Go实战--golang中使用gRPC和Protobuf实现高性能api(golang/protobuf、google.golang.org/grpc)

生命不止，继续 go go go !!!

号外号外，插播一条广告，通过博客的uv可以看到周五，程序员是不怎么干活的：

本篇博客，使用gRPC和Protobuf，实现所谓的高性能api。

protobuf

golang中的protobuf大家应该不会很陌生，之前也有博客介绍过：
Go实战–go中使用google/protobuf(The way to go)

Protocol Buffers (a.k.a., protobuf) are Google’s language-neutral, platform-neutral, extensible mechanism for serializing structured data. You can find protobuf’s documentation on the Google Developers site.

获取：

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

Protobuf语法
下面简要介绍Protobuf语法：
参考：https://segmentfault.com/a/1190000007917576
官方：
https://developers.google.com/protocol-buffers/
https://developers.google.com/protocol-buffers/docs/gotutorial

Message定义
一个message类型定义描述了一个请求或相应的消息格式，可以包含多种类型字段。例如定义一个搜索请求的消息格式，每个请求包含查询字符串、页码、每页数目。

syntax = "proto3";
package tutorial;

首行声明使用的protobuf版本为proto3

message Person {
  string name = 1;
  int32 id = 2;  // Unique ID number for this person.
  string email = 3;

  enum PhoneType {
    MOBILE = 0;
    HOME = 1;
    WORK = 2;
  }

  message PhoneNumber {
    string number = 1;
    PhoneType type = 2;
  }

  repeated PhoneNumber phones = 4;
}

// Our address book file is just one of these.
message AddressBook {
  repeated Person people = 1;
}

生成

protoc -I=$SRC_DIR --go_out=$DST_DIR $SRC_DIR/addressbook.proto

写消息

book := &pb.AddressBook{}
// ...

// Write the new address book back to disk.
out, err := proto.Marshal(book)
if err != nil {
        log.Fatalln("Failed to encode address book:", err)
}
if err := ioutil.WriteFile(fname, out, 0644); err != nil {
        log.Fatalln("Failed to write address book:", err)
}

读消息

// Read the existing address book.
in, err := ioutil.ReadFile(fname)
if err != nil {
        log.Fatalln("Error reading file:", err)
}
book := &pb.AddressBook{}
if err := proto.Unmarshal(in, book); err != nil {
        log.Fatalln("Failed to parse address book:", err)
}

grpc

golang中的rpc大家也不会陌生，之前也有介绍过奥：
Go实战–go中使用rpc(The way to go)

什么是rpc
RPC是Remote Procedure CallProtocol的缩写，即—远程过程调用协议。

RPC是一个计算机通信协议。该协议允许运行于一台计算机的程序调用另一台计算机的子程序，而程序员无需额外地为这个交互作用编程。如果涉及的软件采用面向对象编程，那么远程过程调用亦可称作远程调用或远程方法调用，信息数据。通过它可以使函数调用模式网络化。在OSI网络通信模型中，RPC跨越了传输层和应用层。RPC使得开发包括网络分布式多程序在内的应用程序更加容易。

net/rpc
Go语言标准库能够自带一个rpc框架还是非常给力的，这可以很大程度的降低写后端网络通信服务的门槛，特别是在大规模的分布式系统中，rpc基本是跨机器通信的标配。rpc能够最大程度屏蔽网络细节，让开发者专注在服务功能的开发上面

什么是grpc
gRPC 是一个高性能、开源、通用的RPC框架，由Google推出，基于HTTP/2协议标准设计开发，默认采用Protocol Buffers数据序列化协议，支持多种开发语言。gRPC提供了一种简单的方法来精确的定义服务，并且为客户端和服务端自动生成可靠的功能库。

在gRPC客户端可以直接调用不同服务器上的远程程序，使用姿势看起来就像调用本地程序一样，很容易去构建分布式应用和服务。和很多RPC系统一样，服务端负责实现定义好的接口并处理客户端的请求，客户端根据接口描述直接调用需要的服务。客户端和服务端可以分别使用gRPC支持的不同语言实现。

grpc-go
github地址：
https://github.com/grpc/grpc-go

Star: 4402

文档地址：
https://godoc.org/google.golang.org/grpc

获取：
go get -u google.golang.org/grpc

应用

文件结构

proto文件
customer.proto

syntax = "proto3";
package customer;


