Fixed #30451 -- Added ASGI handler and coroutine-safety.

This adds an ASGI handler, asgi.py file for the default project layout,
a few async utilities and adds async-safety to many parts of Django.

1 files changed, 8 insertions, 2 deletions

diff --git a/django/db/utils.py b/django/db/utils.py
index cb7f3d0f0b..4bd119227f 100644
--- a/django/db/utils.py
+++ b/django/db/utils.py
@@ -1,7 +1,8 @@
 import pkgutil
 from importlib import import_module
 from pathlib import Path
-from threading import local
+
+from asgiref.local import Local
 
 from django.conf import settings
 from django.core.exceptions import ImproperlyConfigured
@@ -139,7 +140,12 @@ class ConnectionHandler:
         like settings.DATABASES).
         """
         self._databases = databases
-        self._connections = local()
+        # Connections needs to still be an actual thread local, as it's truly
+        # thread-critical. Database backends should use @async_unsafe to protect
+        # their code from async contexts, but this will give those contexts
+        # separate connections in case it's needed as well. There's no cleanup
+        # after async contexts, though, so we don't allow that if we can help it.
+        self._connections = Local(thread_critical=True)
 
     @cached_property
     def databases(self):