public class LeaseHolder {
    private final int maxWorkerCount;
    private int leasesInUse;

    public LeaseHolder(int maxWorkerCount) {
        this.maxWorkerCount = maxWorkerCount;
    }

    public boolean grantLease() {
        if (leasesInUse >= maxWorkerCount) {
            return false;
        }
        leasesInUse++;
        return true;
    }

    public void releaseLease() {
        leasesInUse--;
    }

    }

    @Override
    protected boolean doIsLockedByCurrentThread() {
        return Thread.currentThread() == ownerThread;
    }

    @Override
    protected boolean acquireLock() {
        if (parent.grantLease()) {
            ownerThread = Thread.currentThread();
        }
        return ownerThread != null;
    }

    @Override
    protected void releaseLock() {
        if (Thread.currentThread() != ownerThread) {