FactCache changes

* Fix FactCache to conform to the dict API
  * update needs to take a dict rather than a key and a value
  * __init__ needs to allow for setting the intial dictionary
* Remove unneeded _display and _cache attributes
* Move ansible.plugins.cache.FactCache to
  ansible.vars.fact_cache.FactCache because this isn't part of the cache
  plugin API.
* Add backwards compatibility when calling update on the new FactCache
* Remove code for calling old FactCache. There's no way to call the old
  FactCache so there's no need for backwards compatible code for calling
  code.  Backwards compatibility is handling things which are calling
  the new FactCache.
* Port our code to the new FactCache location.

lib/ansible/plugins/cache/__init__.py

@@ -1,4 +1,5 @@
 # (c) 2014, Michael DeHaan <michael.dehaan@gmail.com>
+# (c) 2018, Ansible Project
 #
 # This file is part of Ansible
 #
@@ -29,10 +30,27 @@ from ansible.module_utils._text import to_bytes
 from ansible.module_utils.common._collections_compat import MutableMapping
 from ansible.plugins.loader import cache_loader
 from ansible.utils.display import Display
+from ansible.vars.fact_cache import FactCache as RealFactCache
 
 display = Display()
 
 
+class FactCache(RealFactCache):
+    """
+    This is for backwards compatibility.  Will be removed after deprecation.  It was removed as it
+    wasn't actually part of the cache plugin API.  It's actually the code to make use of cache
+    plugins, not the cache plugin itself.  Subclassing it wouldn't yield a usable Cache Plugin and
+    there was no facility to use it as anything else.
+    """
+    def __init__(self, *args, **kwargs):
+        display.deprecated('ansible.plugins.cache.FactCache has been moved to'
+                           ' ansible.vars.fact_cache.FactCache.  If you are looking for the class'
+                           ' to subclass for a cache plugin, you want'
+                           ' ansible.plugins.cache.BaseCacheModule or one of its subclasses.',
+                           version='2.12')
+        super(FactCache, self).__init__(*args, **kwargs)
+
+
 class BaseCacheModule(with_metaclass(ABCMeta, object)):
 
     # Backwards compat only.  Just import the global display instead
@@ -244,65 +262,6 @@ class BaseFileCacheModule(BaseCacheModule):
         pass
 
 
-class FactCache(MutableMapping):
-
-    def __init__(self, *args, **kwargs):
-
-        self._plugin = cache_loader.get(C.CACHE_PLUGIN)
-        if not self._plugin:
-            raise AnsibleError('Unable to load the facts cache plugin (%s).' % (C.CACHE_PLUGIN))
-
-        # Backwards compat: self._display isn't really needed, just import the global display and use that.
-        self._display = display
-
-        # in memory cache so plugins don't expire keys mid run
-        self._cache = {}
-
-    def __getitem__(self, key):
-        if not self._plugin.contains(key):
-            raise KeyError
-        return self._plugin.get(key)
-
-    def __setitem__(self, key, value):
-        self._plugin.set(key, value)
-
-    def __delitem__(self, key):
-        self._plugin.delete(key)
-
-    def __contains__(self, key):
-        return self._plugin.contains(key)
-
-    def __iter__(self):
-        return iter(self._plugin.keys())
-
-    def __len__(self):
-        return len(self._plugin.keys())
-
-    def copy(self):
-        """ Return a primitive copy of the keys and values from the cache. """
-        return dict(self)
-
-    def keys(self):
-        return self._plugin.keys()
-
-    def flush(self):
-        """ Flush the fact cache of all keys. """
-        self._plugin.flush()
-
-    def update(self, host_facts):
-        """ We override the normal update to ensure we always use the 'setter' method """
-        for key in host_facts:
-            try:
-                host_cache = self._plugin.get(key)
-                if host_cache:
-                    host_cache.update(host_facts[key])
-                else:
-                    host_cache = host_facts[key]
-                self._plugin.set(key, host_cache)
-            except KeyError:
-                self._plugin.set(key, host_facts[key])
-
-
 class InventoryFileCacheModule(BaseFileCacheModule):
     """
     A caching module backed by file based storage.