1 files changed, 19 insertions, 6 deletions
diff --git a/ptrie/trie.go b/ptrie/trie.go
index 9fe9ea52a..d8135f36c 100644
--- a/ptrie/trie.go
+++ b/ptrie/trie.go
@@ -19,7 +19,7 @@ func ParanoiaCheck(t1 *Trie, backend Backend) (bool, *Trie) {
 		t2.Update(it.Key, it.Value)
 	}
 
-	return bytes.Compare(t2.Hash(), t1.Hash()) == 0, t2
+	return bytes.Equal(t2.Hash(), t1.Hash()), t2
 }
 
 type Trie struct {
@@ -49,14 +49,17 @@ func (self *Trie) Iterator() *Iterator {
 	return NewIterator(self)
 }
 
+func (self *Trie) Copy() *Trie {
+	return New(self.roothash, self.cache.backend)
+}
+
 // Legacy support
 func (self *Trie) Root() []byte { return self.Hash() }
 func (self *Trie) Hash() []byte {
 	var hash []byte
 	if self.root != nil {
-		//hash = self.root.Hash().([]byte)
 		t := self.root.Hash()
-		if byts, ok := t.([]byte); ok {
+		if byts, ok := t.([]byte); ok && len(byts) > 0 {
 			hash = byts
 		} else {
 			hash = crypto.Sha3(ethutil.Encode(self.root.RlpData()))
@@ -73,6 +76,9 @@ func (self *Trie) Hash() []byte {
 	return hash
 }
 func (self *Trie) Commit() {
+	self.mu.Lock()
+	defer self.mu.Unlock()
+
 	// Hash first
 	self.Hash()
 
@@ -81,10 +87,15 @@ func (self *Trie) Commit() {
 
 // Reset should only be called if the trie has been hashed
 func (self *Trie) Reset() {
+	self.mu.Lock()
+	defer self.mu.Unlock()
+
 	self.cache.Reset()
 
-	revision := self.revisions.Remove(self.revisions.Back()).([]byte)
-	self.roothash = revision
+	if self.revisions.Len() > 0 {
+		revision := self.revisions.Remove(self.revisions.Back()).([]byte)
+		self.roothash = revision
+	}
 	value := ethutil.NewValueFromBytes(self.cache.Get(self.roothash))
 	self.root = self.mknode(value)
 }
@@ -173,7 +184,7 @@ func (self *Trie) insert(node Node, key []byte, value Node) Node {
 		return cpy
 
 	default:
-		panic("Invalid node")
+		panic(fmt.Sprintf("%T: invalid node: %v", node, node))
 	}
 }
 
@@ -274,6 +285,8 @@ func (self *Trie) delete(node Node, key []byte) Node {
 func (self *Trie) mknode(value *ethutil.Value) Node {
 	l := value.Len()
 	switch l {
+	case 0:
+		return nil
 	case 2:
 		return NewShortNode(self, trie.CompactDecode(string(value.Get(0).Bytes())), self.mknode(value.Get(1)))
 	case 17: