server.go

package goRPC

import (
	"encoding/json"
	"errors"
	"fmt"
	"goRPC/Maincodec/codec"
	"goRPC/serviceRegister"
	"io"
	"log"
	"net"
	"net/http"
	"reflect"
	"strings"
	"sync"
	"time"
)

const MagicNumber = 0x3bef5c

type Option struct {
	MagicNumber    int           //MagicNumber标记这是一个rcp请求
	CodecType      codec.Type    //客户端可以选择不同的编解码器对正文进行编码,这里只实现了god
	ConnectTimeout time.Duration //超时连接
	HandleTimeout  time.Duration
}

var DefaultOption = &Option{
	MagicNumber:    MagicNumber,
	CodecType:      codec.GobType,
	ConnectTimeout: time.Second * 10, //设置超时时间
}

// RPC Server
type Server struct {
	ServiceMap sync.Map
}

// return new server
func NewServer() *Server {
	return &Server{}
}

// 默认实例
var DefaultServer = NewServer()

// 接收请求
func (server *Server) Accept(lis net.Listener) {
	for {
		conn, err := lis.Accept()
		if err != nil {
			log.Println("rpc server: accept error:", err)
			return
		}
		//创建服务器连接
		go server.ServeConn(conn)
	}
}

// 接收请求
func Accept(lis net.Listener) { DefaultServer.Accept(lis) }

func (server *Server) ServeConn(conn io.ReadWriteCloser) {
	defer func() { _ = conn.Close() }()
	var opt Option
	//反序列化，读取消息
	if err := json.NewDecoder(conn).Decode(&opt); err != nil {
		log.Println("rpc server: options error: ", err)
	}
	//检查MagicNumber是否对应
	if opt.MagicNumber != MagicNumber {
		log.Printf("rpc server: invalid magic number %x", opt.MagicNumber)
	}
	//检查编码器是否正确
	f := codec.NewCodecFuncMap[opt.CodecType]
	if f == nil {
		log.Printf("rpc server: invalid codec type %s", opt.CodecType)
	}
	server.serveCodec(f(conn), &opt)
}

var invalidRequest = struct{}{}

func (server *Server) serveCodec(cc codec.Codec, opt *Option) {
	sending := new(sync.Mutex) //锁住线程资源
	wg := new(sync.WaitGroup)  //等待所有请求被处理完毕
	for {
		//读取请求
		req, err := server.readRequest(cc)
		if err != nil {
			if req == nil {
				break // it's not possible to recover, so close the connection
			}
			req.h.Error = err.Error()
			server.sendResponse(cc, req.h, invalidRequest, sending)
			continue
		}
		wg.Add(1)
		//并发执行处理请求
		go server.handleRequest(cc, req, sending, wg, opt.HandleTimeout)
	}
	//等待请求结束
	wg.Wait()
	//关闭请求
	_ = cc.Close()
}

// request stores all information of a call
type request struct {
	h            *codec.Header // 请求头
	argv, replyv reflect.Value // argv and replyv of request
	mtype        *serviceRegister.MethodType
	svc          *serviceRegister.Service
}

// 读取请求
func (server *Server) readRequestHeader(cc codec.Codec) (*codec.Header, error) {
	var h codec.Header
	if err := cc.ReadHeader(&h); err != nil {
		if err != io.EOF && err != io.ErrUnexpectedEOF {
			log.Println("rpc server: read header error:", err)
		}
		return nil, err
	}
	return &h, nil
}

// 处理请求
func (server *Server) readRequest(cc codec.Codec) (*request, error) {
	h, err := server.readRequestHeader(cc)
	if err != nil {
		return nil, err
	}
	req := &request{h: h}
	req.svc, req.mtype, err = server.findService(h.ServiceMethod)
	if err != nil {
		return req, err
	}
	req.argv = req.mtype.NewArgv()
	req.replyv = req.mtype.NewReplyv()
	argvi := req.argv.Interface()
	//确保argvi是一个指针，ReadBody需要一个指针作为参数
	if req.argv.Type().Kind() != reflect.Ptr {
		argvi = req.argv.Addr().Interface()
	}
	if err = cc.ReadBody(argvi); err != nil {
		log.Println("rpc server: read argv err:", err)
		return req, err
	}
	return req, nil
}

// 回复请求
func (server *Server) sendResponse(cc codec.Codec, h *codec.Header, body interface{}, sending *sync.Mutex) {
	sending.Lock()
	defer sending.Unlock()
	if err := cc.Write(h, body); err != nil {
		log.Println("rpc server: write response error:", err)
	}
}

// 处理请求
func (server *Server) handleRequest(cc codec.Codec, req *request, sending *sync.Mutex, wg *sync.WaitGroup, timeout time.Duration) {
	// TODO, should call registered rpc methods to get the right replyv
	// day 1, just print argv and send a hello message
	defer wg.Done()
	called := make(chan struct{})
	sent := make(chan struct{})
	go func() {
		err := req.svc.Call(req.mtype, req.argv, req.replyv)
		called <- struct{}{}
		if err != nil {
			req.h.Error = err.Error()
			server.sendResponse(cc, req.h, invalidRequest, sending)
			sent <- struct{}{}
			return
		}
		server.sendResponse(cc, req.h, req.replyv.Interface(), sending)
		sent <- struct{}{}
	}()
	if timeout == 0 {
		<-called
		<-sent
		return
	}
	select {
	case <-time.After(timeout): //先于 called 接收到消息，说明处理已经超时
		req.h.Error = fmt.Sprintf("rpc server: request handle timeout: expect within %s", timeout)
		server.sendResponse(cc, req.h, invalidRequest, sending)
	case <-called:
		<-sent
	}
	/*


		err := req.svc.Call(req.mtype, req.argv, req.replyv)
		if err != nil {
			req.h.Error = err.Error()
			server.sendResponse(cc, req.h, invalidRequest, sending)
			return
		}
		server.sendResponse(cc, req.h, req.replyv.Interface(), sending)
	*/
}

// Register publishes in the server the set of methods of the
func (server *Server) Register(rcvr interface{}) error {
	s := serviceRegister.NewService(rcvr)
	if _, dup := server.ServiceMap.LoadOrStore(s.Name, s); dup {
		return errors.New("rpc: service already defined: " + s.Name)
	}
	return nil
}

// Register publishes the receiver's methods in the DefaultServer.
func Register(rcvr interface{}) error { return DefaultServer.Register(rcvr) }

func (server *Server) findService(serviceMethod string) (svc *serviceRegister.Service, mtype *serviceRegister.MethodType, err error) {
	dot := strings.LastIndex(serviceMethod, ".")
	if dot < 0 {
		err = errors.New("rpc server: service/method request ill-formed: " + serviceMethod)
		return
	}
	//找到实例，再从实列中找到对应的method
	serviceName, methodName := serviceMethod[:dot], serviceMethod[dot+1:]
	svci, ok := server.ServiceMap.Load(serviceName)
	if !ok {
		err = errors.New("rpc server: can't find service " + serviceName)
		return
	}
	svc = svci.(*serviceRegister.Service)
	mtype = svc.Method[methodName]
	if mtype == nil {
		err = errors.New("rpc server: can't find method " + methodName)
	}
	return
}

// 支持http协议
const (
	connected        = "200 Connected to RPC"
	defaultRPCPath   = "/gorpc"
	defaultDebugPath = "/debug/gorpc"
)

// ServeHTTP实现了一个http处理程序，用于回答RPC请求
func (server *Server) ServeHTTP(w http.ResponseWriter, req *http.Request) {
	if req.Method != "CONNECT" {
		w.Header().Set("Content-Type", "text/plain; charset=utf-8")
		w.WriteHeader(http.StatusMethodNotAllowed)
		_, _ = io.WriteString(w, "405 must CONNECT\n")
		return
	}
	conn, _, err := w.(http.Hijacker).Hijack()
	if err != nil {
		log.Print("rpc hijacking ", req.RemoteAddr, ": ", err.Error())
		return
	}
	_, _ = io.WriteString(conn, "HTTP/1.0 "+connected+"\n\n")
	server.ServeConn(conn)
}

// HandleHTTP registers an HTTP handler for RPC messages on rpcPath.
// It is still necessary to invoke http.Serve(), typically in a go statement.
func (server *Server) HandleHTTP() {
	http.Handle(defaultRPCPath, server)
	http.Handle(defaultDebugPath, DebugHTTP{server})
	log.Println("rpc server debug path:", defaultDebugPath)
}

// HandleHTTP is a convenient approach for default server to register HTTP handlers
func HandleHTTP() {
	DefaultServer.HandleHTTP()
}