6 files changed, 16 insertions, 13 deletions
diff --git a/core/vm/environment.go b/core/vm/environment.go
index daf6fb90d..a4b2ac196 100644
--- a/core/vm/environment.go
+++ b/core/vm/environment.go
@@ -36,9 +36,9 @@ type Environment interface {
 	// The state database
 	Db() Database
 	// Creates a restorable snapshot
-	MakeSnapshot() Database
+	SnapshotDatabase() int
 	// Set database to previous snapshot
-	SetSnapshot(Database)
+	RevertToSnapshot(int)
 	// Address of the original invoker (first occurrence of the VM invoker)
 	Origin() common.Address
 	// The block number this VM is invoked on
@@ -105,9 +105,12 @@ type Database interface {
 	GetState(common.Address, common.Hash) common.Hash
 	SetState(common.Address, common.Hash, common.Hash)
 
-	Delete(common.Address) bool
+	Suicide(common.Address) bool
+	HasSuicided(common.Address) bool
+
+	// Exist reports whether the given account exists in state.
+	// Notably this should also return true for suicided accounts.
 	Exist(common.Address) bool
-	IsDeleted(common.Address) bool
 }
 
 // Account represents a contract or basic ethereum account.
diff --git a/core/vm/instructions.go b/core/vm/instructions.go
index 849a8463c..79aee60d2 100644
--- a/core/vm/instructions.go
+++ b/core/vm/instructions.go
@@ -614,7 +614,7 @@ func opSuicide(instr instruction, pc *uint64, env Environment, contract *Contrac
 	balance := env.Db().GetBalance(contract.Address())
 	env.Db().AddBalance(common.BigToAddress(stack.pop()), balance)
 
-	env.Db().Delete(contract.Address())
+	env.Db().Suicide(contract.Address())
 }
 
 // following functions are used by the instruction jump  table
diff --git a/core/vm/jit.go b/core/vm/jit.go
index 460a68ddd..55d2e0477 100644
--- a/core/vm/jit.go
+++ b/core/vm/jit.go
@@ -425,7 +425,7 @@ func jitCalculateGasAndSize(env Environment, contract *Contract, instr instructi
 		}
 		gas.Set(g)
 	case SUICIDE:
-		if !statedb.IsDeleted(contract.Address()) {
+		if !statedb.HasSuicided(contract.Address()) {
 			statedb.AddRefund(params.SuicideRefundGas)
 		}
 	case MLOAD:
diff --git a/core/vm/jit_test.go b/core/vm/jit_test.go
index e6922aeb7..a6de710e1 100644
--- a/core/vm/jit_test.go
+++ b/core/vm/jit_test.go
@@ -179,8 +179,8 @@ func (self *Env) BlockNumber() *big.Int  { return big.NewInt(0) }
 
 //func (self *Env) PrevHash() []byte      { return self.parent }
 func (self *Env) Coinbase() common.Address { return common.Address{} }
-func (self *Env) MakeSnapshot() Database   { return nil }
-func (self *Env) SetSnapshot(Database)     {}
+func (self *Env) SnapshotDatabase() int    { return 0 }
+func (self *Env) RevertToSnapshot(int)     {}
 func (self *Env) Time() *big.Int           { return big.NewInt(time.Now().Unix()) }
 func (self *Env) Difficulty() *big.Int     { return big.NewInt(0) }
 func (self *Env) Db() Database             { return nil }
diff --git a/core/vm/runtime/env.go b/core/vm/runtime/env.go
index a4793c98f..59fbaa792 100644
--- a/core/vm/runtime/env.go
+++ b/core/vm/runtime/env.go
@@ -86,11 +86,11 @@ func (self *Env) SetDepth(i int) { self.depth = i }
 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/core/vm/vm.go b/core/vm/vm.go
index 5d78b4a2a..033ada21c 100644
--- a/core/vm/vm.go
+++ b/core/vm/vm.go
@@ -303,7 +303,7 @@ func calculateGasAndSize(env Environment, contract *Contract, caller ContractRef
 		}
 		gas.Set(g)
 	case SUICIDE:
-		if !statedb.IsDeleted(contract.Address()) {
+		if !statedb.HasSuicided(contract.Address()) {
 			statedb.AddRefund(params.SuicideRefundGas)
 		}
 	case MLOAD: