Background Workers

background_workers.markdown

##Introduction to Background Workers

#####Repository

git clone https://github.com/turingschool-examples/loremore.git background_workers

rails 4.2 added ActiveJob

whenever gem

Heroku scheduler

###Procedure

• Overall overview.
• Explain what a background worker is.
• Explain what is a job.
• Explore the app.
• Click on generate quotes and observe the delay.
• Create Job.
• Run rails g job generate_quotes.
• Explain the structure of a job class.
• Replace controller code with job.
• Explain that if an adapter is not set the job is performed immediately.
• Add Adapter.
• Add sidekiq gem.
• Add config.active_job.queue_adapter = :sidekiq to application.rb.
• Add require ‘sidekiq/web’ to routes.rb.
• Add mount Sidekiq::Web, at: ‘/sidekiq’ to routes.
• Add gem sinatra to Gemfile.
• Start workers.
• Restart the server and open the dashboard (go to /sidekiq).
• Launch sidekiq with bundle exec sidekiq.

Workshop 1: Queue Quotes

• Scheduling a job.
• Use .set(wait: 1.minute) in job.
• use .set(wait_until: Time.current.next_week) in job.
• Show the dashboard.
• Foreman
• Add gem.
• Create Procfile.
• Add web and workers process.
• Run foreman start.

Workshop

Workshop 1: Creating a Job

Right now, the book titles are generated synchronously and the user perceives a delay. Open the BooksController and find the Book.generate method. Can you create a job that would handle this method?

Implementation

app/jobs/generate_quotes_job.rb

class GenerateQuotesJob < ActiveJob::Base
  queue_as :default

  def perform
    Quote.generate
  end
end

app/controllers/quotes_controller.rb

class QuotesController < ApplicationController
  def index
    @quotes = Quote.all
  end

  def create
    GenerateQuotesJob.set(wait_until: Time.current.next_week).perform_later

   redirect_to :back, success: 'The quotes were generated successfully.'
  end
end

app/config/routes.rb

require 'sidekiq/web'

Rails.application.routes.draw do
  mount Sidekiq::Web, at: '/sidekiq'

  root 'site#show'

  resources :books,  only: [:index, :create]
  resources :quotes, only: [:index, :create]
end

Gemfile

source 'https://rubygems.org'

gem 'rails', '4.2.4'
gem 'sqlite3'
gem 'sass-rails', '~> 5.0'
gem 'uglifier', '>= 1.3.0'
gem 'coffee-rails', '~> 4.1.0'
gem 'jquery-rails'
gem 'turbolinks'
gem 'jbuilder', '~> 2.0'
gem 'bootstrap-sass', '~> 3.3.5'
gem 'faker', '~> 1.5.0'
gem 'sidekiq', '~> 3.5.0'
gem 'sinatra'
gem 'foreman'

group :development, :test do
  gem 'pry'
  gem 'better_errors'
  gem 'binding_of_caller'
end

Procfile

web: bundle exec rails s
workers: bundle exec sidekiq