cancel all long-running tasks (#1793)

* add centralized task management

in order to properly cleanup all long-running tasks we have to keep a list of them

* use new task management functions

* unify shutdown events

* vlads suggestions

rename variable for create_task
wrap cancel() with try/catch

fixup

* rename func to coro

---------

Co-authored-by: dni ⚡ <office@dnilabs.com>

lnbits/tasks.py

@@ -3,7 +3,7 @@ import time
 import traceback
 import uuid
 from http import HTTPStatus
-from typing import Dict, Optional
+from typing import Dict, List, Optional
 
 from fastapi.exceptions import HTTPException
 from loguru import logger
@@ -19,6 +19,26 @@ from lnbits.wallets import get_wallet_class
 
 from .core import db
 
+tasks: List[asyncio.Task] = []
+
+
+def create_task(coro):
+    task = asyncio.create_task(coro)
+    tasks.append(task)
+    return task
+
+
+def create_permanent_task(func):
+    return create_task(catch_everything_and_restart(func))
+
+
+def cancel_all_tasks():
+    for task in tasks:
+        try:
+            task.cancel()
+        except Exception as exc:
+            logger.warning(f"error while cancelling task: {str(exc)}")
+
 
 async def catch_everything_and_restart(func):
     try: