Create pss.java

Author: khwaishchawla

src/main/java/com/thealgorithms/scheduling/pss.java

@@ -0,0 +1,96 @@
+import java.util.PriorityQueue;
+import java.util.Scanner;
+
+// Process class representing a process with attributes: id, weight, burst time, arrival time, and time received
+class Process {
+    int id;
+    int weight;
+    int burstTime;
+    int timeReceived;
+    int arrivalTime;
+    int priorityBoost; // Boost to prevent starvation
+
+    public Process(int id, int weight, int burstTime, int arrivalTime) {
+        this.id = id;
+        this.weight = weight;
+        this.burstTime = burstTime;
+        this.arrivalTime = arrivalTime;
+        this.timeReceived = 0;
+        this.priorityBoost = 0;
+    }
+}
+
+// Comparator to prioritize processes by weight and starvation prevention
+class ProcessComparator implements java.util.Comparator<Process> {
+    @Override
+    public int compare(Process p1, Process p2) {
+        int effectiveWeight1 = p1.weight + p1.priorityBoost;
+        int effectiveWeight2 = p2.weight + p2.priorityBoost;
+        return Integer.compare(effectiveWeight2, effectiveWeight1); // Higher weight gets higher priority
+    }
+}
+
+public class ProportionalShareScheduling {
+
+    // Method to implement the scheduling logic
+    public static void proportionalShareScheduling(PriorityQueue<Process> readyQueue, int totalTimeQuantum) {
+        int currentTime = 0;
+        while (!readyQueue.isEmpty()) {
+            Process current = readyQueue.poll();
+            
+            // Determine time quantum to allocate to the current process
+            int timeGiven = Math.min(current.weight, current.burstTime - current.timeReceived);
+
+            currentTime += timeGiven;
+            current.timeReceived += timeGiven;
+
+            System.out.println("Process " + current.id + " received " + timeGiven + " units at time " + currentTime);
+
+            // If the process has finished execution
+            if (current.timeReceived >= current.burstTime) {
+                System.out.println("Process " + current.id + " completed at time " + currentTime);
+            } else {
+                // Starvation prevention: increase priority boost for unfinished processes
+                current.priorityBoost += 1;
+                readyQueue.add(current); // Reinsert into the queue for future execution
+            }
+
+            // Starvation prevention logic for all other processes in the queue
+            for (Process p : readyQueue) {
+                p.priorityBoost += 1; // Increase the boost to prevent starvation
+            }
+        }
+    }
+
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+
+        // Input number of processes
+        System.out.print("Enter the number of processes: ");
+        int n = sc.nextInt();
+
+        // Input total time quantum
+        System.out.print("Enter the total time quantum: ");
+        int totalTimeQuantum = sc.nextInt();
+
+        // Create a priority queue to store processes based on the comparator
+        PriorityQueue<Process> readyQueue = new PriorityQueue<>(new ProcessComparator());
+
+        // Input the process details (id, weight, burst time, arrival time)
+        for (int i = 0; i < n; i++) {
+            System.out.println("Enter Process ID, Weight, Burst Time, Arrival Time for Process " + (i + 1) + ":");
+            int id = sc.nextInt();
+            int weight = sc.nextInt();
+            int burstTime = sc.nextInt();
+            int arrivalTime = sc.nextInt();
+
+            Process process = new Process(id, weight, burstTime, arrivalTime);
+            readyQueue.add(process); // Add each process to the priority queue
+        }
+
+        // Call the scheduling function
+        proportionalShareScheduling(readyQueue, totalTimeQuantum);
+
+        sc.close();
+    }
+}