squash! Updated structs and tests.

squash! Updated structs and tests.

Updated structs and tests.

Signed-off-by: Frank Davidson <davidfr@americas.manulife.net>
Signed-off-by: Frank Davidson <ffdavidson@gmail.com>
Signed-off-by: Frank Davidson <frank_davidson@manulife.com>

bridge_test.go

@@ -14,12 +14,20 @@
 package main
 
 import (
+	"fmt"
+	"net"
 	"reflect"
 	"testing"
+	"time"
 
 	"github.com/go-kit/kit/log"
+	"github.com/prometheus/client_golang/prometheus"
+	dto "github.com/prometheus/client_model/go"
+	"github.com/prometheus/statsd_exporter/pkg/clock"
 	"github.com/prometheus/statsd_exporter/pkg/event"
+	"github.com/prometheus/statsd_exporter/pkg/exporter"
 	"github.com/prometheus/statsd_exporter/pkg/listener"
+	"github.com/prometheus/statsd_exporter/pkg/mapper"
 )
 
 func TestHandlePacket(t *testing.T) {
@@ -417,11 +425,35 @@ func TestHandlePacket(t *testing.T) {
 		},
 	}
 
-	for k, l := range []statsDPacketHandler{&listener.StatsDUDPListener{nil, nil, log.NewNopLogger()}, &mockStatsDTCPListener{listener.StatsDTCPListener{nil, nil, log.NewNopLogger()}, log.NewNopLogger()}} {
+	for k, l := range []statsDPacketHandler{&listener.StatsDUDPListener{
+		Conn:            nil,
+		EventHandler:    nil,
+		Logger:          log.NewNopLogger(),
+		UDPPackets:      udpPackets,
+		LinesReceived:   linesReceived,
+		EventsFlushed:   eventsFlushed,
+		SampleErrors:    *sampleErrors,
+		SamplesReceived: samplesReceived,
+		TagErrors:       tagErrors,
+		TagsReceived:    tagsReceived,
+	}, &mockStatsDTCPListener{listener.StatsDTCPListener{
+		Conn:            nil,
+		EventHandler:    nil,
+		Logger:          log.NewNopLogger(),
+		LinesReceived:   linesReceived,
+		EventsFlushed:   eventsFlushed,
+		SampleErrors:    *sampleErrors,
+		SamplesReceived: samplesReceived,
+		TagErrors:       tagErrors,
+		TagsReceived:    tagsReceived,
+		TCPConnections:  tcpConnections,
+		TCPErrors:       tcpErrors,
+		TCPLineTooLong:  tcpLineTooLong,
+	}, log.NewNopLogger()}} {
 		events := make(chan event.Events, 32)
 		l.SetEventHandler(&event.UnbufferedEventHandler{C: events})
 		for i, scenario := range scenarios {
-			l.HandlePacket([]byte(scenario.in), udpPackets, linesReceived, eventsFlushed, *sampleErrors, samplesReceived, tagErrors, tagsReceived)
+			l.HandlePacket([]byte(scenario.in))
 
