[RUM-15238] [FIX] RUM events associated to previous view by marco-saia-datadog · Pull Request #1220 · DataDog/dd-sdk-reactnative

marco-saia-datadog · 2026-03-23T15:10:59Z

What does this PR do?

Introduces a NavigationBuffer that queues RUM events during in-flight navigation and flushes them once the new view is confirmed.

Motivation

RUM events (resources, actions) fired inside a screen's useEffect during a navigation transition were being attributed to the previous view instead of the new one. This happened because the onStateChange callback — which triggers DdRum.startView — fires after the new screen mounts and its effects run, leaving a window where events have no active view to attach to.

How it works

__unsafe_action__ listener (startNavigation) — fires synchronously when any navigation action is dispatched, before the new screen mounts. Starts buffering all incoming RUM events and records navigationStartTime.
prepareEndNavigation — called just before DdRum.startView. Stops accepting new events (so startView itself passes through immediately) but keeps the queue intact.
flush — called after startView resolves. Drains queued events to the now-active view.
endNavigation (stop + drain) — used as a fail-safe on timeout (500 ms), teardown, background state, and any path where startView is skipped.

DdRum.startView is also backdated to navigationStartTime so the view's start timestamp reflects when the user triggered navigation, not when onStateChange fired.

New option: `useNavigationBuffer`

Added to NavigationTrackingOptions (default true). Set to false to bypass the buffer entirely if it causes issues.

DdRumReactNavigationTracking.startTrackingViews(ref, {
    useNavigationBuffer: false
});

Back-to-back navigation race condition (in `5c925f3`)

A second __unsafe_action__ can fire before flush() resolves from the first navigation (e.g. rapid taps). Without a fix, nav-2 events would land in the queue being flushed and be attributed to view 1.

prepareEndNavigation() now snapshots callbackQueue into _pendingFlushQueue and resets the live queue to []. flush() drains only the snapshot, so any events enqueued by a concurrent nav-2 are isolated and will be flushed in their own cycle. endNavigation() and drain() call drainAllQueues() which drains both, so nothing leaks on teardown/timeout

Key files

File	What changed
`core/.../Buffer/NavigationBuffer.ts`	New `DatadogBuffer` decorator implementing the buffer lifecycle
`core/.../Buffer/BufferSingleton.ts`	`onInitialization` now installs `NavigationBuffer` wrapping `PassThroughBuffer` as the active SDK buffer
`react-navigation/.../DdRumReactNavigationTracking.tsx`	Wires `__unsafe_action__` listener; calls `prepareEndNavigation`/`flush` around `startView`; adds `useNavigationBuffer` option
`core/src/index.tsx`	`BufferSingleton` removed from public exports — react-navigation accesses it via `getGlobalInstance` using the shared globalThis key

Additional Notes

NavigationBuffer is accessed from react-navigation via getGlobalInstance('com.datadog.reactnative.buffer_singleton', ...) — no cross-package import. The key is the same one BufferSingleton registers under. A comment in both files marks this coupling.
The 500 ms safety timeout (NAVIGATION_BUFFER_TIMEOUT_MS) guarantees the buffer is always drained even if onStateChange never fires (e.g. navigation cancelled).
All existing tests pass; new tests cover the buffer lifecycle and the __unsafe_action__ wiring.
Debug LOG calls are temporary and marked TODO: remove before shipping - I will remove them after some further testing on my side, and before merging the PR

Review checklist (to be filled by reviewers)

Feature or bugfix MUST have appropriate tests
Make sure you discussed the feature or bugfix with the maintaining team in an Issue
Make sure each commit and the PR mention the Issue number (cf the CONTRIBUTING doc)
If this PR is auto-generated, please make sure also to manually update the code related to the change

Copilot

Pull request overview

Adds a navigation-transition buffering mechanism so RUM events emitted during in-flight navigation are attributed to the new view rather than the previous one.

Changes:

Introduces NavigationBuffer in core and wires it into BufferSingleton after SDK initialization.
Updates React Navigation RUM tracking to start buffering on __unsafe_action__, then prepareEndNavigation() before DdRum.startView and flush() after it settles; adds useNavigationBuffer option.
Adds/updates tests covering buffer lifecycle, teardown, and back-to-back navigation behavior.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 9 comments.

Show a summary per file

File	Description
packages/react-navigation/src/rum/instrumentation/DdRumReactNavigationTracking.tsx	Wires navigation lifecycle to the buffer and backdates `startView` using `navigationStartTime`; adds `useNavigationBuffer`.
packages/react-navigation/src/tests/rum/instrumentation/DdRumReactNavigationTracking.test.tsx	Adds integration tests for the buffer wiring and updates RUM mocks to return promises.
packages/core/src/sdk/DatadogProvider/Buffer/NavigationBuffer.ts	Implements the buffering decorator with `startNavigation` / `prepareEndNavigation` / `flush` / `endNavigation` and a safety timeout.
packages/core/src/sdk/DatadogProvider/Buffer/BufferSingleton.ts	Installs `NavigationBuffer(PassThroughBuffer)` as the active buffer on initialization and exposes `getNavigationBuffer()`.
packages/core/src/sdk/DatadogProvider/Buffer/tests/NavigationBuffer.test.ts	Adds unit tests for buffering, draining, timeouts, and the two-phase flush pattern.
packages/core/src/sdk/DatadogProvider/Buffer/tests/BufferSingleton.test.ts	Verifies `NavigationBuffer` wiring through `BufferSingleton`.

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Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

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sbarrio · 2026-04-27T14:11:06Z

-                    } else {
-                        DdRum.startView(customKey, screenName);
-                    }
+                    const context = params ? { params } : undefined;


Since the default context is always {}, perhaps we could set it as such here and remove the nested ternary below and just pass it forward?

const context = params ? { params } : {}; const startViewPromise = navigationStartTime !== undefined ? DdRum.startView( customKey, screenName, context, navigationStartTime ) : DdRum.startView(customKey, screenName, context);

Not sure if I'm missing an edge case here but it certainly looks easier to read 🤔

sbarrio · 2026-04-27T14:21:39Z

                }
+            } else {
+                // App is in background — no startView, drain buffer immediately
+                this.getNavBuffer()?.endNavigation();


Is this actually reachable in that scenario?, handleAppStateChange does not call handleRouteNavigation when the app is in background (it calls stopView) 🤔

sbarrio

Left some minor nits and questions. Nice job!

cdn34dd

I'm guessing while we're fixing this for react-navigation, the issue will still exist for react-native-navigation correct ?

cdn34dd · 2026-04-27T14:07:19Z

                            activeView: route.name,
                            trackingState: this.trackingState
                        }
                    );


Why does this condition not drain the buffer like the other ones ?

I think we're missing this:

this.getNavBuffer()?.endNavigation();

cdn34dd · 2026-04-27T14:11:54Z

+                    if (event.data?.noop) {
+                        return;
+                    }


When does this happen ? It would be nice to add a comment explaining it.

cdn34dd · 2026-04-27T14:21:25Z

+                    this.getNavBuffer()?.startNavigation();
+                };
+                navigationRef.addListener(
+                    '__unsafe_action__',


This is a private event are we sure this exists/behaves the same in all the versions we support 6/7/8 ? I did a quick search for some documentation on it and there is none, which is probably normal since it's a private field, but still, we should ensure it exists and behaves the same in all the versions.

RUM-15238: fix RUM events associated to prior view

37adee8

marco-saia-datadog force-pushed the marcosaia/RUM-15238/fix-events-mis-association branch from e08ad8f to 37adee8 Compare March 23, 2026 15:34

marco-saia-datadog added 2 commits March 23, 2026 16:56

chore: removed NavigationBuffer internal logs

3f0b664

RUM-15238: handle back-to-back navigation

5c925f3

marco-saia-datadog marked this pull request as ready for review March 23, 2026 17:09

marco-saia-datadog requested a review from a team as a code owner March 23, 2026 17:09

Copilot AI review requested due to automatic review settings March 23, 2026 17:09

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pr: addressed copilot comments

eb49967

Copilot AI review requested due to automatic review settings March 31, 2026 14:52

marco-saia-datadog force-pushed the marcosaia/RUM-15238/fix-events-mis-association branch from 2552a9b to eb49967 Compare March 31, 2026 14:52

Copilot started reviewing on behalf of marco-saia-datadog March 31, 2026 14:53 View session

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Comment thread ...ges/react-navigation/src/__tests__/rum/instrumentation/DdRumReactNavigationTracking.test.tsx

pr: add test for useNavigationBuffer=false

e705d50

sbarrio reviewed Apr 27, 2026

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sbarrio approved these changes Apr 27, 2026

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cdn34dd reviewed Apr 27, 2026

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marco-saia-datadog commented Mar 23, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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What does this PR do?

Motivation

How it works

New option: useNavigationBuffer

Back-to-back navigation race condition (in 5c925f3)

Key files

Additional Notes

Review checklist (to be filled by reviewers)

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marco-saia-datadog commented Mar 23, 2026 •

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New option: `useNavigationBuffer`

Back-to-back navigation race condition (in `5c925f3`)