michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
michael@0:  * You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: "use strict"
michael@0: 
michael@0: const DEBUG = false;
michael@0: function debug(s) {
michael@0:   if (DEBUG) dump("-*- SettingsChangeNotifier: " + s + "\n");
michael@0: }
michael@0: 
michael@0: const Cu = Components.utils;
michael@0: const Cc = Components.classes;
michael@0: const Ci = Components.interfaces;
michael@0: 
michael@0: this.EXPORTED_SYMBOLS = ["SettingsChangeNotifier"];
michael@0: 
michael@0: Cu.import("resource://gre/modules/XPCOMUtils.jsm");
michael@0: Cu.import("resource://gre/modules/Services.jsm");
michael@0: 
michael@0: const kXpcomShutdownObserverTopic      = "xpcom-shutdown";
michael@0: const kMozSettingsChangedObserverTopic = "mozsettings-changed";
michael@0: const kFromSettingsChangeNotifier      = "fromSettingsChangeNotifier";
michael@0: 
michael@0: XPCOMUtils.defineLazyServiceGetter(this, "ppmm",
michael@0:                                    "@mozilla.org/parentprocessmessagemanager;1",
michael@0:                                    "nsIMessageBroadcaster");
michael@0: 
michael@0: this.SettingsChangeNotifier = {
michael@0:   init: function() {
michael@0:     if (DEBUG) debug("init");
michael@0:     this.children = [];
michael@0:     this._messages = ["Settings:Changed", "Settings:RegisterForMessages", "child-process-shutdown"];
michael@0:     this._messages.forEach((function(msgName) {
michael@0:       ppmm.addMessageListener(msgName, this);
michael@0:     }).bind(this));
michael@0: 
michael@0:     Services.obs.addObserver(this, kXpcomShutdownObserverTopic, false);
michael@0:     Services.obs.addObserver(this, kMozSettingsChangedObserverTopic, false);
michael@0:   },
michael@0: 
michael@0:   observe: function(aSubject, aTopic, aData) {
michael@0:     if (DEBUG) debug("observe");
michael@0:     switch (aTopic) {
michael@0:       case kXpcomShutdownObserverTopic:
michael@0:         this._messages.forEach((function(msgName) {
michael@0:           ppmm.removeMessageListener(msgName, this);
michael@0:         }).bind(this));
michael@0:         Services.obs.removeObserver(this, kXpcomShutdownObserverTopic);
michael@0:         Services.obs.removeObserver(this, kMozSettingsChangedObserverTopic);
michael@0:         ppmm = null;
michael@0:         break;
michael@0:       case kMozSettingsChangedObserverTopic:
michael@0:       {
michael@0:         let setting = JSON.parse(aData);
michael@0:         // To avoid redundantly broadcasting settings-changed events that are
michael@0:         // just requested from content processes themselves, skip the observer
michael@0:         // messages that are notified from the internal SettingsChangeNotifier.
michael@0:         if (setting.message && setting.message === kFromSettingsChangeNotifier)
michael@0:           return;
michael@0:         this.broadcastMessage("Settings:Change:Return:OK",
michael@0:           { key: setting.key, value: setting.value });
michael@0:         break;
michael@0:       }
michael@0:       default:
michael@0:         if (DEBUG) debug("Wrong observer topic: " + aTopic);
michael@0:         break;
michael@0:     }
michael@0:   },
michael@0: 
michael@0:   broadcastMessage: function broadcastMessage(aMsgName, aContent) {
michael@0:     if (DEBUG) debug("Broadast");
michael@0:     this.children.forEach(function(msgMgr) {
michael@0:       msgMgr.sendAsyncMessage(aMsgName, aContent);
michael@0:     });
michael@0:   },
michael@0: 
michael@0:   receiveMessage: function(aMessage) {
michael@0:     if (DEBUG) debug("receiveMessage");
michael@0:     let msg = aMessage.data;
michael@0:     let mm = aMessage.target;
michael@0:     switch (aMessage.name) {
michael@0:       case "Settings:Changed":
michael@0:         if (!aMessage.target.assertPermission("settings-write")) {
michael@0:           Cu.reportError("Settings message " + msg.name +
michael@0:                          " from a content process with no 'settings-write' privileges.");
michael@0:           return null;
michael@0:         }
michael@0:         this.broadcastMessage("Settings:Change:Return:OK",
michael@0:           { key: msg.key, value: msg.value });
michael@0:         Services.obs.notifyObservers(this, kMozSettingsChangedObserverTopic,
michael@0:           JSON.stringify({
michael@0:             key: msg.key,
michael@0:             value: msg.value,
michael@0:             message: kFromSettingsChangeNotifier
michael@0:           }));
michael@0:         break;
michael@0:       case "Settings:RegisterForMessages":
michael@0:         if (!aMessage.target.assertPermission("settings-read")) {
michael@0:           Cu.reportError("Settings message " + msg.name +
michael@0:                          " from a content process with no 'settings-read' privileges.");
michael@0:           return null;
michael@0:         }
michael@0:         if (DEBUG) debug("Register!");
michael@0:         if (this.children.indexOf(mm) == -1) {
michael@0:           this.children.push(mm);
michael@0:         }
michael@0:         break;
michael@0:       case "child-process-shutdown":
michael@0:         if (DEBUG) debug("Unregister");
michael@0:         let index;
michael@0:         if ((index = this.children.indexOf(mm)) != -1) {
michael@0:           if (DEBUG) debug("Unregister index: " + index);
michael@0:           this.children.splice(index, 1);
michael@0:         }
michael@0:         break;
michael@0:       default:
michael@0:         if (DEBUG) debug("Wrong message: " + aMessage.name);
michael@0:     }
michael@0:   }
michael@0: }
michael@0: 
michael@0: SettingsChangeNotifier.init();