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comparison: addon-sdk/source/lib/sdk/core/disposable.js
addon-sdk/source/lib/sdk/core/disposable.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 "use strict"; | |
| 6 | |
| 7 module.metadata = { | |
| 8 "stability": "experimental" | |
| 9 }; | |
| 10 | |
| 11 | |
| 12 const { Class } = require("./heritage"); | |
| 13 const { Observer, subscribe, unsubscribe, observe } = require("./observer"); | |
| 14 const { isWeak, WeakReference } = require("./reference"); | |
| 15 const method = require("../../method/core"); | |
| 16 | |
| 17 const unloadSubject = require('@loader/unload'); | |
| 18 const addonUnloadTopic = "sdk:loader:destroy"; | |
| 19 | |
| 20 | |
| 21 | |
| 22 const uninstall = method("disposable/uninstall"); | |
| 23 exports.uninstall = uninstall; | |
| 24 | |
| 25 | |
| 26 const shutdown = method("disposable/shutdown"); | |
| 27 exports.shutdown = shutdown; | |
| 28 | |
| 29 const disable = method("disposable/disable"); | |
| 30 exports.disable = disable; | |
| 31 | |
| 32 const upgrade = method("disposable/upgrade"); | |
| 33 exports.upgrade = upgrade; | |
| 34 | |
| 35 const downgrade = method("disposable/downgrade"); | |
| 36 exports.downgrade = downgrade; | |
| 37 | |
| 38 const unload = method("disposable/unload"); | |
| 39 exports.unload = unload; | |
| 40 | |
| 41 const dispose = method("disposable/dispose"); | |
| 42 exports.dispose = dispose; | |
| 43 dispose.define(Object, object => object.dispose()); | |
| 44 | |
| 45 | |
| 46 const setup = method("disposable/setup"); | |
| 47 exports.setup = setup; | |
| 48 setup.define(Object, (object, ...args) => object.setup(...args)); | |
| 49 | |
| 50 | |
| 51 // Set's up disposable instance. | |
| 52 const setupDisposable = disposable => { | |
| 53 subscribe(disposable, addonUnloadTopic, isWeak(disposable)); | |
| 54 }; | |
| 55 | |
| 56 // Tears down disposable instance. | |
| 57 const disposeDisposable = disposable => { | |
| 58 unsubscribe(disposable, addonUnloadTopic); | |
| 59 }; | |
| 60 | |
| 61 // Base type that takes care of disposing it's instances on add-on unload. | |
| 62 // Also makes sure to remove unload listener if it's already being disposed. | |
| 63 const Disposable = Class({ | |
| 64 implements: [Observer], | |
| 65 initialize: function(...args) { | |
| 66 // First setup instance before initializing it's disposal. If instance | |
| 67 // fails to initialize then there is no instance to be disposed at the | |
| 68 // unload. | |
| 69 setup(this, ...args); | |
| 70 setupDisposable(this); | |
| 71 }, | |
| 72 destroy: function(reason) { | |
| 73 // Destroying disposable removes unload handler so that attempt to dispose | |
| 74 // won't be made at unload & delegates to dispose. | |
| 75 disposeDisposable(this); | |
| 76 unload(this, reason); | |
| 77 }, | |
| 78 setup: function() { | |
| 79 // Implement your initialize logic here. | |
| 80 }, | |
| 81 dispose: function() { | |
| 82 // Implement your cleanup logic here. | |
| 83 } | |
| 84 }); | |
| 85 exports.Disposable = Disposable; | |
| 86 | |
| 87 // Disposable instances observe add-on unload notifications in | |
| 88 // order to trigger `unload` on them. | |
| 89 observe.define(Disposable, (disposable, subject, topic, data) => { | |
| 90 const isUnloadTopic = topic === addonUnloadTopic; | |
| 91 const isUnloadSubject = subject.wrappedJSObject === unloadSubject; | |
| 92 if (isUnloadTopic && isUnloadSubject) { | |
| 93 unsubscribe(disposable, topic); | |
| 94 unload(disposable); | |
| 95 } | |
| 96 }); | |
| 97 | |
| 98 const unloaders = { | |
| 99 destroy: dispose, | |
| 100 uninstall: uninstall, | |
| 101 shutdown: shutdown, | |
| 102 disable: disable, | |
| 103 upgrade: upgrade, | |
| 104 downgrade: downgrade | |
| 105 } | |
| 106 const unloaded = new WeakMap(); | |
| 107 unload.define(Disposable, (disposable, reason) => { | |
| 108 if (!unloaded.get(disposable)) { | |
| 109 unloaded.set(disposable, true); | |
| 110 // Pick an unload handler associated with an unload | |
| 111 // reason (falling back to destroy if not found) and | |
| 112 // delegate unloading to it. | |
| 113 const unload = unloaders[reason] || unloaders.destroy; | |
| 114 unload(disposable); | |
| 115 } | |
| 116 }); | |
| 117 | |
| 118 | |
| 119 // If add-on is disabled munally, it's being upgraded, downgraded | |
| 120 // or uniststalled `dispose` is invoked to undo any changes that | |
| 121 // has being done by it in this session. | |
| 122 disable.define(Disposable, dispose); | |
| 123 downgrade.define(Disposable, dispose); | |
| 124 upgrade.define(Disposable, dispose); | |
| 125 uninstall.define(Disposable, dispose); | |
| 126 | |
| 127 // If application is shut down no dispose is invoked as undo-ing | |
| 128 // changes made by instance is likely to just waste of resources & | |
| 129 // increase shutdown time. Although specefic components may choose | |
| 130 // to implement shutdown handler that does something better. | |
| 131 shutdown.define(Disposable, disposable => {}); | |
| 132 |
