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# Copyright 2015 The Chromium Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
from __future__ import print_function
import json
import sys
import fieldtrial_to_struct
def _hex(ch):
hv = hex(ord(ch)).replace('0x', '')
hv.zfill(2)
return hv.upper()
# URL escapes the delimiter characters from the output. urllib.quote is not
# used because it cannot escape '.'.
def _escape(str):
result = str
# Must perform replace on '%' first before the others.
for c in '%:/.,':
result = result.replace(c, '%' + _hex(c))
return result
def _FindDuplicates(entries):
seen = set()
duplicates = set()
for entry in entries:
if entry in seen:
duplicates.add(entry)
else:
seen.add(entry)
return sorted(duplicates)
def _CheckForDuplicateFeatures(enable_features, disable_features):
enable_features = [f.split('<')[0] for f in enable_features]
enable_features_set = set(enable_features)
if len(enable_features_set) != len(enable_features):
raise Exception('Duplicate feature(s) in enable_features: ' +
', '.join(_FindDuplicates(enable_features)))
disable_features = [f.split('<')[0] for f in disable_features]
disable_features_set = set(disable_features)
if len(disable_features_set) != len(disable_features):
raise Exception('Duplicate feature(s) in disable_features: ' +
', '.join(_FindDuplicates(disable_features)))
features_in_both = enable_features_set.intersection(disable_features_set)
if len(features_in_both) > 0:
raise Exception('Conflicting features set as both enabled and disabled: ' +
', '.join(features_in_both))
def _FindFeaturesOverriddenByArgs(args):
"""Returns a list of the features enabled or disabled by the flags in args."""
overridden_features = []
for arg in args:
if (arg.startswith('--enable-features=')
or arg.startswith('--disable-features=')):
_, _, arg_val = arg.partition('=')
overridden_features.extend(arg_val.split(','))
return [f.split('<')[0] for f in overridden_features]
def MergeFeaturesAndFieldTrialsArgs(args):
"""Merges duplicate features and field trials arguments.
Merges multiple instances of --enable-features, --disable-features,
--force-fieldtrials and --force-fieldtrial-params. Any such merged flags are
moved to the end of the returned list. The original argument ordering is
otherwise maintained.
TODO(crbug.com/40663174): Add functionality to handle duplicate flags using
the Foo<Bar syntax. Currently, the implementation considers e.g. 'Foo',
'Foo<Bar' and 'Foo<Baz' to be different. Also add functionality to handle
cases where the same trial is specified with different groups via
--force-fieldtrials, which isn't currently unhandled.
Args:
args: An iterable of strings representing command line arguments.
Returns:
A new list of strings representing the merged command line arguments.
"""
merged_args = []
disable_features = set()
enable_features = set()
force_fieldtrials = set()
force_fieldtrial_params = set()
for arg in args:
if arg.startswith('--disable-features='):
disable_features.update(arg.split('=', 1)[1].split(','))
elif arg.startswith('--enable-features='):
enable_features.update(arg.split('=', 1)[1].split(','))
elif arg.startswith('--force-fieldtrials='):
# A trailing '/' is optional. Do not split by '/' as that would separate
# each group name from the corresponding trial name.
force_fieldtrials.add(arg.split('=', 1)[1].rstrip('/'))
elif arg.startswith('--force-fieldtrial-params='):
force_fieldtrial_params.update(arg.split('=', 1)[1].split(','))
else:
merged_args.append(arg)
# Sort arguments to ensure determinism.
if disable_features:
merged_args.append('--disable-features=%s' % ','.join(
sorted(disable_features)))
if enable_features:
merged_args.append('--enable-features=%s' % ','.join(
sorted(enable_features)))
if force_fieldtrials:
merged_args.append('--force-fieldtrials=%s' % '/'.join(
sorted(force_fieldtrials)))
if force_fieldtrial_params:
merged_args.append('--force-fieldtrial-params=%s' % ','.join(
sorted(force_fieldtrial_params)))
return merged_args
def GenerateArgs(config_path, platform, override_args=None):
"""Generates command-line flags for enabling field trials.
Generates a list of command-line switches to enable field trials for the
provided config_path and platform. If override_args is set, all field trials
that conflict with any listed --enable-features or --disable-features argument
are skipped.
Args:
config_path: The path to the fieldtrial testing config JSON file.
platform: A string representing the platform on which the tests will be run.
override_args (optional): An iterable of string command line arguments.
Returns:
A list of string command-line arguments.
"""
try:
with open(config_path, 'r') as config_file:
config = json.load(config_file)
except (IOError, ValueError):
return []
platform_studies = fieldtrial_to_struct.ConfigToStudies(config, [platform])
if override_args is None:
override_args = []
overriden_features_set = set(_FindFeaturesOverriddenByArgs(override_args))
# Should skip any experiment that will enable or disable a feature that is
# also enabled or disabled in the override_args.
#
# In addition because this is only used for benchmarks we also remove any
# experiment that sets `disable_benchmarking`. In actual field trials this
# would require `--enable-benchmarking` to be passed to the Chrome binary,
# but since this is generated without command line args we err on the side
# of caution and remove that experiment.
def ShouldSkipExperiment(experiment):
if experiment.get('disable_benchmarking', "false") == "true":
return True
experiment_features = (experiment.get('disable_features', [])
+ experiment.get('enable_features', []))
return not overriden_features_set.isdisjoint(experiment_features)
studies = []
params = []
enable_features = []
disable_features = []
for study in platform_studies:
study_name = study['name']
experiments = study['experiments']
# For now, only take the first experiment.
experiment = experiments[0]
if ShouldSkipExperiment(experiment):
continue
selected_study = [study_name, experiment['name']]
studies.extend(selected_study)
param_list = []
if 'params' in experiment:
for param in experiment['params']:
param_list.append(param['key'])
param_list.append(param['value'])
if len(param_list):
# Escape the variables for the command-line.
selected_study = [_escape(x) for x in selected_study]
param_list = [_escape(x) for x in param_list]
param = '%s:%s' % ('.'.join(selected_study), '/'.join(param_list))
params.append(param)
for feature in experiment.get('enable_features', []):
enable_features.append(feature + '<' + study_name)
for feature in experiment.get('disable_features', []):
disable_features.append(feature + '<' + study_name)
if not len(studies):
return []
_CheckForDuplicateFeatures(enable_features, disable_features)
args = ['--force-fieldtrials=%s' % '/'.join(studies)]
if len(params):
args.append('--force-fieldtrial-params=%s' % ','.join(params))
if len(enable_features):
args.append('--enable-features=%s' % ','.join(enable_features))
if len(disable_features):
args.append('--disable-features=%s' % ','.join(disable_features))
return args
def main():
if len(sys.argv) < 3:
print('Usage: fieldtrial_util.py [config_path] [platform]')
print('Optionally pass \'shell_cmd\' as an extra argument to print')
print('quoted command line arguments.')
exit(-1)
print_shell_cmd = len(sys.argv) >= 4 and sys.argv[3] == 'shell_cmd'
supported_platforms = ['android', 'android_webview', 'chromeos', 'ios',
'linux', 'mac', 'windows']
if sys.argv[2] not in supported_platforms:
print('\'%s\' is an unknown platform. Supported platforms: %s' %
(sys.argv[2], supported_platforms))
exit(-1)
generated_args = GenerateArgs(sys.argv[1], sys.argv[2])
if print_shell_cmd:
print(" ".join(map((lambda arg: '"{0}"'.format(arg)), generated_args)))
else:
print(generated_args)
if __name__ == '__main__':
main()
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