Handle str not working when exceptions contain unicode

When a exception contains unicode, the usage of str() in
python 3.3 will cause an error, so try to use the native
python text_type first, and then only revert back to using
str() if that fails.

Change-Id: I4f36642453555c8e288cb67956d47bd0bcb8783f

tooz/drivers/zookeeper.py

@@ -17,9 +17,12 @@
 from kazoo import client
 from kazoo import exceptions
 from kazoo.protocol import paths
+import six
 from zake import fake_client
 
+
 from tooz import coordination
+from tooz import utils
 
 _TOOZ_NAMESPACE = "tooz"
 
@@ -49,7 +52,7 @@ class BaseZooKeeperDriver(coordination.CoordinationDriver):
         except exceptions.NoNodeError:
             raise coordination.ToozError("tooz namespace has not been created")
         except exceptions.ZookeeperError as e:
-            raise coordination.ToozError(str(e))
+            raise coordination.ToozError(utils.exception_message(e))
 
     def create_group(self, group_id):
         group_path = "/%s/%s" % (_TOOZ_NAMESPACE, group_id)
@@ -62,12 +65,13 @@ class BaseZooKeeperDriver(coordination.CoordinationDriver):
         try:
             async_result.get(block=True, timeout=timeout)
         except exceptions.NodeExistsError:
-            raise coordination.MemberAlreadyExist(str(member_id))
+            raise coordination.MemberAlreadyExist("member '%s' already exists"
+                                                  % (member_id))
         except exceptions.NoNodeError:
             raise coordination.GroupNotCreated("group '%s' has not been "
                                                "created" % group_id)
         except exceptions.ZookeeperError as e:
-            raise coordination.ToozError(str(e))
+            raise coordination.ToozError(utils.exception_message(e))
 
     def join_group(self, group_id, capabilities=b""):
         member_path = self._path_member(group_id, self._member_id)
@@ -87,7 +91,7 @@ class BaseZooKeeperDriver(coordination.CoordinationDriver):
                                                "has not been created" %
                                                member_id, group_id)
         except exceptions.ZookeeperError as e:
-            raise coordination.ToozError(str(e))
+            raise coordination.ToozError(utils.exception_message(e))
 
     def leave_group(self, group_id):
         member_path = self._path_member(group_id, self._member_id)
@@ -103,7 +107,7 @@ class BaseZooKeeperDriver(coordination.CoordinationDriver):
             raise coordination.GroupNotCreated("group '%s' does not exist" %
                                                group_id)
         except exceptions.ZookeeperError as e:
-            raise coordination.ToozError(str(e))
+            raise coordination.ToozError(utils.exception_message(e))
         else:
             return members_ids
 
@@ -124,7 +128,7 @@ class BaseZooKeeperDriver(coordination.CoordinationDriver):
                                                "has not been created" %
                                                (member_id, group_id))
         except exceptions.ZookeeperError as e:
-            raise coordination.ToozError(str(e))
+            raise coordination.ToozError(utils.exception_message(e))
 
     def update_capabilities(self, group_id, capabilities):
         member_path = self._path_member(group_id, self._member_id)
@@ -143,7 +147,7 @@ class BaseZooKeeperDriver(coordination.CoordinationDriver):
                                                "has not been created" %
                                                (member_id, group_id))
         except exceptions.ZookeeperError as e:
-            raise coordination.ToozError(str(e))
+            raise coordination.ToozError(utils.exception_message(e))
         else:
             return capabilities
 
@@ -161,7 +165,7 @@ class BaseZooKeeperDriver(coordination.CoordinationDriver):
         except exceptions.NoNodeError:
             raise coordination.ToozError("tooz namespace has not been created")
         except exceptions.ZookeeperError as e:
-            raise coordination.ToozError(str(e))
+            raise coordination.ToozError(utils.exception_message(e))
         else:
             return group_ids
 

tooz/utils.py

@@ -0,0 +1,27 @@
+# -*- coding: utf-8 -*-
+
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+#    Copyright (C) 2014 Yahoo! Inc. 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.
+
+import six
+
+
+def exception_message(exc):
+    """Return the string representation of exception."""
+    try:
+        return six.text_type(exc)
+    except UnicodeError:
+        return str(exc)