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feat(extend-app-start): [2/4] Extract AppStartExtension component #5606

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7dfe617
feat(extend-app-start): Extract AppStartExtension component for the A…
buenaflor Jun 23, 2026
4d0c97d
refactor(extend-app-start): Inject logger into AppStartExtension inst…
buenaflor Jun 25, 2026
b5ac7f5
refactor(extend-app-start): Return ExtendedAppStart from the listener…
buenaflor Jun 25, 2026
81efded
chore(extend-app-start): Remove redundant comments and rename reset t…
buenaflor Jun 25, 2026
3cc743e
refactor(extend-app-start): Inline the logger lookup instead of injec…
buenaflor Jun 25, 2026
1dafb9b
chore(extend-app-start): Drop the class and listener javadocs on AppS…
buenaflor Jun 25, 2026
8548b4d
chore(extend-app-start): Trim finishTransaction/getExtendedEndTime co…
buenaflor Jun 25, 2026
01b1dc4
refactor(extend-app-start): Rename AppStartExtension.finishAppStart t…
buenaflor Jun 25, 2026
05a9df2
chore(extend-app-start): Drop the redundant foreground-check comment …
buenaflor Jun 25, 2026
5830303
test(extend-app-start): Drop the no-value getAppStartExtension test a…
buenaflor Jun 25, 2026
ec4da6c
test(extend-app-start): Drop the no-op finishExtendedAppStart test
buenaflor Jun 25, 2026
d2c16a2
fix(extend-app-start): Read the extended span finish date, not its fi…
buenaflor Jun 25, 2026
b6dd76e
fix(extend-app-start): End the extended transaction at the extended s…
buenaflor Jun 25, 2026
ff8c056
fix(extend-app-start): Guard extendAppStartListener with the lock
buenaflor Jun 26, 2026
e26ee97
style(extend-app-start): Trim verbose finishTransaction comment
buenaflor Jun 26, 2026
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24 changes: 24 additions & 0 deletions sentry-android-core/api/sentry-android-core.api
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Original file line number Diff line number Diff line change
Expand Up @@ -184,6 +184,28 @@ public final class io/sentry/android/core/AppLifecycleIntegration : io/sentry/In
public fun register (Lio/sentry/IScopes;Lio/sentry/SentryOptions;)V
}

public final class io/sentry/android/core/AppStartExtension : io/sentry/IAppStartExtender {
public fun <init> (Lio/sentry/android/core/performance/AppStartMetrics;)V
public fun clear ()V
public fun extendAppStart ()V
public fun finishExtendedAppStart ()V
public fun finishTransaction (Lio/sentry/SentryDate;)V
public fun getExtendedAppStartSpan ()Lio/sentry/ISpan;
public fun getExtendedEndTime ()Lio/sentry/SentryDate;
public fun isActive ()Z
public fun setExtendAppStartListener (Lio/sentry/android/core/AppStartExtension$ExtendAppStartListener;)V
}

public abstract interface class io/sentry/android/core/AppStartExtension$ExtendAppStartListener {
public abstract fun onExtendAppStartRequested ()Lio/sentry/android/core/AppStartExtension$ExtendedAppStart;
}

public final class io/sentry/android/core/AppStartExtension$ExtendedAppStart {
public final field span Lio/sentry/ISpan;
public final field transaction Lio/sentry/ITransaction;
public fun <init> (Lio/sentry/ITransaction;Lio/sentry/ISpan;)V
}

