Refactor data coordinator (#5982)

Rename variable name and make error msg more clear
Signed-off-by: Nsunby <bingyi.sun@zilliz.com>

internal/datacoord/allocator.go

@@ -25,18 +25,19 @@ type allocator interface {
 }
 
 type rootCoordAllocator struct {
+	ctx             context.Context
 	rootCoordClient types.RootCoord
 }
 
-func newAllocator(rootCoordClient types.RootCoord) *rootCoordAllocator {
+func newRootCoordAllocator(ctx context.Context, rootCoordClient types.RootCoord) *rootCoordAllocator {
 	return &rootCoordAllocator{
+		ctx:             ctx,
 		rootCoordClient: rootCoordClient,
 	}
 }
 
-func (allocator *rootCoordAllocator) allocTimestamp() (Timestamp, error) {
-	ctx := context.TODO()
-	resp, err := allocator.rootCoordClient.AllocTimestamp(ctx, &rootcoordpb.AllocTimestampRequest{
+func (alloc *rootCoordAllocator) allocTimestamp() (Timestamp, error) {
+	resp, err := alloc.rootCoordClient.AllocTimestamp(alloc.ctx, &rootcoordpb.AllocTimestampRequest{
 		Base: &commonpb.MsgBase{
 			MsgType:   commonpb.MsgType_RequestTSO,
 			MsgID:     -1, // todo add msg id
@@ -51,9 +52,8 @@ func (allocator *rootCoordAllocator) allocTimestamp() (Timestamp, error) {
 	return resp.Timestamp, nil
 }
 
-func (allocator *rootCoordAllocator) allocID() (UniqueID, error) {
-	ctx := context.TODO()
-	resp, err := allocator.rootCoordClient.AllocID(ctx, &rootcoordpb.AllocIDRequest{
+func (alloc *rootCoordAllocator) allocID() (UniqueID, error) {
+	resp, err := alloc.rootCoordClient.AllocID(alloc.ctx, &rootcoordpb.AllocIDRequest{
 		Base: &commonpb.MsgBase{
 			MsgType:   commonpb.MsgType_RequestID,
 			MsgID:     -1, // todo add msg id

internal/datacoord/allocator_test.go

@@ -15,11 +15,12 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"golang.org/x/net/context"
 )
 
 func TestAllocator_Basic(t *testing.T) {
 	ms := newMockRootCoordService()
-	allocator := newAllocator(ms)
+	allocator := newRootCoordAllocator(context.Background(), ms)
 
 	t.Run("Test allocTimestamp", func(t *testing.T) {
 		_, err := allocator.allocTimestamp()

internal/datacoord/cluster_session_manager.go

@@ -11,6 +11,7 @@
 package datacoord
 
 import (
+	"context"
 	"sync"
 
 	"github.com/milvus-io/milvus/internal/types"
@@ -26,12 +27,14 @@ type sessionManager interface {
 
 type clusterSessionManager struct {
 	sync.RWMutex
+	ctx               context.Context
 	sessions          map[string]types.DataNode
-	dataClientCreator func(addr string) (types.DataNode, error)
+	dataClientCreator dataNodeCreatorFunc
 }
 
-func newClusterSessionManager(dataClientCreator func(addr string) (types.DataNode, error)) *clusterSessionManager {
+func newClusterSessionManager(ctx context.Context, dataClientCreator dataNodeCreatorFunc) *clusterSessionManager {
 	return &clusterSessionManager{
+		ctx:               ctx,
 		sessions:          make(map[string]types.DataNode),
 		dataClientCreator: dataClientCreator,
 	}
@@ -39,7 +42,7 @@ func newClusterSessionManager(dataClientCreator func(addr string) (types.DataNod
 
 // lock acquired
 func (m *clusterSessionManager) createSession(addr string) (types.DataNode, error) {
-	cli, err := m.dataClientCreator(addr)
+	cli, err := m.dataClientCreator(m.ctx, addr)
 	if err != nil {
 		return nil, err
 	}

internal/datacoord/flush_monitor_test.go

@@ -42,15 +42,15 @@ func TestFlushMonitor(t *testing.T) {
 	// create seg0 for partition0, seg0/seg1 for partition1
 	segID0_0, err := mockAllocator.allocID()
 	assert.Nil(t, err)
-	segInfo0_0, err := BuildSegment(collID, partID0, segID0_0, channelName)
+	segInfo0_0, err := buildSegment(collID, partID0, segID0_0, channelName)
 	assert.Nil(t, err)
 	segID1_0, err := mockAllocator.allocID()
 	assert.Nil(t, err)
-	segInfo1_0, err := BuildSegment(collID, partID1, segID1_0, channelName)
+	segInfo1_0, err := buildSegment(collID, partID1, segID1_0, channelName)
 	assert.Nil(t, err)
 	segID1_1, err := mockAllocator.allocID()
 	assert.Nil(t, err)
-	segInfo1_1, err := BuildSegment(collID, partID1, segID1_1, channelName)
+	segInfo1_1, err := buildSegment(collID, partID1, segID1_1, channelName)
 	assert.Nil(t, err)
 
