resolve igor's comments

core/blockchain.go

@@ -597,7 +597,7 @@ func (bc *BlockChain) tryRewindBadBlocks() {
 	snaps := bc.snaps
 	// Verified and Result is false
 	if snaps != nil && snaps.Snapshot(block.Root()) != nil &&
-		snaps.Snapshot(block.Root()).Verified() && !snaps.Snapshot(block.Root()).WaitVerified() {
+		snaps.Snapshot(block.Root()).Verified() && !snaps.Snapshot(block.Root()).WaitAndGetVerifyRes() {
 		// Rewind by one block
 		log.Warn("current block verified failed, rewind to its parent", "height", block.NumberU64(), "hash", block.Hash())
 		bc.futureBlocks.Remove(block.Hash())

core/state/snapshot/difflayer.go

@@ -260,8 +260,8 @@ func (dl *diffLayer) Root() common.Hash {
 	return dl.root
 }
 
-// WaitVerified will wait until the diff layer been verified and return the verification result
-func (dl *diffLayer) WaitVerified() bool {
+// WaitAndGetVerifyRes will wait until the diff layer been verified and return the verification result
+func (dl *diffLayer) WaitAndGetVerifyRes() bool {
 	if dl.verifiedCh == nil {
 		return true
 	}

core/state/snapshot/disklayer.go

@@ -49,7 +49,7 @@ func (dl *diskLayer) Root() common.Hash {
 	return dl.root
 }
 
-func (dl *diskLayer) WaitVerified() bool {
+func (dl *diskLayer) WaitAndGetVerifyRes() bool {
 	return true
 }
 

core/state/snapshot/snapshot.go

@@ -101,8 +101,8 @@ type Snapshot interface {
 	// Root returns the root hash for which this snapshot was made.
 	Root() common.Hash
 
-	// WaitVerified will wait until the snapshot been verified
-	WaitVerified() bool
+	// WaitAndGetVerifyRes will wait until the snapshot been verified and return verification result
+	WaitAndGetVerifyRes() bool
 
 	// Verified returns whether the snapshot is verified
 	Verified() bool

core/state/statedb.go

@@ -170,7 +170,7 @@ func newStateDB(root common.Hash, db Database, snaps *snapshot.Tree) (*StateDB,
 
 	snapVerified := sdb.snap != nil && sdb.snap.Verified()
 	tr, err := db.OpenTrie(root)
-	// return error when 1. failed to open trie and 2. the snap is not nil and done verification
+	// return error when 1. failed to open trie and 2. the snap is nil or the snap is not nil and done verification
 	if err != nil && (sdb.snap == nil || snapVerified) {
 		return nil, err
 	}
@@ -1020,7 +1020,7 @@ func (s *StateDB) AccountsIntermediateRoot() error {
 
 	// We need wait for the parent trie to commit
 	if s.snap != nil {
-		if valid := s.snap.WaitVerified(); !valid {
+		if valid := s.snap.WaitAndGetVerifyRes(); !valid {
 			return fmt.Errorf("verification on parent snap failed")
 		}
 	}

eth/tracers/api.go

@@ -558,7 +558,7 @@ func (api *API) IntermediateRoots(ctx context.Context, hash common.Hash, config
 		// so any modifications are written to the trie
 		root, err := statedb.IntermediateRoot(deleteEmptyObjects)
 		if err != nil {
-			return roots, err
+			return nil, err
 		}
 		roots = append(roots, root)
 	}