Clear Pre-Genesis Objects (#4656)

* remove pre-genesis data
* Merge branch 'master' into clearUnusedObjects
* lint
* Merge branch 'clearUnusedObjects' of https://github.com/prysmaticlabs/geth-sharding into clearUnusedObjects
* fic build
* gaz
* faulty mock
* Update beacon-chain/blockchain/service.go

beacon-chain/blockchain/service.go

@@ -224,6 +224,9 @@ func (s *Service) initializeBeaconChain(
 
 	log.Info("Initialized beacon chain genesis state")
 
+	// Clear out all pre-genesis data now that the state is initialized.
+	s.chainStartFetcher.ClearPreGenesisData()
+
 	// Update committee shuffled indices for genesis epoch.
 	if err := helpers.UpdateCommitteeCache(genesisState, 0 /* genesis epoch */); err != nil {
 		return err

beacon-chain/interop-cold-start/service.go

@@ -127,6 +127,11 @@ func (s *Service) PreGenesisState() *pb.BeaconState {
 	return &pb.BeaconState{}
 }
 
+// ClearPreGenesisData --
+func (s *Service) ClearPreGenesisData() {
+	//no-op
+}
+
 // DepositByPubkey mocks out the deposit cache functionality for interop.
 func (s *Service) DepositByPubkey(ctx context.Context, pubKey []byte) (*ethpb.Deposit, *big.Int) {
 	return &ethpb.Deposit{}, big.NewInt(1)

beacon-chain/powchain/service.go

@@ -65,6 +65,7 @@ type ChainStartFetcher interface {
 	ChainStartDeposits() []*ethpb.Deposit
 	ChainStartEth1Data() *ethpb.Eth1Data
 	PreGenesisState() *pb.BeaconState
+	ClearPreGenesisData()
 }
 
 // ChainInfoFetcher retrieves information about eth1 metadata at the eth2 genesis time.
@@ -241,6 +242,12 @@ func (s *Service) ChainStartDeposits() []*ethpb.Deposit {
 	return s.chainStartData.ChainstartDeposits
 }
 
+// ClearPreGenesisData clears out the stored chainstart deposits and beacon state.
+func (s *Service) ClearPreGenesisData() {
+	s.chainStartData.ChainstartDeposits = []*ethpb.Deposit{}
+	s.preGenesisState = &pb.BeaconState{}
+}
+
 // ChainStartEth1Data returns the eth1 data at chainstart.
 func (s *Service) ChainStartEth1Data() *ethpb.Eth1Data {
 	return s.chainStartData.Eth1Data

beacon-chain/powchain/testing/mock.go

@@ -100,6 +100,11 @@ func (m *POWChain) PreGenesisState() *pb.BeaconState {
 	return &pb.BeaconState{}
 }
 
+// ClearPreGenesisData --
+func (m *POWChain) ClearPreGenesisData() {
+	//no-op
+}
+
 // IsConnectedToETH1 --
 func (m *POWChain) IsConnectedToETH1() bool {
 	return true