osu.Framework.Platform.SDL3.SDL3Exception: Invalid pen instance ID (at SDL_GetPenDeviceType(evtPenProximity.which))

[ppy-sentryintegration]

Sentry Issue: OSU-3SP4

cc @Susko3

osu.Framework.Platform.SDL3.SDL3Exception: Invalid pen instance ID (at SDL_GetPenDeviceType(evtPenProximity.which))
  ?, in SDL_PenDeviceType SDL3Extensions.ThrowIfFailed(SDL_PenDeviceType returnValue, string expression)
  ?, in void SDL3Window.handlePenProximityEvent(SDL_PenProximityEvent evtPenProximity)
  ?, in void SDL3Window.HandleEvent(SDL_Event e)
  ?, in void SDL3Window.RunMainLoop()
  ?, in void SDL3Window.Run()
...
(2 additional frame(s) were not displayed)

An unhandled error has occurred.

[bdach]

see also: https://osu.ppy.sh/community/forums/topics/2204060?n=1

[Susko3]

Looking at Sentry, the crashes don't always have the same total number of pen events: some have as low as 1 successfully handled event, others up to 400k. It's likely timing-related. Sentry also shows the same users hitting the crash multiple times, and on various screens (song select, solo player). The crashes only happen on Windows.

I can't reproduce the crash with my limited testing.

I looked at the SDL3 code: both generic pen & windows events, and I can't figure out code path that would cause an invalid/removed pen ID being in an event.

As for fixing this, the pen type is always SDL_PEN_DEVICE_TYPE_UNKNOWN on Windows, so we could hard-code that instead of querying SDL_GetPenDeviceType(). I'm not too happy with that, but it fixes the problem and signals "stuff is broken" to the person looking at the code.

[bdach]

I'd suggest we drop down the throw to a log-and-return-unknown-on-error to stop users crashing.

[Susko3]

I assume that broken events with invalid pen IDs appear sporadically, in-between events that have valid pen IDs.

The solution you mention seems fine on first glance, but if the unknown fallback gets hit on platforms that support pen types, it can lead to weird input issues that will be hard to diagnose for players. Pen events are converted to touch or mouse depending on the pen type, and we don't support mixing those two playstyles. I don't know what happens when you interleave mouse and touch events in osu! gameplay, but I could imagine that an input gets dropped and the player misses a circle. The player thinks they're bad, but in fact, the game is bugged. It's better for the game to crash so we can fix the issue.

[bdach]

Apparently this still occurs on linux. See ppy/osu#38791.

[Hoopsier]

May we please 🙏 get the temporary fix on Linux side too?

---

The crash happens in ranked play as well, and you already know that is not good. I am not sure if it specifically breaks something for linux, making that call return enum.Unknown, so if it does then I guess I have more to learn.

[Susko3]

Upstream fixed the problem in libsdl-org/SDL@9780425. It requires changes on our side to incorporate it.

@Hoopsier the fix will trickle down to osu! in due time.