perf: improve state reader with error handling and committed flag #27428 (#1166)

- Add error returns to Database.Reader() and NodeIterator() methods
- Introduce committed flag to prevent usage of tries after commit
- Update callers to handle new error signatures
- Add MustNodeIterator() helper for backward compatibility

Co-authored-by: rjl493456442 <garyrong0905@gmail.com>

XDCx/tradingstate/XDCx_trie.go

@@ -186,9 +186,38 @@ func (t *XDCXTrie) Copy() *XDCXTrie {
 // NodeIterator returns an iterator that returns nodes of the underlying trie. Iteration
 // starts at the key after the given start key.
 func (t *XDCXTrie) NodeIterator(start []byte) trie.NodeIterator {
-	return t.trie.NodeIterator(start)
+	trieIt, err := t.trie.NodeIterator(start)
+	if err != nil {
+		log.Error(fmt.Sprintf("Unhandled trie error: %v", err))
+		return errNodeIterator{err: err}
+	}
+	return trieIt
 }
 
+// errNodeIterator is a safe, non-nil iterator that reports an error and yields no nodes.
+// It prevents nil dereferences when callers don't check for a nil iterator.
+type errNodeIterator struct {
+	err error
+}
+
+func (it errNodeIterator) Next(bool) bool { return false }
+func (it errNodeIterator) Error() error   { return it.err }
+func (it errNodeIterator) Hash() common.Hash {
+	return common.Hash{}
+}
+func (it errNodeIterator) Parent() common.Hash {
+	return common.Hash{}
+}
+func (it errNodeIterator) Path() []byte     { return nil }
+func (it errNodeIterator) NodeBlob() []byte { return nil }
+func (it errNodeIterator) Leaf() bool       { return false }
+func (it errNodeIterator) LeafKey() []byte  { return nil }
+func (it errNodeIterator) LeafBlob() []byte { return nil }
+func (it errNodeIterator) LeafProof() [][]byte {
+	return nil
+}
+func (it errNodeIterator) AddResolver(trie.NodeResolver) {}
+
 // hashKey returns the hash of key as an ephemeral buffer.
 // The caller must not hold onto the return value because it will become
 // invalid on the next call to hashKey or secKey.

XDCxlending/lendingstate/XDCx_trie.go

@@ -182,9 +182,38 @@ func (t *XDCXTrie) Copy() *XDCXTrie {
 // NodeIterator returns an iterator that returns nodes of the underlying trie. Iteration
 // starts at the key after the given start key.
 func (t *XDCXTrie) NodeIterator(start []byte) trie.NodeIterator {
-	return t.trie.NodeIterator(start)
+	trieIt, err := t.trie.NodeIterator(start)
+	if err != nil {
+		log.Error(fmt.Sprintf("Unhandled trie error: %v", err))
+		return errNodeIterator{err: err}
+	}
+	return trieIt
 }
 
+// errNodeIterator is a safe, non-nil iterator that reports an error and yields no nodes.
+// It prevents nil dereferences when callers don't check for a nil iterator.
+type errNodeIterator struct {
+	err error
+}
+
+func (it errNodeIterator) Next(bool) bool { return false }
+func (it errNodeIterator) Error() error   { return it.err }
+func (it errNodeIterator) Hash() common.Hash {
+	return common.Hash{}
+}
+func (it errNodeIterator) Parent() common.Hash {
+	return common.Hash{}
+}
+func (it errNodeIterator) Path() []byte     { return nil }
+func (it errNodeIterator) NodeBlob() []byte { return nil }
+func (it errNodeIterator) Leaf() bool       { return false }
+func (it errNodeIterator) LeafKey() []byte  { return nil }
+func (it errNodeIterator) LeafBlob() []byte { return nil }
+func (it errNodeIterator) LeafProof() [][]byte {
+	return nil
+}
+func (it errNodeIterator) AddResolver(trie.NodeResolver) {}
+
 // hashKey returns the hash of key as an ephemeral buffer.
 // The caller must not hold onto the return value because it will become
 // invalid on the next call to hashKey or secKey.

cmd/XDC/dbcmd.go

@@ -390,8 +390,12 @@ func dbDumpTrie(ctx *cli.Context) error {
 	if err != nil {
 		return err
 	}
+	trieIt, err := theTrie.NodeIterator(start)
+	if err != nil {
+		return err
+	}
 	var count int64
-	it := trie.NewIterator(theTrie.NodeIterator(start))
+	it := trie.NewIterator(trieIt)
 	for it.Next() {
 		if max > 0 && count == max {
 			fmt.Printf("Exiting after %d values\n", count)

core/state/database.go

@@ -113,8 +113,9 @@ type Trie interface {
 	Commit(collectLeaf bool) (common.Hash, *trienode.NodeSet)
 
 	// NodeIterator returns an iterator that returns nodes of the trie. Iteration
-	// starts at the key after the given start key.
+	// starts at the key after the given start key. An error will be returned
-	NodeIterator(startKey []byte) trie.NodeIterator
+	// if fails to create node iterator.
+	NodeIterator(startKey []byte) (trie.NodeIterator, error)
 
 	// Prove constructs a Merkle proof for key. The result contains all encoded nodes
 	// on the path to the value at key. The value itself is also included in the last

core/state/dump.go

@@ -139,7 +139,11 @@ func (s *StateDB) DumpToCollector(c DumpCollector, conf *DumpConfig) (nextKey []
 	log.Info("Trie dumping started", "root", s.trie.Hash())
 	c.OnRoot(s.trie.Hash())
 
-	it := trie.NewIterator(s.trie.NodeIterator(conf.Start))
+	trieIt, err := s.trie.NodeIterator(conf.Start)
+	if err != nil {
+		return nil
+	}
+	it := trie.NewIterator(trieIt)
 	for it.Next() {
 		var data types.StateAccount
 		if err := rlp.DecodeBytes(it.Value, &data); err != nil {
@@ -177,7 +181,12 @@ func (s *StateDB) DumpToCollector(c DumpCollector, conf *DumpConfig) (nextKey []
 				log.Error("Failed to load storage trie", "err", err)
 				continue
 			}
-			storageIt := trie.NewIterator(tr.NodeIterator(nil))
+			trieIt, err := tr.NodeIterator(nil)
+			if err != nil {
+				log.Error("Failed to create trie iterator", "err", err)
+				continue
+			}
+			storageIt := trie.NewIterator(trieIt)
 			for storageIt.Next() {
 				_, content, _, err := rlp.Split(storageIt.Value)
 				if err != nil {

