Merge pull request #457 from edx/will/TIM-661

Catch HTTP errors that occur when downloading classifier data

openassessment/assessment/api/ai_worker.py

@@ -2,6 +2,7 @@
 Public interface for AI training and grading, used by workers.
 """
 import logging
+from httplib import HTTPException
 from django.db import DatabaseError
 from dogapi import dog_stats_api
 from openassessment.assessment.models import (
@@ -80,7 +81,10 @@ def get_grading_task_params(grading_workflow_uuid):
                 for classifier in classifiers
             }
         }
-    except (DatabaseError, ClassifierSerializeError, IncompleteClassifierSet, ValueError) as ex:
+    except (
+        DatabaseError, ClassifierSerializeError, IncompleteClassifierSet,
+        ValueError, IOError, HTTPException
+    ) as ex:
         msg = (
             u"An unexpected error occurred while retrieving "
             u"classifiers for the grading workflow with UUID {uuid}: {ex}"

openassessment/assessment/models/ai.py

@@ -276,6 +276,11 @@ class AIClassifierSet(models.Model):
             dict: keys are criteria names, values are JSON-serializable classifier data
             If there are no classifiers in the set, returns None
 
+        Raises:
+            ValueError
+            IOError
+            httplib.HTTPException
+
         """
         # First check the in-memory cache
         # We use an in-memory cache because the classifier data will most often
@@ -364,6 +369,7 @@ class AIClassifier(models.Model):
         Raises:
             ValueError
             IOError
+            httplib.HTTPException
 
         """
         return json.loads(self.classifier_data.read())  # pylint:disable=E1101