Eip1283

core/state/state_object.go

@@ -77,7 +77,7 @@ 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
 
-	cachedStorage Storage // Storage entry cache to avoid duplicate reads
+	originStorage Storage // Storage cache of original entries to dedup rewrites
 	dirtyStorage  Storage // Storage entries that need to be flushed to disk
 
 	// Cache flags.
@@ -115,7 +115,7 @@ func newObject(db *StateDB, address common.Address, data Account) *stateObject {
 		address:       address,
 		addrHash:      crypto.Keccak256Hash(address[:]),
 		data:          data,
-		cachedStorage: make(Storage),
+		originStorage: make(Storage),
 		dirtyStorage:  make(Storage),
 	}
 }
@@ -159,13 +159,25 @@ func (c *stateObject) getTrie(db Database) Trie {
 	return c.trie
 }
 
-// GetState returns a value in account storage.
+// GetState retrieves a value from the account storage trie.
 func (self *stateObject) GetState(db Database, key common.Hash) common.Hash {
-	value, exists := self.cachedStorage[key]
-	if exists {
+	// If we have a dirty value for this state entry, return it
+	value, dirty := self.dirtyStorage[key]
+	if dirty {
 		return value
 	}
-	// Load from DB in case it is missing.
+	// Otherwise return the entry's original value
+	return self.GetCommittedState(db, key)
+}
+
+// GetCommittedState retrieves a value from the committed account storage trie.
+func (self *stateObject) GetCommittedState(db Database, key common.Hash) common.Hash {
+	// If we have the original value cached, return that
+	value, cached := self.originStorage[key]
+	if cached {
+		return value
+	}
+	// Otherwise load the value from the database
 	enc, err := self.getTrie(db).TryGet(key[:])
 	if err != nil {
 		self.setError(err)
@@ -178,22 +190,27 @@ func (self *stateObject) GetState(db Database, key common.Hash) common.Hash {
 		}
 		value.SetBytes(content)
 	}
-	self.cachedStorage[key] = value
+	self.originStorage[key] = value
 	return value
 }
 
 // SetState updates a value in account storage.
 func (self *stateObject) SetState(db Database, key, value common.Hash) {
+	// If the new value is the same as old, don't set
+	prev := self.GetState(db, key)
+	if prev == value {
+		return
+	}
+	// New value is different, update and journal the change
 	self.db.journal.append(storageChange{
 		account:  &self.address,
 		key:      key,
-		prevalue: self.GetState(db, key),
+		prevalue: prev,
 	})
 	self.setState(key, value)
 }
 
 func (self *stateObject) setState(key, value common.Hash) {
-	self.cachedStorage[key] = value
 	self.dirtyStorage[key] = value
 }
 
@@ -202,6 +219,13 @@ func (self *stateObject) updateTrie(db Database) Trie {
 	tr := self.getTrie(db)
 	for key, value := range self.dirtyStorage {
 		delete(self.dirtyStorage, key)
+
+		// Skip noop changes, persist actual changes
+		if value == self.originStorage[key] {
+			continue
+		}
+		self.originStorage[key] = value
+
 		if (value == common.Hash{}) {
 			self.setError(tr.TryDelete(key[:]))
 			continue
@@ -279,7 +303,7 @@ func (self *stateObject) deepCopy(db *StateDB) *stateObject {
 	}
 	stateObject.code = self.code
 	stateObject.dirtyStorage = self.dirtyStorage.Copy()
-	stateObject.cachedStorage = self.dirtyStorage.Copy()
+	stateObject.originStorage = self.originStorage.Copy()
 	stateObject.suicided = self.suicided
 	stateObject.dirtyCode = self.dirtyCode
 	stateObject.deleted = self.deleted

core/state/state_test.go

@@ -96,11 +96,15 @@ func (s *StateSuite) TestNull(c *checker.C) {
 	s.state.CreateAccount(address)
 	//value := common.FromHex("0x823140710bf13990e4500136726d8b55")
 	var value common.Hash
+
 	s.state.SetState(address, common.Hash{}, value)
 	s.state.Commit(false)
-	value = s.state.GetState(address, common.Hash{})
-	if value != (common.Hash{}) {
-		c.Errorf("expected empty hash. got %x", value)
+
+	if value := s.state.GetState(address, common.Hash{}); value != (common.Hash{}) {
+		c.Errorf("expected empty current value, got %x", value)
+	}
+	if value := s.state.GetCommittedState(address, common.Hash{}); value != (common.Hash{}) {
+		c.Errorf("expected empty committed value, got %x", value)
 	}
 }
 
