Unify the database connection lifecycle across all workers

workers/worker.py

@@ -6,12 +6,10 @@ import socket
 from threading import Event
 from apscheduler.schedulers.background import BackgroundScheduler
 from datetime import datetime, timedelta
-from threading import Thread
-from time import sleep
 from raven import Client
 
 from app import app
-from data.model import db
+from data.database import UseThenDisconnect
 from functools import wraps
 
 logger = logging.getLogger(__name__)
@@ -44,7 +42,8 @@ class Worker(object):
     @wraps(operation_func)
     def _operation_func():
       try:
-        return operation_func()
+        with UseThenDisconnect(app.config):
+          return operation_func()
       except Exception:
         logger.exception('Operation raised exception')
         if self._raven_client: