Merge "Make the CellDatabases fixture work with fasteners >= 0.15"

nova/tests/fixtures/nova.py

@@ -17,6 +17,7 @@
 """Fixtures for Nova tests."""
 
 import collections
+import contextlib
 from contextlib import contextmanager
 import functools
 import logging as std_logging
@@ -406,7 +407,24 @@ class CellDatabases(fixtures.Fixture):
         # to point to a cell, we need to take an exclusive lock to
         # prevent any other calls to get_context_manager() until we
         # reset to the default.
-        self._cell_lock = lockutils.ReaderWriterLock()
+        # NOTE(melwitt): As of fasteners >= 0.15, the workaround code to use
+        # eventlet.getcurrent if eventlet patching is detected has been removed
+        # and threading.current_thread is being used instead. Although we are
+        # running in a greenlet in our test environment, we are not running in
+        # a greenlet of type GreenThread. A GreenThread is created by calling
+        # eventlet.spawn and spawn is not used to run our tests. At the time of
+        # this writing, the eventlet patched threading.current_thread method
+        # falls back to the original unpatched current_thread method if it is
+        # not called from a GreenThead [1] and that breaks our tests involving
+        # this fixture.
+        # We can work around this by patching threading.current_thread with
+        # eventlet.getcurrent during creation of the lock object.
+        # [1] https://github.com/eventlet/eventlet/blob/v0.32.0/eventlet/green/threading.py#L128  # noqa
+        eventlet_patched = eventlet.patcher.is_monkey_patched('thread')
+        with (contextlib.ExitStack() if not eventlet_patched else
+              fixtures.MonkeyPatch('threading.current_thread',
+                                   eventlet.getcurrent)):
+            self._cell_lock = lockutils.ReaderWriterLock()
 
     def _cache_schema(self, connection_str):
         # NOTE(melwitt): See the regular Database fixture for why