Rails attribute lookup

1 - benchmark.rb

require 'benchmark/ips'

user = User.last

Benchmark.ips do |x|
  x.report('.attr') { user.name }
  x.report('[attr]') { user.[]('name') }

  # What rails calls for user['name']
  x.report('read_attr/missing') { user.read_attribute('name') { |n| missing_attribute(n, caller) } }

  # Drilling down into read_attribute without missing_attribute
  x.report('read_attribute') { user.read_attribute('name') }
  x.report('attribute_set[].value') { user.instance_variable_get(:@attributes)['name'].value }
  
  # We wouldn't want to do this because type casting is important, but just for curiousity as to how much time
  # type casting takes
  x.report('attribute_set[].value_before_type_cast') { user.instance_variable_get(:@attributes)['name'].value_before_type_cast }
  
  x.compare!
end

## Method trace with sources:

user[:name]
  # https://github.com/rails/rails/blob/master/activerecord/lib/active_record/attribute_methods.rb#L372-L374
user.read_attribute(:name) { |n| missing_attribute(n, caller) }
  # https://github.com/rails/rails/blob/master/activerecord/lib/active_record/attribute_methods/read.rb#L31-L41
user._read_attribute(:name, &block)
  # https://github.com/rails/rails/blob/master/activerecord/lib/active_record/attribute_methods/read.rb#L45-L55
user.@attributes.fetch_value('name') { |n| yield n if block_given? }
  # https://github.com/rails/rails/blob/master/activemodel/lib/active_model/attribute_set.rb#L40-L50
attribute_set['name']
  # https://github.com/rails/rails/blob/master/activemodel/lib/active_model/attribute_set.rb#L15-L17
  ...value
  # https://github.com/rails/rails/blob/master/activemodel/lib/active_model/attribute.rb#L40-L44

2 - results.txt

Warming up --------------------------------------
               .attr   148.416k i/100ms
              [attr]    54.464k i/100ms
   read_attr/missing    64.984k i/100ms
      read_attribute   101.857k i/100ms
attribute_set[].value
                       171.315k i/100ms
attribute_set[].value_before_type_cast
                       181.550k i/100ms
Calculating -------------------------------------
               .attr      2.802M (± 2.1%) i/s -     14.100M in   5.034267s
              [attr]    837.030k (± 4.9%) i/s -      4.194M in   5.021677s
   read_attr/missing    856.952k (± 4.4%) i/s -      4.289M in   5.013995s
      read_attribute      1.426M (± 2.9%) i/s -      7.130M in   5.002834s
attribute_set[].value
                          2.927M (± 3.6%) i/s -     14.733M in   5.040511s
attribute_set[].value_before_type_cast
                          3.350M (± 3.5%) i/s -     16.884M in   5.047108s

Comparison:
attribute_set[].value_before_type_cast:  3349508.8 i/s
attribute_set[].value:  2926736.1 i/s - 1.14x  slower
               .attr:  2802032.7 i/s - 1.20x  slower
      read_attribute:  1426429.5 i/s - 2.35x  slower
   read_attr/missing:   856952.2 i/s - 3.91x  slower
              [attr]:   837030.3 i/s - 4.00x  slower

3 - read_attribute vs _read_attribute.rb

Benchmark.ips do |x|
  x.report('read_attribute') { user.read_attribute(:name) }
  x.report('_read_attribute') { user._read_attribute(:name) }
  x.compare!
end

# Warming up --------------------------------------
#       read_attribute    79.511k i/100ms
#      _read_attribute   136.627k i/100ms
# Calculating -------------------------------------
#       read_attribute      1.207M (± 4.4%) i/s -      6.043M in   5.017097s
#      _read_attribute      2.355M (± 4.8%) i/s -     11.750M in   5.001814s

# Comparison:
#      _read_attribute:  2354831.7 i/s
#       read_attribute:  1206808.2 i/s - 1.95x  slower

4 - improvement.rb

module ActiveRecord
  module AttributeMethods
    alias_method :old_lookup, :[]

    def [](attr_name)
      public_send(attr_name)
    end
  end
end


Benchmark.ips do |x|
  x.report('old') { tag.old_lookup(:name) }
  x.report('new') { tag[:name] }
  x.report('method') { tag.name }
  x.compare!
end

# Warming up --------------------------------------
#                  old    59.763k i/100ms
#                  new   125.890k i/100ms
#               method   149.602k i/100ms
# Calculating -------------------------------------
#                  old    719.833k (± 4.6%) i/s -      3.646M in   5.075733s
#                  new      2.029M (± 1.9%) i/s -     10.197M in   5.028319s
#               method      2.341M (± 9.9%) i/s -     11.669M in   5.042085s

# Comparison:
#               method:  2340888.5 i/s
#                  new:  2028720.4 i/s - 1.15x  slower
#                  old:   719832.8 i/s - 3.25x  slower