Priority with SRTF CPU Scheduling Simulator

🧠 Purpose

This Java program simulates CPU scheduling using a hybrid algorithm:
Priority-based scheduling with Shortest Remaining Time First (SRTF).

It is designed to:

• Accurately model how operating systems schedule processes.
• Help students understand how both priority and remaining burst time influence process execution.
• Allow interactive input and provide clear output including a Gantt chart and performance metrics (TAT, WT, RT).

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📌 Features

• Input multiple processes (PID, Arrival Time, Burst Time, Priority).
• Automatically handles:
  • Invalid characters or formatting.
  • Negative values and zero burst time.
  • Duplicate PIDs.
  • The case where the user enters 0 0 0 0 immediately.
• Calculates:
  • Completion Time
  • Turnaround Time (TAT)
  • Waiting Time (WT)
  • Response Time (RT)
• Prints a visual Gantt Chart.
• Displays averages for key performance metrics.
• Prevents the program from continuing without valid processes.

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⚙️ How It Works

1. User Input:

   • The user enters processes one by one in the format:

     PID ArrivalTime BurstTime Priority
     

   • Ends input with:

     0 0 0 0
     

2. Validation:

   • Checks if all lines contain exactly four numbers.
   • Ensures Arrival Time and Priority are ≥ 0, Burst Time > 0.
   • Ensures no duplicate PIDs.

3. Scheduling Logic:

   • At each time unit, the scheduler chooses the process that:
     • Has the shortest remaining time.
     • If tied, has the higher priority (lower number).
   • Preemptive: the CPU can switch if a new eligible process arrives.
   • Tracks Gantt chart entries at every time unit.
   • Updates process metrics upon completion.

4. Output:

   • Shows Gantt chart.
   • Prints a table of all process data and metrics.
   • Shows average Turnaround Time, Waiting Time, and Response Time.

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📥 Input Format & 📤 Output Sample

1 0 4 2
2 1 3 1
3 2 2 3
0 0 0 0

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👩‍💻 Authors

Fatema Redha Hamza
Sara Mansoor Mahmood
Fatima Mohamed Hasan Abdulla
Eman Rauf

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📝 Note

This project is part of an academic assignment to simulate CPU scheduling. It does not interact with real operating system processes, but rather uses theoretical modeling for educational purposes.