Use entrypoints for backends

Register the oslo_cache backends via the dogpile.cache entry points
rather than manually in configure.

Change-Id: If62bbd8c613770926bd116ceaa05463630cbc0c0

oslo_cache/backends/mongo.py

@@ -16,7 +16,7 @@ import abc
 import datetime
 
 from dogpile.cache import api
-from dogpile.cache import util as dp_util
+from dogpile import util as dp_util
 from oslo_cache import core
 from oslo_log import log
 from oslo_utils import importutils

oslo_cache/core.py

@@ -61,13 +61,6 @@ NO_VALUE = api.NO_VALUE
 
 _LOG = log.getLogger(__name__)
 
-_BACKENDS = [
-    ('oslo_cache.mongo', 'oslo_cache.backends.mongo', 'MongoCacheBackend'),
-    ('oslo_cache.memcache_pool', 'oslo_cache.backends.memcache_pool',
-     'PooledMemcachedBackend'),
-    ('oslo_cache.dict', 'oslo_cache.backends.dictionary', 'DictCacheBackend'),
-]
-
 
 class _DebugProxy(proxy.ProxyBackend):
     """Extra Logging ProxyBackend."""
@@ -366,22 +359,13 @@ def get_memoization_decorator(conf, region, group, expiration_group=None):
 def configure(conf):
     """Configure the library.
 
+    Register the required oslo.cache config options into an oslo.config CONF
+    object.
+
     This must be called before conf().
 
-    The following backends are registered in :mod:`dogpile.cache`:
-
-    * ``oslo_cache.mongo`` -
-      :class:`oslo_cache.backends.mongo.MongoCacheBackend`
-    * ``oslo_cache.memcache_pool`` -
-      :class:`oslo_cache.backends.memcache_pool.PooledMemcachedBackend`
-    * ``oslo_cache.dict`` -
-      :class:`oslo_cache.backends.dictionary.DictCacheBackend`
-
     :param conf: The configuration object.
     :type conf: oslo_config.cfg.ConfigOpts
 
     """
     _opts.configure(conf)
-
-    for backend in _BACKENDS:
-        dogpile.cache.register_backend(*backend)

setup.cfg

@@ -27,6 +27,11 @@ packages =
 oslo.config.opts =
     oslo.cache = oslo_cache._opts:list_opts
 
+dogpile.cache =
+    oslo_cache.mongo = oslo_cache.backends.mongo:MongoCacheBackend
+    oslo_cache.memcache_pool = oslo_cache.backends.memcache_pool:PooledMemcachedBackend
+    oslo_cache.dict = oslo_cache.backends.dictionary:DictCacheBackend
+
 [extras]
 dogpile =
   python-memcached>=1.56 # PSF