core/state/iterator.go

@@ -74,8 +74,12 @@ func (it *nodeIterator) step() error {
 		return nil
 	}
 	// Initialize the iterator if we've just started
+	var err error
 	if it.stateIt == nil {
-		it.stateIt = it.state.trie.NodeIterator(nil)
+		it.stateIt, err = it.state.trie.NodeIterator(nil)
+		if err != nil {
+			return err
+		}
 	}
 	// If we had data nodes previously, we surely have at least state nodes
 	if it.dataIt != nil {
@@ -113,7 +117,10 @@ func (it *nodeIterator) step() error {
 	if err != nil {
 		return err
 	}
-	it.dataIt = dataTrie.NodeIterator(nil)
+	it.dataIt, err = dataTrie.NodeIterator(nil)
+	if err != nil {
+		return err
+	}
 	if !it.dataIt.Next(true) {
 		it.dataIt = nil
 	}

core/state/state_test.go

@@ -43,7 +43,8 @@ func newStateTest() *stateTest {
 
 func TestDump(t *testing.T) {
 	db := rawdb.NewMemoryDatabase()
-	sdb, _ := New(types.EmptyRootHash, NewDatabaseWithConfig(db, &trie.Config{Preimages: true}))
+	tdb := NewDatabaseWithConfig(db, &trie.Config{Preimages: true})
+	sdb, _ := New(types.EmptyRootHash, tdb)
 	s := &stateTest{db: db, state: sdb}
 
 	// generate a few entries
@@ -57,9 +58,10 @@ func TestDump(t *testing.T) {
 	// write some of them to the trie
 	s.state.updateStateObject(obj1)
 	s.state.updateStateObject(obj2)
-	s.state.Commit(0, false)
+	root, _ := s.state.Commit(0, false)
 
 	// check that DumpToCollector contains the state objects that are in trie
+	s.state, _ = New(root, tdb)
 	got := string(s.state.Dump(nil))
 	want := `{
     "root": "71edff0130dd2385947095001c73d9e28d862fc286fca2b922ca6f6f3cddfdd2",
@@ -95,7 +97,8 @@ func TestDump(t *testing.T) {
 
 func TestIterativeDump(t *testing.T) {
 	db := rawdb.NewMemoryDatabase()
-	sdb, _ := New(types.EmptyRootHash, NewDatabaseWithConfig(db, &trie.Config{Preimages: true}))
+	tdb := NewDatabaseWithConfig(db, &trie.Config{Preimages: true})
+	sdb, _ := New(types.EmptyRootHash, tdb)
 	s := &stateTest{db: db, state: sdb}
 
 	// generate a few entries
@@ -111,7 +114,8 @@ func TestIterativeDump(t *testing.T) {
 	// write some of them to the trie
 	s.state.updateStateObject(obj1)
 	s.state.updateStateObject(obj2)
-	s.state.Commit(0, false)
+	root, _ := s.state.Commit(0, false)
+	s.state, _ = New(root, tdb)
 
 	b := &bytes.Buffer{}
 	s.state.IterativeDump(nil, json.NewEncoder(b))

core/state/statedb.go

@@ -45,8 +45,14 @@ type revision struct {
 // StateDB structs within the ethereum protocol are used to store anything
 // within the merkle trie. StateDBs take care of caching and storing
 // nested states. It's the general query interface to retrieve:
+//
 // * Contracts
 // * Accounts
+//
+// Once the state is committed, tries cached in stateDB (including account
+// trie, storage tries) will no longer be functional. A new state instance
+// must be created with new root and updated database for accessing post-
+// commit states.
 type StateDB struct {
 	db   Database
 	trie Trie
@@ -678,7 +684,11 @@ func (s *StateDB) ForEachStorage(addr common.Address, cb func(key, value common.
 	if err != nil {
 		return err
 	}
-	it := trie.NewIterator(tr.NodeIterator(nil))
+	trieIt, err := tr.NodeIterator(nil)
+	if err != nil {
+		return err
+	}
+	it := trie.NewIterator(trieIt)
 
 	for it.Next() {
 		key := common.BytesToHash(s.trie.GetKey(it.Key))

core/state/statedb_test.go

@@ -19,6 +19,7 @@ package state
 import (
 	"bytes"
 	"encoding/binary"
+	"errors"
 	"fmt"
 	"math"
 	"math/big"
@@ -33,6 +34,7 @@ import (
 	"github.com/XinFinOrg/XDPoSChain/core/rawdb"
 	"github.com/XinFinOrg/XDPoSChain/core/tracing"
 	"github.com/XinFinOrg/XDPoSChain/core/types"
+	"github.com/XinFinOrg/XDPoSChain/trie"
 )
 
 // Tests that updating a state trie does not leak any database writes prior to
@@ -514,6 +516,51 @@ func TestTouchDelete(t *testing.T) {
 	}
 }
 
+// TestCommitCopy tests the copy from a committed state is not functional.
+func TestCommitCopy(t *testing.T) {
+	state, _ := New(types.EmptyRootHash, NewDatabase(rawdb.NewMemoryDatabase()))
+
+	// Create an account and check if the retrieved balance is correct
+	addr := common.HexToAddress("0xaffeaffeaffeaffeaffeaffeaffeaffeaffeaffe")
+	skey := common.HexToHash("aaa")
+	sval := common.HexToHash("bbb")
+
+	state.SetBalance(addr, big.NewInt(42), tracing.BalanceChangeUnspecified) // Change the account trie
+	state.SetCode(addr, []byte("hello"))                                     // Change an external metadata
+	state.SetState(addr, skey, sval)                                         // Change the storage trie
+
+	if balance := state.GetBalance(addr); balance.Cmp(big.NewInt(42)) != 0 {
+		t.Fatalf("initial balance mismatch: have %v, want %v", balance, 42)
+	}
+	if code := state.GetCode(addr); !bytes.Equal(code, []byte("hello")) {
+		t.Fatalf("initial code mismatch: have %x, want %x", code, []byte("hello"))
+	}
+	if val := state.GetState(addr, skey); val != sval {
+		t.Fatalf("initial non-committed storage slot mismatch: have %x, want %x", val, sval)
+	}
+	if val := state.GetCommittedState(addr, skey); val != (common.Hash{}) {
+		t.Fatalf("initial committed storage slot mismatch: have %x, want %x", val, common.Hash{})
+	}
+	// Copy the committed state database, the copied one is not functional.
+	state.Commit(0, true)
+	copied := state.Copy()
+	if balance := copied.GetBalance(addr); balance.Cmp(big.NewInt(0)) != 0 {
+		t.Fatalf("unexpected balance: have %v", balance)
+	}
+	if code := copied.GetCode(addr); code != nil {
+		t.Fatalf("unexpected code: have %x", code)
+	}
+	if val := copied.GetState(addr, skey); val != (common.Hash{}) {
+		t.Fatalf("unexpected storage slot: have %x", val)
+	}
+	if val := copied.GetCommittedState(addr, skey); val != (common.Hash{}) {
+		t.Fatalf("unexpected storage slot: have %x", val)
+	}
+	if !errors.Is(copied.Error(), trie.ErrCommitted) {
+		t.Fatalf("unexpected state error, %v", copied.Error())
+	}
+}
+
 func TestStateDBAccessList(t *testing.T) {
 	// Some helpers
 	addr := func(a string) common.Address {
@@ -777,7 +824,8 @@ func TestCopyOfCopy(t *testing.T) {
 //
 // See https://github.com/ethereum/go-ethereum/issues/20106.
 func TestCopyCommitCopy(t *testing.T) {
-	state, _ := New(common.Hash{}, NewDatabase(rawdb.NewMemoryDatabase()))
+	tdb := NewDatabase(rawdb.NewMemoryDatabase())
+	state, _ := New(types.EmptyRootHash, tdb)
 
