Refactor backend to use request-scoped SQLite connections

backend/app/tasks/geo_cache_flush.py

@@ -15,6 +15,10 @@ from typing import TYPE_CHECKING, Any
 
 import structlog
 
+from app.db import open_db
+
+if TYPE_CHECKING:
+    import aiosqlite
 from app.services import geo_service
 
 if TYPE_CHECKING:
@@ -29,6 +33,15 @@ GEO_FLUSH_INTERVAL: int = 60
 JOB_ID: str = "geo_cache_flush"
 
 
+async def _get_db(app: Any) -> tuple[aiosqlite.Connection, bool]:
+    existing_db = getattr(app.state, "db", None)
+    if existing_db is not None:
+        return existing_db, False
+
+    db = await open_db(app.state.settings.database_path)
+    return db, True
+
+
 async def _run_flush(app: Any) -> None:
     """Flush the geo service dirty set to the application database.
 
@@ -39,8 +52,13 @@ async def _run_flush(app: Any) -> None:
         app: The :class:`fastapi.FastAPI` application instance passed via
             APScheduler ``kwargs``.
     """
-    db = app.state.db
-    count = await geo_service.flush_dirty(db)
+    db, close_db = await _get_db(app)
+    try:
+        count = await geo_service.flush_dirty(db)
+    finally:
+        if close_db:
+            await db.close()
+
     if count > 0:
         log.debug("geo_cache_flush_ran", flushed=count)