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// Copyright 2007 The Closure Library Authors. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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//      http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS-IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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/**
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 * @fileoverview Definition of goog.net.NetworkTester.
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 */
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goog.provide('goog.net.NetworkTester');
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goog.require('goog.Timer');
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goog.require('goog.Uri');
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goog.require('goog.log');
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/**
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 * Creates an instance of goog.net.NetworkTester which can be used to test
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 * for internet connectivity by seeing if an image can be loaded from
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 * google.com. It can also be tested with other URLs.
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 * @param {Function} callback Callback that is called when the test completes.
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 *     The callback takes a single boolean parameter. True indicates the URL
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 *     was reachable, false indicates it wasn't.
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 * @param {Object=} opt_handler Handler object for the callback.
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 * @param {goog.Uri=} opt_uri URI to use for testing.
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 * @constructor @struct
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 * @final
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 */
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goog.net.NetworkTester = function(callback, opt_handler, opt_uri) {
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  /**
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   * Callback that is called when the test completes.
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   * The callback takes a single boolean parameter. True indicates the URL was
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   * reachable, false indicates it wasn't.
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   * @type {Function}
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   * @private
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   */
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  this.callback_ = callback;
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  /**
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   * Handler object for the callback.
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   * @type {Object|undefined}
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   * @private
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   */
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  this.handler_ = opt_handler;
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  if (!opt_uri) {
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    // set the default URI to be based on the cleardot image at google.com
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    // We need to add a 'rand' to make sure the response is not fulfilled
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    // by browser cache. Use protocol-relative URLs to avoid insecure content
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    // warnings in IE.
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    opt_uri = new goog.Uri('//www.google.com/images/cleardot.gif');
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    opt_uri.makeUnique();
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  }
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  /**
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   * Uri to use for test. Defaults to using an image off of google.com
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   * @type {goog.Uri}
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   * @private
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   */
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  this.uri_ = opt_uri;
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};
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/**
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 * Default timeout
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 * @type {number}
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 */
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goog.net.NetworkTester.DEFAULT_TIMEOUT_MS = 10000;
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/**
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 * Logger object
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 * @type {goog.log.Logger}
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 * @private
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 */
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goog.net.NetworkTester.prototype.logger_ =
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    goog.log.getLogger('goog.net.NetworkTester');
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/**
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 * Timeout for test
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 * @type {number}
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 * @private
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 */
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goog.net.NetworkTester.prototype.timeoutMs_ =
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    goog.net.NetworkTester.DEFAULT_TIMEOUT_MS;
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/**
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 * Whether we've already started running.
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 * @type {boolean}
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 * @private
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 */
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goog.net.NetworkTester.prototype.running_ = false;
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/**
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 * Number of retries to attempt
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 * @type {number}
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 * @private
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 */
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goog.net.NetworkTester.prototype.retries_ = 0;
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/**
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 * Attempt number we're on
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 * @type {number}
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 * @private
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 */
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goog.net.NetworkTester.prototype.attempt_ = 0;
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/**
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 * Pause between retries in milliseconds.
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 * @type {number}
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 * @private
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 */
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goog.net.NetworkTester.prototype.pauseBetweenRetriesMs_ = 0;
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/**
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 * Timer for timeouts.
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 * @type {?number}
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 * @private
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 */
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goog.net.NetworkTester.prototype.timeoutTimer_ = null;
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/**
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 * Timer for pauses between retries.
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 * @type {?number}
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 * @private
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 */
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goog.net.NetworkTester.prototype.pauseTimer_ = null;
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/** @private {?Image} */
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goog.net.NetworkTester.prototype.image_;
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/**
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 * Returns the timeout in milliseconds.
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 * @return {number} Timeout in milliseconds.
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 */
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goog.net.NetworkTester.prototype.getTimeout = function() {
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  return this.timeoutMs_;
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};
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/**
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 * Sets the timeout in milliseconds.
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 * @param {number} timeoutMs Timeout in milliseconds.
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 */
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goog.net.NetworkTester.prototype.setTimeout = function(timeoutMs) {
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  this.timeoutMs_ = timeoutMs;
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};
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/**
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 * Returns the numer of retries to attempt.
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 * @return {number} Number of retries to attempt.
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 */
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goog.net.NetworkTester.prototype.getNumRetries = function() {
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  return this.retries_;
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};
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/**
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 * Sets the timeout in milliseconds.
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 * @param {number} retries Number of retries to attempt.
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 */
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goog.net.NetworkTester.prototype.setNumRetries = function(retries) {
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  this.retries_ = retries;
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};
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/**
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 * Returns the pause between retries in milliseconds.
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 * @return {number} Pause between retries in milliseconds.
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 */
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goog.net.NetworkTester.prototype.getPauseBetweenRetries = function() {
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  return this.pauseBetweenRetriesMs_;
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};
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/**
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 * Sets the pause between retries in milliseconds.
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 * @param {number} pauseMs Pause between retries in milliseconds.
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 */
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goog.net.NetworkTester.prototype.setPauseBetweenRetries = function(pauseMs) {
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  this.pauseBetweenRetriesMs_ = pauseMs;
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};
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/**
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 * Returns the uri to use for the test.
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 * @return {goog.Uri} The uri for the test.
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 */
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goog.net.NetworkTester.prototype.getUri = function() {
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  return this.uri_;
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};
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/**
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 * Returns the current attempt count.
