grpc - 使用 golang 带你从头撸一套 RPC 服务(一)

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gRPC 是一个高性能、开源和通用的 RPC 框架,面向移动和 HTTP/2 设计,带来诸如双向流、流控、头部压缩、单 TCP 连接上的多复用请求等特。这些特性使得其在移动设备上表现更好,更省电和节省空间占用。

安装 protobuf

grpc使用protobuf作为IDL(interface descriton language),且要求protobuf 3.0以上,这里我们直接选用当前最新版本 3.8,git下载地址

选择操作系统对应的版本下载,这里我们直接使用已经编译好的protoc可执行文件(或者下载安装包编译安装)。

wget https://github.com/protocolbuffers/protobuf/releases/download/v3.8.0-rc1/protoc-3.8.0-rc-1-linux-x86_64.zip
tar -zxvf protoc-3.8.0-rc-1-linux-x86_64.zip
mv protoc-3.8.0-rc-1-linux-x86_64 /usr/local/protoc
ln -s /usr/local/protoc/bin/protoc /usr/local/bin/protoc
#查看 protoc
protoc --version

安装 protoc-gen-go

protoc-gen-goGo Grpcprotoc编译插件,protobuf内置了许多高级语言的编译器,但没有Go的。

# 运行 protoc -h 命令可以发现内置的只支持以下语言
protoc -h
...
--cpp_out=OUT_DIR           Generate C++ header and source.
--csharp_out=OUT_DIR        Generate C# source file.
--java_out=OUT_DIR          Generate Java source file.
--js_out=OUT_DIR            Generate JavaScript source.
--objc_out=OUT_DIR          Generate Objective C header and source.
--php_out=OUT_DIR           Generate PHP source file.
--python_out=OUT_DIR        Generate Python source file.
--ruby_out=OUT_DIR          Generate Ruby source file.
...

所以我们使用protoc编译生成Go版的grpc时,需要先安装此插件。

go get -u github.com/golang/protobuf/{protoc-gen-go}

安装 grpc-go

grpc-go包含了Gogrpc库。

go get google.golang.org/grpc 可能会被墙掉了,使用如下方式手动安装。

git clone https://github.com/grpc/grpc-go.git $GOPATH/src/google.golang.org/grpc
git clone https://github.com/golang/net.git $GOPATH/src/golang.org/x/net
git clone https://github.com/golang/text.git $GOPATH/src/golang.org/x/text
git clone https://github.com/google/go-genproto.git $GOPATH/src/google.golang.org/genproto

cd $GOPATH/src/
go install google.golang.org/grpc

Grpc的四种模式

grpc借口的类型分为一下四种: A为接受参数,B为返回参数

  1. rpc GetFeature(Point) returns (Feature) {} 普通调用:A-B
  2. rpc ListFeatures(Rectangle) returns (stream Feature) {} 单向流:A - B(流)
  3. rpc RecordRoute(stream Point) returns (RouteSummary) {} 单向流:A(流) - B
  4. rpc RouteChat(stream RouteNote) returns (stream RouteNote) {} 双向流:A(流) - B(流)

我们只演示最基础的普通调用,开始撸。

Go实例

下面我们将创建一个提供CURD操作的User服务。

#创建一个 grpc 服务库
mkdir $GOPATH/src/grpc/user -p && cd $GOPATH/src/grpc

定义服务接口

使用proto3 IDL编写如下的用户服务。
vi user.proto

syntax = "proto3";
 
// user 包
package user;

// User 服务及服务接口的定义
service User {
    rpc UserIndex(UserIndexRequest) returns (UserIndexResponse) {}
    rpc UserView(UserViewRequest) returns (UserViewResponse) {}
    rpc UserPost(UserPostRequest) returns (UserPostResponse) {}
    rpc UserDelete(UserDeleteRequest) returns (UserDeleteResponse) {}
}

// 用户实体模型
message UserEntity {
    string name = 1;
    int32 age = 2;
}

// User 服务的各个接口的请求/响应结构
message UserIndexRequest {
    int32 page = 1;
    int32 page_size = 2;
}

message UserIndexResponse {
    int32 err = 1;
    string msg = 2;
    // 返回一个 UserEntity 对象的列表数据
    repeated UserEntity data = 3;
}

message UserViewRequest {
    int32 uid = 1;
}

message UserViewResponse {
    int32 err = 1;
    string msg = 2;
    // 返回一个 UserEntity 对象
    UserEntity data = 3;
}

message UserPostRequest {
    string name = 1;
    string password = 2;
    int32 age = 3;
}

message UserPostResponse {
    int32 err = 1;
    string msg = 2;
}

message UserDeleteRequest {
    int32 uid = 1;
}

message UserDeleteResponse {
    int32 err = 1;
    string msg = 2;
}

生成接口库

# 将 User 服务的所属包 user package 存放在 $GOPATH/src/grpc/user 下
protoc -I. --go_out=plugins=grpc:./user user.proto

编写服务端

vi server.go

package main

import (
    "context"
    "log"
    "net"

