add a way to cleanup snaps on state

core/state/statedb.go

@@ -180,6 +180,11 @@ func (s *StateDB) GetWitness()  *trienode.Witness {
 	return s.trie.GetWitness()
 }
 
+func (s *StateDB) CleanSnaps() {
+	s.snaps = nil
+	s.snap = nil
+}
+
 // StartPrefetcher initializes a new trie prefetcher to pull in nodes from the
 // state trie concurrently while the state is mutated so that when we reach the
 // commit phase, most of the needed data is already hot.

internal/ethapi/api.go

@@ -972,6 +972,7 @@ func (s *BlockChainAPI) GetRequiredBlockState(ctx context.Context, blockNrOrHash
 	if err != nil {
 		return nil, nil
 	}
+	state.CleanSnaps()
 	s.ProcessBlock(ctx, block, state, vm.Config{})
 	return state.GetWitness(), nil
 	// return s.traceBlock(ctx, block)

trie/trienode/witness.go

@@ -32,13 +32,20 @@ type Witness struct {
 }
 
 func (u *Witness) MarshalJSON() ([]byte, error) {
-	nodes := make(map[string]string)
+	type Node struct {
+		Key   string
+		Value string
+	}
+	nodes := []Node{}
 	for key, node := range u.Nodes {
-		nodes[key] = hex.EncodeToString(node)
+		nodes = append(nodes, Node{
+			Key:   hex.EncodeToString([]byte(key)),
+			Value: hex.EncodeToString(node),
+		})
 	}
 	return json.Marshal(&struct {
 		Owner common.Hash
-		Nodes map[string]string
+		Nodes []Node
 	}{
 		Owner: u.Owner,
 		Nodes: nodes,