import 'dart:async';

void main() async {
  await loop(1e3.toInt());
  await loop(1e6.toInt());
}
int sc = 100;
Future<void> loop(int iter) async {
  List<int> asyncResult = [];
  List<int> futureResult = [];
  List<int> syncResult = [];
  for (var j = 0; j < sc; j++) {
  // Async
  var sw1 = new Stopwatch()..start();
  num count1 = 0;
  for (var i = 0; i < iter; i++) {
    count1 += await foo();
  }
  asyncResult.add(sw1.elapsedMicroseconds);

  // Future
  var sw2 = new Stopwatch()..start();
  num count2 = 0;
  for (var i = 0; i < iter; i++) {
    await foo().then((_) {
      count2 += _;
      if (i == iter-1) {
        futureResult.add(sw2.elapsedMicroseconds);
      }
    });
  }

  // sync
  var sw3 = new Stopwatch()..start();
  num count3 = 0;
  for (var i = 0; i < iter; i++) {
    count3 += bar();
  }
  syncResult.add(sw3.elapsedMicroseconds);
  }
  print("-- $iter (avg of $sc)");
  print('async : ${asyncResult.reduce((a, b) => a+b) / asyncResult.length / 1000}ms');
  print('future: ${futureResult.reduce((a, b) => a+b) / futureResult.length / 1000}ms');
  print('sync  : ${syncResult.reduce((a, b) => a+b) / syncResult.length / 1000}ms');
}

Future<num> foo() async {
  return 1;
}

num bar() {
  return 1;
}