improved version of 12 hours to rate a rails application - modified after feedback from Euruko and ScotRuby. As presented at Railsconf

1. hours to rate a
Rails application
Elise Huard @elise_huard
http://jabberwocky.eu
Tuesday 8 June 2010

2. Acquisition
Tuesday 8 June 2010

3. Maintenance
Tuesday 8 June 2010

4. 12 hours To
Rate a Rails
Application
12:00
Tuesday 8 June 2010

5. Team
Tuesday 8 June 2010

6. One man’s application
Tuesday 8 June 2010

7. Automator
Control freak
Innovator
Tuesday 8 June 2010

8. ...
Tuesday 8 June 2010

9. Vision
vision
photo by OneEighteen
Tuesday 8 June 2010

10. Methodology
Tuesday 8 June 2010

11. issue Tracker
Version control
docman on flickr
Tuesday 8 June 2010

12. Back seat
driver
Tuesday 8 June 2010

13. 12 hours To
Rate a Rails
Application
10:00
Tuesday 8 June 2010

14. Try the app
Björn Söderqvist on Flickr
Tuesday 8 June 2010

15. does it work ?
Tuesday 8 June 2010

16. 12 hours To
Rate a Rails
Application
09:45
Tuesday 8 June 2010

17. Rails version
Tuesday 8 June 2010

18. plugins and
gems
Photo Lex on Flickr
Tuesday 8 June 2010

19. Tuesday 8 June 2010

20. managing updates
Bundler
piston
git submodules
(svn externals)
Tuesday 8 June 2010

21. Licenses
BSD, MIT, Apache ...
Tuesday 8 June 2010

22. NIH syndrom
Tuesday 8 June 2010

23. Run Tests
Tuesday 8 June 2010

24. 12 hours To
Rate a Rails
Application
09:00
Tuesday 8 June 2010

25. Lots of code
Tuesday 8 June 2010

26. config/routes.rb
match ‘/’, :to => ‘root#index’
match ‘root’, :to => ‘root#index’
namespace :admin do
resources :grids do
resources :nodes
resources :edges do
collection do
post :all
post :update_all
end
end
resources :walkers
end
end
resources :nodes, :only => [:show,:new,:create,:destroy] do
put :directions, :on => :collection
end
resources :walkers, :only => [:show,:new,:create,:destroy] do
get :select, :on => :collection
end
resources :itineraries, :only => [:show]
Tuesday 8 June 2010 map.four_oh_four '*path' , :controller => 'four_oh_fours'

27. models
railroad -M | dot Tpng > models.png
rubymine ctrl-alt-D
Tuesday 8 June 2010

28. names
“There are only two hard things in
Computer Science: cache
invalidation and naming things”
Phil Karlton
Tuesday 8 June 2010

29. 12 hours To
Rate a Rails
Application
08:30
Tuesday 8 June 2010

30. Metrics
know thine tools
docman on flickr
Tuesday 8 June 2010

31. LOC
rake stats
+----------------------+-------+-------+---------+---------+-----+-------+
| Name | Lines | LOC | Classes | Methods | M/C | LOC/M |
+----------------------+-------+-------+---------+---------+-----+-------+
| Controllers | 2702 | 2150 | 36 | 158 | 4 | 11 |
| Helpers | 358 | 303 | 0 | 22 | 0 | 11 |
| Models | 1358 | 1104 | 30 | 117 | 3 | 7 |
| Libraries | 2286 | 1655 | 38 | 152 | 4 | 8 |
| Integration tests | 0 | 0 | 0 | 0 | 0 | 0 |
| Functional tests | 1687 | 1322 | 31 | 195 | 6 | 4 |
| Unit tests | 1356 | 1079 | 27 | 158 | 5 | 4 |
+----------------------+-------+-------+---------+---------+-----+-------+
| Total | 9747 | 7613 | 162 | 802 | 4 | 7 |
+----------------------+-------+-------+---------+---------+-----+-------+
Code LOC: 5212 Test LOC: 2401 Code to Test Ratio: 1:0.5
Tuesday 8 June 2010

32. RubyParser and
Parsetree
Ryan Davis and Eric Hodel
(‘Ruby Sadists’)
Tuesday 8 June 2010

33. RubyParser and
Parsetree
Abstract syntax tree
RubyParser.new.parse(File.read(‘metrics.rb’),‘metric.rb’)
class Metrics s(:class,:Metrics, nil,
def probe s(:scope,
s(:defn,:probe,
puts "good" s(:args),
end s(:scope,
end s(:block,
s(:call, nil, :puts,
s(:arglist,
s(:str, "good"))))))))
Symbolic Expression (Sexp)
Tuesday 8 June 2010

34. RubyParser and
Parsetree
Abstract syntax tree
RubyParser.new.parse(File.read(‘metrics.rb’),‘metric.rb’)
class Metrics s(:class,:Metrics, nil,
def probe s(:scope,
s(:defn,:probe,
puts "good" s(:args),
end s(:scope,
end s(:block,
s(:call, nil, :puts,
s(:arglist,
s(:str, "good"))))))))
Symbolic Expression (Sexp)
Ruby2Ruby
Tuesday 8 June 2010

