Replace six.iteritems() with .items()

we should avoid using six.iteritems to achieve iterators.
We can use dict.items instead, as it will return iterators in PY3 as well.
And dict.items/keys will be more readable.

In py2, the performance about list should be negligible

Change-Id: I972b6eb73620eea0cae8b1e0ed9df5f80213bf3d

kingbird/api/controllers/quota_manager.py

@@ -23,7 +23,6 @@ from pecan import expose
 from pecan import request
 
 import restcomm
-import six
 
 from kingbird.common import exceptions
 from kingbird.common.i18n import _
@@ -215,7 +214,7 @@ class QuotaManagerController(object):
         if CONF.use_default_quota_class:
             default_quotas = db_api.quota_class_get_default(context)
 
-        for resource, default in six.iteritems(config_defaults):
+        for resource, default in config_defaults.items():
             # get rid of the 'quota_' prefix
             resource_name = resource[6:]
             if default_quotas:

kingbird/api/controllers/v1/quota_class.py

@@ -18,8 +18,6 @@ import pecan
 from pecan import expose
 from pecan import request
 
-import six
-
 from kingbird.api.controllers import restcomm
 from kingbird.common import consts
 from kingbird.common import exceptions
@@ -94,7 +92,7 @@ class QuotaClassSetController(object):
 
         utils.validate_quota_limits(quota_class_set)
 
-        for key, value in six.iteritems(quota_class_set):
+        for key, value in quota_class_set.items():
             try:
                 db_api.quota_class_update(context, class_name, key, value)
             except exceptions.QuotaClassNotFound:

kingbird/common/serializer.py

@@ -12,7 +12,6 @@
 # implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-import six
 
 import oslo_messaging
 
@@ -23,7 +22,7 @@ class Mapping(object):
     def __init__(self, mapping):
         self.direct_mapping = mapping
         self.reverse_mapping = {}
-        for key, value in six.iteritems(mapping):
+        for key, value in mapping.items():
             self.reverse_mapping[value] = key
 
 _SINGLETON_MAPPING = Mapping({
@@ -38,7 +37,7 @@ class KingbirdSerializer(oslo_messaging.Serializer):
 
     def serialize_entity(self, context, entity):
         if isinstance(entity, dict):
-            for key, value in six.iteritems(entity):
+            for key, value in entity.items():
                 entity[key] = self.serialize_entity(context, value)
 
         elif isinstance(entity, list):
@@ -55,7 +54,7 @@ class KingbirdSerializer(oslo_messaging.Serializer):
 
     def deserialize_entity(self, context, entity):
         if isinstance(entity, dict):
-            for key, value in six.iteritems(entity):
+            for key, value in entity.items():
                 entity[key] = self.deserialize_entity(context, value)
 
         elif isinstance(entity, list):

kingbird/db/sqlalchemy/migrate_repo/versions/004_default_quota_class.py

@@ -13,7 +13,6 @@
 
 import datetime
 from oslo_config import cfg
-import six
 import sqlalchemy
 
 CLASS_NAME = 'default'
@@ -40,7 +39,7 @@ def upgrade(migrate_engine):
 
     # Set default quota limits
     qci = quota_classes.insert()
-    for resource, default in six.iteritems(CONF.kingbird_global_limit):
+    for resource, default in CONF.kingbird_global_limit.items():
         qci.execute({'created_at': CREATED_AT,
                      'class_name': CLASS_NAME,
                      'resource': resource[6:],