2 files changed, 111 insertions, 0 deletions
diff --git a/src/rungaurd.cpp b/src/rungaurd.cpp
new file mode 100644
index 0000000..7136e7b
--- /dev/null
+++ b/src/rungaurd.cpp
@@ -0,0 +1,79 @@
+#include "rungaurd.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();
+}
diff --git a/src/rungaurd.h b/src/rungaurd.h
new file mode 100644
index 0000000..06d45a8
--- /dev/null
+++ b/src/rungaurd.h
@@ -0,0 +1,32 @@
+#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