Merge pull request #485 from Shopify/lazy-load-profiler-hooks

Defer loading profiler hooks

lib/liquid.rb

@@ -73,6 +73,3 @@ require 'liquid/token'
 # Load all the tags of the standard library
 #
 Dir[File.dirname(__FILE__) + '/liquid/tags/*.rb'].each { |f| require f }
-
-require 'liquid/profiler'
-require 'liquid/profiler/hooks'

lib/liquid/profiler.rb

@@ -1,9 +1,12 @@
+require 'liquid/profiler/hooks'
+
 module Liquid
 
   # Profiler enables support for profiling template rendering to help track down performance issues.
   #
-  # To enable profiling, pass the <tt>profile: true</tt> option to <tt>Liquid::Template.parse</tt>. Then, after
-  # <tt>Liquid::Template#render</tt> is called, the template object makes available an instance of this
+  # To enable profiling, first require 'liquid/profiler'.
+  # Then, to profile a parse/render cycle, pass the <tt>profile: true</tt> option to <tt>Liquid::Template.parse</tt>.
+  # After <tt>Liquid::Template#render</tt> is called, the template object makes available an instance of this
   # class via the <tt>Liquid::Template#profiler</tt> method.
   #
   #   template = Liquid::Template.parse(template_content, profile: true)

lib/liquid/template.rb

@@ -250,6 +250,8 @@ module Liquid
 
     def with_profiling
       if @profiling && !@options[:included]
+        raise "Profiler not loaded, require 'liquid/profiler' first" unless defined?(Liquid::Profiler)
+
         @profiler = Profiler.new
         @profiler.start
 

test/test_helper.rb

@@ -5,6 +5,7 @@ require 'spy/integration'
 
 $:.unshift(File.join(File.expand_path(File.dirname(__FILE__)), '..', 'lib'))
 require 'liquid.rb'
+require 'liquid/profiler'
 
 mode = :strict
 if env_mode = ENV['LIQUID_PARSER_MODE']