Remove duplication in the staleness check

backdrop/core/data_set.py

@@ -25,26 +25,9 @@ def name(self):
         return self.config['name']
 
     def is_recent_enough(self):
-        max_age_expected = self.get_max_age_expected()
-
-        now = timeutils.now()
-        last_updated = self.get_last_updated()
-
-        """
-        - If `max_age_expected` is None we're saying
-        'hey, we're not going to check this'.
-        - If `last_updated` is a null value,
-        the data-set has never been updated,
-        so it doesn't really give us any value to say
-        'you should update this thing you've never updated before'
-        because we already know that, right?
-        """
-        if max_age_expected is None or not last_updated:
-            return True
-
-        max_age_expected_delta = datetime.timedelta(seconds=max_age_expected)
-
-        return (now - last_updated) < max_age_expected_delta
+        seconds_out_of_date = self.get_seconds_out_of_date()
+
+        return seconds_out_of_date is None or seconds_out_of_date < 0
 
     def get_max_age_expected(self):
         return self.config.get('max_age_expected',
@@ -55,20 +38,30 @@ def get_last_updated(self):
 
     def get_seconds_out_of_date(self):
         now = timeutils.now()
+        max_age_expected = self.get_max_age_expected()
+        last_updated = self.get_last_updated()
 
-        if not self.get_last_updated() or self.get_max_age_expected() is None:
+        if not self._is_staleness_appropriate(last_updated, max_age_expected):
             return None
-        else:
-            last_updated = self.get_last_updated()
 
-        max_age_delta = datetime.timedelta(
-            seconds=self.get_max_age_expected()
-        )
+        max_age_delta = datetime.timedelta(seconds=max_age_expected)
 
         return int((
             now - last_updated - max_age_delta
         ).total_seconds())
 
+    def _is_staleness_appropriate(self, last_updated, max_age_expected):
+        """
+        - If `max_age_expected` is None we're saying
+        'hey, we're not going to check this'.
+        - If `last_updated` is a null value,
+        the data-set has never been updated,
+        so it doesn't really give us any value to say
+        'you should update this thing you've never updated before'
+        because we already know that, right?
+        """
+        return last_updated and max_age_expected
+
     def create_if_not_exists(self):
         if not self.storage.data_set_exists(self.name):
             self.storage.create_data_set(self.name, self.config['capped_size'])