Remove six.iter*

As mentioned in [1], we should avoid using
six.iteritems/six.iterkeys to achieve iterators.
Let's use dict.items/dict.keys instead, as
it should return iterators in PY3 as well.
(As for PY2, the performance about list should
be negligible)

[1] https://wiki.openstack.org/wiki/Python3

Change-Id: Ia9659075a206b3b4d3a0dc7eb3b006b7b43f8f4d

cinder/scheduler/filters/capabilities_filter.py

@@ -14,7 +14,6 @@
 #    under the License.
 
 from oslo_log import log as logging
-import six
 
 from cinder.scheduler import filters
 from cinder.scheduler.filters import extra_specs_ops
@@ -35,7 +34,7 @@ class CapabilitiesFilter(filters.BaseHostFilter):
         if not extra_specs:
             return True
 
-        for key, req in six.iteritems(extra_specs):
+        for key, req in extra_specs.items():
 
             # Either not scoped format, or in capabilities scope
             scope = key.split(':')

cinder/tests/unit/scheduler/fake_hosts.py

@@ -17,8 +17,6 @@
 Fakes For filters tests.
 """
 
-import six
-
 
 class FakeHostManager(object):
     """Defines fake hosts.
@@ -49,5 +47,5 @@ class FakeHostManager(object):
 class FakeHostState(object):
     def __init__(self, host, attribute_dict):
         self.host = host
-        for (key, val) in six.iteritems(attribute_dict):
+        for (key, val) in attribute_dict.items():
             setattr(self, key, val)

cinder/tests/unit/volume/drivers/netapp/test_common.py

@@ -13,7 +13,6 @@
 #    under the License.
 
 import mock
-import six
 
 from cinder import exception
 from cinder import test
@@ -91,7 +90,7 @@ class NetAppDriverFactoryTestCase(test.TestCase):
 
         registry = na_common.NETAPP_UNIFIED_DRIVER_REGISTRY
 
-        for family in six.iterkeys(registry):
+        for family in registry:
             for protocol, full_class_name in registry[family].items():
                 driver = na_common.NetAppDriver.create_driver(
                     family, protocol, **kwargs)

cinder/volume/drivers/vmware/volumeops.py

@@ -23,7 +23,6 @@ from oslo_utils import units
 from oslo_vmware import exceptions
 from oslo_vmware import pbm
 from oslo_vmware import vim_util
-import six
 from six.moves import urllib
 
 from cinder.i18n import _, _LE, _LI
@@ -688,7 +687,7 @@ class VMwareVolumeOps(object):
         cf = self._session.vim.client.factory
         option_values = []
 
-        for key, value in six.iteritems(extra_config):
+        for key, value in extra_config.items():
             opt = cf.create('ns0:OptionValue')
             opt.key = key
             opt.value = value