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gitea/vendor/github.com/couchbase/gomemcached/client/tap_feed.go

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2019-02-05 11:52:51 -05:00
package memcached
import (
"bytes"
"encoding/binary"
"fmt"
"io"
"math"
"github.com/couchbase/gomemcached"
"github.com/couchbase/goutils/logging"
)
// TAP protocol docs: <http://www.couchbase.com/wiki/display/couchbase/TAP+Protocol>
// TapOpcode is the tap operation type (found in TapEvent)
type TapOpcode uint8
// Tap opcode values.
const (
TapBeginBackfill = TapOpcode(iota)
TapEndBackfill
TapMutation
TapDeletion
TapCheckpointStart
TapCheckpointEnd
tapEndStream
)
const tapMutationExtraLen = 16
var tapOpcodeNames map[TapOpcode]string
func init() {
tapOpcodeNames = map[TapOpcode]string{
TapBeginBackfill: "BeginBackfill",
TapEndBackfill: "EndBackfill",
TapMutation: "Mutation",
TapDeletion: "Deletion",
TapCheckpointStart: "TapCheckpointStart",
TapCheckpointEnd: "TapCheckpointEnd",
tapEndStream: "EndStream",
}
}
func (opcode TapOpcode) String() string {
name := tapOpcodeNames[opcode]
if name == "" {
name = fmt.Sprintf("#%d", opcode)
}
return name
}
// TapEvent is a TAP notification of an operation on the server.
type TapEvent struct {
Opcode TapOpcode // Type of event
VBucket uint16 // VBucket this event applies to
Flags uint32 // Item flags
Expiry uint32 // Item expiration time
Key, Value []byte // Item key/value
Cas uint64
}
func makeTapEvent(req gomemcached.MCRequest) *TapEvent {
event := TapEvent{
VBucket: req.VBucket,
}
switch req.Opcode {
case gomemcached.TAP_MUTATION:
event.Opcode = TapMutation
event.Key = req.Key
event.Value = req.Body
event.Cas = req.Cas
case gomemcached.TAP_DELETE:
event.Opcode = TapDeletion
event.Key = req.Key
event.Cas = req.Cas
case gomemcached.TAP_CHECKPOINT_START:
event.Opcode = TapCheckpointStart
case gomemcached.TAP_CHECKPOINT_END:
event.Opcode = TapCheckpointEnd
case gomemcached.TAP_OPAQUE:
if len(req.Extras) < 8+4 {
return nil
}
switch op := int(binary.BigEndian.Uint32(req.Extras[8:])); op {
case gomemcached.TAP_OPAQUE_INITIAL_VBUCKET_STREAM:
event.Opcode = TapBeginBackfill
case gomemcached.TAP_OPAQUE_CLOSE_BACKFILL:
event.Opcode = TapEndBackfill
case gomemcached.TAP_OPAQUE_CLOSE_TAP_STREAM:
event.Opcode = tapEndStream
case gomemcached.TAP_OPAQUE_ENABLE_AUTO_NACK:
return nil
case gomemcached.TAP_OPAQUE_ENABLE_CHECKPOINT_SYNC:
return nil
default:
logging.Infof("TapFeed: Ignoring TAP_OPAQUE/%d", op)
return nil // unknown opaque event
}
case gomemcached.NOOP:
return nil // ignore
default:
logging.Infof("TapFeed: Ignoring %s", req.Opcode)
return nil // unknown event
}
if len(req.Extras) >= tapMutationExtraLen &&
(event.Opcode == TapMutation || event.Opcode == TapDeletion) {
event.Flags = binary.BigEndian.Uint32(req.Extras[8:])
event.Expiry = binary.BigEndian.Uint32(req.Extras[12:])
}
return &event
}
func (event TapEvent) String() string {
switch event.Opcode {
case TapBeginBackfill, TapEndBackfill, TapCheckpointStart, TapCheckpointEnd:
return fmt.Sprintf("<TapEvent %s, vbucket=%d>",
event.Opcode, event.VBucket)
default:
return fmt.Sprintf("<TapEvent %s, key=%q (%d bytes) flags=%x, exp=%d>",
event.Opcode, event.Key, len(event.Value),
event.Flags, event.Expiry)
}
}
// TapArguments are parameters for requesting a TAP feed.
//
// Call DefaultTapArguments to get a default one.
type TapArguments struct {
// Timestamp of oldest item to send.
//
// Use TapNoBackfill to suppress all past items.
Backfill uint64
// If set, server will disconnect after sending existing items.
Dump bool
// The indices of the vbuckets to watch; empty/nil to watch all.
VBuckets []uint16
// Transfers ownership of vbuckets during cluster rebalance.
Takeover bool
// If true, server will wait for client ACK after every notification.
SupportAck bool
// If true, client doesn't want values so server shouldn't send them.
KeysOnly bool
// If true, client wants the server to send checkpoint events.
Checkpoint bool
// Optional identifier to use for this client, to allow reconnects
ClientName string
// Registers this client (by name) till explicitly deregistered.
