Merge pull request #760 from sass/js-perf

Improve the JS performance for logic-heavy stylesheets

CHANGELOG.md

@@ -1,3 +1,9 @@
+## 1.22.5
+
+### JavaScript API
+
+* Improve performance for logic-heavy stylesheets.
+
 ## 1.22.4
 
 * Fix a bug where at-rules imported from within a style rule would appear within

lib/src/utils.dart

@@ -306,7 +306,11 @@ bool startsWithIgnoreSeparator(String string, String prefix) {
 /// If [source] is passed, copies it into the map.
 Map<String, V> normalizedMap<V>([Map<String, V> source]) {
   var map = LinkedHashMap<String, V>(
-      equals: equalsIgnoreSeparator, hashCode: hashCodeIgnoreSeparator);
+      // Explicitly set this because the default implementation involves a type
+      // check, which is very expensive in dart2js.
+      isValidKey: (_) => true,
+      equals: equalsIgnoreSeparator,
+      hashCode: hashCodeIgnoreSeparator);
   if (source != null) map.addAll(source);
   return map;
 }
@@ -316,7 +320,11 @@ Map<String, V> normalizedMap<V>([Map<String, V> source]) {
 /// If [source] is passed, copies it into the set.
 Set<String> normalizedSet([Iterable<String> source]) {
   var set = LinkedHashSet(
-      equals: equalsIgnoreSeparator, hashCode: hashCodeIgnoreSeparator);
+      // Explicitly set this because the default implementation involves a type
+      // check, which is very expensive in dart2js.
+      isValidKey: (_) => true,
+      equals: equalsIgnoreSeparator,
+      hashCode: hashCodeIgnoreSeparator);
   if (source != null) set.addAll(source);
   return set;
 }

lib/src/visitor/async_evaluate.dart

@@ -1962,15 +1962,19 @@ class _EvaluateVisitor
       {bool trackSpans}) async {
     trackSpans ??= _sourceMap;
 
-    var positional = (await mapAsync(arguments.positional,
-            (Expression expression) => expression.accept(this)))
-        .toList();
+    var positional = [
+      for (var expression in arguments.positional) await expression.accept(this)
+    ];
     var named = await normalizedMapMapAsync<String, Expression, Value>(
         arguments.named,
         value: (_, expression) => expression.accept(this));
 
-    var positionalNodes =
-        trackSpans ? arguments.positional.map(_expressionNode).toList() : null;
+    var positionalNodes = trackSpans
+        ? [
+            for (var expression in arguments.positional)
+              _expressionNode(expression)
+          ]
+        : null;
     var namedNodes = trackSpans
         ? mapMap<String, Expression, String, AstNode>(arguments.named,
             value: (_, expression) => _expressionNode(expression))

lib/src/visitor/evaluate.dart

@@ -5,7 +5,7 @@
 // DO NOT EDIT. This file was generated from async_evaluate.dart.
 // See tool/grind/synchronize.dart for details.
 //
-// Checksum: cae91fd0fcd94fbb45712286a85761d69fef5415
+// Checksum: 1685f0e62002cbb13d3d54ea3d5166c4c7f8f678
 //
 // ignore_for_file: unused_import
 
@@ -1949,14 +1949,18 @@ class _EvaluateVisitor
       {bool trackSpans}) {
     trackSpans ??= _sourceMap;
 
-    var positional = arguments.positional
-        .map((Expression expression) => expression.accept(this))
-        .toList();
+    var positional = [
+      for (var expression in arguments.positional) expression.accept(this)
+    ];
     var named = normalizedMapMap<String, Expression, Value>(arguments.named,
         value: (_, expression) => expression.accept(this));
 
-    var positionalNodes =
-        trackSpans ? arguments.positional.map(_expressionNode).toList() : null;
+    var positionalNodes = trackSpans
+        ? [
+            for (var expression in arguments.positional)
+              _expressionNode(expression)
+          ]
+        : null;
     var namedNodes = trackSpans
         ? mapMap<String, Expression, String, AstNode>(arguments.named,
             value: (_, expression) => _expressionNode(expression))

perf.md

@@ -4,7 +4,7 @@ the benefit Dart Sass could provide relative to other implementations.
 This was tested against:
 
 * libsass 0f3d6ad1 and sassc 4674821 compiled with g++ (Debian 7.3.0-18) 7.3.0.
-* Dart Sass 088fc28 on Dart 2.4.0 and Node v12.0.0.
+* Dart Sass 50a45a7 on Dart 2.4.0 and Node v12.0.0.
 * Ruby Sass 8d1edc76 on ruby 2.5.3p105 (2018-10-18 revision 65156) [x86_64-linux].
 
 on Debian x64 with Intel Xeon E5-1650 v3 @ 3.50GHz. The Dart Sass
@@ -20,148 +20,149 @@ I ran five instances of each configuration and recorded the fastest time.
 
