nmon/internal/groups/sum.go

package groups

import (
	"time"

	"github.com/v10networks/nmon/internal/p95"
	"github.com/v10networks/nmon/internal/store"
)

// slot is the group's oriented traffic in one 5-minute window.
type slot struct {
	TS      int64 // window start, Unix ms
	In, Out float64
	// AnyIn and AnyOut say at least one member contributed a sample.
	AnyIn, AnyOut bool
	// FullIn and FullOut say every contributing member had a sample, so the
	// sum is not understated.
	FullIn, FullOut bool
}

// orient maps a member's raw directions to the group's: "toward" keeps them,
// "away" swaps them, since "in" on the port is then traffic leaving the group's
// subject.
func orient(m store.GroupMember) (inDir, outDir string) {
	if m.Direction == store.DirAway {
		return p95.DirOut, p95.DirIn
	}
	return p95.DirIn, p95.DirOut
}

// index turns sorted points into a timestamp lookup.
func index(rates map[p95.Key][]p95.Point) map[p95.Key]map[int64]float64 {
	out := make(map[p95.Key]map[int64]float64, len(rates))
	for k, pts := range rates {
		m := make(map[int64]float64, len(pts))
		for _, p := range pts {
			m[p.TS] = p.V
		}
		out[k] = m
	}
	return out
}

// sum computes the slots of [from, to). A window with no member in force has
// no slot: no membership is not missing data.
func (p plan) sum(rates map[p95.Key][]p95.Point, from, to time.Time) []slot {
	idx := index(rates)
	var out []slot
	for t := from; t.Before(to); t = t.Add(p95.Window) {
		members := p.eligibleAt(t)
		if len(members) == 0 {
			continue
		}
		s := slot{TS: t.UnixMilli(), FullIn: true, FullOut: true}
		for _, m := range members {
			inDir, outDir := orient(m)
			if v, ok := idx[p95.Key{Iface: m.InterfaceID, Dir: p95.DirIn}][s.TS]; ok {
				s.add(inDir, v)
			} else {
				s.miss(inDir)
			}
			if v, ok := idx[p95.Key{Iface: m.InterfaceID, Dir: p95.DirOut}][s.TS]; ok {
				s.add(outDir, v)
			} else {
				s.miss(outDir)
			}
		}
		out = append(out, s)
	}
	return out
}

func (s *slot) add(dir string, v float64) {
	if dir == p95.DirIn {
		s.In, s.AnyIn = s.In+v, true
		return
	}
	s.Out, s.AnyOut = s.Out+v, true
}

func (s *slot) miss(dir string) {
	if dir == p95.DirIn {
		s.FullIn = false
		return
	}
	s.FullOut = false
}