Updated caching to include action caching as well and simplified the name/key reference to just be name

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@368 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

actionpack/lib/action_controller/caching.rb

@@ -4,8 +4,7 @@ module ActionController #:nodoc:
   module Caching #:nodoc:
     def self.append_features(base)
       super
-      base.send(:include, Pages)
-      base.send(:include, Fragments)
+      base.send(:include, Pages, Actions, Fragments, Sweeping)
     end
 
     # Page caching is an approach to caching where the entire action output of is stored as a HTML file that the web server 
@@ -17,7 +16,7 @@ module ActionController #:nodoc:
     # Specifying which actions to cach is done through the <tt>caches</tt> class method:
     #
     #   class WeblogController < ActionController::Base
-    #     caches :show, :new
+    #     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
@@ -35,14 +34,8 @@ module ActionController #:nodoc:
     #     end
     #   end
     #
-    # Additionally, you can expire caches -- or even record new caches -- from outside of the controller, such as from a Active
-    # Record observer:
-    #
-    #   class PostObserver < ActiveRecord::Observer
-    #     def after_update(post)
-    #       WeblogController.expire_page "/weblog/show/#{post.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.
     module Pages
       def self.append_features(base)
         super
@@ -65,7 +58,7 @@ module ActionController #:nodoc:
           logger.info "Expired page: #{path}" unless logger.nil?
         end
         
-        def caches(*actions)
+        def caches_page(*actions)
           actions.each do |action| 
             class_eval "after_filter { |c| c.cache_page if c.action_name == '#{action}' }"
           end
@@ -73,7 +66,13 @@ module ActionController #:nodoc:
       end
 
       def expire_page(options = {})
-        self.class.expire_page(url_for(options.merge({ :only_path => true })))
+        if options[:action].is_a?(Array)
+          options[:action].dup.each do |action|
+            self.class.expire_page(url_for(options.merge({ :only_path => true, :action => action })))
+          end
+        else
+          self.class.expire_page(url_for(options.merge({ :only_path => true })))
+        end
       end
 
       # Expires more than one page at the time. Example:
@@ -90,6 +89,86 @@ module ActionController #:nodoc:
       end
     end
 
