Wrap reindex into transaction

database.cpp

@@ -157,6 +157,7 @@ void Database::reindex(QProgressDialog *progress)
 {
     QVariantList deleteids;
     QSqlDatabase database = QSqlDatabase::database();
+    database.transaction();
     QSqlQuery files = database.exec("SELECT id,file,mtime FROM fits_files");
     progress->setMaximum(files.size());
     int i = 0;
@@ -169,10 +170,16 @@ void Database::reindex(QProgressDialog *progress)
         if(!file.exists())
             deleteids.append(files.value(0));
         progress->setValue(i++);
+        if(progress->wasCanceled())
+        {
+            database.rollback();
+            return;
+        }
     }
     QSqlQuery deleteFiles("DELETE FROM fits_files WHERE id = ?", database);
     deleteFiles.bindValue(0, deleteids);
     deleteFiles.execBatch();
+    database.commit();
 }
 
 QStringList Database::getFitsKeywords()