go-ethereum/trie/stacktrie.go
Paweł Bylica 86fe359a56
trie: simplify StackTrie implementation (#23950)
Trim the search key from head as it's being pushed deeper into the trie. Previously the search key was never modified but each node kept information how to slice and compare it in keyOffset. Now the keyOffset is not needed as this information is included in the slice of the search key. This way the keyOffset can be removed and key manipulation
simplified.
2021-11-29 11:02:40 +01:00

506 lines
13 KiB
Go

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