hwia_perf.rb

require "active_support/hash_with_indifferent_access"
require "active_support/core_ext/object/deep_dup"
require "active_support/version"
require "securerandom"
require "benchmark"

class BigHwiaPerfBench
  def run!
    make_sure_on_active_support_5!

    apply_patch if apply_patch?

    do_bench
  end

  def do_bench
    5.times do
      big_hwia = build_big_hwia

      GC.disable
      puts Benchmark.measure { big_hwia.deep_dup }
      GC.enable
    end
  end

  def make_sure_on_active_support_5!
    raise "not on 5" unless ActiveSupport::VERSION::MAJOR == 5
  end

  def apply_patch?
    ENV["APPLY_PATCH"] == "true"
  end

  def apply_patch
    HashWithIndifferentAccess.class_eval do
      def initialize(constructor = {})
        if constructor.respond_to?(:to_hash)
          super()
          update(constructor)

          hash = constructor.is_a?(Hash) ? constructor : constructor.to_hash
          self.default = hash.default if hash.default
          self.default_proc = hash.default_proc if hash.default_proc
        else
          super(constructor)
        end
      end
    end
  end

  def build_big_hwia
    outer_hash = HashWithIndifferentAccess.new

    100.times do
      inner_hash = outer_hash[SecureRandom.hex] = HashWithIndifferentAccess.new

      100.times do
        inner_inner_hash = inner_hash[SecureRandom.hex] = HashWithIndifferentAccess.new

        100.times do
          inner_inner_hash[SecureRandom.hex] = SecureRandom.hex
        end
      end
    end

    outer_hash
  end
end

BigHwiaPerfBench.new.run!