Add new experimental metrics (#4)

pkg/bitrate/bitrate.go

@@ -0,0 +1,106 @@
+package bitrate
+
+import (
+	"time"
+)
+
+// Bitrate allows calculating bitrates for a set of network interfaces.
+// This implementation is not thread-safe.
+type Bitrate struct {
+	measures                map[string]*measure
+	minDelayBetweenMeasures time.Duration
+}
+
+// New returns a new bitrate measurer.
+func New(minDelayBetweenMeasures time.Duration) *Bitrate {
+	return &Bitrate{
+		measures:                make(map[string]*measure),
+		minDelayBetweenMeasures: minDelayBetweenMeasures,
+	}
+}
+
+// mesure saves the counter values at a specific point in time.
+type measure struct {
+	Counters
+	Last time.Time
+}
+
+// Counters contain Tx and Rx counters for a network interface.
+type Counters struct {
+	Tx, Rx uint64
+}
+
+// Swap swaps Tx and Rx counters.
+func (c *Counters) Swap() {
+	c.Rx, c.Tx = c.Tx, c.Rx
+}
+
+// Bitrates for Tx and Rx.
+type Bitrates struct {
+	// Tx bitrate, can be nil if not available.
+	Tx *BitrateSpec
+	// Rx bitrate, can be nil if not available.
+	Rx *BitrateSpec
+}
+
+// BitrateSpec contains the value of the bitrate
+type BitrateSpec struct {
+	// Value of the bitrate (in Mbit/s). Will be 0 if Reset is true.
+	Value float64
+	// Reset is true when the counter was reset.
+	Reset bool
+}
+
+// ShouldMeasure returns true if a measure should be done.
+func (b *Bitrate) ShouldMeasure(name string) bool {
+	last, ok := b.measures[name]
+	if !ok {
+		return true
+	}
+
+	return time.Now().Sub(last.Last) > b.minDelayBetweenMeasures
+}
+
+// Measure saves the current measure and returns the current RX/TX bitrates.
+func (b *Bitrate) Measure(name string, current *Counters) *Bitrates {
+	br := &Bitrates{}
+
+	last, ok := b.measures[name]
+
+	// Only calculate bitrates if there is a previous measure.
+	if ok && !last.Last.IsZero() {
+		elapsed := time.Now().Sub(last.Last)
+
+		if elapsed.Seconds() > 0 {
+			diff := current.Rx - last.Rx
+			if diff >= 0 {
+				br.Rx = &BitrateSpec{
+					Value: BytesPerSecToMbits(float64(diff) / elapsed.Seconds()),
+				}
+			} else {
+				br.Rx = &BitrateSpec{
+					Reset: true,
+				}
+			}
+
+			diff = current.Tx - last.Tx
+			if diff >= 0 {
+				br.Tx = &BitrateSpec{
+					Value: BytesPerSecToMbits(float64(diff) / elapsed.Seconds()),
+				}
+			} else {
+				br.Tx = &BitrateSpec{
+					Reset: true,
+				}
+			}
+		}
+	}
+
+	// Save this measure as the latest.
+	b.measures[name] = &measure{
+		Counters: *current,
+		Last:     time.Now(),
+	}
+
+	return br
+}

pkg/bitrate/conversion.go

@@ -0,0 +1,11 @@
+package bitrate
+
+// BitsPer30SecsToMbits converts bits/30secs to Mbit/s.
+func BitsPer30SecsToMbits(v int) float64 {
+	return float64(v) / 30000000
+}
+
+// BytesPerSecToMbits converts B/s to Mbit/s.
+func BytesPerSecToMbits(bytes float64) float64 {
+	return bytes * 8 / 1000000
+}