Switch sqlite db to WAL mode

gui/mainwindow.cpp

@@ -630,6 +630,8 @@ void MainWindow::saveSettings()
 								  "Failed to remove old database. Settings not saved.");
 			return;
 		}
+		QFile::remove(Common::databasePath() + "-shm");
+		QFile::remove(Common::databasePath() + "-wal");
 	}
 
 	QSettings settings;

shared/databasefactory.cpp

@@ -1,4 +1,5 @@
 #include <QThread>
+#include <QSqlQuery>
 #include "databasefactory.h"
 #include "logger.h"
 #include "looqsgeneralexception.h"
@@ -31,11 +32,23 @@ QSqlDatabase DatabaseFactory::forCurrentThread()
 	QSqlDatabase db =
 		QSqlDatabase::addDatabase("QSQLITE", "LOOQS" + QString::number((quint64)QThread::currentThread(), 16));
 	db.setDatabaseName(this->connectionString);
+	db.setConnectOptions("QSQLITE_BUSY_TIMEOUT=30000");
 	if(!db.open())
 	{
 		Logger::error() << "Failed to open the database: " << this->connectionString << Qt::endl;
 		throw LooqsGeneralException("Failed to create open new connection");
 	}
+	QSqlQuery q(db);
+	if(!q.exec("PRAGMA journal_mode=WAL;"))
+	{
+		Logger::error() << "Failed to set WAL mode: " << this->connectionString << Qt::endl;
+		throw LooqsGeneralException("Failed to set WAL mode on sqlite database");
+	}
+	if(!q.exec("PRAGMA wal_autocheckpoint=250;"))
+	{
+		Logger::error() << "Failed to set WAL autocheckpoint: " << this->connectionString << Qt::endl;
+		throw LooqsGeneralException("Failed to set WAL autocheckpoint on sqlite database");
+	}
 	dbStore.setLocalData(db);
 	return db;
 }