Add handling for savepoint not found

CHANGES.rst

@@ -1,6 +1,17 @@
 Changelog
 =========
 
+2.6.0
+-----
+
+Features
+~~~~~~~~
+
+- An error during a rollback to a savepoint is ignored, if the transaction was already
+  rolled back by SAP HANA.
+  Based on this feature, ``sqlalchemy_hana.errors`` will no longer extract an inner error
+  if a savepoint was not found.
+
 2.5.0
 -----
 

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "sqlalchemy-hana"
-version = "2.5.0"
+version = "2.6.0"
 description = "SQLAlchemy dialect for SAP HANA"
 keywords = ["sqlalchemy", "sap", "hana"]
 requires-python = "~=3.8"

sqlalchemy_hana/dialect.py

@@ -3,6 +3,7 @@
 from __future__ import annotations
 
 import contextlib
+import sys
 from contextlib import closing
 from types import ModuleType
 from typing import TYPE_CHECKING, Any, Callable, cast
@@ -1215,3 +1216,15 @@ def get_table_comment(
         )
 
         return {"text": result.scalar()}
+
+    def do_rollback_to_savepoint(self, connection: Connection, name: str) -> None:
+        err = sys.exc_info()
+        if (
+            isinstance(err[1], exc.DBAPIError)
+            and isinstance(err[1].orig, hdbcli.dbapi.Error)
+            and err[1].orig.errortext.startswith("transaction rolled back")
+        ):
+            # the transaction was already rolled back by SAP HANA, therefore the savepoint
+            # does no longer exist
+            return
+        super().do_rollback_to_savepoint(connection, name)

sqlalchemy_hana/errors.py

@@ -96,30 +96,11 @@ def convert_dbapi_error(dbapi_error: DBAPIError) -> DBAPIError:
     If it does not contain a hdbcli error, the original exception is returned.
 
     Else the error code and error text are further checked.
-
-    In addition, an edge case is handled where SQLAlchemy creates a savepoint and the same
-    transaction later fails leading to an automatic rollback by HANA.
-    However, SQLAlchemy still tries to roll back the savepoint, which fails because the savepoint
-    is no longer valid.
-    In this case, the cause of the exception is used for further processing
     """
     error = dbapi_error.orig
     if not isinstance(error, HdbcliError):
         return dbapi_error
 
-    # extract hidden inner exceptions
-    # TxSavepoint not found should normally only happen if a transaction was rolled back by HANA,
-    # but SQLAlchemy also tries to perform a savepoint rollback, which fails due to the transaction
-    # rollback. In this case, we need to check the inner exception (__context__)
-    if (
-        error.__context__
-        and isinstance(error.__context__, HdbcliError)
-        and error.errorcode == 128
-        and "TxSavepoint not found" in error.errortext
-    ):
-        error = error.__context__
-        dbapi_error.orig = error
-
     if error.errorcode in [-10807, -10709]:  # sqldbc error codes for connection errors
         return ClientConnectionError.from_dbapi_error(dbapi_error)
     if error.errorcode == 613:

test/test_dialect.py

@@ -2,13 +2,16 @@
 
 from __future__ import annotations
 
+import sys
+from unittest import mock
 from unittest.mock import Mock
 
 import pytest
 from hdbcli.dbapi import Error
 from sqlalchemy import create_engine
+from sqlalchemy.engine.default import DefaultDialect
 from sqlalchemy.engine.url import make_url
-from sqlalchemy.exc import ArgumentError
+from sqlalchemy.exc import ArgumentError, DBAPIError
 from sqlalchemy.testing import assert_raises_message, config, eq_
 from sqlalchemy.testing.engines import testing_engine
 from sqlalchemy.testing.fixtures import TestBase
@@ -176,3 +179,40 @@ def test_with_isolation_level_in_create_engine(self) -> None:
             NON_DEFAULT_ISOLATION_LEVEL,
         )
         conn.close()
+
+    def test_do_rollback_to_savepoint_no_error(self) -> None:
+        dialect = config.db.dialect
+        connection = Mock()
+
+        with mock.patch.object(
+            DefaultDialect, "do_rollback_to_savepoint"
+        ) as super_rollback:
+            dialect.do_rollback_to_savepoint(connection, "savepoint")
+            super_rollback.assert_called_once_with(connection, "savepoint")
+
+    def test_do_rollback_to_savepoint_unrelated_error(self) -> None:
+        dialect = config.db.dialect
+        connection = Mock()
+
+        with mock.patch.object(
+            sys, "exc_info", return_value=(ValueError, ValueError(), Mock())
+        ), mock.patch.object(
+            DefaultDialect, "do_rollback_to_savepoint"
+        ) as super_rollback:
+            dialect.do_rollback_to_savepoint(connection, "savepoint")
+            super_rollback.assert_called_once_with(connection, "savepoint")
+
+    def test_do_rollback_to_savepoint_ignores_error(self) -> None:
+        dialect = config.db.dialect
+        connection = Mock()
+
+        error = Error(133, "transaction rolled back: deadlock")
+        dbapi_error = DBAPIError(None, None, error)
+
+        with mock.patch.object(
+            sys, "exc_info", return_value=(DBAPIError, dbapi_error, Mock())
+        ), mock.patch.object(
+            DefaultDialect, "do_rollback_to_savepoint"
+        ) as super_rollback:
+            dialect.do_rollback_to_savepoint(connection, "savepoint")
+            super_rollback.assert_not_called()

test/test_errors.py

@@ -27,13 +27,6 @@
 
 
 class TestConvertDBAPIError(TestBase):
-    def test_convert_dbapi_error_txsavepoint_not_found(self) -> None:
-        error = HdbcliError(128, "TxSavepoint not found")
-        error.__context__ = HdbcliError(133, "some deadlock")
-        dbapi_error = DBAPIError(None, None, error)
-
-        assert isinstance(convert_dbapi_error(dbapi_error), DeadlockError)
-
     @pytest.mark.parametrize(
         "errorcode,errortext,expected_exception",
         [