Remove commented code and fix naming issue

This PR removes all the commented code and files from PR #28320

For naming issue:
- Renaming `MinCheckpoint` to `EarliestPosition`, see #28320 comment
- Renaming `writebuffer.Mananger` to `BufferMananger`, see #27874
  comment

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

Makefile

@@ -433,7 +433,7 @@ generate-mockery-datanode: getdeps
 	$(INSTALL_PATH)/mockery --name=MetaCache --dir=$(PWD)/internal/datanode/metacache --output=$(PWD)/internal/datanode/metacache --filename=mock_meta_cache.go --with-expecter --structname=MockMetaCache --outpkg=metacache --inpackage
 	$(INSTALL_PATH)/mockery --name=SyncManager --dir=$(PWD)/internal/datanode/syncmgr --output=$(PWD)/internal/datanode/syncmgr --filename=mock_sync_manager.go --with-expecter --structname=MockSyncManager --outpkg=syncmgr --inpackage
 	$(INSTALL_PATH)/mockery --name=WriteBuffer --dir=$(PWD)/internal/datanode/writebuffer --output=$(PWD)/internal/datanode/writebuffer --filename=mock_write_buffer.go --with-expecter --structname=MockWriteBuffer --outpkg=writebuffer --inpackage
-	$(INSTALL_PATH)/mockery --name=Manager --dir=$(PWD)/internal/datanode/writebuffer --output=$(PWD)/internal/datanode/writebuffer --filename=mock_mananger.go --with-expecter --structname=MockManager --outpkg=writebuffer --inpackage
+	$(INSTALL_PATH)/mockery --name=BufferManager --dir=$(PWD)/internal/datanode/writebuffer --output=$(PWD)/internal/datanode/writebuffer --filename=mock_mananger.go --with-expecter --structname=MockBufferManager --outpkg=writebuffer --inpackage
 
 generate-mockery-metastore: getdeps
 	$(INSTALL_PATH)/mockery --name=RootCoordCatalog --dir=$(PWD)/internal/metastore --output=$(PWD)/internal/metastore/mocks --filename=mock_rootcoord_catalog.go --with-expecter --structname=RootCoordCatalog --outpkg=mocks

internal/datanode/compactor.go

@@ -133,7 +133,7 @@ func (t *compactionTask) getChannelName() string {
 func (t *compactionTask) getNumRows() (int64, error) {
 	numRows := int64(0)
 	for _, binlog := range t.plan.SegmentBinlogs {
-		seg, ok := t.metaCache.GetSegmentByID(binlog.GetSegmentID()) // Channel.getSegment(binlog.GetSegmentID())
+		seg, ok := t.metaCache.GetSegmentByID(binlog.GetSegmentID())
 		if !ok {
 			return 0, merr.WrapErrSegmentNotFound(binlog.GetSegmentID(), "get compaction segments num rows failed")
 		}

internal/datanode/data_node.go

@@ -89,7 +89,7 @@ type DataNode struct {
 	eventManagerMap  *typeutil.ConcurrentMap[string, *channelEventManager]
 
 	syncMgr            syncmgr.SyncManager
-	writeBufferManager writebuffer.Manager
+	writeBufferManager writebuffer.BufferManager
 
 	clearSignal        chan string // vchannel name
 	segmentCache       *Cache

internal/datanode/data_sync_service.go

@@ -45,9 +45,8 @@ import (
 
 // dataSyncService controls a flowgraph for a specific collection
 type dataSyncService struct {
-	ctx      context.Context
-	cancelFn context.CancelFunc
-	// channel      Channel // channel stores meta of channel
+	ctx          context.Context
+	cancelFn     context.CancelFunc
 	metacache    metacache.MetaCache
 	opID         int64
 	collectionID UniqueID // collection id of vchan for which this data sync service serves
@@ -74,20 +73,16 @@ type dataSyncService struct {
 	dispClient   msgdispatcher.Client
 	chunkManager storage.ChunkManager
 
-	// test only
-	// flushListener chan *segmentFlushPack // chan to listen flush event
-
 	stopOnce sync.Once
 }
 
 type nodeConfig struct {
 	msFactory    msgstream.Factory // msgStream factory
 	collectionID UniqueID
 	vChannelName string
-	// channel Channel
-	metacache metacache.MetaCache
-	allocator allocator.Allocator
-	serverID  UniqueID
+	metacache    metacache.MetaCache
+	allocator    allocator.Allocator
+	serverID     UniqueID
 }
 
 // start the flow graph in dataSyncService

internal/datanode/data_sync_service_test.go

@@ -326,7 +326,7 @@ type DataSyncServiceSuite struct {
 	chunkManager *mocks.ChunkManager
 	broker       *broker.MockBroker
 	allocator    *allocator.MockAllocator
-	wbManager    *writebuffer.MockManager
+	wbManager    *writebuffer.MockBufferManager
 
 	factory *dependency.MockFactory
 	ms      *msgstream.MockMsgStream
@@ -344,7 +344,7 @@ func (s *DataSyncServiceSuite) SetupTest() {
 	s.chunkManager = mocks.NewChunkManager(s.T())
 	s.broker = broker.NewMockBroker(s.T())
 	s.allocator = allocator.NewMockAllocator(s.T())
-	s.wbManager = writebuffer.NewMockManager(s.T())
+	s.wbManager = writebuffer.NewMockBufferManager(s.T())
 
 	s.broker.EXPECT().UpdateSegmentStatistics(mock.Anything, mock.Anything).Return(nil).Maybe()
 

internal/datanode/flow_graph_time_tick_node.go

@@ -47,7 +47,7 @@ type ttNode struct {
 	BaseNode
 	vChannelName       string
 	metacache          metacache.MetaCache
-	writeBufferManager writebuffer.Manager
+	writeBufferManager writebuffer.BufferManager
 	lastUpdateTime     *atomic.Time
 	broker             broker.Broker
 
@@ -152,7 +152,7 @@ func (ttn *ttNode) updateChannelCP(channelPos *msgpb.MsgPosition, curTs time.Tim
 	return nil
 }
 
-func newTTNode(config *nodeConfig, broker broker.Broker, wbManager writebuffer.Manager) (*ttNode, error) {
+func newTTNode(config *nodeConfig, broker broker.Broker, wbManager writebuffer.BufferManager) (*ttNode, error) {
 	baseNode := BaseNode{}
 	baseNode.SetMaxQueueLength(Params.DataNodeCfg.FlowGraphMaxQueueLength.GetAsInt32())
 	baseNode.SetMaxParallelism(Params.DataNodeCfg.FlowGraphMaxParallelism.GetAsInt32())

internal/datanode/flow_graph_write_node.go

@@ -21,7 +21,7 @@ type writeNode struct {
 	BaseNode
 
 	channelName string
-	wbManager   writebuffer.Manager
+	wbManager   writebuffer.BufferManager
 	updater     statsUpdater
 	metacache   metacache.MetaCache
 }
@@ -110,7 +110,7 @@ func (wNode *writeNode) Operate(in []Msg) []Msg {
 
 func newWriteNode(
 	ctx context.Context,
-	writeBufferManager writebuffer.Manager,
+	writeBufferManager writebuffer.BufferManager,
 	updater statsUpdater,
 	config *nodeConfig,
 ) *writeNode {