let startTime  = process.hrtime()
let startUsage = process.cpuUsage()

let keepTime = process.hrtime()
let keepUsage = process.cpuUsage()
let sw = false

setInterval(() => {
	if(!sw) {
		keepTime = process.hrtime();
    	keepUsage = process.cpuUsage();
    	sw = true;
	} else {
		startTime = keepTime;
		startUsage = keepUsage;
		sw = false;
	} 
}, 500)

module.exports = () => {
    function secNSec2ms (secNSec) {
      return secNSec[0] * 1000 + secNSec[1] / 1000000
    }

    var elapTime = process.hrtime(startTime)
    var elapUsage = process.cpuUsage(startUsage)

    var elapTimeMS = secNSec2ms(elapTime)
    var elapUserMS = elapUsage.user
    var elapSystMS = elapUsage.system

    return Math.round(100 * ((elapUserMS + elapSystMS) / 1000) / elapTimeMS)
}