lib/metrics/platforms/generic/system-cpu.js

/*
 * Copyright Elasticsearch B.V. and other contributors where applicable.
 * Licensed under the BSD 2-Clause License; you may not use this file except in
 * compliance with the BSD 2-Clause License.
 */

'use strict';

const os = require('os');

function cpuAverage() {
  const times = {
    user: 0,
    nice: 0,
    sys: 0,
    idle: 0,
    irq: 0,
    total: 0,
  };

  const cpus = os.cpus();
  for (const cpu of cpus) {
    for (const type of Object.keys(cpu.times)) {
      times[type] += cpu.times[type];
      times.total += cpu.times[type];
    }
  }

  // Average over CPU count
  const averages = {};
  for (const type of Object.keys(times)) {
    averages[type] = times[type] / cpus.length;
  }

  return averages;
}

function cpuPercent(last, next) {
  const idle = next.idle - last.idle;
  const total = next.total - last.total;
  return 1 - idle / total || 0;
}

let last = cpuAverage();

module.exports = function systemCPUUsage() {
  const next = cpuAverage();
  const result = cpuPercent(last, next);
  last = next;
  return result;
};