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, 3 insertions, 3 deletions

diff --git a/miner/worker.go b/miner/worker.go
index ac1ef5ba3..e5348cef4 100644
--- a/miner/worker.go
+++ b/miner/worker.go
@@ -171,7 +171,7 @@ func (self *worker) pending() (*types.Block, *state.StateDB) {
 			self.current.receipts,
 		), self.current.state
 	}
-	return self.current.Block, self.current.state
+	return self.current.Block, self.current.state.Copy()
 }
 
 func (self *worker) start() {
@@ -618,7 +618,7 @@ func (env *Work) commitTransactions(mux *event.TypeMux, txs *types.TransactionsB
 }
 
 func (env *Work) commitTransaction(tx *types.Transaction, bc *core.BlockChain, gp *core.GasPool) (error, vm.Logs) {
-	snap := env.state.Copy()
+	snap := env.state.Snapshot()
 
 	// this is a bit of a hack to force jit for the miners
 	config := env.config.VmConfig
@@ -629,7 +629,7 @@ func (env *Work) commitTransaction(tx *types.Transaction, bc *core.BlockChain, g
 
 	receipt, logs, _, err := core.ApplyTransaction(env.config, bc, gp, env.state, env.header, tx, env.header.GasUsed, config)
 	if err != nil {
-		env.state.Set(snap)
+		env.state.RevertToSnapshot(snap)
 		return err, nil
 	}
 	env.txs = append(env.txs, tx)