question: private CompletableFuture < String > send ( final Message message ) { final CompletableFuture < String > future = new CompletableFuture < > ( ) ; int currentSize ; int newSize ; do { currentSize = size . get ( ) ; newSize = currentSize + 1 ; if ( newSize > queueSize ) { future . completeExceptionally ( new QueueFullException ( ) ) ; return future ; } } while ( ! size . compareAndSet ( currentSize , newSize ) ) ; queue . add ( new QueuedMessage ( message , future ) ) ; scheduleSend ( newSize ) ; return future ; }
target:  Enqueue a message for sending on this topic queue.