handling for 304 not modified responses

skyscanner/skyscanner.py

@@ -43,6 +43,10 @@ class MissingParameter(KeyError):
     """Is thrown when expected request parameter is missing."""
     pass
 
+class NotModified(Exception):
+
+    """Is thrown when the server gives a 304 response."""
+    pass
 
 class Transport(object):
 
@@ -166,13 +170,17 @@ def poll_session(self, poll_url, initial_delay=2, delay=1, tries=20, errors=STRI
         time.sleep(initial_delay)
         poll_response = None
         for n in range(tries):
-            poll_response = self.make_request(poll_url, headers=self._headers(),
-                                              errors=errors, **params)
+            try:
+                poll_response = self.make_request(poll_url, headers=self._headers(),
+                                                  errors=errors, **params)
 
-            if self.is_poll_complete(poll_response):
-                return poll_response
-            else:
-                time.sleep(delay)
+                if self.is_poll_complete(poll_response):
+                    return poll_response
+
+            except NotModified:
+                pass
+            time.sleep(delay)
+
 
         if STRICT == errors:
             raise ExceededRetries(
@@ -265,6 +273,9 @@ def _headers(self):
         return {'Accept': 'application/%s' % self.response_format}
 
     def _default_resp_callback(self, resp):
+        if resp and resp.status_code == 304:
+            raise NotModified
+
         if not resp or not resp.content:
             raise EmptyResponse('Response has no content.')