Bug 1465129 - Collect telemetry data related to the storage.local "JSONFile to IDBBackend" data migrations. r=mixedpuppy

MozReview-Commit-ID: 3iGv5XkqeA3

--HG--
extra : rebase_source : fc18cd0c43c3930a5fbac3ed86c31835e16bc170

toolkit/components/extensions/ExtensionStorageIDB.jsm

@@ -27,6 +27,7 @@ XPCOMUtils.defineLazyGetter(this, "WEBEXT_STORAGE_USER_CONTEXT_ID", () => {
 const IDB_NAME = "webExtensions-storage-local";
 const IDB_DATA_STORENAME = "storage-local-data";
 const IDB_VERSION = 1;
+const IDB_MIGRATE_RESULT_HISTOGRAM = "WEBEXT_STORAGE_LOCAL_IDB_MIGRATE_RESULT_COUNT";
 
 // Whether or not the installed extensions should be migrated to the storage.local IndexedDB backend.
 const BACKEND_ENABLED_PREF = "extensions.webextensions.ExtensionStorageIDB.enabled";
@@ -238,6 +239,7 @@ async function migrateJSONFileData(extension, storagePrincipal) {
   let hasEmptyIDB;
   let oldDataRead = false;
   let migrated = false;
+  let histogram = Services.telemetry.getHistogramById(IDB_MIGRATE_RESULT_HISTOGRAM);
 
   try {
     idbConn = await ExtensionStorageLocalIDB.openForPrincipal(storagePrincipal);
@@ -279,6 +281,9 @@ async function migrateJSONFileData(extension, storagePrincipal) {
       // the data migration promise explicitly (which would prevent the new backend
       // from being enabled for this session).
       Services.qms.clearStoragesForPrincipal(storagePrincipal);
+
+      histogram.add("failure");
+
       throw err;
     }
   } finally {
@@ -290,6 +295,8 @@ async function migrateJSONFileData(extension, storagePrincipal) {
     }
   }
 
+  histogram.add("success");
+
   // If the IDB backend has been enabled, try to remove the old storage.local data file,
   // but keep using the selected backend even if it fails to be removed.
   if (oldStorageExists && migrated) {
@@ -307,6 +314,7 @@ async function migrateJSONFileData(extension, storagePrincipal) {
  */
 this.ExtensionStorageIDB = {
   BACKEND_ENABLED_PREF,
+  IDB_MIGRATE_RESULT_HISTOGRAM,
 
   // Map<extension-id, Set<Function>>
   listeners: new Map(),

toolkit/components/extensions/test/xpcshell/test_ext_storage_idb_data_migration.js

@@ -6,13 +6,16 @@
 // from the JSONFile backend to the IDB backend.
 
 ChromeUtils.import("resource://gre/modules/XPCOMUtils.jsm");
+ChromeUtils.import("resource://gre/modules/ExtensionStorage.jsm");
+ChromeUtils.import("resource://gre/modules/ExtensionStorageIDB.jsm");
 
 XPCOMUtils.defineLazyModuleGetters(this, {
-  ExtensionStorage: "resource://gre/modules/ExtensionStorage.jsm",
-  ExtensionStorageIDB: "resource://gre/modules/ExtensionStorageIDB.jsm",
   OS: "resource://gre/modules/osfile.jsm",
 });
 
+const {IDB_MIGRATE_RESULT_HISTOGRAM} = ExtensionStorageIDB;
+const CATEGORIES = ["success", "failure"];
+
 async function createExtensionJSONFileWithData(extensionId, data) {
   await ExtensionStorage.set(extensionId, data);
   const jsonFile = await ExtensionStorage.getFile(extensionId);
@@ -23,6 +26,20 @@ async function createExtensionJSONFileWithData(extensionId, data) {
   return {jsonFile, oldStorageFilename};
 }
 