35. RubyParser
pure ruby
Parsetree
ruby and inline c
< 1.9
swap out with Ripper ?
Tuesday 8 June 2010

36. rake stats
size
Flog Flay
code complexity code similarities
Roodi
R_B_P
Saikuro Reek
cyclomatic antipatterns Rails
complexity
Heckle Rcov
test coverage
Tuesday 8 June 2010

37. flog
‘the pain your code
is in’
Tuesday 8 June 2010

38. FLOG
flog lib/flog.rb
647.8: flog total
13.8: flog/method average
87.5: Flog#output_details
58.8: Flog#process_iter
54.2: Flog#flog
48.8: Flog#parse_options
34.1: Flog#none
23.2: Flog#output_method_details
22.1: Flog#score_method
16.0: Flog#process_block_pass
15.6: Flog#report
15.2: Flog#expand_dirs_to_files
15.0: Flog#klass_name
Tuesday 8 June 2010

39. FLOG
Assignment Branch Condition (ABC)
def score_method(tally)
a, b, c = 0, 0, 0
tally.each do |cat, score|
case cat
when :assignment then a += score
when :branch then b += score
else c += score
end
end
Math.sqrt(a*a + b*b + c*c)
end
Tuesday 8 June 2010

40. FLOG
Weighing the AST with factors
def process_if(exp)
add_to_score :branch
process exp.shift # cond
penalize_by 0.1 do
process exp.shift # true
process exp.shift # false
end
s()
end
Tuesday 8 June 2010

41. FLOG
Very good: < 20
All Right: < 50
Tuesday 8 June 2010

42. FLAY
code similarities
Tuesday 8 June 2010

43. FLAY
flay *.rb
Total score (lower is better) = 621
1) IDENTICAL code found in :defn (mass*2 = 188)
channel.rb:48
clip.rb:80
2) Similar code found in :defn (mass = 93)
channel.rb:150
clip.rb:110
clip.rb:116
3) Similar code found in :defs (mass = 58)
contact.rb:32
contact.rb:37
Tuesday 8 June 2010

44. FLAY
RubyParser
def mass
@mass ||= self.structure.flatten.size
end
Hash of structure of nodes with mass >
threshold
self.hashes[node.structural_hash] << node
analyze:
if same hash = similar
if same node = identical
Tuesday 8 June 2010

45. Saikuro
cyclomatic
complexity
Tuesday 8 June 2010

46. Saikuro
Tuesday 8 June 2010

47. Saikuro
ruby-lex
every keyword is interpreted into
‘state’
state used to calculate
if, unless, while, until, for, elsif, when, rescue
(blocks)
Recursively
Tuesday 8 June 2010

48. Saikuro
Good:
methods < 5
Tuesday 8 June 2010

49. Roodi
‘Ruby Object Oriented Design Inferometer’
nutmeg66 on flickr
Tuesday 8 June 2010

50. Roodi
app/controllers/itineraries_controller.rb:4 - Method name "show" cyclomatic complexity
is 14. It should be 8 or less.
app/models/itinerary.rb:41 - Block cyclomatic complexity is 6. It should be 4 or less.
app/controllers/itineraries_controller.rb:4 - Method "show" has 30 lines. It should
have 20 or less.
app/helpers/application_helper.rb:27 - Method "clippy" has 26 lines. It should have 20
or less.
Tuesday 8 June 2010

51. Roodi
RubyParser
visitor pattern
visitor: checker (Configurable)
visitable: parsed nodes
= extensible
Tuesday 8 June 2010

52. Reek
Tuesday 8 June 2010

53. Reek
UserSessionsController has no descriptive comment (Irresponsible Module)
UserSessionsController#destroy calls current_user_session twice
(Duplication)
app/controllers/users_controller.rb -- 5 warnings:
UsersController has no descriptive comment (Irresponsible Module)
UsersController tests @aid_app at least 4 times (Simulated Polymorphism)
UsersController#create calls params 3 times (Duplication)
UsersController#create calls params[:user] 3 times (Duplication)
...
Tuesday 8 June 2010

54. Reek
OO Code smells
Control Couple
Data Clump
Feature Envy
Large Class
Long Method
Long Parameter List
Simulated Polymorphism
Uncommunicative Name
Tuesday 8 June 2010

55. Reek
RubyParser
extends parsed nodes
traverses nodes
returns code after Ruby2Ruby
Tuesday 8 June 2010

56. rails_best_practices
kamoda on Flickr
Tuesday 8 June 2010

57. rails_best_practices
./app/controllers/ws/vmg/aid_user_accounts_controller.rb:160 - move model logic into model
(@aid_user_account called_count > 4)
./app/controllers/ws/vmg/ipt_controller.rb:102 - move model logic into model (xml
called_count > 4)
./app/controllers/ws/vmg/ipt_controller.rb:102 - move model logic into model (pf
called_count > 4)
./config/routes.rb:3 - overuse route customizations (customize_count > 3)
./config/routes.rb:35 - overuse route customizations (customize_count > 3)
./app/models/vmg/scenario.rb:41 - keep finders on their own model
Tuesday 8 June 2010

