Make an Event of It! - Speaker Deck

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Jason Clark @jasonrclark Ruby Agent Engineer Make an Event of It! Evented Patterns in Ruby Tuesday, April 22, 14

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Storytime! Tuesday, April 22, 14

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Tuesday, April 22, 14

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Tuesday, April 22, 14

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class UsersController < ApplicationController def create @user = User.new(user_params) if @user.save redirect_to @user else render 'new' end end end Tuesday, April 22, 14

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class UsersController < ApplicationController def create @user = User.new(user_params) if @user.save UserMailer.welcome_email(@user).deliver redirect_to @user ... end end end Tuesday, April 22, 14

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class UsersController < ApplicationController def create @user = User.new(user_params) if @user.save UserMailer.welcome_email(@user).deliver Analytics.notify_user_creation(@user) redirect_to @user ... end end end Tuesday, April 22, 14

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class UsersController < ApplicationController def create @user = User.new(user_params) if @user.save UserMailer.welcome_email(@user).deliver Analytics.notify_user_creation(@user) Crm::Gateway.new(@user.id, @user.name, ...) redirect_to @user ... end end end Tuesday, April 22, 14

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class UsersController < ApplicationController def create @user = User.new(user_params) if @user.save UserMailer.welcome_email(@user).deliver Analytics.notify_user_creation(@user) Crm::Gateway.new(@user.id, @user.name, ...) Resque.enqueue(AlertTheSocials, @user.id) redirect_to @user ... end end end Tuesday, April 22, 14

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class UsersController < ApplicationController def create @user = User.new(user_params) if @user.save UserMailer.welcome_email(@user).deliver Analytics.notify_user_creation(@user) Crm::Gateway.new(@user.id, @user.name, ...) Resque.enqueue(AlertTheSocials, @user.id) redirect_to @user ... end end end Tuesday, April 22, 14

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https://ﬂic.kr/p/6qdTC1 Tuesday, April 22, 14

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Where Are We Going? The Pattern Coupling Mechanics Responsibilities 12 Tuesday, April 22, 14

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The Pattern http://ﬂic.kr/p/6K9jC4 Tuesday, April 22, 14

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14 Tuesday, April 22, 14

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15 Tuesday, April 22, 14

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15 Tuesday, April 22, 14

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15 Tuesday, April 22, 14

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Events Aren't (Necessarily) 16 Asynchronous IO related Distributed Complicated Tuesday, April 22, 14

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17 Tuesday, April 22, 14

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17 Notiﬁer Tuesday, April 22, 14

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17 Notiﬁer Subscriber Subscriber Subscriber Tuesday, April 22, 14

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17 Notiﬁer Subscriber Subscriber Subscriber Eventing System Tuesday, April 22, 14

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17 Notiﬁer Subscriber Subscriber Subscriber Eventing System Tuesday, April 22, 14

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17 Notiﬁer Subscriber Subscriber Subscriber Eventing System Tuesday, April 22, 14

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18 Why Not Methods? Tuesday, April 22, 14

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19 Notiﬁer Subscriber Subscriber Subscriber Eventing System Tuesday, April 22, 14

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Why Not Callbacks? 20 Tuesday, April 22, 14

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21 class Subscription < ActiveRecord::Base before_create :record_signup private def record_signup self.signed_up_on = Date.today end end Tuesday, April 22, 14

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21 class Subscription < ActiveRecord::Base before_create :record_signup private def record_signup self.signed_up_on = Date.today end end Tuesday, April 22, 14

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Where Are We Going? The Pattern Coupling Mechanics Responsibilities 22 Tuesday, April 22, 14

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23 Internal Coupling http://ﬂic.kr/p/KikA9 Tuesday, April 22, 14

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newrelic_rpm 24 Tuesday, April 22, 14

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newrelic_rpm 24 app start Tuesday, April 22, 14

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newrelic_rpm 24 app start connect() New Relic Server Tuesday, April 22, 14

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newrelic_rpm {server conﬁg} 24 app start connect() New Relic Server Tuesday, April 22, 14

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newrelic_rpm {server conﬁg} 24 app start connect() New Relic Server ? Tuesday, April 22, 14

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newrelic_rpm 25 def connect() config = config_from_server() finish_setup(config) end Tuesday, April 22, 14

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newrelic_rpm 26 def finish_setup(config) add_naming_rule(config['rules']) @cross_app_tracing.set_key(config) @js_instrumentor.log_config(config) @beacon = Beacon.new end Tuesday, April 22, 14

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newrelic_rpm 27 def test_finish_setup_naming_rules config = { 'rules' => [...] } @agent.finish_setup(config) assert_equal 2, @agent.transaction_rules.size end Tuesday, April 22, 14

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28 def test_finish_setup_naming_rules @agent.cross_app_tracing.stub(:set_key) @agent.js_instrumentor.stub(:log_config) config = { 'rules' => [...] } @agent.finish_setup(config) assert_equal 2, @agent.transaction_rules.size end newrelic_rpm Tuesday, April 22, 14

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29 def finish_setup(config) add_naming_rule(config['rules']) @cross_app_tracing.set_key(config) @js_instrumentor.log_config(config) @beacon = Beacon.new end newrelic_rpm Tuesday, April 22, 14

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30 def finish_setup(config) add_naming_rule(config['rules']) @cross_app_tracing.set_key(config) @js_instrumentor.log_config(config) @beacon = Beacon.new end newrelic_rpm Tuesday, April 22, 14

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31 class Beacon def initialize # Your code is bad and you should feel bad Net::HTTP.get("http://somewhere.com") end end newrelic_rpm Tuesday, April 22, 14

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32 def test_finish_setup_naming_rules @agent.cross_app_tracing.stub(:set_key) @agent.js_instrumentor.stub(:log_config) Beacon.stub(:new).return(stub("fake beacon")) config = { 'rules' => [...] } @agent.finish_setup(config) assert_equal 2, @agent.transaction_rules.size end newrelic_rpm Tuesday, April 22, 14

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33 def finish_setup(config) add_naming_rule(config['rules']) @cross_app_tracing.set_key(config) @js_instrumentor.log_config(config) @beacon = Beacon.new end newrelic_rpm Tuesday, April 22, 14

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34 def finish_setup(config) events.notify(:configured) end newrelic_rpm Tuesday, April 22, 14

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35 class Beacon def initialize events.subscribe(:configured) do Net::HTTP.get("http://...") end end end newrelic_rpm Tuesday, April 22, 14

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36 def test_finish_setup_notifies called = false @events.subscribe(:configured) do called = true end @agent.finish_setup({}) assert called end newrelic_rpm Tuesday, April 22, 14

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37 def test_add_naming_rules config = { 'rules' => [...] } @agent.add_naming_rules(config) assert_equal 2, @agent.transaction_rules.size end newrelic_rpm Tuesday, April 22, 14

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More Focused Tests 38 Tuesday, April 22, 14

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More Independent Classes 39 Tuesday, April 22, 14

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Domain Language 40 Tuesday, April 22, 14

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Implicit Ordering 41 Tuesday, April 22, 14

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Debugging 42 Tuesday, April 22, 14

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Performance 43 Tuesday, April 22, 14

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http://ﬂic.kr/p/euQpT External Coupling Tuesday, April 22, 14

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45 newrelic_rpm Tuesday, April 22, 14

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45 Javascript insertion newrelic_rpm Tuesday, April 22, 14

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45 Javascript insertion Error collection newrelic_rpm Tuesday, April 22, 14

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45 Javascript insertion Cross application tracing Error collection newrelic_rpm Tuesday, April 22, 14

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46 No Setup Please! newrelic_rpm Tuesday, April 22, 14

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47 module NewRelic::Rack class AgentHooks def call(env) notify(:before_call, env) result = @app.call(env) notify(:after_call, env, result) result end end end newrelic_rpm Tuesday, April 22, 14

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48 class CrossAppTracing def initialize events.subscribe(:before_call) do |e| process_request(e) end ... end end newrelic_rpm Tuesday, April 22, 14

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Ever Heard of Composition? 49 Tuesday, April 22, 14

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Looser Coupling 50 Tuesday, April 22, 14

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Compatibilty Layer 51 Tuesday, April 22, 14

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Where Are We Going? The Pattern Coupling Mechanics Responsibilities 52 Tuesday, April 22, 14

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http://ﬂic.kr/p/dYor95 Adding Eventing Tuesday, April 22, 14

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54 gem install simple_events http://github.com/jasonrclark/simple_events Tuesday, April 22, 14

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55 class SimpleEvents::Notifier def initialize @events = {} ... end end simple_events Tuesday, April 22, 14

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56 class SimpleEvents::Notifier ... def subscribe(event, &handler) @events[event] ||= [] @events[event] << handler check_for_runaway_subscriptions(event) end ... end simple_events Tuesday, April 22, 14

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57 class SimpleEvents::Notifier ... def notify(event, *args) return unless @events.has_key?(event) @events[event].each do |handler| begin handler.call(*args) rescue => err logger.debug("Fail #{@event}", err) end end end end simple_events Tuesday, April 22, 14

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58 class SimpleEvents::Notifier ... def notify(event, *args) return unless @events.has_key?(event) @events[event].each do |handler| begin handler.call(*args) rescue => err logger.debug("Fail #{@event}", err) end end end end simple_events Tuesday, April 22, 14

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59 class SimpleEvents::Notifier ... def notify(event, *args) return unless @events.has_key?(event) @events[event].each do |handler| begin handler.call(*args) rescue => err logger.debug("Fail #{@event}", err) end end end end simple_events Tuesday, April 22, 14

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60 class SimpleEvents::Notifier ... def notify(event, *args) return unless @events.has_key?(event) @events[event].each do |handler| begin handler.call(*args) rescue => err logger.debug("Fail #{@event}", err) end end end end simple_events Tuesday, April 22, 14

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61 class SimpleEvents::Notifier ... def notify(event, *args) return unless @events.has_key?(event) @events[event].each do |handler| begin handler.call(*args) rescue => err logger.debug("Fail #{@event}", err) end end end end simple_events Tuesday, April 22, 14

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ActiveSupport:: Notiﬁcations http://ﬂic.kr/p/aWNwU2 Tuesday, April 22, 14

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63 AS::Notifications = ActiveSupport::Notifications activesupport Tuesday, April 22, 14

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Typical Rails Request 64 • action_dispatch.request • start_processing.action_controller • process_action.action_controller • sql.active_record • render_template.action_view • ... and more! Tuesday, April 22, 14

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65 events = [] AS::Notifications.subscribe("event") do |*args| events << *args end ["render_template.action_view", "e2a1e92a3c613576c2b0" {:identifier=>"/file/path/here"}] activesupport Tuesday, April 22, 14

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66 e = AS::Notifications::Event.new(*args) e.name # => "render_template..." e.duration # => 10 (in milliseconds) e.payload # => { :identifier => ... } activesupport Tuesday, April 22, 14

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67 AS::Notifications.instrument("evt", :data => 1) activesupport Tuesday, April 22, 14

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68 AS::Notifications.instrument("evt", :data => 1) do # your timed code here end activesupport Tuesday, April 22, 14

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• Regexp on Notifications.subscribe • Event#parent_of? • Temporary subscription • Unsubscribe • LogSubscriber 69 activesupport Tuesday, April 22, 14

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Where Are We Going? The Pattern Coupling Mechanics Responsibilities 70 Tuesday, April 22, 14

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http://ﬂic.kr/p/a1dEec Notiﬁers Tuesday, April 22, 14

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Naming 72 Tuesday, April 22, 14

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Flexible Payload 73 Tuesday, April 22, 14

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Primitives at Boundaries 74 Tuesday, April 22, 14

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75 http://ﬂic.kr/p/8w9PyF Subscribers Tuesday, April 22, 14

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Who subscribes? 76 Tuesday, April 22, 14

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77 Tuesday, April 22, 14

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78 class UserSignup < Mutations::Command def execute user = User.create!(inputs) NewsletterSubscriptions.create(user.id) UserMailer.async(:deliver_welcome, user.id) user end end Tuesday, April 22, 14

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79 Nesting Tuesday, April 22, 14

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Synchronous 80 Tuesday, April 22, 14

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81 class SomeSubscriber def initialize events.subscribe(:configured) do log_config end end def log_config ... end end Leaks Tuesday, April 22, 14

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Where Are We Going? The Pattern Coupling Mechanics Responsibilities 82 Tuesday, April 22, 14

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The Pattern Coupling Mechanics Responsibilities ? Jason Clark @jasonrclark Ruby Agent Engineer Tuesday, April 22, 14