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 * @return {number} The attempt count.
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 */
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goog.net.NetworkTester.prototype.getAttemptCount = function() {
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  return this.attempt_;
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};
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/**
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 * Sets the uri to use for the test.
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 * @param {goog.Uri} uri The uri for the test.
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 */
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goog.net.NetworkTester.prototype.setUri = function(uri) {
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  this.uri_ = uri;
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};
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/**
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 * Returns whether the tester is currently running.
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 * @return {boolean} True if it's running, false if it's not running.
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 */
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goog.net.NetworkTester.prototype.isRunning = function() {
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  return this.running_;
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};
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/**
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 * Starts the process of testing the network.
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 */
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goog.net.NetworkTester.prototype.start = function() {
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  if (this.running_) {
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    throw Error('NetworkTester.start called when already running');
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  }
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  this.running_ = true;
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  goog.log.info(this.logger_, 'Starting');
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  this.attempt_ = 0;
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  this.startNextAttempt_();
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};
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/**
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 * Stops the testing of the network. This is a noop if not running.
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 */
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goog.net.NetworkTester.prototype.stop = function() {
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  this.cleanupCallbacks_();
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  this.running_ = false;
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};
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/**
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 * Starts the next attempt to load an image.
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 * @private
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 */
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goog.net.NetworkTester.prototype.startNextAttempt_ = function() {
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  this.attempt_++;
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  if (goog.net.NetworkTester.getNavigatorOffline_()) {
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    goog.log.info(this.logger_, 'Browser is set to work offline.');
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    // Call in a timeout to make async like the rest.
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    goog.Timer.callOnce(goog.bind(this.onResult, this, false), 0);
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  } else {
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    goog.log.info(
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        this.logger_,
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        'Loading image (attempt ' + this.attempt_ + ') at ' + this.uri_);
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    this.image_ = new Image();
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    this.image_.onload = goog.bind(this.onImageLoad_, this);
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    this.image_.onerror = goog.bind(this.onImageError_, this);
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    this.image_.onabort = goog.bind(this.onImageAbort_, this);
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    this.timeoutTimer_ =
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        goog.Timer.callOnce(this.onImageTimeout_, this.timeoutMs_, this);
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    this.image_.src = String(this.uri_);
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  }
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};
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/**
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 * @return {boolean} Whether navigator.onLine returns false.
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 * @private
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 */
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goog.net.NetworkTester.getNavigatorOffline_ = function() {
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  return navigator !== null && 'onLine' in navigator && !navigator.onLine;
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};
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/**
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 * Callback for the image successfully loading.
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 * @private
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 */
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goog.net.NetworkTester.prototype.onImageLoad_ = function() {
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  goog.log.info(this.logger_, 'Image loaded');
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  this.onResult(true);
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};
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/**
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 * Callback for the image failing to load.
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 * @private
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 */
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goog.net.NetworkTester.prototype.onImageError_ = function() {
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  goog.log.info(this.logger_, 'Image load error');
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  this.onResult(false);
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};
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/**
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 * Callback for the image load being aborted.
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 * @private
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 */
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goog.net.NetworkTester.prototype.onImageAbort_ = function() {
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  goog.log.info(this.logger_, 'Image load aborted');
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  this.onResult(false);
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};
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/**
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 * Callback for the image load timing out.
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 * @private
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 */
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goog.net.NetworkTester.prototype.onImageTimeout_ = function() {
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  goog.log.info(this.logger_, 'Image load timed out');
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  this.onResult(false);
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};
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/**
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 * Handles a successful or failed result.
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 * @param {boolean} succeeded Whether the image load succeeded.
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 */
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goog.net.NetworkTester.prototype.onResult = function(succeeded) {
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  this.cleanupCallbacks_();
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  if (succeeded) {
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    this.running_ = false;
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    this.callback_.call(this.handler_, true);
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  } else {
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    if (this.attempt_ <= this.retries_) {
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      if (this.pauseBetweenRetriesMs_) {
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        this.pauseTimer_ = goog.Timer.callOnce(
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            this.onPauseFinished_, this.pauseBetweenRetriesMs_, this);
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      } else {
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        this.startNextAttempt_();
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      }
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    } else {
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      this.running_ = false;
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      this.callback_.call(this.handler_, false);
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    }
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  }
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};
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/**
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 * Callback for the pause between retry timer.
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 * @private
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 */
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goog.net.NetworkTester.prototype.onPauseFinished_ = function() {
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  this.pauseTimer_ = null;
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  this.startNextAttempt_();
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};
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/**
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 * Cleans up the handlers and timer associated with the image.
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 * @private
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 */
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goog.net.NetworkTester.prototype.cleanupCallbacks_ = function() {
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  // clear handlers to avoid memory leaks
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  // NOTE(user): Nullified individually to avoid compiler warnings
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  // (BUG 658126)
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  if (this.image_) {
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    this.image_.onload = null;
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    this.image_.onerror = null;
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    this.image_.onabort = null;
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    this.image_ = null;
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  }
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  if (this.timeoutTimer_) {
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    goog.Timer.clear(this.timeoutTimer_);
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    this.timeoutTimer_ = null;
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  }
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  if (this.pauseTimer_) {
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    goog.Timer.clear(this.pauseTimer_);
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    this.pauseTimer_ = null;
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  }
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};
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