Fix SQLAlchemy 1.4 support

* Fix list_metrics in amqp1d not properly
  validating list/set is not empty.

* Dont set database or drivername on  the
  new immutable SQLAlchemy URL object.

* Validate values is not None before using.

(cherry picked from commit 5ed9cc9)

gnocchi/amqp1d.py

@@ -64,14 +64,17 @@ def _flush(self):
         for host_id, measures_by_names in six.iteritems(self._measures):
             resource = resources[host_id]
 
-            names = set(measures_by_names.keys())
+            mbn_keys = measures_by_names.keys()
+            names = (set(mbn_keys) if len(mbn_keys)
+                     else set())
+
             for name in names:
                 if name not in archive_policies:
                     archive_policies[name] = (
                         self.indexer.get_archive_policy_for_metric(name))
             known_metrics = self.indexer.list_metrics(attribute_filter={
                 "and": [{"=": {"resource_id": resource.id}},
-                        {"in": {"name": names}}]
+                        {"in": {"name": list(names)}}]
             })
             known_names = set((m.name for m in known_metrics))
             already_exists_names = []

gnocchi/indexer/sqlalchemy.py

@@ -260,27 +260,46 @@ def _safe_execute(self, connection, works):
 class SQLAlchemyIndexer(indexer.IndexerDriver):
     _RESOURCE_TYPE_MANAGER = ResourceClassMapper()
 
+    @staticmethod
+    def _set_url_database(url, database):
+        if hasattr(url, "set"):
+            return url.set(database=database)
+        else:
+            url.database = database
+            return url
+
+    @staticmethod
+    def _set_url_drivername(url, drivername):
+        if hasattr(url, "set"):
+            return url.set(drivername=drivername)
+        else:
+            url.drivername = drivername
+            return url
+
     @classmethod
     def _create_new_database(cls, url):
         """Used by testing to create a new database."""
         purl = sqlalchemy_url.make_url(
             cls.dress_url(
                 url))
-        purl.database = purl.database + str(uuid.uuid4()).replace('-', '')
+        new_database = purl.database + str(uuid.uuid4()).replace('-', '')
+        purl = cls._set_url_database(purl, new_database)
         new_url = str(purl)
         sqlalchemy_utils.create_database(new_url)
         return new_url
 
-    @staticmethod
-    def dress_url(url):
+    @classmethod
+    def dress_url(cls, url):
         # If no explicit driver has been set, we default to pymysql
         if url.startswith("mysql://"):
             url = sqlalchemy_url.make_url(url)
-            url.drivername = "mysql+pymysql"
+            new_drivername = "mysql+pymysql"
+            url = cls._set_url_drivername(url, new_drivername)
             return str(url)
         if url.startswith("postgresql://"):
             url = sqlalchemy_url.make_url(url)
-            url.drivername = "postgresql+psycopg2"
+            new_drivername = "postgresql+psycopg2"
+            url = cls._set_url_drivername(url, new_drivername)
             return str(url)
         return url
 
@@ -951,8 +970,6 @@ def delete_resources(self, resource_type='generic',
             target_cls = self._resource_type_to_mappers(
                 session, resource_type)["resource"]
 
-            q = session.query(target_cls.id)
-
             engine = session.connection()
             try:
                 f = QueryTransformer.build_filter(engine.dialect.name,
@@ -964,12 +981,16 @@ def delete_resources(self, resource_type='generic',
                 raise indexer.ResourceAttributeError(resource_type,
                                                      e.attribute)
 
-            q = q.filter(f)
+            q1 = session.query(target_cls.id)
+            q1 = q1.filter(f)
 
             session.query(Metric).filter(
-                Metric.resource_id.in_(q)
+                Metric.resource_id.in_(q1)
             ).update({"status": "delete"},
                      synchronize_session=False)
+
+            q = session.query(target_cls)
+            q = q.filter(f)
             return q.delete(synchronize_session=False)
 
     @retry_on_deadlock

gnocchi/indexer/sqlalchemy_base.py

@@ -51,13 +51,17 @@ def process_bind_param(self, value, dialect):
     def process_result_value(self, value, dialect):
         values = super(ArchivePolicyDefinitionType,
                        self).process_result_value(value, dialect)
+        if values is None:
+            return []
         return [archive_policy.ArchivePolicyItem(**v) for v in values]
 
 
 class SetType(sqlalchemy_utils.JSONType):
     def process_result_value(self, value, dialect):
-        return set(super(SetType,
-                         self).process_result_value(value, dialect))
+        values = super(SetType, self).process_result_value(value, dialect)
+        if values is None:
+            return set()
+        return set(values)
 
 
 class ArchivePolicy(Base, GnocchiBase, archive_policy.ArchivePolicy):