Trying a span to view converter

Author: tcoupland

api/server/server.go

@@ -28,7 +28,6 @@ import (
 	"github.com/fnproject/fn/api/models"
 	"github.com/fnproject/fn/api/mqs"
 	pool "github.com/fnproject/fn/api/runnerpool"
-	"github.com/fnproject/fn/api/server/spanexporter"
 	"github.com/fnproject/fn/api/version"
 	"github.com/fnproject/fn/fnext"
 	"github.com/gin-gonic/gin"
@@ -739,13 +738,8 @@ func WithPrometheus() Option {
 		}
 		s.promExporter = exporter
 		view.RegisterExporter(exporter)
-
-		spanExporter, err := spanexporter.NewExporter(spanexporter.Options{
-			Namespace: "fn",
-			Registry:  reg,
-			OnError:   func(err error) { logrus.WithError(err).Error("opencensus prometheus span exporter err") },
-		})
-		trace.RegisterExporter(spanExporter)
+		converter, _ := NewConverter(Options{Namespace: "fn", Exporter: exporter})
+		trace.RegisterExporter(converter)
 		trace.ApplyConfig(trace.Config{DefaultSampler: trace.AlwaysSample()})
 
 		return nil

api/server/spanconverter.go

@@ -0,0 +1,130 @@
+package server
+
+import (
+	"strings"
+	"sync"
+	"time"
+	"unicode"
+
+	"github.com/sirupsen/logrus"
+	"go.opencensus.io/stats"
+	view "go.opencensus.io/stats/view"
+	"go.opencensus.io/trace"
+)
+
+// Exporter exports stats to Prometheus, users need
+// to register the exporter as an http.Handler to be
+// able to export.
+type Converter struct {
+	opts     Options
+	measures map[string]*stats.Float64Measure
+	viewsMu  sync.Mutex
+	e        view.Exporter
+}
+
+// Options contains options for configuring the exporter.
+type Options struct {
+	Namespace string
+	Exporter  view.Exporter
+}
+
+func NewConverter(o Options) (*Converter, error) {
+	e := &Converter{
+		opts:     o,
+		e:        o.Exporter,
+		measures: make(map[string]*stats.Float64Measure),
+	}
+	return e, nil
+}
+
+// ExportView exports to the Prometheus if view data has one or more rows.
+// Each OpenCensus AggregationData will be converted to
+// corresponding Prometheus Metric: SumData will be converted
+// to Untyped Metric, CountData will be a Counter Metric,
+// DistributionData will be a Histogram Metric.
+func (c *Converter) ExportSpan(sd *trace.SpanData) {
+	m := c.getMeasure(sd)
+
+	spanTimeNanos := sd.EndTime.Sub(sd.StartTime)
+	spanTimeMillis := float64(int64(spanTimeNanos / time.Millisecond))
+
+	m.M(spanTimeMillis)
+}
+
+func (c *Converter) getMeasure(span *trace.SpanData) *stats.Float64Measure {
+	sig := spanName(c.opts.Namespace, span)
+	c.viewsMu.Lock()
+	m, ok := c.measures[sig]
+	c.viewsMu.Unlock()
+
+	if !ok {
+		logrus.Info("Creating Measure: %s", sig)
+		m = stats.Float64("span length", "The span length in milliseconds", "ms")
+		v := &view.View{
+			Name:        spanName(c.opts.Namespace, span),
+			Description: spanName(c.opts.Namespace, span),
+			Measure:     m,
+			Aggregation: view.Distribution(0, 1<<32, 2<<32, 3<<32),
+		}
+		// Buckets: []float64{1,
+		// 	10,
+		// 	50,
+		// 	100,
+		// 	250,
+		// 	500,
+		// 	1000,
+		// 	10000,
+		// 	60000,
+		// 	120000},
+		c.viewsMu.Lock()
+		c.measures[sig] = m
+		view.Register(v)
+		c.viewsMu.Unlock()
+	}
+
+	return m
+}
+
+func spanName(namespace string, s *trace.SpanData) string {
+	var name string
+	if namespace != "" {
+		name = namespace + "_"
+	}
+	return name + sanitize(s.Name)
+}
+
+const labelKeySizeLimit = 100
+
+// sanitize returns a string that is trunacated to 100 characters if it's too
+// long, and replaces non-alphanumeric characters to underscores.
+func sanitize(s string) string {
+	if len(s) == 0 {
+		return s
+	}
+	if len(s) > labelKeySizeLimit {
+		s = s[:labelKeySizeLimit]
+	}
+	s = strings.Map(sanitizeRune, s)
+	if unicode.IsDigit(rune(s[0])) {
+		s = "key_" + s
+	}
+	if s[0] == '_' {
+		s = "key" + s
+	}
+	return s
+}
+
+// converts anything that is not a letter or digit to an underscore
+func sanitizeRune(r rune) rune {
+	if unicode.IsLetter(r) || unicode.IsDigit(r) {
+		return r
+	}
+	// Everything else turns into an underscore
+	return '_'
+}
+
+//Gin creates spans for all paths, containing ID values.
+//We can safely discard these, as other histograms are being created for them.
+func urlName(s string) bool {
+	return strings.HasPrefix(s, "/")
+}