@@ -110,20 +114,24 @@ func (s *StateSuite) TestSnapshot(c *checker.C) {
 	data1 := common.BytesToHash([]byte{42})
 	data2 := common.BytesToHash([]byte{43})
 
+	// snapshot the genesis state
+	genesis := s.state.Snapshot()
+
 	// set initial state object value
 	s.state.SetState(stateobjaddr, storageaddr, data1)
-	// get snapshot of current state
 	snapshot := s.state.Snapshot()
 
-	// set new state object value
+	// set a new state object value, revert it and ensure correct content
 	s.state.SetState(stateobjaddr, storageaddr, data2)
-	// restore snapshot
 	s.state.RevertToSnapshot(snapshot)
 
-	// get state storage value
-	res := s.state.GetState(stateobjaddr, storageaddr)
+	c.Assert(s.state.GetState(stateobjaddr, storageaddr), checker.DeepEquals, data1)
+	c.Assert(s.state.GetCommittedState(stateobjaddr, storageaddr), checker.DeepEquals, common.Hash{})
 
-	c.Assert(data1, checker.DeepEquals, res)
+	// revert up to the genesis state and ensure correct content
+	s.state.RevertToSnapshot(genesis)
+	c.Assert(s.state.GetState(stateobjaddr, storageaddr), checker.DeepEquals, common.Hash{})
+	c.Assert(s.state.GetCommittedState(stateobjaddr, storageaddr), checker.DeepEquals, common.Hash{})
 }
 
 func (s *StateSuite) TestSnapshotEmpty(c *checker.C) {
@@ -208,24 +216,30 @@ func compareStateObjects(so0, so1 *stateObject, t *testing.T) {
 		t.Fatalf("Code mismatch: have %v, want %v", so0.code, so1.code)
 	}
 
-	if len(so1.cachedStorage) != len(so0.cachedStorage) {
-		t.Errorf("Storage size mismatch: have %d, want %d", len(so1.cachedStorage), len(so0.cachedStorage))
+	if len(so1.dirtyStorage) != len(so0.dirtyStorage) {
+		t.Errorf("Dirty storage size mismatch: have %d, want %d", len(so1.dirtyStorage), len(so0.dirtyStorage))
 	}
-	for k, v := range so1.cachedStorage {
-		if so0.cachedStorage[k] != v {
-			t.Errorf("Storage key %x mismatch: have %v, want %v", k, so0.cachedStorage[k], v)
+	for k, v := range so1.dirtyStorage {
+		if so0.dirtyStorage[k] != v {
+			t.Errorf("Dirty storage key %x mismatch: have %v, want %v", k, so0.dirtyStorage[k], v)
 		}
 	}
-	for k, v := range so0.cachedStorage {
-		if so1.cachedStorage[k] != v {
-			t.Errorf("Storage key %x mismatch: have %v, want none.", k, v)
+	for k, v := range so0.dirtyStorage {
+		if so1.dirtyStorage[k] != v {
+			t.Errorf("Dirty storage key %x mismatch: have %v, want none.", k, v)
 		}
 	}
-
-	if so0.suicided != so1.suicided {
-		t.Fatalf("suicided mismatch: have %v, want %v", so0.suicided, so1.suicided)
+	if len(so1.originStorage) != len(so0.originStorage) {
+		t.Errorf("Origin storage size mismatch: have %d, want %d", len(so1.originStorage), len(so0.originStorage))
+	}
+	for k, v := range so1.originStorage {
+		if so0.originStorage[k] != v {
+			t.Errorf("Origin storage key %x mismatch: have %v, want %v", k, so0.originStorage[k], v)
+		}
 	}
-	if so0.deleted != so1.deleted {
-		t.Fatalf("Deleted mismatch: have %v, want %v", so0.deleted, so1.deleted)
+	for k, v := range so0.originStorage {
+		if so1.originStorage[k] != v {
+			t.Errorf("Origin storage key %x mismatch: have %v, want none.", k, v)
+		}
 	}
 }

core/state/statedb.go

@@ -169,11 +169,22 @@ func (self *StateDB) Preimages() map[common.Hash][]byte {
 	return self.preimages
 }
 
+// AddRefund adds gas to the refund counter
 func (self *StateDB) AddRefund(gas uint64) {
 	self.journal.append(refundChange{prev: self.refund})
 	self.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")
+	}
+	self.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 {
@@ -236,10 +247,20 @@ func (self *StateDB) GetCodeHash(addr common.Address) common.Hash {
 	return common.BytesToHash(stateObject.CodeHash())
 }
 
-func (self *StateDB) GetState(addr common.Address, bhash common.Hash) 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)
+	if stateObject != nil {
+		return stateObject.GetState(self.db, hash)
+	}
+	return common.Hash{}
+}
+
+// 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)
 	if stateObject != nil {
-		return stateObject.GetState(self.db, bhash)
+		return stateObject.GetCommittedState(self.db, hash)
 	}
 	return common.Hash{}
 }
@@ -435,19 +456,14 @@ func (db *StateDB) ForEachStorage(addr common.Address, cb func(key, value common
 	if so == nil {
 		return
 	}
-
-	// When iterating over the storage check the cache first
-	for h, value := range so.cachedStorage {
-		cb(h, value)
-	}
-
 	it := trie.NewIterator(so.getTrie(db.db).NodeIterator(nil))
 	for it.Next() {
-		// ignore cached values
 		key := common.BytesToHash(db.trie.GetKey(it.Key))
-		if _, ok := so.cachedStorage[key]; !ok {
-			cb(key, common.BytesToHash(it.Value))
+		if value, dirty := so.dirtyStorage[key]; dirty {
+			cb(key, value)
+			continue
 		}
+		cb(key, common.BytesToHash(it.Value))
 	}
 }
 

core/state/statedb_test.go

@@ -381,11 +381,11 @@ func (test *snapshotTest) checkEqual(state, checkstate *StateDB) error {
 		checkeq("GetCodeSize", state.GetCodeSize(addr), checkstate.GetCodeSize(addr))
 		// Check storage.
 		if obj := state.getStateObject(addr); obj != nil {
-			state.ForEachStorage(addr, func(key, val common.Hash) bool {
-				return checkeq("GetState("+key.Hex()+")", val, checkstate.GetState(addr, key))
+			state.ForEachStorage(addr, func(key, value common.Hash) bool {
+				return checkeq("GetState("+key.Hex()+")", checkstate.GetState(addr, key), value)
 			})
-			checkstate.ForEachStorage(addr, func(key, checkval common.Hash) bool {
-				return checkeq("GetState("+key.Hex()+")", state.GetState(addr, key), checkval)
+			checkstate.ForEachStorage(addr, func(key, value common.Hash) bool {
+				return checkeq("GetState("+key.Hex()+")", checkstate.GetState(addr, key), value)
 			})
 		}
 		if err != nil {

core/vm/gas_table.go

@@ -117,24 +117,69 @@ func gasReturnDataCopy(gt params.GasTable, evm *EVM, contract *Contract, stack *
 
