gecko/services/sync/modules/syncCores.js

/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Bookmarks Sync.
 *
 * The Initial Developer of the Original Code is Mozilla.
 * Portions created by the Initial Developer are Copyright (C) 2007
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *  Dan Mills <thunder@mozilla.com>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

const EXPORTED_SYMBOLS = ['SyncCore', 'BookmarksSyncCore', 'HistorySyncCore', 'CookieSyncCore'];

const Cc = Components.classes;
const Ci = Components.interfaces;
const Cr = Components.results;
const Cu = Components.utils;

Cu.import("resource://gre/modules/XPCOMUtils.jsm");
Cu.import("resource://weave/log4moz.js");
Cu.import("resource://weave/constants.js");
Cu.import("resource://weave/util.js");
Cu.import("resource://weave/async.js");

Function.prototype.async = Async.sugar;

/*
 * SyncCore objects
 * Sync cores deal with diff creation and conflict resolution.
 * Tree data structures where all nodes have GUIDs only need to be
 * subclassed for each data type to implement commandLike and
 * itemExists.
 */

function SyncCore() {
  this._init();
}
SyncCore.prototype = {
  _logName: "Sync",

  _init: function SC__init() {
    this._log = Log4Moz.Service.getLogger("Service." + this._logName);
  },

  // FIXME: this won't work for deep objects, or objects with optional properties
  _getEdits: function SC__getEdits(a, b) {
    let ret = {numProps: 0, props: {}};
    for (prop in a) {
      if (!Utils.deepEquals(a[prop], b[prop])) {
        ret.numProps++;
        ret.props[prop] = b[prop];
      }
    }
    return ret;
  },

  _nodeParents: function SC__nodeParents(GUID, tree) {
    return this._nodeParentsInt(GUID, tree, []);
  },

  _nodeParentsInt: function SC__nodeParentsInt(GUID, tree, parents) {
    if (!tree[GUID] || !tree[GUID].parentGUID)
      return parents;
    parents.push(tree[GUID].parentGUID);
    return this._nodeParentsInt(tree[GUID].parentGUID, tree, parents);
  },

  _detectUpdates: function SC__detectUpdates(a, b) {
    let self = yield;
    let listener = new Utils.EventListener(self.cb);
    let timer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);

    let cmds = [];

    try {
      for (let GUID in a) {

        timer.initWithCallback(listener, 0, timer.TYPE_ONE_SHOT);
        yield; // Yield to main loop

        if (GUID in b) {
          let edits = this._getEdits(a[GUID], b[GUID]);
          if (edits.numProps == 0) // no changes - skip
            continue;
          let parents = this._nodeParents(GUID, b);
          cmds.push({action: "edit", GUID: GUID,
                     depth: parents.length, parents: parents,
                     data: edits.props});
        } else {
          let parents = this._nodeParents(GUID, a); // ???
          cmds.push({action: "remove", GUID: GUID,
                     depth: parents.length, parents: parents});
        }
      }

      for (let GUID in b) {

        timer.initWithCallback(listener, 0, timer.TYPE_ONE_SHOT);
        yield; // Yield to main loop

        if (GUID in a)
          continue;
        let parents = this._nodeParents(GUID, b);
        cmds.push({action: "create", GUID: GUID,
                   depth: parents.length, parents: parents,
                   data: b[GUID]});
      }
      cmds.sort(function(a, b) {
        if (a.depth > b.depth)
          return 1;
        if (a.depth < b.depth)
          return -1;
        if (a.index > b.index)
          return -1;
        if (a.index < b.index)
          return 1;
        return 0; // should never happen, but not a big deal if it does
      });

    } catch (e) {
      throw e;

    } finally {
      timer = null;
      self.done(cmds);
    }
  },

  _commandLike: function SC__commandLike(a, b) {
    this._log.error("commandLike needs to be subclassed");

    // Check that neither command is null, and verify that the GUIDs
    // are different (otherwise we need to check for edits)
    if (!a || !b || a.GUID == b.GUID)
      return false;

    // Check that all other properties are the same
    // FIXME: could be optimized...
    for (let key in a) {
      if (key != "GUID" && !Utils.deepEquals(a[key], b[key]))
        return false;
    }
    for (let key in b) {
      if (key != "GUID" && !Utils.deepEquals(a[key], b[key]))
        return false;
    }
    return true;
  },

  // When we change the GUID of a local item (because we detect it as
  // being the same item as a remote one), we need to fix any other
  // local items that have it as their parent
  _fixParents: function SC__fixParents(list, oldGUID, newGUID) {
    for (let i = 0; i < list.length; i++) {
      if (!list[i])
        continue;
      if (list[i].data && list[i].data.parentGUID == oldGUID)
        list[i].data.parentGUID = newGUID;
      for (let j = 0; j < list[i].parents.length; j++) {
        if (list[i].parents[j] == oldGUID)
          list[i].parents[j] = newGUID;
      }
    }
  },

  _conflicts: function SC__conflicts(a, b) {
    if ((a.GUID == b.GUID) && !Utils.deepEquals(a, b))
      return true;
    return false;
  },

  _getPropagations: function SC__getPropagations(commands, conflicts, propagations) {
    for (let i = 0; i < commands.length; i++) {
      let alsoConflicts = function(elt) {
        return (elt.action == "create" || elt.action == "remove") &&
          commands[i].parents.indexOf(elt.GUID) >= 0;
      };
      if (conflicts.some(alsoConflicts))
        conflicts.push(commands[i]);

      let cmdConflicts = function(elt) {
        return elt.GUID == commands[i].GUID;
      };
      if (!conflicts.some(cmdConflicts))
        propagations.push(commands[i]);
    }
  },

  _itemExists: function SC__itemExists(GUID) {
    this._log.error("itemExists needs to be subclassed");
    return false;
  },

  _reconcile: function SC__reconcile(listA, listB) {
    let self = yield;
    let listener = new Utils.EventListener(self.cb);
    let timer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);

    let propagations = [[], []];
    let conflicts = [[], []];
    let ret = {propagations: propagations, conflicts: conflicts};
    this._log.debug("Reconciling " + listA.length +
		    " against " + listB.length + "commands");

    let guidChanges = [];
    for (let i = 0; i < listA.length; i++) {
      let a = listA[i];
      timer.initWithCallback(listener, 0, timer.TYPE_ONE_SHOT);
      yield; // Yield to main loop

      //this._log.debug("comparing " + i + ", listB length: " + listB.length);

      let skip = false;
      listB = listB.filter(function(b) {
        // fast path for when we already found a matching command
        if (skip)
          return true;

        if (Utils.deepEquals(a, b)) {
          delete listA[i]; // a
          skip = true;
          return false; // b

        } else if (this._commandLike(a, b)) {
          this._fixParents(listA, a.GUID, b.GUID);
          guidChanges.push({action: "edit",
      		      GUID: a.GUID,
      		      data: {GUID: b.GUID}});
          delete listA[i]; // a
          skip = true;
          return false; // b, but we add it back from guidChanges
        }

        // watch out for create commands with GUIDs that already exist
        if (b.action == "create" && this._itemExists(b.GUID)) {
          this._log.error("Remote command has GUID that already exists " +
                          "locally. Dropping command.");
          return false; // delete b
        }
        return true; // keep b
      }, this);
    }

    listA = listA.filter(function(elt) { return elt });
    listB = guidChanges.concat(listB);

    for (let i = 0; i < listA.length; i++) {
      for (let j = 0; j < listB.length; j++) {

        timer.initWithCallback(listener, 0, timer.TYPE_ONE_SHOT);
        yield; // Yield to main loop

        if (this._conflicts(listA[i], listB[j]) ||
            this._conflicts(listB[j], listA[i])) {
          if (!conflicts[0].some(
            function(elt) { return elt.GUID == listA[i].GUID }))
            conflicts[0].push(listA[i]);
          if (!conflicts[1].some(
            function(elt) { return elt.GUID == listB[j].GUID }))
            conflicts[1].push(listB[j]);
        }
      }
    }

    this._getPropagations(listA, conflicts[0], propagations[1]);

    timer.initWithCallback(listener, 0, timer.TYPE_ONE_SHOT);
    yield; // Yield to main loop

    this._getPropagations(listB, conflicts[1], propagations[0]);
    ret = {propagations: propagations, conflicts: conflicts};

    timer = null;
    self.done(ret);
  },

  // Public methods

  detectUpdates: function SC_detectUpdates(onComplete, a, b) {
    return this._detectUpdates.async(this, onComplete, a, b);
  },

  reconcile: function SC_reconcile(onComplete, listA, listB) {
    return this._reconcile.async(this, onComplete, listA, listB);
  }
};

function BookmarksSyncCore() {
  this._init();
}
BookmarksSyncCore.prototype = {
  _logName: "BMSync",

  __bms: null,
  get _bms() {
    if (!this.__bms)
      this.__bms = Cc["@mozilla.org/browser/nav-bookmarks-service;1"].
                   getService(Ci.nsINavBookmarksService);
    return this.__bms;
  },

  _itemExists: function BSC__itemExists(GUID) {
    return this._bms.getItemIdForGUID(GUID) >= 0;
  },

  _getEdits: function BSC__getEdits(a, b) {
    // NOTE: we do not increment ret.numProps, as that would cause
    // edit commands to always get generated
    let ret = SyncCore.prototype._getEdits.call(this, a, b);
    ret.props.type = a.type;
    return ret;
  },

  // compares properties
  // returns true if the property is not set in either object
  // returns true if the property is set and equal in both objects
  // returns false otherwise
  _comp: function BSC__comp(a, b, prop) {
    return (!a.data[prop] && !b.data[prop]) ||
      (a.data[prop] && b.data[prop] && (a.data[prop] == b.data[prop]));
  },

  _commandLike: function BSC__commandLike(a, b) {
    // Check that neither command is null, that their actions, types,
    // and parents are the same, and that they don't have the same
    // GUID.
    // * Items with the same GUID do not qualify for 'likeness' because
    //   we already consider them to be the same object, and therefore
    //   we need to process any edits.
    // * Remove or edit commands don't qualify for likeness either,
    //   since remove or edit commands with different GUIDs are
    //   guaranteed to refer to two different items
    // * The parent GUID check works because reconcile() fixes up the
    //   parent GUIDs as it runs, and the command list is sorted by
    //   depth
    if (!a || !b ||
        a.action != b.action ||
        a.action != "create" ||
        a.data.type != b.data.type ||
        a.data.parentGUID != b.data.parentGUID ||
        a.GUID == b.GUID)
      return false;

    // Bookmarks are allowed to be in a different index as long as
    // they are in the same folder.  Folders and separators must be at
    // the same index to qualify for 'likeness'.
    switch (a.data.type) {
    case "bookmark":
      if (this._comp(a, b, 'URI') &&
          this._comp(a, b, 'title'))
        return true;
      return false;
    case "query":
      if (this._comp(a, b, 'URI') &&
          this._comp(a, b, 'title'))
        return true;
      return false;
    case "microsummary":
      if (this._comp(a, b, 'URI') &&
          this._comp(a, b, 'generatorURI'))
        return true;
      return false;
    case "folder":
      if (this._comp(a, b, 'index') &&
          this._comp(a, b, 'title'))
        return true;
      return false;
    case "livemark":
      if (this._comp(a, b, 'title') &&
          this._comp(a, b, 'siteURI') &&
          this._comp(a, b, 'feedURI'))
        return true;
      return false;
    case "separator":
      if (this._comp(a, b, 'index'))
        return true;
      return false;
    default:
      let json = Cc["@mozilla.org/dom/json;1"].createInstance(Ci.nsIJSON);
      this._log.error("commandLike: Unknown item type: " + json.encode(a));
      return false;
    }
  }
};
BookmarksSyncCore.prototype.__proto__ = new SyncCore();

function HistorySyncCore() {
  this._init();
}
HistorySyncCore.prototype = {
  _logName: "HistSync",

  _itemExists: function BSC__itemExists(GUID) {
    // we don't care about already-existing items; just try to re-add them
    return false;
  },

  _commandLike: function BSC_commandLike(a, b) {
    // History commands never qualify for likeness.  We will always
    // take the union of all client/server items.  We use the URL as
    // the GUID, so the same sites will map to the same item (same
    // GUID), without our intervention.
    return false;
  }
};
HistorySyncCore.prototype.__proto__ = new SyncCore();


function CookieSyncCore() {
  this._init();
}
CookieSyncCore.prototype = {
  _logName: "CookieSync",

  __cookieManager: null,
  get _cookieManager() {
    if (!this.__cookieManager)
      this.__cookieManager = Cc["@mozilla.org/cookiemanager;1"].
                             getService(Ci.nsICookieManager2);
    // need the 2nd revision of the ICookieManager interface
    // because it supports add() and the 1st one doesn't.
    return this.__cookieManager
  },


  _itemExists: function CSC__itemExists(GUID) {
    /* true if a cookie with the given GUID exists.
       The GUID that we are passed should correspond to the keys
       that we define in the JSON returned by CookieStore.wrap()
       That is, it will be a string of the form
       "host:path:name". */
    
    /* TODO verify that colons can't normally appear in any of
       the fields -- if they did it then we can't rely on .split(":")
       to parse correctly.*/
    
    let cookieArray = GUID.split( ":" );
    let cookieHost = cookieArray[0];
    let cookiePath = cookieArray[1];
    let cookieName = cookieArray[2];

    /* alternate implementation would be to instantiate a cookie from
       cookieHost, cookiePath, and cookieName, then call 
       cookieManager.cookieExists(). Maybe that would have better
       performance?  This implementation seems pretty slow.*/
    let enumerator = this._cookieManager.enumerator;
    while (enumerator.hasMoreElements())
      {
	let aCookie = enumerator.getNext();
	if (aCookie.host == cookieHost &&
	    aCookie.path == cookiePath &&
	    aCookie.name == cookieName ) {
	  return true;
	}
      }
    return false;
    /* Note: We can't just call cookieManager.cookieExists() with a generic
       javascript object with .host, .path, and .name attributes attatched.
       cookieExists is implemented in C and does a hard static_cast to an
       nsCookie object, so duck typing doesn't work (and in fact makes 
       Firefox hard-crash as the static_cast returns null and is not checked.)
    */
  },

  _commandLike: function CSC_commandLike(a, b) {
    // Method required to be overridden.
    // a and b each have a .data and a .GUID
    // If this function returns true, an editCommand will be
    // generated to try to resolve the thing.
    // but are a and b objects of the type in the Store or
    // are they "commands"??
    return false;
  }
};
CookieSyncCore.prototype.__proto__ = new SyncCore();