core/state: clear out cached state data when reset occurs (ethereum#2…

…7376)

* core/state: remove cached snap data if reset occurs

* core/state: address comment from peter

* core/state: skip revert in case data is nil

core/state/journal.go

@@ -93,6 +93,8 @@ type (
 		account      *common.Address
 		prev         *stateObject
 		prevdestruct bool
+		prevAccount  []byte
+		prevStorage  map[common.Hash][]byte
 	}
 	suicideChange struct {
 		account     *common.Address
@@ -160,6 +162,12 @@ func (ch resetObjectChange) revert(s *StateDB) {
 	if !ch.prevdestruct {
 		delete(s.stateObjectsDestruct, ch.prev.address)
 	}
+	if ch.prevAccount != nil {
+		s.snapAccounts[ch.prev.addrHash] = ch.prevAccount
+	}
+	if ch.prevStorage != nil {
+		s.snapStorage[ch.prev.addrHash] = ch.prevStorage
+	}
 }
 
 func (ch resetObjectChange) dirtied() *common.Address {

core/state/statedb.go

@@ -627,11 +627,34 @@ func (s *StateDB) createObject(addr common.Address) (newobj, prev *stateObject)
 	if prev == nil {
 		s.journal.append(createObjectChange{account: &addr})
 	} else {
+		// The original account should be marked as destructed and all cached
+		// account and storage data should be cleared as well. Note, it must
+		// be done here, otherwise the destruction event of original one will
+		// be lost.
 		_, prevdestruct := s.stateObjectsDestruct[prev.address]
 		if !prevdestruct {
 			s.stateObjectsDestruct[prev.address] = struct{}{}
 		}
-		s.journal.append(resetObjectChange{account: &addr, prev: prev, prevdestruct: prevdestruct})
+		var (
+			account []byte
+			storage map[common.Hash][]byte
+		)
+		// There may be some cached account/storage data already since IntermediateRoot
+		// will be called for each transaction before byzantium fork which will always
+		// cache the latest account/storage data.
+		if s.snap != nil {
+			account = s.snapAccounts[prev.addrHash]
+			storage = s.snapStorage[prev.addrHash]
+			delete(s.snapAccounts, prev.addrHash)
+			delete(s.snapStorage, prev.addrHash)
+		}
+		s.journal.append(resetObjectChange{
+			account:      &addr,
+			prev:         prev,
+			prevdestruct: prevdestruct,
+			prevAccount:  account,
+			prevStorage:  storage,
+		})
 	}
 	s.setStateObject(newobj)
 	if prev != nil && !prev.deleted {

core/state/statedb_test.go

@@ -31,7 +31,10 @@ import (
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/rawdb"
+	"github.com/ethereum/go-ethereum/core/state/snapshot"
 	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/trie"
 )
 
 // Tests that updating a state trie does not leak any database writes prior to
@@ -998,3 +1001,37 @@ func TestStateDBTransientStorage(t *testing.T) {
 		t.Fatalf("transient storage mismatch: have %x, want %x", got, value)
 	}
 }
+
+func TestResetObject(t *testing.T) {
+	var (
+		disk     = rawdb.NewMemoryDatabase()
+		tdb      = trie.NewDatabase(disk)
+		db       = NewDatabaseWithNodeDB(disk, tdb)
+		snaps, _ = snapshot.New(snapshot.Config{CacheSize: 10}, disk, tdb, types.EmptyRootHash)
+		state, _ = New(types.EmptyRootHash, db, snaps)
+		addr     = common.HexToAddress("0x1")
+		slotA    = common.HexToHash("0x1")
+		slotB    = common.HexToHash("0x2")
+	)
+	// Initialize account with balance and storage in first transaction.
+	state.SetBalance(addr, big.NewInt(1))
+	state.SetState(addr, slotA, common.BytesToHash([]byte{0x1}))
+	state.IntermediateRoot(true)
+
+	// Reset account and mutate balance and storages
+	state.CreateAccount(addr)
+	state.SetBalance(addr, big.NewInt(2))
+	state.SetState(addr, slotB, common.BytesToHash([]byte{0x2}))
+	root, _ := state.Commit(true)
+
+	// Ensure the original account is wiped properly
+	snap := snaps.Snapshot(root)
+	slot, _ := snap.Storage(crypto.Keccak256Hash(addr.Bytes()), crypto.Keccak256Hash(slotA.Bytes()))
+	if len(slot) != 0 {
+		t.Fatalf("Unexpected storage slot")
+	}
+	slot, _ = snap.Storage(crypto.Keccak256Hash(addr.Bytes()), crypto.Keccak256Hash(slotB.Bytes()))
+	if !bytes.Equal(slot, []byte{0x2}) {
+		t.Fatalf("Unexpected storage slot value %v", slot)
+	}
+}