fix: issue with isModelGenerating when switching between multiple models

android/src/main/java/com/swmansion/rnexecutorch/LLM.kt

@@ -64,6 +64,7 @@ class LLM(reactContext: ReactApplicationContext) :
   private fun initializeLlamaModule(modelPath: String, tokenizerPath: String, promise: Promise) {
     llamaModule = LlamaModule(1, modelPath, tokenizerPath, 0.7f)
     isFetching = false
+    this.tempLlamaResponse.clear()
     promise.resolve("Model loaded successfully")
   }
 
@@ -74,8 +75,8 @@ class LLM(reactContext: ReactApplicationContext) :
     contextWindowLength: Double,
     promise: Promise
   ) {
-    if (llamaModule != null || isFetching) {
-      promise.reject("Model already loaded", "Model is already loaded or fetching")
+    if (isFetching) {
+      promise.reject("Model already loaded", "Model is already fetching")
       return
     }
 
@@ -148,10 +149,6 @@ class LLM(reactContext: ReactApplicationContext) :
     llamaModule!!.stop()
   }
 
-  override fun deleteModule() {
-    llamaModule = null
-  }
-
   companion object {
     const val NAME = "LLM"
   }

ios/RnExecutorch/LLM.mm

@@ -28,7 +28,7 @@ - (instancetype)init {
     isFetching = NO;
     tempLlamaResponse = [[NSMutableString alloc] init];
   }
-
+  
   return self;
 }
 
@@ -38,7 +38,7 @@ - (void)onResult:(NSString *)token prompt:(NSString *)prompt {
   if ([token isEqualToString:prompt]) {
     return;
   }
-
+  
   dispatch_async(dispatch_get_main_queue(), ^{
     [self emitOnToken:token];
     [self->tempLlamaResponse appendString:token];
@@ -54,8 +54,8 @@ - (void)updateDownloadProgress:(NSNumber *)progress {
 - (void)loadLLM:(NSString *)modelSource tokenizerSource:(NSString *)tokenizerSource systemPrompt:(NSString *)systemPrompt contextWindowLength:(double)contextWindowLength resolve:(RCTPromiseResolveBlock)resolve reject:(RCTPromiseRejectBlock)reject {
   NSURL *modelURL = [NSURL URLWithString:modelSource];
   NSURL *tokenizerURL = [NSURL URLWithString:tokenizerSource];
-    
-  if(self->runner || isFetching){
+
+  if(isFetching){
     reject(@"model_already_loaded", @"Model and tokenizer already loaded", nil);
     return;
   }
@@ -78,10 +78,11 @@ - (void)loadLLM:(NSString *)modelSource tokenizerSource:(NSString *)tokenizerSou
 
     modelFetcher.onFinish = ^(NSString *modelFilePath) {
       self->runner = [[LLaMARunner alloc] initWithModelPath:modelFilePath tokenizerPath:tokenizerFilePath];
-        NSUInteger contextWindowLengthUInt = (NSUInteger)round(contextWindowLength);
+      NSUInteger contextWindowLengthUInt = (NSUInteger)round(contextWindowLength);
 
       self->conversationManager = [[ConversationManager alloc] initWithNumMessagesContextWindow: contextWindowLengthUInt systemPrompt: systemPrompt];
       self->isFetching = NO;
+      self->tempLlamaResponse = [NSMutableString string];
       resolve(@"Model and tokenizer loaded successfully");
       return;
     };
@@ -94,23 +95,23 @@ - (void)loadLLM:(NSString *)modelSource tokenizerSource:(NSString *)tokenizerSou
 - (void) runInference:(NSString *)input resolve:(RCTPromiseResolveBlock)resolve reject:(RCTPromiseRejectBlock)reject {
   [conversationManager addResponse:input senderRole:ChatRole::USER];
   NSString *prompt = [conversationManager getConversation];
-
+  
   dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
     NSError *error = nil;
     [self->runner generate:prompt withTokenCallback:^(NSString *token) {
-        [self onResult:token prompt:prompt];
+      [self onResult:token prompt:prompt];
     } error:&error];
-
+    
     // make sure to add eot token once generation is done
     if (![self->tempLlamaResponse hasSuffix:END_OF_TEXT_TOKEN_NS]) {
       [self onResult:END_OF_TEXT_TOKEN_NS prompt:prompt];
     }
-
+    
     if (self->tempLlamaResponse) {
       [self->conversationManager addResponse:self->tempLlamaResponse senderRole:ChatRole::ASSISTANT];
       self->tempLlamaResponse = [NSMutableString string];
     }
-
+    
     if (error) {
       reject(@"error_in_generation", error.localizedDescription, nil);
       return;
@@ -125,10 +126,6 @@ -(void)interrupt {
   [self->runner stop];
 }
 
--(void)deleteModule {
-  self->runner = nil;
-}
-
 - (std::shared_ptr<facebook::react::TurboModule>)getTurboModule:(const facebook::react::ObjCTurboModule::InitParams &)params
 {
   return std::make_shared<facebook::react::NativeLLMSpecJSI>(params);

ios/RnExecutorch/utils/LargeFileFetcher.mm

@@ -12,7 +12,7 @@ @implementation LargeFileFetcher {
 - (instancetype)init {
   self = [super init];
   if (self) {
-    NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration backgroundSessionConfigurationWithIdentifier:@"com.swmansion.rnexecutorch"];
+    NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration backgroundSessionConfigurationWithIdentifier:[NSString stringWithFormat:@"com.swmansion.rnexecutorch.%@", [[NSUUID UUID] UUIDString]]];
     _session = [NSURLSession sessionWithConfiguration:configuration delegate:self delegateQueue:nil];
   }
   return self;
@@ -111,7 +111,7 @@ - (void)startDownloadingFileFromURL:(NSURL *)url {
 
 - (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didFinishDownloadingToURL:(NSURL *)location {
   NSFileManager *fileManager = [NSFileManager defaultManager];
-  
+
   [fileManager removeItemAtPath:_destination error:nil];
 
   NSError *error;

src/LLM.ts

@@ -30,15 +30,8 @@ export const useLLM = ({
   const [downloadProgress, setDownloadProgress] = useState(0);
   const downloadProgressListener = useRef<null | EventSubscription>(null);
   const tokenGeneratedListener = useRef<null | EventSubscription>(null);
-  const initialized = useRef(false);
 
   useEffect(() => {
-    if (initialized.current) {
-      return;
-    }
-
-    initialized.current = true;
-
     const loadModel = async () => {
       try {
         let modelUrl = modelSource;
@@ -57,6 +50,7 @@ export const useLLM = ({
             }
           }
         );
+        setIsReady(false);
 
         await LLM.loadLLM(
           modelUrl as string,
@@ -83,6 +77,8 @@ export const useLLM = ({
         const message = (err as Error).message;
         setIsReady(false);
         setError(message);
+      } finally {
+        setDownloadProgress(0);
       }
     };
 
@@ -93,7 +89,6 @@ export const useLLM = ({
       downloadProgressListener.current = null;
       tokenGeneratedListener.current?.remove();
       tokenGeneratedListener.current = null;
-      LLM.deleteModule();
     };
   }, [contextWindowLength, modelSource, systemPrompt, tokenizerSource]);
 

src/native/NativeLLM.ts

@@ -10,7 +10,6 @@ export interface Spec extends TurboModule {
     contextWindowLength: number
   ): Promise<string>;
   runInference(input: string): Promise<string>;
-  deleteModule(): void;
   interrupt(): void;
 
   readonly onToken: EventEmitter<string>;