feat: implement async scheduler with lifespan management and update README

app/main.py

@@ -22,6 +22,7 @@ from app.middleware.profiler import ProfilingMiddleware
 from app.redis import get_redis
 from app.services.auth import AuthBearer
 from app.services.chat_agent import build_chat_agent
+from app.services.scheduler import scheduler_lifespan
 
 templates = Jinja2Templates(directory=Path(__file__).parent.parent / "templates")
 
@@ -45,7 +46,8 @@ async def lifespan(app: FastAPI):
         # await app.logger.ainfo(
         #     "Postgres pool created", idle_size=app.postgres_pool.get_idle_size()
         # )
-        yield
+        async with scheduler_lifespan():
+            yield
     except Exception as e:
         await app.logger.aerror("Error during app startup", error=repr(e))
         raise
@@ -96,16 +98,4 @@ def create_app() -> FastAPI:
 
 app = create_app()
 
-# --- Unused/experimental code and TODOs ---
-# from apscheduler import AsyncScheduler
-# from apscheduler.datastores.sqlalchemy import SQLAlchemyDataStore
-# from apscheduler.eventbrokers.redis import RedisEventBroker
-# from app.database import engine
-# from app.services.scheduler import SchedulerMiddleware
-# _scheduler_data_store = SQLAlchemyDataStore(engine, schema="scheduler")
-# _scheduler_event_broker = RedisEventBroker(client_or_url=global_settings.redis_url.unicode_string())
-# _scheduler_himself = AsyncScheduler(_scheduler_data_store, _scheduler_event_broker)
-# app.add_middleware(SchedulerMiddleware, scheduler=_scheduler_himself)
 # TODO: every non-GET method should reset cache
-# TODO: scheduler tasks needing DB should access connection pool via request
-# TODO: https://stackoverflow.com/questions/16053364/make-sure-only-one-worker-launches-the-apscheduler-event-in-a-pyramid-web-app-ru

app/services/scheduler.py

@@ -1,13 +1,16 @@
+from collections.abc import AsyncIterator
+from contextlib import asynccontextmanager
 from datetime import datetime
 
-from apscheduler import AsyncScheduler
+from apscheduler import AsyncScheduler, ConflictPolicy
+from apscheduler.datastores.sqlalchemy import SQLAlchemyDataStore
+from apscheduler.eventbrokers.redis import RedisEventBroker
 from apscheduler.triggers.interval import IntervalTrigger
-from attrs import define
 from rotoger import get_logger
 from sqlalchemy import text
-from starlette.types import ASGIApp, Receive, Scope, Send
 
-from app.database import AsyncSessionFactory
+from app.config import settings as global_settings
+from app.database import AsyncSessionFactory, engine
 
 logger = get_logger()
 
@@ -21,26 +24,19 @@ async def tick():
         return True
 
 
-@define
-class SchedulerMiddleware:
-    app: ASGIApp
-    scheduler: AsyncScheduler
+@asynccontextmanager
+async def scheduler_lifespan() -> AsyncIterator[None]:
+    scheduler = AsyncScheduler(
+        SQLAlchemyDataStore(engine, schema="scheduler"),
+        RedisEventBroker(client_or_url=global_settings.redis_url.unicode_string()),
+    )
 
-    async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None:
-        """
-        Handles the incoming request and schedules tasks if the scope type is 'lifespan'.
-
-        Args:
-            scope (Scope): The ASGI scope dictionary containing request information.
-            receive (Receive): The ASGI receive callable.
-            send (Send): The ASGI send callable.
-        """
-        if scope["type"] == "lifespan":
-            async with self.scheduler:
-                await self.scheduler.add_schedule(
-                    tick, IntervalTrigger(seconds=25), id="tick-sql-25"
-                )
-                await self.scheduler.start_in_background()
-                await self.app(scope, receive, send)
-        else:
-            await self.app(scope, receive, send)
+    async with scheduler:
+        await scheduler.add_schedule(
+            tick,
+            IntervalTrigger(seconds=25),
+            id="tick-sql-25",
+            conflict_policy=ConflictPolicy.replace,
+        )
+        await scheduler.start_in_background()
+        yield