apps/compress/versioning/hash/__init__.py

   1 import cStringIO
   2 from hashlib import md5, sha1
   3 import os
   4
   5 from compress.conf import settings
   6 from compress.utils import concat, get_output_filename
   7 from compress.versioning.base import VersioningBase
   8
   9
  10 class HashVersioningBase(VersioningBase):
  11
  12     def __init__(self, hash_method):
  13         self.hash_method = hash_method
  14
  15     def needs_update(self, output_file, source_files, version):
  16         output_file_name = get_output_filename(output_file, version)
  17         ph = settings.COMPRESS_VERSION_PLACEHOLDER
  18         of = output_file
  19         try:
  20             phi = of.index(ph)
  21             old_version = output_file_name[phi:phi + len(ph) - len(of)]
  22             return (version != old_version), version
  23         except ValueError:
  24             # no placeholder found, do not update, manual update if needed
  25             return False, version
  26
  27     def get_version(self, source_files):
  28         buf = concat(source_files)
  29         s = cStringIO.StringIO(buf)
  30         version = self.get_hash(s)
  31         s.close()
  32         return version
  33
  34     def get_hash(self, f, CHUNK=2 ** 16):
  35         m = self.hash_method()
  36         while 1:
  37             chunk = f.read(CHUNK)
  38             if not chunk:
  39                 break
  40             m.update(chunk)
  41         return m.hexdigest()
  42
  43
  44 class MD5Versioning(HashVersioningBase):
  45
  46     def __init__(self):
  47         super(MD5Versioning, self).__init__(md5)
  48
  49
  50 class SHA1Versioning(HashVersioningBase):
  51
  52     def __init__(self):
  53         super(SHA1Versioning, self).__init__(sha1)