Code Charcuterie

My talk on Code Charcuterie from RailsBerry

Transcript

1. ZOMG HAPPY FRIDAY!
3. Rails Barry
4. Do you have a Mac? Do you have a Wii?
5. DarwiinRemote
6. Aaron Patterson
7. @tenderlove
8. @tenderlove TWEET TO ME!
9. aaron.patterson@gmail.com
10. aaron.patterson@gmail.com EMAIL TO ME!
11. AT&T, AT&T logo and all AT&T related marks are trademarks of AT&T Intellectual Property and/or AT&T affiliated companies.
12. Señor Software Engineer
13. ruby-core rails-core
14. WWFMD?
24. AWESOME LOGOS
25. STOP IT
28. NOTHING
29. Code Charcuterie
30. Amateur Charcuterier (sp?)
35. Tight Coupling?
36. Setting Expectations
38. Instrumentation Concurrency Attributes
39. Number of Doubts Chart of Doubts
40. Number of Doubts Chart of Doubts Few Doubts
41. Number of Doubts Chart of Doubts Many Doubts
42. Instrumentation
43. Publishing ActiveSupport::Notifications.instrument("render") do render :text => "Foo" end
44. Subscribing events = [] ActiveSupport::Notifications.subscribe("render") do |*e| events << e end
45. def instrument(name, payload={}) started = Time.now begin yield ensure @notifier.publish(name, started, Time.now, @id, payload) end end
46. def instrument(name, payload={}) started = Time.now begin yield ensure @notifier.publish(name, started, Time.now, @id, payload) end end Number of Doubts
47. my time + children
48. -> sql executed -> view rendered Events Received
49. -> sql executed -> view rendered Events Received Number of Doubts
50. Missing Information
51. -> start rendering -> start execute SQL <- finish execute SQL -> start execute SQL <- finish execute SQL <- finish rendering
52. Rendering SQL SQL
53. class Listener def start(event) end def finish(event) end end listener = Listener.new AS::Notifications.subscribe("render", listener)
54. Evented Publishing def instrument(name, payload={}) @notifier.start(name, @id, payload) begin yield ensure @notifier.finish(name, @id, payload) end end
55. Make it Quack class Timed def initialize(pattern, delegate) @delegate = delegate @timestack = Hash.new { |h,id| h[id] = Hash.new { |ids,name| ids[name] = [] } } end def start(name, id, payload) @timestack[id][name].push Time.now end def finish(name, id, payload) started = @timestack[id][name].pop @delegate.call(name, started, Time.now, id, payload) end end
56. Tiny Factory def subscribe(pattern = nil, listener = Proc.new) if listener.respond_to?(:call) subscriber = Timed.new pattern, listener else subscriber = listener end @subscribers << subscriber end
57. Our Reward
58. class Indented def initialize @indentation = 0 end def start name, id, payload print indent puts "-> #{name} -- #{payload[:virtual_path]}" @indentation += 1 end def finish name, id, payload @indentation -= 1 print indent puts "<- #{name} -- #{payload[:virtual_path]}" end private def indent " " * @indentation end end ActiveSupport::Notifications.notifier.subscribe(nil, Indented.new)
59. -> process_action.action_controller -- -> render_template.action_view -- -> !render_template.action_view -- sessions/index <- !render_template.action_view -- sessions/index <- render_template.action_view -- -> !render_template.action_view -- layouts/application -> render_partial.action_view -- -> !render_template.action_view -- layouts/_navigation <- !render_template.action_view -- layouts/_navigation <- render_partial.action_view -- -> render_partial.action_view -- -> !render_template.action_view -- sessions/_slim_login <- !render_template.action_view -- sessions/_slim_login <- render_partial.action_view -- <- !render_template.action_view -- layouts/application <- process_action.action_controller --
