Fix a Rails perf issue.

Closes sass#124.
tenderlove · Aug 21, 2012 · 527e2f4 · 527e2f4
1 parent 78c02f9
commit 527e2f4
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diff --git a/doc-src/SASS_CHANGELOG.md b/doc-src/SASS_CHANGELOG.md
@@ -3,6 +3,11 @@
 * Table of contents
 {:toc}
 
+## 3.2.2 (Unreleased)
+
+* Fix a performance issue with `@import` that only appears when
+  ActiveSupport is loaded.
+
 ## 3.2.1 (15 August 2012)
 
 * Fix a buggy interaction with Pow and Capybara that caused `EOFError`s.

diff --git a/lib/sass/importers/filesystem.rb b/lib/sass/importers/filesystem.rb
@@ -28,7 +28,7 @@ def find(name, options)
 
       # @see Base#mtime
       def mtime(name, options)
-        file, s = find_real_file(@root, name)
+        file, s = Sass::Util.destructure(find_real_file(@root, name))
         File.mtime(file) if file
       rescue Errno::ENOENT
         nil
@@ -132,7 +132,7 @@ def split(name)
       private
 
       def _find(dir, name, options)
-        full_filename, syntax = find_real_file(dir, name)
+        full_filename, syntax = Sass::Util.destructure(find_real_file(dir, name))
         return unless full_filename && File.readable?(full_filename)
 
         options[:syntax] = syntax

diff --git a/lib/sass/plugin/staleness_checker.rb b/lib/sass/plugin/staleness_checker.rb
@@ -140,7 +140,7 @@ def mtime(uri, importer)
       end
 
       def dependencies(uri, importer)
-        stored_mtime, dependencies = @dependencies[[uri, importer]]
+        stored_mtime, dependencies = Sass::Util.destructure(@dependencies[[uri, importer]])
 
         if !stored_mtime || stored_mtime < mtime(uri, importer)
           dependencies = compute_dependencies(uri, importer)

diff --git a/lib/sass/scss/parser.rb b/lib/sass/scss/parser.rb
@@ -706,7 +706,7 @@ def placeholder_selector
       end
 
       def element_name
-        ns, name = qualified_name(:allow_star_name)
+        ns, name = Sass::Util.destructure(qualified_name(:allow_star_name))
         return unless ns || name
 
         if name == '*'
@@ -797,7 +797,7 @@ def pseudo_arg
         # could start a pseudo expression like "n+1", or it could start a
         # selector like "n|m". In order to handle this, we must regrettably
         # backtrack.
-        expr, sel = nil
+        expr, sel = nil, nil
         pseudo_err = catch_error do
           expr = pseudo_expr
           next if tok?(/[,)]/)

diff --git a/lib/sass/util.rb b/lib/sass/util.rb
@@ -467,6 +467,19 @@ def glob(path, &block)
       Dir.glob(path, &block)
     end
 
+    # Prepare a value for a destructuring assignment (e.g. `a, b =
+    # val`). This works around a performance bug when using
+    # ActiveSupport, and only needs to be called when `val` is likely
+    # to be `nil` reasonably often.
+    #
+    # See [this bug report](http://redmine.ruby-lang.org/issues/4917).
+    #
+    # @param val [Object]
+    # @return [Object]
+    def destructure(val)
+      val || []
+    end
+
     ## Cross-Ruby-Version Compatibility
 
     # Whether or not this is running under Ruby 1.8 or lower.