tools: import a small tools to compute size of archive policies

Change-Id: I131664319cc9f9c8eda9b5c24e0de04664da3f25

tools/gnocchi-archive-policy-size.py

@@ -0,0 +1,49 @@
+#!/usr/bin/env python
+#
+# Copyright (c) 2016 Red Hat, Inc.
+#
+# 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.
+
+import sys
+
+from gnocchi import utils
+
+
+WORST_CASE_BYTES_PER_POINT = 8.04
+
+
+if (len(sys.argv) - 1) % 2 != 0:
+    print("Usage: %s <granularity> <timespan> ... <granularity> <timespan>"
+          % sys.argv[0])
+    sys.exit(1)
+
+
+def sizeof_fmt(num, suffix='B'):
+    for unit in ('', 'Ki', 'Mi', 'Gi', 'Ti', 'Pi', 'Ei', 'Zi'):
+        if abs(num) < 1024.0:
+            return "%3.1f%s%s" % (num, unit, suffix)
+        num /= 1024.0
+    return "%.1f%s%s" % (num, 'Yi', suffix)
+
+
+size = 0
+for g, t in utils.grouper(sys.argv[1:], 2):
+    granularity = utils.to_timespan(g)
+    timespan = utils.to_timespan(t)
+    points = timespan.total_seconds() / granularity.total_seconds()
+    cursize = points * WORST_CASE_BYTES_PER_POINT
+    size += cursize
+    print("%s over %s = %d points = %s" % (g, t, points, sizeof_fmt(cursize)))
+
+print("Total: " + sizeof_fmt(size))