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memcache_req.go
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memcache_req.go
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// Package mc implements memcached text protocol: https://github.com/memcached/memcached/blob/master/doc/protocol.txt.
// binary protocol () has not been implemented.
package mc
import (
"bufio"
"fmt"
"io"
"strconv"
"strings"
)
// RealtimeMaxDelta is max delta time.
const RealtimeMaxDelta = 60 * 60 * 24 * 30
// Request is a generic memcached request.
// Some fields are meaningless for some special commands and they are zero values.
// Exptime will always be 0 or epoch (in seconds)
type Request struct {
// Command is memcached command name, see https://github.com/memcached/memcached/wiki/Commands
Command string
Key string
Keys []string
Flags string
Exptime int64 // in second
Data []byte
Value uint64
Cas string
Noreply bool
}
// Error is memcached protocol error.
type Error struct {
Description string
}
func (e Error) Error() string {
return fmt.Sprintf("MC Protocol error: %s", e.Description)
}
// NewError creates a new error.
func NewError(description string) Error {
return Error{description}
}
// ReadRequest reads a request from reader
func ReadRequest(r *bufio.Reader) (req *Request, err error) {
lineBytes, _, err := r.ReadLine()
if err != nil {
return nil, err
}
line := string(lineBytes)
arr := strings.Fields(line)
if len(arr) < 1 {
return nil, NewError("empty line")
}
switch arr[0] {
case "set", "add", "replace", "append", "prepend":
// format:
// <command name> <key> <flags> <exptime> <bytes> [noreply]\r\n
// <data block>\r\n
if len(arr) < 5 {
return nil, NewError(fmt.Sprintf("too few params to command %q", arr[0]))
}
req := &Request{}
req.Command = arr[0]
req.Key = arr[1]
req.Flags = arr[2]
// always use epoch
req.Exptime, err = strconv.ParseInt(arr[3], 10, 64)
if err != nil {
return nil, NewError("cannot read exptime " + err.Error())
}
// if req.Exptime > 0 {
// if req.Exptime <= RealtimeMaxDelta { // <= 30 days
// req.Exptime = time.Now().Unix() + req.Exptime
// }
// }
bytes, err := strconv.Atoi(arr[4])
if err != nil {
return nil, NewError("cannot read bytes " + err.Error())
}
if len(arr) > 5 && arr[5] == "noreply" {
req.Noreply = true
}
req.Data = make([]byte, bytes)
n, err := io.ReadFull(r, req.Data)
if err != nil {
return nil, err
}
if n != bytes {
return nil, NewError(fmt.Sprintf("Read only %d bytes of %d bytes of expected data", n, bytes))
}
c, err := r.ReadByte()
if err != nil {
return nil, err
}
if c != '\r' {
return nil, NewError("expected \\r")
}
c, err = r.ReadByte()
if err != nil {
return nil, err
}
if c != '\n' {
return nil, NewError("expected \\n")
}
return req, nil
case "cas":
// format:
// cas <key> <flags> <exptime> <bytes> <cas unique> [noreply]\r\n
// <data block>\r\n
if len(arr) < 6 {
return nil, NewError(fmt.Sprintf("too few params to command %q", arr[0]))
}
req := &Request{}
req.Command = arr[0]
req.Key = arr[1]
req.Flags = arr[2]
req.Exptime, err = strconv.ParseInt(arr[3], 10, 64)
if err != nil {
return nil, NewError("cannot read exptime " + err.Error())
}
// if req.Exptime > 0 {
// if req.Exptime <= RealtimeMaxDelta { // <= 30 days
// req.Exptime = time.Now().Unix() + req.Exptime
// }
// }
bytes, err := strconv.Atoi(arr[4])
if err != nil {
return nil, err
}
req.Cas = arr[5]
if len(arr) > 6 && arr[6] == "noreply" {
req.Noreply = true
}
req.Data = make([]byte, bytes)
n, err := io.ReadFull(r, req.Data)
if err != nil {
return nil, err
}
if n != bytes {
return nil, NewError(fmt.Sprintf("Read only %d bytes of %d bytes of expected data", n, bytes))
}
c, err := r.ReadByte()
if err != nil {
return nil, err
}
if c != '\r' {
return nil, NewError("expected \\r")
}
c, err = r.ReadByte()
if err != nil {
return nil, err
}
if c != '\n' {
return nil, NewError("expected \\n")
}
return req, nil
case "delete":
// format:
// delete <key> [noreply]\r\n
if len(arr) < 2 {
return nil, NewError(fmt.Sprintf("too few params to command %q", arr[0]))
}
req := &Request{}
req.Command = arr[0]
req.Key = arr[1]
if len(arr) > 2 && arr[2] == "noreply" {
req.Noreply = true
}
return req, nil
case "get", "gets":
// format:
// get <key>*\r\n
// gets <key>*\r\n
if len(arr) < 2 {
return nil, NewError(fmt.Sprintf("too few params to command %q", arr[0]))
}
req := &Request{}
req.Command = arr[0]
req.Keys = arr[1:]
return req, nil
case "incr", "decr":
// format:
// incr <key> <value> [noreply]\r\n
// decr <key> <value> [noreply]\r\n
if len(arr) < 3 {
return nil, NewError(fmt.Sprintf("too few params to command %q", arr[0]))
}
req := &Request{}
req.Command = arr[0]
req.Key = arr[1]
req.Value, err = strconv.ParseUint(arr[2], 10, 64)
if err != nil {
return nil, NewError("cannot read value " + err.Error())
}
if len(arr) > 3 && arr[3] == "noreply" {
req.Noreply = true
}
return req, nil
case "touch":
// format:
// touch <key> <exptime> [noreply]\r\n
if len(arr) < 3 {
return nil, NewError(fmt.Sprintf("too few params to command %q", arr[0]))
}
req := &Request{}
req.Command = arr[0]
req.Key = arr[1]
req.Exptime, err = strconv.ParseInt(arr[2], 10, 64)
if err != nil {
return nil, NewError("cannot read exptime " + err.Error())
}
// if req.Exptime > 0 {
// if req.Exptime <= RealtimeMaxDelta { // <= 30 days
// req.Exptime = time.Now().Unix() + req.Exptime
// }
// }
if len(arr) > 3 && arr[3] == "noreply" {
req.Noreply = true
}
return req, nil
case "flush_all":
// flush_all [delay]\r\n
req := &Request{Command: arr[0]}
if len(arr) > 1 {
req.Exptime, err = strconv.ParseInt(arr[1], 10, 64)
if err != nil {
return nil, NewError("cannot read delay " + err.Error())
}
}
return req, nil
case "version", "quit":
// version\r\n
// quit\r\n
return &Request{Command: arr[0]}, nil
case "stats":
// stats\r\n
// stats <args>\r\n
req := &Request{Command: arr[0]}
if len(arr) > 1 {
req.Keys = arr[1:]
}
return req, nil
}
return nil, NewError(fmt.Sprintf("unknown command %q", arr[0]))
}