Refactoring and add semantic cache

src/main/java/de/shahondin1624/rag/LocalRagService.java

@@ -1,5 +1,6 @@
 package de.shahondin1624.rag;
 
+import de.shahondin1624.rag.cache.SemanticCache;
 import dev.langchain4j.data.segment.TextSegment;
 import dev.langchain4j.store.embedding.EmbeddingMatch;
 import dev.langchain4j.store.embedding.EmbeddingStore;
@@ -7,7 +8,6 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import java.nio.file.Path;
-import java.nio.file.Paths;
 import java.util.List;
 import java.util.Map;
 import java.util.stream.Collectors;
@@ -24,6 +24,8 @@ public class LocalRagService {
     private final RagIndexer indexer;
     private final RagDocumentSplitter splitter;
 
+    private final SemanticCache semanticCache;
+
     public static synchronized LocalRagService getInstance() {
         if (instance == null) {
             instance = new LocalRagService();
@@ -35,6 +37,7 @@ public class LocalRagService {
         this.storeManager = new RagStoreManager();
         this.splitter = new RagDocumentSplitter();
         this.indexer = new RagIndexer(storeManager, splitter);
+        this.semanticCache = new SemanticCache(50, 0.92);
         initialize();
     }
 
@@ -45,53 +48,64 @@ public class LocalRagService {
         log.info("LocalRagService initialized successfully.");
     }
 
-    public void indexDirectory(Path path) {
+    public void indexDirectory(final Path path) {
         indexDirectory(path, null);
     }
 
-    public void indexDirectory(Path path, Map<String, String> metadata) {
+    public void indexDirectory(final Path path, final Map<String, String> metadata) {
         indexer.indexDirectory(path, metadata);
         new RagFileWatcher(path, p -> indexer.indexFile(p, metadata), indexer::removeFile, indexer::isSupportedFile).start();
     }
 
-    public void indexFile(Path path) {
+    public void indexFile(final Path path) {
         indexFile(path, null);
     }
 
-    public void indexFile(Path path, Map<String, String> metadata) {
+    public void indexFile(final Path path, final Map<String, String> metadata) {
         indexer.indexFile(path, metadata);
     }
 
-    public void removeFile(Path path) {
+    public void removeFile(final Path path) {
         indexer.removeFile(path);
     }
 
-    public void indexDocuments(List<String> docs) {
+    public void indexDocuments(final List<String> docs) {
         indexDocuments(docs, null);
     }
 
-    public void indexDocuments(List<String> docs, Map<String, String> metadata) {
+    public void indexDocuments(final List<String> docs, final Map<String, String> metadata) {
         log.info("Indexing {} documents...", docs.size());
-        for (String docText : docs) {
+        for (final String docText : docs) {
-            List<TextSegment> segments = splitter.split(docText, metadata);
+            final List<TextSegment> segments = splitter.split(docText, metadata);
             if (!segments.isEmpty()) {
-                var embeddings = storeManager.getEmbeddingModel().embedAll(segments).content();
+                final var embeddings = storeManager.getEmbeddingModel().embedAll(segments).content();
                 storeManager.getEmbeddingStore().addAll(embeddings, segments);
             }
         }
         log.info("Indexing completed.");
     }
 
-    public String search(String query) {
+    public String search(final String query) {
         log.info("Searching for: {}", query);
-        var queryEmbedding = storeManager.getEmbeddingModel().embed(query).content();
+        final var queryEmbedding = storeManager.getEmbeddingModel().embed(query).content();
-        List<EmbeddingMatch<TextSegment>> matches = storeManager.getEmbeddingStore().findRelevant(queryEmbedding, 5);
 
