CI: Update mymindstorm/setup-emsdk to v14, should fix cache folder conflicts

[akien-mga]

https://github.com/mymindstorm/setup-emsdk/releases/tag/v14

[YuriSizov]

Oh, that's awesome!

[YuriSizov]

So this doesn't help. They simply added the workflow name as a prefix to the old naming scheme. But our CI has one entry point workflow. So both builds still have the same name for the cache:

🔗 GHA-3.1.39-linux-x64

The second-to-run build still throws an error, but for some reason it's just not caught as a problem anymore:

Failed to save: Unable to reserve cache with key 🔗 GHA-3.1.39-linux-x64, another job may be creating this cache. More details: Cache already exists. Scope: refs/pull/87575/merge, Key: 🔗 GHA-3.1.39-linux-x64, Version: bb287b8d239dae54b2b69d026bd1284e06aff2037346bb5491e7f80dd3ba6b57

So it seems we still need to do something manually to resolve this. Seems like they've added cache-key to the configuration options. We should populate it with something fitting. See here.

[YuriSizov]

Oops, I forgot this variable only contains a prefix, and we actually add more to it when creating the actual cache name. So this works, but it's still not unique enough for multiple runs:

This should match our main cache naming scheme.

Suggested change

	cache-key: ${{ matrix.cache-name }}-emsdk
	cache-key: ${{ matrix.cache-name }}-${{env.GODOT_BASE_BRANCH}}-${{github.ref}}-${{github.sha}}-emsdk

Sorry!

[akien-mga]

Thanks, changed.

Overall, I wonder why caching is so convoluted. What we'd want typically is to just cache based on the Emscripten version, and that's it. But somehow it keeps trying to recreate the cache each time it's using it, instead of just using the version that's already there?

IMO, if the cache worked as I think it should, we'd download Emscripten 3.1.39 once, and never again. All builds on all Godot branches would pull from the same cache and never need to write to it concurrently, unless we happen to bump the Emscripten version to all branches at once.

[akien-mga]

Hm should the -emsdk part come earlier in the cache key? IIRC substrings are removed from right to left to find the closest cache hit. It should maybe be emsdk-${{ matrix.cache-name }}-${{env.GODOT_BASE_BRANCH}}-${{github.ref}}-${{github.sha}} instead?

[YuriSizov]

That's a good point. I guess if it's added at the end, we can accidentally download it when trying to find cache for scons itself.

It's not that substrings are removed, we do it manually with restore-keys (and setup-emsdk doesn't, AFAICT). But we do indeed risk a collision because the first part is the same. So yeah, should probably add it somewhere earlier, or at the very start. Good catch!

[YuriSizov]

Overall, I wonder why caching is so convoluted. What we'd want typically is to just cache based on the Emscripten version, and that's it. But somehow it keeps trying to recreate the cache each time it's using it, instead of just using the version that's already there?

IMO, if the cache worked as I think it should, we'd download Emscripten 3.1.39 once, and never again. All builds on all Godot branches would pull from the same cache and never need to write to it concurrently, unless we happen to bump the Emscripten version to all branches at once.

Yes, something feels wrong about it, but I'll need to look closer into it. I also noticed that before trying to restore the cache it looks for a pre-existing folder with it, as a manual step. This suggests we may be able to cache it manually however we want. But if the override attempt happens in actions/cache, then I'm not sure how to counteract that.

[YuriSizov]

LGTM!

[YuriSizov]

Thanks!

[akien-mga]

Cherry-picked for 3.6.
Cherry-picked for 3.5.4.

[akien-mga]

Cherry-picked for 4.2.2.
Cherry-picked for 4.1.4.