Exemplo n.º 1
0
// getTailFromRing returns the oldest ring element that contains the beginning of
// our sequence range (start - end) and whose range of ring segments all
// have their Reassembly.Skip value set to 0 (zero).
func getTailFromRing(head *types.Ring, end types.Sequence) *types.Ring {
	var ret *types.Ring

	for r := head; r != head.Prev(); r = r.Next() {
		if r.Reassembly == nil {
			ret = r.Prev()
			break
		}
		if len(r.Reassembly.Bytes) == 0 {
			log.Print("getTailFromRing: zero payload ring segment encountered.")
			ret = r.Prev()
			break
		}
		if r.Reassembly.Skip != 0 {
			log.Print("getTailFromRing: stream skip encountered.")
			ret = r.Prev()
			break
		}
		diff := r.Reassembly.Seq.Difference(end)
		if diff < 0 {
			return r.Prev()
		}
	}

	// XXX
	// prevent bug where the above sets ret to head.Prev()
	if ret == head.Prev() {
		return nil
	} else {
		return ret
	}
	return nil
}
Exemplo n.º 2
0
// getHeadFromRing returns a pointer to the oldest ring element that
// contains the beginning of our sequence range (start - end) AND
// whose Reassembly.Skip value is 0 (zero).
func getHeadFromRing(ringPtr *types.Ring, start, end types.Sequence) *types.Ring {
	var head *types.Ring
	current := ringPtr.Prev()
	if current.Reassembly == nil {
		return nil
	}
	if start.Difference(current.Reassembly.Seq.Add(len(current.Reassembly.Bytes)-1)) < 0 {
		log.Printf("lastestSeq %d < newStartSeq %d\n", current.Reassembly.Seq.Add(len(current.Reassembly.Bytes)-1), start)
		return nil
	}
	head = nil
	var candidate *types.Ring = nil

	for current := ringPtr.Prev(); current != ringPtr && current.Reassembly != nil; current = current.Prev() {
		if len(current.Reassembly.Bytes) == 0 {
			continue
		}

		startDiff := current.Reassembly.Seq.Difference(start)
		if startDiff == 0 {
			return current
		}
		if startDiff < 0 {
			finishEndDiff := current.Reassembly.Seq.Difference(end)
			if finishEndDiff >= 0 {
				candidate = current
			}

			continue
		} else {
			endDiff := start.Difference(current.Reassembly.Seq.Add(len(current.Reassembly.Bytes) - 1))
			if endDiff >= 0 {
				head = current
				break
			}
		}
	}
	if head == nil && candidate != nil {
		head = candidate
	}
	return head
}