Fixed #30448, Fixed #35618 -- Do not close connection in atomic block.

Previously, the `django.db.close_old_connections` handler for
`request_started` and `request_finished` would incorrectly close any
connection within a `transaction.atomic` block (such as the one
automatically used by `django.db.TestCase`), leading to
`InterfaceError: connection already closed`.

The test client and many of our tests have been working around this
bug by manually suppressing the `close_old_connections` handler, but
the workarounds are incomplete and the bug still affects other
projects.  Fix the bug and remove the workarounds.

Signed-off-by: Anders Kaseorg <andersk@mit.edu>

django/db/backends/base/base.py

@@ -593,7 +593,7 @@ class BaseDatabaseWrapper:
         Close the current connection if unrecoverable errors have occurred
         or if it outlived its maximum age.
         """
-        if self.connection is not None:
+        if self.connection is not None and not self.in_atomic_block:
             self.health_check_done = False
             # If the application didn't restore the original autocommit setting,
             # don't take chances, drop the connection.

django/test/client.py

@@ -17,8 +17,7 @@ from django.core.handlers.asgi import ASGIRequest
 from django.core.handlers.base import BaseHandler
 from django.core.handlers.wsgi import LimitedStream, WSGIRequest
 from django.core.serializers.json import DjangoJSONEncoder
-from django.core.signals import got_request_exception, request_finished, request_started
-from django.db import close_old_connections
+from django.core.signals import got_request_exception, request_started
 from django.http import HttpHeaders, HttpRequest, QueryDict, SimpleCookie
 from django.test import signals
 from django.test.utils import ContextList
@@ -121,9 +120,7 @@ def closing_iterator_wrapper(iterable, close):
     try:
         yield from iterable
     finally:
-        request_finished.disconnect(close_old_connections)
         close()  # will fire request_finished
-        request_finished.connect(close_old_connections)
 
 
 async def aclosing_iterator_wrapper(iterable, close):
@@ -131,9 +128,7 @@ async def aclosing_iterator_wrapper(iterable, close):
         async for chunk in iterable:
             yield chunk
     finally:
-        request_finished.disconnect(close_old_connections)
         close()  # will fire request_finished
-        request_finished.connect(close_old_connections)
 
 
 def conditional_content_removal(request, response):
@@ -172,9 +167,7 @@ class ClientHandler(BaseHandler):
         if self._middleware_chain is None:
             self.load_middleware()
 
-        request_started.disconnect(close_old_connections)
         request_started.send(sender=self.__class__, environ=environ)
-        request_started.connect(close_old_connections)
         request = WSGIRequest(environ)
         # sneaky little hack so that we can easily get round
         # CsrfViewMiddleware.  This makes life easier, and is probably
@@ -203,9 +196,7 @@ class ClientHandler(BaseHandler):
                     response.streaming_content, response.close
                 )
         else:
-            request_finished.disconnect(close_old_connections)
             response.close()  # will fire request_finished
-            request_finished.connect(close_old_connections)
 
         return response
 
@@ -228,9 +219,7 @@ class AsyncClientHandler(BaseHandler):
         else:
             body_file = FakePayload("")
 
-        request_started.disconnect(close_old_connections)
         await request_started.asend(sender=self.__class__, scope=scope)
-        request_started.connect(close_old_connections)
         # Wrap FakePayload body_file to allow large read() in test environment.
         request = ASGIRequest(scope, LimitedStream(body_file, len(body_file)))
         # Sneaky little hack so that we can easily get round
@@ -255,10 +244,8 @@ class AsyncClientHandler(BaseHandler):
                     response.streaming_content, response.close
                 )
         else:
-            request_finished.disconnect(close_old_connections)
             # Will fire request_finished.
             await sync_to_async(response.close, thread_sensitive=False)()
-            request_finished.connect(close_old_connections)
         return response
 
 

tests/asgi/tests.py

@@ -12,7 +12,6 @@ from django.core.asgi import get_asgi_application
 from django.core.exceptions import RequestDataTooBig
 from django.core.handlers.asgi import ASGIHandler, ASGIRequest
 from django.core.signals import request_finished, request_started
-from django.db import close_old_connections
 from django.http import HttpResponse, StreamingHttpResponse
 from django.test import (
     AsyncRequestFactory,
@@ -45,10 +44,6 @@ class SignalHandler:
 class ASGITest(SimpleTestCase):
     async_request_factory = AsyncRequestFactory()
 