// The Customer service definition.
service Customer {   
  // Get all Customers with filter - A server-to-client streaming RPC.
  rpc GetCustomers(CustomerFilter) returns (stream CustomerRequest) {}
  // Create a new Customer - A simple RPC 
  rpc CreateCustomer (CustomerRequest) returns (CustomerResponse) {}
}

// Request message for creating a new customer
message CustomerRequest {
  int32 id = 1;  // Unique ID number for a Customer.
  string name = 2;
  string email = 3;
  string phone= 4;

  message Address {
    string street = 1;
    string city = 2;
    string state = 3;
    string zip = 4;
    bool isShippingAddress = 5; 
  }

  repeated Address addresses = 5;
}

message CustomerResponse {
  int32 id = 1;
  bool success = 2;
}
message CustomerFilter {    
  string keyword = 1;
}

生成customer.pb.go

protoc --go_out=plugins=grpc:. customer.proto

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

/*
Package customer is a generated protocol buffer package.

It is generated from these files:
    customer.proto

It has these top-level messages:
    CustomerRequest
    CustomerResponse
    CustomerFilter
*/
package customer

import proto "github.com/golang/protobuf/proto"
import fmt "fmt"
import math "math"

import (
    context "golang.org/x/net/context"
    grpc "google.golang.org/grpc"
)

// 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.ProtoPackageIsVersion2 // please upgrade the proto package

// Request message for creating a new customer
type CustomerRequest struct {
    Id        int32                      `protobuf:"varint,1,opt,name=id" json:"id,omitempty"`
    Name      string                     `protobuf:"bytes,2,opt,name=name" json:"name,omitempty"`
    Email     string                     `protobuf:"bytes,3,opt,name=email" json:"email,omitempty"`
    Phone     string                     `protobuf:"bytes,4,opt,name=phone" json:"phone,omitempty"`
    Addresses []*CustomerRequest_Address `protobuf:"bytes,5,rep,name=addresses" json:"addresses,omitempty"`
}

func (m *CustomerRequest) Reset()                    { *m = CustomerRequest{} }
func (m *CustomerRequest) String() string            { return proto.CompactTextString(m) }
func (*CustomerRequest) ProtoMessage()               {}
func (*CustomerRequest) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{0} }

func (m *CustomerRequest) GetId() int32 {
    if m != nil {
        return m.Id
    }
    return 0
}

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

func (m *CustomerRequest) GetEmail() string {
    if m != nil {
        return m.Email
    }
    return ""
}

func (m *CustomerRequest) GetPhone() string {
    if m != nil {
        return m.Phone
    }
    return ""
}

func (m *CustomerRequest) GetAddresses() []*CustomerRequest_Address {
    if m != nil {
        return m.Addresses
    }
    return nil
}

type CustomerRequest_Address struct {
    Street            string `protobuf:"bytes,1,opt,name=street" json:"street,omitempty"`
    City              string `protobuf:"bytes,2,opt,name=city" json:"city,omitempty"`
    State             string `protobuf:"bytes,3,opt,name=state" json:"state,omitempty"`
    Zip               string `protobuf:"bytes,4,opt,name=zip" json:"zip,omitempty"`
    IsShippingAddress bool   `protobuf:"varint,5,opt,name=isShippingAddress" json:"isShippingAddress,omitempty"`
}

func (m *CustomerRequest_Address) Reset()                    { *m = CustomerRequest_Address{} }
func (m *CustomerRequest_Address) String() string            { return proto.CompactTextString(m) }
func (*CustomerRequest_Address) ProtoMessage()               {}
func (*CustomerRequest_Address) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{0, 0} }

func (m *CustomerRequest_Address) GetStreet() string {
    if m != nil {
        return m.Street
    }
    return ""
}