 			le := len(events)
 			// Flatten actual events.
@@ -442,3 +474,225 @@ func TestHandlePacket(t *testing.T) {
 		}
 	}
 }
+
+type statsDPacketHandler interface {
+	HandlePacket(packet []byte)
+	SetEventHandler(eh event.EventHandler)
+}
+
+type mockStatsDTCPListener struct {
+	listener.StatsDTCPListener
+	log.Logger
+}
+
+func (ml *mockStatsDTCPListener) HandlePacket(packet []byte) {
+	// Forcing IPv4 because the TravisCI build environment does not have IPv6
+	// addresses.
+	lc, err := net.ListenTCP("tcp4", nil)
+	if err != nil {
+		panic(fmt.Sprintf("mockStatsDTCPListener: listen failed: %v", err))
+	}
+
+	defer lc.Close()
+
+	go func() {
+		cc, err := net.DialTCP("tcp", nil, lc.Addr().(*net.TCPAddr))
+		if err != nil {
+			panic(fmt.Sprintf("mockStatsDTCPListener: dial failed: %v", err))
+		}
+
+		defer cc.Close()
+
+		n, err := cc.Write(packet)
+		if err != nil || n != len(packet) {
+			panic(fmt.Sprintf("mockStatsDTCPListener: write failed: %v,%d", err, n))
+		}
+	}()
+
+	sc, err := lc.AcceptTCP()
+	if err != nil {
+		panic(fmt.Sprintf("mockStatsDTCPListener: accept failed: %v", err))
+	}
+	ml.HandleConn(sc)
+}
+
+// TestTtlExpiration validates expiration of time series.
+// foobar metric without mapping should expire with default ttl of 1s
+// bazqux metric should expire with ttl of 2s
+func TestTtlExpiration(t *testing.T) {
+	// Mock a time.NewTicker
+	tickerCh := make(chan time.Time)
+	clock.ClockInstance = &clock.Clock{
+		TickerCh: tickerCh,
+	}
+
+	config := `
+defaults:
+  ttl: 1s
+mappings:
+- match: bazqux.*
+  name: bazqux
+  ttl: 2s
+`
+	// Create mapper from config and start an Exporter with a synchronous channel
+	testMapper := &mapper.MetricMapper{}
+	err := testMapper.InitFromYAMLString(config, 0)
+	if err != nil {
+		t.Fatalf("Config load error: %s %s", config, err)
+	}
+	events := make(chan event.Events)
+	defer close(events)
+	go func() {
+		ex := exporter.NewExporter(testMapper, log.NewNopLogger(), eventsActions, eventsUnmapped, errorEventStats, eventStats, conflictingEventStats, metricsCount)
+		ex.Listen(events)
+	}()
+
+	ev := event.Events{
+		// event with default ttl = 1s
+		&event.GaugeEvent{
+			GMetricName: "foobar",
+			GValue:      200,
+		},
+		// event with ttl = 2s from a mapping
+		&event.TimerEvent{
+			TMetricName: "bazqux.main",
+			TValue:      42000,
+		},
+	}
+
+	var metrics []*dto.MetricFamily
+	var foobarValue *float64
+	var bazquxValue *float64
+
+	// Step 1. Send events with statsd metrics.
+	// Send empty Events to wait for events are handled.
+	// saveLabelValues will use fake instant as a lastRegisteredAt time.
+	clock.ClockInstance.Instant = time.Unix(0, 0)
+	events <- ev
+	events <- event.Events{}
+
+	// Check values
+	metrics, err = prometheus.DefaultGatherer.Gather()
+	if err != nil {
+		t.Fatal("Gather should not fail")
+	}
+	foobarValue = getFloat64(metrics, "foobar", prometheus.Labels{})
+	bazquxValue = getFloat64(metrics, "bazqux", prometheus.Labels{})
+	if foobarValue == nil || bazquxValue == nil {
+		t.Fatalf("Gauge `foobar` and Summary `bazqux` should be gathered")
+	}
+	if *foobarValue != 200 {
+		t.Fatalf("Gauge `foobar` observation %f is not expected. Should be 200", *foobarValue)
+	}
+	if *bazquxValue != 42 {
+		t.Fatalf("Summary `bazqux` observation %f is not expected. Should be 42", *bazquxValue)
+	}
+
+	// Step 2. Increase Instant to emulate metrics expiration after 1s
+	clock.ClockInstance.Instant = time.Unix(1, 10)
+	clock.ClockInstance.TickerCh <- time.Unix(0, 0)
+	events <- event.Events{}
+
+	// Check values
+	metrics, err = prometheus.DefaultGatherer.Gather()
+	if err != nil {
+		t.Fatal("Gather should not fail")
+	}
+	foobarValue = getFloat64(metrics, "foobar", prometheus.Labels{})
+	bazquxValue = getFloat64(metrics, "bazqux", prometheus.Labels{})
+	if foobarValue != nil {
+		t.Fatalf("Gauge `foobar` should be expired")
+	}
+	if bazquxValue == nil {
+		t.Fatalf("Summary `bazqux` should be gathered")
+	}
+	if *bazquxValue != 42 {
+		t.Fatalf("Summary `bazqux` observation %f is not expected. Should be 42", *bazquxValue)
+	}
+
+	// Step 3. Increase Instant to emulate metrics expiration after 2s
+	clock.ClockInstance.Instant = time.Unix(2, 200)
+	clock.ClockInstance.TickerCh <- time.Unix(0, 0)
+	events <- event.Events{}
+
+	// Check values
+	metrics, err = prometheus.DefaultGatherer.Gather()
+	if err != nil {
+		t.Fatal("Gather should not fail")
+	}
+	foobarValue = getFloat64(metrics, "foobar", prometheus.Labels{})
+	bazquxValue = getFloat64(metrics, "bazqux", prometheus.Labels{})
+	if bazquxValue != nil {
+		t.Fatalf("Summary `bazqux` should be expired")
+	}
+	if foobarValue != nil {
+		t.Fatalf("Gauge `foobar` should not be gathered after expiration")
+	}
+}
+
+// getFloat64 search for metric by name in array of MetricFamily and then search a value by labels.
+// Method returns a value or nil if metric is not found.
+func getFloat64(metrics []*dto.MetricFamily, name string, labels prometheus.Labels) *float64 {
+	var metricFamily *dto.MetricFamily
+	for _, m := range metrics {
+		if *m.Name == name {
+			metricFamily = m
+			break
+		}
+	}
+	if metricFamily == nil {
+		return nil
+	}
+
+	var metric *dto.Metric
+	labelStr := fmt.Sprintf("%v", labels)
+	for _, m := range metricFamily.Metric {
+		l := labelPairsAsLabels(m.GetLabel())
+		ls := fmt.Sprintf("%v", l)
+		if labelStr == ls {
+			metric = m
+			break
+		}
+	}
+	if metric == nil {
+		return nil
+	}
+
+	var value float64
+	if metric.Gauge != nil {
+		value = metric.Gauge.GetValue()
+		return &value
+	}
+	if metric.Counter != nil {
+		value = metric.Counter.GetValue()
+		return &value
+	}
+	if metric.Histogram != nil {
+		value = metric.Histogram.GetSampleSum()
+		return &value
+	}
+	if metric.Summary != nil {
+		value = metric.Summary.GetSampleSum()
+		return &value
+	}
+	if metric.Untyped != nil {
+		value = metric.Untyped.GetValue()
+		return &value
+	}
+	panic(fmt.Errorf("collected a non-gauge/counter/histogram/summary/untyped metric: %s", metric))
+}
+
+func labelPairsAsLabels(pairs []*dto.LabelPair) (labels prometheus.Labels) {
+	labels = prometheus.Labels{}
+	for _, pair := range pairs {
+		if pair.Name == nil {
+			continue
+		}
+		value := ""
+		if pair.Value != nil {
+			value = *pair.Value
+		}
+		labels[*pair.Name] = value
+	}
+	return
+}

exporter_benchmark_test.go

@@ -50,7 +50,7 @@ func benchmarkUDPListener(times int, b *testing.B) {
 
 		for i := 0; i < times; i++ {
 			for _, line := range bytesInput {
-				l.HandlePacket([]byte(line), udpPackets, linesReceived, eventsFlushed, *sampleErrors, samplesReceived, tagErrors, tagsReceived)
+				l.HandlePacket([]byte(line))
 			}
 		}
 	}
@@ -142,7 +142,7 @@ mappings:
 		b.Fatalf("Config load error: %s %s", config, err)
 	}
 
-	ex := exporter.NewExporter(testMapper, log.NewNopLogger())
+	ex := exporter.NewExporter(testMapper, log.NewNopLogger(), eventsActions, eventsUnmapped, errorEventStats, eventStats, conflictingEventStats, metricsCount)
 	for i := 0; i < b.N; i++ {
 		ec := make(chan event.Events, 1000)
 		go func() {
@@ -152,6 +152,6 @@ mappings:
 			close(ec)
 		}()
 
-		ex.Listen(ec, eventsActions, eventsUnmapped, errorEventStats, eventStats, conflictingEventStats, metricsCount)
+		ex.Listen(ec)
 	}
 }

main.go

@@ -32,11 +32,11 @@ import (
 	"github.com/prometheus/common/version"
 	"gopkg.in/alecthomas/kingpin.v2"
 
+	"github.com/prometheus/statsd_exporter/pkg/address"
 	"github.com/prometheus/statsd_exporter/pkg/event"
 	"github.com/prometheus/statsd_exporter/pkg/exporter"
 	"github.com/prometheus/statsd_exporter/pkg/listener"
 	"github.com/prometheus/statsd_exporter/pkg/mapper"
-	"github.com/prometheus/statsd_exporter/pkg/util"
 )
 
 const (
@@ -58,10 +58,11 @@ var (
 			Help: "Number of times events were flushed to exporter",
 		},
 	)
-	eventsUnmapped = prometheus.NewCounter(prometheus.CounterOpts{
+	eventsUnmapped = prometheus.NewCounter(
-		Name: "statsd_exporter_events_unmapped_total",
+		prometheus.CounterOpts{
-		Help: "The total number of StatsD events no mapping was found for.",
+			Name: "statsd_exporter_events_unmapped_total",
-	})
+			Help: "The total number of StatsD events no mapping was found for.",
+		})
 	udpPackets = prometheus.NewCounter(
 		prometheus.CounterOpts{
 			Name: "statsd_exporter_udp_packets_total",
@@ -294,7 +295,7 @@ func main() {
 	eventQueue := event.NewEventQueue(events, *eventFlushThreshold, *eventFlushInterval, eventsFlushed)
 
 	if *statsdListenUDP != "" {
-		udpListenAddr, err := util.UDPAddrFromString(*statsdListenUDP)
+		udpListenAddr, err := address.UDPAddrFromString(*statsdListenUDP)
 		if err != nil {
 			level.Error(logger).Log("msg", "invalid UDP listen address", "address", *statsdListenUDP, "error", err)
 			os.Exit(1)
@@ -313,12 +314,24 @@ func main() {
 			}
 		}
 