    "google.golang.org/grpc"
    "google.golang.org/grpc/reflection"

    user "grpc/user"
)

const (
    port = ":50051"
)

type UserService struct {
    // 实现 User 服务的业务对象
}

// UserService 实现了 User 服务接口中声明的所有方法
func (userService *UserService) UserIndex(ctx context.Context, in *user.UserIndexRequest) (*user.UserIndexResponse, error) {
    log.Printf("receive user index request: page %d page_size %d", in.Page, in.PageSize)

    return &user.UserIndexResponse{
        Err: 0,
        Msg: "success",
        Data: []*user.UserEntity{
            {Name: "big_cat", Age: 28},
            {Name: "sqrt_cat", Age: 29},
        },
    }, nil
}

func (userService *UserService) UserView(ctx context.Context, in *user.UserViewRequest) (*user.UserViewResponse, error) {
    log.Printf("receive user view request: uid %d", in.Uid)

    return &user.UserViewResponse{
        Err:  0,
        Msg:  "success",
        Data: &user.UserEntity{Name: "james", Age: 28},
    }, nil
}

func (userService *UserService) UserPost(ctx context.Context, in *user.UserPostRequest) (*user.UserPostResponse, error) {
    log.Printf("receive user post request: name %s password %s age %d", in.Name, in.Password, in.Age)

    return &user.UserPostResponse{
        Err: 0,
        Msg: "success",
    }, nil
}

func (userService *UserService) UserDelete(ctx context.Context, in *user.UserDeleteRequest) (*user.UserDeleteResponse, error) {
    log.Printf("receive user delete request: uid %d", in.Uid)

    return &user.UserDeleteResponse{
        Err: 0,
        Msg: "success",
    }, nil
}

func main() {
    lis, err := net.Listen("tcp", port)
    if err != nil {
        log.Fatalf("failed to listen: %v", err)
    }

    // 创建 RPC 服务容器
    grpcServer := grpc.NewServer()

    // 为 User 服务注册业务实现 将 User 服务绑定到 RPC 服务容器上
    user.RegisterUserServer(grpcServer, &UserService{})
    // 注册反射服务 这个服务是CLI使用的 跟服务本身没有关系

    reflection.Register(grpcServer)

    if err := grpcServer.Serve(lis); err != nil {
        log.Fatalf("failed to serve: %v", err)
    }
}

编写客户端

vi client.go

package main

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

    "google.golang.org/grpc"

    user "grpc/user"
)

const (
    address = "localhost:50051"
)

func main() {
    //建立链接
    conn, err := grpc.Dial(address, grpc.WithInsecure())

    if err != nil {
        log.Fatalf("did not connect: %v", err)
    }

    defer conn.Close()

    userClient := user.NewUserClient(conn)

    // 设定请求超时时间 3s
    ctx, cancel := context.WithTimeout(context.Background(), time.Second*3)
    defer cancel()

    // UserIndex 请求
    userIndexReponse, err := userClient.UserIndex(ctx, &user.UserIndexRequest{Page: 1, PageSize: 12})
    if err != nil {
        log.Printf("user index could not greet: %v", err)
    }

    if 0 == userIndexReponse.Err {
        log.Printf("user index success: %s", userIndexReponse.Msg)
        // 包含 UserEntity 的数组列表
        userEntityList := userIndexReponse.Data
        for _, row := range userEntityList {
            fmt.Println(row.Name, row.Age)
        }
    } else {
        log.Printf("user index error: %d", userIndexReponse.Err)
    }

    // UserView 请求
    userViewResponse, err := userClient.UserView(ctx, &user.UserViewRequest{Uid: 1})
    if err != nil {
        log.Printf("user view could not greet: %v", err)
    }

    if 0 == userViewResponse.Err {
        log.Printf("user view success: %s", userViewResponse.Msg)
        userEntity := userViewResponse.Data
        fmt.Println(userEntity.Name, userEntity.Age)
    } else {
        log.Printf("user view error: %d", userViewResponse.Err)
    }

    // UserPost 请求
    userPostReponse, err := userClient.UserPost(ctx, &user.UserPostRequest{Name: "big_cat", Password: "123456", Age: 29})
    if err != nil {
        log.Printf("user post could not greet: %v", err)
    }

    if 0 == userPostReponse.Err {
        log.Printf("user post success: %s", userPostReponse.Msg)
    } else {
        log.Printf("user post error: %d", userPostReponse.Err)
    }

    // UserDelete 请求
    userDeleteReponse, err := userClient.UserDelete(ctx, &user.UserDeleteRequest{Uid: 1})
    if err != nil {
        log.Printf("user delete could not greet: %v", err)
    }

    if 0 == userDeleteReponse.Err {
        log.Printf("user delete success: %s", userDeleteReponse.Msg)
    } else {
        log.Printf("user delete error: %d", userDeleteReponse.Err)
    }
}

启动服务/请求服务

go run server.go
# 新建一个窗口
go run client.go

运行结果

#server
[root@localhost rpc]# go run server.go
2019/05/16 00:28:01 receive user index request: page 1 page_size 12
2019/05/16 00:28:01 receive user view request: uid 1
2019/05/16 00:28:01 receive user post request: name big_cat password 123456 age 29
2019/05/16 00:28:01 receive user delete request: uid 1

#client
[root@localhost rpc]# go run client.go 
2019/05/16 00:28:01 user index success: success
big_cat 28
sqrt_cat 29
2019/05/16 00:28:01 user view success: success
james 28
2019/05/16 00:28:01 user post success: success
2019/05/16 00:28:01 user delete success: success

grpc面向服务接口编程大致就是这样啦,你可以更好的组织业务库,我这里全放在package main里了,后面的工作就是把数据库拉进来了。

第二篇我们将以PHP作为客户端请求Go服务端

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