Bug 675397 - Add syncing priority to be able to reshuffle the default syncing order. r=rnewman

services/sync/modules/engines.js

@@ -483,7 +483,9 @@ EngineManager.prototype = {
    * N.B., does not pay attention to the declined list.
    */
   getEnabled: function () {
-    return this.getAll().filter(function(engine) engine.enabled);
+    return this.getAll()
+               .filter((engine) => engine.enabled)
+               .sort((a, b) => a.syncPriority - b.syncPriority);
   },
 
   get enabledEngineNames() {
@@ -700,6 +702,13 @@ SyncEngine.prototype = {
   _recordObj: CryptoWrapper,
   version: 1,
 
+  // 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,

services/sync/modules/engines/addons.js

@@ -119,6 +119,8 @@ AddonsEngine.prototype = {
   _recordObj:             AddonRecord,
   version:                1,
 
+  syncPriority:           5,
+
   _reconciler:            null,
 
   /**

services/sync/modules/engines/bookmarks.js

@@ -203,6 +203,8 @@ BookmarksEngine.prototype = {
   _trackerObj: BookmarksTracker,
   version: 2,
 
+  syncPriority: 4,
+
   _sync: function _sync() {
     let engine = this;
     let batchEx = null;

services/sync/modules/engines/forms.js

@@ -107,6 +107,8 @@ FormEngine.prototype = {
   _recordObj: FormRec,
   applyIncomingBatchSize: FORMS_STORE_BATCH_SIZE,
 
+  syncPriority: 6,
+
   get prefName() "history",
 
   _findDupe: function _findDupe(item) {

services/sync/modules/engines/history.js

@@ -41,7 +41,9 @@ HistoryEngine.prototype = {
   _storeObj: HistoryStore,
   _trackerObj: HistoryTracker,
   downloadLimit: MAX_HISTORY_DOWNLOAD,
-  applyIncomingBatchSize: HISTORY_STORE_BATCH_SIZE
+  applyIncomingBatchSize: HISTORY_STORE_BATCH_SIZE,
+
+  syncPriority: 7,
 };
 
 function HistoryStore(name, engine) {

services/sync/modules/engines/passwords.js

@@ -36,6 +36,8 @@ PasswordEngine.prototype = {
   _recordObj: LoginRec,
   applyIncomingBatchSize: PASSWORDS_STORE_BATCH_SIZE,
 
+  syncPriority: 2,
+
   _syncFinish: function _syncFinish() {
     SyncEngine.prototype._syncFinish.call(this);
 

services/sync/modules/engines/prefs.js

@@ -41,6 +41,8 @@ PrefsEngine.prototype = {
   _recordObj: PrefRec,
   version: 2,
 
+  syncPriority: 1,
+
   getChangedIDs: function getChangedIDs() {
     // No need for a proper timestamp (no conflict resolution needed).
     let changedIDs = {};

services/sync/modules/engines/tabs.js

@@ -45,6 +45,8 @@ TabEngine.prototype = {
   _trackerObj: TabTracker,
   _recordObj: TabSetRecord,
 
+  syncPriority: 3,
+
   getChangedIDs: function getChangedIDs() {
     // No need for a proper timestamp (no conflict resolution needed).
     let changedIDs = {};

services/sync/tests/unit/head_helpers.js

@@ -192,3 +192,11 @@ function mockGetWindowEnumerator(url, numWindows, numTabs) {
     },
   };
 }
+
+// Helper that allows checking array equality.
+function do_check_array_eq(a1, a2) {
+  do_check_eq(a1.length, a2.length);
+  for (let i = 0; i < a1.length; ++i) {
+    do_check_eq(a1[i], a2[i]);
+  }
+}

services/sync/tests/unit/test_enginemanager.js

@@ -75,6 +75,23 @@ add_test(function test_basics() {
   engines = manager.getEnabled();
   do_check_eq(engines.length, 3);
 
+  _("getEnabled() returns enabled engines in sorted order");
+  petrol.syncPriority = 1;
+  dummy.syncPriority = 2;
+  diesel.syncPriority = 3;
+
+  engines = manager.getEnabled();
+
+  do_check_array_eq(engines, [petrol, dummy, diesel]);
+
+  _("Changing the priorities should change the order in getEnabled()");
+
+  dummy.syncPriority = 4;
+
+  engines = manager.getEnabled();
+
+  do_check_array_eq(engines, [petrol, diesel, dummy]);
+
   _("Unregister an engine by name");
   manager.unregister('dummy');
   do_check_eq(manager.get('dummy'), undefined);

services/sync/tests/unit/test_keys.js

@@ -14,13 +14,6 @@ function sha256HMAC(message, key) {
   return Utils.digestBytes(message, h);
 }
 
-function do_check_array_eq(a1, a2) {
-  do_check_eq(a1.length, a2.length);
-  for (let i = 0; i < a1.length; ++i) {
-    do_check_eq(a1[i], a2[i]);
-  }
-}
-
 function do_check_keypair_eq(a, b) {
   do_check_eq(2, a.length);
   do_check_eq(2, b.length);