h1. Bullet !https://secure.travis-ci.org/flyerhzm/bullet.png!:http://travis-ci.org/flyerhzm/bullet !http://api.coderwall.com/flyerhzm/endorsecount.png!:http://coderwall.com/flyerhzm The Bullet gem is designed to help you increase your application's performance by reducing the number of queries it makes. It will watch your queries while you develop your application and notify you when you should add eager loading (N+1 queries), when you're using eager loading that isn't necessary and when you should use counter cache. Best practice is to use Bullet in development mode or custom mode (staging, profile, etc.). The last thing you want is your clients getting alerts about how lazy you are. The Bullet gem now supports **activerecord** 2.1, 2.2, 2.3, 3.0, 3.1, 3.2 and **mongoid** >= 2.4.1. **************************************************************************** h2. External Introduction * "http://railscasts.com/episodes/372-bullet":http://railscasts.com/episodes/372-bullet * "http://ruby5.envylabs.com/episodes/9-episode-8-september-8-2009":http://ruby5.envylabs.com/episodes/9-episode-8-september-8-2009 * "http://railslab.newrelic.com/2009/10/23/episode-19-on-the-edge-part-1":http://railslab.newrelic.com/2009/10/23/episode-19-on-the-edge-part-1 * "http://weblog.rubyonrails.org/2009/10/22/community-highlights":http://weblog.rubyonrails.org/2009/10/22/community-highlights **************************************************************************** h2. Install You can install it as a gem:


gem install bullet

or add it into a Gemfile (Bundler):


gem "bullet", :group => "development"

**************************************************************************** h2. Configuration Bullet won't do ANYTHING unless you tell it to explicitly. Append to config/environments/development.rb initializer with the following code:


config.after_initialize do
  Bullet.enable = true
  Bullet.alert = true
  Bullet.bullet_logger = true
  Bullet.console = true
  Bullet.growl = true
  Bullet.xmpp = { :account => 'bullets_account@jabber.org',
                  :password => 'bullets_password_for_jabber',
                  :receiver => 'your_account@jabber.org',
                  :show_online_status => true }
  Bullet.rails_logger = true
  Bullet.airbrake = true
end

The notifier of bullet is a wrap of "uniform_notifier":https://github.com/flyerhzm/uniform_notifier The code above will enable all seven of the Bullet notification systems: * Bullet.enable: enable Bullet gem, otherwise do nothing * Bullet.alert: pop up a JavaScript alert in the browser * Bullet.bullet_logger: log to the Bullet log file (Rails.root/log/bullet.log) * Bullet.rails_logger: add warnings directly to the Rails log * Bullet.airbrake: add notifications to airbrake * Bullet.console: log warnings to your browser's console.log (Safari/Webkit browsers or Firefox w/Firebug installed) * Bullet.growl: pop up Growl warnings if your system has Growl installed. Requires a little bit of configuration * Bullet.xmpp: send XMPP/Jabber notifications to the receiver indicated. Note that the code will currently not handle the adding of contacts, so you will need to make both accounts indicated know each other manually before you will receive any notifications. If you restart the development server frequently, the 'coming online' sound for the bullet account may start to annoy - in this case set :show_online_status to false; you will still get notifications, but the bullet account won't announce it's online status anymore. **************************************************************************** h2. Log The Bullet log log/bullet.log will look something like this: * N+1 Query:


2009-08-25 20:40:17[INFO] N+1 Query: PATH_INFO: /posts;    model: Post => associations: [comments]·
Add to your finder: :include => [:comments]
2009-08-25 20:40:17[INFO] N+1 Query: method call stack:·
/Users/richard/Downloads/test/app/views/posts/index.html.erb:11:in `_run_erb_app47views47posts47index46html46erb'
/Users/richard/Downloads/test/app/views/posts/index.html.erb:8:in `each'
/Users/richard/Downloads/test/app/views/posts/index.html.erb:8:in `_run_erb_app47views47posts47index46html46erb'
/Users/richard/Downloads/test/app/controllers/posts_controller.rb:7:in `index'

The first two lines are notifications that N+1 queries have been encountered. The remaining lines are stack traces so you can find exactly where the queries were invoked in your code, and fix them. * Unused eager loading:


2009-08-25 20:53:56[INFO] Unused eager loadings: PATH_INFO: /posts;    model: Post => associations: [comments]·
Remove from your finder: :include => [:comments]

These two lines are notifications that unused eager loadings have been encountered. * Need counter cache:


2009-09-11 09:46:50[INFO] Need Counter Cache
  Post => [:comments]

**************************************************************************** h2. Growl, XMPP/Jabber and Airbrake Support see "https://github.com/flyerhzm/uniform_notifier":https://github.com/flyerhzm/uniform_notifier **************************************************************************** h2. Important If you find bullet does not work for you, *please disable your browser's cache*. **************************************************************************** h2. Advance The bullet gem use rack middleware for http request. If you want to bullet for without http server, such as job server. You can do like this:


Bullet.start_request if Bullet.enable?
# run job
if Bullet.enable? && Bullet.notification?
  Bullet.perform_out_of_channel_notifications
end
Bullet.end_request if Bullet.enable?

