ManageIQ currently runs on Ruby on Rails 3. Aaron "tenderlove" Patterson presents his effort to migrate to RoR 4, which entails some changes in the code to take advantage of the latest advances in RoR. For more on ManageIQ, see http://manageiq.org/

1. ( °͡ ʖ͜ °͡) .oO(Hi)

2. Aaron
Patterson

6. Ruby Core
Rails Core

7. Enterprise
Software

8. Twitter: tenderlove
GitHub: tenderlove
Instagram: tenderlove
Yo: tenderlove

10. apatters@redhat.com

11. tenderlove@redhat.com

12. Tender
Parents

13. OMG
INTERNET
POINTS

14. Revert Commits
Count Too!

15. More mistakes ==
more points!!!!

16. Short Stack
Engineer

19. Gorbachev Puff Puff Thunderhorse

20. SEA-TAC Airport YouTube

22. I am new!

23. Lost
Passport

24. Very 

25. I am new!

26. Upgrading to
Rails 4.x

27. Upgrading to
Edge Rails

28. Rails Release
Timeline

29. 4.2 is Very Soon™

30. Next is 5.0

31. Upgrading Rails

32. Why?

33. Performance

34. Memory Reduction

35. Cost

36. How?

37. Push upstream

38. Move to gems

39. Change
implementation

40. Issues Today

41. Rails Fork

42. Rails
Monkey Patches

43. Monkey Patches

44. Rails Fork

45. Active Record
Object Allocation Time

46. ms = Benchmark.ms do
records = rows.map { |model|
# …
}.uniq
end
logger.debug(' %s Inst Including
Associations (%.1fms - %drows)' %
[join_base.active_record.name || 'SQL',
ms, records.length])

47. We can’t
upstream this :-(

48. ActiveSupport
Notifications

49. ActiveSupport::Notifications.instrument(
"some.key", payload
) do
records = rows.map { |model|
# ...
}.uniq
end

50. ActiveSupport::Notifications.subscribe(
'some.key'
) do |value|
# same logger statement
end

51. Truncate table

52. # Executes the truncate statement.
def truncate(table_name, name = nil)
execute("TRUNCATE TABLE
#{quote_table_name(table_name)}", name)
end

53. Pushed up stream

54. Added a
monkey patch
to backport

55. 64 bit
primary keys

56. In PG:
"integer" == 32bit

57. In PG:
"bigint" == 64bit

58. Default is 32bit

59. Why?

60. ¯_(ツ)_/¯

61. Schema.rb
No PK
declared
create_table "accounts" do |t|
t.string "name"
t.integer "acctid"
end
Means
32bit

62. We can
upstream this

63. Determine backwards
compat scheme

64. Default PK
sequences

65. + return if options[:id] == false
+ return unless self.respond_to?
(:set_pk_sequence!)
+
+ value = ActiveRecord::Base.rails_sequence_start
+ set_pk_sequence!(table_name, value) unless
value == 0

66. We can’t
upstream this

67. Extract and
"super"

68. Add
"extension" points.

69. Auto-reconnect

70. Supposedly fixed?

71. + def
self.did_retry_db_connection(connection
,count)
+ logger.info "CONNECTION RETRY:
#{connection.class.name} retry
##{count}." if logger
+ end

72. Push Up
Better Exceptions

73. Connection
Extensions

74. Database
Statistics

75. Create a new gem:
activerecord-pg-stats

76. Virtual Columns

77. Declaration
virtual_column :name, :type
=> :string

78. 2 Responsibilities

79. Declare a "column
type" for reporting

80. Declare associations
used by the method

81. Separate these
concerns

82. Extract reporting

83. Push up relation
declaration.

84. RJS

85. Land the Angular
patch!!!!

86. jquery-rjs

87. prototype-rails

88. Monkey Patches

89. First Glance

90. Churn

91. "How often is stuff
changing?"

92. git log --all -M -C --name-only --
format='format:' "$@" | sort | grep -v
'^$' | uniq -c | sort -n | awk 'BEGIN
{print "counttfile"} {print $1 "t"
$2}'

93. 445 vmdb/app/models/miq_server.rb
498 vmdb/app/models/miq_provision_workflow.rb
508 vmdb/app/models/miq_provision.rb
590 vmdb/app/models/miq_report.rb
720 vmdb/app/controllers/report_controller.rb
777 vmdb/app/models/vm.rb
802 vmdb/app/models/host.rb
825 vmdb/app/helpers/application_helper.rb
1186 vmdb/app/controllers/application.rb

94. Cyclomatic
Complexity

95. Quantify Code
Complexity

96. flog

97. 1965.9: vmdb/db/migrate/20100302205959_collapsed_initial_migration.rb:7
1131.5: vmdb/app/controllers/ops_controller/settings/common.rb:621
1024.9: vmdb/app/controllers/application_controller/filter.rb:137
951.9: vmdb/app/controllers/application_controller/performance.rb:220
862.9: vmdb/spec/models/ems_refresh/refreshers/vc_refresher_spec.rb:27
842.8: vmdb/app/controllers/ops_controller/settings/common.rb:881
824.5: vmdb/spec/models/ems_refresh/refreshers/
rhevm_refresher_3_1_spec.rb:230
791.5: vmdb/app/helpers/application_helper.rb:648

98. application_helper
$$$$$$

99. Static Analysis

100. Find unused
methods

101. Ripper

102. require 'ripper'
class MyParser < Ripper
def on_def name, _, _
# do something
end
end
parser = MyParser.new "some code"
parser.parse

103. class MyParser < Ripper
attr_reader :methods, :calls
def initialize code, file, line
super
@methods = []
@calls = []
end
def on_def name, *rest
@methods << name
end
alias :on_command :on_def
def on_defs target, dot, name, *args
@methods << name
end
def on_call target, dot, name
@calls << name
end
def on_fcall name
@calls << name
end
alias :on_symbol :on_fcall
alias :on_vcall :on_fcall
end

104. Find.find(ARGV[0]) do |file|
next if File.directory? file
ext = file[/(?<=.)w+$/]
next unless ext
case ext
when 'rb'
parser = MyParser.new(File.read(file),
file, 1)
parser.parse
when 'erb'
parser = MyParser.new
ERB.new(File.read(file)).src, file, 1
parser.parse
end
end

105. Dynamic Dispatch
superclass.send("virtual_#{m}")

106. Static Analysis +
Ruby = 

107. Probably also why
Brakeman isn’t perfect

108. This Summit is
GREAT!

109. Communication

110. Browser
WebServer
Memcached

112. Every 500ms
Browser
WebServer
Memcached

113. Every 500ms
Browser
WebServer
Memcached

114. Cache Size

115. Code Complexity

116. Bugs

117. Server Load

118. Every 500ms
Browser
WebServer
Memcached

119. Always Question
Assumptions

120. Ask Why

121. Business
Requirements
aren’t set in stone.

122. Thanks Everyone!

123. Questions?