import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import java.util.function.Predicate;

public class GuardedObject {
    //
    T obj;
    final Lock lock = new ReentrantLock();
    final Condition done = lock.newCondition();
    final int timeout = 2;
    //GuardedObject
    final static Map gos = new ConcurrentHashMap();

    //GuardedObject
    static  GuardedObject create(K key) {
        GuardedObject go = new GuardedObject();
        gos.put(key, go);
        return go;
    }

    static  void fireEvent(K key, T obj) {
        GuardedObject go = gos.remove(key);
        if (go != null) {
            go.onChanged(obj);
        }
    }

    //
    T get(Predicate p) {
        lock.lock();
        try {
            //MESA
            while (!p.test(obj)) {
                done.await(timeout,
                        TimeUnit.SECONDS);
            }
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        } finally {
            lock.unlock();
        }
        //
        return obj;
    }

    //
    void onChanged(T obj) {
        lock.lock();
        try {
            this.obj = obj;
            done.signalAll();
        } finally {
            lock.unlock();
        }
    }

}