Set asset-cached file ctime and mtime to the max mtime of the combined files. Allows for consistent ETag generation without having a shared filesystem.

2 files changed, 7 insertions, 1 deletions

diff --git a/actionpack/lib/action_view/helpers/asset_tag_helper.rb b/actionpack/lib/action_view/helpers/asset_tag_helper.rb
index 1e44b166d9..c2b4f51c9c 100644
--- a/actionpack/lib/action_view/helpers/asset_tag_helper.rb
+++ b/actionpack/lib/action_view/helpers/asset_tag_helper.rb
@@ -618,6 +618,11 @@ module ActionView
         def write_asset_file_contents(joined_asset_path, asset_paths)
           FileUtils.mkdir_p(File.dirname(joined_asset_path))
           File.open(joined_asset_path, "w+") { |cache| cache.write(join_asset_file_contents(asset_paths)) }
+
+          # Set mtime to the latest of the combined files to allow for
+          # consistent ETag without a shared filesystem.
+          mt = asset_paths.map { |p| File.mtime(File.join(ASSETS_DIR, p)) }.max
+          File.utime(mt, mt, joined_asset_path)
         end
 
         def collect_asset_files(*path)
diff --git a/actionpack/test/template/asset_tag_helper_test.rb b/actionpack/test/template/asset_tag_helper_test.rb
index 8410e82c3c..7e40a55dc5 100644
--- a/actionpack/test/template/asset_tag_helper_test.rb
+++ b/actionpack/test/template/asset_tag_helper_test.rb
@@ -425,7 +425,8 @@ class AssetTagHelperTest < ActionView::TestCase
       stylesheet_link_tag(:all, :cache => true)
     )
 
-    assert File.exist?(File.join(ActionView::Helpers::AssetTagHelper::STYLESHEETS_DIR, 'all.css'))
+    expected = Dir["#{ActionView::Helpers::AssetTagHelper::STYLESHEETS_DIR}/*.css"].map { |p| File.mtime(p) }.max
+    assert_equal expected, File.mtime(File.join(ActionView::Helpers::AssetTagHelper::STYLESHEETS_DIR, 'all.css'))
 
     assert_dom_equal(
       %(<link href="http://a0.example.com/stylesheets/money.css" media="screen" rel="stylesheet" type="text/css" />),