(Shell) Operating system task scheduling simulation // //-----------------------

Question

(Shell) Operating system task scheduling simulation
//
//--------------------------------------------------------------------

// Simulates an operating system's use of a priority queue to regulate
// access to a system resource (printer, disk, etc.).

#include <iostream>
#include <cstdlib>
#include "PriorityQueue.cpp"
#include <time.h>

using namespace std;

//--------------------------------------------------------------------
//
// Declaration for the task data struct
//

struct TaskData
{
int getPriority () const
{ return priority; } // Returns the priority. Needed by the heap.

int priority, // Task's priority
arrived; // Time when task was enqueued

};

//--------------------------------------------------------------------   

int main()
{
   PriorityQueue<TaskData, int, Less<int> > taskPQ; // Priority queue of tasks
   TaskData task; // Task
   int simLength, // Length of simulation (minutes)
       minute, // Current minute
       numPtyLevels, // Number of priority levels
       numArrivals, // Number of new tasks arriving
       j; // Loop counter

   // Seed the random number generator
   srand((unsigned int)time(NULL));

   cout << endl << "Enter the number of priority levels : ";
   cin >> numPtyLevels;

   cout << "Enter the length of time to run the simulator : ";
   cin >> simLength;

   for (minute = 0; minute < simLength; minute++)
   {
       // Dequeue the first task in the queue (if any).
       // Your code here

       // Determine the number of new tasks and add them to
       // the queue.
       // Your code here

   }

   return 0;
  

}

Explanation / Answer

for ( minute = 0 ; minute < simLength ; minute++ )
{
// Dequeue the first task in the queue (if any).
   // Your code here
if(!taskPQ.isEmpty())
{
task = taskPQ.dequeue();
cout << "At " << minute << " dequeued : ";
cout << task.priority << " " << task.arrived << " " <<
(minute - task.arrived) << endl;
}

// Determine the number of new tasks and add them to
// the queue.
   // Your code here
switch(rand() % 4)
{
case 1:
if(!taskPQ.isFull())
{
task.priority = rand() % numPtyLevels;
task.arrived = minute;
taskPQ.enqueue(task);
}
break;
case 2:
for(j = 0; j < 2 && !taskPQ.isFull(); j++)
{
task.priority = rand() % numPtyLevels;
task.arrived = minute;
taskPQ.enqueue(task);
}
break;
}

}

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