RegisteredClient bool
}
// Value for TapArguments.Backfill denoting that no past events at all
// should be sent.
const TapNoBackfill = math.MaxUint64
// DefaultTapArguments returns a default set of parameter values to
// pass to StartTapFeed.
func DefaultTapArguments() TapArguments {
return TapArguments{
Backfill: TapNoBackfill,
}
}
func (args *TapArguments) flags() []byte {
var flags gomemcached.TapConnectFlag
if args.Backfill != 0 {
flags |= gomemcached.BACKFILL
}
if args.Dump {
flags |= gomemcached.DUMP
}
if len(args.VBuckets) > 0 {
flags |= gomemcached.LIST_VBUCKETS
}
if args.Takeover {
flags |= gomemcached.TAKEOVER_VBUCKETS
}
if args.SupportAck {
flags |= gomemcached.SUPPORT_ACK
}
if args.KeysOnly {
flags |= gomemcached.REQUEST_KEYS_ONLY
}
if args.Checkpoint {
flags |= gomemcached.CHECKPOINT
}
if args.RegisteredClient {
flags |= gomemcached.REGISTERED_CLIENT
}
encoded := make([]byte, 4)
binary.BigEndian.PutUint32(encoded, uint32(flags))
return encoded
}
func must(err error) {
if err != nil {
panic(err)
}
}
func (args *TapArguments) bytes() (rv []byte) {
buf := bytes.NewBuffer([]byte{})
if args.Backfill > 0 {
must(binary.Write(buf, binary.BigEndian, uint64(args.Backfill)))
}
if len(args.VBuckets) > 0 {
must(binary.Write(buf, binary.BigEndian, uint16(len(args.VBuckets))))
for i := 0; i < len(args.VBuckets); i++ {
must(binary.Write(buf, binary.BigEndian, uint16(args.VBuckets[i])))
}
}
return buf.Bytes()
}
// TapFeed represents a stream of events from a server.
type TapFeed struct {
C <-chan TapEvent
Error error
closer chan bool
}
// StartTapFeed starts a TAP feed on a client connection.
//
// The events can be read from the returned channel. The connection
// can no longer be used for other purposes; it's now reserved for
// receiving the TAP messages. To stop receiving events, close the
// client connection.
func (mc *Client) StartTapFeed(args TapArguments) (*TapFeed, error) {
rq := &gomemcached.MCRequest{
Opcode: gomemcached.TAP_CONNECT,
Key: []byte(args.ClientName),
Extras: args.flags(),
Body: args.bytes()}
err := mc.Transmit(rq)
if err != nil {
return nil, err
}
ch := make(chan TapEvent)
feed := &TapFeed{
C: ch,
closer: make(chan bool),
}
go mc.runFeed(ch, feed)
return feed, nil
}
// TapRecvHook is called after every incoming tap packet is received.
var TapRecvHook func(*gomemcached.MCRequest, int, error)
// Internal goroutine that reads from the socket and writes events to
// the channel
func (mc *Client) runFeed(ch chan TapEvent, feed *TapFeed) {
defer close(ch)
var headerBuf [gomemcached.HDR_LEN]byte
loop:
for {
// Read the next request from the server.
//
// (Can't call mc.Receive() because it reads a
// _response_ not a request.)
var pkt gomemcached.MCRequest
n, err := pkt.Receive(mc.conn, headerBuf[:])
if TapRecvHook != nil {
TapRecvHook(&pkt, n, err)
}
if err != nil {
if err != io.EOF {
feed.Error = err
}
break loop
}
//logging.Infof("** TapFeed received %#v : %q", pkt, pkt.Body)
if pkt.Opcode == gomemcached.TAP_CONNECT {
// This is not an event from the server; it's
// an error response to my connect request.
feed.Error = fmt.Errorf("tap connection failed: %s", pkt.Body)
break loop
}
event := makeTapEvent(pkt)
if event != nil {
if event.Opcode == tapEndStream {
break loop
}
select {
case ch <- *event:
case <-feed.closer:
break loop
}
}
if len(pkt.Extras) >= 4 {
reqFlags := binary.BigEndian.Uint16(pkt.Extras[2:])
if reqFlags&gomemcached.TAP_ACK != 0 {
if _, err := mc.sendAck(&pkt); err != nil {
feed.Error = err
break loop
}
}
}
}
if err := mc.Close(); err != nil {
logging.Errorf("Error closing memcached client: %v", err)
}
}
func (mc *Client) sendAck(pkt *gomemcached.MCRequest) (int, error) {
res := gomemcached.MCResponse{
Opcode: pkt.Opcode,
Opaque: pkt.Opaque,
Status: gomemcached.SUCCESS,
}
return res.Transmit(mc.conn)
}
// Close terminates a TapFeed.
//
// Call this if you stop using a TapFeed before its channel ends.
func (feed *TapFeed) Close() {
close(feed.closer)
}