61. ml !render_template.action_view (4.564 ms) virtual_path layouts/application render_partial.action_view (0.346 ms) identifier /app/views/layouts/_navigation render_partial.action_view (0.133 ms) identifier /app/views/sessions/_logout.ht !render_template.action_view (0.291 ms) virtual_path layouts/_navigation !render_template.action_view (0.087 ms) virtual_path sessions/_logout _l
62. tion_controller (0.021 ms) MessagesController index GET /messages process_action.action_controller (95.463 ms) controller MessagesController action index method GET path /messages sql.active_record (5.671 ms) sql SELECT "messages"."id" AS t0_r0, "messages"."address_id" AS t0_r1, "messages"."from" AS t0_r2, "messages"."to" AS t0_r3, "messages"."disposable" AS t0_r4, "messages"."subject" AS t0_r5, "messages"."body" AS t0_r6, "messages"."plain" AS t0_r7, "messages"."html" AS t0_r8, "messages"."created_at" AS t0_r9, "messages"."updated_at" AS t0_r10, "messages"."parsed_message_id" AS t0_r11, "addresses"."id" AS t1_r0, "addresses"."name" AS t1_r1, "addresses"."person_id" AS t1_r2, "addresses"."created_at" AS t1_r3, "addresses"."updated_at" AS t1_r4 FROM "messages" LEFT render_template.action_view (63.632 ms) identifier /app/views/messages/index.html layout layouts/application
63. Concurrency
64. Amdahl's Law
66. laptop = Laptop.new 1 10.times { laptop.execute { sleep(1) } }
68. = 1
69. $ time ruby test.rb real 0m10.046s user 0m0.023s sys 0m0.008s $
70. laptop = Laptop.new ∞ 10.times { laptop.execute { sleep(1) } }
72. = 10
73. $ time ruby test.rb real 0m1.033s user 0m0.023s sys 0m0.008s $
74. Modeling Our Machine
75. class Sleeper def run; sleep(1); end end q = Queue.new 10.times { q.push Sleeper.new } 10.times { q.push nil } # 10 cores! wow! 10.times.map { Thread.new { while obj = q.pop obj.run end } }.each(&:join)
76. What is my P?
77. class Sleeper def run; sleep(1); end end q = SlowQueue.new # make `pop` cost more 10.times { q.push Sleeper.new } 10.times { q.push nil } # 10 cores! wow! 10.times.map { Thread.new { while obj = q.pop obj.run end } }.each(&:join)
78. $ time ruby test.rb real 0m2.153s user 0m0.027s sys 0m0.012s
79. Hidden Sequential Code
80. Starvation
81. Scarce Resources
83. ME EBI
84. ME EBI
85. Connection Pool
86. Connections Are Not Thread Safe
87. One to One
88. One to One Number of Doubts
89. pool.connection pool = ActiveRecord::Base.connection_pool p pool.connection.object_id # => 1234 p pool.connection.object_id # => 1234
90. Starvation 5.times { Thread.new { pool.connection } } Thread.new { pool.connection }
91. Starvation 5.times { Thread.new { pool.connection } } Thread.new { pool.connection }
92. Queueing
93. Splitting Work cpu_queue = Queue.new io_queue = Queue.new 5.times { Thread.new { io_queue.pop.run } } 10.times { Thread.new { cpu_queue.pop.run } }
94. Consumer class Saver def initialize(record) @record = record end def run @record.save! end end
95. Producer class CreatePost def initialize(q) @q = q end def run post = Post.new(:name => 'aaron') @q.push SavePost.new(post) end end
97. Parallel CPU def fib n if n < 3 1 else fib(n-1) + fib(n-2) end end 2.times.map { fib(34) }
98. $ time ruby test.rb real 0m3.315s user 0m3.264s sys 0m0.010s
99. 2.times.map { Thread.new { fib(34) } }.each(&:join) Parallelize
100. Caught in the GIL $ time ruby test.rb real 0m4.825s user 0m3.823s sys 0m1.978s
101. Slow I/O Server server = GenericServer.new('127.0.0.1') server.start do |socket| sleep 0.5 socket.print "HELLO" socket.close end
102. TCP Client require 'socket' 5.times.map { sock = TCPSocket.new '127.0.0.1', 28561 puts sock.read }
103. $ time ruby client.rb HELLO HELLO HELLO HELLO HELLO real 0m2.546s user 0m0.026s sys 0m0.009s
104. require 'socket' 5.times.map { Thread.new { sock = TCPSocket.new '127.0.0.1', 28561 puts sock.read } }.each(&:join) Parallelize
105. $ time ruby client.rb HELLO HELLO HELLO HELLO HELLO real 0m0.552s user 0m0.028s sys 0m0.009s
