GUIDs are not generated for SessionGameId

[roydejong]

Background

When gameplay starts, normally a GUID is generated for each gameplay session.

The server usually sends this in SetGameplaySceneSyncFinishedRpc or SetPlayerDidConnectLateRpc.

Problem

BeatUpServer doesn't seem to do this, instead returning an empty GUID (00000000-0000-0000-0000-000000000000).

https://github.com/rcelyte/BeatUpRcelyte/blob/4f110ee5feae4bf4d5c1c4523df141ca66ab4844/src/instance/instance.c#L452

Unfortunately this breaks the Server Browser's ability to track individual gameplay sessions.

[rcelyte]

Would it be fine to just have GUIDs count up from zero, or do they need to remain unique across server restarts?

[roydejong]

It would be better if it was globally unique, so if there's another instance of BeatUpServer their session IDs don't overlap.

For context, each GUID is supposed to uniquely reflect a single gameplay session and their results, for example: https://bssb.app/results/9e1efb8a-1b53-4526-ab5e-8c3aa39911ed

If you're able to do the equivalent of Guid.NewGuid that would be perfect.

[rcelyte]

I can't really enforce globally unique IDs across different instances (including vanilla & BeatTogether). It would be much more reliable to additionally index them by master server hostname/address.

[roydejong]

I understand you can't 100% guarantee or enforce that, but the point of a randomly generated GUID is that the chance of overlap is effectively zero.

For context:

[..] the number of random version-4 UUIDs which need to be generated in order to have a 50% probability of at least one collision is 2.71 quintillion [..]

With an implementation that counts up, overlap is guaranteed and more likely to cause eventual conflicts even if I do index it by server address (example: if the server resets its counter).

It's a well accepted practice to treat randomly generated GUIDs as unique, and I think that's the most appropriate solution here.