Handle NDC active -> passive transition with transient workflow & no …

…buffered event

service/history/nDCBranchMgr.go

@@ -169,6 +169,12 @@ func (r *nDCBranchMgrImpl) flushBufferedEvents(
 	// check whether there are buffered events, if so, flush it
 	// NOTE: buffered events does not show in version history or next event id
 	if !r.mutableState.HasBufferedEvents() {
+		if r.mutableState.HasTransientWorkflowTask() {
+			if err := r.mutableState.ClearTransientWorkflowTask(); err != nil {
+				return nil, 0, err
+			}
+			// now transient task is gone
+		}
 		return lcaVersionHistoryItem, versionHistoryIndex, nil
 	}
 

service/history/nDCBranchMgr_test.go

@@ -34,6 +34,7 @@ import (
 	"github.com/stretchr/testify/suite"
 	enumspb "go.temporal.io/api/enums/v1"
 	historypb "go.temporal.io/api/history/v1"
+
 	historyspb "go.temporal.io/server/api/history/v1"
 	persistencespb "go.temporal.io/server/api/persistence/v1"
 	"go.temporal.io/server/common/cluster"
@@ -173,6 +174,46 @@ func (s *nDCBranchMgrSuite) TestCreateNewBranch() {
 	s.True(compareVersionHistory.Equal(newVersionHistory))
 }
 
+func (s *nDCBranchMgrSuite) TestClearTransientWorkflowTask() {
+
+	lastWriteVersion := int64(300)
+	versionHistory := versionhistory.NewVersionHistory([]byte("some random base branch token"), []*historyspb.VersionHistoryItem{
+		versionhistory.NewVersionHistoryItem(10, 0),
+		versionhistory.NewVersionHistoryItem(50, 100),
+		versionhistory.NewVersionHistoryItem(100, 200),
+		versionhistory.NewVersionHistoryItem(150, 300),
+	})
+	versionHistories := versionhistory.NewVersionHistories(versionHistory)
+
+	incomingVersionHistory := versionhistory.CopyVersionHistory(versionHistory)
+	err := versionhistory.AddOrUpdateVersionHistoryItem(
+		incomingVersionHistory,
+		versionhistory.NewVersionHistoryItem(200, 300),
+	)
+	s.NoError(err)
+
+	s.mockMutableState.EXPECT().GetLastWriteVersion().Return(lastWriteVersion, nil).AnyTimes()
+	s.mockMutableState.EXPECT().HasBufferedEvents().Return(false).AnyTimes()
+	s.mockMutableState.EXPECT().HasTransientWorkflowTask().Return(true).AnyTimes()
+	s.mockMutableState.EXPECT().ClearTransientWorkflowTask().Return(nil).AnyTimes()
+
+	s.mockMutableState.EXPECT().GetExecutionInfo().Return(&persistencespb.WorkflowExecutionInfo{
+		NamespaceId:      s.namespaceID,
+		WorkflowId:       s.workflowID,
+		VersionHistories: versionHistories,
+	}).AnyTimes()
+	s.mockMutableState.EXPECT().GetExecutionState().Return(&persistencespb.WorkflowExecutionState{
+		RunId: s.runID,
+	}).AnyTimes()
+
+	_, _, err = s.nDCBranchMgr.prepareVersionHistory(
+		context.Background(),
+		incomingVersionHistory,
+		150+2,
+		300)
+	s.IsType(&serviceerrors.RetryReplication{}, err)
+}
+
 func (s *nDCBranchMgrSuite) TestFlushBufferedEvents() {
 
 	lastWriteVersion := int64(300)
@@ -244,6 +285,7 @@ func (s *nDCBranchMgrSuite) TestPrepareVersionHistory_BranchAppendable_NoMissing
 
 	s.mockMutableState.EXPECT().GetExecutionInfo().Return(&persistencespb.WorkflowExecutionInfo{VersionHistories: versionHistories}).AnyTimes()
 	s.mockMutableState.EXPECT().HasBufferedEvents().Return(false).AnyTimes()
+	s.mockMutableState.EXPECT().HasTransientWorkflowTask().Return(false).AnyTimes()
 
 	doContinue, index, err := s.nDCBranchMgr.prepareVersionHistory(
 		context.Background(),
@@ -274,6 +316,7 @@ func (s *nDCBranchMgrSuite) TestPrepareVersionHistory_BranchAppendable_MissingEv
 	s.NoError(err)
 