-		ul := &listener.StatsDUDPListener{Conn: uconn, EventHandler: eventQueue, Logger: logger}
+		ul := &listener.StatsDUDPListener{
-		go ul.Listen(udpPackets, linesReceived, eventsFlushed, *sampleErrors, samplesReceived, tagErrors, tagsReceived)
+			Conn:            uconn,
+			EventHandler:    eventQueue,
+			Logger:          logger,
+			UDPPackets:      udpPackets,
+			LinesReceived:   linesReceived,
+			EventsFlushed:   eventsFlushed,
+			SampleErrors:    *sampleErrors,
+			SamplesReceived: samplesReceived,
+			TagErrors:       tagErrors,
+			TagsReceived:    tagsReceived,
+		}
+
+		go ul.Listen()
 	}
 
 	if *statsdListenTCP != "" {
-		tcpListenAddr, err := util.TCPAddrFromString(*statsdListenTCP)
+		tcpListenAddr, err := address.TCPAddrFromString(*statsdListenTCP)
 		if err != nil {
 			level.Error(logger).Log("msg", "invalid TCP listen address", "address", *statsdListenUDP, "error", err)
 			os.Exit(1)
@@ -330,8 +343,22 @@ func main() {
 		}
 		defer tconn.Close()
 
-		tl := &listener.StatsDTCPListener{Conn: tconn, EventHandler: eventQueue, Logger: logger}
+		tl := &listener.StatsDTCPListener{
-		go tl.Listen(linesReceived, eventsFlushed, tcpConnections, tcpErrors, tcpLineTooLong, *sampleErrors, samplesReceived, tagErrors, tagsReceived)
+			Conn:            tconn,
+			EventHandler:    eventQueue,
+			Logger:          logger,
+			LinesReceived:   linesReceived,
+			EventsFlushed:   eventsFlushed,
+			SampleErrors:    *sampleErrors,
+			SamplesReceived: samplesReceived,
+			TagErrors:       tagErrors,
+			TagsReceived:    tagsReceived,
+			TCPConnections:  tcpConnections,
+			TCPErrors:       tcpErrors,
+			TCPLineTooLong:  tcpLineTooLong,
+		}
+
+		go tl.Listen()
 	}
 
 	if *statsdListenUnixgram != "" {
@@ -360,7 +387,7 @@ func main() {
 		}
 
 		ul := &listener.StatsDUnixgramListener{Conn: uxgconn, EventHandler: eventQueue, Logger: logger}
-		go ul.Listen(unixgramPackets, linesReceived, eventsFlushed, *sampleErrors, samplesReceived, tagErrors, tagsReceived)
+		go ul.Listen()
 
 		// if it's an abstract unix domain socket, it won't exist on fs
 		// so we can't chmod it either
@@ -403,12 +430,12 @@ func main() {
 
 	go configReloader(*mappingConfig, mapper, *cacheSize, logger, cacheOption)
 
-	exporter := exporter.NewExporter(mapper, logger)
+	exporter := exporter.NewExporter(mapper, logger, eventsActions, eventsUnmapped, errorEventStats, eventStats, conflictingEventStats, metricsCount)
 
 	signals := make(chan os.Signal, 1)
 	signal.Notify(signals, os.Interrupt, syscall.SIGTERM)
 
-	go exporter.Listen(events, eventsActions, eventsUnmapped, errorEventStats, eventStats, conflictingEventStats, metricsCount)
+	go exporter.Listen(events)
 
 	<-signals
 }

pkg/address/address.go

@@ -11,7 +11,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package util
+package address
 
 import (
 	"fmt"

pkg/event/event.go

@@ -69,12 +69,14 @@ type EventQueue struct {
 	C              chan Events
 	q              Events
 	m              sync.Mutex
-	flushThreshold int
 	flushTicker    *time.Ticker
+	flushThreshold int
+	flushInterval  time.Duration
+	eventsFlushed  prometheus.Counter
 }
 
 type EventHandler interface {
-	Queue(event Events, eventsFlushed *prometheus.Counter)
+	Queue(event Events)
 }
 
 func NewEventQueue(c chan Events, flushThreshold int, flushInterval time.Duration, eventsFlushed prometheus.Counter) *EventQueue {
@@ -84,38 +86,39 @@ func NewEventQueue(c chan Events, flushThreshold int, flushInterval time.Duratio
 		flushThreshold: flushThreshold,
 		flushTicker:    ticker,
 		q:              make([]Event, 0, flushThreshold),
+		eventsFlushed:  eventsFlushed,
 	}
 	go func() {
 		for {
 			<-ticker.C
-			eq.Flush(eventsFlushed)
+			eq.Flush()
 		}
 	}()
 	return eq
 }
 
-func (eq *EventQueue) Queue(events Events, eventsFlushed *prometheus.Counter) {
+func (eq *EventQueue) Queue(events Events) {
 	eq.m.Lock()
 	defer eq.m.Unlock()
 
 	for _, e := range events {
 		eq.q = append(eq.q, e)
 		if len(eq.q) >= eq.flushThreshold {
-			eq.FlushUnlocked(*eventsFlushed)
+			eq.FlushUnlocked()
 		}
 	}
 }
 
-func (eq *EventQueue) Flush(eventsFlushed prometheus.Counter) {
+func (eq *EventQueue) Flush() {
 	eq.m.Lock()
 	defer eq.m.Unlock()
-	eq.FlushUnlocked(eventsFlushed)
+	eq.FlushUnlocked()
 }
 
-func (eq *EventQueue) FlushUnlocked(eventsFlushed prometheus.Counter) {
+func (eq *EventQueue) FlushUnlocked() {
 	eq.C <- eq.q
 	eq.q = make([]Event, 0, cap(eq.q))
-	eventsFlushed.Inc()
+	eq.eventsFlushed.Inc()
 }
 
 func (eq *EventQueue) Len() int {
@@ -129,6 +132,6 @@ type UnbufferedEventHandler struct {
 	C chan Events
 }
 
-func (ueh *UnbufferedEventHandler) Queue(events Events, eventsFlushed *prometheus.Counter) {
+func (ueh *UnbufferedEventHandler) Queue(events Events) {
 	ueh.C <- events
 }

pkg/event/event_test.go

@@ -11,23 +11,30 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package main
+package event
 
 import (
 	"testing"
 	"time"
 
+	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/statsd_exporter/pkg/clock"
-	"github.com/prometheus/statsd_exporter/pkg/event"
+)
+
+var eventsFlushed = prometheus.NewCounter(
+	prometheus.CounterOpts{
+		Name: "statsd_exporter_event_queue_flushed_total",
+		Help: "Number of times events were flushed to exporter",
+	},
 )
 
 func TestEventThresholdFlush(t *testing.T) {
-	c := make(chan event.Events, 100)
+	c := make(chan Events, 100)
 	// We're not going to flush during this test, so the duration doesn't matter.
-	eq := event.NewEventQueue(c, 5, time.Second, eventsFlushed)
+	eq := NewEventQueue(c, 5, time.Second, eventsFlushed)
-	e := make(event.Events, 13)
+	e := make(Events, 13)
 	go func() {
-		eq.Queue(e, &eventsFlushed)
+		eq.Queue(e)
 	}()
 
 	batch := <-c
@@ -52,10 +59,10 @@ func TestEventIntervalFlush(t *testing.T) {
 	}
 	clock.ClockInstance.Instant = time.Unix(0, 0)
 
-	c := make(chan event.Events, 100)
+	c := make(chan Events, 100)
-	eq := event.NewEventQueue(c, 1000, time.Second*1000, eventsFlushed)
+	eq := NewEventQueue(c, 1000, time.Second*1000, eventsFlushed)
-	e := make(event.Events, 10)
+	e := make(Events, 10)
-	eq.Queue(e, &eventsFlushed)
+	eq.Queue(e)
 
 	if eq.Len() != 10 {
 		t.Fatal("Expected 10 events to be queued, but got", eq.Len())

pkg/exporter/exporter.go

@@ -32,15 +32,20 @@ const (
 )
 
 type Exporter struct {
-	Mapper   *mapper.MetricMapper
+	Mapper                *mapper.MetricMapper
-	Registry *registry.Registry
+	Registry              *registry.Registry
-	Logger   log.Logger
+	Logger                log.Logger
+	EventsActions         *prometheus.CounterVec
+	EventsUnmapped        prometheus.Counter
+	ErrorEventStats       *prometheus.CounterVec
+	EventStats            *prometheus.CounterVec
+	ConflictingEventStats *prometheus.CounterVec
+	MetricsCount          *prometheus.GaugeVec
 }
 
 // Listen handles all events sent to the given channel sequentially. It
 // terminates when the channel is closed.
-func (b *Exporter) Listen(e <-chan event.Events, eventsActions *prometheus.CounterVec, eventsUnmapped prometheus.Counter,
+func (b *Exporter) Listen(e <-chan event.Events) {
-	errorEventStats *prometheus.CounterVec, eventStats *prometheus.CounterVec, conflictingEventStats *prometheus.CounterVec, metricsCount *prometheus.GaugeVec) {
 
 	removeStaleMetricsTicker := clock.NewTicker(time.Second)
 
@@ -55,15 +60,14 @@ func (b *Exporter) Listen(e <-chan event.Events, eventsActions *prometheus.Count
 				return
 			}
 			for _, event := range events {
-				b.handleEvent(event, eventsActions, eventsUnmapped, errorEventStats, eventStats, conflictingEventStats, metricsCount)
+				b.handleEvent(event)
 			}
 		}
 	}
 }
 
 // handleEvent processes a single Event according to the configured mapping.
-func (b *Exporter) handleEvent(thisEvent event.Event, eventsActions *prometheus.CounterVec, eventsUnmapped prometheus.Counter,
+func (b *Exporter) handleEvent(thisEvent event.Event) {
-	errorEventStats *prometheus.CounterVec, eventStats *prometheus.CounterVec, conflictingEventStats *prometheus.CounterVec, metricsCount *prometheus.GaugeVec) {
 
 	mapping, labels, present := b.Mapper.GetMapping(thisEvent.MetricName(), thisEvent.MetricType())
 	if mapping == nil {
@@ -74,7 +78,7 @@ func (b *Exporter) handleEvent(thisEvent event.Event, eventsActions *prometheus.
 	}
 
 	if mapping.Action == mapper.ActionTypeDrop {
-		eventsActions.WithLabelValues("drop").Inc()
+		b.EventsActions.WithLabelValues("drop").Inc()
 		return
 	}
 
@@ -89,16 +93,16 @@ func (b *Exporter) handleEvent(thisEvent event.Event, eventsActions *prometheus.
 	if present {
 		if mapping.Name == "" {
 			level.Debug(b.Logger).Log("msg", "The mapping generates an empty metric name", "metric_name", thisEvent.MetricName(), "match", mapping.Match)
-			errorEventStats.WithLabelValues("empty_metric_name").Inc()
+			b.ErrorEventStats.WithLabelValues("empty_metric_name").Inc()
 			return
 		}
 		metricName = mapper.EscapeMetricName(mapping.Name)
 		for label, value := range labels {
 			prometheusLabels[label] = value
 		}
-		eventsActions.WithLabelValues(string(mapping.Action)).Inc()
+		b.EventsActions.WithLabelValues(string(mapping.Action)).Inc()
 	} else {
-		eventsUnmapped.Inc()
+		b.EventsUnmapped.Inc()
 		metricName = mapper.EscapeMetricName(thisEvent.MetricName())
 	}
 
@@ -108,21 +112,21 @@ func (b *Exporter) handleEvent(thisEvent event.Event, eventsActions *prometheus.
 		// will cause the exporter to panic. Instead we will warn and continue to the next event.
 		if thisEvent.Value() < 0.0 {
 			level.Debug(b.Logger).Log("msg", "counter must be non-negative value", "metric", metricName, "event_value", thisEvent.Value())
-			errorEventStats.WithLabelValues("illegal_negative_counter").Inc()
+			b.ErrorEventStats.WithLabelValues("illegal_negative_counter").Inc()
 			return
 		}
 
-		counter, err := b.Registry.GetCounter(metricName, prometheusLabels, help, mapping, metricsCount)
+		counter, err := b.Registry.GetCounter(metricName, prometheusLabels, help, mapping, b.MetricsCount)
 		if err == nil {
 			counter.Add(thisEvent.Value())
-			eventStats.WithLabelValues("counter").Inc()
+			b.EventStats.WithLabelValues("counter").Inc()
 		} else {
 			level.Debug(b.Logger).Log("msg", regErrF, "metric", metricName, "error", err)
-			conflictingEventStats.WithLabelValues("counter").Inc()
+			b.ConflictingEventStats.WithLabelValues("counter").Inc()
 		}
 
 	case *event.GaugeEvent:
-		gauge, err := b.Registry.GetGauge(metricName, prometheusLabels, help, mapping, metricsCount)
+		gauge, err := b.Registry.GetGauge(metricName, prometheusLabels, help, mapping, b.MetricsCount)
 
 		if err == nil {
 			if ev.GRelative {
@@ -130,10 +134,10 @@ func (b *Exporter) handleEvent(thisEvent event.Event, eventsActions *prometheus.
 			} else {
 				gauge.Set(thisEvent.Value())
 			}
-			eventStats.WithLabelValues("gauge").Inc()
+			b.EventStats.WithLabelValues("gauge").Inc()
 		} else {
 			level.Debug(b.Logger).Log("msg", regErrF, "metric", metricName, "error", err)
-			conflictingEventStats.WithLabelValues("gauge").Inc()
+			b.ConflictingEventStats.WithLabelValues("gauge").Inc()
 		}
 
 	case *event.TimerEvent:
@@ -147,23 +151,23 @@ func (b *Exporter) handleEvent(thisEvent event.Event, eventsActions *prometheus.
 
