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mirror of https://github.com/open-telemetry/opentelemetry-go.git synced 2024-12-16 10:19:23 +02:00
opentelemetry-go/api/trace/b3_propagator.go
2020-05-06 11:09:41 -04:00

217 lines
4.8 KiB
Go

// 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 trace
import (
"context"
"fmt"
"strings"
"go.opentelemetry.io/otel/api/propagation"
)
const (
B3SingleHeader = "X-B3"
B3DebugFlagHeader = "X-B3-Flags"
B3TraceIDHeader = "X-B3-TraceId"
B3SpanIDHeader = "X-B3-SpanId"
B3SampledHeader = "X-B3-Sampled"
B3ParentSpanIDHeader = "X-B3-ParentSpanId"
b3TraceIDPadding = "0000000000000000"
)
// B3 propagator serializes SpanContext to/from B3 Headers.
// This propagator supports both version of B3 headers,
// 1. Single Header :
// X-B3: {TraceId}-{SpanId}-{SamplingState}-{ParentSpanId}
// 2. Multiple Headers:
// X-B3-TraceId: {TraceId}
// X-B3-ParentSpanId: {ParentSpanId}
// X-B3-SpanId: {SpanId}
// X-B3-Sampled: {SamplingState}
// X-B3-Flags: {DebugFlag}
//
// If SingleHeader is set to true then X-B3 header is used to inject and extract. Otherwise,
// separate headers are used to inject and extract.
type B3 struct {
SingleHeader bool
}
var _ propagation.HTTPPropagator = B3{}
func (b3 B3) Inject(ctx context.Context, supplier propagation.HTTPSupplier) {
sc := SpanFromContext(ctx).SpanContext()
if !sc.IsValid() {
return
}
if b3.SingleHeader {
sampled := sc.TraceFlags & FlagsSampled
supplier.Set(B3SingleHeader,
fmt.Sprintf("%s-%s-%.1d", sc.TraceID, sc.SpanID, sampled))
} else {
supplier.Set(B3TraceIDHeader, sc.TraceID.String())
supplier.Set(B3SpanIDHeader, sc.SpanID.String())
var sampled string
if sc.IsSampled() {
sampled = "1"
} else {
sampled = "0"
}
supplier.Set(B3SampledHeader, sampled)
}
}
// Extract retrieves B3 Headers from the supplier
func (b3 B3) Extract(ctx context.Context, supplier propagation.HTTPSupplier) context.Context {
var sc SpanContext
if b3.SingleHeader {
sc = b3.extractSingleHeader(supplier)
} else {
sc = b3.extract(supplier)
}
if !sc.IsValid() {
return ctx
}
return ContextWithRemoteSpanContext(ctx, sc)
}
func fixB3TID(in string) string {
if len(in) == 16 {
in = b3TraceIDPadding + in
}
return in
}
func (b3 B3) extract(supplier propagation.HTTPSupplier) SpanContext {
tid, err := IDFromHex(fixB3TID(supplier.Get(B3TraceIDHeader)))
if err != nil {
return EmptySpanContext()
}
sid, err := SpanIDFromHex(supplier.Get(B3SpanIDHeader))
if err != nil {
return EmptySpanContext()
}
sampled, ok := b3.extractSampledState(supplier.Get(B3SampledHeader))
if !ok {
return EmptySpanContext()
}
debug, ok := b3.extracDebugFlag(supplier.Get(B3DebugFlagHeader))
if !ok {
return EmptySpanContext()
}
if debug == FlagsSampled {
sampled = FlagsSampled
}
sc := SpanContext{
TraceID: tid,
SpanID: sid,
TraceFlags: sampled,
}
if !sc.IsValid() {
return EmptySpanContext()
}
return sc
}
func (b3 B3) extractSingleHeader(supplier propagation.HTTPSupplier) SpanContext {
h := supplier.Get(B3SingleHeader)
if h == "" || h == "0" {
return EmptySpanContext()
}
sc := SpanContext{}
parts := strings.Split(h, "-")
l := len(parts)
if l > 4 {
return EmptySpanContext()
}
if l < 2 {
return EmptySpanContext()
}
var err error
sc.TraceID, err = IDFromHex(fixB3TID(parts[0]))
if err != nil {
return EmptySpanContext()
}
sc.SpanID, err = SpanIDFromHex(parts[1])
if err != nil {
return EmptySpanContext()
}
if l > 2 {
var ok bool
sc.TraceFlags, ok = b3.extractSampledState(parts[2])
if !ok {
return EmptySpanContext()
}
}
if l == 4 {
_, err = SpanIDFromHex(parts[3])
if err != nil {
return EmptySpanContext()
}
}
if !sc.IsValid() {
return EmptySpanContext()
}
return sc
}
// extractSampledState parses the value of the X-B3-Sampled b3Header.
func (b3 B3) extractSampledState(sampled string) (flag byte, ok bool) {
switch sampled {
case "", "0":
return 0, true
case "1":
return FlagsSampled, true
case "true":
if !b3.SingleHeader {
return FlagsSampled, true
}
case "d":
if b3.SingleHeader {
return FlagsSampled, true
}
}
return 0, false
}
// extracDebugFlag parses the value of the X-B3-Sampled b3Header.
func (b3 B3) extracDebugFlag(debug string) (flag byte, ok bool) {
switch debug {
case "", "0":
return 0, true
case "1":
return FlagsSampled, true
}
return 0, false
}
func (b3 B3) GetAllKeys() []string {
if b3.SingleHeader {
return []string{B3SingleHeader}
}
return []string{B3TraceIDHeader, B3SpanIDHeader, B3SampledHeader}
}