public final class io/sentry/android/core/AppState : java/io/Closeable {
public fun addAppStateListener (Lio/sentry/android/core/AppState$AppStateListener;)V
public fun close ()V
Expand Down Expand Up @@ -745,6 +767,7 @@ public class io/sentry/android/core/performance/AppStartMetrics : io/sentry/andr
public fun getAppStartBaggageHeader ()Ljava/lang/String;
public fun getAppStartContinuousProfiler ()Lio/sentry/IContinuousProfiler;
public fun getAppStartEndTime ()Lio/sentry/SentryDate;
public fun getAppStartExtension ()Lio/sentry/android/core/AppStartExtension;
public fun getAppStartProfiler ()Lio/sentry/ITransactionProfiler;
public fun getAppStartReason ()Ljava/lang/String;
public fun getAppStartSamplingDecision ()Lio/sentry/TracesSamplingDecision;
Expand All @@ -760,6 +783,7 @@ public class io/sentry/android/core/performance/AppStartMetrics : io/sentry/andr
public static fun getInstance ()Lio/sentry/android/core/performance/AppStartMetrics;
public fun getSdkInitTimeSpan ()Lio/sentry/android/core/performance/TimeSpan;
public fun isAppLaunchedInForeground ()Z
public fun isAppStartWindowOpen ()Z
public fun onActivityCreated (Landroid/app/Activity;Landroid/os/Bundle;)V
public fun onActivityDestroyed (Landroid/app/Activity;)V
public fun onActivityPaused (Landroid/app/Activity;)V
Expand Down
1 change: 1 addition & 0 deletions sentry-android-core/src/main/java/io/sentry/android/core/AndroidOptionsInitializer.java
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Original file line number Diff line number Diff line change
Expand Up @@ -198,6 +198,7 @@ static void initializeIntegrationsAndProcessors(
}

final @NotNull AppStartMetrics appStartMetrics = AppStartMetrics.getInstance();
options.setAppStartExtender(appStartMetrics.getAppStartExtension());

if (options.getModulesLoader() instanceof NoOpModulesLoader) {
options.setModulesLoader(new AssetsModulesLoader(context, options));
Expand Down
148 changes: 148 additions & 0 deletions sentry-android-core/src/main/java/io/sentry/android/core/AppStartExtension.java
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Original file line number Diff line number Diff line change
@@ -0,0 +1,148 @@
package io.sentry.android.core;

import io.sentry.IAppStartExtender;
import io.sentry.ISentryLifecycleToken;
import io.sentry.ISpan;
import io.sentry.ITransaction;
import io.sentry.NoOpSpan;
import io.sentry.Sentry;
import io.sentry.SentryDate;
import io.sentry.SentryLevel;
import io.sentry.SpanStatus;
import io.sentry.android.core.performance.AppStartMetrics;
import io.sentry.util.AutoClosableReentrantLock;
import org.jetbrains.annotations.ApiStatus;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

@ApiStatus.Internal
public final class AppStartExtension implements IAppStartExtender {

public static final class ExtendedAppStart {
public final @NotNull ITransaction transaction;
public final @NotNull ISpan span;

public ExtendedAppStart(final @NotNull ITransaction transaction, final @NotNull ISpan span) {
this.transaction = transaction;
this.span = span;
}
}

public interface ExtendAppStartListener {
@Nullable
ExtendedAppStart onExtendAppStartRequested();
}

private final @NotNull AppStartMetrics metrics;
private final @NotNull AutoClosableReentrantLock lock = new AutoClosableReentrantLock();

private @Nullable ExtendAppStartListener extendAppStartListener;
private @Nullable ISpan extendedSpan;
private @Nullable ITransaction extendedTransaction;

public AppStartExtension(final @NotNull AppStartMetrics metrics) {
this.metrics = metrics;
}

public void setExtendAppStartListener(final @Nullable ExtendAppStartListener listener) {
try (final @NotNull ISentryLifecycleToken ignored = lock.acquire()) {
this.extendAppStartListener = listener;
}
}
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@Override
public void extendAppStart() {
try (final @NotNull ISentryLifecycleToken ignored = lock.acquire()) {
if (extendedSpan != null) {
Sentry.getCurrentScopes()
.getOptions()
.getLogger()
.log(SentryLevel.WARNING, "App start is already being extended.");
return;
}
if (!metrics.isAppStartWindowOpen()) {
Sentry.getCurrentScopes()
.getOptions()
.getLogger()
.log(
SentryLevel.WARNING,
"Cannot extend app start: the app start window has already passed.");
return;
}
final @Nullable ExtendAppStartListener listener = extendAppStartListener;
if (listener != null) {
final @Nullable ExtendedAppStart extended = listener.onExtendAppStartRequested();
if (extended != null) {
this.extendedTransaction = extended.transaction;
this.extendedSpan = extended.span;
}
}
}
}

@Override
public void finishExtendedAppStart() {
try (final @NotNull ISentryLifecycleToken ignored = lock.acquire()) {
final @Nullable ISpan span = extendedSpan;
if (span != null && !span.isFinished()) {
span.finish(SpanStatus.OK);
}
}
}

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

@sentry sentry Bot Jun 26, 2026

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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.

