ch4-04: 完善

ch4-rpc/ch4-04-grpc.md

@@ -1,5 +1,104 @@
 # 4.4. GRPC入门
 
+GRPC是Google公司基于Protobuf开发的跨语言的开源RPC框架。GRPC基于HTTP/2协议设计，可以基于一个HTTP/2链接提供多个服务，对于移动设备更加友好。本节将讲述GRPC的简单用法。
+
+## GRPC入门
+
+如果从Protobuf的角度看，GRPC只不过是针对service接口一个生成代码生成器。我们在本章的第二节中一节手工实现了一个简单的Protobuf代码生成器插件，只不过当时生成的代码是适配标准库的RPC框架的。
+
+创建hello.proto文件，定义HelloService接口：
+
+```proto
+syntax = "proto3";
+
+package main;
+
+message String {
+	string value = 1;
+}
+
+service HelloService {
+	rpc Hello (String) returns (String);
+}
+```
+
+使用protoc-gen-go内置的grpc插件生成GRPC代码：
+
+```
+$ protoc --go_out=plugins=grpc:. hello.proto
+```
+
+GRPC插件会为服务端和客户端生成不同的接口：
+
+```go
+type HelloServiceServer interface {
+	Hello(context.Context, *String) (*String, error)
+}
+
+type HelloServiceClient interface {
+	Hello(ctx context.Context, in *String, opts ...grpc.CallOption) (*String, error)
+}
+```
+
+GRPC通过context.Context参数，为每个方法调用提供了上下文支持。客户端在调用方法的时候，可以通过可选的grpc.CallOption类型的参数提供额外的上下文信息。
+
+基于服务端的HelloServiceServer接口可以重新实现HelloService服务：
+
+```go
+type HelloServiceImpl struct{}
+
+func (p *HelloServiceImpl) Hello(ctx context.Context, args *String) (*String, error) {
+	reply := &String{Value: "hello:" + args.GetValue()}
+	return reply, nil
+}
+```
+
+GRPC服务的启动流程和标准库的RPC服务启动流程类似：
+
+```go
+func main() {
+	grpcServer := grpc.NewServer()
+	RegisterHelloServiceServer(grpcServer, &HelloServiceImpl{})
+
+	lis, err := net.Listen("tcp", ":1234")
+	if err != nil {
+		log.Fatal(err)
+	}
+	grpcServer.Serve(lis)
+}
+```
+
+首先是通过`grpc.NewServer()`构造一个GRPC服务对象，然后通过GRPC插件生成的RegisterHelloServiceServer函数注册我们实现的HelloServiceImpl服务。然后通过`grpcServer.Serve(lis)`在一个监听端口上提供GRPC服务。
+
+然后就可以通过客户端链接GRPC服务了：
+
+```go
+func main() {
+	conn, err := grpc.Dial("localhost:1234", grpc.WithInsecure())
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer conn.Close()
+
+	client := NewHelloServiceClient(conn)
+	reply, err := client.Hello(context.Background(), &String{Value: "hello"})
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Println(reply.GetValue())
+}
+```
+
+其中grpc.Dial负责和GRPC服务建立链接，然后NewHelloServiceClient函数基于已经建立的链接构造HelloServiceClient对象。返回的client其实是一个HelloServiceClient接口对象，通过接口定义的方法就可以调用服务端对应的GRPC服务提供的方法。
+
+GRPC和标准库的RPC框架还有一个区别，GRPC生成的接口并不支持异步调用。
+
+## GRPC流
+
+TODO
+
+## 认证
+
 TODO
 
