Apply six for metaclass

__metaclass__ cannot be used in python3.
six be used in general for python 3 compatibility.

Change-Id: I1d9909d70bb614c9d1c336d0c492027f5b6b5088
Closes-Bug: #1236648

ceilometer/alarm/evaluator/__init__.py

@@ -18,6 +18,7 @@
 
 
 import abc
+import six
 
 from oslo.config import cfg
 
@@ -33,11 +34,10 @@ OK = 'ok'
 ALARM = 'alarm'
 
 
+@six.add_metaclass(abc.ABCMeta)
 class Evaluator(object):
     """Base class for alarm rule evaluator plugins."""
 
-    __metaclass__ = abc.ABCMeta
-
     def __init__(self, notifier):
         self.notifier = notifier
         self.api_client = None

ceilometer/alarm/notifier/__init__.py

@@ -17,13 +17,13 @@
 # under the License.
 
 import abc
+import six
 
 
+@six.add_metaclass(abc.ABCMeta)
 class AlarmNotifier(object):
     """Base class for alarm notifier plugins."""
 
-    __metaclass__ = abc.ABCMeta
-
     @abc.abstractmethod
     def notify(self, action, alarm_id, previous, current, reason):
         """Notify that an alarm has been triggered.

ceilometer/alarm/service.py

@@ -19,6 +19,7 @@
 # under the License.
 
 import abc
+import six
 
 from oslo.config import cfg
 from stevedore import extension
@@ -58,10 +59,9 @@ cfg.CONF.import_opt('partition_rpc_topic', 'ceilometer.alarm.rpc',
 LOG = log.getLogger(__name__)
 
 
+@six.add_metaclass(abc.ABCMeta)
 class AlarmService(object):
 
-    __metaclass__ = abc.ABCMeta
-
     EXTENSIONS_NAMESPACE = "ceilometer.alarm.evaluator"
 
     def _load_evaluators(self):

ceilometer/collector/dispatcher/__init__.py

@@ -17,12 +17,12 @@
 # under the License.
 
 import abc
+import six
 
 
+@six.add_metaclass(abc.ABCMeta)
 class Base(object):
 
-    __metaclass__ = abc.ABCMeta
-
     def __init__(self, conf):
         self.conf = conf
 

ceilometer/compute/plugin.py

@@ -19,16 +19,16 @@
 """
 
 import abc
+import six
 
 from ceilometer import plugin
 
 
+@six.add_metaclass(abc.ABCMeta)
 class ComputePollster(plugin.PollsterBase):
     """Base class for plugins that support the polling API on the compute node.
     """
 
-    __metaclass__ = abc.ABCMeta
-
     @abc.abstractmethod
     def get_samples(self, manager, cache, instance):
         """Return a sequence of Counter instances from polling the resources.

ceilometer/plugin.py

@@ -22,6 +22,7 @@ import abc
 import collections
 import fnmatch
 from oslo.config import cfg
+import six
 
 # Import this option so every Notification plugin can use it freely.
 cfg.CONF.import_opt('notification_topics',
@@ -37,11 +38,10 @@ class PluginBase(object):
     """
 
 
+@six.add_metaclass(abc.ABCMeta)
 class NotificationBase(PluginBase):
     """Base class for plugins that support the notification API."""
 
-    __metaclass__ = abc.ABCMeta
-
     @abc.abstractproperty
     def event_types(self):
         """Return a sequence of strings defining the event types to be
@@ -85,11 +85,10 @@ class NotificationBase(PluginBase):
         return []
 
 
+@six.add_metaclass(abc.ABCMeta)
 class PollsterBase(PluginBase):
     """Base class for plugins that support the polling API."""
 
-    __metaclass__ = abc.ABCMeta
-
     @abc.abstractmethod
     def get_samples(self, manager, cache):
         """Return a sequence of Counter instances from polling the resources.

ceilometer/publisher/__init__.py

@@ -21,6 +21,7 @@
 import abc
 from stevedore import driver
 from ceilometer.openstack.common import network_utils
+import six
 
 
 def get_publisher(url, namespace='ceilometer.publisher'):
@@ -34,11 +35,10 @@ def get_publisher(url, namespace='ceilometer.publisher'):
     return loaded_driver.driver(parse_result)
 
 
+@six.add_metaclass(abc.ABCMeta)
 class PublisherBase(object):
     """Base class for plugins that publish the sampler."""
 
-    __metaclass__ = abc.ABCMeta
-
     def __init__(self, parsed_url):
         pass
 

ceilometer/storage/base.py

@@ -21,6 +21,7 @@
 import abc
 import datetime
 import math
+import six
 
 from ceilometer.openstack.common import timeutils
 
@@ -102,21 +103,19 @@ class Pagination(object):
         self.sort_dirs = sort_dirs
 
 
+@six.add_metaclass(abc.ABCMeta)
 class StorageEngine(object):
     """Base class for storage engines."""
 
-    __metaclass__ = abc.ABCMeta
-
     @abc.abstractmethod
     def get_connection(self, conf):
         """Return a Connection instance based on the configuration settings."""
 
 
+@six.add_metaclass(abc.ABCMeta)
 class Connection(object):
     """Base class for storage system connections."""
 
-    __metaclass__ = abc.ABCMeta
-
     @abc.abstractmethod
     def __init__(self, conf):
         """Constructor."""

ceilometer/tests/db.py

@@ -20,6 +20,7 @@
 
 """Base classes for API tests."""
 import os
+import six
 import uuid
 import warnings
 
@@ -78,8 +79,8 @@ class DB2FakeConnectionUrl(MongoDBFakeConnectionUrl):
             self.url = self.url.replace('mongodb:', 'db2:', 1)
 
 
+@six.add_metaclass(test_base.SkipNotImplementedMeta)
 class MixinTestsWithBackendScenarios(object):
-    __metaclass__ = test_base.SkipNotImplementedMeta
 
     scenarios = [
         ('sqlalchemy', dict(database_connection='sqlite://')),

ceilometer/transformer/__init__.py

@@ -17,6 +17,8 @@
 # under the License.
 
 import abc
+import six
+
 from stevedore import extension
 
 
@@ -35,11 +37,10 @@ class TransformerExtensionManager(extension.ExtensionManager):
         return self.by_name[name]
 
 
+@six.add_metaclass(abc.ABCMeta)
 class TransformerBase(object):
     """Base class for plugins that transform the sample."""
 
-    __metaclass__ = abc.ABCMeta
-
     def __init__(self, **kwargs):
         """Setup transformer.