Question

I wish to add processes to a dynamic list then schedule those processes using the “first come first served” scheduling algorithm. The scheduling algorithm should only run a max of 5 processes concurrently and when a process has been terminated it should it should emit a signal to indicate termination.

Then when a process has been terminated, another process should be scheduled by the scheduling algorithm once there are processes in the queue.

Note also that each process has access to a shared list of integer which only one process can access at a time. I already know how to do this part by locking the shared integer list using QMutex. Ideally, I am seeking an example, so I can understand it.

//mutex example
QMutex mutex
while(!mutex->tryLock()){
    //enter code here
}
this->performTask(); // 
mutex.unlock();

Answer 1

You will have 5 instances of a class that extends QThread. Each class will execute a QProcess and wait for it to finish.

class MyThread : public QThread
{
public:
    MyThread(MyScheduler& aScheduler)
    :   iScheduler(aScheduler)
    {
    }

    void ExecuteProgram(const QString& aProgramName)
    {
        iProgramName = aProgramName;
        start();
    }

    void run()
    {
        iProcess.start(iProgramName);
        iProcess.waitForFinished(-1);
        iScheduler.SignalProgramTerminated(this);
    }

private:
    MyScheduler& iScheduler;  // This is your FCFS scheduler.
    QString iProgramName;
    QProcess iProcess;
};

(I haven’t compiled this but it should give you some headway).