fix: pause app hang detection when in background

CHANGELOG.md

@@ -13,6 +13,7 @@
 
 ### Fixes
 
+- The app hang detection now correctly pauses and resumes when the game moves between background and foreground to prevent false positive events ([#2788](https://github.com/getsentry/sentry-unity/pull/2788))
 - Migrated the native support for iOS and macOS to use the Obj-C flavour of `sentry-cocoa` ([#2767](https://github.com/getsentry/sentry-unity/pull/2767))
 - The SDK now correctly synchronizes the `Environment` set on the `Scope` events coming from the native layer ([#2764](https://github.com/getsentry/sentry-unity/pull/2764))
 
@@ -21,9 +22,9 @@
 - Bump .NET SDK from v6.5.0-33-g0140be0a to v6.8.0 ([#2761](https://github.com/getsentry/sentry-unity/pull/2761), [#2762](https://github.com/getsentry/sentry-unity/pull/2762), [#2776](https://github.com/getsentry/sentry-unity/pull/2776))
   - [changelog](https://github.com/getsentry/sentry-dotnet/blob/main/CHANGELOG.md#680)
   - [diff](https://github.com/getsentry/sentry-dotnet/compare/6.5.0-33-g0140be0a...6.8.0)
-- Bump Native SDK from v0.15.3 to v0.16.0 ([#2769](https://github.com/getsentry/sentry-unity/pull/2769), [#2779](https://github.com/getsentry/sentry-unity/pull/2779))
-  - [changelog](https://github.com/getsentry/sentry-native/blob/master/CHANGELOG.md#0160)
-  - [diff](https://github.com/getsentry/sentry-native/compare/0.15.3...0.16.0)
+- Bump Native SDK from v0.15.3 to v0.16.1 ([#2769](https://github.com/getsentry/sentry-unity/pull/2769), [#2779](https://github.com/getsentry/sentry-unity/pull/2779), [#2788](https://github.com/getsentry/sentry-unity/pull/2788))
+  - [changelog](https://github.com/getsentry/sentry-native/blob/master/CHANGELOG.md#0161)
+  - [diff](https://github.com/getsentry/sentry-native/compare/0.15.3...0.16.1)
 - Bump Cocoa SDK from v9.21.0 to v9.23.0 ([#2767](https://github.com/getsentry/sentry-unity/pull/2767))
   - [changelog](https://github.com/getsentry/sentry-cocoa/blob/main/CHANGELOG.md#9230)
   - [diff](https://github.com/getsentry/sentry-cocoa/compare/9.21.0...9.23.0)

src/Sentry.Unity.Android/SentryNative.cs

@@ -28,14 +28,20 @@ public static class SentryNative
 
     internal static void AppHangHeartbeat() => AppHangHeartbeatStrategy();
 
+    internal static void AppHangPause() => AppHangPauseStrategy();
+
     // libsentry.io
     [DllImport("sentry")]
     private static extern void sentry_reinstall_backend();
 
     [DllImport("sentry")]
     private static extern void sentry_app_hang_heartbeat();
 
+    [DllImport("sentry")]
+    private static extern void sentry_app_hang_pause();
+
     // Testing
     internal static Action ReinstallSentryNativeBackendStrategy = sentry_reinstall_backend;
     internal static Action AppHangHeartbeatStrategy = sentry_app_hang_heartbeat;
+    internal static Action AppHangPauseStrategy = sentry_app_hang_pause;
 }

src/Sentry.Unity.Android/SentryNativeAndroid.cs

@@ -77,7 +77,9 @@ public static void Configure(SentryUnityOptions options)
         if (options.NativeAppHangTrackingEnabled && options.NdkIntegrationEnabled)
         {
             Logger?.LogDebug("Starting the app-hang heartbeat coroutine.");
-            SentryMonoBehaviour.Instance.StartAppHangHeartbeat(SentryNative.AppHangHeartbeat);
+            SentryMonoBehaviour.Instance.StartAppHangHeartbeat(
+                SentryNative.AppHangHeartbeat,
+                SentryNative.AppHangPause);
             Logger?.LogDebug("Disabling the C# ANR watchdog - sentry-native handles app hang detection.");
             options.RemoveIntegration<AnrIntegration>();
         }

src/Sentry.Unity.Native/SentryNative.cs

@@ -97,7 +97,9 @@ internal static void Configure(SentryUnityOptions options, RuntimePlatform platf
         if (options.NativeAppHangTrackingEnabled)
         {
             Logger?.LogDebug("Starting the app-hang heartbeat coroutine.");
-            SentryMonoBehaviour.Instance.StartAppHangHeartbeat(SentryNativeBridge.AppHangHeartbeat);
+            SentryMonoBehaviour.Instance.StartAppHangHeartbeat(
+                SentryNativeBridge.AppHangHeartbeat,
+                SentryNativeBridge.AppHangPause);
 
             // sentry-native handles app-hang detection on the desktop platforms. Where it is effective, skip the
             // C# ANR watchdog so a hang isn't reported twice (mirrors the iOS/sentry-cocoa behavior).

src/Sentry.Unity.Native/SentryNativeBridge.cs

@@ -163,6 +163,8 @@ internal static string GetDatabasePath(SentryUnityOptions options, IApplication?
 
     internal static void AppHangHeartbeat() => sentry_app_hang_heartbeat();
 
+    internal static void AppHangPause() => sentry_app_hang_pause();
+
     // libsentry.so
     [DllImport(SentryLib)]
     private static extern IntPtr sentry_options_new();
@@ -211,6 +213,9 @@ internal static string GetDatabasePath(SentryUnityOptions options, IApplication?
     [DllImport(SentryLib)]
     private static extern void sentry_options_set_app_hang_timeout(IntPtr options, ulong timeout);
 
+    [DllImport(SentryLib)]
+    private static extern void sentry_app_hang_pause();
+
     [UnmanagedFunctionPointer(CallingConvention.Cdecl, SetLastError = true)]
     private delegate void sentry_logger_function_t(int level, IntPtr message, IntPtr argsAddress, IntPtr userData);
 

src/Sentry.Unity/SentryMonoBehaviour.AppHang.cs

@@ -14,6 +14,7 @@ public partial class SentryMonoBehaviour
     private static readonly TimeSpan AppHangHeartbeatInterval = TimeSpan.FromSeconds(1);
 
     private Coroutine? _appHangHeartbeat;
+    private Action? _appHangPause;
 
     /// <summary>
     /// Starts the app-hang heartbeat on the main thread at a fixed 1-second interval. Arming is
@@ -23,6 +24,18 @@ public partial class SentryMonoBehaviour
     public Coroutine StartAppHangHeartbeat(Action heartbeat) =>
         StartAppHangHeartbeat(heartbeat, AppHangHeartbeatInterval);
 
+    internal Coroutine StartAppHangHeartbeat(Action heartbeat, Action pause)
+    {
+        if (_appHangPause is not null)
+        {
+            ApplicationPausing -= _appHangPause;
+        }
+
+        _appHangPause = pause;
+        ApplicationPausing += pause;
+        return StartAppHangHeartbeat(heartbeat, AppHangHeartbeatInterval);
+    }
+
     // Internal overload so tests can use a short interval.
     internal Coroutine StartAppHangHeartbeat(Action heartbeat, TimeSpan interval)
     {

test/Sentry.Unity.Android.Tests/SentryNativeAndroidTests.cs

@@ -129,6 +129,25 @@ public void AppHangHeartbeat_InvokesNativeHeartbeat()
         }
     }
 
+    [Test]
+    public void AppHangPause_InvokesNativePause()
+    {
+        var pauseCalled = false;
+        var originalStrategy = Interlocked.Exchange(ref SentryNative.AppHangPauseStrategy,
+            () => pauseCalled = true);
+
+        try
+        {
+            SentryNative.AppHangPause();
+
+            Assert.True(pauseCalled);
+        }
+        finally
+        {
+            Interlocked.Exchange(ref SentryNative.AppHangPauseStrategy, originalStrategy);
+        }
+    }
+
     [Test]
     public void Configure_InstallationIdReturned_SetsDefaultUserId()
     {

test/Sentry.Unity.Tests/SentryMonoBehaviourAppHangTests.cs

@@ -58,4 +58,20 @@ public IEnumerator StartAppHangHeartbeat_StopsWhenObjectDestroyed()
 
         Assert.AreEqual(countAfterDestroy, count);
     }
+
+    [Test]
+    public void StartAppHangHeartbeat_PausesNativeDetectorWhenApplicationPauses()
+    {
+        var sut = GetSut();
+        var pauses = 0;
+
+        sut.StartAppHangHeartbeat(() => { }, () => pauses++);
+
+        sut.UpdatePauseStatus(true);
+        Assert.AreEqual(1, pauses);
+
+        sut.UpdatePauseStatus(false);
+        sut.UpdatePauseStatus(true);
+        Assert.AreEqual(2, pauses);
+    }
 }