Clean up engine setup loop

Sources/ChessKitEngine/Engine.swift

@@ -54,7 +54,7 @@ public class Engine {
     /// - parameter multipv: The number of lines the engine should return,
     /// sent via the `"MultiPV"` UCI option.
     /// - parameter completion: The completion handler that is called when
-    /// the engine set up is complete. You must wait for this to be called
+    /// the engine setup is complete. You must wait for this to be called
     /// before sending further commands to the engine.
     ///
     /// This must be called before sending any commands
@@ -63,55 +63,45 @@ public class Engine {
         messenger.responseHandler = { [weak self] response in
             guard let self else { return }
 
-            Task { @MainActor in
-                if let parsedResponse = EngineResponse(rawValue: response) {
-                    self.log(parsedResponse.rawValue)
-
-                    if parsedResponse == .uciok && !self.isRunning {
-                        self.send(command: .isready)
-                        return
+            DispatchQueue.main.async {
+                guard let parsed = EngineResponse(rawValue: response) else {
+                    if !response.isEmpty {
+                        self.log(response)
                     }
+                    return
+                }
 
-                    if parsedResponse == .readyok && !self.isRunning {
+                self.log(parsed.rawValue)
+
+                guard self.isRunning else {
+                    // engine setup loop
+                    // <uci> → <uciok> → <isready> → <readok> → complete
+                    switch parsed {
+                    case .uciok:
+                        self.send(command: .isready)
+                    case .readyok:
                         self.isRunning = true
                         self.performInitialSetup(
                             coreCount: coreCount ?? ProcessInfo.processInfo.processorCount,
                             multipv: multipv
                         )
                         completion()
-                        return
+                    default:
+                        break
                     }
-
-                    self.receiveResponse(parsedResponse)
-                } else if !response.isEmpty {
-                    self.log(response)
+                    return
                 }
+
+                self.receiveResponse(parsed)
             }
         }
 
         messenger.start()
 
-        // set UCI mode
+        // start engine setup loop
         send(command: .uci)
     }
 
-    private var initialSetupComplete = false
-
-    private func performInitialSetup(coreCount: Int, multipv: Int) {
-        guard !initialSetupComplete else { return }
-
-        // configure engine-specific options
-        type.setupCommands.forEach(send)
-
-        // configure common engine options
-        send(command: .setoption(
-            id: "Threads",
-            value: "\(max(coreCount - 1, 1))"
-        ))
-        send(command: .setoption(id: "MultiPV", value: "\(multipv)"))
-        initialSetupComplete = true
-    }
-
     /// Stops the engine.
     ///
     /// Call this to stop all engine calculation and clean up.
@@ -142,8 +132,8 @@ public class Engine {
         }
 
         queue.sync {
-            self.log(command.rawValue)
-            self.messenger.sendCommand(command.rawValue)
+            log(command.rawValue)
+            messenger.sendCommand(command.rawValue)
         }
     }
 
@@ -157,16 +147,32 @@ public class Engine {
         _ in
     }
 
-}
-
-// MARK: - Private
-
-extension Engine {
+    // MARK: - Private
 
+    /// Logs `message` if `loggingEnabled` is `true`.
     private func log(_ message: String) {
         if loggingEnabled {
             Logging.print(message)
         }
     }
 
+    private var initialSetupComplete = false
+
+    /// Sets initial engine options.
+    private func performInitialSetup(coreCount: Int, multipv: Int) {
+        guard !initialSetupComplete else { return }
+
+        // configure engine-specific options
+        type.setupCommands.forEach(send)
+
+        // configure common engine options
+        send(command: .setoption(
+            id: "Threads",
+            value: "\(max(coreCount - 1, 1))"
+        ))
+        send(command: .setoption(id: "MultiPV", value: "\(multipv)"))
+
+        initialSetupComplete = true
+    }
+
 }

