Remove locals dependency from template.

This means that templates does not need to store its source anymore, allowing us to reduce the ammount of memory taken by our Rails processes. Naively speaking, if your app/views contains 2MB of files, each of your processes (after being hit by a bunch of requests) will take 2MB less of memory after this commit.

This is extremely important for the upcoming features. Since Rails will also render CSS and JS files, their source won't be stored as well allowing us to decrease the ammount of memory taken.

9 files changed, 130 insertions, 85 deletions

diff --git a/actionpack/lib/action_view/lookup_context.rb b/actionpack/lib/action_view/lookup_context.rb
index 3ea8b86af1..794fdeae64 100644
--- a/actionpack/lib/action_view/lookup_context.rb
+++ b/actionpack/lib/action_view/lookup_context.rb
@@ -77,17 +77,17 @@ module ActionView
         @view_paths = ActionView::Base.process_view_paths(paths)
       end
 
-      def find(name, prefix = nil, partial = false)
-        @view_paths.find(*args_for_lookup(name, prefix, partial))
+      def find(name, prefix = nil, partial = false, keys = [])
+        @view_paths.find(*args_for_lookup(name, prefix, partial, keys))
       end
       alias :find_template :find
 
-      def find_all(name, prefix = nil, partial = false)
-        @view_paths.find_all(*args_for_lookup(name, prefix, partial))
+      def find_all(name, prefix = nil, partial = false, keys = [])
+        @view_paths.find_all(*args_for_lookup(name, prefix, partial, keys))
       end
 
-      def exists?(name, prefix = nil, partial = false)
-        @view_paths.exists?(*args_for_lookup(name, prefix, partial))
+      def exists?(name, prefix = nil, partial = false, keys = [])
+        @view_paths.exists?(*args_for_lookup(name, prefix, partial, keys))
       end
       alias :template_exists? :exists?
 
@@ -106,9 +106,9 @@ module ActionView
 
     protected
 
-      def args_for_lookup(name, prefix, partial) #:nodoc:
+      def args_for_lookup(name, prefix, partial, keys) #:nodoc:
         name, prefix = normalize_name(name, prefix)
-        [name, prefix, partial || false, @details, details_key]
+        [name, prefix, partial || false, @details, keys, details_key]
       end
 
       # Support legacy foo.erb names even though we now ignore .erb
diff --git a/actionpack/lib/action_view/paths.rb b/actionpack/lib/action_view/paths.rb
index 9857d688d2..dc26d75ff3 100644
--- a/actionpack/lib/action_view/paths.rb
+++ b/actionpack/lib/action_view/paths.rb
@@ -10,8 +10,8 @@ module ActionView #:nodoc:
       METHOD
     end
 
-    def find(path, prefix = nil, partial = false, details = {}, key = nil)
-      template = find_all(path, prefix, partial, details, key).first
+    def find(path, prefix = nil, partial = false, details = {}, keys = [], key = nil)
+      template = find_all(path, prefix, partial, details, keys, key).first
       raise MissingTemplate.new(self, "#{prefix}/#{path}", details, partial) unless template
       template
     end
diff --git a/actionpack/lib/action_view/render/layouts.rb b/actionpack/lib/action_view/render/layouts.rb
index 8882acca31..08162f7fd5 100644
--- a/actionpack/lib/action_view/render/layouts.rb
+++ b/actionpack/lib/action_view/render/layouts.rb
@@ -62,11 +62,11 @@ module ActionView
     # This is the method which actually finds the layout using details in the lookup
     # context object. If no layout is found, it checks if at least a layout with
     # the given name exists across all details before raising the error.
-    def find_layout(layout)
+    def find_layout(layout, keys)
       begin
         with_layout_format do
           layout =~ /^\// ?
-            with_fallbacks { find_template(layout) } : find_template(layout)
+            with_fallbacks { find_template(layout, nil, false, keys) } : find_template(layout, nil, false, keys)
         end
       rescue ActionView::MissingTemplate => e
         update_details(:formats => nil) do
diff --git a/actionpack/lib/action_view/render/partials.rb b/actionpack/lib/action_view/render/partials.rb
index cc9b444837..07e844afc2 100644
--- a/actionpack/lib/action_view/render/partials.rb
+++ b/actionpack/lib/action_view/render/partials.rb
@@ -218,7 +218,6 @@ module ActionView
       def initialize(view_context, options, block)
         @view           = view_context
         @partial_names  = PARTIAL_NAMES[@view.controller.class.name]
-
         setup(options, block)
       end
 
