Merge "Cache security group driver"

nova/network/security_group/openstack_driver.py

@@ -21,13 +21,17 @@ import nova.network
 NOVA_DRIVER = ('nova.compute.api.SecurityGroupAPI')
 NEUTRON_DRIVER = ('nova.network.security_group.neutron_driver.'
                   'SecurityGroupAPI')
+DRIVER_CACHE = None  # singleton of the driver once loaded
 
 
 def get_openstack_security_group_driver():
-    if is_neutron_security_groups():
-        return importutils.import_object(NEUTRON_DRIVER)
-    else:
-        return importutils.import_object(NOVA_DRIVER)
+    global DRIVER_CACHE
+    if DRIVER_CACHE is None:
+        if is_neutron_security_groups():
+            DRIVER_CACHE = importutils.import_object(NEUTRON_DRIVER)
+        else:
+            DRIVER_CACHE = importutils.import_object(NOVA_DRIVER)
+    return DRIVER_CACHE
 
 
 def is_neutron_security_groups():

nova/test.py

@@ -285,7 +285,7 @@ class TestCase(base.BaseTestCase):
 
         self.useFixture(nova_fixtures.PoisonFunctions())
 
-        openstack_driver.DRIVER_CACHE = {}
+        openstack_driver.DRIVER_CACHE = None
 
         self.useFixture(nova_fixtures.ForbidNewLegacyNotificationFixture())
 

nova/tests/unit/network/test_config.py

@@ -12,6 +12,8 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
+import mock
+
 import nova.network
 import nova.network.security_group.neutron_driver
 import nova.network.security_group.openstack_driver as sgapi
@@ -55,3 +57,11 @@ class SecurityGroupAPIConfigTest(nova.test.NoDBTestCase):
         self.assertIsInstance(
             driver,
             nova.compute.api.SecurityGroupAPI)
+
+    @mock.patch('oslo_utils.importutils.import_object')
+    def test_caches(self, mock_import):
+        self.flags(use_neutron=True)
+        sgapi.DRIVER_CACHE = None
+        for _ in range(2):
+            self.assertIsNotNone(sgapi.get_openstack_security_group_driver())
+        mock_import.assert_called_once_with(sgapi.NEUTRON_DRIVER)