1 files changed, 295 insertions, 0 deletions
diff --git a/services/sync/modules/engines/extension-storage.js b/services/sync/modules/engines/extension-storage.js
new file mode 100644
index 0000000000..705091957e
--- /dev/null
+++ b/services/sync/modules/engines/extension-storage.js
@@ -0,0 +1,295 @@
+/* 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/. */
+
+"use strict";
+
+var EXPORTED_SYMBOLS = [
+  "ExtensionStorageEngineKinto",
+  "ExtensionStorageEngineBridge",
+];
+
+const { XPCOMUtils } = ChromeUtils.import(
+  "resource://gre/modules/XPCOMUtils.jsm"
+);
+
+XPCOMUtils.defineLazyModuleGetters(this, {
+  BridgedEngine: "resource://services-sync/bridged_engine.js",
+  LogAdapter: "resource://services-sync/bridged_engine.js",
+  extensionStorageSync: "resource://gre/modules/ExtensionStorageSync.jsm",
+  Observers: "resource://services-common/observers.js",
+  Svc: "resource://services-sync/util.js",
+  SyncEngine: "resource://services-sync/engines.js",
+  Tracker: "resource://services-sync/engines.js",
+  SCORE_INCREMENT_MEDIUM: "resource://services-sync/constants.js",
+  MULTI_DEVICE_THRESHOLD: "resource://services-sync/constants.js",
+});
+
+XPCOMUtils.defineLazyModuleGetter(
+  this,
+  "extensionStorageSyncKinto",
+  "resource://gre/modules/ExtensionStorageSyncKinto.jsm",
+  "extensionStorageSync"
+);
+
+XPCOMUtils.defineLazyServiceGetter(
+  this,
+  "StorageSyncService",
+  "@mozilla.org/extensions/storage/sync;1",
+  "nsIInterfaceRequestor"
+);
+
+const PREF_FORCE_ENABLE = "engine.extension-storage.force";
+
+// A helper to indicate whether extension-storage is enabled - it's based on
+// the "addons" pref. The same logic is shared between both engine impls.
+function getEngineEnabled() {
+  // By default, we sync extension storage if we sync addons. This
+  // lets us simplify the UX since users probably don't consider
+  // "extension preferences" a separate category of syncing.
+  // However, we also respect engine.extension-storage.force, which
+  // can be set to true or false, if a power user wants to customize
+  // the behavior despite the lack of UI.
+  const forced = Svc.Prefs.get(PREF_FORCE_ENABLE, undefined);
+  if (forced !== undefined) {
+    return forced;
+  }
+  return Svc.Prefs.get("engine.addons", false);
+}
+
+function setEngineEnabled(enabled) {
+  // This will be called by the engine manager when declined on another device.
+  // Things will go a bit pear-shaped if the engine manager tries to end up
+  // with 'addons' and 'extension-storage' in different states - however, this
+  // *can* happen given we support the `engine.extension-storage.force`
+  // preference. So if that pref exists, we set it to this value. If that pref
+  // doesn't exist, we just ignore it and hope that the 'addons' engine is also
+  // going to be set to the same state.
+  if (Svc.Prefs.has(PREF_FORCE_ENABLE)) {
+    Svc.Prefs.set(PREF_FORCE_ENABLE, enabled);
+  }
+}
+
+// A "bridged engine" to our webext-storage component.
+function ExtensionStorageEngineBridge(service) {
+  let bridge = StorageSyncService.getInterface(Ci.mozIBridgedSyncEngine);
+  BridgedEngine.call(this, bridge, "Extension-Storage", service);
+
+  let app_services_logger = Cc["@mozilla.org/appservices/logger;1"].getService(
+    Ci.mozIAppServicesLogger
+  );
+  let logger_target = "app-services:webext_storage:sync";
+  app_services_logger.register(logger_target, new LogAdapter(this._log));
+}
+
+ExtensionStorageEngineBridge.prototype = {
+  __proto__: BridgedEngine.prototype,
+  syncPriority: 10,
+
+  // Used to override the engine name in telemetry, so that we can distinguish .
+  overrideTelemetryName: "rust-webext-storage",
+
+  _notifyPendingChanges() {
+    return new Promise(resolve => {
+      this._bridge
+        .QueryInterface(Ci.mozISyncedExtensionStorageArea)
+        .fetchPendingSyncChanges({
+          QueryInterface: ChromeUtils.generateQI([
+            "mozIExtensionStorageListener",
+            "mozIExtensionStorageCallback",
+          ]),
+          onChanged: (extId, json) => {
+            try {
+              extensionStorageSync.notifyListeners(extId, JSON.parse(json));
+            } catch (ex) {
+              this._log.warn(
+                `Error notifying change listeners for ${extId}`,
+                ex
+              );
+            }
+          },
+          handleSuccess: resolve,
+          handleError: (code, message) => {
+            this._log.warn(
+              "Error fetching pending synced changes",
+              message,
+              code
+            );
+            resolve();
+          },
+        });
+    });
+  },
+
+  _takeMigrationInfo() {
+    return new Promise((resolve, reject) => {
+      this._bridge
+        .QueryInterface(Ci.mozIExtensionStorageArea)
+        .takeMigrationInfo({
+          QueryInterface: ChromeUtils.generateQI([
+            "mozIExtensionStorageCallback",
+          ]),
+          handleSuccess: result => {
+            resolve(result ? JSON.parse(result) : null);
+          },
+          handleError: (code, message) => {
+            this._log.warn("Error fetching migration info", message, code);
+            // `takeMigrationInfo` doesn't actually perform the migration,
+            // just reads (and clears) any data stored in the DB from the
+            // previous migration.
+            //
+            // Any errors here are very likely occurring a good while
+            // after the migration ran, so we just warn and pretend
+            // nothing was there.
+            resolve(null);
+          },
+        });
+    });
+  },
+
+  async _syncStartup() {
+    let result = await super._syncStartup();
+    let info = await this._takeMigrationInfo();
+    if (info) {
+      Observers.notify("weave:telemetry:migration", info, "webext-storage");
+    }
+    return result;
+  },
+
+  async _processIncoming() {
+    await super._processIncoming();
+    try {
+      await this._notifyPendingChanges();
+    } catch (ex) {
+      // Failing to notify `storage.onChanged` observers is bad, but shouldn't
+      // interrupt syncing.
+      this._log.warn("Error notifying about synced changes", ex);
+    }
+  },
+
+  get enabled() {
+    return getEngineEnabled();
+  },
+  set enabled(enabled) {
+    setEngineEnabled(enabled);
+  },
+};
+
+/**
+ *****************************************************************************
+ *
+ * Deprecated support for Kinto
+ *
+ *****************************************************************************
+ */
+
+/**
+ * The Engine that manages syncing for the web extension "storage"
+ * API, and in particular ext.storage.sync.
+ *
+ * ext.storage.sync is implemented using Kinto, so it has mechanisms
+ * for syncing that we do not need to integrate in the Firefox Sync
+ * framework, so this is something of a stub.
+ */
+function ExtensionStorageEngineKinto(service) {
+  SyncEngine.call(this, "Extension-Storage", service);
+  XPCOMUtils.defineLazyPreferenceGetter(
+    this,
+    "_skipPercentageChance",
+    "services.sync.extension-storage.skipPercentageChance",
+    0
+  );
+}
+ExtensionStorageEngineKinto.prototype = {
+  __proto__: SyncEngine.prototype,
+  _trackerObj: ExtensionStorageTracker,
+  // we don't need these since we implement our own sync logic
+  _storeObj: undefined,
+  _recordObj: undefined,
+
+  syncPriority: 10,
+  allowSkippedRecord: false,
+
+  async _sync() {
+    return extensionStorageSyncKinto.syncAll();
+  },
+
+  get enabled() {
+    return getEngineEnabled();
+  },
+  // We only need the enabled setter for the edge-case where info/collections
+  // has `extension-storage` - which could happen if the pref to flip the new
+  // engine on was once set but no longer is.
+  set enabled(enabled) {
+    setEngineEnabled(enabled);
+  },
+
+  _wipeClient() {
+    return extensionStorageSyncKinto.clearAll();
+  },
+
+  shouldSkipSync(syncReason) {
+    if (syncReason == "user" || syncReason == "startup") {
+      this._log.info(
+        `Not skipping extension storage sync: reason == ${syncReason}`
+      );
+      // Always sync if a user clicks the button, or if we're starting up.
+      return false;
+    }
+    // Ensure this wouldn't cause a resync...
+    if (this._tracker.score >= MULTI_DEVICE_THRESHOLD) {
+      this._log.info(
+        "Not skipping extension storage sync: Would trigger resync anyway"
+      );
+      return false;
+    }
+
+    let probability = this._skipPercentageChance / 100.0;
+    // Math.random() returns a value in the interval [0, 1), so `>` is correct:
+    // if `probability` is 1 skip every time, and if it's 0, never skip.
+    let shouldSkip = probability > Math.random();
+
+    this._log.info(
+      `Skipping extension-storage sync with a chance of ${probability}: ${shouldSkip}`
+    );
+    return shouldSkip;
+  },
+};
+
+function ExtensionStorageTracker(name, engine) {
+  Tracker.call(this, name, engine);
+  this._ignoreAll = false;
+}
+ExtensionStorageTracker.prototype = {
+  __proto__: Tracker.prototype,
+
+  get ignoreAll() {
+    return this._ignoreAll;
+  },
+
+  set ignoreAll(value) {
+    this._ignoreAll = value;
+  },
+
+  onStart() {
+    Svc.Obs.add("ext.storage.sync-changed", this.asyncObserver);
+  },
+
+  onStop() {
+    Svc.Obs.remove("ext.storage.sync-changed", this.asyncObserver);
+  },
+
+  async observe(subject, topic, data) {
+    if (this.ignoreAll) {
+      return;
+    }
+
+    if (topic !== "ext.storage.sync-changed") {
+      return;
+    }
+
+    // Single adds, removes and changes are not so important on their
+    // own, so let's just increment score a bit.
+    this.score += SCORE_INCREMENT_MEDIUM;
+  },
+};