Rudimentary capturing of CPU busy time in Node.js

nodejs-cpu-capture.js

'use strict';

var os = require('os');
var hasWrittenHeader = false;
var fileStream = require('fs').createWriteStream('cpuProfile.out');

function buildResults() {
	var output = '';
	var cpus = os.cpus();
	var cpu;

	for (var cpuIndex in cpus) {
		cpu = cpus[cpuIndex];
		output += 'CPU ' + cpuIndex + ': ' + calculateBusyTime(cpu) + '% busy\n';
	}

	return output;
}

function calculateBusyTime(cpu) {
	var total = cpu.times.user + cpu.times.sys + cpu.times.idle;
	var busy = cpu.times.user + cpu.times.sys;

	return Math.round(busy / total * 100);
}

module.exports = {
	captureNext: function captureNext() {
		var date = new Date().toString();
		var results = buildResults();
		var output = date + ':\n' + results + '\n\n';

		fileStream.write(output);
	},

	writeResults: function writeResults() {
		fileStream.end();
	}
};