106. Sending Email!
107. class UserController < ApplicationController def create user = User.create!(params[:user]) UserMailer.deliver_welcome_email(user) end end
108. class UserController < ApplicationController def create user = User.create!(params[:user]) UserMailer.deliver_welcome_email(user) end end
109. class UserController < ApplicationController def create user = User.create!(params[:user]) UserMailer.deliver_welcome_email(user) end end Number of Doubts
110. class MailSender def initialize(id) @id = id end def run user = User.find(@id) UserMailer.deliver_welcome_email(user) end end
111. class UserController < ApplicationController def create user = User.create!(params[:user]) mail_queue.push MailSender.new(user.id) end end
112. Thread.new { loop do mail_queue.pop.run } }
114. Outside the loop More Parallel
115. You are ENCOURAGED to use threads
116. I/O can be parallelized CPU cannot * in MRI
117. Attribute Accessors
118. Attribute Access post = Post.new(:title => 'hello!') post.title # => 'hello!' post.respond_to?(:title) # => true
119. Lazily Defined begin p Post.instance_method(:name) rescue NameError puts "oh no!" end Post.new(:name => 'aaron') p Post.instance_method(:name)
120. Output $ ruby -I lib:test test/cases/argh.rb oh no! #<UnboundMethod: Post(#<Module:0x00>)#__temp__>
121. Definition Time def method_missing(method, *args, &block) unless self.class.attribute_methods_generated? self.class.define_attribute_methods ... end end def respond_to?(name, include_private = false) unless self.class.attribute_methods_generated? self.class.define_attribute_methods end super end
122. Who called respond_to? {:method=>"name="} ########################################################################################## lib/active_record/attribute_assignment.rb:81:in `block in assign_attributes' lib/active_record/attribute_assignment.rb:78:in `each' lib/active_record/attribute_assignment.rb:78:in `assign_attributes' lib/active_record/base.rb:498:in `initialize' test/cases/argh.rb:16:in `new' test/cases/argh.rb:16:in `<main>' ########################################################################################## {:method=>"_run__1290908416815974468__initialize__2045902499019596289__callbacks"} ########################################################################################## lib/active_support/callbacks.rb:398:in `__run_callback' lib/active_support/callbacks.rb:385:in `_run_initialize_callbacks' lib/active_support/callbacks.rb:81:in `run_callbacks' lib/active_record/base.rb:501:in `initialize' test/cases/argh.rb:16:in `new' test/cases/argh.rb:16:in `<main>' ########################################################################################## Number of Doubts
123. after_initialize class Subject < ActiveRecord::Base after_initialize :set_email_address protected def set_email_address ... end end
124. use super class Subject < ActiveRecord::Base def initialize(*args) super set_email_address # after_init end protected def set_email_address ... end end Number of Doubts
125. DO IT AGAIN! 10.times { Post.new(:name => 'aaron') }
126. What method? {:method=>"name="} {:method=>"_run__1048083580144971540__initialize__3082064574212577540__callbacks"} {:method=>"name="} {:method=>"_run__1048083580144971540__initialize__3082064574212577540__callbacks"} {:method=>"name="} {:method=>"_run__1048083580144971540__initialize__3082064574212577540__callbacks"} {:method=>"name="} {:method=>"_run__1048083580144971540__initialize__3082064574212577540__callbacks"} {:method=>"name="} {:method=>"_run__1048083580144971540__initialize__3082064574212577540__callbacks"} {:method=>"name="} {:method=>"_run__1048083580144971540__initialize__3082064574212577540__callbacks"} {:method=>"name="} {:method=>"_run__1048083580144971540__initialize__3082064574212577540__callbacks"} {:method=>"name="} {:method=>"_run__1048083580144971540__initialize__3082064574212577540__callbacks"} {:method=>"name="} {:method=>"_run__1048083580144971540__initialize__3082064574212577540__callbacks"} {:method=>"name="} {:method=>"_run__1048083580144971540__initialize__3082064574212577540__callbacks"} Number of Doubts
127. Define Methods def define_attribute_methods .... @attribute_methods_mutex.synchronize do return if attribute_methods_generated? superclass.define_attribute_methods unless self == base_class super(column_names) column_names.each { |name| define_external_attribute_method(name) } @attribute_methods_generated = true end end
128. Define Methods def define_attribute_methods .... @attribute_methods_mutex.synchronize do return if attribute_methods_generated? superclass.define_attribute_methods unless self == base_class super(column_names) column_names.each { |name| define_external_attribute_method(name) } @attribute_methods_generated = true end end wtf???