 	// check AddSegment
@@ -77,7 +77,7 @@ func TestFlushMonitor(t *testing.T) {
 		fm.segmentPolicy = estSegmentSizePolicy(1024*1024, 1024*1024*2) // row size 1Mib Limit 2 MB
 		segID3Rows, err := mockAllocator.allocID()
 		assert.Nil(t, err)
-		segInfo3Rows, err := BuildSegment(collID, partID1, segID3Rows, channelName)
+		segInfo3Rows, err := buildSegment(collID, partID1, segID3Rows, channelName)
 		segInfo3Rows.NumOfRows = 3
 		assert.Nil(t, err)
 
@@ -95,7 +95,7 @@ func TestFlushMonitor(t *testing.T) {
 		for i := 0; i < 100; i++ {
 			segID, err := mockAllocator.allocID()
 			assert.Nil(t, err)
-			seg, err := BuildSegment(collID, partID0, segID, channelName2)
+			seg, err := buildSegment(collID, partID0, segID, channelName2)
 			assert.Nil(t, err)
 			seg.DmlPosition = &internalpb.MsgPosition{
 				Timestamp: uint64(i + 1),
@@ -108,7 +108,7 @@ func TestFlushMonitor(t *testing.T) {
 
 		exSegID, err := mockAllocator.allocID()
 		assert.Nil(t, err)
-		seg, err := BuildSegment(collID, partID0, exSegID, channelName2)
+		seg, err := buildSegment(collID, partID0, exSegID, channelName2)
 		assert.Nil(t, err)
 		seg.DmlPosition = &internalpb.MsgPosition{
 			Timestamp: uint64(0), // the oldest

internal/datacoord/grpc_services.go

@@ -16,6 +16,8 @@ import (
 	"go.uber.org/zap"
 )
 
+const serverNotServingErrMsg = "server is not serving"
+
 func (s *Server) isClosed() bool {
 	return atomic.LoadInt64(&s.isServing) != 2
 }
@@ -44,11 +46,11 @@ func (s *Server) Flush(ctx context.Context, req *datapb.FlushRequest) (*commonpb
 		ErrorCode: commonpb.ErrorCode_UnexpectedError,
 	}
 	if s.isClosed() {
-		resp.Reason = "server is closed"
+		resp.Reason = serverNotServingErrMsg
 		return resp, nil
 	}
 	if err := s.segmentManager.SealAllSegments(ctx, req.CollectionID); err != nil {
-		resp.Reason = fmt.Sprintf("Seal all segments error %s", err)
+		resp.Reason = fmt.Sprintf("Failed to flush %d, %s", req.CollectionID, err)
 		return resp, nil
 	}
 	return &commonpb.Status{
@@ -60,6 +62,7 @@ func (s *Server) AssignSegmentID(ctx context.Context, req *datapb.AssignSegmentI
 	if s.isClosed() {
 		return &datapb.AssignSegmentIDResponse{
 			Status: &commonpb.Status{
+				Reason:    serverNotServingErrMsg,
 				ErrorCode: commonpb.ErrorCode_UnexpectedError,
 			},
 		}, nil
@@ -85,7 +88,7 @@ func (s *Server) AssignSegmentID(ctx context.Context, req *datapb.AssignSegmentI
 
 		if !s.meta.HasCollection(r.CollectionID) {
 			if err := s.loadCollectionFromRootCoord(ctx, r.CollectionID); err != nil {
-				errMsg := fmt.Sprintf("can not load collection %d", r.CollectionID)
+				errMsg := fmt.Sprintf("Can not load collection %d", r.CollectionID)
 				appendFailedAssignment(errMsg)
 				log.Error("load collection from rootcoord error",
 					zap.Int64("collectionID", r.CollectionID),
@@ -104,7 +107,7 @@ func (s *Server) AssignSegmentID(ctx context.Context, req *datapb.AssignSegmentI
 		segmentID, retCount, expireTs, err := s.segmentManager.AllocSegment(ctx,
 			r.CollectionID, r.PartitionID, r.ChannelName, int64(r.Count))
 		if err != nil {
-			errMsg := fmt.Sprintf("allocation of collection %d, partition %d, channel %s, count %d error:  %s",
+			errMsg := fmt.Sprintf("Allocation of collection %d, partition %d, channel %s, count %d error:  %s",
 				r.CollectionID, r.PartitionID, r.ChannelName, r.Count, err.Error())
 			appendFailedAssignment(errMsg)
 			continue
@@ -142,7 +145,7 @@ func (s *Server) GetSegmentStates(ctx context.Context, req *datapb.GetSegmentSta
 		},
 	}
 	if s.isClosed() {
-		resp.Status.Reason = "server is initializing"
+		resp.Status.Reason = serverNotServingErrMsg
 		return resp, nil
 	}
 
@@ -154,7 +157,7 @@ func (s *Server) GetSegmentStates(ctx context.Context, req *datapb.GetSegmentSta
 		segmentInfo, err := s.meta.GetSegment(segmentID)
 		if err != nil {
 			state.Status.ErrorCode = commonpb.ErrorCode_UnexpectedError
-			state.Status.Reason = "get segment states error: " + err.Error()
+			state.Status.Reason = fmt.Sprintf("Failed to get segment %d, %s", segmentID, err.Error())
 		} else {
 			state.Status.ErrorCode = commonpb.ErrorCode_Success
 			state.State = segmentInfo.GetState()
@@ -174,7 +177,7 @@ func (s *Server) GetInsertBinlogPaths(ctx context.Context, req *datapb.GetInsert
 		},
 	}
 	if s.isClosed() {
-		resp.Status.Reason = "server is initializing"
+		resp.Status.Reason = serverNotServingErrMsg
 		return resp, nil
 	}
 	p := path.Join(Params.SegmentBinlogSubPath, strconv.FormatInt(req.SegmentID, 10)) + "/" // prefix/id/ instead of prefix/id
@@ -212,7 +215,7 @@ func (s *Server) GetCollectionStatistics(ctx context.Context, req *datapb.GetCol
 		},
 	}
 	if s.isClosed() {
-		resp.Status.Reason = "server is initializing"
+		resp.Status.Reason = serverNotServingErrMsg
 		return resp, nil
 	}
 	nums, err := s.meta.GetNumRowsOfCollection(req.CollectionID)
@@ -232,7 +235,7 @@ func (s *Server) GetPartitionStatistics(ctx context.Context, req *datapb.GetPart
 		},
 	}
 	if s.isClosed() {
-		resp.Status.Reason = "server is initializing"
+		resp.Status.Reason = serverNotServingErrMsg
 		return resp, nil
 	}
 	nums, err := s.meta.GetNumRowsOfPartition(req.CollectionID, req.PartitionID)
@@ -261,7 +264,7 @@ func (s *Server) GetSegmentInfo(ctx context.Context, req *datapb.GetSegmentInfoR
 		},
 	}
 	if s.isClosed() {
-		resp.Status.Reason = "data service is not healthy"
+		resp.Status.Reason = serverNotServingErrMsg
 		return resp, nil
 	}
 	infos := make([]*datapb.SegmentInfo, 0, len(req.SegmentIDs))
@@ -283,7 +286,7 @@ func (s *Server) SaveBinlogPaths(ctx context.Context, req *datapb.SaveBinlogPath
 		ErrorCode: commonpb.ErrorCode_UnexpectedError,
 	}
 	if s.isClosed() {
-		resp.Reason = "server is closed"
+		resp.Reason = serverNotServingErrMsg
 		return resp, nil
 	}
 	log.Debug("Receive SaveBinlogPaths request",
@@ -364,7 +367,7 @@ func (s *Server) GetRecoveryInfo(ctx context.Context, req *datapb.GetRecoveryInf
 		},
 	}
 	if s.isClosed() {
-		resp.Status.Reason = "server is initializing"
+		resp.Status.Reason = serverNotServingErrMsg
 		return resp, nil
 	}
 	segmentIDs := s.meta.GetSegmentsOfPartition(collectionID, partitionID)

internal/datacoord/meta.go

@@ -32,15 +32,6 @@ const (
 type errSegmentNotFound struct {
 	segmentID UniqueID
 }
-type errCollectionNotFound struct {
-	collectionID UniqueID
-}
-type meta struct {
-	sync.RWMutex
-	client      kv.TxnKV                            // client of a reliable kv service, i.e. etcd client
-	collections map[UniqueID]*datapb.CollectionInfo // collection id to collection info
-	segments    map[UniqueID]*datapb.SegmentInfo    // segment id to segment info
-}
 
 func newErrSegmentNotFound(segmentID UniqueID) errSegmentNotFound {
 	return errSegmentNotFound{segmentID: segmentID}
@@ -50,6 +41,10 @@ func (err errSegmentNotFound) Error() string {
 	return fmt.Sprintf("segment %d not found", err.segmentID)
 }
 
+type errCollectionNotFound struct {
+	collectionID UniqueID
+}
+
 func newErrCollectionNotFound(collectionID UniqueID) errCollectionNotFound {
 	return errCollectionNotFound{collectionID: collectionID}
 }
@@ -58,6 +53,62 @@ func (err errCollectionNotFound) Error() string {
 	return fmt.Sprintf("collection %d not found", err.collectionID)
 }
 
+type errPartitionNotFound struct {
+	partitionID UniqueID
+}
+
+func newErrPartitionNotFound(partitionID UniqueID) errPartitionNotFound {
+	return errPartitionNotFound{partitionID: partitionID}
+}
+
+func (err errPartitionNotFound) Error() string {
+	return fmt.Sprintf("partition %d not found", err.partitionID)
+}
+
+type errCollectionExist struct {
+	name string
+	id   UniqueID
+}
+
+func newErrCollectionExist(collectionName string, collectionID UniqueID) errCollectionExist {
+	return errCollectionExist{name: collectionName, id: collectionID}
+}
+
+func (err errCollectionExist) Error() string {
+	return fmt.Sprintf("collection %s with id %d already exist", err.name, err.id)
+}
+
+type errPartitionExist struct {
+	id UniqueID
+}
+
+func newErrPartitionExist(partitionID UniqueID) errPartitionExist {
+	return errPartitionExist{id: partitionID}
+}
+
+func (err errPartitionExist) Error() string {
+	return fmt.Sprintf("partition %d already exist", err.id)
+}
+
+type errSegmentExist struct {
+	id UniqueID
+}
+
+func newErrSegmentExist(segmentID UniqueID) errSegmentExist {
+	return errSegmentExist{id: segmentID}
+}
+
+func (err errSegmentExist) Error() string {
+	return fmt.Sprintf("segment %d already exist", err.id)
+}
+
+type meta struct {
+	sync.RWMutex
+	client      kv.TxnKV                            // client of a reliable kv service, i.e. etcd client
+	collections map[UniqueID]*datapb.CollectionInfo // collection id to collection info
+	segments    map[UniqueID]*datapb.SegmentInfo    // segment id to segment info
+}
+
 func newMeta(kv kv.TxnKV) (*meta, error) {
 	mt := &meta{
 		client:      kv,
@@ -93,27 +144,27 @@ func (m *meta) AddCollection(collection *datapb.CollectionInfo) error {
 	m.Lock()
 	defer m.Unlock()
 	if _, ok := m.collections[collection.ID]; ok {
-		return fmt.Errorf("collection %s with id %d already exist", collection.Schema.Name, collection.ID)
+		return newErrCollectionExist(collection.GetSchema().GetName(), collection.GetID())
 	}
 	m.collections[collection.ID] = collection
 	return nil
 }
 
