Merge "Post UserTracker callbacks to background" into main

9 files changed, 238 insertions, 68 deletions

diff --git a/packages/SystemUI/src/com/android/keyguard/KeyguardUpdateMonitor.java b/packages/SystemUI/src/com/android/keyguard/KeyguardUpdateMonitor.java
index 0f733c6e1f24..422b2e1a1d28 100644
--- a/packages/SystemUI/src/com/android/keyguard/KeyguardUpdateMonitor.java
+++ b/packages/SystemUI/src/com/android/keyguard/KeyguardUpdateMonitor.java
@@ -203,7 +203,6 @@ import java.util.Map.Entry;
 import java.util.Optional;
 import java.util.Set;
 import java.util.TimeZone;
-import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.Executor;
 import java.util.stream.Collectors;
 
@@ -2440,7 +2439,7 @@ public class KeyguardUpdateMonitor implements TrustManager.TrustListener, Dumpab
                         handleDevicePolicyManagerStateChanged(msg.arg1);
                         break;
                     case MSG_USER_SWITCHING:
-                        handleUserSwitching(msg.arg1, (CountDownLatch) msg.obj);
+                        handleUserSwitching(msg.arg1, (Runnable) msg.obj);
                         break;
                     case MSG_USER_SWITCH_COMPLETE:
                         handleUserSwitchComplete(msg.arg1);
@@ -2741,10 +2740,12 @@ public class KeyguardUpdateMonitor implements TrustManager.TrustListener, Dumpab
     }
 
     private final UserTracker.Callback mUserChangedCallback = new UserTracker.Callback() {
+
         @Override
-        public void onUserChanging(int newUser, Context userContext, CountDownLatch latch) {
+        public void onUserChanging(int newUser, @NonNull Context userContext,
+                @NonNull Runnable resultCallback) {
             mHandler.sendMessage(mHandler.obtainMessage(MSG_USER_SWITCHING,
-                    newUser, 0, latch));
+                    newUser, 0, resultCallback));
         }
 
         @Override
@@ -3575,7 +3576,7 @@ public class KeyguardUpdateMonitor implements TrustManager.TrustListener, Dumpab
      * Handle {@link #MSG_USER_SWITCHING}
      */
     @VisibleForTesting
-    void handleUserSwitching(int userId, CountDownLatch latch) {
+    void handleUserSwitching(int userId, Runnable resultCallback) {
         mLogger.logUserSwitching(userId, "from UserTracker");
         Assert.isMainThread();
         clearBiometricRecognized();
@@ -3589,7 +3590,7 @@ public class KeyguardUpdateMonitor implements TrustManager.TrustListener, Dumpab
                 cb.onUserSwitching(userId);
             }
         }
-        latch.countDown();
+        resultCallback.run();
     }
 
     /**
diff --git a/packages/SystemUI/src/com/android/systemui/recents/OverviewProxyService.java b/packages/SystemUI/src/com/android/systemui/recents/OverviewProxyService.java
index cef52e73d711..d0ceaf6075fa 100644
--- a/packages/SystemUI/src/com/android/systemui/recents/OverviewProxyService.java
+++ b/packages/SystemUI/src/com/android/systemui/recents/OverviewProxyService.java
@@ -117,7 +117,6 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.Objects;
 import java.util.Optional;
-import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.Executor;
 import java.util.function.Supplier;
 
@@ -492,9 +491,9 @@ public class OverviewProxyService implements CallbackController<OverviewProxyLis
             notifySystemUiStateFlags(mSysUiState.getFlags());
 
             notifyConnectionChanged();
-            if (mLatchForOnUserChanging != null) {
-                mLatchForOnUserChanging.countDown();
-                mLatchForOnUserChanging = null;
+            if (mDoneUserChanging != null) {
+                mDoneUserChanging.run();
+                mDoneUserChanging = null;
             }
         }
 
@@ -550,14 +549,14 @@ public class OverviewProxyService implements CallbackController<OverviewProxyLis
         }
     };
 
-    private CountDownLatch mLatchForOnUserChanging;
+    private Runnable mDoneUserChanging;
     private final UserTracker.Callback mUserChangedCallback =
             new UserTracker.Callback() {
                 @Override
                 public void onUserChanging(int newUser, @NonNull Context userContext,
-                        CountDownLatch latch) {
+                        @NonNull Runnable resultCallback) {
                     mConnectionBackoffAttempts = 0;
-                    mLatchForOnUserChanging = latch;
+                    mDoneUserChanging = resultCallback;
                     internalConnectToCurrentUser("User changed");
                 }
             };
diff --git a/packages/SystemUI/src/com/android/systemui/settings/UserTracker.kt b/packages/SystemUI/src/com/android/systemui/settings/UserTracker.kt
index 93a3e905f0e0..bd592c9daff6 100644
--- a/packages/SystemUI/src/com/android/systemui/settings/UserTracker.kt
+++ b/packages/SystemUI/src/com/android/systemui/settings/UserTracker.kt
@@ -19,7 +19,6 @@ package com.android.systemui.settings
 import android.content.Context
 import android.content.pm.UserInfo
 import android.os.UserHandle
-import java.util.concurrent.CountDownLatch
 import java.util.concurrent.Executor
 
 /**
@@ -68,8 +67,8 @@ interface UserTracker : UserContentResolverProvider, UserContextProvider {
     interface Callback {
 
         /**
-         * Same as {@link onUserChanging(Int, Context, CountDownLatch)} but the latch will be
-         * auto-decremented after the completion of this method.
+         * Same as {@link onUserChanging(Int, Context, Runnable)} but the callback will be
+         * called automatically after the completion of this method.
          */
         fun onUserChanging(newUser: Int, userContext: Context) {}
 
@@ -78,12 +77,12 @@ interface UserTracker : UserContentResolverProvider, UserContextProvider {
          * Override this method to run things while the screen is frozen for the user switch.
          * Please use {@link #onUserChanged} if the task doesn't need to push the unfreezing of the
          * screen further. Please be aware that code executed in this callback will lengthen the
-         * user switch duration. When overriding this method, countDown() MUST be called on the
-         * latch once execution is complete.
+         * user switch duration. When overriding this method, resultCallback#run() MUST be called
+         * once the  execution is complete.
          */
-        fun onUserChanging(newUser: Int, userContext: Context, latch: CountDownLatch) {
+        fun onUserChanging(newUser: Int, userContext: Context, resultCallback: Runnable) {
             onUserChanging(newUser, userContext)
-            latch.countDown()
+            resultCallback.run()
         }
 
         /**
diff --git a/packages/SystemUI/src/com/android/systemui/settings/UserTrackerImpl.kt b/packages/SystemUI/src/com/android/systemui/settings/UserTrackerImpl.kt
index 5fb3c01bbc1d..2f873019349c 100644
--- a/packages/SystemUI/src/com/android/systemui/settings/UserTrackerImpl.kt
+++ b/packages/SystemUI/src/com/android/systemui/settings/UserTrackerImpl.kt
@@ -33,11 +33,22 @@ import androidx.annotation.GuardedBy
 import androidx.annotation.WorkerThread
 import com.android.systemui.Dumpable
 import com.android.systemui.dump.DumpManager
+import com.android.systemui.flags.FeatureFlagsClassic
+import com.android.systemui.flags.Flags
 import com.android.systemui.util.Assert
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.asCoroutineDispatcher
+import kotlinx.coroutines.coroutineScope
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.sync.Mutex
 import java.io.PrintWriter
 import java.lang.ref.WeakReference
 import java.util.concurrent.CountDownLatch
 import java.util.concurrent.Executor
+import javax.inject.Provider
 import kotlin.properties.ReadWriteProperty
 import kotlin.reflect.KProperty
 
@@ -58,20 +69,26 @@ import kotlin.reflect.KProperty
  */
 open class UserTrackerImpl internal constructor(
     private val context: Context,
+    private val featureFlagsProvider: Provider<FeatureFlagsClassic>,
     private val userManager: UserManager,
     private val iActivityManager: IActivityManager,
     private val dumpManager: DumpManager,
-    private val backgroundHandler: Handler
+    private val appScope: CoroutineScope,
+    private val backgroundContext: CoroutineDispatcher,
+    private val backgroundHandler: Handler,
 ) : UserTracker, Dumpable, BroadcastReceiver() {
 
     companion object {
         private const val TAG = "UserTrackerImpl"
+        private const val USER_CHANGE_THRESHOLD = 5L * 1000 // 5 sec
     }
 
     var initialized = false
         private set
 
     private val mutex = Any()
+    private val isBackgroundUserSwitchEnabled: Boolean get() =
+        featureFlagsProvider.get().isEnabled(Flags.USER_TRACKER_BACKGROUND_CALLBACKS)
 
     override var userId: Int by SynchronizedDelegate(context.userId)
         protected set
@@ -103,6 +120,10 @@ open class UserTrackerImpl internal constructor(
     @GuardedBy("callbacks")
     private val callbacks: MutableList<DataItem> = ArrayList()
 
+    private var beforeUserSwitchingJob: Job? = null
+    private var userSwitchingJob: Job? = null
+    private var afterUserSwitchingJob: Job? = null
+
     open fun initialize(startingUser: Int) {
         if (initialized) {
             return
@@ -119,7 +140,7 @@ open class UserTrackerImpl internal constructor(
             addAction(Intent.ACTION_MANAGED_PROFILE_REMOVED)
             addAction(Intent.ACTION_MANAGED_PROFILE_UNLOCKED)
         }
-        context.registerReceiverForAllUsers(this, filter, null /* permission */, backgroundHandler)
+        context.registerReceiverForAllUsers(this, filter, null, backgroundHandler)
 
         registerUserSwitchObserver()
 
@@ -162,16 +183,39 @@ open class UserTrackerImpl internal constructor(
     private fun registerUserSwitchObserver() {
         iActivityManager.registerUserSwitchObserver(object : UserSwitchObserver() {
             override fun onBeforeUserSwitching(newUserId: Int) {
-                handleBeforeUserSwitching(newUserId)
+                if (isBackgroundUserSwitchEnabled) {
+                    beforeUserSwitchingJob?.cancel()
+                    beforeUserSwitchingJob = appScope.launch(backgroundContext) {
+                        handleBeforeUserSwitching(newUserId)
+                    }
+                } else {
+                    handleBeforeUserSwitching(newUserId)
+                }
             }
 
             override fun onUserSwitching(newUserId: Int, reply: IRemoteCallback?) {
-                handleUserSwitching(newUserId)
-                reply?.sendResult(null)
+                if (isBackgroundUserSwitchEnabled) {
+                    userSwitchingJob?.cancel()
+                    userSwitchingJob = appScope.launch(backgroundContext) {
+                        handleUserSwitchingCoroutines(newUserId) {
+                            reply?.sendResult(null)
+                        }
+                    }
+                } else {
+                    handleUserSwitching(newUserId)
+                    reply?.sendResult(null)
+                }
             }
 
             override fun onUserSwitchComplete(newUserId: Int) {
-                handleUserSwitchComplete(newUserId)
+                if (isBackgroundUserSwitchEnabled) {
+                    afterUserSwitchingJob?.cancel()
+                    afterUserSwitchingJob = appScope.launch(backgroundContext) {
+                        handleUserSwitchComplete(newUserId)
+                    }
+                } else {
+                    handleUserSwitchComplete(newUserId)
+                }
             }
         }, TAG)
     }
@@ -195,7 +239,7 @@ open class UserTrackerImpl internal constructor(
             val callback = it.callback.get()
             if (callback != null) {
                 it.executor.execute {
-                    callback.onUserChanging(userId, userContext, latch)
+                    callback.onUserChanging(userId, userContext) { latch.countDown() }
                 }
             } else {
                 latch.countDown()
@@ -205,6 +249,28 @@ open class UserTrackerImpl internal constructor(
     }
 
     @WorkerThread
+    protected open suspend fun handleUserSwitchingCoroutines(newUserId: Int, onDone: () -> Unit) =
+            coroutineScope {
+                Assert.isNotMainThread()
+                Log.i(TAG, "Switching to user $newUserId")
+
+                for (callbackDataItem in synchronized(callbacks) { callbacks.toList() }) {
+                    val callback: UserTracker.Callback = callbackDataItem.callback.get() ?: continue
+                    launch(callbackDataItem.executor.asCoroutineDispatcher()) {
+                        val mutex = Mutex(true)
+                        val thresholdLogJob = launch(backgroundContext) {
+                            delay(USER_CHANGE_THRESHOLD)
+                            Log.e(TAG, "Failed to finish $callback in time")
+                        }
+                        callback.onUserChanging(userId, userContext) { mutex.unlock() }
+                        mutex.lock()
+                        thresholdLogJob.cancel()
+                    }.join()
+                }
+                onDone()
+            }
+
+    @WorkerThread
     protected open fun handleUserSwitchComplete(newUserId: Int) {
         Assert.isNotMainThread()
         Log.i(TAG, "Switched to user $newUserId")
diff --git a/packages/SystemUI/src/com/android/systemui/settings/dagger/MultiUserUtilsModule.java b/packages/SystemUI/src/com/android/systemui/settings/dagger/MultiUserUtilsModule.java
index e9a1dd7e6ecb..a0dd924b3959 100644
--- a/packages/SystemUI/src/com/android/systemui/settings/dagger/MultiUserUtilsModule.java
+++ b/packages/SystemUI/src/com/android/systemui/settings/dagger/MultiUserUtilsModule.java
@@ -25,8 +25,10 @@ import android.os.UserManager;
 
 import com.android.systemui.CoreStartable;
 import com.android.systemui.dagger.SysUISingleton;
+import com.android.systemui.dagger.qualifiers.Application;
 import com.android.systemui.dagger.qualifiers.Background;
 import com.android.systemui.dump.DumpManager;
+import com.android.systemui.flags.FeatureFlagsClassic;
 import com.android.systemui.settings.DisplayTracker;
 import com.android.systemui.settings.DisplayTrackerImpl;
 import com.android.systemui.settings.UserContentResolverProvider;
@@ -42,6 +44,11 @@ import dagger.Provides;
 import dagger.multibindings.ClassKey;
 import dagger.multibindings.IntoMap;
 
+import javax.inject.Provider;
+
+import kotlinx.coroutines.CoroutineDispatcher;
+import kotlinx.coroutines.CoroutineScope;
+
 /**
  * Dagger Module for classes found within the com.android.systemui.settings package.
  */
@@ -60,14 +67,17 @@ public abstract class MultiUserUtilsModule {
     @Provides
     static UserTracker provideUserTracker(
             Context context,
+            Provider<FeatureFlagsClassic> featureFlagsProvider,
             UserManager userManager,
             IActivityManager iActivityManager,
             DumpManager dumpManager,
+            @Application CoroutineScope appScope,
+            @Background CoroutineDispatcher backgroundDispatcher,
             @Background Handler handler
     ) {
         int startingUser = ActivityManager.getCurrentUser();
-        UserTrackerImpl tracker = new UserTrackerImpl(context, userManager, iActivityManager,
-                dumpManager, handler);
+        UserTrackerImpl tracker = new UserTrackerImpl(context, featureFlagsProvider, userManager,
+                iActivityManager, dumpManager, appScope, backgroundDispatcher, handler);
         tracker.initialize(startingUser);
         return tracker;
     }
diff --git a/packages/SystemUI/tests/src/com/android/keyguard/KeyguardUpdateMonitorTest.java b/packages/SystemUI/tests/src/com/android/keyguard/KeyguardUpdateMonitorTest.java
index 562d3a557ea2..29511329b630 100644
--- a/packages/SystemUI/tests/src/com/android/keyguard/KeyguardUpdateMonitorTest.java
+++ b/packages/SystemUI/tests/src/com/android/keyguard/KeyguardUpdateMonitorTest.java
@@ -172,7 +172,6 @@ import java.util.Arrays;
 import java.util.List;
 import java.util.Optional;
 import java.util.Random;
-import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.Executor;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
@@ -1363,7 +1362,7 @@ public class KeyguardUpdateMonitorTest extends SysuiTestCase {
         assertThat(mKeyguardUpdateMonitor.mUserFingerprintAuthenticated.size()).isEqualTo(1);
         assertThat(mKeyguardUpdateMonitor.mUserFaceAuthenticated.size()).isEqualTo(1);
 
-        mKeyguardUpdateMonitor.handleUserSwitching(10 /* user */, new CountDownLatch(0));
+        mKeyguardUpdateMonitor.handleUserSwitching(10 /* user */, () -> {});
         assertThat(mKeyguardUpdateMonitor.mUserFingerprintAuthenticated.size()).isEqualTo(0);
         assertThat(mKeyguardUpdateMonitor.mUserFaceAuthenticated.size()).isEqualTo(0);
     }
diff --git a/packages/SystemUI/tests/src/com/android/systemui/settings/UserTrackerImplReceiveTest.kt b/packages/SystemUI/tests/src/com/android/systemui/settings/UserTrackerImplReceiveTest.kt
index beb981d89735..1bb2ff825115 100644
--- a/packages/SystemUI/tests/src/com/android/systemui/settings/UserTrackerImplReceiveTest.kt
+++ b/packages/SystemUI/tests/src/com/android/systemui/settings/UserTrackerImplReceiveTest.kt
@@ -11,10 +11,13 @@ import androidx.concurrent.futures.DirectExecutor
 import androidx.test.filters.SmallTest
 import com.android.systemui.SysuiTestCase
 import com.android.systemui.dump.DumpManager
+import com.android.systemui.flags.FakeFeatureFlagsClassic
 import com.android.systemui.util.mockito.any
 import com.android.systemui.util.mockito.capture
 import com.google.common.truth.Truth.assertThat
 import java.util.concurrent.Executor
+import kotlinx.coroutines.test.StandardTestDispatcher
+import kotlinx.coroutines.test.runTest
 import org.junit.Before
 import org.junit.Test
 import org.junit.runner.RunWith
@@ -60,6 +63,9 @@ class UserTrackerImplReceiveTest : SysuiTestCase() {
     @Mock private lateinit var callback: UserTracker.Callback
     @Captor private lateinit var captor: ArgumentCaptor<List<UserInfo>>
 
+    private val fakeFeatures = FakeFeatureFlagsClassic()
+    private val testDispatcher = StandardTestDispatcher()
+
     private lateinit var tracker: UserTrackerImpl
 
     @Before
@@ -68,12 +74,21 @@ class UserTrackerImplReceiveTest : SysuiTestCase() {
 
         `when`(context.user).thenReturn(UserHandle.SYSTEM)
         `when`(context.createContextAsUser(ArgumentMatchers.any(), anyInt())).thenReturn(context)
-
-        tracker = UserTrackerImpl(context, userManager, iActivityManager, dumpManager, handler)
     }
 
     @Test
-    fun callsCallbackAndUpdatesProfilesWhenAnIntentReceived() {
+    fun callsCallbackAndUpdatesProfilesWhenAnIntentReceived() = runTest {
+        tracker =
+            UserTrackerImpl(
+                context,
+                { fakeFeatures },
+                userManager,
+                iActivityManager,
+                dumpManager,
+                this,
+                testDispatcher,
+                handler
+            )
         tracker.initialize(0)
         tracker.addCallback(callback, executor)
         val profileID = tracker.userId + 10
diff --git a/packages/SystemUI/tests/src/com/android/systemui/settings/UserTrackerImplTest.kt b/packages/SystemUI/tests/src/com/android/systemui/settings/UserTrackerImplTest.kt
index aa98f08e9015..52b25f85b870 100644
--- a/packages/SystemUI/tests/src/com/android/systemui/settings/UserTrackerImplTest.kt
+++ b/packages/SystemUI/tests/src/com/android/systemui/settings/UserTrackerImplTest.kt
@@ -26,16 +26,25 @@ import android.os.Handler
 import android.os.IRemoteCallback
 import android.os.UserHandle
 import android.os.UserManager
-import android.testing.AndroidTestingRunner
 import androidx.test.filters.SmallTest
 import com.android.systemui.SysuiTestCase
 import com.android.systemui.dump.DumpManager
+import com.android.systemui.flags.FakeFeatureFlagsClassic
+import com.android.systemui.flags.Flags
+import com.android.systemui.util.concurrency.FakeExecutor
 import com.android.systemui.util.mockito.capture
+import com.android.systemui.util.time.FakeSystemClock
 import com.google.common.truth.Truth.assertThat
-import java.util.concurrent.Executor
+import com.google.common.truth.TruthJUnit.assume
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.test.StandardTestDispatcher
+import kotlinx.coroutines.test.TestScope
+import kotlinx.coroutines.test.runCurrent
+import kotlinx.coroutines.test.runTest
 import org.junit.Before
 import org.junit.Test
 import org.junit.runner.RunWith
+import org.junit.runners.Parameterized
 import org.mockito.ArgumentCaptor
 import org.mockito.ArgumentMatchers.any
 import org.mockito.ArgumentMatchers.anyInt
@@ -43,28 +52,52 @@ import org.mockito.ArgumentMatchers.anyString
 import org.mockito.ArgumentMatchers.eq
 import org.mockito.ArgumentMatchers.isNull
 import org.mockito.Mock
+import org.mockito.Mockito.never
 import org.mockito.Mockito.verify
 import org.mockito.Mockito.`when`
 import org.mockito.MockitoAnnotations
+import java.util.concurrent.Executor
+
 
+@OptIn(ExperimentalCoroutinesApi::class)
 @SmallTest
-@RunWith(AndroidTestingRunner::class)
+@RunWith(Parameterized::class)
 class UserTrackerImplTest : SysuiTestCase() {
 
+    companion object {
+
+        @JvmStatic
+        @Parameterized.Parameters
+        fun isBackgroundUserTrackerEnabled(): Iterable<Boolean> = listOf(true, false)
+    }
+
     @Mock
     private lateinit var context: Context
+
     @Mock
     private lateinit var userManager: UserManager
+
     @Mock
     private lateinit var iActivityManager: IActivityManager
+
     @Mock
     private lateinit var userSwitchingReply: IRemoteCallback
+
     @Mock(stubOnly = true)
     private lateinit var dumpManager: DumpManager
+
     @Mock(stubOnly = true)
     private lateinit var handler: Handler
 
+    @Parameterized.Parameter
+    @JvmField
+    var isBackgroundUserTrackerEnabled: Boolean = false
+
+    private val testScope = TestScope()
+    private val testDispatcher = StandardTestDispatcher(testScope.testScheduler)
     private val executor = Executor(Runnable::run)
+    private val featureFlags = FakeFeatureFlagsClassic()
+
     private lateinit var tracker: UserTrackerImpl
 
     @Before
@@ -84,54 +117,65 @@ class UserTrackerImplTest : SysuiTestCase() {
             listOf(info)
         }
 
-        tracker = UserTrackerImpl(context, userManager, iActivityManager, dumpManager, handler)
+        featureFlags.set(Flags.USER_TRACKER_BACKGROUND_CALLBACKS, isBackgroundUserTrackerEnabled)
+        tracker =
+                UserTrackerImpl(
+                        context,
+                        { featureFlags },
+                        userManager,
+                        iActivityManager,
+                        dumpManager,
+                        testScope.backgroundScope,
+                        testDispatcher,
+                        handler,
+                )
     }
 
     @Test
-    fun testNotInitialized() {
+    fun testNotInitialized() = testScope.runTest {
         assertThat(tracker.initialized).isFalse()
     }
 
     @Test(expected = IllegalStateException::class)
-    fun testGetUserIdBeforeInitThrowsException() {
+    fun testGetUserIdBeforeInitThrowsException() = testScope.runTest {
         tracker.userId
     }
 
     @Test(expected = IllegalStateException::class)
-    fun testGetUserHandleBeforeInitThrowsException() {
+    fun testGetUserHandleBeforeInitThrowsException() = testScope.runTest {
         tracker.userHandle
     }
 
     @Test(expected = IllegalStateException::class)
-    fun testGetUserContextBeforeInitThrowsException() {
+    fun testGetUserContextBeforeInitThrowsException() = testScope.runTest {
         tracker.userContext
     }
 
     @Test(expected = IllegalStateException::class)
-    fun testGetUserContentResolverBeforeInitThrowsException() {
+    fun testGetUserContentResolverBeforeInitThrowsException() = testScope.runTest {
         tracker.userContentResolver
     }
 
     @Test(expected = IllegalStateException::class)
-    fun testGetUserProfilesBeforeInitThrowsException() {
+    fun testGetUserProfilesBeforeInitThrowsException() = testScope.runTest {
         tracker.userProfiles
     }
 
     @Test
-    fun testInitialize() {
+    fun testInitialize() = testScope.runTest {
         tracker.initialize(0)
 
         assertThat(tracker.initialized).isTrue()
     }
 
     @Test
-    fun testReceiverRegisteredOnInitialize() {
+    fun testReceiverRegisteredOnInitialize() = testScope.runTest {
         tracker.initialize(0)
 
         val captor = ArgumentCaptor.forClass(IntentFilter::class.java)
 
-        verify(context).registerReceiverForAllUsers(
-                eq(tracker), capture(captor), isNull(), eq(handler))
+        verify(context)
+                .registerReceiverForAllUsers(eq(tracker), capture(captor), isNull(), eq(handler))
         with(captor.value) {
             assertThat(countActions()).isEqualTo(6)
             assertThat(hasAction(Intent.ACTION_USER_INFO_CHANGED)).isTrue()
@@ -144,7 +188,7 @@ class UserTrackerImplTest : SysuiTestCase() {
     }
 
     @Test
-    fun testInitialValuesSet() {
+    fun testInitialValuesSet() = testScope.runTest {
         val testID = 4
         tracker.initialize(testID)
 
@@ -161,7 +205,7 @@ class UserTrackerImplTest : SysuiTestCase() {
     }
 
     @Test
-    fun testUserSwitch() {
+    fun testUserSwitch() = testScope.runTest {
         tracker.initialize(0)
         val newID = 5
 
@@ -169,6 +213,7 @@ class UserTrackerImplTest : SysuiTestCase() {
         verify(iActivityManager).registerUserSwitchObserver(capture(captor), anyString())
         captor.value.onBeforeUserSwitching(newID)
         captor.value.onUserSwitching(newID, userSwitchingReply)
+        runCurrent()
         verify(userSwitchingReply).sendResult(any())
 
         verify(userManager).getProfiles(newID)
@@ -184,7 +229,7 @@ class UserTrackerImplTest : SysuiTestCase() {
     }
 
     @Test
-    fun testManagedProfileAvailable() {
+    fun testManagedProfileAvailable() = testScope.runTest {
         tracker.initialize(0)
         val profileID = tracker.userId + 10
 
@@ -209,7 +254,8 @@ class UserTrackerImplTest : SysuiTestCase() {
         assertThat(tracker.userProfiles.map { it.id }).containsExactly(tracker.userId, profileID)
     }
 
-    fun testManagedProfileUnavailable() {
+    @Test
+    fun testManagedProfileUnavailable() = testScope.runTest {
         tracker.initialize(0)
         val profileID = tracker.userId + 10
 
@@ -234,7 +280,8 @@ class UserTrackerImplTest : SysuiTestCase() {
         assertThat(tracker.userProfiles.map { it.id }).containsExactly(tracker.userId, profileID)
     }
 
-    fun testManagedProfileStartedAndRemoved() {
+    @Test
+    fun testManagedProfileStartedAndRemoved() = testScope.runTest {
         tracker.initialize(0)
         val profileID = tracker.userId + 10
 
@@ -271,7 +318,7 @@ class UserTrackerImplTest : SysuiTestCase() {
     }
 
     @Test
-    fun testCallbackNotCalledOnAdd() {
+    fun testCallbackNotCalledOnAdd() = testScope.runTest {
         tracker.initialize(0)
         val callback = TestCallback()
 
@@ -282,7 +329,7 @@ class UserTrackerImplTest : SysuiTestCase() {
     }
 
     @Test
-    fun testCallbackCalledOnUserChanging() {
+    fun testCallbackCalledOnUserChanging() = testScope.runTest {
         tracker.initialize(0)
         val callback = TestCallback()
         tracker.addCallback(callback, executor)
@@ -293,15 +340,49 @@ class UserTrackerImplTest : SysuiTestCase() {
         verify(iActivityManager).registerUserSwitchObserver(capture(captor), anyString())
         captor.value.onBeforeUserSwitching(newID)
         captor.value.onUserSwitching(newID, userSwitchingReply)
-        verify(userSwitchingReply).sendResult(any())
+        runCurrent()
 
+        verify(userSwitchingReply).sendResult(any())
         assertThat(callback.calledOnUserChanging).isEqualTo(1)
         assertThat(callback.lastUser).isEqualTo(newID)
         assertThat(callback.lastUserContext?.userId).isEqualTo(newID)
     }
 
     @Test
-    fun testCallbackCalledOnUserChanged() {
+    fun testAsyncCallbackWaitsUserToChange() = testScope.runTest {
+        // Skip this test for CountDownLatch variation. The problem is that there would be a
+        // deadlock if the callbacks processing runs on the same thread as the callback (which
+        // is blocked by the latch). Before the change it works because the callbacks are
+        // processed on a binder thread which is always distinct.
+        // This is the issue that this feature addresses.
+        assume().that(isBackgroundUserTrackerEnabled).isTrue()
+
+        tracker.initialize(0)
+        val callback = TestCallback()
+        val callbackExecutor = FakeExecutor(FakeSystemClock())
+        tracker.addCallback(callback, callbackExecutor)
+
+        val newID = 5
+
+        val captor = ArgumentCaptor.forClass(IUserSwitchObserver::class.java)
+        verify(iActivityManager).registerUserSwitchObserver(capture(captor), anyString())
+        captor.value.onBeforeUserSwitching(newID)
+        captor.value.onUserSwitching(newID, userSwitchingReply)
+
+        assertThat(callback.calledOnUserChanging).isEqualTo(0)
+        verify(userSwitchingReply, never()).sendResult(any())
+
+        FakeExecutor.exhaustExecutors(callbackExecutor)
+        runCurrent()
+        FakeExecutor.exhaustExecutors(callbackExecutor)
+        runCurrent()
+
+        assertThat(callback.calledOnUserChanging).isEqualTo(1)
+        verify(userSwitchingReply).sendResult(any())
+    }
+
+    @Test
+    fun testCallbackCalledOnUserChanged() = testScope.runTest {
         tracker.initialize(0)
         val callback = TestCallback()
         tracker.addCallback(callback, executor)
@@ -312,6 +393,7 @@ class UserTrackerImplTest : SysuiTestCase() {
         verify(iActivityManager).registerUserSwitchObserver(capture(captor), anyString())
         captor.value.onBeforeUserSwitching(newID)
         captor.value.onUserSwitchComplete(newID)
+        runCurrent()
 
         assertThat(callback.calledOnUserChanged).isEqualTo(1)
         assertThat(callback.lastUser).isEqualTo(newID)
@@ -321,7 +403,7 @@ class UserTrackerImplTest : SysuiTestCase() {
     }
 
     @Test
-    fun testCallbackCalledOnUserInfoChanged() {
+    fun testCallbackCalledOnUserInfoChanged() = testScope.runTest {
         tracker.initialize(0)
         val callback = TestCallback()
         tracker.addCallback(callback, executor)
@@ -331,18 +413,18 @@ class UserTrackerImplTest : SysuiTestCase() {
             val id = invocation.getArgument<Int>(0)
             val info = UserInfo(id, "", UserInfo.FLAG_FULL)
             val infoProfile = UserInfo(
-                id + 10,
-                "",
-                "",
-                UserInfo.FLAG_MANAGED_PROFILE,
-                UserManager.USER_TYPE_PROFILE_MANAGED
+                    id + 10,
+                    "",
+                    "",
+                    UserInfo.FLAG_MANAGED_PROFILE,
+                    UserManager.USER_TYPE_PROFILE_MANAGED
             )
             infoProfile.profileGroupId = id
             listOf(info, infoProfile)
         }
 
         val intent = Intent(Intent.ACTION_USER_INFO_CHANGED)
-            .putExtra(Intent.EXTRA_USER, UserHandle.of(profileID))
+                .putExtra(Intent.EXTRA_USER, UserHandle.of(profileID))
 
         tracker.onReceive(context, intent)
 
@@ -352,7 +434,7 @@ class UserTrackerImplTest : SysuiTestCase() {
     }
 
     @Test
-    fun testCallbackRemoved() {
+    fun testCallbackRemoved() = testScope.runTest {
         tracker.initialize(0)
         val newID = 5
         val profileID = newID + 10
@@ -364,6 +446,7 @@ class UserTrackerImplTest : SysuiTestCase() {
         val captor = ArgumentCaptor.forClass(IUserSwitchObserver::class.java)
         verify(iActivityManager).registerUserSwitchObserver(capture(captor), anyString())
         captor.value.onUserSwitching(newID, userSwitchingReply)
+        runCurrent()
         verify(userSwitchingReply).sendResult(any())
         captor.value.onUserSwitchComplete(newID)
 
diff --git a/packages/SystemUI/tests/utils/src/com/android/systemui/settings/FakeUserTracker.kt b/packages/SystemUI/tests/utils/src/com/android/systemui/settings/FakeUserTracker.kt
index 4242c1635468..f5f924dfce4b 100644
--- a/packages/SystemUI/tests/utils/src/com/android/systemui/settings/FakeUserTracker.kt
+++ b/packages/SystemUI/tests/utils/src/com/android/systemui/settings/FakeUserTracker.kt
@@ -22,7 +22,6 @@ import android.content.pm.UserInfo
 import android.os.UserHandle
 import android.test.mock.MockContentResolver
 import com.android.systemui.util.mockito.mock
-import java.util.concurrent.CountDownLatch
 import java.util.concurrent.Executor
 
 /** A fake [UserTracker] to be used in tests. */
@@ -73,8 +72,7 @@ class FakeUserTracker(
 
     fun onUserChanging(userId: Int = _userId) {
         val copy = callbacks.toList()
-        val latch = CountDownLatch(copy.size)
-        copy.forEach { it.onUserChanging(userId, userContext, latch) }
+        copy.forEach { it.onUserChanging(userId, userContext) {} }
     }
 
     fun onUserChanged(userId: Int = _userId) {