add get_by_metadata_key to AggregateList object

This change adds the get_by_metadata_key function to the AggregateList object
and the aggregate_get_by_metadata_key function to the DB API.

Previously, the only DB API function available for finding aggregates matching
a metadata key returned a dictionary of aggregated metadata. The
aggregate_get_by_metadata_key function returns all rows matching the specified
metadata key, and is called by the existing aggregate_host_get_by_metadata_key
DB API function.

The get_by_metadata_key function returns a list of Aggregate objects matching
the specified metadata key.

Related to blueprint compute-manager-objects-juno

Change-Id: If50c9f613dd192ab44577f26a81dd5b40e3a7af7

nova/db/api.py

@@ -1769,6 +1769,10 @@ def aggregate_host_get_by_metadata_key(context, key):
     return IMPL.aggregate_host_get_by_metadata_key(context, key)
 
 
+def aggregate_get_by_metadata_key(context, key):
+    return IMPL.aggregate_get_by_metadata_key(context, key)
+
+
 def aggregate_update(context, aggregate_id, values):
     """Update the attributes of an aggregates.
 

nova/db/sqlalchemy/api.py

@@ -5094,13 +5094,7 @@ def aggregate_metadata_get_by_metadata_key(context, aggregate_id, key):
 
 
 def aggregate_host_get_by_metadata_key(context, key):
-    query = model_query(context, models.Aggregate)
-    query = query.join("_metadata")
-    query = query.filter(models.AggregateMetadata.key == key)
-    query = query.options(contains_eager("_metadata"))
-    query = query.options(joinedload("_hosts"))
-    rows = query.all()
-
+    rows = aggregate_get_by_metadata_key(context, key)
     metadata = collections.defaultdict(set)
     for agg in rows:
         for agghost in agg._hosts:
@@ -5108,6 +5102,19 @@ def aggregate_host_get_by_metadata_key(context, key):
     return dict(metadata)
 
 
+def aggregate_get_by_metadata_key(context, key):
+    """Return rows that match metadata key.
+
+    :param key Matches metadata key.
+    """
+    query = model_query(context, models.Aggregate)
+    query = query.join("_metadata")
+    query = query.filter(models.AggregateMetadata.key == key)
+    query = query.options(contains_eager("_metadata"))
+    query = query.options(joinedload("_hosts"))
+    return query.all()
+
+
 def aggregate_update(context, aggregate_id, values):
     session = get_session()
 

nova/objects/aggregate.py

@@ -151,7 +151,8 @@ class AggregateList(base.ObjectListBase, base.NovaObject):
     # Version 1.0: Initial version
     # Version 1.1: Added key argument to get_by_host()
     #              Aggregate <= version 1.1
-    VERSION = '1.1'
+    # Version 1.2: Added get_by_metadata_key
+    VERSION = '1.2'
 
     fields = {
         'objects': fields.ListOfObjectsField('Aggregate'),
@@ -160,8 +161,21 @@ class AggregateList(base.ObjectListBase, base.NovaObject):
         '1.0': '1.1',
         '1.1': '1.1',
         # NOTE(danms): Aggregate was at 1.1 before we added this
+        '1.2': '1.1',
         }
 
+    @classmethod
+    def _filter_db_aggregates(cls, db_aggregates, hosts):
+        if not isinstance(hosts, set):
+            hosts = set(hosts)
+        filtered_aggregates = []
+        for db_aggregate in db_aggregates:
+            for host in db_aggregate['hosts']:
+                if host in hosts:
+                    filtered_aggregates.append(db_aggregate)
+                    break
+        return filtered_aggregates
+
     @base.remotable_classmethod
     def get_all(cls, context):
         db_aggregates = db.aggregate_get_all(context)
@@ -173,3 +187,11 @@ class AggregateList(base.ObjectListBase, base.NovaObject):
         db_aggregates = db.aggregate_get_by_host(context, host, key=key)
         return base.obj_make_list(context, cls(context), objects.Aggregate,
                                   db_aggregates)
+
+    @base.remotable_classmethod
+    def get_by_metadata_key(cls, context, key, hosts=None):
+        db_aggregates = db.aggregate_get_by_metadata_key(context, key=key)
+        if hosts:
+            db_aggregates = cls._filter_db_aggregates(db_aggregates, hosts)
+        return base.obj_make_list(context, cls(context), objects.Aggregate,
+                                  db_aggregates)

nova/tests/objects/test_aggregate.py

@@ -12,6 +12,8 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import mock
+
 from nova import db
 from nova import exception
 from nova.objects import aggregate
@@ -163,6 +165,29 @@ class _TestAggregateObject(object):
         self.assertEqual(1, len(aggs))
         self.compare_obj(aggs[0], fake_aggregate, subs=SUBS)
 
+    @mock.patch('nova.db.aggregate_get_by_metadata_key')
+    def test_get_by_metadata_key(self, get_by_metadata_key):
+        get_by_metadata_key.return_value = [fake_aggregate]
+        aggs = aggregate.AggregateList.get_by_metadata_key(
+            self.context, 'this')
+        self.assertEqual(1, len(aggs))
+        self.compare_obj(aggs[0], fake_aggregate, subs=SUBS)
+
+    @mock.patch('nova.db.aggregate_get_by_metadata_key')
+    def test_get_by_metadata_key_and_hosts_no_match(self, get_by_metadata_key):
+        get_by_metadata_key.return_value = [fake_aggregate]
+        aggs = aggregate.AggregateList.get_by_metadata_key(
+            self.context, 'this', hosts=['baz'])
+        self.assertEqual(0, len(aggs))
+
+    @mock.patch('nova.db.aggregate_get_by_metadata_key')
+    def test_get_by_metadata_key_and_hosts_match(self, get_by_metadata_key):
+        get_by_metadata_key.return_value = [fake_aggregate]
+        aggs = aggregate.AggregateList.get_by_metadata_key(
+            self.context, 'this', hosts=['foo', 'bar'])
+        self.assertEqual(1, len(aggs))
+        self.compare_obj(aggs[0], fake_aggregate, subs=SUBS)
+
 
 class TestAggregateObject(test_objects._LocalTest,
                           _TestAggregateObject):