Add basic cron support

gateway.py

@@ -1,9 +1,27 @@
+from queue import Queue
+
+from apscheduler.schedulers.background import BackgroundScheduler
+
 from config import settings
 from mqtt import MqttClient
 from workers_manager import WorkersManager
 
+queue = Queue()
+scheduler = BackgroundScheduler()
 mqtt = MqttClient(settings['mqtt'])
-
 manager = WorkersManager(settings['workers'])
-for worker_name in manager.workers.keys():
-  mqtt.publish(manager.update(worker_name))
+
+for worker_name, interval in manager.interval_enabled_workers.items():
+  queue.put([worker_name])
+  scheduler.add_job(lambda x: queue.put([x]), 'interval', seconds=interval, args=[worker_name])
+
+scheduler.start()
+
+while True:
+  for worker_name in queue.get(block=True):
+    try:
+      mqtt.publish(manager.update(worker_name))
+    except (KeyboardInterrupt, SystemExit):
+      raise
+    except:
+      print('Some error')