package logs

import (

"context"

"unsafe"

)

// go clean -testcache // Delete all cached test results

const (

traceStr = "23456789abcdefghijkmnpqrstuvwxyz" //32

traceMask = 1<<5 - 1 //11111

traceSize = 8 //6-12

)

func trace() string {

buf := make([]byte, traceSize)

for idx, cache := 0, fastrand(); idx < traceSize; {

buf[idx] = traceStr[cache&traceMask]

cache >>= 5

idx++

}

return unsafe.String(&buf[0], len(buf))

}

func TraceId() string {

return trace()

}

func TraceOf(ctx context.Context) string {

traceId, _ := ctx.Value(traceKey).(string)

return traceId

}

//go:linkname fastrand runtime.fastrand64

func fastrand() uint64

const traceKey = "zlogs-trace-key"

// TraceCtx 处理traceid并返回新的context

// 1. ctx存在traceid，traceid参数不存在/为空 → 复用原有traceid

// 2. ctx不存在traceid → 使用新值（传入的traceid或生成新的）

// 3. ctx存在traceid且traceid参数存在 → 追加（原有值.新traceid）

func TraceCtx(ctx context.Context, traceid ...string) context.Context {

ntraceid := ""

if len(traceid) > 0 {

ntraceid = traceid[0]

}

otraceid, _ := ctx.Value(traceKey).(string)

ftraceid := ""

if otraceid == "" {

if ntraceid == "" {

ntraceid = trace()

}

ftraceid = ntraceid

} else {

if ntraceid == "" {

ftraceid = otraceid

} else {

ftraceid = otraceid + "." + ntraceid

}

}

return context.WithValue(ctx, traceKey, ftraceid)

}