Added first stab at page and fragment caching

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@346 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

actionpack/lib/action_controller.rb

@@ -39,6 +39,7 @@ require 'action_controller/scaffolding'
 require 'action_controller/helpers'
 require 'action_controller/cookies'
 require 'action_controller/cgi_process'
+require 'action_controller/caching'
 
 ActionController::Base.class_eval do
   include ActionController::Filters
@@ -51,6 +52,7 @@ ActionController::Base.class_eval do
   include ActionController::Helpers
   include ActionController::Cookies
   include ActionController::Session
+  include ActionController::Caching
 end
 
 require 'action_view'

actionpack/lib/action_controller/base.rb

@@ -4,6 +4,7 @@ require 'action_controller/url_rewriter'
 require 'action_controller/support/class_attribute_accessors'
 require 'action_controller/support/class_inheritable_attributes'
 require 'action_controller/support/inflector'
+require 'drb'
 
 module ActionController #:nodoc:
   class ActionControllerError < StandardError #:nodoc:
@@ -183,7 +184,6 @@ module ActionController #:nodoc:
       :buffer_size  => 4096
     }
 
-
     # Determines whether the view has access to controller internals @request, @response, @session, and @template.
     # By default, it does.
     @@view_controller_internals = true
@@ -359,7 +359,7 @@ module ActionController #:nodoc:
       # <tt>render_action "show_many"</tt> in WeblogController#display will render "#{template_root}/weblog/show_many.rhtml" or 
       # "#{template_root}/weblog/show_many.rxml".
       def render_action(action_name, status = nil) #:doc:
-        render default_template_name(action_name), status
+        render(default_template_name(action_name), status)
       end
       
       # Works like render, but disregards the template_root and requires a full path to the template that needs to be rendered. Can be
@@ -390,6 +390,12 @@ module ActionController #:nodoc:
         @response.body = block_given? ? block : text
         @performed_render = true
       end
+      
+      # Renders an empty response that can be used when the request is only interested in triggering an effect. Do note that good
+      # HTTP manners mandate that you don't use GET requests to trigger data changes.
+      def render_nothing(status = nil)
+        render_text "", status
+      end
 
       # Sends the file by streaming it 4096 bytes at a time. This way the
       # whole file doesn't need to be read into memory at once.  This makes

actionpack/lib/action_controller/caching.rb

@@ -0,0 +1,186 @@
+require 'fileutils'
+
+module ActionController #:nodoc:
+  module Caching #:nodoc:
+    def self.append_features(base)
+      super
+      base.send(:include, Pages)
+      base.send(:include, Fragments)
+    end
+
+    # 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 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 cach is done through the <tt>caches</tt> class method:
+    #
+    #   class WeblogController < ActionController::Base
+    #     caches :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 -- 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
+    module Pages
+      def self.append_features(base)
+        super
+        base.extend(ClassMethods)
+        base.class_eval do
+          @@page_cache_directory = defined?(RAILS_ROOT) ? "#{RAILS_ROOT}/public" : ""
+          cattr_accessor :page_cache_directory
+        end
+      end
+
+      module ClassMethods
+        def cache_page(content, path)
+          FileUtils.makedirs(File.dirname(page_cache_directory + path))
+          File.open(page_cache_directory + path, "w+") { |f| f.write(content) }
+          logger.info "Cached page: #{path}" unless logger.nil?
+        end
+
+        def expire_page(path)
+          File.delete(page_cache_directory + path) if File.exists?(page_cache_directory + path)
+          logger.info "Expired page: #{path}" unless logger.nil?
+        end
+        
+        def caches(*actions)
+          actions.each do |action| 
+            class_eval "after_filter { |c| c.cache_page if c.action_name == '#{action}' }"
+          end
+        end
+      end
+
+      def expire_page(options = {})
+        self.class.expire_page(url_for(options.merge({ :only_path => true })))
+      end
+
+      # Expires more than one page at the time. Example:
+      #   expire_pages(
+      #     { :controller => "lists", :action => "public", :id => list_id },
+      #     { :controller => "lists", :action => "show", :id => list_id }
+      #   )
+      def expire_pages(*options)
+        options.each { |option| expire_page(option) }
+      end
+      
+      def cache_page(content = nil, options = {})
+        self.class.cache_page(content || @response.body, url_for(options.merge({ :only_path => true })))
+      end
+    end
+
+    module Fragments
+      def self.append_features(base)
+        super
+        base.class_eval do
+          @@cache_store = MemoryStore.new
+          cattr_accessor :fragment_cache_store
+        end
+      end
+
+      def cache_fragment(binding, name, key = nil)
+        buffer = eval("_erbout", binding)
+        if cache = fragment_cache_store.read(name, key)
+          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?
+        end
+      end
+
+      def expire_fragment(name, key = nil)
+        fragment_cache_store.delete(name, key)
+        logger.info "Expired fragment: #{name}/#{key}" unless logger.nil?
+      end
+    
+      class MemoryStore
+        def initialize
+          @data = { }
+        end
+    
+        def read(name, key)
+          begin
+            key ? @data[name][key] : @data[name]
+          rescue
+            nil
+          end
+        end
+
+        def write(name, key, value)
+          if key
+            @data[name] ||= {}
+            @data[name][key] = value
+          else
+            @data[name] = value
+          end
+        end
+
+        def delete(name, key)
+          key ? @data[name].delete(key) : @data.delete(name)
+        end
+      end
+
+      class DRbStore < MemoryStore
+        def initialize(address = 'druby://localhost:9192')
+          @data = DRbObject.new(nil, address)
+        end    
+      end
+
+      class FileStore
+        def initialize(cache_path)
+          @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) }
+        end
+
+        def read(name, key)
+          begin
+            IO.read(cache_file_path(name, key))
+          rescue
+            nil
+          end
+        end
+
+        def delete(name, key)
+          File.delete(cache_file_path(name, key)) if File.exist?(cache_file_path(name, key))
+        end
+    
+        private
+          def cache_file_path(name, key)
+            key ? "#{@cache_path}/#{name}/#{key}" : "#{@cache_path}/#{name}"
+          end
+      
+          def ensure_cache_path(path)
+            FileUtils.makedirs(path) unless File.exists?(path)
+          end
+      end
+    end
+  end
+end

actionpack/lib/action_view/helpers/cache_helper.rb

@@ -0,0 +1,9 @@
+module ActionView
+  module Helpers
+    module CacheHelper
+      def cache(binding, name, key = nil)
+        @controller.cache_fragment(binding, name, key) { yield }
+      end
+    end
+  end
+end