 	// Create an account and check if the retrieved balance is correct
 	addr := common.HexToAddress("0xaffeaffeaffeaffeaffeaffeaffeaffeaffeaffe")
@@ -814,20 +862,6 @@ func TestCopyCommitCopy(t *testing.T) {
 	if val := copyOne.GetCommittedState(addr, skey); val != (common.Hash{}) {
 		t.Fatalf("first copy pre-commit committed storage slot mismatch: have %x, want %x", val, common.Hash{})
 	}
-
-	copyOne.Commit(0, false)
-	if balance := copyOne.GetBalance(addr); balance.Cmp(big.NewInt(42)) != 0 {
-		t.Fatalf("first copy post-commit balance mismatch: have %v, want %v", balance, 42)
-	}
-	if code := copyOne.GetCode(addr); !bytes.Equal(code, []byte("hello")) {
-		t.Fatalf("first copy post-commit code mismatch: have %x, want %x", code, []byte("hello"))
-	}
-	if val := copyOne.GetState(addr, skey); val != sval {
-		t.Fatalf("first copy post-commit non-committed storage slot mismatch: have %x, want %x", val, sval)
-	}
-	if val := copyOne.GetCommittedState(addr, skey); val != sval {
-		t.Fatalf("first copy post-commit committed storage slot mismatch: have %x, want %x", val, sval)
-	}
 	// Copy the copy and check the balance once more
 	copyTwo := copyOne.Copy()
 	if balance := copyTwo.GetBalance(addr); balance.Cmp(big.NewInt(42)) != 0 {
@@ -839,8 +873,23 @@ func TestCopyCommitCopy(t *testing.T) {
 	if val := copyTwo.GetState(addr, skey); val != sval {
 		t.Fatalf("second copy non-committed storage slot mismatch: have %x, want %x", val, sval)
 	}
-	if val := copyTwo.GetCommittedState(addr, skey); val != sval {
+	if val := copyTwo.GetCommittedState(addr, skey); val != (common.Hash{}) {
-		t.Fatalf("second copy post-commit committed storage slot mismatch: have %x, want %x", val, sval)
+		t.Fatalf("second copy committed storage slot mismatch: have %x, want %x", val, sval)
+	}
+	// Commit state, ensure states can be loaded from disk
+	root, _ := state.Commit(0, false)
+	state, _ = New(root, tdb)
+	if balance := state.GetBalance(addr); balance.Cmp(big.NewInt(42)) != 0 {
+		t.Fatalf("state post-commit balance mismatch: have %v, want %v", balance, 42)
+	}
+	if code := state.GetCode(addr); !bytes.Equal(code, []byte("hello")) {
+		t.Fatalf("state post-commit code mismatch: have %x, want %x", code, []byte("hello"))
+	}
+	if val := state.GetState(addr, skey); val != sval {
+		t.Fatalf("state post-commit non-committed storage slot mismatch: have %x, want %x", val, sval)
+	}
+	if val := state.GetCommittedState(addr, skey); val != sval {
+		t.Fatalf("state post-commit committed storage slot mismatch: have %x, want %x", val, sval)
 	}
 }
 
@@ -849,7 +898,7 @@ func TestCopyCommitCopy(t *testing.T) {
 //
 // See https://github.com/ethereum/go-ethereum/issues/20106.
 func TestCopyCopyCommitCopy(t *testing.T) {
-	state, _ := New(common.Hash{}, NewDatabase(rawdb.NewMemoryDatabase()))
+	state, _ := New(types.EmptyRootHash, NewDatabase(rawdb.NewMemoryDatabase()))
 
 	// Create an account and check if the retrieved balance is correct
 	addr := common.HexToAddress("0xaffeaffeaffeaffeaffeaffeaffeaffeaffeaffe")
@@ -900,19 +949,6 @@ func TestCopyCopyCommitCopy(t *testing.T) {
 	if val := copyTwo.GetCommittedState(addr, skey); val != (common.Hash{}) {
 		t.Fatalf("second copy pre-commit committed storage slot mismatch: have %x, want %x", val, common.Hash{})
 	}
-	copyTwo.Commit(0, false)
-	if balance := copyTwo.GetBalance(addr); balance.Cmp(big.NewInt(42)) != 0 {
-		t.Fatalf("second copy post-commit balance mismatch: have %v, want %v", balance, 42)
-	}
-	if code := copyTwo.GetCode(addr); !bytes.Equal(code, []byte("hello")) {
-		t.Fatalf("second copy post-commit code mismatch: have %x, want %x", code, []byte("hello"))
-	}
-	if val := copyTwo.GetState(addr, skey); val != sval {
-		t.Fatalf("second copy post-commit non-committed storage slot mismatch: have %x, want %x", val, sval)
-	}
-	if val := copyTwo.GetCommittedState(addr, skey); val != sval {
-		t.Fatalf("second copy post-commit committed storage slot mismatch: have %x, want %x", val, sval)
-	}
 	// Copy the copy-copy and check the balance once more
 	copyThree := copyTwo.Copy()
 	if balance := copyThree.GetBalance(addr); balance.Cmp(big.NewInt(42)) != 0 {
@@ -924,7 +960,7 @@ func TestCopyCopyCommitCopy(t *testing.T) {
 	if val := copyThree.GetState(addr, skey); val != sval {
 		t.Fatalf("third copy non-committed storage slot mismatch: have %x, want %x", val, sval)
 	}
-	if val := copyThree.GetCommittedState(addr, skey); val != sval {
+	if val := copyThree.GetCommittedState(addr, skey); val != (common.Hash{}) {
 		t.Fatalf("third copy committed storage slot mismatch: have %x, want %x", val, sval)
 	}
 }

