ProducerThread.java

import java.util.Random;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.atomic.AtomicInteger;

public class ProducerThread extends Thread {

    private static final AtomicInteger ID_COUNTER = new AtomicInteger(1);

    private final BlockingQueue<Order> queue;
    private final int                  ordersToGenerate;
    private final Random               random = new Random();

    public ProducerThread(BlockingQueue<Order> queue, String name, int ordersToGenerate) {
        super(name);
        this.queue            = queue;
        this.ordersToGenerate = ordersToGenerate;
    }

    @Override
    public void run() {
        for (int i = 0; i < ordersToGenerate; i++) {
            int   seqId = ID_COUNTER.getAndIncrement();
            int   roll  = random.nextInt(10);
            Order order;

            if (roll < 8) { // 80% BUY/SELL
                Order.Side side = (roll < 4) ? Order.Side.BUY : Order.Side.SELL;
                double price    = 100.0 + (random.nextDouble() * 4);
                int    qty      = 1 + random.nextInt(100);
                order = new Order(seqId, side, price, qty, -1);
            } else { // 20% CANCEL
                int cancelTarget = Math.max(1, seqId - random.nextInt(50));
                order = new Order(seqId, Order.Side.CANCEL, 0, 0, cancelTarget);
            }

            try {
                queue.put(order);
            } catch (InterruptedException e) {
                Thread.currentThread().interrupt();
                break;
            }
        }
        System.out.println("[" + getName() + "] Done.");
    }
}