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