Add key-value storage in persistence plugins

cinderlib/persistence/base.py

@@ -43,6 +43,9 @@ class PersistenceDriverBase(object):
     def get_connections(self, connection_id=None, volume_id=None):
         raise NotImplemented()
 
+    def get_key_values(self, key):
+        raise NotImplemented()
+
     def set_volume(self, volume):
         self.reset_change_tracker(volume)
 
@@ -52,6 +55,9 @@ class PersistenceDriverBase(object):
     def set_connection(self, connection):
         self.reset_change_tracker(connection)
 
+    def set_key_value(self, key, value):
+        raise NotImplemented()
+
     def delete_volume(self, volume):
         self._set_deleted(volume)
         self.reset_change_tracker(volume)
@@ -64,6 +70,9 @@ class PersistenceDriverBase(object):
         self._set_deleted(connection)
         self.reset_change_tracker(connection)
 
+    def delete_key_value(self, key):
+        raise NotImplemented()
+
     def _set_deleted(self, resource):
         resource._ovo.deleted = True
         resource._ovo.deleted_at = timeutils.utcnow()