Golang gRPC 使用

一、概念

1、gRPC默認使用protocol buffers，這是google開源的一套成熟的結構數據序列化機制（當然也可以使用其他數據格式如JSON），可以用proto files創建gRPC服務，用protocol buffers消息類型來定義方法參數和返回類型。

二、安裝

1、yum install autoconf automake libtool  （centos 系統）

2、protocal buffer安裝

從 https://github.com/google/protobuf/releases下載安裝包，解壓，然后操作以下命令：

./autogen.sh
./configure
make
make install

最后設置環境變量即可：export LD_LIBRARY_PATH=/usr/local/lib

3、安裝 golang protobuf

go get -u github.com/golang/protobuf/proto // golang protobuf 庫
go get -u github.com/golang/protobuf/protoc-gen-go //protoc --go_out 工具

4、安裝 gRPC-go

go get google.golang.org/grpc

無法下載的話去 https://github.com/grpc/grpc-go 下載

三、使用

1、編寫 proto 文件，helloworld.proto

syntax = "proto3";

option objc_class_prefix = "HLW";

package helloworld;

// The greeting service definition.
service Greeter {
  // Sends a greeting
  rpc SayHello (HelloRequest) returns (HelloReply) {}
}

// The request message containing the user's name.
message HelloRequest {
  string name = 1;
}

// The response message containing the greetings
message HelloReply {
  string message = 1;
}

• syntax="proto3":指定protobuf的版本
• package helloworld:聲明一個報名，一般與文件目錄名相同
• import "xxx/xx.proto":導入其他的包，這樣你就可以使用其他的包的數據結構
• required、optional、repeated:表示該字段是否必須填充；required表示必須指定且只能指定一個；當optional表示可選，可指定也可不指定，但不可超過一個不指定值的時候會采用空值，如string類型的字段會用字符串表示；repeated表示可以重復，類似與編程語言中的list
• message Author：在一個message體內定義一個message結構體
• enum：是枚舉類型結構體
• 數字：字段的標識符，不可重復
• 數據類型： int32、int64、uint32、uint64、sint32、sint64、double、float、 string、bool、bytes、enum、message等等

2、使用protoc命令生成相關文件：

protoc --go_out=plugins=grpc:. helloworld.proto
ls
helloworld.pb.go    helloworld.proto

這里用了plugins選項，提供對grpc的支持，否則不會生成Service的接口，方便編寫服務器和客戶端程序

helloworld.pb.go 文件如下：

// Code generated by protoc-gen-go. DO NOT EDIT.
// source: helloworld.proto

package helloworld

import (
    context "context"
    fmt "fmt"
    proto "github.com/golang/protobuf/proto"
    grpc "google.golang.org/grpc"
    math "math"
)

// Reference imports to suppress errors if they are not otherwise used.
var _ = proto.Marshal
var _ = fmt.Errorf
var _ = math.Inf

// This is a compile-time assertion to ensure that this generated file
// is compatible with the proto package it is being compiled against.
// A compilation error at this line likely means your copy of the
// proto package needs to be updated.
const _ = proto.ProtoPackageIsVersion3 // please upgrade the proto package

// The request message containing the user's name.
type HelloRequest struct {
    Name                 string   `protobuf:"bytes,1,opt,name=name,proto3" json:"name,omitempty"`
    XXX_NoUnkeyedLiteral struct{} `json:"-"`
    XXX_unrecognized     []byte   `json:"-"`
    XXX_sizecache        int32    `json:"-"`
}

func (m *HelloRequest) Reset()         { *m = HelloRequest{} }
func (m *HelloRequest) String() string { return proto.CompactTextString(m) }
func (*HelloRequest) ProtoMessage()    {}
func (*HelloRequest) Descriptor() ([]byte, []int) {
    return fileDescriptor_17b8c58d586b62f2, []int{0}
}

func (m *HelloRequest) XXX_Unmarshal(b []byte) error {
    return xxx_messageInfo_HelloRequest.Unmarshal(m, b)
}
func (m *HelloRequest) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
    return xxx_messageInfo_HelloRequest.Marshal(b, m, deterministic)
}
func (m *HelloRequest) XXX_Merge(src proto.Message) {
    xxx_messageInfo_HelloRequest.Merge(m, src)
}
func (m *HelloRequest) XXX_Size() int {
    return xxx_messageInfo_HelloRequest.Size(m)
}
func (m *HelloRequest) XXX_DiscardUnknown() {
    xxx_messageInfo_HelloRequest.DiscardUnknown(m)
}

var xxx_messageInfo_HelloRequest proto.InternalMessageInfo

func (m *HelloRequest) GetName() string {
    if m != nil {
        return m.Name
    }
    return ""
}

