0a7c3bf46b
For some Nova scenarios, we will need suppot for set_multi/get_multi/delete_multi for writing to either memcache or dictionary backend. So let's add support for operating on multiple keys. Note that if we don't implement this the default CacheBackend class throws NotImplementedError Closes-Bug: #1483322 Change-Id: I1aca9e65b3be038a507ced8dd039c5413d6c4ac2