Meta: Remove version.txt for downloaded files, and version cache dirs

[ADKaster]

@nico is this kind of what you were thinking for train-worthy bisecting?

One thing that I think is missing for this solution to work for that use case is that the old strategy would blast the entire subdirectory if the version mismatches... So perhaps we should download all the raw files/zips/tar.gz files to a caches/downloads/ folder or some such?

[trflynn89]

Fly-by opinion - I'd rather default to removing old versions when a new version is picked up. Optimizing for bad-train-internet bisecting isn't a strong argument IMO, we have the ability to turn off network downloads for that case. Or at least make it opt-in behavior to keep the old versions.

This also affects CI as we'll keep old versions in the actions cache in perpetuity.

[nico]

Fly-by opinion - I'd rather default to removing old versions when a new version is picked up.

Can you say more on why? The files in my Build/caches are all small (my Build/caches is 287 MB, while Build/x86_64 is 2.85 GB) and most of them change relatively rarely.

[trflynn89]

I'd just rather not have caches laying around that we don't need. Most of it (~220MB) is the CLDR which releases 2-3 times a year, it doesn't make sense to me to default to keeping those around.

Plus, the caches on CI are a prominent issue, and we need to keep their sizes in check. We can certainly figure out how to blow those caches away when we update versions. But again, I'm not convinced that bisecting on a train is a good reason to do that, vs. adding an opt-in option to keep old caches around.

[nico]

We could delete the files when they're N weeks old or something.

Don't focus on the 'on a train' part too much – just bisecting across these is annoying, no?

[trflynn89]

I can only recall bisecting across an update once, but I didn't find it particularly annoying or really even noticeable. Certainly not enough to default to keeping the old downloads around or implement some other cache invalidation.

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This pull request has been automatically marked as stale because it has not had recent activity. It will be closed in 7 days if no further activity occurs. Thank you for your contributions!

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This pull request has been closed because it has not had recent activity. Feel free to re-open if you wish to still contribute these changes. Thank you for your contributions!