Refs #35859 -- Removed support for Task enqueuing on transaction commit.

This removes the ability to configure Task enqueueing via a setting,
since the proposed `ENQUEUE_ON_COMMIT` did not support multi-database
setups.

Thanks to Simon Charette for the report.

Follow-up to 4289966d1b8e848e5e460b7c782dac009d746b20.

4 files changed, 3 insertions, 45 deletions

diff --git a/django/tasks/backends/base.py b/django/tasks/backends/base.py
index 32ae10018d..938e36f21e 100644
--- a/django/tasks/backends/base.py
+++ b/django/tasks/backends/base.py
@@ -4,8 +4,6 @@ from inspect import iscoroutinefunction
 from asgiref.sync import sync_to_async
 
 from django.conf import settings
-from django.core import checks
-from django.db import connections
 from django.tasks import DEFAULT_TASK_QUEUE_NAME
 from django.tasks.base import (
     DEFAULT_TASK_PRIORITY,
@@ -39,16 +37,8 @@ class BaseTaskBackend(metaclass=ABCMeta):
     def __init__(self, alias, params):
         self.alias = alias
         self.queues = set(params.get("QUEUES", [DEFAULT_TASK_QUEUE_NAME]))
-        self.enqueue_on_commit = bool(params.get("ENQUEUE_ON_COMMIT", True))
         self.options = params.get("OPTIONS", {})
 
-    def _get_enqueue_on_commit_for_task(self, task):
-        return (
-            task.enqueue_on_commit
-            if task.enqueue_on_commit is not None
-            else self.enqueue_on_commit
-        )
-
     def validate_task(self, task):
         """
         Determine whether the provided Task can be executed by the backend.
@@ -119,20 +109,4 @@ class BaseTaskBackend(metaclass=ABCMeta):
         )
 
     def check(self, **kwargs):
-        if self.enqueue_on_commit and not connections._settings:
-            yield checks.Error(
-                "ENQUEUE_ON_COMMIT cannot be used when no databases are configured.",
-                hint="Set ENQUEUE_ON_COMMIT to False",
-                id="tasks.E001",
-            )
-
-        elif (
-            self.enqueue_on_commit
-            and not connections["default"].features.supports_transactions
-        ):
-            yield checks.Error(
-                "ENQUEUE_ON_COMMIT cannot be used on a database which doesn't support "
-                "transactions.",
-                hint="Set ENQUEUE_ON_COMMIT to False",
-                id="tasks.E002",
-            )
+        return []
diff --git a/django/tasks/backends/dummy.py b/django/tasks/backends/dummy.py
index 93bb8f3ee4..bc7060ccc4 100644
--- a/django/tasks/backends/dummy.py
+++ b/django/tasks/backends/dummy.py
@@ -1,7 +1,5 @@
 from copy import deepcopy
-from functools import partial
 
-from django.db import transaction
 from django.tasks.base import TaskResult, TaskResultStatus
 from django.tasks.exceptions import TaskResultDoesNotExist
 from django.tasks.signals import task_enqueued
@@ -43,10 +41,7 @@ class DummyBackend(BaseTaskBackend):
             worker_ids=[],
         )
 
-        if self._get_enqueue_on_commit_for_task(task) is not False:
-            transaction.on_commit(partial(self._store_result, result))
-        else:
-            self._store_result(result)
+        self._store_result(result)
 
         # Copy the task to prevent mutation issues.
         return deepcopy(result)
diff --git a/django/tasks/backends/immediate.py b/django/tasks/backends/immediate.py
index 06b94d18ab..2e154850aa 100644
--- a/django/tasks/backends/immediate.py
+++ b/django/tasks/backends/immediate.py
@@ -1,8 +1,6 @@
 import logging
-from functools import partial
 from traceback import format_exception
 
-from django.db import transaction
 from django.tasks.base import TaskContext, TaskError, TaskResult, TaskResultStatus
 from django.tasks.signals import task_enqueued, task_finished, task_started
 from django.utils import timezone
@@ -92,9 +90,6 @@ class ImmediateBackend(BaseTaskBackend):
             worker_ids=[],
         )
 
-        if self._get_enqueue_on_commit_for_task(task) is not False:
-            transaction.on_commit(partial(self._execute_task, task_result))
-        else:
-            self._execute_task(task_result)
+        self._execute_task(task_result)
 
         return task_result
diff --git a/django/tasks/base.py b/django/tasks/base.py
index 905dbef597..cffcdd8996 100644
--- a/django/tasks/base.py
+++ b/django/tasks/base.py
@@ -48,10 +48,6 @@ class Task:
     queue_name: str
     run_after: Optional[datetime]  # The earliest this Task will run.
 
-    # Whether the Task will be enqueued when the current transaction commits,
-    # immediately, or whatever the backend decides.
-    enqueue_on_commit: Optional[bool]
-
     # Whether the Task receives the Task context when executed.
     takes_context: bool = False
 
@@ -140,7 +136,6 @@ def task(
     priority=DEFAULT_TASK_PRIORITY,
     queue_name=DEFAULT_TASK_QUEUE_NAME,
     backend=DEFAULT_TASK_BACKEND_ALIAS,
-    enqueue_on_commit=None,
     takes_context=False,
 ):
     from . import task_backends
@@ -151,7 +146,6 @@ def task(
             func=f,
             queue_name=queue_name,
             backend=backend,
-            enqueue_on_commit=enqueue_on_commit,
             takes_context=takes_context,
             run_after=None,
         )