129. RAWWWRRRR class A def hi(stuff) end end class B < A def hi super(%w{ problem? }) end end
130. :'( def calls_hi(obj) obj.hi(%w{ how are you? }) end calls_hi(A.new) # => OK! calls_hi(B.new) # => Boom!
131. IF THEN B is an A B can be used as an A
132. Number of Doubts
133. define_attribute_methods
134. ActiveModel
135. define_attribute_methods def define_attribute_methods(attr_names) attr_names.each { |attr_name| define_attribute_method(attr_name) } end
136. define_attribute_methods def define_attribute_methods(attr_names) attr_names.each { |attr_name| define_attribute_method(attr_name) } end THANKS ACTIVE MODEL
137. define_attribute_method def define_attribute_method(attr_name) ... unless instance_method_already_implemented?(method_name) generate_method = "define_method_#{matcher.method_missing_target}" if respond_to?(generate_method, true) send(generate_method, attr_name) else define_optimized_call generated_attribute_methods, method_name, matcher.method_missing_target, attr_name.to_s end end end
138. define_attribute_method def define_attribute_method(attr_name) ... unless instance_method_already_implemented?(method_name) generate_method = "define_method_#{matcher.method_missing_target}" if respond_to?(generate_method, true) send(generate_method, attr_name) else define_optimized_call generated_attribute_methods, method_name, matcher.method_missing_target, attr_name.to_s end end end
139. define_attribute_method def define_attribute_method(attr_name) ... unless instance_method_already_implemented?(method_name) generate_method = "define_method_#{matcher.method_missing_target}" if respond_to?(generate_method, true) send(generate_method, attr_name) else define_optimized_call generated_attribute_methods, method_name, matcher.method_missing_target, attr_name.to_s end end end
140. define_attribute_method def define_attribute_method(attr_name) ... unless instance_method_already_implemented?(method_name) generate_method = "define_method_#{matcher.method_missing_target}" if respond_to?(generate_method, true) send(generate_method, attr_name) else define_optimized_call generated_attribute_methods, method_name, matcher.method_missing_target, attr_name.to_s end end end
141. define_attribute_method def define_attribute_method(attr_name) ... unless instance_method_already_implemented?(method_name) generate_method = "define_method_#{matcher.method_missing_target}" if respond_to?(generate_method, true) send(generate_method, attr_name) else define_optimized_call generated_attribute_methods, method_name, matcher.method_missing_target, attr_name.to_s end end end
142. WHY AREN'T THEY ALL OPTIMIZED????
143. define_method_attribute define_method_attribute= define_method_attribute_before_type_cast define_method_attribute? define_method_attribute_changed? define_method_attribute_change define_method_attribute_will_change! define_method_attribute_was define_method_reset_attribute! define_method__attribute define_method_attribute define_method_attribute= define_method_attribute_before_type_cast define_method_attribute? define_method_attribute_changed? define_method_attribute_change define_method_attribute_will_change! define_method_attribute_was define_method_reset_attribute! define_method__attribute
144. define_method_attribute define_method_attribute= define_method_attribute_before_type_cast define_method_attribute? define_method_attribute_changed? define_method_attribute_change define_method_attribute_will_change! define_method_attribute_was define_method_reset_attribute! define_method__attribute define_method_attribute define_method_attribute= define_method_attribute_before_type_cast define_method_attribute? define_method_attribute_changed? define_method_attribute_change define_method_attribute_will_change! define_method_attribute_was define_method_reset_attribute! define_method__attribute
145. define_method_attribute define_method_attribute= define_method_attribute_before_type_cast define_method_attribute? define_method_attribute_changed? define_method_attribute_change define_method_attribute_will_change! define_method_attribute_was define_method_reset_attribute! define_method__attribute define_method_attribute define_method_attribute= define_method_attribute_before_type_cast define_method_attribute? define_method_attribute_changed? define_method_attribute_change define_method_attribute_will_change! define_method_attribute_was define_method_reset_attribute! define_method__attribute
146. define_method_attribute define_method_attribute= define_method_attribute_before_type_cast define_method_attribute? define_method_attribute_changed? define_method_attribute_change define_method_attribute_will_change! define_method_attribute_was define_method_reset_attribute! define_method__attribute define_method_attribute define_method_attribute= define_method_attribute_before_type_cast define_method_attribute? define_method_attribute_changed? define_method_attribute_change define_method_attribute_will_change! define_method_attribute_was define_method_reset_attribute! define_method__attribute THANKS ACTIVE MODEL
147. Number of Doubts
148. Side Note: Does anyone USE this?
149. Side Note: Should you use this?
150. Where were we?
151. Post.new respond_to? AR define_attr_methods AM define_attr_methods AM define_attr_method AR define_method_attr
152. In VIM •Ctrl-] •Ctrl-o •:help ctags
153. def define_method_attribute(attr_name) generated_attribute_methods.module_eval <<-STR, __FILE__, __LINE__ + 1 def __temp__ #{internal_attribute_access_code(attr_name, attribute_cast_code(attr_name))} end alias_method '#{attr_name}', :__temp__ undef_method :__temp__ STR end
154. method(:name).source
155. Type Cast Value Lookup post.method(:title).source
156. Post#name def name attr_name = 'name' unless @attributes.has_key?(attr_name) missing_attribute(attr_name, caller) end v = @attributes[attr_name] && v end
157. Post#name def name attr_name = 'name' unless @attributes.has_key?(attr_name) missing_attribute(attr_name, caller) end v = @attributes[attr_name] && v end SEEMS LEGIT
158. Post#created_at def created_at attr_name = 'created_at' unless @attributes.has_key?(attr_name) @attributes_cache[attr_name] ||= (missing_attribute(attr_name, caller) end (v=@attributes[attr_name]) && ActiveRecord::ConnectionAdapters::SQLiteColumn.string_to_time(v)) end
159. Post#created_at def created_at attr_name = 'created_at' unless @attributes.has_key?(attr_name) @attributes_cache[attr_name] ||= (missing_attribute(attr_name, caller) end (v=@attributes[attr_name]) && ActiveRecord::ConnectionAdapters::SQLiteColumn.string_to_time(v)) end DOUBTS INCREASING
160. attribute_cast_code def attribute_cast_code(attr_name) columns_hash[attr_name].type_cast_code('v') end
161. type_cast_code def type_cast_code(var_name) klass = self.class.name case type when :string, :text then var_name when :integer then "(#{var_name}.to_i rescue #{var_name} ? 1 : 0)" when :float then "#{var_name}.to_f" when :decimal then "#{klass}.value_to_decimal(#{var_name})" when :datetime, :timestamp then "#{klass}.string_to_time(#{var_name})" when :time then "#{klass}.string_to_dummy_time(#{var_name})" when :date then "#{klass}.string_to_date(#{var_name})" when :binary then "#{klass}.binary_to_string(#{var_name})" when :boolean then "#{klass}.value_to_boolean(#{var_name})" else var_name end end
162. type_cast def type_cast(value) return nil if value.nil? return coder.load(value) if encoded? klass = self.class case type when :string, :text then value when :integer then value.to_i rescue value ? 1 : 0 when :float then value.to_f when :decimal then klass.value_to_decimal(value) when :datetime, :timestamp then klass.string_to_time(value) when :time then klass.string_to_dummy_time(value) when :date then klass.string_to_date(value) when :binary then klass.binary_to_string(value) when :boolean then klass.value_to_boolean(value) else value end end
163. Number of Doubts
164. Number of Doubts TOO MANY!
165. HOWTO FIX?
166. What do we want? •Less dynamic code •Consistent method definitions •Matching speed (even on read_attribute)
167. What does it do? •Attribute lookup •Column lookup •Value typecasting •Typecast value caching
168. def read_attribute(attr_name) # If it's cached, just return it @attributes_cache.fetch(attr_name.to_s) { |name| column = @columns_hash[name] value = @attributes.fetch(name) { return attribute_missing(name, caller) } # Cache if we're supposed to if self.class.cache_attribute?(name) @attributes_cache[name] = column.type_cast(value) else column.type_cast value end } end
169. def name read_attribute 'name' end Post#name
170. def created_at read_attribute 'created_at' end Post#created_at
171. BONUS FEATURE! Post.select('true as hi').first.hi # => true
174. Clean Code IS A FEATURE
175. Don't throw out the baby with the bathwater!
176. Questions? ὑ ὑ ὑ ὑ ὑ ὑ