feat: optimize cache, add checkConnection

Signed-off-by: yuluo-yx <yuluo08290126@gmail.com>

Author: yuluo-yx

src/semantic-router/pkg/cache/cache_interface.go

@@ -20,6 +20,11 @@ type CacheBackend interface {
 	// IsEnabled returns whether caching is currently active
 	IsEnabled() bool
 
+	// CheckConnection verifies the cache backend connection is healthy
+	// Returns nil if the connection is healthy, error otherwise
+	// For local caches (in-memory), this may be a no-op
+	CheckConnection() error
+
 	// AddPendingRequest stores a request awaiting its response
 	AddPendingRequest(requestID string, model string, query string, requestBody []byte) error
 

src/semantic-router/pkg/cache/hybrid_cache.go

@@ -191,6 +191,21 @@ func (h *HybridCache) IsEnabled() bool {
 	return h.enabled
 }
 
+// CheckConnection verifies the cache backend connection is healthy
+// For hybrid cache, this checks the Milvus connection
+func (h *HybridCache) CheckConnection() error {
+	if !h.enabled {
+		return nil
+	}
+
+	if h.milvusCache == nil {
+		return fmt.Errorf("milvus cache is not initialized")
+	}
+
+	// Delegate to Milvus cache connection check
+	return h.milvusCache.CheckConnection()
+}
+
 // RebuildFromMilvus rebuilds the in-memory HNSW index from persistent Milvus storage
 // This is called on startup to recover the index after a restart
 func (h *HybridCache) RebuildFromMilvus(ctx context.Context) error {

src/semantic-router/pkg/cache/inmemory_cache.go

@@ -131,6 +131,13 @@ func (c *InMemoryCache) IsEnabled() bool {
 	return c.enabled
 }
 
+// CheckConnection verifies the cache connection is healthy
+// For in-memory cache, this is always healthy (no external connection)
+func (c *InMemoryCache) CheckConnection() error {
+	// In-memory cache has no external connection to check
+	return nil
+}
+
 // generateEmbedding generates an embedding using the configured model
 func (c *InMemoryCache) generateEmbedding(text string) ([]float32, error) {
 	// Normalize to lowercase for case-insensitive comparison
@@ -1099,10 +1106,3 @@ func (h *maxHeap) bubbleDown(i int) {
 		i = largest
 	}
 }
-
-func min(a, b int) int {
-	if a < b {
-		return a
-	}
-	return b
-}

src/semantic-router/pkg/cache/milvus_cache.go

@@ -154,7 +154,6 @@ func NewMilvusCache(options MilvusCacheOptions) (*MilvusCache, error) {
 		logging.Debugf("MilvusCache: failed to connect: %v", err)
 		return nil, fmt.Errorf("failed to create Milvus client: %w", err)
 	}
-	logging.Debugf("MilvusCache: successfully connected to Milvus")
 
 	cache := &MilvusCache{
 		client:              milvusClient,
@@ -165,6 +164,14 @@ func NewMilvusCache(options MilvusCacheOptions) (*MilvusCache, error) {
 		enabled:             options.Enabled,
 	}
 
+	// Test connection using the new CheckConnection method
+	if err := cache.CheckConnection(); err != nil {
+		logging.Debugf("MilvusCache: connection check failed: %v", err)
+		milvusClient.Close()
+		return nil, err
+	}
+	logging.Debugf("MilvusCache: successfully connected to Milvus")
+
 	// Set up the collection for caching
 	logging.Debugf("MilvusCache: initializing collection '%s'", config.Collection.Name)
 	if err := cache.initializeCollection(); err != nil {
@@ -392,6 +399,37 @@ func (c *MilvusCache) IsEnabled() bool {
 	return c.enabled
 }
 
+// CheckConnection verifies the Milvus connection is healthy
+func (c *MilvusCache) CheckConnection() error {
+	if !c.enabled {
+		return nil
+	}
+
+	if c.client == nil {
+		return fmt.Errorf("milvus client is not initialized")
+	}
+
+	ctx := context.Background()
+	if c.config != nil && c.config.Connection.Timeout > 0 {
+		timeout := time.Duration(c.config.Connection.Timeout) * time.Second
+		var cancel context.CancelFunc
+		ctx, cancel = context.WithTimeout(ctx, timeout)
+		defer cancel()
+	}
+
+	// Check if we can query the collection to verify connection
+	hasCollection, err := c.client.HasCollection(ctx, c.collectionName)
+	if err != nil {
+		return fmt.Errorf("milvus connection check failed: %w", err)
+	}
+
+	if !hasCollection {
+		return fmt.Errorf("milvus collection '%s' does not exist", c.collectionName)
+	}
+
+	return nil
+}
+
 // AddPendingRequest stores a request that is awaiting its response
 func (c *MilvusCache) AddPendingRequest(requestID string, model string, query string, requestBody []byte) error {
 	start := time.Now()

src/semantic-router/pkg/cache/redis_cache.go

@@ -115,22 +115,6 @@ func NewRedisCache(options RedisCacheOptions) (*RedisCache, error) {
 		Protocol: 2, // Use RESP2 protocol for compatibility
 	})
 
-	// Test connection
-	ctx := context.Background()
-	if config.Connection.Timeout > 0 {
-		timeout := time.Duration(config.Connection.Timeout) * time.Second
-		var cancel context.CancelFunc
-		ctx, cancel = context.WithTimeout(ctx, timeout)
-		defer cancel()
-		logging.Debugf("RedisCache: connection timeout set to %s", timeout)
-	}
-
-	if err := redisClient.Ping(ctx).Err(); err != nil {
-		logging.Debugf("RedisCache: failed to connect: %v", err)
-		return nil, fmt.Errorf("failed to connect to Redis: %w", err)
-	}
-	logging.Debugf("RedisCache: successfully connected to Redis")
-
 	cache := &RedisCache{
 		client:              redisClient,
 		config:              config,
@@ -140,6 +124,13 @@ func NewRedisCache(options RedisCacheOptions) (*RedisCache, error) {
 		enabled:             options.Enabled,
 	}
 
+	// Test connection using the new CheckConnection method
+	if err := cache.CheckConnection(); err != nil {
+		logging.Debugf("RedisCache: failed to connect: %v", err)
+		return nil, err
+	}
+	logging.Debugf("RedisCache: successfully connected to Redis")
+
 	// Set up the index for vector search
 	logging.Debugf("RedisCache: initializing index '%s'", config.Index.Name)
 	if err := cache.initializeIndex(); err != nil {
@@ -350,6 +341,31 @@ func (c *RedisCache) IsEnabled() bool {
 	return c.enabled
 }
 
+// CheckConnection verifies the Redis connection is healthy
+func (c *RedisCache) CheckConnection() error {
+	if !c.enabled {
+		return nil
+	}
+
+	if c.client == nil {
+		return fmt.Errorf("redis client is not initialized")
+	}
+
+	ctx := context.Background()
+	if c.config != nil && c.config.Connection.Timeout > 0 {
+		timeout := time.Duration(c.config.Connection.Timeout) * time.Second
+		var cancel context.CancelFunc
+		ctx, cancel = context.WithTimeout(ctx, timeout)
+		defer cancel()
+	}
+
+	if err := c.client.Ping(ctx).Err(); err != nil {
+		return fmt.Errorf("redis connection check failed: %w", err)
+	}
+
+	return nil
+}
+
 // AddPendingRequest stores a request that is awaiting its response
 func (c *RedisCache) AddPendingRequest(requestID string, model string, query string, requestBody []byte) error {
 	start := time.Now()