601 lines
17 KiB
Go
601 lines
17 KiB
Go
// Copyright 2014 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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// Package trie implements Merkle Patricia Tries.
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package trie
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import (
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"bytes"
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"fmt"
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"hash"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/crypto"
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"github.com/ethereum/go-ethereum/crypto/sha3"
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"github.com/ethereum/go-ethereum/logger"
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"github.com/ethereum/go-ethereum/logger/glog"
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"github.com/ethereum/go-ethereum/rlp"
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)
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const defaultCacheCapacity = 800
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var (
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// The global cache stores decoded trie nodes by hash as they get loaded.
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globalCache = newARC(defaultCacheCapacity)
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// This is the known root hash of an empty trie.
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emptyRoot = common.HexToHash("56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421")
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// This is the known hash of an empty state trie entry.
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emptyState = crypto.Keccak256Hash(nil)
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)
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// ClearGlobalCache clears the global trie cache
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func ClearGlobalCache() {
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globalCache.Clear()
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}
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// Database must be implemented by backing stores for the trie.
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type Database interface {
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DatabaseWriter
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// Get returns the value for key from the database.
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Get(key []byte) (value []byte, err error)
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}
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// DatabaseWriter wraps the Put method of a backing store for the trie.
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type DatabaseWriter interface {
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// Put stores the mapping key->value in the database.
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// Implementations must not hold onto the value bytes, the trie
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// will reuse the slice across calls to Put.
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Put(key, value []byte) error
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}
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// Trie is a Merkle Patricia Trie.
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// The zero value is an empty trie with no database.
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// Use New to create a trie that sits on top of a database.
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//
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// Trie is not safe for concurrent use.
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type Trie struct {
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root node
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db Database
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originalRoot common.Hash
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*hasher
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}
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// New creates a trie with an existing root node from db.
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//
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// If root is the zero hash or the sha3 hash of an empty string, the
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// trie is initially empty and does not require a database. Otherwise,
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// New will panic if db is nil and returns a MissingNodeError if root does
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// not exist in the database. Accessing the trie loads nodes from db on demand.
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func New(root common.Hash, db Database) (*Trie, error) {
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trie := &Trie{db: db, originalRoot: root}
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if (root != common.Hash{}) && root != emptyRoot {
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if db == nil {
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panic("trie.New: cannot use existing root without a database")
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}
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if v, _ := trie.db.Get(root[:]); len(v) == 0 {
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return nil, &MissingNodeError{
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RootHash: root,
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NodeHash: root,
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}
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}
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trie.root = hashNode(root.Bytes())
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}
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return trie, nil
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}
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// Iterator returns an iterator over all mappings in the trie.
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func (t *Trie) Iterator() *Iterator {
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return NewIterator(t)
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}
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// Get returns the value for key stored in the trie.
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// The value bytes must not be modified by the caller.
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func (t *Trie) Get(key []byte) []byte {
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res, err := t.TryGet(key)
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if err != nil && glog.V(logger.Error) {
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glog.Errorf("Unhandled trie error: %v", err)
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}
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return res
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}
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// TryGet returns the value for key stored in the trie.
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// The value bytes must not be modified by the caller.
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// If a node was not found in the database, a MissingNodeError is returned.
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func (t *Trie) TryGet(key []byte) ([]byte, error) {
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key = compactHexDecode(key)
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pos := 0
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tn := t.root
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for pos < len(key) {
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switch n := tn.(type) {
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case shortNode:
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if len(key)-pos < len(n.Key) || !bytes.Equal(n.Key, key[pos:pos+len(n.Key)]) {
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return nil, nil
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}
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tn = n.Val
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pos += len(n.Key)
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case fullNode:
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tn = n.Children[key[pos]]
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pos++
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case nil:
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return nil, nil
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case hashNode:
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var err error
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tn, err = t.resolveHash(n, key[:pos], key[pos:])
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if err != nil {
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return nil, err
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}
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default:
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panic(fmt.Sprintf("%T: invalid node: %v", tn, tn))
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}
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}
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return tn.(valueNode), nil
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}
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// Update associates key with value in the trie. Subsequent calls to
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// Get will return value. If value has length zero, any existing value
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// is deleted from the trie and calls to Get will return nil.
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//
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// The value bytes must not be modified by the caller while they are
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// stored in the trie.
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func (t *Trie) Update(key, value []byte) {
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if err := t.TryUpdate(key, value); err != nil && glog.V(logger.Error) {
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glog.Errorf("Unhandled trie error: %v", err)
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}
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}
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// TryUpdate associates key with value in the trie. Subsequent calls to
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// Get will return value. If value has length zero, any existing value
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// is deleted from the trie and calls to Get will return nil.
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//
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// The value bytes must not be modified by the caller while they are
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// stored in the trie.
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//
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// If a node was not found in the database, a MissingNodeError is returned.
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func (t *Trie) TryUpdate(key, value []byte) error {
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k := compactHexDecode(key)
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if len(value) != 0 {
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_, n, err := t.insert(t.root, nil, k, valueNode(value))
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if err != nil {
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return err
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}
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t.root = n
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} else {
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_, n, err := t.delete(t.root, nil, k)
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if err != nil {
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return err
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}
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t.root = n
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}
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return nil
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}
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func (t *Trie) insert(n node, prefix, key []byte, value node) (bool, node, error) {
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if len(key) == 0 {
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if v, ok := n.(valueNode); ok {
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return !bytes.Equal(v, value.(valueNode)), value, nil
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}
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return true, value, nil
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}
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switch n := n.(type) {
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case shortNode:
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matchlen := prefixLen(key, n.Key)
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// If the whole key matches, keep this short node as is
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// and only update the value.
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if matchlen == len(n.Key) {
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dirty, nn, err := t.insert(n.Val, append(prefix, key[:matchlen]...), key[matchlen:], value)
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if err != nil {
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return false, nil, err
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}
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if !dirty {
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return false, n, nil
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}
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return true, shortNode{n.Key, nn, nil, true}, nil
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}
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// Otherwise branch out at the index where they differ.
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branch := fullNode{dirty: true}
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var err error
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_, branch.Children[n.Key[matchlen]], err = t.insert(nil, append(prefix, n.Key[:matchlen+1]...), n.Key[matchlen+1:], n.Val)
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if err != nil {
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return false, nil, err
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}
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_, branch.Children[key[matchlen]], err = t.insert(nil, append(prefix, key[:matchlen+1]...), key[matchlen+1:], value)
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if err != nil {
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return false, nil, err
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}
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// Replace this shortNode with the branch if it occurs at index 0.
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if matchlen == 0 {
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return true, branch, nil
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}
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// Otherwise, replace it with a short node leading up to the branch.
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return true, shortNode{key[:matchlen], branch, nil, true}, nil
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case fullNode:
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dirty, nn, err := t.insert(n.Children[key[0]], append(prefix, key[0]), key[1:], value)
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if err != nil {
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return false, nil, err
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}
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if !dirty {
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return false, n, nil
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}
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n.Children[key[0]], n.hash, n.dirty = nn, nil, true
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return true, n, nil
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case nil:
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return true, shortNode{key, value, nil, true}, nil
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case hashNode:
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// We've hit a part of the trie that isn't loaded yet. Load
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// the node and insert into it. This leaves all child nodes on
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// the path to the value in the trie.
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rn, err := t.resolveHash(n, prefix, key)
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if err != nil {
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return false, nil, err
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}
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dirty, nn, err := t.insert(rn, prefix, key, value)
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if err != nil {
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return false, nil, err
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}
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if !dirty {
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return false, rn, nil
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}
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return true, nn, nil
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default:
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panic(fmt.Sprintf("%T: invalid node: %v", n, n))
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}
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}
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// Delete removes any existing value for key from the trie.
