blob: 7a85037febf39748903b90756d6281783dc9eb99 [file] [log] [blame]
# Copyright 2015 The Chromium Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
"""Tools for gradually enabling a feature on a deterministic set of machines.
Add a flag to your program to control the percentage of machines that a new
feature should be enabled on::
def add_argparse_options(self, parser):
parser.add_argument('--myfeature-percent', type=int, default=0)
def main(self, opts):
if experiments.is_active_for_host('myfeature', opts.myfeature_percent):
# do myfeature
import hashlib
import logging
import socket
import struct
def _is_active(labels, percent):
h = hashlib.md5()
for label, value in sorted(labels.iteritems()):
# The first 8 bytes of the hash digest as an unsigned integer.
hash_num = struct.unpack_from('Q', h.digest())[0]
return (hash_num % 100) < percent
def is_active_for_host(experiment_name, percent):
ret = _is_active({
'name': experiment_name,
'host': socket.getfqdn(),
}, percent)
if ret:'Experiment "%s" is active', experiment_name)
return ret