The Tor Browser: addon-sdk/source/lib/sdk/system/unload.js@6474c204b198

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

     1 /* This Source Code Form is subject to the terms of the Mozilla Public

     2  * License, v. 2.0. If a copy of the MPL was not distributed with this

     3  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

     5 // Parts of this module were taken from narwhal:

     6 //

     7 // http://narwhaljs.org

     9 module.metadata = {

    10   "stability": "experimental"

    11 };

    13 const { on, off } = require('./events');

    14 const unloadSubject = require('@loader/unload');

    16 const observers = [];

    17 const unloaders = [];

    19 var when = exports.when = function when(observer) {

    20   if (observers.indexOf(observer) != -1)

    21     return;

    22   observers.unshift(observer);

    23 };

    25 var ensure = exports.ensure = function ensure(obj, destructorName) {

    26   if (!destructorName)

    27     destructorName = "unload";

    28   if (!(destructorName in obj))

    29     throw new Error("object has no '" + destructorName + "' property");

    31   let called = false;

    32   let originalDestructor = obj[destructorName];

    34   function unloadWrapper(reason) {

    35     if (!called) {

    36       called = true;

    37       let index = unloaders.indexOf(unloadWrapper);

    38       if (index == -1)

    39         throw new Error("internal error: unloader not found");

    40       unloaders.splice(index, 1);

    41       originalDestructor.call(obj, reason);

    42       originalDestructor = null;

    43       destructorName = null;

    44       obj = null;

    45     }

    46   };

    48   // TODO: Find out why the order is inverted here. It seems that

    49   // it may be causing issues!

    50   unloaders.push(unloadWrapper);

    52   obj[destructorName] = unloadWrapper;

    53 };

    55 function unload(reason) {

    56   observers.forEach(function(observer) {

    57     try {

    58       observer(reason);

    59     }

    60     catch (error) {

    61       console.exception(error);

    62     }

    63   });

    64 }

    66 when(function(reason) {

    67   unloaders.slice().forEach(function(unloadWrapper) {

    68     unloadWrapper(reason);

    69   });

    70 });

    72 on('sdk:loader:destroy', function onunload({ subject, data: reason }) {

    73   // If this loader is unload then `subject.wrappedJSObject` will be

    74   // `destructor`.

    75   if (subject.wrappedJSObject === unloadSubject) {

    76     off('sdk:loader:destroy', onunload);

    77     unload(reason);

    78   }

    79 // Note that we use strong reference to listener here to make sure it's not

    80 // GC-ed, which may happen otherwise since nothing keeps reference to `onunolad`

    81 // function.

    82 }, true);

The Tor Browser / file revision