core/state: implement reverts by journaling all changes

This commit replaces the deep-copy based state revert mechanism with a
linear complexity journal. This commit also hides several internal
StateDB methods to limit the number of ways in which calling code can
use the journal incorrectly.

As usual consultation and bug fixes to the initial implementation were
provided by @karalabe, @obscuren and @Arachnid. Thank you!

3 files changed, 26 insertions, 48 deletions

diff --git a/tests/state_test_util.go b/tests/state_test_util.go
index 67e4bf832..3c4b42a18 100644
--- a/tests/state_test_util.go
+++ b/tests/state_test_util.go
@@ -95,14 +95,7 @@ func BenchStateTest(ruleSet RuleSet, p string, conf bconf, b *testing.B) error {
 func benchStateTest(ruleSet RuleSet, test VmTest, env map[string]string, b *testing.B) {
 	b.StopTimer()
 	db, _ := ethdb.NewMemDatabase()
-	statedb, _ := state.New(common.Hash{}, db)
-	for addr, account := range test.Pre {
-		obj := StateObjectFromAccount(db, addr, account, statedb.MarkStateObjectDirty)
-		statedb.SetStateObject(obj)
-		for a, v := range account.Storage {
-			obj.SetState(common.HexToHash(a), common.HexToHash(v))
-		}
-	}
+	statedb := makePreState(db, test.Pre)
 	b.StartTimer()
 
 	RunState(ruleSet, statedb, env, test.Exec)
@@ -134,14 +127,7 @@ func runStateTests(ruleSet RuleSet, tests map[string]VmTest, skipTests []string)
 
 func runStateTest(ruleSet RuleSet, test VmTest) error {
 	db, _ := ethdb.NewMemDatabase()
-	statedb, _ := state.New(common.Hash{}, db)
-	for addr, account := range test.Pre {
-		obj := StateObjectFromAccount(db, addr, account, statedb.MarkStateObjectDirty)
-		statedb.SetStateObject(obj)
-		for a, v := range account.Storage {
-			obj.SetState(common.HexToHash(a), common.HexToHash(v))
-		}
-	}
+	statedb := makePreState(db, test.Pre)
 
 	// XXX Yeah, yeah...
 	env := make(map[string]string)
@@ -227,7 +213,7 @@ func RunState(ruleSet RuleSet, statedb *state.StateDB, env, tx map[string]string
 	}
 	// Set pre compiled contracts
 	vm.Precompiled = vm.PrecompiledContracts()
-	snapshot := statedb.Copy()
+	snapshot := statedb.Snapshot()
 	gaspool := new(core.GasPool).AddGas(common.Big(env["currentGasLimit"]))
 
 	key, _ := hex.DecodeString(tx["secretKey"])
@@ -237,7 +223,7 @@ func RunState(ruleSet RuleSet, statedb *state.StateDB, env, tx map[string]string
 	vmenv.origin = addr
 	ret, _, err := core.ApplyMessage(vmenv, message, gaspool)
 	if core.IsNonceErr(err) || core.IsInvalidTxErr(err) || core.IsGasLimitErr(err) {
-		statedb.Set(snapshot)
+		statedb.RevertToSnapshot(snapshot)
 	}
 	statedb.Commit()
 
diff --git a/tests/util.go b/tests/util.go
index ffbcb9d56..8a9d09213 100644
--- a/tests/util.go
+++ b/tests/util.go
@@ -103,19 +103,25 @@ func (self Log) Topics() [][]byte {
 	return t
 }
 
-func StateObjectFromAccount(db ethdb.Database, addr string, account Account, onDirty func(common.Address)) *state.StateObject {
+func makePreState(db ethdb.Database, accounts map[string]Account) *state.StateDB {
+	statedb, _ := state.New(common.Hash{}, db)
+	for addr, account := range accounts {
+		insertAccount(statedb, addr, account)
+	}
+	return statedb
+}
+
+func insertAccount(state *state.StateDB, saddr string, account Account) {
 	if common.IsHex(account.Code) {
 		account.Code = account.Code[2:]
 	}
-	code := common.Hex2Bytes(account.Code)
-	codeHash := crypto.Keccak256Hash(code)
-	obj := state.NewObject(common.HexToAddress(addr), state.Account{
-		Balance:  common.Big(account.Balance),
-		CodeHash: codeHash[:],
-		Nonce:    common.Big(account.Nonce).Uint64(),
-	}, onDirty)
-	obj.SetCode(codeHash, code)
-	return obj
+	addr := common.HexToAddress(saddr)
+	state.SetCode(addr, common.Hex2Bytes(account.Code))
+	state.SetNonce(addr, common.Big(account.Nonce).Uint64())
+	state.SetBalance(addr, common.Big(account.Balance))
+	for a, v := range account.Storage {
+		state.SetState(addr, common.HexToHash(a), common.HexToHash(v))
+	}
 }
 
 type VmEnv struct {
@@ -229,11 +235,11 @@ func (self *Env) CanTransfer(from common.Address, balance *big.Int) bool {
 
 	return self.state.GetBalance(from).Cmp(balance) >= 0
 }
-func (self *Env) MakeSnapshot() vm.Database {
-	return self.state.Copy()
+func (self *Env) SnapshotDatabase() int {
+	return self.state.Snapshot()
 }
-func (self *Env) SetSnapshot(copy vm.Database) {
-	self.state.Set(copy.(*state.StateDB))
+func (self *Env) RevertToSnapshot(snapshot int) {
+	self.state.RevertToSnapshot(snapshot)
 }
 
 func (self *Env) Transfer(from, to vm.Account, amount *big.Int) {
diff --git a/tests/vm_test_util.go b/tests/vm_test_util.go
index 4ad72d91c..c269f21e0 100644
--- a/tests/vm_test_util.go
+++ b/tests/vm_test_util.go
@@ -101,14 +101,7 @@ func BenchVmTest(p string, conf bconf, b *testing.B) error {
 func benchVmTest(test VmTest, env map[string]string, b *testing.B) {
 	b.StopTimer()
 	db, _ := ethdb.NewMemDatabase()
-	statedb, _ := state.New(common.Hash{}, db)
-	for addr, account := range test.Pre {
-		obj := StateObjectFromAccount(db, addr, account, statedb.MarkStateObjectDirty)
-		statedb.SetStateObject(obj)
-		for a, v := range account.Storage {
-			obj.SetState(common.HexToHash(a), common.HexToHash(v))
-		}
-	}
+	statedb := makePreState(db, test.Pre)
 	b.StartTimer()
 
 	RunVm(statedb, env, test.Exec)
@@ -152,14 +145,7 @@ func runVmTests(tests map[string]VmTest, skipTests []string) error {
 
 func runVmTest(test VmTest) error {
 	db, _ := ethdb.NewMemDatabase()
-	statedb, _ := state.New(common.Hash{}, db)
-	for addr, account := range test.Pre {
-		obj := StateObjectFromAccount(db, addr, account, statedb.MarkStateObjectDirty)
-		statedb.SetStateObject(obj)
-		for a, v := range account.Storage {
-			obj.SetState(common.HexToHash(a), common.HexToHash(v))
-		}
-	}
+	statedb := makePreState(db, test.Pre)
 
 	// XXX Yeah, yeah...
 	env := make(map[string]string)