feat(extend-app-start): [2/4] Extract AppStartExtension component by buenaflor · Pull Request #5606 · getsentry/sentry-java

buenaflor · 2026-06-23T11:17:18Z

PR Stack (Extend App Start)

📜 Description

Pulls the Android extender out of the already-large AppStartMetrics into a focused, testable AppStartExtension component.

Class	Change
`AppStartExtension` (new)	`implements IAppStartExtender`. Owns the lock-guarded extend lifecycle and holds the eager App Start `ITransaction` + its child `ISpan`.
`AppStartMetrics`	No longer implements `IAppStartExtender` — just holds the component and exposes the extend gate `isAppStartWindowOpen()`.
`AndroidOptionsInitializer`	Registers the component as the options' app start extender.

Notes

AppStartExtension has no scopes, so it can't create the transaction/span itself — the integration builds them and returns an ExtendedAppStart from the listener.
getExtendedEndTime() is deadline-aware: null on DEADLINE_EXCEEDED, so the vital is suppressed rather than inflated.
isAppStartWindowOpen() gate = measurements not sent + no activity + first frame not drawn. The foreground check is ignored so headless starts can extend as well.
Inert on its own: no listener is registered until [3/4], so extendAppStart() is a no-op and getExtendedAppStartSpan() returns NoOpSpan.

💡 Motivation and Context

Part of the app start extension API stack (#5553). A dedicated component keeps the new concern out of AppStartMetrics and is easy to isolate and test.

💚 How did you test it?

Unit tests in AppStartExtensionTest, AppStartMetricsTest, and AndroidOptionsInitializerTest cover the extend gate, listener firing, inert behavior, idempotent finish, deadline suppression, and wiring. apiCheck, spotless, and the :sentry-android-core unit suite pass.

📝 Checklist

I added GH Issue ID & Linear ID
I added tests to verify the changes.
No new PII added or SDK only sends newly added PII if sendDefaultPII is enabled.
I updated the docs if needed.
I updated the wizard if needed.
Review from the native team if needed.
No breaking change or entry added to the changelog.
No breaking change for hybrid SDKs or communicated to hybrid SDKs.

🔮 Next steps

[3/4] registers the listener, eagerly creates the App Start transaction + child, and extends/suppresses the app start vital in PerformanceAndroidEventProcessor.

⚠️ Merge this PR using a merge commit (not squash). Only the collection branch is squash-merged into main.

#skip-changelog

github-actions · 2026-06-23T11:17:50Z

	Messages
📖	Do not forget to update Sentry-docs with your feature once the pull request gets approved.

Generated by 🚫 dangerJS against e26ee97

sentry · 2026-06-23T11:20:46Z

📲 Install Builds

Android

🔗 App Name	App ID	Version	Configuration
SDK Size	io.sentry.tests.size	8.44.1 (1)	release

⚙️ sentry-android Build Distribution Settings

github-actions · 2026-06-23T12:34:57Z

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	347.33 ms	427.28 ms	79.95 ms
Size	0 B	0 B	0 B

Baseline results on branch: feat/app-start-extension-core

Startup times

Revision	Plain	With Sentry	Diff
`3d04aae`	324.42 ms	359.30 ms	34.88 ms
`69d43cc`	380.70 ms	424.90 ms	44.20 ms
`2821a4d`	315.46 ms	366.56 ms	51.10 ms

App size

Revision	Plain	With Sentry	Diff
`3d04aae`	0 B	0 B	0 B
`69d43cc`	0 B	0 B	0 B
`2821a4d`	0 B	0 B	0 B

Previous results on branch: feat/app-start-extension-android

Startup times

Revision	Plain	With Sentry	Diff
`388ffc5`	315.18 ms	362.43 ms	47.25 ms
`b76203f`	336.02 ms	403.42 ms	67.40 ms
`db5be2f`	311.84 ms	365.94 ms	54.10 ms
`ca0c0cf`	318.45 ms	370.06 ms	51.61 ms
`201a6fd`	326.00 ms	371.92 ms	45.92 ms

App size

Revision	Plain	With Sentry	Diff
`388ffc5`	0 B	0 B	0 B
`b76203f`	0 B	0 B	0 B
`db5be2f`	0 B	0 B	0 B
`ca0c0cf`	0 B	0 B	0 B
`201a6fd`	0 B	0 B	0 B

…ndroid extender Replaces the AppStartMetrics IAppStartExtender implementation and the deferred ExtendedAppStartSpan with a focused, lock-guarded AppStartExtension that owns the eager App Start transaction and extended span. AppStartMetrics now only holds the component and exposes isAppStartWindowOpen(). Inert until 3/4 registers the listener. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

…ead of static scope lookup Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

… instead of a callback The listener now returns the created transaction+span (or null to decline) rather than calling back into onExtended() while extendAppStart() holds the lock. This removes the re-entrant lock acquisition and the A->B->A round trip, collapsing two public methods into one linear flow. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

