go语言实现的memcache协议服务的方法

package memcachep
import (
    "bufio"
    "fmt"
    "io"
    "strconv"
    "strings"
)
//mc请求产生一个request对象
type MCRequest struct {
    //请求命令
    Opcode CommandCode
    //key
    Key string
    //请求内容
    Value []byte
    //请求标识
    Flags int
    //请求内容长度
    Length int
    //过期时间
    Expires int64
}
//request to string
func (req *MCRequest) String() string {
    return fmt.Sprintf("{MCRequest opcode=%s, bodylen=%d, key=‘%s‘}",
        req.Opcode, len(req.Value), req.Key)
}
//将socket请求内容 解析为一个MCRequest对象
func (req *MCRequest) Receive(r *bufio.Reader) error {
    line, _, err := r.ReadLine()
    if err != nil || len(line) == 0 {
        return io.EOF
    }
    params := strings.Fields(string(line))
    command := CommandCode(params[0])
    switch command {
    case SET, ADD, REPLACE:
        req.Opcode = command
        req.Key = params[1]
        req.Length, _ = strconv.Atoi(params[4])
        value := make([]byte, req.Length+2)
        io.ReadFull(r, value)
        req.Value = make([]byte, req.Length)
        copy(req.Value, value)
    case GET:
        req.Opcode = command
        req.Key = params[1]
        RunStats["cmd_get"].(*CounterStat).Increment(1)
    case STATS:
        req.Opcode = command
        req.Key = ""
    case DELETE:
        req.Opcode = command
        req.Key = params[1]
    }
    return err
}

package memcachep
import (
    "fmt"
    "io"
)
type MCResponse struct {
    //命令
    Opcoed CommandCode
    //返回状态
    Status Status
    //key
    Key string
    //返回内容
    Value []byte
    //返回标识
    Flags int
    //错误
    Fatal bool
}
//解析response 并把返回结果写入socket链接
func (res *MCResponse) Transmit(w io.Writer) (err error) {
    switch res.Opcoed {
    case STATS:
        _, err = w.Write(res.Value)
    case GET:
        if res.Status == SUCCESS {
            rs := fmt.Sprintf("VALUE %s %d %d\r\n%s\r\nEND\r\n", res.Key, res.Flags, len(res.Value), res.Value)
            _, err = w.Write([]byte(rs))
        } else {
            _, err = w.Write([]byte(res.Status.ToString()))
        }
    case SET, REPLACE:
        _, err = w.Write([]byte(res.Status.ToString()))
    case DELETE:
        _, err = w.Write([]byte("DELETED\r\n"))
    }
    return
}

package memcachep
import (
    "fmt"
)
type action func(req *MCRequest, res *MCResponse)
var actions = map[CommandCode]action{
    STATS: StatsAction,
}
//等待分发处理
func waitDispatch(rc chan chanReq) {
    for {
        input := <-rc
        input.response <- dispatch(input.request)
    }
}
//分发请求到响应的action操作函数上去
func dispatch(req *MCRequest) (res *MCResponse) {
    if h, ok := actions[req.Opcode]; ok {
        res = &MCResponse{}
        h(req, res)
    } else {
        return notFound(req)
    }
    return
}
//未支持命令
func notFound(req *MCRequest) *MCResponse {
    var response MCResponse
    response.Status = UNKNOWN_COMMAND
    return &response
}
//给request绑定上处理程序
func BindAction(opcode CommandCode, h action) {
    actions[opcode] = h
}
//stats
func StatsAction(req *MCRequest, res *MCResponse) {
    res.Fatal = false
    stats := ""
    for key, value := range RunStats {
        stats += fmt.Sprintf("STAT %s %s\r\n", key, value)
    }
    stats += "END\r\n"
    res.Value = []byte(stats)
}