| # Copyright 2019 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. |
| |
| import os |
| import sys |
| |
| if sys.version_info.major == 2: |
| import cPickle as pickle # 'cPickle' is faster than 'pickle' on Py2 |
| else: |
| import pickle |
| |
| |
| def read_pickle_file(filepath): |
| """ |
| Reads the content of the file as a pickled object. |
| """ |
| with open(filepath, 'rb') as file_obj: |
| return pickle.load(file_obj) |
| |
| |
| def write_pickle_file_if_changed(filepath, obj): |
| """ |
| Writes the given object out to |filepath| if the content changed. |
| |
| Returns True if the object is written to the file, and False if skipped. |
| """ |
| return write_to_file_if_changed(filepath, pickle.dumps(obj)) |
| |
| |
| def write_to_file_if_changed(filepath, contents): |
| """ |
| Writes the given contents out to |filepath| if the contents changed. |
| |
| Returns True if the data is written to the file, and False if skipped. |
| """ |
| try: |
| with open(filepath, 'rb') as file_obj: |
| old_contents = file_obj.read() |
| except (OSError, EnvironmentError): |
| pass |
| else: |
| if contents == old_contents: |
| return False |
| os.remove(filepath) |
| |
| if not os.path.exists(os.path.dirname(filepath)): |
| os.makedirs(os.path.dirname(filepath)) |
| |
| with open(filepath, 'wb') as file_obj: |
| file_obj.write(contents) |
| return True |