Or you want to use it in test mode


before(:each)
  Bullet.start_request if Bullet.enable?
end

after(:each)
  if Bullet.enable? && Bullet.notification?
    Bullet.perform_out_of_channel_notifications
  end
  Bullet.end_request if Bullet.enable?
end

Don't forget enabling bullet in test environment. **************************************************************************** h2. Contributors "https://github.com/flyerhzm/bullet/contributors":https://github.com/flyerhzm/bullet/contributors **************************************************************************** h2. Step by step example Bullet is designed to function as you browse through your application in development. It will alert you whenever it encounters N+1 queries or unused eager loading. 1. setup test environment


$ rails new test_bullet
$ cd test_bullet
$ rails g scaffold post name:string
$ rails g scaffold comment name:string post_id:integer
$ bundle exec rake db:migrate

2. change app/model/post.rb and app/model/comment.rb


class Post < ActiveRecord::Base
  has_many :comments
end

class Comment < ActiveRecord::Base
  belongs_to :post
end

3. go to rails c and execute


post1 = Post.create(:name => 'first')
post2 = Post.create(:name => 'second')
post1.comments.create(:name => 'first')
post1.comments.create(:name => 'second')
post2.comments.create(:name => 'third')
post2.comments.create(:name => 'fourth')

4. change the app/views/posts/index.html.erb to produce a N+1 query


<% @posts.each do |post| %>
  
    <%= post.name %>
    <%= post.comments.map(&:name) %>
    <%= link_to 'Show', post %>
    <%= link_to 'Edit', edit_post_path(post) %>
    <%= link_to 'Destroy', post, :confirm => 'Are you sure?', :method => :delete %>
  
<% end %>

5. add bullet gem to Gemfile


gem "bullet"

And run

bundle install

6. enable the bullet gem in development, add a line to config/environments/development.rb


config.after_initialize do
  Bullet.enable = true
  Bullet.alert = true
  Bullet.bullet_logger = true
  Bullet.console = true
#  Bullet.growl = true
  Bullet.rails_logger = true
end

7. start server


$ rails s

8. input http://localhost:3000/posts in browser, then you will see a popup alert box says


The request has unused preload associations as follows:
None
The request has N+1 queries as follows:
model: Post => associations: [comment]

which means there is a N+1 query from post object to comments associations. In the meanwhile, there's a log appended into log/bullet.log file


2010-03-07 14:12:18[INFO] N+1 Query in /posts
  Post => [:comments]
  Add to your finder: :include => [:comments]
2010-03-07 14:12:18[INFO] N+1 Query method call stack
  /home/flyerhzm/Downloads/test_bullet/app/views/posts/index.html.erb:14:in `_render_template__600522146_80203160_0'
  /home/flyerhzm/Downloads/test_bullet/app/views/posts/index.html.erb:11:in `each'
  /home/flyerhzm/Downloads/test_bullet/app/views/posts/index.html.erb:11:in `_render_template__600522146_80203160_0'
  /home/flyerhzm/Downloads/test_bullet/app/controllers/posts_controller.rb:7:in `index'

The generated SQLs are


  Post Load (1.0ms)   SELECT * FROM "posts"
  Comment Load (0.4ms)   SELECT * FROM "comments" WHERE ("comments".post_id = 1)
  Comment Load (0.3ms)   SELECT * FROM "comments" WHERE ("comments".post_id = 2)

9. fix the N+1 query, change app/controllers/posts_controller.rb file


  def index
    @posts = Post.includes(:comments)

    respond_to do |format|
      format.html # index.html.erb
      format.xml  { render :xml => @posts }
    end
  end

10. refresh http://localhost:3000/posts page, no alert box and no log appended. The generated SQLs are


  Post Load (0.5ms)   SELECT * FROM "posts"
  Comment Load (0.5ms)   SELECT "comments".* FROM "comments" WHERE ("comments".post_id IN (1,2))

a N+1 query fixed. Cool! 11. now simulate unused eager loading. Change app/controllers/posts_controller.rb and app/views/posts/index.html.erb


  def index
    @posts = Post.includes(:comments)

    respond_to do |format|
      format.html # index.html.erb
      format.xml  { render :xml => @posts }
    end
  end


<% @posts.each do |post| %>
  
    <%= post.name %>
    <%= link_to 'Show', post %>
    <%= link_to 'Edit', edit_post_path(post) %>
    <%= link_to 'Destroy', post, :confirm => 'Are you sure?', :method => :delete %>
  
<% end %>

12. refresh http://localhost:3000/posts page, then you will see a popup alert box says


The request has unused preload associations as follows:
model: Post => associations: [comment]
The request has N+1 queries as follows:
None

In the meanwhile, there's a log appended into log/bullet.log file


2009-08-25 21:13:22[INFO] Unused preload associations: PATH_INFO: /posts;    model: Post => associations: [comments]·
Remove from your finder: :include => [:comments]

13. simulate counter_cache. Change app/controllers/posts_controller.rb and app/views/posts/index.html.erb


  def index
    @posts = Post.all

    respond_to do |format|
      format.html # index.html.erb
      format.xml  { render :xml => @posts }
    end
  end


<% @posts.each do |post| %>
  
    <%= post.name %>
    <%= post.comments.size %>
    <%= link_to 'Show', post %>
    <%= link_to 'Edit', edit_post_path(post) %>
    <%= link_to 'Destroy', post, :confirm => 'Are you sure?', :method => :delete %>
  
<% end %>

14. refresh http://localhost:3000/posts page, then you will see a popup alert box says


Need counter cache
  Post => [:comments]

In the meanwhile, there's a log appended into log/bullet.log file.


2009-09-11 10:07:10[INFO] Need Counter Cache
  Post => [:comments]