commit 14385cd831535a82da3e8aa0a158bf68bbc7d2ab
Author: Julius Volz <julius@soundcloud.com>
Date:   Tue Jul 2 18:16:39 2013 +0200

    Initial commit.

diff --git a/main.go b/main.go
new file mode 100644
index 0000000..72bfd8d
--- /dev/null
+++ b/main.go
@@ -0,0 +1,323 @@
+// Copyright (c) 2013, Prometheus Team
+// All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"flag"
+	"log"
+	"net"
+	"net/http"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/exp"
+)
+
+var listeningAddress = flag.String("listeningAddress", ":8080", "The address on which to expose generated Prometheus metrics.")
+var statsdListeningAddress = flag.String("statsdListeningAddress", ":8126", "The UDP address on which to receive statsd metric lines.")
+
+type CounterContainer struct {
+	sync.RWMutex
+
+	Elements map[string]prometheus.Counter
+}
+
+func NewCounterContainer() *CounterContainer {
+	return &CounterContainer{
+		Elements: make(map[string]prometheus.Counter),
+	}
+}
+
+func (c *CounterContainer) Get(metricName string) prometheus.Counter {
+	c.Lock()
+	defer c.Unlock()
+
+	counter, ok := c.Elements[metricName]
+	if !ok {
+		counter = prometheus.NewCounter()
+		c.Elements[metricName] = counter
+		prometheus.Register(metricName, "", prometheus.NilLabels, counter)
+	}
+	return counter
+}
+
+type GaugeContainer struct {
+	sync.RWMutex
+
+	Elements map[string]prometheus.Gauge
+}
+
+func NewGaugeContainer() *GaugeContainer {
+	return &GaugeContainer{
+		Elements: make(map[string]prometheus.Gauge),
+	}
+}
+
+func (c *GaugeContainer) Get(metricName string) prometheus.Gauge {
+	c.Lock()
+	defer c.Unlock()
+
+	gauge, ok := c.Elements[metricName]
+	if !ok {
+		gauge = prometheus.NewGauge()
+		c.Elements[metricName] = gauge
+		prometheus.Register(metricName, "", prometheus.NilLabels, gauge)
+	}
+	return gauge
+}
+
+type SummaryContainer struct {
+	sync.RWMutex
+
+	Elements map[string]prometheus.Histogram
+
+	ResetInterval time.Duration
+}
+
+func NewSummaryContainer() *SummaryContainer {
+	return &SummaryContainer{
+		Elements: make(map[string]prometheus.Histogram),
+	}
+}
+
+func (c *SummaryContainer) Get(metricName string) prometheus.Histogram {
+	c.Lock()
+	defer c.Unlock()
+
+	summary, ok := c.Elements[metricName]
+	if !ok {
+		summary = prometheus.NewDefaultHistogram()
+		c.Elements[metricName] = summary
+		prometheus.Register(metricName, "", prometheus.NilLabels, summary)
+	}
+	return summary
+}
+
+type Event interface {
+	MetricName() string
+	Value() float64
+}
+
+type CounterEvent struct {
+	metricName string
+	value      float64
+}
+
+func (c *CounterEvent) MetricName() string { return c.metricName }
+func (c *CounterEvent) Value() float64     { return c.value }
+
+type GaugeEvent struct {
+	metricName string
+	value      float64
+}
+
+func (g *GaugeEvent) MetricName() string { return g.metricName }
+func (g *GaugeEvent) Value() float64     { return g.value }
+
+type TimerEvent struct {
+	metricName string
+	value      float64
+}
+
+func (t *TimerEvent) MetricName() string { return t.metricName }
+func (t *TimerEvent) Value() float64     { return t.value }
+
+type Events []Event
+
+type Bridge struct {
+	Counters  *CounterContainer
+	Gauges    *GaugeContainer
+	Summaries *SummaryContainer
+}
+
+func escapeMetricName(metricName string) string {
+	// TODO: evaluate what kind of escaping we really want.
+	metricName = strings.Replace(metricName, "_", "__", -1)
+	metricName = strings.Replace(metricName, "-", "__", -1)
+	metricName = strings.Replace(metricName, ".", "_", -1)
+	return metricName
+}
+
+func (b *Bridge) Listen(e <-chan Events) {
+	for {
+		events := <-e
+		for _, event := range events {
+			metricName := escapeMetricName(event.MetricName())
+			switch event.(type) {
+			case *CounterEvent:
+				counter := b.Counters.Get(metricName + "_counter")
+				counter.IncrementBy(prometheus.NilLabels, event.Value())
+			case *GaugeEvent:
+				gauge := b.Gauges.Get(metricName + "_gauge")
+				gauge.Set(prometheus.NilLabels, event.Value())
+			case *TimerEvent:
+				summary := b.Summaries.Get(metricName + "_timer")
+				summary.Add(prometheus.NilLabels, event.Value())
+			default:
+				log.Println("Unsupported event type")
+			}
+		}
+	}
+}
+
+func NewBridge() *Bridge {
+	return &Bridge{
+		Counters:  NewCounterContainer(),
+		Gauges:    NewGaugeContainer(),
+		Summaries: NewSummaryContainer(),
+	}
+}
+
+type StatsDListener struct {
+	conn *net.UDPConn
+}
+
+func (l *StatsDListener) Listen(e chan<- Events) {
+	// TODO: evaluate proper size according to MTU
+	var buf [512]byte
+	for {
+		n, _, err := l.conn.ReadFromUDP(buf[0:])
+		if err != nil {
+			log.Fatal(err)
+		}
+		l.handlePacket(buf[0:n], e)
+	}
+}
+
+func (l *StatsDListener) handlePacket(packet []byte, e chan<- Events) {
+	lines := strings.Split(string(packet), "\n")
+	events := Events{}
+	for _, line := range lines {
+		if line == "" {
+			continue
+		}
+
+		elements := strings.Split(line, ":")
+		if len(elements) < 2 {
+			log.Println("Bad line from StatsD:", line)
+			continue
+		}
+		metric := elements[0]
+		samples := elements[1:]
+		for _, sample := range samples {
+			components := strings.Split(sample, "|")
+			samplingFactor := 1.0
+			if len(components) < 2 || len(components) > 3 {
+				log.Println("Bad component on line:", line)
+				continue
+			}
+			valueStr, statType := components[0], components[1]
+			value, err := strconv.Atoi(valueStr)
+			if err != nil {
+				log.Printf("Bad value %s on line: %s", valueStr, line)
+				continue
+			}
+
+			if len(components) == 3 {
+				if statType != "c" {
+					log.Println("Illegal sampling factor for non-counter metric on line", line)
+				}
+				samplingStr := components[2]
+				if samplingStr[0] != '@' {
+					log.Printf("Invalid sampling factor %s on line %s", samplingStr, line)
+					continue
+				}
+				samplingFactor, err = strconv.ParseFloat(samplingStr[1:], 64)
+				if err != nil {
+					log.Printf("Invalid sampling factor %s on line %s", samplingStr, line)
+					continue
+				}
+				if samplingFactor == 0 {
+					// This should never happen, but avoid division by zero if it does.
+					log.Printf("Invalid zero sampling factor %s on line %s, setting to 1", samplingStr, line)
+					samplingFactor = 1
+				}
+			}
+
+			var event Event
+			switch statType {
+			case "c":
+				event = &CounterEvent{
+					metricName: metric,
+					value:      float64(value) / samplingFactor,
+				}
+			case "g":
+				event = &GaugeEvent{
+					metricName: metric,
+					value:      float64(value),
+				}
+			case "ms":
+				event = &TimerEvent{
+					metricName: metric,
+					value:      float64(value),
+				}
+			case "s":
+				log.Println("No support for StatsD sets in line", line)
+			default:
+				log.Printf("Bad stat type %s on line: %s", statType, line)
+			}
+			if event != nil {
+				events = append(events, event)
+			}
+		}
+	}
+	e <- events
+}
+
+func serveHTTP() {