func (m *CustomerRequest_Address) GetCity() string {
    if m != nil {
        return m.City
    }
    return ""
}

func (m *CustomerRequest_Address) GetState() string {
    if m != nil {
        return m.State
    }
    return ""
}

func (m *CustomerRequest_Address) GetZip() string {
    if m != nil {
        return m.Zip
    }
    return ""
}

func (m *CustomerRequest_Address) GetIsShippingAddress() bool {
    if m != nil {
        return m.IsShippingAddress
    }
    return false
}

type CustomerResponse struct {
    Id      int32 `protobuf:"varint,1,opt,name=id" json:"id,omitempty"`
    Success bool  `protobuf:"varint,2,opt,name=success" json:"success,omitempty"`
}

func (m *CustomerResponse) Reset()                    { *m = CustomerResponse{} }
func (m *CustomerResponse) String() string            { return proto.CompactTextString(m) }
func (*CustomerResponse) ProtoMessage()               {}
func (*CustomerResponse) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{1} }

func (m *CustomerResponse) GetId() int32 {
    if m != nil {
        return m.Id
    }
    return 0
}

func (m *CustomerResponse) GetSuccess() bool {
    if m != nil {
        return m.Success
    }
    return false
}

type CustomerFilter struct {
    Keyword string `protobuf:"bytes,1,opt,name=keyword" json:"keyword,omitempty"`
}

func (m *CustomerFilter) Reset()                    { *m = CustomerFilter{} }
func (m *CustomerFilter) String() string            { return proto.CompactTextString(m) }
func (*CustomerFilter) ProtoMessage()               {}
func (*CustomerFilter) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{2} }

func (m *CustomerFilter) GetKeyword() string {
    if m != nil {
        return m.Keyword
    }
    return ""
}

func init() {
    proto.RegisterType((*CustomerRequest)(nil), "customer.CustomerRequest")
    proto.RegisterType((*CustomerRequest_Address)(nil), "customer.CustomerRequest.Address")
    proto.RegisterType((*CustomerResponse)(nil), "customer.CustomerResponse")
    proto.RegisterType((*CustomerFilter)(nil), "customer.CustomerFilter")
}

// 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

// Client API for Customer service

type CustomerClient interface {
    // Get all Customers with filter - A server-to-client streaming RPC.
    GetCustomers(ctx context.Context, in *CustomerFilter, opts ...grpc.CallOption) (Customer_GetCustomersClient, error)
    // Create a new Customer - A simple RPC
    CreateCustomer(ctx context.Context, in *CustomerRequest, opts ...grpc.CallOption) (*CustomerResponse, error)
}

type customerClient struct {
    cc *grpc.ClientConn
}

func NewCustomerClient(cc *grpc.ClientConn) CustomerClient {
    return &customerClient{cc}
}

func (c *customerClient) GetCustomers(ctx context.Context, in *CustomerFilter, opts ...grpc.CallOption) (Customer_GetCustomersClient, error) {
    stream, err := grpc.NewClientStream(ctx, &_Customer_serviceDesc.Streams[0], c.cc, "/customer.Customer/GetCustomers", opts...)
    if err != nil {
        return nil, err
    }
    x := &customerGetCustomersClient{stream}
    if err := x.ClientStream.SendMsg(in); err != nil {
        return nil, err
    }
    if err := x.ClientStream.CloseSend(); err != nil {
        return nil, err
    }
    return x, nil
}

type Customer_GetCustomersClient interface {
    Recv() (*CustomerRequest, error)
    grpc.ClientStream
}

type customerGetCustomersClient struct {
    grpc.ClientStream
}

func (x *customerGetCustomersClient) Recv() (*CustomerRequest, error) {
    m := new(CustomerRequest)
    if err := x.ClientStream.RecvMsg(m); err != nil {
        return nil, err
    }
    return m, nil
}

func (c *customerClient) CreateCustomer(ctx context.Context, in *CustomerRequest, opts ...grpc.CallOption) (*CustomerResponse, error) {
    out := new(CustomerResponse)
    err := grpc.Invoke(ctx, "/customer.Customer/CreateCustomer", in, out, c.cc, opts...)
    if err != nil {
        return nil, err
    }
    return out, nil
}

