Imported github.com/ardanlabs/service as base example project

example-project/vendor/github.com/openzipkin/zipkin-go/model/traceid.go

@@ -0,0 +1,59 @@
+package model
+
+import (
+	"fmt"
+	"strconv"
+)
+
+// TraceID is a 128 bit number internally stored as 2x uint64 (high & low).
+// In case of 64 bit traceIDs, the value can be found in Low.
+type TraceID struct {
+	High uint64
+	Low  uint64
+}
+
+// Empty returns if TraceID has zero value.
+func (t TraceID) Empty() bool {
+	return t.Low == 0 && t.High == 0
+}
+
+// String outputs the 128-bit traceID as hex string.
+func (t TraceID) String() string {
+	if t.High == 0 {
+		return fmt.Sprintf("%016x", t.Low)
+	}
+	return fmt.Sprintf("%016x%016x", t.High, t.Low)
+}
+
+// TraceIDFromHex returns the TraceID from a hex string.
+func TraceIDFromHex(h string) (t TraceID, err error) {
+	if len(h) > 16 {
+		if t.High, err = strconv.ParseUint(h[0:len(h)-16], 16, 64); err != nil {
+			return
+		}
+		t.Low, err = strconv.ParseUint(h[len(h)-16:], 16, 64)
+		return
+	}
+	t.Low, err = strconv.ParseUint(h, 16, 64)
+	return
+}
+
+// MarshalJSON custom JSON serializer to export the TraceID in the required
+// zero padded hex representation.
+func (t TraceID) MarshalJSON() ([]byte, error) {
+	return []byte(fmt.Sprintf("%q", t.String())), nil
+}
+
+// UnmarshalJSON custom JSON deserializer to retrieve the traceID from the hex
+// encoded representation.
+func (t *TraceID) UnmarshalJSON(traceID []byte) error {
+	if len(traceID) < 3 {
+		return ErrValidTraceIDRequired
+	}
+	tID, err := TraceIDFromHex(string(traceID[1 : len(traceID)-1]))
+	if err != nil {
+		return err
+	}
+	*t = tID
+	return nil
+}