Fix dispatcher exception during unsubs (#1073)

Author: abhinavsingh

proxy/core/event/dispatcher.py

@@ -59,14 +59,19 @@ def handle_event(self, ev: Dict[str, Any]) -> None:
                 'event_name': eventNames.SUBSCRIBED,
             })
         elif ev['event_name'] == eventNames.UNSUBSCRIBE:
-            # send ack
-            logger.info('unsubscription request ack sent')
-            self.subscribers[ev['event_payload']['sub_id']].send({
-                'event_name': eventNames.UNSUBSCRIBED,
-            })
-            # close conn and delete subscriber
-            self.subscribers[ev['event_payload']['sub_id']].close()
-            del self.subscribers[ev['event_payload']['sub_id']]
+            if ev['event_payload']['sub_id'] in self.subscribers:
+                # send ack
+                logger.debug('unsubscription request ack sent')
+                self.subscribers[ev['event_payload']['sub_id']].send({
+                    'event_name': eventNames.UNSUBSCRIBED,
+                })
+                # close conn and delete subscriber
+                self.subscribers[ev['event_payload']['sub_id']].close()
+                del self.subscribers[ev['event_payload']['sub_id']]
+            else:
+                logger.info(
+                    'unsubscription request ack not sent, subscriber already gone',
+                )
         else:
             # logger.info(ev)
             self._broadcast(ev)

proxy/plugin/cache/cache_responses.py

@@ -85,6 +85,17 @@ def write_content_type(
             if parser.code and int(parser.code) == httpStatusCodes.SWITCHING_PROTOCOLS:
                 logger.warning('Bypassing websocket response packet')
                 return None
+            # Certain responses may never reach complete state
+            #
+            # E.g. Facebook sends HTML page with content-length: 0
+            # and as chunked encoded, while keeping the connection alive.
+            # This connection gets dropped after timeout period.
+            # Hence, technically response never completed or rather
+            # terminated cleanly with a CRLF tokens.
+            #
+            # E.g. When it's a web socket upgrade response, same problem
+            # can arise.  The response may not reach completion state.
+            #
             # if not parser.is_complete:
             #     logger.warning(data)
             #     return None