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func (t *Trie) Delete(key []byte) {
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if err := t.TryDelete(key); err != nil && glog.V(logger.Error) {
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glog.Errorf("Unhandled trie error: %v", err)
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}
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}
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// TryDelete removes any existing value for key from the trie.
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// If a node was not found in the database, a MissingNodeError is returned.
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func (t *Trie) TryDelete(key []byte) error {
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k := compactHexDecode(key)
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_, n, err := t.delete(t.root, nil, k)
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if err != nil {
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return err
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}
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t.root = n
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return nil
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}
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// delete returns the new root of the trie with key deleted.
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// It reduces the trie to minimal form by simplifying
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// nodes on the way up after deleting recursively.
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func (t *Trie) delete(n node, prefix, key []byte) (bool, node, error) {
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switch n := n.(type) {
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case shortNode:
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matchlen := prefixLen(key, n.Key)
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if matchlen < len(n.Key) {
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return false, n, nil // don't replace n on mismatch
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}
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if matchlen == len(key) {
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return true, nil, nil // remove n entirely for whole matches
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}
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// The key is longer than n.Key. Remove the remaining suffix
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// from the subtrie. Child can never be nil here since the
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// subtrie must contain at least two other values with keys
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// longer than n.Key.
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dirty, child, err := t.delete(n.Val, append(prefix, key[:len(n.Key)]...), key[len(n.Key):])
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if err != nil {
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return false, nil, err
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}
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if !dirty {
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return false, n, nil
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}
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switch child := child.(type) {
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case shortNode:
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// Deleting from the subtrie reduced it to another
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// short node. Merge the nodes to avoid creating a
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// shortNode{..., shortNode{...}}. Use concat (which
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// always creates a new slice) instead of append to
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// avoid modifying n.Key since it might be shared with
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// other nodes.
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return true, shortNode{concat(n.Key, child.Key...), child.Val, nil, true}, nil
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default:
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return true, shortNode{n.Key, child, nil, true}, nil
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}
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case fullNode:
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dirty, nn, err := t.delete(n.Children[key[0]], append(prefix, key[0]), key[1:])
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if err != nil {
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return false, nil, err
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}
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if !dirty {
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return false, n, nil
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}
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n.Children[key[0]], n.hash, n.dirty = nn, nil, true
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// Check how many non-nil entries are left after deleting and
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// reduce the full node to a short node if only one entry is
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// left. Since n must've contained at least two children
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// before deletion (otherwise it would not be a full node) n
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// can never be reduced to nil.
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//
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// When the loop is done, pos contains the index of the single
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// value that is left in n or -2 if n contains at least two
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// values.
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pos := -1
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for i, cld := range n.Children {
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if cld != nil {
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if pos == -1 {
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pos = i
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} else {
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pos = -2
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break
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}
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}
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}
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if pos >= 0 {
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if pos != 16 {
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// If the remaining entry is a short node, it replaces
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// n and its key gets the missing nibble tacked to the
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// front. This avoids creating an invalid
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// shortNode{..., shortNode{...}}. Since the entry
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// might not be loaded yet, resolve it just for this
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// check.
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cnode, err := t.resolve(n.Children[pos], prefix, []byte{byte(pos)})
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if err != nil {
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return false, nil, err
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}
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if cnode, ok := cnode.(shortNode); ok {
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k := append([]byte{byte(pos)}, cnode.Key...)
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return true, shortNode{k, cnode.Val, nil, true}, nil
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}
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}
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// Otherwise, n is replaced by a one-nibble short node
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// containing the child.
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return true, shortNode{[]byte{byte(pos)}, n.Children[pos], nil, true}, nil
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}
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// n still contains at least two values and cannot be reduced.
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return true, n, nil
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case nil:
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return false, nil, nil
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case hashNode:
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// We've hit a part of the trie that isn't loaded yet. Load
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// the node and delete from it. This leaves all child nodes on
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// the path to the value in the trie.
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rn, err := t.resolveHash(n, prefix, key)
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if err != nil {
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return false, nil, err
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}
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dirty, nn, err := t.delete(rn, prefix, key)
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if err != nil {
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return false, nil, err
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}
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if !dirty {
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return false, rn, nil
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}
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return true, nn, nil
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default:
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panic(fmt.Sprintf("%T: invalid node: %v (%v)", n, n, key))
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}
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}
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func concat(s1 []byte, s2 ...byte) []byte {
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r := make([]byte, len(s1)+len(s2))
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copy(r, s1)
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copy(r[len(s1):], s2)
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return r
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}
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func (t *Trie) resolve(n node, prefix, suffix []byte) (node, error) {
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if n, ok := n.(hashNode); ok {
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return t.resolveHash(n, prefix, suffix)
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}
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return n, nil
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}
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func (t *Trie) resolveHash(n hashNode, prefix, suffix []byte) (node, error) {
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if v, ok := globalCache.Get(n); ok {
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return v, nil
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}
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enc, err := t.db.Get(n)
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if err != nil || enc == nil {
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return nil, &MissingNodeError{
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RootHash: t.originalRoot,
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NodeHash: common.BytesToHash(n),
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Key: compactHexEncode(append(prefix, suffix...)),
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PrefixLen: len(prefix),
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SuffixLen: len(suffix),
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}
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}
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dec := mustDecodeNode(n, enc)
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if dec != nil {
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globalCache.Put(n, dec)
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}
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return dec, nil
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}
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// Root returns the root hash of the trie.
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// Deprecated: use Hash instead.
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func (t *Trie) Root() []byte { return t.Hash().Bytes() }
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// Hash returns the root hash of the trie. It does not write to the
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// database and can be used even if the trie doesn't have one.
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func (t *Trie) Hash() common.Hash {
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hash, cached, _ := t.hashRoot(nil)
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t.root = cached
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return common.BytesToHash(hash.(hashNode))
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}
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// Commit writes all nodes to the trie's database.
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// Nodes are stored with their sha3 hash as the key.
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//
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// Committing flushes nodes from memory.
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// Subsequent Get calls will load nodes from the database.
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func (t *Trie) Commit() (root common.Hash, err error) {
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if t.db == nil {
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panic("Commit called on trie with nil database")
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}
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return t.CommitTo(t.db)
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}
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// CommitTo writes all nodes to the given database.
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// Nodes are stored with their sha3 hash as the key.
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//
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// Committing flushes nodes from memory. Subsequent Get calls will
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// load nodes from the trie's database. Calling code must ensure that
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// the changes made to db are written back to the trie's attached
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// database before using the trie.
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func (t *Trie) CommitTo(db DatabaseWriter) (root common.Hash, err error) {
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hash, cached, err := t.hashRoot(db)
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if err != nil {
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return (common.Hash{}), err
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}
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t.root = cached
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return common.BytesToHash(hash.(hashNode)), nil
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}
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func (t *Trie) hashRoot(db DatabaseWriter) (node, node, error) {
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if t.root == nil {
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return hashNode(emptyRoot.Bytes()), nil, nil
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}
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if t.hasher == nil {
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t.hasher = newHasher()
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}
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return t.hasher.hash(t.root, db, true)
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}
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type hasher struct {
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tmp *bytes.Buffer
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sha hash.Hash
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}
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func newHasher() *hasher {
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return &hasher{tmp: new(bytes.Buffer), sha: sha3.NewKeccak256()}
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}
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// hash collapses a node down into a hash node, also returning a copy of the
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// original node initialzied with the computed hash to replace the original one.
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func (h *hasher) hash(n node, db DatabaseWriter, force bool) (node, node, error) {
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// If we're not storing the node, just hashing, use avaialble cached data
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if hash, dirty := n.cache(); hash != nil && (db == nil || !dirty) {
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return hash, n, nil
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}
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// Trie not processed yet or needs storage, walk the children
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collapsed, cached, err := h.hashChildren(n, db)
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if err != nil {
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return hashNode{}, n, err
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}
|
|
hashed, err := h.store(collapsed, db, force)
|
|
if err != nil {
|
|
return hashNode{}, n, err
|
|
}
|
|
// Cache the hash and RLP blob of the ndoe for later reuse
|
|
if hash, ok := hashed.(hashNode); ok && !force {
|
|
switch cached := cached.(type) {
|
|
case shortNode:
|
|
cached.hash = hash
|
|
if db != nil {
|
|
cached.dirty = false
|
|
}
|
|
return hashed, cached, nil
|
|
case fullNode:
|
|
cached.hash = hash
|
|
if db != nil {
|
|
cached.dirty = false
|
|
}
|
|
return hashed, cached, nil
|
|
}
|
|
}
|
|
return hashed, cached, nil
|
|
}
|
|
|
|
// hashChildren replaces the children of a node with their hashes if the encoded
|
|
// size of the child is larger than a hash, returning the collapsed node as well
|
|
// as a replacement for the original node with the child hashes cached in.
|
|
func (h *hasher) hashChildren(original node, db DatabaseWriter) (node, node, error) {
|
|
var err error
|
|
|
|
switch n := original.(type) {
|
|
case shortNode:
|
|
// Hash the short node's child, caching the newly hashed subtree
|
|
cached := n
|
|
cached.Key = common.CopyBytes(cached.Key)
|
|
|
|
n.Key = compactEncode(n.Key)
|
|
if _, ok := n.Val.(valueNode); !ok {
|
|
if n.Val, cached.Val, err = h.hash(n.Val, db, false); err != nil {
|
|
return n, original, err
|
|
}
|
|
}
|
|
if n.Val == nil {
|
|
n.Val = valueNode(nil) // Ensure that nil children are encoded as empty strings.
|
|
}
|
|
return n, cached, nil
|
|
|
|
case fullNode:
|
|
// Hash the full node's children, caching the newly hashed subtrees
|
|
cached := fullNode{dirty: n.dirty}
|
|
|
|
for i := 0; i < 16; i++ {
|
|
if n.Children[i] != nil {
|
|
if n.Children[i], cached.Children[i], err = h.hash(n.Children[i], db, false); err != nil {
|
|
return n, original, err
|
|
}
|
|
} else {
|
|
n.Children[i] = valueNode(nil) // Ensure that nil children are encoded as empty strings.
|
|
}
|
|
}
|
|
cached.Children[16] = n.Children[16]
|
|
if n.Children[16] == nil {
|
|
n.Children[16] = valueNode(nil)
|
|
}
|
|
return n, cached, nil
|
|
|
|
default:
|
|
// Value and hash nodes don't have children so they're left as were
|
|
return n, original, nil
|
|
}
|
|
}
|
|
|
|
func (h *hasher) store(n node, db DatabaseWriter, force bool) (node, error) {
|
|
// Don't store hashes or empty nodes.
|
|
if _, isHash := n.(hashNode); n == nil || isHash {
|
|
return n, nil
|
|
}
|
|
// Generate the RLP encoding of the node
|
|
h.tmp.Reset()
|
|
if err := rlp.Encode(h.tmp, n); err != nil {
|
|
panic("encode error: " + err.Error())
|
|
}
|
|
if h.tmp.Len() < 32 && !force {
|
|
return n, nil // Nodes smaller than 32 bytes are stored inside their parent
|
|
}
|
|
// Larger nodes are replaced by their hash and stored in the database.
|
|
hash, _ := n.cache()
|
|
if hash == nil {
|
|
h.sha.Reset()
|
|
h.sha.Write(h.tmp.Bytes())
|
|
hash = hashNode(h.sha.Sum(nil))
|
|
}
|
|
if db != nil {
|
|
return hash, db.Put(hash, h.tmp.Bytes())
|
|
}
|
|
return hash, nil
|
|
}
|