fix(sample): Drop Nav3 Activity ui.load transactions when the toggle is off (#6401)

The sample cancelled the Activity's ui.load transaction through the scope. When another
transaction was already bound, such as the previous Activity's nav transaction, the SDK didn't
bind ui.load, so the cancel missed and the transaction was still sent, often waiting the full
deadline with the Activity's spans.

Keep cancelling a bound ui.load transaction so it doesn't block the first nav transaction, and
also drop Nav3 sample Activities' ui.load transactions in an event processor when the Activity
was created with the toggle off.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: 0xadam-brown

sentry-samples/sentry-samples-android/src/main/java/io/sentry/samples/android/navigation/nav3/Nav3Activity.kt

@@ -92,11 +92,10 @@ class Nav3Activity : ComponentActivity() {
     configuration.applyToCurrentOptions()
     showActivityUiLoadTransactionDelayMessage = configuration.hasOnlyActivityUiLoadTransactions
 
-    if (!configuration.enableActivityUiLoadTransaction) {
-      // Cancel the already-started Activity transaction before Compose installs SentryNavEffect,
-      // otherwise the initial /Landing route transaction gets preempted by the lingering ui.load.
-      cancelCurrentActivityUiLoadTransaction()
-    }
+    // When the toggle is off, cancel the already-started Activity transaction before Compose
+    // installs SentryNavEffect, otherwise the lingering ui.load preempts the initial /Landing route
+    // transaction.
+    applyActivityUiLoadTransactionSetting(this, configuration.enableActivityUiLoadTransaction)
 
     NavigationTransactionHistory.install()
 

sentry-samples/sentry-samples-android/src/main/java/io/sentry/samples/android/navigation/nav3/Nav3MultiActivity.kt

@@ -89,9 +89,7 @@ class Nav3ProductsActivity : ComponentActivity() {
     super.onCreate(savedInstanceState)
     val configuration = (intent.extras ?: Bundle()).nav3SampleConfiguration()
     NavigationTransactionHistory.install()
-    if (!configuration.enableActivityUiLoadTransaction) {
-      cancelCurrentActivityUiLoadTransaction()
-    }
+    applyActivityUiLoadTransactionSetting(this, configuration.enableActivityUiLoadTransaction)
     setContent {
       val stack = rememberSaveableNav3BackStack(Nav3Route.ProductList)
       SideEffect {
@@ -174,9 +172,7 @@ open class Nav3CheckoutActivity : ComponentActivity() {
     val crashOnFirstComposition =
       savedInstanceState == null && intent.getBooleanExtra(EXTRA_CRASH_ON_FIRST_COMPOSITION, false)
     NavigationTransactionHistory.install()
-    if (!configuration.enableActivityUiLoadTransaction) {
-      cancelCurrentActivityUiLoadTransaction()
-    }
+    applyActivityUiLoadTransactionSetting(this, configuration.enableActivityUiLoadTransaction)
     setContent {
       Nav3SampleTheme {
         if (showAsSheet) {

sentry-samples/sentry-samples-android/src/main/java/io/sentry/samples/android/navigation/nav3/Nav3MultiFragment.kt

@@ -76,9 +76,7 @@ class Nav3FragmentsActivity : FragmentActivity() {
   override fun onCreate(savedInstanceState: Bundle?) {
     super.onCreate(savedInstanceState)
     NavigationTransactionHistory.install()
-    if (!configuration.enableActivityUiLoadTransaction) {
-      cancelCurrentActivityUiLoadTransaction()
-    }
+    applyActivityUiLoadTransactionSetting(this, configuration.enableActivityUiLoadTransaction)
 
     val controls =
       ComposeView(this).apply {

sentry-samples/sentry-samples-android/src/main/java/io/sentry/samples/android/navigation/nav3/Nav3SampleTracing.kt

@@ -1,8 +1,13 @@
 package io.sentry.samples.android.navigation.nav3
 
+import android.app.Activity
+import io.sentry.EventProcessor
+import io.sentry.Hint
 import io.sentry.Sentry
 import io.sentry.SpanStatus
 import io.sentry.protocol.SentryTransaction
+import java.util.Collections
+import java.util.concurrent.ConcurrentHashMap
 import kotlin.coroutines.resume
 import kotlinx.coroutines.suspendCancellableCoroutine
 
@@ -21,6 +26,51 @@ internal fun SentryTransaction.navigationSampleScenarioLabel(): String =
     ?: getTag(NAV3_SCENARIO_TAG)
     ?: UNKNOWN_NAVIGATION_SCENARIO_LABEL
 
+/**
+ * Applies the sample's "Activity ui.load transaction" toggle to [activity].
+ *
+ * Call from `onCreate` after `super.onCreate`, once the SDK has started the Activity's ui.load
+ * transaction. When [enabled] is false, the transaction is cancelled if it's bound to the scope.
+ * It's also dropped before sending, because the SDK doesn't bind it when another transaction (such
+ * as the previous Activity's nav transaction) is already bound, and the sample can't reach an
+ * unbound ui.load transaction to cancel it.
+ */
+internal fun applyActivityUiLoadTransactionSetting(activity: Activity, enabled: Boolean) {
+  // Matches the transaction name ActivityLifecycleIntegration uses.
+  val activityName = activity.javaClass.simpleName
+  if (enabled) {
+    SuppressedActivityUiLoadTransactions.activityNames.remove(activityName)
+    return
+  }
+  SuppressedActivityUiLoadTransactions.install()
+  SuppressedActivityUiLoadTransactions.activityNames.add(activityName)
+  cancelCurrentActivityUiLoadTransaction()
+}
+
+/** Drops ui.load transactions for sample Activities created with the ui.load toggle off. */
+private object SuppressedActivityUiLoadTransactions : EventProcessor {
+  val activityNames: MutableSet<String> =
+    Collections.newSetFromMap(ConcurrentHashMap<String, Boolean>())
+
+  @Volatile private var installed = false
+
+  fun install() {
+    if (installed) return
+    synchronized(this) {
+      if (installed) return
+      Sentry.getCurrentScopes().options.addEventProcessor(this)
+      installed = true
+    }
+  }
+
+  override fun process(transaction: SentryTransaction, hint: Hint): SentryTransaction? {
+    val isSuppressed =
+      transaction.contexts.trace?.operation == ACTIVITY_UI_LOAD_OP &&
+        transaction.transaction in activityNames
+    return if (isSuppressed) null else transaction
+  }
+}
+
 internal fun cancelCurrentActivityUiLoadTransaction() {
   Sentry.configureScope { scope ->
     scope.withTransaction { transaction ->