storage: completely remove MemoryBatch

If you need something like that, just wrap another MemCachedStore layer around
it.

pkg/core/blockchain.go

@@ -532,23 +532,17 @@ func (bc *Blockchain) jumpToStateInternal(p uint32, stage stateJumpStage) error
 
 		fallthrough
 	case newStorageItemsAdded:
-		b := bc.dao.Store.Batch()
+		cache := bc.dao.GetWrapped().(*dao.Simple)
 		prefix := statesync.TemporaryPrefix(bc.dao.Version.StoragePrefix)
 		bc.dao.Store.Seek(storage.SeekRange{Prefix: []byte{byte(prefix)}}, func(k, _ []byte) bool {
 			// #1468, but don't need to copy here, because it is done by Store.
-			b.Delete(k)
+			_ = cache.Store.Delete(k)
 			return true
 		})
 
-		err := bc.dao.Store.PutBatch(b)
-		if err != nil {
-			return fmt.Errorf("failed to remove old storage items: %w", err)
-		}
-
 		// After current state is updated, we need to remove outdated state-related data if so.
 		// The only outdated data we might have is genesis-related data, so check it.
 		if p-bc.config.MaxTraceableBlocks > 0 {
-			cache := bc.dao.GetWrapped().(*dao.Simple)
 			writeBuf.Reset()
 			err := cache.DeleteBlock(bc.headerHashes[0], writeBuf)
 			if err != nil {
@@ -561,14 +555,11 @@ func (bc *Blockchain) jumpToStateInternal(p uint32, stage stateJumpStage) error
 					return true
 				})
 			}
-			_, err = cache.Persist()
-			if err != nil {
-				return fmt.Errorf("failed to drop genesis block state: %w", err)
 		}
-		}
-		err = bc.dao.Store.Put(jumpStageKey, []byte{byte(genesisStateRemoved)})
+		_ = cache.Store.Put(jumpStageKey, []byte{byte(genesisStateRemoved)})
+		_, err := cache.Persist()
 		if err != nil {
-			return fmt.Errorf("failed to store state jump stage: %w", err)
+			return fmt.Errorf("failed to persist old items removal: %w", err)
 		}
 	case genesisStateRemoved:
 		// there's nothing to do after that, so just continue with common operations
@@ -933,7 +924,7 @@ func (bc *Blockchain) AddHeaders(headers ...*block.Header) error {
 func (bc *Blockchain) addHeaders(verify bool, headers ...*block.Header) error {
 	var (
 		start = time.Now()
-		batch = bc.dao.Store.Batch()
+		batch = bc.dao.GetWrapped().(*dao.Simple)
 		err   error
 	)
 
@@ -982,7 +973,7 @@ func (bc *Blockchain) addHeaders(verify bool, headers ...*block.Header) error {
 		}
 
 		key := storage.AppendPrefix(storage.DataExecutable, h.Hash().BytesBE())
-		batch.Put(key, buf.Bytes())
+		_ = batch.Store.Put(key, buf.Bytes())
 		buf.Reset()
 		lastHeader = h
 	}
@@ -995,13 +986,13 @@ func (bc *Blockchain) addHeaders(verify bool, headers ...*block.Header) error {
 			}
 
 			key := storage.AppendPrefixInt(storage.IXHeaderHashList, int(bc.storedHeaderCount))
-			batch.Put(key, buf.Bytes())
+			_ = batch.Store.Put(key, buf.Bytes())
 			bc.storedHeaderCount += headerBatchCount
 		}
 
-		batch.Put(storage.SYSCurrentHeader.Bytes(), hashAndIndexToBytes(lastHeader.Hash(), lastHeader.Index))
+		_ = batch.Store.Put(storage.SYSCurrentHeader.Bytes(), hashAndIndexToBytes(lastHeader.Hash(), lastHeader.Index))
 		updateHeaderHeightMetric(len(bc.headerHashes) - 1)
-		if err = bc.dao.Store.PutBatch(batch); err != nil {
+		if _, err = batch.Persist(); err != nil {
 			return err
 		}
 		bc.log.Debug("done processing headers",

pkg/core/blockchain_test.go

@@ -1846,7 +1846,7 @@ func TestBlockchain_InitWithIncompleteStateJump(t *testing.T) {
 	require.NoError(t, bcSpout.AddHeaders(&b.Header))
 
 	// put storage items with STTemp prefix
-	batch := bcSpout.dao.Store.Batch()
+	batch := storage.NewMemCachedStore(bcSpout.dao.Store)
 	tempPrefix := storage.STTempStorage
 	if bcSpout.dao.Version.StoragePrefix == tempPrefix {
 		tempPrefix = storage.STStorage
@@ -1855,10 +1855,11 @@ func TestBlockchain_InitWithIncompleteStateJump(t *testing.T) {
 		key := slice.Copy(k)
 		key[0] = byte(tempPrefix)
 		value := slice.Copy(v)
-		batch.Put(key, value)
+		_ = batch.Put(key, value)
 		return true
 	})
-	require.NoError(t, bcSpout.dao.Store.PutBatch(batch))
+	_, err := batch.Persist()
+	require.NoError(t, err)
 
 	checkNewBlockchainErr := func(t *testing.T, cfg func(c *config.Config), store storage.Store, shouldFail bool) {
 		unitTestNetCfg, err := config.Load("../../config", testchain.Network())

pkg/core/dao/dao.go

@@ -665,9 +665,9 @@ func (dao *Simple) StoreAsBlock(block *block.Block, aer1 *state.AppExecResult, a
 	return dao.Store.Put(key, buf.Bytes())
 }
 