core/state/sync_test.go

@@ -109,7 +109,7 @@ func checkTrieConsistency(db ethdb.Database, root common.Hash) error {
 	if err != nil {
 		return err
 	}
-	it := trie.NodeIterator(nil)
+	it := trie.MustNodeIterator(nil)
 	for it.Next(true) {
 	}
 	return it.Error()
@@ -567,6 +567,10 @@ func TestIncompleteStateSync(t *testing.T) {
 		addedPaths  []string
 		addedHashes []common.Hash
 	)
+	reader, err := srcDb.TrieDB().Reader(srcRoot)
+	if err != nil {
+		t.Fatalf("state is not available %x", srcRoot)
+	}
 	nodeQueue := make(map[string]stateElement)
 	codeQueue := make(map[common.Hash]struct{})
 	paths, nodes, codes := sched.Missing(1)
@@ -604,7 +608,7 @@ func TestIncompleteStateSync(t *testing.T) {
 			results := make([]trie.NodeSyncResult, 0, len(nodeQueue))
 			for path, element := range nodeQueue {
 				owner, inner := trie.ResolvePath([]byte(element.path))
-				data, err := srcDb.TrieDB().Reader(srcRoot).Node(owner, inner, element.hash)
+				data, err := reader.Node(owner, inner, element.hash)
 				if err != nil {
 					t.Fatalf("failed to retrieve node data for %x", element.hash)
 				}

eth/api_debug.go

@@ -211,7 +211,11 @@ func (api *DebugAPI) StorageRangeAt(ctx context.Context, blockHash common.Hash,
 }
 
 func storageRangeAt(st state.Trie, start []byte, maxResult int) (StorageRangeResult, error) {
-	it := trie.NewIterator(st.NodeIterator(start))
+	trieIt, err := st.NodeIterator(start)
+	if err != nil {
+		return StorageRangeResult{}, err
+	}
+	it := trie.NewIterator(trieIt)
 	result := StorageRangeResult{Storage: storageMap{}}
 	for i := 0; i < maxResult && it.Next(); i++ {
 		_, content, _, err := rlp.Split(it.Value)
@@ -303,7 +307,15 @@ func (api *DebugAPI) getModifiedAccounts(startBlock, endBlock *types.Block) ([]c
 		return nil, err
 	}
 
-	diff, _ := trie.NewDifferenceIterator(oldTrie.NodeIterator([]byte{}), newTrie.NodeIterator([]byte{}))
+	oldIt, err := oldTrie.NodeIterator([]byte{})
+	if err != nil {
+		return nil, err
+	}
+	newIt, err := newTrie.NodeIterator([]byte{})
+	if err != nil {
+		return nil, err
+	}
+	diff, _ := trie.NewDifferenceIterator(oldIt, newIt)
 	iter := trie.NewIterator(diff)
 
 	var dirty []common.Address

eth/api_debug_test.go

@@ -36,7 +36,7 @@ import (
 
 var dumper = spew.ConfigState{Indent: "    "}
 
-func accountRangeTest(t *testing.T, trie *state.Trie, statedb *state.StateDB, start common.Hash, requestedNum int, expectedNum int) state.IteratorDump {
+func accountRangeTest(t *testing.T, statedb *state.StateDB, start common.Hash, requestedNum int, expectedNum int) state.IteratorDump {
 	result := statedb.IteratorDump(&state.DumpConfig{
 		SkipCode:          true,
 		SkipStorage:       true,
@@ -80,17 +80,17 @@ func TestAccountRange(t *testing.T) {
 			m[addr] = true
 		}
 	}
-	sdb.Commit(0, true)
+	root, err := sdb.Commit(0, true)
-	root := sdb.IntermediateRoot(true)
+	sdb, _ = state.New(root, statedb)
 
-	trie, err := statedb.OpenTrie(root)
+	_, err = statedb.OpenTrie(root)
 	if err != nil {
 		t.Fatal(err)
 	}
-	accountRangeTest(t, &trie, sdb, common.Hash{}, AccountRangeMaxResults/2, AccountRangeMaxResults/2)
+	accountRangeTest(t, sdb, common.Hash{}, AccountRangeMaxResults/2, AccountRangeMaxResults/2)
 	// test pagination
-	firstResult := accountRangeTest(t, &trie, sdb, common.Hash{}, AccountRangeMaxResults, AccountRangeMaxResults)
+	firstResult := accountRangeTest(t, sdb, common.Hash{}, AccountRangeMaxResults, AccountRangeMaxResults)
-	secondResult := accountRangeTest(t, &trie, sdb, common.BytesToHash(firstResult.Next), AccountRangeMaxResults, AccountRangeMaxResults)
+	secondResult := accountRangeTest(t, sdb, common.BytesToHash(firstResult.Next), AccountRangeMaxResults, AccountRangeMaxResults)
 
 	hList := make([]common.Hash, 0)
 	for addr1 := range firstResult.Accounts {
@@ -108,7 +108,7 @@ func TestAccountRange(t *testing.T) {
 	// set and get an even split between the first and second sets.
 	slices.SortFunc(hList, common.Hash.Cmp)
 	middleH := hList[AccountRangeMaxResults/2]
-	middleResult := accountRangeTest(t, &trie, sdb, middleH, AccountRangeMaxResults, AccountRangeMaxResults)
+	middleResult := accountRangeTest(t, sdb, middleH, AccountRangeMaxResults, AccountRangeMaxResults)
 	missing, infirst, insecond := 0, 0, 0
 	for h := range middleResult.Accounts {
 		if _, ok := firstResult.Accounts[h]; ok {

tests/state_test_util.go

@@ -202,6 +202,11 @@ func (t *StateTest) Run(subtest StateSubtest, vmconfig vm.Config) (*state.StateD
 	if root != common.Hash(post.Root) {
 		return statedb, fmt.Errorf("post state root mismatch: got %x, want %x", root, post.Root)
 	}
+	// Re-init the post-state instance for further operation
+	statedb, err = state.New(root, statedb.Database())
+	if err != nil {
+		return nil, err
+	}
 	return statedb, nil
 }
 

trie/database_wrap.go

@@ -133,11 +133,11 @@ func (db *Database) InsertPreimage(secKeyCache map[string][]byte) {
 
 // Reader returns a reader for accessing all trie nodes with provided state root.
 // Nil is returned in case the state is not available.
-func (db *Database) Reader(blockRoot common.Hash) Reader {
+func (db *Database) Reader(blockRoot common.Hash) (Reader, error) {
 	if hdb, ok := db.backend.(*hashdb.Database); ok {
 		return hdb.Reader(blockRoot)
 	}
-	return nil
+	return nil, errors.New("no support hashdb.Database")
 }
 
 // Update performs a state transition by committing dirty nodes contained in the

trie/errors.go

@@ -17,11 +17,17 @@
 package trie
 
 import (
+	"errors"
 	"fmt"
 
 	"github.com/XinFinOrg/XDPoSChain/common"
 )
 
+// ErrCommitted is returned when a already committed trie is requested for usage.
+// The potential usages can be `Get`, `Update`, `Delete`, `NodeIterator`, `Prove`
+// and so on.
+var ErrCommitted = errors.New("trie is already committed")
+
 // MissingNodeError is returned by the trie functions (Get, Update, Delete)
 // in the case where a trie node is not present in the local database. It contains
 // information necessary for retrieving the missing node.

