Use last end position in pursuit mode (#26144)

Signed-off-by: NCongqi Xia <congqi.xia@zilliz.com>

pkg/mq/msgstream/mq_msgstream.go

@@ -28,6 +28,7 @@ import (
 	"github.com/golang/protobuf/proto"
 	"github.com/milvus-io/milvus-proto/go-api/v2/commonpb"
 	"github.com/milvus-io/milvus-proto/go-api/v2/msgpb"
+	"github.com/samber/lo"
 	"go.uber.org/zap"
 
 	"github.com/milvus-io/milvus/pkg/log"
@@ -594,8 +595,10 @@ func (ms *MqTtMsgStream) bufMsgPackToChannel() {
 			return
 		default:
 			timeTickBuf := make([]TsMsg, 0)
-			startMsgPosition := make([]*msgpb.MsgPosition, 0)
-			endMsgPositions := make([]*msgpb.MsgPosition, 0)
+			// startMsgPosition := make([]*msgpb.MsgPosition, 0)
+			// endMsgPositions := make([]*msgpb.MsgPosition, 0)
+			startPositions := make(map[string]*msgpb.MsgPosition)
+			endPositions := make(map[string]*msgpb.MsgPosition)
 			var endTs uint64
 			var size uint64
 
@@ -623,6 +626,11 @@ func (ms *MqTtMsgStream) bufMsgPackToChannel() {
 					if len(msgs) == 0 {
 						continue
 					}
+					startPos := typeutil.Clone(ms.chanMsgPos[consumer])
+					channelName := startPos.ChannelName
+					if _, ok := startPositions[channelName]; !ok {
+						startPositions[channelName] = startPos
+					}
 					tempBuffer := make([]TsMsg, 0)
 					var timeTickMsg TsMsg
 					for _, v := range msgs {
@@ -639,7 +647,7 @@ func (ms *MqTtMsgStream) bufMsgPackToChannel() {
 					}
 					ms.chanMsgBuf[consumer] = tempBuffer
 
-					startMsgPosition = append(startMsgPosition, proto.Clone(ms.chanMsgPos[consumer]).(*msgpb.MsgPosition))
+					//	startMsgPosition = append(startMsgPosition, proto.Clone(ms.chanMsgPos[consumer]).(*msgpb.MsgPosition))
 					var newPos *msgpb.MsgPosition
 					if len(tempBuffer) > 0 {
 						// if tempBuffer is not empty, use tempBuffer[0] to seek
@@ -649,7 +657,7 @@ func (ms *MqTtMsgStream) bufMsgPackToChannel() {
 							Timestamp:   currTs,
 							MsgGroup:    consumer.Subscription(),
 						}
-						endMsgPositions = append(endMsgPositions, newPos)
+						endPositions[channelName] = newPos
 					} else if timeTickMsg != nil {
 						// if tempBuffer is empty, use timeTickMsg to seek
 						newPos = &msgpb.MsgPosition{
@@ -658,7 +666,7 @@ func (ms *MqTtMsgStream) bufMsgPackToChannel() {
 							Timestamp:   currTs,
 							MsgGroup:    consumer.Subscription(),
 						}
-						endMsgPositions = append(endMsgPositions, newPos)
+						endPositions[channelName] = newPos
 					}
 					ms.chanMsgPos[consumer] = newPos
 				}
@@ -683,8 +691,8 @@ func (ms *MqTtMsgStream) bufMsgPackToChannel() {
 					BeginTs:        ms.lastTimeStamp,
 					EndTs:          endTs,
 					Msgs:           uniqueMsgs,
-					StartPositions: startMsgPosition,
-					EndPositions:   endMsgPositions,
+					StartPositions: lo.MapToSlice(startPositions, func(_ string, pos *msgpb.MsgPosition) *msgpb.MsgPosition { return pos }),
+					EndPositions:   lo.MapToSlice(endPositions, func(_ string, pos *msgpb.MsgPosition) *msgpb.MsgPosition { return pos }),
 				}
 
 				select {