/
tracedata.go
70 lines (57 loc) · 1.65 KB
/
tracedata.go
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package tracedata
import (
"fmt"
"math/rand"
"net/http"
"golang.org/x/net/context"
)
const (
// Tracing headers like in Zipkin (http://zipkin.io/)
TraceIDHeader = "X-Trace-ID"
SpanIDHeader = "X-Span-ID"
ParentSpanIDHeader = "X-Parent-Span-ID"
)
type dataCtxKeyType int
const dataCtxKey dataCtxKeyType = 0
type TraceData struct {
TraceID string
SpanID string
ParentSpanID string
}
// TraceFromContext returns data from request
func GetTraceDataFromRequest(req *http.Request) *TraceData {
traceID := req.Header.Get(TraceIDHeader)
spanID := req.Header.Get(SpanIDHeader)
parentSpanID := req.Header.Get(ParentSpanIDHeader)
if traceID == "" {
traceID = generate()
spanID = traceID
} else if spanID == "" {
spanID = generate()
}
return &TraceData{
TraceID: traceID,
SpanID: spanID,
ParentSpanID: parentSpanID,
}
}
// SetTraceDataToRequest sets data to request
func SetTraceDataToRequest(data *TraceData, req *http.Request) {
req.Header.Set(TraceIDHeader, data.TraceID)
req.Header.Set(SpanIDHeader, "") // if we do not send spanID then child service will generate spanID
req.Header.Set(ParentSpanIDHeader, data.SpanID)
}
// SetTraceDataToContext creates new child context with given trace data
func SetTraceDataToContext(ctx context.Context, data *TraceData) context.Context {
return context.WithValue(ctx, dataCtxKey, data)
}
// GetTraceDataFromContext gets trace data from given context
func GetTraceDataFromContext(ctx context.Context) *TraceData {
if result, ok := ctx.Value(dataCtxKey).(*TraceData); ok {
return result
}
return &TraceData{}
}
func generate() string {
return fmt.Sprintf("%X", rand.Int63())
}