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Diffstat (limited to 'browser/patch-worker.js')
| -rw-r--r-- | browser/patch-worker.js | 135 |
1 files changed, 135 insertions, 0 deletions
diff --git a/browser/patch-worker.js b/browser/patch-worker.js new file mode 100644 index 0000000..428ea6c --- /dev/null +++ b/browser/patch-worker.js @@ -0,0 +1,135 @@ +/* +Copyright 2013 Rob Wu <gwnRob@gmail.com> +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. +*/ +// Target: Chrome 20+ + +// W3-compliant Worker proxy. +// This module replaces the global Worker object. +// When invoked, the default Worker object is called. +// If this call fails with SECURITY_ERR, the script is fetched +// using async XHR, and transparently proxies all calls and +// setters/getters to the new Worker object. +// Note: This script does not magically circumvent the Same origin policy. + +(function () { + 'use strict'; + var Worker_ = window.Worker; + var URL = window.URL || window.webkitURL; + // Create dummy worker for the following purposes: + // 1. Don't override the global Worker object if the fallback isn't + // going to work (future API changes?) + // 2. Use it to trigger early validation of postMessage calls + // Note: Blob constructor is supported since Chrome 20, but since + // some of the used Chrome APIs are only supported as of Chrome 20, + // I don't bother adding a BlobBuilder fallback. + var dummyWorker = new Worker_( + URL.createObjectURL(new Blob([], { type: 'text/javascript' }))); + window.Worker = function Worker(scriptURL) { + if (arguments.length === 0) { + throw new TypeError('Not enough arguments'); + } + try { + return new Worker_(scriptURL); + } catch (e) { + if (e.code === 18/*DOMException.SECURITY_ERR*/) { + return new WorkerXHR(scriptURL); + } else { + throw e; + } + } + }; + // Bind events and replay queued messages + function bindWorker(worker, workerURL) { + if (worker._terminated) { + return; + } + worker.Worker = new Worker_(workerURL); + worker.Worker.onerror = worker._onerror; + worker.Worker.onmessage = worker._onmessage; + var o; + while ((o = worker._replayQueue.shift())) { + worker.Worker[o.method].apply(worker.Worker, o.arguments); + } + while ((o = worker._messageQueue.shift())) { + worker.Worker.postMessage.apply(worker.Worker, o); + } + } + function WorkerXHR(scriptURL) { + var worker = this; + var x = new XMLHttpRequest(); + x.responseType = 'blob'; + x.onload = function () { + // http://stackoverflow.com/a/10372280/938089 + var workerURL = URL.createObjectURL(x.response); + bindWorker(worker, workerURL); + }; + x.open('GET', scriptURL); + x.send(); + worker._replayQueue = []; + worker._messageQueue = []; + } + WorkerXHR.prototype = { + constructor: Worker_, + terminate: function () { + if (!this._terminated) { + this._terminated = true; + if (this.Worker) + this.Worker.terminate(); + } + }, + postMessage: function (message, transfer) { + if (!(this instanceof WorkerXHR)) + throw new TypeError('Illegal invocation'); + if (this.Worker) { + this.Worker.postMessage.apply(this.Worker, arguments); + } else { + // Trigger validation: + dummyWorker.postMessage(message); + // Alright, push the valid message to the queue. + this._messageQueue.push(arguments); + } + } + }; + // Implement the EventTarget interface + [ + 'addEventListener', + 'removeEventListener', + 'dispatchEvent' + ].forEach(function (method) { + WorkerXHR.prototype[method] = function () { + if (!(this instanceof WorkerXHR)) { + throw new TypeError('Illegal invocation'); + } + if (this.Worker) { + this.Worker[method].apply(this.Worker, arguments); + } else { + this._replayQueue.push({ method: method, arguments: arguments }); + } + }; + }); + Object.defineProperties(WorkerXHR.prototype, { + onmessage: { + get: function () { return this._onmessage || null; }, + set: function (func) { + this._onmessage = typeof func === 'function' ? func : null; + } + }, + onerror: { + get: function () { return this._onerror || null; }, + set: function (func) { + this._onerror = typeof func === 'function' ? func : null; + } + } + }); +})();
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