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Diffstat (limited to 'services/sync/modules/engines.js')
| -rw-r--r-- | services/sync/modules/engines.js | 2280 |
1 files changed, 2280 insertions, 0 deletions
diff --git a/services/sync/modules/engines.js b/services/sync/modules/engines.js new file mode 100644 index 0000000000..3fb54f534a --- /dev/null +++ b/services/sync/modules/engines.js @@ -0,0 +1,2280 @@ +/* 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/. */ + +var EXPORTED_SYMBOLS = [ + "EngineManager", + "SyncEngine", + "Tracker", + "LegacyTracker", + "Store", + "Changeset", +]; + +const { XPCOMUtils } = ChromeUtils.import( + "resource://gre/modules/XPCOMUtils.jsm" +); +const { JSONFile } = ChromeUtils.import("resource://gre/modules/JSONFile.jsm"); +const { Log } = ChromeUtils.import("resource://gre/modules/Log.jsm"); +const { Async } = ChromeUtils.import("resource://services-common/async.js"); +const { Observers } = ChromeUtils.import( + "resource://services-common/observers.js" +); +const { + DEFAULT_DOWNLOAD_BATCH_SIZE, + DEFAULT_GUID_FETCH_BATCH_SIZE, + ENGINE_BATCH_INTERRUPTED, + ENGINE_DOWNLOAD_FAIL, + ENGINE_UPLOAD_FAIL, + VERSION_OUT_OF_DATE, +} = ChromeUtils.import("resource://services-sync/constants.js"); +const { Collection, CryptoWrapper } = ChromeUtils.import( + "resource://services-sync/record.js" +); +const { Resource } = ChromeUtils.import("resource://services-sync/resource.js"); +const { SerializableSet, Svc, Utils } = ChromeUtils.import( + "resource://services-sync/util.js" +); + +XPCOMUtils.defineLazyModuleGetters(this, { + fxAccounts: "resource://gre/modules/FxAccounts.jsm", + OS: "resource://gre/modules/osfile.jsm", + PlacesUtils: "resource://gre/modules/PlacesUtils.jsm", +}); + +function ensureDirectory(path) { + let basename = OS.Path.dirname(path); + return OS.File.makeDir(basename, { from: OS.Constants.Path.profileDir }); +} + +/** + * Trackers are associated with a single engine and deal with + * listening for changes to their particular data type. + * + * The base `Tracker` only supports listening for changes, and bumping the score + * to indicate how urgently the engine wants to sync. It does not persist any + * data. Engines that track changes directly in the storage layer (like + * bookmarks, bridged engines, addresses, and credit cards) or only upload a + * single record (tabs and preferences) should subclass `Tracker`. + */ +function Tracker(name, engine) { + if (!engine) { + throw new Error("Tracker must be associated with an Engine instance."); + } + + name = name || "Unnamed"; + this.name = name.toLowerCase(); + this.engine = engine; + + this._log = Log.repository.getLogger(`Sync.Engine.${name}.Tracker`); + + this._score = 0; + + this.asyncObserver = Async.asyncObserver(this, this._log); +} + +Tracker.prototype = { + // New-style trackers use change sources to filter out changes made by Sync in + // observer notifications, so we don't want to let the engine ignore all + // changes during a sync. + get ignoreAll() { + return false; + }, + + // Define an empty setter so that the engine doesn't throw a `TypeError` + // setting a read-only property. + set ignoreAll(value) {}, + + /* + * 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() { + this._score = 0; + }, + + // Unsupported, and throws a more descriptive error to ensure callers aren't + // accidentally using persistence. + async getChangedIDs() { + throw new TypeError("This tracker doesn't store changed IDs"); + }, + + // Also unsupported. + async addChangedID(id, when) { + throw new TypeError("Can't add changed ID to this tracker"); + }, + + // Ditto. + async removeChangedID(...ids) { + throw new TypeError("Can't remove changed IDs from this tracker"); + }, + + // This method is called at various times, so we override with a no-op + // instead of throwing. + clearChangedIDs() {}, + + _now() { + return Date.now() / 1000; + }, + + _isTracking: false, + + start() { + if (!this.engineIsEnabled()) { + return; + } + this._log.trace("start()."); + if (!this._isTracking) { + this.onStart(); + this._isTracking = true; + } + }, + + async stop() { + this._log.trace("stop()."); + if (this._isTracking) { + await this.asyncObserver.promiseObserversComplete(); + this.onStop(); + this._isTracking = false; + } + }, + + // Override these in your subclasses. + onStart() {}, + onStop() {}, + async observe(subject, topic, data) {}, + + engineIsEnabled() { + if (!this.engine) { + // Can't tell -- we must be running in a test! + return true; + } + return this.engine.enabled; + }, + + /** + * Starts or stops listening for changes depending on the associated engine's + * enabled state. + * + * @param {Boolean} engineEnabled Whether the engine was enabled. + */ + async onEngineEnabledChanged(engineEnabled) { + if (engineEnabled == this._isTracking) { + return; + } + + if (engineEnabled) { + this.start(); + } else { + await this.stop(); + this.clearChangedIDs(); + } + }, + + async finalize() { + await this.stop(); + }, +}; + +/* + * A tracker that persists a list of IDs for all changed items that need to be + * synced. This is 🚨 _extremely deprecated_ 🚨 and only kept around for current + * engines. ⚠️ Please **don't use it** for new engines! ⚠️ + * + * Why is this kind of external change tracking deprecated? Because it causes + * consistency issues due to missed notifications, interrupted syncs, and the + * tracker's view of what changed diverging from the data store's. + */ +function LegacyTracker(name, engine) { + Tracker.call(this, name, engine); + + this._ignored = []; + this.file = this.name; + this._storage = new JSONFile({ + path: Utils.jsonFilePath("changes/" + this.file), + dataPostProcessor: json => this._dataPostProcessor(json), + beforeSave: () => this._beforeSave(), + }); + this._ignoreAll = false; +} + +LegacyTracker.prototype = { + __proto__: Tracker.prototype, + + get ignoreAll() { + return this._ignoreAll; + }, + + set ignoreAll(value) { + this._ignoreAll = value; + }, + + // Default to an empty object if the file doesn't exist. + _dataPostProcessor(json) { + return (typeof json == "object" && json) || {}; + }, + + // Ensure the Weave storage directory exists before writing the file. + _beforeSave() { + return ensureDirectory(this._storage.path); + }, + + async getChangedIDs() { + await this._storage.load(); + return this._storage.data; + }, + + _saveChangedIDs() { + this._storage.saveSoon(); + }, + + // 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(id) { + this.unignoreID(id); + this._ignored.push(id); + }, + + unignoreID(id) { + let index = this._ignored.indexOf(id); + if (index != -1) { + this._ignored.splice(index, 1); + } + }, + + async _saveChangedID(id, when) { + this._log.trace(`Adding changed ID: ${id}, ${JSON.stringify(when)}`); + const changedIDs = await this.getChangedIDs(); + changedIDs[id] = when; + this._saveChangedIDs(); + }, + + async addChangedID(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(); + } + + const changedIDs = await this.getChangedIDs(); + // Add/update the entry if we have a newer time. + if ((changedIDs[id] || -Infinity) < when) { + await this._saveChangedID(id, when); + } + + return true; + }, + + async removeChangedID(...ids) { + if (!ids.length || this.ignoreAll) { + return false; + } + for (let id of ids) { + if (!id) { + this._log.warn("Attempted to remove undefined ID from tracker"); + continue; + } + if (this._ignored.includes(id)) { + this._log.debug(`Not removing ignored ID ${id} from tracker`); + continue; + } + const changedIDs = await this.getChangedIDs(); + if (changedIDs[id] != null) { + this._log.trace("Removing changed ID " + id); + delete changedIDs[id]; + } + } + this._saveChangedIDs(); + return true; + }, + + clearChangedIDs() { + this._log.trace("Clearing changed ID list"); + this._storage.data = {}; + this._saveChangedIDs(); + }, + + async finalize() { + // Persist all pending tracked changes to disk, and wait for the final write + // to finish. + await super.finalize(); + this._saveChangedIDs(); + await this._storage.finalize(); + }, +}; + +/** + * The Store serves as the interface between Sync and stored data. + * + * The name "store" is slightly a misnomer because it doesn't actually "store" + * anything. Instead, it serves as a gateway to something that actually does + * the "storing." + * + * The store is responsible for record management inside an engine. It tells + * Sync what items are available for Sync, converts items to and from Sync's + * record format, and applies records from Sync into changes on the underlying + * store. + * + * Store implementations require a number of functions to be implemented. These + * are all documented below. + * + * For stores that deal with many records or which have expensive store access + * routines, it is highly recommended to implement a custom applyIncomingBatch + * and/or applyIncoming function on top of the basic APIs. + */ + +function Store(name, engine) { + if (!engine) { + throw new Error("Store must be associated with an Engine instance."); + } + + name = name || "Unnamed"; + this.name = name.toLowerCase(); + this.engine = engine; + + this._log = Log.repository.getLogger(`Sync.Engine.${name}.Store`); + + XPCOMUtils.defineLazyGetter(this, "_timer", function() { + return Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer); + }); +} +Store.prototype = { + /** + * 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 + */ + async applyIncomingBatch(records) { + let failed = []; + + await Async.yieldingForEach(records, async record => { + try { + await this.applyIncoming(record); + } catch (ex) { + if (ex.code == SyncEngine.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); + 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 + */ + async applyIncoming(record) { + if (record.deleted) { + await this.remove(record); + } else if (!(await this.itemExists(record.id))) { + await this.create(record); + } else { + await 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 + */ + async create(record) { + throw new Error("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 + */ + async remove(record) { + throw new Error("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 + */ + async update(record) { + throw new Error("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 + */ + async itemExists(id) { + throw new Error("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 + */ + async createRecord(id, collection) { + throw new Error("override createRecord in a subclass"); + }, + + /** + * Change the ID of a record. + * + * @param oldID + * string old/current record ID + * @param newID + * string new record ID + */ + async changeItemID(oldID, newID) { + throw new Error("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. + */ + async getAllIDs() { + throw new Error("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. + */ + async wipe() { + throw new Error("override wipe in a subclass"); + }, +}; + +function EngineManager(service) { + this.service = service; + + this._engines = {}; + + this._altEngineInfo = {}; + + // This will be populated by Service on startup. + this._declined = new Set(); + this._log = Log.repository.getLogger("Sync.EngineManager"); + this._log.manageLevelFromPref("services.sync.log.logger.service.engines"); + // define the default level for all engine logs here (although each engine + // allows its level to be controlled via a specific, non-default pref) + Log.repository + .getLogger(`Sync.Engine`) + .manageLevelFromPref("services.sync.log.logger.engine"); +} +EngineManager.prototype = { + get(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; + } + + return this._engines[name]; // Silently returns undefined for unknown names. + }, + + getAll() { + let engines = []; + for (let [, engine] of Object.entries(this._engines)) { + engines.push(engine); + } + return engines; + }, + + /** + * If a user has changed a pref that controls which variant of a sync engine + * for a given collection we use, unregister the old engine and register the + * new one. + * + * This is called by EngineSynchronizer before every sync. + */ + async switchAlternatives() { + for (let [name, info] of Object.entries(this._altEngineInfo)) { + let prefValue = info.prefValue; + if (prefValue === info.lastValue) { + this._log.trace( + `No change for engine ${name} (${info.pref} is still ${prefValue})` + ); + continue; + } + // Unregister the old engine, register the new one. + this._log.info( + `Switching ${name} engine ("${info.pref}" went from ${info.lastValue} => ${prefValue})` + ); + try { + await this._removeAndFinalize(name); + } catch (e) { + this._log.warn(`Failed to remove previous ${name} engine...`, e); + } + let engineType = prefValue ? info.whenTrue : info.whenFalse; + try { + // If register throws, we'll try again next sync, but until then there + // won't be an engine registered for this collection. + await this.register(engineType); + info.lastValue = prefValue; + // Note: engineType.name is using Function.prototype.name. + this._log.info(`Switched the ${name} engine to use ${engineType.name}`); + } catch (e) { + this._log.warn( + `Switching the ${name} engine to use ${engineType.name} failed (couldn't register)`, + e + ); + } + } + }, + + async registerAlternatives(name, pref, whenTrue, whenFalse) { + let info = { name, pref, whenTrue, whenFalse }; + + XPCOMUtils.defineLazyPreferenceGetter(info, "prefValue", pref, false); + + let chosen = info.prefValue ? info.whenTrue : info.whenFalse; + info.lastValue = info.prefValue; + this._altEngineInfo[name] = info; + + await this.register(chosen); + }, + + /** + * N.B., does not pay attention to the declined list. + */ + getEnabled() { + return this.getAll() + .filter(engine => engine.enabled) + .sort((a, b) => a.syncPriority - b.syncPriority); + }, + + get enabledEngineNames() { + return this.getEnabled().map(e => e.name); + }, + + persistDeclined() { + Svc.Prefs.set("declinedEngines", [...this._declined].join(",")); + }, + + /** + * Returns an array. + */ + getDeclined() { + return [...this._declined]; + }, + + setDeclined(engines) { + this._declined = new Set(engines); + this.persistDeclined(); + }, + + isDeclined(engineName) { + return this._declined.has(engineName); + }, + + /** + * Accepts a Set or an array. + */ + decline(engines) { + for (let e of engines) { + this._declined.add(e); + } + this.persistDeclined(); + }, + + undecline(engines) { + for (let e of engines) { + this._declined.delete(e); + } + 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 + */ + async register(engineObject) { + if (Array.isArray(engineObject)) { + for (const e of engineObject) { + await this.register(e); + } + return; + } + + 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 { + if (engine.initialize) { + await engine.initialize(); + } + this._engines[name] = engine; + } + } catch (ex) { + let name = engineObject || ""; + name = name.prototype || ""; + name = name.name || ""; + + this._log.error(`Could not initialize engine ${name}`, ex); + } + }, + + async unregister(val) { + let name = val; + if (val instanceof SyncEngine) { + name = val.name; + } + await this._removeAndFinalize(name); + delete this._altEngineInfo[name]; + }, + + // Common code for disabling an engine by name, that doesn't complain if the + // engine doesn't exist. Doesn't touch the engine's alternative info (if any + // exists). + async _removeAndFinalize(name) { + if (name in this._engines) { + let engine = this._engines[name]; + delete this._engines[name]; + await engine.finalize(); + } + }, + + async clear() { + for (let name in this._engines) { + let engine = this._engines[name]; + delete this._engines[name]; + await engine.finalize(); + } + this._altEngineInfo = {}; + }, +}; + +function SyncEngine(name, service) { + if (!service) { + throw new Error("SyncEngine must be associated with a Service instance."); + } + + this.Name = name || "Unnamed"; + this.name = name.toLowerCase(); + this.service = service; + + this._notify = Utils.notify("weave:engine:"); + this._log = Log.repository.getLogger("Sync.Engine." + this.Name); + this._log.manageLevelFromPref(`services.sync.log.logger.engine.${this.name}`); + + this._modified = this.emptyChangeset(); + this._tracker; // initialize tracker to load previously changed IDs + this._log.debug("Engine constructed"); + + this._toFetchStorage = new JSONFile({ + path: Utils.jsonFilePath("toFetch/" + this.name), + dataPostProcessor: json => this._metadataPostProcessor(json), + beforeSave: () => this._beforeSaveMetadata(), + }); + + this._previousFailedStorage = new JSONFile({ + path: Utils.jsonFilePath("failed/" + this.name), + dataPostProcessor: json => this._metadataPostProcessor(json), + beforeSave: () => this._beforeSaveMetadata(), + }); + + XPCOMUtils.defineLazyPreferenceGetter( + this, + "_enabled", + `services.sync.engine.${this.prefName}`, + false + ); + XPCOMUtils.defineLazyPreferenceGetter( + this, + "_syncID", + `services.sync.${this.name}.syncID`, + "" + ); + XPCOMUtils.defineLazyPreferenceGetter( + this, + "_lastSync", + `services.sync.${this.name}.lastSync`, + "0", + null, + v => parseFloat(v) + ); + // Async initializations can be made in the initialize() method. + + // The map of ids => metadata for records needing a weak upload. + // + // Currently the "metadata" fields are: + // + // - forceTombstone: whether or not we should ignore the local information + // about the record, and write a tombstone for it anyway -- e.g. in the case + // of records that should exist locally, but should never be uploaded to the + // server (note that not all sync engines support tombstones) + // + // The difference between this and a "normal" upload is that these records + // are only tracked in memory, and if the upload attempt fails (shutdown, + // 412, etc), we abort uploading the "weak" set (by clearing the map). + // + // The rationale here is for the cases where we receive a record from the + // server that we know is wrong in some (small) way. For example, the + // dateAdded field on bookmarks -- maybe we have a better date, or the server + // record is entirely missing the date, etc. + // + // In these cases, we fix our local copy of the record, and mark it for + // weak upload. A normal ("strong") upload is problematic here because + // in the case of a conflict from the server, there's a window where our + // record would be marked as modified more recently than a change that occurs + // on another device change, and we lose data from the user. + this._needWeakUpload = new Map(); + + this.asyncObserver = Async.asyncObserver(this, this._log); +} + +// 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 = { + _recordObj: CryptoWrapper, + // _storeObj, and _trackerObj should to be overridden in subclasses + _storeObj: Store, + _trackerObj: Tracker, + version: 1, + + // 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, + + // Which sortindex to use when retrieving records for this engine. + _defaultSort: undefined, + + _hasSyncedThisSession: false, + + _metadataPostProcessor(json) { + if (Array.isArray(json)) { + // Pre-`JSONFile` storage stored an array, but `JSONFile` defaults to + // an object, so we wrap the array for consistency. + json = { ids: json }; + } + if (!json.ids) { + json.ids = []; + } + // The set serializes the same way as an array, but offers more efficient + // methods of manipulation. + json.ids = new SerializableSet(json.ids); + return json; + }, + + async _beforeSaveMetadata() { + await ensureDirectory(this._toFetchStorage.path); + await ensureDirectory(this._previousFailedStorage.path); + }, + + // 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, + + downloadBatchSize: DEFAULT_DOWNLOAD_BATCH_SIZE, + + async initialize() { + await this._toFetchStorage.load(); + await this._previousFailedStorage.load(); + Svc.Prefs.observe(`engine.${this.prefName}`, this.asyncObserver); + this._log.debug("SyncEngine initialized", this.name); + }, + + get prefName() { + return this.name; + }, + + get enabled() { + return this._enabled; + }, + + set enabled(val) { + if (!!val != this._enabled) { + 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; + }, + + 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"; + }, + + startTracking() { + this._tracker.start(); + }, + + // Returns a promise + stopTracking() { + return this._tracker.stop(); + }, + + // Listens for engine enabled state changes, and updates the tracker's state. + // This is an async observer because the tracker waits on all its async + // observers to finish when it's stopped. + async observe(subject, topic, data) { + if ( + topic == "nsPref:changed" && + data == `services.sync.engine.${this.prefName}` + ) { + await this._tracker.onEngineEnabledChanged(this._enabled); + } + }, + + async sync() { + if (!this.enabled) { + return false; + } + + if (!this._sync) { + throw new Error("engine does not implement _sync method"); + } + + return this._notify("sync", this.name, this._sync)(); + }, + + // Override this method to return a new changeset type. + emptyChangeset() { + return new Changeset(); + }, + + /** + * Returns the local sync ID for this engine, or `""` if the engine hasn't + * synced for the first time. This is exposed for tests. + * + * @return the current sync ID. + */ + async getSyncID() { + return this._syncID; + }, + + /** + * Ensures that the local sync ID for the engine matches the sync ID for the + * collection on the server. A mismatch indicates that another client wiped + * the collection; we're syncing after a node reassignment, and another + * client synced before us; or the store was replaced since the last sync. + * In case of a mismatch, we need to reset all local Sync state and start + * over as a first sync. + * + * In most cases, this method should return the new sync ID as-is. However, an + * engine may ignore the given ID and assign a different one, if it determines + * that the sync ID on the server is out of date. The bookmarks engine uses + * this to wipe the server and other clients on the first sync after the user + * restores from a backup. + * + * @param newSyncID + * The new sync ID for the collection from `meta/global`. + * @return The assigned sync ID. If this doesn't match `newSyncID`, we'll + * replace the sync ID in `meta/global` with the assigned ID. + */ + async ensureCurrentSyncID(newSyncID) { + let existingSyncID = this._syncID; + if (existingSyncID == newSyncID) { + return existingSyncID; + } + this._log.debug("Engine syncIDs: " + [newSyncID, existingSyncID]); + Svc.Prefs.set(this.name + ".syncID", newSyncID); + Svc.Prefs.set(this.name + ".lastSync", "0"); + return newSyncID; + }, + + /** + * Resets the local sync ID for the engine, wipes the server, and resets all + * local Sync state to start over as a first sync. + * + * @return the new sync ID. + */ + async resetSyncID() { + let newSyncID = await this.resetLocalSyncID(); + await this.wipeServer(); + return newSyncID; + }, + + /** + * Resets the local sync ID for the engine, signaling that we're starting over + * as a first sync. + * + * @return the new sync ID. + */ + async resetLocalSyncID() { + return this.ensureCurrentSyncID(Utils.makeGUID()); + }, + + /** + * Allows overriding scheduler logic -- added to help reduce kinto server + * getting hammered because our scheduler never got tuned for it. + * + * Note: Overriding engines must take resyncs into account -- score will not + * be cleared. + */ + shouldSkipSync(syncReason) { + return false; + }, + + /* + * lastSync is a timestamp in server time. + */ + async getLastSync() { + return this._lastSync; + }, + async setLastSync(lastSync) { + // Store the value as a string to keep floating point precision + Svc.Prefs.set(this.name + ".lastSync", lastSync.toString()); + }, + async resetLastSync() { + this._log.debug("Resetting " + this.name + " last sync time"); + await this.setLastSync(0); + }, + + get hasSyncedThisSession() { + return this._hasSyncedThisSession; + }, + + set hasSyncedThisSession(hasSynced) { + this._hasSyncedThisSession = hasSynced; + }, + + get toFetch() { + this._toFetchStorage.ensureDataReady(); + return this._toFetchStorage.data.ids; + }, + + set toFetch(ids) { + if (ids.constructor.name != "SerializableSet") { + throw new Error( + "Bug: Attempted to set toFetch to something that isn't a SerializableSet" + ); + } + this._toFetchStorage.data = { ids }; + this._toFetchStorage.saveSoon(); + }, + + get previousFailed() { + this._previousFailedStorage.ensureDataReady(); + return this._previousFailedStorage.data.ids; + }, + + set previousFailed(ids) { + if (ids.constructor.name != "SerializableSet") { + throw new Error( + "Bug: Attempted to set previousFailed to something that isn't a SerializableSet" + ); + } + this._previousFailedStorage.data = { ids }; + this._previousFailedStorage.saveSoon(); + }, + + /* + * Returns a changeset for this sync. Engine implementations can override this + * method to bypass the tracker for certain or all changed items. + */ + async getChangedIDs() { + return this._tracker.getChangedIDs(); + }, + + // Create a new record using the store and add in metadata. + async _createRecord(id) { + let record = await this._store.createRecord(id, this.name); + record.id = id; + record.collection = this.name; + return record; + }, + + // Creates a tombstone Sync record with additional metadata. + _createTombstone(id) { + let tombstone = new this._recordObj(this.name, id); + tombstone.id = id; + tombstone.collection = this.name; + tombstone.deleted = true; + return tombstone; + }, + + addForWeakUpload(id, { forceTombstone = false } = {}) { + this._needWeakUpload.set(id, { forceTombstone }); + }, + + // Any setup that needs to happen at the beginning of each sync. + async _syncStartup() { + // Determine if we need to wipe on outdated versions + let metaGlobal = await this.service.recordManager.get(this.metaURL); + let engines = metaGlobal.payload.engines || {}; + let engineData = engines[this.name] || {}; + + // 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]); + + // Clear the server and reupload everything on bad version or missing + // meta. Note that we don't regenerate per-collection keys here. + let newSyncID = await this.resetSyncID(); + + // Set the newer version and newly generated syncID + engineData.version = this.version; + engineData.syncID = newSyncID; + + // Put the new data back into meta/global and mark for upload + engines[this.name] = engineData; + metaGlobal.payload.engines = engines; + metaGlobal.changed = true; + } else if (engineData.version > this.version) { + // Don't sync this engine if the server has newer data + + let error = new Error("New data: " + [engineData.version, this.version]); + error.failureCode = VERSION_OUT_OF_DATE; + throw error; + } else { + // Changes to syncID mean we'll need to upload everything + let assignedSyncID = await this.ensureCurrentSyncID(engineData.syncID); + if (assignedSyncID != engineData.syncID) { + engineData.syncID = assignedSyncID; + metaGlobal.changed = true; + } + } + + // Save objects that need to be uploaded in this._modified. 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. + let initialChanges = await this.pullChanges(); + this._modified.replace(initialChanges); + // Clear the tracker now. If the sync fails we'll add the ones we failed + // to upload back. + this._tracker.clearChangedIDs(); + this._tracker.resetScore(); + + this._log.info( + this._modified.count() + " outgoing items pre-reconciliation" + ); + + // Keep track of what to delete at the end of sync + this._delete = {}; + }, + + async pullChanges() { + let lastSync = await this.getLastSync(); + if (lastSync) { + return this.pullNewChanges(); + } + this._log.debug("First sync, uploading all items"); + return this.pullAllChanges(); + }, + + /** + * A tiny abstraction to make it easier to test incoming record + * application. + */ + itemSource() { + return new Collection(this.engineURL, this._recordObj, this.service); + }, + + /** + * Download and apply remote records changed since the last sync. This + * happens in three stages. + * + * In the first stage, we fetch full records for all changed items, newest + * first, up to the download limit. The limit lets us make progress for large + * collections, where the sync is likely to be interrupted before we + * can fetch everything. + * + * In the second stage, we fetch the IDs of any remaining records changed + * since the last sync, add them to our backlog, and fast-forward our last + * sync time. + * + * In the third stage, we fetch and apply records for all backlogged IDs, + * as well as any records that failed to apply during the last sync. We + * request records for the IDs in chunks, to avoid exceeding URL length + * limits, then remove successfully applied records from the backlog, and + * record IDs of any records that failed to apply to retry on the next sync. + */ + async _processIncoming() { + this._log.trace("Downloading & applying server changes"); + + let newitems = this.itemSource(); + let lastSync = await this.getLastSync(); + + newitems.newer = lastSync; + newitems.full = true; + + let downloadLimit = Infinity; + if (this.downloadLimit) { + // Fetch new records up to the download limit. Currently, only the history + // engine sets a limit, since the history collection has the highest volume + // of changed records between syncs. The other engines fetch all records + // changed since the last sync. + if (this._defaultSort) { + // A download limit with a sort order doesn't make sense: we won't know + // which records to backfill. + throw new Error("Can't specify download limit with default sort order"); + } + newitems.sort = "newest"; + downloadLimit = newitems.limit = this.downloadLimit; + } else if (this._defaultSort) { + // The bookmarks engine fetches records by sort index; other engines leave + // the order unspecified. We can remove `_defaultSort` entirely after bug + // 1305563: the sort index won't matter because we'll buffer all bookmarks + // before applying. + newitems.sort = this._defaultSort; + } + + // 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 recordsToApply = []; + let failedInCurrentSync = new SerializableSet(); + + let oldestModified = this.lastModified; + let downloadedIDs = new Set(); + + // Stage 1: Fetch new records from the server, up to the download limit. + if (this.lastModified == null || this.lastModified > lastSync) { + let { response, records } = await newitems.getBatched( + this.downloadBatchSize + ); + if (!response.success) { + response.failureCode = ENGINE_DOWNLOAD_FAIL; + throw response; + } + + await Async.yieldingForEach(records, async record => { + downloadedIDs.add(record.id); + + if (record.modified < oldestModified) { + oldestModified = record.modified; + } + + let { shouldApply, error } = await this._maybeReconcile(record); + if (error) { + failedInCurrentSync.add(record.id); + count.failed++; + return; + } + if (!shouldApply) { + count.reconciled++; + return; + } + recordsToApply.push(record); + }); + + let failedToApply = await this._applyRecords(recordsToApply); + Utils.setAddAll(failedInCurrentSync, failedToApply); + + // `applied` is a bit of a misnomer: it counts records that *should* be + // applied, so it also includes records that we tried to apply and failed. + // `recordsToApply.length - failedToApply.length` is the number of records + // that we *successfully* applied. + count.failed += failedToApply.length; + count.applied += recordsToApply.length; + } + + // Stage 2: If we reached our download limit, we might still have records + // on the server that changed since the last sync. Fetch the IDs for the + // remaining records, and add them to the backlog. Note that this stage + // only runs for engines that set a download limit. + if (downloadedIDs.size == downloadLimit) { + let guidColl = this.itemSource(); + + guidColl.newer = lastSync; + guidColl.older = oldestModified; + guidColl.sort = "oldest"; + + let guids = await guidColl.get(); + if (!guids.success) { + throw guids; + } + + // Filtering out already downloaded IDs here isn't necessary. We only do + // that in case the Sync server doesn't support `older` (bug 1316110). + let remainingIDs = guids.obj.filter(id => !downloadedIDs.has(id)); + if (remainingIDs.length > 0) { + this.toFetch = Utils.setAddAll(this.toFetch, remainingIDs); + } + } + + // Fast-foward the lastSync timestamp since we have backlogged the + // remaining items. + if (lastSync < this.lastModified) { + lastSync = this.lastModified; + await this.setLastSync(lastSync); + } + + // Stage 3: Backfill records from the backlog, and those that failed to + // decrypt or apply during the last sync. We only backfill up to the + // download limit, to prevent a large backlog for one engine from blocking + // the others. We'll keep processing the backlog on subsequent engine syncs. + let failedInPreviousSync = this.previousFailed; + let idsToBackfill = Array.from( + Utils.setAddAll( + Utils.subsetOfSize(this.toFetch, downloadLimit), + failedInPreviousSync + ) + ); + + // Note that we intentionally overwrite the previously failed list here. + // Records that fail to decrypt or apply in two consecutive syncs are likely + // corrupt; we remove them from the list because retrying and failing on + // every subsequent sync just adds noise. + this.previousFailed = failedInCurrentSync; + + let backfilledItems = this.itemSource(); + + backfilledItems.sort = "newest"; + backfilledItems.full = true; + + // `getBatched` includes the list of IDs as a query parameter, so we need to fetch + // records in chunks to avoid exceeding URI length limits. + if (this.guidFetchBatchSize) { + for (let ids of PlacesUtils.chunkArray( + idsToBackfill, + this.guidFetchBatchSize + )) { + backfilledItems.ids = ids; + + let { response, records } = await backfilledItems.getBatched( + this.downloadBatchSize + ); + if (!response.success) { + response.failureCode = ENGINE_DOWNLOAD_FAIL; + throw response; + } + + let backfilledRecordsToApply = []; + let failedInBackfill = []; + + await Async.yieldingForEach(records, async record => { + let { shouldApply, error } = await this._maybeReconcile(record); + if (error) { + failedInBackfill.push(record.id); + count.failed++; + return; + } + if (!shouldApply) { + count.reconciled++; + return; + } + backfilledRecordsToApply.push(record); + }); + + let failedToApply = await this._applyRecords(backfilledRecordsToApply); + failedInBackfill.push(...failedToApply); + + count.failed += failedToApply.length; + count.applied += backfilledRecordsToApply.length; + + this.toFetch = Utils.setDeleteAll(this.toFetch, ids); + this.previousFailed = Utils.setAddAll( + this.previousFailed, + failedInBackfill + ); + + if (lastSync < this.lastModified) { + lastSync = this.lastModified; + await this.setLastSync(lastSync); + } + } + } + + count.newFailed = 0; + for (let item of this.previousFailed) { + if (!failedInPreviousSync.has(item)) { + ++count.newFailed; + } + } + + 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); + }, + + async _maybeReconcile(item) { + let key = this.service.collectionKeys.keyForCollection(this.name); + + // Grab a later last modified if possible + if (this.lastModified == null || item.modified > this.lastModified) { + this.lastModified = item.modified; + } + + try { + try { + await item.decrypt(key); + } catch (ex) { + if (!Utils.isHMACMismatch(ex)) { + throw ex; + } + let strategy = await this.handleHMACMismatch(item, true); + if (strategy == SyncEngine.kRecoveryStrategy.retry) { + // You only get one retry. + try { + // Try decrypting again, typically because we've got new keys. + this._log.info("Trying decrypt again..."); + key = this.service.collectionKeys.keyForCollection(this.name); + await item.decrypt(key); + strategy = null; + } catch (ex) { + if (!Utils.isHMACMismatch(ex)) { + throw ex; + } + strategy = await this.handleHMACMismatch(item, false); + } + } + + switch (strategy) { + case null: + // Retry succeeded! No further handling. + break; + case SyncEngine.kRecoveryStrategy.retry: + this._log.debug("Ignoring second retry suggestion."); + // Fall through to error case. + case SyncEngine.kRecoveryStrategy.error: + this._log.warn("Error decrypting record", ex); + return { shouldApply: false, error: ex }; + case SyncEngine.kRecoveryStrategy.ignore: + this._log.debug( + "Ignoring record " + item.id + " with bad HMAC: already handled." + ); + return { shouldApply: false, error: null }; + } + } + } catch (ex) { + if (Async.isShutdownException(ex)) { + throw ex; + } + this._log.warn("Error decrypting record", ex); + return { shouldApply: false, error: ex }; + } + + if (this._shouldDeleteRemotely(item)) { + this._log.trace("Deleting item from server without applying", item); + await this._deleteId(item.id); + return { shouldApply: false, error: null }; + } + + let shouldApply; + try { + shouldApply = await this._reconcile(item); + } catch (ex) { + if (ex.code == SyncEngine.prototype.eEngineAbortApplyIncoming) { + this._log.warn("Reconciliation failed: aborting incoming processing."); + throw ex.cause; + } else if (!Async.isShutdownException(ex)) { + this._log.warn("Failed to reconcile incoming record " + item.id, ex); + return { shouldApply: false, error: ex }; + } else { + throw ex; + } + } + + if (!shouldApply) { + this._log.trace("Skipping reconciled incoming item " + item.id); + } + + return { shouldApply, error: null }; + }, + + async _applyRecords(records) { + this._tracker.ignoreAll = true; + try { + let failedIDs = await this._store.applyIncomingBatch(records); + return failedIDs; + } catch (ex) { + // Catch any error that escapes from applyIncomingBatch. At present + // those will all be abort events. + this._log.warn("Got exception, aborting processIncoming", ex); + throw ex; + } finally { + this._tracker.ignoreAll = false; + } + }, + + // Indicates whether an incoming item should be deleted from the server at + // the end of the sync. Engines can override this method to clean up records + // that shouldn't be on the server. + _shouldDeleteRemotely(remoteItem) { + return false; + }, + + /** + * 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 + */ + async _findDupe(item) { + // By default, assume there's no dupe items for the engine + }, + + /** + * Called before a remote record is discarded due to failed reconciliation. + * Used by bookmark sync to merge folder child orders. + */ + beforeRecordDiscard(localRecord, remoteRecord, remoteIsNewer) {}, + + // 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). + async _shouldReviveRemotelyDeletedRecord(remoteItem) { + return true; + }, + + async _deleteId(id) { + await this._tracker.removeChangedID(id); + this._noteDeletedId(id); + }, + + // Marks an ID for deletion at the end of the sync. + _noteDeletedId(id) { + if (this._delete.ids == null) { + this._delete.ids = [id]; + } else { + this._delete.ids.push(id); + } + }, + + async _switchItemToDupe(localDupeGUID, incomingItem) { + // The local, duplicate ID is always deleted on the server. + await 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 + ); + return 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. + */ + async _reconcile(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 = await this._store.itemExists(item.id); + let locallyModified = this._modified.has(item.id); + + // TODO Handle clock drift better. Tracked in bug 721181. + let remoteAge = Resource.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 = await 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 = await 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 = await 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.changeID(localDupeGUID, item.id); + } else { + locallyModified = false; + localAge = null; + } + + // Tell the engine to do whatever it needs to switch the items. + await 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 = await 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 + ); + if (!remoteIsNewer) { + this.beforeRecordDiscard(localRecord, item, remoteIsNewer); + } + return remoteIsNewer; + }, + + // Upload outgoing records. + async _uploadOutgoing() { + this._log.trace("Uploading local changes to server."); + + // collection we'll upload + let up = new Collection(this.engineURL, null, this.service); + let modifiedIDs = new Set(this._modified.ids()); + for (let id of this._needWeakUpload.keys()) { + modifiedIDs.add(id); + } + let counts = { failed: 0, sent: 0 }; + if (modifiedIDs.size) { + this._log.trace("Preparing " + modifiedIDs.size + " outgoing records"); + + counts.sent = modifiedIDs.size; + + let failed = []; + let successful = []; + let lastSync = await this.getLastSync(); + let handleResponse = async (postQueue, resp, batchOngoing) => { + // 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.status}`); + 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; + } + + 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); + } + + await this._onRecordsWritten( + successful, + failed, + postQueue.lastModified + ); + + // Advance lastSync since we've finished the batch. + if (postQueue.lastModified > lastSync) { + lastSync = postQueue.lastModified; + await this.setLastSync(lastSync); + } + + // clear for next batch + failed.length = 0; + successful.length = 0; + }; + + let postQueue = up.newPostQueue(this._log, lastSync, handleResponse); + + for (let id of modifiedIDs) { + let out; + let ok = false; + try { + let { forceTombstone = false } = this._needWeakUpload.get(id) || {}; + if (forceTombstone) { + out = await this._createTombstone(id); + } else { + out = await this._createRecord(id); + } + if (this._log.level <= Log.Level.Trace) { + this._log.trace("Outgoing: " + out); + } + await out.encrypt( + this.service.collectionKeys.keyForCollection(this.name) + ); + ok = true; + } catch (ex) { + this._log.warn("Error creating record", ex); + ++counts.failed; + if (Async.isShutdownException(ex) || !this.allowSkippedRecord) { + if (!this.allowSkippedRecord) { + // Don't bother for shutdown errors + Observers.notify("weave:engine:sync:uploaded", counts, this.name); + } + throw ex; + } + } + if (ok) { + let { enqueued, error } = await postQueue.enqueue(out); + if (!enqueued) { + ++counts.failed; + if (!this.allowSkippedRecord) { + Observers.notify("weave:engine:sync:uploaded", counts, this.name); + this._log.warn( + `Failed to enqueue record "${id}" (aborting)`, + error + ); + throw error; + } + this._modified.delete(id); + this._log.warn( + `Failed to enqueue record "${id}" (skipping)`, + error + ); + } + } + await Async.promiseYield(); + } + await postQueue.flush(true); + } + this._needWeakUpload.clear(); + + if (counts.sent || counts.failed) { + Observers.notify("weave:engine:sync:uploaded", counts, this.name); + } + }, + + async _onRecordsWritten(succeeded, failed, serverModifiedTime) { + // 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 + async _syncFinish() { + this._log.trace("Finishing up sync"); + + let doDelete = async (key, val) => { + let coll = new Collection(this.engineURL, this._recordObj, this.service); + coll[key] = val; + await coll.delete(); + }; + + for (let [key, val] of Object.entries(this._delete)) { + // Remove the key for future uses + delete this._delete[key]; + + this._log.trace("doing post-sync deletions", { key, val }); + // Send a simple delete for the property + if (key != "ids" || val.length <= 100) { + await doDelete(key, val); + } else { + // For many ids, split into chunks of at most 100 + while (val.length > 0) { + await doDelete(key, val.slice(0, 100)); + val = val.slice(100); + } + } + } + this.hasSyncedThisSession = true; + await this._tracker.asyncObserver.promiseObserversComplete(); + }, + + async _syncCleanup() { + this._needWeakUpload.clear(); + try { + // Mark failed WBOs as changed again so they are reuploaded next time. + await this.trackRemainingChanges(); + } finally { + this._modified.clear(); + } + }, + + async _sync() { + try { + Async.checkAppReady(); + await this._syncStartup(); + Async.checkAppReady(); + Observers.notify("weave:engine:sync:status", "process-incoming"); + await this._processIncoming(); + Async.checkAppReady(); + Observers.notify("weave:engine:sync:status", "upload-outgoing"); + try { + await this._uploadOutgoing(); + Async.checkAppReady(); + await this._syncFinish(); + } catch (ex) { + if (!ex.status || ex.status != 412) { + throw ex; + } + // a 412 posting just means another client raced - but we don't want + // to treat that as a sync error - the next sync is almost certain + // to work. + this._log.warn("412 error during sync - will retry."); + } + } finally { + await this._syncCleanup(); + } + }, + + async canDecrypt() { + // 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); + + // Any failure fetching/decrypting will just result in false + try { + this._log.trace("Trying to decrypt a record from the server.."); + let json = (await test.get()).obj[0]; + let record = new this._recordObj(); + record.deserialize(json); + await record.decrypt(key); + canDecrypt = true; + } catch (ex) { + if (Async.isShutdownException(ex)) { + throw ex; + } + this._log.debug("Failed test decrypt", ex); + } + + return canDecrypt; + }, + + /** + * Deletes the collection for this engine on the server, and removes all local + * Sync metadata for this engine. This does *not* remove any existing data on + * other clients. This is called when we reset the sync ID. + */ + async wipeServer() { + await this._deleteServerCollection(); + await this._resetClient(); + }, + + /** + * Deletes the collection for this engine on the server, without removing + * any local Sync metadata or user data. Deleting the collection will not + * remove any user data on other clients, but will force other clients to + * start over as a first sync. + */ + async _deleteServerCollection() { + let response = await this.service.resource(this.engineURL).delete(); + if (response.status != 200 && response.status != 404) { + throw response; + } + }, + + async removeClientData() { + // 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. + */ + async handleHMACMismatch(item, mayRetry) { + // By default we either try again, or bail out noisily. + return (await 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. + */ + async pullAllChanges() { + let changes = {}; + let ids = await this._store.getAllIDs(); + for (let id in ids) { + changes[id] = 0; + } + return changes; + }, + + /* + * 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. + */ + async pullNewChanges() { + await this._tracker.asyncObserver.promiseObserversComplete(); + return 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. + * + */ + async trackRemainingChanges() { + for (let [id, change] of this._modified.entries()) { + await this._tracker.addChangedID(id, change); + } + }, + + /** + * Removes all local Sync metadata for this engine, but keeps all existing + * local user data. + */ + async resetClient() { + return this._notify("reset-client", this.name, this._resetClient)(); + }, + + async _resetClient() { + await this.resetLastSync(); + this.hasSyncedThisSession = false; + this.previousFailed = new SerializableSet(); + this.toFetch = new SerializableSet(); + this._needWeakUpload.clear(); + }, + + /** + * Removes all local Sync metadata and user data for this engine. + */ + async wipeClient() { + return this._notify("wipe-client", this.name, this._wipeClient)(); + }, + + async _wipeClient() { + await this.resetClient(); + this._log.debug("Deleting all local data"); + this._tracker.ignoreAll = true; + await this._store.wipe(); + this._tracker.ignoreAll = false; + this._tracker.clearChangedIDs(); + }, + + /** + * 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() { + return null; + }, + + async finalize() { + Svc.Prefs.ignore(`engine.${this.prefName}`, this.asyncObserver); + await this.asyncObserver.promiseObserversComplete(); + await this._tracker.finalize(); + await this._toFetchStorage.finalize(); + await this._previousFailedStorage.finalize(); + }, + + // Returns a new watchdog. Exposed for tests. + _newWatchdog() { + return Async.watchdog(); + }, +}; + +/** + * 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 an empty changeset. + constructor() { + this.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; + } + + // Adds multiple entries to the changeset, preserving existing entries. + insert(changes) { + Object.assign(this.changes, changes); + } + + // Overwrites the existing set of tracked changes with new entries. + replace(changes) { + this.changes = changes; + } + + // 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]; + } + + // Changes the ID of an entry in the changeset. Used when reconciling + // duplicates that have local changes. + changeID(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 = {}; + } +} |