+    # Action caching is similar to page caching by the fact that the entire output of the response is cached, but unlike page caching, 
+    # every request still goes through the Action Pack. The key benefit of this is that filters are run before the cache is served, which
+    # allows for authentication and other restrictions on whether someone are supposed to see the cache. Example:
+    #
+    #   class ListsController < ApplicationController
+    #     before_filter :authenticate, :except => :public
+    #     caches_page   :public
+    #     caches_action :show, :feed
+    #   end
+    #
+    # In this example, the public action doesn't require authentication, so it's possible to use the faster page caching method. But both the
+    # show and feed action are to be shielded behind the authenticate filter, so we need to implement those as action caches.
+    #
+    # Action caching internally uses the fragment caching and an around filter to do the job. The fragment cache is named according to both
+    # the current host and the path. So a page that is accessed at http://david.somewhere.com/lists/show/1 will result in a fragment named
+    # "david.somewhere.com/lists/show/1". This allows the cacher to differentiate between "david.somewhere.com/lists/" and
+    # "jamis.somewhere.com/lists/" -- which is a helpful way of assisting the subdomain-as-account-key pattern.
+    module Actions
+      def self.append_features(base)
+        super
+        base.extend(ClassMethods)
+        base.send(:attr_accessor, :rendered_action_cache)
+      end
+
+      module ClassMethods
+        def caches_action(*actions)
+          around_filter(ActionCacheFilter.new(*actions))
+        end
+      end
+
+      def expire_action(options = {})
+        expire_fragment(url_for(options).split("://").last)
+      end
+
+      class ActionCacheFilter
+        def initialize(*actions)
+          @actions = actions
+        end
+        
+        def before(controller)
+          return unless @actions.include?(controller.action_name.intern)
+          if cache = controller.read_fragment(controller.url_for.split("://").last)
+            controller.rendered_action_cache = true
+            controller.send(:render_text, cache)
+            false
+          end
+        end
+        
+        def after(controller)
+          return if !@actions.include?(controller.action_name.intern) || controller.rendered_action_cache
+          controller.write_fragment(controller.url_for.split("://").last, controller.response.body)
+        end
+      end
+    end
+
+    # Fragment caching is used for caching various blocks within templates without caching the entire action as a whole. This is useful when
+    # certain elements of an action change frequently or depend on complicated state while other parts rarely change or can be shared amongst multiple
+    # parties. The caching is doing using the cache helper available in the Action View. A template with caching might look something like:
+    #
+    #   <b>Hello <%= @name %></b>
+    #   <% cache(binding) do %>
+    #     All the topics in the system:
+    #     <%= render_collection_of_partials "topic", Topic.find_all %>
+    #   <% end %>
+    #
+    # This cache will bind to the name of action that called it. So you would be able to invalidate it using 
+    # <tt>expire_fragment(:controller => "topics", :action => "list")</tt> -- if that was the controller/action used. This is not too helpful
+    # if you need to cache multiple fragments per action or if the action itself is cached using <tt>caches_action</tt>. So instead we should
+    # qualify the name of the action used with something like:
+    #
+    #   <% cache(binding, :action => "list", :action_suffix => "all_topics") do %>
+    #
+    # That would result in a name such as "/topics/list/all_topics", which wouldn't conflict with any action cache and neither with another
+    # fragment using a different suffix. Note that the URL doesn't have to really exist or be callable. We're just using the url_for system
+    # to generate unique cache names that we can refer to later for expirations. The expiration call for this example would be
+    # <tt>expire_fragment(:controller => "topics", :action => "list", :action_suffix => "all_topics")</tt>.
+    #
+    # == Fragment stores
+    #
+    # TO BE WRITTEN...
     module Fragments
       def self.append_features(base)
         super
@@ -99,22 +178,41 @@ module ActionController #:nodoc:
         end
       end
 
-      def cache_fragment(binding, name, key = nil)
+      # Called by CacheHelper#cache
+      def cache_erb_fragment(binding, name = {}, options = {})
         buffer = eval("_erbout", binding)
-        if cache = fragment_cache_store.read(name, key)
+
+        name = url_for(name) if name.is_a?(Hash)
+        if cache = read_fragment(name, options)
           buffer.concat(cache)
-          logger.info "Fragment hit: #{name}/#{key}" unless logger.nil?
         else
           pos = buffer.length
           yield
-          fragment_cache_store.write(name, key, buffer[pos..-1])
-          logger.info "Cached fragment: #{name}/#{key}" unless logger.nil?
+          write_fragment(name, buffer[pos..-1], options)
         end
       end
-
-      def expire_fragment(name, key = nil)
-        fragment_cache_store.delete(name, key)
-        logger.info "Expired fragment: #{name}/#{key}" unless logger.nil?
+      
+      def write_fragment(name, content, options = {})
+        name = url_for(name) if name.is_a?(Hash)
+        fragment_cache_store.write(name, content, options)
+        logger.info "Cached fragment: #{name}" unless logger.nil?
+        content
+      end
+      
+      def read_fragment(name, options = {})
+        name = url_for(name) if name.is_a?(Hash)
+        if cache = fragment_cache_store.read(name, options)
+          logger.info "Fragment hit: #{name}" unless logger.nil?
+          cache
+        else
+          false
+        end
+      end
+      
+      def expire_fragment(name, options = {})
+        name = url_for(name) if name.is_a?(Hash)
+        fragment_cache_store.delete(name, options)
+        logger.info "Expired fragment: #{name}" unless logger.nil?
       end
     
       class MemoryStore
@@ -122,25 +220,20 @@ module ActionController #:nodoc:
           @data = { }
         end
     
-        def read(name, key)
+        def read(name, options = {}) #:nodoc:
           begin
-            key ? @data[name][key] : @data[name]
+            @data[name]
           rescue
             nil
           end
         end
 
