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tap.go
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tap.go
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package gomemcached
import (
"bytes"
"encoding/binary"
"fmt"
"io"
"io/ioutil"
"strings"
)
type TapConnectFlag uint32
// Tap connect option flags
const (
BACKFILL = TapConnectFlag(0x01)
DUMP = TapConnectFlag(0x02)
LIST_VBUCKETS = TapConnectFlag(0x04)
TAKEOVER_VBUCKETS = TapConnectFlag(0x08)
SUPPORT_ACK = TapConnectFlag(0x10)
REQUEST_KEYS_ONLY = TapConnectFlag(0x20)
CHECKPOINT = TapConnectFlag(0x40)
REGISTERED_CLIENT = TapConnectFlag(0x80)
FIX_FLAG_BYTEORDER = TapConnectFlag(0x100)
)
// Tap opaque event subtypes
const (
TAP_OPAQUE_ENABLE_AUTO_NACK = 0
TAP_OPAQUE_INITIAL_VBUCKET_STREAM = 1
TAP_OPAQUE_ENABLE_CHECKPOINT_SYNC = 2
TAP_OPAQUE_CLOSE_TAP_STREAM = 7
TAP_OPAQUE_CLOSE_BACKFILL = 8
)
// Tap item flags
const (
TAP_ACK = 1
TAP_NO_VALUE = 2
TAP_FLAG_NETWORK_BYTE_ORDER = 4
)
// TapConnectFlagNames for TapConnectFlag
var TapConnectFlagNames = map[TapConnectFlag]string{
BACKFILL: "BACKFILL",
DUMP: "DUMP",
LIST_VBUCKETS: "LIST_VBUCKETS",
TAKEOVER_VBUCKETS: "TAKEOVER_VBUCKETS",
SUPPORT_ACK: "SUPPORT_ACK",
REQUEST_KEYS_ONLY: "REQUEST_KEYS_ONLY",
CHECKPOINT: "CHECKPOINT",
REGISTERED_CLIENT: "REGISTERED_CLIENT",
FIX_FLAG_BYTEORDER: "FIX_FLAG_BYTEORDER",
}
// TapItemParser is a function to parse a single tap extra.
type TapItemParser func(io.Reader) (interface{}, error)
// TapParseUint64 is a function to parse a single tap uint64.
func TapParseUint64(r io.Reader) (interface{}, error) {
var rv uint64
err := binary.Read(r, binary.BigEndian, &rv)
return rv, err
}
// TapParseUint16 is a function to parse a single tap uint16.
func TapParseUint16(r io.Reader) (interface{}, error) {
var rv uint16
err := binary.Read(r, binary.BigEndian, &rv)
return rv, err
}
// TapParseBool is a function to parse a single tap boolean.
func TapParseBool(r io.Reader) (interface{}, error) {
return true, nil
}
// TapParseVBList parses a list of vBucket numbers as []uint16.
func TapParseVBList(r io.Reader) (interface{}, error) {
num, err := TapParseUint16(r)
if err != nil {
return nil, err
}
n := int(num.(uint16))
rv := make([]uint16, n)
for i := 0; i < n; i++ {
x, err := TapParseUint16(r)
if err != nil {
return nil, err
}
rv[i] = x.(uint16)
}
return rv, err
}
// TapFlagParsers parser functions for TAP fields.
var TapFlagParsers = map[TapConnectFlag]TapItemParser{
BACKFILL: TapParseUint64,
LIST_VBUCKETS: TapParseVBList,
}
// SplitFlags will split the ORed flags into the individual bit flags.
func (f TapConnectFlag) SplitFlags() []TapConnectFlag {
rv := []TapConnectFlag{}
for i := uint32(1); f != 0; i = i << 1 {
if uint32(f)&i == i {
rv = append(rv, TapConnectFlag(i))
}
f = TapConnectFlag(uint32(f) & (^i))
}
return rv
}
func (f TapConnectFlag) String() string {
parts := []string{}
for _, x := range f.SplitFlags() {
p := TapConnectFlagNames[x]
if p == "" {
p = fmt.Sprintf("0x%x", int(x))
}
parts = append(parts, p)
}
return strings.Join(parts, "|")
}
type TapConnect struct {
Flags map[TapConnectFlag]interface{}
RemainingBody []byte
Name string
}
// ParseTapCommands parse the tap request into the interesting bits we may
// need to do something with.
func (req *MCRequest) ParseTapCommands() (TapConnect, error) {
rv := TapConnect{
Flags: map[TapConnectFlag]interface{}{},
Name: string(req.Key),
}
if len(req.Extras) < 4 {
return rv, fmt.Errorf("not enough extra bytes: %x", req.Extras)
}
flags := TapConnectFlag(binary.BigEndian.Uint32(req.Extras))
r := bytes.NewReader(req.Body)
for _, f := range flags.SplitFlags() {
fun := TapFlagParsers[f]
if fun == nil {
fun = TapParseBool
}
val, err := fun(r)
if err != nil {
return rv, err
}
rv.Flags[f] = val
}
var err error
rv.RemainingBody, err = ioutil.ReadAll(r)
return rv, err
}