Add InstanceGroupList.get_counts()

This adds a method for getting counts of server groups in the database
for checking quota.

Part of blueprint cells-count-resources-to-check-quota-in-api

Change-Id: I9eadf93b432630607069cdf8ec1915920e32b905

nova/objects/instance_group.py

@@ -475,7 +475,8 @@ class InstanceGroupList(base.ObjectListBase, base.NovaObject):
     # Version 1.5: InstanceGroup <= version 1.8
     # Version 1.6: InstanceGroup <= version 1.9
     # Version 1.7: InstanceGroup <= version 1.10
-    VERSION = '1.7'
+    # Version 1.8: Added get_counts() for quotas
+    VERSION = '1.8'
 
     fields = {
         'objects': fields.ListOfObjectsField('InstanceGroup'),
@@ -496,6 +497,18 @@ class InstanceGroupList(base.ObjectListBase, base.NovaObject):
         return base.obj_make_list(context, cls(context), objects.InstanceGroup,
                                   main_db_groups)
 
+    @staticmethod
+    @db_api.api_context_manager.reader
+    def _get_counts_from_db(context, project_id, user_id=None):
+        query = context.session.query(api_models.InstanceGroup.id).\
+                filter_by(project_id=project_id)
+        counts = {}
+        counts['project'] = {'server_groups': query.count()}
+        if user_id:
+            query = query.filter_by(user_id=user_id)
+            counts['user'] = {'server_groups': query.count()}
+        return counts
+
     @base.remotable_classmethod
     def get_by_project_id(cls, context, project_id):
         api_db_groups = cls._get_from_db(context, project_id=project_id)
@@ -511,6 +524,21 @@ class InstanceGroupList(base.ObjectListBase, base.NovaObject):
         return base.obj_make_list(context, cls(context), objects.InstanceGroup,
                                   api_db_groups + main_db_groups)
 
+    @base.remotable_classmethod
+    def get_counts(cls, context, project_id, user_id=None):
+        """Get the counts of InstanceGroup objects in the database.
+
+        :param context: The request context for database access
+        :param project_id: The project_id to count across
+        :param user_id: The user_id to count across
+        :returns: A dict containing the project-scoped counts and user-scoped
+                  counts if user_id is specified. For example:
+
+                    {'project': {'server_groups': <count across project>},
+                     'user': {'server_groups': <count across user>}}
+        """
+        return cls._get_counts_from_db(context, project_id, user_id=user_id)
+
 
 @db_api.pick_context_manager_reader
 def _get_main_instance_groups(context, limit):

nova/tests/functional/db/test_instance_group.py

@@ -185,6 +185,26 @@ class InstanceGroupObjectTestCase(test.TestCase):
         self.assertTrue(base.obj_equal_prims(create_group, get_groups[0]))
         ovo_fixture.compare_obj(self, get_groups[1], db_group)
 
+    def test_get_counts(self):
+        # _api_group() creates a group with project_id and user_id from
+        # self.context by default
+        self._api_group()
+        self._api_group(project_id='foo')
+        self._api_group(user_id='bar')
+
+        # Count only across a project
+        counts = objects.InstanceGroupList.get_counts(self.context, 'foo')
+        self.assertEqual(1, counts['project']['server_groups'])
+        self.assertNotIn('user', counts)
+
+        # Count across a project and a user
+        counts = objects.InstanceGroupList.get_counts(
+            self.context, self.context.project_id,
+            user_id=self.context.user_id)
+
+        self.assertEqual(2, counts['project']['server_groups'])
+        self.assertEqual(1, counts['user']['server_groups'])
+
     def test_migrate_instance_groups(self):
         self._api_group(name='apigroup')
         orig_main_models = []

nova/tests/unit/objects/test_objects.py

@@ -1110,7 +1110,7 @@ object_data = {
     'InstanceFault': '1.2-7ef01f16f1084ad1304a513d6d410a38',
     'InstanceFaultList': '1.2-6bb72de2872fe49ded5eb937a93f2451',
     'InstanceGroup': '1.10-1a0c8c7447dc7ecb9da53849430c4a5f',
-    'InstanceGroupList': '1.7-be18078220513316abd0ae1b2d916873',
+    'InstanceGroupList': '1.8-90f8f1a445552bb3bbc9fa1ae7da27d4',
     'InstanceInfoCache': '1.5-cd8b96fefe0fc8d4d337243ba0bf0e1e',
     'InstanceList': '2.2-ff71772c7bf6d72f6ef6eee0199fb1c9',
     'InstanceMapping': '1.0-65de80c491f54d19374703c0753c4d47',