opentelemetry-go/exporters/trace/zipkin/model.go

package zipkin

import (
	"encoding/binary"
	"encoding/json"
	"fmt"

	zkmodel "github.com/openzipkin/zipkin-go/model"

	"go.opentelemetry.io/otel/api/core"
	"go.opentelemetry.io/otel/api/trace"
	export "go.opentelemetry.io/otel/sdk/export/trace"
)

func toZipkinSpanModels(batch []*export.SpanData) []zkmodel.SpanModel {
	models := make([]zkmodel.SpanModel, 0, len(batch))
	for _, data := range batch {
		models = append(models, toZipkinSpanModel(data))
	}
	return models
}

func toZipkinSpanModel(data *export.SpanData) zkmodel.SpanModel {
	return zkmodel.SpanModel{
		SpanContext:    toZipkinSpanContext(data),
		Name:           data.Name,
		Kind:           toZipkinKind(data.SpanKind),
		Timestamp:      data.StartTime,
		Duration:       data.EndTime.Sub(data.StartTime),
		Shared:         false,
		LocalEndpoint:  nil, // *Endpoint
		RemoteEndpoint: nil, // *Endpoint
		Annotations:    toZipkinAnnotations(data.MessageEvents),
		Tags:           toZipkinTags(data),
	}
}

func toZipkinSpanContext(data *export.SpanData) zkmodel.SpanContext {
	return zkmodel.SpanContext{
		TraceID:  toZipkinTraceID(data.SpanContext.TraceID),
		ID:       toZipkinID(data.SpanContext.SpanID),
		ParentID: toZipkinParentID(data.ParentSpanID),
		Debug:    false,
		Sampled:  nil,
		Err:      nil,
	}
}

func toZipkinTraceID(traceID core.TraceID) zkmodel.TraceID {
	return zkmodel.TraceID{
		High: binary.BigEndian.Uint64(traceID[:8]),
		Low:  binary.BigEndian.Uint64(traceID[8:]),
	}
}

func toZipkinID(spanID core.SpanID) zkmodel.ID {
	return zkmodel.ID(binary.BigEndian.Uint64(spanID[:]))
}

func toZipkinParentID(spanID core.SpanID) *zkmodel.ID {
	if spanID.IsValid() {
		id := toZipkinID(spanID)
		return &id
	}
	return nil
}

func toZipkinKind(kind trace.SpanKind) zkmodel.Kind {
	switch kind {
	case trace.SpanKindUnspecified:
		return zkmodel.Undetermined
	case trace.SpanKindInternal:
		// The spec says we should set the kind to nil, but
		// the model does not allow that.
		return zkmodel.Undetermined
	case trace.SpanKindServer:
		return zkmodel.Server
	case trace.SpanKindClient:
		return zkmodel.Client
	case trace.SpanKindProducer:
		return zkmodel.Producer
	case trace.SpanKindConsumer:
		return zkmodel.Consumer
	}
	return zkmodel.Undetermined
}

func toZipkinAnnotations(events []export.Event) []zkmodel.Annotation {
	if len(events) == 0 {
		return nil
	}
	annotations := make([]zkmodel.Annotation, 0, len(events))
	for _, event := range events {
		value := event.Name
		if len(event.Attributes) > 0 {
			jsonString := attributesToJSONMapString(event.Attributes)
			if jsonString != "" {
				value = fmt.Sprintf("%s: %s", event.Name, jsonString)
			}
		}
		annotations = append(annotations, zkmodel.Annotation{
			Timestamp: event.Time,
			Value:     value,
		})
	}
	return annotations
}

func attributesToJSONMapString(attributes []core.KeyValue) string {
	m := make(map[string]interface{}, len(attributes))
	for _, attribute := range attributes {
		m[(string)(attribute.Key)] = attribute.Value.AsInterface()
	}
	// if an error happens, the result will be an empty string
	jsonBytes, _ := json.Marshal(m)
	return (string)(jsonBytes)
}

func toZipkinTags(data *export.SpanData) map[string]string {
	// +2 for status code and for status message
	m := make(map[string]string, len(data.Attributes)+2)
	for _, kv := range data.Attributes {
		m[(string)(kv.Key)] = kv.Value.Emit()
	}
	if v, ok := m["error"]; ok && v == "false" {
		delete(m, "error")
	}
	m["ot.status_code"] = data.StatusCode.String()
	m["ot.status_description"] = data.StatusMessage
	return m
}