From c94991382214d4f25def31ef935c28f5c4624f6a Mon Sep 17 00:00:00 2001
From: Nishant Das <nishdas93@gmail.com>
Date: Tue, 3 Nov 2020 22:43:06 +0800
Subject: [PATCH] start from finalized checkpoint (#7715)

---
 beacon-chain/powchain/log_processing.go | 18 ++++++++----------
 beacon-chain/powchain/service.go        | 18 +++++++++++-------
 2 files changed, 19 insertions(+), 17 deletions(-)

diff --git a/beacon-chain/powchain/log_processing.go b/beacon-chain/powchain/log_processing.go
index 27ba66114..85d7d885a 100644
--- a/beacon-chain/powchain/log_processing.go
+++ b/beacon-chain/powchain/log_processing.go
@@ -346,25 +346,23 @@ func (s *Service) processPastLogs(ctx context.Context) error {
 	}
 
 	s.latestEth1Data.LastRequestedBlock = currentBlockNum
-	b, err := s.beaconDB.HeadBlock(ctx)
+
+	c, err := s.beaconDB.FinalizedCheckpoint(ctx)
 	if err != nil {
 		return err
 	}
-	if b == nil || b.Block == nil {
+	fRoot := bytesutil.ToBytes32(c.Root)
+	// Return if no checkpoint exists yet.
+	if fRoot == params.BeaconConfig().ZeroHash {
 		return nil
 	}
-	r, err := b.Block.HashTreeRoot()
+	fState, err := s.stateGen.StateByRoot(ctx, fRoot)
 	if err != nil {
 		return err
 	}
-	currentState, err := s.stateGen.StateByRoot(ctx, r)
-	if err != nil {
-		return errors.Wrap(err, "could not get head state")
+	if fState != nil && fState.Eth1DepositIndex() > 0 {
+		s.depositCache.PrunePendingDeposits(ctx, int64(fState.Eth1DepositIndex()))
 	}
-	if currentState != nil && currentState.Eth1DepositIndex() > 0 {
-		s.depositCache.PrunePendingDeposits(ctx, int64(currentState.Eth1DepositIndex()))
-	}
-
 	return nil
 }
 
diff --git a/beacon-chain/powchain/service.go b/beacon-chain/powchain/service.go
index 55db17af0..dc323d02a 100644
--- a/beacon-chain/powchain/service.go
+++ b/beacon-chain/powchain/service.go
@@ -520,19 +520,23 @@ func (s *Service) initDepositCaches(ctx context.Context, ctrs []*protodb.Deposit
 		return err
 	}
 	// Default to all deposits post-genesis deposits in
-	// the event we cannot find a suitable head state.
+	// the event we cannot find a finalized state.
 	currIndex := genesisState.Eth1DepositIndex()
-	rt := s.beaconDB.LastArchivedRoot(ctx)
+	chkPt, err := s.beaconDB.FinalizedCheckpoint(ctx)
+	if err != nil {
+		return err
+	}
+	rt := bytesutil.ToBytes32(chkPt.Root)
 	if rt != [32]byte{} {
-		currentState, err := s.beaconDB.State(ctx, rt)
+		fState, err := s.stateGen.StateByRoot(ctx, rt)
 		if err != nil {
-			return errors.Wrap(err, "could not get last archived state")
+			return errors.Wrap(err, "could not get finalized state")
 		}
-		if currentState == nil {
-			return errors.Errorf("archived state with root %#x does not exist in the db", rt)
+		if fState == nil {
+			return errors.Errorf("finalized state with root %#x does not exist in the db", rt)
 		}
 		// Set deposit index to the one in the current archived state.
-		currIndex = currentState.Eth1DepositIndex()
+		currIndex = fState.Eth1DepositIndex()
 	}
 	validDepositsCount.Add(float64(currIndex + 1))
 	// Only add pending deposits if the container slice length