fix: Batching failures when individual event errors bubble up

event_routing_backends/__init__.py

@@ -2,4 +2,4 @@
 Various backends for receiving edX LMS events..
 """
 
-__version__ = '8.3.0'
+__version__ = '8.3.1'

event_routing_backends/backends/events_router.py

@@ -225,6 +225,17 @@ def queue_event(self, redis, event):
 
         if queue_size >= settings.EVENT_ROUTING_BACKEND_BATCH_SIZE or self.time_to_send(redis):
             batch = redis.rpop(self.queue_name, queue_size)
+
+            orig_size = len(batch)
+            # Deduplicate list, in some misconfigured cases tracking events can be emitted to the
+            # bus twice, causing them to be processed twice, which LRSs will reject.
+            # See: https://github.com/openedx/event-routing-backends/issues/410
+            batch = [i for n, i in enumerate(batch) if i not in batch[n + 1:]]
+            final_size = len(batch)
+
+            if final_size != orig_size:  # pragma: no cover
+                logger.warning(f"{orig_size - final_size} duplicate events in event-routing-backends batch queue! "
+                               f"This is a likely due to misconfiguration of EVENT_TRACKING_BACKENDS.")
             return batch
 
         return None
@@ -237,7 +248,9 @@ def time_to_send(self, redis):
         if not last_sent:
             return True
         time_passed = (datetime.now() - datetime.fromisoformat(last_sent.decode('utf-8')))
-        return time_passed > timedelta(seconds=settings.EVENT_ROUTING_BACKEND_BATCH_INTERVAL)
+        ready = time_passed > timedelta(seconds=settings.EVENT_ROUTING_BACKEND_BATCH_INTERVAL)
+
+        return ready
 
     def process_event(self, event):
         """

event_routing_backends/processors/caliper/tests/test_caliper.py

@@ -5,7 +5,6 @@
 
 from django.test import SimpleTestCase
 from django.test.utils import override_settings
-from eventtracking.processors.exceptions import EventEmissionExit, NoBackendEnabled
 from mock import MagicMock, call, patch, sentinel
 
 from event_routing_backends.processors.caliper.transformer_processor import CaliperProcessor
@@ -29,13 +28,11 @@ def setUp(self):
 
     @override_settings(CALIPER_EVENTS_ENABLED=False)
     def test_skip_event_when_disabled(self):
-        with self.assertRaises(NoBackendEnabled):
-            self.processor(self.sample_event)
+        self.assertFalse(self.processor(self.sample_event))
 
     @patch('event_routing_backends.processors.mixins.base_transformer_processor.logger')
     def test_send_method_with_no_transformer_implemented(self, mocked_logger):
-        with self.assertRaises(EventEmissionExit):
-            self.processor([self.sample_event])
+        self.assertFalse(self.processor([self.sample_event]))
 
         mocked_logger.error.assert_called_once_with(
             'Could not get transformer for %s event.',
@@ -130,6 +127,5 @@ def test_send_method_with_successfull_flow_logging_disabled(
     def test_with_no_registry(self, mocked_logger):
         backend = CaliperProcessor()
         backend.registry = None
-        with self.assertRaises(EventEmissionExit):
-            self.assertIsNone(backend([self.sample_event]))
+        self.assertFalse(backend([self.sample_event]))
         mocked_logger.exception.assert_called_once()

event_routing_backends/processors/mixins/base_transformer.py

@@ -175,9 +175,7 @@ def get_data(self, key, required=False):
             result = None
 
         if result is None:
-            if not required:
-                logger.warning('Could not get value for %s in event "%s"', key, self.event.get('name', None))
-            else:
+            if required:
                 raise ValueError(
                     'Could not get value for {} in event "{}"'.format(key, self.event.get('name', None))
                 )

event_routing_backends/processors/mixins/base_transformer_processor.py

@@ -3,7 +3,7 @@
 """
 from logging import getLogger
 
-from eventtracking.processors.exceptions import EventEmissionExit, NoTransformerImplemented
+from eventtracking.processors.exceptions import NoBackendEnabled, NoTransformerImplemented
 
 logger = getLogger(__name__)
 
@@ -34,13 +34,18 @@ def __call__(self, events):
         """
         returned_events = []
         for event in events:
-            transformed_event = self.transform_event(event)
-            if not transformed_event:
-                raise EventEmissionExit
-            if isinstance(transformed_event, list):
-                returned_events += transformed_event
-            else:
-                returned_events.append(transformed_event)
+            try:
+                transformed_event = self.transform_event(event)
+                if not transformed_event:
+                    pass
+                elif isinstance(transformed_event, list):
+                    returned_events += transformed_event
+                else:
+                    returned_events.append(transformed_event)
+
+            # If the backend isn't enabled at all, early out
+            except NoBackendEnabled:
+                break
         return returned_events
 
     def transform_event(self, event):
@@ -60,7 +65,6 @@ def transform_event(self, event):
 
         try:
             transformed_event = self.get_transformed_event(event)
-
         except NoTransformerImplemented:
             logger.error('Could not get transformer for %s event.', event_name)
             return None

event_routing_backends/processors/xapi/tests/test_xapi.py

@@ -5,7 +5,6 @@
 
 from django.test import SimpleTestCase
 from django.test.utils import override_settings
-from eventtracking.processors.exceptions import EventEmissionExit, NoBackendEnabled
 from mock import MagicMock, call, patch, sentinel
 from tincan import Activity, Statement
 
@@ -25,13 +24,11 @@ def setUp(self):
 
     @override_settings(XAPI_EVENTS_ENABLED=False)
     def test_skip_event_when_disabled(self):
-        with self.assertRaises(NoBackendEnabled):
-            self.processor(self.sample_event)
+        self.assertFalse(self.processor(self.sample_event))
 
     @patch('event_routing_backends.processors.mixins.base_transformer_processor.logger')
     def test_send_method_with_no_transformer_implemented(self, mocked_logger):
-        with self.assertRaises(EventEmissionExit):
-            self.processor([self.sample_event])
+        self.assertFalse(self.processor([self.sample_event]))
 
         mocked_logger.error.assert_called_once_with(
             'Could not get transformer for %s event.',
@@ -91,9 +88,7 @@ def test_send_method_with_invalid_object(self, mocked_logger, mocked_get_transfo
         mocked_transformer.transform.return_value = transformed_event
         mocked_get_transformer.return_value = mocked_transformer
 
-        with self.assertRaises(EventEmissionExit):
-            self.processor([self.sample_event])
-
+        self.assertFalse(self.processor([self.sample_event]))
         self.assertNotIn(call(transformed_event.to_json()), mocked_logger.mock_calls)
 
     @override_settings(XAPI_EVENT_LOGGING_ENABLED=False)
@@ -116,6 +111,5 @@ def test_send_method_with_successfull_flow_no_logger(self, mocked_logger, mocked
     def test_with_no_registry(self, mocked_logger):
         backend = XApiProcessor()
         backend.registry = None
-        with self.assertRaises(EventEmissionExit):
-            self.assertIsNone(backend([self.sample_event]))
+        self.assertFalse(backend([self.sample_event]))
         mocked_logger.exception.assert_called_once()