514 lines
14 KiB
Go
514 lines
14 KiB
Go
// Copyright 2020 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
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import (
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"bufio"
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"bytes"
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"encoding/gob"
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"errors"
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"fmt"
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"io"
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"sync"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/ethdb"
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"github.com/ethereum/go-ethereum/log"
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"github.com/ethereum/go-ethereum/rlp"
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)
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var ErrCommitDisabled = errors.New("no database for committing")
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var stPool = sync.Pool{
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New: func() interface{} {
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return NewStackTrie(nil)
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},
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}
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func stackTrieFromPool(db ethdb.KeyValueWriter) *StackTrie {
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st := stPool.Get().(*StackTrie)
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st.db = db
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return st
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}
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func returnToPool(st *StackTrie) {
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st.Reset()
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stPool.Put(st)
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}
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// StackTrie is a trie implementation that expects keys to be inserted
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// in order. Once it determines that a subtree will no longer be inserted
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// into, it will hash it and free up the memory it uses.
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type StackTrie struct {
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nodeType uint8 // node type (as in branch, ext, leaf)
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val []byte // value contained by this node if it's a leaf
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key []byte // key chunk covered by this (full|ext) node
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keyOffset int // offset of the key chunk inside a full key
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children [16]*StackTrie // list of children (for fullnodes and exts)
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db ethdb.KeyValueWriter // Pointer to the commit db, can be nil
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}
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// NewStackTrie allocates and initializes an empty trie.
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func NewStackTrie(db ethdb.KeyValueWriter) *StackTrie {
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return &StackTrie{
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nodeType: emptyNode,
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db: db,
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}
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}
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// NewFromBinary initialises a serialized stacktrie with the given db.
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func NewFromBinary(data []byte, db ethdb.KeyValueWriter) (*StackTrie, error) {
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var st StackTrie
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if err := st.UnmarshalBinary(data); err != nil {
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return nil, err
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}
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// If a database is used, we need to recursively add it to every child
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if db != nil {
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st.setDb(db)
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}
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return &st, nil
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}
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// MarshalBinary implements encoding.BinaryMarshaler
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func (st *StackTrie) MarshalBinary() (data []byte, err error) {
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var (
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b bytes.Buffer
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w = bufio.NewWriter(&b)
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)
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if err := gob.NewEncoder(w).Encode(struct {
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Nodetype uint8
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Val []byte
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Key []byte
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KeyOffset uint8
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}{
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st.nodeType,
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st.val,
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st.key,
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uint8(st.keyOffset),
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}); err != nil {
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return nil, err
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}
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for _, child := range st.children {
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if child == nil {
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w.WriteByte(0)
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continue
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}
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w.WriteByte(1)
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if childData, err := child.MarshalBinary(); err != nil {
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return nil, err
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} else {
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w.Write(childData)
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}
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}
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w.Flush()
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return b.Bytes(), nil
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}
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// UnmarshalBinary implements encoding.BinaryUnmarshaler
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func (st *StackTrie) UnmarshalBinary(data []byte) error {
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r := bytes.NewReader(data)
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return st.unmarshalBinary(r)
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}
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func (st *StackTrie) unmarshalBinary(r io.Reader) error {
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var dec struct {
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Nodetype uint8
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Val []byte
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Key []byte
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KeyOffset uint8
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}
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gob.NewDecoder(r).Decode(&dec)
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st.nodeType = dec.Nodetype
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st.val = dec.Val
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st.key = dec.Key
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st.keyOffset = int(dec.KeyOffset)
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var hasChild = make([]byte, 1)
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for i := range st.children {
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if _, err := r.Read(hasChild); err != nil {
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return err
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} else if hasChild[0] == 0 {
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continue
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}
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var child StackTrie
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child.unmarshalBinary(r)
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st.children[i] = &child
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}
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return nil
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}
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func (st *StackTrie) setDb(db ethdb.KeyValueWriter) {
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st.db = db
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for _, child := range st.children {
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if child != nil {
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child.setDb(db)
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}
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}
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}
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func newLeaf(ko int, key, val []byte, db ethdb.KeyValueWriter) *StackTrie {
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st := stackTrieFromPool(db)
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st.nodeType = leafNode
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st.keyOffset = ko
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st.key = append(st.key, key[ko:]...)
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st.val = val
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return st
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}
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func newExt(ko int, key []byte, child *StackTrie, db ethdb.KeyValueWriter) *StackTrie {
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st := stackTrieFromPool(db)
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st.nodeType = extNode
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st.keyOffset = ko
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st.key = append(st.key, key[ko:]...)
