misc: delete unused safe_get_or_create (#64485)

Introduced in #60658 it used a global lock on model's table to prevent
multiple access, using the Lock model is simpler and more efficient.

src/authentic2/utils/models.py

@@ -16,26 +16,9 @@
 
 import itertools
 
-from django.conf import settings
-from django.db import connection, transaction
 from django.utils.text import slugify
 
 
-def safe_get_or_create(model, defaults=None, **kwargs):
-    assert (
-        getattr(settings, 'TESTING', False) or not connection.in_atomic_block
-    ), 'safe_get_or_create cannot be used in inside a transaction'
-
-    try:
-        return model.objects.get(**kwargs), False
-    except model.DoesNotExist:
-        pass
-    with transaction.atomic():
-        with connection.cursor() as cur:
-            cur.execute('LOCK TABLE "%s" IN EXCLUSIVE MODE' % model._meta.db_table)
-        return model.objects.get_or_create(defaults=defaults, **kwargs)
-
-
 def generate_slug(name, seen_slugs=None, max_length=256):
     base_slug = slugify(name).lstrip('_')
     slug = base_slug[:max_length]

tests/test_utils_models.py

@@ -15,42 +15,7 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 # authentic2
 
-import threading
-
-from django.db import connection
-
-from authentic2.custom_user.models import User
-from authentic2.utils.models import generate_slug, safe_get_or_create
-
-
-def test_safe_get_or_create(transactional_db, concurrency):
-    EMAIL = 'john.doe@example.net'
-    barrier = threading.Barrier(concurrency)
-    users = []
-    exceptions = []
-    threads = []
-
-    def thread_run():
-        try:
-            barrier.wait()
-            user, created = safe_get_or_create(User, email=EMAIL, defaults={'email': EMAIL})
-        except Exception as e:
-            exceptions.append(e)
-        else:
-            if created:
-                users.append(user)
-        finally:
-            connection.close()
-
-    for _ in range(concurrency):
-        threads.append(threading.Thread(target=thread_run))
-        threads[-1].start()
-    for thread in threads:
-        thread.join()
-    assert not exceptions
-    assert len(users) == 1
-    assert User.objects.count() == 1
-    users[0].delete()
+from authentic2.utils.models import generate_slug
 
 
 def test_generate_slug():