@@ -237,16 +236,28 @@ module ActionView
           @object = partial
 
           if @collection = collection
-            paths = @collection_paths = @collection.map { |o| partial_path(o) }
+            paths = @collection_data = @collection.map { |o| partial_path(o) }
             @path = paths.uniq.size == 1 ? paths.first : nil
           else
             @path = partial_path
           end
         end
+
+        if @path
+          @variable, @variable_counter = retrieve_variable(@path)
+        else
+          paths.map! { |path| retrieve_variable(path).unshift(path) }
+        end
+      end
+
+      def retrieve_variable(path)
+        variable = @options[:as] || path[%r'_?(\w+)(\.\w+)*$', 1].to_sym
+        variable_counter = :"#{variable}_counter" if @collection
+        [variable, variable_counter]
       end
 
       def render
-        identifier = ((@template = find_template) ? @template.identifier : @path)
+        identifier = ((@template = find_partial) ? @template.identifier : @path)
 
         if @collection
           ActiveSupport::Notifications.instrument("render_collection.action_view",
@@ -254,15 +265,16 @@ module ActionView
             render_collection
           end
         else
+          if !@block && (layout = @options[:layout])
+            layout = find_template(layout)
+          end
+
           content = ActiveSupport::Notifications.instrument("render_partial.action_view",
             :identifier => identifier) do
             render_partial
           end
 
-          if !@block && (layout = @options[:layout])
-            content = @view._render_layout(find_template(layout), @locals){ content }
-          end
-
+          content = @view._render_layout(layout, @locals){ content } if layout
           content
         end
       end
@@ -278,16 +290,9 @@ module ActionView
         result.join(spacer).html_safe
       end
 
-      def collection_with_template(template = @template)
+      def collection_with_template
         segments, locals, template = [], @locals, @template
-
-        if @options[:as]
-          as = @options[:as]
-          counter = "#{as}_counter".to_sym
-        else
-          as = template.variable_name
-          counter = template.counter_name
-        end
+        as, counter = @variable, @variable_counter
 
         locals[counter] = -1
 
@@ -300,20 +305,16 @@ module ActionView
         segments
       end
 
-      def collection_without_template(collection_paths = @collection_paths)
-        segments, locals = [], @locals
+      def collection_without_template
+        segments, locals, collection_data = [], @locals, @collection_data
         index, template  = -1, nil
-
-        if @options[:as]
-          as = @options[:as]
-          counter = "#{as}_counter"
-        end
+        keys = @locals.keys
 
         @collection.each_with_index do |object, i|
-          template = find_template(collection_paths[i])
-          locals[as || template.variable_name] = object
-          locals[counter || template.counter_name] = (index += 1)
-
+          path, *data = collection_data[i]
+          template = find_template(path, keys + data)
+          locals[data[0]] = object
+          locals[data[1]] = (index += 1)
           segments << template.render(@view, locals)
         end
 
@@ -321,13 +322,14 @@ module ActionView
         segments
       end
 
-      def render_partial(object = @object)
-        locals, view, template = @locals, @view, @template
+      def render_partial
+        locals, view = @locals, @view
+        object, as = @object, @variable
 
-        object ||= locals[template.variable_name]
-        locals[@options[:as] || template.variable_name] = object
+        object ||= locals[as]
+        locals[as] = object
 
-        template.render(view, locals) do |*name|
+        @template.render(view, locals) do |*name|
           view._layout_for(*name, &@block)
         end
       end
@@ -342,10 +344,18 @@ module ActionView
         end
       end
 
-      def find_template(path=@path)
-        return path unless path.is_a?(String)
+      def find_partial
+        if path = @path
+          locals = @locals.keys
+          locals << @variable
+          locals << @variable_counter if @collection
+          find_template(path, locals)
+        end
+      end 
+
+      def find_template(path=@path, locals=@locals.keys)
         prefix = @view.controller_path unless path.include?(?/)
-        @view.find_template(path, prefix, true)
+        @view.find_template(path, prefix, true, locals)
       end
 
       def partial_path(object = @object)
diff --git a/actionpack/lib/action_view/render/rendering.rb b/actionpack/lib/action_view/render/rendering.rb
index 5320245173..0771b40c37 100644
--- a/actionpack/lib/action_view/render/rendering.rb
+++ b/actionpack/lib/action_view/render/rendering.rb
@@ -34,16 +34,18 @@ module ActionView
 
