24.把熔断器整合到我们的客户端代码中(初步)

熔断器一般部署在客户端或者网关里面

封装到服务端

package main

import (
    "fmt"
    "github.com/afex/hystrix-go/hystrix"
    "gomicro2/util"
    "log"
    "time"
)



func main() {
    configA := hystrix.CommandConfig{
        Timeout:                2000,
        MaxConcurrentRequests:  5,
        RequestVolumeThreshold: 3,
        SleepWindow:            int(time.Second * 10),
        ErrorPercentThreshold:  20,
    }

    hystrix.ConfigureCommand("getuser", configA)
    err := hystrix.Do("getuser", func() error {
        res, err := util.GetUser() //调用方法
        fmt.Println(res)
        return err
    }, func(e error) error {
        fmt.Println("降级用户")
        return e
    })
    if err != nil {
        log.Fatal(err)
    }
}

Util.GetUser

package util

import (
    "context"
    "fmt"
    "github.com/go-kit/kit/endpoint"
    "github.com/go-kit/kit/log"
    "github.com/go-kit/kit/sd"
    "github.com/go-kit/kit/sd/consul"
    "github.com/go-kit/kit/sd/lb"
    httptransport "github.com/go-kit/kit/transport/http"
    consulapi "github.com/hashicorp/consul/api"
    "gomicro2/Services"
    "io"
    "net/url"
    "os"
    "time"
)

func GetUser() (string, error) {
    //第一步创建client
    {
        config := consulapi.DefaultConfig()            //初始化consul的配置
        config.Address = "localhost:8500"              //consul的地址
        api_client, err := consulapi.NewClient(config) //根据consul的配置初始化client
        if err != nil {
            return "", err
        }
        client := consul.NewClient(api_client) //根据client创建实例

        var logger log.Logger
        {
            logger = log.NewLogfmtLogger(os.Stdout)
            var Tag = []string{"primary"}
            instancer := consul.NewInstancer(client, logger, "userservice", Tag, true) //最后的true表示只有通过健康检查的服务才能被得到
            {
                factory := func(service_url string) (endpoint.Endpoint, io.Closer, error) { //factory定义了如何获得服务端的endpoint,这里的service_url是从consul中读取到的service的address我这里是192.168.3.14:8000
                    tart, _ := url.Parse("http://" + service_url)                                                                                 //server ip +8080真实服务的地址
                    return httptransport.NewClient("GET", tart, Services.GetUserInfo_Request, Services.GetUserInfo_Response).Endpoint(), nil, nil //我再GetUserInfo_Request里面定义了访问哪一个api把url拼接成了http://192.168.3.14:8000/v1/user/{uid}的形式
                }
                endpointer := sd.NewEndpointer(instancer, factory, logger)
                endpoints, err := endpointer.Endpoints() //获取所有的服务端当前server的所有endpoint函数
                if err != nil {
                    return "", err
                }
                fmt.Println("服务有", len(endpoints), "条")

                mylb := lb.NewRandom(endpointer, time.Now().UnixNano()) //使用go-kit自带的轮询

                for {
                    getUserInfo, err := mylb.Endpoint() //写死获取第一个
                    ctx := context.Background()         //第三步：创建一个context上下文对象

                    //第四步：执行
                    res, err := getUserInfo(ctx, Services.UserRequest{Uid: 101})
                    if err != nil {
                        return "", err
                    }
                    //第五步：断言，得到响应值
                    userinfo := res.(Services.UserResponse)
                    return userinfo.Result, nil
                }

            }
        }
    }
}

来自为知笔记(Wiz)