Started down a different path; using a circular buffer instead.

After talks on #go-nuts, it seems as though I should look into using something
like the following:

https://github.com/cespare/goproc/tree/master/nwstat

And this makes sense. I have trimmed out the old tests and rearranged some code
here.

bandwidth.go

@@ -3,9 +3,9 @@
 package bandwidth
 
 import (
-	"container/list"
 	"errors"
-	"fmt"
+	"log"
+	"sort"
 	"time"
 )
 
@@ -27,17 +27,26 @@ type Bandwidth struct {
 	rxSnap []float64
 	txSnap []float64
 	dt     time.Duration
-	rxstream *stream
+
-	txstream *stream
+	curRx int
+	curTx int
+
+	rxstream []int
+	txstream []int
+
+	timeI int
+	max   int
 }
 
 // NewBandwidth Returns a populated and ready to launch Bandwidth. seconds is
 // a slice of seconds on which to report (e.g. 1, 10, 60 seconds). dt is how
 // often the values used to send to Rx and Tx are updated.
-func NewBandwidth(seconds []int, dt time.Duration) (*Bandwidth, error) {
+func NewBandwidth(dts []int, dt time.Duration) (*Bandwidth, error) {
-	if len(seconds) < 1 {
+	if len(dts) < 1 {
 		return nil, errors.New("must specify at least one interval lenght")
 	}
+	sort.Ints(dts)
+	max := dts[len(dts)-1]
 	r := &Bandwidth{
 		AddRx:    make(chan int, 1024),
 		AddTx:    make(chan int, 1024),
@@ -45,8 +54,9 @@ func NewBandwidth(seconds []int, dt time.Duration) (*Bandwidth, error) {
 		Tx:       make(chan []float64),
 		dt:       dt,
 		Quit:     make(chan interface{}),
-		rxstream: newStream(seconds),
+		rxstream: make([]int, max),
-		txstream: newStream(seconds),
+		txstream: make([]int, max),
+		max:      max,
 	}
 	return r, nil
 }
@@ -59,14 +69,17 @@ outer:
 	for {
 		select {
 		case <-t.C:
-			bw.rxSnap = bw.rxstream.averages()
+			bw.rxSnap = bw.averages(bw.rxstream)
-			bw.txSnap = bw.txstream.averages()
+			bw.txSnap = bw.averages(bw.txstream)
+			bw.curTx = 0
+			bw.curRx = 0
+			bw.timeI += 1
 		case bw.Rx <- bw.rxSnap:
 		case bw.Tx <- bw.txSnap:
 		case s := <-bw.AddRx:
-			bw.rxstream.add(datum{float64(s), time.Now()})
+			bw.curTx += s
 		case s := <-bw.AddTx:
-			bw.txstream.add(datum{float64(s), time.Now()})
+			bw.curRx += s
 		case <-bw.Quit:
 			break outer
 		}
@@ -77,86 +90,9 @@ outer:
 	close(bw.Tx)
 }
 
-// datum stores both a piece of info, plus the time at which that info was
+func (bw *Bandwidth) averages(state []int) []float64 {
-// collected.
+	for i := 0; i < bw.max; i++ {
-type datum struct {
+		log.Println(bw.timeI + i)
-	value float64
+	}
-	at    time.Time
+	return nil
-}
-
-func (d datum) String() string {
-	r := struct {
-		value string
-		at    string
-	}{
-		value: fmt.Sprintf("%04f", d.value),
-		at:    fmt.Sprintf("%s", d.at),
-	}
-	return fmt.Sprintf("%+v", r)
-}
-
-// stream manages a list of datum, and prunes itself on add
-type stream struct {
-	data    *list.List
-	extents []time.Duration
-	max     time.Duration
-}
-
-func newStream(seconds []int) *stream {
-	extents := []time.Duration{}
-	for _, s := range seconds {
-		extents = append(extents, time.Duration(-s)*time.Second)
-
-	}
-	max := extents[len(extents)-1]
-	return &stream{
-		data:    list.New(),
-		extents: extents,
-		max:     max,
-	}
-}
-
-func (s *stream) add(v datum) {
-	s.data.PushBack(v)
-}
-
-func (s *stream) averages() []float64 {
-	var limit time.Time
-	total := 0.0
-	totals := []float64{}
-
-	if s.data.Back() == nil {
-		return totals
-	}
-
-	now := time.Now()
-	cutoff := now.Add(s.max)
-	for e := s.data.Front(); e != nil; e = e.Next() {
-		cur := e.Value.(datum).at
-		if cur.Before(cutoff) {
-			s.data.Remove(e)
-		} else {
-			break
-		}
-	}
-
-	e := s.data.Back()
-
-	for _, extent := range s.extents {
-		limit = now.Add(extent)
-		for ; e != nil; e = e.Prev() {
-			if e.Prev() == nil {
-				break
-			}
-			next := e.Prev().Value.(datum)
-			if next.at.Before(limit) {
-				break
-			}
-			cur := e.Value.(datum)
-			total += cur.value
-		}
-		totals = append(totals, total/float64(-int(extent/time.Second)))
-	}
-
-	return totals
 }

bandwidth_test.go

@@ -10,35 +10,6 @@ func init() {
 	log.SetFlags(log.Ldate | log.Ltime | log.Lshortfile)
 }
 
