ref(feedback): address review feedback for shake gesture detection

- Reuse single SentryShakeDetector instance across activity transitions
  instead of re-creating on every resume (reduces allocations)
- Memoize SensorManager and Sensor lookups to avoid repeated binder calls
- Use getDefaultSensor(TYPE_ACCELEROMETER, false) to avoid wakeup sensor
- Deliver sensor events on a background HandlerThread instead of main thread
- Use SentryUserFeedbackDialog.Builder directly with tracked activity
  instead of going through showDialog/CurrentActivityHolder
- Merge dialogActivity into currentActivity, use AppState.isInBackground()
  to gate against background shakes
- Fix integration count in SentryAndroidTest (19 -> 20)

Tested manually on Pixel 8 Pro by enabling useShakeGesture in the sample
app's SentryAndroid.init and verifying shake opens the feedback dialog.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: antonis

sentry-android-core/src/main/java/io/sentry/android/core/FeedbackShakeIntegration.java

@@ -23,15 +23,15 @@ public final class FeedbackShakeIntegration
     implements Integration, Closeable, Application.ActivityLifecycleCallbacks {
 
   private final @NotNull Application application;
-  private @Nullable SentryShakeDetector shakeDetector;
+  private final @NotNull SentryShakeDetector shakeDetector;
   private @Nullable SentryAndroidOptions options;
   private volatile @Nullable Activity currentActivity;
   private volatile boolean isDialogShowing = false;
-  private volatile @Nullable Activity dialogActivity;
   private volatile @Nullable Runnable previousOnFormClose;
 
   public FeedbackShakeIntegration(final @NotNull Application application) {
     this.application = Objects.requireNonNull(application, "Application is required");
+    this.shakeDetector = new SentryShakeDetector(io.sentry.NoOpLogger.getInstance());
   }
 
   @Override
@@ -42,6 +42,9 @@ public void register(final @NotNull IScopes scopes, final @NotNull SentryOptions
       return;
     }
 
+    // Re-assign a properly configured detector logger now that options are available
+    shakeDetector.init(application);
+
     addIntegrationToSdkVersion("FeedbackShake");
     application.registerActivityLifecycleCallbacks(this);
     options.getLogger().log(SentryLevel.DEBUG, "FeedbackShakeIntegration installed.");
@@ -95,9 +98,8 @@ public void onActivitySaveInstanceState(
   public void onActivityDestroyed(final @NotNull Activity activity) {
     // Only reset if this is the activity that hosts the dialog — the dialog cannot
     // outlive its host activity being destroyed.
-    if (activity == dialogActivity) {
+    if (isDialogShowing && activity == currentActivity) {
       isDialogShowing = false;
-      dialogActivity = null;
       if (options != null) {
         options.getFeedbackOptions().setOnFormClose(previousOnFormClose);
       }
@@ -109,39 +111,39 @@ private void startShakeDetection(final @NotNull Activity activity) {
     if (options == null) {
       return;
     }
-    // Stop any existing detector (e.g. when transitioning between activities)
+    // Stop any existing detection (e.g. when transitioning between activities)
     stopShakeDetection();
-    shakeDetector = new SentryShakeDetector(options.getLogger());
     shakeDetector.start(
         activity,
         () -> {
           final Activity active = currentActivity;
-          if (active != null && options != null && !isDialogShowing) {
+          final Boolean inBackground = AppState.getInstance().isInBackground();
+          if (active != null
+              && options != null
+              && !isDialogShowing
+              && !Boolean.TRUE.equals(inBackground)) {
             active.runOnUiThread(
                 () -> {
                   if (isDialogShowing) {
                     return;
                   }
                   try {
                     isDialogShowing = true;
-                    dialogActivity = active;
                     previousOnFormClose = options.getFeedbackOptions().getOnFormClose();
                     options
                         .getFeedbackOptions()
                         .setOnFormClose(
                             () -> {
                               isDialogShowing = false;
-                              dialogActivity = null;
                               options.getFeedbackOptions().setOnFormClose(previousOnFormClose);
                               if (previousOnFormClose != null) {
                                 previousOnFormClose.run();
                               }
                               previousOnFormClose = null;
                             });
-                    options.getFeedbackOptions().getDialogHandler().showDialog(null, null);
+                    new SentryUserFeedbackDialog.Builder(active).create().show();
                   } catch (Throwable e) {
                     isDialogShowing = false;
-                    dialogActivity = null;
                     options.getFeedbackOptions().setOnFormClose(previousOnFormClose);
                     previousOnFormClose = null;
                     options
@@ -154,9 +156,6 @@ private void startShakeDetection(final @NotNull Activity activity) {
   }
 
   private void stopShakeDetection() {
-    if (shakeDetector != null) {
-      shakeDetector.stop();
-      shakeDetector = null;
-    }
+    shakeDetector.stop();
   }
 }

sentry-android-core/src/main/java/io/sentry/android/core/SentryShakeDetector.java

@@ -5,6 +5,8 @@
 import android.hardware.SensorEvent;
 import android.hardware.SensorEventListener;
 import android.hardware.SensorManager;
+import android.os.Handler;
+import android.os.HandlerThread;
 import android.os.SystemClock;
 import io.sentry.ILogger;
 import io.sentry.SentryLevel;
@@ -21,6 +23,9 @@
  *
  * <p>Requires at least {@link #SHAKE_COUNT_THRESHOLD} accelerometer readings above {@link
  * #SHAKE_THRESHOLD_GRAVITY} within {@link #SHAKE_WINDOW_MS} to trigger a shake event.
+ *
+ * <p>Sensor events are delivered on a background {@link HandlerThread} to avoid polluting the main
+ * thread.
  */
 @ApiStatus.Internal
 public final class SentryShakeDetector implements SensorEventListener {
@@ -31,6 +36,8 @@ public final class SentryShakeDetector implements SensorEventListener {
   private static final int SHAKE_COOLDOWN_MS = 1000;
 
   private @Nullable SensorManager sensorManager;
+  private @Nullable Sensor accelerometer;
+  private @Nullable HandlerThread handlerThread;
   private final @NotNull AtomicLong lastShakeTimestamp = new AtomicLong(0);
   private volatile @Nullable Listener listener;
   private final @NotNull ILogger logger;
@@ -46,27 +53,46 @@ public SentryShakeDetector(final @NotNull ILogger logger) {
     this.logger = logger;
   }
 
+  /**
+   * Initializes the sensor manager and accelerometer sensor. This is separated from start() so the
+   * values can be resolved once and reused across activity transitions.
+   */
+  void init(final @NotNull Context context) {
+    if (sensorManager == null) {
+      sensorManager = (SensorManager) context.getSystemService(Context.SENSOR_SERVICE);
+    }
+    if (sensorManager != null && accelerometer == null) {
+      accelerometer = sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER, false);
+    }
+  }
+
   public void start(final @NotNull Context context, final @NotNull Listener shakeListener) {
     this.listener = shakeListener;
-    sensorManager = (SensorManager) context.getSystemService(Context.SENSOR_SERVICE);
+    init(context);
     if (sensorManager == null) {
       logger.log(SentryLevel.WARNING, "SensorManager is not available. Shake detection disabled.");
       return;
     }
-    Sensor accelerometer = sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
     if (accelerometer == null) {
       logger.log(
           SentryLevel.WARNING, "Accelerometer sensor not available. Shake detection disabled.");
       return;
     }
-    sensorManager.registerListener(this, accelerometer, SensorManager.SENSOR_DELAY_NORMAL);
+    handlerThread = new HandlerThread("sentry-shake");
+    handlerThread.start();
+    final Handler handler = new Handler(handlerThread.getLooper());
+    sensorManager.registerListener(
+        this, accelerometer, SensorManager.SENSOR_DELAY_NORMAL, handler);
   }
 
   public void stop() {
     listener = null;
     if (sensorManager != null) {
       sensorManager.unregisterListener(this);
-      sensorManager = null;
+    }
+    if (handlerThread != null) {
+      handlerThread.quitSafely();
+      handlerThread = null;
     }
   }
 

sentry-android-core/src/test/java/io/sentry/android/core/SentryAndroidTest.kt

@@ -477,7 +477,7 @@ class SentryAndroidTest {
     fixture.initSut(context = mock<Application>()) { options ->
       optionsRef = options
       options.dsn = "https://key@sentry.io/123"
-      assertEquals(19, options.integrations.size)
+      assertEquals(20, options.integrations.size)
       options.integrations.removeAll {
         it is UncaughtExceptionHandlerIntegration ||
           it is ShutdownHookIntegration ||

sentry-android-core/src/test/java/io/sentry/android/core/SentryShakeDetectorTest.kt

@@ -4,13 +4,15 @@ import android.content.Context
 import android.hardware.Sensor
 import android.hardware.SensorEvent
 import android.hardware.SensorManager
+import android.os.Handler
 import android.os.SystemClock
 import androidx.test.ext.junit.runners.AndroidJUnit4
 import io.sentry.ILogger
 import kotlin.test.Test
 import org.junit.runner.RunWith
 import org.mockito.kotlin.any
 import org.mockito.kotlin.eq
+import org.mockito.kotlin.isA
 import org.mockito.kotlin.mock
 import org.mockito.kotlin.never
 import org.mockito.kotlin.verify
@@ -28,7 +30,7 @@ class SentryShakeDetectorTest {
 
     init {
       whenever(context.getSystemService(Context.SENSOR_SERVICE)).thenReturn(sensorManager)
-      whenever(sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER)).thenReturn(accelerometer)
+      whenever(sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER, false)).thenReturn(accelerometer)
     }
 
     fun getSut(): SentryShakeDetector {
@@ -44,7 +46,7 @@ class SentryShakeDetectorTest {
     sut.start(fixture.context, fixture.listener)
 
     verify(fixture.sensorManager)
-      .registerListener(eq(sut), eq(fixture.accelerometer), eq(SensorManager.SENSOR_DELAY_NORMAL))
+      .registerListener(eq(sut), eq(fixture.accelerometer), eq(SensorManager.SENSOR_DELAY_NORMAL), isA<Handler>())
   }
 
   @Test
@@ -63,17 +65,17 @@ class SentryShakeDetectorTest {
     val sut = fixture.getSut()
     sut.start(fixture.context, fixture.listener)
 
-    verify(fixture.sensorManager, never()).registerListener(any(), any<Sensor>(), any())
+    verify(fixture.sensorManager, never()).registerListener(any(), any<Sensor>(), any<Int>(), any<Handler>())
   }
 
   @Test
   fun `does not crash when accelerometer is null`() {
-    whenever(fixture.sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER)).thenReturn(null)
+    whenever(fixture.sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER, false)).thenReturn(null)
 
     val sut = fixture.getSut()
     sut.start(fixture.context, fixture.listener)
 
-    verify(fixture.sensorManager, never()).registerListener(any(), any<Sensor>(), any())
+    verify(fixture.sensorManager, never()).registerListener(any(), any<Sensor>(), any<Int>(), any<Handler>())
   }
 
   @Test