Make Aggregate.get_by_uuid use the API db.

Make Aggregate.get_by_uuid access the api db first only accessing the
cell db if not found.

blueprint cells-aggregate-api-db

Change-Id: Iaf89c041b6b6990f65e90c5086b13edea1af26f1

nova/objects/aggregate.py

@@ -47,6 +47,21 @@ def _aggregate_get_from_db(context, aggregate_id):
     return aggregate
 
 
+@db_api.api_context_manager.reader
+def _aggregate_get_from_db_by_uuid(context, aggregate_uuid):
+    query = context.session.query(api_models.Aggregate).\
+            options(joinedload('_hosts')).\
+            options(joinedload('_metadata'))
+    query = query.filter(api_models.Aggregate.uuid == aggregate_uuid)
+
+    aggregate = query.first()
+
+    if not aggregate:
+        raise exception.AggregateNotFound(aggregate_id=aggregate_uuid)
+
+    return aggregate
+
+
 @base.NovaObjectRegistry.register
 class Aggregate(base.NovaPersistentObject, base.NovaObject):
     # Version 1.0: Initial version
@@ -121,7 +136,11 @@ class Aggregate(base.NovaPersistentObject, base.NovaObject):
 
     @base.remotable_classmethod
     def get_by_uuid(cls, context, aggregate_uuid):
-        db_aggregate = db.aggregate_get_by_uuid(context, aggregate_uuid)
+        try:
+            db_aggregate = _aggregate_get_from_db_by_uuid(context,
+                                                          aggregate_uuid)
+        except exception.AggregateNotFound:
+            db_aggregate = db.aggregate_get_by_uuid(context, aggregate_uuid)
         return cls._from_db_object(context, cls(), db_aggregate)
 
     @base.remotable

nova/tests/unit/objects/test_aggregate.py

@@ -98,6 +98,14 @@ class _TestAggregateObject(object):
         self.assertEqual(fake_db_aggregate_hosts, expected.hosts)
         self.assertEqual(fake_db_aggregate_metadata, expected['metadetails'])
 
+    def test_aggregate_get_from_db_by_uuid(self):
+        result = _create_aggregate_with_hosts(self.context)
+        expected = aggregate._aggregate_get_from_db_by_uuid(
+                self.context, result['uuid'])
+        self.assertEqual(result.uuid, expected.uuid)
+        self.assertEqual(fake_db_aggregate_hosts, expected.hosts)
+        self.assertEqual(fake_db_aggregate_metadata, expected['metadetails'])
+
     def test_aggregate_get_from_db_raise_not_found(self):
         aggregate_id = 5
         self.assertRaises(exception.AggregateNotFound,
@@ -192,14 +200,27 @@ class _TestAggregateObject(object):
             self.assertEqual(uuid, obj.uuid)
             mock_save.assert_called_once_with()
 
+    @mock.patch('nova.objects.aggregate._aggregate_get_from_db_by_uuid')
     @mock.patch('nova.db.aggregate_get_by_uuid')
-    def test_get_by_uuid(self, get_by_uuid):
+    def test_get_by_uuid(self, get_by_uuid, get_by_uuid_api):
+        get_by_uuid_api.side_effect = exception.AggregateNotFound(
+                                                            aggregate_id=123)
         get_by_uuid.return_value = fake_aggregate
         agg = aggregate.Aggregate.get_by_uuid(self.context,
                                               uuidsentinel.fake_aggregate)
         self.assertEqual(uuidsentinel.fake_aggregate, agg.uuid)
         self.assertEqual(fake_aggregate['id'], agg.id)
 
+    @mock.patch('nova.objects.aggregate._aggregate_get_from_db_by_uuid')
+    @mock.patch('nova.db.aggregate_get_by_uuid')
+    def test_get_by_uuid_from_api(self, get_by_uuid, get_by_uuid_api):
+        get_by_uuid_api.return_value = fake_aggregate
+        agg = aggregate.Aggregate.get_by_uuid(self.context,
+                                              uuidsentinel.fake_aggregate)
+        self.assertEqual(uuidsentinel.fake_aggregate, agg.uuid)
+        self.assertEqual(fake_aggregate['id'], agg.id)
+        self.assertFalse(get_by_uuid.called)
+
     def test_create(self):
         self.mox.StubOutWithMock(db, 'aggregate_create')
         db.aggregate_create(self.context, {'name': 'foo',