feat(sqlalchemy-spanner): wire timeout execution option through to DBAPI Connection.timeout

Add timeout handling to SpannerExecutionContext.pre_exec() and
reset_connection() so that users can set a per-statement gRPC deadline
via execution_options(timeout=N).

Depends on googleapis/python-spanner#1534 for the DBAPI Connection.timeout property.

Fixes #16467

Author: waiho-gumloop

packages/sqlalchemy-spanner/google/cloud/sqlalchemy_spanner/sqlalchemy_spanner.py

@@ -72,6 +72,7 @@ def reset_connection(dbapi_conn, connection_record, reset_state=None):
 
         dbapi_conn.staleness = None
         dbapi_conn.read_only = False
+        dbapi_conn.timeout = None
 
 
 # register a method to get a single value of a JSON object
@@ -217,6 +218,10 @@ def pre_exec(self):
         if request_tag:
             self.cursor.request_tag = request_tag
 
+        timeout = self.execution_options.get("timeout")
+        if timeout is not None:
+            self._dbapi_connection.connection.timeout = timeout
+
         ignore_transaction_warnings = self.execution_options.get(
             "ignore_transaction_warnings"
         )

packages/sqlalchemy-spanner/tests/unit/test_sqlalchemy_spanner.py

@@ -0,0 +1,102 @@
+# Copyright 2024 Google LLC All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Unit tests for SpannerExecutionContext and reset_connection."""
+
+import unittest
+from unittest import mock
+
+from google.cloud import spanner_dbapi
+from google.cloud.sqlalchemy_spanner.sqlalchemy_spanner import reset_connection
+
+
+class ResetConnectionTest(unittest.TestCase):
+    def test_reset_connection_clears_timeout(self):
+        dbapi_conn = mock.MagicMock(spec=spanner_dbapi.Connection)
+        dbapi_conn.inside_transaction = False
+
+        reset_connection(dbapi_conn, connection_record=None)
+
+        assert dbapi_conn.staleness is None
+        assert dbapi_conn.read_only is False
+        assert dbapi_conn.timeout is None
+
+    def test_reset_connection_with_wrapper(self):
+        inner_conn = mock.MagicMock(spec=spanner_dbapi.Connection)
+        inner_conn.inside_transaction = False
+        wrapper = mock.MagicMock()
+        wrapper.connection = inner_conn
+
+        reset_connection(wrapper, connection_record=None)
+
+        assert inner_conn.staleness is None
+        assert inner_conn.read_only is False
+        assert inner_conn.timeout is None
+
+
+class SpannerExecutionContextPreExecTest(unittest.TestCase):
+    def _make_context(self, execution_options):
+        from google.cloud.sqlalchemy_spanner.sqlalchemy_spanner import (
+            SpannerExecutionContext,
+        )
+
+        ctx = SpannerExecutionContext.__new__(SpannerExecutionContext)
+        ctx.execution_options = execution_options
+
+        dbapi_conn = mock.MagicMock()
+        dbapi_conn.connection = mock.MagicMock()
+        ctx._dbapi_connection = dbapi_conn
+        ctx.cursor = mock.MagicMock()
+
+        return ctx
+
+    @mock.patch(
+        "google.cloud.sqlalchemy_spanner.sqlalchemy_spanner.DefaultExecutionContext.pre_exec"
+    )
+    def test_pre_exec_sets_timeout(self, mock_super_pre_exec):
+        ctx = self._make_context({"timeout": 60})
+        ctx.pre_exec()
+
+        assert ctx._dbapi_connection.connection.timeout == 60
+
+    @mock.patch(
+        "google.cloud.sqlalchemy_spanner.sqlalchemy_spanner.DefaultExecutionContext.pre_exec"
+    )
+    def test_pre_exec_no_timeout_leaves_connection_unchanged(self, mock_super_pre_exec):
+        ctx = self._make_context({})
+
+        conn = ctx._dbapi_connection.connection
+        conn._mock_children.clear()
+
+        ctx.pre_exec()
+
+        set_attrs = {
+            name
+            for name, _ in conn._mock_children.items()
+            if not name.startswith("_")
+        }
+        assert "timeout" not in set_attrs
+
+    @mock.patch(
+        "google.cloud.sqlalchemy_spanner.sqlalchemy_spanner.DefaultExecutionContext.pre_exec"
+    )
+    def test_pre_exec_timeout_with_other_options(self, mock_super_pre_exec):
+        ctx = self._make_context(
+            {"timeout": 30, "read_only": True, "request_priority": 2}
+        )
+        ctx.pre_exec()
+
+        assert ctx._dbapi_connection.connection.timeout == 30
+        assert ctx._dbapi_connection.connection.read_only is True
+        assert ctx._dbapi_connection.connection.request_priority == 2