| // Copyright 2013 The Closure Library Authors. All Rights Reserved. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS-IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| /** |
| * @fileoverview Utility functions for managing networking, such as |
| * testing network connectivity. |
| * |
| * @visibility {:internal} |
| */ |
| |
| |
| goog.provide('goog.labs.net.webChannel.netUtils'); |
| |
| goog.require('goog.Uri'); |
| goog.require('goog.labs.net.webChannel.WebChannelDebug'); |
| |
| goog.scope(function() { |
| var netUtils = goog.labs.net.webChannel.netUtils; |
| var WebChannelDebug = goog.labs.net.webChannel.WebChannelDebug; |
| |
| |
| /** |
| * Default timeout to allow for URI pings. |
| * @type {number} |
| */ |
| netUtils.NETWORK_TIMEOUT = 10000; |
| |
| |
| /** |
| * Pings the network with an image URI to check if an error is a server error |
| * or user's network error. |
| * |
| * The caller needs to add a 'rand' parameter to make sure the response is |
| * not fulfilled by browser cache. |
| * |
| * @param {function(boolean)} callback The function to call back with results. |
| * @param {goog.Uri=} opt_imageUri The URI (of an image) to use for the network |
| * test. |
| */ |
| netUtils.testNetwork = function(callback, opt_imageUri) { |
| var uri = opt_imageUri; |
| if (!uri) { |
| // default google.com image |
| uri = new goog.Uri('//www.google.com/images/cleardot.gif'); |
| |
| if (!(goog.global.location && goog.global.location.protocol == 'http')) { |
| uri.setScheme('https'); // e.g. chrome-extension |
| } |
| uri.makeUnique(); |
| } |
| |
| netUtils.testLoadImage(uri.toString(), netUtils.NETWORK_TIMEOUT, callback); |
| }; |
| |
| |
| /** |
| * Test loading the given image, retrying if necessary. |
| * @param {string} url URL to the image. |
| * @param {number} timeout Milliseconds before giving up. |
| * @param {function(boolean)} callback Function to call with results. |
| * @param {number} retries The number of times to retry. |
| * @param {number=} opt_pauseBetweenRetriesMS Optional number of milliseconds |
| * between retries - defaults to 0. |
| */ |
| netUtils.testLoadImageWithRetries = function(url, timeout, callback, |
| retries, opt_pauseBetweenRetriesMS) { |
| var channelDebug = new WebChannelDebug(); |
| channelDebug.debug('TestLoadImageWithRetries: ' + opt_pauseBetweenRetriesMS); |
| if (retries == 0) { |
| // no more retries, give up |
| callback(false); |
| return; |
| } |
| |
| var pauseBetweenRetries = opt_pauseBetweenRetriesMS || 0; |
| retries--; |
| netUtils.testLoadImage(url, timeout, function(succeeded) { |
| if (succeeded) { |
| callback(true); |
| } else { |
| // try again |
| goog.global.setTimeout(function() { |
| netUtils.testLoadImageWithRetries(url, timeout, callback, |
| retries, pauseBetweenRetries); |
| }, pauseBetweenRetries); |
| } |
| }); |
| }; |
| |
| |
| /** |
| * Test loading the given image. |
| * @param {string} url URL to the image. |
| * @param {number} timeout Milliseconds before giving up. |
| * @param {function(boolean)} callback Function to call with results. |
| */ |
| netUtils.testLoadImage = function(url, timeout, callback) { |
| var channelDebug = new WebChannelDebug(); |
| channelDebug.debug('TestLoadImage: loading ' + url); |
| var img = new Image(); |
| img.onload = goog.partial(netUtils.imageCallback_, channelDebug, img, |
| 'TestLoadImage: loaded', true, callback); |
| img.onerror = goog.partial(netUtils.imageCallback_, channelDebug, img, |
| 'TestLoadImage: error', false, callback); |
| img.onabort = goog.partial(netUtils.imageCallback_, channelDebug, img, |
| 'TestLoadImage: abort', false, callback); |
| img.ontimeout = goog.partial(netUtils.imageCallback_, channelDebug, img, |
| 'TestLoadImage: timeout', false, callback); |
| |
| goog.global.setTimeout(function() { |
| if (img.ontimeout) { |
| img.ontimeout(); |
| } |
| }, timeout); |
| img.src = url; |
| }; |
| |
| |
| /** |
| * Wrap the image callback with debug and cleanup logic. |
| * @param {!WebChannelDebug} channelDebug The WebChannelDebug object. |
| * @param {!Image} img The image element. |
| * @param {string} debugText The debug text. |
| * @param {boolean} result The result of image loading. |
| * @param {function(boolean)} callback The image callback. |
| * @private |
| */ |
| netUtils.imageCallback_ = function(channelDebug, img, debugText, result, |
| callback) { |
| try { |
| channelDebug.debug(debugText); |
| netUtils.clearImageCallbacks_(img); |
| callback(result); |
| } catch (e) { |
| channelDebug.dumpException(e); |
| } |
| }; |
| |
| |
| /** |
| * Clears handlers to avoid memory leaks. |
| * @param {Image} img The image to clear handlers from. |
| * @private |
| */ |
| netUtils.clearImageCallbacks_ = function(img) { |
| img.onload = null; |
| img.onerror = null; |
| img.onabort = null; |
| img.ontimeout = null; |
| }; |
| }); // goog.scope |