Merge pull request #179 from cartsnitch/feature/cart-550-api-lifespan-pooling

feat(api): implement FastAPI lifespan with connection pooling (CAR-550)

api/src/cartsnitch_api/cache.py

@@ -1,26 +1,51 @@
 """Redis/DragonflyDB caching helpers."""
 
+import redis.asyncio as redis
+
 from cartsnitch_api.config import settings
 
 
 class CacheClient:
-    """Stub for Redis/DragonflyDB caching.
+    """Redis/DragonflyDB caching with connection pooling.
 
     Will be used for expensive queries: price trends, product comparisons.
     Cache invalidation via Redis pub/sub events from other services.
     """
 
     def __init__(self) -> None:
-        self.url = settings.redis_url
+        self._pool: redis.ConnectionPool | None = None
+        self._client: redis.Redis | None = None
+
+    async def initialize(self) -> None:
+        """Initialize the Redis connection pool."""
+        self._pool = redis.ConnectionPool.from_url(
+            settings.redis_url,
+            max_connections=20,
+            decode_responses=True,
+        )
+        self._client = redis.Redis(connection_pool=self._pool)
+
+    async def close(self) -> None:
+        """Close the Redis connection pool."""
+        if self._client:
+            await self._client.aclose()
+        if self._pool:
+            await self._pool.aclose()
 
     async def get(self, key: str) -> str | None:
-        # TODO: implement with redis-py async
-        return None
+        if not self._client:
+            return None
+        return await self._client.get(key)
 
     async def set(self, key: str, value: str, ttl_seconds: int = 300) -> None:
-        # TODO: implement with redis-py async
-        pass
+        if not self._client:
+            return
+        await self._client.set(key, value, ex=ttl_seconds)
 
     async def delete(self, key: str) -> None:
-        # TODO: implement with redis-py async
-        pass
+        if not self._client:
+            return
+        await self._client.delete(key)
+
+
+cache_client = CacheClient()

api/src/cartsnitch_api/database.py

@@ -6,7 +6,14 @@ from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_asyn
 
 from cartsnitch_api.config import settings
 
-engine = create_async_engine(settings.database_url, echo=False)
+engine = create_async_engine(
+    settings.database_url,
+    echo=False,
+    pool_size=10,
+    max_overflow=20,
+    pool_pre_ping=True,
+    pool_recycle=3600,
+)
 async_session_factory = async_sessionmaker(engine, class_=AsyncSession, expire_on_commit=False)
 
 
@@ -14,3 +21,8 @@ async def get_db() -> AsyncGenerator[AsyncSession, None]:
     """FastAPI dependency that yields an async DB session."""
     async with async_session_factory() as session:
         yield session
+
+
+async def dispose_engine() -> None:
+    """Dispose the database engine, closing all pooled connections."""
+    await engine.dispose()

api/src/cartsnitch_api/main.py

@@ -5,6 +5,8 @@ from contextlib import asynccontextmanager
 from fastapi import APIRouter, FastAPI
 
 from cartsnitch_api.auth.routes import router as auth_router
+from cartsnitch_api.cache import cache_client
+from cartsnitch_api.database import dispose_engine
 from cartsnitch_api.middleware.cors import add_cors_middleware
 from cartsnitch_api.middleware.error_handler import add_error_handlers, add_error_monitor_middleware
 from cartsnitch_api.middleware.rate_limit import add_rate_limit_middleware
@@ -23,9 +25,10 @@ from cartsnitch_api.routes.user import router as user_router
 
 @asynccontextmanager
 async def lifespan(app: FastAPI):
-    # TODO: initialize DB session pool, Redis connection, service clients
+    await cache_client.initialize()
     yield
-    # TODO: cleanup connections
+    await cache_client.close()
+    await dispose_engine()
 
 
 def create_app() -> FastAPI: