The Tor Browser: dom/base/DOMRequestHelper.jsm@b8a032363ba2 (annotated)

dom/base/DOMRequestHelper.jsm@b8a032363ba2 (annotated)

dom/base/DOMRequestHelper.jsm

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /* 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/. */
 /**
  * Helper object for APIs that deal with DOMRequests and Promises.
  * It allows objects inheriting from it to create and keep track of DOMRequests
  * and Promises objects in the common scenario where requests are created in
  * the child, handed out to content and delivered to the parent within an async
  * message (containing the identifiers of these requests). The parent may send
  * messages back as answers to different requests and the child will use this
  * helper to get the right request object. This helper also takes care of
  * releasing the requests objects when the window goes out of scope.
  *
  * DOMRequestIPCHelper also deals with message listeners, allowing to add them
  * to the child side of frame and process message manager and removing them
  * when needed.
  */
 const Cu = Components.utils;
 const Cc = Components.classes;
 const Ci = Components.interfaces;
 const Cr = Components.results;
 this.EXPORTED_SYMBOLS = ["DOMRequestIpcHelper"];
 Cu.import("resource://gre/modules/XPCOMUtils.jsm");
 Cu.import("resource://gre/modules/Services.jsm");
 XPCOMUtils.defineLazyServiceGetter(this, "cpmm",
                                    "@mozilla.org/childprocessmessagemanager;1",
                                    "nsIMessageListenerManager");
 this.DOMRequestIpcHelper = function DOMRequestIpcHelper() {
   // _listeners keeps a list of messages for which we added a listener and the
   // kind of listener that we added (strong or weak). It's an object of this
   // form:
   //  {
   //    "message1": true,
   //    "messagen": false
   //  }
   //
   // where each property is the name of the message and its value is a boolean
   // that indicates if the listener is weak or not.
   this._listeners = null;
   this._requests = null;
   this._window = null;
 }
 DOMRequestIpcHelper.prototype = {
   /**
    * An object which "inherits" from DOMRequestIpcHelper and declares its own
    * queryInterface method MUST implement Ci.nsISupportsWeakReference.
    */
   QueryInterface: XPCOMUtils.generateQI([Ci.nsISupportsWeakReference,
                                          Ci.nsIObserver]),
    /**
    *  'aMessages' is expected to be an array of either:
    *  - objects of this form:
    *    {
    *      name: "messageName",
    *      weakRef: false
    *    }
    *    where 'name' is the message identifier and 'weakRef' a boolean
    *    indicating if the listener should be a weak referred one or not.
    *
    *  - or only strings containing the message name, in which case the listener
    *    will be added as a strong reference by default.
    */
   addMessageListeners: function(aMessages) {
     if (!aMessages) {
       return;
     }
     if (!this._listeners) {
       this._listeners = {};
     }
     if (!Array.isArray(aMessages)) {
       aMessages = [aMessages];
     }
     aMessages.forEach((aMsg) => {
       let name = aMsg.name || aMsg;
       // If the listener is already set and it is of the same type we just
       // bail out. If it is not of the same type, we throw an exception.
       if (this._listeners[name] != undefined) {
         if (!!aMsg.weakRef == this._listeners[name]) {
           return;
         } else {
           throw Cr.NS_ERROR_FAILURE;
         }
       }
       aMsg.weakRef ? cpmm.addWeakMessageListener(name, this)
                    : cpmm.addMessageListener(name, this);
       this._listeners[name] = !!aMsg.weakRef;
     });
   },
   /**
    * 'aMessages' is expected to be a string or an array of strings containing
    * the message names of the listeners to be removed.
    */
   removeMessageListeners: function(aMessages) {
     if (!this._listeners || !aMessages) {
       return;
     }
     if (!Array.isArray(aMessages)) {
       aMessages = [aMessages];
     }
     aMessages.forEach((aName) => {
       if (this._listeners[aName] == undefined) {
         return;
       }
       this._listeners[aName] ? cpmm.removeWeakMessageListener(aName, this)
                              : cpmm.removeMessageListener(aName, this);
       delete this._listeners[aName];
     });
   },
   /**
    * Initialize the helper adding the corresponding listeners to the messages
    * provided as the second parameter.
    *
    * 'aMessages' is expected to be an array of either:
    *
    *  - objects of this form:
    *    {
    *      name: 'messageName',
    *      weakRef: false
    *    }
    *    where 'name' is the message identifier and 'weakRef' a boolean
