Fixed #30323 -- Fixed detecting changes by autoreloader when using StatReloader.

django/utils/autoreload.py

@@ -324,41 +324,33 @@ class StatReloader(BaseReloader):
     SLEEP_TIME = 1  # Check for changes once per second.
 
     def tick(self):
-        state, previous_timestamp = {}, time.time()
+        mtimes = {}
         while True:
-            state.update(self.loop_files(state, previous_timestamp))
-            previous_timestamp = time.time()
+            for filepath, mtime in self.snapshot_files():
+                old_time = mtimes.get(filepath)
+                if old_time is None:
+                    logger.debug('File %s first seen with mtime %s', filepath, mtime)
+                    mtimes[filepath] = mtime
+                    continue
+                elif mtime > old_time:
+                    logger.debug('File %s previous mtime: %s, current mtime: %s', filepath, old_time, mtime)
+                    self.notify_file_changed(filepath)
+
             time.sleep(self.SLEEP_TIME)
             yield
 
-    def loop_files(self, previous_times, previous_timestamp):
-        updated_times = {}
-        for path, mtime in self.snapshot_files():
-            previous_time = previous_times.get(path)
-            # If there are overlapping globs, a file may be iterated twice.
-            if path in updated_times:
-                continue
-            # A new file has been detected. This could happen due to it being
-            # imported at runtime and only being polled now, or because the
-            # file was just created. Compare the file's mtime to the
-            # previous_timestamp and send a notification if it was created
-            # since the last poll.
-            is_newly_created = previous_time is None and mtime > previous_timestamp
-            is_changed = previous_time is not None and previous_time != mtime
-            if is_newly_created or is_changed:
-                logger.debug('File %s. is_changed: %s, is_new: %s', path, is_changed, is_newly_created)
-                logger.debug('File %s previous mtime: %s, current mtime: %s', path, previous_time, mtime)
-                self.notify_file_changed(path)
-                updated_times[path] = mtime
-        return updated_times
-
     def snapshot_files(self):
+        # watched_files may produce duplicate paths if globs overlap.
+        seen_files = set()
         for file in self.watched_files():
+            if file in seen_files:
+                continue
             try:
                 mtime = file.stat().st_mtime
             except OSError:
                 # This is thrown when the file does not exist.
                 continue
+            seen_files.add(file)
             yield file, mtime
 
     @classmethod
@@ -564,7 +556,7 @@ def start_django(reloader, main_func, *args, **kwargs):
     ensure_echo_on()
 
     main_func = check_errors(main_func)
-    django_main_thread = threading.Thread(target=main_func, args=args, kwargs=kwargs)
+    django_main_thread = threading.Thread(target=main_func, args=args, kwargs=kwargs, name='django-main-thread')
     django_main_thread.setDaemon(True)
     django_main_thread.start()
 

docs/releases/2.2.1.txt

@@ -67,3 +67,6 @@ Bugfixes
 
 * Fixed a regression in Django 2.2 that caused a crash of :djadmin:`runserver`
   when URLConf modules raised exceptions (:ticket:`30323`).
+
+* Fixed a regression in Django 2.2 where changes were not reliably detected by
+  auto-reloader when using ``StatReloader`` (:ticket:`30323`).

tests/utils_tests/test_autoreload.py

@@ -255,7 +255,7 @@ class StartDjangoTests(SimpleTestCase):
         self.assertEqual(mocked_thread.call_count, 1)
         self.assertEqual(
             mocked_thread.call_args[1],
-            {'target': fake_main_func, 'args': (123,), 'kwargs': {'abc': 123}}
+            {'target': fake_main_func, 'args': (123,), 'kwargs': {'abc': 123}, 'name': 'django-main-thread'}
         )
         self.assertSequenceEqual(fake_thread.setDaemon.call_args[0], [True])
         self.assertTrue(fake_thread.start.called)
@@ -376,26 +376,6 @@ class IntegrationTests:
         self.assertEqual(notify_mock.call_count, 1)
         self.assertCountEqual(notify_mock.call_args[0], [self.existing_file])
 
