vendor/rails/actionpack/lib/action_controller/caching/pages.rb

   1 require 'fileutils'
   2 require 'uri'
   3
   4 module ActionController #:nodoc:
   5   module Caching
   6     # Page caching is an approach to caching where the entire action output of is stored as a HTML file that the web server
   7     # can serve without going through Action Pack. This is the fastest way to cache your content as opposed to going dynamically
   8     # through the process of generating the content. Unfortunately, this incredible speed-up is only available to stateless pages
   9     # where all visitors are treated the same. Content management systems -- including weblogs and wikis -- have many pages that are
  10     # a great fit for this approach, but account-based systems where people log in and manipulate their own data are often less
  11     # likely candidates.
  12     #
  13     # Specifying which actions to cache is done through the <tt>caches_page</tt> class method:
  14     #
  15     #   class WeblogController < ActionController::Base
  16     #     caches_page :show, :new
  17     #   end
  18     #
  19     # This will generate cache files such as <tt>weblog/show/5.html</tt> and <tt>weblog/new.html</tt>,
  20     # which match the URLs used to trigger the dynamic generation. This is how the web server is able
  21     # pick up a cache file when it exists and otherwise let the request pass on to Action Pack to generate it.
  22     #
  23     # Expiration of the cache is handled by deleting the cached file, which results in a lazy regeneration approach where the cache
  24     # is not restored before another hit is made against it. The API for doing so mimics the options from +url_for+ and friends:
  25     #
  26     #   class WeblogController < ActionController::Base
  27     #     def update
  28     #       List.update(params[:list][:id], params[:list])
  29     #       expire_page :action => "show", :id => params[:list][:id]
  30     #       redirect_to :action => "show", :id => params[:list][:id]
  31     #     end
  32     #   end
  33     #
  34     # Additionally, you can expire caches using Sweepers that act on changes in the model to determine when a cache is supposed to be
  35     # expired.
  36     module Pages
  37       def self.included(base) #:nodoc:
  38         base.extend(ClassMethods)
  39         base.class_eval do
  40           @@page_cache_directory = defined?(Rails.public_path) ? Rails.public_path : ""
  41           ##
  42           # :singleton-method:
  43           # The cache directory should be the document root for the web server and is set using <tt>Base.page_cache_directory = "/document/root"</tt>.
  44           # For Rails, this directory has already been set to Rails.public_path (which is usually set to <tt>RAILS_ROOT + "/public"</tt>). Changing
  45           # this setting can be useful to avoid naming conflicts with files in <tt>public/</tt>, but doing so will likely require configuring your
  46           # web server to look in the new location for cached files.
  47           cattr_accessor :page_cache_directory
  48
  49           @@page_cache_extension = '.html'
  50           ##
  51           # :singleton-method:
  52           # Most Rails requests do not have an extension, such as <tt>/weblog/new</tt>. In these cases, the page caching mechanism will add one in
  53           # order to make it easy for the cached files to be picked up properly by the web server. By default, this cache extension is <tt>.html</tt>.
  54           # If you want something else, like <tt>.php</tt> or <tt>.shtml</tt>, just set Base.page_cache_extension. In cases where a request already has an
  55           # extension, such as <tt>.xml</tt> or <tt>.rss</tt>, page caching will not add an extension. This allows it to work well with RESTful apps.
  56           cattr_accessor :page_cache_extension
  57         end
  58       end
  59
  60       module ClassMethods
  61         # Expires the page that was cached with the +path+ as a key. Example:
  62         #   expire_page "/lists/show"
  63         def expire_page(path)
  64           return unless perform_caching
  65
  66           benchmark "Expired page: #{page_cache_file(path)}" do
  67             File.delete(page_cache_path(path)) if File.exist?(page_cache_path(path))
  68           end
  69         end
  70
  71         # Manually cache the +content+ in the key determined by +path+. Example:
  72         #   cache_page "I'm the cached content", "/lists/show"
  73         def cache_page(content, path)
  74           return unless perform_caching
  75
  76           benchmark "Cached page: #{page_cache_file(path)}" do
  77             FileUtils.makedirs(File.dirname(page_cache_path(path)))
  78             File.open(page_cache_path(path), "wb+") { |f| f.write(content) }
  79           end
  80         end
  81
  82         # Caches the +actions+ using the page-caching approach that'll store the cache in a path within the page_cache_directory that
  83         # matches the triggering url.
  84         #
  85         # Usage:
  86         #
  87         #   # cache the index action
  88         #   caches_page :index
  89         #
  90         #   # cache the index action except for JSON requests
  91         #   caches_page :index, :if => Proc.new { |c| !c.request.format.json? }
  92         def caches_page(*actions)
  93           return unless perform_caching
  94           options = actions.extract_options!
  95           after_filter({:only => actions}.merge(options)) { |c| c.cache_page }
  96         end
  97
  98         private
  99           def page_cache_file(path)
 100             name = (path.empty? || path == "/") ? "/index" : URI.unescape(path.chomp('/'))
 101             name << page_cache_extension unless (name.split('/').last || name).include? '.'
 102             return name
 103           end
 104
 105           def page_cache_path(path)
 106             page_cache_directory + page_cache_file(path)
 107           end
 108       end
 109
 110       # Expires the page that was cached with the +options+ as a key. Example:
 111       #   expire_page :controller => "lists", :action => "show"
 112       def expire_page(options = {})
 113         return unless perform_caching
 114
 115         if options.is_a?(Hash)
 116           if options[:action].is_a?(Array)
 117             options[:action].dup.each do |action|
 118               self.class.expire_page(url_for(options.merge(:only_path => true, :skip_relative_url_root => true, :action => action)))
 119             end
 120           else
 121             self.class.expire_page(url_for(options.merge(:only_path => true, :skip_relative_url_root => true)))
 122           end
 123         else
 124           self.class.expire_page(options)
 125         end
 126       end
 127
 128       # Manually cache the +content+ in the key determined by +options+. If no content is provided, the contents of response.body is used
 129       # If no options are provided, the requested url is used. Example:
 130       #   cache_page "I'm the cached content", :controller => "lists", :action => "show"
 131       def cache_page(content = nil, options = nil)
 132         return unless perform_caching && caching_allowed
 133
 134         path = case options
 135           when Hash
 136             url_for(options.merge(:only_path => true, :skip_relative_url_root => true, :format => params[:format]))
 137           when String
 138             options
 139           else
 140             request.path
 141         end
 142
 143         self.class.cache_page(content || response.body, path)
 144       end
 145
 146       private
 147         def caching_allowed
 148           request.get? && response.status.to_i == 200
 149         end
 150     end
 151   end
 152 end