Prevent duplicate threads

app/src/main/java/eu/faircode/email/DB.java

@@ -60,7 +60,7 @@ import io.requery.android.database.sqlite.SQLiteDatabase;
 // https://developer.android.com/topic/libraries/architecture/room.html
 
 @Database(
-        version = 146,
+        version = 147,
         entities = {
                 EntityIdentity.class,
                 EntityAccount.class,
@@ -1401,6 +1401,13 @@ public abstract class DB extends RoomDatabase {
                         Log.i("DB migration from version " + startVersion + " to " + endVersion);
                         db.execSQL("ALTER TABLE `account` ADD COLUMN `max_messages` INTEGER");
                     }
+                })
+                .addMigrations(new Migration(146, 147) {
+                    @Override
+                    public void migrate(@NonNull SupportSQLiteDatabase db) {
+                        Log.i("DB migration from version " + startVersion + " to " + endVersion);
+                        db.execSQL("ALTER TABLE `account` ADD COLUMN `thread` INTEGER");
+                    }
                 });
     }
 

app/src/main/java/eu/faircode/email/DaoAccount.java

@@ -122,6 +122,12 @@ public interface DaoAccount {
     @Query("UPDATE account SET synchronize = :synchronize WHERE id = :id")
     int setAccountSynchronize(long id, boolean synchronize);
 
+    @Query("UPDATE account SET thread = :thread WHERE id = :id")
+    int setAccountThread(long id, Long thread);
+
+    @Query("SELECT thread FROM account WHERE id = :id")
+    Long getAccountThread(long id);
+
     @Query("UPDATE account SET state = :state WHERE id = :id")
     int setAccountState(long id, String state);
 

app/src/main/java/eu/faircode/email/EntityAccount.java

@@ -129,6 +129,7 @@ public class EntityAccount extends EntityOrder implements Serializable {
 
     public Long created;
     public Boolean tbd;
+    public Long thread;
     public String state;
     public String warning;
     public String error;

app/src/main/java/eu/faircode/email/ServiceSynchronize.java

@@ -790,6 +790,14 @@ public class ServiceSynchronize extends ServiceBase implements SharedPreferences
         try {
             wlAccount.acquire();
 
+            final DB db = DB.getInstance(this);
+            final ExecutorService executor =
+                    Helper.getBackgroundExecutor(1, "account_" + account.id);
+
+            long thread = Thread.currentThread().getId();
+            Long currentThread = thread;
+            db.account().setAccountThread(account.id, thread);
+
             if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
                 if (account.notify)
                     account.createNotificationChannel(ServiceSynchronize.this);
@@ -807,14 +815,11 @@ public class ServiceSynchronize extends ServiceBase implements SharedPreferences
                     Log.w(account.name + " backoff " + ex.toString());
                 }
 
-            final DB db = DB.getInstance(this);
-            final ExecutorService executor =
-                    Helper.getBackgroundExecutor(1, "account_" + account.id);
-
             state.setBackoff(CONNECT_BACKOFF_START);
-            while (state.isRunning()) {
+            while (state.isRunning() &&
+                    currentThread != null && currentThread.equals(thread)) {
                 state.reset();
-                Log.i(account.name + " run");
+                Log.i(account.name + " run thread=" + currentThread);
 
                 Handler handler = new Handler(getMainLooper());
                 final List<TwoStateOwner> cowners = new ArrayList<>();
@@ -1573,7 +1578,12 @@ public class ServiceSynchronize extends ServiceBase implements SharedPreferences
                     else if (backoff < CONNECT_BACKOFF_AlARM_MAX * 60)
                         state.setBackoff(backoff * 2);
                 }
+
+                currentThread = Thread.currentThread().getId();
             }
+
+            if (currentThread == null || !currentThread.equals(thread))
+                Log.e(account.name + " orphan thread id=" + currentThread + "/" + thread);
         } finally {
             EntityLog.log(this, account.name + " stopped");
             wlAccount.release();