Fix: App hang being reported from background (#3298)

Some Apps may run in the background after receiving a notification or as part of background fetch.
We should not report app hang in this cases.

CHANGELOG.md

@@ -18,6 +18,7 @@
 
 ### Fixes
 
+- Reporting app hangs from background (#3298)
 - Missing `mechanism.handled` is not considered crash (#3353)
 
 ## 8.14.1
@@ -40,6 +41,7 @@ The MetricKit integration subscribes to [MXHangDiagnostic](https://developer.app
 [MXDiskWriteExceptionDiagnostic](https://developer.apple.com/documentation/metrickit/mxdiskwriteexceptiondiagnostic),
 and [MXCPUExceptionDiagnostic](https://developer.apple.com/documentation/metrickit/mxcpuexceptiondiagnostic).
 
+
 ## 8.13.1
 
 ### Fixes

Sources/Sentry/SentryANRTrackingIntegration.m

@@ -3,6 +3,7 @@
 #import "SentryClient+Private.h"
 #import "SentryCrashMachineContext.h"
 #import "SentryCrashWrapper.h"
+#import "SentryDependencyContainer.h"
 #import "SentryDispatchQueueWrapper.h"
 #import "SentryEvent.h"
 #import "SentryException.h"
@@ -14,9 +15,13 @@
 #import "SentryThread.h"
 #import "SentryThreadInspector.h"
 #import "SentryThreadWrapper.h"
-#import <SentryDependencyContainer.h>
+#import "SentryUIApplication.h"
 #import <SentryOptions+Private.h>
 
+#if SENTRY_HAS_UIKIT
+#    import <UIKit/UIKit.h>
+#endif
+
 NS_ASSUME_NONNULL_BEGIN
 
 @interface
@@ -61,6 +66,14 @@ - (void)dealloc
 
 - (void)anrDetected
 {
+#if SENTRY_HAS_UIKIT
+    // If the app is not active, the main thread may be blocked or too busy.
+    // Since there is no UI for the user to interact, there is no need to report app hang.
+    if (SentryDependencyContainer.sharedInstance.application.applicationState
+        != UIApplicationStateActive) {
+        return;
+    }
+#endif
     SentryThreadInspector *threadInspector = SentrySDK.currentHub.getClient.threadInspector;
 
     NSArray<SentryThread *> *threads = [threadInspector getCurrentThreadsWithStackTrace];

Sources/Sentry/SentryUIApplication.m

@@ -56,6 +56,11 @@ - (UIApplication *)sharedApplication
     return result;
 }
 
+- (UIApplicationState)applicationState
+{
+    return self.sharedApplication.applicationState;
+}
+
 @end
 
 #endif // SENTRY_HAS_UIKIT

Sources/Sentry/include/SentryUIApplication.h

@@ -7,13 +7,20 @@
 @class UIWindow;
 @protocol UIApplicationDelegate;
 
+typedef NS_ENUM(NSInteger, UIApplicationState);
+
 NS_ASSUME_NONNULL_BEGIN
 
 /**
  * A helper tool to retrieve informations from the application instance.
  */
 @interface SentryUIApplication : NSObject
 
+/**
+ * Returns the application state available at @c NSApplication.sharedApplication.applicationState
+ */
+@property (nonatomic, readonly) UIApplicationState applicationState;
+
 /**
  * Application shared UIApplication instance.
  */

Tests/SentryTests/Integrations/ANR/SentryANRTrackingIntegrationTests.swift

@@ -108,7 +108,23 @@ class SentryANRTrackingIntegrationTests: SentrySDKIntegrationTestsBase {
 
         assertNoEventCaptured()
     }
-
+#if os(iOS) || os(tvOS) || targetEnvironment(macCatalyst)
+    func testANRDetected_ButBackground_EventNotCaptured() {
+
+        class BackgroundSentryUIApplication: SentryUIApplication {
+            override var applicationState: UIApplication.State { .background }
+        }
+
+        givenInitializedTracker()
+        setUpThreadInspector()
+        SentryDependencyContainer.sharedInstance().application = BackgroundSentryUIApplication()
+
+        Dynamic(sut).anrDetected()
+
+        assertNoEventCaptured()
+    }
+#endif
+
     func testDealloc_CallsUninstall() {
         givenInitializedTracker()
 
@@ -137,7 +153,7 @@ class SentryANRTrackingIntegrationTests: SentrySDKIntegrationTestsBase {
 
     private func setUpThreadInspector(addThreads: Bool = true) {
         let threadInspector = TestThreadInspector.instance
-        
+
         if addThreads {
 
             let frame1 = Sentry.Frame()