+function clearMigrationHistogram() {
+  const histogram = Services.telemetry.getHistogramById(IDB_MIGRATE_RESULT_HISTOGRAM);
+  histogram.clear();
+  equal(histogram.snapshot().sum, 0,
+        `No data recorded for histogram ${IDB_MIGRATE_RESULT_HISTOGRAM}`);
+}
+
+function assertMigrationHistogramCount(category, expectedCount) {
+  const histogram = Services.telemetry.getHistogramById(IDB_MIGRATE_RESULT_HISTOGRAM);
+
+  equal(histogram.snapshot().counts[CATEGORIES.indexOf(category)], expectedCount,
+        `Got the expected count on category "${category}" for histogram ${IDB_MIGRATE_RESULT_HISTOGRAM}`);
+}
+
 add_task(async function setup() {
   Services.prefs.setBoolPref(ExtensionStorageIDB.BACKEND_ENABLED_PREF, true);
 });
@@ -56,6 +73,8 @@ add_task(async function test_storage_local_data_migration() {
     browser.test.sendMessage("storage-local-data-migrated");
   }
 
+  clearMigrationHistogram();
+
   let extension = ExtensionTestUtils.loadExtension({
     manifest: {
       permissions: ["storage"],
@@ -82,6 +101,9 @@ add_task(async function test_storage_local_data_migration() {
   equal(await OS.File.exists(oldStorageFilename), false,
         "The old json storage file should have been removed");
 
+  assertMigrationHistogramCount("success", 1);
+  assertMigrationHistogramCount("failure", 0);
+
   await extension.unload();
 });
 
@@ -110,13 +132,15 @@ add_task(async function test_storage_local_corrupted_data_migration() {
     const storedData = await browser.storage.local.get();
 
     browser.test.assertEq(Object.keys(storedData).length, 0,
-                          "No data should be found found on invalid data migration");
+                          "No data should be found on invalid data migration");
 
     await browser.storage.local.set({"test_key_string_on_IDBBackend": "expected-value"});
 
     browser.test.sendMessage("storage-local-data-migrated-and-set");
   }
 
+  clearMigrationHistogram();
+
   let extension = ExtensionTestUtils.loadExtension({
     manifest: {
       permissions: ["storage"],
@@ -143,6 +167,11 @@ add_task(async function test_storage_local_corrupted_data_migration() {
   equal(await OS.File.exists(`${oldStorageFilename}.corrupt`), true,
         "The old json storage should still be available if failed to be read");
 
+  // The extension is still migrated successfully to the new backend if the file from the
+  // original json file was corrupted.
+  assertMigrationHistogramCount("success", 1);
+  assertMigrationHistogramCount("failure", 0);
+
   await extension.unload();
 });
 

toolkit/components/telemetry/Histograms.json

@@ -13439,7 +13439,7 @@
     "n_buckets": 100,
     "description": "The amount of time it takes to perform a set via storage.local using the JSONFile backend."
   },
-    "WEBEXT_STORAGE_LOCAL_IDB_GET_MS": {
+  "WEBEXT_STORAGE_LOCAL_IDB_GET_MS": {
     "record_in_processes": ["main", "content"],
     "alert_emails": ["addons-dev-internal@mozilla.com"],
     "bug_numbers": [1465120],
@@ -13461,6 +13461,16 @@
     "n_buckets": 100,
     "description": "The amount of time it takes to perform a set via storage.local using the IndexedDB backend."
   },
+  "WEBEXT_STORAGE_LOCAL_IDB_MIGRATE_RESULT_COUNT": {
+    "record_in_processes": ["main"],
+    "bug_numbers": [1465129],
+    "alert_emails": ["addons-dev-internal@mozilla.com"],
+    "expires_in_version": "67",
+    "kind": "categorical",
+    "labels": ["success", "failure"],
+    "releaseChannelCollection": "opt-out",
+    "description": "The number of times a storage.local backend data migration has been completed and results in one of the categories."
+  },
   "EXTENSION_UPDATE_TYPE": {
     "record_in_processes": ["main"],
     "alert_emails": ["addons-dev-internal@mozilla.com"],