chrome/test/data/third_party/spaceport/js/util/benchAsync.js

   1 define([ 'util/ensureCallback' ], function (ensureCallback) {
   2     var requestAnimationFrame
   3          = window.requestAnimationFrame
   4         || window.webkitRequestAnimationFrame
   5         || window.mozRequestAnimationFrame
   6         || window.oRequestAnimationFrame
   7         || window.msRequestAnimationFrame;
   8
   9     // Benchmarks fn until maxTime ms has passed.  Returns an object:
  10     //
  11     // {
  12     //   "score" -- approximate number of operations performed in that time ('score')
  13     // }
  14     function benchAsync(maxTime, fn, callback) {
  15         if (typeof fn !== 'function') {
  16             throw new TypeError('Argument must be a function');
  17         }
  18
  19         var startTime;
  20         var running = true;
  21
  22         function checkDone(endTime) {
  23             if (!running) {
  24                 return;
  25             }
  26
  27             if (endTime - startTime >= maxTime) {
  28                 running = false;
  29
  30                 var elapsed = endTime - startTime;
  31                 var timeoutScore = timeoutTimes.length / elapsed * maxTime;
  32                 var rafScore = rafTimes.length / elapsed * maxTime;
  33                 return callback(null, {
  34                     startTime: startTime,
  35                     timeoutScore: timeoutScore,
  36                     rafScore: rafScore,
  37                     score: requestAnimationFrame ? rafScore : timeoutScore,
  38                     elapsed: elapsed
  39                 });
  40             }
  41         }
  42
  43         function rafUpdate() {
  44             var now = Date.now();
  45             rafTimes.push(now);
  46             checkDone(now);
  47             if (running) {
  48                 requestAnimationFrame(rafUpdate);
  49             }
  50         }
  51
  52         var timeoutTimes = [ ];
  53         var rafTimes = [ ];
  54
  55         function next() {
  56             fn(timeoutTimes.length, function () {
  57                 var now = Date.now();
  58                 timeoutTimes.push(now);
  59                 checkDone(now);
  60                 if (running) {
  61                     next();
  62                 }
  63             });
  64         }
  65
  66         setTimeout(function () {
  67             startTime = Date.now();
  68
  69             if (requestAnimationFrame) {
  70                 requestAnimationFrame(rafUpdate);
  71             }
  72
  73             next();
  74         }, 0);
  75     }
  76
  77     return benchAsync;
  78 });