resource_allocator.java

import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public class ResourceAllocator {

    private boolean busy;
    private final Lock lock = new ReentrantLock();
    private final Condition resourceAvailable = lock.newCondition();

    public ResourceAllocator() {
        this.busy = false;
    }

    public void acquire(long timeoutMillis) throws InterruptedException {
        lock.lock();
        try {
            if (busy) {
               if(!resourceAvailable.await(timeoutMillis, java.util.concurrent.TimeUnit.MILLISECONDS))
                   System.out.println(" Timed out waiting for resource.");
            }
            if(!busy){
                 busy = true;
            }
        } finally {
            lock.unlock();
        }
    }

    public void release() {
        lock.lock();
        try {
            busy = false;
            resourceAvailable.signal();
        } finally {
            lock.unlock();
        }
    }
}