core/state, trie: add node iterator, test state/trie sync consistency

core/state/iterator.go

@@ -0,0 +1,133 @@
+// Copyright 2015 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package state
+
+import (
+	"bytes"
+	"fmt"
+	"math/big"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/rlp"
+	"github.com/ethereum/go-ethereum/trie"
+)
+
+// NodeIterator is an iterator to traverse the entire state trie post-order,
+// including all of the contract code and contract state tries.
+type NodeIterator struct {
+	state *StateDB // State being iterated
+
+	stateIt *trie.NodeIterator // Primary iterator for the global state trie
+	dataIt  *trie.NodeIterator // Secondary iterator for the data trie of a contract
+	code    []byte             // Source code associated with a contract
+
+	Entry interface{} // Current state entry being iterated (internal representation)
+}
+
+// NewNodeIterator creates an post-order state node iterator.
+func NewNodeIterator(state *StateDB) *NodeIterator {
+	return &NodeIterator{
+		state: state,
+	}
+}
+
+// Next moves the iterator to the next node, returning whether there are any
+// further nodes.
+func (it *NodeIterator) Next() bool {
+	it.step()
+	return it.retrieve()
+}
+
+// step moves the iterator to the next entry of the state trie.
+func (it *NodeIterator) step() {
+	// Abort if we reached the end of the iteration
+	if it.state == nil {
+		return
+	}
+	// Initialize the iterator if we've just started
+	if it.stateIt == nil {
+		it.stateIt = trie.NewNodeIterator(it.state.trie.Trie)
+	}
+	// If we had data nodes previously, we surely have at least state nodes
+	if it.dataIt != nil {
+		if cont := it.dataIt.Next(); !cont {
+			it.dataIt = nil
+		}
+		return
+	}
+	// If we had source code previously, discard that
+	if it.code != nil {
+		it.code = nil
+		return
+	}
+	// Step to the next state trie node, terminating if we're out of nodes
+	if cont := it.stateIt.Next(); !cont {
+		it.state, it.stateIt = nil, nil
+		return
+	}
+	// If the state trie node is an internal entry, leave as is
+	if !it.stateIt.Leaf {
+		return
+	}
+	// Otherwise we've reached an account node, initiate data iteration
+	var account struct {
+		Nonce    uint64
+		Balance  *big.Int
+		Root     common.Hash
+		CodeHash []byte
+	}
+	err := rlp.Decode(bytes.NewReader(it.stateIt.LeafBlob), &account)
+	if err != nil {
+		panic(err)
+	}
+	dataTrie, err := trie.New(account.Root, it.state.db)
+	if err != nil {
+		panic(err)
+	}
+	it.dataIt = trie.NewNodeIterator(dataTrie)
+	if !it.dataIt.Next() {
+		it.dataIt = nil
+	}
+	if bytes.Compare(account.CodeHash, emptyCodeHash) != 0 {
+		it.code, err = it.state.db.Get(account.CodeHash)
+		if err != nil {
+			panic(fmt.Sprintf("code %x: %v", account.CodeHash, err))
+		}
+	}
+}
+
+// retrieve pulls and caches the current state entry the iterator is traversing.
+// The method returns whether there are any more data left for inspection.
+func (it *NodeIterator) retrieve() bool {
+	// Clear out any previously set values
+	it.Entry = nil
+
+	// If the iteration's done, return no available data
+	if it.state == nil {
+		return false
+	}
+	// Otherwise retrieve the current entry
+	switch {
+	case it.dataIt != nil:
+		it.Entry = it.dataIt.Node
+	case it.code != nil:
+		it.Entry = it.code
+	case it.stateIt != nil:
+		it.Entry = it.stateIt.Node
+	}
+	return true
+}