-        def write(name, key, value)
-          if key
-            @data[name] ||= {}
-            @data[name][key] = value
-          else
-            @data[name] = value
-          end
+        def write(name, value, options = {}) #:nodoc:
+          @data[name] = value
         end
 
-        def delete(name, key)
-          key ? @data[name].delete(key) : @data.delete(name)
+        def delete(name, options = {}) #:nodoc:
+          @data.delete(name)
         end
       end
 
@@ -155,32 +248,78 @@ module ActionController #:nodoc:
           @cache_path = cache_path
         end
     
-        def write(name, key, value)
-          ensure_cache_path(File.dirname(cache_file_path(name, key)))
-          File.open(cache_file_path(name, key), "w+") { |f| f.write(value) }
+        def write(name, value, options = {}) #:nodoc:
+          begin
+            ensure_cache_path(File.dirname(real_file_path(name)))
+            File.open(real_file_path(name), "w+") { |f| f.write(value) }
+          rescue => e
+            Base.logger.info "Couldn't create cache directory: #{name} (#{e.message})" unless Base.logger.nil?
+          end
         end
 
-        def read(name, key)
+        def read(name, options = {}) #:nodoc:
           begin
-            IO.read(cache_file_path(name, key))
+            IO.read(real_file_path(name))
           rescue
             nil
           end
         end
 
-        def delete(name, key)
-          File.delete(cache_file_path(name, key)) if File.exist?(cache_file_path(name, key))
+        def delete(name, options) #:nodoc:
+          File.delete(real_file_path(name)) if File.exist?(real_file_path(name))
         end
     
         private
-          def cache_file_path(name, key)
-            key ? "#{@cache_path}/#{name}/#{key}" : "#{@cache_path}/#{name}"
+          def real_file_path(name)
+            "#{@cache_path}/#{name}"
           end
-      
+        
           def ensure_cache_path(path)
             FileUtils.makedirs(path) unless File.exists?(path)
           end
       end
     end
+
+    module Sweeping #:nodoc:
+      def self.append_features(base) #:nodoc:
+        super
+        base.extend(ClassMethods)
+      end
+
+      # Sweepers are the terminators of the caching world and responsible for expiring caches when model objects change.
+      # They do this by being half-observers, half-filters and implementing callbacks for both roles. A Sweeper example:
+      # 
+      #   class ListSweeper < ActiveRecord::Observer
+      #     observe List, Item
+      #   
+      #     def after_save(record)
+      #       @list = record.is_a?(List) ? record : record.list
+      #     end
+      #     
+      #     def filter(controller)
+      #       controller.expire_page(:controller => "lists", :action => %w( show public feed ), :id => @list.id)
+      #       controller.expire_action(:controller => "lists", :action => "all")
+      #       @list.shares.each { |share| controller.expire_page(:controller => "lists", :action => "show", :id => share.url_key) }
+      #     end
+      #   end
+      #
+      # The sweeper is assigned on the controllers that wish to have its job performed using the <tt>cache_sweeper</tt> class method:
+      #
+      #   class ListsController < ApplicationController
+      #     caches_action :index, :show, :public, :feed
+      #     cache_sweeper :list_sweeper, :only => [ :edit, :destroy, :share ]
+      #   end
+      #
+      # In the example above, four actions are cached and three actions are responsible of expiring those caches.
+      module ClassMethods
+        def cache_sweeper(*sweepers)
+          configuration = sweepers.last.is_a?(Hash) ? sweepers.pop : {}
+          sweepers.each do |sweeper| 
+            observer(sweeper)
+            after_filter(Object.const_get(Inflector.classify(sweeper)).instance, :only => configuration[:only])
+          end
+        end
+      end
+    end
   end
 end

actionpack/lib/action_view/helpers/cache_helper.rb

@@ -1,8 +1,9 @@
 module ActionView
   module Helpers
+    # See ActionController::Caching::Fragments for usage instructions.
     module CacheHelper
       def cache(binding, name, key = nil)
-        @controller.cache_fragment(binding, name, key) { yield }
+        @controller.cache_erb_fragment(binding, name, key) { yield }
       end
     end
   end