feat: use sync instead of psync while Redis version is less than 2.8.…

…0. (#874)

internal/reader/sync_standalone_reader.go

@@ -78,6 +78,9 @@ type syncStandaloneReader struct {
 		AofReceivedBytes  int64  `json:"aof_received_bytes"`  // bytes of AOF received from master
 		AofReceivedHuman  string `json:"aof_received_human"`
 	}
+
+	// version info
+	SupportPSYNC  bool
 }
 
 func NewSyncStandaloneReader(ctx context.Context, opts *SyncReaderOptions) Reader {
@@ -90,10 +93,36 @@ func NewSyncStandaloneReader(ctx context.Context, opts *SyncReaderOptions) Reade
 	r.stat.Status = kHandShake
 	r.stat.Dir = utils.GetAbsPath(r.stat.Name)
 	utils.CreateEmptyDir(r.stat.Dir)
+
+	r.SupportPSYNC = r.supportPSYNC();
 	return r
 }
 
+
+func (r *syncStandaloneReader) supportPSYNC() bool {
+	reply := r.client.DoWithStringReply("info", "server")
+	for _, line := range strings.Split(reply, "\n") {
+		if strings.HasPrefix(line, "redis_version:") {
+			version := strings.Split(line, ":")[1]
+			parts := strings.Split(version,".");
+			if len(parts) > 2{
+				v1,_ := strconv.Atoi(parts[0]);
+				v2,_ := strconv.Atoi(parts[1]);
+				if v1 * 1000  + v2 < 2008{
+					return false
+				}
+			}
+
+		}
+	}
+
+	return true;
+}
+
 func (r *syncStandaloneReader) StartRead(ctx context.Context) []chan *entry.Entry {
+	if !r.SupportPSYNC{
+		return r.StartReadWithSync(ctx);
+	}
 	r.ctx = ctx
 	r.ch = make(chan *entry.Entry, 1024)
 	go func() {
@@ -116,6 +145,29 @@ func (r *syncStandaloneReader) StartRead(ctx context.Context) []chan *entry.Entr
 	return []chan *entry.Entry{r.ch}
 }
 
+func (r *syncStandaloneReader) StartReadWithSync(ctx context.Context) []chan *entry.Entry {
+	r.ctx = ctx
+	r.ch = make(chan *entry.Entry, 1024)
+	go func() {
+		//r.sendReplconfListenPort()
+		r.sendSync()
+		rdbFilePath := r.receiveRDB()
+		startOffset := r.stat.AofReceivedOffset
+		//go r.sendReplconfAck() // start sent replconf ack
+		go r.receiveAOF(r.rd)
+		if r.opts.SyncRdb {
+			r.sendRDB(rdbFilePath)
+		}
+		if r.opts.SyncAof {
+			r.stat.Status = kSyncAof
+			r.sendAOF(startOffset)
+		}
+		close(r.ch)
+	}()
+
+	return []chan *entry.Entry{r.ch}
+}
+
 func (r *syncStandaloneReader) sendReplconfListenPort() {
 	// use status_port as redis-shake port
 	argv := []interface{}{"replconf", "listening-port", strconv.Itoa(config.Opt.Advanced.StatusPort)}
@@ -166,6 +218,40 @@ func (r *syncStandaloneReader) sendPSync() {
 	r.stat.AofReceivedOffset = int64(masterOffset)
 }
 
+func (r *syncStandaloneReader) sendSync() {
+	if r.opts.TryDiskless {
+		argv := []interface{}{"REPLCONF", "CAPA", "EOF"}
+		reply := r.client.DoWithStringReply(argv...)
+		if reply != "OK" {
+			log.Warnf("[%s] send replconf capa eof to redis server failed. reply=[%v]", r.stat.Name, reply)
+		}
+	}
+	// send SYNC
+	argv := []interface{}{"SYNC"}
+	if config.Opt.Advanced.AwsPSync != "" {
+		argv = []interface{}{config.Opt.Advanced.GetPSyncCommand(r.stat.Address), "?", "-1"}
+	}
+	r.client.Send(argv...)
+
+	// format: \n\n\n+<reply>\r\n
+	for {
+		select {
+		case <-r.ctx.Done():
+			close(r.ch)
+			runtime.Goexit() // stop goroutine
+		default:
+		}
+		bytes, err := r.rd.Peek(1)
+		if err != nil {
+			log.Panicf(err.Error())
+		}
+		if bytes[0] != '\n' {
+			break
+		}
+		r.rd.ReadByte()
+	}
+}
+
 func (r *syncStandaloneReader) receiveRDB() string {
 	log.Debugf("[%s] source db is doing bgsave.", r.stat.Name)
 	r.stat.Status = kWaitBgsave