Merge branch '1800-db-view-model' into 'master'

Introduce DbViewModel as replacement of DbController

See merge request briar/briar!1326

briar-android/src/main/java/org/briarproject/briar/android/activity/BriarActivity.java

@@ -129,10 +129,6 @@ public abstract class BriarActivity extends BaseActivity {
 		lockManager.onActivityStop();
 	}
 
-	protected boolean signedIn() {
-		return briarController.accountSignedIn();
-	}
-
 	/**
 	 * Sets the transition animations.
 	 *

briar-android/src/main/java/org/briarproject/briar/android/contact/add/remote/AddContactViewModel.java

@@ -9,7 +9,9 @@ import org.briarproject.bramble.api.contact.PendingContact;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.NoSuchPendingContactException;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.briar.android.viewmodel.DbViewModel;
 import org.briarproject.briar.android.viewmodel.LiveEvent;
 import org.briarproject.briar.android.viewmodel.LiveResult;
 import org.briarproject.briar.android.viewmodel.MutableLiveEvent;
@@ -21,7 +23,6 @@ import java.util.logging.Logger;
 import javax.inject.Inject;
 
 import androidx.annotation.Nullable;
-import androidx.lifecycle.AndroidViewModel;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 
@@ -31,14 +32,12 @@ import static org.briarproject.bramble.api.contact.HandshakeLinkConstants.LINK_R
 import static org.briarproject.bramble.util.LogUtils.logException;
 
 @NotNullByDefault
-public class AddContactViewModel extends AndroidViewModel {
+public class AddContactViewModel extends DbViewModel {
 
 	private final static Logger LOG =
 			getLogger(AddContactViewModel.class.getName());
 
 	private final ContactManager contactManager;
-	@DatabaseExecutor
-	private final Executor dbExecutor;
 
 	private final MutableLiveData<String> handshakeLink =
 			new MutableLiveData<>();
@@ -52,10 +51,10 @@ public class AddContactViewModel extends AndroidViewModel {
 	@Inject
 	AddContactViewModel(Application application,
 			ContactManager contactManager,
-			@DatabaseExecutor Executor dbExecutor) {
-		super(application);
+			@DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager) {
+		super(application, dbExecutor, lifecycleManager);
 		this.contactManager = contactManager;
-		this.dbExecutor = dbExecutor;
 	}
 
 	void onCreate() {
@@ -63,7 +62,7 @@ public class AddContactViewModel extends AndroidViewModel {
 	}
 
 	private void loadHandshakeLink() {
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				handshakeLink.postValue(contactManager.getHandshakeLink());
 			} catch (DbException e) {
@@ -102,7 +101,7 @@ public class AddContactViewModel extends AndroidViewModel {
 
 	void addContact(String nickname) {
 		if (remoteHandshakeLink == null) throw new IllegalStateException();
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				contactManager.addPendingContact(remoteHandshakeLink, nickname);
 				addContactResult.postValue(new LiveResult<>(true));
@@ -122,11 +121,11 @@ public class AddContactViewModel extends AndroidViewModel {
 	}
 
 	public void updatePendingContact(String name, PendingContact p) {
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				contactManager.removePendingContact(p.getId());
 				addContact(name);
-			} catch(NoSuchPendingContactException e) {
+			} catch (NoSuchPendingContactException e) {
 				logException(LOG, WARNING, e);
 				// no error in UI as pending contact was converted into contact
 			} catch (DbException e) {

briar-android/src/main/java/org/briarproject/briar/android/contact/add/remote/PendingContactListViewModel.java

@@ -14,9 +14,11 @@ import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.event.EventListener;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.rendezvous.RendezvousPoller;
 import org.briarproject.bramble.api.rendezvous.event.RendezvousPollEvent;
+import org.briarproject.briar.android.viewmodel.DbViewModel;
 
 import java.util.ArrayList;
 import java.util.Collection;
@@ -26,7 +28,6 @@ import java.util.logging.Logger;
 
 import javax.inject.Inject;
 
-import androidx.lifecycle.AndroidViewModel;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 
@@ -36,14 +37,12 @@ import static org.briarproject.bramble.api.contact.PendingContactState.OFFLINE;
 import static org.briarproject.bramble.util.LogUtils.logException;
 
 @NotNullByDefault
-public class PendingContactListViewModel extends AndroidViewModel
+public class PendingContactListViewModel extends DbViewModel
 		implements EventListener {
 
 	private final Logger LOG =
 			getLogger(PendingContactListViewModel.class.getName());
 
-	@DatabaseExecutor
-	private final Executor dbExecutor;
 	private final ContactManager contactManager;
 	private final RendezvousPoller rendezvousPoller;
 	private final EventBus eventBus;
@@ -56,11 +55,11 @@ public class PendingContactListViewModel extends AndroidViewModel
 	@Inject
 	PendingContactListViewModel(Application application,
 			@DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager,
 			ContactManager contactManager,
 			RendezvousPoller rendezvousPoller,
 			EventBus eventBus) {
-		super(application);
-		this.dbExecutor = dbExecutor;
+		super(application, dbExecutor, lifecycleManager);
 		this.contactManager = contactManager;
 		this.rendezvousPoller = rendezvousPoller;
 		this.eventBus = eventBus;
@@ -87,7 +86,7 @@ public class PendingContactListViewModel extends AndroidViewModel
 	}
 
 	private void loadPendingContacts() {
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				Collection<Pair<PendingContact, PendingContactState>> pairs =
 						contactManager.getPendingContacts();
@@ -113,7 +112,7 @@ public class PendingContactListViewModel extends AndroidViewModel
 	}
 
 	void removePendingContact(PendingContactId id) {
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				contactManager.removePendingContact(id);
 			} catch (DbException e) {

briar-android/src/main/java/org/briarproject/briar/android/controller/DbController.java

@@ -2,6 +2,7 @@ package org.briarproject.briar.android.controller;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
+@Deprecated
 @NotNullByDefault
 public interface DbController {
 

briar-android/src/main/java/org/briarproject/briar/android/controller/DbControllerImpl.java

@@ -11,6 +11,7 @@ import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
 
 @Immutable
+@Deprecated
 @NotNullByDefault
 public class DbControllerImpl implements DbController {
 

briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationActivity.java

@@ -98,7 +98,6 @@ import androidx.core.content.ContextCompat;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.Observer;
 import androidx.lifecycle.ViewModelProvider;
-import androidx.lifecycle.ViewModelProviders;
 import androidx.recyclerview.selection.Selection;
 import androidx.recyclerview.selection.SelectionPredicates;
 import androidx.recyclerview.selection.SelectionTracker;
@@ -224,8 +223,9 @@ public class ConversationActivity extends BriarActivity
 		if (id == -1) throw new IllegalStateException();
 		contactId = new ContactId(id);
 
-		viewModel = ViewModelProviders.of(this, viewModelFactory)
+		viewModel = new ViewModelProvider(this, viewModelFactory)
 				.get(ConversationViewModel.class);
+		viewModel.setContactId(contactId);
 		attachmentRetriever = viewModel.getAttachmentRetriever();
 
 		setContentView(R.layout.activity_conversation);
@@ -330,16 +330,6 @@ public class ConversationActivity extends BriarActivity
 		list.startPeriodicUpdate();
 	}
 
-	@Override
-	public void onResume() {
-		super.onResume();
-		// Trigger loading of contact data, noop if data was loaded already.
-		//
-		// We can only start loading data *after* we are sure
-		// the user has signed in. After sign-in, onCreate() isn't run again.
-		if (signedIn()) viewModel.setContactId(contactId);
-	}
-
 	@Override
 	public void onStop() {
 		super.onStop();

briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationViewModel.java

@@ -15,6 +15,7 @@ import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.event.EventListener;
 import org.briarproject.bramble.api.identity.AuthorId;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.settings.Settings;
 import org.briarproject.bramble.api.settings.SettingsManager;
@@ -26,6 +27,7 @@ import org.briarproject.briar.android.attachment.AttachmentManager;
 import org.briarproject.briar.android.attachment.AttachmentResult;
 import org.briarproject.briar.android.attachment.AttachmentRetriever;
 import org.briarproject.briar.android.util.UiUtils;
+import org.briarproject.briar.android.viewmodel.DbViewModel;
 import org.briarproject.briar.android.viewmodel.LiveEvent;
 import org.briarproject.briar.android.viewmodel.MutableLiveEvent;
 import org.briarproject.briar.api.messaging.AttachmentHeader;
@@ -44,7 +46,6 @@ import javax.inject.Inject;
 
 import androidx.annotation.Nullable;
 import androidx.annotation.UiThread;
-import androidx.lifecycle.AndroidViewModel;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 import androidx.lifecycle.Transformations;
@@ -59,10 +60,10 @@ import static org.briarproject.briar.android.settings.SettingsFragment.SETTINGS_
 import static org.briarproject.briar.android.util.UiUtils.observeForeverOnce;
 
 @NotNullByDefault
-public class ConversationViewModel extends AndroidViewModel
+public class ConversationViewModel extends DbViewModel
 		implements EventListener, AttachmentManager {
 
-	private static Logger LOG =
+	private static final Logger LOG =
 			getLogger(ConversationViewModel.class.getName());
 
 	private static final String SHOW_ONBOARDING_IMAGE =
@@ -70,8 +71,6 @@ public class ConversationViewModel extends AndroidViewModel
 	private static final String SHOW_ONBOARDING_INTRODUCTION =
 			"showOnboardingIntroduction";
 
-	@DatabaseExecutor
-	private final Executor dbExecutor;
 	private final TransactionManager db;
 	private final EventBus eventBus;
 	private final MessagingManager messagingManager;
@@ -105,6 +104,7 @@ public class ConversationViewModel extends AndroidViewModel
 	@Inject
 	ConversationViewModel(Application application,
 			@DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager,
 			TransactionManager db,
 			EventBus eventBus,
 			MessagingManager messagingManager,
@@ -113,8 +113,7 @@ public class ConversationViewModel extends AndroidViewModel
 			PrivateMessageFactory privateMessageFactory,
 			AttachmentRetriever attachmentRetriever,
 			AttachmentCreator attachmentCreator) {
-		super(application);
-		this.dbExecutor = dbExecutor;
+		super(application, dbExecutor, lifecycleManager);
 		this.db = db;
 		this.eventBus = eventBus;
 		this.messagingManager = messagingManager;
@@ -143,7 +142,7 @@ public class ConversationViewModel extends AndroidViewModel
 			AttachmentReceivedEvent a = (AttachmentReceivedEvent) e;
 			if (a.getContactId().equals(contactId)) {
 				LOG.info("Attachment received");
-				dbExecutor.execute(() -> attachmentRetriever
+				runOnDbThread(() -> attachmentRetriever
 						.loadAttachmentItem(a.getMessageId()));
 			}
 		}
@@ -163,7 +162,7 @@ public class ConversationViewModel extends AndroidViewModel
 	}
 
 	private void loadContact(ContactId contactId) {
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				long start = now();
 				Contact c = contactManager.getContact(contactId);
@@ -181,7 +180,7 @@ public class ConversationViewModel extends AndroidViewModel
 	}
 
 	void markMessageRead(GroupId g, MessageId m) {
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				long start = now();
 				messagingManager.setReadFlag(g, m, true);
@@ -193,7 +192,7 @@ public class ConversationViewModel extends AndroidViewModel
 	}
 
 	void setContactAlias(String alias) {
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				contactManager.setContactAlias(requireNonNull(contactId),
 						alias.isEmpty() ? null : alias);
@@ -296,7 +295,7 @@ public class ConversationViewModel extends AndroidViewModel
 	@UiThread
 	private void storeMessage(PrivateMessage m) {
 		attachmentCreator.onAttachmentsSent(m.getMessage().getId());
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				long start = now();
 				messagingManager.addLocalMessage(m);
@@ -356,7 +355,7 @@ public class ConversationViewModel extends AndroidViewModel
 
 	@UiThread
 	void recheckFeaturesAndOnboarding(ContactId contactId) {
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				checkFeaturesAndOnboarding(contactId);
 			} catch (DbException e) {

briar-android/src/main/java/org/briarproject/briar/android/conversation/ImageViewModel.java

@@ -11,9 +11,11 @@ import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.event.EventListener;
 import org.briarproject.bramble.api.lifecycle.IoExecutor;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.android.attachment.AttachmentItem;
+import org.briarproject.briar.android.viewmodel.DbViewModel;
 import org.briarproject.briar.android.viewmodel.LiveEvent;
 import org.briarproject.briar.android.viewmodel.MutableLiveEvent;
 import org.briarproject.briar.api.messaging.Attachment;
@@ -37,7 +39,6 @@ import javax.inject.Inject;
 
 import androidx.annotation.Nullable;
 import androidx.annotation.UiThread;
-import androidx.lifecycle.AndroidViewModel;
 
 import static android.media.MediaScannerConnection.scanFile;
 import static android.os.Environment.DIRECTORY_PICTURES;
@@ -49,20 +50,18 @@ import static org.briarproject.bramble.util.IoUtils.copyAndClose;
 import static org.briarproject.bramble.util.LogUtils.logException;
 
 @NotNullByDefault
-public class ImageViewModel extends AndroidViewModel implements EventListener {
+public class ImageViewModel extends DbViewModel implements EventListener {
 
-	private static Logger LOG = getLogger(ImageViewModel.class.getName());
+	private static final Logger LOG = getLogger(ImageViewModel.class.getName());
 
 	private final MessagingManager messagingManager;
 	private final EventBus eventBus;
-	@DatabaseExecutor
-	private final Executor dbExecutor;
 	@IoExecutor
 	private final Executor ioExecutor;
 
 	private boolean receivedAttachmentsInitialized = false;
-	private HashMap<MessageId, MutableLiveEvent<Boolean>> receivedAttachments =
-			new HashMap<>();
+	private final HashMap<MessageId, MutableLiveEvent<Boolean>>
+			receivedAttachments = new HashMap<>();
 
 	/**
 	 * true means there was an error saving the image, false if image was saved.
@@ -75,13 +74,14 @@ public class ImageViewModel extends AndroidViewModel implements EventListener {
 
 	@Inject
 	ImageViewModel(Application application,
-			MessagingManager messagingManager, EventBus eventBus,
+			MessagingManager messagingManager,
+			EventBus eventBus,
 			@DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager,
 			@IoExecutor Executor ioExecutor) {
-		super(application);
+		super(application, dbExecutor, lifecycleManager);
 		this.messagingManager = messagingManager;
 		this.eventBus = eventBus;
-		this.dbExecutor = dbExecutor;
 		this.ioExecutor = ioExecutor;
 
 		eventBus.addListener(this);
@@ -195,7 +195,7 @@ public class ImageViewModel extends AndroidViewModel implements EventListener {
 
 	private void saveImage(AttachmentItem attachment, OutputStreamProvider osp,
 			@Nullable Runnable afterCopy) {
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				Attachment a =
 						messagingManager.getAttachment(attachment.getHeader());

briar-android/src/main/java/org/briarproject/briar/android/navdrawer/NavDrawerViewModel.java

@@ -4,9 +4,11 @@ import android.app.Application;
 
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.settings.Settings;
 import org.briarproject.bramble.api.settings.SettingsManager;
+import org.briarproject.briar.android.viewmodel.DbViewModel;
 
 import java.util.concurrent.Executor;
 import java.util.logging.Logger;
@@ -14,7 +16,6 @@ import java.util.logging.Logger;
 import javax.inject.Inject;
 
 import androidx.annotation.UiThread;
-import androidx.lifecycle.AndroidViewModel;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 
@@ -28,7 +29,7 @@ import static org.briarproject.briar.android.settings.SettingsFragment.SETTINGS_
 import static org.briarproject.briar.android.util.UiUtils.needsDozeWhitelisting;
 
 @NotNullByDefault
-public class NavDrawerViewModel extends AndroidViewModel {
+public class NavDrawerViewModel extends DbViewModel {
 
 	private static final Logger LOG =
 			getLogger(NavDrawerViewModel.class.getName());
@@ -37,8 +38,6 @@ public class NavDrawerViewModel extends AndroidViewModel {
 	private static final String SHOW_TRANSPORTS_ONBOARDING =
 			"showTransportsOnboarding";
 
-	@DatabaseExecutor
-	private final Executor dbExecutor;
 	private final SettingsManager settingsManager;
 
 	private final MutableLiveData<Boolean> showExpiryWarning =
@@ -49,10 +48,11 @@ public class NavDrawerViewModel extends AndroidViewModel {
 			new MutableLiveData<>();
 
 	@Inject
-	NavDrawerViewModel(Application app, @DatabaseExecutor Executor dbExecutor,
+	NavDrawerViewModel(Application app,
+			@DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager,
 			SettingsManager settingsManager) {
-		super(app);
-		this.dbExecutor = dbExecutor;
+		super(app, dbExecutor, lifecycleManager);
 		this.settingsManager = settingsManager;
 	}
 
@@ -62,7 +62,7 @@ public class NavDrawerViewModel extends AndroidViewModel {
 
 	@UiThread
 	void checkExpiryWarning() {
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				Settings settings =
 						settingsManager.getSettings(SETTINGS_NAMESPACE);
@@ -97,7 +97,7 @@ public class NavDrawerViewModel extends AndroidViewModel {
 	@UiThread
 	void expiryWarningDismissed() {
 		showExpiryWarning.setValue(false);
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				Settings settings = new Settings();
 				int date = (int) (System.currentTimeMillis() / 1000L);
@@ -120,7 +120,7 @@ public class NavDrawerViewModel extends AndroidViewModel {
 			shouldAskForDozeWhitelisting.setValue(false);
 			return;
 		}
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				Settings settings =
 						settingsManager.getSettings(SETTINGS_NAMESPACE);
@@ -141,7 +141,7 @@ public class NavDrawerViewModel extends AndroidViewModel {
 	@UiThread
 	void checkTransportsOnboarding() {
 		if (showTransportsOnboarding.getValue() != null) return;
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				Settings settings =
 						settingsManager.getSettings(SETTINGS_NAMESPACE);
@@ -157,7 +157,7 @@ public class NavDrawerViewModel extends AndroidViewModel {
 	@UiThread
 	void transportsOnboardingShown() {
 		showTransportsOnboarding.setValue(false);
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				Settings settings = new Settings();
 				settings.putBoolean(SHOW_TRANSPORTS_ONBOARDING, false);

briar-android/src/main/java/org/briarproject/briar/android/navdrawer/PluginViewModel.java

@@ -12,6 +12,7 @@ import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.event.EventListener;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.network.NetworkManager;
 import org.briarproject.bramble.api.network.NetworkStatus;
 import org.briarproject.bramble.api.network.event.NetworkStatusEvent;
@@ -27,6 +28,7 @@ import org.briarproject.bramble.api.plugin.event.TransportStateEvent;
 import org.briarproject.bramble.api.settings.Settings;
 import org.briarproject.bramble.api.settings.SettingsManager;
 import org.briarproject.bramble.api.settings.event.SettingsUpdatedEvent;
+import org.briarproject.briar.android.viewmodel.DbViewModel;
 
 import java.util.concurrent.Executor;
 import java.util.logging.Logger;
@@ -34,7 +36,6 @@ import java.util.logging.Logger;
 import javax.inject.Inject;
 
 import androidx.annotation.Nullable;
-import androidx.lifecycle.AndroidViewModel;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 
@@ -51,13 +52,12 @@ import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.LogUtils.now;
 
 @NotNullByDefault
-public class PluginViewModel extends AndroidViewModel implements EventListener {
+public class PluginViewModel extends DbViewModel implements EventListener {
 
 	private static final Logger LOG =
 			getLogger(PluginViewModel.class.getName());
 
 	private final Application app;
-	private final Executor dbExecutor;
 	private final SettingsManager settingsManager;
 	private final PluginManager pluginManager;
 	private final EventBus eventBus;
@@ -85,11 +85,11 @@ public class PluginViewModel extends AndroidViewModel implements EventListener {
 
 	@Inject
 	PluginViewModel(Application app, @DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager,
 			SettingsManager settingsManager, PluginManager pluginManager,
 			EventBus eventBus, NetworkManager networkManager) {
-		super(app);
+		super(app, dbExecutor, lifecycleManager);
 		this.app = app;
-		this.dbExecutor = dbExecutor;
 		this.settingsManager = settingsManager;
 		this.pluginManager = pluginManager;
 		this.eventBus = eventBus;
@@ -182,7 +182,7 @@ public class PluginViewModel extends AndroidViewModel implements EventListener {
 	}
 
 	private void loadSettings() {
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				boolean tor = isPluginEnabled(TorConstants.ID,
 						TorConstants.DEFAULT_PREF_PLUGIN_ENABLE);
@@ -219,7 +219,7 @@ public class PluginViewModel extends AndroidViewModel implements EventListener {
 	}
 
 	private void mergeSettings(Settings s, String namespace) {
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				long start = now();
 				settingsManager.mergeSettings(s, namespace);
@@ -235,8 +235,7 @@ public class PluginViewModel extends AndroidViewModel implements EventListener {
 		@Override
 		public void onReceive(Context context, Intent intent) {
 			int state = intent.getIntExtra(EXTRA_STATE, 0);
-			if (state == STATE_ON) bluetoothTurnedOn.postValue(true);
-			else bluetoothTurnedOn.postValue(false);
+			bluetoothTurnedOn.postValue(state == STATE_ON);
 		}
 	}
 }

briar-android/src/main/java/org/briarproject/briar/android/viewmodel/DbViewModel.java

@@ -0,0 +1,50 @@
+package org.briarproject.briar.android.viewmodel;
+
+import android.app.Application;
+
+import org.briarproject.bramble.api.db.DatabaseExecutor;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.annotation.concurrent.Immutable;
+
+import androidx.annotation.NonNull;
+import androidx.lifecycle.AndroidViewModel;
+
+import static java.util.logging.Logger.getLogger;
+
+@Immutable
+@NotNullByDefault
+public abstract class DbViewModel extends AndroidViewModel {
+
+	private static final Logger LOG = getLogger(DbViewModel.class.getName());
+
+	@DatabaseExecutor
+	private final Executor dbExecutor;
+	private final LifecycleManager lifecycleManager;
+
+	public DbViewModel(
+			@NonNull Application application,
+			@DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager) {
+		super(application);
+		this.dbExecutor = dbExecutor;
+		this.lifecycleManager = lifecycleManager;
+	}
+
+	public void runOnDbThread(Runnable task) {
+		dbExecutor.execute(() -> {
+			try {
+				lifecycleManager.waitForDatabase();
+				task.run();
+			} catch (InterruptedException e) {
+				LOG.warning("Interrupted while waiting for database");
+				Thread.currentThread().interrupt();
+			}
+		});
+	}
+
+}