Refactor database connection handling in API endpoints

- Removed direct pool checks and replaced them with a centralized database initialization method in `init_db`.
- Updated API endpoints in `admin.py`, `collection.py`, `pins.py`, and `watched.py` to ensure the database connection pool is initialized before usage.
- Enhanced error handling to raise HTTP exceptions if the database is unavailable.
- Improved the `init_db` function in `database.py` to prevent multiple simultaneous initializations using an asyncio lock.

backend/app/api/admin.py

@@ -1,7 +1,6 @@
 """Admin API endpoints"""
 from fastapi import APIRouter, HTTPException, Header
 from typing import Optional
-from app.core.database import pool
 from app.core.config import settings
 from app.services.sync import sync_all_arrs
 

backend/app/api/collection.py

@@ -1,7 +1,6 @@
 """Collection API endpoints"""
 from fastapi import APIRouter, Query
 from typing import List, Optional
-from app.core.database import pool
 import json
 
 router = APIRouter()
@@ -15,17 +14,20 @@ async def get_collection_summary(
     Get collection summary by country and media type.
     Returns counts per country per media type.
     """
-    # Pool should be initialized on startup, but check just in case
-    if not pool:
-        from app.core.database import init_db
+    # Ensure pool is initialized
+    from app.core.database import init_db, pool as db_pool
     await init_db()
     
+    if db_pool is None:
+        from fastapi import HTTPException
+        raise HTTPException(status_code=503, detail="Database not available")
+    
     # Parse types filter
     type_filter = []
     if types:
         type_filter = [t.strip() for t in types.split(",") if t.strip() in ["movie", "show", "music"]]
     
-    async with pool.connection() as conn:
+    async with db_pool.connection() as conn:
         async with conn.cursor() as cur:
             # Build query
             query = """

backend/app/api/pins.py

@@ -3,7 +3,7 @@ from fastapi import APIRouter, HTTPException
 from pydantic import BaseModel
 from typing import Optional
 from uuid import UUID
-from app.core.database import pool
+from app.core.database import init_db, pool as db_pool
 
 router = APIRouter()
 
@@ -16,12 +16,11 @@ class PinCreate(BaseModel):
 @router.get("")
 async def list_pins():
     """List all manual pins"""
-    # Pool should be initialized on startup
-    if not pool:
-        from app.core.database import init_db
     await init_db()
+    if db_pool is None:
+        raise HTTPException(status_code=503, detail="Database not available")
     
-    async with pool.connection() as conn:
+    async with db_pool.connection() as conn:
         async with conn.cursor() as cur:
             query = """
                 SELECT id, country_code, label, pinned_at
@@ -46,12 +45,11 @@ async def list_pins():
 @router.post("")
 async def create_pin(pin: PinCreate):
     """Create a new manual pin"""
-    # Pool should be initialized on startup
-    if not pool:
-        from app.core.database import init_db
     await init_db()
+    if db_pool is None:
+        raise HTTPException(status_code=503, detail="Database not available")
     
-    async with pool.connection() as conn:
+    async with db_pool.connection() as conn:
         async with conn.cursor() as cur:
             query = """
                 INSERT INTO moviemap.manual_pin (country_code, label)
@@ -68,12 +66,11 @@ async def create_pin(pin: PinCreate):
 @router.delete("/{pin_id}")
 async def delete_pin(pin_id: UUID):
     """Delete a manual pin"""
-    # Pool should be initialized on startup
-    if not pool:
-        from app.core.database import init_db
     await init_db()
+    if db_pool is None:
+        raise HTTPException(status_code=503, detail="Database not available")
     
-    async with pool.connection() as conn:
+    async with db_pool.connection() as conn:
         async with conn.cursor() as cur:
             query = "DELETE FROM moviemap.manual_pin WHERE id = %s RETURNING id"
             await cur.execute(query, (str(pin_id),))

backend/app/api/watched.py

@@ -4,7 +4,7 @@ from pydantic import BaseModel
 from typing import Optional
 from datetime import datetime
 from uuid import UUID
-from app.core.database import pool
+from app.core.database import init_db, pool as db_pool
 import json
 
 router = APIRouter()
@@ -30,12 +30,11 @@ class WatchedItemUpdate(BaseModel):
 @router.get("/summary")
 async def get_watched_summary():
     """Get watched items summary by country"""
-    # Pool should be initialized on startup
-    if not pool:
-        from app.core.database import init_db
     await init_db()
+    if db_pool is None:
+        raise HTTPException(status_code=503, detail="Database not available")
     
-    async with pool.connection() as conn:
+    async with db_pool.connection() as conn:
         async with conn.cursor() as cur:
             query = """
                 SELECT 
@@ -63,12 +62,11 @@ async def get_watched_summary():
 @router.get("")
 async def list_watched_items():
     """List all watched items"""
-    # Pool should be initialized on startup
-    if not pool:
-        from app.core.database import init_db
     await init_db()
+    if db_pool is None:
+        raise HTTPException(status_code=503, detail="Database not available")
     
