4f3ba6742f
The stacktrie is a bit un-untuitive, API-wise: since it mutates input values. Such behaviour is dangerous, and easy to get wrong if the calling code 'forgets' this quirk. The behaviour is fixed by this PR, so that the input values are not modified by the stacktrie. Note: just as with the Trie, the stacktrie still references the live input objects, so it's still _not_ safe to mutate the values form the callsite.
420 lines
12 KiB
Go
420 lines
12 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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"errors"
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"fmt"
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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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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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