update poc

flutter/example/lib/auto_close_screen.dart

@@ -27,7 +27,7 @@ class AutoCloseScreenState extends State<AutoCloseScreen> {
         description: 'running a $delayInSeconds seconds operation');
     await Future.delayed(const Duration(seconds: delayInSeconds));
     await childSpan?.finish();
-    SentryFlutter.reportFullDisplay();
+    SentryFlutter.reportFullyDisplayed();
     // ignore: use_build_context_synchronously
     // Navigator.of(context).pop();
   }

flutter/example/lib/main.dart

@@ -103,7 +103,7 @@ class _MyAppState extends State<MyApp> {
 
   @override
   Widget build(BuildContext context) {
-    SentryFlutter.reportFullDisplay();
+    // SentryFlutter.reportFullDisplay();
     return feedback.BetterFeedback(
       child: ChangeNotifierProvider<ThemeProvider>(
         create: (_) => ThemeProvider(),

flutter/lib/src/event_processor/native_app_start_event_processor.dart

@@ -2,6 +2,7 @@ import 'dart:async';
 
 import 'package:sentry/sentry.dart';
 
+import '../integrations/integrations.dart';
 import '../native/sentry_native.dart';
 
 /// EventProcessor that enriches [SentryTransaction] objects with app start
@@ -18,28 +19,9 @@ class NativeAppStartEventProcessor implements EventProcessor {
 
   @override
   Future<SentryEvent?> apply(SentryEvent event, {Hint? hint}) async {
-    final appStartEnd = _native.appStartEnd;
-
-    if (appStartEnd != null &&
-        event is SentryTransaction &&
-        !_native.didFetchAppStart) {
-      final nativeAppStart = await _native.fetchNativeAppStart();
-      if (nativeAppStart == null) {
-        return event;
-      }
-      final measurement = nativeAppStart.toMeasurement(appStartEnd);
-      // We filter out app start more than 60s.
-      // This could be due to many different reasons.
-      // If you do the manual init and init the SDK too late and it does not
-      // compute the app start end in the very first Screen.
-      // If the process starts but the App isn't in the foreground.
-      // If the system forked the process earlier to accelerate the app start.
-      // And some unknown reasons that could not be reproduced.
-      // We've seen app starts with hours, days and even months.
-      if (measurement.value >= _maxAppStartMillis) {
-        return event;
-      }
-
+    final appStartInfo = AppStartTracker().appStartInfo;
+    if (appStartInfo != null && event is SentryTransaction) {
+      final measurement = appStartInfo.measurement;
       event.measurements[measurement.name] = measurement;
     }
     return event;

flutter/lib/src/integrations/native_app_start_integration.dart

@@ -1,4 +1,5 @@
 import 'package:flutter/scheduler.dart';
+import 'package:meta/meta.dart';
 import 'package:sentry/sentry.dart';
 
 import '../../sentry_flutter.dart';
@@ -23,18 +24,14 @@ class NativeAppStartIntegration extends Integration<SentryFlutterOptions> {
             'Scheduler binding is null. Can\'t auto detect app start time.');
       } else {
         schedulerBinding.addPostFrameCallback((timeStamp) async {
+          final appStartEnd = options.clock();
           // ignore: invalid_use_of_internal_member
-          _native.appStartEnd = options.clock();
+          _native.appStartEnd = appStartEnd;
 
-          final appStartEnd = _native.appStartEnd;
+          if (!_native.didFetchAppStart) {
+            final nativeAppStart = await _native.fetchNativeAppStart();
+            final measurement = nativeAppStart?.toMeasurement(appStartEnd!);
 
-          if (_native.appStartEnd != null && !_native!.didFetchAppStart) {
-            print('fetch app start');
-            final nativeAppStart = await _native!.fetchNativeAppStart();
-            if (nativeAppStart == null) {
-              return;
-            }
-            final measurement = nativeAppStart.toMeasurement(appStartEnd!);
             // We filter out app start more than 60s.
             // This could be due to many different reasons.
             // If you do the manual init and init the SDK too late and it does not
@@ -43,49 +40,23 @@ class NativeAppStartIntegration extends Integration<SentryFlutterOptions> {
             // If the system forked the process earlier to accelerate the app start.
             // And some unknown reasons that could not be reproduced.
             // We've seen app starts with hours, days and even months.
-            if (measurement.value >= 60000) {
+            if (nativeAppStart == null ||
+                measurement == null ||
+                measurement.value >= 60000) {
+              AppStartTracker().setAppStartInfo(null);
               return;
             }
 
-            final appStartDateTime = DateTime.fromMillisecondsSinceEpoch(
-                nativeAppStart.appStartTime.toInt());
-
-            final transactionContext2 = SentryTransactionContext(
-              'root ("/")',
-              'ui.load',
-              transactionNameSource: SentryTransactionNameSource.component,
-              // ignore: invalid_use_of_internal_member
-              origin: SentryTraceOrigins.autoNavigationRouteObserver,
+            final appStartInfo = AppStartInfo(
+              DateTime.fromMillisecondsSinceEpoch(
+                  nativeAppStart.appStartTime.toInt()),
+              appStartEnd,
+              measurement,
             );
 
-            final transaction2 = hub.startTransactionWithContext(
-                transactionContext2,
-                waitForChildren: true,
-                autoFinishAfter: Duration(seconds: 3),
-                trimEnd: true,
-                startTimestamp: appStartDateTime,
-                onFinish: (transaction) async {
-              final nativeFrames = await _native
-                  ?.endNativeFramesCollection(transaction.context.traceId);
-              if (nativeFrames != null) {
-                final measurements = nativeFrames.toMeasurements();
-                for (final item in measurements.entries) {
-                  final measurement = item.value;
-                  transaction.setMeasurement(
-                    item.key,
-                    measurement.value,
-                    unit: measurement.unit,
-                  );
-                }
-              }
-            });
-
-            final ttidSpan = transaction2.startChild('ui.load.initial_display', startTimestamp: appStartDateTime);
-            await ttidSpan.finish(endTimestamp: appStartEnd);
-
-            SentryNavigatorObserver.ttfdSpan = transaction2.startChild('ui.load.full_display', startTimestamp: appStartDateTime);
-
-            print('end of the road');
+            AppStartTracker().setAppStartInfo(appStartInfo);
+          } else {
+            AppStartTracker().setAppStartInfo(null);
           }
         });
       }
@@ -99,3 +70,40 @@ class NativeAppStartIntegration extends Integration<SentryFlutterOptions> {
 
 /// Used to provide scheduler binding at call time.
 typedef SchedulerBindingProvider = SchedulerBinding? Function();
+
+@internal
+class AppStartInfo {
+  final DateTime start;
+  final DateTime end;
+  final SentryMeasurement measurement;
+
+  AppStartInfo(this.start, this.end, this.measurement);
+}
+
+@internal
+class AppStartTracker {
+  static final AppStartTracker _instance = AppStartTracker._internal();
+
+  factory AppStartTracker() => _instance;
+
+  AppStartInfo? _appStartInfo;
+
+  AppStartInfo? get appStartInfo => _appStartInfo;
+  Function(AppStartInfo?)? _callback;
+
+  AppStartTracker._internal();
+
+  void setAppStartInfo(AppStartInfo? appStartInfo) {
+    _appStartInfo = appStartInfo;
+    _notifyObserver();
+  }
+
+  void onAppStartComplete(Function(AppStartInfo?) callback) {
+    _callback = callback;
+    _callback?.call(_appStartInfo);
+  }
+
+  void _notifyObserver() {
+    _callback?.call(_appStartInfo);
+  }
+}