Merge "Add legacy get_sessionmaker() method"

oslo_db/sqlalchemy/enginefacade.py

@@ -964,6 +964,18 @@ class LegacyEngineFacade(object):
         else:
             return self._factory._writer_maker(**kwargs)
 
+    def get_sessionmaker(self, use_slave=False):
+        """Get the sessionmaker instance used to create a Session.
+
+        This can be called for those cases where the sessionmaker() is to
+        be temporarily injected with some state such as a specific connection.
+
+        """
+        if use_slave:
+            return self._factory._reader_maker
+        else:
+            return self._factory._writer_maker
+
     @classmethod
     def from_config(cls, conf,
                     sqlite_fk=False, autocommit=True, expire_on_commit=False):

oslo_db/tests/sqlalchemy/test_enginefacade.py

@@ -947,6 +947,13 @@ class LegacyIntegrationtest(test_base.DbTestCase):
             enginefacade.get_legacy_facade() is legacy_facade
         )
 
+    def test_get_sessionmaker(self):
+        legacy_facade = enginefacade.get_legacy_facade()
+        self.assertTrue(
+            legacy_facade.get_sessionmaker() is
+            enginefacade._context_manager._factory._writer_maker
+        )
+
 
 class ThreadingTest(test_base.DbTestCase):
     """Test copying on new threads using real connections and sessions."""