1// Copyright (c) 2017 Uber Technologies, Inc.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7// http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15package jaeger
16
17import (
18	"github.com/opentracing/opentracing-go"
19)
20
21// ZipkinSpanFormat is an OpenTracing carrier format constant
22const ZipkinSpanFormat = "zipkin-span-format"
23
24// ExtractableZipkinSpan is a type of Carrier used for integration with Zipkin-aware
25// RPC frameworks (like TChannel). It does not support baggage, only trace IDs.
26type ExtractableZipkinSpan interface {
27	TraceID() uint64
28	SpanID() uint64
29	ParentID() uint64
30	Flags() byte
31}
32
33// InjectableZipkinSpan is a type of Carrier used for integration with Zipkin-aware
34// RPC frameworks (like TChannel). It does not support baggage, only trace IDs.
35type InjectableZipkinSpan interface {
36	SetTraceID(traceID uint64)
37	SetSpanID(spanID uint64)
38	SetParentID(parentID uint64)
39	SetFlags(flags byte)
40}
41
42type zipkinPropagator struct {
43	tracer *Tracer
44}
45
46func (p *zipkinPropagator) Inject(
47	ctx SpanContext,
48	abstractCarrier interface{},
49) error {
50	carrier, ok := abstractCarrier.(InjectableZipkinSpan)
51	if !ok {
52		return opentracing.ErrInvalidCarrier
53	}
54
55	carrier.SetTraceID(ctx.TraceID().Low) // TODO this cannot work with 128bit IDs
56	carrier.SetSpanID(uint64(ctx.SpanID()))
57	carrier.SetParentID(uint64(ctx.ParentID()))
58	carrier.SetFlags(ctx.samplingState.flags())
59	return nil
60}
61
62func (p *zipkinPropagator) Extract(abstractCarrier interface{}) (SpanContext, error) {
63	carrier, ok := abstractCarrier.(ExtractableZipkinSpan)
64	if !ok {
65		return emptyContext, opentracing.ErrInvalidCarrier
66	}
67	if carrier.TraceID() == 0 {
68		return emptyContext, opentracing.ErrSpanContextNotFound
69	}
70	var ctx SpanContext
71	ctx.traceID.Low = carrier.TraceID()
72	ctx.spanID = SpanID(carrier.SpanID())
73	ctx.parentID = SpanID(carrier.ParentID())
74	ctx.samplingState = &samplingState{}
75	ctx.samplingState.setFlags(carrier.Flags())
76	return ctx, nil
77}
78