test: Add very basic benchmark infrastructure (#3431)

Add very basic benchmark infrastructure, using the `examples` app as a
centralized benchmark playground and with first ever benchmark file just
testing some components and updates (more to come).

This also sets up the `dart-benchmark-action` to run, starting on this
very PR!

.github/workflows/benchmark.yml

@@ -0,0 +1,20 @@
+name: Benchmark
+
+on: [pull_request]
+
+jobs:
+  benchmark:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: subosito/flutter-action@v2
+      - uses: bluefireteam/melos-action@v3
+
+      - uses: luanpotter/[email protected]
+        with:
+          paths: "packages/flame/"
+          ignore-tag: "no-benchmark"
+          is-flutter: true
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

packages/flame/benchmark/main.dart

@@ -0,0 +1,5 @@
+import 'update_components_benchmark.dart';
+
+Future<void> main() async {
+  await UpdateComponentsBenchmark.main();
+}

packages/flame/benchmark/update_components_benchmark.dart

@@ -0,0 +1,96 @@
+import 'dart:math';
+
+import 'package:benchmark_harness/benchmark_harness.dart';
+import 'package:flame/components.dart';
+import 'package:flame/game.dart';
+
+const _amountComponents = 20;
+const _amountTicks = 1000;
+const _amountInputs = 100;
+
+class UpdateComponentsBenchmark extends AsyncBenchmarkBase {
+  final Random random;
+
+  late final FlameGame _game;
+  late final List<_BenchmarkComponent> _components;
+  late final List<double> _dts;
+  late final Set<int> _inputTicks;
+
+  UpdateComponentsBenchmark(this.random)
+      : super('Updating Components Benchmark');
+
+  static Future<void> main() async {
+    final r = Random(69420);
+    await UpdateComponentsBenchmark(r).report();
+  }
+
+  @override
+  Future<void> setup() async {
+    _game = FlameGame();
+    await _game.addAll(
+      List.generate(_amountComponents, _BenchmarkComponent.new),
+    );
+
+    await _game.ready();
+
+    _components =
+        _game.children.whereType<_BenchmarkComponent>().toList(growable: false);
+
+    _dts = List.generate(_amountTicks, (_) => random.nextDouble());
+    _inputTicks = List.generate(
+      _amountInputs,
+      (_) => random.nextInt(_amountTicks),
+    ).toSet();
+  }
+
+  @override
+  Future<void> exercise() async {
+    for (final (idx, dt) in _dts.indexed) {
+      if (_inputTicks.contains(idx)) {
+        _components[random.nextInt(_amountComponents)].input(
+          xDirection: random.nextInt(3) - 1,
+          doJump: random.nextBool(),
+        );
+      }
+      _game.update(dt);
+    }
+  }
+}
+
+class _BenchmarkComponent extends PositionComponent {
+  static const _groundY = -20.0;
+
+  final int id;
+  final Vector2 velocity = Vector2.zero();
+
+  _BenchmarkComponent(this.id);
+
+  void input({
+    required int xDirection,
+    required bool doJump,
+  }) {
+    // move x
+    velocity.x = xDirection * 100;
+
+    // jump
+    if (position.y == _groundY) {
+      velocity.y -= 100;
+    }
+  }
+
+  @override
+  void update(double dt) {
+    super.update(dt);
+
+    position.add(velocity * dt);
+    velocity.add(Vector2(0, 10 * dt));
+
+    if (position.y > _groundY) {
+      position.y = _groundY;
+      velocity.setValues(0, 0);
+    }
+  }
+
+  @override
+  String toString() => '[Component $id]';
+}

packages/flame/pubspec.yaml

@@ -25,6 +25,7 @@ dependencies:
   vector_math: ^2.1.4
 
 dev_dependencies:
+  benchmark_harness: ^2.3.1
   canvas_test: ^0.2.0
   dartdoc: ^8.0.8
   flame_lint: ^1.2.1