Refactoring

Use foreground IntentService for DB loading and update.
Add EventBus.
Some other changes.

app/build.gradle

@@ -8,6 +8,12 @@ android {
         targetSdkVersion 28
         versionCode 3040
         versionName "0.3.4"
+
+        javaCompileOptions {
+            annotationProcessorOptions {
+                arguments = [eventBusIndex: 'dummydomain.yetanothercallblocker.EventBusIndex']
+            }
+        }
     }
     buildTypes {
         release {
@@ -25,6 +31,8 @@ android {
 }
 
 dependencies {
+    def eventbus_version = '3.2.0'
+
     implementation 'org.slf4j:slf4j-api:1.7.30'
     implementation 'com.github.tony19:logback-android:2.0.0'
     //noinspection GradleDependency: 3.12.* is the latest version compatible with Android <5
@@ -35,4 +43,6 @@ dependencies {
     implementation 'androidx.recyclerview:recyclerview:1.1.0'
     implementation 'com.google.android.material:material:1.1.0'
     implementation 'androidx.work:work-runtime:2.3.4'
+    implementation "org.greenrobot:eventbus:$eventbus_version"
+    annotationProcessor "org.greenrobot:eventbus-annotation-processor:$eventbus_version"
 }

app/proguard-rules.pro

@@ -19,3 +19,14 @@
 # If you keep the line number information, uncomment this to
 # hide the original source file name.
 #-renamesourcefileattribute SourceFile
+
+-keepattributes *Annotation*
+-keepclassmembers class * {
+    @org.greenrobot.eventbus.Subscribe <methods>;
+}
+-keep enum org.greenrobot.eventbus.ThreadMode { *; }
+
+# And if you use AsyncExecutor:
+-keepclassmembers class * extends org.greenrobot.eventbus.util.ThrowableFailureEvent {
+    <init>(java.lang.Throwable);
+}

app/src/main/AndroidManifest.xml

@@ -45,6 +45,8 @@
                 <action android:name="android.intent.action.PHONE_STATE" />
             </intent-filter>
         </receiver>
+
+        <service android:name=".work.TaskService" />
     </application>
 
 </manifest>

app/src/main/java/dummydomain/yetanothercallblocker/App.java

@@ -2,6 +2,8 @@ package dummydomain.yetanothercallblocker;
 
 import android.app.Application;
 
+import org.greenrobot.eventbus.EventBus;
+
 public class App extends Application {
 
     private static App instance;
@@ -12,6 +14,14 @@ public class App extends Application {
 
         instance = this;
 
+        EventBus.builder()
+                .throwSubscriberException(BuildConfig.DEBUG)
+                .sendNoSubscriberEvent(false)
+                .addIndex(new EventBusIndex())
+                .installDefaultEventBus();
+
+        EventHandler.create(this);
+
         NotificationHelper.createNotificationChannels(this);
     }
 

app/src/main/java/dummydomain/yetanothercallblocker/DebugActivity.java

@@ -8,10 +8,16 @@ import android.widget.TextView;
 
 import androidx.appcompat.app.AppCompatActivity;
 
+import org.greenrobot.eventbus.EventBus;
+import org.greenrobot.eventbus.Subscribe;
+import org.greenrobot.eventbus.ThreadMode;
+
+import dummydomain.yetanothercallblocker.event.SecondaryDbUpdateFinished;
 import dummydomain.yetanothercallblocker.sia.DatabaseSingleton;
 import dummydomain.yetanothercallblocker.sia.model.NumberCategory;
 import dummydomain.yetanothercallblocker.sia.model.database.CommunityDatabaseItem;
 import dummydomain.yetanothercallblocker.sia.model.database.FeaturedDatabaseItem;
+import dummydomain.yetanothercallblocker.work.TaskService;
 
 public class DebugActivity extends AppCompatActivity {
 
@@ -22,6 +28,26 @@ public class DebugActivity extends AppCompatActivity {
         hideSummary();
     }
 
