Bug 1848200 - add migration flag to init

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 [Full changelog](https://github.com/mozilla/glean.js/compare/v2.0.0...main)
 
+* [#1751](https://github.com/mozilla/glean.js/pull/1751): Add a migration flag to initialize. If not explicitly set in the `config` object the migration from IndexedDB to LocalStorage will not occur. **The only projects that should ever set this flag are those that have used Glean.js in production with a version <v2.0.0 and have upgraded.**
+
 # v2.0.0 (2023-08-03)
 
 [Full changelog](https://github.com/mozilla/glean.js/compare/v1.4.0...v2.0.0)

glean/src/core/config.ts

@@ -56,6 +56,9 @@ export interface ConfigurationInterface {
   readonly osVersion?: string,
   // The build date, provided by glean_parser
   readonly buildDate?: Date,
+  // Migrate from legacy storage (IndexedDB) to the new one (LocalStorage).
+  // This should only be true for older projects that have existing data in IndexedDB.
+  readonly migrateFromLegacyStorage?: boolean,
 }
 
 // Important: the `Configuration` should only be used internally by the Glean singleton.
@@ -68,6 +71,7 @@ export class Configuration implements ConfigurationInterface {
   readonly osVersion?: string;
   readonly buildDate?: Date;
   readonly maxEvents: number;
+  readonly migrateFromLegacyStorage?: boolean;
 
   // Debug configuration.
   debug: DebugOptions;
@@ -82,6 +86,7 @@ export class Configuration implements ConfigurationInterface {
     this.osVersion = config?.osVersion;
     this.buildDate = config?.buildDate;
     this.maxEvents = config?.maxEvents || DEFAULT_MAX_EVENTS;
+    this.migrateFromLegacyStorage = config?.migrateFromLegacyStorage;
 
     this.debug = {};
 

glean/src/core/glean/sync.ts

@@ -2,8 +2,10 @@
  * 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/. */
 
-import { CLIENT_INFO_STORAGE, KNOWN_CLIENT_ID } from "../constants.js";
 import type { ConfigurationInterface } from "../config.js";
+import type PlatformSync from "../../platform/sync.js";
+
+import { CLIENT_INFO_STORAGE, KNOWN_CLIENT_ID } from "../constants.js";
 import { Configuration } from "../config.js";
 import PingUploadManager from "../upload/manager/sync.js";
 import { isBoolean, isString, sanitizeApplicationId } from "../utils.js";
@@ -13,7 +15,6 @@ import { DatetimeMetric } from "../metrics/types/datetime.js";
 import CorePings from "../internal_pings.js";
 import { registerPluginToEvent } from "../events/utils/sync.js";
 import ErrorManagerSync from "../error/sync.js";
-import type PlatformSync from "../../platform/sync.js";
 import { Lifetime } from "../metrics/lifetime.js";
 import { Context } from "../context.js";
 import log, { LoggingLevel } from "../log.js";
@@ -42,7 +43,15 @@ namespace Glean {
    */
   function onUploadEnabled(): void {
     Context.uploadEnabled = true;
-    (Context.coreMetrics as CoreMetricsSync).initialize();
+  }
+
+  /**
+   * Initialize core metrics: client_id, first_run_date, os, etc.
+   *
+   * @param migrateFromLegacy Whether or not to migrate data from legacy storage.
+   */
+  function initializeCoreMetrics(migrateFromLegacy?: boolean): void {
+    (Context.coreMetrics as CoreMetricsSync).initialize(migrateFromLegacy);
   }
 
   /**
@@ -246,6 +255,7 @@ namespace Glean {
       // If upload is enabled,
       // just follow the normal code path to instantiate the core metrics.
       onUploadEnabled();
+      initializeCoreMetrics(config?.migrateFromLegacyStorage);
     } else {
       // If upload is disabled, and we've never run before, only set the
       // client_id to KNOWN_CLIENT_ID, but do not send a deletion request
@@ -317,6 +327,7 @@ namespace Glean {
     if (Context.uploadEnabled !== flag) {
       if (flag) {
         onUploadEnabled();
+        initializeCoreMetrics(Context.config.migrateFromLegacyStorage);
       } else {
         onUploadDisabled(false);
       }

glean/src/core/internal_metrics/sync.ts

@@ -125,7 +125,7 @@ export class CoreMetricsSync {
     );
   }
 
-  initialize(): void {
+  initialize(migrateFromLegacyStorage?: boolean): void {
     // The "sync" version of Glean.js is only meant to be used in the browser.
     // If we cannot access the window object, then we are unable to store
     // any of the metric data in `localStorage`.
@@ -140,11 +140,9 @@ export class CoreMetricsSync {
     // Currently we are interested in migrating two things
     // 1. The client_id - consistent clientId across all sessions.
     // 2. The first_run_date - the date when the client was first run.
-
-    // The migration is done only once per client. The flag is set in
-    // LocalStorage to indicate that the migration has been completed.
-    const migrationFlag = localStorage.getItem("GLEAN_MIGRATION_FLAG");
-    if (migrationFlag !== "1") {
+    if (!!migrateFromLegacyStorage && localStorage.getItem("GLEAN_MIGRATION_FLAG") !== "1") {
+      // The migration is done only once per client. The flag is set in
+      // LocalStorage to indicate that the migration has been completed.
       this.migrateCoreMetricsFromIdb();
       localStorage.setItem("GLEAN_MIGRATION_FLAG", "1");
     } else {