Move checksum calculation to Unit class

trans/formats.py

@@ -27,6 +27,7 @@ from translate.storage import factory
 from trans.util import get_source, get_string
 from translate.misc import quote
 import re
+import hashlib
 import importlib
 import __builtin__
 
@@ -145,6 +146,17 @@ class FileUnit(object):
             return self.mainunit.getid()
         return context
 
+    def get_checksum(self):
+        '''
+        Returns checksum of source string, used for quick lookup.
+
+        We use MD5 as it is faster than SHA1.
+        '''
+        md5 = hashlib.md5()
+        md5.update(self.get_source().encode('utf-8'))
+        md5.update(self.get_context().encode('utf-8'))
+        return md5.hexdigest()
+
     def is_translated(self):
         '''
         Checks whether unit is translated.

trans/models/unit.py

@@ -48,11 +48,10 @@ class UnitManager(models.Manager):
         '''
         Process translation toolkit unit and stores/updates database entry.
         '''
+        # Get basic unit data
         src = unit.get_source()
         ctx = unit.get_context()
-
-        # TODO: move to unit
-        checksum = msg_checksum(src, ctx)
+        checksum = unit.get_checksum()
 
         # Try getting existing unit
         dbunit = None