fix: encode keys before caching

This patch addresses an error in the caching layer that prevented it
from playing nice with backends like memcached that expect keys to be
bytestrings rather than unicode strings. The change is made in
oslo.cache to make its use as transparent as possible to users.

Change-Id: Iee48e16393321ff7908807a9f0f7fa20480ec5f4
Closes-Bug: 1230556

marconi/common/cache/backends.py

@@ -13,12 +13,12 @@
 #    under the License.
 
 import abc
+import six
 
 
+@six.add_metaclass(abc.ABCMeta)
 class BaseCache(object):
 
-    __metaclass__ = abc.ABCMeta
-
     def __init__(self, conf, group, cache_namespace):
         self.conf = conf[group]
         self._cache_namespace = cache_namespace
@@ -68,10 +68,19 @@ class BaseCache(object):
 
         :param key: The key to be prefixed
         """
+        prepared = key
         if self._cache_namespace:
-            return ("%(prefix)s-%(key)s" %
-                    {'prefix': self._cache_namespace, 'key': key})
-        return key
+            prepared = ("%(prefix)s-%(key)s" %
+                        {'prefix': self._cache_namespace, 'key': key})
+
+        # NOTE(cpp-cabrera): some caching backends (memcache) enforce
+        # that the key type must be bytes. This is here to ensure that
+        # this precondition is respected and that users can continue
+        # to use the caching layer transparently.
+        if isinstance(prepared, six.text_type):
+            prepared = prepared.encode('utf8')
+
+        return prepared
 
     def add(self, key, value, ttl=0):
         """Sets the value for a key if it doesn't exist

marconi/proxy/utils/lookup.py

@@ -27,7 +27,7 @@ def partition(project, queue, catalogue_controller, cache):
     :param cache: cache for catalogue - updated if lookup fails
     :returns: Maybe text - partition name or None if not found
     """
-    key = u'q.{project}.{queue}'.format(project=project, queue=queue)
+    key = u'q.{project}/{queue}'.format(project=project, queue=queue)
     name = cache.get(key)
     if not name:
         try: