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+/* 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/. */
+
+this.EXPORTED_SYMBOLS = [
+ "EngineManager",
+ "Engine",
+ "SyncEngine",
+ "Tracker",
+ "Store",
+ "Changeset"
+];
+
+var {classes: Cc, interfaces: Ci, results: Cr, utils: Cu} = Components;
+
+Cu.import("resource://services-common/async.js");
+Cu.import("resource://gre/modules/Log.jsm");
+Cu.import("resource://services-common/observers.js");
+Cu.import("resource://services-sync/constants.js");
+Cu.import("resource://services-sync/identity.js");
+Cu.import("resource://services-sync/record.js");
+Cu.import("resource://services-sync/resource.js");
+Cu.import("resource://services-sync/util.js");
+
+XPCOMUtils.defineLazyModuleGetter(this, "fxAccounts",
+ "resource://gre/modules/FxAccounts.jsm");
+
+/*
+ * Trackers are associated with a single engine and deal with
+ * listening for changes to their particular data type.
+ *
+ * There are two things they keep track of:
+ * 1) A score, indicating how urgently the engine wants to sync
+ * 2) A list of IDs for all the changed items that need to be synced
+ * and updating their 'score', indicating how urgently they
+ * want to sync.
+ *
+ */
+this.Tracker = function Tracker(name, engine) {
+ if (!engine) {
+ throw new Error("Tracker must be associated with an Engine instance.");
+ }
+
+ name = name || "Unnamed";
+ this.name = this.file = name.toLowerCase();
+ this.engine = engine;
+
+ this._log = Log.repository.getLogger("Sync.Tracker." + name);
+ let level = Svc.Prefs.get("log.logger.engine." + this.name, "Debug");
+ this._log.level = Log.Level[level];
+
+ this._score = 0;
+ this._ignored = [];
+ this.ignoreAll = false;
+ this.changedIDs = {};
+ this.loadChangedIDs();
+
+ Svc.Obs.add("weave:engine:start-tracking", this);
+ Svc.Obs.add("weave:engine:stop-tracking", this);
+
+ Svc.Prefs.observe("engine." + this.engine.prefName, this);
+};
+
+Tracker.prototype = {
+ /*
+ * Score can be called as often as desired to decide which engines to sync
+ *
+ * Valid values for score:
+ * -1: Do not sync unless the user specifically requests it (almost disabled)
+ * 0: Nothing has changed
+ * 100: Please sync me ASAP!
+ *
+ * Setting it to other values should (but doesn't currently) throw an exception
+ */
+ get score() {
+ return this._score;
+ },
+
+ set score(value) {
+ this._score = value;
+ Observers.notify("weave:engine:score:updated", this.name);
+ },
+
+ // Should be called by service everytime a sync has been done for an engine
+ resetScore: function () {
+ this._score = 0;
+ },
+
+ persistChangedIDs: true,
+
+ /**
+ * Persist changedIDs to disk at a later date.
+ * Optionally pass a callback to be invoked when the write has occurred.
+ */
+ saveChangedIDs: function (cb) {
+ if (!this.persistChangedIDs) {
+ this._log.debug("Not saving changedIDs.");
+ return;
+ }
+ Utils.namedTimer(function () {
+ this._log.debug("Saving changed IDs to " + this.file);
+ Utils.jsonSave("changes/" + this.file, this, this.changedIDs, cb);
+ }, 1000, this, "_lazySave");
+ },
+
+ loadChangedIDs: function (cb) {
+ Utils.jsonLoad("changes/" + this.file, this, function(json) {
+ if (json && (typeof(json) == "object")) {
+ this.changedIDs = json;
+ } else if (json !== null) {
+ this._log.warn("Changed IDs file " + this.file + " contains non-object value.");
+ json = null;
+ }
+ if (cb) {
+ cb.call(this, json);
+ }
+ });
+ },
+
+ // ignore/unignore specific IDs. Useful for ignoring items that are
+ // being processed, or that shouldn't be synced.
+ // But note: not persisted to disk
+
+ ignoreID: function (id) {
+ this.unignoreID(id);
+ this._ignored.push(id);
+ },
+
+ unignoreID: function (id) {
+ let index = this._ignored.indexOf(id);
+ if (index != -1)
+ this._ignored.splice(index, 1);
+ },
+
+ _saveChangedID(id, when) {
+ this._log.trace(`Adding changed ID: ${id}, ${JSON.stringify(when)}`);
+ this.changedIDs[id] = when;
+ this.saveChangedIDs(this.onSavedChangedIDs);
+ },
+
+ addChangedID: function (id, when) {
+ if (!id) {
+ this._log.warn("Attempted to add undefined ID to tracker");
+ return false;
+ }
+
+ if (this.ignoreAll || this._ignored.includes(id)) {
+ return false;
+ }
+
+ // Default to the current time in seconds if no time is provided.
+ if (when == null) {
+ when = this._now();
+ }
+
+ // Add/update the entry if we have a newer time.
+ if ((this.changedIDs[id] || -Infinity) < when) {
+ this._saveChangedID(id, when);
+ }
+
+ return true;
+ },
+
+ removeChangedID: function (id) {
+ if (!id) {
+ this._log.warn("Attempted to remove undefined ID to tracker");
+ return false;
+ }
+ if (this.ignoreAll || this._ignored.includes(id)) {
+ return false;
+ }
+ if (this.changedIDs[id] != null) {
+ this._log.trace("Removing changed ID " + id);
+ delete this.changedIDs[id];
+ this.saveChangedIDs();
+ }
+ return true;
+ },
+
+ clearChangedIDs: function () {
+ this._log.trace("Clearing changed ID list");
+ this.changedIDs = {};
+ this.saveChangedIDs();
+ },
+
+ _now() {
+ return Date.now() / 1000;
+ },
+
+ _isTracking: false,
+
+ // Override these in your subclasses.
+ startTracking: function () {
+ },
+
+ stopTracking: function () {
+ },
+
+ engineIsEnabled: function () {
+ if (!this.engine) {
+ // Can't tell -- we must be running in a test!
+ return true;
+ }
+ return this.engine.enabled;
+ },
+
+ onEngineEnabledChanged: function (engineEnabled) {
+ if (engineEnabled == this._isTracking) {
+ return;
+ }
+
+ if (engineEnabled) {
+ this.startTracking();
+ this._isTracking = true;
+ } else {
+ this.stopTracking();
+ this._isTracking = false;
+ this.clearChangedIDs();
+ }
+ },
+
+ observe: function (subject, topic, data) {
+ switch (topic) {
+ case "weave:engine:start-tracking":
+ if (!this.engineIsEnabled()) {
+ return;
+ }
+ this._log.trace("Got start-tracking.");
+ if (!this._isTracking) {
+ this.startTracking();
+ this._isTracking = true;
+ }
+ return;
+ case "weave:engine:stop-tracking":
+ this._log.trace("Got stop-tracking.");
+ if (this._isTracking) {
+ this.stopTracking();
+ this._isTracking = false;
+ }
+ return;
+ case "nsPref:changed":
+ if (data == PREFS_BRANCH + "engine." + this.engine.prefName) {
+ this.onEngineEnabledChanged(this.engine.enabled);
+ }
+ return;
+ }
+ }
+};
+
+
+
+/**
+ * The Store serves as the interface between Sync and stored data.
+ *
+ * The name "store" is slightly a misnomer because it doesn't actually "store"
+ * anything. Instead, it serves as a gateway to something that actually does
+ * the "storing."
+ *
+ * The store is responsible for record management inside an engine. It tells
+ * Sync what items are available for Sync, converts items to and from Sync's
+ * record format, and applies records from Sync into changes on the underlying
+ * store.
+ *
+ * Store implementations require a number of functions to be implemented. These
+ * are all documented below.
+ *
+ * For stores that deal with many records or which have expensive store access
+ * routines, it is highly recommended to implement a custom applyIncomingBatch
+ * and/or applyIncoming function on top of the basic APIs.
+ */
+
+this.Store = function Store(name, engine) {
+ if (!engine) {
+ throw new Error("Store must be associated with an Engine instance.");
+ }
+
+ name = name || "Unnamed";
+ this.name = name.toLowerCase();
+ this.engine = engine;
+
+ this._log = Log.repository.getLogger("Sync.Store." + name);
+ let level = Svc.Prefs.get("log.logger.engine." + this.name, "Debug");
+ this._log.level = Log.Level[level];
+
+ XPCOMUtils.defineLazyGetter(this, "_timer", function() {
+ return Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
+ });
+}
+Store.prototype = {
+
+ _sleep: function _sleep(delay) {
+ let cb = Async.makeSyncCallback();
+ this._timer.initWithCallback(cb, delay, Ci.nsITimer.TYPE_ONE_SHOT);
+ Async.waitForSyncCallback(cb);
+ },
+
+ /**
+ * Apply multiple incoming records against the store.
+ *
+ * This is called with a set of incoming records to process. The function
+ * should look at each record, reconcile with the current local state, and
+ * make the local changes required to bring its state in alignment with the
+ * record.
+ *
+ * The default implementation simply iterates over all records and calls
+ * applyIncoming(). Store implementations may overwrite this function
+ * if desired.
+ *
+ * @param records Array of records to apply
+ * @return Array of record IDs which did not apply cleanly
+ */
+ applyIncomingBatch: function (records) {
+ let failed = [];
+ for (let record of records) {
+ try {
+ this.applyIncoming(record);
+ } catch (ex) {
+ if (ex.code == Engine.prototype.eEngineAbortApplyIncoming) {
+ // This kind of exception should have a 'cause' attribute, which is an
+ // originating exception.
+ // ex.cause will carry its stack with it when rethrown.
+ throw ex.cause;
+ }
+ if (Async.isShutdownException(ex)) {
+ throw ex;
+ }
+ this._log.warn("Failed to apply incoming record " + record.id, ex);
+ this.engine._noteApplyFailure();
+ failed.push(record.id);
+ }
+ };
+ return failed;
+ },
+
+ /**
+ * Apply a single record against the store.
+ *
+ * This takes a single record and makes the local changes required so the
+ * local state matches what's in the record.
+ *
+ * The default implementation calls one of remove(), create(), or update()
+ * depending on the state obtained from the store itself. Store
+ * implementations may overwrite this function if desired.
+ *
+ * @param record
+ * Record to apply
+ */
+ applyIncoming: function (record) {
+ if (record.deleted)
+ this.remove(record);
+ else if (!this.itemExists(record.id))
+ this.create(record);
+ else
+ this.update(record);
+ },
+
+ // override these in derived objects
+
+ /**
+ * Create an item in the store from a record.
+ *
+ * This is called by the default implementation of applyIncoming(). If using
+ * applyIncomingBatch(), this won't be called unless your store calls it.
+ *
+ * @param record
+ * The store record to create an item from
+ */
+ create: function (record) {
+ throw "override create in a subclass";
+ },
+
+ /**
+ * Remove an item in the store from a record.
+ *
+ * This is called by the default implementation of applyIncoming(). If using
+ * applyIncomingBatch(), this won't be called unless your store calls it.
+ *
+ * @param record
+ * The store record to delete an item from
+ */
+ remove: function (record) {
+ throw "override remove in a subclass";
+ },
+
+ /**
+ * Update an item from a record.
+ *
+ * This is called by the default implementation of applyIncoming(). If using
+ * applyIncomingBatch(), this won't be called unless your store calls it.
+ *
+ * @param record
+ * The record to use to update an item from
+ */
+ update: function (record) {
+ throw "override update in a subclass";
+ },
+
+ /**
+ * Determine whether a record with the specified ID exists.
+ *
+ * Takes a string record ID and returns a booleans saying whether the record
+ * exists.
+ *
+ * @param id
+ * string record ID
+ * @return boolean indicating whether record exists locally
+ */
+ itemExists: function (id) {
+ throw "override itemExists in a subclass";
+ },
+
+ /**
+ * Create a record from the specified ID.
+ *
+ * If the ID is known, the record should be populated with metadata from
+ * the store. If the ID is not known, the record should be created with the
+ * delete field set to true.
+ *
+ * @param id
+ * string record ID
+ * @param collection
+ * Collection to add record to. This is typically passed into the
+ * constructor for the newly-created record.
+ * @return record type for this engine
+ */
+ createRecord: function (id, collection) {
+ throw "override createRecord in a subclass";
+ },
+
+ /**
+ * Change the ID of a record.
+ *
+ * @param oldID
+ * string old/current record ID
+ * @param newID
+ * string new record ID
+ */
+ changeItemID: function (oldID, newID) {
+ throw "override changeItemID in a subclass";
+ },
+
+ /**
+ * Obtain the set of all known record IDs.
+ *
+ * @return Object with ID strings as keys and values of true. The values
+ * are ignored.
+ */
+ getAllIDs: function () {
+ throw "override getAllIDs in a subclass";
+ },
+
+ /**
+ * Wipe all data in the store.
+ *
+ * This function is called during remote wipes or when replacing local data
+ * with remote data.
+ *
+ * This function should delete all local data that the store is managing. It
+ * can be thought of as clearing out all state and restoring the "new
+ * browser" state.
+ */
+ wipe: function () {
+ throw "override wipe in a subclass";
+ }
+};
+
+this.EngineManager = function EngineManager(service) {
+ this.service = service;
+
+ this._engines = {};
+
+ // This will be populated by Service on startup.
+ this._declined = new Set();
+ this._log = Log.repository.getLogger("Sync.EngineManager");
+ this._log.level = Log.Level[Svc.Prefs.get("log.logger.service.engines", "Debug")];
+}
+EngineManager.prototype = {
+ get: function (name) {
+ // Return an array of engines if we have an array of names
+ if (Array.isArray(name)) {
+ let engines = [];
+ name.forEach(function(name) {
+ let engine = this.get(name);
+ if (engine) {
+ engines.push(engine);
+ }
+ }, this);
+ return engines;
+ }
+
+ let engine = this._engines[name];
+ if (!engine) {
+ this._log.debug("Could not get engine: " + name);
+ if (Object.keys) {
+ this._log.debug("Engines are: " + JSON.stringify(Object.keys(this._engines)));
+ }
+ }
+ return engine;
+ },
+
+ getAll: function () {
+ let engines = [];
+ for (let [, engine] of Object.entries(this._engines)) {
+ engines.push(engine);
+ }
+ return engines;
+ },
+
+ /**
+ * N.B., does not pay attention to the declined list.
+ */
+ getEnabled: function () {
+ return this.getAll()
+ .filter((engine) => engine.enabled)
+ .sort((a, b) => a.syncPriority - b.syncPriority);
+ },
+
+ get enabledEngineNames() {
+ return this.getEnabled().map(e => e.name);
+ },
+
+ persistDeclined: function () {
+ Svc.Prefs.set("declinedEngines", [...this._declined].join(","));
+ },
+
+ /**
+ * Returns an array.
+ */
+ getDeclined: function () {
+ return [...this._declined];
+ },
+
+ setDeclined: function (engines) {
+ this._declined = new Set(engines);
+ this.persistDeclined();
+ },
+
+ isDeclined: function (engineName) {
+ return this._declined.has(engineName);
+ },
+
+ /**
+ * Accepts a Set or an array.
+ */
+ decline: function (engines) {
+ for (let e of engines) {
+ this._declined.add(e);
+ }
+ this.persistDeclined();
+ },
+
+ undecline: function (engines) {
+ for (let e of engines) {
+ this._declined.delete(e);
+ }
+ this.persistDeclined();
+ },
+
+ /**
+ * Mark any non-enabled engines as declined.
+ *
+ * This is useful after initial customization during setup.
+ */
+ declineDisabled: function () {
+ for (let e of this.getAll()) {
+ if (!e.enabled) {
+ this._log.debug("Declining disabled engine " + e.name);
+ this._declined.add(e.name);
+ }
+ }
+ this.persistDeclined();
+ },
+
+ /**
+ * Register an Engine to the service. Alternatively, give an array of engine
+ * objects to register.
+ *
+ * @param engineObject
+ * Engine object used to get an instance of the engine
+ * @return The engine object if anything failed
+ */
+ register: function (engineObject) {
+ if (Array.isArray(engineObject)) {
+ return engineObject.map(this.register, this);
+ }
+
+ try {
+ let engine = new engineObject(this.service);
+ let name = engine.name;
+ if (name in this._engines) {
+ this._log.error("Engine '" + name + "' is already registered!");
+ } else {
+ this._engines[name] = engine;
+ }
+ } catch (ex) {
+ let name = engineObject || "";
+ name = name.prototype || "";
+ name = name.name || "";
+
+ this._log.error(`Could not initialize engine ${name}`, ex);
+ return engineObject;
+ }
+ },
+
+ unregister: function (val) {
+ let name = val;
+ if (val instanceof Engine) {
+ name = val.name;
+ }
+ delete this._engines[name];
+ },
+
+ clear: function () {
+ for (let name in this._engines) {
+ delete this._engines[name];
+ }
+ },
+};
+
+this.Engine = function Engine(name, service) {
+ if (!service) {
+ throw new Error("Engine must be associated with a Service instance.");
+ }
+
+ this.Name = name || "Unnamed";
+ this.name = name.toLowerCase();
+ this.service = service;
+
+ this._notify = Utils.notify("weave:engine:");
+ this._log = Log.repository.getLogger("Sync.Engine." + this.Name);
+ let level = Svc.Prefs.get("log.logger.engine." + this.name, "Debug");
+ this._log.level = Log.Level[level];
+
+ this._tracker; // initialize tracker to load previously changed IDs
+ this._log.debug("Engine initialized");
+}
+Engine.prototype = {
+ // _storeObj, and _trackerObj should to be overridden in subclasses
+ _storeObj: Store,
+ _trackerObj: Tracker,
+
+ // Local 'constant'.
+ // Signal to the engine that processing further records is pointless.
+ eEngineAbortApplyIncoming: "error.engine.abort.applyincoming",
+
+ // Should we keep syncing if we find a record that cannot be uploaded (ever)?
+ // If this is false, we'll throw, otherwise, we'll ignore the record and
+ // continue. This currently can only happen due to the record being larger
+ // than the record upload limit.
+ allowSkippedRecord: true,
+
+ get prefName() {
+ return this.name;
+ },
+
+ get enabled() {
+ return Svc.Prefs.get("engine." + this.prefName, false);
+ },
+
+ set enabled(val) {
+ Svc.Prefs.set("engine." + this.prefName, !!val);
+ },
+
+ get score() {
+ return this._tracker.score;
+ },
+
+ get _store() {
+ let store = new this._storeObj(this.Name, this);
+ this.__defineGetter__("_store", () => store);
+ return store;
+ },
+
+ get _tracker() {
+ let tracker = new this._trackerObj(this.Name, this);
+ this.__defineGetter__("_tracker", () => tracker);
+ return tracker;
+ },
+
+ sync: function () {
+ if (!this.enabled) {
+ return;
+ }
+
+ if (!this._sync) {
+ throw "engine does not implement _sync method";
+ }
+
+ this._notify("sync", this.name, this._sync)();
+ },
+
+ /**
+ * Get rid of any local meta-data.
+ */
+ resetClient: function () {
+ if (!this._resetClient) {
+ throw "engine does not implement _resetClient method";
+ }
+
+ this._notify("reset-client", this.name, this._resetClient)();
+ },
+
+ _wipeClient: function () {
+ this.resetClient();
+ this._log.debug("Deleting all local data");
+ this._tracker.ignoreAll = true;
+ this._store.wipe();
+ this._tracker.ignoreAll = false;
+ this._tracker.clearChangedIDs();
+ },
+
+ wipeClient: function () {
+ this._notify("wipe-client", this.name, this._wipeClient)();
+ },
+
+ /**
+ * If one exists, initialize and return a validator for this engine (which
+ * must have a `validate(engine)` method that returns a promise to an object
+ * with a getSummary method). Otherwise return null.
+ */
+ getValidator: function () {
+ return null;
+ }
+};
+
+this.SyncEngine = function SyncEngine(name, service) {
+ Engine.call(this, name || "SyncEngine", service);
+
+ this.loadToFetch();
+ this.loadPreviousFailed();
+}
+
+// Enumeration to define approaches to handling bad records.
+// Attached to the constructor to allow use as a kind of static enumeration.
+SyncEngine.kRecoveryStrategy = {
+ ignore: "ignore",
+ retry: "retry",
+ error: "error"
+};
+
+SyncEngine.prototype = {
+ __proto__: Engine.prototype,
+ _recordObj: CryptoWrapper,
+ version: 1,
+
+ // Which sortindex to use when retrieving records for this engine.
+ _defaultSort: undefined,
+
+ // A relative priority to use when computing an order
+ // for engines to be synced. Higher-priority engines
+ // (lower numbers) are synced first.
+ // It is recommended that a unique value be used for each engine,
+ // in order to guarantee a stable sequence.
+ syncPriority: 0,
+
+ // How many records to pull in a single sync. This is primarily to avoid very
+ // long first syncs against profiles with many history records.
+ downloadLimit: null,
+
+ // How many records to pull at one time when specifying IDs. This is to avoid
+ // URI length limitations.
+ guidFetchBatchSize: DEFAULT_GUID_FETCH_BATCH_SIZE,
+ mobileGUIDFetchBatchSize: DEFAULT_MOBILE_GUID_FETCH_BATCH_SIZE,
+
+ // How many records to process in a single batch.
+ applyIncomingBatchSize: DEFAULT_STORE_BATCH_SIZE,
+
+ get storageURL() {
+ return this.service.storageURL;
+ },
+
+ get engineURL() {
+ return this.storageURL + this.name;
+ },
+
+ get cryptoKeysURL() {
+ return this.storageURL + "crypto/keys";
+ },
+
+ get metaURL() {
+ return this.storageURL + "meta/global";
+ },
+
+ get syncID() {
+ // Generate a random syncID if we don't have one
+ let syncID = Svc.Prefs.get(this.name + ".syncID", "");
+ return syncID == "" ? this.syncID = Utils.makeGUID() : syncID;
+ },
+ set syncID(value) {
+ Svc.Prefs.set(this.name + ".syncID", value);
+ },
+
+ /*
+ * lastSync is a timestamp in server time.
+ */
+ get lastSync() {
+ return parseFloat(Svc.Prefs.get(this.name + ".lastSync", "0"));
+ },
+ set lastSync(value) {
+ // Reset the pref in-case it's a number instead of a string
+ Svc.Prefs.reset(this.name + ".lastSync");
+ // Store the value as a string to keep floating point precision
+ Svc.Prefs.set(this.name + ".lastSync", value.toString());
+ },
+ resetLastSync: function () {
+ this._log.debug("Resetting " + this.name + " last sync time");
+ Svc.Prefs.reset(this.name + ".lastSync");
+ Svc.Prefs.set(this.name + ".lastSync", "0");
+ this.lastSyncLocal = 0;
+ },
+
+ get toFetch() {
+ return this._toFetch;
+ },
+ set toFetch(val) {
+ let cb = (error) => {
+ if (error) {
+ this._log.error("Failed to read JSON records to fetch", error);
+ }
+ }
+ // Coerce the array to a string for more efficient comparison.
+ if (val + "" == this._toFetch) {
+ return;
+ }
+ this._toFetch = val;
+ Utils.namedTimer(function () {
+ Utils.jsonSave("toFetch/" + this.name, this, val, cb);
+ }, 0, this, "_toFetchDelay");
+ },
+
+ loadToFetch: function () {
+ // Initialize to empty if there's no file.
+ this._toFetch = [];
+ Utils.jsonLoad("toFetch/" + this.name, this, function(toFetch) {
+ if (toFetch) {
+ this._toFetch = toFetch;
+ }
+ });
+ },
+
+ get previousFailed() {
+ return this._previousFailed;
+ },
+ set previousFailed(val) {
+ let cb = (error) => {
+ if (error) {
+ this._log.error("Failed to set previousFailed", error);
+ } else {
+ this._log.debug("Successfully wrote previousFailed.");
+ }
+ }
+ // Coerce the array to a string for more efficient comparison.
+ if (val + "" == this._previousFailed) {
+ return;
+ }
+ this._previousFailed = val;
+ Utils.namedTimer(function () {
+ Utils.jsonSave("failed/" + this.name, this, val, cb);
+ }, 0, this, "_previousFailedDelay");
+ },
+
+ loadPreviousFailed: function () {
+ // Initialize to empty if there's no file
+ this._previousFailed = [];
+ Utils.jsonLoad("failed/" + this.name, this, function(previousFailed) {
+ if (previousFailed) {
+ this._previousFailed = previousFailed;
+ }
+ });
+ },
+
+ /*
+ * lastSyncLocal is a timestamp in local time.
+ */
+ get lastSyncLocal() {
+ return parseInt(Svc.Prefs.get(this.name + ".lastSyncLocal", "0"), 10);
+ },
+ set lastSyncLocal(value) {
+ // Store as a string because pref can only store C longs as numbers.
+ Svc.Prefs.set(this.name + ".lastSyncLocal", value.toString());
+ },
+
+ /*
+ * Returns a changeset for this sync. Engine implementations can override this
+ * method to bypass the tracker for certain or all changed items.
+ */
+ getChangedIDs: function () {
+ return this._tracker.changedIDs;
+ },
+
+ // Create a new record using the store and add in crypto fields.
+ _createRecord: function (id) {
+ let record = this._store.createRecord(id, this.name);
+ record.id = id;
+ record.collection = this.name;
+ return record;
+ },
+
+ // Any setup that needs to happen at the beginning of each sync.
+ _syncStartup: function () {
+
+ // Determine if we need to wipe on outdated versions
+ let metaGlobal = this.service.recordManager.get(this.metaURL);
+ let engines = metaGlobal.payload.engines || {};
+ let engineData = engines[this.name] || {};
+
+ let needsWipe = false;
+
+ // Assume missing versions are 0 and wipe the server
+ if ((engineData.version || 0) < this.version) {
+ this._log.debug("Old engine data: " + [engineData.version, this.version]);
+
+ // Prepare to clear the server and upload everything
+ needsWipe = true;
+ this.syncID = "";
+
+ // Set the newer version and newly generated syncID
+ engineData.version = this.version;
+ engineData.syncID = this.syncID;
+
+ // Put the new data back into meta/global and mark for upload
+ engines[this.name] = engineData;
+ metaGlobal.payload.engines = engines;
+ metaGlobal.changed = true;
+ }
+ // Don't sync this engine if the server has newer data
+ else if (engineData.version > this.version) {
+ let error = new String("New data: " + [engineData.version, this.version]);
+ error.failureCode = VERSION_OUT_OF_DATE;
+ throw error;
+ }
+ // Changes to syncID mean we'll need to upload everything
+ else if (engineData.syncID != this.syncID) {
+ this._log.debug("Engine syncIDs: " + [engineData.syncID, this.syncID]);
+ this.syncID = engineData.syncID;
+ this._resetClient();
+ };
+
+ // Delete any existing data and reupload on bad version or missing meta.
+ // No crypto component here...? We could regenerate per-collection keys...
+ if (needsWipe) {
+ this.wipeServer();
+ }
+
+ // Save objects that need to be uploaded in this._modified. We also save
+ // the timestamp of this fetch in this.lastSyncLocal. As we successfully
+ // upload objects we remove them from this._modified. If an error occurs
+ // or any objects fail to upload, they will remain in this._modified. At
+ // the end of a sync, or after an error, we add all objects remaining in
+ // this._modified to the tracker.
+ this.lastSyncLocal = Date.now();
+ if (this.lastSync) {
+ this._modified = this.pullNewChanges();
+ } else {
+ this._log.debug("First sync, uploading all items");
+ this._modified = this.pullAllChanges();
+ }
+ // Clear the tracker now. If the sync fails we'll add the ones we failed
+ // to upload back.
+ this._tracker.clearChangedIDs();
+
+ this._log.info(this._modified.count() +
+ " outgoing items pre-reconciliation");
+
+ // Keep track of what to delete at the end of sync
+ this._delete = {};
+ },
+
+ /**
+ * A tiny abstraction to make it easier to test incoming record
+ * application.
+ */
+ itemSource: function () {
+ return new Collection(this.engineURL, this._recordObj, this.service);
+ },
+
+ /**
+ * Process incoming records.
+ * In the most awful and untestable way possible.
+ * This now accepts something that makes testing vaguely less impossible.
+ */
+ _processIncoming: function (newitems) {
+ this._log.trace("Downloading & applying server changes");
+
+ // Figure out how many total items to fetch this sync; do less on mobile.
+ let batchSize = this.downloadLimit || Infinity;
+ let isMobile = (Svc.Prefs.get("client.type") == "mobile");
+
+ if (!newitems) {
+ newitems = this.itemSource();
+ }
+
+ if (this._defaultSort) {
+ newitems.sort = this._defaultSort;
+ }
+
+ if (isMobile) {
+ batchSize = MOBILE_BATCH_SIZE;
+ }
+ newitems.newer = this.lastSync;
+ newitems.full = true;
+ newitems.limit = batchSize;
+
+ // applied => number of items that should be applied.
+ // failed => number of items that failed in this sync.
+ // newFailed => number of items that failed for the first time in this sync.
+ // reconciled => number of items that were reconciled.
+ let count = {applied: 0, failed: 0, newFailed: 0, reconciled: 0};
+ let handled = [];
+ let applyBatch = [];
+ let failed = [];
+ let failedInPreviousSync = this.previousFailed;
+ let fetchBatch = Utils.arrayUnion(this.toFetch, failedInPreviousSync);
+ // Reset previousFailed for each sync since previously failed items may not fail again.
+ this.previousFailed = [];
+
+ // Used (via exceptions) to allow the record handler/reconciliation/etc.
+ // methods to signal that they would like processing of incoming records to
+ // cease.
+ let aborting = undefined;
+
+ function doApplyBatch() {
+ this._tracker.ignoreAll = true;
+ try {
+ failed = failed.concat(this._store.applyIncomingBatch(applyBatch));
+ } catch (ex) {
+ if (Async.isShutdownException(ex)) {
+ throw ex;
+ }
+ // Catch any error that escapes from applyIncomingBatch. At present
+ // those will all be abort events.
+ this._log.warn("Got exception, aborting processIncoming", ex);
+ aborting = ex;
+ }
+ this._tracker.ignoreAll = false;
+ applyBatch = [];
+ }
+
+ function doApplyBatchAndPersistFailed() {
+ // Apply remaining batch.
+ if (applyBatch.length) {
+ doApplyBatch.call(this);
+ }
+ // Persist failed items so we refetch them.
+ if (failed.length) {
+ this.previousFailed = Utils.arrayUnion(failed, this.previousFailed);
+ count.failed += failed.length;
+ this._log.debug("Records that failed to apply: " + failed);
+ failed = [];
+ }
+ }
+
+ let key = this.service.collectionKeys.keyForCollection(this.name);
+
+ // Not binding this method to 'this' for performance reasons. It gets
+ // called for every incoming record.
+ let self = this;
+
+ newitems.recordHandler = function(item) {
+ if (aborting) {
+ return;
+ }
+
+ // Grab a later last modified if possible
+ if (self.lastModified == null || item.modified > self.lastModified)
+ self.lastModified = item.modified;
+
+ // Track the collection for the WBO.
+ item.collection = self.name;
+
+ // Remember which records were processed
+ handled.push(item.id);
+
+ try {
+ try {
+ item.decrypt(key);
+ } catch (ex) {
+ if (!Utils.isHMACMismatch(ex)) {
+ throw ex;
+ }
+ let strategy = self.handleHMACMismatch(item, true);
+ if (strategy == SyncEngine.kRecoveryStrategy.retry) {
+ // You only get one retry.
+ try {
+ // Try decrypting again, typically because we've got new keys.
+ self._log.info("Trying decrypt again...");
+ key = self.service.collectionKeys.keyForCollection(self.name);
+ item.decrypt(key);
+ strategy = null;
+ } catch (ex) {
+ if (!Utils.isHMACMismatch(ex)) {
+ throw ex;
+ }
+ strategy = self.handleHMACMismatch(item, false);
+ }
+ }
+
+ switch (strategy) {
+ case null:
+ // Retry succeeded! No further handling.
+ break;
+ case SyncEngine.kRecoveryStrategy.retry:
+ self._log.debug("Ignoring second retry suggestion.");
+ // Fall through to error case.
+ case SyncEngine.kRecoveryStrategy.error:
+ self._log.warn("Error decrypting record", ex);
+ self._noteApplyFailure();
+ failed.push(item.id);
+ return;
+ case SyncEngine.kRecoveryStrategy.ignore:
+ self._log.debug("Ignoring record " + item.id +
+ " with bad HMAC: already handled.");
+ return;
+ }
+ }
+ } catch (ex) {
+ if (Async.isShutdownException(ex)) {
+ throw ex;
+ }
+ self._log.warn("Error decrypting record", ex);
+ self._noteApplyFailure();
+ failed.push(item.id);
+ return;
+ }
+
+ let shouldApply;
+ try {
+ shouldApply = self._reconcile(item);
+ } catch (ex) {
+ if (ex.code == Engine.prototype.eEngineAbortApplyIncoming) {
+ self._log.warn("Reconciliation failed: aborting incoming processing.");
+ self._noteApplyFailure();
+ failed.push(item.id);
+ aborting = ex.cause;
+ } else if (!Async.isShutdownException(ex)) {
+ self._log.warn("Failed to reconcile incoming record " + item.id, ex);
+ self._noteApplyFailure();
+ failed.push(item.id);
+ return;
+ } else {
+ throw ex;
+ }
+ }
+
+ if (shouldApply) {
+ count.applied++;
+ applyBatch.push(item);
+ } else {
+ count.reconciled++;
+ self._log.trace("Skipping reconciled incoming item " + item.id);
+ }
+
+ if (applyBatch.length == self.applyIncomingBatchSize) {
+ doApplyBatch.call(self);
+ }
+ self._store._sleep(0);
+ };
+
+ // Only bother getting data from the server if there's new things
+ if (this.lastModified == null || this.lastModified > this.lastSync) {
+ let resp = newitems.getBatched();
+ doApplyBatchAndPersistFailed.call(this);
+ if (!resp.success) {
+ resp.failureCode = ENGINE_DOWNLOAD_FAIL;
+ throw resp;
+ }
+
+ if (aborting) {
+ throw aborting;
+ }
+ }
+
+ // Mobile: check if we got the maximum that we requested; get the rest if so.
+ if (handled.length == newitems.limit) {
+ let guidColl = new Collection(this.engineURL, null, this.service);
+
+ // Sort and limit so that on mobile we only get the last X records.
+ guidColl.limit = this.downloadLimit;
+ guidColl.newer = this.lastSync;
+
+ // index: Orders by the sortindex descending (highest weight first).
+ guidColl.sort = "index";
+
+ let guids = guidColl.get();
+ if (!guids.success)
+ throw guids;
+
+ // Figure out which guids weren't just fetched then remove any guids that
+ // were already waiting and prepend the new ones
+ let extra = Utils.arraySub(guids.obj, handled);
+ if (extra.length > 0) {
+ fetchBatch = Utils.arrayUnion(extra, fetchBatch);
+ this.toFetch = Utils.arrayUnion(extra, this.toFetch);
+ }
+ }
+
+ // Fast-foward the lastSync timestamp since we have stored the
+ // remaining items in toFetch.
+ if (this.lastSync < this.lastModified) {
+ this.lastSync = this.lastModified;
+ }
+
+ // Process any backlog of GUIDs.
+ // At this point we impose an upper limit on the number of items to fetch
+ // in a single request, even for desktop, to avoid hitting URI limits.
+ batchSize = isMobile ? this.mobileGUIDFetchBatchSize :
+ this.guidFetchBatchSize;
+
+ while (fetchBatch.length && !aborting) {
+ // Reuse the original query, but get rid of the restricting params
+ // and batch remaining records.
+ newitems.limit = 0;
+ newitems.newer = 0;
+ newitems.ids = fetchBatch.slice(0, batchSize);
+
+ // Reuse the existing record handler set earlier
+ let resp = newitems.get();
+ if (!resp.success) {
+ resp.failureCode = ENGINE_DOWNLOAD_FAIL;
+ throw resp;
+ }
+
+ // This batch was successfully applied. Not using
+ // doApplyBatchAndPersistFailed() here to avoid writing toFetch twice.
+ fetchBatch = fetchBatch.slice(batchSize);
+ this.toFetch = Utils.arraySub(this.toFetch, newitems.ids);
+ this.previousFailed = Utils.arrayUnion(this.previousFailed, failed);
+ if (failed.length) {
+ count.failed += failed.length;
+ this._log.debug("Records that failed to apply: " + failed);
+ }
+ failed = [];
+
+ if (aborting) {
+ throw aborting;
+ }
+
+ if (this.lastSync < this.lastModified) {
+ this.lastSync = this.lastModified;
+ }
+ }
+
+ // Apply remaining items.
+ doApplyBatchAndPersistFailed.call(this);
+
+ count.newFailed = this.previousFailed.reduce((count, engine) => {
+ if (failedInPreviousSync.indexOf(engine) == -1) {
+ count++;
+ this._noteApplyNewFailure();
+ }
+ return count;
+ }, 0);
+ count.succeeded = Math.max(0, count.applied - count.failed);
+ this._log.info(["Records:",
+ count.applied, "applied,",
+ count.succeeded, "successfully,",
+ count.failed, "failed to apply,",
+ count.newFailed, "newly failed to apply,",
+ count.reconciled, "reconciled."].join(" "));
+ Observers.notify("weave:engine:sync:applied", count, this.name);
+ },
+
+ _noteApplyFailure: function () {
+ // here would be a good place to record telemetry...
+ },
+
+ _noteApplyNewFailure: function () {
+ // here would be a good place to record telemetry...
+ },
+
+ /**
+ * Find a GUID of an item that is a duplicate of the incoming item but happens
+ * to have a different GUID
+ *
+ * @return GUID of the similar item; falsy otherwise
+ */
+ _findDupe: function (item) {
+ // By default, assume there's no dupe items for the engine
+ },
+
+ // Called when the server has a record marked as deleted, but locally we've
+ // changed it more recently than the deletion. If we return false, the
+ // record will be deleted locally. If we return true, we'll reupload the
+ // record to the server -- any extra work that's needed as part of this
+ // process should be done at this point (such as mark the record's parent
+ // for reuploading in the case of bookmarks).
+ _shouldReviveRemotelyDeletedRecord(remoteItem) {
+ return true;
+ },
+
+ _deleteId: function (id) {
+ this._tracker.removeChangedID(id);
+
+ // Remember this id to delete at the end of sync
+ if (this._delete.ids == null)
+ this._delete.ids = [id];
+ else
+ this._delete.ids.push(id);
+ },
+
+ _switchItemToDupe(localDupeGUID, incomingItem) {
+ // The local, duplicate ID is always deleted on the server.
+ this._deleteId(localDupeGUID);
+
+ // We unconditionally change the item's ID in case the engine knows of
+ // an item but doesn't expose it through itemExists. If the API
+ // contract were stronger, this could be changed.
+ this._log.debug("Switching local ID to incoming: " + localDupeGUID + " -> " +
+ incomingItem.id);
+ this._store.changeItemID(localDupeGUID, incomingItem.id);
+ },
+
+ /**
+ * Reconcile incoming record with local state.
+ *
+ * This function essentially determines whether to apply an incoming record.
+ *
+ * @param item
+ * Record from server to be tested for application.
+ * @return boolean
+ * Truthy if incoming record should be applied. False if not.
+ */
+ _reconcile: function (item) {
+ if (this._log.level <= Log.Level.Trace) {
+ this._log.trace("Incoming: " + item);
+ }
+
+ // We start reconciling by collecting a bunch of state. We do this here
+ // because some state may change during the course of this function and we
+ // need to operate on the original values.
+ let existsLocally = this._store.itemExists(item.id);
+ let locallyModified = this._modified.has(item.id);
+
+ // TODO Handle clock drift better. Tracked in bug 721181.
+ let remoteAge = AsyncResource.serverTime - item.modified;
+ let localAge = locallyModified ?
+ (Date.now() / 1000 - this._modified.getModifiedTimestamp(item.id)) : null;
+ let remoteIsNewer = remoteAge < localAge;
+
+ this._log.trace("Reconciling " + item.id + ". exists=" +
+ existsLocally + "; modified=" + locallyModified +
+ "; local age=" + localAge + "; incoming age=" +
+ remoteAge);
+
+ // We handle deletions first so subsequent logic doesn't have to check
+ // deleted flags.
+ if (item.deleted) {
+ // If the item doesn't exist locally, there is nothing for us to do. We
+ // can't check for duplicates because the incoming record has no data
+ // which can be used for duplicate detection.
+ if (!existsLocally) {
+ this._log.trace("Ignoring incoming item because it was deleted and " +
+ "the item does not exist locally.");
+ return false;
+ }
+
+ // We decide whether to process the deletion by comparing the record
+ // ages. If the item is not modified locally, the remote side wins and
+ // the deletion is processed. If it is modified locally, we take the
+ // newer record.
+ if (!locallyModified) {
+ this._log.trace("Applying incoming delete because the local item " +
+ "exists and isn't modified.");
+ return true;
+ }
+ this._log.trace("Incoming record is deleted but we had local changes.");
+
+ if (remoteIsNewer) {
+ this._log.trace("Remote record is newer -- deleting local record.");
+ return true;
+ }
+ // If the local record is newer, we defer to individual engines for
+ // how to handle this. By default, we revive the record.
