Source: lib/debug/timer.js

  1. /**
  2.  * @license
  3.  * Copyright 2016 Google Inc.
  4.  *
  5.  * Licensed under the Apache License, Version 2.0 (the "License");
  6.  * you may not use this file except in compliance with the License.
  7.  * You may obtain a copy of the License at
  8.  *
  9.  *     http://www.apache.org/licenses/LICENSE-2.0
  10.  *
  11.  * Unless required by applicable law or agreed to in writing, software
  12.  * distributed under the License is distributed on an "AS IS" BASIS,
  13.  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14.  * See the License for the specific language governing permissions and
  15.  * limitations under the License.
  16.  */
  18. goog.provide('shaka.timer');
  20. goog.require('shaka.log');
  23. /**
  24.  * @namespace shaka.timer
  25.  * @summary A performance timing framework.
  26.  *   Used in both debugging and production builds.
  27.  */
  30. /**
  31.  * Begins a timer.
  32.  *
  33.  * @param {string} name
  34.  */
  35. shaka.timer.begin = function(name) {
  36.   shaka.timer.timers_[name] = {
  37.     begin: shaka.timer.now_(),
  38.     end: NaN
  39.   };
  40. };
  43. /**
  44.  * End a timer and log (debug) the elapsed time.
  45.  * Does nothing if the timer has not begun.
  46.  *
  47.  * @param {string} name
  48.  */
  49. shaka.timer.end = function(name) {
  50.   var record = shaka.timer.timers_[name];
  51.   if (!record) {
  52.     return;
  53.   }
  55.   record.end = shaka.timer.now_();
  56.   var diff = record.end - record.begin;
  57.   shaka.log.debug(name + ': ' + diff.toFixed(3) + 'ms');
  58. };
  61. /**
  62.  * Log (debug) the diff between two or more completed timers and return it.
  63.  * Does nothing if not all of the timers have begun.
  64.  *
  65.  * @param {string} name1
  66.  * @param {string} name2
  67.  * @param {...string} var_args
  68.  * @return {number} The diff between the timers, or NaN if they have not all
  69.  *   completed.
  70.  */
  71. shaka.timer.diff = function(name1, name2, var_args) {
  72.   var t1 = shaka.timer.get(name1);
  73.   var t2 = shaka.timer.get(name2);
  74.   if (!t1 || !t2) {
  75.     return NaN;
  76.   }
  77.   var diff = t1 - t2;
  78.   var name = name1 + ' - ' + name2;
  80.   for (var i = 2; i < arguments.length; ++i) {
  81.     var name3 = arguments[i];
  82.     var t3 = shaka.timer.get(name3);
  83.     if (!t3) {
  84.       return NaN;
  85.     }
  86.     diff -= t3;
  87.     name += ' - ' + name3;
  88.   }
  90.   shaka.log.debug(name + ': ' + diff.toFixed(3) + 'ms');
  91.   return diff;
  92. };
  95. /**
  96.  * Query a timer.
  97.  *
  98.  * @param {string} name
  99.  * @return {number} The elapsed time in milliseconds, if the timer is complete.
  100.  *   Returns NaN if the timer doesn't exist or hasn't ended yet.
  101.  */
  102. shaka.timer.get = function(name) {
  103.   var record = shaka.timer.timers_[name];
  104.   if (!record || !record.end) {
  105.     return NaN;
  106.   }
  108.   return record.end - record.begin;
  109. };
  112. /** @private {function():number} */
  113. shaka.timer.now_ = window.performance && window.performance.now ?
  114.                        window.performance.now.bind(window.performance) :
  115.                        Date.now;
  118. /** @private {!Object.<string, {begin: number, end: number}>} */
  119. shaka.timer.timers_ = {};