-        String result = matches.stream()
+        final String cachedResult = semanticCache.get(queryEmbedding);
+        if (cachedResult != null) {
+            log.info("⚡ Cache Hit! Returning result without vector search.");
+            return cachedResult;
+        }
+
+        final List<EmbeddingMatch<TextSegment>> matches = storeManager.getEmbeddingStore().findRelevant(queryEmbedding, 5);
+
+        final String result = matches.stream()
                 .map(m -> m.embedded().text())
                 .collect(Collectors.joining("\n\n---\n\n"));
 
         log.info("Search completed with {} matches.", matches.size());
+
+        if (!result.isBlank()) {
+            semanticCache.put(query, queryEmbedding, result);
+        }
         return result;
     }
 
@@ -99,7 +113,7 @@ public class LocalRagService {
         return storeManager.getEmbeddingStore();
     }
 
-    public void saveStore(Path path) {
+    public void saveStore(final Path path) {
         storeManager.saveStore(path);
     }
 }

src/main/java/de/shahondin1624/rag/RagDocumentSplitter.java

@@ -23,13 +23,13 @@ public class RagDocumentSplitter {
      * @param metadata The metadata to associate with each segment.
      * @return A list of text segments.
      */
-    public List<TextSegment> split(String docText, Map<String, String> metadata) {
+    public List<TextSegment> split(final String docText, final Map<String, String> metadata) {
-        List<TextSegment> segments = new ArrayList<>();
+        final List<TextSegment> segments = new ArrayList<>();
-        Metadata lcMetadata = metadata != null ? Metadata.from(metadata) : new Metadata();
+        final Metadata lcMetadata = metadata != null ? Metadata.from(metadata) : new Metadata();
 
         // Try to split by DSL-like blocks or Markdown headers
-        String[] blocks = docText.split("\n(?=## )|\n(?=\\w+\\s*\\{)");
+        final String[] blocks = docText.split("\n(?=## )|\n(?=\\w+\\s*\\{)");
-        for (String block : blocks) {
+        for (final String block : blocks) {
             if (!block.isBlank()) {
                 segments.add(TextSegment.from(block.trim(), lcMetadata));
             }
@@ -37,9 +37,9 @@ public class RagDocumentSplitter {
 
         if (segments.isEmpty()) {
             // Fallback to recursive splitter if no blocks found
-            DocumentSplitter splitter = DocumentSplitters.recursive(500, 50);
+            final DocumentSplitter splitter = DocumentSplitters.recursive(500, 50);
-            List<TextSegment> splitSegments = splitter.split(Document.from(docText));
+            final List<TextSegment> splitSegments = splitter.split(Document.from(docText));
-            for (TextSegment segment : splitSegments) {
+            for (final TextSegment segment : splitSegments) {
                 segments.add(TextSegment.from(segment.text(), lcMetadata));
             }
         }

src/main/java/de/shahondin1624/rag/RagFileWatcher.java

@@ -19,7 +19,7 @@ public class RagFileWatcher {
     private final Consumer<Path> onFileDeleted;
     private final Predicate<Path> fileFilter;
 
-    public RagFileWatcher(Path dir, Consumer<Path> onFileChanged, Consumer<Path> onFileDeleted, Predicate<Path> fileFilter) {
+    public RagFileWatcher(final Path dir, final Consumer<Path> onFileChanged, final Consumer<Path> onFileDeleted, final Predicate<Path> fileFilter) {
         this.dir = dir;
         this.onFileChanged = onFileChanged;
         this.onFileDeleted = onFileDeleted;
@@ -28,17 +28,17 @@ public class RagFileWatcher {
 
     public void start() {
         CompletableFuture.runAsync(() -> {
-            try (WatchService watcher = FileSystems.getDefault().newWatchService()) {
+            try (final WatchService watcher = FileSystems.getDefault().newWatchService()) {
                 dir.register(watcher, StandardWatchEventKinds.ENTRY_CREATE,
                         StandardWatchEventKinds.ENTRY_DELETE,
                         StandardWatchEventKinds.ENTRY_MODIFY);
                 log.info("Started watching directory for changes: {}", dir);
                 while (!Thread.currentThread().isInterrupted()) {
-                    WatchKey key = watcher.take();
+                    final WatchKey key = watcher.take();
-                    for (WatchEvent<?> event : key.pollEvents()) {
+                    for (final WatchEvent<?> event : key.pollEvents()) {
-                        WatchEvent.Kind<?> kind = event.kind();
+                        final WatchEvent.Kind<?> kind = event.kind();
-                        Path fileName = (Path) event.context();
+                        final Path fileName = (Path) event.context();
-                        Path filePath = dir.resolve(fileName);
+                        final Path filePath = dir.resolve(fileName);
 