 		switch t {
 		case mapper.TimerTypeHistogram:
-			histogram, err := b.Registry.GetHistogram(metricName, prometheusLabels, help, mapping, metricsCount)
+			histogram, err := b.Registry.GetHistogram(metricName, prometheusLabels, help, mapping, b.MetricsCount)
 			if err == nil {
 				histogram.Observe(thisEvent.Value() / 1000) // prometheus presumes seconds, statsd millisecond
-				eventStats.WithLabelValues("timer").Inc()
+				b.EventStats.WithLabelValues("timer").Inc()
 			} else {
 				level.Debug(b.Logger).Log("msg", regErrF, "metric", metricName, "error", err)
-				conflictingEventStats.WithLabelValues("timer").Inc()
+				b.ConflictingEventStats.WithLabelValues("timer").Inc()
 			}
 
 		case mapper.TimerTypeDefault, mapper.TimerTypeSummary:
-			summary, err := b.Registry.GetSummary(metricName, prometheusLabels, help, mapping, metricsCount)
+			summary, err := b.Registry.GetSummary(metricName, prometheusLabels, help, mapping, b.MetricsCount)
 			if err == nil {
 				summary.Observe(thisEvent.Value() / 1000) // prometheus presumes seconds, statsd millisecond
-				eventStats.WithLabelValues("timer").Inc()
+				b.EventStats.WithLabelValues("timer").Inc()
 			} else {
 				level.Debug(b.Logger).Log("msg", regErrF, "metric", metricName, "error", err)
-				conflictingEventStats.WithLabelValues("timer").Inc()
+				b.ConflictingEventStats.WithLabelValues("timer").Inc()
 			}
 
 		default:
@@ -173,14 +177,20 @@ func (b *Exporter) handleEvent(thisEvent event.Event, eventsActions *prometheus.
 
 	default:
 		level.Debug(b.Logger).Log("msg", "Unsupported event type")
-		eventStats.WithLabelValues("illegal").Inc()
+		b.EventStats.WithLabelValues("illegal").Inc()
 	}
 }
 
-func NewExporter(mapper *mapper.MetricMapper, logger log.Logger) *Exporter {
+func NewExporter(mapper *mapper.MetricMapper, logger log.Logger, eventsActions *prometheus.CounterVec, eventsUnmapped prometheus.Counter, errorEventStats *prometheus.CounterVec, eventStats *prometheus.CounterVec, conflictingEventStats *prometheus.CounterVec, metricsCount *prometheus.GaugeVec) *Exporter {
 	return &Exporter{
-		Mapper:   mapper,
+		Mapper:                mapper,
-		Registry: registry.NewRegistry(mapper),
+		Registry:              registry.NewRegistry(mapper),
-		Logger:   logger,
+		Logger:                logger,
+		EventsActions:         eventsActions,
+		EventsUnmapped:        eventsUnmapped,
+		ErrorEventStats:       errorEventStats,
+		EventStats:            eventStats,
+		ConflictingEventStats: conflictingEventStats,
+		MetricsCount:          metricsCount,
 	}
 }

pkg/exporter/exporter_test.go

@@ -11,7 +11,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package main
+package exporter
 
 import (
 	"fmt"
@@ -25,13 +25,133 @@ import (
 
 	"github.com/prometheus/statsd_exporter/pkg/clock"
 	"github.com/prometheus/statsd_exporter/pkg/event"
-	"github.com/prometheus/statsd_exporter/pkg/exporter"
 	"github.com/prometheus/statsd_exporter/pkg/line"
 	"github.com/prometheus/statsd_exporter/pkg/listener"
 	"github.com/prometheus/statsd_exporter/pkg/mapper"
 	"github.com/prometheus/statsd_exporter/pkg/registry"
 )
 
+var (
+	eventStats = prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "statsd_exporter_events_total",
+			Help: "The total number of StatsD events seen.",
+		},
+		[]string{"type"},
+	)
+	eventsFlushed = prometheus.NewCounter(
+		prometheus.CounterOpts{
+			Name: "statsd_exporter_event_queue_flushed_total",
+			Help: "Number of times events were flushed to exporter",
+		},
+	)
+	eventsUnmapped = prometheus.NewCounter(
+		prometheus.CounterOpts{
+			Name: "statsd_exporter_events_unmapped_total",
+			Help: "The total number of StatsD events no mapping was found for.",
+		})
+	udpPackets = prometheus.NewCounter(
+		prometheus.CounterOpts{
+			Name: "statsd_exporter_udp_packets_total",
+			Help: "The total number of StatsD packets received over UDP.",
+		},
+	)
+	tcpConnections = prometheus.NewCounter(
+		prometheus.CounterOpts{
+			Name: "statsd_exporter_tcp_connections_total",
+			Help: "The total number of TCP connections handled.",
+		},
+	)
+	tcpErrors = prometheus.NewCounter(
+		prometheus.CounterOpts{
+			Name: "statsd_exporter_tcp_connection_errors_total",
+			Help: "The number of errors encountered reading from TCP.",
+		},
+	)
+	tcpLineTooLong = prometheus.NewCounter(
+		prometheus.CounterOpts{
+			Name: "statsd_exporter_tcp_too_long_lines_total",
+			Help: "The number of lines discarded due to being too long.",
+		},
+	)
+	unixgramPackets = prometheus.NewCounter(
+		prometheus.CounterOpts{
+			Name: "statsd_exporter_unixgram_packets_total",
+			Help: "The total number of StatsD packets received over Unixgram.",
+		},
+	)
+	linesReceived = prometheus.NewCounter(
+		prometheus.CounterOpts{
+			Name: "statsd_exporter_lines_total",
+			Help: "The total number of StatsD lines received.",
+		},
+	)
+	samplesReceived = prometheus.NewCounter(
+		prometheus.CounterOpts{
+			Name: "statsd_exporter_samples_total",
+			Help: "The total number of StatsD samples received.",
+		},
+	)
+	sampleErrors = prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "statsd_exporter_sample_errors_total",
+			Help: "The total number of errors parsing StatsD samples.",
+		},
+		[]string{"reason"},
+	)
+	tagsReceived = prometheus.NewCounter(
+		prometheus.CounterOpts{
+			Name: "statsd_exporter_tags_total",
+			Help: "The total number of DogStatsD tags processed.",
+		},
+	)
+	tagErrors = prometheus.NewCounter(
+		prometheus.CounterOpts{
+			Name: "statsd_exporter_tag_errors_total",
+			Help: "The number of errors parsing DogStatsD tags.",
+		},
+	)
+	configLoads = prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "statsd_exporter_config_reloads_total",
+			Help: "The number of configuration reloads.",
+		},
+		[]string{"outcome"},
+	)
+	mappingsCount = prometheus.NewGauge(prometheus.GaugeOpts{
+		Name: "statsd_exporter_loaded_mappings",
+		Help: "The current number of configured metric mappings.",
+	})
+	conflictingEventStats = prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "statsd_exporter_events_conflict_total",
+			Help: "The total number of StatsD events with conflicting names.",
+		},
+		[]string{"type"},
+	)
+	errorEventStats = prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "statsd_exporter_events_error_total",
+			Help: "The total number of StatsD events discarded due to errors.",
+		},
+		[]string{"reason"},
+	)
+	eventsActions = prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "statsd_exporter_events_actions_total",
+			Help: "The total number of StatsD events by action.",
+		},
+		[]string{"action"},
+	)
+	metricsCount = prometheus.NewGaugeVec(
+		prometheus.GaugeOpts{
+			Name: "statsd_exporter_metrics_total",
+			Help: "The total number of metrics.",
+		},
+		[]string{"type"},
+	)
+)
+
 // TestNegativeCounter validates when we send a negative
 // number to a counter that we no longer panic the Exporter Listener.
 func TestNegativeCounter(t *testing.T) {
@@ -64,8 +184,8 @@ func TestNegativeCounter(t *testing.T) {
 	testMapper := mapper.MetricMapper{}
 	testMapper.InitCache(0)
 
