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/* 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";
const {Cc,Ci} = require("chrome");
// ## Implementation Notes ##
//
// Making `XMLHttpRequest` objects available to Jetpack code involves a
// few key principles universal to all low-level module implementations:
//
// * **Unloadability**. A Jetpack-based extension using this module can be
// asked to unload itself at any time, e.g. because the user decides to
// uninstall or disable the extension. This means we need to keep track of
// all in-progress reqests and abort them on unload.
//
// * **Developer-Ergonomic Tracebacks**. Whenever an exception is raised
// by a Jetpack-based extension, we want it to be logged in a
// place that is specific to that extension--so that a developer
// can distinguish it from an error on a web page or in another
// extension, for instance. We also want it to be logged with a
// full stack traceback, which the Mozilla platform doesn't usually
// do.
//
// Because of this, we don't actually want to give the Mozilla
// platform's "real" XHR implementation to clients, but instead provide
// a simple wrapper that trivially delegates to the implementation in
// all cases except where callbacks are involved: whenever Mozilla
// platform code calls into the extension, such as during the XHR's
// `onreadystatechange` callback, we want to wrap the client's callback
// in a try-catch clause that traps any exceptions raised by the
// callback and logs them via console.exception() instead of allowing
// them to propagate back into Mozilla platform code.
// This is a private list of all active requests, so we know what to
// abort if we're asked to unload.
var requests = [];
// Events on XHRs that we should listen for, so we know when to remove
// a request from our private list.
const TERMINATE_EVENTS = ["load", "error", "abort"];
// Read-only properties of XMLHttpRequest objects that we want to
// directly delegate to.
const READ_ONLY_PROPS = ["readyState", "responseText", "responseXML",
"status", "statusText"];
// Methods of XMLHttpRequest that we want to directly delegate to.
const DELEGATED_METHODS = ["abort", "getAllResponseHeaders",
"getResponseHeader", "overrideMimeType",
"send", "sendAsBinary", "setRequestHeader",
"open"];
var getRequestCount = exports.getRequestCount = function getRequestCount() {
return requests.length;
};
var XMLHttpRequest = exports.XMLHttpRequest = function XMLHttpRequest() {
var req = Cc["@mozilla.org/xmlextras/xmlhttprequest;1"]
.createInstance(Ci.nsIXMLHttpRequest);
// For the sake of simplicity, don't tie this request to any UI.
req.mozBackgroundRequest = true;
memory.track(req, "XMLHttpRequest");
this._req = req;
this._orsc = null;
requests.push(this);
var self = this;
this._boundCleanup = function _boundCleanup() {
self._cleanup();
};
TERMINATE_EVENTS.forEach(
function(name) {
self._req.addEventListener(name, self._boundCleanup, false);
});
};
XMLHttpRequest.prototype = {
_cleanup: function _cleanup() {
this.onreadystatechange = null;
var index = requests.indexOf(this);
if (index != -1) {
var self = this;
TERMINATE_EVENTS.forEach(
function(name) {
self._req.removeEventListener(name, self._boundCleanup, false);
});
requests.splice(index, 1);
}
},
_unload: function _unload() {
this._req.abort();
this._cleanup();
},
addEventListener: function addEventListener() {
throw new Error("not implemented");
},
removeEventListener: function removeEventListener() {
throw new Error("not implemented");
},
set upload(newValue) {
throw new Error("not implemented");
},
get onreadystatechange() {
return this._orsc;
},
set onreadystatechange(cb) {
this._orsc = cb;
if (cb) {
var self = this;
this._req.onreadystatechange = function() {
try {
self._orsc.apply(self, arguments);
} catch (e) {
console.exception(e);
}
};
} else
this._req.onreadystatechange = null;
}
};
READ_ONLY_PROPS.forEach(
function(name) {
XMLHttpRequest.prototype.__defineGetter__(
name,
function() {
return this._req[name];
});
});
DELEGATED_METHODS.forEach(
function(name) {
XMLHttpRequest.prototype[name] = function() {
return this._req[name].apply(this._req, arguments);
};
});
require("./unload").when(
function() {
requests.slice().forEach(function(request) { request._unload(); });
});
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