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// Copyright The OpenTelemetry Authors
// SPDX-License-Identifier: Apache-2.0
package consistent // import "go.opentelemetry.io/contrib/samplers/probability/consistent"
import (
"strings"
"go.opentelemetry.io/otel"
sdktrace "go.opentelemetry.io/otel/sdk/trace"
"go.opentelemetry.io/otel/trace"
)
type (
parentProbabilitySampler struct {
delegate sdktrace.Sampler
}
)
// ParentProbabilityBased is an implementation of the OpenTelemetry
// Trace Sampler interface that provides additional checks for tracestate
// Probability Sampling fields.
func ParentProbabilityBased(root sdktrace.Sampler, samplers ...sdktrace.ParentBasedSamplerOption) sdktrace.Sampler {
return &parentProbabilitySampler{
delegate: sdktrace.ParentBased(root, samplers...),
}
}
// ShouldSample implements "go.opentelemetry.io/otel/sdk/trace".Sampler.
func (p *parentProbabilitySampler) ShouldSample(params sdktrace.SamplingParameters) sdktrace.SamplingResult {
psc := trace.SpanContextFromContext(params.ParentContext)
// Note: We do not check psc.IsValid(), i.e., we repair the tracestate
// with or without a parent TraceId and SpanId.
state := psc.TraceState()
otts, err := parseOTelTraceState(state.Get(traceStateKey), psc.IsSampled())
if err != nil {
otel.Handle(err)
value := otts.serialize()
if len(value) > 0 {
// Note: see the note in
// "go.opentelemetry.io/otel/trace".TraceState.Insert(). The
// error below is not a condition we're supposed to handle.
state, _ = state.Insert(traceStateKey, value)
} else {
state = state.Delete(traceStateKey)
}
// Fix the broken tracestate before calling the delegate.
params.ParentContext = trace.ContextWithSpanContext(params.ParentContext, psc.WithTraceState(state))
}
return p.delegate.ShouldSample(params)
}
// Description returns the same description as the built-in
// ParentBased sampler, with "ParentBased" replaced by
// "ParentProbabilityBased".
func (p *parentProbabilitySampler) Description() string {
return "ParentProbabilityBased" + strings.TrimPrefix(p.delegate.Description(), "ParentBased")
}
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