fix: Ignore file open and read notifications in the watcher

The watchdog inotify mask includes open and close-without-write events, so
reading a watched file produces notifications. A reload reads the files, so
reacting to those notifications would make every reload trigger the next one.
The watcher now reacts only to events that can change a file's content or
presence: created, modified, moved, deleted, and closed after writing.

Author: kinyoklion

ldclient/impl/integrations/files/filedata.py

@@ -53,6 +53,10 @@
 # because it does not exist yet.
 _WATCH_RETRY_INTERVAL = 1.0
 
+# The watchdog event types that can change a file's content or presence. Opening or reading a
+# file also produces events, and a reload reads the files, so those must not count as changes.
+_CHANGE_EVENT_TYPES = frozenset(["created", "modified", "moved", "deleted", "closed"])
+
 
 class DuplicateKeysHandling(str, Enum):
     """
@@ -614,6 +618,8 @@ def _retry_pending(self) -> None:
                 self._retry_task.stop()
 
     def _handle_event(self, event) -> None:
+        if getattr(event, "event_type", None) not in _CHANGE_EVENT_TYPES:
+            return
         candidates = [getattr(event, "src_path", None), getattr(event, "dest_path", None)]
         for candidate in candidates:
             if isinstance(candidate, bytes):

ldclient/testing/integrations/test_filedata.py

@@ -860,6 +860,34 @@ def test_watcher_matches_the_destination_of_a_move_event(tmp_path, make_watcher)
     assert temp not in w.watcher._watched_paths
 
 
+@watchdog_required
+def test_watcher_ignores_events_that_do_not_change_the_file(tmp_path, make_watcher):
+    # Opening and reading a watched file produces notifications too. A reload reads the files,
+    # so reacting to those would make every reload trigger the next one.
+    import watchdog.events
+
+    path = os.path.join(str(tmp_path), 'data.json')
+    real_path = os.path.join(os.path.realpath(str(tmp_path)), 'data.json')
+    write_file(path, 'a')
+    w = make_watcher([path])
+    w.watcher._handle_event(watchdog.events.FileOpenedEvent(real_path))
+    w.watcher._handle_event(watchdog.events.FileClosedNoWriteEvent(real_path))
+    w.require_no_change()
+    w.watcher._handle_event(watchdog.events.FileClosedEvent(real_path))
+    w.require_change()
+
+
+@watchdog_required
+def test_watcher_does_not_signal_when_the_file_is_only_read(tmp_path, make_watcher):
+    path = os.path.join(str(tmp_path), 'data.json')
+    write_file(path, 'a')
+    w = make_watcher([path])
+    for _ in range(3):
+        with open(path, 'rb') as f:
+            f.read()
+    w.require_no_change()
+
+
 @watchdog_required
 def test_watcher_detects_file_deletion(tmp_path, make_watcher):
     path = os.path.join(str(tmp_path), 'data.json')