Server: .../depsgrahp: format Last-Modified header in ISO-8601 format

This format allows sub-second precision, which is what we need for reliable
queries.

packages/flamenco/flamenco/managers/api.py

@@ -261,6 +261,7 @@ def get_depsgraph(manager_id, request_json):
             task_query['status'] = {'$in': DEPSGRAPH_CLEAN_SLATE_TASK_STATUSES}
         else:
             # Not clean slate, just give all updated tasks assigned to this manager.
+            log.debug('Modified-since header: %s', modified_since)
             modified_since = dateutil.parser.parse(modified_since)
             task_query['_updated'] = {'$gt': modified_since}
             task_query['status'] = {'$in': DEPSGRAPH_MODIFIED_SINCE_TASK_STATUSES}
@@ -296,36 +297,11 @@ def get_depsgraph(manager_id, request_json):
     if depsgraph:
         last_modification = max(task['_updated'] for task in depsgraph)
         log.debug('Last modification was %s', last_modification)
-        resp.headers['Last-Modified'] = format_http_date(last_modification)
+        # We need a format that can handle sub-second precision.
+        resp.headers['Last-Modified'] = last_modification.isoformat()
+        resp.headers['X-Last-Modified-Format'] = 'ISO-8601'
     return resp
 
 
-def format_http_date(last_modification):
-    """Format the given timestamp into RFC 1123 format.
-
-    :param last_modification: datetime in UTC timezone
-    :type last_modification: datetime.datetime
-    """
-
-    import time
-    import email.utils
-
-    # This incorrectly represents 'stamp' in local time, instead of the UTC we get
-    # from the database.
-    stamp = time.mktime(last_modification.timetuple())
-
-    # Subtract the UTC to local time offset
-    timediff = time.mktime(time.gmtime(0))
-    stamp -= timediff
-
-    http_date = email.utils.formatdate(
-        timeval=stamp,
-        localtime=False,
-        usegmt=True
-    )  # --> Wed, 22 Oct 2008 10:55:46 GMT
-
-    return http_date
-
-
 def setup_app(app):
     app.register_api_blueprint(api_blueprint, url_prefix='/flamenco/managers')

packages/flamenco/tests/test_depsgraph.py

@@ -95,7 +95,7 @@ class DepsgraphTest(AbstractFlamencoTest):
         last_modified = parse(resp.headers['Last-Modified'])
         with self.app.test_request_context():
             task0 = self.flamenco.db('tasks').find_one({'_id': self.task_ids[0]})
-        self.assert_equal_to_second(task0['_updated'], last_modified)
+        self.assertEqual(task0['_updated'], last_modified)
 
         # The tasks in the database, as well as the response, should be set to claimed-by-manager
         with self.app.test_request_context():
@@ -164,15 +164,9 @@ class DepsgraphTest(AbstractFlamencoTest):
             task0 = self.flamenco.db('tasks').find_one({'_id': self.task_ids[0]})
             task2 = self.flamenco.db('tasks').find_one({'_id': self.task_ids[2]})
         # They should be equal to second precision
-        self.assert_equal_to_second(task2['_updated'], last_modified)
+        self.assertEqual(task2['_updated'], last_modified)
 
         self.assertEqual(task0['status'], u'claimed-by-manager')
         self.assertEqual(task2['status'], u'claimed-by-manager')
         self.assertEqual(2 * [u'claimed-by-manager'],
                          [task['status'] for task in depsgraph])
-
-    def assert_equal_to_second(self, actual, expected):
-        import datetime
-
-        diff = datetime.timedelta(microseconds=actual.microsecond)
-        self.assertEqual(actual - diff, expected)