97 lines
2.5 KiB
Go
97 lines
2.5 KiB
Go
package tracing
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import (
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"context"
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"fmt"
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"strconv"
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"go.opentelemetry.io/otel/propagation"
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"go.opentelemetry.io/otel/trace"
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)
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const (
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traceIDHeader = "x-frostfs-trace-id"
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spanIDHeader = "x-frostfs-span-id"
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flagsHeader = "x-frostfs-trace-flags"
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)
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const (
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flagsSampled = 1 << iota
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)
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// propagator serializes SpanContext to/from headers.
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// x-frostfs-trace-id - TraceID, 16 bytes, hex-string (32 bytes).
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// x-frostfs-span-id - SpanID, 8 bytes, hexstring (16 bytes).
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// x-frostfs-trace-flags - trace flags (now sampled only).
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type propagator struct{}
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// Propagator is propagation.TextMapPropagator instance, used to extract/inject trace info from/to remote context.
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var Propagator propagation.TextMapPropagator = &propagator{}
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// Inject injects tracing info to carrier.
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func (p *propagator) Inject(ctx context.Context, carrier propagation.TextMapCarrier) {
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sc := trace.SpanFromContext(ctx).SpanContext()
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if !sc.TraceID().IsValid() || !sc.SpanID().IsValid() {
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return
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}
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var flags int
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if sc.IsSampled() {
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flags = flags | flagsSampled
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}
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carrier.Set(traceIDHeader, sc.TraceID().String())
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carrier.Set(spanIDHeader, sc.SpanID().String())
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carrier.Set(flagsHeader, fmt.Sprintf("%x", flags))
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}
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// Extract extracts tracing info from carrier and returns context with tracing info.
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// In case of error returns ctx.
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func (p *propagator) Extract(ctx context.Context, carrier propagation.TextMapCarrier) context.Context {
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spanConfig := trace.SpanContextConfig{}
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var err error
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traceIDStr := carrier.Get(traceIDHeader)
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traceIDDefined := false
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if traceIDStr != "" {
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traceIDDefined = true
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spanConfig.TraceID, err = trace.TraceIDFromHex(traceIDStr)
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if err != nil {
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return ctx
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}
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}
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spanIDstr := carrier.Get(spanIDHeader)
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spanIDDefined := false
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if spanIDstr != "" {
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spanIDDefined = true
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spanConfig.SpanID, err = trace.SpanIDFromHex(spanIDstr)
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if err != nil {
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return ctx
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}
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}
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if traceIDDefined != spanIDDefined {
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return ctx //traceID + spanID must be defined OR no traceID and no spanID
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}
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flagsStr := carrier.Get(flagsHeader)
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if flagsStr != "" {
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var v int64
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v, err = strconv.ParseInt(flagsStr, 16, 32)
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if err != nil {
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return ctx
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}
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if v&flagsSampled == flagsSampled {
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spanConfig.TraceFlags = trace.FlagsSampled
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}
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}
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return trace.ContextWithRemoteSpanContext(ctx, trace.NewSpanContext(spanConfig))
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}
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// Fields returns the keys whose values are set with Inject.
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func (p *propagator) Fields() []string {
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return []string{traceIDHeader, spanIDHeader, flagsHeader}
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}
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