Add functionality to remove deactivated users from the monthly_active_users table (#10947)

* add test

* add function to remove user from monthly active table in deactivate code

* add function to remove user from monthly active table

* add changelog entry

* update changelog number

* requested changes

* update docstring on new function

* fix lint error

* Update synapse/storage/databases/main/monthly_active_users.py

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

2 files changed, 28 insertions, 0 deletions

diff --git a/synapse/handlers/deactivate_account.py b/synapse/handlers/deactivate_account.py
index 9ae5b7750e..12bdca7445 100644
--- a/synapse/handlers/deactivate_account.py
+++ b/synapse/handlers/deactivate_account.py
@@ -133,6 +133,10 @@ class DeactivateAccountHandler(BaseHandler):
         # delete from user directory
         await self.user_directory_handler.handle_local_user_deactivated(user_id)
 
+        # If the user is present in the monthly active users table
+        # remove them
+        await self.store.remove_deactivated_user_from_mau_table(user_id)
+
         # Mark the user as erased, if they asked for that
         if erase_data:
             user = UserID.from_string(user_id)
diff --git a/synapse/storage/databases/main/monthly_active_users.py b/synapse/storage/databases/main/monthly_active_users.py
index a14ac03d4b..ec4d47a560 100644
--- a/synapse/storage/databases/main/monthly_active_users.py
+++ b/synapse/storage/databases/main/monthly_active_users.py
@@ -354,3 +354,27 @@ class MonthlyActiveUsersStore(MonthlyActiveUsersWorkerStore):
                         await self.upsert_monthly_active_user(user_id)
             elif now - last_seen_timestamp > LAST_SEEN_GRANULARITY:
                 await self.upsert_monthly_active_user(user_id)
+
+    async def remove_deactivated_user_from_mau_table(self, user_id: str) -> None:
+        """
+        Removes a deactivated user from the monthly active user
+        table and resets affected caches.
+
+        Args:
+            user_id(str): the user_id to remove
+        """
+
+        rows_deleted = await self.db_pool.simple_delete(
+            table="monthly_active_users",
+            keyvalues={"user_id": user_id},
+            desc="simple_delete",
+        )
+
+        if rows_deleted != 0:
+            await self.invalidate_cache_and_stream(
+                "user_last_seen_monthly_active", (user_id,)
+            )
+            await self.invalidate_cache_and_stream("get_monthly_active_count", ())
+            await self.invalidate_cache_and_stream(
+                "get_monthly_active_count_by_service", ()
+            )