Instana tracer implementation

vendor/github.com/opentracing/basictracer-go/propagation_ot.go

@@ -0,0 +1,180 @@
+package basictracer
+
+import (
+	"encoding/binary"
+	"io"
+	"strconv"
+	"strings"
+
+	"github.com/gogo/protobuf/proto"
+	"github.com/opentracing/basictracer-go/wire"
+	opentracing "github.com/opentracing/opentracing-go"
+)
+
+type textMapPropagator struct {
+	tracer *tracerImpl
+}
+type binaryPropagator struct {
+	tracer *tracerImpl
+}
+
+const (
+	prefixTracerState = "ot-tracer-"
+	prefixBaggage     = "ot-baggage-"
+
+	tracerStateFieldCount = 3
+	fieldNameTraceID      = prefixTracerState + "traceid"
+	fieldNameSpanID       = prefixTracerState + "spanid"
+	fieldNameSampled      = prefixTracerState + "sampled"
+)
+
+func (p *textMapPropagator) Inject(
+	spanContext opentracing.SpanContext,
+	opaqueCarrier interface{},
+) error {
+	sc, ok := spanContext.(SpanContext)
+	if !ok {
+		return opentracing.ErrInvalidSpanContext
+	}
+	carrier, ok := opaqueCarrier.(opentracing.TextMapWriter)
+	if !ok {
+		return opentracing.ErrInvalidCarrier
+	}
+	carrier.Set(fieldNameTraceID, strconv.FormatUint(sc.TraceID, 16))
+	carrier.Set(fieldNameSpanID, strconv.FormatUint(sc.SpanID, 16))
+	carrier.Set(fieldNameSampled, strconv.FormatBool(sc.Sampled))
+
+	for k, v := range sc.Baggage {
+		carrier.Set(prefixBaggage+k, v)
+	}
+	return nil
+}
+
+func (p *textMapPropagator) Extract(
+	opaqueCarrier interface{},
+) (opentracing.SpanContext, error) {
+	carrier, ok := opaqueCarrier.(opentracing.TextMapReader)
+	if !ok {
+		return nil, opentracing.ErrInvalidCarrier
+	}
+	requiredFieldCount := 0
+	var traceID, spanID uint64
+	var sampled bool
+	var err error
+	decodedBaggage := make(map[string]string)
+	err = carrier.ForeachKey(func(k, v string) error {
+		switch strings.ToLower(k) {
+		case fieldNameTraceID:
+			traceID, err = strconv.ParseUint(v, 16, 64)
+			if err != nil {
+				return opentracing.ErrSpanContextCorrupted
+			}
+		case fieldNameSpanID:
+			spanID, err = strconv.ParseUint(v, 16, 64)
+			if err != nil {
+				return opentracing.ErrSpanContextCorrupted
+			}
+		case fieldNameSampled:
+			sampled, err = strconv.ParseBool(v)
+			if err != nil {
+				return opentracing.ErrSpanContextCorrupted
+			}
+		default:
+			lowercaseK := strings.ToLower(k)
+			if strings.HasPrefix(lowercaseK, prefixBaggage) {
+				decodedBaggage[strings.TrimPrefix(lowercaseK, prefixBaggage)] = v
+			}
+			// Balance off the requiredFieldCount++ just below...
+			requiredFieldCount--
+		}
+		requiredFieldCount++
+		return nil
+	})
+	if err != nil {
+		return nil, err
+	}
+	if requiredFieldCount < tracerStateFieldCount {
+		if requiredFieldCount == 0 {
+			return nil, opentracing.ErrSpanContextNotFound
+		}
+		return nil, opentracing.ErrSpanContextCorrupted
+	}
+
+	return SpanContext{
+		TraceID: traceID,
+		SpanID:  spanID,
+		Sampled: sampled,
+		Baggage: decodedBaggage,
+	}, nil
+}
+
+func (p *binaryPropagator) Inject(
+	spanContext opentracing.SpanContext,
+	opaqueCarrier interface{},
+) error {
+	sc, ok := spanContext.(SpanContext)
+	if !ok {
+		return opentracing.ErrInvalidSpanContext
+	}
+	carrier, ok := opaqueCarrier.(io.Writer)
+	if !ok {
+		return opentracing.ErrInvalidCarrier
+	}
+
+	state := wire.TracerState{}
+	state.TraceId = sc.TraceID
+	state.SpanId = sc.SpanID
+	state.Sampled = sc.Sampled
+	state.BaggageItems = sc.Baggage
+
+	b, err := proto.Marshal(&state)
+	if err != nil {
+		return err
+	}
+
+	// Write the length of the marshalled binary to the writer.
+	length := uint32(len(b))
+	if err := binary.Write(carrier, binary.BigEndian, &length); err != nil {
+		return err
+	}
+
+	_, err = carrier.Write(b)
+	return err
+}
+
+func (p *binaryPropagator) Extract(
+	opaqueCarrier interface{},
+) (opentracing.SpanContext, error) {
+	carrier, ok := opaqueCarrier.(io.Reader)
+	if !ok {
+		return nil, opentracing.ErrInvalidCarrier
+	}
+
+	// Read the length of marshalled binary. io.ReadAll isn't that performant
+	// since it keeps resizing the underlying buffer as it encounters more bytes
+	// to read. By reading the length, we can allocate a fixed sized buf and read
+	// the exact amount of bytes into it.
+	var length uint32
+	if err := binary.Read(carrier, binary.BigEndian, &length); err != nil {
+		return nil, opentracing.ErrSpanContextCorrupted
+	}
+	buf := make([]byte, length)
+	if n, err := carrier.Read(buf); err != nil {
+		if n > 0 {
+			return nil, opentracing.ErrSpanContextCorrupted
+		}
+		return nil, opentracing.ErrSpanContextNotFound
+	}
+
+	ctx := wire.TracerState{}
+	if err := proto.Unmarshal(buf, &ctx); err != nil {
+		return nil, opentracing.ErrSpanContextCorrupted
+	}
+
+	return SpanContext{
+		TraceID: ctx.TraceId,
+		SpanID:  ctx.SpanId,
+		Sampled: ctx.Sampled,
+		Baggage: ctx.BaggageItems,
+	}, nil
+}