fix: deduplicate scheduled tasks before enqueue

tubesync/common/models/tasks.py

@@ -1,6 +1,6 @@
 import uuid
 from datetime import timedelta
-from itertools import islice
+from itertools import chain, islice
 
 from django.db import connection, models, transaction
 from django.utils import timezone
@@ -27,6 +27,18 @@ def th_schedule(cls, task_wrapper, /, *args, remove_duplicates=False, vn_args=()
     if not ('delay' in kwargs or 'eta' in kwargs):
         kwargs['delay'] = task_wrapper.settings.get('delay') or int()
     task_obj = task_wrapper.s(*args, **kwargs)
+    if remove_duplicates:
+        waiting_tasks = chain(
+            task_wrapper.huey.pending(),
+            task_wrapper.huey.scheduled(),
+        )
+        duplicate_exists = any(
+            existing.name == task_obj.name and
+            existing.data == task_obj.data
+            for existing in waiting_tasks
+        )
+        if duplicate_exists:
+            return False
     task_id = str(task_obj.id)
     scheduled_at = task_wrapper.huey.scheduled_at_from_task(task_obj)
     if scheduled_at:

tubesync/common/tests.py

@@ -1,9 +1,12 @@
 import os.path
+from types import SimpleNamespace
+from unittest.mock import Mock
 from django.conf import settings
 from django.test import TestCase, Client
 from .testutils import prevent_request_warnings
 from .utils import parse_database_connection_string, clean_filename
 from .errors import DatabaseConnectionError
+from .models.tasks import th_schedule
 
 
 class ErrorPageTestCase(TestCase):
@@ -142,3 +145,79 @@ class UtilsTestCase(TestCase):
         self.assertEqual(clean_filename('a  a'), 'a  a')
         self.assertEqual(clean_filename('a\t\t\ta'), 'a   a')
         self.assertEqual(clean_filename('a\t\t\ta\t\t\t'), 'a   a')
+
+
+class TaskHistoryScheduleTestCase(TestCase):
+
+    def make_schedule_objects(self, pending=(), scheduled=()):
+        task = SimpleNamespace(
+            id='00000000-0000-0000-0000-000000000001',
+            __module__='sync.tasks',
+            name='download_media_metadata',
+            priority=60,
+            args=('media-id',),
+            kwargs={},
+            data=(('media-id',), {}),
+        )
+        huey = SimpleNamespace(
+            name='limited',
+            pending=Mock(return_value=list(pending)),
+            scheduled=Mock(return_value=list(scheduled)),
+            scheduled_at_from_task=Mock(return_value=None),
+            enqueue=Mock(),
+        )
+        wrapper = SimpleNamespace(
+            huey=huey,
+            settings={'delay': 60},
+            s=Mock(return_value=task),
+        )
+        objects = SimpleNamespace(update_or_create=Mock())
+        cls = SimpleNamespace(objects=objects)
+        return cls, wrapper, task
+
+    def test_remove_duplicates_skips_pending_duplicate(self):
+        existing = SimpleNamespace(
+            name='download_media_metadata',
+            data=(('media-id',), {}),
+        )
+        cls, wrapper, _ = self.make_schedule_objects(pending=(existing,))
+
+        result = th_schedule(
+            cls, wrapper, 'media-id',
+            remove_duplicates=True,
+            vn_fmt='metadata {}', vn_args=('media-id',),
+        )
+
+        self.assertFalse(result)
+        cls.objects.update_or_create.assert_not_called()
+        wrapper.huey.enqueue.assert_not_called()
+
+    def test_remove_duplicates_skips_scheduled_duplicate(self):
+        existing = SimpleNamespace(
+            name='download_media_metadata',
+            data=(('media-id',), {}),
+        )
+        cls, wrapper, _ = self.make_schedule_objects(scheduled=(existing,))
+
+        result = th_schedule(
+            cls, wrapper, 'media-id',
+            remove_duplicates=True,
+            vn_fmt='metadata {}', vn_args=('media-id',),
+        )
+
+        self.assertFalse(result)
+        cls.objects.update_or_create.assert_not_called()
+        wrapper.huey.enqueue.assert_not_called()
+
+    def test_remove_duplicates_enqueues_when_no_duplicate_exists(self):
+        cls, wrapper, task = self.make_schedule_objects()
+
+        result = th_schedule(
+            cls, wrapper, 'media-id',
+            remove_duplicates=True,
+            vn_fmt='metadata {}', vn_args=('media-id',),
+        )
+
+        self.assertTrue(result)
+        cls.objects.update_or_create.assert_called_once()
+        wrapper.huey.enqueue.assert_called_once_with(task)