- 本文实现Redis的协议层,协议层负责解析指令,然后将指令交给核心database执行
- echo database用来测试协议层的代码
- https://github.com/csgopher/go-redis
- 本文涉及以下文件:
conn:定义连接接口
interface/reply:定义各类响应接口
consts:定义常用响应
errors:定义错误响应
resp/reply:实现reply接口
parser:解析指令
conn:实现conn接口
handler:解析指令再交给database层
database:定义核心层接口
echo_database:测试
RESP协议
RESP是客户端与服务端通信的协议,格式有五种:
正常回复:以“+”开头,以“\r\n”结尾的字符串形式
错误回复:以“-”开头,以“\r\n”结尾的字符串形式
整数:以“:”开头,以“\r\n”结尾的字符串形式
多行字符串:以“$”开头,后跟实际发送字节数,再以“\r\n”开头和结尾
$3\r\nabc\r\n
数组:以“*”开头,后跟成员个数
SET key value
*3\r\n$3\r\nSET\r\n$3\r\nkey\r\n$5\r\nvalue\r\n
客户端和服务器发送的命令或数据一律以 \r\n (CRLF)作为换行符。
当我们输入*3\r\n$3\r\nSET\r\n$3\r\nkey\r\n$5\r\nvalue\r\n这样一串命令,服务端接收到的是如下的命令:
*3\r\n
$3\r\n
SET\r\n
$3\r\n
key\r\n
$5\r\n
value\r\n
interface/resp/conn.go
type Connection interface {
Write([]byte) error
GetDBIndex() int
SelectDB(int)
}
interface/resp/reply.go
type Reply interface {
ToBytes() []byte
}
Connection接口:Redis客户端的一个连接
Write:给客户端回复消息
GetDBIndex:Redis有16个DB
Reply接口:响应接口
resp/reply/consts.go
type PongReply struct{}
var pongBytes = []byte("+PONG\r\n")
func (r *PongReply) ToBytes() []byte {
return pongBytes
}
var thePongReply = new(PongReply)
// 回复pong
func MakePongReply() *PongReply {
return thePongReply
}
type OkReply struct{}
var okBytes = []byte("+OK\r\n")
func (r *OkReply) ToBytes() []byte {
return okBytes
}
var theOkReply = new(OkReply)
// 回复ok
func MakeOkReply() *OkReply {
return theOkReply
}
var nullBulkBytes = []byte("$-1\r\n")
type NullBulkReply struct{}
func (r *NullBulkReply) ToBytes() []byte {
return nullBulkBytes
}
// 回复null
func MakeNullBulkReply() *NullBulkReply {
return &NullBulkReply{}
}
var emptyMultiBulkBytes = []byte("*0\r\n")
type EmptyMultiBulkReply struct{}
// 回复空数组
func (r *EmptyMultiBulkReply) ToBytes() []byte {
return emptyMultiBulkBytes
}
type NoReply struct{}
var noBytes = []byte("")
// 回复空
func (r *NoReply) ToBytes() []byte {
return noBytes
}
定义五种回复:回复pong,ok,null,空数组,空
resp/reply/reply.go
type ErrorReply interface {
Error() string
ToBytes() []byte
}
ErrorReply:定义错误接口
resp/reply/errors.go
type UnknownErrReply struct{}
var unknownErrBytes = []byte("-Err unknown\r\n")
func (r *UnknownErrReply) ToBytes() []byte {
return unknownErrBytes
}
func (r *UnknownErrReply) Error() string {
return "Err unknown"
}
type ArgNumErrReply struct {
Cmd string
}
func (r *ArgNumErrReply) ToBytes() []byte {
return []byte("-ERR wrong number of arguments for '" + r.Cmd + "' command\r\n")
}
func (r *ArgNumErrReply) Error() string {
return "ERR wrong number of arguments for '" + r.Cmd + "' command"
}
func MakeArgNumErrReply(cmd string) *ArgNumErrReply {
return &ArgNumErrReply{
Cmd: cmd,
}
}
type SyntaxErrReply struct{}
var syntaxErrBytes = []byte("-Err syntax error\r\n")
var theSyntaxErrReply = &SyntaxErrReply{}
func MakeSyntaxErrReply() *SyntaxErrReply {
return theSyntaxErrReply
}
func (r *SyntaxErrReply) ToBytes() []byte {
return syntaxErrBytes
}
func (r *SyntaxErrReply) Error() string {
return "Err syntax error"
}
type WrongTypeErrReply struct{}
var wrongTypeErrBytes = []byte("-WRONGTYPE Operation against a key ho