core: wrap cached dao properly, don't miss cached data

Fixes #817 where invoked contract missed updated account information because
it got it one layer below cachedDao used to process the block.

pkg/core/blockchain.go

@@ -80,7 +80,7 @@ type Blockchain struct {
 	lock sync.RWMutex
 
 	// Data access object for CRUD operations around storage.
-	dao *dao
+	dao *simpleDao
 
 	// Current index/height of the highest block.
 	// Read access should always be called by BlockHeight().
@@ -154,7 +154,7 @@ func NewBlockchain(s storage.Store, cfg config.ProtocolConfiguration, log *zap.L
 	}
 	bc := &Blockchain{
 		config:        cfg,
-		dao:           newDao(s),
+		dao:           newSimpleDao(s),
 		headersOp:     make(chan headersOpFunc),
 		headersOpDone: make(chan struct{}),
 		stopCh:        make(chan struct{}),
@@ -457,7 +457,7 @@ func (bc *Blockchain) getSystemFeeAmount(h util.Uint256) uint32 {
 // is happening here, quite allot as you can see :). If things are wired together
 // and all tests are in place, we can make a more optimized and cleaner implementation.
 func (bc *Blockchain) storeBlock(block *block.Block) error {
-	cache := newCachedDao(bc.dao.store)
+	cache := newCachedDao(bc.dao)
 	fee := bc.getSystemFeeAmount(block.PrevHash)
 	for _, tx := range block.Transactions {
 		fee += uint32(bc.SystemFee(tx).IntegralValue())
@@ -655,7 +655,7 @@ func (bc *Blockchain) storeBlock(block *block.Block) error {
 				return err
 			}
 		case *transaction.InvocationTX:
-			systemInterop := bc.newInteropContext(trigger.Application, cache.store, block, tx)
+			systemInterop := bc.newInteropContext(trigger.Application, cache, block, tx)
 			v := bc.spawnVMWithInterops(systemInterop)
 			v.SetCheckedHash(tx.VerificationHash().BytesBE())
 			v.LoadScript(t.Script)
@@ -721,7 +721,7 @@ func (bc *Blockchain) storeBlock(block *block.Block) error {
 	defer bc.lock.Unlock()
 
 	if bc.config.SaveStorageBatch {
-		bc.lastBatch = cache.dao.store.GetBatch()
+		bc.lastBatch = cache.dao.GetBatch()
 	}
 
 	_, err := cache.Persist()
@@ -1725,7 +1725,7 @@ func (bc *Blockchain) GetStandByValidators() (keys.PublicKeys, error) {
 // GetValidators returns validators.
 // Golang implementation of GetValidators method in C# (https://github.com/neo-project/neo/blob/c64748ecbac3baeb8045b16af0d518398a6ced24/neo/Persistence/Snapshot.cs#L182)
 func (bc *Blockchain) GetValidators(txes ...*transaction.Transaction) ([]*keys.PublicKey, error) {
-	cache := newCachedDao(bc.dao.store)
+	cache := newCachedDao(bc.dao)
 	if len(txes) > 0 {
 		for _, tx := range txes {
 			// iterate through outputs
@@ -2016,12 +2016,11 @@ func (bc *Blockchain) spawnVMWithInterops(interopCtx *interopContext) *vm.VM {
 }
 
 // GetTestVM returns a VM and a Store setup for a test run of some sort of code.
-func (bc *Blockchain) GetTestVM() (*vm.VM, storage.Store) {
+func (bc *Blockchain) GetTestVM() *vm.VM {
-	tmpStore := storage.NewMemCachedStore(bc.dao.store)
+	systemInterop := bc.newInteropContext(trigger.Application, bc.dao, nil, nil)
-	systemInterop := bc.newInteropContext(trigger.Application, tmpStore, nil, nil)
 	vm := bc.spawnVMWithInterops(systemInterop)
 	vm.SetPriceGetter(getPrice)
-	return vm, tmpStore
+	return vm
 }
 
 // ScriptFromWitness returns verification script for provided witness.
@@ -2106,7 +2105,7 @@ func (bc *Blockchain) verifyTxWitnesses(t *transaction.Transaction, block *block
 	}
 	sort.Slice(hashes, func(i, j int) bool { return hashes[i].Less(hashes[j]) })
 	sort.Slice(witnesses, func(i, j int) bool { return witnesses[i].ScriptHash().Less(witnesses[j].ScriptHash()) })
-	interopCtx := bc.newInteropContext(trigger.Verification, bc.dao.store, block, t)
+	interopCtx := bc.newInteropContext(trigger.Verification, bc.dao, block, t)
 	for i := 0; i < len(hashes); i++ {
 		err := bc.verifyHashAgainstScript(hashes[i], &witnesses[i], t.VerificationHash(), interopCtx, false)
 		if err != nil {
@@ -2126,7 +2125,7 @@ func (bc *Blockchain) verifyHeaderWitnesses(currHeader, prevHeader *block.Header
 	} else {
 		hash = prevHeader.NextConsensus
 	}
-	interopCtx := bc.newInteropContext(trigger.Verification, bc.dao.store, nil, nil)
+	interopCtx := bc.newInteropContext(trigger.Verification, bc.dao, nil, nil)
 	return bc.verifyHashAgainstScript(hash, &currHeader.Script, currHeader.VerificationHash(), interopCtx, true)
 }
 
@@ -2141,6 +2140,6 @@ func (bc *Blockchain) secondsPerBlock() int {
 	return bc.config.SecondsPerBlock
 }
 
-func (bc *Blockchain) newInteropContext(trigger trigger.Type, s storage.Store, block *block.Block, tx *transaction.Transaction) *interopContext {
+func (bc *Blockchain) newInteropContext(trigger trigger.Type, d dao, block *block.Block, tx *transaction.Transaction) *interopContext {
-	return newInteropContext(trigger, bc, s, block, tx, bc.log)
+	return newInteropContext(trigger, bc, d, block, tx, bc.log)
 }

pkg/core/blockchainer.go

@@ -5,7 +5,6 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/core/block"
 	"github.com/nspcc-dev/neo-go/pkg/core/mempool"
 	"github.com/nspcc-dev/neo-go/pkg/core/state"
-	"github.com/nspcc-dev/neo-go/pkg/core/storage"
 	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
 	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
 	"github.com/nspcc-dev/neo-go/pkg/util"
@@ -41,7 +40,7 @@ type Blockchainer interface {
 	GetScriptHashesForVerifying(*transaction.Transaction) ([]util.Uint160, error)
 	GetStorageItem(scripthash util.Uint160, key []byte) *state.StorageItem
 	GetStorageItems(hash util.Uint160) (map[string]*state.StorageItem, error)
-	GetTestVM() (*vm.VM, storage.Store)
+	GetTestVM() *vm.VM
 	GetTransaction(util.Uint256) (*transaction.Transaction, uint32, error)
 	GetUnspentCoinState(util.Uint256) *state.UnspentCoin
 	References(t *transaction.Transaction) ([]transaction.InOut, error)

pkg/core/cacheddao.go

@@ -1,8 +1,9 @@
 package core
 
 import (
+	"errors"
+
 	"github.com/nspcc-dev/neo-go/pkg/core/state"
-	"github.com/nspcc-dev/neo-go/pkg/core/storage"
 	"github.com/nspcc-dev/neo-go/pkg/io"
 	"github.com/nspcc-dev/neo-go/pkg/util"
 )
@@ -20,13 +21,13 @@ type cachedDao struct {
 }
 
