/
binary.go
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/
binary.go
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// Copyright The OpenTelemetry Authors
//
// 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 opencensus // import "go.opentelemetry.io/contrib/propagators/opencensus"
import (
"context"
ocpropagation "go.opencensus.io/trace/propagation"
"go.opentelemetry.io/otel/bridge/opencensus"
"go.opentelemetry.io/otel/propagation"
"go.opentelemetry.io/otel/trace"
)
type key uint
const binaryKey key = 0
// binaryHeader is the same as traceContextKey is in opencensus:
// https://github.com/census-instrumentation/opencensus-go/blob/3fb168f674736c026e623310bfccb0691e6dec8a/plugin/ocgrpc/trace_common.go#L30
const binaryHeader = "grpc-trace-bin"
// Binary is an OpenTelemetry implementation of the OpenCensus grpc binary format.
// Binary propagation was temporarily removed from opentelemetry. See
// https://github.com/open-telemetry/opentelemetry-specification/issues/437
type Binary struct{}
var _ propagation.TextMapPropagator = Binary{}
// Inject injects context into the TextMapCarrier
func (b Binary) Inject(ctx context.Context, carrier propagation.TextMapCarrier) {
binaryContext := ctx.Value(binaryKey)
if state, ok := binaryContext.(string); binaryContext != nil && ok {
carrier.Set(binaryHeader, state)
}
sc := trace.SpanContextFromContext(ctx)
if !sc.IsValid() {
return
}
h := ocpropagation.Binary(opencensus.OTelSpanContextToOC(sc))
carrier.Set(binaryHeader, string(h))
}
// Extract extracts the SpanContext from the TextMapCarrier
func (b Binary) Extract(ctx context.Context, carrier propagation.TextMapCarrier) context.Context {
state := carrier.Get(binaryHeader)
if state != "" {
ctx = context.WithValue(ctx, binaryKey, state)
}
sc := b.extract(carrier)
if !sc.IsValid() {
return ctx
}
return trace.ContextWithRemoteSpanContext(ctx, sc)
}
func (b Binary) extract(carrier propagation.TextMapCarrier) trace.SpanContext {
h := carrier.Get(binaryHeader)
if h == "" {
return trace.SpanContext{}
}
ocContext, ok := ocpropagation.FromBinary([]byte(h))
if !ok {
return trace.SpanContext{}
}
return opencensus.OCSpanContextToOTel(ocContext)
}
// Fields returns the fields that this propagator modifies.
func (b Binary) Fields() []string {
return []string{binaryHeader}
}