chrome/browser/resources/cryptotoken/countdowntimer.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  * @fileoverview Provides a countdown-based timer implementation.
   7  */
   8 'use strict';
   9
  10 /**
  11  * Constructs a new timer.  The timer has a very limited resolution, and does
  12  * not attempt to be millisecond accurate. Its intended use is as a
  13  * low-precision timer that pauses while debugging.
  14  * @param {number=} timeoutMillis how long, in milliseconds, the countdown
  15  *     lasts.
  16  * @param {Function=} cb called back when the countdown expires.
  17  * @constructor
  18  * @implements {Countdown}
  19  */
  20 function CountdownTimer(timeoutMillis, cb) {
  21   this.remainingMillis = 0;
  22   this.setTimeout(timeoutMillis || 0, cb);
  23 }
  24
  25 /** Timer interval */
  26 CountdownTimer.TIMER_INTERVAL_MILLIS = 200;
  27
  28 /**
  29  * Sets a new timeout for this timer. Only possible if the timer is not
  30  * currently active.
  31  * @param {number} timeoutMillis how long, in milliseconds, the countdown lasts.
  32  * @param {Function=} cb called back when the countdown expires.
  33  * @return {boolean} whether the timeout could be set.
  34  */
  35 CountdownTimer.prototype.setTimeout = function(timeoutMillis, cb) {
  36   if (this.timeoutId)
  37     return false;
  38   if (!timeoutMillis || timeoutMillis < 0)
  39     return false;
  40   this.remainingMillis = timeoutMillis;
  41   this.cb = cb;
  42   if (this.remainingMillis > CountdownTimer.TIMER_INTERVAL_MILLIS) {
  43     this.timeoutId =
  44         window.setInterval(this.timerTick.bind(this),
  45             CountdownTimer.TIMER_INTERVAL_MILLIS);
  46   } else {
  47     // Set a one-shot timer for the last interval.
  48     this.timeoutId =
  49         window.setTimeout(this.timerTick.bind(this), this.remainingMillis);
  50   }
  51   return true;
  52 };
  53
  54 /** Clears this timer's timeout. Timers that are cleared become expired. */
  55 CountdownTimer.prototype.clearTimeout = function() {
  56   if (this.timeoutId) {
  57     window.clearTimeout(this.timeoutId);
  58     this.timeoutId = undefined;
  59   }
  60   this.remainingMillis = 0;
  61 };
  62
  63 /**
  64  * @return {number} how many milliseconds are remaining until the timer expires.
  65  */
  66 CountdownTimer.prototype.millisecondsUntilExpired = function() {
  67   return this.remainingMillis > 0 ? this.remainingMillis : 0;
  68 };
  69
  70 /** @return {boolean} whether the timer has expired. */
  71 CountdownTimer.prototype.expired = function() {
  72   return this.remainingMillis <= 0;
  73 };
  74
  75 /**
  76  * Constructs a new clone of this timer, while overriding its callback.
  77  * @param {Function=} cb callback for new timer.
  78  * @return {!Countdown} new clone.
  79  */
  80 CountdownTimer.prototype.clone = function(cb) {
  81   return new CountdownTimer(this.remainingMillis, cb);
  82 };
  83
  84 /** Timer callback. */
  85 CountdownTimer.prototype.timerTick = function() {
  86   this.remainingMillis -= CountdownTimer.TIMER_INTERVAL_MILLIS;
  87   if (this.expired()) {
  88     window.clearTimeout(this.timeoutId);
  89     this.timeoutId = undefined;
  90     if (this.cb) {
  91       this.cb();
  92     }
  93   }
  94 };
  95
  96 /**
  97  * A factory for creating CountdownTimers.
  98  * @constructor
  99  * @implements {CountdownFactory}
 100  */
 101 function CountdownTimerFactory() {
 102 }
 103
 104 /**
 105  * Creates a new timer.
 106  * @param {number} timeoutMillis How long, in milliseconds, the countdown lasts.
 107  * @param {function()=} opt_cb Called back when the countdown expires.
 108  * @return {!Countdown} The timer.
 109  */
 110 CountdownTimerFactory.prototype.createTimer =
 111     function(timeoutMillis, opt_cb) {
 112   return new CountdownTimer(timeoutMillis, opt_cb);
 113 };
 114
 115 /**
 116  * Minimum timeout attenuation, below which a response couldn't be reasonably
 117  * guaranteed, in seconds.
 118  * @const
 119  */
 120 var MINIMUM_TIMEOUT_ATTENUATION_SECONDS = 0.5;
 121
 122 /**
 123  * @param {number} timeoutSeconds Timeout value in seconds.
 124  * @return {number} The timeout value, attenuated to ensure a response can be
 125  *     given before the timeout's expiration.
 126  * @private
 127  */
 128 function attenuateTimeoutInSeconds_(timeoutSeconds) {
 129   if (timeoutSeconds < MINIMUM_TIMEOUT_ATTENUATION_SECONDS)
 130     return 0;
 131   return timeoutSeconds - MINIMUM_TIMEOUT_ATTENUATION_SECONDS;
 132 }
 133
 134 /**
 135  * Default request timeout when none is present in the request, in seconds.
 136  * @const
 137  */
 138 var DEFAULT_REQUEST_TIMEOUT_SECONDS = 30;
 139
 140 /**
 141  * Creates a new countdown from the given request using the given timer factory,
 142  * attenuated to ensure a response is given prior to the countdown's expiration.
 143  * @param {CountdownFactory} timerFactory The factory to use.
 144  * @param {Object} request The request containing the timeout.
 145  * @param {number=} opt_defaultTimeoutSeconds
 146  * @return {!Countdown} A countdown timer.
 147  */
 148 function createTimerForRequest(timerFactory, request,
 149     opt_defaultTimeoutSeconds) {
 150   var timeoutValueSeconds;
 151   if (request.hasOwnProperty('timeoutSeconds')) {
 152     timeoutValueSeconds = request['timeoutSeconds'];
 153   } else if (request.hasOwnProperty('timeout')) {
 154     timeoutValueSeconds = request['timeout'];
 155   } else if (opt_defaultTimeoutSeconds !== undefined) {
 156     timeoutValueSeconds = opt_defaultTimeoutSeconds;
 157   } else {
 158     timeoutValueSeconds = DEFAULT_REQUEST_TIMEOUT_SECONDS;
 159   }
 160   timeoutValueSeconds = attenuateTimeoutInSeconds_(timeoutValueSeconds);
 161   return timerFactory.createTimer(timeoutValueSeconds * 1000);
 162 }