                         if (kind == StandardWatchEventKinds.ENTRY_CREATE || kind == StandardWatchEventKinds.ENTRY_MODIFY) {
                             if (Files.isRegularFile(filePath) && fileFilter.test(filePath)) {
@@ -52,7 +52,7 @@ public class RagFileWatcher {
                         break;
                     }
                 }
-            } catch (Exception e) {
+            } catch (final Exception e) {
                 log.error("Error in file watcher", e);
             }
         });

src/main/java/de/shahondin1624/rag/RagIndexer.java

@@ -24,39 +24,39 @@ public class RagIndexer {
     private final RagDocumentSplitter splitter;
     private final Map<Path, List<String>> fileToIds = new ConcurrentHashMap<>();
 
-    public RagIndexer(RagStoreManager storeManager, RagDocumentSplitter splitter) {
+    public RagIndexer(final RagStoreManager storeManager, final RagDocumentSplitter splitter) {
         this.storeManager = storeManager;
         this.splitter = splitter;
     }
 
-    public void indexDirectory(Path path) {
+    public void indexDirectory(final Path path) {
         indexDirectory(path, null);
     }
 
-    public void indexDirectory(Path path, Map<String, String> metadata) {
+    public void indexDirectory(final Path path, final Map<String, String> metadata) {
         log.info("Indexing directory: {}", path);
-        try (Stream<Path> paths = Files.walk(path)) {
+        try (final Stream<Path> paths = Files.walk(path)) {
             paths.filter(Files::isRegularFile)
                     .filter(this::isSupportedFile)
                     .forEach(p -> indexFile(p, metadata));
-        } catch (IOException e) {
+        } catch (final IOException e) {
             log.error("Failed to index directory: {}", path, e);
         }
     }
 
-    public void indexFile(Path path) {
+    public void indexFile(final Path path) {
         indexFile(path, null);
     }
 
-    public void indexFile(Path path, Map<String, String> extraMetadata) {
+    public void indexFile(final Path path, final Map<String, String> extraMetadata) {
         removeFile(path);
         try {
-            String content = Files.readString(path);
+            final String content = Files.readString(path);
             if (content.isBlank()) {
                 return;
             }
 
-            Map<String, String> metadata = new HashMap<>();
+            final Map<String, String> metadata = new HashMap<>();
             metadata.put("file_path", path.toString());
             if (extraMetadata != null) {
                 metadata.putAll(extraMetadata);
@@ -64,28 +64,28 @@ public class RagIndexer {
 
             List<TextSegment> segments = splitter.split(content, metadata);
             if (!segments.isEmpty()) {
-                List<Embedding> embeddings = storeManager.getEmbeddingModel().embedAll(segments).content();
+                final List<Embedding> embeddings = storeManager.getEmbeddingModel().embedAll(segments).content();
-                List<String> ids = storeManager.getEmbeddingStore().addAll(embeddings, segments);
+                final List<String> ids = storeManager.getEmbeddingStore().addAll(embeddings, segments);
                 fileToIds.put(path, ids);
                 log.info("Indexed file: {} ({} segments)", path, segments.size());
             }
-        } catch (IOException e) {
+        } catch (final IOException e) {
             log.error("Failed to read file: {}", path, e);
         }
     }
 
