Bug 1617133 - Report error names to Telemetry on Nightly r=glasserc

Differential Revision: https://phabricator.services.mozilla.com/D64560

--HG--
extra : moz-landing-system : lando

services/settings/RemoteSettingsClient.jsm

@@ -6,6 +6,9 @@
 
 var EXPORTED_SYMBOLS = ["RemoteSettingsClient"];
 
+const { AppConstants } = ChromeUtils.import(
+  "resource://gre/modules/AppConstants.jsm"
+);
 const { XPCOMUtils } = ChromeUtils.import(
   "resource://gre/modules/XPCOMUtils.jsm"
 );
@@ -429,6 +432,7 @@ class RemoteSettingsClient extends EventEmitter {
     let importedFromDump = [];
     const startedAt = new Date();
     let reportStatus = null;
+    let thrownError = null;
     try {
       // If network is offline, we can't synchronize.
       if (Utils.isOffline) {
@@ -626,6 +630,7 @@ class RemoteSettingsClient extends EventEmitter {
         );
       }
     } catch (e) {
+      thrownError = e;
       // If no Telemetry status was determined yet (ie. outside sync step),
       // then introspect error, default status at this step is UNKNOWN.
       if (reportStatus == null) {
@@ -641,11 +646,34 @@ class RemoteSettingsClient extends EventEmitter {
         reportStatus = UptakeTelemetry.STATUS.SUCCESS;
       }
       // Report success/error status to Telemetry.
-      await UptakeTelemetry.report(TELEMETRY_COMPONENT, reportStatus, {
+      let reportArgs = {
         source: this.identifier,
         trigger,
         duration: durationMilliseconds,
-      });
+      };
+      // In Bug 1617133, we will try to break down specific errors into
+      // more precise statuses by reporting the JavaScript error name
+      // ("TypeError", etc.) to Telemetry on Nightly.
+      if (
+        thrownError !== null &&
+        AppConstants.NIGHTLY_BUILD &&
+        [
+          UptakeTelemetry.STATUS.SYNC_ERROR,
+          UptakeTelemetry.STATUS.CUSTOM_1_ERROR, // IndexedDB.
+          UptakeTelemetry.STATUS.UNKNOWN_ERROR,
+        ].includes(reportStatus)
+      ) {
+        // List of possible error names for IndexedDB:
+        // https://searchfox.org/mozilla-central/rev/49ed791/dom/base/DOMException.cpp#28-53
+        reportArgs = { ...reportArgs, errorName: thrownError.name };
+      }
+
+      await UptakeTelemetry.report(
+        TELEMETRY_COMPONENT,
+        reportStatus,
+        reportArgs
+      );
+
       console.debug(`${this.identifier} sync status is ${reportStatus}`);
       this._syncRunning = false;
     }

services/settings/test/unit/test_remote_settings.js

@@ -729,6 +729,39 @@ add_task(async function test_telemetry_reports_indexeddb_as_custom_1() {
 });
 add_task(clear_state);
 
+add_task(async function test_telemetry_reports_error_name_as_event_nightly() {
+  const backup = client.openCollection;
+  client.openCollection = () => {
+    const e = new Error("Some unknown error");
+    e.name = "ThrownError";
+    throw e;
+  };
+
+  await withFakeChannel("nightly", async () => {
+    try {
+      await client.maybeSync(2000);
+    } catch (e) {}
+
+    TelemetryTestUtils.assertEvents([
+      [
+        "uptake.remotecontent.result",
+        "uptake",
+        "remotesettings",
+        UptakeTelemetry.STATUS.UNKNOWN_ERROR,
+        {
+          source: client.identifier,
+          trigger: "manual",
+          duration: v => v >= 0,
+          errorName: "ThrownError",
+        },
+      ],
+    ]);
+  });
+
+  client.openCollection = backup;
+});
+add_task(clear_state);
+
 add_task(async function test_bucketname_changes_when_bucket_pref_changes() {
   equal(client.bucketName, "main");
 

toolkit/components/telemetry/Events.yaml

@@ -1692,6 +1692,8 @@ uptake.remotecontent.result:
         The duration of the synchronization process in milliseconds.
       timestamp: >
         The current timestamp, received during synchronization.
+      errorName: >
+        An optional string with the error name attribute in case of failure.
     bug_numbers:
       - 1517469
     products: