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// Copyright The OpenTelemetry Authors
// SPDX-License-Identifier: Apache-2.0
package sdk
import (
"context"
"time"
"go.opentelemetry.io/otel/trace"
"go.opentelemetry.io/otel/trace/noop"
"go.opentelemetry.io/auto/sdk/internal/telemetry"
)
type tracer struct {
noop.Tracer
name, schemaURL, version string
}
var _ trace.Tracer = tracer{}
func (t tracer) Start(ctx context.Context, name string, opts ...trace.SpanStartOption) (context.Context, trace.Span) {
var psc trace.SpanContext
sampled := true
span := new(span)
// Ask eBPF for sampling decision and span context info.
t.start(ctx, span, &psc, &sampled, &span.spanContext)
span.sampled.Store(sampled)
ctx = trace.ContextWithSpan(ctx, span)
if sampled {
// Only build traces if sampled.
cfg := trace.NewSpanStartConfig(opts...)
span.traces, span.span = t.traces(name, cfg, span.spanContext, psc)
}
return ctx, span
}
// Expected to be implemented in eBPF.
//
//go:noinline
func (t *tracer) start(
ctx context.Context,
spanPtr *span,
psc *trace.SpanContext,
sampled *bool,
sc *trace.SpanContext,
) {
start(ctx, spanPtr, psc, sampled, sc)
}
// start is used for testing.
var start = func(context.Context, *span, *trace.SpanContext, *bool, *trace.SpanContext) {}
func (t tracer) traces(name string, cfg trace.SpanConfig, sc, psc trace.SpanContext) (*telemetry.Traces, *telemetry.Span) {
span := &telemetry.Span{
TraceID: telemetry.TraceID(sc.TraceID()),
SpanID: telemetry.SpanID(sc.SpanID()),
Flags: uint32(sc.TraceFlags()),
TraceState: sc.TraceState().String(),
ParentSpanID: telemetry.SpanID(psc.SpanID()),
Name: name,
Kind: spanKind(cfg.SpanKind()),
}
span.Attrs, span.DroppedAttrs = convCappedAttrs(maxSpan.Attrs, cfg.Attributes())
links := cfg.Links()
if limit := maxSpan.Links; limit == 0 {
span.DroppedLinks = uint32(len(links))
} else {
if limit > 0 {
n := max(len(links)-limit, 0)
span.DroppedLinks = uint32(n)
links = links[n:]
}
span.Links = convLinks(links)
}
if t := cfg.Timestamp(); !t.IsZero() {
span.StartTime = cfg.Timestamp()
} else {
span.StartTime = time.Now()
}
return &telemetry.Traces{
ResourceSpans: []*telemetry.ResourceSpans{
{
ScopeSpans: []*telemetry.ScopeSpans{
{
Scope: &telemetry.Scope{
Name: t.name,
Version: t.version,
},
Spans: []*telemetry.Span{span},
SchemaURL: t.schemaURL,
},
},
},
},
}, span
}
func spanKind(kind trace.SpanKind) telemetry.SpanKind {
switch kind {
case trace.SpanKindInternal:
return telemetry.SpanKindInternal
case trace.SpanKindServer:
return telemetry.SpanKindServer
case trace.SpanKindClient:
return telemetry.SpanKindClient
case trace.SpanKindProducer:
return telemetry.SpanKindProducer
case trace.SpanKindConsumer:
return telemetry.SpanKindConsumer
}
return telemetry.SpanKind(0) // undefined.
}
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