[#340] Ironed out some bugs in the alarm integration.

- The alarm ID should be randomly generated - auto-increment IDs are
  subject to race conditions when alarms are created in separate
  processes.

- Clean up alarms that are not static and have been removed from the db.

- Better alarm shut down detection logic.

platypush/plugins/alarm/__init__.py

@@ -167,6 +167,13 @@ class AlarmPlugin(RunnablePlugin, EntityManager):
                         media_plugin=alarm.media_plugin or self.media_plugin,
                     )
 
+        # Stop and remove alarms that are not statically configured no longer
+        # present in the db
+        for name, alarm in self.alarms.copy().items():
+            if not alarm.static and name not in alarms:
+                del self.alarms[name]
+                alarm.stop()
+
     def _sync_alarms(self):
         with self._get_session() as session:
             db_alarms = {
@@ -184,15 +191,16 @@ class AlarmPlugin(RunnablePlugin, EntityManager):
             self._synced = True
 
     def _clear_alarm(self, alarm: DbAlarm, session: Session):
-        self.alarms.pop(str(alarm.name), None)
+        alarm_obj = self.alarms.pop(str(alarm.name), None)
+        if alarm_obj:
+            alarm_obj.stop()
+
         session.delete(alarm)
         self._bus.post(EntityDeleteEvent(entity=alarm))
 
     def _clear_expired_alarms(self, session: Session):
         expired_alarms = [
-            alarm
-            for alarm in self.alarms.values()
-            if alarm.is_expired() and alarm.is_shut_down()
+            alarm for alarm in self.alarms.values() if alarm.should_stop()
         ]
 
         if not expired_alarms:
@@ -220,7 +228,7 @@ class AlarmPlugin(RunnablePlugin, EntityManager):
             iter(
                 alarm
                 for alarm in self.alarms.values()
-                if alarm.state == AlarmState.RUNNING
+                if alarm.state in {AlarmState.RUNNING, AlarmState.SNOOZED}
             ),
             None,
         )
@@ -233,6 +241,9 @@ class AlarmPlugin(RunnablePlugin, EntityManager):
 
     def _on_alarm_update(self, alarm: Alarm):
         with self._db_lock:
+            if alarm.should_stop():
+                return
+
             self.publish_entities([alarm])
 
     def _add(

platypush/plugins/alarm/_model.py

@@ -3,6 +3,7 @@ import enum
 import os
 import time
 import threading
+from random import randint
 from typing import Callable, Optional, Union
 
 import croniter
@@ -40,9 +41,6 @@ class Alarm:
     Alarm model and controller.
     """
 
-    _alarms_count = 0
-    _id_lock = threading.RLock()
-
     def __init__(
         self,
         when: Union[str, int, float],
@@ -59,10 +57,7 @@ class Alarm:
         on_change: Optional[Callable[['Alarm'], None]] = None,
         **_,
     ):
-        with self._id_lock:
-            self._alarms_count += 1
-            self.id = self._alarms_count
-
+        self.id = randint(0, 65535)
         self.when = when
         self.name = name or f'Alarm_{self.id}'
         self.media = self._get_media_resource(media)
@@ -240,10 +235,10 @@ class Alarm:
                             sleep_time = self._runtime_snooze_interval
                         else:
                             self.state = AlarmState.WAITING
-                            self._on_change()
 
                         break
 
+                    self._on_change()
                     self.wait_stop(self.poll_interval)
 
             if self.state == AlarmState.SNOOZED:
@@ -266,7 +261,11 @@ class Alarm:
         self.stop_event.wait(timeout)
 
     def should_stop(self):
-        return self.stop_event.is_set() or (self.is_expired() and self.is_shut_down())
+        return (
+            self.stop_event.is_set()
+            or (self.is_expired() and self.state == AlarmState.DISMISSED)
+            or self.state == AlarmState.SHUTDOWN
+        )
 
     def to_dict(self) -> dict:
         return {