| # Copyright 2013 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 hashlib |
| import os |
| |
| |
| def CallAndRecordIfStale( |
| function, record_path=None, input_paths=None, input_strings=None, |
| force=False): |
| """Calls function if the md5sum of the input paths/strings has changed. |
| |
| The md5sum of the inputs is compared with the one stored in record_path. If |
| this has changed (or the record doesn't exist), function will be called and |
| the new md5sum will be recorded. |
| |
| If force is True, the function will be called regardless of whether the |
| md5sum is out of date. |
| """ |
| if not input_paths: |
| input_paths = [] |
| if not input_strings: |
| input_strings = [] |
| md5_checker = _Md5Checker( |
| record_path=record_path, |
| input_paths=input_paths, |
| input_strings=input_strings) |
| if force or md5_checker.IsStale(): |
| function() |
| md5_checker.Write() |
| |
| |
| def _UpdateMd5ForFile(md5, path, block_size=2**16): |
| with open(path, 'rb') as infile: |
| while True: |
| data = infile.read(block_size) |
| if not data: |
| break |
| md5.update(data) |
| |
| |
| def _UpdateMd5ForDirectory(md5, dir_path): |
| for root, _, files in os.walk(dir_path): |
| for f in files: |
| _UpdateMd5ForFile(md5, os.path.join(root, f)) |
| |
| |
| def _UpdateMd5ForPath(md5, path): |
| if os.path.isdir(path): |
| _UpdateMd5ForDirectory(md5, path) |
| else: |
| _UpdateMd5ForFile(md5, path) |
| |
| |
| class _Md5Checker(object): |
| def __init__(self, record_path=None, input_paths=None, input_strings=None): |
| if not input_paths: |
| input_paths = [] |
| if not input_strings: |
| input_strings = [] |
| |
| assert record_path.endswith('.stamp'), ( |
| 'record paths must end in \'.stamp\' so that they are easy to find ' |
| 'and delete') |
| |
| self.record_path = record_path |
| |
| md5 = hashlib.md5() |
| for i in sorted(input_paths): |
| _UpdateMd5ForPath(md5, i) |
| for s in input_strings: |
| md5.update(s) |
| self.new_digest = md5.hexdigest() |
| |
| self.old_digest = '' |
| if os.path.exists(self.record_path): |
| with open(self.record_path, 'r') as old_record: |
| self.old_digest = old_record.read() |
| |
| def IsStale(self): |
| return self.old_digest != self.new_digest |
| |
| def Write(self): |
| with open(self.record_path, 'w') as new_record: |
| new_record.write(self.new_digest) |