Rails Four - Speaker Deck

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Thursday, June 7, 12

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Thank You Magma Rails Thursday, June 7, 12

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Aaron Patterson @tenderlove Thursday, June 7, 12

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Señor Software Engineer Thursday, June 7, 12

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ruby core rails core Thursday, June 7, 12

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WWFMD? Thursday, June 7, 12

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Rails Four For you and me! Thursday, June 7, 12

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New Features! Thursday, June 7, 12

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Bells & Whistles Thursday, June 7, 12

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Problems & Solutions Thursday, June 7, 12

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How Rails Core Works. Thursday, June 7, 12

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*opinions expressed here do not reﬂect the rest of the rails core team! :-P Thursday, June 7, 12

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The Plan: Thursday, June 7, 12

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There is no plan. Thursday, June 7, 12

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Features •Someone commits it •We might talk about it •It doesn’t get reverted Thursday, June 7, 12

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Reverts •We discuss and it seems bad •People complain •DHH doesn’t like it Thursday, June 7, 12

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How can I get a new feature? Thursday, June 7, 12

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Send a pull request Thursday, June 7, 12

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Email rails-core Thursday, June 7, 12

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Prerequisite Thursday, June 7, 12

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Concurrency in MRI Thursday, June 7, 12

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CPU Thursday, June 7, 12

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I / O Thursday, June 7, 12

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GVL Thursday, June 7, 12

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CPU Concurrency Thursday, June 7, 12

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def fib(n) if n < 3 1 else fib(n-1) + fib(n-2) end end 4.times { fib(34) } Thursday, June 7, 12

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$ time ruby benchmark/bm_app_fib.rb real 0m10.327s user 0m10.225s sys 0m0.018s $ Thursday, June 7, 12

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$ time ruby benchmark/bm_app_fib.rb real 0m10.327s user 0m10.225s sys 0m0.018s $ Thursday, June 7, 12

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def fib(n) if n < 3 1 else fib(n-1) + fib(n-2) end end 4.times.map { Thread.new { fib(34) } }.each(&:join) Thursday, June 7, 12

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$ time ruby benchmark/bm_app_fib.rb real 0m9.486s user 0m9.212s sys 0m0.034s $ Thursday, June 7, 12

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$ time ruby benchmark/bm_app_fib.rb real 0m9.486s user 0m9.212s sys 0m0.034s $ Thursday, June 7, 12

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CPU CPU Thursday, June 7, 12

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CPU CPU Thread Thread Thursday, June 7, 12

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CPU CPU Thread Thread Thread ??? Thursday, June 7, 12

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CPU is a Resource Thursday, June 7, 12

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CPU CPU Thursday, June 7, 12

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CPU Thursday, June 7, 12

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CPU Thread Thread ??? Thursday, June 7, 12

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I / O Concurrency Thursday, June 7, 12

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Slow Mail Server server = GenericServer.new('127.0.0.1', 28561, 5) server.start do |socket| sleep 0.5 socket.print "HELLO" socket.close end Thursday, June 7, 12

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Slow Mail Server server = GenericServer.new('127.0.0.1', 28561, 5) server.start do |socket| sleep 0.5 socket.print "HELLO" socket.close end Thursday, June 7, 12

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Slow Mail Server server = GenericServer.new('127.0.0.1', 28561, 5) server.start do |socket| sleep 0.5 socket.print "HELLO" socket.close end Thursday, June 7, 12

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Mail Client require 'socket' 5.times { sock = TCPSocket.new '127.0.0.1', 28561 puts sock.read } Thursday, June 7, 12

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$ time ruby client.rb HELLO HELLO HELLO HELLO HELLO real 0m2.555s user 0m0.029s sys 0m0.011s Thursday, June 7, 12

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require 'socket' 5.times.map { Thread.new { sock = TCPSocket.new '127.0.0.1', 28561 puts sock.read } }.each(&:join) Mail Client Thursday, June 7, 12

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$ time ruby client.rb HELLO HELLO HELLO HELLO HELLO real 0m0.556s user 0m0.028s sys 0m0.011s Thursday, June 7, 12

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1. Release GVL 2. Wait until data is available (select()) 3. Acquire GVL What Happened? Thursday, June 7, 12