 	s.mockMutableState.EXPECT().HasBufferedEvents().Return(false).AnyTimes()
+	s.mockMutableState.EXPECT().HasTransientWorkflowTask().Return(false).AnyTimes()
 	s.mockMutableState.EXPECT().GetExecutionInfo().Return(&persistencespb.WorkflowExecutionInfo{
 		NamespaceId:      s.namespaceID,
 		WorkflowId:       s.workflowID,
@@ -314,6 +357,7 @@ func (s *nDCBranchMgrSuite) TestPrepareVersionHistory_BranchNotAppendable_NoMiss
 	newBranchToken := []byte("some random new branch token")
 
 	s.mockMutableState.EXPECT().HasBufferedEvents().Return(false).AnyTimes()
+	s.mockMutableState.EXPECT().HasTransientWorkflowTask().Return(false).AnyTimes()
 	s.mockMutableState.EXPECT().GetExecutionInfo().Return(&persistencespb.WorkflowExecutionInfo{
 		NamespaceId:      s.namespaceID,
 		WorkflowId:       s.workflowID,
@@ -372,6 +416,7 @@ func (s *nDCBranchMgrSuite) TestPrepareVersionHistory_BranchNotAppendable_Missin
 	})
 
 	s.mockMutableState.EXPECT().HasBufferedEvents().Return(false).AnyTimes()
+	s.mockMutableState.EXPECT().HasTransientWorkflowTask().Return(false).AnyTimes()
 	s.mockMutableState.EXPECT().GetExecutionInfo().Return(&persistencespb.WorkflowExecutionInfo{
 		NamespaceId:      s.namespaceID,
 		WorkflowId:       s.workflowID,

service/history/workflow/mutable_state.go

@@ -176,6 +176,8 @@ type (
 		GetWorkflowType() *commonpb.WorkflowType
 		GetWorkflowStateStatus() (enumsspb.WorkflowExecutionState, enumspb.WorkflowExecutionStatus)
 		GetQueryRegistry() QueryRegistry
+		HasTransientWorkflowTask() bool
+		ClearTransientWorkflowTask() error
 		HasBufferedEvents() bool
 		HasInFlightWorkflowTask() bool
 		HasParentExecution() bool

service/history/workflow/mutable_state_impl.go

@@ -1254,6 +1254,46 @@ func (e *MutableStateImpl) GetInFlightWorkflowTask() (*WorkflowTaskInfo, bool) {
 	return e.workflowTaskManager.GetInFlightWorkflowTask()
 }
 
+func (e *MutableStateImpl) HasTransientWorkflowTask() bool {
+	workflowTask, ok := e.GetInFlightWorkflowTask()
+	if !ok {
+		return false
+	}
+	return workflowTask.ScheduleID >= e.GetNextEventID()
+}
+
+func (e *MutableStateImpl) ClearTransientWorkflowTask() error {
+	workflowTask, ok := e.GetInFlightWorkflowTask()
+	if !ok {
+		return serviceerror.NewInternal("cannot clear transient workflow task when task is missing")
+	}
+
+	if workflowTask.ScheduleID < e.GetNextEventID() {
+		return serviceerror.NewInternal("cannot clear transient workflow task when task is not transient")
+	}
+	// workflowTask.ScheduleID >= e.GetNextEventID()
+	// this is transient workflow
+	if e.HasBufferedEvents() {
+		return serviceerror.NewInternal("cannot clear transient workflow task when there are buffered events")
+	}
+	// no buffered event
+	resetWorkflowTaskInfo := &WorkflowTaskInfo{
+		Version:             common.EmptyVersion,
+		ScheduleID:          common.EmptyEventID,
+		StartedID:           common.EmptyEventID,
+		RequestID:           emptyUUID,
+		WorkflowTaskTimeout: timestamp.DurationFromSeconds(0),
+		Attempt:             1,
+		StartedTime:         timestamp.UnixOrZeroTimePtr(0),
+		ScheduledTime:       timestamp.UnixOrZeroTimePtr(0),
+
+		TaskQueue:             nil,
+		OriginalScheduledTime: timestamp.UnixOrZeroTimePtr(0),
+	}
+	e.workflowTaskManager.UpdateWorkflowTask(resetWorkflowTaskInfo)
+	return nil
+}
+
 func (e *MutableStateImpl) HasBufferedEvents() bool {
 	return e.hBuilder.HasBufferEvents()
 }