Bug 915598 - Allow strong references to DOMRequestIPCHelper message listeners. Part 1: DOMRequestHelper. r=fabrice

This commit is contained in:
Fernando Jiménez 2013-10-04 23:59:48 +02:00
parent b284d9f9b7
commit 3d1216244e

View File

@ -3,12 +3,23 @@
* You can obtain one at http://mozilla.org/MPL/2.0/. */
/**
* Helper object for APIs that deal with DOMRequests and Promises and need to
* release them when the window goes out of scope.
* 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"];
@ -19,45 +30,148 @@ XPCOMUtils.defineLazyServiceGetter(this, "cpmm",
"@mozilla.org/childprocessmessagemanager;1",
"nsIMessageListenerManager");
/**
* We use DOMRequestIpcHelperMessageListener to avoid leaking objects which
* "inherit" from DOMRequestIpcHelper.
*
* The issue is that the message manager will hold a strong ref to the message
* listener we register with it. But we don't want to hold a strong ref to the
* DOMRequestIpcHelper object, because that object may be arbitrarily large.
*
* So instead the message manager holds a strong ref to the
* DOMRequestIpcHelperMessageListener, and that holds a /weak/ ref to its
* DOMRequestIpcHelper.
*
* Additionally, we want to unhook all of these message listeners when the
* appropriate window is destroyed. We use DOMRequestIpcHelperMessageListener
* for this, too.
*/
this.DOMRequestIpcHelperMessageListener = function(aHelper, aWindow, aMessages) {
this._weakHelper = Cu.getWeakReference(aHelper);
this._messages = aMessages;
this._messages.forEach(function(msgName) {
cpmm.addWeakMessageListener(msgName, this);
}, this);
Services.obs.addObserver(this, "inner-window-destroyed", /* weakRef */ true);
// aWindow may be null; in that case, the DOMRequestIpcHelperMessageListener
// is not tied to a particular window and lives forever.
if (aWindow) {
let util = aWindow.QueryInterface(Ci.nsIInterfaceRequestor)
.getInterface(Ci.nsIDOMWindowUtils);
this._innerWindowID = util.currentInnerWindowID;
}
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 strong or not.
this._listeners = null;
this._requests = null;
this._window = null;
}
DOMRequestIpcHelperMessageListener.prototype = {
QueryInterface: XPCOMUtils.generateQI([Ci.nsIMessageListener,
Ci.nsIObserver,
Ci.nsISupportsWeakReference]),
DOMRequestIpcHelper.prototype = {
/**
* An object which "inherits" from DOMRequestIpcHelper, declares its own
* queryInterface method and adds at least one weak listener to the Message
* Manager MUST implement Ci.nsISupportsWeakReference.
*/
QueryInterface: XPCOMUtils.generateQI([Ci.nsISupportsWeakReference]),
/**
* 'aMessages' is expected to be an array of either:
* - objects of this form:
* {
* name: "messageName",
* strongRef: false
* }
* where 'name' is the message identifier and 'strongRef' a boolean
* indicating if the listener should be a strong referred one or not.
*
* - or only strings containing the message name, in which case the listener
* will be added as a weak 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.strongRef == this._listeners[name]) {
return;
} else {
throw Cr.NS_ERROR_FAILURE;
}
}
aMsg.strongRef ? cpmm.addMessageListener(name, this)
: cpmm.addWeakMessageListener(name, this);
this._listeners[name] = !!aMsg.strongRef;
});
},
/**
* '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.removeMessageListener(aName, this)
: cpmm.removeWeakMessageListener(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',
* strongRef: false
* }
* where 'name' is the message identifier and 'strongRef' a boolean
* indicating if the listener should be a strong referred one or not.
*
* - or only strings containing the message name, in which case the listener
* will be added as a weak referred one by default.
*/
initDOMRequestHelper: function(aWindow, aMessages) {
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;
}
Services.obs.addObserver(this, "inner-window-destroyed", false);
},
destroyDOMRequestHelper: function() {
Services.obs.removeObserver(this, "inner-window-destroyed");
if (this._listeners) {
Object.keys(this._listeners).forEach((aName) => {
this._listeners[aName] ? cpmm.removeMessageListener(aName, this)
