Student must wait XQUEUE_WAITTIME_BETWEEN_REQUESTS between queueing submissions

common/lib/capa/capa/capa_problem.py

@@ -29,6 +29,7 @@ from xml.sax.saxutils import unescape
 
 import calc
 from correctmap import CorrectMap
+from datetime import datetime
 import eia
 import inputtypes
 from util import contextualize_text, convert_files_to_filenames
@@ -204,6 +205,21 @@ class LoncapaProblem(object):
         '''
         return any([self.correct_map.is_queued(answer_id) for answer_id in self.correct_map])
 
+
+    def get_recentmost_queuetime(self):
+        '''
+        Returns a DateTime object that represents the timestamp of the most recent queueing request, or None if not queued
+        '''
+        if not self.is_queued():
+            return None
+
+        # Get a list of timestamps of all queueing requests, then convert it to a DateTime object
+        queuetimes = [self.correct_map.get_queuetime_str(answer_id) for answer_id in self.correct_map if self.correct_map.is_queued(answer_id)]
+        queuetimes = [datetime.strptime(qt,'%Y%m%d%H%M%S') for qt in queuetimes]
+
+        return max(queuetimes)
+
+
     def grade_answers(self, answers):
         '''
         Grade student responses.  Called by capa_module.check_problem.

common/lib/xmodule/xmodule/capa_module.py

@@ -7,7 +7,8 @@ import traceback
 import re
 import sys
 
-from datetime import timedelta
+from datetime import datetime, timedelta
+from django.conf import settings
 from lxml import etree
 from pkg_resources import resource_string
 
@@ -462,11 +463,13 @@ class CapaModule(XModule):
             self.system.track_function('save_problem_check_fail', event_info)
             raise NotFoundError('Problem must be reset before it can be checked again')
 
-        # Problem queued. Student should not be able to submit
-        '''
+        # Problem queued. Students must wait XQUEUE_WAITTIME_BETWEEN_REQUESTS
         if self.lcp.is_queued():
-            return {'success': False, 'html': 'Already queued'} 
-        '''
+            current_time = datetime.now()
+            prev_submit_time = self.lcp.get_recentmost_queuetime() 
+            if (current_time-prev_submit_time).total_seconds() < settings.XQUEUE_WAITTIME_BETWEEN_REQUESTS:
+                msg = 'You must wait %d seconds between queueing requests' % settings.XQUEUE_WAITTIME_BETWEEN_REQUESTS
+                return {'success': msg, 'html': ''}
 
         try:
             old_state = self.lcp.get_state()

lms/envs/dev.py

@@ -63,6 +63,7 @@ XQUEUE_INTERFACE = {
     },
     "basic_auth": ('anant', 'agarwal'),
 }
+XQUEUE_WAITTIME_BETWEEN_REQUESTS = 5 # seconds
 
 # Make the keyedcache startup warnings go away
 CACHE_TIMEOUT = 0