unicode error in event converter

it's possible that a unicode error be thrown when attempting to
convert notification to event. this patch uses six to handle this
issue.

Closes-Bug: #1421430
Change-Id: Icf450792fd2921344c2a432e5a72be18dda33ac9

ceilometer/event/storage/models.py

@@ -13,6 +13,7 @@
 """Model classes for use in the events storage API.
 """
 from oslo_utils import timeutils
+import six
 
 from ceilometer.storage import base
 
@@ -51,7 +52,7 @@ class Event(base.Model):
     def __repr__(self):
         trait_list = []
         if self.traits:
-            trait_list = [str(trait) for trait in self.traits]
+            trait_list = [six.text_type(trait) for trait in self.traits]
         return ("<Event: %s, %s, %s, %s>" %
                 (self.message_id, self.event_type, self.generated,
                  " ".join(trait_list)))
@@ -117,4 +118,4 @@ class Trait(base.Model):
             return float(value)
         if trait_type is cls.DATETIME_TYPE:
             return timeutils.normalize_time(timeutils.parse_isotime(value))
-        return str(value)
+        return six.text_type(value)

ceilometer/event/trait_plugins.py

@@ -110,7 +110,7 @@ class SplitterTraitPlugin(TraitPluginBase):
     def trait_value(self, match_list):
         if not match_list:
             return None
-        value = str(match_list[0][1])
+        value = six.text_type(match_list[0][1])
         if self.max_split is not None:
             values = value.split(self.separator, self.max_split)
         else:

ceilometer/tests/storage/test_models.py

@@ -16,6 +16,7 @@
 import datetime
 
 from oslotest import base as testbase
+import six
 
 from ceilometer.alarm.storage import models as alarm_models
 from ceilometer.event.storage import models as event_models
@@ -109,7 +110,7 @@ class TestTraitModel(testbase.BaseTestCase):
         v = event_models.Trait.convert_value(
             event_models.Trait.TEXT_TYPE, 10)
         self.assertEqual("10", v)
-        self.assertIsInstance(v, str)
+        self.assertIsInstance(v, six.text_type)
 
 
 class TestClassModel(testbase.BaseTestCase):