+    @Override
+    protected void onStart() {
+        super.onStart();
+
+        EventBus.getDefault().register(this);
+    }
+
+    @Override
+    protected void onStop() {
+        EventBus.getDefault().unregister(this);
+
+        super.onStop();
+    }
+
+    @Subscribe(threadMode = ThreadMode.MAIN_ORDERED)
+    public void onSecondaryDbUpdateFinished(SecondaryDbUpdateFinished event) {
+        setResult(getString(R.string.debug_update_result,
+                DatabaseSingleton.getCommunityDatabase().getEffectiveDbVersion()));
+    }
+
     public void onQueryDbButtonClick(View view) {
         setResult("");
         hideSummary();
@@ -90,20 +116,7 @@ public class DebugActivity extends AppCompatActivity {
         setResult("");
         hideSummary();
 
-        new AsyncTask<Void, Void, Void>() {
+        TaskService.start(this, TaskService.TASK_UPDATE_SECONDARY_DB);
-            @Override
-            protected Void doInBackground(Void... voids) {
-                DatabaseSingleton.getCommunityDatabase().updateSecondaryDb();
-
-                return null;
-            }
-
-            @Override
-            protected void onPostExecute(Void aVoid) {
-                setResult(DebugActivity.this.getString(R.string.debug_update_result,
-                        DatabaseSingleton.getCommunityDatabase().getEffectiveDbVersion()));
-            }
-        }.execute();
     }
 
     private String getNumber() {

app/src/main/java/dummydomain/yetanothercallblocker/EventHandler.java

@@ -0,0 +1,36 @@
+package dummydomain.yetanothercallblocker;
+
+import android.content.Context;
+
+import org.greenrobot.eventbus.EventBus;
+import org.greenrobot.eventbus.Subscribe;
+import org.greenrobot.eventbus.SubscriberExceptionEvent;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class EventHandler {
+
+    private static final Logger LOG = LoggerFactory.getLogger(EventHandler.class);
+
+    private static EventHandler instance;
+
+    private Context context;
+
+    public static EventHandler create(Context context) {
+        EventHandler instance = new EventHandler(context);
+
+        EventBus.getDefault().register(instance);
+
+        return EventHandler.instance = instance;
+    }
+
+    private EventHandler(Context context) {
+        this.context = context;
+    }
+
+    @Subscribe
+    public void onSubscriberExceptionEvent(SubscriberExceptionEvent event) {
+        LOG.warn("onSubscriberExceptionEvent()", event.throwable);
+    }
+
+}

app/src/main/java/dummydomain/yetanothercallblocker/MainActivity.java

@@ -16,18 +16,27 @@ import androidx.appcompat.app.AppCompatActivity;
 import androidx.appcompat.widget.SwitchCompat;
 import androidx.recyclerview.widget.RecyclerView;
 
+import org.greenrobot.eventbus.EventBus;
+import org.greenrobot.eventbus.Subscribe;
+import org.greenrobot.eventbus.ThreadMode;
+
 import java.util.ArrayList;
 import java.util.List;
 
+import dummydomain.yetanothercallblocker.event.MainDbDownloadFinishedEvent;
+import dummydomain.yetanothercallblocker.event.MainDbDownloadingEvent;
 import dummydomain.yetanothercallblocker.sia.DatabaseSingleton;
 import dummydomain.yetanothercallblocker.sia.model.NumberInfo;
-import dummydomain.yetanothercallblocker.sia.model.database.DbManager;
+import dummydomain.yetanothercallblocker.work.TaskService;
 
 public class MainActivity extends AppCompatActivity {
 
     private CallLogItemRecyclerViewAdapter callLogAdapter;
     private List<CallLogItem> callLogItems = new ArrayList<>();
 
+    private AsyncTask<Void, Void, Boolean> checkMainDbTask;
+    private AsyncTask<Void, Void, List<CallLogItem>> loadCallLogTask;
+
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
@@ -53,22 +62,6 @@ public class MainActivity extends AppCompatActivity {
             if (isChecked) Updater.scheduleAutoUpdateWorker();
             else Updater.cancelAutoUpdateWorker();
         });
-
-        @SuppressLint("StaticFieldLeak")
-        AsyncTask<Void, Void, Boolean> noDbTask = new AsyncTask<Void, Void, Boolean>() {
-            @Override
-            protected Boolean doInBackground(Void... voids) {
-                return DatabaseSingleton.getCommunityDatabase().isOperational();
-            }
-
-            @Override
-            protected void onPostExecute(Boolean result) {
-                updateNoDbUi(result ? UpdateUiState.HIDDEN : UpdateUiState.NO_DB);
-            }
-        };
-        noDbTask.execute();
-
-        PermissionHelper.checkPermissions(this);
     }
 
