Add benchmark for hashing. Improve hashing performance.

CHANGELOG.md

@@ -6,6 +6,7 @@
 - Generate empty constructor with semicolon instead of {}.
 - Use ArgumentError.notNull for null errors.
 - Reject dynamic fields.
+- Add simple benchmark for hashing. Improve hashing performance.
 
 ## 0.1.5
 

built_value/lib/built_value.dart

@@ -4,8 +4,6 @@
 
 library built_value;
 
-export 'package:quiver/core.dart' show hashObjects;
-
 /// Implement this for a Built Value.
 ///
 /// Then use built_value_generator.dart code generation functionality to
@@ -59,3 +57,19 @@ abstract class Builder<V extends Built<V, B>, B extends Builder<V, B>> {
 //
 // Fields marked with this annotation are allowed to be null.
 const String nullable = 'nullable';
+
+/// For use by generated code in calculating hash codes. Do not use directly.
+int $jc(int hash, int value) {
+  // Jenkins hash "combine".
+  hash = 0x1fffffff & (hash + value);
+  hash = 0x1fffffff & (hash + ((0x0007ffff & hash) << 10));
+  return hash ^ (hash >> 6);
+}
+
+/// For use by generated code in calculating hash codes. Do not use directly.
+int $jf(int hash) {
+  // Jenkins hash "finish".
+  hash = 0x1fffffff & (hash + ((0x03ffffff & hash) << 3));
+  hash = hash ^ (hash >> 11);
+  return 0x1fffffff & (hash + ((0x00003fff & hash) << 15));
+}

built_value/pubspec.yaml

@@ -8,6 +8,3 @@ homepage: https://github.com/google/built_value.dart
 
 environment:
   sdk: '>=1.8.0 <2.0.0'
-
-dependencies:
-  quiver: '>=0.21.0 <0.24.0'

built_value_generator/lib/src/source_class.dart

@@ -259,9 +259,11 @@ abstract class SourceClass implements Built<SourceClass, SourceClassBuilder> {
     if (fields.length == 0) {
       result.writeln('return ${name.hashCode};');
     } else {
-      result.writeln('return hashObjects([');
-      result.write(fields.map((field) => field.name).join(', '));
-      result.writeln(']);');
+      result.writeln(r'return $jf(');
+      result.writeln(r'$jc(' * fields.length);
+      result.writeln('0, ');
+      result.write(fields.map((field) => '${field.name}.hashCode').join('), '));
+      result.writeln('));');
     }
     result.writeln('}');
     result.writeln();

example/pubspec.yaml

@@ -19,4 +19,5 @@ dev_dependencies:
 #  built_value_generator: '^0.1.6'
   built_value_generator:
     path: ../built_value_generator
+  quiver: '>=0.21.0 <0.24.0'
   test: any

example/test/benchmark_test.dart

@@ -0,0 +1,36 @@
+// Copyright (c) 2016, Google Inc. Please see the AUTHORS file for details.
+// All rights reserved. Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+import 'package:example/simple_value.dart';
+import 'package:test/test.dart';
+
+void main() {
+  group('benchmark SimpleValue', () {
+    test('hashCode', () {
+      final value = new SimpleValue((b) => b
+        ..anInt = 0
+        ..aString = 'zero');
+      benchmark('hashCode', () => value.hashCode);
+    });
+  });
+}
+
+void benchmark(String name, function()) {
+  // Warm up.
+  for (var i = 0; i != 1000; ++i) {
+    function();
+  }
+
+  // Time.
+  for (int i = 0; i != 3; ++i) {
+    final stopwatch = new Stopwatch()..start();
+    final reps = 10000000;
+    for (var i = 0; i != reps; ++i) {
+      function();
+    }
+    final perSecond =
+        (reps / (stopwatch.elapsedMicroseconds / 1000000.0)).round();
+    print('$name: $perSecond/s');
+  }
+}

example/test/collections_test.dart

@@ -4,6 +4,7 @@
 
 import 'package:built_collection/built_collection.dart';
 import 'package:example/collections.dart';
+import 'package:quiver/core.dart';
 import 'package:test/test.dart';
 
 void main() {
@@ -70,5 +71,29 @@ void main() {
         'six': [false]
       });
     });
+
+    test('hash matches quiver hash', () {
+      final collections = new Collections((b) => b
+        ..list.add(1)
+        ..set.add('two')
+        ..map['three'] = 4
+        ..listMultimap.add(5, true)
+        ..setMultimap.add('six', false));
+
+      expect(
+          collections.hashCode,
+          hashObjects([
+            collections.list,
+            collections.set,
+            collections.map,
+            collections.listMultimap,
+            collections.setMultimap,
+            collections.nullableList,
+            collections.nullableSet,
+            collections.nullableMap,
+            collections.nullableListMultimap,
+            collections.nullableSetMultimap,
+          ]));
+    });
   });
 }

example/test/compound_value_test.dart

@@ -4,6 +4,7 @@
 
 import 'package:example/compound_value.dart';
 import 'package:example/validated_value.dart';
+import 'package:quiver/core.dart';
 import 'package:test/test.dart';
 
 void main() {
@@ -28,5 +29,14 @@ void main() {
             ..validatedValue.anInt = 2).validatedValue.anInt,
           2);
     });
+
+    test('hash matches quiver hash', () {
+      final value = new CompoundValue((b) => b
+        ..simpleValue.anInt = 1
+        ..simpleValue.aString = 'two');
+
+      expect(value.hashCode,
+          hashObjects([value.simpleValue, value.validatedValue]));
+    });
   });
 }