Content Caching in Rails Ahmad Gozali [email_address]

Ahmad Gozali

[email_address]

Content Cache Page cache Action cache Fragment cache

Page cache

Action cache

Fragment cache

Page Cache (1)‏ Easiest to use Fastest Worst scaling properties

Easiest to use

Fastest

Worst scaling properties

Page Cache (2)‏ Pages created by Rails as normal Written out to public directory Cached pages served directly by webserver without involking rails

Pages created by Rails as normal

Written out to public directory

Cached pages served directly by webserver without involking rails

Enable Page Caching class PostsController < ApplicationController caches_page :show cache_sweeper :posts_sweeper, :only => [:create, :update, :destroy] def show Post.find_by_id(params[:id])‏ end end

class PostsController < ApplicationController

caches_page :show

cache_sweeper :posts_sweeper, :only => [:create, :update, :destroy]

def show

Post.find_by_id(params[:id])‏

end

end

Sweepers Rails::Initializer.run do |config| # ... config.load_paths += %W( #{RAILS_ROOT}/app/sweepers )‏ # ... end

Rails::Initializer.run do |config|

# ...

config.load_paths += %W( #{RAILS_ROOT}/app/sweepers )‏

# ...

end

Expires Cache class PostsSweeper < ActionController::Caching::Sweeper observe Post def after_update(post)‏ expire_cache_for(post)‏ end ...

class PostsSweeper < ActionController::Caching::Sweeper

observe Post

def after_update(post)‏

expire_cache_for(post)‏

end

...

.htaccess RewriteRule ^$ index.html [QSA] RewriteRule ^([^.]+)$ $1.html [QSA] RewriteCond %{REQUEST_FILENAME} !-f RewriteRule ^(.*)$ dispatch.fcgi [QSA,L]

RewriteRule ^$ index.html [QSA]

RewriteRule ^([^.]+)$ $1.html [QSA]

RewriteCond %{REQUEST_FILENAME} !-f

RewriteRule ^(.*)$ dispatch.fcgi [QSA,L]

Action Caching Similar to page cache, but runs entirely inside of Rails Slower, because Rails is always involved Much less complex on the web server side; no mod_rewrite tricks Uses the fragment cache internally

Similar to page cache, but runs entirely inside of Rails

Slower, because Rails is always involved

Much less complex on the web server side; no mod_rewrite tricks

Uses the fragment cache internally

Example class PostsController < ApplicationController layout 'base' before_filter :authenticate caches_action :list, :show

class PostsController < ApplicationController

layout 'base'

before_filter :authenticate

caches_action :list, :show

Cleanup Action Cache expire_action(:controller => 'posts', :action => 'list')‏ expire_action(:controller => 'posts', :action => 'show', :id => record.id)‏

expire_action(:controller => 'posts', :action => 'list')‏

expire_action(:controller => 'posts', :action => 'show', :id => record.id)‏

Fragment Cache You have to call it yourself, because it works on short bits of data, not whole pages. read_fragment(key) and write_fragment(key,value)‏ Expire with expire_fragment(key) (or regex). No way to list entries.

You have to call it yourself, because it works on short bits of data, not whole pages.

read_fragment(key) and write_fragment(key,value)‏

Expire with expire_fragment(key) (or regex).

No way to list entries.

Example <strong>My Blog Posts</strong> <% cache do %> <ul> <% for post in @posts %> <li><%= link_to post.title, :controller => 'posts', :action => 'show', :id => post %></li> <% end %> </ul> <% end %>

<strong>My Blog Posts</strong>

<% cache do %>

<ul>

<% for post in @posts %>

<li><%= link_to post.title, :controller => 'posts', :action => 'show', :id => post %></li>

<% end %>

</ul>

<% end %>

Post Controllers def list unless read_fragment({})‏ @post = Post.find(:all, :order => 'created_on desc', :limit => 10) %> end end

def list

unless read_fragment({})‏

@post = Post.find(:all, :order => 'created_on desc', :limit => 10) %>

end

end

Expire Fragment Cache expire_fragment(:controller => 'post', :action => 'list')‏

expire_fragment(:controller => 'post', :action => 'list')‏

Demo