Moved to google.golang.org/genproto/googleapis/api/annotations

Fixes #52

vendor/github.com/go-kit/kit/metrics/dogstatsd/dogstatsd.go

@@ -0,0 +1,314 @@
+// Package dogstatsd provides a DogStatsD backend for package metrics. It's very
+// similar to StatsD, but supports arbitrary tags per-metric, which map to Go
+// kit's label values. So, while label values are no-ops in StatsD, they are
+// supported here. For more details, see the documentation at
+// http://docs.datadoghq.com/guides/dogstatsd/.
+//
+// This package batches observations and emits them on some schedule to the
+// remote server. This is useful even if you connect to your DogStatsD server
+// over UDP. Emitting one network packet per observation can quickly overwhelm
+// even the fastest internal network.
+package dogstatsd
+
+import (
+	"fmt"
+	"io"
+	"strings"
+	"time"
+
+	"github.com/go-kit/kit/log"
+	"github.com/go-kit/kit/metrics"
+	"github.com/go-kit/kit/metrics/internal/lv"
+	"github.com/go-kit/kit/metrics/internal/ratemap"
+	"github.com/go-kit/kit/util/conn"
+)
+
+// Dogstatsd receives metrics observations and forwards them to a DogStatsD
+// server. Create a Dogstatsd object, use it to create metrics, and pass those
+// metrics as dependencies to the components that will use them.
+//
+// All metrics are buffered until WriteTo is called. Counters and gauges are
+// aggregated into a single observation per timeseries per write. Timings and
+// histograms are buffered but not aggregated.
+//
+// To regularly report metrics to an io.Writer, use the WriteLoop helper method.
+// To send to a DogStatsD server, use the SendLoop helper method.
+type Dogstatsd struct {
+	prefix     string
+	rates      *ratemap.RateMap
+	counters   *lv.Space
+	gauges     *lv.Space
+	timings    *lv.Space
+	histograms *lv.Space
+	logger     log.Logger
+}
+
+// New returns a Dogstatsd object that may be used to create metrics. Prefix is
+// applied to all created metrics. Callers must ensure that regular calls to
+// WriteTo are performed, either manually or with one of the helper methods.
+func New(prefix string, logger log.Logger) *Dogstatsd {
+	return &Dogstatsd{
+		prefix:     prefix,
+		rates:      ratemap.New(),
+		counters:   lv.NewSpace(),
+		gauges:     lv.NewSpace(),
+		timings:    lv.NewSpace(),
+		histograms: lv.NewSpace(),
+		logger:     logger,
+	}
+}
+
+// NewCounter returns a counter, sending observations to this Dogstatsd object.
+func (d *Dogstatsd) NewCounter(name string, sampleRate float64) *Counter {
+	d.rates.Set(d.prefix+name, sampleRate)
+	return &Counter{
+		name: d.prefix + name,
+		obs:  d.counters.Observe,
+	}
+}
+
+// NewGauge returns a gauge, sending observations to this Dogstatsd object.
+func (d *Dogstatsd) NewGauge(name string) *Gauge {
+	return &Gauge{
+		name: d.prefix + name,
+		obs:  d.gauges.Observe,
+		add:  d.gauges.Add,
+	}
+}
+
+// NewTiming returns a histogram whose observations are interpreted as
+// millisecond durations, and are forwarded to this Dogstatsd object.
+func (d *Dogstatsd) NewTiming(name string, sampleRate float64) *Timing {
+	d.rates.Set(d.prefix+name, sampleRate)
+	return &Timing{
+		name: d.prefix + name,
+		obs:  d.timings.Observe,
+	}
+}
+
+// NewHistogram returns a histogram whose observations are of an unspecified
+// unit, and are forwarded to this Dogstatsd object.
+func (d *Dogstatsd) NewHistogram(name string, sampleRate float64) *Histogram {
+	d.rates.Set(d.prefix+name, sampleRate)
+	return &Histogram{
+		name: d.prefix + name,
+		obs:  d.histograms.Observe,
+	}
+}
+
+// WriteLoop is a helper method that invokes WriteTo to the passed writer every
+// time the passed channel fires. This method blocks until the channel is
+// closed, so clients probably want to run it in its own goroutine. For typical
+// usage, create a time.Ticker and pass its C channel to this method.
+func (d *Dogstatsd) WriteLoop(c <-chan time.Time, w io.Writer) {
+	for range c {
+		if _, err := d.WriteTo(w); err != nil {
+			d.logger.Log("during", "WriteTo", "err", err)
+		}
+	}
+}
+
+// SendLoop is a helper method that wraps WriteLoop, passing a managed
+// connection to the network and address. Like WriteLoop, this method blocks
+// until the channel is closed, so clients probably want to start it in its own
+// goroutine. For typical usage, create a time.Ticker and pass its C channel to
+// this method.
+func (d *Dogstatsd) SendLoop(c <-chan time.Time, network, address string) {
+	d.WriteLoop(c, conn.NewDefaultManager(network, address, d.logger))
+}
+
+// WriteTo flushes the buffered content of the metrics to the writer, in
+// DogStatsD format. WriteTo abides best-effort semantics, so observations are
+// lost if there is a problem with the write. Clients should be sure to call