-    @mock.patch('django.utils.autoreload.BaseReloader.notify_file_changed')
-    @mock.patch('django.utils.autoreload.iter_all_python_module_files', return_value=frozenset())
-    def test_nonexistent_file(self, mocked_modules, notify_mock):
-        self.reloader.watch_file(self.nonexistent_file)
-        with self.tick_twice():
-            self.ensure_file(self.nonexistent_file)
-        self.assertEqual(notify_mock.call_count, 1)
-        self.assertCountEqual(notify_mock.call_args[0], [self.nonexistent_file])
-
-    @mock.patch('django.utils.autoreload.BaseReloader.notify_file_changed')
-    @mock.patch('django.utils.autoreload.iter_all_python_module_files', return_value=frozenset())
-    def test_nonexistent_file_in_non_existing_directory(self, mocked_modules, notify_mock):
-        non_existing_directory = self.tempdir / 'non_existing_dir'
-        nonexistent_file = non_existing_directory / 'test'
-        self.reloader.watch_file(nonexistent_file)
-        with self.tick_twice():
-            self.ensure_file(nonexistent_file)
-        self.assertEqual(notify_mock.call_count, 1)
-        self.assertCountEqual(notify_mock.call_args[0], [nonexistent_file])
-
     @mock.patch('django.utils.autoreload.BaseReloader.notify_file_changed')
     @mock.patch('django.utils.autoreload.iter_all_python_module_files', return_value=frozenset())
     def test_glob(self, mocked_modules, notify_mock):
@@ -407,18 +387,6 @@ class IntegrationTests:
         self.assertEqual(notify_mock.call_count, 1)
         self.assertCountEqual(notify_mock.call_args[0], [self.existing_file])
 
-    @mock.patch('django.utils.autoreload.BaseReloader.notify_file_changed')
-    @mock.patch('django.utils.autoreload.iter_all_python_module_files', return_value=frozenset())
-    def test_glob_non_existing_directory(self, mocked_modules, notify_mock):
-        non_existing_directory = self.tempdir / 'does_not_exist'
-        nonexistent_file = non_existing_directory / 'test.py'
-        self.reloader.watch_dir(non_existing_directory, '*.py')
-        with self.tick_twice():
-            self.ensure_file(nonexistent_file)
-            self.set_mtime(nonexistent_file, time.time())
-        self.assertEqual(notify_mock.call_count, 1)
-        self.assertCountEqual(notify_mock.call_args[0], [nonexistent_file])
-
     @mock.patch('django.utils.autoreload.BaseReloader.notify_file_changed')
     @mock.patch('django.utils.autoreload.iter_all_python_module_files', return_value=frozenset())
     def test_multiple_globs(self, mocked_modules, notify_mock):
@@ -669,28 +637,8 @@ class StatReloaderTests(ReloaderTests, IntegrationTests):
             snapshot2 = dict(self.reloader.snapshot_files())
             self.assertNotEqual(snapshot1[self.existing_file], snapshot2[self.existing_file])
 
-    def test_does_not_fire_without_changes(self):
-        with mock.patch.object(self.reloader, 'watched_files', return_value=[self.existing_file]), \
-                mock.patch.object(self.reloader, 'notify_file_changed') as notifier:
-            mtime = self.existing_file.stat().st_mtime
-            initial_snapshot = {self.existing_file: mtime}
-            second_snapshot = self.reloader.loop_files(initial_snapshot, time.time())
-            self.assertEqual(second_snapshot, {})
-            notifier.assert_not_called()
-
-    def test_fires_when_created(self):
-        with mock.patch.object(self.reloader, 'watched_files', return_value=[self.nonexistent_file]), \
-                mock.patch.object(self.reloader, 'notify_file_changed') as notifier:
-            self.nonexistent_file.touch()
-            mtime = self.nonexistent_file.stat().st_mtime
-            second_snapshot = self.reloader.loop_files({}, mtime - 1)
-            self.assertCountEqual(second_snapshot.keys(), [self.nonexistent_file])
-            notifier.assert_called_once_with(self.nonexistent_file)
-
-    def test_fires_with_changes(self):
-        with mock.patch.object(self.reloader, 'watched_files', return_value=[self.existing_file]), \
-                mock.patch.object(self.reloader, 'notify_file_changed') as notifier:
-            initial_snapshot = {self.existing_file: 1}
-            second_snapshot = self.reloader.loop_files(initial_snapshot, time.time())
-            notifier.assert_called_once_with(self.existing_file)
-            self.assertCountEqual(second_snapshot.keys(), [self.existing_file])
+    def test_snapshot_files_with_duplicates(self):
+        with mock.patch.object(self.reloader, 'watched_files', return_value=[self.existing_file, self.existing_file]):
+            snapshot = list(self.reloader.snapshot_files())
+            self.assertEqual(len(snapshot), 1)
+            self.assertEqual(snapshot[0][0], self.existing_file)