Added run guard to prevent tray from opening multiple instances

CMakeLists.txt

@@ -23,6 +23,8 @@ add_executable(pamac-tray-plasma
   main.cpp
   pamac_tray.cpp
   pamac_tray.h
+  run_guard.cpp
+  run_guard.h
 )
 target_include_directories(pamac-tray-plasma PUBLIC ${DEPS_INCLUDE_DIRS})
 

main.cpp

 #include <QApplication>
 #include <libnotify/notify.h>
 #include <pamac_tray.h>
+#include <run_guard.h>
 int main(int argc, char *argv[])
 {
+    RunGuard guard("org.manjaro.pamac.tray-plasma");
+    if(!guard.tryToRun()){
+        return 0;
+    }
+
     QApplication a(argc, argv);
     notify_init("Package Manager");
 

run_guard.cpp

+#include "run_guard.h"
+
+#include <QCryptographicHash>
+
+
+namespace
+{
+
+QString generateKeyHash( const QString& key, const QString& salt )
+{
+    QByteArray data;
+
+    data.append( key.toUtf8() );
+    data.append( salt.toUtf8() );
+    data = QCryptographicHash::hash( data, QCryptographicHash::Sha1 ).toHex();
+
+    return data;
+}
+
+}
+
+
+RunGuard::RunGuard( const QString& key )
+    : key( key )
+    , memLockKey( generateKeyHash( key, "_memLockKey" ) )
+    , sharedmemKey( generateKeyHash( key, "_sharedmemKey" ) )
+    , sharedMem( sharedmemKey )
+    , memLock( memLockKey, 1 )
+{
+    memLock.acquire();
+    {
+        QSharedMemory fix( sharedmemKey );    // Fix for *nix: http://habrahabr.ru/post/173281/
+        fix.attach();
+    }
+    memLock.release();
+}
+
+RunGuard::~RunGuard()
+{
+    release();
+}
+
+bool RunGuard::isAnotherRunning()
+{
+    if ( sharedMem.isAttached() )
+        return false;
+
+    memLock.acquire();
+    const bool isRunning = sharedMem.attach();
+    if ( isRunning )
+        sharedMem.detach();
+    memLock.release();
+
+    return isRunning;
+}
+
+bool RunGuard::tryToRun()
+{
+    if ( isAnotherRunning() )   // Extra check
+        return false;
+
+    memLock.acquire();
+    const bool result = sharedMem.create( sizeof( quint64 ) );
+    memLock.release();
+    if ( !result )
+    {
+        release();
+        return false;
+    }
+
+    return true;
+}
+
+void RunGuard::release()
+{
+    memLock.acquire();
+    if ( sharedMem.isAttached() )
+        sharedMem.detach();
+    memLock.release();
+}

run_guard.h

+#ifndef RUNGUARD_H
+#define RUNGUARD_H
+
+#include <QObject>
+#include <QSharedMemory>
+#include <QSystemSemaphore>
+
+
+class RunGuard
+{
+
+public:
+    RunGuard( const QString& key );
+    ~RunGuard();
+
+    bool isAnotherRunning();
+    bool tryToRun();
+    void release();
+
+private:
+    const QString key;
+    const QString memLockKey;
+    const QString sharedmemKey;
+
+    QSharedMemory sharedMem;
+    QSystemSemaphore memLock;
+
+    Q_DISABLE_COPY( RunGuard )
+};
+
+
+#endif // RUNGUARD_H