Send emails to celery after committing

In case the celery broker (redis) is down this may result in lost
emails, but this is a very unlikely case (especially since usually
sessions wouldn't work either with redis being down) and without
committing first, an event log entry may not be persisted in the
database yet when the task runs and wants to update its state.

indico/core/notifications.py

@@ -86,11 +86,6 @@ def _log_email(email, event, module, user):
                      user, type_='email', data=log_data)
 
 
-def has_email_queue():
-    """Check whether there are any emails queued"""
-    return bool(g.get('email_queue'))
-
-
 def flush_email_queue():
     """Send all the emails in the queue"""
     queue = g.pop('email_queue', [])

indico/web/rh.py

@@ -36,7 +36,7 @@
 from indico.core.db import db
 from indico.core.db.sqlalchemy.core import handle_sqlalchemy_database_error
 from indico.core.logger import Logger, sentry_set_tags
-from indico.core.notifications import flush_email_queue, has_email_queue
+from indico.core.notifications import flush_email_queue
 from indico.legacy.common import fossilize
 from indico.legacy.common.security import Sanitization
 from indico.util.i18n import _
@@ -270,13 +270,8 @@ def process(self):
             signals.after_process.send()
 
             if self.commit:
-                if has_email_queue():
-                    # ensure we fail early (before sending out e-mails)
-                    # in case there are DB constraint violations, etc...
-                    db.enforce_constraints()
-                    flush_email_queue()
-
                 db.session.commit()
+                flush_email_queue()
             else:
                 db.session.rollback()
         except DatabaseError: