Safely close database connections and delete backends

Also fix NewClosure leak caused by disconnected object signals

src/device/devicedatabasebackend.cpp

@@ -18,9 +18,14 @@
  *
  */
 
+#include "config.h"
+
 #include <stdbool.h>
+#include <assert.h>
 
 #include <QObject>
+#include <QApplication>
+#include <QThread>
 #include <QMutex>
 #include <QIODevice>
 #include <QFile>
@@ -32,17 +37,47 @@
 
 #include "core/database.h"
 #include "core/scopedtransaction.h"
+#include "core/logging.h"
 #include "devicedatabasebackend.h"
 
 const int DeviceDatabaseBackend::kDeviceSchemaVersion = 0;
 
 DeviceDatabaseBackend::DeviceDatabaseBackend(QObject *parent) :
     QObject(parent),
-    db_(nullptr)
-    {}
+    db_(nullptr),
+    original_thread_(nullptr)
+    {
+
+  original_thread_ = thread();
+
+}
+
+DeviceDatabaseBackend::~DeviceDatabaseBackend() {}
 
 void DeviceDatabaseBackend::Init(Database* db) { db_ = db; }
 
+void DeviceDatabaseBackend::Close() {
+
+  if (db_) {
+    QMutexLocker l(db_->Mutex());
+    db_->Close();
+  }
+
+}
+
+void DeviceDatabaseBackend::ExitAsync() {
+  metaObject()->invokeMethod(this, "Exit", Qt::QueuedConnection);
+}
+
+void DeviceDatabaseBackend::Exit() {
+
+  assert(QThread::currentThread() == thread());
+  Close();
+  moveToThread(original_thread_);
+  emit ExitFinished();
+
+}
+
 DeviceDatabaseBackend::DeviceList DeviceDatabaseBackend::GetAllDevices() {
 
   QMutexLocker l(db_->Mutex());
@@ -101,6 +136,7 @@ int DeviceDatabaseBackend::AddDevice(const Device &device) {
   db_->ExecSchemaCommands(db, schema, 0, true);
 
   t.Commit();
+
   return id;
 
 }

src/device/devicedatabasebackend.h

@@ -40,6 +40,7 @@ class DeviceDatabaseBackend : public QObject {
 
  public:
   Q_INVOKABLE DeviceDatabaseBackend(QObject *parent = nullptr);
+  ~DeviceDatabaseBackend();
 
   struct Device {
     Device() : id_(-1) {}
@@ -58,6 +59,9 @@ class DeviceDatabaseBackend : public QObject {
   static const int kDeviceSchemaVersion;
 
   void Init(Database *db);
+  void Close();
+  void ExitAsync();
+
   Database *db() const { return db_; }
 
   DeviceList GetAllDevices();
@@ -66,8 +70,16 @@ class DeviceDatabaseBackend : public QObject {
 
   void SetDeviceOptions(int id, const QString &friendly_name, const QString &icon_name, MusicStorage::TranscodeMode mode, Song::FileType format);
 
+ private slots:
+  void Exit();
+
+ signals:
+  void ExitFinished();
+
  private:
   Database *db_;
+  QThread *original_thread_;
+
 };
 
 #endif  // DEVICEDATABASEBACKEND_H

src/device/devicemanager.cpp

@@ -158,9 +158,17 @@ DeviceManager::~DeviceManager() {
     delete lister;
   }
 
-  backend_->deleteLater();
+  backend_->Close();
 
   delete root_;
+  delete backend_;
+
+}
+
+void DeviceManager::Exit() {
+
+  connect(backend_, SIGNAL(ExitFinished()), this, SIGNAL(ExitFinished()));
+  backend_->ExitAsync();
 
 }
 
@@ -174,6 +182,7 @@ void DeviceManager::LoadAllDevices() {
     info->InitFromDb(device);
     emit DeviceCreatedFromDB(info);
   }
+  backend_->Close();
 
 }
 

src/device/devicemanager.h

@@ -85,6 +85,8 @@ class DeviceManager : public SimpleTreeModel<DeviceInfo> {
   static const int kDeviceIconSize;
   static const int kDeviceIconOverlaySize;
 
+  void Exit();
+
   DeviceStateFilterModel *connected_devices_model() const { return connected_devices_model_; }
 
   // Get info about devices
@@ -115,6 +117,7 @@ class DeviceManager : public SimpleTreeModel<DeviceInfo> {
   void Unmount(QModelIndex idx);
 
  signals:
+  void ExitFinished();
   void DeviceConnected(QModelIndex idx);
   void DeviceDisconnected(QModelIndex idx);
   void DeviceCreatedFromDB(DeviceInfo* info);

src/device/gpodloader.cpp

@@ -102,6 +102,8 @@ Itdb_iTunesDB *GPodLoader::TryLoad() {
   // Add the songs we've just loaded
   backend_->AddOrUpdateSongs(songs);
 
+  backend_->Close();
+
   return db;
 
 }

src/device/mtploader.cpp

@@ -96,6 +96,8 @@ bool MtpLoader::TryLoad() {
   // Add the songs we've just loaded
   backend_->AddOrUpdateSongs(songs);
 
+  backend_->Close();
+
   return true;
 
 }