Cursor locked in place when loading an Age on macOS.

[Hoikas]

When loading a new Age's reosurces from disk on macOS, the cursor is locked in place and cannot move. This makes it difficult to control the system while linking. That's especially annoying on slow Macs. On Windows, the cursor is free to move during this process.

[colincornaby]

I'm going to summarize the discussion about the bug that has been had ad hoc. Analysis was done on a 2014 Mac Mini matching the configuration that @Hoikas used.

It looks like during load - on slower Macs - Plasma is taking up the entire main run loop and not letting the system provide events. It's possible we need to do something on our side to forcibly flush events out of the event queue between draws.

Instruments can also trace the problem.

The red sections are where the system has decided our process is no longer responding because the main run loop is being monopolized by Plasma. Those red sections match up with segments spent loading.

I'm going to assign this issue to myself, although I know @dpogue has been watching it as well. It looks like there were similar issues on Windows at one point so if @dpogue has any insights from that feel free to grab this issue.

[colincornaby]

I've been looking more at this in the background. I did verify that the mouse events are never being received because the main thread is blocked. There are a few possible solutions:

• Plasma game loop gets moved to a secondary thread. This is Apple's preferred outcome - but would be the most disruptive. The main thread wouldn't be blocked, so we'd always get input events and decide how to feed them in. Plasma shouldn't care that it's in a secondary thread. The initial version of the Mac client did this, but it required more locking from within the client to avoid data races when talking to the engine.
• I can also purposely pad the time between frames. Apple also has guidance on how to do this. I'd need to keep a running average of how long the game loop is taking. The display timer lets me set a minimum time a frame has to reman on screen. I can set that value to avoid it calling the game loop more than X times a second. That would come with some amount of frame rate degradation on slow Macs (but hopefully not too much) and still has the chance some events could get missed.

[Hoikas]

Windows has similar logic, but the threshold for considering the app to be crashed is a lot higher - as in you have to not service the event loop for multiple seconds. It's unfortunate that macOS is more aggressive in this respect, but what can you do?

I'm of the opinion that it makes more sense to go with method 1 for the mac client. We most of the information that we need to process from the OS event loop should just be messages that we send into Plasma. The code already exists for those to be sent from a different thread, AFAIK. The intro videos are probably the only place that expect to take ownership of the message pump loop, so that will need some attention. Aside from that, all as long as Plasma can have its own "main thread" - regardless of whether or not it's actually the main thread - we should be fine. The important part is sending OS events through the established Plasma message system in a threadsafe way.