    *    indicating if the listener should be a weak referred one or not.
    *
    *  - or only strings containing the message name, in which case the listener
    *    will be added as a strong referred one by default.
    */
   initDOMRequestHelper: function(aWindow, aMessages) {
     // Query our required interfaces to force a fast fail if they are not
     // provided. These calls will throw if the interface is not available.
     this.QueryInterface(Ci.nsISupportsWeakReference);
     this.QueryInterface(Ci.nsIObserver);
     if (aMessages) {
       this.addMessageListeners(aMessages);
     }
     this._id = this._getRandomId();
     this._window = aWindow;
     if (this._window) {
       // We don't use this.innerWindowID, but other classes rely on it.
       let util = this._window.QueryInterface(Ci.nsIInterfaceRequestor)
                              .getInterface(Ci.nsIDOMWindowUtils);
       this.innerWindowID = util.currentInnerWindowID;
     }
     this._destroyed = false;
     Services.obs.addObserver(this, "inner-window-destroyed",
                              /* weak-ref */ true);
   },
   destroyDOMRequestHelper: function() {
     if (this._destroyed) {
       return;
     }
     this._destroyed = true;
     Services.obs.removeObserver(this, "inner-window-destroyed");
     if (this._listeners) {
       Object.keys(this._listeners).forEach((aName) => {
         this._listeners[aName] ? cpmm.removeWeakMessageListener(aName, this)
                                : cpmm.removeMessageListener(aName, this);
         delete this._listeners[aName];
       });
     }
     this._listeners = null;
     this._requests = null;
     // Objects inheriting from DOMRequestIPCHelper may have an uninit function.
     if (this.uninit) {
       this.uninit();
     }
     this._window = null;
   },
   observe: function(aSubject, aTopic, aData) {
     if (aTopic !== "inner-window-destroyed") {
       return;
     }
     let wId = aSubject.QueryInterface(Ci.nsISupportsPRUint64).data;
     if (wId != this.innerWindowID) {
       return;
     }
     this.destroyDOMRequestHelper();
   },
   getRequestId: function(aRequest) {
     if (!this._requests) {
       this._requests = {};
     }
     let id = "id" + this._getRandomId();
     this._requests[id] = aRequest;
     return id;
   },
   getPromiseResolverId: function(aPromiseResolver) {
     // Delegates to getRequest() since the lookup table is agnostic about
     // storage.
     return this.getRequestId(aPromiseResolver);
   },
   getRequest: function(aId) {
     if (this._requests && this._requests[aId]) {
       return this._requests[aId];
     }
   },
   getPromiseResolver: function(aId) {
     // Delegates to getRequest() since the lookup table is agnostic about
     // storage.
     return this.getRequest(aId);
   },
   removeRequest: function(aId) {
     if (this._requests && this._requests[aId]) {
       delete this._requests[aId];
     }
   },
   removePromiseResolver: function(aId) {
     // Delegates to getRequest() since the lookup table is agnostic about
     // storage.
     this.removeRequest(aId);
   },
   takeRequest: function(aId) {
     if (!this._requests || !this._requests[aId]) {
       return null;
     }
     let request = this._requests[aId];
     delete this._requests[aId];
     return request;
   },
   takePromiseResolver: function(aId) {
     // Delegates to getRequest() since the lookup table is agnostic about
     // storage.
     return this.takeRequest(aId);
   },
   _getRandomId: function() {
     return Cc["@mozilla.org/uuid-generator;1"]
              .getService(Ci.nsIUUIDGenerator).generateUUID().toString();
   },
   createRequest: function() {
     return Services.DOMRequest.createRequest(this._window);
   },
   /**
    * createPromise() creates a new Promise, with `aPromiseInit` as the
    * PromiseInit callback. The promise constructor is obtained from the
    * reference to window owned by this DOMRequestIPCHelper.
    */
   createPromise: function(aPromiseInit) {
     return new this._window.Promise(aPromiseInit);
   },
   forEachRequest: function(aCallback) {
     if (!this._requests) {
       return;
     }
     Object.keys(this._requests).forEach((aKey) => {
       if (this.getRequest(aKey) instanceof this._window.DOMRequest) {
         aCallback(aKey);
       }
     });
   },
   forEachPromiseResolver: function(aCallback) {
     if (!this._requests) {
       return;
     }
     Object.keys(this._requests).forEach((aKey) => {
       if ("resolve" in this.getPromiseResolver(aKey) &&
           "reject" in this.getPromiseResolver(aKey)) {
         aCallback(aKey);
       }
     });
   },
 }

The Tor Browser / annotate

dom/base/DOMRequestHelper.jsm@b8a032363ba2 (annotated)

dom/base/DOMRequestHelper.jsm