The Tor Browser / file comparison
comparison: addon-sdk/source/lib/sdk/system/unload.js
addon-sdk/source/lib/sdk/system/unload.js
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| 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/. */ | |
| 4 | |
| 5 // Parts of this module were taken from narwhal: | |
| 6 // | |
| 7 // http://narwhaljs.org | |
| 8 | |
| 9 module.metadata = { | |
| 10 "stability": "experimental" | |
| 11 }; | |
| 12 | |
| 13 const { on, off } = require('./events'); | |
| 14 const unloadSubject = require('@loader/unload'); | |
| 15 | |
| 16 const observers = []; | |
| 17 const unloaders = []; | |
| 18 | |
| 19 var when = exports.when = function when(observer) { | |
| 20 if (observers.indexOf(observer) != -1) | |
| 21 return; | |
| 22 observers.unshift(observer); | |
| 23 }; | |
| 24 | |
| 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"); | |
| 30 | |
| 31 let called = false; | |
| 32 let originalDestructor = obj[destructorName]; | |
| 33 | |
| 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 }; | |
| 47 | |
| 48 // TODO: Find out why the order is inverted here. It seems that | |
| 49 // it may be causing issues! | |
| 50 unloaders.push(unloadWrapper); | |
| 51 | |
| 52 obj[destructorName] = unloadWrapper; | |
| 53 }; | |
| 54 | |
| 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 } | |
| 65 | |
| 66 when(function(reason) { | |
| 67 unloaders.slice().forEach(function(unloadWrapper) { | |
| 68 unloadWrapper(reason); | |
| 69 }); | |
| 70 }); | |
| 71 | |
| 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); |