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st.children[0] = child
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return st
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}
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// List all values that StackTrie#nodeType can hold
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const (
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emptyNode = iota
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branchNode
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extNode
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leafNode
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hashedNode
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)
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// TryUpdate inserts a (key, value) pair into the stack trie
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func (st *StackTrie) TryUpdate(key, value []byte) error {
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k := keybytesToHex(key)
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if len(value) == 0 {
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panic("deletion not supported")
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}
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st.insert(k[:len(k)-1], value)
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return nil
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}
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func (st *StackTrie) Update(key, value []byte) {
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if err := st.TryUpdate(key, value); err != nil {
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log.Error(fmt.Sprintf("Unhandled trie error: %v", err))
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}
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}
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func (st *StackTrie) Reset() {
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st.db = nil
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st.key = st.key[:0]
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st.val = nil
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for i := range st.children {
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st.children[i] = nil
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}
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st.nodeType = emptyNode
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st.keyOffset = 0
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}
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// Helper function that, given a full key, determines the index
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// at which the chunk pointed by st.keyOffset is different from
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// the same chunk in the full key.
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func (st *StackTrie) getDiffIndex(key []byte) int {
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diffindex := 0
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for ; diffindex < len(st.key) && st.key[diffindex] == key[st.keyOffset+diffindex]; diffindex++ {
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}
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return diffindex
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}
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// Helper function to that inserts a (key, value) pair into
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// the trie.
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func (st *StackTrie) insert(key, value []byte) {
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switch st.nodeType {
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case branchNode: /* Branch */
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idx := int(key[st.keyOffset])
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// Unresolve elder siblings
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for i := idx - 1; i >= 0; i-- {
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if st.children[i] != nil {
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if st.children[i].nodeType != hashedNode {
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st.children[i].hash()
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}
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break
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}
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}
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// Add new child
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if st.children[idx] == nil {
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st.children[idx] = stackTrieFromPool(st.db)
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st.children[idx].keyOffset = st.keyOffset + 1
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}
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st.children[idx].insert(key, value)
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case extNode: /* Ext */
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// Compare both key chunks and see where they differ
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diffidx := st.getDiffIndex(key)
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// Check if chunks are identical. If so, recurse into
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// the child node. Otherwise, the key has to be split
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// into 1) an optional common prefix, 2) the fullnode
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// representing the two differing path, and 3) a leaf
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// for each of the differentiated subtrees.
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if diffidx == len(st.key) {
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// Ext key and key segment are identical, recurse into
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// the child node.
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st.children[0].insert(key, value)
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return
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}
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// Save the original part. Depending if the break is
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// at the extension's last byte or not, create an
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// intermediate extension or use the extension's child
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// node directly.
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var n *StackTrie
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if diffidx < len(st.key)-1 {
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n = newExt(diffidx+1, st.key, st.children[0], st.db)
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} else {
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// Break on the last byte, no need to insert
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// an extension node: reuse the current node
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n = st.children[0]
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}
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// Convert to hash
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n.hash()
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var p *StackTrie
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if diffidx == 0 {
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// the break is on the first byte, so
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// the current node is converted into
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// a branch node.
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st.children[0] = nil
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p = st
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st.nodeType = branchNode
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} else {
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// the common prefix is at least one byte
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// long, insert a new intermediate branch
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// node.
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st.children[0] = stackTrieFromPool(st.db)
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st.children[0].nodeType = branchNode
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st.children[0].keyOffset = st.keyOffset + diffidx
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p = st.children[0]
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}
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// Create a leaf for the inserted part
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o := newLeaf(st.keyOffset+diffidx+1, key, value, st.db)
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// Insert both child leaves where they belong:
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origIdx := st.key[diffidx]
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newIdx := key[diffidx+st.keyOffset]
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p.children[origIdx] = n
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p.children[newIdx] = o
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st.key = st.key[:diffidx]
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case leafNode: /* Leaf */
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// Compare both key chunks and see where they differ
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diffidx := st.getDiffIndex(key)
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// Overwriting a key isn't supported, which means that
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// the current leaf is expected to be split into 1) an
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// optional extension for the common prefix of these 2
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// keys, 2) a fullnode selecting the path on which the
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// keys differ, and 3) one leaf for the differentiated
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// component of each key.
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if diffidx >= len(st.key) {
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panic("Trying to insert into existing key")
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}
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// Check if the split occurs at the first nibble of the
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// chunk. In that case, no prefix extnode is necessary.
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// Otherwise, create that
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var p *StackTrie
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if diffidx == 0 {
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// Convert current leaf into a branch
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st.nodeType = branchNode
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p = st
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st.children[0] = nil
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} else {
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// Convert current node into an ext,
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// and insert a child branch node.
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st.nodeType = extNode
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st.children[0] = NewStackTrie(st.db)
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st.children[0].nodeType = branchNode
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st.children[0].keyOffset = st.keyOffset + diffidx
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p = st.children[0]
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}
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// Create the two child leaves: the one containing the
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// original value and the one containing the new value
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// The child leave will be hashed directly in order to
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// free up some memory.
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origIdx := st.key[diffidx]
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p.children[origIdx] = newLeaf(diffidx+1, st.key, st.val, st.db)
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p.children[origIdx].hash()
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newIdx := key[diffidx+st.keyOffset]
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p.children[newIdx] = newLeaf(p.keyOffset+1, key, value, st.db)
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// Finally, cut off the key part that has been passed
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// over to the children.
