Added method get_legacy_facade() to the _TransactionContextManager

This public method was added to be able to create several
legacy facades from several transaction context managers.

It could be used in Nova where we have two DBs.
There we need some legal way to create two legacy facades
because right now in Nova we create facades by using
private field _factory. It is not quite right.

Change-Id: I96b3dbcbc5a05ac025c247ae6d8abfc988d0295e

2 files changed, 24 insertions, 1 deletions

diff --git a/oslo_db/sqlalchemy/enginefacade.py b/oslo_db/sqlalchemy/enginefacade.py
index 0985ea8..111f033 100644
--- a/oslo_db/sqlalchemy/enginefacade.py
+++ b/oslo_db/sqlalchemy/enginefacade.py
@@ -622,6 +622,17 @@ class _TransactionContextManager(object):
         """
         self._factory.configure(**kw)
 
+    def get_legacy_facade(self):
+        """Return a :class:`.LegacyEngineFacade` for factory from this context.
+
+        This facade will make use of the same engine and sessionmaker
+        as this factory, however will not share the same transaction context;
+        the legacy facade continues to work the old way of returning
+        a new Session each time get_session() is called.
+        """
+
+        return self._factory.get_legacy_facade()
+
     @property
     def replace(self):
         """Modifier to replace the global transaction factory with this one."""
@@ -827,7 +838,7 @@ def get_legacy_facade():
     a new Session each time get_session() is called.
 
     """
-    return _context_manager._factory.get_legacy_facade()
+    return _context_manager.get_legacy_facade()
 
 
 reader = _context_manager.reader
diff --git a/oslo_db/tests/sqlalchemy/test_enginefacade.py b/oslo_db/tests/sqlalchemy/test_enginefacade.py
index 4a2517e..62e3fa9 100644
--- a/oslo_db/tests/sqlalchemy/test_enginefacade.py
+++ b/oslo_db/tests/sqlalchemy/test_enginefacade.py
@@ -985,6 +985,18 @@ class LegacyIntegrationtest(test_base.DbTestCase):
             enginefacade._context_manager._factory._writer_maker
         )
 
+    def test_legacy_facades_from_different_context_managers(self):
+        transaction_context1 = enginefacade.transaction_context()
+        transaction_context2 = enginefacade.transaction_context()
+
+        transaction_context1.configure(connection='sqlite:///?conn1')
+        transaction_context2.configure(connection='sqlite:///?conn2')
+
+        legacy1 = transaction_context1.get_legacy_facade()
+        legacy2 = transaction_context2.get_legacy_facade()
+
+        self.assertNotEqual(legacy1, legacy2)
+
 
 class ThreadingTest(test_base.DbTestCase):
     """Test copy/pickle on new threads using real connections and sessions."""