bm.rb

require "bundler/inline"
require 'benchmark'

gemfile(true) do
  source "https://rubygems.org/"

  gem "ostruct"
  gem "rails"
  gem "sqlite3"
end

require "active_record"
require "logger"
require "minitest/autorun"

ActiveRecord::Base.establish_connection(adapter: "sqlite3", database: ":memory:")
ActiveRecord::Base.logger = Logger.new($stdout)

ActiveRecord::Schema.define do
  create_table :posts, force: true do |t|
    t.string :title
  end
end


  def new_find_finder_class_for(record, stop_class)
    current_class = record.class
    found_class = nil
    loop do
      found_class = current_class unless current_class.abstract_class?
      break if current_class == stop_class
      current_class = current_class.superclass
    end

    found_class
  end

  def old_find_finder_class_for(record, stop_class)
    class_hierarchy = [record.class]

    while class_hierarchy.first != stop_class
      class_hierarchy.unshift(class_hierarchy.first.superclass)
    end

    class_hierarchy.detect { |klass| !klass.abstract_class? }
  end
class ApplicationRecord < ActiveRecord::Base
  self.abstract_class = true
end
class Post < ApplicationRecord
end

class Post2 < Post

end
class Post3 < Post2

end
class Post4 < Post3
end

amount = 100000
obj = Post.new
Benchmark.bmbm do |x|
  x.report("Old") do
    amount.times do
      old_find_finder_class_for(obj, ApplicationRecord)
    end
  end
  x.report('New') do
    amount.times do
      new_find_finder_class_for(obj, ApplicationRecord)
    end
  end
end