     @Override
@@ -91,29 +84,74 @@ public class MainActivity extends AppCompatActivity {
     protected void onStart() {
         super.onStart();
 
+        EventBus.getDefault().register(this);
+
+        startCheckMainDbTask();
+
+        PermissionHelper.checkPermissions(this);
+
         loadCallLog();
     }
 
-    public void onDownloadDbClick(View view) {
+    @Override
-        // TODO: use service
+    protected void onStop() {
+        EventBus.getDefault().unregister(this);
 
-        updateNoDbUi(UpdateUiState.DOWNLOADING_DB);
+        super.onStop();
+    }
 
+    @Override
+    protected void onDestroy() {
+        cancelCheckMainDbTask();
+        cancelLoadingCallLogTask();
+
+        super.onDestroy();
+    }
+
+    @Subscribe(threadMode = ThreadMode.MAIN_ORDERED)
+    public void onMainDbDownloadFinished(MainDbDownloadFinishedEvent event) {
+        loadCallLog();
+    }
+
+    private void startCheckMainDbTask() {
+        cancelCheckMainDbTask();
         @SuppressLint("StaticFieldLeak")
-        AsyncTask<Void, Void, Boolean> dlTask = new AsyncTask<Void, Void, Boolean>() {
+        AsyncTask<Void, Void, Boolean> checkMainDbTask = this.checkMainDbTask
+                = new AsyncTask<Void, Void, Boolean>() {
             @Override
             protected Boolean doInBackground(Void... voids) {
-                return DbManager.downloadMainDb()
+                return DatabaseSingleton.getCommunityDatabase().isOperational();
-                        && DatabaseSingleton.getCommunityDatabase().reload()
-                        && DatabaseSingleton.getFeaturedDatabase().reload();
             }
 
             @Override
             protected void onPostExecute(Boolean result) {
-                updateNoDbUi(result ? UpdateUiState.HIDDEN : UpdateUiState.ERROR);
+                if (!result && EventBus.getDefault().getStickyEvent(MainDbDownloadingEvent.class) == null) {
+                    showNoMainDbDialog();
+                }
             }
         };
-        dlTask.execute();
+        checkMainDbTask.execute();
+    }
+
+    private void cancelCheckMainDbTask() {
+        if (checkMainDbTask != null) {
+            checkMainDbTask.cancel(true);
+            checkMainDbTask = null;
+        }
+    }
+
+    private void showNoMainDbDialog() {
+        new AlertDialog.Builder(this)
+                .setTitle(R.string.no_main_db_title)
+                .setMessage(R.string.no_main_db_text)
+                .setPositiveButton(R.string.download_main_db,
+                        (d, w) -> downloadMainDb())
+                .setNegativeButton(R.string.no, null)
+                .show();
+    }
+
+    public void downloadMainDb() {
+        TaskService.start(this, TaskService.TASK_DOWNLOAD_MAIN_DB);
     }
 
     public void onOpenDebugActivity(MenuItem item) {
@@ -147,24 +185,16 @@ public class MainActivity extends AppCompatActivity {
         builder.show();
     }
 
-    enum UpdateUiState {HIDDEN, NO_DB, DOWNLOADING_DB, ERROR}
-
-    private void updateNoDbUi(UpdateUiState state) {
-        findViewById(R.id.noDbText).setVisibility(state == UpdateUiState.NO_DB ? View.VISIBLE : View.GONE);
-        findViewById(R.id.downloadDbButton).setVisibility(state == UpdateUiState.NO_DB ? View.VISIBLE : View.GONE);
-
-        findViewById(R.id.downloadingDbText).setVisibility(state == UpdateUiState.DOWNLOADING_DB ? View.VISIBLE : View.GONE);
-
-        findViewById(R.id.dbCouldNotBeDownloaded).setVisibility(state == UpdateUiState.ERROR ? View.VISIBLE : View.GONE);
-    }
-
     private void loadCallLog() {
         if (!PermissionHelper.havePermission(this, Manifest.permission.READ_CALL_LOG)) {
             setCallLogVisibility(false);
             return;
         }
 
-        new AsyncTask<Void, Void, List<CallLogItem>>() {
+        cancelLoadingCallLogTask();
+        @SuppressLint("StaticFieldLeak")
+        AsyncTask<Void, Void, List<CallLogItem>> loadCallLogTask = this.loadCallLogTask
+                = new AsyncTask<Void, Void, List<CallLogItem>>() {
             @Override
             protected List<CallLogItem> doInBackground(Void... voids) {
                 List<CallLogItem> items = CallLogHelper.getRecentCalls(MainActivity.this, 10);
@@ -186,7 +216,15 @@ public class MainActivity extends AppCompatActivity {
 
                 setCallLogVisibility(true);
             }
-        }.execute();
+        };
+        loadCallLogTask.execute();
+    }
+
+    private void cancelLoadingCallLogTask() {
+        if (loadCallLogTask != null) {
+            loadCallLogTask.cancel(true);
+            loadCallLogTask = null;
+        }
     }
 
     private void setCallLogVisibility(boolean visible) {

app/src/main/java/dummydomain/yetanothercallblocker/NotificationHelper.java

@@ -8,6 +8,7 @@ import android.app.PendingIntent;
 import android.content.Context;
 import android.content.Intent;
 import android.os.Build;
+
 import androidx.annotation.ColorInt;
 import androidx.annotation.DrawableRes;
 import androidx.core.app.NotificationCompat;
@@ -26,15 +27,19 @@ public class NotificationHelper {
     private static final String NOTIFICATION_TAG_BLOCKED_CALL = "blockedCallNotification";
     private static final int NOTIFICATION_ID_INCOMING_CALL = 1;
     private static final int NOTIFICATION_ID_BLOCKED_CALL = 2;
+    public static final int NOTIFICATION_ID_TASKS = 3;
 
     private static final String CHANNEL_GROUP_ID_INCOMING_CALLS = "incoming_calls";
     private static final String CHANNEL_GROUP_ID_BLOCKED_CALLS = "blocked_calls";
+    private static final String CHANNEL_GROUP_ID_TASKS = "tasks";
+
     private static final String CHANNEL_ID_POSITIVE_KNOWN = "positive_known_calls";
     private static final String CHANNEL_ID_POSITIVE = "positive_calls";
     private static final String CHANNEL_ID_NEUTRAL = "neutral_calls";
     private static final String CHANNEL_ID_UNKNOWN = "unknown_calls";
     private static final String CHANNEL_ID_NEGATIVE = "negative_calls";
     private static final String CHANNEL_ID_BLOCKED_INFO = "blocked_info";
+    public static final String CHANNEL_ID_TASKS = "tasks";
 
     public static void showIncomingCallNotification(Context context, NumberInfo numberInfo) {
         Notification notification = createIncomingCallNotification(context, numberInfo);
@@ -171,6 +176,11 @@ public class NotificationHelper {
                     context.getString(R.string.notification_channel_group_name_blocked_calls));
             notificationManager.createNotificationChannelGroup(channelGroupBlocked);
 
+            NotificationChannelGroup channelGroupTasks = new NotificationChannelGroup(
+                    CHANNEL_GROUP_ID_TASKS,
+                    context.getString(R.string.notification_channel_group_name_tasks));
+            notificationManager.createNotificationChannelGroup(channelGroupTasks);
+
             List<NotificationChannel> channels = new ArrayList<>();
 
             NotificationChannel channel;
@@ -217,6 +227,13 @@ public class NotificationHelper {
             channel.setGroup(channelGroupBlocked.getId());
             channels.add(channel);
 
+            channel = new NotificationChannel(
+                    CHANNEL_ID_TASKS, context.getString(R.string.notification_channel_name_tasks),
+                    NotificationManager.IMPORTANCE_LOW
+            );
+            channel.setGroup(channelGroupTasks.getId());
+            channels.add(channel);
+
             notificationManager.createNotificationChannels(channels);
         }
     }

app/src/main/java/dummydomain/yetanothercallblocker/ReviewsActivity.java

@@ -1,16 +1,18 @@
 package dummydomain.yetanothercallblocker;
 
+import android.annotation.SuppressLint;
 import android.content.Context;
 import android.content.Intent;
 import android.os.AsyncTask;
 import android.os.Bundle;
+import android.text.TextUtils;
+import android.view.View;
+import android.widget.TextView;
+
 import androidx.appcompat.app.AppCompatActivity;
 import androidx.recyclerview.widget.DividerItemDecoration;
 import androidx.recyclerview.widget.LinearLayoutManager;
 import androidx.recyclerview.widget.RecyclerView;
-import android.text.TextUtils;
-import android.view.View;
-import android.widget.TextView;
 
 import java.util.List;
 
@@ -22,7 +24,8 @@ public class ReviewsActivity extends AppCompatActivity {
     private static final String PARAM_NUMBER = "param_number";
 
     private CustomListViewAdapter listViewAdapter;
-    private RecyclerView reviewsList;
+
+    private AsyncTask<Void, Void, List<CommunityReview>> loadReviewsTask;
 
     public static Intent getNumberIntent(Context context, String number) {
         Intent intent = new Intent(context, ReviewsActivity.class);
@@ -47,12 +50,14 @@ public class ReviewsActivity extends AppCompatActivity {
         setText(getString(R.string.reviews_loading));
 
         listViewAdapter = new CustomListViewAdapter();
-        reviewsList = findViewById(R.id.reviews_list);
+        RecyclerView reviewsList = findViewById(R.id.reviews_list);
         reviewsList.setLayoutManager(new LinearLayoutManager(this));
         reviewsList.setAdapter(listViewAdapter);
         reviewsList.addItemDecoration(new DividerItemDecoration(this, DividerItemDecoration.VERTICAL));
 
-        new AsyncTask<Void, Void, List<CommunityReview>>() {
+        @SuppressLint("StaticFieldLeak")
+        AsyncTask<Void, Void, List<CommunityReview>> asyncTask = loadReviewsTask
+                = new AsyncTask<Void, Void, List<CommunityReview>>() {
             @Override
             protected List<CommunityReview> doInBackground(Void... voids) {
                 return CommunityReviewsLoader.loadReviews(paramNumber);
@@ -63,7 +68,22 @@ public class ReviewsActivity extends AppCompatActivity {
                 setText("");
                 handleReviews(reviews);
             }
-        }.execute();
+        };
+        asyncTask.execute();
+    }
+
+    @Override
+    protected void onDestroy() {
+        cancelReviewsLoadingTask();
+
+        super.onDestroy();
+    }
+
+    private void cancelReviewsLoadingTask() {
+        if (loadReviewsTask != null) {
+            loadReviewsTask.cancel(true);
+            loadReviewsTask = null;
+        }
     }
 
     private void setText(String text) {

app/src/main/java/dummydomain/yetanothercallblocker/UpdateWorker.java

@@ -1,13 +1,17 @@
 package dummydomain.yetanothercallblocker;
 
 import android.content.Context;
-import androidx.annotation.NonNull;
 
+import androidx.annotation.NonNull;
+import androidx.work.Worker;
+import androidx.work.WorkerParameters;
+
+import org.greenrobot.eventbus.EventBus;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import androidx.work.Worker;
+import dummydomain.yetanothercallblocker.event.SecondaryDbUpdateFinished;
-import androidx.work.WorkerParameters;
+import dummydomain.yetanothercallblocker.event.SecondaryDbUpdatingEvent;
 import dummydomain.yetanothercallblocker.sia.DatabaseSingleton;
 
 public class UpdateWorker extends Worker {
@@ -23,7 +27,18 @@ public class UpdateWorker extends Worker {
     public Result doWork() {
         LOG.info("doWork() started");
 
+        EventBus bus = EventBus.getDefault();
+
+        SecondaryDbUpdatingEvent sticky = new SecondaryDbUpdatingEvent();
+
+        bus.postSticky(sticky);
+        try {
             DatabaseSingleton.getCommunityDatabase().updateSecondaryDb();
+        } finally {
+            bus.removeStickyEvent(sticky);
+        }
+
+        bus.post(new SecondaryDbUpdateFinished());
 
         LOG.info("doWork() finished");
         return Result.success();

app/src/main/java/dummydomain/yetanothercallblocker/event/MainDbDownloadFinishedEvent.java

@@ -0,0 +1,3 @@
+package dummydomain.yetanothercallblocker.event;
+
+public class MainDbDownloadFinishedEvent {}

app/src/main/java/dummydomain/yetanothercallblocker/event/MainDbDownloadingEvent.java

@@ -0,0 +1,3 @@
+package dummydomain.yetanothercallblocker.event;
+
+public class MainDbDownloadingEvent {}

app/src/main/java/dummydomain/yetanothercallblocker/event/SecondaryDbUpdateFinished.java

@@ -0,0 +1,3 @@
+package dummydomain.yetanothercallblocker.event;
+
+public class SecondaryDbUpdateFinished {}

app/src/main/java/dummydomain/yetanothercallblocker/event/SecondaryDbUpdatingEvent.java

@@ -0,0 +1,3 @@
+package dummydomain.yetanothercallblocker.event;
+
+public class SecondaryDbUpdatingEvent {}

app/src/main/java/dummydomain/yetanothercallblocker/sia/model/database/DbManager.java

@@ -33,9 +33,20 @@ public class DbManager {
 
         if (DbDownloader.download(url, FileUtils.getDataDirPath() + tmpUpdateDir)) {
             LOG.debug("downloadMainDb() downloaded and unpacked");
-            new File(dataDir, siaDir).renameTo(new File(dataDir, oldDir));
+
-            new File(dataDir, tmpUpdateDir).renameTo(new File(dataDir, siaDir));
+            File old = new File(dataDir, siaDir);
+            if (old.exists() && !old.renameTo(new File(dataDir, oldDir))) {
+                LOG.warn("downloadMainDb() couldn't rename sia to old");
+                return false;
+            }
+
+            if (!new File(dataDir, tmpUpdateDir).renameTo(new File(dataDir, siaDir))) {
+                LOG.warn("downloadMainDb() couldn't rename tmp to sia");
+                return false;
+            }
+
             FileUtils.delete(dataDir, oldDir);
+
             LOG.debug("downloadMainDb() folders moved");
             return true;
         } else {

app/src/main/java/dummydomain/yetanothercallblocker/work/TaskService.java

@@ -0,0 +1,139 @@
+package dummydomain.yetanothercallblocker.work;
+
+import android.app.IntentService;
+import android.app.Notification;
+import android.content.Context;
+import android.content.Intent;
+import android.os.Process;
+import android.text.TextUtils;
+
+import androidx.annotation.Nullable;
+import androidx.core.app.NotificationCompat;
+import androidx.core.app.NotificationManagerCompat;
+import androidx.core.content.ContextCompat;
+
+import org.greenrobot.eventbus.EventBus;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import dummydomain.yetanothercallblocker.NotificationHelper;
+import dummydomain.yetanothercallblocker.R;
+import dummydomain.yetanothercallblocker.event.MainDbDownloadFinishedEvent;
+import dummydomain.yetanothercallblocker.event.MainDbDownloadingEvent;
+import dummydomain.yetanothercallblocker.event.SecondaryDbUpdateFinished;
+import dummydomain.yetanothercallblocker.event.SecondaryDbUpdatingEvent;
+import dummydomain.yetanothercallblocker.sia.DatabaseSingleton;
+import dummydomain.yetanothercallblocker.sia.model.database.DbManager;
+
+public class TaskService extends IntentService {
+
+    public static final String TASK_DOWNLOAD_MAIN_DB = "download_main_db";
+    public static final String TASK_UPDATE_SECONDARY_DB = "update_secondary_db";
+
+    private static final Logger LOG = LoggerFactory.getLogger(TaskService.class);
+
+    public static void start(Context context, String task) {
+        Intent intent = new Intent(context, TaskService.class);
+        intent.setAction(task);
+        ContextCompat.startForegroundService(context, intent);
+    }
+
+    public TaskService() {
+        super(TaskService.class.getSimpleName());
+    }
+
+    @Override
+    protected void onHandleIntent(@Nullable Intent intent) {
+        Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND);
+
+        String action = intent != null ? intent.getAction() : null;
+
+        startForeground(NotificationHelper.NOTIFICATION_ID_TASKS, createNotification(null));
+        try {
+            if (!TextUtils.isEmpty(action)) {
+                switch (action) {
+                    case TASK_DOWNLOAD_MAIN_DB:
+                        updateNotification(getString(R.string.main_db_downloading));
+                        downloadMainDb();
+                        break;
+
+                    case TASK_UPDATE_SECONDARY_DB:
+                        updateNotification(getString(R.string.secondary_db_updating));
+                        updateSecondaryDb();
+                        break;
+
+                    default:
+                        LOG.warn("Unknown action: " + action);
+                        break;
+                }
+            }
+        } finally {
+            stopForeground(true);
+        }
+    }
+
+    private Notification createNotification(String title) {
+        if (title == null) title = getString(R.string.notification_background_operation);
+
+        NotificationCompat.Builder builder = new NotificationCompat.Builder(
+                getApplicationContext(), NotificationHelper.CHANNEL_ID_TASKS)
+                .setSmallIcon(R.drawable.ic_file_download_black_24dp);
+
+        builder.setContentTitle(title);
+
+        return builder.build();
+    }
+
+    private void updateNotification(String title) {
+        NotificationManagerCompat notificationManager = NotificationManagerCompat
+                .from(getApplicationContext());
+
+        notificationManager.notify(NotificationHelper.NOTIFICATION_ID_TASKS,
+                createNotification(title));
+    }
+
+    private void downloadMainDb() {
+        MainDbDownloadingEvent sticky = new MainDbDownloadingEvent();
+
+        postSticky(sticky);
+        try {
+            DbManager.downloadMainDb();
+            DatabaseSingleton.getCommunityDatabase().reload();
+            DatabaseSingleton.getFeaturedDatabase().reload();
+        } finally {
+            removeSticky(sticky);
+        }
+
+        post(new MainDbDownloadFinishedEvent());
+    }
+
+    private void updateSecondaryDb() {
+        SecondaryDbUpdatingEvent sticky = new SecondaryDbUpdatingEvent();
+
+        postSticky(sticky);
+        try {
+            DatabaseSingleton.getCommunityDatabase().updateSecondaryDb();
+        } finally {
+            removeSticky(sticky);
+        }
+
+        post(new SecondaryDbUpdateFinished());
+    }
+
+    private void post(Object event) {
+        bus().post(event);
+    }
+
+    private void postSticky(Object event) {
+        bus().postSticky(event);
+    }
+
+    private void removeSticky(Object event) {
+        bus().removeStickyEvent(event);
+    }
+
+    private EventBus bus() {
+        return EventBus.getDefault();
+    }
+
+}

app/src/main/res/drawable/ic_file_download_black_24dp.xml

@@ -0,0 +1,9 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24.0"
+    android:viewportHeight="24.0">
+    <path
+        android:fillColor="#FF000000"
+        android:pathData="M19,9h-4V3H9v6H5l7,7 7,-7zM5,18v2h14v-2H5z" />
+</vector>

app/src/main/res/layout/activity_main.xml

@@ -26,54 +26,6 @@
         android:paddingRight="@dimen/item_padding"
         android:showDividers="middle">
 
-        <TextView
-            android:id="@+id/noDbText"
-            android:layout_width="wrap_content"
-            android:layout_height="wrap_content"
-            android:layout_gravity="start"
-            android:layout_marginStart="@dimen/text_margin"
-            android:layout_marginLeft="@dimen/text_margin"
-            android:paddingTop="@dimen/item_padding"
-            android:text="@string/no_main_db"
-            android:textAlignment="textStart"
-            android:textColor="@color/rateNegative"
-            android:visibility="gone" />
-
-        <androidx.appcompat.widget.AppCompatButton
-            android:id="@+id/downloadDbButton"
-            android:layout_width="match_parent"
-            android:layout_height="wrap_content"
-            android:layout_marginTop="@dimen/text_margin"
-            android:layout_marginBottom="@dimen/text_margin"
-            android:onClick="onDownloadDbClick"
-            android:text="@string/download_main_db"
-            android:visibility="gone" />
-
-        <TextView
-            android:id="@+id/downloadingDbText"
-            android:layout_width="wrap_content"
-            android:layout_height="wrap_content"
-            android:layout_gravity="start"
-            android:layout_marginStart="@dimen/text_margin"
-            android:layout_marginLeft="@dimen/text_margin"
-            android:paddingTop="@dimen/item_padding"
-            android:text="@string/downloading_db"
-            android:textAlignment="textStart"
-            android:visibility="gone" />
-
-        <TextView
-            android:id="@+id/dbCouldNotBeDownloaded"
-            android:layout_width="wrap_content"
-            android:layout_height="wrap_content"
-            android:layout_gravity="start"
-            android:layout_marginStart="@dimen/text_margin"
-            android:layout_marginLeft="@dimen/text_margin"
-            android:paddingTop="@dimen/item_padding"
-            android:text="@string/db_could_not_be_downloaded"
-            android:textAlignment="textStart"
-            android:textColor="@color/rateNegative"
-            android:visibility="gone" />
-
         <androidx.appcompat.widget.SwitchCompat
             android:id="@+id/notificationsEnabledSwitch"
             android:layout_width="match_parent"

app/src/main/res/values/strings.xml

@@ -3,6 +3,7 @@
 
     <string name="notification_channel_group_name_incoming_calls">Incoming calls</string>
     <string name="notification_channel_group_name_blocked_calls">Blocked calls</string>
+    <string name="notification_channel_group_name_tasks">Tasks</string>
 
     <string name="notification_channel_name_positive_known">Known positive calls</string>
     <string name="notification_channel_name_positive">Positive calls</string>
@@ -10,6 +11,7 @@
     <string name="notification_channel_name_unknown">Unknown calls</string>
     <string name="notification_channel_name_negative">Negative calls</string>
     <string name="notification_channel_name_blocked_info">Blocked info</string>
+    <string name="notification_channel_name_tasks">Tasks</string>
 
     <string name="notification_incoming_call_positive">Positive call</string>
     <string name="notification_incoming_call_neutral">Neutral call</string>
@@ -20,6 +22,8 @@
 
     <string name="notification_incoming_call_text_description">Negative: %d, positive: %d, neutral: %d</string>
 
+    <string name="notification_background_operation">Performing background operation…</string>
+
     <string name="sia_category_none">None</string>
     <string name="sia_category_telemarketer">Telemarketer</string>
     <string name="sia_category_dept_collector">Debt collector</string>
@@ -47,18 +51,22 @@
     <string name="reviews_loading">Loading reviews…</string>
 
     <string name="general_settings">General settings</string>
-    <string name="no_main_db">Database is not present! For the app to function offline you need to download DB. Press the button below to do it.</string>
+
-    <string name="downloading_db">Downloading DB…</string>
+    <string name="no_main_db_title">Download main database</string>
-    <string name="db_could_not_be_downloaded">Database couldn\'t be downloaded</string>
+    <string name="no_main_db_text">Database is not present! For the app to perform most of its functions you need to download DB. It will take around 25 MB of traffic.</string>
+    <string name="download_main_db">Download database</string>
+    <string name="main_db_downloading">Downloading DB…</string>
+
+    <string name="secondary_db_updating">Updating DB…</string>
 
     <string name="recent_calls">Recent calls</string>
     <string name="online_reviews">Online reviews</string>
     <string name="back">Back</string>
+    <string name="no">No</string>
 
     <string name="incoming_call_notifications_enabled">Incoming call notifications enabled</string>
     <string name="block_calls">Block unwanted calls</string>
     <string name="auto_update_enabled">Auto-update enabled</string>
-    <string name="download_main_db">Download database</string>
 
     <string name="open_debug_activity">Open debug screen</string>
     <string name="debug_activity_label">Debug</string>