Fix defining object finalizer in Ruby 3.1 to reference a UUID string

[vkononov]

Describe the change

Fixes the "undefined local variable or method `callback_queue' for FiniteMachine::Observer:Class (NameError)" exception thrown in Ruby 3.1.1

Why are we doing this?

In Ruby 3.1.1, accessing callback_queue from a finalizer causes a "undefined local variable or method `callback_queue' for FiniteMachine::Observer:Class (NameError)", and callback_queue is never cleaned up. However, making the finalizer an instance method rather than a class method throws a warning about improper use of finalizers.

The fix is borrowed from a Github issue found at https://github.com/appsignal/rdkafka-ruby/pull/160/files.

Benefits

This library will become compatible with Ruby 3.1.1.

Drawbacks

None.

Requirements

• Tests passing locally?
• Code style checked?
• Rebased with master branch?
• Documentation updated?
• Changelog updated?

[dup2]

This just hit me also when trying to update an application to ruby 3.1.

What do we need to be able to merge this?

[luiswitz]

Hello 👋 - Re-asking @dup2 question: what do we need to be able to merge this?

[piotrmurach]

Hi Vadim,

Thank you for the PR and for resolving this issue. Would you have time to look into the comments? I appreciate this is long overdue so hopefully, we can get this sorted for everyone.

Also, if you could add an entry in the changelog under the 'Fixed' heading with your name and handle that would be great. Please don't worry about the version, you can use '## unreleased' for now.

[vkononov]

@piotrmurach Please let me know if there's anything else you need me to do to get this merged. Thanks.

[piotrmurach]

Hi, I've left a few more comments. The annoying thing is that this finalizer is only necessary when async callbacks are used. Otherwise, for the vast majority of cases, I believe it shouldn't be even defined. Eager to learn about what you think.

[vkononov]

I've made a bit of refactoring to address your comments and after familiarizing myself further with how the ObjectSpace class works. Hopefully, this can be merged now, but I'm happy to hear any other feedback.

[abhishekjain16]

@piotrmurach Is there anything we can do to get this merged and make this lib compatible with Ruby 3.1+. Happy to help in any way possible

[vkononov]

@piotrmurach Is there anything we can do to get this merged and make this lib compatible with Ruby 3.1+. Happy to help in any way possible

@abhishekjain16 You could help resolve the failing pipelines. That's probably the only thing that is still needed.

[abhishekjain16]

@vkononov This method needs to return @callback_queue

      return @callback_queue if instance_variable_defined?(:@callback_queue)

      @callback_queue = MessageQueue.new
      @object_id = SecureRandom.uuid
      ObjectSpace.define_finalizer(@object_id, cleanup_callback_queue)
      @callback_queue

Add @callback_queue to return from this method fixes pipeline

[abhishekjain16]

@vkononov https://github.com/piotrmurach/finite_machine/pull/74/files#r1285879315 This should fix the pipeline

[vkononov]

Thank you, @abhishekjain16. Can't believe I missed that. @piotrmurach, Could you run the pipeline and merge this code if the pipeline succeeds?

[jimbali]

Thanks for this. Are there any imminent plans to release a new version to RubyGems with this fix?

[piotrmurach]

@jimbali Thanks for your interest. I'm preparing a new release but cannot promise any timelines.

[jimbali]

Hi @piotrmurach, have you found any time to prepare a release for this yet? Any idea when that might be? Thanks

[piotrmurach]

Hi @jimbali, I appreciate your patience. I had to deal with upsetting news from my family that didn't allow me the headspace to finish what I wanted. I released a new 0.14.1 version with a few fixes. Please see the changelog for more information.

[jimbali]

Aw man, really sorry to hear that. Thanks for finding the time to sort this out. I've sponsored you a couple of coffees!

[piotrmurach]

@jimbali That's life and the show must go on. You didn't have to but thank you. Appreciate your kindness. 🙏