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Not Just for Clients Thursday, June 7, 12

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Small Trick Thursday, June 7, 12

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Generate Keys require 'openssl' 5.times.map { OpenSSL::PKey::RSA.generate 5000 } Thursday, June 7, 12

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Generate Keys require 'openssl' 5.times.map { Thread.new { OpenSSL::PKey::RSA.generate 5000 } }.each(&:join) Thursday, June 7, 12

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What Happened? 1. Release GVL 2. Perform CPU only key generation 3. Acquire GVL Thursday, June 7, 12

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Threads are for managing resources Thursday, June 7, 12

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A locked interpreter is a locked interpreter Thursday, June 7, 12

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Be wary of libraries that boast Thursday, June 7, 12

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Understand Threads. Do not fear them. Thursday, June 7, 12

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Problem: Email Thursday, June 7, 12

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Action Mailer Thursday, June 7, 12

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class UsersController < ApplicationController def create @user = User.new(params[:user]) respond_to do |format| if @user.save # Send Email UserMailer.deliver_welcome_email(@user) end end end end Thursday, June 7, 12

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Create User Send Email Render View Thursday, June 7, 12

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Create User Send Email Render View Thursday, June 7, 12

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Create User Send Email Render View Thursday, June 7, 12

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Best case: Wasted user’s time Thursday, June 7, 12

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Worst case: Lose data and user Thursday, June 7, 12

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What do we do? Thursday, June 7, 12

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class UsersController < ApplicationController MAIL_QUEUE = ::Queue.new Thread.new { while work = MAIL_QUEUE.pop work.run end } def create @user = User.new(params[:user]) respond_to do |format| if @user.save MAIL_QUEUE.push UserMailer.new(@user) end end end end Thursday, June 7, 12

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Create User Render View Send Email Thursday, June 7, 12

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Create User Render View Send Email Thursday, June 7, 12

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Queue Issues •Not persistent •CPU intensive tasks •Cannot distribute to other machines Thursday, June 7, 12

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Queueing Libraries •Resque •Queue Classic •Sidekiq •DelayedJob •AMQP Thursday, June 7, 12

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•Queue#push •Job#run We wrote: Thursday, June 7, 12

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If your API is inconsistent, you’re gonna have a bad time Thursday, June 7, 12

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Rails Queue* *not sure if this name is ﬁnal Thursday, June 7, 12

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# app code Rails.queue.push SendEmail.new(user) # consumer while job = queue.pop job.run # SendEmail#run end Thursday, June 7, 12

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What’s the win? Thursday, June 7, 12

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class PeopleControllerTest < ActionController::TestCase fixtures :people def test_create_success assert_difference('Person.count') do assert_difference('Rails.queue.length') do post :create, :person => { :name => 'hi!', :password => 'lolwut', :password_confirmation => 'lolwut', :email => 'zomgwut' } end end assert_redirected_to '/' end end Thursday, June 7, 12

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Enforce Consistent API Thursday, June 7, 12

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Problem: Streaming Thursday, June 7, 12

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API Responses Thursday, June 7, 12

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Reducing time to ﬁrst byte Thursday, June 7, 12

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Streaming with Rack Thursday, June 7, 12

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class StreamingApplication def call(env) [200, {}, ["hello world"]] end end Thursday, June 7, 12

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class StreamingApplication class Body def each yield "hello" yield " world" end end def call(env) [200, { }, Body.new] end end Thursday, June 7, 12

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What about Content-Length? Thursday, June 7, 12

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use Rack::Chunked Thursday, June 7, 12

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class StreamingApplication class Body def each yield "hello" yield " world\n" end end def call(env) [200, {'Content-Type' => 'text/plain'}, Body.new] end end use Rack::Chunked run StreamingApplication.new Thursday, June 7, 12

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Let’s make it inﬁnite! Thursday, June 7, 12

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class StreamingApplication class Body < Struct.new(:q) def each while chunk = q.pop yield chunk end end end def call(env) q = Queue.new # A half second timer timer = Thread.new { loop { q.push "chunk\n" sleep 0.5 } } [200, {'Content-Type' => 'text/plain'}, Body.new(q)] end end Thursday, June 7, 12

