CI: test under py311

Jammy only offers a py311 RC, so include the __slots__ hack to avoid
the segfault from https://github.com/python/cpython/issues/99886.

Fix up a test to work with the slotted connection.

Change-Id: I0e928bcb3810e391297300f4949024db3cf87d05

.zuul.yaml

@@ -136,6 +136,22 @@
       python_version: '3.10'
     post-run: tools/playbooks/common/cover-post.yaml
 
+- job:
+    name: swift-tox-py311
+    parent: swift-tox-base
+    nodeset: ubuntu-jammy
+    description: |
+      Run unit-tests for swift under cPython version 3.11.
+
+      Uses tox with the ``py311`` environment.
+      It sets TMPDIR to an XFS mount point created via
+      tools/test-setup.sh.
+    vars:
+      tox_envlist: py311
+      bindep_profile: test py311
+      python_version: '3.11'
+    post-run: tools/playbooks/common/cover-post.yaml
+
 - job:
     name: swift-tox-func-py27
     parent: swift-tox-base
@@ -700,6 +716,8 @@
             irrelevant-files: *unittest-irrelevant-files
         - swift-tox-py310:
             irrelevant-files: *unittest-irrelevant-files
+        - swift-tox-py311:
+            irrelevant-files: *unittest-irrelevant-files
 
         # Functional tests
         - swift-tox-func-py27:
@@ -788,6 +806,7 @@
         - swift-tox-py36
         - swift-tox-py39
         - swift-tox-py310
+        - swift-tox-py311
         - swift-tox-func-py27
         - swift-tox-func-encryption-py27
         - swift-tox-func-ec-py27

swift/common/db.py

@@ -129,6 +129,9 @@ class DatabaseAlreadyExists(sqlite3.DatabaseError):
 
 class GreenDBConnection(sqlite3.Connection):
     """SQLite DB Connection handler that plays well with eventlet."""
+    # slots are needed for python 3.11.0 (there's an issue fixed in 3.11.1,
+    # see https://github.com/python/cpython/issues/99886)
+    __slots__ = ('timeout', 'db_file')
 
     def __init__(self, database, timeout=None, *args, **kwargs):
         if timeout is None:
@@ -157,6 +160,9 @@ class GreenDBConnection(sqlite3.Connection):
 
 class GreenDBCursor(sqlite3.Cursor):
     """SQLite Cursor handler that plays well with eventlet."""
+    # slots are needed for python 3.11.0 (there's an issue fixed in 3.11.1,
+    # see https://github.com/python/cpython/issues/99886)
+    __slots__ = ('timeout', 'db_file')
 
     def __init__(self, *args, **kwargs):
         self.timeout = args[0].timeout

test/unit/account/test_backend.py

@@ -1521,23 +1521,37 @@ class TestAccountBrokerBeforeSPI(TestAccountBroker):
         real_get = broker.get
         called = []
 
+        class ExpectedError(Exception):
+            '''Expected error to be raised during the test'''
+
         @contextmanager
         def mock_get():
             with real_get() as conn:
 
-                def mock_executescript(script):
-                    if called:
-                        raise Exception('kaboom!')
-                    called.append(script)
+                class MockConn(object):
+                    def __init__(self, real_conn):
+                        self.real_conn = real_conn
 
-                conn.executescript = mock_executescript
-                yield conn
+                    @property
+                    def cursor(self):
+                        return self.real_conn.cursor
+
+                    @property
+                    def execute(self):
+                        return self.real_conn.execute
+
+                    def executescript(self, script):
+                        if called:
+                            raise ExpectedError('kaboom!')
+                        called.append(script)
+
+                yield MockConn(conn)
 
         broker.get = mock_get
 
         try:
             broker._commit_puts()
-        except Exception:
+        except ExpectedError:
             pass
         else:
             self.fail('mock exception was not raised')