Fill domainID for backwards compatibility (cadence-workflow#4819)

* Fill domainID for backwards compatibility

* Added unit test

service/history/execution/mutable_state_builder.go

@@ -331,6 +331,8 @@ func (e *mutableStateBuilder) Load(
 	e.replicationState = state.ReplicationState
 	e.checksum = state.Checksum
 
+	e.fillForBackwardsCompatibility()
+
 	if len(state.Checksum.Value) > 0 {
 		switch {
 		case e.shouldInvalidateChecksum():
@@ -348,6 +350,21 @@ func (e *mutableStateBuilder) Load(
 	}
 }
 
+func (e *mutableStateBuilder) fillForBackwardsCompatibility() {
+	// With https://github.com/uber/cadence/pull/4601 newly introduced DomainID may not be set for older workflows.
+	// Here we will fill its value based on previously used domain name.
+	for _, info := range e.pendingChildExecutionInfoIDs {
+		if info.DomainID == "" && info.DomainNameDEPRECATED != "" {
+			domainID, err := e.shard.GetDomainCache().GetDomainID(info.DomainNameDEPRECATED)
+			if err != nil {
+				e.logError("failed to fill domainId for pending child executions", tag.Error(err))
+			}
+
+			info.DomainID = domainID
+		}
+	}
+}
+
 func (e *mutableStateBuilder) GetCurrentBranchToken() ([]byte, error) {
 	if e.versionHistories != nil {
 		currentVersionHistory, err := e.versionHistories.GetCurrentVersionHistory()

service/history/execution/mutable_state_builder_test.go

@@ -95,6 +95,8 @@ func (s *mutableStateSuite) SetupTest() {
 	s.testScope = s.mockShard.Resource.MetricsScope
 	s.logger = s.mockShard.GetLogger()
 
+	s.mockShard.Resource.DomainCache.EXPECT().GetDomainID(constants.TestDomainName).Return(constants.TestDomainID, nil).AnyTimes()
+
 	s.msBuilder = newMutableStateBuilder(s.mockShard, s.logger, constants.TestLocalDomainEntry)
 }
 
@@ -787,6 +789,14 @@ func (s *mutableStateSuite) prepareTransientDecisionCompletionFirstBatchReplicat
 	return newDecisionScheduleEvent, newDecisionStartedEvent
 }
 
+func (s *mutableStateSuite) TestLoad_BackwardsCompatibility() {
+	mutableState := s.buildWorkflowMutableState()
+
+	s.msBuilder.Load(mutableState)
+
+	s.Equal(constants.TestDomainID, s.msBuilder.pendingChildExecutionInfoIDs[81].DomainID)
+}
+
 func (s *mutableStateSuite) TestUpdateCurrentVersion_WorkflowOpen() {
 	mutableState := s.buildWorkflowMutableState()
 
@@ -892,6 +902,16 @@ func (s *mutableStateSuite) buildWorkflowMutableState() *persistence.WorkflowMut
 			DomainID:              constants.TestDomainID,
 			WorkflowTypeName:      "code.uber.internal/test/foobar",
 		},
+		81: {
+			Version:               failoverVersion,
+			InitiatedID:           80,
+			InitiatedEventBatchID: 20,
+			InitiatedEvent:        &types.HistoryEvent{},
+			StartedID:             common.EmptyEventID,
+			CreateRequestID:       uuid.New(),
+			DomainNameDEPRECATED:  constants.TestDomainName,
+			WorkflowTypeName:      "code.uber.internal/test/foobar",
+		},
 	}
 
 	signalInfos := map[int64]*persistence.SignalInfo{