Pull in logic from merkleeyes, get it all working with trees

stack/checkpoint.go

@@ -0,0 +1,43 @@
+package stack
+
+import (
+	"github.com/tendermint/basecoin"
+	"github.com/tendermint/basecoin/state"
+)
+
+//nolint
+const (
+	NameCheckpoint = "check"
+)
+
+// Checkpoint isolates all data store below this
+type Checkpoint struct {
+	PassOption
+}
+
+// Name of the module - fulfills Middleware interface
+func (Checkpoint) Name() string {
+	return NameCheckpoint
+}
+
+var _ Middleware = Checkpoint{}
+
+// CheckTx reverts all data changes if there was an error
+func (c Checkpoint) CheckTx(ctx basecoin.Context, store state.KVStore, tx basecoin.Tx, next basecoin.Checker) (res basecoin.Result, err error) {
+	ps := state.NewKVCache(unwrap(store))
+	res, err = next.CheckTx(ctx, ps, tx)
+	if err == nil {
+		ps.Sync()
+	}
+	return res, err
+}
+
+// DeliverTx reverts all data changes if there was an error
+func (c Checkpoint) DeliverTx(ctx basecoin.Context, store state.KVStore, tx basecoin.Tx, next basecoin.Deliver) (res basecoin.Result, err error) {
+	ps := state.NewKVCache(unwrap(store))
+	res, err = next.DeliverTx(ctx, ps, tx)
+	if err == nil {
+		ps.Sync()
+	}
+	return res, err
+}

stack/prefixstore.go

@@ -31,6 +31,14 @@ func stateSpace(store state.KVStore, app string) state.KVStore {
 	return PrefixedStore(app, store)
 }
 
+func unwrap(store state.KVStore) state.KVStore {
+	// unwrap one-level if wrapped
+	if pstore, ok := store.(prefixStore); ok {
+		store = pstore.store
+	}
+	return store
+}
+
 // PrefixedStore allows one to create an isolated state-space for a given
 // app prefix, but it cannot easily be unwrapped
 //