[Ruby] Strings used in expressions being garbage collected

[stenlarsson]

Describe the bug, including details regarding any error messages, version, and platform.

#48880 is marked as fixed, but I'm still getting corrupted values.

It is very difficult to create a test case that reliably demonstrates the problem. This defines a finaliser on the string literal, but we need to go through some hoops to make sure it is not in scope of any block.

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require 'objspace'

class TestExecutePlan < Test::Unit::TestCase
  class LiveChecker
    def initialize
      @live = true
    end

    def check(object)
      ObjectSpace.define_finalizer(object, self.class.create_finalizer(self))
      object
    end

    def live?
      GC.start
      @live
    end

    def finalize
      @live = false
    end

    def self.create_finalizer(checker)
      proc { checker.finalize }
    end
  end

  def test_filter_expressions_live
    checker = LiveChecker.new
    table = Arrow::Table.new(
      'foo' => [1, 2],
      'bar' => %w[a b],
    )
    plan = Arrow::ExecutePlan.new
    node = plan.build_source_node(table)
    node = plan.build_filter_node(
      node,
      Arrow::FilterNodeOptions.new(
        Arrow::CallExpression.new('equal', [:bar, checker.check('a')]),
      ),
    )
    assert do
      checker.live?
    end
  end

  def test_project_expressions_live
    checker = LiveChecker.new
    table = Arrow::Table.new(
      'foo' => [1, 2],
      'bar' => [%w[a b], %w[c d]],
    )
    plan = Arrow::ExecutePlan.new
    node = plan.build_source_node(table)
    node = plan.build_project_node(
      node,
      Arrow::ProjectNodeOptions.new(
        [
          :foo,
          Arrow::CallExpression.new('binary_join', [:bar, checker.check(',')]),
        ],
        %w[foo bar],
      ),
    )
    assert do
      checker.live?
    end
  end
end

These tests pass if I add CallExpression, FilterNodeOptions, and ProjectNodeOptions to the gc_guard in loader.rb, but I'm not sure if it is the correct solution.

Component(s)

Ruby

[kou]

Thanks. How about #48989?

[stenlarsson]

Nice! That in combination with #48919 seems to completely solve the issue for me. 🙏