-    async with pool.connection() as conn:
+    async with db_pool.connection() as conn:
         async with conn.cursor() as cur:
             query = """
                 SELECT 
@@ -100,15 +98,14 @@ async def list_watched_items():
 @router.post("")
 async def create_watched_item(item: WatchedItemCreate):
     """Create a new watched item"""
-    # Pool should be initialized on startup
-    if not pool:
-        from app.core.database import init_db
     await init_db()
+    if db_pool is None:
+        raise HTTPException(status_code=503, detail="Database not available")
     
     if item.media_type not in ["movie", "show"]:
         raise HTTPException(status_code=400, detail="media_type must be 'movie' or 'show'")
     
-    async with pool.connection() as conn:
+    async with db_pool.connection() as conn:
         async with conn.cursor() as cur:
             query = """
                 INSERT INTO moviemap.watched_item 
@@ -136,12 +133,11 @@ async def create_watched_item(item: WatchedItemCreate):
 @router.patch("/{item_id}")
 async def update_watched_item(item_id: UUID, item: WatchedItemUpdate):
     """Update a watched item"""
-    # Pool should be initialized on startup
-    if not pool:
-        from app.core.database import init_db
     await init_db()
+    if db_pool is None:
+        raise HTTPException(status_code=503, detail="Database not available")
     
-    async with pool.connection() as conn:
+    async with db_pool.connection() as conn:
         async with conn.cursor() as cur:
             # Build dynamic update query
             updates = []
@@ -189,12 +185,11 @@ async def update_watched_item(item_id: UUID, item: WatchedItemUpdate):
 @router.delete("/{item_id}")
 async def delete_watched_item(item_id: UUID):
     """Delete a watched item"""
-    # Pool should be initialized on startup
-    if not pool:
-        from app.core.database import init_db
     await init_db()
+    if db_pool is None:
+        raise HTTPException(status_code=503, detail="Database not available")
     
-    async with pool.connection() as conn:
+    async with db_pool.connection() as conn:
         async with conn.cursor() as cur:
             query = "DELETE FROM moviemap.watched_item WHERE id = %s RETURNING id"
             await cur.execute(query, (str(item_id),))

backend/app/core/database.py

@@ -4,16 +4,37 @@ from psycopg_pool import AsyncConnectionPool
 from app.core.config import settings
 from typing import Optional
 import logging
+import asyncio
 
 logger = logging.getLogger(__name__)
 
 # Connection pool
 pool: Optional[AsyncConnectionPool] = None
+_init_lock = asyncio.Lock()
+_initializing = False
 
 
 async def init_db():
     """Initialize database connection pool"""
-    global pool
+    global pool, _initializing
+    
+    # If already initialized, return
+    if pool is not None:
+        return
+    
+    # Use lock to prevent multiple simultaneous initializations
+    async with _init_lock:
+        # Double-check after acquiring lock
+        if pool is not None:
+            return
+        
+        if _initializing:
+            # Wait for other initialization to complete
+            while _initializing:
+                await asyncio.sleep(0.1)
+            return
+        
+        _initializing = True
         try:
             pool = AsyncConnectionPool(
                 conninfo=settings.database_url,
@@ -25,7 +46,10 @@ async def init_db():
             logger.info("Database connection pool initialized")
         except Exception as e:
             logger.error(f"Failed to initialize database pool: {e}")
+            pool = None
             raise
+        finally:
+            _initializing = False
 
 
 async def close_db():

backend/app/services/sync.py

@@ -3,7 +3,6 @@ import httpx
 import logging
 from typing import Dict, List, Optional
 from app.core.config import settings
-from app.core.database import pool
 import json
 
 logger = logging.getLogger(__name__)
@@ -130,12 +129,12 @@ def extract_country_from_lidarr(artist: Dict) -> Optional[str]:
 async def upsert_media_item(source_kind: str, source_item_id: int, title: str, 
                            year: Optional[int], media_type: str, arr_raw: Dict):
     """Upsert a media item into the database"""
-    # Pool should be initialized on startup
-    if not pool:
-        from app.core.database import init_db
+    from app.core.database import init_db, pool as db_pool
     await init_db()
+    if db_pool is None:
+        raise Exception("Database not available")
     
-    async with pool.connection() as conn:
+    async with db_pool.connection() as conn:
         async with conn.cursor() as cur:
             # Upsert media item
             query = """
@@ -273,12 +272,13 @@ async def sync_all_arrs() -> Dict:
         logger.error(f"Lidarr sync failed: {e}")
         results["lidarr"] = 0
     
-    # Update last sync time (pool should be initialized)
-    if not pool:
-        from app.core.database import init_db
+    # Update last sync time
+    from app.core.database import init_db, pool as db_pool
     await init_db()
+    if db_pool is None:
+        raise Exception("Database not available")
     
-    async with pool.connection() as conn:
+    async with db_pool.connection() as conn:
         async with conn.cursor() as cur:
             for source_kind in ["radarr", "sonarr", "lidarr"]:
                 await cur.execute(