Merge pull request #27 from rcrowley/librato

first pass at a librato reporter

librato/librato.go

@@ -0,0 +1,139 @@
+package librato
+
+import (
+	"fmt"
+	"github.com/rcrowley/go-metrics"
+	"github.com/samuel/go-librato/librato"
+	"log"
+	"math"
+	"time"
+)
+
+type LibratoReporter struct {
+	Email, Token string
+	Source       string
+	Interval     time.Duration
+	Registry     metrics.Registry
+	Percentiles  []float64
+}
+
+func (self *LibratoReporter) Run() {
+	ticker := time.Tick(self.Interval * time.Millisecond)
+	metricsApi := &librato.Metrics{self.Email, self.Token}
+	for now := range ticker {
+		var metrics *librato.MetricsFormat
+		var err error
+		if metrics, err = self.BuildRequest(now, self.Registry); err != nil {
+			log.Printf("ERROR constructing librato request body %s", err)
+		}
+		if err := metricsApi.SendMetrics(metrics); err != nil {
+			log.Printf("ERROR sending metrics to librato %s", err)
+		}
+	}
+}
+
+// calculate sum of squares from data provided by metrics.Histogram
+// see http://en.wikipedia.org/wiki/Standard_deviation#Rapid_calculation_methods
+func sumSquares(m metrics.Histogram) float64 {
+	count := float64(m.Count())
+	sum := m.Mean() * float64(m.Count())
+	sumSquared := math.Pow(float64(sum), 2)
+	sumSquares := math.Pow(count*m.StdDev(), 2) + sumSquared/float64(m.Count())
+	if math.IsNaN(sumSquares) {
+		return 0.0
+	}
+	return sumSquared
+}
+func sumSquaresTimer(m metrics.Timer) float64 {
+	count := float64(m.Count())
+	sum := m.Mean() * float64(m.Count())
+	sumSquared := math.Pow(float64(sum), 2)
+	sumSquares := math.Pow(count*m.StdDev(), 2) + sumSquared/float64(m.Count())
+	if math.IsNaN(sumSquares) {
+		return 0.0
+	}
+	return sumSquares
+}
+
+func (self *LibratoReporter) BuildRequest(now time.Time, r metrics.Registry) (snapshot *librato.MetricsFormat, err error) {
+	snapshot = &librato.MetricsFormat{}
+	snapshot.MeasureTime = now.Unix()
+	snapshot.Source = self.Source
+	snapshot.Gauges = make([]interface{}, 0)
+	snapshot.Counters = make([]librato.Metric, 0)
+	histogramGaugeCount := 1 + len(self.Percentiles)
+	r.Each(func(name string, metric interface{}) {
+		switch m := metric.(type) {
+		case metrics.Counter:
+			libratoName := fmt.Sprintf("%s.%s", name, "count")
+			snapshot.Counters = append(snapshot.Counters, librato.Metric{Name: libratoName, Value: float64(m.Count())})
+		case metrics.Gauge:
+			snapshot.Gauges = append(snapshot.Gauges, librato.Metric{Name: name, Value: float64(m.Value())})
+		case metrics.Histogram:
+			if m.Count() > 0 {
+				libratoName := fmt.Sprintf("%s.%s", name, "hist")
+				gauges := make([]interface{}, histogramGaugeCount, histogramGaugeCount)
+				gauges[0] = librato.Gauge{
+					Name:       libratoName,
+					Count:      uint64(m.Count()),
+					Sum:        m.Mean() * float64(m.Count()),
+					Max:        float64(m.Max()),
+					Min:        float64(m.Min()),
+					SumSquares: sumSquares(m),
+				}
+				for i, p := range self.Percentiles {
+					gauges[i+1] = librato.Metric{Name: fmt.Sprintf("%s.%.2f", libratoName, p), Value: m.Percentile(p)}
+				}
+				snapshot.Gauges = append(snapshot.Gauges, gauges...)
+			}
+		case metrics.Meter:
+			snapshot.Counters = append(snapshot.Counters, librato.Metric{Name: name, Value: float64(m.Count())})
+			snapshot.Gauges = append(snapshot.Gauges,
+				librato.Metric{
+					Name:  fmt.Sprintf("%s.%s", name, "1min"),
+					Value: m.Rate1(),
+				},
+				librato.Metric{
+					Name:  fmt.Sprintf("%s.%s", name, "5min"),
+					Value: m.Rate5(),
+				},
+				librato.Metric{
+					Name:  fmt.Sprintf("%s.%s", name, "15min"),
+					Value: m.Rate15(),
+				},
+			)
+		case metrics.Timer:
+			if m.Count() > 0 {
+				libratoName := fmt.Sprintf("%s.%s", name, "timer")
+				gauges := make([]interface{}, histogramGaugeCount, histogramGaugeCount)
+				gauges[0] = librato.Gauge{
+					Name:       libratoName,
+					Count:      uint64(m.Count()),
+					Sum:        m.Mean() * float64(m.Count()),
+					Max:        float64(m.Max()),
+					Min:        float64(m.Min()),
+					SumSquares: sumSquaresTimer(m),
+				}
+				for i, p := range self.Percentiles {
+					gauges[i+1] = librato.Metric{Name: fmt.Sprintf("%s.%2.0f", libratoName, p*100), Value: m.Percentile(p)}
+				}
+				snapshot.Gauges = append(snapshot.Gauges, gauges...)
+				snapshot.Gauges = append(snapshot.Gauges,
+					librato.Metric{
+						Name:  fmt.Sprintf("%s.%s", name, "1min"),
+						Value: m.Rate1(),
+					},
+					librato.Metric{
+						Name:  fmt.Sprintf("%s.%s", name, "5min"),
+						Value: m.Rate5(),
+					},
+					librato.Metric{
+						Name:  fmt.Sprintf("%s.%s", name, "15min"),
+						Value: m.Rate15(),
+					},
+				)
+			}
+		}
+	})
+	return
+}