benchmark_instantiate_collection_proxy.rb

  require 'benchmark/ips'

begin
  class CreateModels < ActiveRecord::Migration
    def change
      create_table :items do |t|
      end

      create_table :events do |t|
        t.belongs_to :item
      end

      create_table :event_people do |t|
        t.belongs_to :event
        t.belongs_to :person
      end

      create_table :people do |t|
      end
    end
  end

  class Item < ActiveRecord::Base
    has_many :events
    has_many :event_people, :through => :events
    has_many :people, :through => :events
  end

  class Event < ActiveRecord::Base
    belongs_to :item
    has_many :event_people
    has_many :people, :through => :event_people
  end

  class EventPerson < ActiveRecord::Base
    belongs_to :event
    belongs_to :person
  end

  class Person < ActiveRecord::Base
  end

  ActiveRecord::Migration.verbose = false
  CreateModels.new.change

rescue => e
  # Tables already exist
  # puts e.message
end

unless Item.count >= 100
  puts "Populating Database"
  1000.times do
    Item.create
  end

  Item.all.each_with_index do |item|
    event = Event.new
    event.people.build
    event.people.build
    item.events << event
  end
end

puts "=" * 80
puts "Benchmark : Instantiate ActiveRecord::Associations::CollectionProxy"
puts "#{Rails.version} - #{ActiveRecord::Base.configurations[Rails.env]['adapter']}"
puts "=" * 80
puts ""

rails3 = (Rails.version.split(".").first.to_i < 4)

items = Item.all.to_a
Benchmark.ips do |x|

  x.report('has_many') {
    items.each do |item|
      association = item.association(:events)
      if rails3
        ActiveRecord::Associations::CollectionProxy.new(association)
      else
        ActiveRecord::Associations::CollectionProxy.new(Event, association)
      end
    end
  }

  x.report('has_many through') {
    items.each do |item|
      association = item.association(:event_people)
      if rails3
        ActiveRecord::Associations::CollectionProxy.new(association)
      else
        ActiveRecord::Associations::CollectionProxy.new(EventPerson, association)
      end
    end
  }

  x.report('has_many through through') {
    items.each do |item|
      association = item.association(:people)
      if rails3
        ActiveRecord::Associations::CollectionProxy.new(association)
      else
        ActiveRecord::Associations::CollectionProxy.new(Person, association)
      end
    end
  }
end