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st.key = st.key[:diffidx]
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st.val = nil
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case emptyNode: /* Empty */
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st.nodeType = leafNode
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st.key = key[st.keyOffset:]
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st.val = value
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case hashedNode:
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panic("trying to insert into hash")
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default:
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panic("invalid type")
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}
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}
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// hash() hashes the node 'st' and converts it into 'hashedNode', if possible.
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// Possible outcomes:
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// 1. The rlp-encoded value was >= 32 bytes:
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// - Then the 32-byte `hash` will be accessible in `st.val`.
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// - And the 'st.type' will be 'hashedNode'
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// 2. The rlp-encoded value was < 32 bytes
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// - Then the <32 byte rlp-encoded value will be accessible in 'st.val'.
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// - And the 'st.type' will be 'hashedNode' AGAIN
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//
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// This method will also:
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// set 'st.type' to hashedNode
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// clear 'st.key'
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func (st *StackTrie) hash() {
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/* Shortcut if node is already hashed */
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if st.nodeType == hashedNode {
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return
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}
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// The 'hasher' is taken from a pool, but we don't actually
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// claim an instance until all children are done with their hashing,
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// and we actually need one
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var h *hasher
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switch st.nodeType {
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case branchNode:
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var nodes [17]node
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for i, child := range st.children {
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if child == nil {
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nodes[i] = nilValueNode
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continue
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}
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child.hash()
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if len(child.val) < 32 {
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nodes[i] = rawNode(child.val)
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} else {
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nodes[i] = hashNode(child.val)
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}
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st.children[i] = nil // Reclaim mem from subtree
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returnToPool(child)
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}
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nodes[16] = nilValueNode
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h = newHasher(false)
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defer returnHasherToPool(h)
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h.tmp.Reset()
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if err := rlp.Encode(&h.tmp, nodes); err != nil {
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panic(err)
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}
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case extNode:
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st.children[0].hash()
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h = newHasher(false)
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defer returnHasherToPool(h)
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h.tmp.Reset()
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var valuenode node
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if len(st.children[0].val) < 32 {
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valuenode = rawNode(st.children[0].val)
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} else {
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valuenode = hashNode(st.children[0].val)
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}
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n := struct {
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Key []byte
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Val node
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}{
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Key: hexToCompact(st.key),
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Val: valuenode,
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}
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if err := rlp.Encode(&h.tmp, n); err != nil {
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panic(err)
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}
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returnToPool(st.children[0])
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st.children[0] = nil // Reclaim mem from subtree
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case leafNode:
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h = newHasher(false)
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defer returnHasherToPool(h)
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h.tmp.Reset()
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st.key = append(st.key, byte(16))
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sz := hexToCompactInPlace(st.key)
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n := [][]byte{st.key[:sz], st.val}
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if err := rlp.Encode(&h.tmp, n); err != nil {
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panic(err)
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}
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case emptyNode:
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st.val = emptyRoot.Bytes()
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st.key = st.key[:0]
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st.nodeType = hashedNode
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return
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default:
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panic("Invalid node type")
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}
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st.key = st.key[:0]
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st.nodeType = hashedNode
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if len(h.tmp) < 32 {
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st.val = common.CopyBytes(h.tmp)
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return
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}
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// Write the hash to the 'val'. We allocate a new val here to not mutate
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// input values
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st.val = make([]byte, 32)
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h.sha.Reset()
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h.sha.Write(h.tmp)
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h.sha.Read(st.val)
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if st.db != nil {
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// TODO! Is it safe to Put the slice here?
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// Do all db implementations copy the value provided?
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st.db.Put(st.val, h.tmp)
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}
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}
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// Hash returns the hash of the current node
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func (st *StackTrie) Hash() (h common.Hash) {
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st.hash()
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if len(st.val) != 32 {
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// If the node's RLP isn't 32 bytes long, the node will not
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// be hashed, and instead contain the rlp-encoding of the
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// node. For the top level node, we need to force the hashing.
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ret := make([]byte, 32)
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h := newHasher(false)
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defer returnHasherToPool(h)
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h.sha.Reset()
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h.sha.Write(st.val)
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h.sha.Read(ret)
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return common.BytesToHash(ret)
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}
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return common.BytesToHash(st.val)
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}
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// Commit will firstly hash the entrie trie if it's still not hashed
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// and then commit all nodes to the associated database. Actually most
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// of the trie nodes MAY have been committed already. The main purpose
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// here is to commit the root node.
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//
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// The associated database is expected, otherwise the whole commit
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// functionality should be disabled.
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func (st *StackTrie) Commit() (common.Hash, error) {
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if st.db == nil {
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return common.Hash{}, ErrCommitDisabled
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}
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st.hash()
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if len(st.val) != 32 {
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// If the node's RLP isn't 32 bytes long, the node will not
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// be hashed (and committed), and instead contain the rlp-encoding of the
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// node. For the top level node, we need to force the hashing+commit.
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ret := make([]byte, 32)
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h := newHasher(false)
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defer returnHasherToPool(h)
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h.sha.Reset()
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h.sha.Write(st.val)
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h.sha.Read(ret)
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st.db.Put(ret, st.val)
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return common.BytesToHash(ret), nil
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}
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return common.BytesToHash(st.val), nil
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}
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