improved redis singleton (#106)

Author: cyclotruc

src/backend/cache/redis_client.py

@@ -1,4 +1,5 @@
 import os
+import asyncio
 from redis import asyncio as aioredis
 from dotenv import load_dotenv
 
@@ -15,30 +16,55 @@ class RedisClient:
     """Service for managing Redis connections with proper lifecycle management."""
 
     _instance = None
+    _client = None
+    _lock = asyncio.Lock()
 
     @classmethod
     async def get_instance(cls) -> aioredis.Redis:
-        """Get or create a Redis client instance."""
-        if cls._instance is None:
-            cls._instance = cls()
-            await cls._instance.initialize()
-        return cls._instance.client
+        """Get or create a Redis client instance with proper singleton behavior."""
+        if cls._client is None:
+            async with cls._lock:
+                # Double-check pattern to prevent race conditions
+                if cls._client is None:
+                    if cls._instance is None:
+                        cls._instance = cls()
+                    await cls._instance.initialize()
+        return cls._client
 
-    def __init__(self):
-        self.client = None
 
     async def initialize(self) -> None:
-        """Initialize the Redis client."""
-        self.client = aioredis.from_url(
-            REDIS_URL,
-            password=REDIS_PASSWORD,
-            decode_responses=True,
-            health_check_interval=30
-        )
-        
-    async def close(self) -> None:
-        """Close the Redis client connection."""
-        if self.client:
-            await self.client.close()
-            self.client = None
-            print("Redis client closed.")
+        """Initialize the Redis client with connection pool limits."""
+        if RedisClient._client is None:
+            try:
+                RedisClient._client = aioredis.from_url(
+                    REDIS_URL,
+                    password=REDIS_PASSWORD,
+                    decode_responses=True,
+                    health_check_interval=30,
+                    max_connections=20,  # Limit connection pool size
+                    retry_on_timeout=True,
+                    socket_keepalive=True,
+                    socket_keepalive_options={}
+                )
+                print(f"Redis client initialized with connection pool (max 20 connections)")
+                
+                # Test the connection
+                await RedisClient._client.ping()
+                
+            except Exception as e:
+                print(f"Failed to initialize Redis client: {e}")
+                RedisClient._client = None
+                raise
+    
+    @classmethod
+    async def close(cls) -> None:
+        """Close the Redis client connection and reset singleton state."""
+        if cls._client:
+            try:
+                await cls._client.close()
+                print("Redis client closed.")
+            except Exception as e:
+                print(f"Error closing Redis client: {e}")
+            finally:
+                cls._client = None
+                cls._instance = None

src/backend/main.py

@@ -49,7 +49,6 @@ async def lifespan(app: FastAPI):
 
     # Initialize Redis client and verify connection
     redis = await RedisClient.get_instance()
-    await redis.ping()
     print("Redis connection established successfully")
 
     # Initialize the canvas worker
@@ -58,9 +57,8 @@ async def lifespan(app: FastAPI):
 
     yield
 
-    # Shutdown
     await CanvasWorker.shutdown_instance()
-    await redis.close()
+    await RedisClient.close()
     await engine.dispose()
 
 app = FastAPI(lifespan=lifespan)