private void enqueue(E x){
  items[putIndex]=x;
  putIndex=inc(putIndex);
  count++;
  notEmpty.signal();
}

private void enqueue ( E x ) { items [ putIndex ] = x ; putIndex = inc ( putIndex ) ; count ++ ; notEmpty . signal ( ) ; }
inserts element at current put position , advances , and signals . call only when holding lock .