// Server API for Customer service

type CustomerServer interface {
    // Get all Customers with filter - A server-to-client streaming RPC.
    GetCustomers(*CustomerFilter, Customer_GetCustomersServer) error
    // Create a new Customer - A simple RPC
    CreateCustomer(context.Context, *CustomerRequest) (*CustomerResponse, error)
}

func RegisterCustomerServer(s *grpc.Server, srv CustomerServer) {
    s.RegisterService(&_Customer_serviceDesc, srv)
}

func _Customer_GetCustomers_Handler(srv interface{}, stream grpc.ServerStream) error {
    m := new(CustomerFilter)
    if err := stream.RecvMsg(m); err != nil {
        return err
    }
    return srv.(CustomerServer).GetCustomers(m, &customerGetCustomersServer{stream})
}

type Customer_GetCustomersServer interface {
    Send(*CustomerRequest) error
    grpc.ServerStream
}

type customerGetCustomersServer struct {
    grpc.ServerStream
}

func (x *customerGetCustomersServer) Send(m *CustomerRequest) error {
    return x.ServerStream.SendMsg(m)
}

func _Customer_CreateCustomer_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
    in := new(CustomerRequest)
    if err := dec(in); err != nil {
        return nil, err
    }
    if interceptor == nil {
        return srv.(CustomerServer).CreateCustomer(ctx, in)
    }
    info := &grpc.UnaryServerInfo{
        Server:     srv,
        FullMethod: "/customer.Customer/CreateCustomer",
    }
    handler := func(ctx context.Context, req interface{}) (interface{}, error) {
        return srv.(CustomerServer).CreateCustomer(ctx, req.(*CustomerRequest))
    }
    return interceptor(ctx, in, info, handler)
}

var _Customer_serviceDesc = grpc.ServiceDesc{
    ServiceName: "customer.Customer",
    HandlerType: (*CustomerServer)(nil),
    Methods: []grpc.MethodDesc{
        {
            MethodName: "CreateCustomer",
            Handler:    _Customer_CreateCustomer_Handler,
        },
    },
    Streams: []grpc.StreamDesc{
        {
            StreamName:    "GetCustomers",
            Handler:       _Customer_GetCustomers_Handler,
            ServerStreams: true,
        },
    },
    Metadata: "customer.proto",
}