-// DeleteBlock removes block from dao.
+// DeleteBlock removes block from dao. It's not atomic, so make sure you're
+// using private MemCached instance here.
 func (dao *Simple) DeleteBlock(h util.Uint256, w *io.BufBinWriter) error {
-	batch := dao.Store.Batch()
 	key := make([]byte, util.Uint256Size+1)
 	key[0] = byte(storage.DataExecutable)
 	copy(key[1:], h.BytesBE())
@@ -694,21 +694,21 @@ func (dao *Simple) DeleteBlock(h util.Uint256, w *io.BufBinWriter) error {
 	if w.Err != nil {
 		return w.Err
 	}
-	batch.Put(key, w.Bytes())
+	_ = dao.Store.Put(key, w.Bytes())
 
 	for _, tx := range b.Transactions {
 		copy(key[1:], tx.Hash().BytesBE())
-		batch.Delete(key)
+		_ = dao.Store.Delete(key)
 		if dao.Version.P2PSigExtensions {
 			for _, attr := range tx.GetAttributes(transaction.ConflictsT) {
 				hash := attr.Value.(*transaction.Conflicts).Hash
 				copy(key[1:], hash.BytesBE())
-				batch.Delete(key)
+				_ = dao.Store.Delete(key)
 			}
 		}
 	}
 
-	return dao.Store.PutBatch(batch)
+	return nil
 }
 
 // StoreAsCurrentBlock stores a hash of the given block with prefix

pkg/core/stateroot/module.go

@@ -146,13 +146,13 @@ func (s *Module) CleanStorage() error {
 	if s.localHeight.Load() != 0 {
 		return fmt.Errorf("can't clean MPT data for non-genesis block: expected local stateroot height 0, got %d", s.localHeight.Load())
 	}
-	b := s.Store.Batch()
+	b := storage.NewMemCachedStore(s.Store)
 	s.Store.Seek(storage.SeekRange{Prefix: []byte{byte(storage.DataMPT)}}, func(k, _ []byte) bool {
 		// #1468, but don't need to copy here, because it is done by Store.
-		b.Delete(k)
+		_ = b.Delete(k)
 		return true
 	})
-	err := s.Store.PutBatch(b)
+	_, err := b.Persist()
 	if err != nil {
 		return fmt.Errorf("failed to remove outdated MPT-reated items: %w", err)
 	}

pkg/core/storage/memcached_store_test.go

@@ -263,18 +263,10 @@ func newMemCachedStoreForTesting(t testing.TB) Store {
 	return NewMemCachedStore(NewMemoryStore())
 }
 
-type BadBatch struct{}
-
-func (b BadBatch) Delete(k []byte) {}
-func (b BadBatch) Put(k, v []byte) {}
-
 type BadStore struct {
 	onPutBatch func()
 }
 
-func (b *BadStore) Batch() Batch {
-	return BadBatch{}
-}
 func (b *BadStore) Delete(k []byte) error {
 	return nil
 }
@@ -284,9 +276,6 @@ func (b *BadStore) Get([]byte) ([]byte, error) {
 func (b *BadStore) Put(k, v []byte) error {
 	return nil
 }
-func (b *BadStore) PutBatch(Batch) error {
-	return nil
-}
 func (b *BadStore) PutChangeSet(_ map[string][]byte, _ map[string][]byte) error {
 	b.onPutBatch()
 	return ErrKeyNotFound

pkg/core/storage/memory_store.go

@@ -17,21 +17,6 @@ type MemoryStore struct {
 	stor map[string][]byte
 }
 
-// MemoryBatch is an in-memory batch compatible with MemoryStore.
-type MemoryBatch struct {
-	MemoryStore
-}
-
-// Put implements the Batch interface.
-func (b *MemoryBatch) Put(k, v []byte) {
-	put(b.MemoryStore.chooseMap(k), string(k), slice.Copy(v))
-}
-
-// Delete implements Batch interface.
-func (b *MemoryBatch) Delete(k []byte) {
-	drop(b.MemoryStore.chooseMap(k), string(k))
-}
-
 // NewMemoryStore creates a new MemoryStore object.
 func NewMemoryStore() *MemoryStore {
 	return &MemoryStore{
@@ -91,12 +76,6 @@ func (s *MemoryStore) Delete(key []byte) error {
 	return nil
 }
 
-// PutBatch implements the Store interface. Never returns an error.
-func (s *MemoryStore) PutBatch(batch Batch) error {
-	b := batch.(*MemoryBatch)
-	return s.PutChangeSet(b.mem, b.stor)
-}
-
 // PutChangeSet implements the Store interface. Never returns an error.
 func (s *MemoryStore) PutChangeSet(puts map[string][]byte, stores map[string][]byte) error {
 	s.mut.Lock()
@@ -187,16 +166,6 @@ func (s *MemoryStore) seek(rng SeekRange, f func(k, v []byte) bool) {
 	}
 }
 
-// Batch implements the Batch interface and returns a compatible Batch.
-func (s *MemoryStore) Batch() Batch {
-	return newMemoryBatch()
-}
-
-// newMemoryBatch returns new memory batch.
-func newMemoryBatch() *MemoryBatch {
-	return &MemoryBatch{MemoryStore: *NewMemoryStore()}
-}
-
 // Close implements Store interface and clears up memory. Never returns an
 // error.
 func (s *MemoryStore) Close() error {

pkg/core/storage/store.go

@@ -103,15 +103,6 @@ type (
 		Close() error
 	}
 
-	// Batch represents an abstraction on top of batch operations.
-	// Each Store implementation is responsible of casting a Batch
-	// to its appropriate type. Batches can only be used in a single
-	// thread.
-	Batch interface {
-		Delete(k []byte)
-		Put(k, v []byte)
-	}
-
 	// KeyPrefix is a constant byte added as a prefix for each key
 	// stored.
 	KeyPrefix uint8