58. rails_best_practices
Visitor pattern
visitor : checking_visitor
visitable: visitable sexp
Tuesday 8 June 2010

59. Churn
Tuesday 8 June 2010

60. Churn
Not only classes but also methods
(RubyParser)
Version control: git, Hg, svn
Locates changes in source using logs
(as in git log)
Tuesday 8 June 2010

61. Churn
+-------------------------------------------------+---------------+
| file_path | times_changed |
+-------------------------------------------------+---------------+
| db/schema.rb | 26 |
| config/routes.rb | 24 |
| app/controllers/application_controller.rb | 22 |
| app/controllers/add_apps_controller.rb | 22 |
| config/environment.rb | 20 |
| app/views/layouts/application.html.erb | 20 |
| app/models/ability.rb | 18 |
...
Tuesday 8 June 2010

62. Churn
common sense ...
mostly useful in maintenance phase
Tuesday 8 June 2010

63. Rcov
Tuesday 8 June 2010

64. Rcov
Total coverage: comments included
Tuesday 8 June 2010

65. Rcov
Executes test
keeps track of the executed lines
Using C extension when possible
to hook into MRI
(experimental for 1.9)
Tuesday 8 June 2010

66. Rcov
good: 100% coverage
Tuesday 8 June 2010

67. Heckle
Tuesday 8 June 2010

68. Heckle
ParseTree + Ruby2Ruby
mutate
Tuesday 8 June 2010

69. Heckle
Initial tests pass. Let's rumble.
**********************************************************************
*** AidApp#property_names loaded with 4 possible mutations
**********************************************************************
4 mutations remaining...
Replacing AidApp#property_names with:
--- original
+++ mutation
def property_names
- (meta_policy and meta_policy.property_names_for(:aid_app))
+ (nil and meta_policy.property_names_for(:aid_app))
end
Tuesday 8 June 2010

70. Heckle
time-consuming: combinatorials
more for small programs (gems, scripts)
doesn’t work for ruby 1.9 (ParseTree)
Tuesday 8 June 2010

71. rake stats
size
Flog Flay
code complexity code similarities
Roodi
R_B_P
Saikuro Reek
cyclomatic antipatterns Rails
complexity
Heckle Rcov
test coverage
Tuesday 8 June 2010

72. metric_fu
Tuesday 8 June 2010

73. what these metrics don’t
tell you
Bugs
Tuesday 8 June 2010

74. what these metrics don’t
tell you
code performance
Ruby Profiling
Tuesday 8 June 2010

75. Reads like a book
Tuesday 8 June 2010

76. 12 hours To
Rate a Rails
Application
06:30
Tuesday 8 June 2010

77. check out the good stuff
OrbitalJoe on flickr
Tuesday 8 June 2010

78. Database
db/schema.rb
seed data
everything in migrations ?
Tuesday 8 June 2010

79. views
Bad:
unindented
divitis
(too much) javascript in body
too much logic in viewiew
Tuesday 8 June 2010

80. 12 hours To
Rate a Rails
Application
04:30
Tuesday 8 June 2010

81. Tests
Tuesday 8 June 2010

82. maintainable test
suite
tests = software
changes in implementation
changes in requirements
Tuesday 8 June 2010

83. maintainable test
suite
express code responsibility
hide implementation detail
Tuesday 8 June 2010

84. maintainable test
suite
-> expressive code
(DRY not mandatory)
Tuesday 8 June 2010

85. 12 hours To
Rate a Rails
Application
02:30
Tuesday 8 June 2010

86. Deployment
photo by devilarts on flickr
Tuesday 8 June 2010

87. Deployment
Tuesday 8 June 2010

88. Deployment
Automation, automation, automation
Tuesday 8 June 2010

89. Deployment
deployment = software
same rules apply
Tuesday 8 June 2010

90. Deployment
Traffic
Performance tests
Bottlenecks
Tuesday 8 June 2010

91. 12 hours To
Rate a Rails
Application
01:00
Tuesday 8 June 2010

92. Brownie Points
Tuesday 8 June 2010

93. Continuous integration
... and they’re using it
Tuesday 8 June 2010

94. Documentation of any kind
... and it’s up to date
Tuesday 8 June 2010

95. monitoring
exception notification
Log analyzers
Tuesday 8 June 2010

96. testing javascript
Continuous
performance testing
Tuesday 8 June 2010

97. 12 hours To
Rate a Rails
Application
00:00
Tuesday 8 June 2010

98. http://railroad.rubyforge.org/
http://www.igvita.com/2008/12/11/ruby-ast-for-fun-and-profit/
http://ruby.sadi.st/Ruby_Sadist.html
http://goruco2008.confreaks.com/04_davis.html
http://cwd.dhemery.com/2009/11/wmaat/
http://c2.com/cgi/wiki?AbcMetric
http://hissa.nist.gov/HHRFdata/Artifacts/ITLdoc/235/title.htm
http://blog.rubybestpractices.com/posts/judofyr/sexp-for-
rubyists.html
Elise Huard @elise_huard
elise@elisehuard.be
http://jabberwocky.eu
Tuesday 8 June 2010