[workingset] value in cache takes precedence

Author: dustinxie

db/kvstorewithbuffer.go

@@ -8,6 +8,7 @@ import (
 	"github.com/pkg/errors"
 
 	"github.com/iotexproject/iotex-core/v2/db/batch"
+	"github.com/iotexproject/iotex-core/v2/pkg/lifecycle"
 	"github.com/iotexproject/iotex-core/v2/pkg/log"
 )
 
@@ -23,7 +24,12 @@ type (
 	// KVStoreWithBuffer defines a KVStore with a buffer, which enables snapshot, revert,
 	// and transaction with multiple writes
 	KVStoreWithBuffer interface {
-		KVStore
+		lifecycle.StartStopper
+		Put(string, []byte, []byte) error
+		Get(string, []byte) ([]byte, bool, error)
+		Delete(string, []byte) error
+		WriteBatch(batch.KVStoreBatch) error
+		Filter(string, Condition, []byte, []byte) ([][]byte, [][]byte, error)
 		withBuffer
 	}
 
@@ -165,15 +171,18 @@ func (kvb *kvStoreWithBuffer) Size() int {
 	return kvb.buffer.Size()
 }
 
-func (kvb *kvStoreWithBuffer) Get(ns string, key []byte) ([]byte, error) {
+func (kvb *kvStoreWithBuffer) Get(ns string, key []byte) ([]byte, bool, error) {
 	value, err := kvb.buffer.Get(ns, key)
+	if err == nil {
+		return value, true, nil
+	}
 	if errors.Cause(err) == batch.ErrNotExist {
 		value, err = kvb.store.Get(ns, key)
 	}
 	if errors.Cause(err) == batch.ErrAlreadyDeleted {
 		err = errors.Wrapf(ErrNotExist, "failed to get key %x in %s, deleted in buffer level", key, ns)
 	}
-	return value, err
+	return value, false, err
 }
 
 func (kvb *kvStoreWithBuffer) Put(ns string, key, value []byte) error {

state/factory/workingset.go

@@ -345,12 +345,16 @@ func (ws *workingSet) State(s interface{}, opts ...protocol.StateOption) (uint64
 	if cfg.Keys != nil {
 		return 0, errors.Wrap(ErrNotSupported, "Read state with keys option has not been implemented yet")
 	}
+	value, inCache, err := ws.store.Get(cfg.Namespace, cfg.Key)
+	if inCache && err == nil {
+		return ws.height, state.Deserialize(s, value)
+	}
 	if ws.parent != nil {
-		if value, err := ws.parent.store.Get(cfg.Namespace, cfg.Key); err == nil {
+		value, inCache, err = ws.parent.store.Get(cfg.Namespace, cfg.Key)
+		if inCache && err == nil {
 			return ws.height, state.Deserialize(s, value)
 		}
 	}
-	value, err := ws.store.Get(cfg.Namespace, cfg.Key)
 	if err != nil {
 		return ws.height, err
 	}

state/factory/workingsetstore.go

@@ -10,11 +10,15 @@ import (
 
 	"github.com/iotexproject/iotex-core/v2/action/protocol"
 	"github.com/iotexproject/iotex-core/v2/db"
+	"github.com/iotexproject/iotex-core/v2/pkg/lifecycle"
 )
 
 type (
 	workingSetStore interface {
-		db.KVStoreBasic
+		lifecycle.StartStopper
+		Put(string, []byte, []byte) error
+		Get(string, []byte) ([]byte, bool, error)
+		Delete(string, []byte) error
 		Commit() error
 		States(string, [][]byte) ([][]byte, [][]byte, error)
 		Digest() hash.Hash256

state/factory/workingsetstore_statedb.go

@@ -39,15 +39,15 @@ func (store *stateDBWorkingSetStore) Stop(context.Context) error {
 	return nil
 }
 
-func (store *stateDBWorkingSetStore) Get(ns string, key []byte) ([]byte, error) {
-	data, err := store.flusher.KVStoreWithBuffer().Get(ns, key)
+func (store *stateDBWorkingSetStore) Get(ns string, key []byte) ([]byte, bool, error) {
+	data, inCache, err := store.flusher.KVStoreWithBuffer().Get(ns, key)
 	if err != nil {
 		if errors.Cause(err) == db.ErrNotExist {
-			return nil, errors.Wrapf(state.ErrStateNotExist, "failed to get state of ns = %x and key = %x", ns, key)
+			return nil, inCache, errors.Wrapf(state.ErrStateNotExist, "failed to get state of ns = %x and key = %x", ns, key)
 		}
-		return nil, err
+		return nil, inCache, err
 	}
-	return data, nil
+	return data, inCache, nil
 }
 
 func (store *stateDBWorkingSetStore) States(ns string, keys [][]byte) ([][]byte, [][]byte, error) {