-    def setUp(self):
-        request_started.disconnect(close_old_connections)
-        self.addCleanup(request_started.connect, close_old_connections)
-
     async def test_get_asgi_application(self):
         """
         get_asgi_application() returns a functioning ASGI callable.

tests/backends/base/test_base.py

@@ -381,6 +381,11 @@ class ConnectionHealthChecksTests(SimpleTestCase):
         connection.set_autocommit(True)
         self.assertIs(new_connection, connection.connection)
 
+    def test_no_close_in_atomic(self):
+        with transaction.atomic():
+            connection.close_if_unusable_or_obsolete()
+            self.run_query()
+
 
 class MultiDatabaseTests(TestCase):
     databases = {"default", "other"}

tests/cache/tests.py

@@ -27,7 +27,7 @@ from django.core.cache import (
 from django.core.cache.backends.base import InvalidCacheBackendError
 from django.core.cache.backends.redis import RedisCacheClient
 from django.core.cache.utils import make_template_fragment_key
-from django.db import close_old_connections, connection, connections
+from django.db import connection, connections
 from django.db.backends.utils import CursorWrapper
 from django.http import (
     HttpRequest,
@@ -1560,15 +1560,11 @@ class BaseMemcachedTests(BaseCacheTests):
     def test_close(self):
         # For clients that don't manage their connections properly, the
         # connection is closed when the request is complete.
-        signals.request_finished.disconnect(close_old_connections)
-        try:
-            with mock.patch.object(
-                cache._class, "disconnect_all", autospec=True
-            ) as mock_disconnect:
-                signals.request_finished.send(self.__class__)
-                self.assertIs(mock_disconnect.called, self.should_disconnect_on_close)
-        finally:
-            signals.request_finished.connect(close_old_connections)
+        with mock.patch.object(
+            cache._class, "disconnect_all", autospec=True
+        ) as mock_disconnect:
+            signals.request_finished.send(self.__class__)
+            self.assertIs(mock_disconnect.called, self.should_disconnect_on_close)
 
     def test_set_many_returns_failing_keys(self):
         def fail_set_multi(mapping, *args, **kwargs):

tests/handlers/tests.py

@@ -1,7 +1,7 @@
 from django.core.exceptions import ImproperlyConfigured
 from django.core.handlers.wsgi import WSGIHandler, WSGIRequest, get_script_name
 from django.core.signals import request_finished, request_started
-from django.db import close_old_connections, connection
+from django.db import connection
 from django.test import (
     AsyncRequestFactory,
     RequestFactory,
@@ -14,10 +14,6 @@ from django.test import (
 class HandlerTests(SimpleTestCase):
     request_factory = RequestFactory()
 
-    def setUp(self):
-        request_started.disconnect(close_old_connections)
-        self.addCleanup(request_started.connect, close_old_connections)
-
     def test_middleware_initialized(self):
         handler = WSGIHandler()
         self.assertIsNotNone(handler._middleware_chain)

tests/httpwrappers/tests.py

@@ -7,8 +7,6 @@ import uuid
 
 from django.core.exceptions import DisallowedRedirect
 from django.core.serializers.json import DjangoJSONEncoder
-from django.core.signals import request_finished
-from django.db import close_old_connections
 from django.http import (
     BadHeaderError,
     HttpResponse,
@@ -758,12 +756,6 @@ class StreamingHttpResponseTests(SimpleTestCase):
 
 
 class FileCloseTests(SimpleTestCase):
-    def setUp(self):
-        # Disable the request_finished signal during this test
-        # to avoid interfering with the database connection.
-        request_finished.disconnect(close_old_connections)
-        self.addCleanup(request_finished.connect, close_old_connections)
-
     def test_response(self):
         filename = os.path.join(os.path.dirname(__file__), "abc.txt")
 

tests/wsgi/tests.py

@@ -1,8 +1,6 @@
 from django.core.exceptions import ImproperlyConfigured
 from django.core.servers.basehttp import get_internal_wsgi_application
-from django.core.signals import request_started
 from django.core.wsgi import get_wsgi_application
-from django.db import close_old_connections
 from django.http import FileResponse
 from django.test import SimpleTestCase, override_settings
 from django.test.client import RequestFactory
@@ -12,10 +10,6 @@ from django.test.client import RequestFactory
 class WSGITest(SimpleTestCase):
     request_factory = RequestFactory()
 
-    def setUp(self):
-        request_started.disconnect(close_old_connections)
-        self.addCleanup(request_started.connect, close_old_connections)
-
     def test_get_wsgi_application(self):
         """
         get_wsgi_application() returns a functioning WSGI callable.