// The response message containing the greetings
type HelloReply struct {
    Message              string   `protobuf:"bytes,1,opt,name=message,proto3" json:"message,omitempty"`
    XXX_NoUnkeyedLiteral struct{} `json:"-"`
    XXX_unrecognized     []byte   `json:"-"`
    XXX_sizecache        int32    `json:"-"`
}

func (m *HelloReply) Reset()         { *m = HelloReply{} }
func (m *HelloReply) String() string { return proto.CompactTextString(m) }
func (*HelloReply) ProtoMessage()    {}
func (*HelloReply) Descriptor() ([]byte, []int) {
    return fileDescriptor_17b8c58d586b62f2, []int{1}
}

func (m *HelloReply) XXX_Unmarshal(b []byte) error {
    return xxx_messageInfo_HelloReply.Unmarshal(m, b)
}
func (m *HelloReply) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
    return xxx_messageInfo_HelloReply.Marshal(b, m, deterministic)
}
func (m *HelloReply) XXX_Merge(src proto.Message) {
    xxx_messageInfo_HelloReply.Merge(m, src)
}
func (m *HelloReply) XXX_Size() int {
    return xxx_messageInfo_HelloReply.Size(m)
}
func (m *HelloReply) XXX_DiscardUnknown() {
    xxx_messageInfo_HelloReply.DiscardUnknown(m)
}

var xxx_messageInfo_HelloReply proto.InternalMessageInfo

func (m *HelloReply) GetMessage() string {
    if m != nil {
        return m.Message
    }
    return ""
}

func init() {
    proto.RegisterType((*HelloRequest)(nil), "helloworld.HelloRequest")
    proto.RegisterType((*HelloReply)(nil), "helloworld.HelloReply")
}

func init() { proto.RegisterFile("helloworld.proto", fileDescriptor_17b8c58d586b62f2) }

var fileDescriptor_17b8c58d586b62f2 = []byte{
    // 149 bytes of a gzipped FileDescriptorProto
    0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0xe2, 0x12, 0xc8, 0x48, 0xcd, 0xc9,
    0xc9, 0x2f, 0xcf, 0x2f, 0xca, 0x49, 0xd1, 0x2b, 0x28, 0xca, 0x2f, 0xc9, 0x17, 0xe2, 0x42, 0x88,
    0x28, 0x29, 0x71, 0xf1, 0x78, 0x80, 0x78, 0x41, 0xa9, 0x85, 0xa5, 0xa9, 0xc5, 0x25, 0x42, 0x42,
    0x5c, 0x2c, 0x79, 0x89, 0xb9, 0xa9, 0x12, 0x8c, 0x0a, 0x8c, 0x1a, 0x9c, 0x41, 0x60, 0xb6, 0x92,
    0x1a, 0x17, 0x17, 0x54, 0x4d, 0x41, 0x4e, 0xa5, 0x90, 0x04, 0x17, 0x7b, 0x6e, 0x6a, 0x71, 0x71,
    0x62, 0x3a, 0x4c, 0x11, 0x8c, 0x6b, 0xe4, 0xc9, 0xc5, 0xee, 0x5e, 0x94, 0x9a, 0x5a, 0x92, 0x5a,
    0x24, 0x64, 0xc7, 0xc5, 0x11, 0x9c, 0x58, 0x09, 0xd6, 0x25, 0x24, 0xa1, 0x87, 0xe4, 0x02, 0x64,
    0xcb, 0xa4, 0xc4, 0xb0, 0xc8, 0x14, 0xe4, 0x54, 0x2a, 0x31, 0x38, 0xb1, 0x2d, 0x62, 0x62, 0xf6,
    0xf0, 0x09, 0x4f, 0x62, 0x03, 0xbb, 0xd8, 0x18, 0x10, 0x00, 0x00, 0xff, 0xff, 0xbe, 0xde, 0x1d,
    0x2e, 0xc5, 0x00, 0x00, 0x00,
}