-func (m *meta) DropCollection(collID UniqueID) error {
+func (m *meta) DropCollection(collectionID UniqueID) error {
 	m.Lock()
 	defer m.Unlock()
 
-	if _, ok := m.collections[collID]; !ok {
-		return newErrCollectionNotFound(collID)
+	if _, ok := m.collections[collectionID]; !ok {
+		return newErrCollectionNotFound(collectionID)
 	}
-	key := fmt.Sprintf("%s/%d/", segmentPrefix, collID)
+	key := buildCollectionPath(collectionID)
 	if err := m.client.RemoveWithPrefix(key); err != nil {
 		return err
 	}
-	delete(m.collections, collID)
+	delete(m.collections, collectionID)
 
 	for i, info := range m.segments {
-		if info.CollectionID == collID {
+		if info.CollectionID == collectionID {
 			delete(m.segments, i)
 		}
 	}
@@ -141,9 +192,9 @@ func (m *meta) GetNumRowsOfCollection(collectionID UniqueID) (int64, error) {
 	m.RLock()
 	defer m.RUnlock()
 	var ret int64 = 0
-	for _, info := range m.segments {
-		if info.CollectionID == collectionID {
-			ret += info.NumOfRows
+	for _, segment := range m.segments {
+		if segment.CollectionID == collectionID {
+			ret += segment.GetNumOfRows()
 		}
 	}
 	return ret, nil
@@ -153,7 +204,7 @@ func (m *meta) AddSegment(segment *datapb.SegmentInfo) error {
 	m.Lock()
 	defer m.Unlock()
 	if _, ok := m.segments[segment.ID]; ok {
-		return fmt.Errorf("segment %d already exist", segment.ID)
+		return newErrSegmentExist(segment.GetID())
 	}
 	m.segments[segment.ID] = segment
 	if err := m.saveSegmentInfo(segment); err != nil {
@@ -179,13 +230,13 @@ func (m *meta) UpdateSegmentStatistic(stats *internalpb.SegmentStatisticsUpdates
 func (m *meta) SetLastExpireTime(segmentID UniqueID, expireTs Timestamp) error {
 	m.Lock()
 	defer m.Unlock()
-	seg, ok := m.segments[segmentID]
+	segment, ok := m.segments[segmentID]
 	if !ok {
 		return newErrSegmentNotFound(segmentID)
 	}
-	seg.LastExpireTime = expireTs
+	segment.LastExpireTime = expireTs
 
-	if err := m.saveSegmentInfo(seg); err != nil {
+	if err := m.saveSegmentInfo(segment); err != nil {
 		return err
 	}
 	return nil
@@ -238,7 +289,7 @@ func (m *meta) SaveBinlogAndCheckPoints(segID UniqueID, flushed bool,
 	startPositions []*datapb.SegmentStartPosition) error {
 	m.Lock()
 	defer m.Unlock()
-	segInfo, ok := m.segments[segID]
+	segment, ok := m.segments[segID]
 	if !ok {
 		return newErrSegmentNotFound(segID)
 	}
@@ -247,7 +298,7 @@ func (m *meta) SaveBinlogAndCheckPoints(segID UniqueID, flushed bool,
 		kv[k] = v
 	}
 	if flushed {
-		segInfo.State = commonpb.SegmentState_Flushing
+		segment.State = commonpb.SegmentState_Flushing
 	}
 
 	modifiedSegments := make(map[UniqueID]struct{})
@@ -281,9 +332,9 @@ func (m *meta) SaveBinlogAndCheckPoints(segID UniqueID, flushed bool,
 	}
 
 	for id := range modifiedSegments {
-		segInfo = m.segments[id]
-		segBytes := proto.MarshalTextString(segInfo)
-		key := m.prepareSegmentPath(segInfo)
+		segment = m.segments[id]
+		segBytes := proto.MarshalTextString(segment)
+		key := buildSegmentPath(segment.GetCollectionID(), segment.GetPartitionID(), segment.GetID())
 		kv[key] = segBytes
 	}
 
