gecko-dev/dom/datastore/DataStoreChangeNotifier.jsm

/* 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 {classes: Cc, interfaces: Ci, utils: Cu, results: Cr} = Components;

this.EXPORTED_SYMBOLS = ["DataStoreChangeNotifier"];

function debug(s) {
  //dump('DEBUG DataStoreChangeNotifier: ' + s + '\n');
}

// DataStoreServiceInternal should not be converted into a lazy getter as it
// runs code during initialization.
Cu.import('resource://gre/modules/DataStoreServiceInternal.jsm');
Cu.import("resource://gre/modules/XPCOMUtils.jsm");
Cu.import("resource://gre/modules/Services.jsm");

XPCOMUtils.defineLazyServiceGetter(this, "ppmm",
                                   "@mozilla.org/parentprocessmessagemanager;1",
                                   "nsIMessageBroadcaster");

this.DataStoreChangeNotifier = {
  children: [],
  messages: [ "DataStore:Changed", "DataStore:RegisterForMessages",
              "child-process-shutdown" ],

  init: function() {
    debug("init");

    this.messages.forEach((function(msgName) {
      ppmm.addMessageListener(msgName, this);
    }).bind(this));

    Services.obs.addObserver(this, 'xpcom-shutdown', false);
  },

  observe: function(aSubject, aTopic, aData) {
    debug("observe");

    switch (aTopic) {
      case 'xpcom-shutdown':
        this.messages.forEach((function(msgName) {
          ppmm.removeMessageListener(msgName, this);
        }).bind(this));

        Services.obs.removeObserver(this, 'xpcom-shutdown');
        ppmm = null;
        break;

      default:
        debug("Wrong observer topic: " + aTopic);
        break;
    }
  },

  broadcastMessage: function broadcastMessage(aMsgName, aData) {
    debug("Broadast");
    this.children.forEach(function(obj) {
      if (obj.store == aData.store && obj.owner == aData.owner) {
        obj.mm.sendAsyncMessage(aMsgName, aData.message);
      }
    });
  },

  receiveMessage: function(aMessage) {
    debug("receiveMessage");

    switch (aMessage.name) {
      case "DataStore:Changed":
        this.broadcastMessage("DataStore:Changed:Return:OK", aMessage.data);
        break;

      case "DataStore:RegisterForMessages":
        debug("Register!");

        for (let i = 0; i < this.children.length; ++i) {
          if (this.children[i].mm == aMessage.target &&
              this.children[i].store == aMessage.data.store &&
              this.children[i].owner == aMessage.data.owner) {
            return;
          }
        }

        this.children.push({ mm: aMessage.target,
                             store: aMessage.data.store,
                             owner: aMessage.data.owner });
        break;

      case "child-process-shutdown":
        debug("Unregister");

        for (let i = 0; i < this.children.length;) {
          if (this.children[i].mm == aMessage.target) {
            debug("Unregister index: " + i);
            this.children.splice(i, 1);
          } else {
            ++i;
          }
        }
        break;

      default:
        debug("Wrong message: " + aMessage.name);
    }
  }
}

DataStoreChangeNotifier.init();