+// WriteTo regularly, ideally through the WriteLoop or SendLoop helper methods.
+func (d *Dogstatsd) WriteTo(w io.Writer) (count int64, err error) {
+	var n int
+
+	d.counters.Reset().Walk(func(name string, lvs lv.LabelValues, values []float64) bool {
+		n, err = fmt.Fprintf(w, "%s:%f|c%s%s\n", name, sum(values), sampling(d.rates.Get(name)), tagValues(lvs))
+		if err != nil {
+			return false
+		}
+		count += int64(n)
+		return true
+	})
+	if err != nil {
+		return count, err
+	}
+
+	d.gauges.Reset().Walk(func(name string, lvs lv.LabelValues, values []float64) bool {
+		n, err = fmt.Fprintf(w, "%s:%f|g%s\n", name, last(values), tagValues(lvs))
+		if err != nil {
+			return false
+		}
+		count += int64(n)
+		return true
+	})
+	if err != nil {
+		return count, err
+	}
+
+	d.timings.Reset().Walk(func(name string, lvs lv.LabelValues, values []float64) bool {
+		sampleRate := d.rates.Get(name)
+		for _, value := range values {
+			n, err = fmt.Fprintf(w, "%s:%f|ms%s%s\n", name, value, sampling(sampleRate), tagValues(lvs))
+			if err != nil {
+				return false
+			}
+			count += int64(n)
+		}
+		return true
+	})
+	if err != nil {
+		return count, err
+	}
+
+	d.histograms.Reset().Walk(func(name string, lvs lv.LabelValues, values []float64) bool {
+		sampleRate := d.rates.Get(name)
+		for _, value := range values {
+			n, err = fmt.Fprintf(w, "%s:%f|h%s%s\n", name, value, sampling(sampleRate), tagValues(lvs))
+			if err != nil {
+				return false
+			}
+			count += int64(n)
+		}
+		return true
+	})
+	if err != nil {
+		return count, err
+	}
+
+	return count, err
+}
+
+func sum(a []float64) float64 {
+	var v float64
+	for _, f := range a {
+		v += f
+	}
+	return v
+}
+
+func last(a []float64) float64 {
+	return a[len(a)-1]
+}
+
+func sampling(r float64) string {
+	var sv string
+	if r < 1.0 {
+		sv = fmt.Sprintf("|@%f", r)
+	}
+	return sv
+}
+
+func tagValues(labelValues []string) string {
+	if len(labelValues) == 0 {
+		return ""
+	}
+	if len(labelValues)%2 != 0 {
+		panic("tagValues received a labelValues with an odd number of strings")
+	}
+	pairs := make([]string, 0, len(labelValues)/2)
+	for i := 0; i < len(labelValues); i += 2 {
+		pairs = append(pairs, labelValues[i]+":"+labelValues[i+1])
+	}
+	return "|#" + strings.Join(pairs, ",")
+}
+
+type observeFunc func(name string, lvs lv.LabelValues, value float64)
+
+// Counter is a DogStatsD counter. Observations are forwarded to a Dogstatsd
+// object, and aggregated (summed) per timeseries.
+type Counter struct {
+	name string
+	lvs  lv.LabelValues
+	obs  observeFunc
+}
+
+// With implements metrics.Counter.
+func (c *Counter) With(labelValues ...string) metrics.Counter {
+	return &Counter{
+		name: c.name,
+		lvs:  c.lvs.With(labelValues...),
+		obs:  c.obs,
+	}
+}
+
+// Add implements metrics.Counter.
+func (c *Counter) Add(delta float64) {
+	c.obs(c.name, c.lvs, delta)
+}
+
+// Gauge is a DogStatsD gauge. Observations are forwarded to a Dogstatsd
+// object, and aggregated (the last observation selected) per timeseries.
+type Gauge struct {
+	name string
+	lvs  lv.LabelValues
+	obs  observeFunc
+	add  observeFunc
+}
+
+// With implements metrics.Gauge.
+func (g *Gauge) With(labelValues ...string) metrics.Gauge {
+	return &Gauge{
+		name: g.name,
+		lvs:  g.lvs.With(labelValues...),
+		obs:  g.obs,
+		add:  g.add,
+	}
+}
+
+// Set implements metrics.Gauge.
+func (g *Gauge) Set(value float64) {
+	g.obs(g.name, g.lvs, value)
+}
+
+// Add implements metrics.Gauge.
+func (g *Gauge) Add(delta float64) {
+	g.add(g.name, g.lvs, delta)
+}
+
+// Timing is a DogStatsD timing, or metrics.Histogram. Observations are
+// forwarded to a Dogstatsd object, and collected (but not aggregated) per
+// timeseries.
+type Timing struct {
+	name string
+	lvs  lv.LabelValues
+	obs  observeFunc
+}
+
+// With implements metrics.Timing.
+func (t *Timing) With(labelValues ...string) metrics.Histogram {
+	return &Timing{
+		name: t.name,
+		lvs:  t.lvs.With(labelValues...),
+		obs:  t.obs,
+	}
+}
+
+// Observe implements metrics.Histogram. Value is interpreted as milliseconds.
+func (t *Timing) Observe(value float64) {
+	t.obs(t.name, t.lvs, value)
+}
+
+// Histogram is a DogStatsD histrogram. Observations are forwarded to a
+// Dogstatsd object, and collected (but not aggregated) per timeseries.
+type Histogram struct {
+	name string
+	lvs  lv.LabelValues
+	obs  observeFunc
+}
+
+// With implements metrics.Histogram.
+func (h *Histogram) With(labelValues ...string) metrics.Histogram {
+	return &Histogram{
+		name: h.name,
+		lvs:  h.lvs.With(labelValues...),
+		obs:  h.obs,
+	}
+}
+
+// Observe implements metrics.Histogram.
+func (h *Histogram) Observe(value float64) {
+	h.obs(h.name, h.lvs, value)
+}