trie/iterator_test.go

@@ -34,7 +34,7 @@ import (
 
 func TestEmptyIterator(t *testing.T) {
 	trie := NewEmpty(NewDatabase(rawdb.NewMemoryDatabase()))
-	iter := trie.NodeIterator(nil)
+	iter := trie.MustNodeIterator(nil)
 
 	seen := make(map[string]struct{})
 	for iter.Next(true) {
@@ -67,7 +67,7 @@ func TestIterator(t *testing.T) {
 
 	trie, _ = New(TrieID(root), db)
 	found := make(map[string]string)
-	it := NewIterator(trie.NodeIterator(nil))
+	it := NewIterator(trie.MustNodeIterator(nil))
 	for it.Next() {
 		found[string(it.Key)] = string(it.Value)
 	}
@@ -101,7 +101,7 @@ func TestIteratorLargeData(t *testing.T) {
 		vals[string(value2.k)] = value2
 	}
 
-	it := NewIterator(trie.NodeIterator(nil))
+	it := NewIterator(trie.MustNodeIterator(nil))
 	for it.Next() {
 		vals[string(it.Key)].t = true
 	}
@@ -139,7 +139,7 @@ func testNodeIteratorCoverage(t *testing.T, scheme string) {
 
 	// Gather all the node hashes found by the iterator
 	var elements = make(map[common.Hash]iterationElement)
-	for it := trie.NodeIterator(nil); it.Next(true); {
+	for it := trie.MustNodeIterator(nil); it.Next(true); {
 		if it.Hash() != (common.Hash{}) {
 			elements[it.Hash()] = iterationElement{
 				hash: it.Hash(),
@@ -149,8 +149,12 @@ func testNodeIteratorCoverage(t *testing.T, scheme string) {
 		}
 	}
 	// Cross check the hashes and the database itself
+	reader, err := nodeDb.Reader(trie.Hash())
+	if err != nil {
+		t.Fatalf("state is not available %x", trie.Hash())
+	}
 	for _, element := range elements {
-		if blob, err := nodeDb.Reader(trie.Hash()).Node(common.Hash{}, element.path, element.hash); err != nil {
+		if blob, err := reader.Node(common.Hash{}, element.path, element.hash); err != nil {
 			t.Errorf("failed to retrieve reported node %x: %v", element.hash, err)
 		} else if !bytes.Equal(blob, element.blob) {
 			t.Errorf("node blob is different, want %v got %v", element.blob, blob)
@@ -210,19 +214,19 @@ func TestIteratorSeek(t *testing.T) {
 	}
 
 	// Seek to the middle.
-	it := NewIterator(trie.NodeIterator([]byte("fab")))
+	it := NewIterator(trie.MustNodeIterator([]byte("fab")))
 	if err := checkIteratorOrder(testdata1[4:], it); err != nil {
 		t.Fatal(err)
 	}
 
 	// Seek to a non-existent key.
-	it = NewIterator(trie.NodeIterator([]byte("barc")))
+	it = NewIterator(trie.MustNodeIterator([]byte("barc")))
 	if err := checkIteratorOrder(testdata1[1:], it); err != nil {
 		t.Fatal(err)
 	}
 
 	// Seek beyond the end.
-	it = NewIterator(trie.NodeIterator([]byte("z")))
+	it = NewIterator(trie.MustNodeIterator([]byte("z")))
 	if err := checkIteratorOrder(nil, it); err != nil {
 		t.Fatal(err)
 	}
@@ -264,7 +268,7 @@ func TestDifferenceIterator(t *testing.T) {
 	trieb, _ = New(TrieID(rootB), dbb)
 
 	found := make(map[string]string)
-	di, _ := NewDifferenceIterator(triea.NodeIterator(nil), trieb.NodeIterator(nil))
+	di, _ := NewDifferenceIterator(triea.MustNodeIterator(nil), trieb.MustNodeIterator(nil))
 	it := NewIterator(di)
 	for it.Next() {
 		found[string(it.Key)] = string(it.Value)
@@ -305,7 +309,7 @@ func TestUnionIterator(t *testing.T) {
 	dbb.Update(rootB, types.EmptyRootHash, 0, trienode.NewWithNodeSet(nodesB))
 	trieb, _ = New(TrieID(rootB), dbb)
 
-	di, _ := NewUnionIterator([]NodeIterator{triea.NodeIterator(nil), trieb.NodeIterator(nil)})
+	di, _ := NewUnionIterator([]NodeIterator{triea.MustNodeIterator(nil), trieb.MustNodeIterator(nil)})
 	it := NewIterator(di)
 
 	all := []struct{ k, v string }{
@@ -344,7 +348,7 @@ func TestIteratorNoDups(t *testing.T) {
 	for _, val := range testdata1 {
 		tr.MustUpdate([]byte(val.k), []byte(val.v))
 	}
-	checkIteratorNoDups(t, tr.NodeIterator(nil), nil)
+	checkIteratorNoDups(t, tr.MustNodeIterator(nil), nil)
 }
 
 // This test checks that nodeIterator.Next can be retried after inserting missing trie nodes.
@@ -369,7 +373,7 @@ func testIteratorContinueAfterError(t *testing.T, memonly bool, scheme string) {
 		tdb.Commit(root, false)
 	}
 	tr, _ = New(TrieID(root), tdb)
-	wantNodeCount := checkIteratorNoDups(t, tr.NodeIterator(nil), nil)
+	wantNodeCount := checkIteratorNoDups(t, tr.MustNodeIterator(nil), nil)
 
 	var (
 		paths  [][]byte
@@ -428,7 +432,7 @@ func testIteratorContinueAfterError(t *testing.T, memonly bool, scheme string) {
 		}
 		// Iterate until the error is hit.
 		seen := make(map[string]bool)
-		it := tr.NodeIterator(nil)
+		it := tr.MustNodeIterator(nil)
 		checkIteratorNoDups(t, it, seen)
 		missing, ok := it.Error().(*MissingNodeError)
 		if !ok || missing.NodeHash != rhash {
@@ -496,7 +500,7 @@ func testIteratorContinueAfterSeekError(t *testing.T, memonly bool, scheme strin
 	}
 	// Create a new iterator that seeks to "bars". Seeking can't proceed because
 	// the node is missing.
-	it := tr.NodeIterator([]byte("bars"))
+	it := tr.MustNodeIterator([]byte("bars"))
 	missing, ok := it.Error().(*MissingNodeError)
 	if !ok {
 		t.Fatal("want MissingNodeError, got", it.Error())
@@ -598,7 +602,10 @@ func makeLargeTestTrie() (*Database, *StateTrie, *loggingDb) {
 	}
 	root, nodes := trie.Commit(false)
 	triedb.Update(root, types.EmptyRootHash, 0, trienode.NewWithNodeSet(nodes))
+	triedb.Commit(root, false)
+
 	// Return the generated trie
+	trie, _ = NewStateTrie(TrieID(root), triedb)
 	return triedb, trie, logDb
 }
 
