wellness-linux-cpu/index.js

Wellness module to check linux CPU usage.

'use strict';
var is = require('is2');
var inspect = require('inspect-1-line');
var debug = require('debug')('wellness-linux-cpu');
var cpuLoad = 0.0;

/**
 * The check for free CPU
 * @param {function} cb - A standard call back for async.parallel
 */
function checkCpuUsage(cb) {
    if (!is.func(cb)) {
        var err = new Error('Bad cb argument checkCpuUsage: '+inspect(cb));
        throw err;
    }
    if (process.platform !== 'linux')
        return cb(null, 'CPU usage: unknown (only works on Linux)', true);

    debug('in checkCpuUsage');
    if (cpuLoad > 80)
        return cb(null, 'CPU usage too high: '+cpuLoad+'%', false);
    return cb(null, 'CPU usage: '+cpuLoad+'%', true);
}

/**
 * Get the CPU average for 500ms every 2500 ms.
 */
function sampleCpuUsage() {
    cpuLoad(500, function(load) {
        debug('CPU utilization: '+load+'%');
        cpuLoad = load;
    });
}

if (process.platform === 'linux') {
    setInterval(sampleCpuUsage, 2500);
}


module.exports = checkCpuUsage;