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Thursday, June 7, 12

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Time until our ﬁrst byte. Thursday, June 7, 12

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class StreamingApplication class Body def each yield HTML_HEADER sleep 0.5 yield HTML_REST end end def call(env) [200, {'Content-Type' => 'text/html'}, Body.new] end end Thursday, June 7, 12

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Thursday, June 7, 12

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Our tools •Ruby •Rack •Unicorn Thursday, June 7, 12

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Small Detour: Rack as node.js Thursday, June 7, 12

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Sample App http = require('http'); http.createServer(function(req, res) { res.writeHead(200, 'Content-Type': 'text/plain') for(var i = 0; i < 10; i++) { res.chunk("Hello world\n") } res.end("Goodbye world\n") }); Thursday, June 7, 12

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In Ruby use Rack::Chunked run createServer { |req, res| res.writeHead(200, {'Content-Type' => 'text/plain'}) 10.times do res.chunk "Hello world\n" sleep 0.5 end res.end "Goodbye World\n" } Thursday, June 7, 12

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Adapter App class Adapter def initialize block @block = block end def call env resp = Response.new Thread.new { @block.call(env, resp) } # Wait for the child thread to write the header resp.await_header [resp.code, resp.header, resp] end end Thursday, June 7, 12

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Response class Response attr_reader :code, :header def initialize @header_written = Latch.new @q = Queue.new @code = 200 @header = {} end def await_header @header_written.await end def writeHead code, header @code = code @header = header @header_written.release end end Thursday, June 7, 12

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Response pt 2 class Response ## # Called from a child thread def chunk string @q.push string end ## # Called from a child thread def end string @q.push string @q.push nil end ## # Consumed in the main thread def each while part = @q.pop yield part end end end Thursday, June 7, 12

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Final piece def createServer &block Adapter.new block end Thursday, June 7, 12

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Thursday, June 7, 12

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If the socket was available, threads could go away Thursday, June 7, 12

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Streaming in Rails? Thursday, June 7, 12

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In a Controller class UsersController < ApplicationController def index self.response_body = ["hello world"] end end Thursday, June 7, 12

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Rendering a template class UsersController < ApplicationController def index render :stream => true end end Thursday, June 7, 12

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I don’t like it Thursday, June 7, 12

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Rails Four class UsersController < ApplicationController def index # written to the socket response.body.write "hello" response.body.write " world\n" end end M y W ish! Thursday, June 7, 12

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Rails Four class UsersController < ApplicationController def index File.open('from aws') do |f| f.each_line do |line| response.body.puts line end end end end M y W ish! Thursday, June 7, 12

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Problem: Data Types Thursday, June 7, 12

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`create table users` class User 1:1 Active Record Thursday, June 7, 12

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Active Record $ ruby script/rails c Loading development environment (Rails 4.0.0.beta) irb(main):001:0> User.columns.map { |c| [c.name, c.type] } => [["id", :integer], ["name", :string], ["email", :string], ["password_digest", :string], ["created_at", :timestamp], ["updated_at", :timestamp]] Thursday, June 7, 12

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Column Class class ARBase class Column < Struct.new(:name, :type) def type_cast value case type when 'integer' then value.to_i when 'varchar(255)' then value.to_s when 'text' then value.to_s end end end end Thursday, June 7, 12

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class ARBase def self.columns table @cache[table] ||= conn.execute("PRAGMA table_info(#{table})").map { |row| Column.new(row[1], row[2]) } end def self.find id stmt = ARBase.conn.prepare( "SELECT * FROM #{table_name} WHERE id = ?" ) rs = stmt.execute id new Hash[columns(table_name).zip(rs.first)] end end Thursday, June 7, 12

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class ARBase def initialize record @record = record end def method_missing column column = self.class.columns(table_name).find { |c| c.name == column.to_s } column.type_cast @record[column.to_s] end end Type Casting Thursday, June 7, 12

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Finder class ARBase def self.columns table @cache[table] ||= conn.execute("PRAGMA table_info(#{table})").map { |row| Column.new(row[1], row[2]) } end def self.find id stmt = ARBase.conn.prepare( "SELECT * FROM people WHERE id = ?" ) rs = stmt.execute id new Hash[rs.columns.zip(rs.first)] end end Thursday, June 7, 12

