Add support for prometheus with exemplars

- Pull in latest v1.4.1 prometheus client
- Add WithExemplar methods to counters and histograms

Gopkg.toml

@@ -12,7 +12,7 @@
 
 [[constraint]]
   name = "github.com/prometheus/client_golang"
-  version = "1.1.0"
+  version = "1.4.1"
 
 [[constraint]]
   name = "github.com/stretchr/testify"

metrics/counter.go

@@ -18,6 +18,7 @@ package metrics
 type Counter interface {
 	// Inc adds the given value to the counter.
 	Inc(int64)
+	IncWithExemplar(int64, string)
 }
 
 // NullCounter counter that does nothing
@@ -26,3 +27,5 @@ var NullCounter Counter = nullCounter{}
 type nullCounter struct{}
 
 func (nullCounter) Inc(int64) {}
+
+func (n nullCounter) IncWithExemplar(int64, string) {}

metrics/go-kit/metrics.go

@@ -35,6 +35,11 @@ func (c *Counter) Inc(delta int64) {
 	c.counter.Add(float64(delta))
 }
 
+// IncWithExemplar adds the given value alongwith the trace ID provided.
+func (c *Counter) IncWithExemplar(int64, string) {
+	panic("not implemented")
+}
+
 // Gauge is an adapter from go-kit Gauge to jaeger-lib Gauge
 type Gauge struct {
 	gauge kit.Gauge
@@ -65,6 +70,11 @@ func (t *Timer) Record(delta time.Duration) {
 	t.hist.Observe(delta.Seconds())
 }
 
+// RecordWithExemplar saves the time passed in with the trace ID provided.
+func (t *Timer) RecordWithExemplar(time.Duration, string) {
+	panic("not implemented")
+}
+
 // Histogram is an adapter from go-kit Histogram to jaeger-lib Histogram
 type Histogram struct {
 	hist kit.Histogram
@@ -79,3 +89,8 @@ func NewHistogram(hist kit.Histogram) *Histogram {
 func (t *Histogram) Record(value float64) {
 	t.hist.Observe(value)
 }
+
+// RecordWithExemplar saves the time passed in with the trace ID provided.
+func (t *Histogram) RecordWithExemplar(float64, string) {
+	panic("not implemented")
+}

metrics/histogram.go

@@ -18,6 +18,7 @@ package metrics
 type Histogram interface {
 	// Records the value passed in.
 	Record(float64)
+	RecordWithExemplar(float64, string)
 }
 
 // NullHistogram that does nothing
@@ -26,3 +27,5 @@ var NullHistogram Histogram = nullHistogram{}
 type nullHistogram struct{}
 
 func (nullHistogram) Record(float64) {}
+
+func (n nullHistogram) RecordWithExemplar(float64, string) {}

metrics/metricstest/local.go

@@ -276,6 +276,10 @@ func (l *localTimer) Record(d time.Duration) {
 	l.localBackend.RecordTimer(l.name, l.tags, d)
 }
 
+func (l *localTimer) RecordWithExemplar(d time.Duration, t string) {
+	l.localBackend.RecordTimer(l.name, l.tags, d)
+}
+
 type localHistogram struct {
 	stats
 }
@@ -284,6 +288,10 @@ func (l *localHistogram) Record(v float64) {
 	l.localBackend.RecordHistogram(l.name, l.tags, v)
 }
 
+func (l *localHistogram) RecordWithExemplar(v float64, t string) {
+	l.localBackend.RecordHistogram(l.name, l.tags, v)
+}
+
 type localCounter struct {
 	stats
 }
@@ -292,6 +300,10 @@ func (l *localCounter) Inc(delta int64) {
 	l.localBackend.IncCounter(l.name, l.tags, delta)
 }
 
+func (l *localCounter) IncWithExemplar(delta int64, t string) {
+	l.localBackend.IncCounter(l.name, l.tags, delta)
+}
+
 type localGauge struct {
 	stats
 }

metrics/multi/multi.go

@@ -42,6 +42,12 @@ func (c *counter) Inc(delta int64) {
 	}
 }
 
+func (c *counter) IncWithExemplar(delta int64, t string) {
+	for _, counter := range c.counters {
+		counter.Inc(delta)
+	}
+}
+
 // Counter implements metrics.Factory interface
 func (f *Factory) Counter(options metrics.Options) metrics.Counter {
 	counter := &counter{
@@ -63,6 +69,12 @@ func (t *timer) Record(delta time.Duration) {
 	}
 }
 
+func (t *timer) RecordWithExemplar(delta time.Duration, traceID string) {
+	for _, timer := range t.timers {
+		timer.Record(delta)
+	}
+}
+
 // Timer implements metrics.Factory interface
 func (f *Factory) Timer(options metrics.TimerOptions) metrics.Timer {
 	timer := &timer{
@@ -84,6 +96,12 @@ func (h *histogram) Record(value float64) {
 	}
 }
 
+func (h *histogram) RecordWithExemplar(value float64, t string) {
+	for _, histogram := range h.histograms {
+		histogram.Record(value)
+	}
+}
+
 // Histogram implements metrics.Factory interface
 func (f *Factory) Histogram(options metrics.HistogramOptions) metrics.Histogram {
 	histogram := &histogram{