[stable-only] Re-add autocommit support

There are a number of projects that have yet to migrate away from
autocommit. To prevent them blocking the release, temporarily re-add
autocommit support. We do this only on the stable branch since we are
going to need to address SQLAlchemy 2.x support in C.

This is effectively a partial revert of change
Ifaca67c07f008d8bc0febeecd3e200cc7ee7a4b0 but focused solely on
autocommit and with additional logic in tests to prevent us trying to
use autocommit with SQLAlchemy 2.x (where it's not supported).

Change-Id: Ib49ed6886470284e6486581290af4e0f2482e5c5
Signed-off-by: Stephen Finucane <stephenfin@redhat.com>

oslo_db/sqlalchemy/enginefacade.py

@@ -176,6 +176,7 @@ class _TransactionFactory:
         }
         self._maker_cfg = {
             'expire_on_commit': _Default(False),
+            '__autocommit': _Default(False),
         }
         self._transaction_ctx_cfg = {
             'rollback_reader_sessions': False,
@@ -446,6 +447,8 @@ class _TransactionFactory:
 
     def _maker_args_for_conf(self, conf):
         maker_args = self._args_for_conf(self._maker_cfg, conf)
+        if '__autocommit' in maker_args:
+            maker_args['autocommit'] = maker_args.pop('__autocommit')
         return maker_args
 
     def dispose_pool(self):
@@ -1214,6 +1217,10 @@ class LegacyEngineFacade(object):
     :param sqlite_fk: enable foreign keys in SQLite
     :type sqlite_fk: bool
 
+    :param autocommit: use autocommit mode for created Session instances
+                       (only supported with SQLAlchemy < 2.0)
+    :type autocommit: bool
+
     :param expire_on_commit: expire session objects on commit
     :type expire_on_commit: bool
 
@@ -1251,7 +1258,8 @@ class LegacyEngineFacade(object):
 
     """
     def __init__(self, sql_connection, slave_connection=None,
-                 sqlite_fk=False, expire_on_commit=False, _conf=None,
+                 sqlite_fk=False, autocommit=False,
+                 expire_on_commit=False, _conf=None,
                  _factory=None, **kwargs):
         warnings.warn(
             "EngineFacade is deprecated; please use "
@@ -1259,6 +1267,14 @@ class LegacyEngineFacade(object):
             warning.OsloDBDeprecationWarning,
             stacklevel=2)
 
+        if autocommit is True:
+            warnings.warn(
+                'autocommit support has been removed in SQLAlchemy 2.0 and '
+                'should not be relied on; please rework your code to remove '
+                'reliance on this feature',
+                warning.OsloDBDeprecationWarning,
+                stacklevel=2)
+
         if _factory:
             self._factory = _factory
         else:
@@ -1266,6 +1282,7 @@ class LegacyEngineFacade(object):
 
             self._factory.configure(
                 sqlite_fk=sqlite_fk,
+                __autocommit=autocommit,
                 expire_on_commit=expire_on_commit,
                 **kwargs
             )
@@ -1331,7 +1348,7 @@ class LegacyEngineFacade(object):
 
     @classmethod
     def from_config(cls, conf,
-                    sqlite_fk=False, expire_on_commit=False):
+                    sqlite_fk=False, autocommit=False, expire_on_commit=False):
         """Initialize EngineFacade using oslo.config config instance options.
 
         :param conf: oslo.config config instance
@@ -1340,6 +1357,10 @@ class LegacyEngineFacade(object):
         :param sqlite_fk: enable foreign keys in SQLite
         :type sqlite_fk: bool
 
+        :param autocommit: use autocommit mode for created Session instances
+                           (only supported with SQLAlchemy < 2.0)
+        :type autocommit: bool
+
         :param expire_on_commit: expire session objects on commit
         :type expire_on_commit: bool
 
@@ -1348,4 +1369,5 @@ class LegacyEngineFacade(object):
         return cls(
             None,
             sqlite_fk=sqlite_fk,
+            autocommit=autocommit,
             expire_on_commit=expire_on_commit, _conf=conf)

oslo_db/tests/sqlalchemy/test_enginefacade.py

@@ -361,10 +361,12 @@ class MockFacadeTest(test_base.BaseTestCase):
         maker_factories = mock.Mock(side_effect=get_maker)
 
         maker_factories(
+            autocommit=False,
             engine=engines.writer,
             expire_on_commit=False)
         if self.slave_uri:
             maker_factories(
+                autocommit=False,
                 engine=engines.async_reader,
                 expire_on_commit=False)
 
@@ -1385,6 +1387,19 @@ class PatchFactoryTest(test_base.BaseTestCase):
         self.assertEqual(38, engine_args["max_overflow"])
         self.assertNotIn("mysql_wsrep_sync_wait", engine_args)
 
+    def test_new_manager_deprecated_options(self):
+        normal_mgr = enginefacade.transaction_context()
+        normal_mgr.configure(
+            connection="sqlite://",
+            __autocommit=True,
+        )
+
+        normal_mgr._factory._start()
+        copied_mgr = normal_mgr.make_new_manager()
+
+        engine_args = copied_mgr._factory._maker_args_for_conf(None)
+        self.assertTrue(engine_args['autocommit'])
+
     def test_new_manager_from_options(self):
         """test enginefacade's defaults given a default structure from opts"""
 

oslo_db/tests/sqlalchemy/test_sqlalchemy.py

@@ -432,7 +432,9 @@ class EngineFacadeTestCase(test_base.BaseTestCase):
             logging_name=mock.ANY,
         )
         get_maker.assert_called_once_with(
-            engine=create_engine(), expire_on_commit=True,
+            engine=create_engine(),
+            autocommit=False,
+            expire_on_commit=True,
         )
 
     def test_slave_connection(self):

releasenotes/notes/readd-autocommit-b070ba5a3a57dcad.yaml

@@ -0,0 +1,7 @@
+---
+upgrade:
+  - |
+    The ability to create engine facades that used autocommit, which was
+    removed in 13.0.0, has been re-added temporarily to allow a longer
+    transition time for projects. It is still deprecated and requires
+    SQLAlchemy < 2.x. It will be removed again in a future release.