 <!--

examples/ch4-04-grpc/basic/client/Makefile

@@ -0,0 +1,2 @@
+default:
+	protoc --go_out=plugins=grpc:. hello.proto

examples/ch4-04-grpc/basic/client/hello.pb.go

@@ -0,0 +1,151 @@
+// Code generated by protoc-gen-go. DO NOT EDIT.
+// source: hello.proto
+
+package main
+
+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
+
+type String struct {
+	Value                string   `protobuf:"bytes,1,opt,name=value,proto3" json:"value,omitempty"`
+	XXX_NoUnkeyedLiteral struct{} `json:"-"`
+	XXX_unrecognized     []byte   `json:"-"`
+	XXX_sizecache        int32    `json:"-"`
+}
+
+func (m *String) Reset()         { *m = String{} }
+func (m *String) String() string { return proto.CompactTextString(m) }
+func (*String) ProtoMessage()    {}
+func (*String) Descriptor() ([]byte, []int) {
+	return fileDescriptor_hello_5dd9d59ecabc789f, []int{0}
+}
+func (m *String) XXX_Unmarshal(b []byte) error {
+	return xxx_messageInfo_String.Unmarshal(m, b)
+}
+func (m *String) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
+	return xxx_messageInfo_String.Marshal(b, m, deterministic)
+}
+func (dst *String) XXX_Merge(src proto.Message) {
+	xxx_messageInfo_String.Merge(dst, src)
+}
+func (m *String) XXX_Size() int {
+	return xxx_messageInfo_String.Size(m)
+}
+func (m *String) XXX_DiscardUnknown() {
+	xxx_messageInfo_String.DiscardUnknown(m)
+}
+
+var xxx_messageInfo_String proto.InternalMessageInfo
+
+func (m *String) GetValue() string {
+	if m != nil {
+		return m.Value
+	}
+	return ""
+}
+
+func init() {
+	proto.RegisterType((*String)(nil), "main.String")
+}
+
+// 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
+
+// HelloServiceClient is the client API for HelloService service.
+//
+// For semantics around ctx use and closing/ending streaming RPCs, please refer to https://godoc.org/google.golang.org/grpc#ClientConn.NewStream.
+type HelloServiceClient interface {
+	Hello(ctx context.Context, in *String, opts ...grpc.CallOption) (*String, error)
+}
+
+type helloServiceClient struct {
+	cc *grpc.ClientConn
+}
+
+func NewHelloServiceClient(cc *grpc.ClientConn) HelloServiceClient {
+	return &helloServiceClient{cc}
+}
+
+func (c *helloServiceClient) Hello(ctx context.Context, in *String, opts ...grpc.CallOption) (*String, error) {
+	out := new(String)
+	err := c.cc.Invoke(ctx, "/main.HelloService/Hello", in, out, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+// HelloServiceServer is the server API for HelloService service.
+type HelloServiceServer interface {
+	Hello(context.Context, *String) (*String, error)
+}
+
+func RegisterHelloServiceServer(s *grpc.Server, srv HelloServiceServer) {
+	s.RegisterService(&_HelloService_serviceDesc, srv)
+}
+
+func _HelloService_Hello_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(String)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(HelloServiceServer).Hello(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: "/main.HelloService/Hello",
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(HelloServiceServer).Hello(ctx, req.(*String))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+var _HelloService_serviceDesc = grpc.ServiceDesc{
+	ServiceName: "main.HelloService",
+	HandlerType: (*HelloServiceServer)(nil),
+	Methods: []grpc.MethodDesc{
+		{
+			MethodName: "Hello",
+			Handler:    _HelloService_Hello_Handler,
+		},
+	},
+	Streams:  []grpc.StreamDesc{},
+	Metadata: "hello.proto",
+}
+
+func init() { proto.RegisterFile("hello.proto", fileDescriptor_hello_5dd9d59ecabc789f) }
+
+var fileDescriptor_hello_5dd9d59ecabc789f = []byte{
+	// 107 bytes of a gzipped FileDescriptorProto
+	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0xe2, 0xe2, 0xce, 0x48, 0xcd, 0xc9,
+	0xc9, 0xd7, 0x2b, 0x28, 0xca, 0x2f, 0xc9, 0x17, 0x62, 0xc9, 0x4d, 0xcc, 0xcc, 0x53, 0x92, 0xe3,
+	0x62, 0x0b, 0x2e, 0x29, 0xca, 0xcc, 0x4b, 0x17, 0x12, 0xe1, 0x62, 0x2d, 0x4b, 0xcc, 0x29, 0x4d,
+	0x95, 0x60, 0x54, 0x60, 0xd4, 0xe0, 0x0c, 0x82, 0x70, 0x8c, 0x8c, 0xb9, 0x78, 0x3c, 0x40, 0x9a,
+	0x82, 0x53, 0x8b, 0xca, 0x32, 0x93, 0x53, 0x85, 0x94, 0xb9, 0x58, 0xc1, 0x7c, 0x21, 0x1e, 0x3d,
+	0x90, 0x7e, 0x3d, 0x88, 0x66, 0x29, 0x14, 0x5e, 0x12, 0x1b, 0xd8, 0x06, 0x63, 0x40, 0x00, 0x00,
+	0x00, 0xff, 0xff, 0xa1, 0x2a, 0xa2, 0x5a, 0x70, 0x00, 0x00, 0x00,
+}

examples/ch4-04-grpc/basic/client/hello.proto

@@ -0,0 +1,11 @@
+syntax = "proto3";
+
+package main;
+
+message String {
+	string value = 1;
+}
+
+service HelloService {
+	rpc Hello (String) returns (String);
+}

examples/ch4-04-grpc/basic/client/main.go

@@ -0,0 +1,49 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"net"
+
+	"google.golang.org/grpc"
+)
+
+type HelloServiceImpl struct{}
+
+func (p *HelloServiceImpl) Hello(ctx context.Context, args *String) (*String, error) {
+	reply := &String{Value: "hello:" + args.GetValue()}
+	return reply, nil
+}
+
+func main() {
+	go startGrpcServer()
+	doClientWork()
+}
+
+func startGrpcServer() {
+	grpcServer := grpc.NewServer()
+	RegisterHelloServiceServer(grpcServer, &HelloServiceImpl{})
+
+	lis, err := net.Listen("tcp", ":1234")
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	grpcServer.Serve(lis)
+}
+
+func doClientWork() {
+	conn, err := grpc.Dial("localhost:1234", grpc.WithInsecure())
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer conn.Close()
+
+	client := NewHelloServiceClient(conn)
+	reply, err := client.Hello(context.Background(), &String{Value: "hello"})
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Println(reply.GetValue())
+}