module that returns system health info

performance.js

// const startUsage = process.cpuUsage();
// // { user: 38579, system: 6986 }

// // spin the CPU for 500 milliseconds
// const now = Date.now();
// while (Date.now() - now < 500);

// console.log(process.cpuUsage(startUsage));
// // { user: 514883, system: 11226 }

let prev = process.hrtime();
let prevUsage = process.cpuUsage();

let average = 0;
let averageSum = 0;
let averageCount = 0;
let busy = false;
let delay = 0;
let cpuUsage = process.cpuUsage(prevUsage);

let startTime = process.hrtime();
while (process.hrtime(startTime) * 1e-6 < 500) {
}
const maxCpu = process.cpuUsage();

const maxCpuTime = maxCpu.user + maxCpu.system;
let currentCpuTime = 0;

console.log(`maxCpu ${JSON.stringify(maxCpu)}`);

setInterval(async () => {
  delay = Math.round(process.hrtime(prev)[1] * 1e-6);
  prev = process.hrtime();
  averageSum += delay;
  averageCount++;

  average = Math.round(averageSum / averageCount);

  if (averageCount >= 10) {
    averageSum = average;
    averageCount = 1;
  }

  // console.log(`Delay ${delay}ms, Average: ${average !== 0 ? average : delay}ms`);
  busy = delay >= 400 || average >= 400;
  cpuUsage = process.cpuUsage(prevUsage);
  currentCpuTime = cpuUsage.user + cpuUsage.system;
  prevUsage = process.cpuUsage();
}, 1000);

module.exports = {
  delay: () => average,
  busy: () => busy,
  cpuUsage: () => Math.round((currentCpuTime / maxCpuTime)*100)
};