fix swift 6 warnings - thread safe tokenizer and model config (#126)

- replaces #125 with simpler mechanism (NSLock)

Co-authored-by: John Mai <maiqingqiang@gmail.com>

Author: davidkoski

Libraries/LLM/Configuration.swift

@@ -26,20 +26,21 @@ public enum StringOrNumber: Codable, Equatable, Sendable {
     }
 }
 
-public struct ModelType: RawRepresentable, Codable, Sendable {
-    public let rawValue: String
+private class ModelTypeRegistry: @unchecked Sendable {
 
-    public init(rawValue: String) {
-        self.rawValue = rawValue
-    }
+    // Note: using NSLock as we have very small (just dictionary get/set)
+    // critical sections and expect no contention.  this allows the methods
+    // to remain synchronous.
+    private let lock = NSLock()
 
+    @Sendable
     private static func createLlamaModel(url: URL) throws -> LLMModel {
         let configuration = try JSONDecoder().decode(
             LlamaConfiguration.self, from: Data(contentsOf: url))
         return LlamaModel(configuration)
     }
 
-    private static var creators: [String: (URL) throws -> LLMModel] = [
+    private var creators: [String: @Sendable (URL) throws -> LLMModel] = [
         "mistral": createLlamaModel,
         "llama": createLlamaModel,
         "phi": { url in
@@ -89,18 +90,44 @@ public struct ModelType: RawRepresentable, Codable, Sendable {
         },
     ]
 
-    public static func registerModelType(
-        _ type: String, creator: @escaping (URL) throws -> LLMModel
+    public func registerModelType(
+        _ type: String, creator: @Sendable @escaping (URL) throws -> LLMModel
     ) {
-        creators[type] = creator
+        lock.withLock {
+            creators[type] = creator
+        }
     }
 
-    public func createModel(configuration: URL) throws -> LLMModel {
-        guard let creator = ModelType.creators[rawValue] else {
+    public func createModel(configuration: URL, rawValue: String) throws -> LLMModel {
+        let creator = lock.withLock {
+            creators[rawValue]
+        }
+        guard let creator else {
             throw LLMError(message: "Unsupported model type.")
         }
         return try creator(configuration)
     }
+
+}
+
+private let modelTypeRegistry = ModelTypeRegistry()
+
+public struct ModelType: RawRepresentable, Codable, Sendable {
+    public let rawValue: String
+
+    public init(rawValue: String) {
+        self.rawValue = rawValue
+    }
+
+    public static func registerModelType(
+        _ type: String, creator: @Sendable @escaping (URL) throws -> LLMModel
+    ) {
+        modelTypeRegistry.registerModelType(type, creator: creator)
+    }
+
+    public func createModel(configuration: URL) throws -> LLMModel {
+        try modelTypeRegistry.createModel(configuration: configuration, rawValue: rawValue)
+    }
 }
 
 public struct BaseConfiguration: Codable, Sendable {

Libraries/LLM/Tokenizer.swift

@@ -67,12 +67,35 @@ private func updateTokenizerConfig(_ tokenizerConfig: Config) -> Config {
     return tokenizerConfig
 }
 
-/// overrides for TokenizerModel/knownTokenizers
-public var replacementTokenizers = [
-    "InternLM2Tokenizer": "PreTrainedTokenizer",
-    "Qwen2Tokenizer": "PreTrainedTokenizer",
-    "CohereTokenizer": "PreTrainedTokenizer",
-]
+public class TokenizerReplacementRegistry: @unchecked Sendable {
+
+    // Note: using NSLock as we have very small (just dictionary get/set)
+    // critical sections and expect no contention.  this allows the methods
+    // to remain synchronous.
+    private let lock = NSLock()
+
+    /// overrides for TokenizerModel/knownTokenizers
+    private var replacementTokenizers = [
+        "InternLM2Tokenizer": "PreTrainedTokenizer",
+        "Qwen2Tokenizer": "PreTrainedTokenizer",
+        "CohereTokenizer": "PreTrainedTokenizer",
+    ]
+
+    public subscript(key: String) -> String? {
+        get {
+            lock.withLock {
+                replacementTokenizers[key]
+            }
+        }
+        set {
+            lock.withLock {
+                replacementTokenizers[key] = newValue
+            }
+        }
+    }
+}
+
+public let replacementTokenizers = TokenizerReplacementRegistry()
 
 public protocol StreamingDetokenizer: IteratorProtocol<String> {
 

Tools/LinearModelTraining/LinearModelTraining.swift

@@ -7,7 +7,7 @@ import MLXNN
 import MLXOptimizers
 import MLXRandom
 
-#if swift(>=6.0)
+#if swift(>=5.10)
     extension MLX.DeviceType: @retroactive ExpressibleByArgument {
         public init?(argument: String) {
             self.init(rawValue: argument)

Tools/image-tool/Arguments.swift

@@ -4,7 +4,7 @@ import ArgumentParser
 import Foundation
 import MLX
 
-#if swift(>=6.0)
+#if swift(>=5.10)
     /// Extension to allow URL command line arguments.
     extension URL: @retroactive ExpressibleByArgument {
         public init?(argument: String) {

Tools/image-tool/ImageTool.swift

@@ -22,7 +22,7 @@ struct StableDiffusionTool: AsyncParsableCommand {
     )
 }
 
-#if swift(>=6.0)
+#if swift(>=5.10)
     extension StableDiffusionConfiguration.Preset: @retroactive ExpressibleByArgument {}
 #else
     extension StableDiffusionConfiguration.Preset: ExpressibleByArgument {}

Tools/llm-tool/Arguments.swift

@@ -4,7 +4,7 @@ import ArgumentParser
 import Foundation
 
 /// Extension to allow URL command line arguments.
-#if swift(>=6.0)
+#if swift(>=5.10)
     extension URL: @retroactive ExpressibleByArgument {
         public init?(argument: String) {
             if argument.contains("://") {

Tools/mnist-tool/MNISTTool.swift

@@ -16,7 +16,7 @@ struct MNISTTool: AsyncParsableCommand {
         defaultSubcommand: Train.self)
 }
 
-#if swift(>=6.0)
+#if swift(>=5.10)
     extension MLX.DeviceType: @retroactive ExpressibleByArgument {
         public init?(argument: String) {
             self.init(rawValue: argument)