-	ex := exporter.NewExporter(&testMapper, log.NewNopLogger())
+	ex := NewExporter(&testMapper, log.NewNopLogger(), eventsActions, eventsUnmapped, errorEventStats, eventStats, conflictingEventStats, metricsCount)
-	ex.Listen(events, eventsActions, eventsUnmapped, errorEventStats, eventStats, conflictingEventStats, metricsCount)
+	ex.Listen(events)
 
 	updated := getTelemetryCounterValue(errorCounter)
 	if updated-prev != 1 {
@@ -145,8 +265,8 @@ mappings:
 		t.Fatalf("Config load error: %s %s", config, err)
 	}
 
-	ex := exporter.NewExporter(testMapper, log.NewNopLogger())
+	ex := NewExporter(testMapper, log.NewNopLogger(), eventsActions, eventsUnmapped, errorEventStats, eventStats, conflictingEventStats, metricsCount)
-	ex.Listen(events, eventsActions, eventsUnmapped, errorEventStats, eventStats, conflictingEventStats, metricsCount)
+	ex.Listen(events)
 
 	metrics, err := prometheus.DefaultGatherer.Gather()
 	if err != nil {
@@ -203,8 +323,8 @@ mappings:
 		t.Fatalf("Config load error: %s %s", config, err)
 	}
 
-	ex := exporter.NewExporter(testMapper, log.NewNopLogger())
+	ex := NewExporter(testMapper, log.NewNopLogger(), eventsActions, eventsUnmapped, errorEventStats, eventStats, conflictingEventStats, metricsCount)
-	ex.Listen(events, eventsActions, eventsUnmapped, errorEventStats, eventStats, conflictingEventStats, metricsCount)
+	ex.Listen(events)
 
 	metrics, err := prometheus.DefaultGatherer.Gather()
 	if err != nil {
@@ -418,8 +538,8 @@ mappings:
 				events <- s.in
 				close(events)
 			}()
-			ex := exporter.NewExporter(testMapper, log.NewNopLogger())
+			ex := NewExporter(testMapper, log.NewNopLogger(), eventsActions, eventsUnmapped, errorEventStats, eventStats, conflictingEventStats, metricsCount)
-			ex.Listen(events, eventsActions, eventsUnmapped, errorEventStats, eventStats, conflictingEventStats, metricsCount)
+			ex.Listen(events)
 
 			metrics, err := prometheus.DefaultGatherer.Gather()
 			if err != nil {
@@ -473,8 +593,8 @@ mappings:
 	errorCounter := errorEventStats.WithLabelValues("empty_metric_name")
 	prev := getTelemetryCounterValue(errorCounter)
 
-	ex := exporter.NewExporter(testMapper, log.NewNopLogger())
+	ex := NewExporter(testMapper, log.NewNopLogger(), eventsActions, eventsUnmapped, errorEventStats, eventStats, conflictingEventStats, metricsCount)
-	ex.Listen(events, eventsActions, eventsUnmapped, errorEventStats, eventStats, conflictingEventStats, metricsCount)
+	ex.Listen(events)
 
 	updated := getTelemetryCounterValue(errorCounter)
 	if updated-prev != 1 {
@@ -498,9 +618,33 @@ func TestInvalidUtf8InDatadogTagValue(t *testing.T) {
 	ueh := &event.UnbufferedEventHandler{C: events}
 
 	go func() {
-		for _, l := range []statsDPacketHandler{&listener.StatsDUDPListener{nil, nil, log.NewNopLogger()}, &mockStatsDTCPListener{listener.StatsDTCPListener{nil, nil, log.NewNopLogger()}, log.NewNopLogger()}} {
+		for _, l := range []statsDPacketHandler{&listener.StatsDUDPListener{
+			Conn:            nil,
+			EventHandler:    nil,
+			Logger:          log.NewNopLogger(),
+			UDPPackets:      udpPackets,
+			LinesReceived:   linesReceived,
+			EventsFlushed:   eventsFlushed,
+			SampleErrors:    *sampleErrors,
+			SamplesReceived: samplesReceived,
+			TagErrors:       tagErrors,
+			TagsReceived:    tagsReceived,
+		}, &mockStatsDTCPListener{listener.StatsDTCPListener{
+			Conn:            nil,
+			EventHandler:    nil,
+			Logger:          log.NewNopLogger(),
+			LinesReceived:   linesReceived,
+			EventsFlushed:   eventsFlushed,
+			SampleErrors:    *sampleErrors,
+			SamplesReceived: samplesReceived,
+			TagErrors:       tagErrors,
+			TagsReceived:    tagsReceived,
+			TCPConnections:  tcpConnections,
+			TCPErrors:       tcpErrors,
+			TCPLineTooLong:  tcpLineTooLong,
+		}, log.NewNopLogger()}} {
 			l.SetEventHandler(ueh)
-			l.HandlePacket([]byte("bar:200|c|#tag:value\nbar:200|c|#tag:\xc3\x28invalid"), udpPackets, linesReceived, eventsFlushed, *sampleErrors, samplesReceived, tagErrors, tagsReceived)
+			l.HandlePacket([]byte("bar:200|c|#tag:value\nbar:200|c|#tag:\xc3\x28invalid"))
 		}
 		close(events)
 	}()
@@ -508,8 +652,8 @@ func TestInvalidUtf8InDatadogTagValue(t *testing.T) {
 	testMapper := mapper.MetricMapper{}
 	testMapper.InitCache(0)
 
