add histogram for gpa fetch

src/core/metrics.ts

@@ -37,6 +37,7 @@ enum METRIC_TYPES {
 	runtime_specs = 'runtime_specs',
 	endpoint_response_times_histogram = 'endpoint_response_times_histogram',
 	endpoint_response_status = 'endpoint_response_status',
+	gpa_fetch_duration = 'endpoint_response_status',
 	health_status = 'health_status',
 }
 
@@ -70,6 +71,12 @@ const meterProvider = new MeterProvider({
 			meterName,
 			aggregation: createHistogramBuckets(0, 20, 30),
 		}),
+		new View({
+			instrumentName: METRIC_TYPES.gpa_fetch_duration,
+			instrumentType: InstrumentType.HISTOGRAM,
+			meterName,
+			aggregation: createHistogramBuckets(0, 500, 20),
+		}),
 	],
 });
 meterProvider.addMetricReader(exporter);
@@ -109,6 +116,13 @@ const endpointResponseTimeHistogram = meter.createHistogram(
 		unit: 'ms',
 	}
 );
+const gpaFetchDurationHistogram = meter.createHistogram(
+	METRIC_TYPES.gpa_fetch_duration,
+	{
+		description: 'Duration of GPA fetches',
+		unit: 'ms',
+	}
+);
 
 const responseStatusCounter = meter.createCounter(
 	METRIC_TYPES.endpoint_response_status,
@@ -170,6 +184,7 @@ const handleHealthCheck = (slotSource: SlotSource) => {
 
 export {
 	endpointResponseTimeHistogram,
+	gpaFetchDurationHistogram,
 	responseStatusCounter,
 	handleHealthCheck,
 };

src/index.ts

@@ -33,7 +33,7 @@ import {
 import { logger, setLogLevel } from './utils/logger';
 
 import * as http from 'http';
-import { handleHealthCheck } from './core/metrics';
+import { gpaFetchDurationHistogram, handleHealthCheck } from './core/metrics';
 import { handleResponseTime } from './core/middleware';
 import {
 	SubscriberLookup,
@@ -279,7 +279,9 @@ const main = async () => {
 	if (useWebsocket && !FEATURE_FLAGS.DISABLE_GPA_REFRESH) {
 		const recursiveFetch = (delay = WS_FALLBACK_FETCH_INTERVAL) => {
 			setTimeout(() => {
+				const startFetch = Date.now();
 				dlobProvider.fetch().then(() => {
+					gpaFetchDurationHistogram.record(Date.now() - startFetch);
 					// eslint-disable-next-line @typescript-eslint/no-unused-vars
 					recursiveFetch();
 				});