/**
 * Returns the average delay between a tick of the node.js event loop, as measured for N calls of `process.nextTick`
 */
export async function eventLoopDelay(
  iterations: number = 10000,
): Promise<number> {
  const jobs: Array<() => Promise<number>> = [];

  async function sleepyFunc(): Promise<number> {
    return new Promise((resolve) => {
      const start = process.hrtime();
      process.nextTick(() => {
        const delta = process.hrtime(start);
        const ms = delta[0] * 1000 + delta[1] / 1000000;
        resolve(ms);
      });
    });
  }

  let i = 0;
  while (i < iterations) {
    jobs.push(sleepyFunc);
    i++;
  }

  const results = [];
  for (const job of jobs) results.push(await job());

  let sum = 0;
  results.forEach((t) => (sum += t));

  const avg = Math.round((sum / results.length) * 10000) / 1000;
  return avg;
}