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!

1 files changed, 16 insertions, 16 deletions

diff --git a/cmd/evm/main.go b/cmd/evm/main.go
index 09ade1577..22707c1cc 100644
--- a/cmd/evm/main.go
+++ b/cmd/evm/main.go
@@ -227,22 +227,22 @@ type ruleSet struct{}
 
 func (ruleSet) IsHomestead(*big.Int) bool { return true }
 
-func (self *VMEnv) RuleSet() vm.RuleSet        { return ruleSet{} }
-func (self *VMEnv) Vm() vm.Vm                  { return self.evm }
-func (self *VMEnv) Db() vm.Database            { return self.state }
-func (self *VMEnv) MakeSnapshot() vm.Database  { return self.state.Copy() }
-func (self *VMEnv) SetSnapshot(db vm.Database) { self.state.Set(db.(*state.StateDB)) }
-func (self *VMEnv) Origin() common.Address     { return *self.transactor }
-func (self *VMEnv) BlockNumber() *big.Int      { return common.Big0 }
-func (self *VMEnv) Coinbase() common.Address   { return *self.transactor }
-func (self *VMEnv) Time() *big.Int             { return self.time }
-func (self *VMEnv) Difficulty() *big.Int       { return common.Big1 }
-func (self *VMEnv) BlockHash() []byte          { return make([]byte, 32) }
-func (self *VMEnv) Value() *big.Int            { return self.value }
-func (self *VMEnv) GasLimit() *big.Int         { return big.NewInt(1000000000) }
-func (self *VMEnv) VmType() vm.Type            { return vm.StdVmTy }
-func (self *VMEnv) Depth() int                 { return 0 }
-func (self *VMEnv) SetDepth(i int)             { self.depth = i }
+func (self *VMEnv) RuleSet() vm.RuleSet       { return ruleSet{} }
+func (self *VMEnv) Vm() vm.Vm                 { return self.evm }
+func (self *VMEnv) Db() vm.Database           { return self.state }
+func (self *VMEnv) SnapshotDatabase() int     { return self.state.Snapshot() }
+func (self *VMEnv) RevertToSnapshot(snap int) { self.state.RevertToSnapshot(snap) }
+func (self *VMEnv) Origin() common.Address    { return *self.transactor }
+func (self *VMEnv) BlockNumber() *big.Int     { return common.Big0 }
+func (self *VMEnv) Coinbase() common.Address  { return *self.transactor }
+func (self *VMEnv) Time() *big.Int            { return self.time }
+func (self *VMEnv) Difficulty() *big.Int      { return common.Big1 }
+func (self *VMEnv) BlockHash() []byte         { return make([]byte, 32) }
+func (self *VMEnv) Value() *big.Int           { return self.value }
+func (self *VMEnv) GasLimit() *big.Int        { return big.NewInt(1000000000) }
+func (self *VMEnv) VmType() vm.Type           { return vm.StdVmTy }
+func (self *VMEnv) Depth() int                { return 0 }
+func (self *VMEnv) SetDepth(i int)            { self.depth = i }
 func (self *VMEnv) GetHash(n uint64) common.Hash {
 	if self.block.Number().Cmp(big.NewInt(int64(n))) == 0 {
 		return self.block.Hash()