GeezerVison

See #9667 which this is intended to fix.

I'm going to hold off on the default location change for now and merge the config for both 10.0 and 10.1.

I like the new default but it's a pretty visible change that should probably bake in jruby-head for a while (and I don't think it should be backported to 10.0).

This now contains just the default location change (to $HOME/.cache), with the configurable JSA home merged from #9698. Will merge after 10.1.2.0 and let it bake in jruby-head for a bit.

I wonder if it's best to assume $HOME/.cache exists here. Other platforms like Mac have a different path for such data, and depending on the host, the operator might have defined it otherwise using the XDG_CACHE_HOME environment variable.

Well, that is a fair point, but is it worse than assuming the JRuby install location is writable? I'm trying to find a better option that allows users to get the benefit of the JSA file without requiring that.

Presumably this is also why the Debian package defaults to .cache. I want to reduce the amount of third-party patching required to maintain JRuby packages.

FWIW on my MacOS machine I do have a .cache directory, containing several Ruby-related items and a few from packages I've installed with Homebrew:

$ ls -1 ~/.cache                    
bashbrew
codex-runtimes
gem
install4j
javasharedresources
jruby
opencode
rbs
rubocop_cache
ruby-install
uv
vllm

Interestingly, the javasharedresources directory is put there by IBM's OpenJ9 JVM (Semeru) as a place to store that JVM's equivalent of AppCDS JSA files:

eclipse-openj9/openj9#2862

I'd still like this to go somewhere outside of the JRuby install. The .cache dir still seems like the best choice, but I'd like more input. Try to do this a good while before 10.2 so it can settle.