// Reference imports to suppress errors if they are not otherwise used.
var _ context.Context
var _ grpc.ClientConn

// This is a compile-time assertion to ensure that this generated file
// is compatible with the grpc package it is being compiled against.
const _ = grpc.SupportPackageIsVersion4

// GreeterClient is the client API for Greeter service.
//
// For semantics around ctx use and closing/ending streaming RPCs, please refer to https://godoc.org/google.golang.org/grpc#ClientConn.NewStream.
type GreeterClient interface {
    // Sends a greeting
    SayHello(ctx context.Context, in *HelloRequest, opts ...grpc.CallOption) (*HelloReply, error)
}

type greeterClient struct {
    cc *grpc.ClientConn
}

func NewGreeterClient(cc *grpc.ClientConn) GreeterClient {
    return &greeterClient{cc}
}

func (c *greeterClient) SayHello(ctx context.Context, in *HelloRequest, opts ...grpc.CallOption) (*HelloReply, error) {
    out := new(HelloReply)
    err := c.cc.Invoke(ctx, "/helloworld.Greeter/SayHello", in, out, opts...)
    if err != nil {
        return nil, err
    }
    return out, nil
}

// GreeterServer is the server API for Greeter service.
type GreeterServer interface {
    // Sends a greeting
    SayHello(context.Context, *HelloRequest) (*HelloReply, error)
}

func RegisterGreeterServer(s *grpc.Server, srv GreeterServer) {
    s.RegisterService(&_Greeter_serviceDesc, srv)
}

func _Greeter_SayHello_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
    in := new(HelloRequest)
    if err := dec(in); err != nil {
        return nil, err
    }
    if interceptor == nil {
        return srv.(GreeterServer).SayHello(ctx, in)
    }
    info := &grpc.UnaryServerInfo{
        Server:     srv,
        FullMethod: "/helloworld.Greeter/SayHello",
    }
    handler := func(ctx context.Context, req interface{}) (interface{}, error) {
        return srv.(GreeterServer).SayHello(ctx, req.(*HelloRequest))
    }
    return interceptor(ctx, in, info, handler)
}

var _Greeter_serviceDesc = grpc.ServiceDesc{
    ServiceName: "helloworld.Greeter",
    HandlerType: (*GreeterServer)(nil),
    Methods: []grpc.MethodDesc{
        {
            MethodName: "SayHello",
            Handler:    _Greeter_SayHello_Handler,
        },
    },
    Streams:  []grpc.StreamDesc{},
    Metadata: "helloworld.proto",
}

3、服務器程序

package main

import (
    "log"
    "net"

    pb "test_grpc/helloworld"
    "google.golang.org/grpc"
    "golang.org/x/net/context"
)

const (
    PORT = ":50001"
)

type server struct {}

func (s *server) SayHello(ctx context.Context, in *pb.HelloRequest) (*pb.HelloReply, error) {
    log.Println("request: ", in.Name)
    return &pb.HelloReply{Message: "Hello " + in.Name}, nil
}

func main() {
    lis, err := net.Listen("tcp", PORT)

    if err != nil {
        log.Fatalf("failed to listen: %v", err)
    }

    s := grpc.NewServer()
    pb.RegisterGreeterServer(s, &server{})
    log.Println("rpc服務已經開啟")
    s.Serve(lis)
}

4、客戶端程序

package main

import (
    "log"
    "os"

    pb "test_grpc/helloworld"
    "golang.org/x/net/context"
    "google.golang.org/grpc"
)

const (
    address = "localhost:50001"
)

func main() {
    conn, err := grpc.Dial(address, grpc.WithInsecure())

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

    defer conn.Close()

    c := pb.NewGreeterClient(conn)

    name := "lin"
    if len(os.Args) > 1 {
        name = os.Args[1]
    }

    r, err := c.SayHello(context.Background(), &pb.HelloRequest{Name: name})

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

    log.Println(r.Message)
}