⚗️ Partial view updates — batch optimizations (#4807)

Author: mormubis

packages/browser-core/src/transport/batch.ts

@@ -17,6 +17,7 @@ import type { FlushEvent, FlushReason, UrgentFlushReason } from './flushControll
 export const MESSAGE_BYTES_LIMIT = 256 * ONE_KIBI_BYTE
 
 export interface Batch {
+  isEmpty: boolean
   add: (message: Context) => void
   upsert: (message: Context, key: string) => void
   forceFlush: (reason: FlushReason) => void
@@ -115,6 +116,9 @@ export function createBatch({
   }
 
   return {
+    get isEmpty() {
+      return flushController.messagesCount === 0
+    },
     add: addOrUpdate,
     upsert: addOrUpdate,
     prepareUrgentFlushObservable: flushController.prepareUrgentFlushObservable,

packages/browser-core/src/transport/flushController.ts

@@ -95,6 +95,9 @@ export function createFlushController({ pageMayExitObservable }: FlushController
     flushObservable,
     prepareUrgentFlushObservable,
     forceFlush: flush,
+    get messagesCount() {
+      return currentMessagesCount
+    },
 
     /**
      * Notifies that a message will be added to a pool of pending messages waiting to be flushed.

packages/browser-core/test/emulate/mockFlushController.ts

@@ -24,6 +24,9 @@ export function createMockFlushController() {
     flushObservable,
     prepareUrgentFlushObservable,
     forceFlush: jasmine.createSpy<FlushController['forceFlush']>(),
+    get messagesCount() {
+      return currentMessagesCount
+    },
   } satisfies FlushController
 
   return {

packages/browser-debugger/src/entries/main.spec.ts

@@ -1,5 +1,5 @@
-import { registerCleanupTask, replaceMockableWithSpy } from '@datadog/browser-core/test'
 import { Observable } from '@datadog/browser-core'
+import { registerCleanupTask, replaceMockableWithSpy } from '@datadog/browser-core/test'
 import { initDebuggerTransport } from '../domain/api'
 import { startDeliveryApiPolling } from '../domain/deliveryApi'
 import { display } from '../domain/display'
@@ -39,6 +39,7 @@ describe('datadogDebugger', () => {
     replaceMockableWithSpy(startDebuggerBatch).and.callFake(() => ({
       flushObservable: new Observable(),
       prepareUrgentFlushObservable: new Observable(),
+      isEmpty: false,
       add: () => undefined,
       flush: () => undefined,
       forceFlush: () => undefined,
@@ -72,6 +73,7 @@ describe('datadogDebugger', () => {
     replaceMockableWithSpy(startDebuggerBatch).and.callFake(() => ({
       flushObservable: new Observable(),
       prepareUrgentFlushObservable: new Observable(),
+      isEmpty: false,
       add: () => undefined,
       flush: () => undefined,
       forceFlush: () => undefined,