…o clear Drop comments that restate code or annotate omissions (region markers, getter javadoc, the reset call-site comment, the ExtendedAppStart/isActive docs). Rename AppStartExtension.reset() to clear() to match its owner AppStartMetrics.clear(). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

…ting it The extension logs only two warnings, both on rare guard paths in extendAppStart(). Inline Sentry.getCurrentScopes().getOptions().getLogger() at those sites instead of holding a logger field set at init, dropping the field, setLogger(), and the AndroidOptionsInitializer wiring. extendAppStart() runs post-init, so the lookup always yields the configured logger. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

…tartExtension Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

…mments Drop finishTransaction's javadoc (trivial body; it described caller context and waitForChildren behavior configured elsewhere) and reduce getExtendedEndTime's javadoc to a single inline note on the only non-obvious branch (deadline suppression). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

…o finishExtendedAppStart Implements the renamed IAppStartExtender.finishExtendedAppStart(). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

…on extendAppStart Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

…nd trim comments Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

buenaflor · 2026-06-25T13:13:10Z

+    }
+  }
+
+  public void finishTransaction(final @NotNull SentryDate endTimestamp) {


this will be used in the next PR 3/4

Copilot

Pull request overview

This PR continues the “Extend App Start” stack by extracting the Android app-start extension behavior out of AppStartMetrics into a dedicated, testable AppStartExtension component, and wiring it into Android options so the core IAppStartExtender bridge can route to Android.

Changes:

Introduces AppStartExtension (@ApiStatus.Internal) implementing IAppStartExtender, encapsulating the extension lifecycle and extended txn/span references.
Updates AppStartMetrics to own the component, expose an isAppStartWindowOpen() gate, and clear the extension state when spans are sent / metrics reset.
Registers the extender in AndroidOptionsInitializer and adds/extends unit coverage for the new behavior and gates.

Reviewed changes

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

Show a summary per file

File	Description
sentry-android-core/src/main/java/io/sentry/android/core/AppStartExtension.java	New internal extender component with lock-guarded lifecycle and span/txn accessors.
sentry-android-core/src/main/java/io/sentry/android/core/performance/AppStartMetrics.java	Holds the extension component, adds `isAppStartWindowOpen()`, clears extension state on reset/send.
sentry-android-core/src/main/java/io/sentry/android/core/AndroidOptionsInitializer.java	Wires the Android extender implementation into `SentryAndroidOptions`.
sentry-android-core/src/test/java/io/sentry/android/core/AppStartExtensionTest.kt	New unit tests for extension activation/inert behavior, finish semantics, and end-time suppression.
sentry-android-core/src/test/java/io/sentry/android/core/performance/AppStartMetricsTest.kt	Adds coverage for the new “window open” gate and extension state reset paths.
sentry-android-core/api/sentry-android-core.api	API dump updates for newly added internal class and new `AppStartMetrics` methods.

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…nished flag getExtendedEndTime() gated on span.isFinished(), but finishing the extended span completes the waitForChildren transaction and runs the event processor re-entrantly within finishExtendedAppStart(), before the span's finished flag is set. The processor then saw an unfinished span and dropped the app start measurement whenever the extension finished after the first frame. Read getFinishDate() (set before the finish callback) instead, which also keeps the extended end controllable in tests. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

…pan end When the extended span finished after the timestamp passed to finishTransaction() but before that call ran (e.g. a synchronous extension in a headless start, where finishTransaction runs later at main-thread idle), waitForChildren had nothing left to wait for and the transaction kept the earlier passed timestamp. The extended span then ended after the transaction, and the app start vital exceeded the transaction duration. Finish at max(endTimestamp, extended span finish date) so the span is contained and the duration matches the vital. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

The setter wrote the field without synchronization while extendAppStart() reads it under the lock, leaving no happens-before edge. Acquire the same lock in the setter, consistent with the rest of the class's mutable state. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

cursor

Cursor Bugbot has reviewed your changes and found 1 potential issue.

^{❌ Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, enable autofix in the Cursor dashboard.}

^{Reviewed by Cursor Bugbot for commit e26ee97. Configure here.}

cursor · 2026-06-26T12:20:59Z

+    return shouldSendStartMeasurements(true)
+        && activeActivitiesCounter.get() == 0
+        && !firstDrawDone.get();
+  }


Extend window reopens after destroy

Medium Severity

isAppStartWindowOpen() treats shouldSendStartMeasurements and firstDrawDone as “extension still allowed,” but onActivityDestroyed resets both when the last activity is destroyed to prepare warm-start measurements. After a cold start has already sent vitals or drawn its first frame, the gate can read open again and let extendAppStart() run outside the real startup window.

^{Reviewed by Cursor Bugbot for commit e26ee97. Configure here.}

sentry · 2026-06-26T12:22:14Z

+  public @NotNull ISpan getExtendedAppStartSpan() {
+    try (final @NotNull ISentryLifecycleToken ignored = lock.acquire()) {
+      final @Nullable ISpan span = extendedSpan;
+      if (span != null && !span.isFinished()) {


Bug: The getExtendedAppStartSpan() method uses span.isFinished() which is vulnerable to a reentrancy issue, potentially returning a live span that is already in the process of finishing.
_{Severity: MEDIUM}

Suggested Fix

To fix the reentrancy vulnerability, change the condition at line 97 from if (span != null && !span.isFinished()) to check span.getFinishDate() == null instead. This aligns the logic with the fix already implemented in getExtendedEndTime() for the same issue.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI agent. Verify if this is a real issue. If it is, propose a fix; if not, explain why it's not valid. Location: sentry-android-core/src/main/java/io/sentry/android/core/AppStartExtension.java#L97 Potential issue: The method `getExtendedAppStartSpan()` uses `span.isFinished()` to determine if the app start span is still active. However, a reentrancy issue can occur when the span is being finished. During this window, `isFinished()` may return `false` even though the span's `finishDate` has been set. This could cause the method to return a live span that is in the process of being finalized, potentially allowing callers to add new child spans to a finished span. A similar method, `getExtendedEndTime()`, was already fixed to handle this exact reentrancy scenario by checking `span.getFinishDate()` instead.

This was referenced Jun 23, 2026

feat(extend-app-start): App start extension API #5604

Draft

feat(extend-app-start): [1/4] Add IAppStartExtender bridge #5605

Open

buenaflor force-pushed the feat/app-start-extension-core branch from 064d3f1 to 7a7d63f Compare June 23, 2026 12:13

buenaflor force-pushed the feat/app-start-extension-android branch from fd450bb to 54be119 Compare June 23, 2026 12:13

buenaflor mentioned this pull request Jun 23, 2026

feat(extend-app-start): [3/4] Eagerly create the extended app start transaction #5608

Open

8 tasks

buenaflor force-pushed the feat/app-start-extension-android branch from 54be119 to d2b96ad Compare June 24, 2026 10:47

buenaflor mentioned this pull request Jun 25, 2026

feat(extend-app-start): [4/4] Add public Sentry app start extension API #5628

Open

8 tasks

buenaflor changed the title ~~feat(extend-app-start): [2/4] Add deferred extended span and extension state~~ feat(extend-app-start): [2/4] Extract AppStartExtension component Jun 25, 2026

buenaflor force-pushed the feat/app-start-extension-android branch 2 times, most recently from 3bc1643 to 45f6c0b Compare June 25, 2026 11:37

buenaflor and others added 8 commits June 25, 2026 14:27

refactor(extend-app-start): Inject logger into AppStartExtension inst…

4d0c97d

…ead of static scope lookup Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

chore(extend-app-start): Drop the class and listener javadocs on AppS…

1dafb9b

…tartExtension Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

refactor(extend-app-start): Rename AppStartExtension.finishAppStart t…

01b1dc4

…o finishExtendedAppStart Implements the renamed IAppStartExtender.finishExtendedAppStart(). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

buenaflor force-pushed the feat/app-start-extension-android branch from 2d5188e to 01b1dc4 Compare June 25, 2026 12:32

buenaflor and others added 3 commits June 25, 2026 15:10

chore(extend-app-start): Drop the redundant foreground-check comment …

05a9df2

…on extendAppStart Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

test(extend-app-start): Drop the no-value getAppStartExtension test a…

5830303

…nd trim comments Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

test(extend-app-start): Drop the no-op finishExtendedAppStart test

ec4da6c

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

buenaflor commented Jun 25, 2026

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buenaflor marked this pull request as ready for review June 25, 2026 13:16

Copilot AI review requested due to automatic review settings June 25, 2026 13:16

buenaflor requested review from adinauer and romtsn as code owners June 25, 2026 13:16

buenaflor requested review from 0xadam-brown, markushi and runningcode as code owners June 25, 2026 13:16

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Comment thread sentry-android-core/src/main/java/io/sentry/android/core/AppStartExtension.java

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Comment thread sentry-android-core/src/main/java/io/sentry/android/core/AppStartExtension.java

buenaflor force-pushed the feat/app-start-extension-android branch from a622ea2 to d2c16a2 Compare June 25, 2026 14:51

buenaflor and others added 3 commits June 25, 2026 17:22

style(extend-app-start): Trim verbose finishTransaction comment

e26ee97

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

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PR Stack (Extend App Start)

📜 Description

💡 Motivation and Context

💚 How did you test it?

📝 Checklist

🔮 Next steps

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📲 Install Builds

Android

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Performance metrics 🚀

Baseline results on branch: feat/app-start-extension-core

Startup times

App size

Previous results on branch: feat/app-start-extension-android

Startup times

App size

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buenaflor Jun 25, 2026

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Pull request overview

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Extend window reopens after destroy

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buenaflor commented Jun 23, 2026 •

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