Actively unset reset agent in discard transaction

The assumptions in _discard_transaction from
916e1fea25afcd07fa1d1d2f72043b372cd02223 were too narrow,
assuming that if the given transaction were not our
"current" one, that this would not be the reset agent.  however
as the legacy behvaior is that even a "nested" transaction gets
set as "self._transaction", this did not accommodate for the nested
transaction being thrown away.   We will attempt to refine all of this
logic in #5327 for 1.4 /master assuming this is feasible for the
full suite of current use cases.

Fixes: #5326
Change-Id: I6787e82c9e50c23317f87d0d094122c6a6f066da
(cherry picked from commit 79de84b25e87bbb7fa94f0dd513b4abc76e05a7e)

diff --git a/doc/build/changelog/unreleased_13/5326.rst b/doc/build/changelog/unreleased_13/5326.rst
new file mode 100644 (file)
index 0000000..801ff4a
--- /dev/null
+++ b/doc/build/changelog/unreleased_13/5326.rst
@@ -0,0 +1,9 @@
+.. change::
+    :tags: bug, engine
+    :tickets: 5326
+
+    Further refinements to the fixes to the "reset" agent fixed in
+    :ticket:`5326`, which now emits a warning when it is not being correctly
+    invoked and corrects for the behavior.  Additional scenarios have been
+    identified and fixed where this warning was being emitted.
+

diff --git a/lib/sqlalchemy/engine/base.py b/lib/sqlalchemy/engine/base.py
index 3b4b4c2459cf364e185b51a9ba3d2a6219d77b85..4cf14b58d36e1bda606c390e7fe2788c0b4e692b 100644 (file)
--- a/lib/sqlalchemy/engine/base.py
+++ b/lib/sqlalchemy/engine/base.py
@@ -799,18 +799,12 @@ class Connection(Connectable):
         if trans is self.__transaction:
             if trans._parent is trans:
                 self.__transaction = None
-                if self._still_open_and_connection_is_valid:
-                    assert self.__connection._reset_agent is None
             else:
                 self.__transaction = trans._parent
 
-                # not doing this assertion for now, however this is how
-                # it would look:
-                # if self._still_open_and_connection_is_valid:
-                #    trans = self._transaction
-                #    while not trans._is_root:
-                #        trans = trans._parent
-                #    assert self.__connection._reset_agent is trans
+        if self._still_open_and_connection_is_valid:
+            if self.__connection._reset_agent is trans:
+                self.__connection._reset_agent = None
 
     def _rollback_to_savepoint_impl(self, name, context):
         assert not self.__branch_from

diff --git a/test/engine/test_transaction.py b/test/engine/test_transaction.py
index 6bab13109b97634fae0333a850a1acf4695a915a..970435e030f1fa6564ebaef6e4f5ff14744f367e 100644 (file)
--- a/test/engine/test_transaction.py
+++ b/test/engine/test_transaction.py
@@ -620,7 +620,7 @@ class ResetAgentTest(fixtures.TestBase):
             conn.close()
 
     @testing.requires.savepoints
-    def test_begin_nested_trans_close(self):
+    def test_begin_nested_trans_close_one(self):
         with testing.db.connect() as connection:
             t1 = connection.begin()
             assert connection.connection._reset_agent is t1
@@ -634,6 +634,20 @@ class ResetAgentTest(fixtures.TestBase):
             assert connection.connection._reset_agent is None
         assert not t1.is_active
 
+    @testing.requires.savepoints
+    def test_begin_nested_trans_close_two(self):
+        with testing.db.connect() as connection:
+            t1 = connection.begin()
+            assert connection.connection._reset_agent is t1
+            t2 = connection.begin_nested()
+            assert connection.connection._reset_agent is t1
+            assert connection._Connection__transaction is t2
+
+            assert connection.connection._reset_agent is t1
+            t1.close()
+            assert connection.connection._reset_agent is None
+        assert not t1.is_active
+
     @testing.requires.savepoints
     def test_begin_nested_trans_rollback(self):
         with testing.db.connect() as connection: