move state commitment to the state reader

Author: MaksymMalicki

blockchain/blockchain.go

@@ -100,7 +100,7 @@ func (b *Blockchain) Network() *utils.Network {
 func (b *Blockchain) StateCommitment() (felt.Felt, error) {
 	b.listener.OnRead("StateCommitment")
 	batch := b.database.NewIndexedBatch() // this is a hack because we don't need to write to the db
-	return core.NewState(batch).Commitment()
+	return core.NewStateSnapshotReader(batch).Commitment()
 }
 
 // Height returns the latest block height. If blockchain is empty nil is returned.

core/state.go

@@ -65,44 +65,6 @@ func (s *State) putNewContract(
 	return s.updateContractCommitment(contractTrie, contract)
 }
 
-// Root returns the state commitment.
-func (s *State) Commitment() (felt.Felt, error) {
-	var storageRoot, classesRoot felt.Felt
-
-	sStorage, closer, err := contractTrie(s.txn)
-	if err != nil {
-		return felt.Felt{}, err
-	}
-
-	if storageRoot, err = sStorage.Hash(); err != nil {
-		return felt.Felt{}, err
-	}
-
-	if err = closer(); err != nil {
-		return felt.Felt{}, err
-	}
-
-	classes, closer, err := classesTrie(s.txn)
-	if err != nil {
-		return felt.Felt{}, err
-	}
-
-	if classesRoot, err = classes.Hash(); err != nil {
-		return felt.Felt{}, err
-	}
-
-	if err = closer(); err != nil {
-		return felt.Felt{}, err
-	}
-
-	if classesRoot.IsZero() {
-		return storageRoot, nil
-	}
-
-	root := crypto.PoseidonArray(stateVersion, &storageRoot, &classesRoot)
-	return root, nil
-}
-
 func (s *State) verifyStateUpdateRoot(root *felt.Felt) error {
 	currentRoot, err := s.Commitment()
 	if err != nil {

core/state_reader.go

@@ -5,6 +5,7 @@ import (
 	"encoding/binary"
 	"errors"
 
+	"github.com/NethermindEth/juno/core/crypto"
 	"github.com/NethermindEth/juno/core/felt"
 	"github.com/NethermindEth/juno/core/state/commontrie"
 	"github.com/NethermindEth/juno/core/trie"
@@ -47,6 +48,38 @@ func NewStateSnapshotReader(txn db.KeyValueReader) *StateSnapshotReader {
 	}
 }
 
+// Root returns the state commitment.
+func (s *StateSnapshotReader) Commitment() (felt.Felt, error) {
+	var storageRoot, classesRoot felt.Felt
+
+	sStorage, err := contractTrieReader(s.txn)
+	if err != nil {
+		return felt.Felt{}, err
+	}
+
+	storageRoot, err = sStorage.Hash()
+	if err != nil {
+		return felt.Felt{}, err
+	}
+
+	classes, err := classesTrieReader(s.txn)
+	if err != nil {
+		return felt.Felt{}, err
+	}
+
+	classesRoot, err = classes.Hash()
+	if err != nil {
+		return felt.Felt{}, err
+	}
+
+	if classesRoot.IsZero() {
+		return storageRoot, nil
+	}
+
+	root := crypto.PoseidonArray(stateVersion, &storageRoot, &classesRoot)
+	return root, nil
+}
+
 // ContractStorageAt returns the value of a storage location
 // of the given contract at the height `height`
 func (s *StateSnapshotReader) ContractStorageAt(