src/third_party/WebKit/Source/devtools/front_end/common/Throttler.js

   1 // Copyright 2014 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 /**
   6  * @constructor
   7  * @param {number} timeout
   8  */
   9 WebInspector.Throttler = function(timeout)
  10 {
  11     this._timeout = timeout;
  12     this._isRunningProcess = false;
  13     this._asSoonAsPossible = false;
  14     /** @type {?function(!WebInspector.Throttler.FinishCallback)} */
  15     this._process = null;
  16 }
  17
  18 WebInspector.Throttler.prototype = {
  19     _processCompleted: function()
  20     {
  21         this._isRunningProcess = false;
  22         if (this._process)
  23             this._innerSchedule(false);
  24         this._processCompletedForTests();
  25     },
  26
  27     _processCompletedForTests: function()
  28     {
  29         // For sniffing in tests.
  30     },
  31
  32     _onTimeout: function()
  33     {
  34         delete this._processTimeout;
  35         this._asSoonAsPossible = false;
  36         this._isRunningProcess = true;
  37
  38         // Process might issue synchronous calls to this throttler.
  39         var process = this._process;
  40         this._process = null;
  41         process(this._processCompleted.bind(this));
  42     },
  43
  44     /**
  45      * @param {function(!WebInspector.Throttler.FinishCallback)} process
  46      * @param {boolean=} asSoonAsPossible
  47      */
  48     schedule: function(process, asSoonAsPossible)
  49     {
  50         // Deliberately skip previous process.
  51         this._process = process;
  52
  53         // Run the first scheduled task instantly.
  54         var hasScheduledTasks = !!this._processTimeout || this._isRunningProcess;
  55         asSoonAsPossible = !!asSoonAsPossible || !hasScheduledTasks;
  56
  57         var forceTimerUpdate = asSoonAsPossible && !this._asSoonAsPossible;
  58         this._asSoonAsPossible = this._asSoonAsPossible || asSoonAsPossible;
  59
  60         this._innerSchedule(forceTimerUpdate);
  61     },
  62
  63     /**
  64      * @param {boolean} forceTimerUpdate
  65      */
  66     _innerSchedule: function(forceTimerUpdate)
  67     {
  68         if (this._isRunningProcess)
  69             return;
  70         if (this._processTimeout && !forceTimerUpdate)
  71             return;
  72         if (this._processTimeout)
  73             this._clearTimeout(this._processTimeout);
  74
  75         var timeout = this._asSoonAsPossible ? 0 : this._timeout;
  76         this._processTimeout = this._setTimeout(this._onTimeout.bind(this), timeout);
  77     },
  78
  79     /**
  80      *  @param {number} timeoutId
  81      */
  82     _clearTimeout: function(timeoutId)
  83     {
  84         clearTimeout(timeoutId);
  85     },
  86
  87     /**
  88      * @param {function()} operation
  89      * @param {number} timeout
  90      * @return {number}
  91      */
  92     _setTimeout: function(operation, timeout)
  93     {
  94         return setTimeout(operation, timeout);
  95     }
  96 }
  97
  98 /** @typedef {function()} */
  99 WebInspector.Throttler.FinishCallback;