TimeSyncing using a stats library + slow server faking

lib/backend/server.js

@@ -18,6 +18,9 @@ var argv = optimist.options('port', {
   alias: 'l',
   "default": 'info',
   describe: 'Log level'
+}).options('slow', {
+ bool: true,
+ describe: 'Fake slow connection' 
 }).argv;
 
 winston.setLevels(winston.config.syslog.levels);
@@ -60,6 +63,23 @@ app.get('/', function(req, res, next){
 function getTime(cb){
   return cb(new Date().getTime());
 }
+function makeSlow(func) {
+  return function(cb){
+    setTimeout(function(){
+      func(function(){
+        var args = arguments;
+        setTimeout(function(){
+          cb.apply(null, args);
+        }, 200 + (Math.random()*20) + (Math.random()>.90?100:0) +  (Math.random()>.97?300:0));
+      });
+    }, 200  + (Math.random()*20)+ (Math.random()>.90?100:0) +  (Math.random()>.97?300:0));
+  };
+}
+
+if(argv.slow){
+  winston.notice('Server running on slow mode');
+  getTime = makeSlow(getTime);
+}
 
 var channels = {};
 

lib/public/index.html

@@ -81,6 +81,7 @@ <h1 id="title"></h1>
 
   <!-- scripts concatenated and minified via ant build script-->
   <script src="/js/helper.js"></script>
+  <script src="/js/faststats.js"></script>
   <script src="/socket.io/socket.io.js"></script>
   <script src="/js/libs/underscore.js"></script>
   <script src="/js/libs/backbone.js"></script>

lib/public/js/app.js

@@ -51,20 +51,12 @@ ms.bind('progress', function() {
 
 });
 
-
-
 */
 
-
-
 if(typeof ms == "undefined") {
   ms = {};
 }
 
-_.avg = function (values) {
-  return _.reduce(values, function(a, b){ return a + b; }, 0) / values.length;
-};
-
 var pathparts = window.location.pathname.split('/');
 ms.channel = pathparts[1];
 
@@ -75,25 +67,27 @@ _.extend(ms, Backbone.Events);
 // Measure helper class
 var Measure = function(opt) {
   this.opt = _.defaults(opt || {}, {
-    samples: 3,
-    retries: 3,
+    minSamples: 4,
+    maxSamples: 30,
+    maxErrors: 5,
     timeout: 400,
-    sleep: 120, //ms
-    deviation: 30,
+    sleep: 50, //ms
+    moe: 10,
     max: null,
     min: null
   });
   this.errors = 0;
   this.ready = false;
   this.value = 0;
   this.i = 0;
+  this.samples = 0;
 
   _.bindAll(this, 'measure');
 };
 Measure.prototype = _.extend(Backbone.Events, {
   run: function(iterator) {
     this.iterator = iterator;
-    this.results = [];
+    this.results = new Stats();
     this.measure();
   },
   measure: function() {
@@ -103,14 +97,14 @@ Measure.prototype = _.extend(Backbone.Events, {
   },
   measureResponder: function(index, result){
     if (this.i != index) {
-      return this.trigger('error', {msg: 'Wrong response order.'});
+      return;
+      //return this.trigger('error', {msg: 'Wrong response order.'});
     }
     var timeNow = new Date().getTime();
     if ((this.opt.timeout == null && timeNow - this._requestTime > this.opt.timeout) ||
-      (this.results.length && Math.abs(_.avg(this.results) -  result) > this.opt.deviation) ||
       (this.opt.min != null && result < this.opt.min) || (this.opt.max != null && result > this.opt.max)) {
         this.errors++;
-        if (this.errors >= this.opt.retries) {
+        if (this.errors >= this.opt.maxErrors) {
           this.ready = false;
           this.trigger('error', {msg: 'Max retries limit'});
         }
@@ -119,15 +113,36 @@ Measure.prototype = _.extend(Backbone.Events, {
         }
     }
     else {
+      this.samples++;
       this.results.push(result);
-      if (this.results.length >= this.opt.samples) {
-        this.value = _.avg(this.results);
+      if (this.samples < this.opt.minSamples) {
+        return _.delay(this.measure, this.opt.sleep);
+      }
+
+      var moe = this.results.moe();
+      var moeReq = this.opt.moe;
+      if (this.samples < this.opt.maxSamples * .3) {
+        moeReq*=.5;
+      }
+      else if(this.samples > this.opt.maxSamples * .85){
+        moeReq*=2;
+      }
+      if (moe <= moeReq) {
         this.ready = true;
-        this.trigger('ready', this.value);
+        this.value = this.results.amean();
+        return this.trigger('ready', this.value);
       }
-      else {
-        _.delay(this.measure, this.opt.sleep);
+      //console.log('result was', result, this.results.amean(), moe, moeReq, this.samples);
+      if (this.samples >= this.opt.maxSamples) {
+        this.ready = false;
+        return this.trigger('error', {msg: 'Max samples limit'});
       }
+
+      if (this.samples >= this.minSamples) {
+        this.results = this.results.irq();
+      }
+
+      _.delay(this.measure, this.opt.sleep);
     }
 
   }