+ let willRevive = this._shouldReviveRemotelyDeletedRecord(item);
+ this._log.trace("Local record is newer -- reviving? " + willRevive);
+
+ return !willRevive;
+ }
+
+ // At this point the incoming record is not for a deletion and must have
+ // data. If the incoming record does not exist locally, we check for a local
+ // duplicate existing under a different ID. The default implementation of
+ // _findDupe() is empty, so engines have to opt in to this functionality.
+ //
+ // If we find a duplicate, we change the local ID to the incoming ID and we
+ // refresh the metadata collected above. See bug 710448 for the history
+ // of this logic.
+ if (!existsLocally) {
+ let localDupeGUID = this._findDupe(item);
+ if (localDupeGUID) {
+ this._log.trace("Local item " + localDupeGUID + " is a duplicate for " +
+ "incoming item " + item.id);
+
+ // The current API contract does not mandate that the ID returned by
+ // _findDupe() actually exists. Therefore, we have to perform this
+ // check.
+ existsLocally = this._store.itemExists(localDupeGUID);
+
+ // If the local item was modified, we carry its metadata forward so
+ // appropriate reconciling can be performed.
+ if (this._modified.has(localDupeGUID)) {
+ locallyModified = true;
+ localAge = this._tracker._now() - this._modified.getModifiedTimestamp(localDupeGUID);
+ remoteIsNewer = remoteAge < localAge;
+
+ this._modified.swap(localDupeGUID, item.id);
+ } else {
+ locallyModified = false;
+ localAge = null;
+ }
+
+ // Tell the engine to do whatever it needs to switch the items.
+ this._switchItemToDupe(localDupeGUID, item);
+
+ this._log.debug("Local item after duplication: age=" + localAge +
+ "; modified=" + locallyModified + "; exists=" +
+ existsLocally);
+ } else {
+ this._log.trace("No duplicate found for incoming item: " + item.id);
+ }
+ }
+
+ // At this point we've performed duplicate detection. But, nothing here
+ // should depend on duplicate detection as the above should have updated
+ // state seamlessly.
+
+ if (!existsLocally) {
+ // If the item doesn't exist locally and we have no local modifications
+ // to the item (implying that it was not deleted), always apply the remote
+ // item.
+ if (!locallyModified) {
+ this._log.trace("Applying incoming because local item does not exist " +
+ "and was not deleted.");
+ return true;
+ }
+
+ // If the item was modified locally but isn't present, it must have
+ // been deleted. If the incoming record is younger, we restore from
+ // that record.
+ if (remoteIsNewer) {
+ this._log.trace("Applying incoming because local item was deleted " +
+ "before the incoming item was changed.");
+ this._modified.delete(item.id);
+ return true;
+ }
+
+ this._log.trace("Ignoring incoming item because the local item's " +
+ "deletion is newer.");
+ return false;
+ }
+
+ // If the remote and local records are the same, there is nothing to be
+ // done, so we don't do anything. In the ideal world, this logic wouldn't
+ // be here and the engine would take a record and apply it. The reason we
+ // want to defer this logic is because it would avoid a redundant and
+ // possibly expensive dip into the storage layer to query item state.
+ // This should get addressed in the async rewrite, so we ignore it for now.
+ let localRecord = this._createRecord(item.id);
+ let recordsEqual = Utils.deepEquals(item.cleartext,
+ localRecord.cleartext);
+
+ // If the records are the same, we don't need to do anything. This does
+ // potentially throw away a local modification time. But, if the records
+ // are the same, does it matter?
+ if (recordsEqual) {
+ this._log.trace("Ignoring incoming item because the local item is " +
+ "identical.");
+
+ this._modified.delete(item.id);
+ return false;
+ }
+
+ // At this point the records are different.
+
+ // If we have no local modifications, always take the server record.
+ if (!locallyModified) {
+ this._log.trace("Applying incoming record because no local conflicts.");
+ return true;
+ }
+
+ // At this point, records are different and the local record is modified.
+ // We resolve conflicts by record age, where the newest one wins. This does
+ // result in data loss and should be handled by giving the engine an
+ // opportunity to merge the records. Bug 720592 tracks this feature.
+ this._log.warn("DATA LOSS: Both local and remote changes to record: " +
+ item.id);
+ return remoteIsNewer;
+ },
+
+ // Upload outgoing records.
+ _uploadOutgoing: function () {
+ this._log.trace("Uploading local changes to server.");
+
+ let modifiedIDs = this._modified.ids();
+ if (modifiedIDs.length) {
+ this._log.trace("Preparing " + modifiedIDs.length +
+ " outgoing records");
+
+ let counts = { sent: modifiedIDs.length, failed: 0 };
+
+ // collection we'll upload
+ let up = new Collection(this.engineURL, null, this.service);
+
+ let failed = [];
+ let successful = [];
+ let handleResponse = (resp, batchOngoing = false) => {
+ // Note: We don't want to update this.lastSync, or this._modified until
+ // the batch is complete, however we want to remember success/failure
+ // indicators for when that happens.
+ if (!resp.success) {
+ this._log.debug("Uploading records failed: " + resp);
+ resp.failureCode = resp.status == 412 ? ENGINE_BATCH_INTERRUPTED : ENGINE_UPLOAD_FAIL;
+ throw resp;
+ }
+
+ // Update server timestamp from the upload.
+ failed = failed.concat(Object.keys(resp.obj.failed));
+ successful = successful.concat(resp.obj.success);
+
+ if (batchOngoing) {
+ // Nothing to do yet
+ return;
+ }
+ // Advance lastSync since we've finished the batch.
+ let modified = resp.headers["x-weave-timestamp"];
+ if (modified > this.lastSync) {
+ this.lastSync = modified;
+ }
+ if (failed.length && this._log.level <= Log.Level.Debug) {
+ this._log.debug("Records that will be uploaded again because "
+ + "the server couldn't store them: "
+ + failed.join(", "));
+ }
+
+ counts.failed += failed.length;
+
+ for (let id of successful) {
+ this._modified.delete(id);
+ }
+
+ this._onRecordsWritten(successful, failed);
+
+ // clear for next batch
+ failed.length = 0;
+ successful.length = 0;
+ };
+
+ let postQueue = up.newPostQueue(this._log, this.lastSync, handleResponse);
+
+ for (let id of modifiedIDs) {
+ let out;
+ let ok = false;
+ try {
+ out = this._createRecord(id);
+ if (this._log.level <= Log.Level.Trace)
+ this._log.trace("Outgoing: " + out);
+
+ out.encrypt(this.service.collectionKeys.keyForCollection(this.name));
+ ok = true;
+ } catch (ex) {
+ if (Async.isShutdownException(ex)) {
+ throw ex;
+ }
+ this._log.warn("Error creating record", ex);
+ }
+ if (ok) {
+ let { enqueued, error } = postQueue.enqueue(out);
+ if (!enqueued) {
+ ++counts.failed;
+ if (!this.allowSkippedRecord) {
+ throw error;
+ }
+ }
+ }
+ this._store._sleep(0);
+ }
+ postQueue.flush(true);
+ Observers.notify("weave:engine:sync:uploaded", counts, this.name);
+ }
+ },
+
+ _onRecordsWritten(succeeded, failed) {
+ // Implement this method to take specific actions against successfully
+ // uploaded records and failed records.