@@ -355,20 +406,20 @@ func (m *meta) AddPartition(collectionID UniqueID, partitionID UniqueID) error {
 
 	for _, t := range coll.Partitions {
 		if t == partitionID {
-			return fmt.Errorf("partition %d already exists", partitionID)
+			return newErrPartitionExist(partitionID)
 		}
 	}
 	coll.Partitions = append(coll.Partitions, partitionID)
 	return nil
 }
 
-func (m *meta) DropPartition(collID UniqueID, partitionID UniqueID) error {
+func (m *meta) DropPartition(collectionID UniqueID, partitionID UniqueID) error {
 	m.Lock()
 	defer m.Unlock()
 
-	collection, ok := m.collections[collID]
+	collection, ok := m.collections[collectionID]
 	if !ok {
-		return newErrCollectionNotFound(collID)
+		return newErrCollectionNotFound(collectionID)
 	}
 	idx := -1
 	for i, id := range collection.Partitions {
@@ -378,10 +429,10 @@ func (m *meta) DropPartition(collID UniqueID, partitionID UniqueID) error {
 		}
 	}
 	if idx == -1 {
-		return fmt.Errorf("cannot find partition id %d", partitionID)
+		return newErrPartitionNotFound(partitionID)
 	}
 
-	prefix := fmt.Sprintf("%s/%d/%d/", segmentPrefix, collID, partitionID)
+	prefix := buildPartitionPath(collectionID, partitionID)
 	if err := m.client.RemoveWithPrefix(prefix); err != nil {
 		return err
 	}
@@ -451,24 +502,32 @@ func (m *meta) GetFlushingSegments() []*datapb.SegmentInfo {
 func (m *meta) saveSegmentInfo(segment *datapb.SegmentInfo) error {
 	segBytes := proto.MarshalTextString(segment)
 
-	key := m.prepareSegmentPath(segment)
+	key := buildSegmentPath(segment.GetCollectionID(), segment.GetPartitionID(), segment.GetID())
 	return m.client.Save(key, segBytes)
 }
 
 func (m *meta) removeSegmentInfo(segment *datapb.SegmentInfo) error {
-	key := m.prepareSegmentPath(segment)
+	key := buildSegmentPath(segment.GetCollectionID(), segment.GetPartitionID(), segment.GetID())
 	return m.client.Remove(key)
 }
 
-func (m *meta) prepareSegmentPath(segInfo *datapb.SegmentInfo) string {
-	return fmt.Sprintf("%s/%d/%d/%d", segmentPrefix, segInfo.CollectionID, segInfo.PartitionID, segInfo.ID)
-}
-
 func (m *meta) saveKvTxn(kv map[string]string) error {
 	return m.client.MultiSave(kv)
 }
 
-func BuildSegment(collectionID UniqueID, partitionID UniqueID, segmentID UniqueID, channelName string) (*datapb.SegmentInfo, error) {
+func buildSegmentPath(collectionID UniqueID, partitionID UniqueID, segmentID UniqueID) string {
+	return fmt.Sprintf("%s/%d/%d/%d", segmentPrefix, collectionID, partitionID, segmentID)
+}
+
+func buildCollectionPath(collectionID UniqueID) string {
+	return fmt.Sprintf("%s/%d/", segmentPrefix, collectionID)
+}
+
+func buildPartitionPath(collectionID UniqueID, partitionID UniqueID) string {
+	return fmt.Sprintf("%s/%d/%d/", segmentPrefix, collectionID, partitionID)
+}
+
+func buildSegment(collectionID UniqueID, partitionID UniqueID, segmentID UniqueID, channelName string) (*datapb.SegmentInfo, error) {
 	return &datapb.SegmentInfo{
 		ID:            segmentID,
 		CollectionID:  collectionID,

internal/datacoord/meta_test.go

@@ -122,15 +122,15 @@ func TestMeta_Basic(t *testing.T) {
 		// create seg0 for partition0, seg0/seg1 for partition1
 		segID0_0, err := mockAllocator.allocID()
 		assert.Nil(t, err)
-		segInfo0_0, err := BuildSegment(collID, partID0, segID0_0, channelName)
+		segInfo0_0, err := buildSegment(collID, partID0, segID0_0, channelName)
 		assert.Nil(t, err)
 		segID1_0, err := mockAllocator.allocID()
 		assert.Nil(t, err)
-		segInfo1_0, err := BuildSegment(collID, partID1, segID1_0, channelName)
+		segInfo1_0, err := buildSegment(collID, partID1, segID1_0, channelName)
 		assert.Nil(t, err)
 		segID1_1, err := mockAllocator.allocID()
 		assert.Nil(t, err)
-		segInfo1_1, err := BuildSegment(collID, partID1, segID1_1, channelName)
+		segInfo1_1, err := buildSegment(collID, partID1, segID1_1, channelName)
 		assert.Nil(t, err)
 
 		// check AddSegment
@@ -202,7 +202,7 @@ func TestMeta_Basic(t *testing.T) {
 		// add seg1 with 100 rows
 		segID0, err := mockAllocator.allocID()
 		assert.Nil(t, err)
-		segInfo0, err := BuildSegment(collID, partID0, segID0, channelName)
+		segInfo0, err := buildSegment(collID, partID0, segID0, channelName)
 		assert.Nil(t, err)
 		segInfo0.NumOfRows = rowCount0
 		err = meta.AddSegment(segInfo0)
@@ -211,7 +211,7 @@ func TestMeta_Basic(t *testing.T) {
 		// add seg2 with 300 rows
 		segID1, err := mockAllocator.allocID()
 		assert.Nil(t, err)
-		segInfo1, err := BuildSegment(collID, partID0, segID1, channelName)
+		segInfo1, err := buildSegment(collID, partID0, segID1, channelName)
 		assert.Nil(t, err)
 		segInfo1.NumOfRows = rowCount1
 		err = meta.AddSegment(segInfo1)

internal/datacoord/segment_allocation_policy.go

@@ -70,7 +70,7 @@ func getSegmentCapacityPolicy(sizeFactor float64) segmentSealPolicy {
 	return func(status *segmentStatus, ts Timestamp) bool {
 		var allocSize int64
 		for _, allocation := range status.allocations {
-			allocSize += allocation.rowNums
+			allocSize += allocation.numOfRows
 		}
 		// max, written, allocated := status.total, status.currentRows, allocSize
 		// float64(writtenCount) >= Params.SegmentSizeFactor*float64(maxCount)

internal/datacoord/segment_manager.go

@@ -68,7 +68,7 @@ type segmentStatus struct {
 }
 
 type allocation struct {
-	rowNums    int64
+	numOfRows  int64
 	expireTime Timestamp
 }
 
@@ -250,16 +250,15 @@ func (s *SegmentManager) AllocSegment(ctx context.Context, collectionID UniqueID
 	segID = status.id
 	retCount = requestRows
 	expireTime = status.lastExpireTime
-
 	return
 }
 
-func (s *SegmentManager) alloc(segStatus *segmentStatus, numRows int64) (bool, error) {
+func (s *SegmentManager) alloc(status *segmentStatus, numOfRows int64) (bool, error) {
 	var allocSize int64
-	for _, allocation := range segStatus.allocations {
-		allocSize += allocation.rowNums
+	for _, allocItem := range status.allocations {
+		allocSize += allocItem.numOfRows
 	}
-	if !s.allocPolicy.apply(segStatus.total, segStatus.currentRows, allocSize, numRows) {
+	if !s.allocPolicy.apply(status.total, status.currentRows, allocSize, numOfRows) {
 		return false, nil
 	}
 
@@ -269,13 +268,13 @@ func (s *SegmentManager) alloc(segStatus *segmentStatus, numRows int64) (bool, e
 	}
 
 	alloc := &allocation{
-		rowNums:    numRows,
+		numOfRows:  numOfRows,
 		expireTime: expireTs,
 	}
-	segStatus.lastExpireTime = expireTs
-	segStatus.allocations = append(segStatus.allocations, alloc)
+	status.lastExpireTime = expireTs
+	status.allocations = append(status.allocations, alloc)
 
-	if err := s.meta.SetLastExpireTime(segStatus.id, expireTs); err != nil {
+	if err := s.meta.SetLastExpireTime(status.id, expireTs); err != nil {
 		return false, err
 	}
 	return true, nil
@@ -299,22 +298,22 @@ func (s *SegmentManager) openNewSegment(ctx context.Context, collectionID Unique
 	if err != nil {
 		return nil, err
 	}
-	totalRows, err := s.estimateTotalRows(collectionID)
+	maxNumOfRows, err := s.estimateMaxNumOfRows(collectionID)
 	if err != nil {
 		return nil, err
 	}
-	segStatus := &segmentStatus{
+	status := &segmentStatus{
 		id:             id,
 		collectionID:   collectionID,
 		partitionID:    partitionID,
 		sealed:         false,
-		total:          int64(totalRows),
+		total:          int64(maxNumOfRows),
 		insertChannel:  channelName,
 		allocations:    []*allocation{},
 		lastExpireTime: 0,
 		currentRows:    0,
 	}
-	s.stats[id] = segStatus
+	s.stats[id] = status
 
 	segmentInfo := &datapb.SegmentInfo{
 		ID:             id,
@@ -323,7 +322,7 @@ func (s *SegmentManager) openNewSegment(ctx context.Context, collectionID Unique
 		InsertChannel:  channelName,
 		NumOfRows:      0,
 		State:          commonpb.SegmentState_Growing,
-		MaxRowNum:      int64(totalRows),
+		MaxRowNum:      int64(maxNumOfRows),
 		LastExpireTime: 0,
 		StartPosition: &internalpb.MsgPosition{
 			ChannelName: channelName,
@@ -339,15 +338,14 @@ func (s *SegmentManager) openNewSegment(ctx context.Context, collectionID Unique
 	log.Debug("datacoord: estimateTotalRows: ",
 		zap.Int64("CollectionID", segmentInfo.CollectionID),
 		zap.Int64("SegmentID", segmentInfo.ID),
-		zap.Int("Rows", totalRows),
-		zap.String("channel", segmentInfo.InsertChannel))
+		zap.Int("Rows", maxNumOfRows),
+		zap.String("Channel", segmentInfo.InsertChannel))
 
 	s.helper.afterCreateSegment(segmentInfo)
-
-	return segStatus, nil
+	return status, nil
 }
 
