add lists to keep track of actually hacked files

3 files changed, 540 insertions, 313 deletions

diff --git a/core/state/journal.go b/core/state/journal.go
index 6e85173..cfa1a4a 100644
--- a/core/state/journal.go
+++ b/core/state/journal.go
@@ -90,7 +90,8 @@ type (
 		account *common.Address
 	}
 	resetObjectChange struct {
-		prev *stateObject
+		prev         *stateObject
+		prevdestruct bool
 	}
 	suicideChange struct {
 		account     *common.Address
@@ -130,9 +131,7 @@ type (
 		hash common.Hash
 	}
 	touchChange struct {
-		account   *common.Address
-		prev      bool
-		prevDirty bool
+		account *common.Address
 	}
 )
 
@@ -147,6 +146,9 @@ func (ch createObjectChange) dirtied() *common.Address {
 
 func (ch resetObjectChange) revert(s *StateDB) {
 	s.setStateObject(ch.prev)
+	if !ch.prevdestruct && s.snap != nil {
+		delete(s.snapDestructs, ch.prev.addrHash)
+	}
 }
 
 func (ch resetObjectChange) dirtied() *common.Address {
diff --git a/core/state/state_object.go b/core/state/state_object.go
index 9c47dc4..2893f80 100644
--- a/core/state/state_object.go
+++ b/core/state/state_object.go
@@ -23,10 +23,10 @@ import (
 	"math/big"
 	"time"
 
-	"github.com/ava-labs/go-ethereum/common"
-	"github.com/ava-labs/go-ethereum/crypto"
-	"github.com/ava-labs/go-ethereum/metrics"
-	"github.com/ava-labs/go-ethereum/rlp"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/metrics"
+	"github.com/ethereum/go-ethereum/rlp"
 )
 
 var emptyCodeHash = crypto.Keccak256(nil)
@@ -79,9 +79,10 @@ type stateObject struct {
 	trie Trie // storage trie, which becomes non-nil on first access
 	code Code // contract bytecode, which gets set when code is loaded
 
-	originStorage Storage // Storage cache of original entries to dedup rewrites
-	dirtyStorage  Storage // Storage entries that need to be flushed to disk
-	fakeStorage   Storage // Fake storage which constructed by caller for debugging purpose.
+	originStorage  Storage // Storage cache of original entries to dedup rewrites, reset for every transaction
+	pendingStorage Storage // Storage entries that need to be flushed to disk, at the end of an entire block
+	dirtyStorage   Storage // Storage entries that have been modified in the current transaction execution
+	fakeStorage    Storage // Fake storage which constructed by caller for debugging purpose.
 
 	// Cache flags.
 	// When an object is marked suicided it will be delete from the trie
@@ -114,13 +115,17 @@ func newObject(db *StateDB, address common.Address, data Account) *stateObject {
 	if data.CodeHash == nil {
 		data.CodeHash = emptyCodeHash
 	}
+	if data.Root == (common.Hash{}) {
+		data.Root = emptyRoot
+	}
 	return &stateObject{
-		db:            db,
-		address:       address,
-		addrHash:      crypto.Keccak256Hash(address[:]),
-		data:          data,
-		originStorage: make(Storage),
-		dirtyStorage:  make(Storage),
+		db:             db,
+		address:        address,
+		addrHash:       crypto.Keccak256Hash(address[:]),
+		data:           data,
+		originStorage:  make(Storage),
+		pendingStorage: make(Storage),
+		dirtyStorage:   make(Storage),
 	}
 }
 
@@ -184,21 +189,44 @@ func (s *stateObject) GetCommittedState(db Database, key common.Hash) common.Has
 	if s.fakeStorage != nil {
 		return s.fakeStorage[key]
 	}
-	// If we have the original value cached, return that
-	value, cached := s.originStorage[key]
-	if cached {
+	// If we have a pending write or clean cached, return that
+	if value, pending := s.pendingStorage[key]; pending {
 		return value
 	}
-	// Track the amount of time wasted on reading the storage trie
-	if metrics.EnabledExpensive {
-		defer func(start time.Time) { s.db.StorageReads += time.Since(start) }(time.Now())
+	if value, cached := s.originStorage[key]; cached {
+		return value
 	}
-	// Otherwise load the value from the database
-	enc, err := s.getTrie(db).TryGet(key[:])
-	if err != nil {
-		s.setError(err)
-		return common.Hash{}
+	// If no live objects are available, attempt to use snapshots
+	var (
+		enc []byte
+		err error
+	)
+	if s.db.snap != nil {
+		if metrics.EnabledExpensive {
+			defer func(start time.Time) { s.db.SnapshotStorageReads += time.Since(start) }(time.Now())
+		}
+		// If the object was destructed in *this* block (and potentially resurrected),
+		// the storage has been cleared out, and we should *not* consult the previous
+		// snapshot about any storage values. The only possible alternatives are:
+		//   1) resurrect happened, and new slot values were set -- those should
+		//      have been handles via pendingStorage above.
+		//   2) we don't have new values, and can deliver empty response back
+		if _, destructed := s.db.snapDestructs[s.addrHash]; destructed {
+			return common.Hash{}
+		}
+		enc, err = s.db.snap.Storage(s.addrHash, crypto.Keccak256Hash(key.Bytes()))
+	}
+	// If snapshot unavailable or reading from it failed, load from the database
+	if s.db.snap == nil || err != nil {
+		if metrics.EnabledExpensive {
+			defer func(start time.Time) { s.db.StorageReads += time.Since(start) }(time.Now())
+		}
+		if enc, err = s.getTrie(db).TryGet(key.Bytes()); err != nil {
+			s.setError(err)
+			return common.Hash{}
+		}
 	}
+	var value common.Hash
 	if len(enc) > 0 {
 		_, content, _, err := rlp.Split(enc)
 		if err != nil {
@@ -253,38 +281,73 @@ func (s *stateObject) setState(key, value common.Hash) {
 	s.dirtyStorage[key] = value
 }
 
+// finalise moves all dirty storage slots into the pending area to be hashed or
+// committed later. It is invoked at the end of every transaction.
+func (s *stateObject) finalise() {
+	for key, value := range s.dirtyStorage {
+		s.pendingStorage[key] = value
+	}
+	if len(s.dirtyStorage) > 0 {
+		s.dirtyStorage = make(Storage)
+	}
+}
+
 // updateTrie writes cached storage modifications into the object's storage trie.
+// It will return nil if the trie has not been loaded and no changes have been made
 func (s *stateObject) updateTrie(db Database) Trie {
+	// Make sure all dirty slots are finalized into the pending storage area
+	s.finalise()
+	if len(s.pendingStorage) == 0 {
+		return s.trie
+	}
 	// Track the amount of time wasted on updating the storge trie
 	if metrics.EnabledExpensive {
 		defer func(start time.Time) { s.db.StorageUpdates += time.Since(start) }(time.Now())
 	}
-	// Update all the dirty slots in the trie
+	// Retrieve the snapshot storage map for the object
+	var storage map[common.Hash][]byte
+	if s.db.snap != nil {
+		// Retrieve the old storage map, if available, create a new one otherwise
+		storage = s.db.snapStorage[s.addrHash]
+		if storage == nil {
+			storage = make(map[common.Hash][]byte)
+			s.db.snapStorage[s.addrHash] = storage
+		}
+	}
+	// Insert all the pending updates into the trie
 	tr := s.getTrie(db)
-	for key, value := range s.dirtyStorage {
-		delete(s.dirtyStorage, key)
-
+	for key, value := range s.pendingStorage {
 		// Skip noop changes, persist actual changes
 		if value == s.originStorage[key] {
 			continue
 		}
 		s.originStorage[key] = value
 
+		var v []byte
 		if (value == common.Hash{}) {
 			s.setError(tr.TryDelete(key[:]))
-			continue
+		} else {
+			// Encoding []byte cannot fail, ok to ignore the error.
+			v, _ = rlp.EncodeToBytes(common.TrimLeftZeroes(value[:]))
+			s.setError(tr.TryUpdate(key[:], v))
+		}
+		// If state snapshotting is active, cache the data til commit
+		if storage != nil {
+			storage[crypto.Keccak256Hash(key[:])] = v // v will be nil if value is 0x00
 		}
-		// Encoding []byte cannot fail, ok to ignore the error.
-		v, _ := rlp.EncodeToBytes(bytes.TrimLeft(value[:], "\x00"))
-		s.setError(tr.TryUpdate(key[:], v))
+	}
+	if len(s.pendingStorage) > 0 {
+		s.pendingStorage = make(Storage)
 	}
 	return tr
 }
 
 // UpdateRoot sets the trie root to the current root hash of
 func (s *stateObject) updateRoot(db Database) {
-	s.updateTrie(db)
-
+	// If nothing changed, don't bother with hashing anything
+	if s.updateTrie(db) == nil {
+		return
+	}
 	// Track the amount of time wasted on hashing the storge trie
 	if metrics.EnabledExpensive {
 		defer func(start time.Time) { s.db.StorageHashes += time.Since(start) }(time.Now())
@@ -295,7 +358,10 @@ func (s *stateObject) updateRoot(db Database) {
 // CommitTrie the storage trie of the object to db.
 // This updates the trie root.
 func (s *stateObject) CommitTrie(db Database) error {
-	s.updateTrie(db)
+	// If nothing changed, don't bother with hashing anything
+	if s.updateTrie(db) == nil {
+		return nil
+	}
 	if s.dbErr != nil {
 		return s.dbErr
 	}
@@ -310,22 +376,21 @@ func (s *stateObject) CommitTrie(db Database) error {
 	return err
 }
 
-// AddBalance removes amount from c's balance.
+// AddBalance adds amount to s's balance.
 // It is used to add funds to the destination account of a transfer.
 func (s *stateObject) AddBalance(amount *big.Int) {
-	// EIP158: We must check emptiness for the objects such that the account
+	// EIP161: We must check emptiness for the objects such that the account
 	// clearing (0,0,0 objects) can take effect.
 	if amount.Sign() == 0 {
 		if s.empty() {
 			s.touch()
 		}
-
 		return
 	}
 	s.SetBalance(new(big.Int).Add(s.Balance(), amount))
 }
 
-// SubBalance removes amount from c's balance.
+// SubBalance removes amount from s's balance.
 // It is used to remove funds from the origin account of a transfer.
 func (s *stateObject) SubBalance(amount *big.Int) {
 	if amount.Sign() == 0 {
@@ -388,6 +453,7 @@ func (s *stateObject) deepCopy(db *StateDB) *stateObject {
 	stateObject.code = s.code
 	stateObject.dirtyStorage = s.dirtyStorage.Copy()
 	stateObject.originStorage = s.originStorage.Copy()
+	stateObject.pendingStorage = s.pendingStorage.Copy()
 	stateObject.suicided = s.suicided
 	stateObject.dirtyCode = s.dirtyCode
 	stateObject.deleted = s.deleted
@@ -419,6 +485,23 @@ func (s *stateObject) Code(db Database) []byte {
 	return code
 }
 
+// CodeSize returns the size of the contract code associated with this object,
+// or zero if none. This method is an almost mirror of Code, but uses a cache
+// inside the database to avoid loading codes seen recently.
+func (s *stateObject) CodeSize(db Database) int {
+	if s.code != nil {
+		return len(s.code)
+	}
+	if bytes.Equal(s.CodeHash(), emptyCodeHash) {
+		return 0
+	}
+	size, err := db.ContractCodeSize(s.addrHash, common.BytesToHash(s.CodeHash()))
+	if err != nil {
+		s.setError(fmt.Errorf("can't load code size %x: %v", s.CodeHash(), err))
+	}
+	return size
+}
+
 func (s *stateObject) SetCode(codeHash common.Hash, code []byte) {
 	prevcode := s.Code(s.db.db)
 	s.db.journal.append(codeChange{
diff --git a/core/state/statedb.go b/core/state/statedb.go
index 9c7535b..805c607 100644
--- a/core/state/statedb.go
+++ b/core/state/statedb.go
@@ -24,13 +24,15 @@ import (
 	"sort"
 	"time"
 
+	"github.com/ava-labs/coreth/core/rawdb"
+	"github.com/ava-labs/coreth/core/state/snapshot"
 	"github.com/ava-labs/coreth/core/types"
-	"github.com/ava-labs/go-ethereum/common"
-	"github.com/ava-labs/go-ethereum/crypto"
-	"github.com/ava-labs/go-ethereum/log"
-	"github.com/ava-labs/go-ethereum/metrics"
-	"github.com/ava-labs/go-ethereum/rlp"
-	"github.com/ava-labs/go-ethereum/trie"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/log"
+	"github.com/ethereum/go-ethereum/metrics"
+	"github.com/ethereum/go-ethereum/rlp"
+	"github.com/ethereum/go-ethereum/trie"
 )
 
 type revision struct {
@@ -42,9 +44,6 @@ var (
 	// emptyRoot is the known root hash of an empty trie.
 	emptyRoot = common.HexToHash("56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421")
 	zeroRoot  = common.HexToHash("0000000000000000000000000000000000000000000000000000000000000000")
-
-	// emptyCode is the known hash of the empty EVM bytecode.
-	emptyCode = crypto.Keccak256Hash(nil)
 )
 
 type proofList [][]byte
@@ -58,7 +57,7 @@ func (n *proofList) Delete(key []byte) error {
 	panic("not supported")
 }
 
-// StateDBs within the ethereum protocol are used to store anything
+// StateDB structs within the ethereum protocol are used to store anything
 // within the merkle trie. StateDBs take care of caching and storing
 // nested states. It's the general query interface to retrieve:
 // * Contracts
@@ -67,9 +66,16 @@ type StateDB struct {
 	db   Database
 	trie Trie
 
+	snaps         *snapshot.Tree
+	snap          snapshot.Snapshot
+	snapDestructs map[common.Hash]struct{}
+	snapAccounts  map[common.Hash][]byte
+	snapStorage   map[common.Hash]map[common.Hash][]byte
+
 	// This map holds 'live' objects, which will get modified while processing a state transition.
-	stateObjects      map[common.Address]*stateObject
-	stateObjectsDirty map[common.Address]struct{}
+	stateObjects        map[common.Address]*stateObject
+	stateObjectsPending map[common.Address]struct{} // State objects finalized but not yet written to the trie
+	stateObjectsDirty   map[common.Address]struct{} // State objects modified in the current execution
 
 	// DB error.
 	// State objects are used by the consensus core and VM which are
@@ -95,134 +101,157 @@ type StateDB struct {
 	nextRevisionId int
 
 	// Measurements gathered during execution for debugging purposes
-	AccountReads   time.Duration
-	AccountHashes  time.Duration
-	AccountUpdates time.Duration
-	AccountCommits time.Duration
-	StorageReads   time.Duration
-	StorageHashes  time.Duration
-	StorageUpdates time.Duration
-	StorageCommits time.Duration
-}
-
-// Create a new state from a given trie.
-func New(root common.Hash, db Database) (*StateDB, error) {
+	AccountReads         time.Duration
+	AccountHashes        time.Duration
+	AccountUpdates       time.Duration
+	AccountCommits       time.Duration
+	StorageReads         time.Duration
+	StorageHashes        time.Duration
+	StorageUpdates       time.Duration
+	StorageCommits       time.Duration
+	SnapshotAccountReads time.Duration
+	SnapshotStorageReads time.Duration
+	SnapshotCommits      time.Duration
+}
+
+// New creates a new state from a given trie.
+func New(root common.Hash, db Database, snaps *snapshot.Tree) (*StateDB, error) {
 	tr, err := db.OpenTrie(root)
 	if err != nil {
 		return nil, err
 	}
-	return &StateDB{
-		db:                db,
-		trie:              tr,
-		stateObjects:      make(map[common.Address]*stateObject),
-		stateObjectsDirty: make(map[common.Address]struct{}),
-		logs:              make(map[common.Hash][]*types.Log),
-		preimages:         make(map[common.Hash][]byte),
-		journal:           newJournal(),
-	}, nil
+	sdb := &StateDB{
+		db:                  db,
+		trie:                tr,
+		snaps:               snaps,
+		stateObjects:        make(map[common.Address]*stateObject),
+		stateObjectsPending: make(map[common.Address]struct{}),
+		stateObjectsDirty:   make(map[common.Address]struct{}),
+		logs:                make(map[common.Hash][]*types.Log),
+		preimages:           make(map[common.Hash][]byte),
+		journal:             newJournal(),
+	}
+	if sdb.snaps != nil {
+		if sdb.snap = sdb.snaps.Snapshot(root); sdb.snap != nil {
+			sdb.snapDestructs = make(map[common.Hash]struct{})
+			sdb.snapAccounts = make(map[common.Hash][]byte)
+			sdb.snapStorage = make(map[common.Hash]map[common.Hash][]byte)
+		}
+	}
+	return sdb, nil
 }
 
 // setError remembers the first non-nil error it is called with.
-func (self *StateDB) setError(err error) {
-	if self.dbErr == nil {
-		self.dbErr = err
+func (s *StateDB) setError(err error) {
+	if s.dbErr == nil {
+		s.dbErr = err
 	}
 }
 
-func (self *StateDB) Error() error {
-	return self.dbErr
+func (s *StateDB) Error() error {
+	return s.dbErr
 }
 
 // Reset clears out all ephemeral state objects from the state db, but keeps
 // the underlying state trie to avoid reloading data for the next operations.
-func (self *StateDB) Reset(root common.Hash) error {
-	tr, err := self.db.OpenTrie(root)
+func (s *StateDB) Reset(root common.Hash) error {
+	tr, err := s.db.OpenTrie(root)
 	if err != nil {
 		return err
 	}
-	self.trie = tr
-	self.stateObjects = make(map[common.Address]*stateObject)
-	self.stateObjectsDirty = make(map[common.Address]struct{})
-	self.thash = common.Hash{}
-	self.bhash = common.Hash{}
-	self.txIndex = 0
-	self.logs = make(map[common.Hash][]*types.Log)
-	self.logSize = 0
-	self.preimages = make(map[common.Hash][]byte)
-	self.clearJournalAndRefund()
+	s.trie = tr
+	s.stateObjects = make(map[common.Address]*stateObject)
+	s.stateObjectsPending = make(map[common.Address]struct{})
+	s.stateObjectsDirty = make(map[common.Address]struct{})
+	s.thash = common.Hash{}
+	s.bhash = common.Hash{}
+	s.txIndex = 0
+	s.logs = make(map[common.Hash][]*types.Log)
+	s.logSize = 0
+	s.preimages = make(map[common.Hash][]byte)
+	s.clearJournalAndRefund()
+
+	if s.snaps != nil {
+		s.snapAccounts, s.snapDestructs, s.snapStorage = nil, nil, nil
+		if s.snap = s.snaps.Snapshot(root); s.snap != nil {
+			s.snapDestructs = make(map[common.Hash]struct{})
+			s.snapAccounts = make(map[common.Hash][]byte)
+			s.snapStorage = make(map[common.Hash]map[common.Hash][]byte)
+		}
+	}
 	return nil
 }
 
-func (self *StateDB) AddLog(log *types.Log) {
-	self.journal.append(addLogChange{txhash: self.thash})
+func (s *StateDB) AddLog(log *types.Log) {
+	s.journal.append(addLogChange{txhash: s.thash})
 
-	log.TxHash = self.thash
-	log.BlockHash = self.bhash
-	log.TxIndex = uint(self.txIndex)
-	log.Index = self.logSize
-	self.logs[self.thash] = append(self.logs[self.thash], log)
-	self.logSize++
+	log.TxHash = s.thash
+	log.BlockHash = s.bhash
+	log.TxIndex = uint(s.txIndex)
+	log.Index = s.logSize
+	s.logs[s.thash] = append(s.logs[s.thash], log)
+	s.logSize++
 }
 
-func (self *StateDB) GetLogs(hash common.Hash) []*types.Log {
-	return self.logs[hash]
+func (s *StateDB) GetLogs(hash common.Hash) []*types.Log {
+	return s.logs[hash]
 }
 
-func (self *StateDB) Logs() []*types.Log {
+func (s *StateDB) Logs() []*types.Log {
 	var logs []*types.Log
-	for _, lgs := range self.logs {
+	for _, lgs := range s.logs {
 		logs = append(logs, lgs...)
 	}
 	return logs
 }
 
 // AddPreimage records a SHA3 preimage seen by the VM.
-func (self *StateDB) AddPreimage(hash common.Hash, preimage []byte) {
-	if _, ok := self.preimages[hash]; !ok {
-		self.journal.append(addPreimageChange{hash: hash})
+func (s *StateDB) AddPreimage(hash common.Hash, preimage []byte) {
+	if _, ok := s.preimages[hash]; !ok {
+		s.journal.append(addPreimageChange{hash: hash})
 		pi := make([]byte, len(preimage))
 		copy(pi, preimage)
-		self.preimages[hash] = pi
+		s.preimages[hash] = pi
 	}
 }
 
 // Preimages returns a list of SHA3 preimages that have been submitted.
-func (self *StateDB) Preimages() map[common.Hash][]byte {
-	return self.preimages
+func (s *StateDB) Preimages() map[common.Hash][]byte {
+	return s.preimages
 }
 
 // AddRefund adds gas to the refund counter
-func (self *StateDB) AddRefund(gas uint64) {
-	self.journal.append(refundChange{prev: self.refund})
-	self.refund += gas
+func (s *StateDB) AddRefund(gas uint64) {
+	s.journal.append(refundChange{prev: s.refund})
+	s.refund += gas
 }
 
 // SubRefund removes gas from the refund counter.
 // This method will panic if the refund counter goes below zero
-func (self *StateDB) SubRefund(gas uint64) {
-	self.journal.append(refundChange{prev: self.refund})
-	if gas > self.refund {
-		panic("Refund counter below zero")
+func (s *StateDB) SubRefund(gas uint64) {
+	s.journal.append(refundChange{prev: s.refund})
+	if gas > s.refund {
+		panic(fmt.Sprintf("Refund counter below zero (gas: %d > refund: %d)", gas, s.refund))
 	}
-	self.refund -= gas
+	s.refund -= gas
 }
 
 // Exist reports whether the given account address exists in the state.
 // Notably this also returns true for suicided accounts.
-func (self *StateDB) Exist(addr common.Address) bool {
-	return self.getStateObject(addr) != nil
+func (s *StateDB) Exist(addr common.Address) bool {
+	return s.getStateObject(addr) != nil
 }
 
 // Empty returns whether the state object is either non-existent
 // or empty according to the EIP161 specification (balance = nonce = code = 0)
-func (self *StateDB) Empty(addr common.Address) bool {
-	so := self.getStateObject(addr)
+func (s *StateDB) Empty(addr common.Address) bool {
+	so := s.getStateObject(addr)
 	return so == nil || so.empty()
 }
 
-// Retrieve the balance from the given address or 0 if object not found
-func (self *StateDB) GetBalance(addr common.Address) *big.Int {
-	stateObject := self.getStateObject(addr)
+// GetBalance retrieves the balance from the given address or 0 if object not found
+func (s *StateDB) GetBalance(addr common.Address) *big.Int {
+	stateObject := s.getStateObject(addr)
 	if stateObject != nil {
 		return stateObject.Balance()
 	}
@@ -262,8 +291,8 @@ func (self *StateDB) IsMultiCoin(addr common.Address) bool {
 	return false
 }
 
-func (self *StateDB) GetNonce(addr common.Address) uint64 {
-	stateObject := self.getStateObject(addr)
+func (s *StateDB) GetNonce(addr common.Address) uint64 {
+	stateObject := s.getStateObject(addr)
 	if stateObject != nil {
 		return stateObject.Nonce()
 	}
@@ -272,40 +301,33 @@ func (self *StateDB) GetNonce(addr common.Address) uint64 {
 }
 
 // TxIndex returns the current transaction index set by Prepare.
-func (self *StateDB) TxIndex() int {
-	return self.txIndex
+func (s *StateDB) TxIndex() int {
+	return s.txIndex
 }
 
 // BlockHash returns the current block hash set by Prepare.
-func (self *StateDB) BlockHash() common.Hash {
-	return self.bhash
+func (s *StateDB) BlockHash() common.Hash {
+	return s.bhash
 }
 
-func (self *StateDB) GetCode(addr common.Address) []byte {
-	stateObject := self.getStateObject(addr)
+func (s *StateDB) GetCode(addr common.Address) []byte {
+	stateObject := s.getStateObject(addr)
 	if stateObject != nil {
-		return stateObject.Code(self.db)
+		return stateObject.Code(s.db)
 	}
 	return nil
 }
 
-func (self *StateDB) GetCodeSize(addr common.Address) int {
-	stateObject := self.getStateObject(addr)
-	if stateObject == nil {
-		return 0
-	}
-	if stateObject.code != nil {
-		return len(stateObject.code)
-	}
-	size, err := self.db.ContractCodeSize(stateObject.addrHash, common.BytesToHash(stateObject.CodeHash()))
-	if err != nil {
-		self.setError(err)
+func (s *StateDB) GetCodeSize(addr common.Address) int {
+	stateObject := s.getStateObject(addr)
+	if stateObject != nil {
+		return stateObject.CodeSize(s.db)
 	}
-	return size
+	return 0
 }
 
-func (self *StateDB) GetCodeHash(addr common.Address) common.Hash {
-	stateObject := self.getStateObject(addr)
+func (s *StateDB) GetCodeHash(addr common.Address) common.Hash {
+	stateObject := s.getStateObject(addr)
 	if stateObject == nil {
 		return common.Hash{}
 	}
@@ -313,25 +335,25 @@ func (self *StateDB) GetCodeHash(addr common.Address) common.Hash {
 }
 
 // GetState retrieves a value from the given account's storage trie.
-func (self *StateDB) GetState(addr common.Address, hash common.Hash) common.Hash {
-	stateObject := self.getStateObject(addr)
+func (s *StateDB) GetState(addr common.Address, hash common.Hash) common.Hash {
+	stateObject := s.getStateObject(addr)
 	if stateObject != nil {
-		return stateObject.GetState(self.db, hash)
+		return stateObject.GetState(s.db, hash)
 	}
 	return common.Hash{}
 }
 
 // GetProof returns the MerkleProof for a given Account
-func (self *StateDB) GetProof(a common.Address) ([][]byte, error) {
+func (s *StateDB) GetProof(a common.Address) ([][]byte, error) {
 	var proof proofList
-	err := self.trie.Prove(crypto.Keccak256(a.Bytes()), 0, &proof)
+	err := s.trie.Prove(crypto.Keccak256(a.Bytes()), 0, &proof)
 	return [][]byte(proof), err
 }
 
-// GetProof returns the StorageProof for given key
-func (self *StateDB) GetStorageProof(a common.Address, key common.Hash) ([][]byte, error) {
+// GetStorageProof returns the StorageProof for given key
+func (s *StateDB) GetStorageProof(a common.Address, key common.Hash) ([][]byte, error) {
 	var proof proofList
-	trie := self.StorageTrie(a)
+	trie := s.StorageTrie(a)
 	if trie == nil {
 		return proof, errors.New("storage trie for requested address does not exist")
 	}
@@ -340,32 +362,33 @@ func (self *StateDB) GetStorageProof(a common.Address, key common.Hash) ([][]byt
 }
 
 // GetCommittedState retrieves a value from the given account's committed storage trie.
-func (self *StateDB) GetCommittedState(addr common.Address, hash common.Hash) common.Hash {
-	stateObject := self.getStateObject(addr)
+func (s *StateDB) GetCommittedState(addr common.Address, hash common.Hash) common.Hash {
+	stateObject := s.getStateObject(addr)
 	if stateObject != nil {
-		return stateObject.GetCommittedState(self.db, hash)
+		return stateObject.GetCommittedState(s.db, hash)
 	}
 	return common.Hash{}
 }
 
 // Database retrieves the low level database supporting the lower level trie ops.
-func (self *StateDB) Database() Database {
-	return self.db
+func (s *StateDB) Database() Database {
+	return s.db
 }
 
 // StorageTrie returns the storage trie of an account.
 // The return value is a copy and is nil for non-existent accounts.
-func (self *StateDB) StorageTrie(addr common.Address) Trie {
-	stateObject := self.getStateObject(addr)
+func (s *StateDB) StorageTrie(addr common.Address) Trie {
+	stateObject := s.getStateObject(addr)
 	if stateObject == nil {
 		return nil
 	}
-	cpy := stateObject.deepCopy(self)
-	return cpy.updateTrie(self.db)
+	cpy := stateObject.deepCopy(s)
+	cpy.updateTrie(s.db)
+	return cpy.getTrie(s.db)
 }
 
-func (self *StateDB) HasSuicided(addr common.Address) bool {
-	stateObject := self.getStateObject(addr)
+func (s *StateDB) HasSuicided(addr common.Address) bool {
+	stateObject := s.getStateObject(addr)
 	if stateObject != nil {
 		return stateObject.suicided
 	}
@@ -377,81 +400,81 @@ func (self *StateDB) HasSuicided(addr common.Address) bool {
  */
 
 // AddBalance adds amount to the account associated with addr.
-func (self *StateDB) AddBalance(addr common.Address, amount *big.Int) {
-	stateObject := self.GetOrNewStateObject(addr)
+func (s *StateDB) AddBalance(addr common.Address, amount *big.Int) {
+	stateObject := s.GetOrNewStateObject(addr)
 	if stateObject != nil {
 		stateObject.AddBalance(amount)
 	}
 }
 
 // SubBalance subtracts amount from the account associated with addr.
-func (self *StateDB) SubBalance(addr common.Address, amount *big.Int) {
-	stateObject := self.GetOrNewStateObject(addr)
+func (s *StateDB) SubBalance(addr common.Address, amount *big.Int) {
+	stateObject := s.GetOrNewStateObject(addr)
 	if stateObject != nil {
 		stateObject.SubBalance(amount)
 	}
 }
 
-func (self *StateDB) SetBalance(addr common.Address, amount *big.Int) {
-	stateObject := self.GetOrNewStateObject(addr)
+func (s *StateDB) SetBalance(addr common.Address, amount *big.Int) {
+	stateObject := s.GetOrNewStateObject(addr)
 	if stateObject != nil {
 		stateObject.SetBalance(amount)
 	}
 }
 
 // AddBalance adds amount to the account associated with addr.
-func (self *StateDB) AddBalanceMultiCoin(addr common.Address, coinID common.Hash, amount *big.Int) {
-	stateObject := self.GetOrNewStateObject(addr)
+func (s *StateDB) AddBalanceMultiCoin(addr common.Address, coinID common.Hash, amount *big.Int) {
+	stateObject := s.GetOrNewStateObject(addr)
 	if stateObject != nil {
-		stateObject.AddBalanceMultiCoin(coinID, amount, self.db)
+		stateObject.AddBalanceMultiCoin(coinID, amount, s.db)
 	}
 }
 
 // SubBalance subtracts amount from the account associated with addr.
-func (self *StateDB) SubBalanceMultiCoin(addr common.Address, coinID common.Hash, amount *big.Int) {
-	stateObject := self.GetOrNewStateObject(addr)
+func (s *StateDB) SubBalanceMultiCoin(addr common.Address, coinID common.Hash, amount *big.Int) {
+	stateObject := s.GetOrNewStateObject(addr)
 	if stateObject != nil {
-		stateObject.SubBalanceMultiCoin(coinID, amount, self.db)
+		stateObject.SubBalanceMultiCoin(coinID, amount, s.db)
 	}
 }
 
-func (self *StateDB) SetBalanceMultiCoin(addr common.Address, coinID common.Hash, amount *big.Int) {
-	stateObject := self.GetOrNewStateObject(addr)
+func (s *StateDB) SetBalanceMultiCoin(addr common.Address, coinID common.Hash, amount *big.Int) {
+	stateObject := s.GetOrNewStateObject(addr)
 	if stateObject != nil {
-		stateObject.SetBalanceMultiCoin(coinID, amount, self.db)
+		stateObject.SetBalanceMultiCoin(coinID, amount, s.db)
 	}
 }
 
-func (self *StateDB) SetNonce(addr common.Address, nonce uint64) {
-	stateObject := self.GetOrNewStateObject(addr)
+func (s *StateDB) SetNonce(addr common.Address, nonce uint64) {
+	stateObject := s.GetOrNewStateObject(addr)
 	if stateObject != nil {
 		stateObject.SetNonce(nonce)
 	}
 }
 
-func (self *StateDB) SetCode(addr common.Address, code []byte) {
-	stateObject := self.GetOrNewStateObject(addr)
+func (s *StateDB) SetCode(addr common.Address, code []byte) {
+	stateObject := s.GetOrNewStateObject(addr)
 	if stateObject != nil {
 		stateObject.SetCode(crypto.Keccak256Hash(code), code)
 	}
 }
 
-func (self *StateDB) SetState(addr common.Address, key, value common.Hash) (res error) {
+func (s *StateDB) SetState(addr common.Address, key, value common.Hash) (res error) {
 	res = nil
-	stateObject := self.GetOrNewStateObject(addr)
+	stateObject := s.GetOrNewStateObject(addr)
 	if stateObject != nil {
 		if stateObject.data.IsMultiCoin {
 			NormalizeStateKey(&key)
 		}
-		stateObject.SetState(self.db, key, value)
+		stateObject.SetState(s.db, key, value)
 	}
 	return
 }
 
 // SetStorage replaces the entire storage for the specified account with given
 // storage. This function should only be used for debugging.
-func (self *StateDB) SetStorage(addr common.Address, storage map[common.Hash]common.Hash) {
-	stateObject := self.GetOrNewStateObject(addr)
+func (s *StateDB) SetStorage(addr common.Address, storage map[common.Hash]common.Hash) {
+	stateObject := s.GetOrNewStateObject(addr)
 	if stateObject != nil {
 		stateObject.SetStorage(storage)
 	}
@@ -462,12 +485,12 @@ func (self *StateDB) SetStorage(addr common.Address, storage map[common.Hash]com
 //
 // The account's state object is still available until the state is committed,
 // getStateObject will return a non-nil account after Suicide.
-func (self *StateDB) Suicide(addr common.Address) bool {
-	stateObject := self.getStateObject(addr)
+func (s *StateDB) Suicide(addr common.Address) bool {
+	stateObject := s.getStateObject(addr)
 	if stateObject == nil {
 		return false
 	}
-	self.journal.append(suicideChange{
+	s.journal.append(suicideChange{
 		account:     &addr,
 		prev:        stateObject.suicided,
 		prevbalance: new(big.Int).Set(stateObject.Balance()),
@@ -483,90 +506,153 @@ func (self *StateDB) Suicide(addr common.Address) bool {
 //
 
 // updateStateObject writes the given object to the trie.
-func (s *StateDB) updateStateObject(stateObject *stateObject) {
+func (s *StateDB) updateStateObject(obj *stateObject) {
 	// Track the amount of time wasted on updating the account from the trie
 	if metrics.EnabledExpensive {
 		defer func(start time.Time) { s.AccountUpdates += time.Since(start) }(time.Now())
 	}
 	// Encode the account and update the account trie
-	addr := stateObject.Address()
+	addr := obj.Address()
 
-	data, err := rlp.EncodeToBytes(stateObject)
+	data, err := rlp.EncodeToBytes(obj)
 	if err != nil {
 		panic(fmt.Errorf("can't encode object at %x: %v", addr[:], err))
 	}
-	s.setError(s.trie.TryUpdate(addr[:], data))
+	if err = s.trie.TryUpdate(addr[:], data); err != nil {
+		s.setError(fmt.Errorf("updateStateObject (%x) error: %v", addr[:], err))
+	}
+
+	// If state snapshotting is active, cache the data til commit. Note, this
+	// update mechanism is not symmetric to the deletion, because whereas it is
+	// enough to track account updates at commit time, deletions need tracking
+	// at transaction boundary level to ensure we capture state clearing.
+	if s.snap != nil {
+		s.snapAccounts[obj.addrHash] = snapshot.SlimAccountRLP(obj.data.Nonce, obj.data.Balance, obj.data.Root, obj.data.CodeHash)
+	}
 }
 
 // deleteStateObject removes the given object from the state trie.
-func (s *StateDB) deleteStateObject(stateObject *stateObject) {
+func (s *StateDB) deleteStateObject(obj *stateObject) {
 	// Track the amount of time wasted on deleting the account from the trie
 	if metrics.EnabledExpensive {
 		defer func(start time.Time) { s.AccountUpdates += time.Since(start) }(time.Now())
 	}
 	// Delete the account from the trie
-	stateObject.deleted = true
+	addr := obj.Address()
+	if err := s.trie.TryDelete(addr[:]); err != nil {
+		s.setError(fmt.Errorf("deleteStateObject (%x) error: %v", addr[:], err))
+	}
+}
 
-	addr := stateObject.Address()
-	s.setError(s.trie.TryDelete(addr[:]))
+// getStateObject retrieves a state object given by the address, returning nil if
+// the object is not found or was deleted in this execution context. If you need
+// to differentiate between non-existent/just-deleted, use getDeletedStateObject.
+func (s *StateDB) getStateObject(addr common.Address) *stateObject {
+	if obj := s.getDeletedStateObject(addr); obj != nil && !obj.deleted {
+		return obj
+	}
+	return nil
 }
 
-// Retrieve a state object given by the address. Returns nil if not found.
-func (s *StateDB) getStateObject(addr common.Address) (stateObject *stateObject) {
-	// Prefer live objects
+// getDeletedStateObject is similar to getStateObject, but instead of returning
+// nil for a deleted state object, it returns the actual object with the deleted
+// flag set. This is needed by the state journal to revert to the correct s-
+// destructed object instead of wiping all knowledge about the state object.
+func (s *StateDB) getDeletedStateObject(addr common.Address) *stateObject {
+	// Prefer live objects if any is available
 	if obj := s.stateObjects[addr]; obj != nil {
-		if obj.deleted {
-			return nil
-		}
 		return obj
 	}
-	// Track the amount of time wasted on loading the object from the database
-	if metrics.EnabledExpensive {
-		defer func(start time.Time) { s.AccountReads += time.Since(start) }(time.Now())
-	}
-	// Load the object from the database
-	enc, err := s.trie.TryGet(addr[:])
-	if len(enc) == 0 {
-		s.setError(err)
-		return nil
+	// If no live objects are available, attempt to use snapshots
+	var (
+		data *Account
+		err  error
+	)
+	if s.snap != nil {
+		if metrics.EnabledExpensive {
+			defer func(start time.Time) { s.SnapshotAccountReads += time.Since(start) }(time.Now())
+		}
+		var acc *snapsh