+ },
+
+ // Any cleanup necessary.
+ // Save the current snapshot so as to calculate changes at next sync
+ _syncFinish: function () {
+ this._log.trace("Finishing up sync");
+ this._tracker.resetScore();
+
+ let doDelete = Utils.bind2(this, function(key, val) {
+ let coll = new Collection(this.engineURL, this._recordObj, this.service);
+ coll[key] = val;
+ coll.delete();
+ });
+
+ for (let [key, val] of Object.entries(this._delete)) {
+ // Remove the key for future uses
+ delete this._delete[key];
+
+ // Send a simple delete for the property
+ if (key != "ids" || val.length <= 100)
+ doDelete(key, val);
+ else {
+ // For many ids, split into chunks of at most 100
+ while (val.length > 0) {
+ doDelete(key, val.slice(0, 100));
+ val = val.slice(100);
+ }
+ }
+ }
+ },
+
+ _syncCleanup: function () {
+ if (!this._modified) {
+ return;
+ }
+
+ // Mark failed WBOs as changed again so they are reuploaded next time.
+ this.trackRemainingChanges();
+ this._modified.clear();
+ },
+
+ _sync: function () {
+ try {
+ this._syncStartup();
+ Observers.notify("weave:engine:sync:status", "process-incoming");
+ this._processIncoming();
+ Observers.notify("weave:engine:sync:status", "upload-outgoing");
+ this._uploadOutgoing();
+ this._syncFinish();
+ } finally {
+ this._syncCleanup();
+ }
+ },
+
+ canDecrypt: function () {
+ // Report failure even if there's nothing to decrypt
+ let canDecrypt = false;
+
+ // Fetch the most recently uploaded record and try to decrypt it
+ let test = new Collection(this.engineURL, this._recordObj, this.service);
+ test.limit = 1;
+ test.sort = "newest";
+ test.full = true;
+
+ let key = this.service.collectionKeys.keyForCollection(this.name);
+ test.recordHandler = function recordHandler(record) {
+ record.decrypt(key);
+ canDecrypt = true;
+ }.bind(this);
+
+ // Any failure fetching/decrypting will just result in false
+ try {
+ this._log.trace("Trying to decrypt a record from the server..");
+ test.get();
+ } catch (ex) {
+ if (Async.isShutdownException(ex)) {
+ throw ex;
+ }
+ this._log.debug("Failed test decrypt", ex);
+ }
+
+ return canDecrypt;
+ },
+
+ _resetClient: function () {
+ this.resetLastSync();
+ this.previousFailed = [];
+ this.toFetch = [];
+ },
+
+ wipeServer: function () {
+ let response = this.service.resource(this.engineURL).delete();
+ if (response.status != 200 && response.status != 404) {
+ throw response;
+ }
+ this._resetClient();
+ },
+
+ removeClientData: function () {
+ // Implement this method in engines that store client specific data
+ // on the server.
+ },
+
+ /*
+ * Decide on (and partially effect) an error-handling strategy.
+ *
+ * Asks the Service to respond to an HMAC error, which might result in keys
+ * being downloaded. That call returns true if an action which might allow a
+ * retry to occur.
+ *
+ * If `mayRetry` is truthy, and the Service suggests a retry,
+ * handleHMACMismatch returns kRecoveryStrategy.retry. Otherwise, it returns
+ * kRecoveryStrategy.error.
+ *
+ * Subclasses of SyncEngine can override this method to allow for different
+ * behavior -- e.g., to delete and ignore erroneous entries.
+ *
+ * All return values will be part of the kRecoveryStrategy enumeration.
+ */
+ handleHMACMismatch: function (item, mayRetry) {
+ // By default we either try again, or bail out noisily.
+ return (this.service.handleHMACEvent() && mayRetry) ?
+ SyncEngine.kRecoveryStrategy.retry :
+ SyncEngine.kRecoveryStrategy.error;
+ },
+
+ /**
+ * Returns a changeset containing all items in the store. The default
+ * implementation returns a changeset with timestamps from long ago, to
+ * ensure we always use the remote version if one exists.
+ *
+ * This function is only called for the first sync. Subsequent syncs call
+ * `pullNewChanges`.
+ *
+ * @return A `Changeset` object.
+ */
+ pullAllChanges() {
+ let changeset = new Changeset();
+ for (let id in this._store.getAllIDs()) {
+ changeset.set(id, 0);
+ }
+ return changeset;
+ },
+
+ /*
+ * Returns a changeset containing entries for all currently tracked items.
+ * The default implementation returns a changeset with timestamps indicating
+ * when the item was added to the tracker.
+ *
+ * @return A `Changeset` object.
+ */
+ pullNewChanges() {
+ return new Changeset(this.getChangedIDs());
+ },
+
+ /**
+ * Adds all remaining changeset entries back to the tracker, typically for
+ * items that failed to upload. This method is called at the end of each sync.
+ *
+ */
+ trackRemainingChanges() {
+ for (let [id, change] of this._modified.entries()) {
+ this._tracker.addChangedID(id, change);
+ }
+ },
+};
+
+/**
+ * A changeset is created for each sync in `Engine::get{Changed, All}IDs`,
+ * and stores opaque change data for tracked IDs. The default implementation
+ * only records timestamps, though engines can extend this to store additional
+ * data for each entry.
+ */
+class Changeset {
+ // Creates a changeset with an initial set of tracked entries.
+ constructor(changes = {}) {
+ this.changes = changes;
+ }
+
+ // Returns the last modified time, in seconds, for an entry in the changeset.
+ // `id` is guaranteed to be in the set.
+ getModifiedTimestamp(id) {
+ return this.changes[id];
+ }
+
+ // Adds a change for a tracked ID to the changeset.
+ set(id, change) {
+ this.changes[id] = change;
+ }
+
+ // Indicates whether an entry is in the changeset.
+ has(id) {
+ return id in this.changes;
+ }
+
+ // Deletes an entry from the changeset. Used to clean up entries for
+ // reconciled and successfully uploaded records.
+ delete(id) {
+ delete this.changes[id];
+ }
+
+ // Swaps two entries in the changeset. Used when reconciling duplicates that
+ // have local changes.
+ swap(oldID, newID) {
+ this.changes[newID] = this.changes[oldID];
+ delete this.changes[oldID];
+ }
+
+ // Returns an array of all tracked IDs in this changeset.
+ ids() {
+ return Object.keys(this.changes);
+ }
+
+ // Returns an array of `[id, change]` tuples. Used to repopulate the tracker
+ // with entries for failed uploads at the end of a sync.
+ entries() {
+ return Object.entries(this.changes);
+ }
+
+ // Returns the number of entries in this changeset.
+ count() {
+ return this.ids().length;
+ }
+
+ // Clears the changeset.
+ clear() {
+ this.changes = {};
+ }
+}