Fix py34 gate job

Add a configuration wrapper to avoid reentrant call to __getattr__()
in copy.copy(conf) on Python 3.x which is causing Zaqar's py34 gate job
failure randomly. The code is copied from Cinder, see the similar fix
in Cinder: https://review.openstack.org/#/c/280241/

Co-Authored-By: wangxiyuan<wangxiyuan@huawei.com>
Co-Authored-By: Wang Hao<wanghao749@huawei.com>

Change-Id: I627b96f00e5b05993b8f4f586ea216214d5f1a5f

zaqar/storage/configuration.py

@@ -0,0 +1,44 @@
+# Copyright (c) 2016 HuaWei, Inc.
+#
+# 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.
+from oslo_config import cfg
+
+
+class Configuration(object):
+
+    def __init__(self, conf):
+        """Initialize configuration."""
+        self.local_conf = conf
+
+    def register_opts(self, volume_opts, group=None):
+        self.local_conf.register_opts(volume_opts, group=group)
+
+    def set_override(self, name, override, group=None, enforce_type=False):
+        self.local_conf.set_override(name, override, group=group,
+                                     enforce_type=enforce_type)
+
+    def safe_get(self, value):
+        try:
+            return self.__getattr__(value)
+        except cfg.NoSuchOptError:
+            return None
+
+    def __getattr__(self, value):
+        # Don't use self.local_conf to avoid reentrant call to __getattr__()
+        local_conf = object.__getattribute__(self, 'local_conf')
+        return getattr(local_conf, value)
+
+    def __getitem__(self, key):
+        """Look up an option value and perform string substitution."""
+        return self.local_conf.__getitem__(key)

zaqar/storage/utils.py

@@ -22,6 +22,7 @@ from stevedore import driver
 from zaqar.common import errors
 from zaqar.common import utils
 from zaqar.i18n import _LE
+from zaqar.storage import configuration
 
 LOG = log.getLogger(__name__)
 
@@ -47,20 +48,31 @@ def dynamic_conf(uri, options, conf=None):
     storage_opts = utils.dict_to_conf(options)
     storage_group = u'drivers:message_store:%s' % storage_type
 
+    dynamic = False
     # NOTE(cpp-cabrera): register those options!
     if conf is None:
         conf = cfg.ConfigOpts()
     else:
-        conf = copy.copy(conf)
+        conf_wrap = configuration.Configuration(conf)
+        conf = copy.copy(conf_wrap)
+        dynamic = True
 
-    if storage_group not in conf:
-        conf.register_opts(storage_opts,
-                           group=storage_group)
-
-    if 'drivers' not in conf:
-        # NOTE(cpp-cabrera): parse general opts: 'drivers'
-        driver_opts = utils.dict_to_conf({'message_store': storage_type})
-        conf.register_opts(driver_opts, group=u'drivers')
+    if dynamic:
+        if not conf.safe_get(storage_group):
+            conf.register_opts(storage_opts,
+                               group=storage_group)
+        if not conf.safe_get('drivers'):
+            # NOTE(cpp-cabrera): parse general opts: 'drivers'
+            driver_opts = utils.dict_to_conf({'message_store': storage_type})
+            conf.register_opts(driver_opts, group=u'drivers')
+    else:
+        if storage_group not in conf:
+            conf.register_opts(storage_opts,
+                               group=storage_group)
+        if 'drivers' not in conf:
+            # NOTE(cpp-cabrera): parse general opts: 'drivers'
+            driver_opts = utils.dict_to_conf({'message_store': storage_type})
+            conf.register_opts(driver_opts, group=u'drivers')
 
     conf.set_override('message_store', storage_type, 'drivers',
                       enforce_type=True)