Merge pull request #148 from basvanbeek/master

add TextMapReader and TextMapWriter compatibility

Author: basvanbeek

go.mod

@@ -6,7 +6,7 @@ require (
 	github.com/gorilla/mux v1.7.3 // indirect
 	github.com/opentracing-contrib/go-observer v0.0.0-20170622124052-a52f23424492
 	github.com/opentracing/opentracing-go v1.1.0
-	github.com/openzipkin/zipkin-go v0.2.0
+	github.com/openzipkin/zipkin-go v0.2.1
 	github.com/stretchr/testify v1.3.0
 	google.golang.org/grpc v1.22.1 // indirect
 )

go.sum

@@ -33,8 +33,8 @@ github.com/opentracing-contrib/go-observer v0.0.0-20170622124052-a52f23424492 h1
 github.com/opentracing-contrib/go-observer v0.0.0-20170622124052-a52f23424492/go.mod h1:Ngi6UdF0k5OKD5t5wlmGhe/EDKPoUM3BXZSSfIuJbis=
 github.com/opentracing/opentracing-go v1.1.0 h1:pWlfV3Bxv7k65HYwkikxat0+s3pV4bsqf19k25Ur8rU=
 github.com/opentracing/opentracing-go v1.1.0/go.mod h1:UkNAQd3GIcIGf0SeVgPpRdFStlNbqXla1AfSYxPUl2o=
-github.com/openzipkin/zipkin-go v0.2.0 h1:33/f6xXB6YlOQ9tgTsXVOkdLCJsHTcZJnMy4DnSd6FU=
-github.com/openzipkin/zipkin-go v0.2.0/go.mod h1:NaW6tEwdmWMaCDZzg8sh+IBNOxHMPnhQw8ySjnjRyN4=
+github.com/openzipkin/zipkin-go v0.2.1 h1:noL5/5Uf1HpVl3wNsfkZhIKbSWCVi5jgqkONNx8PXcA=
+github.com/openzipkin/zipkin-go v0.2.1/go.mod h1:NaW6tEwdmWMaCDZzg8sh+IBNOxHMPnhQw8ySjnjRyN4=
 github.com/pierrec/lz4 v1.0.2-0.20190131084431-473cd7ce01a1/go.mod h1:3/3N9NVKO0jef7pBehbT1qWhCMrIgbYNnFAZCqQ5LRc=
 github.com/pkg/profile v1.2.1/go.mod h1:hJw3o1OdXxsrSjjVksARp5W95eeEaEfptyVZyv6JUPA=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=

propagation.go

@@ -59,6 +59,21 @@ func (p *textMapPropagator) Inject(
 			return b3.InjectHTTP(req)(model.SpanContext(sc))
 		}
 	}
+	// fallback to support native opentracing textmap writer
+	if carrier, ok := opaqueCarrier.(opentracing.TextMapWriter); ok {
+		m := make(b3.Map)
+		switch p.tracer.opts.b3InjectOpt {
+		case B3InjectSingle:
+			m.Inject(b3.WithSingleHeaderOnly())(model.SpanContext(sc))
+		case B3InjectBoth:
+			m.Inject(b3.WithSingleAndMultiHeader())(model.SpanContext(sc))
+		default:
+			m.Inject()(model.SpanContext(sc))
+		}
+		for k, v := range m {
+			carrier.Set(k, v)
+		}
+	}
 
 	return opentracing.ErrInvalidCarrier
 }
@@ -81,6 +96,19 @@ func (p *textMapPropagator) Extract(
 		}
 		return SpanContext{}, err
 	}
+	if carrier, ok := opaqueCarrier.(opentracing.TextMapReader); ok {
+		m := make(b3.Map)
+		carrier.ForeachKey(func(key string, val string) error {
+			m[key] = val
+			return nil
+		})
+		sc, err := m.Extract()
+		if sc != nil {
+			return SpanContext(*sc), err
+		}
+		return SpanContext{}, err
+	}
+
 	return nil, opentracing.ErrUnsupportedFormat
 }