Sources/ChessKitEngine/EngineResponse/EngineResponse.swift

@@ -7,37 +7,37 @@
 /// [Universal Chess Interface (UCI)](https://backscattering.de/chess/uci/2006-04.txt).
 ///
 public enum EngineResponse {
-    
+
     /// `"id name <x>"`, `"id author <x>"`
     ///
     /// See [UCI protocol documentation](https://backscattering.de/chess/uci/2006-04.txt)
     /// for more information.
     case id(ID)
-    
+
     /// `"uciok"`
     ///
     /// See [UCI protocol documentation](https://backscattering.de/chess/uci/2006-04.txt)
     /// for more information.
     case uciok
-    
+
     /// `"readyok"`
     ///
     /// See [UCI protocol documentation](https://backscattering.de/chess/uci/2006-04.txt)
     /// for more information.
     case readyok
-    
+
     /// `"bestmove <move1> [ ponder <move2> ]"`
     ///
     /// See [UCI protocol documentation](https://backscattering.de/chess/uci/2006-04.txt)
     /// for more information.
     case bestmove(move: String, ponder: String?)
-    
+
     /// `"info"`
     ///
     /// See [UCI protocol documentation](https://backscattering.de/chess/uci/2006-04.txt)
     /// for more information.
     case info(Info)
-    
+
 }
 
 extension EngineResponse: Equatable {}
@@ -45,35 +45,35 @@ extension EngineResponse: Equatable {}
 extension EngineResponse: RawRepresentable {
     public init?(rawValue: String) {
         let parsed = EngineResponseParser.parse(response: rawValue)
-        
+
         guard let parsed else {
             return nil
         }
-        
+
         self = parsed
     }
-    
+
     public var rawValue: String {
         switch self {
         case let .id(id):
             switch id {
             case let .name(name):
-                return "<id> <name> \(name)"
+                "<id> <name> \(name)"
             case let .author(author):
-                return "<id> <author> \(author)"
+                "<id> <author> \(author)"
             }
         case .uciok:
-            return "<uciok>"
+            "<uciok>"
         case .readyok:
-            return "<readyok>"
+            "<readyok>"
         case let .bestmove(move, ponder):
             if let ponder {
-                return "<bestmove> \(move) <ponder> \(ponder)"
+                "<bestmove> \(move) <ponder> \(ponder)"
             } else {
-                return "<bestmove> \(move)"
+                "<bestmove> \(move)"
             }
         case let .info(info):
-            return "<info>\(info)"
+            "<info>\(info)"
         }
     }
 }

Sources/ChessKitEngine/EngineType.swift

@@ -42,7 +42,7 @@ public enum EngineType: Int {
             let options = [
                 "EvalFile": "nn-b1a57edbea57",
                 "EvalFileSmall": "nn-baff1ede1f90"
-            ].mapValues {
+            ].compactMapValues {
                 Bundle.main.url(forResource: $0, withExtension: "nnue")?.path()
             }
 

Sources/ChessKitEngineCore/EngineMessenger/EngineMessenger.mm

@@ -43,8 +43,6 @@ NSFileHandle *_pipeWriteHandle;
 }
 
 - (void)start {
-
-
     // set up read pipe
     _readPipe = [NSPipe pipe];
     _pipeReadHandle = [_readPipe fileHandleForReading];
@@ -66,7 +64,7 @@ NSFileHandle *_pipeWriteHandle;
     dup2([[_writePipe fileHandleForReading] fileDescriptor], fileno(stdin));
 
     // create command dispatch queue and start engine
-    _queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
+    _queue = dispatch_queue_create("ck-message-queue", DISPATCH_QUEUE_CONCURRENT);
 
     dispatch_async(_queue, ^{
         _engine->initialize();
@@ -88,8 +86,8 @@ NSFileHandle *_pipeWriteHandle;
 
 - (void)sendCommand: (NSString*) command {
     dispatch_sync(_queue, ^{
-        const char *cCommand = [[command stringByAppendingString:@"\n"] UTF8String];
-        write([_pipeWriteHandle fileDescriptor], cCommand, strlen(cCommand));
+        const char *cmd = [[command stringByAppendingString:@"\n"] UTF8String];
+        write([_pipeWriteHandle fileDescriptor], cmd, strlen(cmd));
     });
 }