add few comments in code

consensus/XDPoS/engines/engine_v1/engine.go

@@ -483,6 +483,7 @@ func (x *XDPoS_v1) snapshot(chain consensus.ChainReader, number uint64, hash com
 			}
 			parents = parents[:len(parents)-1]
 		} else if selfHeader != nil && selfHeader.Hash() == hash {
+			// it prevents db doesn't have current block info, can be removed by refactor blockchain.go reorg function call.
 			header = selfHeader
 		} else {
 			// No explicit parents (or no more left), reach out to the database

core/blockchain.go

@@ -1345,6 +1345,9 @@ func (bc *BlockChain) WriteBlockWithState(block *types.Block, receipts []*types.
 		reorg = block.NumberU64() > currentBlock.NumberU64()
 	}
 
+	// This is the ETH fix. We shall ultimately have this workflow,
+	// but due to below code has diverged significantly between ETH and XDC, and current issue we have,
+	// it's best to have it in a different PR with more investigations.
 	// if reorg {
 	// 	// Write the positional metadata for transaction and receipt lookups
 	// 	if err := WriteTxLookupEntries(batch, block); err != nil {