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decoder.go
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decoder.go
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// Copyright 2016 CodisLabs. All Rights Reserved.
// Licensed under the MIT (MIT-LICENSE.txt) license.
package redis
import (
"bufio"
"bytes"
"io"
"strconv"
"pkg/libs/errors"
"pkg/libs/log"
)
var (
ErrBadRespCRLFEnd = errors.New("bad resp CRLF end")
ErrBadRespBytesLen = errors.New("bad resp bytes len")
ErrBadRespArrayLen = errors.New("bad resp array len")
)
type Decoder struct {
r *bufio.Reader
}
func NewDecoder(r *bufio.Reader) *Decoder {
return &Decoder{r: r}
}
func Decode(r *bufio.Reader) (Resp, error) {
d := &Decoder{r}
return d.decodeResp(0)
}
func MustDecodeOpt(d *Decoder) Resp {
resp, err := d.decodeResp(0)
if err != nil {
log.PanicError(err, "decode redis resp failed")
}
return resp
}
func MustDecode(r *bufio.Reader) Resp {
resp, err := Decode(r)
if err != nil {
log.PanicError(err, "decode redis resp failed")
}
return resp
}
func DecodeFromBytes(p []byte) (Resp, error) {
r := bufio.NewReader(bytes.NewReader(p))
return Decode(r)
}
func MustDecodeFromBytes(p []byte) Resp {
resp, err := DecodeFromBytes(p)
if err != nil {
log.PanicError(err, "decode redis resp from bytes failed")
}
return resp
}
func (d *Decoder) decodeResp(depth int) (Resp, error) {
t, err := d.decodeType()
if err != nil {
return nil, err
}
switch t {
case typeString:
resp := &String{}
resp.Value, err = d.decodeText()
return resp, err
case typeError:
resp := &Error{}
resp.Value, err = d.decodeText()
return resp, err
case typeInt:
resp := &Int{}
resp.Value, err = d.decodeInt()
return resp, err
case typeBulkBytes:
resp := &BulkBytes{}
resp.Value, err = d.decodeBulkBytes()
return resp, err
case typeArray:
resp := &Array{}
resp.Value, err = d.decodeArray(depth)
return resp, err
default:
if depth != 0 {
return nil, errors.Errorf("bad resp type %s", t)
}
if err = d.r.UnreadByte(); err != nil {
return nil, errors.Trace(err)
}
return d.decodeSingleLineBulkBytesArray()
}
}
func (d *Decoder) decodeType() (respType, error) {
ReadByte:
if b, err := d.r.ReadByte(); err != nil {
return 0, errors.Trace(err)
} else if string(b) == "\n" {
/*
* Bugfix: see https://github.com/alibaba/RedisShake/issues/204.
* "\n" occurs before and after the +FULLRESYNC response sometimes at the redis version of 3.2.7.
*/
goto ReadByte
} else {
return respType(b), nil
}
}
func (d *Decoder) decodeText() ([]byte, error) {
b, err := d.r.ReadBytes('\n')
if err != nil {
return make([]byte, 0, 0), errors.Trace(err)
}
if n := len(b) - 2; n < 0 || b[n] != '\r' {
return make([]byte, 0, 0), errors.Trace(ErrBadRespCRLFEnd)
} else {
//return string(b[:n]), nil
return b[:n], nil
}
}
func (d *Decoder) decodeInt() (int64, error) {
b, err := d.decodeText()
if err != nil {
return 0, err
}
if n, err := strconv.ParseInt(string(b), 10, 64); err != nil {
return 0, errors.Trace(err)
} else {
return n, nil
}
}
func (d *Decoder) decodeBulkBytes() ([]byte, error) {
n, err := d.decodeInt()
if err != nil {
return nil, err
}
if n < -1 {
return nil, errors.Trace(ErrBadRespBytesLen)
} else if n == -1 {
return nil, nil
}
b := make([]byte, n+2)
if _, err := io.ReadFull(d.r, b); err != nil {
return nil, errors.Trace(err)
}
if b[n] != '\r' || b[n+1] != '\n' {
return nil, errors.Trace(ErrBadRespCRLFEnd)
}
return b[:n], nil
}
func (d *Decoder) decodeArray(depth int) ([]Resp, error) {
n, err := d.decodeInt()
if err != nil {
return nil, err
}
if n < -1 {
return nil, errors.Trace(ErrBadRespArrayLen)
} else if n == -1 {
return nil, nil
}
a := make([]Resp, n)
for i := 0; i < len(a); i++ {
if a[i], err = d.decodeResp(depth + 1); err != nil {
return nil, err
}
}
return a, nil
}
func (d *Decoder) decodeSingleLineBulkBytesArray() (Resp, error) {
b, err := d.r.ReadBytes('\n')
if err != nil {
return nil, errors.Trace(err)
}
if n := len(b) - 2; n < 0 || b[n] != '\r' {
return nil, errors.Trace(ErrBadRespCRLFEnd)
} else {
resp := &Array{}
for l, r := 0, 0; r <= n; r++ {
if r == n || b[r] == ' ' {
if l < r {
resp.Value = append(resp.Value, &BulkBytes{b[l:r]})
}
l = r + 1
}
}
return resp, nil
}
}