JRuby support

[headius]

JRuby has an impl of zlib based on a Java port of libzlib called "jzlib". We need to incorporate our version into this gem in some way (in descending order of tight integration):

• directly merge our extension
• release our own jruby-zlib gem and a zlib -java gem that avoids shipping the C ext and depends on the JRuby version
• release a -java version that does nothing on JRuby

We will put together a PR soon.

[hsbt]

👍

In my understanding, Will JRuby team ship jruby-zlib from this repo in the future?

[headius]

Revisiting this... I just realized some gems have started to depend on zlib, so we need to find a way to get JRuby's zlib support merged in.

Example: ksss/rubocop-on-rbs#101

[headius]

I'm back again! Today I'm trying to start getting RBS working on JRuby, but one of its test dependencies (rubocop-on-rbs) requires zlib.

So I think we need to make a move on this finally.

There's two options:

• Release a zlib stub gem for JRuby that does not install any loadable code. All zlib behavior will fall back on the built-in JRuby version.
• Migrate the existing JRuby zlib extension to this repository and release it as a -java version of the gem. JRuby would then remove it from being part of our core binary and ship it as a normal standard library gem.

The first step could happen any time and would be very quick; see a similar case in the bigdecimal gem.

The second step will require disentangling our zlib code from JRuby proper. You can see it here... it might not be too bad to transplant: https://github.com/jruby/jruby/tree/master/core/src/main/java/org/jruby/ext/zlib

[headius]

Ok, importing turned out to be easier than I expected: #99.