ThreadPoolStats.java

package com.taskscheduler;

import java.util.concurrent.atomic.AtomicLong;

/**
 * Tracks runtime statistics for the thread pool.
 * Thread-safe using atomic operations.
 */
public class ThreadPoolStats {

    private final AtomicLong totalCompleted = new AtomicLong(0);
    private final AtomicLong totalFailed    = new AtomicLong(0);
    private final AtomicLong totalWaitTime  = new AtomicLong(0);
    private final AtomicLong totalExecTime  = new AtomicLong(0);

    public void recordCompletion(long waitTimeMs, long execTimeMs) {
        totalCompleted.incrementAndGet();
        totalWaitTime.addAndGet(waitTimeMs);
        totalExecTime.addAndGet(execTimeMs);
    }

    public void recordFailure() {
        totalFailed.incrementAndGet();
    }

    public long getTotalCompleted()  { return totalCompleted.get(); }
    public long getTotalFailed()     { return totalFailed.get(); }

    public double getAverageWaitTime() {
        long completed = totalCompleted.get();
        return completed == 0 ? 0 : (double) totalWaitTime.get() / completed;
    }

    public double getAverageExecTime() {
        long completed = totalCompleted.get();
        return completed == 0 ? 0 : (double) totalExecTime.get() / completed;
    }

    public void printReport() {
        System.out.println("\n========== Thread Pool Stats ==========");
        System.out.printf("  Tasks completed  : %d%n", getTotalCompleted());
        System.out.printf("  Tasks failed     : %d%n", getTotalFailed());
        System.out.printf("  Avg wait time    : %.2f ms%n", getAverageWaitTime());
        System.out.printf("  Avg exec time    : %.2f ms%n", getAverageExecTime());
        System.out.println("=======================================\n");
    }
}