How to Fix Slow Code in Ruby - scir_full_example_benchmark.rb

scir_full_example_benchmark.rb

# frozen_string_literal: true

require "bundler/inline"

gemfile(true) do
  source "https://rubygems.org"
  gem "benchmark-ips"
  gem "rails"
  gem "sqlite3"
end

require "rails"
require "active_record"
require "benchmark/ips"

Rails.cache = ActiveSupport::Cache::MemoryStore.new
ActiveRecord::Base.establish_connection(adapter: "sqlite3", database: ":memory:")

ActiveRecord::Schema.define do
  create_table :line_items do |t|
    t.string :name
    t.decimal :price
    t.references :order
  end

  create_table :orders do |t|
  end
end

class LineItem < ActiveRecord::Base
  belongs_to :order
end

class Order < ActiveRecord::Base
  has_many :line_items

  def price
    line_items.pluck(:price).sum
  end
end

class OrderWithCachedPrice < Order
  def price
    Rails.cache.fetch("order_#{id}_total") { super }
  end
end

order = Order.first_or_create!
order.line_items.create!(name: "Rocket Shoes", price: 97.98)
order.line_items.create!(name: "Invisible Ink", price: 5.67)
order.line_items.create!(name: "Ray Gun", price: 1_235.97)
order.line_items.create!(name: "Chunky Bacon", price: 8.99)
order_with_cache = OrderWithCachedPrice.first

Benchmark.ips do |x|
  x.report("before") { order.price }
  x.report("after") { order_with_cache.price }

  x.compare!
end