Throw DequeueError when reading unprocessable data from queue.

rq/exceptions.py

@@ -1,2 +1,5 @@
 class NoQueueError(Exception):
     pass
+
+class DequeueError(Exception):
+    pass

rq/queue.py

@@ -2,6 +2,7 @@ import uuid
 from functools import total_ordering
 from pickle import loads, dumps
 from .proxy import conn
+from .exceptions import DequeueError
 
 class DelayedResult(object):
     """Proxy object that is returned as a result of `Queue.enqueue()` calls.
@@ -44,8 +45,11 @@ class Job(object):
     @classmethod
     def unpickle(cls, pickle_data):
         """Constructs a Job instance form the given pickle'd job tuple data."""
+        try:
             job_tuple = loads(pickle_data)
             return Job(job_tuple)
+        except (AttributeError, ValueError, IndexError):
+            raise DequeueError('Could not decode job tuple.')
 
     def __init__(self, job_tuple, origin=None):
         self.func, self.args, self.kwargs, self.rv_key = job_tuple

tests/test_rq.py

@@ -1,8 +1,9 @@
 import unittest
-from pickle import loads
+from pickle import loads, dumps
 from redis import Redis
 from logbook import NullHandler
 from rq import conn, Queue, Worker
+from rq.exceptions import DequeueError
 
 # Test data
 def testjob(name=None):
@@ -135,6 +136,37 @@ class TestQueue(RQTestCase):
         self.assertEquals(job.args[0], 'for Bar', 'Bar should be dequeued second.')
 
 
+    def test_dequeue_unpicklable_data(self):
+        """Error handling of invalid pickle data."""
+
+        # Push non-pickle data on the queue
+        q = Queue('foo')
+        blob = 'this is nothing like pickled data'
+        self.testconn.rpush(q._key, blob)
+
+        with self.assertRaises(DequeueError):
+            q.dequeue()  # error occurs when perform()'ing
+
+        # Push value pickle data, but not representing a job tuple
+        q = Queue('foo')
+        blob = dumps('this is not a job tuple')
+        self.testconn.rpush(q._key, blob)
+
+        with self.assertRaises(DequeueError):
+            q.dequeue()  # error occurs when perform()'ing
+
+        # Push slightly incorrect pickled data onto the queue (simulate
+        # a function that can't be imported from the worker)
+        q = Queue('foo')
+
+        job_tuple = dumps((testjob, [], dict(name='Frank'), 'unused'))
+        blob = job_tuple.replace('testjob', 'fooobar')
+        self.testconn.rpush(q._key, blob)
+
+        with self.assertRaises(DequeueError):
+            q.dequeue()  # error occurs when dequeue()'ing
+
+
 class TestWorker(RQTestCase):
     def test_create_worker(self):
         """Worker creation."""