Add InfluxDB support for traefik metrics

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

@@ -0,0 +1,218 @@
+// Package generic implements generic versions of each of the metric types. They
+// can be embedded by other implementations, and converted to specific formats
+// as necessary.
+package generic
+
+import (
+	"fmt"
+	"io"
+	"math"
+	"sync"
+	"sync/atomic"
+
+	"github.com/VividCortex/gohistogram"
+
+	"github.com/go-kit/kit/metrics"
+	"github.com/go-kit/kit/metrics/internal/lv"
+)
+
+// Counter is an in-memory implementation of a Counter.
+type Counter struct {
+	Name string
+	lvs  lv.LabelValues
+	bits uint64
+}
+
+// NewCounter returns a new, usable Counter.
+func NewCounter(name string) *Counter {
+	return &Counter{
+		Name: name,
+	}
+}
+
+// With implements Counter.
+func (c *Counter) With(labelValues ...string) metrics.Counter {
+	return &Counter{
+		bits: atomic.LoadUint64(&c.bits),
+		lvs:  c.lvs.With(labelValues...),
+	}
+}
+
+// Add implements Counter.
+func (c *Counter) Add(delta float64) {
+	for {
+		var (
+			old  = atomic.LoadUint64(&c.bits)
+			newf = math.Float64frombits(old) + delta
+			new  = math.Float64bits(newf)
+		)
+		if atomic.CompareAndSwapUint64(&c.bits, old, new) {
+			break
+		}
+	}
+}
+
+// Value returns the current value of the counter.
+func (c *Counter) Value() float64 {
+	return math.Float64frombits(atomic.LoadUint64(&c.bits))
+}
+
+// ValueReset returns the current value of the counter, and resets it to zero.
+// This is useful for metrics backends whose counter aggregations expect deltas,
+// like Graphite.
+func (c *Counter) ValueReset() float64 {
+	for {
+		var (
+			old  = atomic.LoadUint64(&c.bits)
+			newf = 0.0
+			new  = math.Float64bits(newf)
+		)
+		if atomic.CompareAndSwapUint64(&c.bits, old, new) {
+			return math.Float64frombits(old)
+		}
+	}
+}
+
+// LabelValues returns the set of label values attached to the counter.
+func (c *Counter) LabelValues() []string {
+	return c.lvs
+}
+
+// Gauge is an in-memory implementation of a Gauge.
+type Gauge struct {
+	Name string
+	lvs  lv.LabelValues
+	bits uint64
+}
+
+// NewGauge returns a new, usable Gauge.
+func NewGauge(name string) *Gauge {
+	return &Gauge{
+		Name: name,
+	}
+}
+
+// With implements Gauge.
+func (g *Gauge) With(labelValues ...string) metrics.Gauge {
+	return &Gauge{
+		bits: atomic.LoadUint64(&g.bits),
+		lvs:  g.lvs.With(labelValues...),
+	}
+}
+
+// Set implements Gauge.
+func (g *Gauge) Set(value float64) {
+	atomic.StoreUint64(&g.bits, math.Float64bits(value))
+}
+
+// Value returns the current value of the gauge.
+func (g *Gauge) Value() float64 {
+	return math.Float64frombits(atomic.LoadUint64(&g.bits))
+}
+
+// LabelValues returns the set of label values attached to the gauge.
+func (g *Gauge) LabelValues() []string {
+	return g.lvs
+}
+
+// Histogram is an in-memory implementation of a streaming histogram, based on
+// VividCortex/gohistogram. It dynamically computes quantiles, so it's not
+// suitable for aggregation.
+type Histogram struct {
+	Name string
+	lvs  lv.LabelValues
+	h    gohistogram.Histogram
+}
+
+// NewHistogram returns a numeric histogram based on VividCortex/gohistogram. A
+// good default value for buckets is 50.
+func NewHistogram(name string, buckets int) *Histogram {
+	return &Histogram{
+		Name: name,
+		h:    gohistogram.NewHistogram(buckets),
+	}
+}
+
+// With implements Histogram.
+func (h *Histogram) With(labelValues ...string) metrics.Histogram {
+	return &Histogram{
+		lvs: h.lvs.With(labelValues...),
+		h:   h.h,
+	}
+}
+
+// Observe implements Histogram.
+func (h *Histogram) Observe(value float64) {
+	h.h.Add(value)
+}
+
+// Quantile returns the value of the quantile q, 0.0 < q < 1.0.
+func (h *Histogram) Quantile(q float64) float64 {
+	return h.h.Quantile(q)
+}
+
+// LabelValues returns the set of label values attached to the histogram.
+func (h *Histogram) LabelValues() []string {
+	return h.lvs
+}
+
+// Print writes a string representation of the histogram to the passed writer.
+// Useful for printing to a terminal.
+func (h *Histogram) Print(w io.Writer) {
+	fmt.Fprintf(w, h.h.String())
+}
+
+// Bucket is a range in a histogram which aggregates observations.
+type Bucket struct {
+	From, To, Count int64
+}
+
+// Quantile is a pair of a quantile (0..100) and its observed maximum value.
+type Quantile struct {
+	Quantile int // 0..100
+	Value    int64
+}
+
+// SimpleHistogram is an in-memory implementation of a Histogram. It only tracks
+// an approximate moving average, so is likely too naïve for many use cases.
+type SimpleHistogram struct {
+	mtx sync.RWMutex
+	lvs lv.LabelValues
+	avg float64
+	n   uint64
+}
+
+// NewSimpleHistogram returns a SimpleHistogram, ready for observations.
+func NewSimpleHistogram() *SimpleHistogram {
+	return &SimpleHistogram{}
+}
+
+// With implements Histogram.
+func (h *SimpleHistogram) With(labelValues ...string) metrics.Histogram {
+	return &SimpleHistogram{
+		lvs: h.lvs.With(labelValues...),
+		avg: h.avg,
+		n:   h.n,
+	}
+}
+
+// Observe implements Histogram.
+func (h *SimpleHistogram) Observe(value float64) {
+	h.mtx.Lock()
+	defer h.mtx.Unlock()
+	h.n++
+	h.avg -= h.avg / float64(h.n)
+	h.avg += value / float64(h.n)
+}
+
+// ApproximateMovingAverage returns the approximate moving average of observations.
+func (h *SimpleHistogram) ApproximateMovingAverage() float64 {
+	h.mtx.RLock()
+	defer h.mtx.RUnlock()
+	return h.avg
+}
+
+// LabelValues returns the set of label values attached to the histogram.
+func (h *SimpleHistogram) LabelValues() []string {
+	return h.lvs
+}