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Rails Page Caching


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Presentation given at the Feb '10 Nashville Ruby on Rails Meetup group.

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Rails Page Caching

  1. 1. Rails Page Caching <ul><li>Travis Roberts </li></ul><ul><li> </li></ul><ul><li> </li></ul>
  2. 2. Why Cache? <ul><li>Significantly speed up page load. </li></ul><ul><li>Reduce resource usage on server. </li></ul>
  3. 3. But, How Do We Do It? <ul><li>in config/environments/development.rb </li></ul><ul><li>in app/controllers/[controller_name].rb </li></ul><ul><li>in config/environment.rb </li></ul>config.action_controller.perform_caching = true caches_page :index, :show, :feed # Move the cached files into their own directory config.action_controller.page_cache_directory = RAILS_ROOT + &quot;/public/cache/&quot;
  4. 4. What About New Content? <ul><li>New content won’t show, so we have to expire the cache </li></ul><ul><li>in config/environment.rb </li></ul><ul><li>This tells the application to load our “sweepers” dir </li></ul><ul><li>We put the expire logic in the sweepers </li></ul>config.load_paths += %W( #{RAILS_ROOT}/app/sweepers )
  5. 5. Quick and Dirty Sweeper class SiteSweeper < ActionController::Caching::Sweeper observe Post, Comment def after_save (record) self.class::sweep end def after_destroy (record) self.class::sweep end def self.sweep cache_dir = ActionController :: Base .page_cache_directory unless cache_dir == RAILS_ROOT + &quot;/public&quot; FileUtils .rm_r( Dir .glob(cache_dir + &quot;/*&quot; )) rescue Errno ::ENOENT RAILS_DEFAULT_LOGGER .info( &quot;Cache directory fully swept.&quot; ) end end end
  6. 6. We Can Do Better <ul><li>in app/sweepers/post_sweeper.rb </li></ul>class PostSweeper < ActionController::Caching::Sweeper observe Post def after_save (post) expire_pages(post) end def after_destroy (post) expire_pages(post) end def expire_pages (post) expire_page(blog_path(:page => nil )) # expire blog index (/blog/list) expire_page(blog_path(post)) # expire detail page (/blog/12) # if we need to remove an entire directory in the cache cache_dir = ActionController :: Base .page_cache_directory FileUtils .rm_r( Dir .glob(cache_dir + &quot;/blog/list/*&quot; )) rescue Errno ::ENOENT # expire list RAILS_DEFAULT_LOGGER .info( &quot;Cache directory for blog successfully swept.&quot; ) end end
  7. 7. Calling the Sweeper <ul><li>We need to tell our controller when to invoke the sweeper </li></ul><ul><li>in app/controllers/post_controller.rb </li></ul>class Manage::PostsController < ApplicationController cache_sweeper :post_sweeper, :only => [:create, :update, :destroy] # other code... end
  8. 8. Tell the Server to Use Cache <ul><li>Add the following lines to your .conf file </li></ul># Rewrite index to check for static index RewriteRule ^/$ /cache/index.html [QSA] # Rewrite to check for cached pages RewriteRule ^([^.]+)$ /cache/$1.html [QSA]
  9. 9. What about pagination? <ul><li>With default pagination, caching won’t work ( </li></ul><ul><li>We need to add a route for caching </li></ul>map.blog_list 'blog/list/:page' , :controller => 'blog' , :action => 'index' , :requirements => { :page => / d +/ }, :page => nil # This will add the following routes # blog_list_path => # blog_list_path(:page => 3) =>
  10. 10. The End! <ul><li>Questions? </li></ul><ul><li>Comments? </li></ul>