public synchronized SlabRef detach(){
  if (!isAttached()) {
    return null;
  }
  SlabRef slab=_slab;
  _slab=null;
  _slabExpiresAt=0;
  return slab;
}

public synchronized SlabRef detach ( ) { if ( ! isAttached ( ) ) { return null ; } SlabRef slab = _slab ; _slab = null ; _slabExpiresAt = 0 ; return slab ; }
detaches a slab from the channel and returns it to the caller to dispose of .
