PYTHON-4021 - Publish TopologyDescriptionChangedEvent on topology close (mongodb#1762)

Author: NoahStapp

pymongo/asynchronous/topology.py

@@ -664,9 +664,31 @@ async def close(self) -> None:
         # Publish only after releasing the lock.
         if self._publish_tp:
             assert self._events is not None
+            old_td = self._description
+            self._description = TopologyDescription(
+                TOPOLOGY_TYPE.Unknown,
+                {},
+                self._description.replica_set_name,
+                self._description.max_set_version,
+                self._description.max_election_id,
+                self._description._topology_settings,
+            )
+            self._events.put(
+                (
+                    self._listeners.publish_topology_description_changed,
+                    (
+                        old_td,
+                        self._description,
+                        self._topology_id,
+                    ),
+                )
+            )
             self._events.put((self._listeners.publish_topology_closed, (self._topology_id,)))
         if self._publish_server or self._publish_tp:
+            # Make sure the events executor thread is fully closed before publishing the remaining events
             self.__events_executor.close()
+            self.__events_executor.join(1)
+            process_events_queue(weakref.ref(self._events))  # type: ignore[arg-type]
 
     @property
     def description(self) -> TopologyDescription:

pymongo/synchronous/topology.py

@@ -662,9 +662,31 @@ def close(self) -> None:
         # Publish only after releasing the lock.
         if self._publish_tp:
             assert self._events is not None
+            old_td = self._description
+            self._description = TopologyDescription(
+                TOPOLOGY_TYPE.Unknown,
+                {},
+                self._description.replica_set_name,
+                self._description.max_set_version,
+                self._description.max_election_id,
+                self._description._topology_settings,
+            )
+            self._events.put(
+                (
+                    self._listeners.publish_topology_description_changed,
+                    (
+                        old_td,
+                        self._description,
+                        self._topology_id,
+                    ),
+                )
+            )
             self._events.put((self._listeners.publish_topology_closed, (self._topology_id,)))
         if self._publish_server or self._publish_tp:
+            # Make sure the events executor thread is fully closed before publishing the remaining events
             self.__events_executor.close()
+            self.__events_executor.join(1)
+            process_events_queue(weakref.ref(self._events))  # type: ignore[arg-type]
 
     @property
     def description(self) -> TopologyDescription:

test/discovery_and_monitoring/rs/compatible.json

@@ -16,7 +16,7 @@
               "b:27017"
             ],
             "minWireVersion": 0,
-            "maxWireVersion": 6
+            "maxWireVersion": 21
           }
         ],
         [

test/discovery_and_monitoring/rs/compatible_unknown.json

@@ -16,7 +16,7 @@
               "b:27017"
             ],
             "minWireVersion": 0,
-            "maxWireVersion": 6
+            "maxWireVersion": 21
           }
         ]
       ],

test/discovery_and_monitoring/sharded/compatible.json

@@ -23,7 +23,7 @@
             "isWritablePrimary": true,
             "msg": "isdbgrid",
             "minWireVersion": 0,
-            "maxWireVersion": 6
+            "maxWireVersion": 21
           }
         ]
       ],

test/discovery_and_monitoring/single/compatible.json

@@ -11,7 +11,7 @@
             "helloOk": true,
             "isWritablePrimary": true,
             "minWireVersion": 0,
-            "maxWireVersion": 6
+            "maxWireVersion": 21
           }
         ]
       ],

test/discovery_and_monitoring/single/too_old_then_upgraded.json

@@ -1,5 +1,5 @@
 {
-  "description": "Standalone with default maxWireVersion of 0 is upgraded to one with maxWireVersion 6",
+  "description": "Standalone with default maxWireVersion of 0 is upgraded to one with maxWireVersion 21",
   "uri": "mongodb://a",
   "phases": [
     {
@@ -35,7 +35,7 @@
             "helloOk": true,
             "isWritablePrimary": true,
             "minWireVersion": 0,
-            "maxWireVersion": 6
+            "maxWireVersion": 21
           }
         ]
       ],