🔊 Deduplicate telemetry events

DataDog · May 7, 2024 · c7546ff · c7546ff
1 parent 1ad9175
commit c7546ff
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Showing 2 changed files with 40 additions and 3 deletions.
diff --git a/packages/core/src/domain/telemetry/telemetry.spec.ts b/packages/core/src/domain/telemetry/telemetry.spec.ts
@@ -1,4 +1,5 @@
 import type { StackTrace } from '@datadog/browser-core'
+import { addTelemetryError } from '@datadog/browser-core'
 import { NO_ERROR_STACK_PRESENT_MESSAGE } from '../error/error'
 import { callMonitored } from '../../tools/monitor'
 import type { ExperimentalFeature } from '../../tools/experimentalFeatures'
@@ -20,6 +21,7 @@ function startAndSpyTelemetry(configuration?: Partial<Configuration>) {
   const telemetry = startTelemetry(TelemetryService.RUM, {
     maxTelemetryEventsPerPage: 7,
     telemetrySampleRate: 100,
+    telemetryUsageSampleRate: 100,
     ...configuration,
   } as Configuration)
   const notifySpy = jasmine.createSpy('notified')
@@ -181,6 +183,34 @@ describe('telemetry', () => {
     })
   })
 
+  describe('deduplicating', () => {
+    it('should discard already seen telemetry', () => {
+      const { notifySpy } = startAndSpyTelemetry()
+      const fooError = new Error('foo')
+      const barError = new Error('bar')
+
+      addTelemetryError(fooError)
+      addTelemetryError(fooError)
+      addTelemetryError(barError)
+
+      expect(notifySpy).toHaveBeenCalledTimes(2)
+      expect(notifySpy.calls.argsFor(0)[0].telemetry.message).toEqual('foo')
+      expect(notifySpy.calls.argsFor(1)[0].telemetry.message).toEqual('bar')
+    })
+
+    it('should not consider a discarded event for the maxTelemetryEventsPerPage', () => {
+      const { notifySpy } = startAndSpyTelemetry({ maxTelemetryEventsPerPage: 2 })
+
+      addTelemetryUsage({ feature: 'stop-session' })
+      addTelemetryUsage({ feature: 'stop-session' })
+      addTelemetryUsage({ feature: 'start-session-replay-recording' })
+
+      expect(notifySpy).toHaveBeenCalledTimes(2)
+      expect(notifySpy.calls.argsFor(0)[0].telemetry.usage.feature).toEqual('stop-session')
+      expect(notifySpy.calls.argsFor(1)[0].telemetry.usage.feature).toEqual('start-session-replay-recording')
+    })
+  })
+
   describe('excluded sites', () => {
     ;[
       { site: INTAKE_SITE_US1_FED, enabled: false },

diff --git a/packages/core/src/domain/telemetry/telemetry.ts b/packages/core/src/domain/telemetry/telemetry.ts
@@ -64,6 +64,7 @@ let onRawTelemetryEventCollected: ((event: RawTelemetryEvent) => void) | undefin
 export function startTelemetry(telemetryService: TelemetryService, configuration: Configuration): Telemetry {
   let contextProvider: () => Context
   const observable = new Observable<TelemetryEvent & Context>()
+  const alreadySeenEvents = new Set<string>()
 
   const telemetryEnabled =
     !includes(TELEMETRY_EXCLUDED_SITES, configuration.site) && performDraw(configuration.telemetrySampleRate)
@@ -76,10 +77,17 @@ export function startTelemetry(telemetryService: TelemetryService, configuration
 
   const runtimeEnvInfo = getRuntimeEnvInfo()
   onRawTelemetryEventCollected = (rawEvent: RawTelemetryEvent) => {
-    if (telemetryEnabledPerType[rawEvent.type!]) {
+    const stringifiedEvent = jsonStringify(rawEvent)!
+    if (
+      telemetryEnabledPerType[rawEvent.type!] &&
+      telemetryConfiguration.sentEventCount < telemetryConfiguration.maxEventsPerPage &&
+      !alreadySeenEvents.has(stringifiedEvent)
+    ) {
       const event = toTelemetryEvent(telemetryService, rawEvent, runtimeEnvInfo)
       observable.notify(event)
       sendToExtension('telemetry', event)
+      alreadySeenEvents.add(stringifiedEvent)
+      telemetryConfiguration.sentEventCount += 1
     }
   }
   startMonitorErrorCollection(addTelemetryError)
@@ -197,8 +205,7 @@ export function addTelemetryUsage(usage: RawTelemetryUsage) {
 }
 
 function addTelemetry(event: RawTelemetryEvent) {
-  if (onRawTelemetryEventCollected && telemetryConfiguration.sentEventCount < telemetryConfiguration.maxEventsPerPage) {
-    telemetryConfiguration.sentEventCount += 1
+  if (onRawTelemetryEventCollected) {
     onRawTelemetryEventCollected(event)
   }
 }