-func general(t *testing.T) {
-	bw, err := NewBandwidth([]int{1, 10, 60}, 100*time.Millisecond)
-	if err != nil {
-		t.Error(err)
-	}
-	go bw.Run()
-	bw.AddRx <- 10
-	bw.AddTx <- 10
-	time.Sleep(1 * time.Second)
-	log.Printf("%+v", <-bw.Rx)
-	log.Printf("%+v", <-bw.Tx)
-	for i := 0; i < 10; i++ {
-		bw.AddRx <- (10 * i)
-		bw.AddRx <- (10 * i)
-		time.Sleep(500 * time.Millisecond)
-		log.Printf("%+v", <-bw.Rx)
-		log.Printf("%+v", <-bw.Tx)
-	}
-	log.Printf("%+v", <-bw.Rx)
-	log.Printf("%+v", <-bw.Tx)
-	time.Sleep(10 * time.Second)
-	log.Printf("%+v", <-bw.Rx)
-	log.Printf("%+v", <-bw.Tx)
-	close(bw.Quit)
-	time.Sleep(100 * time.Millisecond)
-	log.Printf("%+v", <-bw.Rx)
-	log.Printf("%+v", <-bw.Tx)
-}
-
 func validate(t *testing.T, actual, expected []float64) {
 	if len(actual) != len(expected) {
 		t.Errorf("len is not same: %d expected %d", len(actual), len(expected))
@@ -50,64 +21,14 @@ func validate(t *testing.T, actual, expected []float64) {
 	}
 }
 
-func TestOncePerSecond(t *testing.T) {
-	bw, err := NewBandwidth([]int{1, 10, 60}, 100*time.Millisecond)
-	if err != nil {
-		t.Error(err)
-	}
-	bw.rxstream = newStream([]int{1, 10, 60})
-	var i int64 = 0
-	for ; i < 1000; i++ {
-		d := datum{
-			value: 1.0,
-			at:    time.Unix(1234567890+i, 0),
-		}
-		bw.rxstream.add(d)
-	}
-	validate(t, bw.rxstream.averages(), []float64{1.0, 1.0, 1.0})
-}
-
-func TestOneOverManySeconds(t *testing.T) {
-	bw, err := NewBandwidth([]int{1, 10, 60}, 100*time.Millisecond)
-	if err != nil {
-		t.Error(err)
-	}
-	bw.rxstream = newStream([]int{1, 10, 60})
-	var i int64 = 0
-	for ; i < 1000; i++ {
-		d := datum{
-			value: 1.0,
-			at:    time.Unix(1234567890+i*2, 0),
-		}
-		bw.rxstream.add(d)
-	}
-	validate(t, bw.rxstream.averages(), []float64{0.0, 0.5, 0.5})
-}
-
-func TestManyPerSecond(t *testing.T) {
-	bw, err := NewBandwidth([]int{1, 10, 60}, 100*time.Millisecond)
-	if err != nil {
-		t.Error(err)
-	}
-	bw.rxstream = newStream([]int{1, 10, 60})
-	var i int64 = 0
-	for ; i < 10000; i++ {
-		d := datum{
-			value: 1.0,
-			at:    time.Unix(1234567890, i*10000000),
-		}
-		bw.rxstream.add(d)
-	}
-	validate(t, bw.rxstream.averages(), []float64{100.0, 100.0, 100.0})
-}
-
 func TestEmpty(t *testing.T) {
 	bw, err := NewBandwidth([]int{1, 10, 60}, 100*time.Millisecond)
 	if err != nil {
 		t.Error(err)
 	}
-	bw.rxstream = newStream([]int{1, 10, 60})
+	go bw.Run()
-	validate(t, bw.rxstream.averages(), []float64{})
+	bw.rxstream = []int{1, 10, 60}
+	validate(t, <-bw.Rx, []float64{})
 }
 
 func TestEmptySeconds(t *testing.T) {
@@ -116,3 +37,8 @@ func TestEmptySeconds(t *testing.T) {
 		t.Error(err)
 	}
 }
+
+func TestA(t *testing.T) {
+	bw, _ := NewBandwidth([]int{1, 10, 30}, 1*time.Second)
+	log.Printf("%+v", bw)
+}