From 38a54239c832b3fc51117ade432242793e173df1 Mon Sep 17 00:00:00 2001
From: Sunny <sunny2022.za@gmail.com>
Date: Fri, 15 Nov 2024 14:45:08 +0800
Subject: [PATCH] feat: PEVM fallback to serial process

fallback to serial processor when pevm execution result is not correct
---
 core/blockchain.go | 56 +++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 53 insertions(+), 3 deletions(-)

diff --git a/core/blockchain.go b/core/blockchain.go
index 2f25bbc2d..2b9814ca2 100644
--- a/core/blockchain.go
+++ b/core/blockchain.go
@@ -539,6 +539,7 @@ func NewBlockChain(db ethdb.Database, cacheConfig *CacheConfig, genesis *Genesis
 		log.Info("Parallel V2 enabled", "parallelNum", ParallelNum())
 	} else {
 		bc.processor = NewStateProcessor(chainConfig, bc, engine)
+		bc.serialProcessor = bc.processor
 	}
 	// Start future block processor.
 	bc.wg.Add(1)
@@ -1832,6 +1833,11 @@ func (bc *BlockChain) insertChain(chain types.Blocks, setHead bool) (int, error)
 	defer func() {
 		DebugInnerExecutionDuration = 0
 	}()
+
+	if bc.serialProcessor == nil {
+		bc.serialProcessor = bc.processor
+	}
+
 	for ; block != nil && err == nil || errors.Is(err, ErrKnownBlock); block, err = it.next() {
 		DebugInnerExecutionDuration = 0
 		// If the chain is terminating, stop processing blocks
@@ -1897,6 +1903,7 @@ func (bc *BlockChain) insertChain(chain types.Blocks, setHead bool) (int, error)
 			err               error
 		)
 
+		blockProcessedInParallel := false
 		// skip block process if we already have the state, receipts and logs from mining work
 		if !(receiptExist && logExist && stateExist) {
 			// Retrieve the parent block and it's state to execute on top
@@ -1940,8 +1947,19 @@ func (bc *BlockChain) insertChain(chain types.Blocks, setHead bool) (int, error)
 			pstart = time.Now()
 			if bc.vmConfig.TxDAG == nil && bc.vmConfig.EnableParallelUnorderedMerge {
 				receipts, logs, usedGas, err = bc.serialProcessor.Process(block, statedb, bc.vmConfig)
+				blockProcessedInParallel = false
 			} else {
 				receipts, logs, usedGas, err = bc.processor.Process(block, statedb, bc.vmConfig)
+				blockProcessedInParallel = true
+				if err != nil {
+					// parallel processing fail , fallback to serial with new statDB.
+					log.Warn("ParallelEVM fallback!!!", "error", err.Error())
+					statedb, err = bc.reGenerateStateForFallBack(parent.Root, block.Root(), statedb)
+					statedb.StartPrefetcher("chain")
+					activeState = statedb
+					receipts, logs, usedGas, err = bc.serialProcessor.Process(block, statedb, bc.vmConfig)
+					blockProcessedInParallel = false
+				}
 			}
 			if err != nil {
 				bc.reportBlock(block, receipts, err)
@@ -1953,9 +1971,30 @@ func (bc *BlockChain) insertChain(chain types.Blocks, setHead bool) (int, error)
 
 		vstart := time.Now()
 		if err := bc.validator.ValidateState(block, statedb, receipts, usedGas); err != nil {
-			bc.reportBlock(block, receipts, err)
-			followupInterrupt.Store(true)
-			return it.index, err
+			if blockProcessedInParallel {
+				// invalid parallel execution, try serial
+				log.Warn("ParallelEVM fallback after ValidateState!!!", "error", err.Error())
+				parent := it.previous()
+				if parent == nil {
+					parent = bc.GetHeader(block.ParentHash(), block.NumberU64()-1)
+				}
+
+				statedb, err = bc.reGenerateStateForFallBack(parent.Root, block.Root(), statedb)
+				statedb.StartPrefetcher("chain")
+				activeState = statedb
+
+				receipts, logs, usedGas, err = bc.serialProcessor.Process(block, statedb, bc.vmConfig)
+				blockProcessedInParallel = false
+				if err := bc.validator.ValidateState(block, statedb, receipts, usedGas); err != nil {
+					bc.reportBlock(block, receipts, err)
+					followupInterrupt.Store(true)
+					return it.index, err
+				}
+			} else {
+				bc.reportBlock(block, receipts, err)
+				followupInterrupt.Store(true)
+				return it.index, err
+			}
 		}
 
 		vtime := time.Since(vstart)
@@ -2784,6 +2823,17 @@ func (bc *BlockChain) SetupTxDAGGeneration(output string, readFile bool) {
 
 }
 
+func (bc *BlockChain) reGenerateStateForFallBack(parentRoot common.Hash, blockRoot common.Hash, oldDB *state.StateDB) (*state.StateDB, error) {
+	oldDB.StopPrefetcher()
+	statedb, err := state.New(parentRoot, bc.stateCache, bc.snaps)
+	if err != nil {
+		return nil, err
+	}
+
+	statedb.SetExpectedStateRoot(blockRoot)
+	return statedb, nil
+}
+
 type TxDAGOutputItem struct {
 	blockNumber uint64
 	txDAG       types.TxDAG