+	exp.Handle(prometheus.ExpositionResource, prometheus.DefaultHandler)
+	http.ListenAndServe(*listeningAddress, exp.DefaultCoarseMux)
+}
+
+func udpAddrFromString(addr string) *net.UDPAddr {
+	host, portStr, err := net.SplitHostPort(*statsdListeningAddress)
+	if err != nil {
+		log.Fatal("Bad StatsD listening address", *statsdListeningAddress)
+	}
+
+	if host == "" {
+		host = "0.0.0.0"
+	}
+	ip, err := net.ResolveIPAddr("ip", host)
+	if err != nil {
+		log.Fatalf("Unable to resolve %s: %s", host, err)
+	}
+
+	port, err := strconv.Atoi(portStr)
+	if err != nil || port < 0 || port > 65535 {
+		log.Fatal("Bad port %s: %s", portStr, err)
+	}
+
+	return &net.UDPAddr{
+		IP:   ip.IP,
+		Port: port,
+		Zone: ip.Zone,
+	}
+}
+
+func main() {
+	flag.Parse()
+
+	go serveHTTP()
+
+	events := make(chan Events, 1024)
+	defer close(events)
+
+	listenAddr := udpAddrFromString(*statsdListeningAddress)
+	conn, err := net.ListenUDP("udp", listenAddr)
+	if err != nil {
+		log.Fatal(err)
+	}
+	l := &StatsDListener{conn: conn}
+	go l.Listen(events)
+
+	bridge := NewBridge()
+	bridge.Listen(events)
+}
diff --git a/main_test.go b/main_test.go
new file mode 100644
index 0000000..a720979
--- /dev/null
+++ b/main_test.go
@@ -0,0 +1,126 @@
+// Copyright (c) 2013, Prometheus Team
+// All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"fmt"
+	"testing"
+)
+
+func TestHandlePacket(t *testing.T) {
+	scenarios := []struct {
+		name string
+		in   string
+		out  Events
+	}{
+		{
+			name: "empty",
+		}, {
+			name: "simple counter",
+			in:   "foo:2|c",
+			out: Events{
+				&CounterEvent{
+					metricName: "foo",
+					value:      2,
+				},
+			},
+		}, {
+			name: "simple gauge",
+			in:   "foo:3|g",
+			out: Events{
+				&GaugeEvent{
+					metricName: "foo",
+					value:      3,
+				},
+			},
+		}, {
+			name: "simple timer",
+			in:   "foo:200|ms",
+			out: Events{
+				&TimerEvent{
+					metricName: "foo",
+					value:      200,
+				},
+			},
+		}, {
+			name: "combined multiline metrics",
+			in:   "foo:200|ms:300|ms:5|c|@0.1:6|g\nbar:1|c:5|ms",
+			out: Events{
+				&TimerEvent{
+					metricName: "foo",
+					value:      200,
+				},
+				&TimerEvent{
+					metricName: "foo",
+					value:      300,
+				},
+				&CounterEvent{
+					metricName: "foo",
+					value:      50,
+				},
+				&GaugeEvent{
+					metricName: "foo",
+					value:      6,
+				},
+				&CounterEvent{
+					metricName: "bar",
+					value:      1,
+				},
+				&TimerEvent{
+					metricName: "bar",
+					value:      5,
+				},
+			},
+		}, {
+			name: "bad line",
+			in:   "foo",
+		}, {
+			name: "bad component",
+			in:   "foo:1",
+		}, {
+			name: "bad value",
+			in:   "foo:1o|c",
+		}, {
+			name: "illegal sampling factor",
+			in:   "foo:1|c|@bar",
+		}, {
+			name: "zero sampling factor",
+			in:   "foo:2|c|@0",
+			out: Events{
+				&CounterEvent{
+					metricName: "foo",
+					value:      2,
+				},
+			},
+		}, {
+			name: "illegal stat type",
+			in:   "foo:2|t",
+		},
+	}
+
+	l := StatsDListener{}
+	events := make(chan Events, 32)
+	for i, scenario := range scenarios {
+		l.handlePacket([]byte(scenario.in), events)
+
+		// Flatten actual events.
+		actual := Events{}
+		for i := 0; i < len(events); i++ {
+			actual = append(actual, <-events...)
+		}
+
+		if len(actual) != len(scenario.out) {
+			t.Fatalf("%d. Expected %d events, got %d", i, len(scenario.out), len(actual))
+		}
+
+		for j, expected := range scenario.out {
+			if fmt.Sprintf("%v", actual[j]) != fmt.Sprintf("%v", expected) {
+				t.Fatalf("%d.%d. Expected %v, got %v", i, j, actual[j], expected)
+			}
+		}
+	}
+}