InotifyObserver deals poorly with moves from/to outside the watched directory

[ericloewe]

My use case is as follows: I want to watch a directory, which is a dropbox into which directories full of files and subdirs are atomically moved (FTP use case) - I want to be notified of these directories having been moved into the watched directory, so that I can process them.

The problem is that without hacking around the top-level API, the move events are converted from MOVED_TO to CREATED (similarly, MOVED_FROM gets turned into DELETED). Inotify itself reports these as expected, as seen from the debug logs, but then this bizarre conversion happens in InotifyEmitter.queue_events, from around line 156.
Specifically, this happens when events cross the watched boundary - in other words, moves within the watched directory are reported correctly, but moves to/from outside the watched directory get mangled.

This behavior is conditional on the full_events flag, but there is no documented way of setting this flag. From what I can see, the only solution is to manually bypass the Observer() helper function by reimplementing its functionality, e.g.:

def get_observer() -> watchdog.observers.api.BaseObserver:
    """Work around Watchdog's top-level API"""
    if platform.is_linux():
        with contextlib.suppress(UnsupportedLibcError):
            from watchdog.observers.inotify import InotifyObserver

            return InotifyObserver(generate_full_events=True)

So I have two questions:

1. Is there a reasoning behind this behavior? I understand that some use cases are fine with it, but it would seem beneficial to not abstract away the distinction between a move and a create/delete.
2. Is there a reasoning for this not to be exposed in the API or docs?

[BoboTiG]

Both questions are valid, and I do not have answers right now. I'll dig into the history.

I think we could enhance the exposed API in any cases to allow setting the generate_full_events without having to deal with such low-level code.

[ericloewe]

My quick and dirty analysis is that not all Observers support these semantics. Kqueue doesn't deal with the move destination, as I understand it, so this is a complete non-starter. Polling also would seem to not allow these events to be detected. The Windows API does seem to report moves across the watch boundary, but I haven't followed the code nor tested it myself - but it doesn't seem to be propagating them to the higher levels of the API.