 // newCachedDao returns new cachedDao wrapping around given backing store.
-func newCachedDao(backend storage.Store) *cachedDao {
+func newCachedDao(d dao) *cachedDao {
 	accs := make(map[util.Uint160]*state.Account)
 	ctrs := make(map[util.Uint160]*state.Contract)
 	unspents := make(map[util.Uint256]*state.UnspentCoin)
 	balances := make(map[util.Uint160]*state.NEP5Balances)
 	transfers := make(map[util.Uint160]map[uint32]*state.NEP5TransferLog)
-	return &cachedDao{*newDao(backend), accs, ctrs, unspents, balances, transfers}
+	return &cachedDao{d.GetWrapped(), accs, ctrs, unspents, balances, transfers}
 }
 
 // GetAccountStateOrNew retrieves Account from cache or underlying Store
@@ -139,6 +140,24 @@ func (cd *cachedDao) AppendNEP5Transfer(acc util.Uint160, index uint32, tr *stat
 // Persist flushes all the changes made into the (supposedly) persistent
 // underlying store.
 func (cd *cachedDao) Persist() (int, error) {
+	lowerCache, ok := cd.dao.(*cachedDao)
+	// If the lower dao is cachedDao, we only need to flush the MemCached DB.
+	// This actually breaks dao interface incapsulation, but for our current
+	// usage scenario it should be good enough if cd doesn't modify object
+	// caches (accounts/contracts/etc) in any way.
+	if ok {
+		var simpleCache *simpleDao
+		for simpleCache == nil {
+			simpleCache, ok = lowerCache.dao.(*simpleDao)
+			if !ok {
+				lowerCache, ok = cd.dao.(*cachedDao)
+				if !ok {
+					return 0, errors.New("unsupported lower dao")
+				}
+			}
+		}
+		return simpleCache.Persist()
+	}
 	buf := io.NewBufBinWriter()
 
 	for sc := range cd.accounts {
@@ -172,3 +191,13 @@ func (cd *cachedDao) Persist() (int, error) {
 	}
 	return cd.dao.Persist()
 }
+
+func (cd *cachedDao) GetWrapped() dao {
+	return &cachedDao{cd.dao.GetWrapped(),
+		cd.accounts,
+		cd.contracts,
+		cd.unspents,
+		cd.balances,
+		cd.transfers,
+	}
+}

pkg/core/cacheddao_test.go

@@ -8,15 +8,16 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/crypto/hash"
 	"github.com/nspcc-dev/neo-go/pkg/internal/random"
 	"github.com/nspcc-dev/neo-go/pkg/smartcontract"
+	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
 func TestCachedDaoAccounts(t *testing.T) {
 	store := storage.NewMemoryStore()
 	// Persistent DAO to check for backing storage.
-	pdao := newDao(store)
+	pdao := newSimpleDao(store)
 	// Cached DAO.
-	cdao := newCachedDao(store)
+	cdao := newCachedDao(pdao)
 
 	hash := random.Uint160()
 	_, err := cdao.GetAccountState(hash)
@@ -50,7 +51,8 @@ func TestCachedDaoAccounts(t *testing.T) {
 
 func TestCachedDaoContracts(t *testing.T) {
 	store := storage.NewMemoryStore()
-	dao := newCachedDao(store)
+	pdao := newSimpleDao(store)
+	dao := newCachedDao(pdao)
 
 	script := []byte{0xde, 0xad, 0xbe, 0xef}
 	sh := hash.Hash160(script)
@@ -69,7 +71,7 @@ func TestCachedDaoContracts(t *testing.T) {
 
 	_, err = dao.Persist()
 	require.Nil(t, err)
-	dao2 := newCachedDao(store)
+	dao2 := newCachedDao(pdao)
 	cs2, err = dao2.GetContractState(sh)
 	require.Nil(t, err)
 	require.Equal(t, cs, cs2)
@@ -81,3 +83,49 @@ func TestCachedDaoContracts(t *testing.T) {
 	_, err = dao.GetContractState(sh)
 	require.NotNil(t, err)
 }
+
+func TestCachedCachedDao(t *testing.T) {
+	store := storage.NewMemoryStore()
+	// Persistent DAO to check for backing storage.
+	pdao := newSimpleDao(store)
+	assert.NotEqual(t, store, pdao.store)
+	// Cached DAO.
+	cdao := newCachedDao(pdao)
+	cdaoDao := cdao.dao.(*simpleDao)
+	assert.NotEqual(t, store, cdaoDao.store)
+	assert.NotEqual(t, pdao.store, cdaoDao.store)
+
+	// Cached cached DAO.
+	ccdao := newCachedDao(cdao)
+	ccdaoDao := ccdao.dao.(*cachedDao)
+	intDao := ccdaoDao.dao.(*simpleDao)
+	assert.NotEqual(t, store, intDao.store)
+	assert.NotEqual(t, pdao.store, intDao.store)
+	assert.NotEqual(t, cdaoDao.store, intDao.store)
+
+	hash := random.Uint160()
+	key := []byte("qwerty")
+	si := &state.StorageItem{Value: []byte("poiuyt")}
+	require.NoError(t, ccdao.PutStorageItem(hash, key, si))
+	resi := ccdao.GetStorageItem(hash, key)
+	assert.Equal(t, si, resi)
+
+	resi = cdao.GetStorageItem(hash, key)
+	assert.Equal(t, (*state.StorageItem)(nil), resi)
+	resi = pdao.GetStorageItem(hash, key)
+	assert.Equal(t, (*state.StorageItem)(nil), resi)
+
+	cnt, err := ccdao.Persist()
+	assert.NoError(t, err)
+	assert.Equal(t, 1, cnt)
+	resi = cdao.GetStorageItem(hash, key)
+	assert.Equal(t, si, resi)
+	resi = pdao.GetStorageItem(hash, key)
+	assert.Equal(t, (*state.StorageItem)(nil), resi)
+
+	cnt, err = cdao.Persist()
+	assert.NoError(t, err)
+	assert.Equal(t, 1, cnt)
+	resi = pdao.GetStorageItem(hash, key)
+	assert.Equal(t, si, resi)
+}

pkg/core/dao.go

@@ -16,16 +16,80 @@ import (
 )
 
