Enable Customer SDK Stats by JacksonWeber · Pull Request #2707 · microsoft/ApplicationInsights-JS

JacksonWeber · 2026-02-21T00:25:52Z

This pull request introduces SDK statistics tracking and enhances event notification capabilities in the Application Insights SDK. The main focus is on enabling periodic SDK stats reporting, improving notification for telemetry event lifecycle (including retries), and supporting these features with new interfaces and configuration options.

SDK Statistics Tracking:

Added support for SDK statistics reporting, including new configuration options (SDK_STATS, SDK_STATS_VERSION, SDK_STATS_FLUSH_INTERVAL) and default enablement in the config. The stats listener is registered during initialization and properly cleaned up on unload. (AISKU/src/AISku.ts [1] [2] [3] [4] [5] [6]
Introduced ISdkStatsNotifCbk and related imports to facilitate SDK stats notification callbacks. (AISKU/src/AISku.ts AISKU/src/AISku.tsL14-R21)

Telemetry Event Notification Enhancements:

Extended the notification system to include a new eventsRetry event, allowing listeners to be notified when telemetry items are retried, along with the relevant HTTP status code. (shared/AppInsightsCore/src/constants/InternalConstants.ts [1] shared/AppInsightsCore/src/core/NotificationManager.ts [2] [3] [4]
Updated the Sender plugin to trigger notification callbacks for events sent, discarded, and retried, including logic to extract minimal telemetry items for notification purposes. (channels/applicationinsights-channel-js/src/Sender.ts [1] [2] [3] [4] [5]

Internal Data Structure Updates:

Added a bT (baseType) property to IInternalStorageItem for mapping telemetry types in SDK stats and notification extraction. (channels/applicationinsights-channel-js/src/Interfaces.ts [1] channels/applicationinsights-channel-js/src/Sender.ts [2]

These changes collectively improve observability, reliability, and extensibility of the telemetry pipeline, especially for SDK usage metrics and event retry handling.

shared/AppInsightsCore/src/core/SdkStatsNotificationCbk.ts

Copilot

Pull request overview

This pull request introduces comprehensive SDK statistics tracking and enhances the notification system to support telemetry retry events. The main objective is to enable periodic reporting of SDK usage metrics (success, dropped, and retry counts) and provide visibility into the complete telemetry lifecycle including retry scenarios.

Changes:

Adds eventsRetry notification callback to INotificationManager and INotificationListener interfaces for tracking telemetry retry events with HTTP status codes
Implements SdkStatsNotificationCbk - a notification listener that accumulates telemetry counts by type and periodically reports them as metrics
Integrates SDK stats listener into AISku with automatic initialization (enabled by default) and proper cleanup during unload
Updates Sender to trigger notifications for sent, discarded, and retried events, storing baseType in IInternalStorageItem for telemetry type mapping
Adds comprehensive unit tests for the SDK stats notification callback covering all major scenarios

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
shared/AppInsightsCore/src/interfaces/ai/INotificationManager.ts	Adds eventsRetry method signature to notification manager interface
shared/AppInsightsCore/src/interfaces/ai/INotificationListener.ts	Adds optional eventsRetry callback to listener interface
shared/AppInsightsCore/src/index.ts	Exports new SDK stats notification callback factory and interfaces
shared/AppInsightsCore/src/core/SdkStatsNotificationCbk.ts	New file implementing the SDK stats accumulator and periodic metric flushing logic
shared/AppInsightsCore/src/core/NotificationManager.ts	Implements eventsRetry notification dispatch to all registered listeners
shared/AppInsightsCore/src/constants/InternalConstants.ts	Adds STR_EVENTS_RETRY constant for the new notification type
shared/AppInsightsCore/Tests/Unit/src/aiunittests.ts	Registers new SDK stats notification callback test suite
shared/AppInsightsCore/Tests/Unit/src/ai/SdkStatsNotificationCbk.Tests.ts	New comprehensive test suite covering all SDK stats functionality
channels/applicationinsights-channel-js/src/Sender.ts	Adds notification triggers for sent/discarded/retry events and extracts telemetry items for notifications
channels/applicationinsights-channel-js/src/Interfaces.ts	Adds bT (baseType) property to IInternalStorageItem for telemetry type mapping
AISKU/src/AISku.ts	Integrates SDK stats listener with initialization, configuration, and unload handling

AISKU/src/AISku.ts

channels/applicationinsights-channel-js/src/Sender.ts

AISKU/src/AISku.ts

shared/AppInsightsCore/Tests/Unit/src/ai/SdkStatsNotificationCbk.Tests.ts

AISKU/src/AISku.ts

Copilot

Pull request overview

Copilot reviewed 11 out of 11 changed files in this pull request and generated 4 comments.

Copilot · 2026-02-25T20:31:59Z

channels/applicationinsights-channel-js/src/Sender.ts

+            function _extractTelemetryItems(payload: IInternalStorageItem[]): ITelemetryItem[] {
+                if (payload && payload.length) {
+                    let items: ITelemetryItem[] = [];
+                    arrForEach(payload, (p) => {
+                        if (p) {
+                            let baseType = p.bT || "EventData";
+                            items.push({ name: baseType, baseType: baseType } as ITelemetryItem);


The name field in extracted telemetry items is set to baseType (line 1427), which doesn't represent the actual telemetry item name. This creates synthetic items where name equals baseType (e.g., both set to "EventData"). While this may be intentional for notification purposes since the original name is not available in IInternalStorageItem, it could be misleading for listeners expecting accurate telemetry item information. Consider documenting this behavior in the function comment or using a more descriptive synthetic name pattern.

shared/AppInsightsCore/src/core/SdkStatsNotificationCbk.ts

Copilot · 2026-02-25T20:32:00Z

channels/applicationinsights-channel-js/src/Sender.ts

             * error handler
             */
-            _self._onError = (payload: IInternalStorageItem[] | string[], message: string, event?: ErrorEvent) => {
+            _self._onError = (payload: IInternalStorageItem[] | string[], message: string, event?: ErrorEvent, statusCode?: number) => {


The public stub signature for _onError is missing the new statusCode parameter. The implementation at line 630 accepts a statusCode parameter, but the stub at line 1594 does not include it. Update the stub signature to include the optional statusCode parameter: public _onError(payload: string[] | IInternalStorageItem[], message: string, event?: ErrorEvent, statusCode?: number)

shared/AppInsightsCore/src/core/SdkStatsNotificationCbk.ts

MSNev · 2026-03-03T22:28:03Z

AISKU/src/AISku.ts

                    _core.initialize(_config, [ _sender, properties, dependencies, _analyticsPlugin, _cfgSyncPlugin], logger, notificationManager);

+                    // Register SDK Stats notification listener (on by default)
+                    if (isFeatureEnabled(SDK_STATS, _config, true)) {


This initialization should be inside the onConfigChange below so that if/when the configuration is changed (by the config feature fetch) this can be enabled / disabled on the fly without needing to re-initialize the SDK (a new page load)

Moved the initialization.

MSNev · 2026-03-03T23:24:00Z

channels/applicationinsights-channel-js/src/Sender.ts

+                // Notify listeners of successful send
+                let mgr = _getNotifyMgr();
+                if (mgr) {
+                    let items = _extractTelemetryItems(payload);


Follow up PR -- lets try and minimize the need to call this, it might be a large PR as it will most likely require changing the whole serialization process (like we do in 1ds-post-js) where we convert to a string as late as possible so at this level we are still playing with the objects -- there is a gotya around the persistence to the session storage / array storage today for this though.

MSNev · 2026-03-03T23:59:10Z

shared/AppInsightsCore/src/core/SdkStatsNotificationCbk.ts

+    /**
+     * The track function to call when flushing metrics. Typically core.track().
+     */
+    trk: (item: ITelemetryItem) => void;


I don't think you actually need this as it you pass the IAppInsightsCore instance that has the track function that is shared across both AI and 1DS

Changed ISdkStatsConfig.trk: (item: ITelemetryItem) => void to ISdkStatsConfig.core: IAppInsightsCore. All internal calls now use cfg.core.track(item) instead of cfg.trk(item). Updated AISku.ts initialization to pass core: _core instead of the trk wrapper function.

MSNev · 2026-03-04T00:02:48Z

AISKU/src/AISku.ts

+                            },
+                            lang: "JavaScript",
+                            ver: SDK_STATS_VERSION,
+                            int: SDK_STATS_FLUSH_INTERVAL


As one of the items is the interval which should be dynamic, I think we should really be passing the common sdkStats config (from the shared Config) or pass down the full config (IConfiguration) to this function and if we want to cache it internally in a local variable (still reading the PR) then we would need to use the onCfgChange() helper to listen to changes.

The interval is updated to be passed through the config and used in the createSdkStatsNotifCbk. Since the SDK stats listener is now created/destroyed inside onConfigChange, the interval should be updated by destroying and recreating the listener when config changes.

MSNev · 2026-03-04T00:03:38Z

shared/AppInsightsCore/src/core/SdkStatsNotificationCbk.ts

+    var _droppedCounts: { [code: string]: { [telType: string]: number } } = objCreate(null);
+    var _retryCounts: { [code: string]: { [telType: string]: number } } = objCreate(null);
+    var _timer: ITimerHandler;
+    var _interval = cfg.int || FLUSH_INTERVAL;


This should be the common dynamic config so we can change via the CDN callback

Addressed as part of the above change to make interval dynamic.

MSNev · 2026-03-04T00:16:08Z

shared/AppInsightsCore/src/core/SdkStatsNotificationCbk.ts

+                }
+            }
+        }
+        _ensureTimer();


unlikely, but minor. Only call if a new value was set

Added a changed flag in _incSuccess to ensure this isn't changed if a new value isn't set.

MSNev · 2026-03-04T00:19:06Z

shared/AppInsightsCore/src/core/SdkStatsNotificationCbk.ts

+        if (!_safeKey(code)) {
+            return;
+        }
+        var bucket: { [telType: string]: number };


this could be simplified slightly and avoid the call to objHasOwn

let bucket = _droppedCount[code]; if (!bucket) { bucket = _droppedCount[code] = objCreate(null); }

Replaced the objHasOwn + if/else pattern with the simplified pattern in the new _incBucketed helper function

MSNev · 2026-03-04T00:20:48Z

shared/AppInsightsCore/src/core/SdkStatsNotificationCbk.ts

+            return;
+        }
+        var bucket: { [telType: string]: number };
+        if (objHasOwn(_retryCounts, code)) {


same as above

Addressed in above comment.

MSNev · 2026-03-04T00:22:03Z

shared/AppInsightsCore/src/core/SdkStatsNotificationCbk.ts

+        _ensureTimer();
+    }
+
+    function _incRetry(items: ITelemetryItem[], code: string) {


minification optimization, this function and _incDropped look mostly the same, could put the bulk in a common function and then pass the differences as parameters.

Merged _incDropped and _incRetry into a single _incBucketed(counters, items, code) helper function.

MSNev · 2026-03-04T00:24:22Z

shared/AppInsightsCore/src/core/SdkStatsNotificationCbk.ts

+    function _createMetric(name: string, value: number, props: { [key: string]: any }): ITelemetryItem {
+        // Merge standard dimensions
+        props[P_LANG] = cfg.lang;
+        props[P_VER] = cfg.ver;


Minification optimization: As these are only actually used once, it's better to just use the names inline instead of creating constants.

The build system "counts" all objects that are used more than the number of bytes saved by using local variables and will automatically translate (using the DynamicConstants) as part of the build, reusing the same constant across the entire bundle / package.

Removed the P_LANG, P_VER, P_COMPUTE, P_TEL_TYPE, P_DROP_CODE, and P_RETRY_CODE constants. Replaced all usages with inline string literals ("language", "version", "computeType", "telemetry_type", "drop.code", "retry.code")

MSNev · 2026-03-04T00:27:06Z

shared/AppInsightsCore/src/core/SdkStatsNotificationCbk.ts

+
+        return {
+            name: name,
+            baseType: "MetricData",


There is now an exported constant MetricDataType for the "MetricData" so could use that instead (Total bundle minification stuff)

Imported MetricDataType from "../telemetry/ai/DataTypes" and replaced the inline "MetricData" string in _createMetric with the MetricDataType constant.

MSNev · 2026-03-04T00:28:27Z

shared/AppInsightsCore/src/core/SdkStatsNotificationCbk.ts

+        }
+
+        // Flush dropped counts
+        for (code in _droppedCounts) {


Looks like these could be collapsed as well into a single helper function

Created a unified helper to handle this, _flushBucketed().

github-advanced-security bot found potential problems Feb 24, 2026

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shared/AppInsightsCore/src/core/SdkStatsNotificationCbk.ts Fixed Show fixed Hide fixed

shared/AppInsightsCore/src/core/SdkStatsNotificationCbk.ts Fixed Show fixed Hide fixed

JacksonWeber marked this pull request as ready for review February 24, 2026 18:07

JacksonWeber requested a review from a team as a code owner February 24, 2026 18:07

Copilot AI review requested due to automatic review settings February 24, 2026 18:07

Copilot started reviewing on behalf of JacksonWeber February 24, 2026 18:08 View session

Copilot AI reviewed Feb 24, 2026

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JacksonWeber changed the title ~~Jacksonweber/enable customer sdk stats~~ Enable Customer SDK Stats Feb 24, 2026

JacksonWeber added 9 commits February 25, 2026 12:20

Enable customer sdk stats.

21e0853

Delete customer_facing_sdk_stats_spec.md

122843e

Delete customer_sdk_stats_implementation.md

5b75594

Update flush of sdk stats.

407adf4

Fix possible prototype pollution bug.

7af6493

Update to resolve prototype pollution issue.

c9d1d98

Add tests.

14ef500

Resolve prototype-polluting assignment issues.

58a56d2

Address github comments.

7eaafe0

JacksonWeber force-pushed the jacksonweber/enable-customer-sdk-stats branch from 9ed6655 to 7eaafe0 Compare February 25, 2026 20:21

JacksonWeber changed the base branch from beta to main February 25, 2026 20:22

JacksonWeber requested a review from Copilot February 25, 2026 20:23

Copilot started reviewing on behalf of JacksonWeber February 25, 2026 20:24 View session

Copilot AI reviewed Feb 25, 2026

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JacksonWeber added 4 commits February 25, 2026 13:54

Update SdkStatsNotificationCbk.ts

1325688

Update Sender.ts

3321b4c

Add notification of retry events in post-channel.

69304a6

Add extra length check.

d0cbd08

lzchen approved these changes Mar 3, 2026

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MSNev reviewed Mar 3, 2026

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MSNev reviewed Mar 4, 2026

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JacksonWeber added 3 commits March 4, 2026 14:52

Move initialization inside onConfigChange.

151ea67

Address PR comments.

bc9edea

Update SdkStatsNotificationCbk.ts

056eaf9

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JacksonWeber commented Feb 21, 2026

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