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// Copyright 2006 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 tmpnetwork.js contains some temporary networking functions
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 * for browserchannel which will be moved at a later date.
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 */
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/**
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 * Namespace for BrowserChannel
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 */
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goog.provide('goog.net.tmpnetwork');
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goog.require('goog.Uri');
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goog.require('goog.net.ChannelDebug');
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/**
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 * Default timeout to allow for google.com pings.
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 * @type {number}
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 */
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goog.net.tmpnetwork.GOOGLECOM_TIMEOUT = 10000;
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/**
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 * @define {string} url to use to test for internet connectivity.
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 * Use protocol-relative URLs to avoid insecure content warnings in IE.
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 */
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goog.define(
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    'goog.net.tmpnetwork.TEST_URL', '//www.google.com/images/cleardot.gif');
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/**
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 * Pings the network to check if an error is a server error or user's network
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 * error.
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 *
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 * @param {Function} callback The function to call back with results.
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 * @param {goog.Uri?=} opt_imageUri The URI of an image to use for the network
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 *     test. You *must* provide an image URI; the default behavior is provided
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 *     for compatibility with existing code, but the search team does not want
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 *     people using images served off of google.com for this purpose. The
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 *     default will go away when all usages have been changed.
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 */
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goog.net.tmpnetwork.testGoogleCom = function(callback, opt_imageUri) {
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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.
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  var uri = opt_imageUri;
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  if (!uri) {
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    uri = new goog.Uri(goog.net.tmpnetwork.TEST_URL);
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    uri.makeUnique();
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  }
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  goog.net.tmpnetwork.testLoadImage(
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      uri.toString(), goog.net.tmpnetwork.GOOGLECOM_TIMEOUT, callback);
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};
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/**
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 * Test loading the given image, retrying if necessary.
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 * @param {string} url URL to the iamge.
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 * @param {number} timeout Milliseconds before giving up.
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 * @param {Function} callback Function to call with results.
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 * @param {number} retries The number of times to retry.
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 * @param {number=} opt_pauseBetweenRetriesMS Optional number of milliseconds
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 *     between retries - defaults to 0.
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 */
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goog.net.tmpnetwork.testLoadImageWithRetries = function(
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    url, timeout, callback, retries, opt_pauseBetweenRetriesMS) {
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  var channelDebug = new goog.net.ChannelDebug();
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  channelDebug.debug('TestLoadImageWithRetries: ' + opt_pauseBetweenRetriesMS);
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  if (retries == 0) {
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    // no more retries, give up
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    callback(false);
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    return;
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  }
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  var pauseBetweenRetries = opt_pauseBetweenRetriesMS || 0;
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  retries--;
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  goog.net.tmpnetwork.testLoadImage(url, timeout, function(succeeded) {
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    if (succeeded) {
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      callback(true);
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    } else {
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      // try again
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      goog.global.setTimeout(function() {
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        goog.net.tmpnetwork.testLoadImageWithRetries(
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            url, timeout, callback, retries, pauseBetweenRetries);
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      }, pauseBetweenRetries);
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    }
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  });
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};
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/**
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 * Test loading the given image.
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 * @param {string} url URL to the iamge.
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 * @param {number} timeout Milliseconds before giving up.
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 * @param {Function} callback Function to call with results.
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 */
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goog.net.tmpnetwork.testLoadImage = function(url, timeout, callback) {
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  var channelDebug = new goog.net.ChannelDebug();
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  channelDebug.debug('TestLoadImage: loading ' + url);
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  var img = new Image();
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  img.onload = function() {
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    try {
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      channelDebug.debug('TestLoadImage: loaded');
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      goog.net.tmpnetwork.clearImageCallbacks_(img);
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      callback(true);
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    } catch (e) {
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      channelDebug.dumpException(e);
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    }
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  };
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  img.onerror = function() {
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    try {
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      channelDebug.debug('TestLoadImage: error');
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      goog.net.tmpnetwork.clearImageCallbacks_(img);
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      callback(false);
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    } catch (e) {
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      channelDebug.dumpException(e);
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    }
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  };
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  img.onabort = function() {
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    try {
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      channelDebug.debug('TestLoadImage: abort');
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      goog.net.tmpnetwork.clearImageCallbacks_(img);
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      callback(false);
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    } catch (e) {
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      channelDebug.dumpException(e);
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    }
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  };
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  img.ontimeout = function() {
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    try {
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      channelDebug.debug('TestLoadImage: timeout');
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      goog.net.tmpnetwork.clearImageCallbacks_(img);
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      callback(false);
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    } catch (e) {
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      channelDebug.dumpException(e);
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    }
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  };
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  goog.global.setTimeout(function() {
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    if (img.ontimeout) {
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      img.ontimeout();
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    }
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  }, timeout);
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  img.src = url;
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};
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/**
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 * Clear handlers to avoid memory leaks.
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 * @param {Image} img The image to clear handlers from.
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 * @private
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 */
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goog.net.tmpnetwork.clearImageCallbacks_ = function(img) {
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  // NOTE(user): Nullified individually to avoid compiler warnings
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  // (BUG 658126)
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  img.onload = null;
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  img.onerror = null;
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  img.onabort = null;
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  img.ontimeout = null;
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};
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