 // dao is a data access object.
-type dao struct {
+type dao interface {
+	AppendNEP5Transfer(acc util.Uint160, index uint32, tr *state.NEP5Transfer) (bool, error)
+	DeleteContractState(hash util.Uint160) error
+	DeleteStorageItem(scripthash util.Uint160, key []byte) error
+	DeleteValidatorState(vs *state.Validator) error
+	GetAccountState(hash util.Uint160) (*state.Account, error)
+	GetAccountStateOrNew(hash util.Uint160) (*state.Account, error)
+	GetAndDecode(entity io.Serializable, key []byte) error
+	GetAppExecResult(hash util.Uint256) (*state.AppExecResult, error)
+	GetAssetState(assetID util.Uint256) (*state.Asset, error)
+	GetBatch() *storage.MemBatch
+	GetBlock(hash util.Uint256) (*block.Block, uint32, error)
+	GetContractState(hash util.Uint160) (*state.Contract, error)
+	GetCurrentBlockHeight() (uint32, error)
+	GetCurrentHeaderHeight() (i uint32, h util.Uint256, err error)
+	GetHeaderHashes() ([]util.Uint256, error)
+	GetNEP5Balances(acc util.Uint160) (*state.NEP5Balances, error)
+	GetNEP5TransferLog(acc util.Uint160, index uint32) (*state.NEP5TransferLog, error)
+	GetStorageItem(scripthash util.Uint160, key []byte) *state.StorageItem
+	GetStorageItems(hash util.Uint160) (map[string]*state.StorageItem, error)
+	GetTransaction(hash util.Uint256) (*transaction.Transaction, uint32, error)
+	GetUnspentCoinState(hash util.Uint256) (*state.UnspentCoin, error)
+	GetValidatorState(publicKey *keys.PublicKey) (*state.Validator, error)
+	GetValidatorStateOrNew(publicKey *keys.PublicKey) (*state.Validator, error)
+	GetValidators() []*state.Validator
+	GetValidatorsCount() (*state.ValidatorsCount, error)
+	GetVersion() (string, error)
+	GetWrapped() dao
+	HasTransaction(hash util.Uint256) bool
+	IsDoubleClaim(claim *transaction.ClaimTX) bool
+	IsDoubleSpend(tx *transaction.Transaction) bool
+	Persist() (int, error)
+	PutAccountState(as *state.Account) error
+	PutAppExecResult(aer *state.AppExecResult) error
+	PutAssetState(as *state.Asset) error
+	PutContractState(cs *state.Contract) error
+	PutCurrentHeader(hashAndIndex []byte) error
+	PutNEP5Balances(acc util.Uint160, bs *state.NEP5Balances) error
+	PutNEP5TransferLog(acc util.Uint160, index uint32, lg *state.NEP5TransferLog) error
+	PutStorageItem(scripthash util.Uint160, key []byte, si *state.StorageItem) error
+	PutUnspentCoinState(hash util.Uint256, ucs *state.UnspentCoin) error
+	PutValidatorState(vs *state.Validator) error
+	PutValidatorsCount(vc *state.ValidatorsCount) error
+	PutVersion(v string) error
+	StoreAsBlock(block *block.Block, sysFee uint32) error
+	StoreAsCurrentBlock(block *block.Block) error
+	StoreAsTransaction(tx *transaction.Transaction, index uint32) error
+	putAccountState(as *state.Account, buf *io.BufBinWriter) error
+	putNEP5Balances(acc util.Uint160, bs *state.NEP5Balances, buf *io.BufBinWriter) error
+	putUnspentCoinState(hash util.Uint256, ucs *state.UnspentCoin, buf *io.BufBinWriter) error
+}
+
+// simpleDao is memCached wrapper around DB, simple dao implementation.
+type simpleDao struct {
 	store *storage.MemCachedStore
 }
 
-func newDao(backend storage.Store) *dao {
+func newSimpleDao(backend storage.Store) *simpleDao {
-	return &dao{store: storage.NewMemCachedStore(backend)}
+	return &simpleDao{store: storage.NewMemCachedStore(backend)}
+}
+
+// GetBatch returns currently accumulated DB changeset.
+func (dao *simpleDao) GetBatch() *storage.MemBatch {
+	return dao.store.GetBatch()
+}
+
+// GetWrapped returns new dao instance with another layer of wrapped
+// MemCachedStore around the current dao store.
+func (dao *simpleDao) GetWrapped() dao {
+	return newSimpleDao(dao.store)
 }
 
 // GetAndDecode performs get operation and decoding with serializable structures.
-func (dao *dao) GetAndDecode(entity io.Serializable, key []byte) error {
+func (dao *simpleDao) GetAndDecode(entity io.Serializable, key []byte) error {
 	entityBytes, err := dao.store.Get(key)
 	if err != nil {
 		return err
@@ -36,12 +100,12 @@ func (dao *dao) GetAndDecode(entity io.Serializable, key []byte) error {
 }
 
 // Put performs put operation with serializable structures.
-func (dao *dao) Put(entity io.Serializable, key []byte) error {
+func (dao *simpleDao) Put(entity io.Serializable, key []byte) error {
 	return dao.putWithBuffer(entity, key, io.NewBufBinWriter())
 }
 
 // putWithBuffer performs put operation using buf as a pre-allocated buffer for serialization.
-func (dao *dao) putWithBuffer(entity io.Serializable, key []byte, buf *io.BufBinWriter) error {
+func (dao *simpleDao) putWithBuffer(entity io.Serializable, key []byte, buf *io.BufBinWriter) error {
 	entity.EncodeBinary(buf.BinWriter)
 	if buf.Err != nil {
 		return buf.Err
@@ -53,7 +117,7 @@ func (dao *dao) putWithBuffer(entity io.Serializable, key []byte, buf *io.BufBin
 
 // GetAccountStateOrNew retrieves Account from temporary or persistent Store
 // or creates a new one if it doesn't exist and persists it.
-func (dao *dao) GetAccountStateOrNew(hash util.Uint160) (*state.Account, error) {
+func (dao *simpleDao) GetAccountStateOrNew(hash util.Uint160) (*state.Account, error) {
 	account, err := dao.GetAccountState(hash)
 	if err != nil {
 		if err != storage.ErrKeyNotFound {
@@ -66,7 +130,7 @@ func (dao *dao) GetAccountStateOrNew(hash util.Uint160) (*state.Account, error)
 
 // GetAccountState returns Account from the given Store if it's
 // present there. Returns nil otherwise.
-func (dao *dao) GetAccountState(hash util.Uint160) (*state.Account, error) {
+func (dao *simpleDao) GetAccountState(hash util.Uint160) (*state.Account, error) {
 	account := &state.Account{}
 	key := storage.AppendPrefix(storage.STAccount, hash.BytesBE())
 	err := dao.GetAndDecode(account, key)
@@ -76,11 +140,11 @@ func (dao *dao) GetAccountState(hash util.Uint160) (*state.Account, error) {
 	return account, err
 }
 
-func (dao *dao) PutAccountState(as *state.Account) error {
+func (dao *simpleDao) PutAccountState(as *state.Account) error {
 	return dao.putAccountState(as, io.NewBufBinWriter())
 }
 
-func (dao *dao) putAccountState(as *state.Account, buf *io.BufBinWriter) error {
+func (dao *simpleDao) putAccountState(as *state.Account, buf *io.BufBinWriter) error {
 	key := storage.AppendPrefix(storage.STAccount, as.ScriptHash.BytesBE())
 	return dao.putWithBuffer(as, key, buf)
 }
@@ -90,7 +154,7 @@ func (dao *dao) putAccountState(as *state.Account, buf *io.BufBinWriter) error {
 // -- start assets.
 
 // GetAssetState returns given asset state as recorded in the given store.
-func (dao *dao) GetAssetState(assetID util.Uint256) (*state.Asset, error) {
+func (dao *simpleDao) GetAssetState(assetID util.Uint256) (*state.Asset, error) {
 	asset := &state.Asset{}
 	key := storage.AppendPrefix(storage.STAsset, assetID.BytesBE())
 	err := dao.GetAndDecode(asset, key)
@@ -104,7 +168,7 @@ func (dao *dao) GetAssetState(assetID util.Uint256) (*state.Asset, error) {
 }
 
 // PutAssetState puts given asset state into the given store.
-func (dao *dao) PutAssetState(as *state.Asset) error {
+func (dao *simpleDao) PutAssetState(as *state.Asset) error {
 	key := storage.AppendPrefix(storage.STAsset, as.ID.BytesBE())
 	return dao.Put(as, key)
 }
@@ -115,7 +179,7 @@ func (dao *dao) PutAssetState(as *state.Asset) error {
 
 // GetContractState returns contract state as recorded in the given
 // store by the given script hash.
-func (dao *dao) GetContractState(hash util.Uint160) (*state.Contract, error) {
+func (dao *simpleDao) GetContractState(hash util.Uint160) (*state.Contract, error) {
 	contract := &state.Contract{}
 	key := storage.AppendPrefix(storage.STContract, hash.BytesBE())
 	err := dao.GetAndDecode(contract, key)
@@ -130,13 +194,13 @@ func (dao *dao) GetContractState(hash util.Uint160) (*state.Contract, error) {
 }
 
 // PutContractState puts given contract state into the given store.
-func (dao *dao) PutContractState(cs *state.Contract) error {
+func (dao *simpleDao) PutContractState(cs *state.Contract) error {
 	key := storage.AppendPrefix(storage.STContract, cs.ScriptHash().BytesBE())
 	return dao.Put(cs, key)
 }
 
 // DeleteContractState deletes given contract state in the given store.
-func (dao *dao) DeleteContractState(hash util.Uint160) error {
+func (dao *simpleDao) DeleteContractState(hash util.Uint160) error {
 	key := storage.AppendPrefix(storage.STContract, hash.BytesBE())
 	return dao.store.Delete(key)
 }
@@ -146,7 +210,7 @@ func (dao *dao) DeleteContractState(hash util.Uint160) error {
 // -- start nep5 balances.
 
 // GetNEP5Balances retrieves nep5 balances from the cache.
-func (dao *dao) GetNEP5Balances(acc util.Uint160) (*state.NEP5Balances, error) {
+func (dao *simpleDao) GetNEP5Balances(acc util.Uint160) (*state.NEP5Balances, error) {
 	key := storage.AppendPrefix(storage.STNEP5Balances, acc.BytesBE())
 	bs := state.NewNEP5Balances()
 	err := dao.GetAndDecode(bs, key)
@@ -157,11 +221,11 @@ func (dao *dao) GetNEP5Balances(acc util.Uint160) (*state.NEP5Balances, error) {
 }
 
 // PutNEP5Balances saves nep5 balances from the cache.
-func (dao *dao) PutNEP5Balances(acc util.Uint160, bs *state.NEP5Balances) error {
+func (dao *simpleDao) PutNEP5Balances(acc util.Uint160, bs *state.NEP5Balances) error {
 	return dao.putNEP5Balances(acc, bs, io.NewBufBinWriter())
 }
 
-func (dao *dao) putNEP5Balances(acc util.Uint160, bs *state.NEP5Balances, buf *io.BufBinWriter) error {
+func (dao *simpleDao) putNEP5Balances(acc util.Uint160, bs *state.NEP5Balances, buf *io.BufBinWriter) error {
 	key := storage.AppendPrefix(storage.STNEP5Balances, acc.BytesBE())
 	return dao.putWithBuffer(bs, key, buf)
 }
@@ -181,7 +245,7 @@ func getNEP5TransferLogKey(acc util.Uint160, index uint32) []byte {
 }
 
 // GetNEP5TransferLog retrieves transfer log from the cache.
-func (dao *dao) GetNEP5TransferLog(acc util.Uint160, index uint32) (*state.NEP5TransferLog, error) {
+func (dao *simpleDao) GetNEP5TransferLog(acc util.Uint160, index uint32) (*state.NEP5TransferLog, error) {
 	key := getNEP5TransferLogKey(acc, index)
 	value, err := dao.store.Get(key)
 	if err != nil {
@@ -194,14 +258,14 @@ func (dao *dao) GetNEP5TransferLog(acc util.Uint160, index uint32) (*state.NEP5T
 }
 
 // PutNEP5TransferLog saves given transfer log in the cache.
-func (dao *dao) PutNEP5TransferLog(acc util.Uint160, index uint32, lg *state.NEP5TransferLog) error {
+func (dao *simpleDao) PutNEP5TransferLog(acc util.Uint160, index uint32, lg *state.NEP5TransferLog) error {
 	key := getNEP5TransferLogKey(acc, index)
 	return dao.store.Put(key, lg.Raw)
 }
 
 // AppendNEP5Transfer appends a single NEP5 transfer to a log.
 // First return value signalizes that log size has exceeded batch size.
-func (dao *dao) AppendNEP5Transfer(acc util.Uint160, index uint32, tr *state.NEP5Transfer) (bool, error) {
+func (dao *simpleDao) AppendNEP5Transfer(acc util.Uint160, index uint32, tr *state.NEP5Transfer) (bool, error) {
 	lg, err := dao.GetNEP5TransferLog(acc, index)
 	if err != nil {
 		if err != storage.ErrKeyNotFound {
@@ -220,7 +284,7 @@ func (dao *dao) AppendNEP5Transfer(acc util.Uint160, index uint32, tr *state.NEP
 // -- start unspent coins.
 
 // GetUnspentCoinState retrieves UnspentCoinState from the given store.
-func (dao *dao) GetUnspentCoinState(hash util.Uint256) (*state.UnspentCoin, error) {
+func (dao *simpleDao) GetUnspentCoinState(hash util.Uint256) (*state.UnspentCoin, error) {
 	unspent := &state.UnspentCoin{}
 	key := storage.AppendPrefix(storage.STCoin, hash.BytesLE())
 	err := dao.GetAndDecode(unspent, key)
@@ -231,11 +295,11 @@ func (dao *dao) GetUnspentCoinState(hash util.Uint256) (*state.UnspentCoin, erro
 }
 
 // PutUnspentCoinState puts given UnspentCoinState into the given store.
-func (dao *dao) PutUnspentCoinState(hash util.Uint256, ucs *state.UnspentCoin) error {
+func (dao *simpleDao) PutUnspentCoinState(hash util.Uint256, ucs *state.UnspentCoin) error {
 	return dao.putUnspentCoinState(hash, ucs, io.NewBufBinWriter())
 }
 
-func (dao *dao) putUnspentCoinState(hash util.Uint256, ucs *state.UnspentCoin, buf *io.BufBinWriter) error {
+func (dao *simpleDao) putUnspentCoinState(hash util.Uint256, ucs *state.UnspentCoin, buf *io.BufBinWriter) error {
 	key := storage.AppendPrefix(storage.STCoin, hash.BytesLE())
 	return dao.putWithBuffer(ucs, key, buf)
 }
@@ -245,7 +309,7 @@ func (dao *dao) putUnspentCoinState(hash util.Uint256, ucs *state.UnspentCoin, b
 // -- start validator.
 