-	ex := exporter.NewExporter(&testMapper, log.NewNopLogger())
+	ex := NewExporter(&testMapper, log.NewNopLogger(), eventsActions, eventsUnmapped, errorEventStats, eventStats, conflictingEventStats, metricsCount)
-	ex.Listen(events, eventsActions, eventsUnmapped, errorEventStats, eventStats, conflictingEventStats, metricsCount)
+	ex.Listen(events)
 }
 
 // In the case of someone starting the statsd exporter with no mapping file specified
@@ -522,8 +666,8 @@ func TestSummaryWithQuantilesEmptyMapping(t *testing.T) {
 		testMapper := mapper.MetricMapper{}
 		testMapper.InitCache(0)
 
-		ex := exporter.NewExporter(&testMapper, log.NewNopLogger())
+		ex := NewExporter(&testMapper, log.NewNopLogger(), eventsActions, eventsUnmapped, errorEventStats, eventStats, conflictingEventStats, metricsCount)
-		ex.Listen(events, eventsActions, eventsUnmapped, errorEventStats, eventStats, conflictingEventStats, metricsCount)
+		ex.Listen(events)
 	}()
 
 	name := "default_foo"
@@ -566,9 +710,9 @@ func TestHistogramUnits(t *testing.T) {
 	go func() {
 		testMapper := mapper.MetricMapper{}
 		testMapper.InitCache(0)
-		ex := exporter.NewExporter(&testMapper, log.NewNopLogger())
+		ex := NewExporter(&testMapper, log.NewNopLogger(), eventsActions, eventsUnmapped, errorEventStats, eventStats, conflictingEventStats, metricsCount)
 		ex.Mapper.Defaults.TimerType = mapper.TimerTypeHistogram
-		ex.Listen(events, eventsActions, eventsUnmapped, errorEventStats, eventStats, conflictingEventStats, metricsCount)
+		ex.Listen(events)
 	}()
 
 	// Synchronously send a statsd event to wait for handleEvent execution.
@@ -605,8 +749,8 @@ func TestCounterIncrement(t *testing.T) {
 	go func() {
 		testMapper := mapper.MetricMapper{}
 		testMapper.InitCache(0)
-		ex := exporter.NewExporter(&testMapper, log.NewNopLogger())
+		ex := NewExporter(&testMapper, log.NewNopLogger(), eventsActions, eventsUnmapped, errorEventStats, eventStats, conflictingEventStats, metricsCount)
-		ex.Listen(events, eventsActions, eventsUnmapped, errorEventStats, eventStats, conflictingEventStats, metricsCount)
+		ex.Listen(events)
 	}()
 
 	// Synchronously send a statsd event to wait for handleEvent execution.
@@ -647,7 +791,7 @@ func TestCounterIncrement(t *testing.T) {
 }
 
 type statsDPacketHandler interface {
-	HandlePacket(packet []byte, udpPackets prometheus.Counter, linesReceived prometheus.Counter, eventsFlushed prometheus.Counter, sampleErrors prometheus.CounterVec, samplesReceived prometheus.Counter, tagErrors prometheus.Counter, tagsReceived prometheus.Counter)
+	HandlePacket(packet []byte)
 	SetEventHandler(eh event.EventHandler)
 }
 
@@ -656,7 +800,7 @@ type mockStatsDTCPListener struct {
 	log.Logger
 }
 
-func (ml *mockStatsDTCPListener) HandlePacket(packet []byte, udpPackets prometheus.Counter, linesReceived prometheus.Counter, eventsFlushed prometheus.Counter, sampleErrors prometheus.CounterVec, samplesReceived prometheus.Counter, tagErrors prometheus.Counter, tagsReceived prometheus.Counter) {
+func (ml *mockStatsDTCPListener) HandlePacket(packet []byte) {
 	// Forcing IPv4 because the TravisCI build environment does not have IPv6
 	// addresses.
 	lc, err := net.ListenTCP("tcp4", nil)
@@ -684,7 +828,7 @@ func (ml *mockStatsDTCPListener) HandlePacket(packet []byte, udpPackets promethe
 	if err != nil {
 		panic(fmt.Sprintf("mockStatsDTCPListener: accept failed: %v", err))
 	}
-	ml.HandleConn(sc, linesReceived, eventsFlushed, tcpConnections, tcpErrors, tcpLineTooLong, sampleErrors, samplesReceived, tagErrors, tagsReceived)
+	ml.HandleConn(sc)
 }
 
 // TestTtlExpiration validates expiration of time series.
@@ -714,8 +858,8 @@ mappings:
 	events := make(chan event.Events)
 	defer close(events)
 	go func() {
-		ex := exporter.NewExporter(testMapper, log.NewNopLogger())
+		ex := NewExporter(testMapper, log.NewNopLogger(), eventsActions, eventsUnmapped, errorEventStats, eventStats, conflictingEventStats, metricsCount)
-		ex.Listen(events, eventsActions, eventsUnmapped, errorEventStats, eventStats, conflictingEventStats, metricsCount)
+		ex.Listen(events)
 	}()
 
 	ev := event.Events{

pkg/listener/listener.go

@@ -28,16 +28,23 @@ import (
 )
 
 type StatsDUDPListener struct {
-	Conn         *net.UDPConn
+	Conn            *net.UDPConn
-	EventHandler event.EventHandler
+	EventHandler    event.EventHandler
-	Logger       log.Logger
+	Logger          log.Logger
+	UDPPackets      prometheus.Counter
+	LinesReceived   prometheus.Counter
+	EventsFlushed   prometheus.Counter
+	SampleErrors    prometheus.CounterVec
+	SamplesReceived prometheus.Counter
+	TagErrors       prometheus.Counter
+	TagsReceived    prometheus.Counter
 }
 
 func (l *StatsDUDPListener) SetEventHandler(eh event.EventHandler) {
 	l.EventHandler = eh
 }
 
-func (l *StatsDUDPListener) Listen(udpPackets prometheus.Counter, linesReceived prometheus.Counter, eventsFlushed prometheus.Counter, sampleErrors prometheus.CounterVec, samplesReceived prometheus.Counter, tagErrors prometheus.Counter, tagsReceived prometheus.Counter) {
+func (l *StatsDUDPListener) Listen() {
 	buf := make([]byte, 65535)
 	for {
 		n, _, err := l.Conn.ReadFromUDP(buf)
@@ -50,30 +57,39 @@ func (l *StatsDUDPListener) Listen(udpPackets prometheus.Counter, linesReceived
 			level.Error(l.Logger).Log("error", err)
 			return
 		}
-		l.HandlePacket(buf[0:n], udpPackets, linesReceived, eventsFlushed, sampleErrors, samplesReceived, tagErrors, tagsReceived)
+		l.HandlePacket(buf[0:n])
 	}
 }
 
