message_flags: Update 'do_update_message_flags' to send event on commit.

Earlier, we were using 'send_event' in do_update_message_flags
which can lead to a situation where we enqueue events but the
function fails at a later stage.

Events should not be sent until we know we're not rolling back.

Fixes part of #30489.

zerver/actions/message_flags.py

@@ -273,7 +273,7 @@ def do_update_message_flags(
     flagattr = getattr(UserMessage.flags, flag)
     flag_target = flagattr if is_adding else 0
 
-    with transaction.atomic(savepoint=False):
+    with transaction.atomic(durable=True):
         if flag == "read" and not is_adding:
             # We have an invariant that all stream messages marked as
             # unread must be in streams the user is subscribed to.
@@ -374,9 +374,11 @@ def do_update_message_flags(
             # details on the messages required to update the client's
             # `unread_msgs` data structure.
             raw_unread_data = get_raw_unread_data(user_profile, messages)
-        event["message_details"] = format_unread_message_details(user_profile.id, raw_unread_data)
+            event["message_details"] = format_unread_message_details(
+                user_profile.id, raw_unread_data
+            )
 
-    send_event(user_profile.realm, event, [user_profile.id])
+        send_event_on_commit(user_profile.realm, event, [user_profile.id])
 
         if flag == "read" and is_adding:
             event_time = timezone_now()

zerver/tests/test_message_flags.py

@@ -2,7 +2,7 @@ from typing import TYPE_CHECKING, Any
 from unittest import mock
 
 import orjson
-from django.db import connection, transaction
+from django.db import connection
 from typing_extensions import override
 
 from zerver.actions.message_flags import do_update_message_flags
@@ -1603,7 +1603,6 @@ class MessageAccessTests(ZulipTestCase):
 
         # Starring private stream messages you didn't receive fails.
         self.login("cordelia")
-        with transaction.atomic():
         result = self.change_star(message_ids)
         self.assert_json_error(result, "Invalid message(s)")
 
@@ -1619,7 +1618,6 @@ class MessageAccessTests(ZulipTestCase):
         # can't see it if you didn't receive the message and are
         # not subscribed.
         self.login("cordelia")
-        with transaction.atomic():
         result = self.change_star(message_ids)
         self.assert_json_error(result, "Invalid message(s)")
 
@@ -1661,7 +1659,6 @@ class MessageAccessTests(ZulipTestCase):
 
         guest_user = self.example_user("polonius")
         self.login_user(guest_user)
-        with transaction.atomic():
         result = self.change_star(message_id)
         self.assert_json_error(result, "Invalid message(s)")
 
@@ -1693,14 +1690,12 @@ class MessageAccessTests(ZulipTestCase):
 
         guest_user = self.example_user("polonius")
         self.login_user(guest_user)
-        with transaction.atomic():
         result = self.change_star(message_id)
         self.assert_json_error(result, "Invalid message(s)")
 
         # Guest user can't access messages of subscribed private streams if
         # history is not public to subscribers
         self.subscribe(guest_user, stream_name)
-        with transaction.atomic():
         result = self.change_star(message_id)
         self.assert_json_error(result, "Invalid message(s)")