gistfile1.m

- (void)testJavaScriptCallSpeed
{
  int const runs = 4e5;
  int const frequency = 10;
  double const threshold = 0.1;
  static double const expectedTimes[] = {
    0x1.469c0a1af80e3p+14,
    0x1.5cb66713b13b1p+14,
    0x1.593e1e9f7248p+14,
    0x1.5d5f559066c1p+14,
  };

  dispatch_semaphore_t semaphore = dispatch_semaphore_create(0);
  RCTContextExecutor *executor = RCTCreateExecutor([RCTContextExecutor class]);
  NSString *script = @" \
    var modules = { \
      module: { \
        method: function () { \
          return true; \
        } \
      } \
    }; \
    function require(module) { \
      return modules[module]; \
    } \
  ";

  [executor executeApplicationScript:script sourceURL:[NSURL URLWithString:@"http://localhost:8081/"] onComplete:^(NSError *error) {
    NSMutableArray *params = [[NSMutableArray alloc] init];
    id data = @1;
    for (int i = 0; i < 4; i++) {
      double samples[runs / frequency];
      int size = runs / frequency;
      double total = 0;
      for (int j = 0; j < runs; j++) {
        @autoreleasepool {
          double start = _get_time_nanoseconds();
          [executor executeJSCall:@"module"
                           method:@"method"
                        arguments:params
                          context:RCTGetExecutorID(executor)
                         callback:^(id json, NSError *__error) {
                           RCTAssert([json isEqual:@YES], @"Invalid return");
                         }];
          double run = _get_time_nanoseconds() - start;
          if ((j % frequency) == frequency - 1) { // Warmup
            total += run;
            samples[j/frequency] = run;
          }
        }
      }

      double mean = total / size;
      double variance = 0;

      for (int j = 0; j < size; j++) {
        variance += pow(samples[j] - mean, 2);
      }
      variance /= size;

      double standardDeviation = sqrt(variance);
      double marginOfError = standardDeviation * 1.645;

      double lower = mean - marginOfError;
      double upper = mean + marginOfError;

      int s = 0;
      total = 0;
      for (int j = 0; j < size; j++) {
        double v = samples[j];
        if (v >= lower && v <= upper) {
          samples[s++] = v;
          total += v;
        }
      }
      mean = total / s;

      lower = mean * (1.0 - threshold);
      upper = mean * (1.0 + threshold);

      double expected = expectedTimes[i];

      NSLog(@"Previous: %lf, New: %f -> %a", expected, mean, mean);
      if (upper < expected) {
        NSLog(@"You made JS calls with %d argument(s) %.2lf%% faster :) - Remember to update the tests with the new value: %a",
                      i, (1 - (double)mean / expected) * 100, mean);
      }


      STAssertTrue(lower < expected, @"You made JS calls with %d argument(s) %.2lf%% slower :( - If that's *really* necessary, update the tests with the new value: %a",
        i, ((double)mean / expected - 1) * 100, mean);

      [params addObject:data];
    }
    dispatch_semaphore_signal(semaphore);
  }];

  while (dispatch_semaphore_wait(semaphore, DISPATCH_TIME_NOW)) {
    [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode
                             beforeDate:[NSDate dateWithTimeIntervalSinceNow:10]];
  }
}