使用wire重构商品微服务

一.wire简介

Wire 是一个轻巧的Golang依赖注入工具。它由Go Cloud团队开发，通过自动生成代码的方式在编译期完成依赖注入。

依赖注入是保持软件 “低耦合、易维护” 的重要设计准则之一。

此准则被广泛应用在各种开发平台之中，有很多与之相关的优秀工具。

其中最著名的当属 Spring，Spring IOC 作为框架的核心功能对Spring的发展到今天统治地位起了决定性作用。

依赖注入很重要，所以Golang社区中早已有人开发了相关工具，比如来自Uber 的 dig 、来自Facebook 的 inject 。他们都通过反射机制实现了运行时依赖注入。

二.快速使用

2.1安装

安装很简单，运行 go get github.com/google/wire/cmd/wire 之后， wire 命令行工具将被安装到 $GOPATH/bin 。只要确保 $GOPATH/bin 在 $PATH 中， wire 命令就可以在任何目录调用了。安装成功后运行如下命令
在这里插入图片描述

2.2快速入门

设计一个程序，其中 Event依赖Greeter，Greeter依赖Message

package mainimport ("fmt""github.com/pkg/errors""time"
)type Message stringfunc NewMessage(phrase string) Message {return Message(phrase)
}type Greeter struct {Message Message
}func NewGreeter(m Message) Greeter {return Greeter{Message: m}
}func (g Greeter) Greet() Message {return g.Message
}type Event struct {Greeter Greeter // <- adding a Greeter field
}func NewEvent(g Greeter) (Event, error) {if time.Now().Unix()%2 == 0 {return Event{}, errors.New("could not create event: event greeter is grumpy")}return Event{Greeter: g}, nil
}func (e Event) Start() {msg := e.Greeter.Greet()fmt.Println(msg)
}

如果运行Event需要逐个构建依赖，代码如下

func main() {message := NewMessage("lisus2000")greeter := NewGreeter(message)event := NewEvent(greeter)event.Start()
}

在此之前先介绍两个概念

Provider
Provider 你可以把它理解成工厂函数，这个函数的入参是依赖的属性，返回值为新一个新的类型实例

如下所示都是 provider 函数，在实际使用的时候，往往是一些简单的工厂函数，这个函数不会太复杂。

func NewMessage() Message {return Message("Hi there!")
}func NewGreeter(m Message) Greeter {return Greeter{Message: m}
}

Injector

我们常常在 wire.go 文件中定义 injector ，injector也是一个普通函数，它用来声明组件之间的依赖关系

如下代码，我们把Event、Greeter、Message 的工厂函数(provider)一股脑塞入wire.Build()中，代表着构建 Event依赖Greeter、Message。我们不必关心Greeter、Message之间的依赖关系，wire会帮我们处理

func InitializeEvent() Event {wire.Build(NewEvent, NewGreeter, NewMessage)return Event{}
}

编写wire.go文件

//go:build wireinject
// +build wireinjectpackage mainimport "github.com/google/wire"var wireSet = wire.NewSet(wire.Struct(new(Greeter), "Message"), NewMessage)func InitializeEvent(phrase string) (Event, error) {//我们常常在 wire.go 文件中定义 injector ，injector也是一个普通函数，它用来声明组件之间的依赖关系//如下代码，我们把Event、Greeter、Message 的工厂函数(provider)一股脑塞入wire.Build()中，//代表着构建 Event依赖Greeter、Message。我们不必关心Greeter、Message之间的依赖关系，wire会帮我们处理panic(wire.Build(NewEvent, wireSet))//return Event{}, nil
}

注：使用wire生成代码时，要在代码上加以下

可以在wire.go第一行加入 //+build wireinject （与//go:build wireinject等效）注释，确保了这个文件在我们正常编译的时候不会被引用

