Store contentsum with unit (issue #326)

trans/formats.py

@@ -216,6 +216,17 @@ class FileUnit(object):
         md5.update(self.get_context().encode('utf-8'))
         return md5.hexdigest()
 
+    def get_contentsum(self):
+        '''
+        Returns checksum of source string and conntext, 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

@@ -379,6 +379,7 @@ class Unit(models.Model):
         fuzzy = unit.is_fuzzy()
         translated = unit.is_translated()
         previous_source = unit.get_previous_source()
+        contentsum = unit.get_contentsum()
 
         # Monolingual files handling
         if unit.template is not None:
@@ -412,6 +413,7 @@ class Unit(models.Model):
                 translated == self.translated and
                 comment == self.comment and
                 pos == self.position and
+                contentsum == self.contentsum and
                 previous_source == self.previous_source):
             return
 
@@ -424,6 +426,7 @@ class Unit(models.Model):
         self.fuzzy = fuzzy
         self.translated = translated
         self.comment = comment
+        self.contentsum = contentsum
         self.previous_source = previous_source
         self.save(
             force_insert=created,