From f740013e0e2e1d215b411b45766fa7977ce76b67 Mon Sep 17 00:00:00 2001
From: David <david@taiko.xyz>
Date: Sat, 22 Jul 2023 04:19:23 +0800
Subject: [PATCH] feat(driver): improve `ProcessL1Blocks` for reorg handling
 (#325)

---
 driver/chain_syncer/calldata/syncer.go | 21 +++++++++++-
 pkg/rpc/methods.go                     | 47 ++++++++++++++++++++++++--
 2 files changed, 64 insertions(+), 4 deletions(-)

diff --git a/driver/chain_syncer/calldata/syncer.go b/driver/chain_syncer/calldata/syncer.go
index df31d08cb..d621170a2 100644
--- a/driver/chain_syncer/calldata/syncer.go
+++ b/driver/chain_syncer/calldata/syncer.go
@@ -80,10 +80,29 @@ func (s *Syncer) ProcessL1Blocks(ctx context.Context, l1End *types.Header) error
 		s.reorgDetectedFlag = false
 		firstTry = false
 
+		startHeight := s.state.GetL1Current().Number
+		// If there is a L1 reorg, sometimes this will happen.
+		if startHeight.Uint64() >= l1End.Number.Uint64() {
+			startHeight = new(big.Int).Sub(l1End.Number, common.Big1)
+			newL1Current, err := s.rpc.L1.HeaderByNumber(ctx, startHeight)
+			if err != nil {
+				return err
+			}
+			s.state.SetL1Current(newL1Current)
+			s.lastInsertedBlockID = nil
+
+			log.Info(
+				"Reorg detected",
+				"oldL1Current", s.state.GetL1Current().Number,
+				"newL1Current", startHeight,
+				"l1Head", l1End.Number,
+			)
+		}
+
 		iter, err := eventIterator.NewBlockProposedIterator(ctx, &eventIterator.BlockProposedIteratorConfig{
 			Client:               s.rpc.L1,
 			TaikoL1:              s.rpc.TaikoL1,
-			StartHeight:          s.state.GetL1Current().Number,
+			StartHeight:          startHeight,
 			EndHeight:            l1End.Number,
 			FilterQuery:          nil,
 			OnBlockProposedEvent: s.onBlockProposed,
diff --git a/pkg/rpc/methods.go b/pkg/rpc/methods.go
index eb309f45b..16451d5c0 100644
--- a/pkg/rpc/methods.go
+++ b/pkg/rpc/methods.go
@@ -356,11 +356,33 @@ func (c *Client) CheckL1Reorg(ctx context.Context, blockID *big.Int) (bool, *typ
 
 		l1Origin, err := c.L2.L1OriginByID(ctx, blockID)
 		if err != nil {
-			// If the L2 EE is just synced through P2P, there is a chance that the EE do not have
-			// the chain head L1Origin information recorded.
 			if err.Error() == ethereum.NotFound.Error() {
 				log.Info("L1Origin not found", "blockID", blockID)
-				return false, nil, nil, nil
+
+				// If the L2 EE is just synced through P2P, there is a chance that the EE do not have
+				// the chain head L1Origin information recorded.
+				justSyncedByP2P, err := c.IsJustSyncedByP2P(ctx)
+				if err != nil {
+					return false,
+						nil,
+						nil,
+						fmt.Errorf("failed to check whether the L2 execution engine has just finished a P2P sync: %w", err)
+				}
+
+				log.Info(
+					"Check whether the L2 execution engine has just finished a P2P sync",
+					"justSyncedByP2P",
+					justSyncedByP2P,
+				)
+
+				if justSyncedByP2P {
+					return false, nil, nil, nil
+				}
+
+				log.Info("Reorg detected due to L1Origin not found", "blockID", blockID)
+				reorged = true
+				blockID = new(big.Int).Sub(blockID, common.Big1)
+				continue
 			}
 			return false, nil, nil, err
 		}
@@ -401,3 +423,22 @@ func (c *Client) CheckL1Reorg(ctx context.Context, blockID *big.Int) (bool, *typ
 
 	return reorged, l1CurrentToReset, blockIDToReset, nil
 }
+
+// IsJustSyncedByP2P checks whether the given L2 execution engine has just finished a P2P
+// sync.
+func (c *Client) IsJustSyncedByP2P(ctx context.Context) (bool, error) {
+	l2Head, err := c.L2.HeaderByNumber(ctx, nil)
+	if err != nil {
+		return false, err
+	}
+
+	if _, err = c.L2.L1OriginByID(ctx, l2Head.Number); err != nil {
+		if err.Error() == ethereum.NotFound.Error() {
+			return true, nil
+		}
+
+		return false, err
+	}
+
+	return false, nil
+}