Tidy up sensor policy, and fix termination bug

epu/decisionengine/impls/sensor.py

@@ -222,15 +222,17 @@ def decide(self, control, state):
         time_since_last_action = datetime.now() - self.time_of_last_scale_action
         if time_since_last_action < cooldown:
             log.debug("No scaling action, in cooldown period")
-            scale_by = 0
+            return
         elif self.metric is not None and self.sample_function is not None:
             values = []
             for instance_id in valid_set:
                 instance = state.instances[instance_id]
-                if hasattr(instance, 'sensor_data') and instance.sensor_data:
+                if (hasattr(instance, 'sensor_data') and instance.sensor_data and
+                    instance.sensor_data.get(self.sample_function)):
                     values.append(instance.sensor_data[self.sample_function])
             try:
-                average_metric = float(sum(values)) / float(len(values))
+                divisor = max(len(values), valid_count)
+                average_metric = float(sum(values)) / float(divisor)
             except ZeroDivisionError:
                 average_metric = None
 
@@ -243,9 +245,12 @@ def decide(self, control, state):
             else:
                 scale_by = 0
 
-            self.time_of_last_scale_action = datetime.now()
+            if scale_by != 0:
+                self.time_of_last_scale_action = datetime.now()
+
+
         else:
-            log.debug("No sensor metric or sample function specified. Not scaling")
+            # No sensor metric or sample function specified. Not scaling
             scale_by = 0
 
         wanted_target = valid_count + scale_by
@@ -313,7 +318,8 @@ def _launch_one(self, control, extravars=None):
             log.info("Launched an instance ('%s')", instance_ids[0])
 
     def _destroy_one(self, control, instanceid):
-        control.destroy_instances([instanceid])
+        owner = control.domain.owner
+        control.destroy_instances([instanceid], caller=owner)
         log.info("Destroyed an instance ('%s')" % instanceid)
 
     def reconfigure(self, control, newconf):

epu/epumanagement/decider.py

@@ -214,7 +214,6 @@ def _get_engine_sensor_state(self, domain):
         end_time = datetime.utcnow()
         start_time = end_time - timedelta(seconds=sample_period)
 
-        sensor_state = {}
         instances = domain.get_instances()
         for instance in instances:
             if 'ec2' not in instance.site and sensor_type == CLOUDWATCH_SENSOR_TYPE:
@@ -231,14 +230,19 @@ def _get_engine_sensor_state(self, domain):
                 continue
 
             dimensions = {'InstanceId': instance.iaas_id}
+            sensor_state = {}
             state = sensor_aggregator.get_metric_statistics(period, start_time,
                     end_time, metric, sample_function, dimensions)
-            for iaas_id, metric in state.iteritems():
-                series = metric.get(Statistics.SERIES)
+            for iaas_id, metric_result in state.iteritems():
+                if iaas_id != instance.iaas_id:
+                    continue
+                series = metric_result.get(Statistics.SERIES)
                 if series is not None and series != []:
-                    sensor_state[instance.instance_id] = metric
+                    sensor_state[instance.instance_id] = metric_result
+
+            if sensor_state != {}:
+                domain.new_instance_sensor(instance.instance_id, sensor_state)
 
-            domain.new_instance_sensor(instance.instance_id, sensor_state)
 
     def _get_sensor_aggregator(self, config):
         sensor_type = config.get(CONF_SENSOR_TYPE)