Updates for jaeger tracing client.

vendor/github.com/uber/jaeger-client-go/zipkin/propagation.go

@@ -0,0 +1,95 @@
+// Copyright (c) 2017 Uber Technologies, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package zipkin
+
+import (
+	"strconv"
+	"strings"
+
+	opentracing "github.com/opentracing/opentracing-go"
+
+	"github.com/uber/jaeger-client-go"
+)
+
+// Propagator is an Injector and Extractor
+type Propagator struct{}
+
+// NewZipkinB3HTTPHeaderPropagator creates a Propagator for extracting and injecting
+// Zipkin HTTP B3 headers into SpanContexts.
+func NewZipkinB3HTTPHeaderPropagator() Propagator {
+	return Propagator{}
+}
+
+// Inject conforms to the Injector interface for decoding Zipkin HTTP B3 headers
+func (p Propagator) Inject(
+	sc jaeger.SpanContext,
+	abstractCarrier interface{},
+) error {
+	textMapWriter, ok := abstractCarrier.(opentracing.TextMapWriter)
+	if !ok {
+		return opentracing.ErrInvalidCarrier
+	}
+
+	// TODO this needs to change to support 128bit IDs
+	textMapWriter.Set("x-b3-traceid", strconv.FormatUint(sc.TraceID().Low, 16))
+	if sc.ParentID() != 0 {
+		textMapWriter.Set("x-b3-parentspanid", strconv.FormatUint(uint64(sc.ParentID()), 16))
+	}
+	textMapWriter.Set("x-b3-spanid", strconv.FormatUint(uint64(sc.SpanID()), 16))
+	if sc.IsSampled() {
+		textMapWriter.Set("x-b3-sampled", "1")
+	} else {
+		textMapWriter.Set("x-b3-sampled", "0")
+	}
+	return nil
+}
+
+// Extract conforms to the Extractor interface for encoding Zipkin HTTP B3 headers
+func (p Propagator) Extract(abstractCarrier interface{}) (jaeger.SpanContext, error) {
+	textMapReader, ok := abstractCarrier.(opentracing.TextMapReader)
+	if !ok {
+		return jaeger.SpanContext{}, opentracing.ErrInvalidCarrier
+	}
+	var traceID uint64
+	var spanID uint64
+	var parentID uint64
+	sampled := false
+	err := textMapReader.ForeachKey(func(rawKey, value string) error {
+		key := strings.ToLower(rawKey) // TODO not necessary for plain TextMap
+		var err error
+		if key == "x-b3-traceid" {
+			traceID, err = strconv.ParseUint(value, 16, 64)
+		} else if key == "x-b3-parentspanid" {
+			parentID, err = strconv.ParseUint(value, 16, 64)
+		} else if key == "x-b3-spanid" {
+			spanID, err = strconv.ParseUint(value, 16, 64)
+		} else if key == "x-b3-sampled" && value == "1" {
+			sampled = true
+		}
+		return err
+	})
+
+	if err != nil {
+		return jaeger.SpanContext{}, err
+	}
+	if traceID == 0 {
+		return jaeger.SpanContext{}, opentracing.ErrSpanContextNotFound
+	}
+	return jaeger.NewSpanContext(
+		jaeger.TraceID{Low: traceID},
+		jaeger.SpanID(spanID),
+		jaeger.SpanID(parentID),
+		sampled, nil), nil
+}