rservcli.go

/*Rserve go client */
package rservcli

import (
	"bytes"
	"encoding/binary"
	"errors"
	"fmt"
	"net"
	"strings"
)

/*
 return mkint32($cmd) . mkint32($n + 4) . mkint32(0) . mkint32(0) . chr(4) . mkint24($n) . $string;
*/
type Qhdr struct {
	Cmd   int32 /* command */
	Len   int32 /* length of the packet minus header (ergo -16) */
	MsgId int32 /* message id (since 1.8) [WAS:data offset behind header (ergo usually 0)] */
	Res   int32 /* high 32-bit of the packet length (since 0103
	and supported on 64-bit platforms only)
	aka "lenhi", but the name was not changed to
	maintain compatibility */
}

func NewQhdr(cmd int32, data string) *Qhdr {
	head := new(Qhdr)
	head.Cmd = cmd
	head.Len = int32(len(data) + 4)
	return head
}

//MkpStr
func MakeBytes(cmd int32, data string) []byte {
	data = strings.Replace(data, "\r", "\n", -1)
	buff := new(bytes.Buffer)
	header := NewQhdr(cmd, data)
	binary.Write(buff, binary.LittleEndian, header) //eval
	binary.Write(buff, binary.LittleEndian, int8(4))
	binary.Write(buff, binary.LittleEndian, int32(len(data)))
	buff.Truncate(len(buff.Bytes()) - 1) // truncate 36bit int to 24 bit int -- 3 bytes
	// data string
	binary.Write(buff, binary.LittleEndian, []byte(data))
	return buff.Bytes()
}

func RInit() (net.Conn, error) {
	conn, err := net.Dial("tcp", "127.0.0.1:6311")
	if err != nil {
		fmt.Printf("Cannot connect to %v", err)
	}
	return conn, err
}

func REval(conn net.Conn, data string) (int, error) {
	send := MakeBytes(0x002, data) //CMD_voidEval = 0x002
	buff := new(bytes.Buffer)
	binary.Write(buff, binary.LittleEndian, send)
	// binary.Write(buff, binary.LittleEndian, int32(len(send)))
	// binary.Write(buff, binary.LittleEndian, int32(0))
	n, err := conn.Write(buff.Bytes())
	if err != nil {
		fmt.Printf("%v", err)
	}
	return n, err
}

func CheckResp(conn net.Conn) error {
	read_buff := make([]byte, 32)
	conn.Read(read_buff) // read protocol head
	conn.Read(read_buff)
	status := read_buff[0:3]
	fmt.Print(string(status))
	if status[0] == 1 && status[2] == 1 {
		fmt.Print("ok")
	} else {
		err := errors.New("Something wrong with R script.")
		return err
	}
	return nil
}

// func NewRespHdr(buff []byte) *RespHdr {
// head := new(RespHdr)
// head.XTType = buff[0]
// t_byte := make([]byte, 4)
// for i := 1; i < 4; i++ {
// t_byte[i-1] = buff[i]
// }
// fmt.Print(head.XTType)
// fmt.Print(t_byte)
// head.BodyLen = binary.LittleEndian.Uint32(t_byte)
// return head

// }