Add late packets metric (#22)

* Add late packets metric

* Rise golang to 1.14

.travis.yml

@@ -16,7 +16,7 @@ addons:
 language: go
 
 go:
-  - 1.11.1
+  - 1.14
 
 script:
 - mkdir -p $HOME/gopath/src/github.com/exaring/

pkg/prober/collector.go

@@ -2,6 +2,7 @@ package prober
 
 import (
 	"strings"
+	"sync/atomic"
 	"time"
 
 	"github.com/exaring/matroschka-prober/pkg/measurement"
@@ -31,6 +32,7 @@ func (p *Prober) Collect(ch chan<- prometheus.Metric) {
 	p.collectRTTMin(ch, m)
 	p.collectRTTMax(ch, m)
 	p.collectRTTAvg(ch, m)
+	p.collectLatePackets(ch, m)
 }
 
 func (p *Prober) labels() []string {
@@ -94,6 +96,12 @@ func (p *Prober) collectRTTAvg(ch chan<- prometheus.Metric, m *measurement.Measu
 	ch <- prometheus.MustNewConstMetric(desc, prometheus.GaugeValue, v, p.labelValues()...)
 }
 
+func (p *Prober) collectLatePackets(ch chan<- prometheus.Metric, m *measurement.Measurement) {
+	desc := prometheus.NewDesc(metricPrefix+"late_packets_total", "Timedout but received packets", p.labels(), nil)
+	n := atomic.LoadUint64(&p.latePackets)
+	ch <- prometheus.MustNewConstMetric(desc, prometheus.CounterValue, float64(n), p.labelValues()...)
+}
+
 func (p *Prober) lastFinishedMeasurement() int64 {
 	measurementLengthNS := int64(p.cfg.MeasurementLengthMS) * int64(time.Millisecond)
 	timeoutNS := int64(p.cfg.TimeoutMS) * int64(time.Millisecond)

pkg/prober/prober.go

@@ -28,6 +28,7 @@ type Prober struct {
 	transitProbes  *transitProbes // Keeps track of in-flight packets
 	udpConn        udpSocket      // Used to receive returning packets
 	measurements   *measurement.MeasurementsDB
+	latePackets    uint64
 }
 
 // Config is the configuration of a prober

pkg/prober/receiver.go

@@ -42,6 +42,7 @@ func (p *Prober) receiver() {
 		rtt := now - pkt.Ts
 		if p.timedOut(rtt) {
 			// Probe arrived late. rttTimoutChecker() will clean up after it. So we ignore it from here on
+			atomic.AddUint64(&p.latePackets, 1)
 			continue
 		}