func init() { proto.RegisterFile("customer.proto", fileDescriptor0) }

var fileDescriptor0 = []byte{
    // 326 bytes of a gzipped FileDescriptorProto
    0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0x74, 0x92, 0xef, 0x4a, 0xc3, 0x30,
    0x10, 0xc0, 0x97, 0x6e, 0xdd, 0x9f, 0x53, 0xea, 0x0c, 0x22, 0xb1, 0x9f, 0x6a, 0x3f, 0x15, 0x91,
    0x21, 0xf3, 0xab, 0x20, 0x32, 0x70, 0xf8, 0xb5, 0x3e, 0x41, 0x6d, 0x0f, 0x17, 0xdc, 0xda, 0x9a,
    0xcb, 0x90, 0xf9, 0x0a, 0xbe, 0x83, 0xcf, 0xe0, 0x23, 0x4a, 0xd2, 0x66, 0x03, 0xe7, 0xbe, 0xdd,
    0xef, 0x72, 0x77, 0xf9, 0xe5, 0x08, 0x04, 0xf9, 0x9a, 0x74, 0xb5, 0x42, 0x35, 0xa9, 0x55, 0xa5,
    0x2b, 0x3e, 0x74, 0x1c, 0xff, 0x78, 0x70, 0x32, 0x6b, 0x21, 0xc5, 0xf7, 0x35, 0x92, 0xe6, 0x01,
    0x78, 0xb2, 0x10, 0x2c, 0x62, 0x89, 0x9f, 0x7a, 0xb2, 0xe0, 0x1c, 0x7a, 0x65, 0xb6, 0x42, 0xe1,
    0x45, 0x2c, 0x19, 0xa5, 0x36, 0xe6, 0x67, 0xe0, 0xe3, 0x2a, 0x93, 0x4b, 0xd1, 0xb5, 0xc9, 0x06,
    0x4c, 0xb6, 0x5e, 0x54, 0x25, 0x8a, 0x5e, 0x93, 0xb5, 0xc0, 0xef, 0x61, 0x94, 0x15, 0x85, 0x42,
    0x22, 0x24, 0xe1, 0x47, 0xdd, 0xe4, 0x68, 0x7a, 0x39, 0xd9, 0x1a, 0xfd, 0xb9, 0x7d, 0xf2, 0xd0,
    0x94, 0xa6, 0xbb, 0x9e, 0xf0, 0x8b, 0xc1, 0xa0, 0x4d, 0xf3, 0x73, 0xe8, 0x93, 0x56, 0x88, 0xda,
    0x0a, 0x8e, 0xd2, 0x96, 0x8c, 0x64, 0x2e, 0xf5, 0xc6, 0x49, 0x9a, 0xd8, 0xe8, 0x90, 0xce, 0x34,
    0x3a, 0x49, 0x0b, 0x7c, 0x0c, 0xdd, 0x4f, 0x59, 0xb7, 0x8a, 0x26, 0xe4, 0xd7, 0x70, 0x2a, 0xe9,
    0x79, 0x21, 0xeb, 0x5a, 0x96, 0xaf, 0xed, 0x45, 0xc2, 0x8f, 0x58, 0x32, 0x4c, 0xf7, 0x0f, 0xe2,
    0x3b, 0x18, 0xef, 0x9c, 0xa9, 0xae, 0x4a, 0xc2, 0xbd, 0x95, 0x09, 0x18, 0xd0, 0x3a, 0xcf, 0xcd,
    0x1c, 0xcf, 0xce, 0x71, 0x18, 0x5f, 0x41, 0xe0, 0xba, 0x1f, 0xe5, 0x52, 0xa3, 0x32, 0xb5, 0x6f,
    0xb8, 0xf9, 0xa8, 0x54, 0xd1, 0x3e, 0xc9, 0xe1, 0xf4, 0x9b, 0xc1, 0xd0, 0x15, 0xf3, 0x39, 0x1c,
    0xcf, 0x51, 0x3b, 0x24, 0x2e, 0xf6, 0x57, 0xd8, 0x0c, 0x0c, 0x2f, 0x0e, 0x2e, 0x37, 0xee, 0xdc,
    0x30, 0xfe, 0x04, 0xc1, 0x4c, 0x61, 0xa6, 0x71, 0x3b, 0xfa, 0x70, 0x43, 0x18, 0xfe, 0x77, 0xd4,
    0x3c, 0x3a, 0xee, 0xbc, 0xf4, 0xed, 0x77, 0xba, 0xfd, 0x0d, 0x00, 0x00, 0xff, 0xff, 0xde, 0x91,
    0xd3, 0x62, 0x60, 0x02, 0x00, 0x00,
}

server/main.go

package main

import (
    "log"
    "net"
    "strings"

    "golang.org/x/net/context"
    "google.golang.org/grpc"

    pb "go_grpc_protobuf/customer"
)

const (
    port = ":50051"
)

// server is used to implement customer.CustomerServer.
type server struct {
    savedCustomers []*pb.CustomerRequest
}

// CreateCustomer creates a new Customer
func (s *server) CreateCustomer(ctx context.Context, in *pb.CustomerRequest) (*pb.CustomerResponse, error) {
    s.savedCustomers = append(s.savedCustomers, in)
    return &pb.CustomerResponse{Id: in.Id, Success: true}, nil
}

