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// Copyright The OpenTelemetry Authors
// SPDX-License-Identifier: Apache-2.0
package telemetry
import (
"encoding/hex"
"errors"
"fmt"
)
const (
traceIDSize = 16
spanIDSize = 8
)
// TraceID is a custom data type that is used for all trace IDs.
type TraceID [traceIDSize]byte
// String returns the hex string representation form of a TraceID.
func (tid TraceID) String() string {
return hex.EncodeToString(tid[:])
}
// IsEmpty returns false if id contains at least one non-zero byte.
func (tid TraceID) IsEmpty() bool {
return tid == [traceIDSize]byte{}
}
// MarshalJSON converts the trace ID into a hex string enclosed in quotes.
func (tid TraceID) MarshalJSON() ([]byte, error) {
if tid.IsEmpty() {
return []byte(`""`), nil
}
return marshalJSON(tid[:])
}
// UnmarshalJSON inflates the trace ID from hex string, possibly enclosed in
// quotes.
func (tid *TraceID) UnmarshalJSON(data []byte) error {
*tid = [traceIDSize]byte{}
return unmarshalJSON(tid[:], data)
}
// SpanID is a custom data type that is used for all span IDs.
type SpanID [spanIDSize]byte
// String returns the hex string representation form of a SpanID.
func (sid SpanID) String() string {
return hex.EncodeToString(sid[:])
}
// IsEmpty returns true if the span ID contains at least one non-zero byte.
func (sid SpanID) IsEmpty() bool {
return sid == [spanIDSize]byte{}
}
// MarshalJSON converts span ID into a hex string enclosed in quotes.
func (sid SpanID) MarshalJSON() ([]byte, error) {
if sid.IsEmpty() {
return []byte(`""`), nil
}
return marshalJSON(sid[:])
}
// UnmarshalJSON decodes span ID from hex string, possibly enclosed in quotes.
func (sid *SpanID) UnmarshalJSON(data []byte) error {
*sid = [spanIDSize]byte{}
return unmarshalJSON(sid[:], data)
}
// marshalJSON converts id into a hex string enclosed in quotes.
func marshalJSON(id []byte) ([]byte, error) {
// Plus 2 quote chars at the start and end.
hexLen := hex.EncodedLen(len(id)) + 2
b := make([]byte, hexLen)
hex.Encode(b[1:hexLen-1], id)
b[0], b[hexLen-1] = '"', '"'
return b, nil
}
// unmarshalJSON inflates trace id from hex string, possibly enclosed in quotes.
func unmarshalJSON(dst []byte, src []byte) error {
if l := len(src); l >= 2 && src[0] == '"' && src[l-1] == '"' {
src = src[1 : l-1]
}
nLen := len(src)
if nLen == 0 {
return nil
}
if len(dst) != hex.DecodedLen(nLen) {
return errors.New("invalid length for ID")
}
_, err := hex.Decode(dst, src)
if err != nil {
return fmt.Errorf("cannot unmarshal ID from string '%s': %w", string(src), err)
}
return nil
}
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