在带有wire.go目录下运行wire命令，就会生成wire_gen.go文件，如下图所示

在这里插入图片描述

完整的main.go文件如下

package mainimport ("fmt""github.com/pkg/errors""time"
)type Message stringfunc NewMessage(phrase string) Message {return Message(phrase)
}type Greeter struct {Message Message
}func NewGreeter(m Message) Greeter {return Greeter{Message: m}
}func (g Greeter) Greet() Message {return g.Message
}type Event struct {Greeter Greeter // <- adding a Greeter field
}func NewEvent(g Greeter) (Event, error) {if time.Now().Unix()%2 == 0 {return Event{}, errors.New("could not create event: event greeter is grumpy")}return Event{Greeter: g}, nil
}func (e Event) Start() {msg := e.Greeter.Greet()fmt.Println(msg)
}func main() {event, _ := InitializeEvent("hello")event.Start()
}

wire的进阶，详见https://blog.csdn.net/weixin_50071922/article/details/133278161

三.基于wire构建商品微服务

3.1编写商品微服务提供者

func NewGoodsAppWire(logOpts *log.Options, registrar registry.Registrar, serverOpts *options.ServerOptions,rpcServer *rpcserver.Server) (*gapp.App, error) {//初始化loglog.Init(logOpts)defer log.Flush()return gapp.New(gapp.WithName(serverOpts.Name),gapp.WithRPCServer(rpcServer),gapp.WithRegistrar(registrar),), nil
}

func NewRegistrar(registry *options.RegistryOptions) registry.Registrar {c := api.DefaultConfig()c.Address = registry.Addressc.Scheme = registry.Schemeclient, err := api.NewClient(c)if err != nil {panic(err)}return consul.New(client, consul.WithHealthCheck(true))
}

func NewGoodsRPCServerWire(telemetry *options.TelemetryOptions,serverOpts *options.ServerOptions, gserver gpb.GoodsServer) (*rpcserver.Server, error) {// 初始化 open-telemetry 的 exportertrace.InitAgent(trace.Options{Name:     telemetry.Name,Endpoint: telemetry.Endpoint,Sampler:  telemetry.Sampler,Batcher:  telemetry.Batcher,})// 这里会根据 endpoint 为单元注册 trace 服务的实例rpcAddr := fmt.Sprintf("%s:%d", serverOpts.Host, serverOpts.Port)var opts []rpcserver.ServerOptionopts = append(opts, rpcserver.WithAddress(rpcAddr))if serverOpts.EnableLimit {opts = append(opts, rpcserver.WithUnaryInterceptor(grpc.NewUnaryServerInterceptor()))}grpcServer := rpcserver.NewServer(opts...)gpb.RegisterGoodsServer(grpcServer.Server, gserver)return grpcServer, nil
}

func NewGoodsServerWire(srv v1.ServiceFactory) proto.GoodsServer {return &goodsServer{srv: srv,}
}

func NewGoodsServiceWire(data v1.DataFactory, dataSearch v12.SearchFactory) ServiceFactory {return &service{data:       data,dataSearch: dataSearch,}
}

func GetDBFactoryOr(mysqlOpts *options.MySQLOptions) (v1.DataFactory, error) {if mysqlOpts == nil && dbFactory == nil {return nil, errors.WithCode(code.ErrConnectDB, "failed to get mysql store factory")}var err erroronce.Do(func() {dsn := fmt.Sprintf("%s:%s@tcp(%s:%s)/%s?charset=utf8mb4&parseTime=True&loc=Local",mysqlOpts.Username,mysqlOpts.Password,mysqlOpts.Host,mysqlOpts.Port,mysqlOpts.Database)//希望大家自己可以去封装loggernewLogger := logger.New(log.New(os.Stdout, "\r\n", log.LstdFlags), // io writer（日志输出的目标，前缀和日志包含的内容——译者注）logger.Config{SlowThreshold:             time.Second,                         // 慢 SQL 阈值LogLevel:                  logger.LogLevel(mysqlOpts.LogLevel), // 日志级别IgnoreRecordNotFoundError: true,                                // 忽略ErrRecordNotFound（记录未找到）错误Colorful:                  false,                               // 禁用彩色打印},)db, err := gorm.Open(mysql.Open(dsn), &gorm.Config{Logger: newLogger,})if err != nil {return}sqlDB, _ := db.DB()dbFactory = &mysqlFactory{db: db,}//允许连接多少个mysqlsqlDB.SetMaxOpenConns(mysqlOpts.MaxOpenConnections)//允许最大的空闲的连接数sqlDB.SetMaxIdleConns(mysqlOpts.MaxIdleConnections)//重用连接的最大时长sqlDB.SetConnMaxLifetime(mysqlOpts.MaxConnectionLifetime)})if dbFactory == nil || err != nil {return nil, errors.WithCode(code.ErrConnectDB, "failed to get mysql store factory")}return dbFactory, nil
}

