copy_vs_merge.rb

require 'benchmark'
require 'securerandom'
require 'ostruct'

cids = {}

class Object
  def deep_copy
    Marshal.load(Marshal.dump(self))
  end
end

class OpenStruct
  def [](field)
    self.send field
  end

  def process_field_copy(field, cids)
    copy = self[field].deep_copy

    cids.inject({}) do |hash, (cid, count)|
      copy[cid] = self[field].fetch(cid, 0) + count
    end

    self[field] = copy
    self.save
  end

  def process_field_merge(field, cids)
    processable_cids = cids.inject({}) do |hash, (cid, count)|
      hash[cid] = self[field].fetch(cid, 0) + count
      hash
    end
    self[field] = self[field].merge(processable_cids)
    self.save
  end
end


1_000_000.times do
  cids[SecureRandom.hex] = 1
end

puts Benchmark.measure {
  OpenStruct.new(satisfied_cids: {}).process_field_merge(:satisfied_cids, cids)
}


puts Benchmark.measure {
  OpenStruct.new(satisfied_cids: {}).process_field_copy(:satisfied_cids, cids)
}