}

// ReplicaSetsBySizeNewer sorts a list of ReplicaSet by size in descending order, using their creation timestamp or name as a tie breaker.
// By using the creation timestamp, this sorts from new to old replica sets.
type ReplicaSetsBySizeNewer []*apps.ReplicaSet

func (o ReplicaSetsBySizeNewer) Len() int      { return len(o) }
func (o ReplicaSetsBySizeNewer) Swap(i, j int) { o[i], o[j] = o[j], o[i] }

		// when scaling down, we should scale down older replica sets first.
		var scalingOperation string
		switch {
		case deploymentReplicasToAdd > 0:
			sort.Sort(controller.ReplicaSetsBySizeNewer(allRSs))
			scalingOperation = "up"

		case deploymentReplicasToAdd < 0:
			sort.Sort(controller.ReplicaSetsBySizeOlder(allRSs))
			scalingOperation = "down"
		}