: cpmm.removeWeakMessageListener(aName, this);
delete this._listeners[aName];
});
}
this._listeners = null;
this._requests = null;
this._window = null;
},
observe: function(aSubject, aTopic, aData) {
if (aTopic !== "inner-window-destroyed") {
@ -65,70 +179,18 @@ DOMRequestIpcHelperMessageListener.prototype = {
}
let wId = aSubject.QueryInterface(Ci.nsISupportsPRUint64).data;
if (wId != this._innerWindowID) {
if (wId != this.innerWindowID) {
return;
}
this.destroy();
},
receiveMessage: function(aMsg) {
let helper = this._weakHelper.get();
if (helper) {
helper.receiveMessage(aMsg);
} else {
this.destroy();
}
},
destroy: function() {
// DOMRequestIpcHelper.destroy() calls back into this function.
if (this._destroyed) {
return;
}
this._destroyed = true;
Services.obs.removeObserver(this, "inner-window-destroyed");
this._messages.forEach(function(msgName) {
cpmm.removeWeakMessageListener(msgName, this);
}, this);
this._messages = null;
let helper = this._weakHelper.get();
if (helper) {
helper.destroyDOMRequestHelper();
}
}
}
this.DOMRequestIpcHelper = function DOMRequestIpcHelper() {
}
DOMRequestIpcHelper.prototype = {
/**
* An object which "inherits" from DOMRequestIpcHelper and declares its own
* queryInterface method MUST implement Ci.nsISupportsWeakReference.
*/
QueryInterface: XPCOMUtils.generateQI([Ci.nsISupportsWeakReference]),
initDOMRequestHelper: function(aWindow, aMessages) {
this._DOMRequestIpcHelperMessageListener =
new DOMRequestIpcHelperMessageListener(this, aWindow, aMessages);
this._window = aWindow;
this._requests = {};
this._id = this._getRandomId();
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.destroyDOMRequestHelper();
},
getRequestId: function(aRequest) {
if (!this._requests) {
this._requests = {};
}
let id = "id" + this._getRandomId();
this._requests[id] = aRequest;
return id;
@ -141,8 +203,9 @@ DOMRequestIpcHelper.prototype = {
},
getRequest: function(aId) {
if (this._requests[aId])
if (this._requests && this._requests[aId]) {
return this._requests[aId];
}
},
getPromiseResolver: function(aId) {
@ -152,8 +215,9 @@ DOMRequestIpcHelper.prototype = {
},
removeRequest: function(aId) {
if (this._requests[aId])
if (this._requests && this._requests[aId]) {
delete this._requests[aId];
}
},
removePromiseResolver: function(aId) {
@ -163,8 +227,9 @@ DOMRequestIpcHelper.prototype = {
},
takeRequest: function(aId) {
if (!this._requests[aId])
if (!this._requests || !this._requests[aId]) {
return null;
}
let request = this._requests[aId];
delete this._requests[aId];
return request;
@ -177,25 +242,8 @@ DOMRequestIpcHelper.prototype = {
},
_getRandomId: function() {
return Cc["@mozilla.org/uuid-generator;1"].getService(Ci.nsIUUIDGenerator).generateUUID().toString();
},
destroyDOMRequestHelper: function() {
// This function is re-entrant --
// DOMRequestIpcHelperMessageListener.destroy() calls back into this
// function, and this.uninit() may also call it.
if (this._destroyed) {
return;
}
this._destroyed = true;
this._DOMRequestIpcHelperMessageListener.destroy();
this._requests = {};
this._window = null;
if(this.uninit) {
this.uninit();
}
return Cc["@mozilla.org/uuid-generator;1"]
.getService(Ci.nsIUUIDGenerator).generateUUID().toString();
},
createRequest: function() {
@ -212,19 +260,27 @@ DOMRequestIpcHelper.prototype = {
},
forEachRequest: function(aCallback) {
Object.keys(this._requests).forEach(function(k) {
if (this.getRequest(k) instanceof this._window.DOMRequest) {
aCallback(k);
if (!this._requests) {
return;
}
Object.keys(this._requests).forEach((aKey) => {
if (this.getRequest(aKey) instanceof this._window.DOMRequest) {
aCallback(aKey);
}
}, this);
});
},
forEachPromiseResolver: function(aCallback) {
Object.keys(this._requests).forEach(function(k) {
if ("resolve" in this.getPromiseResolver(k) &&
"reject" in this.getPromiseResolver(k)) {
aCallback(k);
if (!this._requests) {
return;
}
Object.keys(this._requests).forEach((aKey) => {
if ("resolve" in this.getPromiseResolver(aKey) &&
"reject" in this.getPromiseResolver(aKey)) {
aCallback(aKey);
}
}, this);
});
},
}