func GetSearchFactoryOr(opts *options.EsOptions) (v12.SearchFactory, error) {if opts == nil && searchFactory == nil {return nil, errors.New("failed to get es client")}once.Do(func() {esOpt := db.EsOptions{Host: opts.Host,Port: opts.Port,}esClient, err := db.NewEsClient(&esOpt)if err != nil {return}searchFactory = &dataSearch{esClient: esClient,}})if searchFactory == nil {return nil, errors.New("failed to get es client")}return searchFactory, nil
}

3.2编写wire.go文件

//go:build wireinject
// +build wireinjectpackage srvimport ("github.com/google/wire"v1 "mxshop/app/goods/srv/internal/controller/v1""mxshop/app/goods/srv/internal/data/v1/data_search/v1/es""mxshop/app/goods/srv/internal/data/v1/db"v12 "mxshop/app/goods/srv/internal/service/v1""mxshop/app/pkg/options"gapp "mxshop/gmicro/app""mxshop/pkg/log"
)func initApp(*log.Options, *options.ServerOptions, *options.RegistryOptions,*options.TelemetryOptions, *options.MySQLOptions, *options.EsOptions) (*gapp.App, error) {wire.Build(NewGoodsAppWire,NewRegistrar,NewGoodsRPCServerWire,v1.NewGoodsServerWire,v12.NewGoodsServiceWire,db.GetDBFactoryOr,es.GetSearchFactoryOr,)return &gapp.App{}, nil
}

3.3生成wire_gen.go文件

在这里插入图片描述

生成后的文件如下：

// Code generated by Wire. DO NOT EDIT.//go:generate go run github.com/google/wire/cmd/wire
//go:build !wireinject
// +build !wireinjectpackage srvimport (v1_2 "mxshop/app/goods/srv/internal/controller/v1""mxshop/app/goods/srv/internal/data/v1/data_search/v1/es""mxshop/app/goods/srv/internal/data/v1/db""mxshop/app/goods/srv/internal/service/v1""mxshop/app/pkg/options""mxshop/gmicro/app""mxshop/pkg/log"
)// Injectors from wire.go:func initApp(logOptions *log.Options, serverOptions *options.ServerOptions, registryOptions *options.RegistryOptions, telemetryOptions *options.TelemetryOptions, mySQLOptions *options.MySQLOptions, esOptions *options.EsOptions) (*app.App, error) {registrar := NewRegistrar(registryOptions)dataFactory, err := db.GetDBFactoryOr(mySQLOptions)if err != nil {return nil, err}searchFactory, err := es.GetSearchFactoryOr(esOptions)if err != nil {return nil, err}serviceFactory := v1.NewGoodsServiceWire(dataFactory, searchFactory)goodsServer := v1_2.NewGoodsServerWire(serviceFactory)server, err := NewGoodsRPCServerWire(telemetryOptions, serverOptions, goodsServer)if err != nil {return nil, err}appApp, err := NewGoodsAppWire(logOptions, registrar, serverOptions, server)if err != nil {return nil, err}return appApp, nil
}