geth state/trie 관련 코드

type stateObject struct {
	address  common.Address
	addrHash common.Hash // hash of ethereum address of the account
	data     Account
	db       *StateDB

	dbErr error

	// Write caches.
	trie Trie // storage trie, which becomes non-nil on first access
	code Code // contract bytecode, which gets set when code is loaded

	originStorage Storage // Storage cache of original entries to dedup rewrites
	dirtyStorage  Storage // Storage entries that need to be flushed to disk

	// Cache flags.
	// When an object is marked suicided it will be delete from the trie
	// during the "update" phase of the state transition.
	dirtyCode bool // true if the code was updated
	suicided  bool
	deleted   bool
}

• SetState시 value에 변화가 있으면, storagChange를 journal에 저장하고, dirtyStorage에도 반영한다.

• updateRoot()는 updateTrie를 통해 originStorag에 수정사항을 반영하고
Root를 재계산한다.(trie.Hash())

// updateTrie writes cached storage modifications into the object's storage trie.
func (s *stateObject) updateTrie(db Database) Trie {
	// Track the amount of time wasted on updating the storge trie
	if metrics.EnabledExpensive {
		defer func(start time.Time) { s.db.StorageUpdates += time.Since(start) }(time.Now())
	}
	// Update all the dirty slots in the trie
	tr := s.getTrie(db)
	for key, value := range s.dirtyStorage {
		delete(s.dirtyStorage, key)

		// Skip noop changes, persist actual changes
		if value == s.originStorage[key] {
			continue
		}
		s.originStorage[key] = value

		if (value == common.Hash{}) {
			s.setError(tr.TryDelete(key[:]))
			continue
		}
		// Encoding []byte cannot fail, ok to ignore the error.
		v, _ := rlp.EncodeToBytes(bytes.TrimLeft(value[:], "\x00"))
		s.setError(tr.TryUpdate(key[:], v))
	}
	return tr
}

// UpdateRoot sets the trie root to the current root hash of
func (s *stateObject) updateRoot(db Database) {
	s.updateTrie(db)

	// Track the amount of time wasted on hashing the storge trie
	if metrics.EnabledExpensive {
		defer func(start time.Time) { s.db.StorageHashes += time.Since(start) }(time.Now())
	}
	s.data.Root = s.trie.Hash()
}

type Account struct {
	Nonce    uint64
	Balance  *big.Int
	Root     common.Hash // merkle root of the storage trie
	CodeHash []byte
}

• CommitTrie를 하면 updateTrie를 통해 db에 수정된 storage trie(아래코드중 trie)가 저장된다.