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