dart:mirrors benchmark

benchmark_mirrors.dart

import 'dart:mirrors';

class Class {
  int field;
}

final mirror = reflectClass(Class);
final constructor = const Symbol('');

main() {
  testIterations(100, 'a hundred');
  testIterations(1000, 'a thousand');
  testIterations(10000, '10 thousand');
  testIterations(20000, '20 thousand');
  testIterations(50000, '50 thousand');
  testIterations(100000, 'a hundred thousand');
  testIterations(1000000, 'a million');
  testIterations(2000000, 'two million');
  testIterations(5000000, 'five million');
  testIterations(10000000, 'ten million');
}

testIterations(int times, String description) {
  final repeats = 50;

  // Repeat 50 times
  var durationsMirrors = 0;
  for (var i in new List.filled(repeats, 1)) {

    // Start times
    var starttimeMirrors = new DateTime.now().millisecondsSinceEpoch;
    // Run benchmark
    testWithMirrors(times);
    // Sum up the milliseconds each iteration of the test takes
    durationsMirrors += new DateTime.now().millisecondsSinceEpoch - starttimeMirrors;
  }
  // Get the average milliseconds it took the complete the test
  var durationMirrors = durationsMirrors / repeats;

  // Do the same for the test without mirrors
  var durationsWithoutMirrors = 0;
  for (var i in new List.filled(repeats, 1)) {
    var starttimeWithoutMirrors = new DateTime.now().millisecondsSinceEpoch;
    testWithoutMirrors(times);
    durationsWithoutMirrors += new DateTime.now().millisecondsSinceEpoch - starttimeWithoutMirrors;
  }
  var durationWithoutMirrors = durationsWithoutMirrors / repeats;

  // Get how many times slower the mirrors implementation was
  var slower = durationMirrors / durationWithoutMirrors;

  print('''$description instantiations and assignments:
  using mirrors: $durationMirrors ms
  without using mirrors: $durationWithoutMirrors ms
  ${slower.toString() == 'Infinity'
  ? 'Without using mirrors was to quick to measure'
  : 'Mirrors was $slower times slower.'}''');
}

testWithMirrors(int times) {
  for (var i in new List<int>.filled(times, 1))
    mirror.newInstance(constructor, []).setField(#field, i);
}

testWithoutMirrors(int times) {
  for (var i in new List<int>.filled(times, 1))
    new Class().field = i;
}