return span;
}
return NoOpSpan.getInstance();
}
}

public boolean isActive() {
try (final @NotNull ISentryLifecycleToken ignored = lock.acquire()) {
return extendedTransaction != null && !extendedTransaction.isFinished();
}
}

public void finishTransaction(final @NotNull SentryDate endTimestamp) {

@buenaflor buenaflor Jun 25, 2026

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this will be used in the next PR 3/4

try (final @NotNull ISentryLifecycleToken ignored = lock.acquire()) {
final @Nullable ITransaction transaction = extendedTransaction;
if (transaction != null && !transaction.isFinished()) {
// End at the extended span's finish if it ran past endTimestamp, so the txn covers it.
final @Nullable ISpan span = extendedSpan;
final @Nullable SentryDate spanEnd = span == null ? null : span.getFinishDate();
final @NotNull SentryDate end =
spanEnd != null && spanEnd.isAfter(endTimestamp) ? spanEnd : endTimestamp;
transaction.finish(SpanStatus.OK, end);
}
}
}

public @Nullable SentryDate getExtendedEndTime() {
try (final @NotNull ISentryLifecycleToken ignored = lock.acquire()) {
final @Nullable ISpan span = extendedSpan;
if (span == null) {
return null;
}
// A deadline timeout would report an artificially inflated duration; suppress the vital
// instead.
if (span.getStatus() == SpanStatus.DEADLINE_EXCEEDED) {
return null;
}
// Read the finish date, not isFinished(): finishing the extended span completes the
// waitForChildren transaction and runs the event processor re-entrantly before the span's
// finished flag is set, but the finish timestamp is already in place. Null until finished.
return span.getFinishDate();
}
}

public void clear() {
try (final @NotNull ISentryLifecycleToken ignored = lock.acquire()) {
extendedSpan = null;
extendedTransaction = null;
}
}
}
19 changes: 19 additions & 0 deletions sentry-android-core/src/main/java/io/sentry/android/core/performance/AppStartMetrics.java
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,7 @@
import io.sentry.NoOpLogger;
import io.sentry.SentryDate;
import io.sentry.TracesSamplingDecision;
import io.sentry.android.core.AppStartExtension;
import io.sentry.android.core.BuildInfoProvider;
import io.sentry.android.core.ContextUtils;
import io.sentry.android.core.CurrentActivityHolder;
Expand Down Expand Up @@ -98,6 +99,7 @@ public enum AppStartType {
private @Nullable String appStartBaggageHeader;
private @Nullable SentryDate appStartEndTime;
private @Nullable ApplicationStartInfo cachedStartInfo;
private final @NotNull AppStartExtension appStartExtension = new AppStartExtension(this);

public static @NotNull AppStartMetrics getInstance() {
if (instance == null) {
Expand Down Expand Up @@ -281,6 +283,7 @@ public void onAppStartSpansSent() {
shouldSendStartMeasurements = false;
contentProviderOnCreates.clear();
activityLifecycles.clear();
appStartExtension.clear();
}

public boolean shouldSendStartMeasurements(final boolean ignoreForegroundCheck) {
Expand Down Expand Up @@ -336,6 +339,21 @@ public long getClassLoadedUptimeMs() {
return new TimeSpan();
}

public @NotNull AppStartExtension getAppStartExtension() {
return appStartExtension;
}

/**
* Whether the app start window is still open, i.e. an app start can be extended: measurements
* haven't been sent yet, no activity has been created, and the first frame hasn't been drawn. The
* foreground check is ignored so headless app starts (broadcast/service) can also be extended.
*/
public boolean isAppStartWindowOpen() {
return shouldSendStartMeasurements(true)
&& activeActivitiesCounter.get() == 0
&& !firstDrawDone.get();
}

@cursor cursor Bot Jun 26, 2026

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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.

Fix in Cursor Fix in Web

Reviewed by Cursor Bugbot for commit e26ee97. Configure here.


@TestOnly
void setFirstIdle(final long firstIdle) {
this.firstIdle = firstIdle;
Expand Down Expand Up @@ -377,6 +395,7 @@ public void clear() {
appStartBaggageHeader = null;
appStartEndTime = null;
cachedStartInfo = null;
appStartExtension.clear();
}

public @Nullable ITransactionProfiler getAppStartProfiler() {
Expand Down
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