 func gasSStore(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
 	var (
-		y, x = stack.Back(1), stack.Back(0)
-		val  = evm.StateDB.GetState(contract.Address(), common.BigToHash(x))
+		y, x    = stack.Back(1), stack.Back(0)
+		current = evm.StateDB.GetState(contract.Address(), common.BigToHash(x))
 	)
-	// This checks for 3 scenario's and calculates gas accordingly
-	// 1. From a zero-value address to a non-zero value         (NEW VALUE)
-	// 2. From a non-zero value address to a zero-value address (DELETE)
-	// 3. From a non-zero to a non-zero                         (CHANGE)
-	if val == (common.Hash{}) && y.Sign() != 0 {
-		// 0 => non 0
-		return params.SstoreSetGas, nil
-	} else if val != (common.Hash{}) && y.Sign() == 0 {
-		// non 0 => 0
-		evm.StateDB.AddRefund(params.SstoreRefundGas)
-		return params.SstoreClearGas, nil
-	} else {
-		// non 0 => non 0 (or 0 => 0)
-		return params.SstoreResetGas, nil
+	// The legacy gas metering only takes into consideration the current state
+	if !evm.chainRules.IsConstantinople {
+		// This checks for 3 scenario's and calculates gas accordingly:
+		//
+		// 1. From a zero-value address to a non-zero value         (NEW VALUE)
+		// 2. From a non-zero value address to a zero-value address (DELETE)
+		// 3. From a non-zero to a non-zero                         (CHANGE)
+		switch {
+		case current == (common.Hash{}) && y.Sign() != 0: // 0 => non 0
+			return params.SstoreSetGas, nil
+		case current != (common.Hash{}) && y.Sign() == 0: // non 0 => 0
+			evm.StateDB.AddRefund(params.SstoreRefundGas)
+			return params.SstoreClearGas, nil
+		default: // non 0 => non 0 (or 0 => 0)
+			return params.SstoreResetGas, nil
+		}
+	}
+	// The new gas metering is based on net gas costs (EIP-1283):
+	//
+	// 1. If current value equals new value (this is a no-op), 200 gas is deducted.
+	// 2. If current value does not equal new value
+	//   2.1. If original value equals current value (this storage slot has not been changed by the current execution context)
+	//     2.1.1. If original value is 0, 20000 gas is deducted.
+	// 	   2.1.2. Otherwise, 5000 gas is deducted. If new value is 0, add 15000 gas to refund counter.
+	// 	2.2. If original value does not equal current value (this storage slot is dirty), 200 gas is deducted. Apply both of the following clauses.
+	// 	  2.2.1. If original value is not 0
+	//       2.2.1.1. If current value is 0 (also means that new value is not 0), remove 15000 gas from refund counter. We can prove that refund counter will never go below 0.
+	//       2.2.1.2. If new value is 0 (also means that current value is not 0), add 15000 gas to refund counter.
+	// 	  2.2.2. If original value equals new value (this storage slot is reset)
+	//       2.2.2.1. If original value is 0, add 19800 gas to refund counter.
+	// 	     2.2.2.2. Otherwise, add 4800 gas to refund counter.
+	value := common.BigToHash(y)
+	if current == value { // noop (1)
+		return params.NetSstoreNoopGas, nil
+	}
+	original := evm.StateDB.GetCommittedState(contract.Address(), common.BigToHash(x))
+	if original == current {
+		if original == (common.Hash{}) { // create slot (2.1.1)
+			return params.NetSstoreInitGas, nil
+		}
+		if value == (common.Hash{}) { // delete slot (2.1.2b)
+			evm.StateDB.AddRefund(params.NetSstoreClearRefund)
+		}
+		return params.NetSstoreCleanGas, nil // write existing slot (2.1.2)
+	}
+	if original != (common.Hash{}) {
+		if current == (common.Hash{}) { // recreate slot (2.2.1.1)
+			evm.StateDB.SubRefund(params.NetSstoreClearRefund)
+		} else if value == (common.Hash{}) { // delete slot (2.2.1.2)
+			evm.StateDB.AddRefund(params.NetSstoreClearRefund)
+		}
+	}
+	if original == value {
+		if original == (common.Hash{}) { // reset to original inexistent slot (2.2.2.1)
+			evm.StateDB.AddRefund(params.NetSstoreResetClearRefund)
+		} else { // reset to original existing slot (2.2.2.2)
+			evm.StateDB.AddRefund(params.NetSstoreResetRefund)
+		}
 	}
+	return params.NetSstoreDirtyGas, nil
 }
 
 func makeGasLog(n uint64) gasFunc {

core/vm/interface.go

@@ -40,8 +40,10 @@ type StateDB interface {
 	GetCodeSize(common.Address) int
 
 	AddRefund(uint64)
+	SubRefund(uint64)
 	GetRefund() uint64
 
+	GetCommittedState(common.Address, common.Hash) common.Hash
 	GetState(common.Address, common.Hash) common.Hash
 	SetState(common.Address, common.Hash, common.Hash)
 

core/vm/logger_test.go

@@ -41,11 +41,6 @@ func (d *dummyContractRef) SetBalance(*big.Int)        {}
 func (d *dummyContractRef) SetNonce(uint64)            {}
 func (d *dummyContractRef) Balance() *big.Int          { return new(big.Int) }
 
-type dummyStateDB struct {
-	NoopStateDB
-	ref *dummyContractRef
-}
-
 func TestStoreCapture(t *testing.T) {
 	var (
 		env      = NewEVM(Context{}, nil, params.TestChainConfig, Config{})