Log class hash history

core/history.go

@@ -111,3 +111,25 @@ func (h *History) ContractNonceAt(contractAddress *felt.Felt, height uint64) (*f
 
 	return new(felt.Felt).SetBytes(value), nil
 }
+
+func classHashLogKey(contractAddress *felt.Felt) []byte {
+	return db.ContractClassHashHistory.Key(contractAddress.Marshal())
+}
+
+func (h *History) LogContractClassHash(contractAddress, oldValue *felt.Felt, height uint64) error {
+	return h.logOldValue(classHashLogKey(contractAddress), oldValue.Marshal(), height)
+}
+
+func (h *History) DeleteContractClassHashLog(contractAddress *felt.Felt, height uint64) error {
+	return h.deleteLog(classHashLogKey(contractAddress), height)
+}
+
+func (h *History) ContractClassHashAt(contractAddress *felt.Felt, height uint64) (*felt.Felt, error) {
+	key := classHashLogKey(contractAddress)
+	value, err := h.valueAt(key, height)
+	if err != nil {
+		return nil, err
+	}
+
+	return new(felt.Felt).SetBytes(value), nil
+}

core/state.go

@@ -26,7 +26,7 @@ type StateHistoryReader interface {
 
 	ContractStorageAt(addr, key *felt.Felt, blockNumber uint64) (*felt.Felt, error)
 	ContractNonceAt(addr *felt.Felt, blockNumber uint64) (*felt.Felt, error)
-	// todo: extend
+	ContractClassHashAt(addr *felt.Felt, blockNumber uint64) (*felt.Felt, error)
 }
 
 type StateReader interface {
@@ -222,7 +222,12 @@ func (s *State) updateContracts(blockNumber uint64, diff *StateDiff) error {
 
 	// replace contract instances
 	for _, replace := range diff.ReplacedClasses {
-		if err := s.replaceContract(replace.Address, replace.ClassHash); err != nil {
+		oldClassHash, err := s.replaceContract(replace.Address, replace.ClassHash)
+		if err != nil {
+			return err
+		}
+
+		if err = s.LogContractClassHash(replace.Address, oldClassHash, blockNumber); err != nil {
 			return err
 		}
 	}
@@ -254,17 +259,26 @@ func (s *State) updateContracts(blockNumber uint64, diff *StateDiff) error {
 }
 
 // replaceContract replaces the class that a contract at a given address instantiates
-func (s *State) replaceContract(addr, classHash *felt.Felt) error {
+func (s *State) replaceContract(addr, classHash *felt.Felt) (*felt.Felt, error) {
 	contract, err := NewContract(addr, s.txn)
 	if err != nil {
-		return err
+		return nil, err
+	}
+
+	oldClassHash, err := contract.ClassHash()
+	if err != nil {
+		return nil, err
 	}
 
 	if err = contract.Replace(classHash); err != nil {
-		return err
+		return nil, err
 	}
 
-	return s.updateContractCommitment(contract)
+	if err = s.updateContractCommitment(contract); err != nil {
+		return nil, err
+	}
+
+	return oldClassHash, nil
 }
 
 func (s *State) putClass(classHash *felt.Felt, class Class) error {

db/buckets.go

@@ -24,6 +24,7 @@ const (
 	ClassesTrie
 	ContractStorageHistory
 	ContractNonceHistory
+	ContractClassHashHistory
 )
 
 // Key flattens a prefix and series of byte arrays into a single []byte.