From 68e774bb2c1aa630144dac0177771e968a542e6e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rub=C3=A9n=20Norte?= <rubennorte@meta.com>
Date: Mon, 1 Sep 2025 09:18:19 -0700
Subject: [PATCH] Implement PerformanceObserver.takeRecords() (#53428)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/53428

Changelog: [internal]

This is the last method in `PerformanceObserver` to implement. For some reason we never added it, even though it was trivial.

Reviewed By: rshest

Differential Revision: D80717237

fbshipit-source-id: ae3bd243d0f3f0fe4f0705437d78d14c532515f7
---
 .../performance/PerformanceObserver.js        | 18 ++++++++++++++++-
 .../__tests__/PerformanceObserver-itest.js    | 20 +++++++++++++++++++
 2 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/packages/react-native/src/private/webapis/performance/PerformanceObserver.js b/packages/react-native/src/private/webapis/performance/PerformanceObserver.js
index c576a4451f6..e2efde682ea 100644
--- a/packages/react-native/src/private/webapis/performance/PerformanceObserver.js
+++ b/packages/react-native/src/private/webapis/performance/PerformanceObserver.js
@@ -145,6 +145,22 @@ export class PerformanceObserver {
     NativePerformance.disconnect(this.#nativeObserverHandle);
   }
 
+  takeRecords(): PerformanceEntryList {
+    let entries: PerformanceEntryList = [];
+
+    if (this.#nativeObserverHandle != null) {
+      const rawEntries = NativePerformance.takeRecords(
+        this.#nativeObserverHandle,
+        true,
+      );
+      if (rawEntries && rawEntries.length > 0) {
+        entries = rawEntries.map(rawToPerformanceEntry);
+      }
+    }
+
+    return entries;
+  }
+
   #createNativeObserver(): OpaqueNativeObserverHandle | null {
     this.#calledAtLeastOnce = false;
 
@@ -154,7 +170,7 @@ export class PerformanceObserver {
           observerHandle,
           true, // sort records
         );
-        if (!rawEntries) {
+        if (!rawEntries || rawEntries.length === 0) {
           return;
         }
 
diff --git a/packages/react-native/src/private/webapis/performance/__tests__/PerformanceObserver-itest.js b/packages/react-native/src/private/webapis/performance/__tests__/PerformanceObserver-itest.js
index 77af8cb8c83..70e91786f95 100644
--- a/packages/react-native/src/private/webapis/performance/__tests__/PerformanceObserver-itest.js
+++ b/packages/react-native/src/private/webapis/performance/__tests__/PerformanceObserver-itest.js
@@ -97,4 +97,24 @@ describe('PerformanceObserver', () => {
     expect(entries1.getEntries()[1]).toBe(measure);
     expect(entries2.getEntries()[1]).toBe(measure);
   });
+
+  describe('takeRecords()', () => {
+    it('provides all buffered events and clears the buffer', () => {
+      const callback = jest.fn();
+      const observer = new PerformanceObserver(callback);
+      observer.observe({entryTypes: ['mark']});
+
+      Fantom.runTask(() => {
+        const entry = performance.mark('mark1');
+
+        const entries = observer.takeRecords();
+        expect(entries.length).toBe(1);
+        // This is not supported yet
+        // expect(entries[0]).toBe(entry);
+        expect(entries[0]).toEqual(entry);
+      });
+
+      expect(callback).not.toHaveBeenCalled();
+    });
+  });
 });