[#778] Properly cache Liquid markup

This commit moves the markup caching into Liquid rendering. As
Liquid allows to return different results depending on the environment
(variables, logged user, ...) we only cache the page if it contains
no active content.

Unfortunetely, active content currently also includes the TOC
in wiki pages.

lib/chili_project/liquid/liquid_ext/block.rb

@@ -19,15 +19,19 @@ module ChiliProject
         def self.included(base)
           base.send(:include, InstanceMethods)
           base.class_eval do
-            alias_method_chain :render_all, :cleaned_whitespace
+            alias_method_chain :render_all, :cleaned_whitespace_and_cache
           end
         end
 
         module InstanceMethods
-          def render_all_with_cleaned_whitespace(list, context)
+          def render_all_with_cleaned_whitespace_and_cache(list, context)
             # Remove the leading newline in a block's content
             list[0].sub!(/\A\r?\n/, "") if list[0].is_a?(String)
-            render_all_without_cleaned_whitespace(list, context)
+
+            # prevent caching if there are any potentially active elements
+            context.not_cachable! if list.any? { |token| token.respond_to?(:render) }
+
+            render_all_without_cleaned_whitespace_and_cache(list, context)
           end
         end
       end

lib/chili_project/liquid/liquid_ext/context.rb

@@ -47,6 +47,14 @@ module ChiliProject
           def html_results
             registers[:html_results] ||= {}
           end
+
+          def cacheable?
+            registers.has_key?(:cachable) ? !!registers[:cachable] : true
+          end
+
+          def not_cachable!
+            registers[:cachable] = false
+          end
         end
       end
     end

lib/chili_project/liquid/template.rb

@@ -74,6 +74,26 @@ module ChiliProject
         context = context_from_render_options(*args)
         context.registers[:html_results] ||= {}
 
+        obj = context.registers[:object]
+        attribute = context.registers[:attribute]
+
+        if Setting.cache_formatted_text? && cache_key = cache_key_for(Setting.text_formatting, obj, attribute)
+          # Text retrieved from the cache store may be frozen
+          # We need to dup it so we can do in-place substitutions with gsub!
+          result = Rails.cache.fetch(cache_key)
+          result ||= begin
+            result = render_context(context)
+            Rails.cache.write(cache_key, result) if context.cacheable?
+            result
+          end.dup
+        else
+          render_context(context)
+        end
+      end
+
+      def render_context(context)
+        return '' if @root.nil?
+
         # ENTER THE RENDERING STAGE
 
         # 1. Render the input as Liquid
@@ -88,8 +108,8 @@ module ChiliProject
 
         # 2. Perform the Wiki markup transformation (e.g. Textile)
         obj = context.registers[:object]
-        attr = context.registers[:attribute]
-        result = Redmine::WikiFormatting.to_html(Setting.text_formatting, result, :object => obj, :attribute => attr)
+        attribute = context.registers[:attribute]
+        result = Redmine::WikiFormatting.to_html(Setting.text_formatting, result, :object => obj, :attribute => attribute)
 
         # 3. Now finally, replace the captured raw HTML bits in the final content
         length = nil
@@ -105,6 +125,13 @@ module ChiliProject
 
         result
       end
+
+    private
+      def cache_key_for(format, object, attribute)
+        if object && attribute && !object.new_record? && object.respond_to?(:updated_on) && !format.blank?
+          "formatted_text/#{format}/#{object.class.model_name.cache_key}/#{object.id}-#{attribute}-#{object.updated_on.to_s(:number)}"
+        end
+      end
     end
   end
 end

lib/redmine/wiki_formatting.rb

@@ -41,27 +41,7 @@ module Redmine
       end
 
       def to_html(format, text, options = {}, &block)
-        if Setting.cache_formatted_text? && text.size > 2.kilobyte && cache_store && cache_key = cache_key_for(format, options[:object], options[:attribute])
-          # Text retrieved from the cache store may be frozen
-          # We need to dup it so we can do in-place substitutions with gsub!
-          cache_store.fetch cache_key do
-            formatter_for(format).new(text).to_html
-          end.dup
-        else
-          formatter_for(format).new(text).to_html
-        end
-      end
-
-      # Returns a cache key for the given text +format+, +object+ and +attribute+ or nil if no caching should be done
-      def cache_key_for(format, object, attribute)
-        if object && attribute && !object.new_record? && object.respond_to?(:updated_on) && !format.blank?
-          "formatted_text/#{format}/#{object.class.model_name.cache_key}/#{object.id}-#{attribute}-#{object.updated_on.to_s(:number)}"
-        end
-      end
-
-      # Returns the cache store used to cache HTML output
-      def cache_store
-        ActionController::Base.cache_store
+        formatter_for(format).new(text).to_html
       end
     end
   end