1. Attributes Unwrapped

2. @jonleighton

4. I lied to you

6. Measure

7. Measure
Refactor

8. Measure
Refactor
Optimise

9. LET’S DO SCIENCE

10. gem 'rails', '3.2.0'
require 'active_record'
ActiveRecord::Base
.establish_connection(
:adapter => 'sqlite3',
:database => ':memory:')

11. ActiveRecord::Schema.define do
create_table :posts do |t|
t.string :title
end
end
class Post < ActiveRecord::Base
end
p = Post.create(:title => "lol")

12. require 'benchmark'
n = 1_000_000
Benchmark.report(20) do |r|
r.report('attribute') do
n.times { p.title }
end
r.report('read_attribute') do
n.times { p[:title] }
end
end

13. attribute 1.09 s
read_attribute 2.87 s

14. gem install
benchmark_suite

15. require 'benchmark/ips'
Benchmark.ips do |r|
r.report('attribute') do
p.title
end
r.report('read_attribute') do
p[:title]
end
end

16. attribute 828,648
read_attribute 299,856

17. Ruby 1.9

18. Ruby 1.8

19. Ruby 1.8
oops!

20. define_method

21. method compilation

24. create_table :roflcopters do |t|
t.string " ROFL:ROFL:ROFL:ROFL"
t.string " _^____ "
t.string " L __/ [] "
t.string "LOL===_ "
t.string " L _________] "
t.string " I I "
t.string " --------/ "
end

25. if compilable?
class_eval <<-STR
def #{attr_name}
...
end
STR
else
define_method attr_name do
...
end
end

26. attr_name
=~
/A[a-zA-Z_]w*[!?=]?z/

27. :title
=~
/A[a-zA-Z_]w*[!?=]?z/

28. Ruby 1.9
:title =~ /.../
# => true

29. Ruby 1.8
:title =~ /.../
# => false

30. def __temp__
...
end
alias "@#>" :__temp__
undef_method :__temp__

31. DO
def __temp__
N'T
...
US
end
E
TH
alias "@#>" :__temp__
IS
undef_method :__temp__

32. API Changes

34. def title
self[:title].upcase
end

35. def title
super.upcase
end

36. module A
def foo
"bar"
end
end

37. class B
include A
def foo
super.upcase
end
end

38. Don’t fight Ruby
<3 <3 <3

39. #read_attribute
#[]

40. def read_attribute(name)
name = "_#{name}"
if respond_to?(name)
send(name)
else
# other stuff
end
end

41. Module.new

42. def read_attribute(name)
mod = self.class.methods_module
if mod.respond_to?(name)
mod.send(name, @attributes)
else
# other stuff
end
end

43. Module.new.respond_to?(:name)
# => true

44. Module.new { extend self }

45. Module.new { extend self }
mod.method_defined?(:name)

46. IN
SA
Module.new { extend self }
NE
HA
CK
mod.method_defined?(:name)

47. Still too slow
☹

48. gem install
perftools.rb

50. if attr_name == 'id'
attr_name =
self.class.primary_key
end

51. No code is faster
than no code

52. def title
cast @attributes['title']
end

53. def title
cast @attributes[:title]
end

55. class A
def initialize
@attributes = { :foo => 1 }
end
def foo
@attributes[:foo]
end
end

56. class B
def initialize
@attributes = { 'foo' => 1 }
end
def foo
@attributes['foo']
end
end

57. Benchmark.ips do |r|
r.report('symbol') { a.foo }
r.report('string') { b.foo }
end

59. code = "@attributes['foo']"
iseq =
RubyVM::InstructionSequence
.compile(code)
puts iseq.disassemble

60. trace 1
getinstancevariable :@attributes
putstring "foo"
opt_aref <ic:2>
leave

61. trace 1
getinstancevariable :@attributes
putobject :foo
opt_aref <ic:2>
leave

62. DEFINE_INSN
putstring
(VALUE str)
()
(VALUE val)
{
val = rb_str_resurrect(str);
}

63. DEFINE_INSN
putobject
(VALUE val)
()
(VALUE val)
{
/* */
}

65. code = "@attributes['foo']"
compiled =
Rubinius::Compiler
.compile_string(code)
puts compiled.decode

66. push_ivar 0
push_literal "foo"
string_dup
send_stack :[], 1
pop
push_true
ret

67. push_ivar 0
push_literal :foo
send_stack :[], 1
pop
push_true
ret

69. jruby --bytecode
-e "@attributes['foo']"

70. RubyString

71. RubyString
RubySymbol

72. Performance problems
are a code smell

73. Be a scientist

74. But...

75. Avoid roflscaling!

76. ER!
OV
S
IT'
Thanks!

77. Thanks!
IT'
S
OV
E R!
(♥ @tenderlove ♥)