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// Copyright The OpenTelemetry Authors
// SPDX-License-Identifier: Apache-2.0
package trace // import "go.opentelemetry.io/otel/sdk/trace"
import (
"errors"
"fmt"
"os"
"strconv"
"strings"
)
const (
tracesSamplerKey = "OTEL_TRACES_SAMPLER"
tracesSamplerArgKey = "OTEL_TRACES_SAMPLER_ARG"
samplerAlwaysOn = "always_on"
samplerAlwaysOff = "always_off"
samplerTraceIDRatio = "traceidratio"
samplerParentBasedAlwaysOn = "parentbased_always_on"
samplerParsedBasedAlwaysOff = "parentbased_always_off"
samplerParentBasedTraceIDRatio = "parentbased_traceidratio"
)
type errUnsupportedSampler string
func (e errUnsupportedSampler) Error() string {
return fmt.Sprintf("unsupported sampler: %s", string(e))
}
var (
errNegativeTraceIDRatio = errors.New("invalid trace ID ratio: less than 0.0")
errGreaterThanOneTraceIDRatio = errors.New("invalid trace ID ratio: greater than 1.0")
)
type samplerArgParseError struct {
parseErr error
}
func (e samplerArgParseError) Error() string {
return fmt.Sprintf("parsing sampler argument: %s", e.parseErr.Error())
}
func (e samplerArgParseError) Unwrap() error {
return e.parseErr
}
func samplerFromEnv() (Sampler, error) {
sampler, ok := os.LookupEnv(tracesSamplerKey)
if !ok {
return nil, nil
}
sampler = strings.ToLower(strings.TrimSpace(sampler))
samplerArg, hasSamplerArg := os.LookupEnv(tracesSamplerArgKey)
samplerArg = strings.TrimSpace(samplerArg)
switch sampler {
case samplerAlwaysOn:
return AlwaysSample(), nil
case samplerAlwaysOff:
return NeverSample(), nil
case samplerTraceIDRatio:
if !hasSamplerArg {
return TraceIDRatioBased(1.0), nil
}
return parseTraceIDRatio(samplerArg)
case samplerParentBasedAlwaysOn:
return ParentBased(AlwaysSample()), nil
case samplerParsedBasedAlwaysOff:
return ParentBased(NeverSample()), nil
case samplerParentBasedTraceIDRatio:
if !hasSamplerArg {
return ParentBased(TraceIDRatioBased(1.0)), nil
}
ratio, err := parseTraceIDRatio(samplerArg)
return ParentBased(ratio), err
default:
return nil, errUnsupportedSampler(sampler)
}
}
func parseTraceIDRatio(arg string) (Sampler, error) {
v, err := strconv.ParseFloat(arg, 64)
if err != nil {
return TraceIDRatioBased(1.0), samplerArgParseError{err}
}
if v < 0.0 {
return TraceIDRatioBased(1.0), errNegativeTraceIDRatio
}
if v > 1.0 {
return TraceIDRatioBased(1.0), errGreaterThanOneTraceIDRatio
}
return TraceIDRatioBased(v), nil
}
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