 Running on a file containing 4 instances of `.foo {a: b}`:
 
-* sassc: 0.004s
-* Dart Sass from a script snapshot: 0.219s
-* Dart Sass native executable: 0.020s
-* Dart Sass on Node.js: 0.200s
-* Ruby Sass with a hot cache: 0.155s
+* sassc: 0.005s
+* Dart Sass from a script snapshot: 0.216s
+* Dart Sass native executable: 0.018s
+* Dart Sass on Node.js: 0.209s
+* Ruby Sass with a hot cache: 0.148s
 
 Based on these numbers, Dart Sass from a native executable is approximately:
 
-* 5.0x slower than libsass
-* 10.0x faster than Dart Sass on Node
-* 7.8x faster than Ruby Sass
+* 3.6x slower than libsass
+* 11.6x faster than Dart Sass on Node
+* 8.2x faster than Ruby Sass
 
 ## Large Plain CSS
 
 Running on a file containing 2^17 instances of `.foo {a: b}`:
 
-* sassc: 1.714s
-* Dart Sass from a script snapshot: 1.606s
-* Dart Sass native executable: 1.547s
-* Dart Sass on Node.js: 2.672s
-* Ruby Sass with a hot cache: 11.145s
+* sassc: 1.705s
+* Dart Sass from a script snapshot: 1.550s
+* Dart Sass native executable: 1.518s
+* Dart Sass on Node.js: 2.765s
+* Ruby Sass with a hot cache: 10.965s
 
 Based on these numbers, Dart Sass from a native executable is approximately:
 
 * 1.1x faster than libsass
-* 1.7x faster than Dart Sass on Node
+* 1.8x faster than Dart Sass on Node
 * 7.2x faster than Ruby Sass
 
 ## Preceding Sparse `@extend`
 
 Running on a file containing `.x {@extend .y}`, 2^17 instances of `.foo {a: b}`, and then `.y {a: b}`:
 
-* sassc: 1.750s
-* Dart Sass from a script snapshot: 1.602s
-* Dart Sass native executable: 1.585s
-* Dart Sass on Node.js: 2.782s
-* Ruby Sass with a hot cache: 17.012s
+* sassc: 1.712s
+* Dart Sass from a script snapshot: 1.613s
+* Dart Sass native executable: 1.582s
+* Dart Sass on Node.js: 2.739s
+* Ruby Sass with a hot cache: 16.472s
 
 Based on these numbers, Dart Sass from a native executable is approximately:
 
 * 1.1x faster than libsass
-* 1.8x faster than Dart Sass on Node
-* 10.7x faster than Ruby Sass
+* 1.7x faster than Dart Sass on Node
+* 10.4x faster than Ruby Sass
 
 ## Following Sparse `@extend`
 
 Running on a file containing `.y {a: b}`, 2^17 instances of `.foo {a: b}`, and then `.x {@extend .y}`:
 
-* sassc: 1.724s
-* Dart Sass from a script snapshot: 1.610s
-* Dart Sass native executable: 1.568s
-* Dart Sass on Node.js: 2.712s
-* Ruby Sass with a hot cache: 16.670s
+* sassc: 1.701s
+* Dart Sass from a script snapshot: 1.568s
+* Dart Sass native executable: 1.543s
+* Dart Sass on Node.js: 2.821s
+* Ruby Sass with a hot cache: 16.469s
 
 Based on these numbers, Dart Sass from a native executable is approximately:
 
 * 1.1x faster than libsass
-* 1.7x faster than Dart Sass on Node
-* 10.6x faster than Ruby Sass
+* 1.8x faster than Dart Sass on Node
+* 10.7x faster than Ruby Sass
 
 ## Preceding Dense `@extend`
 
 Running on a file containing `.bar {@extend .foo}` followed by 2^17 instances of `.foo {a: b}`:
 
-* sassc: 2.290s
-* Dart Sass from a script snapshot: 2.476s
-* Dart Sass native executable: 2.566s
-* Dart Sass on Node.js: 5.399s
-* Ruby Sass with a hot cache: 29.002s
+* sassc: 2.260s
+* Dart Sass from a script snapshot: 2.405s
+* Dart Sass native executable: 2.526s
+* Dart Sass on Node.js: 5.612s
+* Ruby Sass with a hot cache: 28.690s
 
 Based on these numbers, Dart Sass from a native executable is approximately:
 
 * 1.1x slower than libsass
-* 2.1x faster than Dart Sass on Node
-* 11.3x faster than Ruby Sass
+* 2.2x faster than Dart Sass on Node
+* 11.4x faster than Ruby Sass
 
 ## Following Dense `@extend`
 
 Running on a file containing 2^17 instances of `.foo {a: b}` followed by `.bar {@extend .foo}`:
 
