require 'fileutils' require 'uri' module ActionController #:nodoc: module Caching # Page caching is an approach to caching where the entire action output of is stored as a HTML file that the web server # can serve without going through the Action Pack. This can be as much as 100 times faster than going through the process of dynamically # generating the content. Unfortunately, this incredible speed-up is only available to stateless pages where all visitors # are treated the same. Content management systems -- including weblogs and wikis -- have many pages that are a great fit # for this approach, but account-based systems where people log in and manipulate their own data are often less likely candidates. # # Specifying which actions to cache is done through the caches class method: # # class WeblogController < ActionController::Base # caches_page :show, :new # end # # This will generate cache files such as weblog/show/5 and weblog/new, which match the URLs used to trigger the dynamic # generation. This is how the web server is able pick up a cache file when it exists and otherwise let the request pass on to # the Action Pack to generate it. # # Expiration of the cache is handled by deleting the cached file, which results in a lazy regeneration approach where the cache # is not restored before another hit is made against it. The API for doing so mimics the options from url_for and friends: # # class WeblogController < ActionController::Base # def update # List.update(params[:list][:id], params[:list]) # expire_page :action => "show", :id => params[:list][:id] # redirect_to :action => "show", :id => params[:list][:id] # end # end # # Additionally, you can expire caches using Sweepers that act on changes in the model to determine when a cache is supposed to be # expired. # # == Setting the cache directory # # The cache directory should be the document root for the web server and is set using Base.page_cache_directory = "/document/root". # For Rails, this directory has already been set to RAILS_ROOT + "/public". # # == Setting the cache extension # # By default, the cache extension is .html, which makes it easy for the cached files to be picked up by the web server. If you want # something else, like .php or .shtml, just set Base.page_cache_extension. module Pages def self.included(base) #:nodoc: base.extend(ClassMethods) base.class_eval do @@page_cache_directory = defined?(RAILS_ROOT) ? "#{RAILS_ROOT}/public" : "" cattr_accessor :page_cache_directory @@page_cache_extension = '.html' cattr_accessor :page_cache_extension end end module ClassMethods # Expires the page that was cached with the +path+ as a key. Example: # expire_page "/lists/show" def expire_page(path) return unless perform_caching benchmark "Expired page: #{page_cache_file(path)}" do File.delete(page_cache_path(path)) if File.exist?(page_cache_path(path)) end end # Manually cache the +content+ in the key determined by +path+. Example: # cache_page "I'm the cached content", "/lists/show" def cache_page(content, path) return unless perform_caching benchmark "Cached page: #{page_cache_file(path)}" do FileUtils.makedirs(File.dirname(page_cache_path(path))) File.open(page_cache_path(path), "wb+") { |f| f.write(content) } end end # Caches the +actions+ using the page-caching approach that'll store the cache in a path within the page_cache_directory that # matches the triggering url. def caches_page(*actions) return unless perform_caching actions = actions.map(&:to_s) after_filter { |c| c.cache_page if actions.include?(c.action_name) } end private def page_cache_file(path) name = (path.empty? || path == "/") ? "/index" : URI.unescape(path.chomp('/')) name << page_cache_extension unless (name.split('/').last || name).include? '.' return name end def page_cache_path(path) page_cache_directory + page_cache_file(path) end end # Expires the page that was cached with the +options+ as a key. Example: # expire_page :controller => "lists", :action => "show" def expire_page(options = {}) return unless perform_caching if options.is_a?(Hash) if options[:action].is_a?(Array) options[:action].dup.each do |action| self.class.expire_page(url_for(options.merge(:only_path => true, :skip_relative_url_root => true, :action => action))) end else self.class.expire_page(url_for(options.merge(:only_path => true, :skip_relative_url_root => true))) end else self.class.expire_page(options) end end # Manually cache the +content+ in the key determined by +options+. If no content is provided, the contents of response.body is used # If no options are provided, the requested url is used. Example: # cache_page "I'm the cached content", :controller => "lists", :action => "show" def cache_page(content = nil, options = nil) return unless perform_caching && caching_allowed path = case options when Hash url_for(options.merge(:only_path => true, :skip_relative_url_root => true, :format => params[:format])) when String options else request.path end self.class.cache_page(content || response.body, path) end private def caching_allowed request.get? && response.headers['Status'].to_i == 200 end end end end