require 'mongoid'

class Foo
  include Mongoid::Document
  embeds_many :bars
end

class Bar
  include Mongoid::Document
  embedded_in :foo
end

require 'benchmark'
array_1k = Array.new(1000) { Bar.new }
array_2k = Array.new(2000) { Bar.new }
array_3k = Array.new(3000) { Bar.new }
array_4k = Array.new(4000) { Bar.new }
array_5k = Array.new(5000) { Bar.new }

Benchmark.bm do |x|
  x.report('1k') { Foo.new.bars = array_1k }
  x.report('2k') { Foo.new.bars = array_2k }
  x.report('3k') { Foo.new.bars = array_3k }
  x.report('4k') { Foo.new.bars = array_4k }
  x.report('5k') { Foo.new.bars = array_5k }
end

def object_already_related?(document)
  _target.any? { |existing| existing.id && existing === document }
end