-func (l *StatsDUDPListener) HandlePacket(packet []byte, udpPackets prometheus.Counter, linesReceived prometheus.Counter, eventsFlushed prometheus.Counter, sampleErrors prometheus.CounterVec, samplesReceived prometheus.Counter, tagErrors prometheus.Counter, tagsReceived prometheus.Counter) {
+func (l *StatsDUDPListener) HandlePacket(packet []byte) {
-	udpPackets.Inc()
+	l.UDPPackets.Inc()
 	lines := strings.Split(string(packet), "\n")
 	for _, line := range lines {
-		linesReceived.Inc()
+		l.LinesReceived.Inc()
-		l.EventHandler.Queue(pkgLine.LineToEvents(line, sampleErrors, samplesReceived, tagErrors, tagsReceived, l.Logger), &eventsFlushed)
+		l.EventHandler.Queue(pkgLine.LineToEvents(line, l.SampleErrors, l.SamplesReceived, l.TagErrors, l.TagsReceived, l.Logger))
 	}
 }
 
 type StatsDTCPListener struct {
-	Conn         *net.TCPListener
+	Conn            *net.TCPListener
-	EventHandler event.EventHandler
+	EventHandler    event.EventHandler
-	Logger       log.Logger
+	Logger          log.Logger
+	LinesReceived   prometheus.Counter
+	EventsFlushed   prometheus.Counter
+	SampleErrors    prometheus.CounterVec
+	SamplesReceived prometheus.Counter
+	TagErrors       prometheus.Counter
+	TagsReceived    prometheus.Counter
+	TCPConnections  prometheus.Counter
+	TCPErrors       prometheus.Counter
+	TCPLineTooLong  prometheus.Counter
 }
 
 func (l *StatsDTCPListener) SetEventHandler(eh event.EventHandler) {
 	l.EventHandler = eh
 }
 
-func (l *StatsDTCPListener) Listen(linesReceived prometheus.Counter, eventsFlushed prometheus.Counter, tcpConnections prometheus.Counter, tcpErrors prometheus.Counter, tcpLineTooLong prometheus.Counter, sampleErrors prometheus.CounterVec, samplesReceived prometheus.Counter, tagErrors prometheus.Counter, tagsReceived prometheus.Counter) {
+func (l *StatsDTCPListener) Listen() {
 	for {
 		c, err := l.Conn.AcceptTCP()
 		if err != nil {
@@ -85,46 +101,53 @@ func (l *StatsDTCPListener) Listen(linesReceived prometheus.Counter, eventsFlush
 			level.Error(l.Logger).Log("msg", "AcceptTCP failed", "error", err)
 			os.Exit(1)
 		}
-		go l.HandleConn(c, linesReceived, eventsFlushed, tcpConnections, tcpErrors, tcpLineTooLong, sampleErrors, samplesReceived, tagErrors, tagsReceived)
+		go l.HandleConn(c)
 	}
 }
 
-func (l *StatsDTCPListener) HandleConn(c *net.TCPConn, linesReceived prometheus.Counter, eventsFlushed prometheus.Counter, tcpConnections prometheus.Counter, tcpErrors prometheus.Counter, tcpLineTooLong prometheus.Counter, sampleErrors prometheus.CounterVec, samplesReceived prometheus.Counter, tagErrors prometheus.Counter, tagsReceived prometheus.Counter) {
+func (l *StatsDTCPListener) HandleConn(c *net.TCPConn) {
 	defer c.Close()
 
-	tcpConnections.Inc()
+	l.TCPConnections.Inc()
 
 	r := bufio.NewReader(c)
 	for {
 		line, isPrefix, err := r.ReadLine()
 		if err != nil {
 			if err != io.EOF {
-				tcpErrors.Inc()
+				l.TCPErrors.Inc()
 				level.Debug(l.Logger).Log("msg", "Read failed", "addr", c.RemoteAddr(), "error", err)
 			}
 			break
 		}
 		if isPrefix {
-			tcpLineTooLong.Inc()
+			l.TCPLineTooLong.Inc()
 			level.Debug(l.Logger).Log("msg", "Read failed: line too long", "addr", c.RemoteAddr())
 			break
 		}
-		linesReceived.Inc()
+		l.LinesReceived.Inc()
-		l.EventHandler.Queue(pkgLine.LineToEvents(string(line), sampleErrors, samplesReceived, tagErrors, tagsReceived, l.Logger), &eventsFlushed)
+		l.EventHandler.Queue(pkgLine.LineToEvents(string(line), l.SampleErrors, l.SamplesReceived, l.TagErrors, l.TagsReceived, l.Logger))
 	}
 }
 
 type StatsDUnixgramListener struct {
-	Conn         *net.UnixConn
+	Conn            *net.UnixConn
-	EventHandler event.EventHandler
+	EventHandler    event.EventHandler
-	Logger       log.Logger
+	Logger          log.Logger
+	UnixgramPackets prometheus.Counter
+	LinesReceived   prometheus.Counter
+	EventsFlushed   prometheus.Counter
+	SampleErrors    prometheus.CounterVec
+	SamplesReceived prometheus.Counter
+	TagErrors       prometheus.Counter
+	TagsReceived    prometheus.Counter
 }
 
 func (l *StatsDUnixgramListener) SetEventHandler(eh event.EventHandler) {
 	l.EventHandler = eh
 }
 
-func (l *StatsDUnixgramListener) Listen(unixgramPackets prometheus.Counter, linesReceived prometheus.Counter, eventsFlushed prometheus.Counter, sampleErrors prometheus.CounterVec, samplesReceived prometheus.Counter, tagErrors prometheus.Counter, tagsReceived prometheus.Counter) {
+func (l *StatsDUnixgramListener) Listen() {
 	buf := make([]byte, 65535)
 	for {
 		n, _, err := l.Conn.ReadFromUnix(buf)
@@ -137,15 +160,15 @@ func (l *StatsDUnixgramListener) Listen(unixgramPackets prometheus.Counter, line
 			level.Error(l.Logger).Log(err)
 			os.Exit(1)
 		}
-		l.HandlePacket(buf[:n], unixgramPackets, linesReceived, eventsFlushed, sampleErrors, samplesReceived, tagErrors, tagsReceived)
+		l.HandlePacket(buf[:n])
 	}
 }
 
-func (l *StatsDUnixgramListener) HandlePacket(packet []byte, unixgramPackets prometheus.Counter, linesReceived prometheus.Counter, eventsFlushed prometheus.Counter, sampleErrors prometheus.CounterVec, samplesReceived prometheus.Counter, tagErrors prometheus.Counter, tagsReceived prometheus.Counter) {
+func (l *StatsDUnixgramListener) HandlePacket(packet []byte) {
-	unixgramPackets.Inc()
+	l.UnixgramPackets.Inc()
 	lines := strings.Split(string(packet), "\n")
 	for _, line := range lines {
-		linesReceived.Inc()
+		l.LinesReceived.Inc()
-		l.EventHandler.Queue(pkgLine.LineToEvents(line, sampleErrors, samplesReceived, tagErrors, tagsReceived, l.Logger), &eventsFlushed)
+		l.EventHandler.Queue(pkgLine.LineToEvents(line, l.SampleErrors, l.SamplesReceived, l.TagErrors, l.TagsReceived, l.Logger))
 	}
 }