How to make a loner application using Qt5 + for Windows (xp, 7, 8, 10)? That it was impossible to start two copies at the same time.

  • What is a “loner app” in your understanding? - Kromster
  • 2
    That it was impossible to start two copies at the same time - Miron Sosyak
  • Please add clarifications to the question (edit button) - Kromster

1 answer 1

Lock file

The file will be deleted automatically.
Each user can run his version.

#include <QString> #include <QLockFile> #include <QDir> #include <QMessageBox> QString tmpDir = QDir::tempPath(); QLockFile lockFile(tmpDir + "/<unique identifier>.lock"); if(!lockFile.tryLock(100)){ QMessageBox msgBox; msgBox.setIcon(QMessageBox::Warning); msgBox.setText("You already have this app running." "\r\nOnly one instance is allowed."); msgBox.exec(); return 1; }

Semaphores and shared memory

Unique instance of the application on the whole machine

 QSystemSemaphore sema("<unique identifier>", 1); sema.acquire(); #ifndef Q_OS_WIN32 // в Unix разделяемая память не чистится при креше // Очищаем, если осталась от предыдущих запусков QSharedMemory nix_fix_shmem("<unique identifier 2>"); if(nix_fix_shmem.attach()){ nix_fix_shmem.detach(); } #endif QSharedMemory shmem("<unique identifier 2>"); bool is_running; if (shmem.attach()){ is_running = true; }else{ shmem.create(1); is_running = false; } sema.release(); if(is_running){ QMessageBox msgBox; msgBox.setIcon(QMessageBox::Warning); msgBox.setText("You already have this app running." "\r\nOnly one instance is allowed."); msgBox.exec(); return 1; }