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SELECT name AS nickname .... SELECT 10 AS name .... Thursday, June 7, 12

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What do we do? Thursday, June 7, 12

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SELECT * Cache Type Type Type Type Thursday, June 7, 12

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SELECT name AS nickname .... SELECT 10 AS name .... Thursday, June 7, 12

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Column types require 'pg' conn = PG.connect 'dbname' => 'activerecord_unittest' rs = conn.exec 'SELECT * FROM posts' rs.fields.each_with_index do |fname, i| p [fname, rs.ftype(i), rs.fmod(i)] end Thursday, June 7, 12

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New Finder class ARBase def self.find id stmt = ARBase.conn.prepare( "SELECT * FROM #{table_name} WHERE id = ?" ) rs = stmt.execute id values = Hash[rs.columns.zip(rs.first)] types = {} rs.fields.each_with_index do |fname, i| types[fname] = type_cache(rs.ftype(i), rs.fmod(i)) end new(values, types) end end Thursday, June 7, 12

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New Casting class ARBase def initialize record, types @record = record @types = types end def method_missing column @types[column].type_cast @record[column] end end Thursday, June 7, 12

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Data types in Rails? Thursday, June 7, 12

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post = Post.new(:title => 'hello!') post.title # => 'hello!' post.respond_to?(:title) # => true Attribute Access Thursday, June 7, 12

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Lazily Deﬁned begin p Post.instance_method(:name) rescue NameError puts "oh no!" end Post.new(:name => 'aaron') p Post.instance_method(:name) Thursday, June 7, 12

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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 Thursday, June 7, 12

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puts caller {:method=>"name="} ########################################################################################## lib/active_record/attribute_assignment.rb:81:in `block in assign_attributes' lib/active_record/attribute_assignment.rb:78:in èach' lib/active_record/attribute_assignment.rb:78:in àssign_attributes' lib/active_record/base.rb:498:in ìnitialize' test/cases/argh.rb:16:in `new' test/cases/argh.rb:16:in `' ########################################################################################## {: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 ìnitialize' test/cases/argh.rb:16:in `new' test/cases/argh.rb:16:in `' ########################################################################################## Thursday, June 7, 12

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after_initialize class Subject < ActiveRecord::Base after_initialize :set_email_address protected def set_email_address ... end end Thursday, June 7, 12

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use super? class Subject < ActiveRecord::Base def initialize(*args) super set_email_address # after_init end protected def set_email_address ... end end Thursday, June 7, 12

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10.times { Post.new(:name => 'aaron') } Thursday, June 7, 12

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I digress... Thursday, June 7, 12

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method(:name).source Thursday, June 7, 12

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Value Lookup Type Cast Thursday, June 7, 12

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Value Lookup Type Cast Thursday, June 7, 12

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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 Thursday, June 7, 12

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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 Thursday, June 7, 12

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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 Thursday, June 7, 12

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Method source depends on column type Thursday, June 7, 12

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Solution? Thursday, June 7, 12

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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 Rails 4 Thursday, June 7, 12

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def name read_attribute 'name' end def created_at read_attribute 'created_at' end Generated CodeRails 4 Thursday, June 7, 12

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Complex type support Rails 4 Thursday, June 7, 12

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class Person < ActiveRecord::Base end person = Person.new person.preferences = { 'color' => 'green' } HStore (PG) Rails 4 Thursday, June 7, 12

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With PG 9.2, JSON support Thursday, June 7, 12

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Problem: Fat Clients Thursday, June 7, 12

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The future of the web is mobile. Thursday, June 7, 12

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The future of the web is JavaScript. Thursday, June 7, 12

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The future is Fat Clients. Thursday, June 7, 12

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Economy Thursday, June 7, 12

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Broadband Thursday, June 7, 12

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Smart Phones Thursday, June 7, 12

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History Thursday, June 7, 12

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Centralized Thursday, June 7, 12

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D i s t r i b u t e d Thursday, June 7, 12

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Centralized Thursday, June 7, 12

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D i s t r i b u t e d Thursday, June 7, 12

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API Support Thursday, June 7, 12

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•JBuilder •ActiveModel::Serializer •... and more! API Solutions Thursday, June 7, 12