perf(Key): don't use Map.putIfAbsent -- too slow

This change gives a 25% boost to Module benchmark.
dart-archive · May 5, 2014 · 0930b37 · vicb · May 5, 2014 · 0930b37
1 parent f673267
commit 0930b37
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Showing 2 changed files with 17 additions and 4 deletions.
diff --git a/lib/key.dart b/lib/key.dart
@@ -21,11 +21,19 @@ class Key {
    * a previous call had.  E.g. `identical(new Key(t, a), new Key(t, a))` holds.
    */
   factory Key(Type type, [Type annotation]) {
-    var annotationToKey = _typeToAnnotationToKey.putIfAbsent(type, () => {});
-    return annotationToKey.putIfAbsent(
-        annotation, () => new Key._(type, annotation, _numInstances++));
+    // Don't use Map.putIfAbsent -- too slow!
+    var annotationToKey = _typeToAnnotationToKey[type];
+    if (annotationToKey == null) {
+      _typeToAnnotationToKey[type] = annotationToKey = {};
+    }
+    Key key = annotationToKey[annotation];
+    if (key == null) {
+      annotationToKey[annotation] =
+          key = new Key._(type, annotation, _numInstances++);
+    }
+    return key;
   }
-  
+
   Key._(this.type, this.annotation, this.id);
 
   String toString() {

diff --git a/test/main.dart b/test/main.dart
@@ -835,6 +835,11 @@ createKeySpec() {
       expectEquals(new Key(Car, Turbo), new Key(Car, Turbo), true);
     });
 
+    it('should not be equal to another key where type and annotation are same '
+        'but reversed', () {
+      expectEquals(new Key(Car, Turbo), new Key(Turbo, Car), false);
+    });
+
     it('should not be equal to another key if types are different', () {
       expectEquals(new Key(Car), new Key(Porsche), false);
     });