1 files changed, 171 insertions, 0 deletions
diff --git a/devtools/shared/worker/worker.js b/devtools/shared/worker/worker.js
new file mode 100644
index 000000000..9ed9afa27
--- /dev/null
+++ b/devtools/shared/worker/worker.js
@@ -0,0 +1,171 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+/* global ChromeWorker */
+
+(function (factory) {
+  if (this.module && module.id.indexOf("worker") >= 0) {
+    // require
+    const { Cc, Ci, Cu, ChromeWorker } = require("chrome");
+    const dumpn = require("devtools/shared/DevToolsUtils").dumpn;
+    factory.call(this, require, exports, module, { Cc, Ci, Cu }, ChromeWorker, dumpn);
+  } else {
+    // Cu.import
+    const { classes: Cc, interfaces: Ci, utils: Cu } = Components;
+    const { require } = Cu.import("resource://devtools/shared/Loader.jsm", {});
+    this.isWorker = false;
+    this.Promise = Cu.import("resource://gre/modules/Promise.jsm", {}).Promise;
+    this.console = Cu.import("resource://gre/modules/Console.jsm", {}).console;
+    factory.call(
+      this, require, this, { exports: this },
+      { Cc, Ci, Cu }, ChromeWorker, null
+    );
+    this.EXPORTED_SYMBOLS = ["DevToolsWorker"];
+  }
+}).call(this, function (require, exports, module, { Ci, Cc }, ChromeWorker, dumpn) {
+  let MESSAGE_COUNTER = 0;
+
+  /**
+   * Creates a wrapper around a ChromeWorker, providing easy
+   * communication to offload demanding tasks. The corresponding URL
+   * must implement the interface provided by `devtools/shared/worker/helper`.
+   *
+   * @see `./devtools/client/shared/widgets/GraphsWorker.js`
+   *
+   * @param {string} url
+   *        The URL of the worker.
+   * @param Object opts
+   *        An option with the following optional fields:
+   *        - name: a name that will be printed with logs
+   *        - verbose: log incoming and outgoing messages
+   */
+  function DevToolsWorker(url, opts) {
+    opts = opts || {};
+    this._worker = new ChromeWorker(url);
+    this._verbose = opts.verbose;
+    this._name = opts.name;
+
+    this._worker.addEventListener("error", this.onError, false);
+  }
+  exports.DevToolsWorker = DevToolsWorker;
+
+  /**
+   * Performs the given task in a chrome worker, passing in data.
+   * Returns a promise that resolves when the task is completed, resulting in
+   * the return value of the task.
+   *
+   * @param {string} task
+   *        The name of the task to execute in the worker.
+   * @param {any} data
+   *        Data to be passed into the task implemented by the worker.
+   * @return {Promise}
+   */
+  DevToolsWorker.prototype.performTask = function (task, data) {
+    if (this._destroyed) {
+      return Promise.reject("Cannot call performTask on a destroyed DevToolsWorker");
+    }
+    let worker = this._worker;
+    let id = ++MESSAGE_COUNTER;
+    let payload = { task, id, data };
+
+    if (this._verbose && dumpn) {
+      dumpn("Sending message to worker" +
+            (this._name ? (" (" + this._name + ")") : "") +
+            ": " +
+            JSON.stringify(payload, null, 2));
+    }
+    worker.postMessage(payload);
+
+    return new Promise((resolve, reject) => {
+      let listener = ({ data: result }) => {
+        if (this._verbose && dumpn) {
+          dumpn("Received message from worker" +
+                (this._name ? (" (" + this._name + ")") : "") +
+                ": " +
+                JSON.stringify(result, null, 2));
+        }
+
+        if (result.id !== id) {
+          return;
+        }
+        worker.removeEventListener("message", listener);
+        if (result.error) {
+          reject(result.error);
+        } else {
+          resolve(result.response);
+        }
+      };
+
+      worker.addEventListener("message", listener);
+    });
+  };
+
+  /**
+   * Terminates the underlying worker. Use when no longer needing the worker.
+   */
+  DevToolsWorker.prototype.destroy = function () {
+    this._worker.terminate();
+    this._worker = null;
+    this._destroyed = true;
+  };
+
+  DevToolsWorker.prototype.onError = function ({ message, filename, lineno }) {
+    dump(new Error(message + " @ " + filename + ":" + lineno) + "\n");
+  };
+
+  /**
+   * Takes a function and returns a Worker-wrapped version of the same function.
+   * Returns a promise upon resolution.
+   * @see `./devtools/shared/shared/tests/browser/browser_devtools-worker-03.js
+   *
+   * ⚠ This should only be used for tests or A/B testing performance ⚠
+   *
+   * The original function must:
+   *
+   * Be a pure function, that is, not use any variables not declared within the
+   * function, or its arguments.
+   *
+   * Return a value or a promise.
+   *
+   * Note any state change in the worker will not affect the callee's context.
+   *
+   * @param {function} fn
+   * @return {function}
+   */
+  function workerify(fn) {
+    console.warn("`workerify` should only be used in tests or measuring performance. " +
+                 "This creates an object URL on the browser window, and should not be " +
+                 "used in production.");
+    // Fetch via window/utils here as we don't want to include
+    // this module normally.
+    let { getMostRecentBrowserWindow } = require("sdk/window/utils");
+    let { URL, Blob } = getMostRecentBrowserWindow();
+    let stringifiedFn = createWorkerString(fn);
+    let blob = new Blob([stringifiedFn]);
+    let url = URL.createObjectURL(blob);
+    let worker = new DevToolsWorker(url);
+
+    let wrapperFn = data => worker.performTask("workerifiedTask", data);
+
+    wrapperFn.destroy = function () {
+      URL.revokeObjectURL(url);
+      worker.destroy();
+    };
+
+    return wrapperFn;
+  }
+  exports.workerify = workerify;
+
+  /**
+   * Takes a function, and stringifies it, attaching the worker-helper.js
+   * boilerplate hooks.
+   */
+  function createWorkerString(fn) {
+    return `importScripts("resource://gre/modules/workers/require.js");
+            const { createTask } = require("resource://devtools/shared/worker/helper.js");
+            createTask(self, "workerifiedTask", ${fn.toString()});`;
+  }
+});