我使用的是rpcx+etcd+xorm在这个基础上给我加上opentelemetry，给我写出代码-DPDK中文网

以下是一个使用rpcx+etcd+xorm并添加opentelemetry的示例代码：

package main

import (
	"context"
	"fmt"
	"log"
	"time"

	"github.com/opentracing/opentracing-go"
	"github.com/opentracing/opentracing-go/ext"
	"github.com/opentracing/opentracing-go/log"

	"github.com/smallnest/rpcx/client"
	rpcxContext "github.com/smallnest/rpcx/context"

	"go.etcd.io/etcd/clientv3"
	"xorm.io/xorm"
)

func main() {
	ctx := context.Background()

	tracer, closer, err := initTracer()
	if err != nil {
		log.Fatalf("Failed to initialize tracer: %v", err)
	}
	defer closer.Close()

	opentracing.SetGlobalTracer(tracer)

	cli, err := clientv3.New(clientv3.Config{
		Endpoints:   []string{"localhost:2379"},
		DialTimeout: 5 * time.Second,
	})
	if err != nil {
		log.Fatalf("Failed to create etcd client: %v", err)
	}
	defer cli.Close()

	engine, err := xorm.NewEngine("mysql", "user:password@tcp(127.0.0.1:3306)/database?charset=utf8mb4")
	if err != nil {
	    log.Fatalf("Failed to create XORM engine: %v", err)
    }
	defer engine.Close()

	client := client.NewEtcdV3DiscoveryClient("serviceName", "/rpcx/", []string{"localhost:2379"}, nil)
	xclient := client.NewXClient("ServiceMethod", client.Failtry, client.RandomSelect, cli)

	err = opentracing.GlobalTracer().Inject(
        span.Context(),
        opentracing.TextMap,
        rpcxContext.HeaderCarrier(metadata))
    if err != nil {
        log.Printf("Failed to inject span context into RPC metadata: %v", err)
    }

	err = xclient.Call(ctx, "ServiceMethod", args, reply)
	if err != nil {
		log.Fatalf("Failed to call remote service: %v", err)
	}

	span := opentracing.SpanFromContext(ctx)

	defer span.Finish()

	fmt.Printf("RPC result: %+v\n", reply)
}

func initTracer() (opentracing.Tracer, io.Closer, error) {
	cfg := config.NewConfig(
		config.WithSampler(config.AlwaysSample()),
		config.WithReporter(
			reporter.NewLogReporter(),
		),
	)

	tracer, closer, err := cfg.NewTracer()
	if err != nil {
		return nil, nil, fmt.Errorf("failed to create Jaeger tracer: %w", err)
	}

	return tracer, closer, nil
}

请根据实际情况调整代码中的服务名称、地址、数据库连接等参数。这个示例中使用了rpcx作为远程过程调用框架，etcd作为服务发现和配置存储，xorm作为ORM框架，并结合opentelemetry进行分布式跟踪。

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