send_email: Change clear_scheduled_emails to only take one user.

No codepath except tests passes in more than one user_profile -- and
doing so is what makes the deduplication necessary.

Simplify the API by making it only take one user_profile id.

zerver/lib/actions.py

@@ -1214,7 +1214,7 @@ def do_deactivate_user(
         change_user_is_active(user_profile, False)
 
         delete_user_sessions(user_profile)
-        clear_scheduled_emails([user_profile.id])
+        clear_scheduled_emails(user_profile.id)
 
         event_time = timezone_now()
         RealmAuditLog.objects.create(
@@ -5036,7 +5036,7 @@ def do_change_notification_settings(
 
     # Disabling digest emails should clear a user's email queue
     if name == "enable_digest_emails" and not value:
-        clear_scheduled_emails([user_profile.id], ScheduledEmail.DIGEST)
+        clear_scheduled_emails(user_profile.id, ScheduledEmail.DIGEST)
 
     user_profile.save(update_fields=[name])
     event = {

zerver/lib/send_email.py

@@ -416,23 +416,20 @@ def clear_scheduled_invitation_emails(email: str) -> None:
 
 
 @transaction.atomic(savepoint=False)
-def clear_scheduled_emails(user_ids: List[int], email_type: Optional[int] = None) -> None:
+def clear_scheduled_emails(user_id: int, email_type: Optional[int] = None) -> None:
     # We need to obtain a FOR UPDATE lock on the selected rows to keep a concurrent
     # execution of this function (or something else) from deleting them before we access
     # the .users attribute.
-    items = ScheduledEmail.objects.filter(users__in=user_ids).select_for_update()
+    items = ScheduledEmail.objects.filter(users__in=[user_id]).select_for_update()
     if email_type is not None:
         items = items.filter(type=email_type)
 
-    deduplicated_items = {}
     for item in items:
-        deduplicated_items[item.id] = item
-    for item in deduplicated_items.values():
         # Now we want a FOR UPDATE lock on the item.users rows
         # to prevent a concurrent transaction from mutating them
         # simultaneously.
         item.users.all().select_for_update()
-        item.users.remove(*user_ids)
+        item.users.remove(user_id)
         if item.users.all().count() == 0:
             # Due to our transaction holding the row lock we have a guarantee
             # that the obtained COUNT is accurate, thus we can reliably use it

zerver/tests/test_users.py

@@ -1392,7 +1392,7 @@ class ActivateTest(ZulipTestCase):
         assert email is not None and email.users is not None
         self.assertEqual(email.users.count(), 2)
 
-    def test_clear_scheduled_emails_with_multiple_user_ids(self) -> None:
+    def test_clear_schedule_emails(self) -> None:
         hamlet = self.example_user("hamlet")
         iago = self.example_user("iago")
         send_future_email(
@@ -1402,20 +1402,7 @@ class ActivateTest(ZulipTestCase):
             delay=datetime.timedelta(hours=1),
         )
         self.assertEqual(ScheduledEmail.objects.count(), 1)
-        clear_scheduled_emails([hamlet.id, iago.id])
-        self.assertEqual(ScheduledEmail.objects.count(), 0)
-
-    def test_clear_schedule_emails_with_one_user_id(self) -> None:
-        hamlet = self.example_user("hamlet")
-        iago = self.example_user("iago")
-        send_future_email(
-            "zerver/emails/followup_day1",
-            iago.realm,
-            to_user_ids=[hamlet.id, iago.id],
-            delay=datetime.timedelta(hours=1),
-        )
-        self.assertEqual(ScheduledEmail.objects.count(), 1)
-        clear_scheduled_emails([hamlet.id])
+        clear_scheduled_emails(hamlet.id)
         self.assertEqual(ScheduledEmail.objects.count(), 1)
         self.assertEqual(ScheduledEmail.objects.filter(users=hamlet).count(), 0)
         self.assertEqual(ScheduledEmail.objects.filter(users=iago).count(), 1)

zerver/views/unsubscribe.py

@@ -39,7 +39,7 @@ def do_missedmessage_unsubscribe(user_profile: UserProfile) -> None:
 
 
 def do_welcome_unsubscribe(user_profile: UserProfile) -> None:
-    clear_scheduled_emails([user_profile.id], ScheduledEmail.WELCOME)
+    clear_scheduled_emails(user_profile.id, ScheduledEmail.WELCOME)
 
 
 def do_digest_unsubscribe(user_profile: UserProfile) -> None: