refactor(core): Convert app to Qt app

src/apps/deskflow-core/deskflow-core.cpp

@@ -1,7 +1,7 @@
 /*
  * Deskflow -- mouse and keyboard sharing utility
  * SPDX-FileCopyrightText: (C) 2025 Chris Rizzitello <sithlord48@gmail.com>
- * SPDX-FileCopyrightText: (C) 2012 - 2016 Symless Ltd.
+ * SPDX-FileCopyrightText: (C) 2012 - 2016, 2025 - 2026 Symless Ltd.
  * SPDX-FileCopyrightText: (C) 2002 Chris Schoeneman
  * SPDX-License-Identifier: GPL-2.0-only WITH LicenseRef-OpenSSL-Exception
  */
@@ -21,15 +21,27 @@
 #include <QCoreApplication>
 #endif
 
+#include <QCoreApplication>
 #include <QFileInfo>
 #include <QSharedMemory>
 #include <QTextStream>
+#include <QThread>
 
 void showHelp(const CoreArgParser &parser)
 {
   QTextStream(stdout) << parser.helpText();
 }
 
+App *createApp(const CoreArgParser &parser, EventQueue &events, const QString &processName)
+{
+  if (parser.serverMode()) {
+    return new ServerApp(&events, processName);
+  } else if (parser.clientMode()) {
+    return new ClientApp(&events, processName);
+  }
+  return nullptr;
+}
+
 int main(int argc, char **argv)
 {
 #if defined(Q_OS_WIN)
@@ -86,13 +98,18 @@ int main(int argc, char **argv)
   EventQueue events;
   const auto processName = QFileInfo(argv[0]).fileName();
 
-  if (parser.serverMode()) {
-    ServerApp app(&events, processName);
-    return app.run();
-  } else if (parser.clientMode()) {
-    ClientApp app(&events, processName);
-    return app.run();
-  }
+  App *coreApp = createApp(parser, events, processName);
 
-  return s_exitSuccess;
+  QCoreApplication app(argc, argv);
+  QCoreApplication::setApplicationName(QStringLiteral("%1 Core").arg(kAppName));
+
+  QThread coreThread;
+  QObject::connect(&coreThread, &QThread::finished, &app, &QCoreApplication::quit);
+  coreApp->run(coreThread);
+
+  const auto exitCode = QCoreApplication::exec();
+  coreThread.wait();
+
+  LOG_DEBUG("core exited, code: %d", exitCode);
+  return exitCode;
 }

src/lib/deskflow/App.cpp

@@ -1,6 +1,6 @@
 /*
  * Deskflow -- mouse and keyboard sharing utility
- * SPDX-FileCopyrightText: (C) 2012 - 2025 Symless Ltd.
+ * SPDX-FileCopyrightText: (C) 2012 - 2026 Symless Ltd.
  * SPDX-FileCopyrightText: (C) 2002 Chris Schoeneman
  * SPDX-License-Identifier: GPL-2.0-only WITH LicenseRef-OpenSSL-Exception
  */
@@ -57,48 +57,69 @@ App::~App()
   s_instance = nullptr;
 }
 
-int App::run()
+void App::run(QThread &coreThread)
 {
+  LOG_NOTE("starting core");
+
+  // Important: Move the daemon app to the daemon thread before creating any more Qt objects
+  // owned by the daemon app, as they will be created on the daemon thread.
+  moveToThread(&coreThread);
+
+  connect(&coreThread, &QThread::started, this, [this, &coreThread]() {
+    LOG_DEBUG("core thread started");
+
 #if MAC_OS_X_VERSION_10_7
-  // dock hide only supported on lion :(
-  ProcessSerialNumber psn = {0, kCurrentProcess};
+    // dock hide only supported on lion :(
+    ProcessSerialNumber psn = {0, kCurrentProcess};
 
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
-  GetCurrentProcess(&psn);
+    GetCurrentProcess(&psn);
 #pragma GCC diagnostic pop
 
-  TransformProcessType(&psn, kProcessTransformToBackgroundApplication);
+    TransformProcessType(&psn, kProcessTransformToBackgroundApplication);
 #endif
 
-  // install application in to arch
-  appUtil().adoptApp(this);
+    // install application in to arch
+    appUtil().adoptApp(this);
 
-  // HACK: fail by default (saves us setting result in each catch)
-  int result = s_exitFailed;
+    // HACK: fail by default (saves us setting result in each catch)
+    int result = s_exitFailed;
 
-  try {
-    result = appUtil().run();
-  } catch (ExitAppException &e) {
-    // instead of showing a nasty error, just exit with the error code.
-    // not sure if i like this behaviour, but it's probably better than
-    // using the exit(int) function!
-    result = e.getCode();
-  } catch (DisplayInvalidException &die) {
-    LOG_CRIT("a display invalid exception error occurred: %s\n", die.what());
-    // display invalid exceptions can occur when going to sleep. When this
-    // process exits, the UI will restart us instantly. We don't really want
-    // that behevior, so we quies for a bit
-    Arch::sleep(10);
-  } catch (std::runtime_error &re) {
-    LOG_CRIT("a runtime error occurred: %s\n", re.what());
-  } catch (std::exception &e) {
-    LOG_CRIT("an error occurred: %s\n", e.what());
-  } catch (...) {
-    LOG_CRIT("an unknown error occurred\n");
-  }
+    try {
+      result = appUtil().run();
+    } catch (ExitAppException &e) {
+      // instead of showing a nasty error, just exit with the error code.
+      // not sure if i like this behaviour, but it's probably better than
+      // using the exit(int) function!
+      result = e.getCode();
+    } catch (DisplayInvalidException &die) {
+      LOG_CRIT("a display invalid exception error occurred: %s\n", die.what());
+      // display invalid exceptions can occur when going to sleep. When this
+      // process exits, the UI will restart us instantly. We don't really want
+      // that behevior, so we quies for a bit
+      Arch::sleep(10);
+    } catch (std::runtime_error &re) {
+      LOG_CRIT("a runtime error occurred: %s\n", re.what());
+    } catch (std::exception &e) {
+      LOG_CRIT("an error occurred: %s\n", e.what());
+    } catch (...) {
+      LOG_CRIT("an unknown error occurred\n");
+    }
 
-  return result;
+    if (result == s_exitSuccess) {
+      LOG_INFO("core stopped successfully");
+    } else {
+      // TODO: surface error code to main thread somehow
+      LOG_ERR("core stopped with error code: %d", result);
+    }
+
+    coreThread.quit();
+    LOG_DEBUG("core thread finished");
+  });
+
+  LOG_DEBUG("starting core thread");
+  coreThread.start();
 }
 
 void App::setupFileLogging()

src/lib/deskflow/App.h

@@ -1,7 +1,7 @@
 /*
  * Deskflow -- mouse and keyboard sharing utility
  * SPDX-FileCopyrightText: (C) 2026 Deskflow Developers
- * SPDX-FileCopyrightText: (C) 2012 - 2025 Symless Ltd.
+ * SPDX-FileCopyrightText: (C) 2012 - 2026 Symless Ltd.
  * SPDX-FileCopyrightText: (C) 2002 Chris Schoeneman
  * SPDX-License-Identifier: GPL-2.0-only WITH LicenseRef-OpenSSL-Exception
  */
@@ -19,6 +19,9 @@
 #include "deskflow/unix/AppUtilUnix.h"
 #endif
 
+#include <QObject>
+#include <QThread>
+
 #include <memory>
 #include <stdexcept>
 
@@ -30,7 +33,7 @@ class FileLogOutputter;
 class IEventQueue;
 class SocketMultiplexer;
 
-class App : public IApp
+class App : public QObject, private IApp
 {
 public:
   class XNoEiSupport : public std::runtime_error
@@ -72,7 +75,7 @@ public:
     return m_appUtil;
   }
 
-  int run();
+  void run(QThread &coreThread);
   void setupFileLogging();
   void loggingFilterWarning() const;
   void initApp() override;