buffer-semaphore-good

class Buffer<T> {

    List<T> items;
    private int capacity;

    private Semaphore consumeSemaphore = new Semaphore(0);
    private Semaphore produceSemaphore = new Semaphore(1);

    private Semaphore pcCoordinatorSemaphore = new Semaphore(1);

    Buffer(int capacity) {
        this.items = new ArrayList<>(capacity);
        this.capacity = capacity;
    }

    T getItem() throws InterruptedException {
        T item = null;
        consumeSemaphore.acquire();
        pcCoordinatorSemaphore.acquire();
        while (items.size() == 0) {
            pcCoordinatorSemaphore.release();
            Thread.sleep(100);
            pcCoordinatorSemaphore.acquire();
        }

        item = items.remove(items.size() - 1);

        pcCoordinatorSemaphore.release();
        produceSemaphore.release();
        return item;
    }

    void addItem(T item) throws InterruptedException {
        produceSemaphore.acquire();
        pcCoordinatorSemaphore.acquire();

        while (items.size() > capacity) {
            pcCoordinatorSemaphore.release();
            Thread.sleep(100);
            pcCoordinatorSemaphore.acquire();
        }

        items.add(item);

        pcCoordinatorSemaphore.release();
        consumeSemaphore.release();
    }

}