-    public void removeFile(Path path) {
+    public void removeFile(final Path path) {
-        List<String> ids = fileToIds.remove(path);
+        final List<String> ids = fileToIds.remove(path);
         if (ids != null) {
-            for (String id : ids) {
+            for (final String id : ids) {
                 storeManager.getEmbeddingStore().remove(id);
             }
             log.info("Removed file from index: {}", path);
         }
     }
 
-    public boolean isSupportedFile(Path path) {
+    public boolean isSupportedFile(final Path path) {
-        String s = path.toString();
+        final String s = path.toString();
         return s.endsWith(".md") || s.endsWith(".dsl") || s.endsWith(".txt");
     }
 

src/main/java/de/shahondin1624/rag/RagStoreManager.java

@@ -26,14 +26,14 @@ public class RagStoreManager {
         this.embeddingModel = new AllMiniLmL6V2EmbeddingModel();
     }
 
-    public void loadBundledStore(String resourcePath) {
+    public void loadBundledStore(final String resourcePath) {
-        try (InputStream is = getClass().getClassLoader().getResourceAsStream(resourcePath)) {
+        try (final InputStream is = getClass().getClassLoader().getResourceAsStream(resourcePath)) {
             if (is != null) {
-                String json = new String(is.readAllBytes(), StandardCharsets.UTF_8);
+                final String json = new String(is.readAllBytes(), StandardCharsets.UTF_8);
                 this.embeddingStore = InMemoryEmbeddingStore.fromJson(json);
                 log.info("Loaded bundled embedding store from {}", resourcePath);
             }
-        } catch (IOException e) {
+        } catch (final IOException e) {
             log.error("Failed to load bundled embedding store", e);
         }
     }
@@ -44,13 +44,13 @@ public class RagStoreManager {
         }
     }
 
-    public void saveStore(Path path) {
+    public void saveStore(final Path path) {
         if (embeddingStore == null) return;
         try {
-            String json = embeddingStore.serializeToJson();
+            final String json = embeddingStore.serializeToJson();
             Files.writeString(path, json);
             log.info("Saved embedding store to {}", path);
-        } catch (IOException e) {
+        } catch (final IOException e) {
             log.error("Failed to save embedding store", e);
         }
     }

src/main/java/de/shahondin1624/rag/TestDataGenerator.java

@@ -9,7 +9,7 @@ import java.nio.file.StandardOpenOption;
 public class TestDataGenerator {
 
     public static void main(String[] args) {
-        Path root = Paths.get("test-data");
+        final Path root = Paths.get("test-data");
         
         try {
             // 1. Create Directories
@@ -86,13 +86,13 @@ public class TestDataGenerator {
 
             System.out.println("✅ Test data generated successfully in: " + root.toAbsolutePath());
 
-        } catch (IOException e) {
+        } catch (final IOException e) {
             System.err.println("Failed to generate test data: " + e.getMessage());
             e.printStackTrace();
         }
     }
 
-    private static void createFile(Path path, String content) throws IOException {
+    private static void createFile(final Path path, final String content) throws IOException {
         Files.writeString(path, content, StandardOpenOption.CREATE, StandardOpenOption.TRUNCATE_EXISTING);
         System.out.println("Created: " + path);
     }

