Written by Brian Goetz in “Java Concurrency”

@ThreadSafe
public class BoundedBuffer<E> {
  private final Semaphore availableItems, availableSpaces;
  @GuardedBy("this") private final E[] items;
  @GuardedBy("this") private int putPosition=0; takePosition=0;

  public BoundedBuffer(int capacity) {
    availableItems= new Semaphore(0);
    availableSpaces = new Semaphore(capacity);
    items = (E[]) new Object[capacity];
  }
  public boolean isEmpty() {
    return availableItems.availablePermits()==0;
  }
  public boolean isFull() {
    return availableSpaces.availablePermits()==0;
  }
  public void put(E x) throws InterruptedException {
    availableSpaces.acquire();
    doInsert(x);
    availableItems.release();
  }
  public E take() throws InterruptedException {
    availableItems.acquire();
    E items = doExtract();
    availableSpaces.release();
    return item;
  }

  private synchronized void doInsert(E x){
    int i = putPosition;
    items[i] = x;
    putPosition = (++1 == items.length)? 0:i;
  }
  private synchronized E doExtract() {
    int i = takePosition;
    E x = items[i];
    items[i] = null;
    takePosition = (++i == items.length)?0:i;
    return x;
  }
}