func (w *WaterMark) SetDoneUntil(val uint64) {
	atomic.StoreUint64(&w.doneUntil, val)
}
func (w *WaterMark) SetDoneUntil(val uint64) {
	atomic.StoreUint64(&w.doneUntil, val)
}
func ( w * WaterMark ) SetDoneUntil ( val uint64 ) { atomic . StoreUint64 ( & w . doneUntil , val ) }
// SetDoneUntil sets the maximum index that has the property that all indices
// less than or equal to it are done.
SetDoneUntil sets the maximum index that has the property that all indices less than or equal to it are done .