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gecko-dev/services/sync/modules/engines.js

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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/. */
var EXPORTED_SYMBOLS = [
"EngineManager",
"SyncEngine",
"Tracker",
"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.
*
* 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.
*
*/
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.Engine.${name}.Tracker`);
this._score = 0;
this._ignored = [];
this._storage = new JSONFile({
path: Utils.jsonFilePath("changes/" + this.file),
dataPostProcessor: json => this._dataPostProcessor(json),
beforeSave: () => this._beforeSave(),
});
this.ignoreAll = false;
this.asyncObserver = Async.asyncObserver(this, this._log);
}
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;
},
// 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);
},
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;
},
persistChangedIDs: true,
async getChangedIDs() {
await this._storage.load();
return this._storage.data;
},
_saveChangedIDs() {
if (!this.persistChangedIDs) {
this._log.debug("Not saving changedIDs.");
return;
}
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];
}
}
await this._saveChangedIDs();
return true;
},
async clearChangedIDs() {
this._log.trace("Clearing changed ID list");
this._storage.data = {};
await this._saveChangedIDs();
},
_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;
},
async onEngineEnabledChanged(engineEnabled) {
if (engineEnabled == this._isTracking) {
return;
}
if (engineEnabled) {
this.start();
} else {
await this.stop();
await this.clearChangedIDs();
}
},
async finalize() {
// Persist all pending tracked changes to disk, and wait for the final write
// to finish.
await this.stop();
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.${this.prefName}`,
false,
(data, previous, latest) =>
// We do not await on the promise onEngineEnabledChanged returns.
this._tracker.onEngineEnabledChanged(latest)
);
XPCOMUtils.defineLazyPreferenceGetter(
this,
"_syncID",
`services.sync.${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.
//
// Additionally, we use this as the set of items to upload for bookmark
// repair reponse, which has similar constraints.
this._needWeakUpload = new Map();
}
// 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();
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();
},
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.
await 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);
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();
if (!this._modified) {
return;
}
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;
await 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() {
await this._tracker.finalize();
await this._toFetchStorage.finalize();
await this._previousFailedStorage.finalize();
},
};
/**
* 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 = {};
}
}
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