Remove dedicated task signals

The global ones can be used, and restored later if needed. The implementation is a bit of a bodge

README.md

@@ -240,12 +240,6 @@ Whilst signals are available, they may not be the most maintainable approach.
 - `django_tasks.signals.task_enqueued`: Called when a task is enqueued. The sender is the backend class. Also called with the enqueued `task_result`.
 - `django_tasks.signals.task_finished`: Called when a task finishes (`COMPLETE` or `FAILED`). The sender is the backend class. Also called with the finished `task_result`.
 
-Additionally, each `Task` has its own signals. These signals are only sent for the given `Task`, whilst the above will be called for all `Task`s.
-
-- `Task.finished`: Called when the task finishes (`COMPLETE` or `FAILED`). There is no sender (`None`), however the handler is called with the finished `task_result`.
-
-Tasks which are modified by `.using` have the same signal.
-
 ## Contributing
 
 See [CONTRIBUTING.md](./CONTRIBUTING.md) for information on how to contribute.

django_tasks/backends/database/management/commands/db_worker.py

@@ -134,7 +134,6 @@ def run_task(self, db_task_result: DBTaskResult) -> None:
             # Setting the return and success value inside the error handling,
             # So errors setting it (eg JSON encode) can still be recorded
             db_task_result.set_complete(return_value)
-            task_result.task.finished.send(sender=None, task_result=task_result)
             task_finished.send(
                 sender=type(task.get_backend()), task_result=db_task_result.task_result
             )
@@ -146,7 +145,6 @@ def run_task(self, db_task_result: DBTaskResult) -> None:
             except (ModuleNotFoundError, SuspiciousOperation):
                 logger.exception("Task id=%s failed unexpectedly", db_task_result.id)
             else:
-                task_result.task.finished.send(sender=None, task_result=task_result)
                 task_finished.send(
                     sender=sender,
                     task_result=task_result,

django_tasks/backends/immediate.py

@@ -60,13 +60,11 @@ def _execute_task(self, task_result: TaskResult) -> None:
 
             object.__setattr__(task_result, "status", ResultStatus.FAILED)
 
-            task_result.task.finished.send(sender=None, task_result=task_result)
             task_finished.send(type(self), task_result=task_result)
         else:
             object.__setattr__(task_result, "finished_at", timezone.now())
             object.__setattr__(task_result, "status", ResultStatus.COMPLETE)
 
-            task_result.task.finished.send(sender=None, task_result=task_result)
             task_finished.send(type(self), task_result=task_result)
 
     def enqueue(

django_tasks/task.py

@@ -1,6 +1,5 @@
 from dataclasses import dataclass, field, replace
 from datetime import datetime, timedelta
-from functools import lru_cache
 from inspect import iscoroutinefunction
 from typing import (
     TYPE_CHECKING,
@@ -17,7 +16,6 @@
 
 from asgiref.sync import async_to_sync, sync_to_async
 from django.db.models.enums import TextChoices
-from django.dispatch import Signal
 from django.utils import timezone
 from django.utils.functional import cached_property
 from django.utils.module_loading import import_string
@@ -56,17 +54,6 @@ class ResultStatus(TextChoices):
     COMPLETE = ("COMPLETE", _("Complete"))
 
 
-# Use a large number to ensure `lru_cache` still uses a lock
-@lru_cache(maxsize=100000)
-def _get_task_signal(task: "Task", name: str) -> Signal:
-    """
-    Allow a Task to have a signal, without storing it on the task itself.
-
-    This allows the Task to still be hashable, picklable and deepcopyable.
-    """
-    return Signal()
-
-
 T = TypeVar("T")
 P = ParamSpec("P")
 
@@ -198,11 +185,6 @@ def is_modified(self) -> bool:
         """
         return self != self.original
 
-    @property
-    def finished(self) -> Signal:
-        """A signal, fired when the task finished"""
-        return _get_task_signal(self.original, "finished")
-
 
 # Bare decorator usage
 # e.g. @task

tests/tests/test_tasks.py

@@ -1,8 +1,6 @@
 import dataclasses
-from copy import deepcopy
 from datetime import datetime, timedelta
 
-from django.dispatch import Signal
 from django.test import SimpleTestCase, override_settings
 from django.utils import timezone
 from django.utils.module_loading import import_string
@@ -259,16 +257,3 @@ def test_original(self) -> None:
     def test_is_modified(self) -> None:
         self.assertFalse(test_tasks.noop_task.is_modified)
         self.assertTrue(test_tasks.noop_task.using(priority=10).is_modified)
-
-    def test_finished_signal(self) -> None:
-        self.assertIsInstance(test_tasks.noop_task.finished, Signal)
-        self.assertIs(
-            test_tasks.noop_task.using().finished, test_tasks.noop_task.finished
-        )
-        self.assertIs(
-            test_tasks.noop_task.using(priority=10).finished,
-            test_tasks.noop_task.finished,
-        )
-        self.assertIs(
-            deepcopy(test_tasks.noop_task).finished, test_tasks.noop_task.finished
-        )