exec-time/index.js

See how much time every step of a script takes to execute

var util = require('util');

function formatTime (time, precision) {
  // If we're dealing with ms, round up to seconds when time is at least 1 second
  if (time > 1000 && precision == 'ms') {
    return (Math.floor(time / 100) / 10) + ' s';
  } else {
    return time.toFixed(3) + ' ' + precision;
  }
}

// get time in ns
function getTime() {
  var t = process.hrtime();
  return (t[0] * 1e9 + t[1]);
}


console.log(getTime());

var a = getTime();
setTimeout(function() {
  console.log((getTime() - a) / 1e6);
}, 1175);



/**
 * Create a profiler with name testName to monitor the execution time of a route
 * The profiler has two arguments: a step msg and an optional reset for the internal timer
 * It will display the execution time per step and total from latest rest
 *
 * Optional logToConsole flag, which defaults to true, causes steps to be printed to console.
 * otherwise, they can be accessed from Profiler.steps array.
 */
function Profiler (name, logToConsole, precision) {
  this.name = name;
  this.steps = [];
  this.sinceBeginning = null;
  this.lastStep = null;
  this.logToConsole = typeof(logToConsole) === 'undefined' ? true : logToConsole;
  this.precision = typeof(precision) === 'undefined' ? 'ms' : precision
  this.divisor = 1;

  if (this.precision === 'ms') this.divisor = 1e6;
}


Profiler.prototype.beginProfiling = function () {
  if (this.logToConsole) { console.log(this.name + ' - Begin profiling'); }
  this.resetTimers();
};


Profiler.prototype.resetTimers = function () {
  this.sinceBeginning = getTime();
  this.lastStep = getTime();
  this.steps.push(['BEGIN_TIMER', this.lastStep])
};


Profiler.prototype.elapsedSinceBeginning = function () {
  return (getTime() - this.sinceBeginning) / this.divisor;
}


Profiler.prototype.elapsedSinceLastStep = function () {
  return (getTime() - this.lastStep) / this.divisor;
}

// Return the deltas between steps, in nanoseconds

Profiler.prototype.getSteps = function () {
  var divisor = this.divisor;

  return this.steps.map(function(curr, index, arr) {
    if (index === 0) return;
    var delta = (curr[1] - arr[index-1][1]);
    return [curr[0], (delta / divisor)];
  }).slice(1);
}

Profiler.prototype.step = function (msg) {
  if (!this.sinceBeginning || !this.lastStep) {
    console.log(util.format(
      '%s - %s - You must call beginProfiling before registering steps',
      this.name,
      msg
    ));
    return;
  }

  if (this.logToConsole) { 
    console.log(util.format('%s - %s - %s (total: %s)',
      this.name, 
      msg,
      formatTime(this.elapsedSinceLastStep(), this.precision),
      formatTime(this.elapsedSinceBeginning(), this.precision)
    ));
  }

  this.lastStep = getTime();
  this.steps.push([msg, this.lastStep]);
};



module.exports = Profiler;