fix: issue with isModelGenerating when switching between multiple mod…

…els (#73)

## Description
There was a problem when user was switching between multiple llms in one
component, to fix this issue I removed code related to handling strict
mode problems(strict mode was causing problems with event listeners also
so I think we should ignore it as it isn't the best with background
tasks), I've also remove deleteModule native function as it wasn't
really doing anything, now user can download multiple llms within one
component and seamlessly switch between them without bugs.
The problem was mentioned in issue #42 

### Type of change
- [x] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to not work as expected)
- [ ] Documentation update (improves or adds clarity to existing
documentation)

### Tested on
- [x] iOS
- [x] Android

### Testing instructions
<!-- Provide step-by-step instructions on how to test your changes.
Include setup details if necessary. -->

### Screenshots
<!-- Add screenshots here, if applicable -->

### Related issues
<!-- Link related issues here using #issue-number -->

### Checklist
- [x] I have performed a self-review of my code
- [ ] I have commented my code, particularly in hard-to-understand areas
- [ ] I have updated the documentation accordingly
- [ ] My changes generate no new warnings

### Additional notes
<!-- Include any additional information, assumptions, or context that
reviewers might need to understand this PR. -->

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 is fetching", "Model is fetching")
       return
     }
 

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];
@@ -54,9 +54,9 @@ - (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){
-    reject(@"model_already_loaded", @"Model and tokenizer already loaded", nil);
+
+  if(isFetching){
+    reject(@"model_is_fetching", @"Model is fetching", 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;
@@ -120,7 +121,6 @@ - (void) runInference:(NSString *)input resolve:(RCTPromiseResolveBlock)resolve
   });
 }
 
-
 -(void)interrupt {
   [self->runner stop];
 }

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);
       }
     };
 

src/native/NativeLLM.ts

@@ -10,8 +10,8 @@ export interface Spec extends TurboModule {
     contextWindowLength: number
   ): Promise<string>;
   runInference(input: string): Promise<string>;
-  deleteModule(): void;
   interrupt(): void;
+  deleteModule(): void;
 
   readonly onToken: EventEmitter<string>;
   readonly onDownloadProgress: EventEmitter<number>;