     # Determine the template to be rendered using the given options.
     def _determine_template(options) #:nodoc:
+      keys = (options[:locals] ||= {}).keys
+
       if options.key?(:inline)
         handler = Template.handler_class_for_extension(options[:type] || "erb")
-        Template.new(options[:inline], "inline template", handler, {})
+        Template.new(options[:inline], "inline template", handler, { :locals => keys })
       elsif options.key?(:text)
         Template::Text.new(options[:text], formats.try(:first))
       elsif options.key?(:file)
-        with_fallbacks { find_template(options[:file], options[:prefix]) }
+        with_fallbacks { find_template(options[:file], options[:prefix], false, keys) }
       elsif options.key?(:template)
         options[:template].respond_to?(:render) ?
-          options[:template] : find_template(options[:template], options[:prefix])
+          options[:template] : find_template(options[:template], options[:prefix], false, keys)
       end
     end
 
@@ -51,7 +53,7 @@ module ActionView
     # supplied as well.
     def _render_template(template, layout = nil, options = {}) #:nodoc:
       locals = options[:locals] || {}
-      layout = find_layout(layout) if layout
+      layout = find_layout(layout, locals.keys) if layout
 
       ActiveSupport::Notifications.instrument("render_template.action_view",
         :identifier => template.identifier, :layout => layout.try(:virtual_path)) do
diff --git a/actionpack/lib/action_view/template.rb b/actionpack/lib/action_view/template.rb
index 164d177dcc..7e65654d0b 100644
--- a/actionpack/lib/action_view/template.rb
+++ b/actionpack/lib/action_view/template.rb
@@ -98,6 +98,8 @@ module ActionView
 
     extend Template::Handlers
 
+    attr_accessor :locals
+
     attr_reader :source, :identifier, :handler, :virtual_path, :formats,
                 :original_encoding
 
@@ -117,23 +119,17 @@ module ActionView
       @handler            = handler
       @original_encoding  = nil
       @method_names       = {}
-
-      format   = details[:format] || :html
-      @formats = Array.wrap(format).map(&:to_sym)
-      @virtual_path = details[:virtual_path].try(:sub, ".#{format}", "")
+      @locals             = details[:locals] || []
+      @formats            = Array.wrap(details[:format] || :html).map(&:to_sym)
+      @virtual_path       = details[:virtual_path].try(:sub, ".#{@formats.first}", "")
+      @compiled           = false
     end
 
     def render(view, locals, &block)
       # Notice that we use a bang in this instrumentation because you don't want to
       # consume this in production. This is only slow if it's being listened to.
       ActiveSupport::Notifications.instrument("!render_template.action_view", :virtual_path => @virtual_path) do
-        if view.is_a?(ActionView::CompiledTemplates)
-          mod = ActionView::CompiledTemplates
-        else
-          mod = view.singleton_class
-        end
-
-        method_name = compile(locals, view, mod)
+        compile!(view)
         view.send(method_name, locals, &block)
       end
     rescue Exception => e
@@ -141,7 +137,7 @@ module ActionView
         e.sub_template_of(self)
         raise e
       else
-        raise Template::Error.new(self, view.respond_to?(:assigns) ? view.assigns : {}, e)
+        raise Template::Error.new(refresh(view) || self, view.respond_to?(:assigns) ? view.assigns : {}, e)
       end
     end
 
@@ -149,10 +145,12 @@ module ActionView
       @mime_type ||= Mime::Type.lookup_by_extension(@formats.first.to_s) if @formats.first
     end
 
+    # TODO Remove me
     def variable_name
       @variable_name ||= @virtual_path[%r'_?(\w+)(\.\w+)*$', 1].to_sym
     end
 
+    # TODO Remove me
     def counter_name
       @counter_name ||= "#{variable_name}_counter".to_sym
     end
@@ -166,7 +164,25 @@ module ActionView
         end
     end
 
-    private
+    def compile!(view)
+      return if @compiled
+
+      if view.is_a?(ActionView::CompiledTemplates)
+        mod = ActionView::CompiledTemplates
+      else
+        mod = view.singleton_class
+      end
+
+      compile(view, mod)
+
+      # Just discard the source if we have a virtual path. This
+      # means we can get the template back.
+      @source = nil if @virtual_path
+      @compiled = true
+    end
+
+    protected
+
       # Among other things, this method is responsible for properly setting
       # the encoding of the source. Until this point, we assume that the
       # source is BINARY data. If no additional information is supplied,
@@ -187,11 +203,9 @@ module ActionView
       # encode the source into Encoding.default_internal. In general,
       # this means that templates will be UTF-8 inside of Rails,
       # regardless of the original source encoding.
-      def compile(locals, view, mod)
-        method_name = build_method_name(locals)
-        return method_name if view.respond_to?(method_name)
-
-        locals_code = locals.keys.map! { |key| "#{key} = local_assigns[:#{key}];" }.join
+      def compile(view, mod)
+        method_name = self.method_name
+        locals_code = @locals.map { |key| "#{key} = local_assigns[:#{key}];" }.join
 
         if source.encoding_aware?
           # Look for # encoding: *. If we find one, we'll encode the
@@ -256,8 +270,6 @@ module ActionView
         begin
           mod.module_eval(source, identifier, 0)
           ObjectSpace.define_finalizer(self, Finalizer[method_name, mod])
-
-          method_name
         rescue Exception => e # errors from template code
           if logger = (view && view.logger)
             logger.debug "ERROR: compiling #{method_name} RAISED #{e}"
@@ -269,12 +281,20 @@ module ActionView
         end
       end
 
