add other session providers (#5963)

vendor/github.com/couchbase/gomemcached/tap.go

@@ -0,0 +1,168 @@
+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
+}