src/main/java/de/shahondin1624/rag/cache/SemanticCache.java

@@ -0,0 +1,63 @@
+package de.shahondin1624.rag.cache;
+
+import dev.langchain4j.data.embedding.Embedding;
+import dev.langchain4j.store.embedding.CosineSimilarity;
+
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
+
+public class SemanticCache {
+
+    private final int maxEntries;
+    private final double similarityThreshold;
+
+    private final Map<CachedQuery, String> cache;
+    private final ReentrantReadWriteLock lock = new ReentrantReadWriteLock();
+
+    public SemanticCache(final int maxEntries, final double similarityThreshold) {
+        this.maxEntries = maxEntries;
+        this.similarityThreshold = similarityThreshold;
+
+        this.cache = new LinkedHashMap<>(maxEntries, 0.75f, true) {
+            @Override
+            protected boolean removeEldestEntry(Map.Entry<CachedQuery, String> eldest) {
+                return size() > SemanticCache.this.maxEntries;
+            }
+        };
+    }
+
+    /**
+     * Tries to find a semantically similar query in the cache.
+     * @param incomingEmbedding The vector of the new user query.
+     * @return The cached string result, or null if no match found.
+     */
+    public String get(final Embedding incomingEmbedding) {
+        lock.readLock().lock();
+        try {
+            // Linear scan of the cache (fast for <100 entries)
+            for (final Map.Entry<CachedQuery, String> entry : cache.entrySet()) {
+                final double similarity = CosineSimilarity.between(incomingEmbedding, entry.getKey().embedding);
+                if (similarity >= similarityThreshold) {
+                    System.out.println("⚡ Semantic Cache Hit! (Similarity: " + similarity + ")");
+                    return entry.getValue();
+                }
+            }
+            return null;
+        } finally {
+            lock.readLock().unlock();
+        }
+    }
+
+    public void put(final String originalQueryText, final Embedding embedding, final String result) {
+        lock.writeLock().lock();
+        try {
+            cache.put(new CachedQuery(originalQueryText, embedding), result);
+        } finally {
+            lock.writeLock().unlock();
+        }
+    }
+
+    // Wrapper class to store metadata if needed (e.g., timestamps)
+    private record CachedQuery(String text, Embedding embedding) {}
+}

src/main/java/de/shahondin1624/rag/tooling/RagEmbedTool.java

@@ -56,15 +56,15 @@ public class RagEmbedTool extends McpValidatedTool {
     }
 
     @Override
-    public McpSchema.CallToolResult callValidated(McpSchema.CallToolRequest request, Map<String, Object> arguments) {
+    public McpSchema.CallToolResult callValidated(final McpSchema.CallToolRequest request, final Map<String, Object> arguments) {
-        String content = (String) arguments.get("content");
+        final String content = (String) arguments.get("content");
         @SuppressWarnings("unchecked")
-        Map<String, Object> rawMetadata = (Map<String, Object>) arguments.get("metadata");
+        final Map<String, Object> rawMetadata = (Map<String, Object>) arguments.get("metadata");
 
         Map<String, String> metadata = null;
         if (rawMetadata != null) {
             metadata = new HashMap<>();
-            for (Map.Entry<String, Object> entry : rawMetadata.entrySet()) {
+            for (final Map.Entry<String, Object> entry : rawMetadata.entrySet()) {
                 metadata.put(entry.getKey(), String.valueOf(entry.getValue()));
             }
         }
@@ -74,7 +74,7 @@ public class RagEmbedTool extends McpValidatedTool {
         try {
             LocalRagService.getInstance().indexDocuments(List.of(content), metadata);
             return successResult("Information successfully embedded and indexed.");
-        } catch (Exception e) {
+        } catch (final Exception e) {
             logger.error("Error during information embedding", e);
             return error("Error during information embedding: " + e.getMessage());
         }

src/main/java/de/shahondin1624/rag/tooling/RagSearchTool.java

@@ -48,14 +48,14 @@ public class RagSearchTool extends McpValidatedTool {
     }
 
     @Override
-    public McpSchema.CallToolResult callValidated(McpSchema.CallToolRequest request, Map<String, Object> arguments) {
+    public McpSchema.CallToolResult callValidated(final McpSchema.CallToolRequest request, final Map<String, Object> arguments) {
-        String query = (String) arguments.get("query");
+        final String query = (String) arguments.get("query");
         logger.debug("RagSearchTool called with query: {}", query);
         
         try {
-            String result = LocalRagService.getInstance().search(query);
+            final String result = LocalRagService.getInstance().search(query);
             return successResult(result);
-        } catch (Exception e) {
+        } catch (final Exception e) {
             logger.error("Error during RAG search", e);
             return error("Error during RAG search: " + e.getMessage());
         }