@@ -610,8 +617,8 @@ func TestNodeIteratorLargeTrie(t *testing.T) {
 	// Do a seek operation
 	trie.NodeIterator(common.FromHex("0x77667766776677766778855885885885"))
 	// master: 24 get operations
-	// this pr: 5 get operations
+	// this pr: 6 get operations
-	if have, want := logDb.getCount, uint64(5); have != want {
+	if have, want := logDb.getCount, uint64(6); have != want {
 		t.Fatalf("Too many lookups during seek, have %d want %d", have, want)
 	}
 }
@@ -642,7 +649,7 @@ func testIteratorNodeBlob(t *testing.T, scheme string) {
 
 	var found = make(map[common.Hash][]byte)
 	trie, _ = New(TrieID(root), triedb)
-	it := trie.NodeIterator(nil)
+	it := trie.MustNodeIterator(nil)
 	for it.Next(true) {
 		if it.Hash() == (common.Hash{}) {
 			continue

trie/proof.go

@@ -34,6 +34,10 @@ import (
 // nodes of the longest existing prefix of the key (at least the root node), ending
 // with the node that proves the absence of the key.
 func (t *Trie) Prove(key []byte, proofDb ethdb.KeyValueWriter) error {
+	// Short circuit if the trie is already committed and not usable.
+	if t.committed {
+		return ErrCommitted
+	}
 	// Collect all nodes on the path to key.
 	var (
 		prefix []byte

trie/proof_test.go

@@ -63,7 +63,7 @@ func makeProvers(trie *Trie) []func(key []byte) *memorydb.Database {
 	// Create a leaf iterator based Merkle prover
 	provers = append(provers, func(key []byte) *memorydb.Database {
 		proof := memorydb.New()
-		if it := NewIterator(trie.NodeIterator(key)); it.Next() && bytes.Equal(key, it.Key) {
+		if it := NewIterator(trie.MustNodeIterator(key)); it.Next() && bytes.Equal(key, it.Key) {
 			for _, p := range it.Prove() {
 				proof.Put(crypto.Keccak256(p), p)
 			}

trie/secure_trie.go

@@ -250,12 +250,18 @@ func (t *StateTrie) Copy() *StateTrie {
 	}
 }
 
-// NodeIterator returns an iterator that returns nodes of the underlying trie. Iteration
+// NodeIterator returns an iterator that returns nodes of the underlying trie.
-// starts at the key after the given start key.
+// Iteration starts at the key after the given start key.
-func (t *StateTrie) NodeIterator(start []byte) NodeIterator {
+func (t *StateTrie) NodeIterator(start []byte) (NodeIterator, error) {
 	return t.trie.NodeIterator(start)
 }
 
+// MustNodeIterator is a wrapper of NodeIterator and will omit any encountered
+// error but just print out an error message.
+func (t *StateTrie) MustNodeIterator(start []byte) NodeIterator {
+	return t.trie.MustNodeIterator(start)
+}
+
 // hashKey returns the hash of key as an ephemeral buffer.
 // The caller must not hold onto the return value because it will become
 // invalid on the next call to hashKey or secKey.

trie/sync_test.go

@@ -94,7 +94,7 @@ func checkTrieConsistency(db ethdb.Database, scheme string, root common.Hash) er
 	if err != nil {
 		return nil // Consider a non existent state consistent
 	}
-	it := trie.NodeIterator(nil)
+	it := trie.MustNodeIterator(nil)
 	for it.Next(true) {
 	}
 	return it.Error()
@@ -159,12 +159,16 @@ func testIterativeSync(t *testing.T, count int, bypath bool, scheme string) {
 			syncPath: NewSyncPath([]byte(paths[i])),
 		})
 	}
+	reader, err := srcDb.Reader(srcTrie.Hash())
+	if err != nil {
+		t.Fatalf("State is not available %x", srcTrie.Hash())
+	}
 	for len(elements) > 0 {
 		results := make([]NodeSyncResult, len(elements))
 		if !bypath {
 			for i, element := range elements {
 				owner, inner := ResolvePath([]byte(element.path))
-				data, err := srcDb.Reader(srcTrie.Hash()).Node(owner, inner, element.hash)
+				data, err := reader.Node(owner, inner, element.hash)
 				if err != nil {
 					t.Fatalf("failed to retrieve node data for hash %x: %v", element.hash, err)
 				}
@@ -230,12 +234,16 @@ func testIterativeDelayedSync(t *testing.T, scheme string) {
 			syncPath: NewSyncPath([]byte(paths[i])),
 		})
 	}
+	reader, err := srcDb.Reader(srcTrie.Hash())
+	if err != nil {
+		t.Fatalf("State is not available %x", srcTrie.Hash())
+	}
 	for len(elements) > 0 {
 		// Sync only half of the scheduled nodes
 		results := make([]NodeSyncResult, len(elements)/2+1)
 		for i, element := range elements[:len(results)] {
 			owner, inner := ResolvePath([]byte(element.path))
-			data, err := srcDb.Reader(srcTrie.Hash()).Node(owner, inner, element.hash)
+			data, err := reader.Node(owner, inner, element.hash)
 			if err != nil {
 				t.Fatalf("failed to retrieve node data for %x: %v", element.hash, err)
 			}
@@ -295,12 +303,16 @@ func testIterativeRandomSync(t *testing.T, count int, scheme string) {
 			syncPath: NewSyncPath([]byte(paths[i])),
 		}
 	}
+	reader, err := srcDb.Reader(srcTrie.Hash())
+	if err != nil {
+		t.Fatalf("State is not available %x", srcTrie.Hash())
+	}
 	for len(queue) > 0 {
 		// Fetch all the queued nodes in a random order
 		results := make([]NodeSyncResult, 0, len(queue))
 		for path, element := range queue {
 			owner, inner := ResolvePath([]byte(element.path))
-			data, err := srcDb.Reader(srcTrie.Hash()).Node(owner, inner, element.hash)
+			data, err := reader.Node(owner, inner, element.hash)
 			if err != nil {
 				t.Fatalf("failed to retrieve node data for %x: %v", element.hash, err)
 			}
@@ -358,12 +370,16 @@ func testIterativeRandomDelayedSync(t *testing.T, scheme string) {
 			syncPath: NewSyncPath([]byte(path)),
 		}
 	}
+	reader, err := srcDb.Reader(srcTrie.Hash())
+	if err != nil {
+		t.Fatalf("State is not available %x", srcTrie.Hash())
+	}
 	for len(queue) > 0 {
 		// Sync only half of the scheduled nodes, even those in random order
 		results := make([]NodeSyncResult, 0, len(queue)/2+1)
 		for path, element := range queue {
 			owner, inner := ResolvePath([]byte(element.path))
-			data, err := srcDb.Reader(srcTrie.Hash()).Node(owner, inner, element.hash)
+			data, err := reader.Node(owner, inner, element.hash)
 			if err != nil {
 				t.Fatalf("failed to retrieve node data for %x: %v", element.hash, err)
 			}
@@ -426,13 +442,16 @@ func testDuplicateAvoidanceSync(t *testing.T, scheme string) {
 			syncPath: NewSyncPath([]byte(paths[i])),
 		})
 	}
+	reader, err := srcDb.Reader(srcTrie.Hash())
+	if err != nil {
+		t.Fatalf("State is not available %x", srcTrie.Hash())
+	}
 	requested := make(map[common.Hash]struct{})
-
 	for len(elements) > 0 {
 		results := make([]NodeSyncResult, len(elements))
 		for i, element := range elements {
 			owner, inner := ResolvePath([]byte(element.path))
-			data, err := srcDb.Reader(srcTrie.Hash()).Node(owner, inner, element.hash)
+			data, err := reader.Node(owner, inner, element.hash)
 			if err != nil {
 				t.Fatalf("failed to retrieve node data for %x: %v", element.hash, err)
 			}
@@ -501,12 +520,16 @@ func testIncompleteSync(t *testing.T, scheme string) {
 			syncPath: NewSyncPath([]byte(paths[i])),
 		})
 	}
+	reader, err := srcDb.Reader(srcTrie.Hash())
+	if err != nil {
+		t.Fatalf("State is not available %x", srcTrie.Hash())
+	}
 	for len(elements) > 0 {
 		// Fetch a batch of trie nodes
 		results := make([]NodeSyncResult, len(elements))
 		for i, element := range elements {
 			owner, inner := ResolvePath([]byte(element.path))
-			data, err := srcDb.Reader(srcTrie.Hash()).Node(owner, inner, element.hash)
+			data, err := reader.Node(owner, inner, element.hash)
 			if err != nil {
 				t.Fatalf("failed to retrieve node data for %x: %v", element.hash, err)
 			}
@@ -585,12 +608,15 @@ func testSyncOrdering(t *testing.T, scheme string) {
 		})
 		reqs = append(reqs, NewSyncPath([]byte(paths[i])))
 	}
-
+	reader, err := srcDb.Reader(srcTrie.Hash())
+	if err != nil {
+		t.Fatalf("State is not available %x", srcTrie.Hash())
+	}
 	for len(elements) > 0 {
 		results := make([]NodeSyncResult, len(elements))
 		for i, element := range elements {
 			owner, inner := ResolvePath([]byte(element.path))
-			data, err := srcDb.Reader(srcTrie.Hash()).Node(owner, inner, element.hash)
+			data, err := reader.Node(owner, inner, element.hash)
 			if err != nil {
 				t.Fatalf("failed to retrieve node data for %x: %v", element.hash, err)
 			}
@@ -649,11 +675,15 @@ func syncWith(t *testing.T, root common.Hash, db ethdb.Database, srcDb *Database
 			syncPath: NewSyncPath([]byte(paths[i])),
 		})
 	}
+	reader, err := srcDb.Reader(root)
+	if err != nil {
+		t.Fatalf("State is not available %x", root)
+	}
 	for len(elements) > 0 {
 		results := make([]NodeSyncResult, len(elements))
 		for i, element := range elements {
 			owner, inner := ResolvePath([]byte(element.path))
-			data, err := srcDb.Reader(root).Node(owner, inner, element.hash)
+			data, err := reader.Node(owner, inner, element.hash)
 			if err != nil {
 				t.Fatalf("failed to retrieve node data for hash %x: %v", element.hash, err)
 			}