-* sassc: 2.317s
-* Dart Sass from a script snapshot: 2.381s
-* Dart Sass native executable: 2.461s
-* Dart Sass on Node.js: 5.481s
-* Ruby Sass with a hot cache: 29.197s
+* sassc: 2.289s
+* Dart Sass from a script snapshot: 2.396s
+* Dart Sass native executable: 2.457s
+* Dart Sass on Node.js: 6.319s
+* Ruby Sass with a hot cache: 28.708s
 
 Based on these numbers, Dart Sass from a native executable is approximately:
 
 * 1.1x slower than libsass
-* 2.2x faster than Dart Sass on Node
-* 11.9x faster than Ruby Sass
+* 2.6x faster than Dart Sass on Node
+* 11.7x faster than Ruby Sass
 
 ## Bootstrap
 
 Running on a file containing 16 instances of importing the Bootstrap framework:
 
-* sassc: 0.763s
-* Dart Sass from a script snapshot: 1.613s
-* Dart Sass native executable: 0.992s
-* Dart Sass on Node.js: 3.529s
-* Ruby Sass with a hot cache: 12.969s
+* sassc: 0.767s
+* Dart Sass from a script snapshot: 1.534s
+* Dart Sass native executable: 0.955s
+* Dart Sass on Node.js: 3.156s
+* Ruby Sass with a hot cache: 12.521s
 
 Based on these numbers, Dart Sass from a native executable is approximately:
 
-* 1.3x slower than libsass
-* 3.6x faster than Dart Sass on Node
+* 1.2x slower than libsass
+* 3.3x faster than Dart Sass on Node
 * 13.1x faster than Ruby Sass
 
 ## a11ycolor
 
 Running on a file containing test cases for a computation-intensive color-processing library:
 
-* sassc: 0.262s
-* Dart Sass from a script snapshot: 0.805s
-* Dart Sass native executable: 0.612s
-* Dart Sass on Node.js: 1.876s
-* Ruby Sass with a hot cache: 5.396s
+* sassc: 0.248s
+* Dart Sass from a script snapshot: 0.736s
+* Dart Sass native executable: 0.565s
+* Dart Sass on Node.js: 1.043s
+* Ruby Sass with a hot cache: 5.091s
 
 Based on these numbers, Dart Sass from a native executable is approximately:
 
 * 2.3x slower than libsass
-* 3.1x faster than Dart Sass on Node
-* 8.8x faster than Ruby Sass
+* 1.8x faster than Dart Sass on Node
+* 9.0x faster than Ruby Sass
 
 ## Susy
 
 Running on a file containing test cases for the computation-intensive Susy grid framework:
 
-* sassc: 0.244s
+* sassc: 0.248s
 * Dart Sass from a script snapshot: 0.673s
-* Dart Sass native executable: 0.248s
-* Dart Sass on Node.js: 1.361s
-* Ruby Sass with a hot cache: 1.576s
+* Dart Sass native executable: 0.237s
+* Dart Sass on Node.js: 0.990s
+* Ruby Sass with a hot cache: 1.527s
 
 Based on these numbers, Dart Sass from a native executable is approximately:
 
 * identical to libsass
-* 5.5x faster than Dart Sass on Node
+* 4.2x faster than Dart Sass on Node
 * 6.4x faster than Ruby Sass
 
 # Prior Measurements
 
+* [1.22.4](https://github.com/sass/dart-sass/blob/a7172a2b1dd48b339e5d57159ed364ffb9f5812e/perf.md).
 * [1.20.2](https://github.com/sass/dart-sass/blob/4b7699291c9f69533d25980d23b0647266b665f2/perf.md).
 * [1.13.4](https://github.com/sass/dart-sass/blob/b6ccc91a138e75420227ff79381c5f70e60254f1/perf.md).
 * [1.6.0](https://github.com/sass/dart-sass/blob/048cbe197a77e1cf4b837a40a5acb737e949fd5c/perf.md).

pubspec.yaml

@@ -1,5 +1,5 @@
 name: sass
-version: 1.22.4
+version: 1.22.5
 description: A Sass implementation in Dart.
 author: Dart Team <misc@dartlang.org>
 homepage: https://github.com/sass/dart-sass

tool/grind/npm.dart

@@ -40,7 +40,10 @@ void _js({@required bool release}) {
     // * We expect our test coverage to ensure that nothing throws subtypes of
     //   Error.
     // * We thoroughly test edge cases in user input.
-    if (release) ...["-O4", "--fast-startup"]
+    //
+    // We don't minify because download size isn't especially important
+    // server-side and it's nice to get readable stack traces from bug reports.
+    if (release) ...["-O4", "--no-minify", "--fast-startup"]
   ]);
   var text = destination
       .readAsStringSync()