(format!("Failed to read input: {:?}", e)); None }
+                    let s = s.trim();
+                    tx.send(Cmd::Stdin(s.to_string())).unwrap();
+                    if s == "quit" {
+                        break;
+                    }
+                }
+                Err(e) => {
+                    eprintln!("Failed to read input: {:?}", e);
+                }
+            }
         }
     }
 
@@ -133,7 +152,7 @@ impl Uci {
         println!("{}", s);
     }
 
-    /// Handle an UCI command, return false if engine should stop listening.
+    /// Handle an UCI command, return false if it should stop listening.
     fn handle_command(&mut self, cmd: &UciCmd) -> bool {
         match cmd {
             UciCmd::Uci => if self.state == State::Init {
@@ -150,11 +169,23 @@ impl Uci {
             UciCmd::Go(g) => if self.state == State::Ready { self.go(g) }
             UciCmd::Quit => return false,
             UciCmd::Unknown(c) => { self.log(format!("Unknown command: {}", c)); }
-            _ => {}
         }
         true
     }
 
+    /// Handle an engine command.
+    fn handle_engine_command(&mut self, cmd: &engine::Cmd) {
+        match cmd {
+            engine::Cmd::UciChannel(s) => {
+                self.engine_in = Some(s.to_owned());
+                // Send a ping to the engine to ensure communication.
+                let ping = engine::Cmd::Ping("test".to_string());
+                self.engine_in.as_ref().unwrap().send(ping).unwrap();
+            }
+            _ => {}
+        }
+    }
+
     /// Send IDs to interface.
     fn send_identities(&mut self) {
         self.send(&format!("id name {}", VATU_NAME));
@@ -163,17 +194,11 @@ impl Uci {
     }
 
     fn setup_engine(&mut self) {
-        // Create the channel to send commands to the engine.
+        let uci_s = self.cmd_channel.0.clone();
-        let (uci_out, engine_in): (mpsc::Sender<engine::Cmd>, mpsc::Receiver<engine::Cmd>) =
-            mpsc::channel();
-        self.engine_in = Some(uci_out);
-        // Pass the general Uci receiver to the engine as well.
-        let engine_out = self.cmd_channel.0;
         thread::spawn(move || {
-            let mut engine = engine::Engine::new(engine::Mode::Uci(engine_in, engine_out));
+            let mut engine = engine::Engine::new();
-            engine.listen();
+            engine.setup_uci(uci_s);
         });
-        self.engine_in.as_ref().unwrap().send(engine::Cmd::Ping("test".to_string()));
         self.state = State::Ready;
     }
 
@@ -226,28 +251,6 @@ impl Uci {
     }
 }
 
-/// Read lines over stdin, notifying over an MPSC channel.
-///
-/// As it is not trivial to add a timeout, or overly complicated to
-/// break the loop with a second channel, simply stop listening when
-/// the UCI "quit" command is received.
-pub fn read_stdin(tx: mpsc::Sender<Cmd>) {
-    let mut s = String::new();
-    loop {
-        match io::stdin().read_line(&mut s) {
-            Ok(_) => {
-                let s = s.trim();
-                tx.send(Cmd::Stdin(s.to_string()));
-                if s == "quit" {
-                    break;
-                }
-            }
-            Err(e) => {
-                eprintln!("Failed to read input: {:?}", e);
-            }
-        }
-    }
-}
 
 /// Parse an UCI command.
 fn parse_command(s: &str) -> UciCmd {