Qt:单实例应用程序保护的最佳实践

2021-12-09 00:00:00 qt c++ qmutex qsharedmemory

QSingleApplication?QMutex?QSharedMemory?我正在寻找可以在 Windows、OSX 和 Linux (Ubuntu) 中顺利运行的东西.使用 Qt 4.7.1

QSingleApplication? QMutex? QSharedMemory? I'm looking for something that will work smoothly in Windows, OSX and Linux (Ubuntu). Using Qt 4.7.1

推荐答案

简单的解决方案，满足您的需求.没有网络依赖(如 QtSingleApplication)并且没有任何开销.

Simple solution, that does what you want. Without network dependency (as QtSingleApplication) and without any overhead.

用法:

int main()
{
    RunGuard guard( "some_random_key" );
    if ( !guard.tryToRun() )
        return 0;

    QAppplication a(/*...*/);
    // ...
}

RunGuard.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

RunGuard.cpp

RunGuard.cpp

#include "RunGuard.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();
}

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