use dataSync service on receiving FCM notifications

jni/dc_wrapper.c

@@ -276,6 +276,12 @@ JNIEXPORT void Java_com_b44t_messenger_DcAccounts_setPushDeviceToken(JNIEnv *env
 }
 
 
+JNIEXPORT jboolean Java_com_b44t_messenger_DcAccounts_backgroundFetch(JNIEnv *env, jobject obj, jint timeout_seconds)
+{
+    return dc_accounts_background_fetch(get_dc_accounts(env, obj), timeout_seconds) != 0;
+}
+
+
 JNIEXPORT jint Java_com_b44t_messenger_DcAccounts_addAccount(JNIEnv *env, jobject obj)
 {
     return dc_accounts_add_account(get_dc_accounts(env, obj));

src/gplay/java/org/thoughtcrime/securesms/notifications/FcmReceiveService.java

@@ -17,7 +17,7 @@
 
 import org.thoughtcrime.securesms.ApplicationContext;
 import org.thoughtcrime.securesms.BuildConfig;
-import org.thoughtcrime.securesms.util.Prefs;
+import org.thoughtcrime.securesms.service.FetchForegroundService;
 import org.thoughtcrime.securesms.util.Util;
 
 public class FcmReceiveService extends FirebaseMessagingService {
@@ -92,12 +92,15 @@ public static String getToken() {
     return prefixedToken;
   }
 
+  @WorkerThread
   @Override
   public void onMessageReceived(@NonNull RemoteMessage remoteMessage) {
     Log.i(TAG, "FCM push notification received");
-    // the app is running (again) now and fetching and notifications should be processed as usual.
-    // to support accounts that do not send PUSH notifications and for simplicity,
-    // we just let the app run as long as possible.
+    FetchForegroundService.start(this);
+    if (!ApplicationContext.dcAccounts.backgroundFetch(19)) { // we should complete within 20 seconds
+      FetchForegroundService.stop(this);
+    }
+    Log.i(TAG, "background fetch done");
   }
 
   @Override

src/main/AndroidManifest.xml

@@ -380,6 +380,10 @@
         android:name=".service.GenericForegroundService"
         android:foregroundServiceType="dataSync" />
 
+    <service
+        android:name=".service.FetchForegroundService"
+        android:foregroundServiceType="dataSync" />
+
     <service
         android:name=".service.IPCAddAccountsService"
         android:foregroundServiceType="dataSync"

src/main/java/com/b44t/messenger/DcAccounts.java

@@ -25,6 +25,7 @@ public void unref() {
     public native void            stopIo               ();
     public native void            maybeNetwork         ();
     public native void            setPushDeviceToken   (String token);
+    public native boolean         backgroundFetch      (int timeoutSeconds);
 
     public native int             addAccount           ();
     public native int             migrateAccount       (String dbfile);

src/main/java/com/b44t/messenger/DcContext.java

@@ -31,6 +31,7 @@ public class DcContext {
     public final static int DC_EVENT_WEBXDC_STATUS_UPDATE        = 2120;
     public final static int DC_EVENT_WEBXDC_INSTANCE_DELETED     = 2121;
     public final static int DC_EVENT_WEBXDC_REALTIME_DATA        = 2150;
+    public final static int DC_EVENT_ACCOUNTS_BACKGROUND_FETCH_DONE = 2200;
 
     public final static int DC_IMEX_EXPORT_SELF_KEYS = 1;
     public final static int DC_IMEX_IMPORT_SELF_KEYS = 2;

src/main/java/org/thoughtcrime/securesms/connect/DcEventCenter.java

@@ -11,6 +11,7 @@
 
 import org.thoughtcrime.securesms.ApplicationContext;
 import org.thoughtcrime.securesms.R;
+import org.thoughtcrime.securesms.service.FetchForegroundService;
 import org.thoughtcrime.securesms.util.Util;
 
 import java.util.ArrayList;
@@ -177,6 +178,10 @@ public long handleEvent(@NonNull DcEvent event) {
         DcHelper.getNotificationCenter(context).removeNotifications(accountId, event.getData1Int());
         break;
 
+      case DcContext.DC_EVENT_ACCOUNTS_BACKGROUND_FETCH_DONE:
+        FetchForegroundService.stop(context);
+        break;
+
       case DcContext.DC_EVENT_IMEX_PROGRESS:
         sendToCurrentAccountObservers(event);
         return 0;

src/main/java/org/thoughtcrime/securesms/notifications/NotificationCenter.java

@@ -168,6 +168,7 @@ private PendingIntent getMarkAsReadIntent(ChatData chatData, int msgId, boolean
     public static final int ID_PERMANENT   = 1;
     public static final int ID_MSG_SUMMARY = 2;
     public static final int ID_GENERIC     = 3;
+    public static final int ID_FETCH       = 4;
     public static final int ID_MSG_OFFSET  = 0; // msgId is added - as msgId start at 10, there are no conflicts with lower numbers
 
 

src/main/java/org/thoughtcrime/securesms/service/FetchForegroundService.java

@@ -0,0 +1,61 @@
+package org.thoughtcrime.securesms.service;
+
+import android.app.Notification;
+import android.app.Service;
+import android.content.Context;
+import android.content.Intent;
+import android.os.IBinder;
+
+import androidx.annotation.Nullable;
+import androidx.core.app.NotificationCompat;
+import androidx.core.content.ContextCompat;
+
+import org.thoughtcrime.securesms.R;
+import org.thoughtcrime.securesms.notifications.NotificationCenter;
+
+public final class FetchForegroundService extends Service {
+  private static final Object SERVICE_LOCK = new Object();
+  private static Intent service;
+
+  public static void start(Context context) {
+    GenericForegroundService.createFgNotificationChannel(context);
+    synchronized (SERVICE_LOCK) {
+      if (service == null) {
+        service = new Intent(context, FetchForegroundService.class);
+        ContextCompat.startForegroundService(context, service);
+      }
+    }
+  }
+
+  public static void stop(Context context) {
+    synchronized (SERVICE_LOCK) {
+      if (service != null) {
+        context.stopService(service);
+        service = null;
+      }
+    }
+  }
+
+  @Override
+  public void onCreate() {
+    super.onCreate();
+
+    Notification notification = new NotificationCompat.Builder(this, NotificationCenter.CH_GENERIC)
+      .setContentTitle(getString(R.string.connectivity_updating))
+      .setSmallIcon(R.drawable.notification_permanent)
+      .build();
+
+    startForeground(NotificationCenter.ID_FETCH, notification);
+  }
+
+  @Override
+  public void onDestroy() {
+    stopForeground(true);
+  }
+
+  @Nullable
+  @Override
+  public IBinder onBind(Intent intent) {
+    return null;
+  }
+}

src/main/java/org/thoughtcrime/securesms/service/GenericForegroundService.java

@@ -185,7 +185,7 @@ synchronized void replaceProgress(int id, int progressMax, int progress, boolean
   }
 
   @TargetApi(Build.VERSION_CODES.O)
-  static private void createFgNotificationChannel(Context context) {
+  static public void createFgNotificationChannel(Context context) {
     if(!CHANNEL_CREATED.get() && Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
       CHANNEL_CREATED.set(true);
       NotificationChannel channel = new NotificationChannel(NotificationCenter.CH_GENERIC,