Merge "Make memcache client reusable across threads" into stable/kilo

2 files changed, 32 insertions, 5 deletions

diff --git a/keystone/common/cache/_memcache_pool.py b/keystone/common/cache/_memcache_pool.py
index b15332db0..bc559781a 100644
--- a/keystone/common/cache/_memcache_pool.py
+++ b/keystone/common/cache/_memcache_pool.py
@@ -35,11 +35,22 @@ from keystone.i18n import _
 
 LOG = log.getLogger(__name__)
 
-# This 'class' is taken from http://stackoverflow.com/a/22520633/238308
-# Don't inherit client from threading.local so that we can reuse clients in
-# different threads
-_MemcacheClient = type('_MemcacheClient', (object,),
-                       dict(memcache.Client.__dict__))
+
+class _MemcacheClient(memcache.Client):
+    """Thread global memcache client
+
+    As client is inherited from threading.local we have to restore object
+    methods overloaded by threading.local so we can reuse clients in
+    different threads
+    """
+    __delattr__ = object.__delattr__
+    __getattribute__ = object.__getattribute__
+    __new__ = object.__new__
+    __setattr__ = object.__setattr__
+
+    def __del__(self):
+        pass
+
 
 _PoolItem = collections.namedtuple('_PoolItem', ['ttl', 'connection'])
 
diff --git a/keystone/tests/unit/common/test_connection_pool.py b/keystone/tests/unit/common/test_connection_pool.py
index 74d0420ce..3813e0339 100644
--- a/keystone/tests/unit/common/test_connection_pool.py
+++ b/keystone/tests/unit/common/test_connection_pool.py
@@ -10,9 +10,11 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
+import threading
 import time
 
 import mock
+import six
 from six.moves import queue
 import testtools
 from testtools import matchers
@@ -117,3 +119,17 @@ class TestConnectionPool(core.TestCase):
         # after it is available.
         connection_pool.put_nowait(conn)
         _acquire_connection()
+
+
+class TestMemcacheClientOverrides(core.BaseTestCase):
+
+    def test_client_stripped_of_threading_local(self):
+        """threading.local overrides are restored for _MemcacheClient"""
+        client_class = _memcache_pool._MemcacheClient
+        # get the genuine thread._local from MRO
+        thread_local = client_class.__mro__[2]
+        self.assertTrue(thread_local is threading.local)
+        for field in six.iterkeys(thread_local.__dict__):
+            if field not in ('__dict__', '__weakref__'):
+                self.assertNotEqual(id(getattr(thread_local, field, None)),
+                                    id(getattr(client_class, field, None)))