Merge "Update cache doc"

doc/source/admin/identity-caching-layer.rst

@@ -50,6 +50,9 @@ So to enable only the token back end caching, set the values as follows:
 
 Current functional back ends are:
 
+``dogpile.cache.null``
+   A "null" backend that effectively disables all cache operations.(Default)
+
 ``dogpile.cache.memcached``
    Memcached back end using the standard ``python-memcached`` library.
 
@@ -71,8 +74,24 @@ Current functional back ends are:
    between processes. This means that caching and cache invalidation will not
    be consistent or reliable.
 
-``dogpile.cache.mongo``
-    MongoDB as caching back end.
+``dogpile.cache.memory_pickle``
+   In-memory cache, but serializes objects with pickle lib. It's not suitable
+   for use outside of testing. The reason is the same with
+   ``dogpile.cache.memory``
+
+``oslo_cache.mongo``
+   MongoDB as caching back end.
+
+``oslo_cache.memcache_pool``
+   Memcached backend that does connection pooling.
+
+``oslo_cache.etcd3gw``
+   Uses etcd 3.x for storage.
+
+``oslo_cache.dict``
+   A DictCacheBackend based on dictionary, not suitable for use outside of
+   testing as it does not share cache between processes.This means that caching
+   and cache invalidation will not be consistent or reliable.
 
 Caching for tokens and tokens validation
 ----------------------------------------