trie/tracer_test.go

@@ -226,14 +226,14 @@ func TestAccessListLeak(t *testing.T) {
 	}{
 		{
 			func(tr *Trie) {
-				it := tr.NodeIterator(nil)
+				it := tr.MustNodeIterator(nil)
 				for it.Next(true) {
 				}
 			},
 		},
 		{
 			func(tr *Trie) {
-				it := NewIterator(tr.NodeIterator(nil))
+				it := NewIterator(tr.MustNodeIterator(nil))
 				for it.Next() {
 				}
 			},
@@ -300,7 +300,7 @@ func compareSet(setA, setB map[string]struct{}) bool {
 
 func forNodes(tr *Trie) map[string][]byte {
 	var (
-		it    = tr.NodeIterator(nil)
+		it    = tr.MustNodeIterator(nil)
 		nodes = make(map[string][]byte)
 	)
 	for it.Next(true) {
@@ -319,7 +319,7 @@ func iterNodes(db *Database, root common.Hash) map[string][]byte {
 
 func forHashedNodes(tr *Trie) map[string][]byte {
 	var (
-		it    = tr.NodeIterator(nil)
+		it    = tr.MustNodeIterator(nil)
 		nodes = make(map[string][]byte)
 	)
 	for it.Next(true) {

trie/trie.go

@@ -39,6 +39,10 @@ type Trie struct {
 	root  node
 	owner common.Hash
 
+	// Flag whether the commit operation is already performed. If so the
+	// trie is not usable(latest state is invisible).
+	committed bool
+
 	// Keep track of the number leaves which have been inserted since the last
 	// hashing operation. This number will not directly map to the number of
 	// actually unhashed nodes.
@@ -88,12 +92,13 @@ func (t *Trie) UpdateDb(root common.Hash, parent common.Hash, block uint64, node
 // Copy returns a copy of Trie.
 func (t *Trie) Copy() *Trie {
 	return &Trie{
-		root:     t.root,
+		root:      t.root,
-		owner:    t.owner,
+		owner:     t.owner,
-		unhashed: t.unhashed,
+		committed: t.committed,
-		db:       t.db,
+		unhashed:  t.unhashed,
-		reader:   t.reader,
+		db:        t.db,
-		tracer:   t.tracer.copy(),
+		reader:    t.reader,
+		tracer:    t.tracer.copy(),
 	}
 }
 
@@ -130,10 +135,24 @@ func NewEmpty(db *Database) *Trie {
 	return tr
 }
 
+// MustNodeIterator is a wrapper of NodeIterator and will omit any encountered
+// error but just print out an error message.
+func (t *Trie) MustNodeIterator(start []byte) NodeIterator {
+	it, err := t.NodeIterator(start)
+	if err != nil {
+		log.Error("Unhandled trie error in Trie.NodeIterator", "err", err)
+	}
+	return it
+}
+
 // NodeIterator returns an iterator that returns nodes of the trie. Iteration starts at
 // the key after the given start key.
-func (t *Trie) NodeIterator(start []byte) NodeIterator {
+func (t *Trie) NodeIterator(start []byte) (NodeIterator, error) {
-	return newNodeIterator(t, start)
+	// Short circuit if the trie is already committed and not usable.
+	if t.committed {
+		return nil, ErrCommitted
+	}
+	return newNodeIterator(t, start), nil
 }
 
 // MustGet is a wrapper of Get and will omit any encountered error but just
@@ -152,6 +171,10 @@ func (t *Trie) MustGet(key []byte) []byte {
 // If the requested node is not present in trie, no error will be returned.
 // If the trie is corrupted, a MissingNodeError is returned.
 func (t *Trie) Get(key []byte) ([]byte, error) {
+	// Short circuit if the trie is already committed and not usable.
+	if t.committed {
+		return nil, ErrCommitted
+	}
 	value, newroot, didResolve, err := t.get(t.root, keybytesToHex(key), 0)
 	if err == nil && didResolve {
 		t.root = newroot
@@ -211,6 +234,10 @@ func (t *Trie) MustGetNode(path []byte) ([]byte, int) {
 // If the requested node is not present in trie, no error will be returned.
 // If the trie is corrupted, a MissingNodeError is returned.
 func (t *Trie) GetNode(path []byte) ([]byte, int, error) {
+	// Short circuit if the trie is already committed and not usable.
+	if t.committed {
+		return nil, 0, ErrCommitted
+	}
 	item, newroot, resolved, err := t.getNode(t.root, compactToHex(path), 0)
 	if err != nil {
 		return nil, resolved, err
@@ -468,6 +495,10 @@ func (t *Trie) MustUpdate(key, value []byte) {
 // If the requested node is not present in trie, no error will be returned.
 // If the trie is corrupted, a MissingNodeError is returned.
 func (t *Trie) Update(key, value []byte) error {
+	// Short circuit if the trie is already committed and not usable.
+	if t.committed {
+		return ErrCommitted
+	}
 	return t.update(key, value)
 }
 
@@ -582,6 +613,10 @@ func (t *Trie) MustDelete(key []byte) {
 // If the requested node is not present in trie, no error will be returned.
 // If the trie is corrupted, a MissingNodeError is returned.
 func (t *Trie) Delete(key []byte) error {
+	// Short circuit if the trie is already committed and not usable.
+	if t.committed {
+		return ErrCommitted
+	}
 	t.unhashed++
 	k := keybytesToHex(key)
 	_, n, err := t.delete(t.root, nil, k)
@@ -769,7 +804,9 @@ func (t *Trie) Hash() common.Hash {
 // be created with new root and updated trie database for following usage
 func (t *Trie) Commit(collectLeaf bool) (common.Hash, *trienode.NodeSet) {
 	defer t.tracer.reset()
-
+	defer func() {
+		t.committed = true
+	}()
 	nodes := trienode.NewNodeSet(t.owner)
 	t.tracer.markDeletions(nodes)
 
@@ -816,4 +853,5 @@ func (t *Trie) Reset() {
 	t.owner = common.Hash{}
 	t.unhashed = 0
 	t.tracer.reset()
+	t.committed = false
 }

trie/trie_reader.go

@@ -17,9 +17,9 @@
 package trie
 
 import (
-	"fmt"
-
 	"github.com/XinFinOrg/XDPoSChain/common"
+	"github.com/XinFinOrg/XDPoSChain/core/types"
+	"github.com/XinFinOrg/XDPoSChain/log"
 )
 
 // Reader wraps the Node method of a backing trie store.
@@ -30,13 +30,6 @@ type Reader interface {
 	Node(owner common.Hash, path []byte, hash common.Hash) ([]byte, error)
 }
 
-// NodeReader wraps all the necessary functions for accessing trie node.
-type NodeReader interface {
-	// Reader returns a reader for accessing all trie nodes with provided
-	// state root. Nil is returned in case the state is not available.
-	Reader(root common.Hash) Reader
-}
-
 // trieReader is a wrapper of the underlying node reader. It's not safe
 // for concurrent usage.
 type trieReader struct {
@@ -46,10 +39,16 @@ type trieReader struct {
 }
 
 // newTrieReader initializes the trie reader with the given node reader.
-func newTrieReader(stateRoot, owner common.Hash, db NodeReader) (*trieReader, error) {
+func newTrieReader(stateRoot, owner common.Hash, db *Database) (*trieReader, error) {
-	reader := db.Reader(stateRoot)
+	if stateRoot == (common.Hash{}) || stateRoot == types.EmptyRootHash {
-	if reader == nil {
+		if stateRoot == (common.Hash{}) {
-		return nil, fmt.Errorf("state not found #%x", stateRoot)
+			log.Error("Zero state root hash!")
+		}
+		return &trieReader{owner: owner}, nil
+	}
+	reader, err := db.Reader(stateRoot)
+	if err != nil {
+		return nil, &MissingNodeError{Owner: owner, NodeHash: stateRoot, err: err}
 	}
 	return &trieReader{owner: owner, reader: reader}, nil
 }

trie/trie_test.go

@@ -540,7 +540,7 @@ func runRandTest(rt randTest) error {
 			origin = root
 		case opItercheckhash:
 			checktr := NewEmpty(triedb)
-			it := NewIterator(tr.NodeIterator(nil))
+			it := NewIterator(tr.MustNodeIterator(nil))
 			for it.Next() {
 				checktr.MustUpdate(it.Key, it.Value)
 			}
@@ -549,8 +549,8 @@ func runRandTest(rt randTest) error {
 			}
 		case opNodeDiff:
 			var (
-				origIter = origTrie.NodeIterator(nil)
+				origIter = origTrie.MustNodeIterator(nil)
-				curIter  = tr.NodeIterator(nil)
+				curIter  = tr.MustNodeIterator(nil)
 				origSeen = make(map[string]struct{})
 				curSeen  = make(map[string]struct{})
 			)
@@ -729,7 +729,7 @@ func TestTinyTrie(t *testing.T) {
 		t.Errorf("3: got %x, exp %x", root, exp)
 	}
 	checktr := NewEmpty(NewDatabase(rawdb.NewMemoryDatabase()))
-	it := NewIterator(trie.NodeIterator(nil))
+	it := NewIterator(trie.MustNodeIterator(nil))
 	for it.Next() {
 		checktr.MustUpdate(it.Key, it.Value)
 	}

trie/triedb/hashdb/database.go

@@ -18,6 +18,7 @@ package hashdb
 
 import (
 	"errors"
+	"fmt"
 	"reflect"
 	"sync"
 	"time"
@@ -621,8 +622,12 @@ func (db *Database) Scheme() string {
 }
 
 // Reader retrieves a node reader belonging to the given state root.
-func (db *Database) Reader(root common.Hash) *reader {
+// An error will be returned if the requested state is not available.
-	return &reader{db: db}
+func (db *Database) Reader(root common.Hash) (*reader, error) {
+	if _, err := db.Node(root); err != nil {
+		return nil, fmt.Errorf("state %#x is not available, %v", root, err)
+	}
+	return &reader{db: db}, nil
 }
 
 // reader is a state reader of Database which implements the Reader interface.