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, 4 insertions, 2 deletions

diff --git a/accounts/abi/bind/backends/simulated.go b/accounts/abi/bind/backends/simulated.go
index 7e09abb11..74203a468 100644
--- a/accounts/abi/bind/backends/simulated.go
+++ b/accounts/abi/bind/backends/simulated.go
@@ -172,8 +172,9 @@ func (b *SimulatedBackend) CallContract(ctx context.Context, call ethereum.CallM
 func (b *SimulatedBackend) PendingCallContract(ctx context.Context, call ethereum.CallMsg) ([]byte, error) {
 	b.mu.Lock()
 	defer b.mu.Unlock()
+	defer b.pendingState.RevertToSnapshot(b.pendingState.Snapshot())
 
-	rval, _, err := b.callContract(ctx, call, b.pendingBlock, b.pendingState.Copy())
+	rval, _, err := b.callContract(ctx, call, b.pendingBlock, b.pendingState)
 	return rval, err
 }
 
@@ -197,8 +198,9 @@ func (b *SimulatedBackend) SuggestGasPrice(ctx context.Context) (*big.Int, error
 func (b *SimulatedBackend) EstimateGas(ctx context.Context, call ethereum.CallMsg) (*big.Int, error) {
 	b.mu.Lock()
 	defer b.mu.Unlock()
+	defer b.pendingState.RevertToSnapshot(b.pendingState.Snapshot())
 
-	_, gas, err := b.callContract(ctx, call, b.pendingBlock, b.pendingState.Copy())
+	_, gas, err := b.callContract(ctx, call, b.pendingBlock, b.pendingState)
 	return gas, err
 }