srpc/server.go

package srpc

import (
	"bytes"
	"errors"
	"fmt"
	"log"
	"net"
	"reflect"
	"sync"
)

type argumentType uint8

type responseStatus uint8

const (
	OK  responseStatus = 0
	ERR responseStatus = 1
)

var RESPONSE_HEADER_SIZE = int32(9)

type responseHeader struct {
	size   int64
	status responseStatus
}

type parseInputsFunc func(in []byte) (ret []reflect.Value)
type parseOutputsFunc func(in []reflect.Value) (ret []byte)

type service struct {
	f    reflect.Value
	fin  parseInputsFunc
	fout parseOutputsFunc
}

type Server struct {
	ed         IEncoderDecoder
	serviceMap sync.Map
}

func (server *Server) ServeConn(conn net.Conn) {
	var fs service

	dec := server.ed.NewDecoder(conn)

	var req request
	dec.Decode(&req)
	fmt.Println(req)

	if fsRaw, ok := server.serviceMap.Load(req.FuncName); !ok {
		log.Printf("srpc: Call to unknown method: '%s'", req.FuncName)
		return
	} else {
		fs = fsRaw.(service)
	}

	inputs := fs.fin(req.Payload)
	outputs := fs.f.Call(inputs)
	log.Println(outputs)

	respData := fs.fout(outputs)
	respSize := int64(len(respData))
	enc := server.ed.NewEncoder(conn)
	enc.Encode(respSize)
	enc.Encode(respData)
}

func (server *Server) Accept(ln net.Listener) {
	for {
		conn, err := ln.Accept()
		if err != nil {
			log.Printf("srpc: accept: %s", err.Error())
			return
		}
		go server.ServeConn(conn)
	}
}

func (server *Server) RegisterName(name string, rcvr interface{}) (err error) {
	if _, ok := server.serviceMap.Load(name); ok {
		return errors.New("srpc: Function with name '" + name + "' already registerd")
	}
	ft := reflect.TypeOf(rcvr)
	fv := reflect.ValueOf(rcvr)

	nIn := ft.NumIn()

	fs := service{}

	fs.fin = func(in []byte) (ret []reflect.Value) {
		var b bytes.Buffer
		if _, err = b.Write(in); err != nil {
			return nil
		}
		decoder := server.ed.NewDecoder(&b)

		ret = make([]reflect.Value, nIn)
		for i := 0; i < nIn; i++ {
			in := reflect.New(ft.In(i))
			if err = decoder.Decode(in.Interface()); err != nil {
				fmt.Println(err)
				return nil
			}
			ret[i] = reflect.Indirect(in)
		}

		return ret
	}

	fs.fout = func(in []reflect.Value) (ret []byte) {
		var b bytes.Buffer
		encoder := server.ed.NewEncoder(&b)

		for _, v := range in {
			if v.Type() == reflect.TypeOf((*error)(nil)).Elem() {
				if v.IsNil() {
					if err := encoder.Encode(string("")); err != nil {
						fmt.Println(err)
						return nil
					}
				} else {
					if err := encoder.Encode(v.Interface().(error).Error()); err != nil {
						fmt.Println(err)
						return nil
					}
				}
			} else {
				if err := encoder.Encode(v.Interface()); err != nil {
					fmt.Println(err)
					return nil
				}
			}
		}

		return b.Bytes()
	}

	fs.f = fv
	server.serviceMap.Store(name, fs)

	return nil
}

func (server *Server) CallName(name string, args ...interface{}) (ret []byte, err error) {
	var b bytes.Buffer
	var fs service
	encoder := server.ed.NewEncoder(&b)

	if fsRaw, ok := server.serviceMap.Load(name); !ok {
		return nil, errors.New("srpc: Call to unknown method: '" + name + "'")
	} else {
		fs = fsRaw.(service)
	}

	for _, a := range args {
		if err := encoder.Encode(a); err != nil {
			return nil, errors.New("srpc: Error: '" + err.Error() + "'")
		}
	}
	inputs := fs.fin(b.Bytes())
	outputs := fs.f.Call(inputs)
	return fs.fout(outputs), nil
}

func NewServer(ed IEncoderDecoder) *Server {
	ret := &Server{}
	ret.ed = ed
	return ret
}

func NewDefaultServer() *Server {
	ret := NewServer(NewEncoderDecoder())
	return ret
}

var DefaultServer = NewDefaultServer()