 // GetValidatorStateOrNew gets validator from store or created new one in case of error.
-func (dao *dao) GetValidatorStateOrNew(publicKey *keys.PublicKey) (*state.Validator, error) {
+func (dao *simpleDao) GetValidatorStateOrNew(publicKey *keys.PublicKey) (*state.Validator, error) {
 	validatorState, err := dao.GetValidatorState(publicKey)
 	if err != nil {
 		if err != storage.ErrKeyNotFound {
@@ -258,7 +322,7 @@ func (dao *dao) GetValidatorStateOrNew(publicKey *keys.PublicKey) (*state.Valida
 }
 
 // GetValidators returns all validators from store.
-func (dao *dao) GetValidators() []*state.Validator {
+func (dao *simpleDao) GetValidators() []*state.Validator {
 	var validators []*state.Validator
 	dao.store.Seek(storage.STValidator.Bytes(), func(k, v []byte) {
 		r := io.NewBinReaderFromBuf(v)
@@ -273,7 +337,7 @@ func (dao *dao) GetValidators() []*state.Validator {
 }
 
 // GetValidatorState returns validator by publicKey.
-func (dao *dao) GetValidatorState(publicKey *keys.PublicKey) (*state.Validator, error) {
+func (dao *simpleDao) GetValidatorState(publicKey *keys.PublicKey) (*state.Validator, error) {
 	validatorState := &state.Validator{}
 	key := storage.AppendPrefix(storage.STValidator, publicKey.Bytes())
 	err := dao.GetAndDecode(validatorState, key)
@@ -284,20 +348,20 @@ func (dao *dao) GetValidatorState(publicKey *keys.PublicKey) (*state.Validator,
 }
 
 // PutValidatorState puts given Validator into the given store.
-func (dao *dao) PutValidatorState(vs *state.Validator) error {
+func (dao *simpleDao) PutValidatorState(vs *state.Validator) error {
 	key := storage.AppendPrefix(storage.STValidator, vs.PublicKey.Bytes())
 	return dao.Put(vs, key)
 }
 
 // DeleteValidatorState deletes given Validator into the given store.
-func (dao *dao) DeleteValidatorState(vs *state.Validator) error {
+func (dao *simpleDao) DeleteValidatorState(vs *state.Validator) error {
 	key := storage.AppendPrefix(storage.STValidator, vs.PublicKey.Bytes())
 	return dao.store.Delete(key)
 }
 
 // GetValidatorsCount returns current ValidatorsCount or new one if there is none
 // in the DB.
-func (dao *dao) GetValidatorsCount() (*state.ValidatorsCount, error) {
+func (dao *simpleDao) GetValidatorsCount() (*state.ValidatorsCount, error) {
 	vc := &state.ValidatorsCount{}
 	key := []byte{byte(storage.IXValidatorsCount)}
 	err := dao.GetAndDecode(vc, key)
@@ -308,7 +372,7 @@ func (dao *dao) GetValidatorsCount() (*state.ValidatorsCount, error) {
 }
 
 // PutValidatorsCount put given ValidatorsCount in the store.
-func (dao *dao) PutValidatorsCount(vc *state.ValidatorsCount) error {
+func (dao *simpleDao) PutValidatorsCount(vc *state.ValidatorsCount) error {
 	key := []byte{byte(storage.IXValidatorsCount)}
 	return dao.Put(vc, key)
 }
@@ -319,7 +383,7 @@ func (dao *dao) PutValidatorsCount(vc *state.ValidatorsCount) error {
 
 // GetAppExecResult gets application execution result from the
 // given store.
-func (dao *dao) GetAppExecResult(hash util.Uint256) (*state.AppExecResult, error) {
+func (dao *simpleDao) GetAppExecResult(hash util.Uint256) (*state.AppExecResult, error) {
 	aer := &state.AppExecResult{}
 	key := storage.AppendPrefix(storage.STNotification, hash.BytesBE())
 	err := dao.GetAndDecode(aer, key)
@@ -331,7 +395,7 @@ func (dao *dao) GetAppExecResult(hash util.Uint256) (*state.AppExecResult, error
 
 // PutAppExecResult puts given application execution result into the
 // given store.
-func (dao *dao) PutAppExecResult(aer *state.AppExecResult) error {
+func (dao *simpleDao) PutAppExecResult(aer *state.AppExecResult) error {
 	key := storage.AppendPrefix(storage.STNotification, aer.TxHash.BytesBE())
 	return dao.Put(aer, key)
 }
@@ -341,7 +405,7 @@ func (dao *dao) PutAppExecResult(aer *state.AppExecResult) error {
 // -- start storage item.
 
 // GetStorageItem returns StorageItem if it exists in the given Store.
-func (dao *dao) GetStorageItem(scripthash util.Uint160, key []byte) *state.StorageItem {
+func (dao *simpleDao) GetStorageItem(scripthash util.Uint160, key []byte) *state.StorageItem {
 	b, err := dao.store.Get(makeStorageItemKey(scripthash, key))
 	if err != nil {
 		return nil
@@ -359,18 +423,18 @@ func (dao *dao) GetStorageItem(scripthash util.Uint160, key []byte) *state.Stora
 
 // PutStorageItem puts given StorageItem for given script with given
 // key into the given Store.
-func (dao *dao) PutStorageItem(scripthash util.Uint160, key []byte, si *state.StorageItem) error {
+func (dao *simpleDao) PutStorageItem(scripthash util.Uint160, key []byte, si *state.StorageItem) error {
 	return dao.Put(si, makeStorageItemKey(scripthash, key))
 }
 
 // DeleteStorageItem drops storage item for the given script with the
 // given key from the Store.
-func (dao *dao) DeleteStorageItem(scripthash util.Uint160, key []byte) error {
+func (dao *simpleDao) DeleteStorageItem(scripthash util.Uint160, key []byte) error {
 	return dao.store.Delete(makeStorageItemKey(scripthash, key))
 }
 
 // GetStorageItems returns all storage items for a given scripthash.
-func (dao *dao) GetStorageItems(hash util.Uint160) (map[string]*state.StorageItem, error) {
+func (dao *simpleDao) GetStorageItems(hash util.Uint160) (map[string]*state.StorageItem, error) {
 	var siMap = make(map[string]*state.StorageItem)
 	var err error
 
@@ -406,7 +470,7 @@ func makeStorageItemKey(scripthash util.Uint160, key []byte) []byte {
 // -- other.
 
 // GetBlock returns Block by the given hash if it exists in the store.
-func (dao *dao) GetBlock(hash util.Uint256) (*block.Block, uint32, error) {
+func (dao *simpleDao) GetBlock(hash util.Uint256) (*block.Block, uint32, error) {
 	key := storage.AppendPrefix(storage.DataBlock, hash.BytesLE())
 	b, err := dao.store.Get(key)
 	if err != nil {
@@ -422,14 +486,14 @@ func (dao *dao) GetBlock(hash util.Uint256) (*block.Block, uint32, error) {
 
 // GetVersion attempts to get the current version stored in the
 // underlying Store.
-func (dao *dao) GetVersion() (string, error) {
+func (dao *simpleDao) GetVersion() (string, error) {
 	version, err := dao.store.Get(storage.SYSVersion.Bytes())
 	return string(version), err
 }
 
 // GetCurrentBlockHeight returns the current block height found in the
 // underlying Store.
-func (dao *dao) GetCurrentBlockHeight() (uint32, error) {
+func (dao *simpleDao) GetCurrentBlockHeight() (uint32, error) {
 	b, err := dao.store.Get(storage.SYSCurrentBlock.Bytes())
 	if err != nil {
 		return 0, err
@@ -439,7 +503,7 @@ func (dao *dao) GetCurrentBlockHeight() (uint32, error) {
 
 // GetCurrentHeaderHeight returns the current header height and hash from
 // the underlying Store.
-func (dao *dao) GetCurrentHeaderHeight() (i uint32, h util.Uint256, err error) {
+func (dao *simpleDao) GetCurrentHeaderHeight() (i uint32, h util.Uint256, err error) {
 	var b []byte
 	b, err = dao.store.Get(storage.SYSCurrentHeader.Bytes())
 	if err != nil {
@@ -452,7 +516,7 @@ func (dao *dao) GetCurrentHeaderHeight() (i uint32, h util.Uint256, err error) {
 
 // GetHeaderHashes returns a sorted list of header hashes retrieved from
 // the given underlying Store.
-func (dao *dao) GetHeaderHashes() ([]util.Uint256, error) {
+func (dao *simpleDao) GetHeaderHashes() ([]util.Uint256, error) {
 	hashMap := make(map[uint32][]util.Uint256)
 	dao.store.Seek(storage.IXHeaderHashList.Bytes(), func(k, v []byte) {
 		storedCount := binary.LittleEndian.Uint32(k[1:])
@@ -482,7 +546,7 @@ func (dao *dao) GetHeaderHashes() ([]util.Uint256, error) {
 
 // GetTransaction returns Transaction and its height by the given hash
 // if it exists in the store.
-func (dao *dao) GetTransaction(hash util.Uint256) (*transaction.Transaction, uint32, error) {
+func (dao *simpleDao) GetTransaction(hash util.Uint256) (*transaction.Transaction, uint32, error) {
 	key := storage.AppendPrefix(storage.DataTransaction, hash.BytesLE())
 	b, err := dao.store.Get(key)
 	if err != nil {
@@ -502,12 +566,12 @@ func (dao *dao) GetTransaction(hash util.Uint256) (*transaction.Transaction, uin
 }
 
 // PutVersion stores the given version in the underlying Store.
-func (dao *dao) PutVersion(v string) error {
+func (dao *simpleDao) PutVersion(v string) error {
 	return dao.store.Put(storage.SYSVersion.Bytes(), []byte(v))
 }
 
 // PutCurrentHeader stores current header.
-func (dao *dao) PutCurrentHeader(hashAndIndex []byte) error {
+func (dao *simpleDao) PutCurrentHeader(hashAndIndex []byte) error {
 	return dao.store.Put(storage.SYSCurrentHeader.Bytes(), hashAndIndex)
 }
 
@@ -526,7 +590,7 @@ func read2000Uint256Hashes(b []byte) ([]util.Uint256, error) {
 
 // HasTransaction returns true if the given store contains the given
 // Transaction hash.
-func (dao *dao) HasTransaction(hash util.Uint256) bool {
+func (dao *simpleDao) HasTransaction(hash util.Uint256) bool {
 	key := storage.AppendPrefix(storage.DataTransaction, hash.BytesLE())
 	if _, err := dao.store.Get(key); err == nil {
 		return true
@@ -535,7 +599,7 @@ func (dao *dao) HasTransaction(hash util.Uint256) bool {
 }
 
 // StoreAsBlock stores the given block as DataBlock.
-func (dao *dao) StoreAsBlock(block *block.Block, sysFee uint32) error {
+func (dao *simpleDao) StoreAsBlock(block *block.Block, sysFee uint32) error {
 	var (
 		key = storage.AppendPrefix(storage.DataBlock, block.Hash().BytesLE())
 		buf = io.NewBufBinWriter()
@@ -553,7 +617,7 @@ func (dao *dao) StoreAsBlock(block *block.Block, sysFee uint32) error {
 }
 
 // StoreAsCurrentBlock stores the given block witch prefix SYSCurrentBlock.
-func (dao *dao) StoreAsCurrentBlock(block *block.Block) error {
+func (dao *simpleDao) StoreAsCurrentBlock(block *block.Block) error {
 	buf := io.NewBufBinWriter()
 	h := block.Hash()
 	h.EncodeBinary(buf.BinWriter)
@@ -562,7 +626,7 @@ func (dao *dao) StoreAsCurrentBlock(block *block.Block) error {
 }
 
 // StoreAsTransaction stores the given TX as DataTransaction.
-func (dao *dao) StoreAsTransaction(tx *transaction.Transaction, index uint32) error {
+func (dao *simpleDao) StoreAsTransaction(tx *transaction.Transaction, index uint32) error {
 	key := storage.AppendPrefix(storage.DataTransaction, tx.Hash().BytesLE())
 	buf := io.NewBufBinWriter()
 	buf.WriteU32LE(index)
@@ -574,16 +638,16 @@ func (dao *dao) StoreAsTransaction(tx *transaction.Transaction, index uint32) er
 }
 
 // IsDoubleSpend verifies that the input transactions are not double spent.
-func (dao *dao) IsDoubleSpend(tx *transaction.Transaction) bool {
+func (dao *simpleDao) IsDoubleSpend(tx *transaction.Transaction) bool {
 	return dao.checkUsedInputs(tx.Inputs, state.CoinSpent)
 }
 
 // IsDoubleClaim verifies that given claim inputs are not already claimed by another tx.
-func (dao *dao) IsDoubleClaim(claim *transaction.ClaimTX) bool {
+func (dao *simpleDao) IsDoubleClaim(claim *transaction.ClaimTX) bool {
 	return dao.checkUsedInputs(claim.Claims, state.CoinClaimed)
 }
 
-func (dao *dao) checkUsedInputs(inputs []transaction.Input, coin state.Coin) bool {
+func (dao *simpleDao) checkUsedInputs(inputs []transaction.Input, coin state.Coin) bool {
 	if len(inputs) == 0 {
 		return false
 	}
@@ -604,6 +668,6 @@ func (dao *dao) checkUsedInputs(inputs []transaction.Input, coin state.Coin) boo
 
 // Persist flushes all the changes made into the (supposedly) persistent
 // underlying store.
-func (dao *dao) Persist() (int, error) {
+func (dao *simpleDao) Persist() (int, error) {
 	return dao.store.Persist()
 }

pkg/core/dao_test.go

@@ -16,7 +16,7 @@ import (
 )
 
 func TestPutGetAndDecode(t *testing.T) {
-	dao := newDao(storage.NewMemoryStore())
+	dao := newSimpleDao(storage.NewMemoryStore())
 	serializable := &TestSerializable{field: random.String(4)}
 	hash := []byte{1}
 	err := dao.Put(serializable, hash)
@@ -41,7 +41,7 @@ func (t *TestSerializable) DecodeBinary(reader *io.BinReader) {
 }
 
 func TestGetAccountStateOrNew_New(t *testing.T) {
-	dao := newDao(storage.NewMemoryStore())
+	dao := newSimpleDao(storage.NewMemoryStore())
 	hash := random.Uint160()
 	createdAccount, err := dao.GetAccountStateOrNew(hash)
 	require.NoError(t, err)
@@ -49,7 +49,7 @@ func TestGetAccountStateOrNew_New(t *testing.T) {
 }
 
 func TestPutAndGetAccountStateOrNew(t *testing.T) {
-	dao := newDao(storage.NewMemoryStore())
+	dao := newSimpleDao(storage.NewMemoryStore())
 	hash := random.Uint160()
 	accountState := &state.Account{ScriptHash: hash}
 	err := dao.PutAccountState(accountState)
@@ -60,7 +60,7 @@ func TestPutAndGetAccountStateOrNew(t *testing.T) {
 }
 
 func TestPutAndGetAssetState(t *testing.T) {
-	dao := newDao(storage.NewMemoryStore())
+	dao := newSimpleDao(storage.NewMemoryStore())
 	id := random.Uint256()
 	assetState := &state.Asset{ID: id, Owner: keys.PublicKey{}}
 	err := dao.PutAssetState(assetState)
@@ -71,7 +71,7 @@ func TestPutAndGetAssetState(t *testing.T) {
 }
 