-func (s *SegmentManager) estimateTotalRows(collectionID UniqueID) (int, error) {
+func (s *SegmentManager) estimateMaxNumOfRows(collectionID UniqueID) (int, error) {
 	collMeta, err := s.meta.GetCollection(collectionID)
 	if err != nil {
 		return -1, err
@@ -391,12 +389,12 @@ func (s *SegmentManager) GetFlushableSegments(ctx context.Context, channel strin
 	}
 
 	ret := make([]UniqueID, 0)
-	for _, segStatus := range s.stats {
-		if segStatus.insertChannel != channel {
+	for _, status := range s.stats {
+		if status.insertChannel != channel {
 			continue
 		}
-		if s.flushPolicy.apply(segStatus, t) {
-			ret = append(ret, segStatus.id)
+		if s.flushPolicy.apply(status, t) {
+			ret = append(ret, status.id)
 		}
 	}
 
@@ -416,34 +414,34 @@ func (s *SegmentManager) UpdateSegmentStats(stat *internalpb.SegmentStatisticsUp
 // tryToSealSegment applies segment & channel seal policies
 func (s *SegmentManager) tryToSealSegment(ts Timestamp) error {
 	channelInfo := make(map[string][]*segmentStatus)
-	for _, segStatus := range s.stats {
-		channelInfo[segStatus.insertChannel] = append(channelInfo[segStatus.insertChannel], segStatus)
-		if segStatus.sealed {
+	for _, status := range s.stats {
+		channelInfo[status.insertChannel] = append(channelInfo[status.insertChannel], status)
+		if status.sealed {
 			continue
 		}
 		// change shouldSeal to segment seal policy logic
 		for _, policy := range s.segmentSealPolicies {
-			if policy(segStatus, ts) {
-				if err := s.meta.SealSegment(segStatus.id); err != nil {
+			if policy(status, ts) {
+				if err := s.meta.SealSegment(status.id); err != nil {
 					return err
 				}
-				segStatus.sealed = true
+				status.sealed = true
 				break
 			}
 		}
 
 	}
-	for channel, segs := range channelInfo {
+	for channel, segmentStats := range channelInfo {
 		for _, policy := range s.channelSealPolicies {
-			vs := policy(channel, segs, ts)
-			for _, seg := range vs {
-				if seg.sealed {
+			vs := policy(channel, segmentStats, ts)
+			for _, status := range vs {
+				if status.sealed {
 					continue
 				}
-				if err := s.meta.SealSegment(seg.id); err != nil {
+				if err := s.meta.SealSegment(status.id); err != nil {
 					return err
 				}
-				seg.sealed = true
+				status.sealed = true
 			}
 		}
 	}

internal/datacoord/server.go

@@ -37,12 +37,20 @@ import (
 	"github.com/milvus-io/milvus/internal/proto/milvuspb"
 )
 
-const rootCoordClientTimout = 20 * time.Second
+const (
+	rootCoordClientTimout = 20 * time.Second
+	connEtcdMaxRetryTime  = 100000
+	connEtcdRetryInterval = 200 * time.Millisecond
+)
 
 type (
 	UniqueID  = typeutil.UniqueID
 	Timestamp = typeutil.Timestamp
 )
+
+type dataNodeCreatorFunc func(ctx context.Context, addr string) (types.DataNode, error)
+type rootCoordCreatorFunc func(ctx context.Context) (types.RootCoord, error)
+
 type Server struct {
 	ctx              context.Context
 	serverLoopCtx    context.Context
@@ -67,27 +75,30 @@ type Server struct {
 	activeCh <-chan bool
 	eventCh  <-chan *sessionutil.SessionEvent
 
-	dataClientCreator      func(addr string) (types.DataNode, error)
-	rootCoordClientCreator func(addr string) (types.RootCoord, error)
+	dataClientCreator      dataNodeCreatorFunc
+	rootCoordClientCreator rootCoordCreatorFunc
 }
 
 func CreateServer(ctx context.Context, factory msgstream.Factory) (*Server, error) {
 	rand.Seed(time.Now().UnixNano())
 	s := &Server{
-		ctx:       ctx,
-		msFactory: factory,
-		flushCh:   make(chan UniqueID, 1024),
+		ctx:                    ctx,
+		msFactory:              factory,
+		flushCh:                make(chan UniqueID, 1024),
+		dataClientCreator:      defaultDataNodeCreatorFunc,
+		rootCoordClientCreator: defaultRootCoordCreatorFunc,
 	}
-	s.dataClientCreator = func(addr string) (types.DataNode, error) {
-		return datanodeclient.NewClient(addr, 3*time.Second)
-	}
-	s.rootCoordClientCreator = func(addr string) (types.RootCoord, error) {
-		return rootcoordclient.NewClient(ctx, Params.MetaRootPath, Params.EtcdEndpoints, rootCoordClientTimout)
-	}
-
 	return s, nil
 }
 
+func defaultDataNodeCreatorFunc(ctx context.Context, addr string) (types.DataNode, error) {
+	return datanodeclient.NewClient(ctx, addr, 3*time.Second)
+}
+
+func defaultRootCoordCreatorFunc(ctx context.Context) (types.RootCoord, error) {
+	return rootcoordclient.NewClient(ctx, Params.MetaRootPath, Params.EtcdEndpoints, rootCoordClientTimout)
+}
+
 // Register register data service at etcd
 func (s *Server) Register() error {
 	s.session = sessionutil.NewSession(s.ctx, Params.MetaRootPath, Params.EtcdEndpoints)
@@ -127,7 +138,7 @@ func (s *Server) Start() error {
 		return err
 	}
 
-	s.allocator = newAllocator(s.rootCoordClient)
+	s.allocator = newRootCoordAllocator(s.ctx, s.rootCoordClient)
 
 	s.startSegmentManager()
 	if err = s.initFlushMsgStream(); err != nil {
@@ -141,7 +152,7 @@ func (s *Server) Start() error {
 	s.startServerLoop()
 
 	atomic.StoreInt64(&s.isServing, 2)
-	log.Debug("start success")
+	log.Debug("DataCoordinator startup success")
 	return nil
 }
 
@@ -150,7 +161,7 @@ func (s *Server) initCluster() error {
 	if err != nil {
 		return err
 	}
-	sManager := newClusterSessionManager(s.dataClientCreator)
+	sManager := newClusterSessionManager(s.ctx, s.dataClientCreator)
 	s.cluster = newCluster(s.ctx, dManager, sManager, s)
 	return nil
 }
@@ -211,7 +222,7 @@ func (s *Server) initMeta() error {
 		}
 		return nil
 	}
-	return retry.Retry(100000, time.Millisecond*200, connectEtcdFn)
+	return retry.Retry(connEtcdMaxRetryTime, connEtcdRetryInterval, connectEtcdFn)
 }
 
 func (s *Server) initFlushMsgStream() error {
@@ -224,7 +235,6 @@ func (s *Server) initFlushMsgStream() error {
 	s.flushMsgStream.AsProducer([]string{Params.SegmentInfoChannelName})
 	log.Debug("DataCoord AsProducer:" + Params.SegmentInfoChannelName)
 	s.flushMsgStream.Start()
-
 	return nil
 }
 
@@ -251,6 +261,7 @@ func (s *Server) startStatsChannel(ctx context.Context) {
 	for {
 		select {
 		case <-ctx.Done():
+			log.Debug("stats channel shutdown")
 			return
 		default:
 		}
@@ -290,7 +301,7 @@ func (s *Server) startDataNodeTtLoop(ctx context.Context) {
 	for {
 		select {
 		case <-ctx.Done():
-			log.Debug("data node tt loop done")
+			log.Debug("data node tt loop shutdown")
 			return
 		default:
 		}
@@ -381,7 +392,7 @@ func (s *Server) startActiveCheck(ctx context.Context) {
 				continue
 			}
 			s.Stop()
-			log.Debug("disconnect with etcd")
+			log.Debug("disconnect with etcd and shutdown data coordinator")
 			return
 		case <-ctx.Done():
 			log.Debug("connection check shutdown")
@@ -438,8 +449,7 @@ func (s *Server) handleFlushingSegments(ctx context.Context) {
 
 func (s *Server) initRootCoordClient() error {
 	var err error
-	s.rootCoordClient, err = s.rootCoordClientCreator("")
-	if err != nil {
+	if s.rootCoordClient, err = s.rootCoordClientCreator(s.ctx); err != nil {
 		return err
 	}
 	if err = s.rootCoordClient.Init(); err != nil {

internal/datacoord/server_test.go

@@ -636,7 +636,7 @@ func TestGetRecoveryInfo(t *testing.T) {
 	svr := newTestServer(t, nil)
 	defer closeTestServer(t, svr)
 
-	svr.rootCoordClientCreator = func(addr string) (types.RootCoord, error) {
+	svr.rootCoordClientCreator = func(ctx context.Context) (types.RootCoord, error) {
 		return newMockRootCoordService(), nil
 	}
 
@@ -773,10 +773,10 @@ func newTestServer(t *testing.T, receiveCh chan interface{}) *Server {
 
 	svr, err := CreateServer(context.TODO(), factory)
 	assert.Nil(t, err)
-	svr.dataClientCreator = func(addr string) (types.DataNode, error) {
+	svr.dataClientCreator = func(ctx context.Context, addr string) (types.DataNode, error) {
 		return newMockDataNodeClient(0, receiveCh)
 	}
-	svr.rootCoordClientCreator = func(addr string) (types.RootCoord, error) {
+	svr.rootCoordClientCreator = func(ctx context.Context) (types.RootCoord, error) {
 		return newMockRootCoordService(), nil
 	}
 	assert.Nil(t, err)

internal/distributed/datanode/client/client.go

@@ -45,7 +45,7 @@ type Client struct {
 	recallTry int
 }
 
-func NewClient(addr string, timeout time.Duration) (*Client, error) {
+func NewClient(ctx context.Context, addr string, timeout time.Duration) (*Client, error) {
 	if addr == "" {
 		return nil, fmt.Errorf("address is empty")
 	}
@@ -54,7 +54,7 @@ func NewClient(addr string, timeout time.Duration) (*Client, error) {
 		grpc:      nil,
 		conn:      nil,
 		addr:      addr,
-		ctx:       context.Background(),
+		ctx:       ctx,
 		timeout:   timeout,
 		recallTry: 3,
 		reconnTry: 10,