[TOC] ## rpcx 调用 [通过 conetxt ] [rpcx_jaeger [master] ](https://github.com/idcpj/rpcx_jaeger) 核心代码,实现与 zipkin 还是稍有不同 ``` func GenerateSpanWithContext(ctx context.Context, operationName string) (opentracing.Span, context.Context, error) { md := ctx.Value(share.ReqMetaDataKey) // share.ReqMetaDataKey 固定值 "__req_metadata" 可自定义 var span opentracing.Span tracer := opentracing.GlobalTracer() if md != nil { carrier := opentracing.TextMapCarrier(md.(map[string]string)) spanContext, err := tracer.Extract(opentracing.TextMap, carrier) if err != nil && err != opentracing.ErrSpanContextNotFound { log.Printf("metadata error %s\n", err) return nil, nil, err } span = tracer.StartSpan(operationName, ext.RPCServerOption(spanContext)) } else { span = opentracing.StartSpan(operationName) } metadata := opentracing.TextMapCarrier(make(map[string]string)) err := tracer.Inject(span.Context(), opentracing.TextMap, metadata) if err != nil { return nil, nil, err } //把metdata 携带的 traceid,spanid,parentSpanid 放入 context ctx = context.WithValue(context.Background(), share.ReqMetaDataKey, (map[string]string)(metadata)) return span, ctx, nil } ```