 func TestPutAndGetContractState(t *testing.T) {
-	dao := newDao(storage.NewMemoryStore())
+	dao := newSimpleDao(storage.NewMemoryStore())
 	contractState := &state.Contract{Script: []byte{}, ParamList: []smartcontract.ParamType{}}
 	hash := contractState.ScriptHash()
 	err := dao.PutContractState(contractState)
@@ -82,7 +82,7 @@ func TestPutAndGetContractState(t *testing.T) {
 }
 
 func TestDeleteContractState(t *testing.T) {
-	dao := newDao(storage.NewMemoryStore())
+	dao := newSimpleDao(storage.NewMemoryStore())
 	contractState := &state.Contract{Script: []byte{}, ParamList: []smartcontract.ParamType{}}
 	hash := contractState.ScriptHash()
 	err := dao.PutContractState(contractState)
@@ -95,7 +95,7 @@ func TestDeleteContractState(t *testing.T) {
 }
 
 func TestGetUnspentCoinState_Err(t *testing.T) {
-	dao := newDao(storage.NewMemoryStore())
+	dao := newSimpleDao(storage.NewMemoryStore())
 	hash := random.Uint256()
 	gotUnspentCoinState, err := dao.GetUnspentCoinState(hash)
 	require.Error(t, err)
@@ -103,7 +103,7 @@ func TestGetUnspentCoinState_Err(t *testing.T) {
 }
 
 func TestPutGetUnspentCoinState(t *testing.T) {
-	dao := newDao(storage.NewMemoryStore())
+	dao := newSimpleDao(storage.NewMemoryStore())
 	hash := random.Uint256()
 	unspentCoinState := &state.UnspentCoin{Height: 42, States: []state.OutputState{}}
 	err := dao.PutUnspentCoinState(hash, unspentCoinState)
@@ -114,7 +114,7 @@ func TestPutGetUnspentCoinState(t *testing.T) {
 }
 
 func TestGetValidatorStateOrNew_New(t *testing.T) {
-	dao := newDao(storage.NewMemoryStore())
+	dao := newSimpleDao(storage.NewMemoryStore())
 	publicKey := &keys.PublicKey{}
 	validatorState, err := dao.GetValidatorStateOrNew(publicKey)
 	require.NoError(t, err)
@@ -122,7 +122,7 @@ func TestGetValidatorStateOrNew_New(t *testing.T) {
 }
 
 func TestPutGetValidatorState(t *testing.T) {
-	dao := newDao(storage.NewMemoryStore())
+	dao := newSimpleDao(storage.NewMemoryStore())
 	publicKey := &keys.PublicKey{}
 	validatorState := &state.Validator{
 		PublicKey:  publicKey,
@@ -137,7 +137,7 @@ func TestPutGetValidatorState(t *testing.T) {
 }
 
 func TestDeleteValidatorState(t *testing.T) {
-	dao := newDao(storage.NewMemoryStore())
+	dao := newSimpleDao(storage.NewMemoryStore())
 	publicKey := &keys.PublicKey{}
 	validatorState := &state.Validator{
 		PublicKey:  publicKey,
@@ -154,7 +154,7 @@ func TestDeleteValidatorState(t *testing.T) {
 }
 
 func TestGetValidators(t *testing.T) {
-	dao := newDao(storage.NewMemoryStore())
+	dao := newSimpleDao(storage.NewMemoryStore())
 	publicKey := &keys.PublicKey{}
 	validatorState := &state.Validator{
 		PublicKey:  publicKey,
@@ -169,7 +169,7 @@ func TestGetValidators(t *testing.T) {
 }
 
 func TestPutGetAppExecResult(t *testing.T) {
-	dao := newDao(storage.NewMemoryStore())
+	dao := newSimpleDao(storage.NewMemoryStore())
 	hash := random.Uint256()
 	appExecResult := &state.AppExecResult{
 		TxHash: hash,
@@ -184,7 +184,7 @@ func TestPutGetAppExecResult(t *testing.T) {
 }
 
 func TestPutGetStorageItem(t *testing.T) {
-	dao := newDao(storage.NewMemoryStore())
+	dao := newSimpleDao(storage.NewMemoryStore())
 	hash := random.Uint160()
 	key := []byte{0}
 	storageItem := &state.StorageItem{Value: []uint8{}}
@@ -195,7 +195,7 @@ func TestPutGetStorageItem(t *testing.T) {
 }
 
 func TestDeleteStorageItem(t *testing.T) {
-	dao := newDao(storage.NewMemoryStore())
+	dao := newSimpleDao(storage.NewMemoryStore())
 	hash := random.Uint160()
 	key := []byte{0}
 	storageItem := &state.StorageItem{Value: []uint8{}}
@@ -208,7 +208,7 @@ func TestDeleteStorageItem(t *testing.T) {
 }
 
 func TestGetBlock_NotExists(t *testing.T) {
-	dao := newDao(storage.NewMemoryStore())
+	dao := newSimpleDao(storage.NewMemoryStore())
 	hash := random.Uint256()
 	block, _, err := dao.GetBlock(hash)
 	require.Error(t, err)
@@ -216,7 +216,7 @@ func TestGetBlock_NotExists(t *testing.T) {
 }
 
 func TestPutGetBlock(t *testing.T) {
-	dao := newDao(storage.NewMemoryStore())
+	dao := newSimpleDao(storage.NewMemoryStore())
 	b := &block.Block{
 		Base: block.Base{
 			Script: transaction.Witness{
@@ -235,14 +235,14 @@ func TestPutGetBlock(t *testing.T) {
 }
 
 func TestGetVersion_NoVersion(t *testing.T) {
-	dao := newDao(storage.NewMemoryStore())
+	dao := newSimpleDao(storage.NewMemoryStore())
 	version, err := dao.GetVersion()
 	require.Error(t, err)
 	require.Equal(t, "", version)
 }
 
 func TestGetVersion(t *testing.T) {
-	dao := newDao(storage.NewMemoryStore())
+	dao := newSimpleDao(storage.NewMemoryStore())
 	err := dao.PutVersion("testVersion")
 	require.NoError(t, err)
 	version, err := dao.GetVersion()
@@ -251,14 +251,14 @@ func TestGetVersion(t *testing.T) {
 }
 
 func TestGetCurrentHeaderHeight_NoHeader(t *testing.T) {
-	dao := newDao(storage.NewMemoryStore())
+	dao := newSimpleDao(storage.NewMemoryStore())
 	height, err := dao.GetCurrentBlockHeight()
 	require.Error(t, err)
 	require.Equal(t, uint32(0), height)
 }
 
 func TestGetCurrentHeaderHeight_Store(t *testing.T) {
-	dao := newDao(storage.NewMemoryStore())
+	dao := newSimpleDao(storage.NewMemoryStore())
 	b := &block.Block{
 		Base: block.Base{
 			Script: transaction.Witness{
@@ -275,7 +275,7 @@ func TestGetCurrentHeaderHeight_Store(t *testing.T) {
 }
 
 func TestStoreAsTransaction(t *testing.T) {
-	dao := newDao(storage.NewMemoryStore())
+	dao := newSimpleDao(storage.NewMemoryStore())
 	tx := &transaction.Transaction{Type: transaction.IssueType, Data: &transaction.IssueTX{}}
 	hash := tx.Hash()
 	err := dao.StoreAsTransaction(tx, 0)

