remoting/webapp/base/js/suspend_detector.js

   1 // Copyright 2015 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 /** @suppress {duplicate} */
   6 var remoting = remoting || {};
   7
   8 (function () {
   9
  10 'use strict';
  11
  12 var INTERVAL_IN_MS = 500;
  13
  14 var TIMER_INACCURACY_IN_MS = 10;
  15
  16 /**
  17  * @constructor
  18  * @param {number=} opt_maxSuspendInMs  The maximum permitted suspend duration
  19  *     to raise the resume event.
  20  * @extends {base.EventSourceImpl}
  21  * @implements {base.Disposable}
  22  */
  23 remoting.SuspendDetector = function(opt_maxSuspendInMs) {
  24   base.inherits(this, base.EventSourceImpl);
  25   this.defineEvents(base.values(remoting.SuspendDetector.Events));
  26
  27   if (opt_maxSuspendInMs == undefined ||
  28       !Number.isInteger(opt_maxSuspendInMs)) {
  29     opt_maxSuspendInMs = TIMER_INACCURACY_IN_MS;
  30   }
  31
  32   /** @private */
  33   this.maxSuspendInMs_ = Math.max(opt_maxSuspendInMs, TIMER_INACCURACY_IN_MS);
  34
  35   /**
  36    * JavaScript timer is paused while the computer is suspended, we need to use
  37    * a higher resolution timer instead of |this.maxSuspendInMs_| to ensure the
  38    * resume event fires promptly after the system wakes up from sleep.
  39    * @private
  40    */
  41   this.timer_ =
  42       new base.RepeatingTimer(this.onTick_.bind(this), INTERVAL_IN_MS);
  43
  44   /** @private */
  45   this.lastTick_ = new Date();
  46 };
  47
  48 remoting.SuspendDetector.prototype.dispose = function() {
  49   base.dispose(this.timer_);
  50   this.timer = null;
  51 };
  52
  53 /** @private */
  54 remoting.SuspendDetector.prototype.onTick_ = function() {
  55   var now = new Date();
  56   // If the computer has just resumed from sleep, the sleep duration will
  57   // roughly equal the |delta| between the ticks.
  58   var delta = now - this.lastTick_;
  59   this.lastTick_ = now;
  60   if (delta > this.maxSuspendInMs_) {
  61     this.raiseEvent(remoting.SuspendDetector.Events.resume, delta);
  62   }
  63 };
  64
  65 })();
  66
  67 /** @enum {string} */
  68 remoting.SuspendDetector.Events = {
  69   // Fired when the computer resumes up from sleep with the approximate sleep
  70   // duration in milliseconds.  The sleep duration is only an approximation with
  71   // and an uncertainty of |INTERVAL_IN_MS|.
  72   //  {number} sleepDuration
  73   resume: 'resume'
  74 };