trie: implement NodeBlob API for trie iterator

trie/iterator.go

@@ -86,6 +86,10 @@ type NodeIterator interface {
 	// For leaf nodes, the last element of the path is the 'terminator symbol' 0x10.
 	Path() []byte
 
+	// NodeBlob returns the rlp-encoded value of the current iterated node.
+	// If the node is an embedded node in its parent, nil is returned then.
+	NodeBlob() []byte
+
 	// Leaf returns true iff the current node is a leaf node.
 	Leaf() bool
 
@@ -224,6 +228,18 @@ func (it *nodeIterator) Path() []byte {
 	return it.path
 }
 
+func (it *nodeIterator) NodeBlob() []byte {
+	if it.Hash() == (common.Hash{}) {
+		return nil // skip the non-standalone node
+	}
+	blob, err := it.resolveBlob(it.Hash().Bytes(), it.Path())
+	if err != nil {
+		it.err = err
+		return nil
+	}
+	return blob
+}
+
 func (it *nodeIterator) Error() error {
 	if it.err == errIteratorEnd {
 		return nil
@@ -362,6 +378,15 @@ func (it *nodeIterator) resolveHash(hash hashNode, path []byte) (node, error) {
 	return resolved, err
 }
 
+func (it *nodeIterator) resolveBlob(hash hashNode, path []byte) ([]byte, error) {
+	if it.resolver != nil {
+		if blob, err := it.resolver.Get(hash); err == nil && len(blob) > 0 {
+			return blob, nil
+		}
+	}
+	return it.trie.resolveBlob(hash, path)
+}
+
 func (st *nodeIteratorState) resolve(it *nodeIterator, path []byte) error {
 	if hash, ok := st.node.(hashNode); ok {
 		resolved, err := it.resolveHash(hash, path)
@@ -549,6 +574,10 @@ func (it *differenceIterator) Path() []byte {
 	return it.b.Path()
 }
 
+func (it *differenceIterator) NodeBlob() []byte {
+	return it.b.NodeBlob()
+}
+
 func (it *differenceIterator) AddResolver(resolver ethdb.KeyValueReader) {
 	panic("not implemented")
 }
@@ -660,6 +689,10 @@ func (it *unionIterator) Path() []byte {
 	return (*it.items)[0].Path()
 }
 
+func (it *unionIterator) NodeBlob() []byte {
+	return (*it.items)[0].NodeBlob()
+}
+
 func (it *unionIterator) AddResolver(resolver ethdb.KeyValueReader) {
 	panic("not implemented")
 }

trie/iterator_test.go

@@ -521,3 +521,54 @@ func TestNodeIteratorLargeTrie(t *testing.T) {
 		t.Fatalf("Too many lookups during seek, have %d want %d", have, want)
 	}
 }
+
+func TestIteratorNodeBlob(t *testing.T) {
+	var (
+		db      = memorydb.New()
+		triedb  = NewDatabase(db)
+		trie, _ = New(common.Hash{}, triedb)
+	)
+	vals := []struct{ k, v string }{
+		{"do", "verb"},
+		{"ether", "wookiedoo"},
+		{"horse", "stallion"},
+		{"shaman", "horse"},
+		{"doge", "coin"},
+		{"dog", "puppy"},
+		{"somethingveryoddindeedthis is", "myothernodedata"},
+	}
+	all := make(map[string]string)
+	for _, val := range vals {
+		all[val.k] = val.v
+		trie.Update([]byte(val.k), []byte(val.v))
+	}
+	trie.Commit(nil)
+	triedb.Cap(0)
+
+	found := make(map[common.Hash][]byte)
+	it := trie.NodeIterator(nil)
+	for it.Next(true) {
+		if it.Hash() == (common.Hash{}) {
+			continue
+		}
+		found[it.Hash()] = it.NodeBlob()
+	}
+
+	dbIter := db.NewIterator(nil, nil)
+	defer dbIter.Release()
+
+	var count int
+	for dbIter.Next() {
+		got, present := found[common.BytesToHash(dbIter.Key())]
+		if !present {
+			t.Fatalf("Miss trie node %v", dbIter.Key())
+		}
+		if !bytes.Equal(got, dbIter.Value()) {
+			t.Fatalf("Unexpected trie node want %v got %v", dbIter.Value(), got)
+		}
+		count += 1
+	}
+	if count != len(found) {
+		t.Fatal("Find extra trie node via iterator")
+	}
+}

trie/trie.go

@@ -514,6 +514,15 @@ func (t *Trie) resolveHash(n hashNode, prefix []byte) (node, error) {
 	return nil, &MissingNodeError{NodeHash: hash, Path: prefix}
 }
 
+func (t *Trie) resolveBlob(n hashNode, prefix []byte) ([]byte, error) {
+	hash := common.BytesToHash(n)
+	blob, _ := t.db.Node(hash)
+	if len(blob) != 0 {
+		return blob, nil
+	}
+	return nil, &MissingNodeError{NodeHash: hash, Path: prefix}
+}
+
 // Hash returns the root hash of the trie. It does not write to the
 // database and can be used even if the trie doesn't have one.
 func (t *Trie) Hash() common.Hash {