// GetCustomers returns all customers by given filter
func (s *server) GetCustomers(filter *pb.CustomerFilter, stream pb.Customer_GetCustomersServer) error {
    for _, customer := range s.savedCustomers {
        if filter.Keyword != "" {
            if !strings.Contains(customer.Name, filter.Keyword) {
                continue
            }
        }
        if err := stream.Send(customer); err != nil {
            return err
        }
    }
    return nil
}

func main() {
    lis, err := net.Listen("tcp", port)
    if err != nil {
        log.Fatalf("failed to listen: %v", err)
    }
    // Creates a new gRPC server
    s := grpc.NewServer()
    pb.RegisterCustomerServer(s, &server{})
    s.Serve(lis)
}

client/main.go

package main

import (
    "io"
    "log"

    "golang.org/x/net/context"
    "google.golang.org/grpc"

    pb "go_grpc_protobuf/customer"
)

const (
    address = "localhost:50051"
)

// createCustomer calls the RPC method CreateCustomer of CustomerServer
func createCustomer(client pb.CustomerClient, customer *pb.CustomerRequest) {
    resp, err := client.CreateCustomer(context.Background(), customer)
    if err != nil {
        log.Fatalf("Could not create Customer: %v", err)
    }
    if resp.Success {
        log.Printf("A new Customer has been added with id: %d", resp.Id)
    }
}

// getCustomers calls the RPC method GetCustomers of CustomerServer
func getCustomers(client pb.CustomerClient, filter *pb.CustomerFilter) {
    // calling the streaming API
    stream, err := client.GetCustomers(context.Background(), filter)
    if err != nil {
        log.Fatalf("Error on get customers: %v", err)
    }
    for {
        customer, err := stream.Recv()
        if err == io.EOF {
            break
        }
        if err != nil {
            log.Fatalf("%v.GetCustomers(_) = _, %v", client, err)
        }
        log.Printf("Customer: %v", customer)
    }
}
func main() {
    // Set up a connection to the gRPC server.
    conn, err := grpc.Dial(address, grpc.WithInsecure())
    if err != nil {
        log.Fatalf("did not connect: %v", err)
    }
    defer conn.Close()
    // Creates a new CustomerClient
    client := pb.NewCustomerClient(conn)

    customer := &pb.CustomerRequest{
        Id:    101,
        Name:  "Shiju Varghese",
        Email: "shiju@xyz.com",
        Phone: "732-757-2923",
        Addresses: []*pb.CustomerRequest_Address{
            &pb.CustomerRequest_Address{
                Street:            "1 Mission Street",
                City:              "San Francisco",
                State:             "CA",
                Zip:               "94105",
                IsShippingAddress: false,
            },
            &pb.CustomerRequest_Address{
                Street:            "Greenfield",
                City:              "Kochi",
                State:             "KL",
                Zip:               "68356",
                IsShippingAddress: true,
            },
        },
    }

    // Create a new customer
    createCustomer(client, customer)

    customer = &pb.CustomerRequest{
        Id:    102,
        Name:  "Irene Rose",
        Email: "irene@xyz.com",
        Phone: "732-757-2924",
        Addresses: []*pb.CustomerRequest_Address{
            &pb.CustomerRequest_Address{
                Street:            "1 Mission Street",
                City:              "San Francisco",
                State:             "CA",
                Zip:               "94105",
                IsShippingAddress: true,
            },
        },
    }

    // Create a new customer
    createCustomer(client, customer)
    // Filter with an empty Keyword
    filter := &pb.CustomerFilter{Keyword: ""}
    getCustomers(client, filter)
}

运行server，运行client，输出：

2017/12/07 11:55:59 A new Customer has been added with id: 101
2017/12/07 11:55:59 A new Customer has been added with id: 102
2017/12/07 11:55:59 Customer: id:101 name:"Shiju Varghese" email:"shiju@xyz.com" phone:"732-757-2923" addresses:<street:"1 Mission Street" city:"San Francisco" state:"CA" zip:"94105" > addresses:<street:"Greenfield" city:"Kochi" state:"KL" zip:"68356" isShippingAddress:true >
2017/12/07 11:55:59 Customer: id:102 name:"Irene Rose" email:"irene@xyz.com" phone:"732-757-2924" addresses:<street:"1 Mission Street" city:"San Francisco" state:"CA" zip:"94105" isShippingAddress:true >