-      def build_method_name(locals)
-        @method_names[locals.keys.hash] ||= "_#{identifier_method_name}__#{@identifier.hash}_#{__id__}_#{locals.keys.hash}".gsub('-', "_")
+      def refresh(view)
+        return unless @virtual_path
+        pieces  = @virtual_path.split("/")
+        name    = pieces.pop
+        partial = name.sub!(/^_/, "")
+        view.find_template(name, pieces.join, partial || false, @locals)
+      end
+
+      def method_name
+        @method_name ||= "_#{identifier_method_name}__#{@identifier.hash}_#{__id__}".gsub('-', "_")
       end
 
       def identifier_method_name
-        @identifier_method_name ||= inspect.gsub(/[^a-z_]/, '_')
+        inspect.gsub(/[^a-z_]/, '_')
       end
   end
 end
diff --git a/actionpack/lib/action_view/template/resolver.rb b/actionpack/lib/action_view/template/resolver.rb
index a031d0dc33..9ec39b16f0 100644
--- a/actionpack/lib/action_view/template/resolver.rb
+++ b/actionpack/lib/action_view/template/resolver.rb
@@ -6,8 +6,8 @@ module ActionView
   # = Action View Resolver
   class Resolver
     def initialize
-      @cached = Hash.new { |h1,k1| h1[k1] =
-        Hash.new { |h2,k2| h2[k2] = Hash.new { |h3, k3| h3[k3] = {} } } }
+      @cached = Hash.new { |h1,k1| h1[k1] = Hash.new { |h2,k2|
+        h2[k2] = Hash.new { |h3,k3| h3[k3] = Hash.new { |h4,k4| h4[k4] = {} } } } }
     end
 
     def clear_cache
@@ -15,8 +15,8 @@ module ActionView
     end
 
     # Normalizes the arguments and passes it on to find_template.
-    def find_all(name, prefix=nil, partial=false, details={}, key=nil)
-      cached(key, prefix, name, partial) do
+    def find_all(name, prefix=nil, partial=false, details={}, locals=[], key=nil)
+      cached(key, prefix, name, partial, locals) do
         find_templates(name, prefix, partial, details)
       end
     end
@@ -51,9 +51,25 @@ module ActionView
       [handler, format]
     end
 
-    def cached(key, prefix, name, partial)
-      return yield unless key && caching?
-      @cached[key][prefix][name][partial] ||= yield
+    def cached(key, prefix, name, partial, locals)
+      locals = sort_locals(locals)
+      unless key && caching?
+        yield.each { |t| t.locals = locals }
+      else
+        @cached[key][prefix][name][partial][locals] ||= yield.each { |t| t.locals = locals }
+      end
+    end
+
+    if :locale.respond_to?("<=>")
+      def sort_locals(locals)
+        locals.sort.freeze
+      end
+    else
+      def sort_locals(locals)
+        locals = locals.map{ |l| l.to_s }
+        locals.sort!
+        locals.freeze
+      end
     end
   end
 
diff --git a/actionpack/lib/action_view/template/text.rb b/actionpack/lib/action_view/template/text.rb
index 51be831dfb..4261c3b5e2 100644
--- a/actionpack/lib/action_view/template/text.rb
+++ b/actionpack/lib/action_view/template/text.rb
@@ -25,10 +25,6 @@ module ActionView #:nodoc:
       def formats
         [@mime_type.to_sym]
       end
-
-      def partial?
-        false
-      end
     end
   end
 end
diff --git a/actionpack/test/template/template_test.rb b/actionpack/test/template/template_test.rb
index c7c33af670..210ba673f0 100644
--- a/actionpack/test/template/template_test.rb
+++ b/actionpack/test/template/template_test.rb
@@ -51,6 +51,7 @@ class TestERBTemplate < ActiveSupport::TestCase
 
   def test_locals
     @template = new_template("<%= my_local %>")
+    @template.locals = [:my_local]
     assert_equal "I'm a local", render(:my_local => "I'm a local")
   end