Sync units module from olso

There are lots of numeric expressions across some projects, such as
1024*1024 , 1024**3, 1000, 1000000 etc. This patch adds binary and
decimal unit constants. Replacing nummeric experssions with these
constants makes code more readable.

Change-Id: I45fb5a10009f22b1eedb07b3e52f1ce40403b068

glance/openstack/common/units.py

@@ -0,0 +1,40 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright 2013 IBM Corp
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+"""
+Unit constants
+"""
+
+#Binary unit constants.
+Ki = 1024
+Mi = 1024 ** 2
+Gi = 1024 ** 3
+Ti = 1024 ** 4
+Pi = 1024 ** 5
+Ei = 1024 ** 6
+Zi = 1024 ** 7
+Yi = 1024 ** 8
+
+#Decimal unit constants.
+k = 1000
+M = 1000 ** 2
+G = 1000 ** 3
+T = 1000 ** 4
+P = 1000 ** 5
+E = 1000 ** 6
+Z = 1000 ** 7
+Y = 1000 ** 8

openstack-common.conf

@@ -13,6 +13,7 @@ module=notifier
 module=policy
 module=strutils
 module=timeutils
+module=units
 module=uuidutils
 
 # The base module to hold the copy of openstack.common