Merge pull request #189 from Shopify/cache_partials

Cache tokenized partial templates

lib/liquid/tags/include.rb

@@ -24,8 +24,7 @@ module Liquid
     end
     
     def render(context)
-      source = _read_template_from_file_system(context)
-      partial = Liquid::Template.parse(source)
+      partial = load_cached_partial(context)
       variable = context[@variable_name || @template_name[1..-2]]
       
       context.stack do
@@ -46,7 +45,21 @@ module Liquid
     end
    
     private
-      def _read_template_from_file_system(context)
+      def load_cached_partial(context)
+        cached_partials = context.registers[:cached_partials] || {}
+        template_name = context[@template_name]
+
+        if cached = cached_partials[template_name]
+          return cached
+        end
+        source = read_template_from_file_system(context)
+        partial = Liquid::Template.parse(source)
+        cached_partials[template_name] = partial
+        context.registers[:cached_partials] = cached_partials
+        partial
+      end
+
+      def read_template_from_file_system(context)
         file_system = context.registers[:file_system] || Liquid::Template.file_system
       
         # make read_template_file call backwards-compatible.

performance/theme_runner.rb

@@ -14,6 +14,17 @@ require File.dirname(__FILE__) + '/shopify/liquid'
 require File.dirname(__FILE__) + '/shopify/database.rb'
 
 class ThemeRunner
+  class FileSystem
+
+    def initialize(path)
+      @path = path
+    end
+
+    # Called by Liquid to retrieve a template file
+    def read_template_file(template_path, context)
+      File.read(@path + '/' + template_path + '.liquid')
+    end
+  end
 
   # Load all templates into memory, do this now so that 
   # we don't profile IO. 
@@ -47,7 +58,7 @@ class ThemeRunner
 
       # Compute page_tempalte outside of profiler run, uninteresting to profiler
       page_template = File.basename(template_name, File.extname(template_name))
-      compile_and_render(liquid, layout, assigns, page_template) 
+      compile_and_render(liquid, layout, assigns, page_template, template_name)
        
     end
   end
@@ -74,7 +85,7 @@ class ThemeRunner
       html = nil
 
       RubyProf.resume
-      html = compile_and_render(liquid, layout, assigns, page_template) 
+      html = compile_and_render(liquid, layout, assigns, page_template, template_name)
       RubyProf.pause
       
 
@@ -88,10 +99,11 @@ class ThemeRunner
     RubyProf.stop
   end
 
-  def compile_and_render(template, layout, assigns, page_template)    
+  def compile_and_render(template, layout, assigns, page_template, template_file)
     tmpl = Liquid::Template.new
     tmpl.assigns['page_title'] = 'Page title'
     tmpl.assigns['template'] = page_template
+    tmpl.registers[:file_system] = ThemeRunner::FileSystem.new(File.dirname(template_file))
 
     content_for_layout = tmpl.parse(template).render(assigns)
 

test/liquid/tags/include_tag_test.rb

@@ -39,6 +39,15 @@ class OtherFileSystem
   end
 end
 
+class CountingFileSystem
+  attr_reader :count
+  def read_template_file(template_path, context)
+    @count ||= 0
+    @count += 1
+    'from CountingFileSystem'
+  end
+end
+
 class IncludeTagTest < Test::Unit::TestCase
   include Liquid
 
@@ -136,4 +145,22 @@ class IncludeTagTest < Test::Unit::TestCase
 
     assert_equal "Product: Draft 151cm ", Template.parse("{% include template for product %}").render("template" => 'product', 'product' => { 'title' => 'Draft 151cm'})
   end
+
+  def test_include_tag_caches_second_read_of_same_partial
+    file_system = CountingFileSystem.new
+    assert_equal 'from CountingFileSystemfrom CountingFileSystem',
+      Template.parse("{% include 'pick_a_source' %}{% include 'pick_a_source' %}").render({}, :registers => {:file_system => file_system})
+    assert_equal 1, file_system.count
+  end
+
+  def test_include_tag_doesnt_cache_partials_across_renders
+    file_system = CountingFileSystem.new
+    assert_equal 'from CountingFileSystem',
+      Template.parse("{% include 'pick_a_source' %}").render({}, :registers => {:file_system => file_system})
+    assert_equal 1, file_system.count
+
+    assert_equal 'from CountingFileSystem',
+      Template.parse("{% include 'pick_a_source' %}").render({}, :registers => {:file_system => file_system})
+    assert_equal 2, file_system.count
+  end
 end # IncludeTagTest