pkg/core/gas_price_test.go

@@ -15,7 +15,8 @@ import (
 func TestGetPrice(t *testing.T) {
 	bc := newTestChain(t)
 	defer bc.Close()
-	systemInterop := bc.newInteropContext(trigger.Application, storage.NewMemoryStore(), nil, nil)
+	sdao := newSimpleDao(storage.NewMemoryStore())
+	systemInterop := bc.newInteropContext(trigger.Application, sdao, nil, nil)
 
 	v := bc.spawnVMWithInterops(systemInterop)
 	v.SetPriceGetter(getPrice)

pkg/core/interop_neo_test.go

@@ -123,7 +123,7 @@ func TestHeaderGetVersion_Negative(t *testing.T) {
 	block := newDumbBlock()
 	chain := newTestChain(t)
 	defer chain.Close()
-	context := chain.newInteropContext(trigger.Application, storage.NewMemoryStore(), block, nil)
+	context := chain.newInteropContext(trigger.Application, newSimpleDao(storage.NewMemoryStore()), block, nil)
 	v.Estack().PushVal(vm.NewBoolItem(false))
 
 	err := context.headerGetVersion(v)
@@ -219,7 +219,7 @@ func TestWitnessGetVerificationScript(t *testing.T) {
 	chain := newTestChain(t)
 	defer chain.Close()
 
-	context := chain.newInteropContext(trigger.Application, storage.NewMemoryStore(), nil, nil)
+	context := chain.newInteropContext(trigger.Application, newSimpleDao(storage.NewMemoryStore()), nil, nil)
 	v.Estack().PushVal(vm.NewInteropItem(&witness))
 	err := context.witnessGetVerificationScript(v)
 	require.NoError(t, err)
@@ -462,7 +462,7 @@ func createVMAndPushBlock(t *testing.T) (*vm.VM, *block.Block, *interopContext,
 	v := vm.New()
 	block := newDumbBlock()
 	chain := newTestChain(t)
-	context := chain.newInteropContext(trigger.Application, storage.NewMemoryStore(), block, nil)
+	context := chain.newInteropContext(trigger.Application, newSimpleDao(storage.NewMemoryStore()), block, nil)
 	v.Estack().PushVal(vm.NewInteropItem(block))
 	return v, block, context, chain
 }
@@ -492,7 +492,7 @@ func createVMAndAssetState(t *testing.T) (*vm.VM, *state.Asset, *interopContext,
 	}
 
 	chain := newTestChain(t)
-	context := chain.newInteropContext(trigger.Application, storage.NewMemoryStore(), nil, nil)
+	context := chain.newInteropContext(trigger.Application, newSimpleDao(storage.NewMemoryStore()), nil, nil)
 	return v, assetState, context, chain
 }
 
@@ -511,7 +511,7 @@ func createVMAndContractState(t *testing.T) (*vm.VM, *state.Contract, *interopCo
 	}
 
 	chain := newTestChain(t)
-	context := chain.newInteropContext(trigger.Application, storage.NewMemoryStore(), nil, nil)
+	context := chain.newInteropContext(trigger.Application, newSimpleDao(storage.NewMemoryStore()), nil, nil)
 	return v, contractState, context, chain
 }
 
@@ -526,7 +526,7 @@ func createVMAndAccState(t *testing.T) (*vm.VM, *state.Account, *interopContext,
 
 	require.NoError(t, err)
 	chain := newTestChain(t)
-	context := chain.newInteropContext(trigger.Application, storage.NewMemoryStore(), nil, nil)
+	context := chain.newInteropContext(trigger.Application, newSimpleDao(storage.NewMemoryStore()), nil, nil)
 	return v, accountState, context, chain
 }
 
@@ -557,6 +557,6 @@ func createVMAndTX(t *testing.T) (*vm.VM, *transaction.Transaction, *interopCont
 	tx.Inputs = inputs
 	tx.Outputs = outputs
 	chain := newTestChain(t)
-	context := chain.newInteropContext(trigger.Application, storage.NewMemoryStore(), nil, tx)
+	context := chain.newInteropContext(trigger.Application, newSimpleDao(storage.NewMemoryStore()), nil, tx)
 	return v, tx, context, chain
 }

pkg/core/interops.go

@@ -12,7 +12,6 @@ import (
 
 	"github.com/nspcc-dev/neo-go/pkg/core/block"
 	"github.com/nspcc-dev/neo-go/pkg/core/state"
-	"github.com/nspcc-dev/neo-go/pkg/core/storage"
 	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
 	"github.com/nspcc-dev/neo-go/pkg/smartcontract/trigger"
 	"github.com/nspcc-dev/neo-go/pkg/vm"
@@ -29,8 +28,8 @@ type interopContext struct {
 	log           *zap.Logger
 }
 
-func newInteropContext(trigger trigger.Type, bc Blockchainer, s storage.Store, block *block.Block, tx *transaction.Transaction, log *zap.Logger) *interopContext {
+func newInteropContext(trigger trigger.Type, bc Blockchainer, d dao, block *block.Block, tx *transaction.Transaction, log *zap.Logger) *interopContext {
-	dao := newCachedDao(s)
+	dao := newCachedDao(d)
 	nes := make([]state.NotificationEvent, 0)
 	return &interopContext{bc, trigger, block, tx, dao, nes, log}
 }

pkg/core/interops_test.go

@@ -16,7 +16,7 @@ func testNonInterop(t *testing.T, value interface{}, f func(*interopContext, *vm
 	v.Estack().PushVal(value)
 	chain := newTestChain(t)
 	defer chain.Close()
-	context := chain.newInteropContext(trigger.Application, storage.NewMemoryStore(), nil, nil)
+	context := chain.newInteropContext(trigger.Application, newSimpleDao(storage.NewMemoryStore()), nil, nil)
 	require.Error(t, f(context, v))
 }
 

pkg/network/helper_test.go

@@ -11,7 +11,6 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/core/block"
 	"github.com/nspcc-dev/neo-go/pkg/core/mempool"
 	"github.com/nspcc-dev/neo-go/pkg/core/state"
-	"github.com/nspcc-dev/neo-go/pkg/core/storage"
 	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
 	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
 	"github.com/nspcc-dev/neo-go/pkg/io"
@@ -109,7 +108,7 @@ func (chain testChain) GetScriptHashesForVerifying(*transaction.Transaction) ([]
 func (chain testChain) GetStorageItem(scripthash util.Uint160, key []byte) *state.StorageItem {
 	panic("TODO")
 }
-func (chain testChain) GetTestVM() (*vm.VM, storage.Store) {
+func (chain testChain) GetTestVM() *vm.VM {
 	panic("TODO")
 }
 func (chain testChain) GetStorageItems(hash util.Uint160) (map[string]*state.StorageItem, error) {

pkg/rpc/server/server.go

@@ -881,7 +881,7 @@ func (s *Server) invokescript(reqParams request.Params) (interface{}, error) {
 // runScriptInVM runs given script in a new test VM and returns the invocation
 // result.
 func (s *Server) runScriptInVM(script []byte) *result.Invoke {
-	vm, _ := s.chain.GetTestVM()
+	vm := s.chain.GetTestVM()
 	vm.SetGasLimit(s.config.MaxGasInvoke)
 	vm.LoadScript(script)
 	_ = vm.Run()