Make digest cache work in development.

Avoid computing the same fragment digest many times when looping over templates.

The cache is cleared on every request so template changes are still picked up.

4 files changed, 79 insertions, 14 deletions

diff --git a/actionview/lib/action_view/digestor.rb b/actionview/lib/action_view/digestor.rb
index df8059d04e..4224346a2f 100644
--- a/actionview/lib/action_view/digestor.rb
+++ b/actionview/lib/action_view/digestor.rb
@@ -8,6 +8,13 @@ module ActionView
     @@cache          = ThreadSafe::Cache.new
     @@digest_monitor = Monitor.new
 
+    class PerRequestDigestCacheExpiry < Struct.new(:app) # :nodoc:
+      def call(env)
+        ActionView::Digestor.cache.clear
+        app.call(env)
+      end
+    end
+
     class << self
       # Supported options:
       #
@@ -41,10 +48,7 @@ module ActionView
             Digestor
           end
 
-          digest = klass.new(options).digest
-          # Store the actual digest if config.cache_template_loading is true
-          @@cache[cache_key] = stored_digest = digest if ActionView::Resolver.caching?
-          digest
+          @@cache[cache_key] = stored_digest = klass.new(options).digest
         ensure
           # something went wrong or ActionView::Resolver.caching? is false, make sure not to corrupt the @@cache
           @@cache.delete_pair(cache_key, false) if pre_stored && !stored_digest
diff --git a/actionview/lib/action_view/railtie.rb b/actionview/lib/action_view/railtie.rb
index 5dc7950d6b..e829d86c99 100644
--- a/actionview/lib/action_view/railtie.rb
+++ b/actionview/lib/action_view/railtie.rb
@@ -42,6 +42,14 @@ module ActionView
       end
     end
 
+    initializer "action_view.per_request_digest_cache" do |app|
+      ActiveSupport.on_load(:action_view) do
+        if app.config.consider_all_requests_local
+          app.middleware.use ActionView::Digestor::PerRequestDigestCacheExpiry
+        end
+      end
+    end
+
     initializer "action_view.setup_action_pack" do |app|
       ActiveSupport.on_load(:action_controller) do
         ActionView::RoutingUrlFor.include(ActionDispatch::Routing::UrlFor)
diff --git a/actionview/test/template/digestor_test.rb b/actionview/test/template/digestor_test.rb
index f0afcdb5ae..97e3c6e7b9 100644
--- a/actionview/test/template/digestor_test.rb
+++ b/actionview/test/template/digestor_test.rb
@@ -239,16 +239,6 @@ class TemplateDigestorTest < ActionView::TestCase
     assert_not_equal digest_phone, digest_fridge_phone
   end
 
-  def test_cache_template_loading
-    resolver_before = ActionView::Resolver.caching
-    ActionView::Resolver.caching = false
-    assert_digest_difference("messages/edit", true) do
-      change_template("comments/_comment")
-    end
-  ensure
-    ActionView::Resolver.caching = resolver_before
-  end
-
   def test_digest_cache_cleanup_with_recursion
     first_digest = digest("level/_recursion")
     second_digest = digest("level/_recursion")
diff --git a/railties/test/application/per_request_digest_cache_test.rb b/railties/test/application/per_request_digest_cache_test.rb
new file mode 100644
index 0000000000..3198e12662
--- /dev/null
+++ b/railties/test/application/per_request_digest_cache_test.rb
@@ -0,0 +1,63 @@
+require 'isolation/abstract_unit'
+require 'rack/test'
+require 'minitest/mock'
+
+require 'action_view'
+require 'active_support/testing/method_call_assertions'
+
+class PerRequestDigestCacheTest < ActiveSupport::TestCase
+  include ActiveSupport::Testing::Isolation
+  include ActiveSupport::Testing::MethodCallAssertions
+  include Rack::Test::Methods
+
+  setup do
+    build_app
+    add_to_config 'config.consider_all_requests_local = true'
+
+    app_file 'app/models/customer.rb', <<-RUBY
+      class Customer < Struct.new(:name, :id)
+        extend ActiveModel::Naming
+        include ActiveModel::Conversion
+      end
+    RUBY
+
+    app_file 'config/routes.rb', <<-RUBY
+      Rails.application.routes.draw do
+        resources :customers, only: :index
+      end
+    RUBY
+
+    app_file 'app/controllers/customers_controller.rb', <<-RUBY
+      class CustomersController < ApplicationController
+        def index
+          render [ Customer.new('david', 1), Customer.new('dingus', 2) ]
+        end
+      end
+    RUBY
+
+    app_file 'app/views/customers/_customer.html.erb', <<-RUBY
+      <% cache customer do %>
+        <%= customer.name %>
+      <% end %>
+    RUBY
+
+    require "#{app_path}/config/environment"
+  end
+
+  teardown :teardown_app
+
+  test "digests are reused when rendering the same template twice" do
+    get '/customers'
+    assert_equal 200, last_response.status
+
+    assert_equal [ '8ba099b7749542fe765ff34a6824d548' ], ActionView::Digestor.cache.values
+    assert_equal %w(david dingus), last_response.body.split.map(&:strip)
+  end
+
+  test "template digests are cleared before a request" do
+    assert_called(ActionView::Digestor.cache, :clear) do
+      get '/customers'
+      assert_equal 200, last_response.status
+    end
+  end
+end