Sinhronizacija so pomos na Semaphor

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Semaphore;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public class SemaphorsLibrary {
    List<String> books = new ArrayList<>();
    int kapacitet;

    Semaphore koordinator = new Semaphore(1); //ni pomaga za kriticniot domen
    Semaphore returnBookSemaphor = new Semaphore(10);
    Semaphore borrowBookSemaphor = new Semaphore(10);

    public SemaphorsLibrary(int kapacitet) {
        this.kapacitet = kapacitet;
    }

    //slucaj koga clenot treba da vrati kniga vo bibliotekatta
    public void returnBook(String book) throws InterruptedException {
        returnBookSemaphor.acquire(); //ke dade kluc
        koordinator.acquire(); //zaklucuvame kriticen domen
        if (books.size() == kapacitet) {
            Thread.sleep(1000);
            koordinator.acquire();
        }
        books.add(book);
        koordinator.release(); //predadi kluc na dr
        borrowBookSemaphor.release();
    }


    //slucaj kgoa clenot treba da zeme kniga od bibliotekata
    public String borrowBook() throws InterruptedException {
        borrowBookSemaphor.acquire();
        String book = "";
        koordinator.acquire();
        while (books.size() == 0) {
            koordinator.release();
            Thread.sleep(1000);
            koordinator.acquire();
        }
        book = books.remove(0);
        returnBookSemaphor.release();
        return book;
    }

}