Async save/load support

[krojew]

The documentation for USpudSubsystem::SaveGame() says it's asynchronous, but it's not in reality. All the saving, especially calls to USpudState::SaveToArchive() happen on the game thread. This might be an issue for bigger states, especially on consoles where certification prohibits long stalls. It would be great to have proper async save support.

[ac-branislav]

I implemented this already but I'm waiting on the slow path fix, so once that is sorted out I can upgrade our plugin to the latest version and than push the changes for async saving into here since I needed it for PS5. @sinbad do you have any updates on the slow path fix?

[sinbad]

Sorry, I've had an absolute nightmare 12 months due to my mother's worsening dementia and recent death so I've had no time to look at this. Our current game doesn't need SPUD (no level state) so I'm not in the codebase during the day job and I've been wiped out outside of that. Things should settle down a bit soon I hope.

[cyphusx]

Really sorry to hear that, @sinbad, I think we can probably all agree that family comes first.

@ac-branislav the PR for the slow fix is pretty much good to go, the only bit that's missing is the part I commented on (I believe it was a missing version check). We've fixed and deployed that in our game, and it's working well.

We are also working on an async save, however we've taken the approach of adding a "save to archive" method to the subsystem, which then gives us the freedom to then persist that to disk however we wish.

[ac-branislav]

That's good to hear, still waiting for the official merge into main branch for us for me to pick it up.

I think the more options for saving the better since supporting sync and async is good idea for different situations

[sinbad]

I fixed up the slow path PR (now #143) so it doesn't break old saves anymore and merged it. Feel free to follow on as you see fit!

[krojew]

@ac-branislav will you make a PR for this?

[ac-branislav]

I will upgrade our plugin on monday and than I can try and push this back, the question is whether we want to have a flag whether to choose async or not async when saving, since currently on my side the save is completely async (I'm going to assume we want to be able to choose @sinbad )

[krojew]

@ac-branislav you can also introduce async versions of save/load functions.

[ac-branislav]

Ok let me take a look next week and see what makes most sense

[sinbad]

Yep I'd say Async suffixed functions would be the way to go.

[ac-branislav]

I looked at adding SaveGameAsync function but it feels like its going to be easier to add a boolean to SaveGame to say its async
because FinishSaveGame() is actually that is doing the async portion and duplicating all the code in the functions that call this is a bit much I think, I will prep a commit and than we can see if this looks good