mirror of https://github.com/poanetwork/quorum.git
176 lines
5.1 KiB
Go
176 lines
5.1 KiB
Go
// Copyright 2016 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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"bytes"
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"hash"
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"sync"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/crypto/sha3"
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"github.com/ethereum/go-ethereum/rlp"
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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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cachegen, cachelimit uint16
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}
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// hashers live in a global pool.
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var hasherPool = sync.Pool{
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New: func() interface{} {
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return &hasher{tmp: new(bytes.Buffer), sha: sha3.NewKeccak256()}
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},
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}
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func newHasher(cachegen, cachelimit uint16) *hasher {
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h := hasherPool.Get().(*hasher)
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h.cachegen, h.cachelimit = cachegen, cachelimit
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return h
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}
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func returnHasherToPool(h *hasher) {
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hasherPool.Put(h)
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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 {
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if db == nil {
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return hash, n, nil
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}
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if n.canUnload(h.cachegen, h.cachelimit) {
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// Evict the node from cache. All of its subnodes will have a lower or equal
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// cache generation number.
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return hash, hash, nil
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}
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if !dirty {
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return hash, n, nil
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}
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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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}
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hashed, err := h.store(collapsed, db, force)
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if err != nil {
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return hashNode{}, n, err
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}
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// Cache the hash of the ndoe for later reuse.
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if hash, ok := hashed.(hashNode); ok && !force {
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switch cached := cached.(type) {
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case *shortNode:
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cached = cached.copy()
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cached.flags.hash = hash
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if db != nil {
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cached.flags.dirty = false
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}
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return hashed, cached, nil
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case *fullNode:
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cached = cached.copy()
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cached.flags.hash = hash
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if db != nil {
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cached.flags.dirty = false
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}
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return hashed, cached, nil
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}
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}
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return hashed, cached, nil
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}
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// hashChildren replaces the children of a node with their hashes if the encoded
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// size of the child is larger than a hash, returning the collapsed node as well
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// as a replacement for the original node with the child hashes cached in.
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func (h *hasher) hashChildren(original node, db DatabaseWriter) (node, node, error) {
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var err error
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switch n := original.(type) {
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case *shortNode:
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// Hash the short node's child, caching the newly hashed subtree
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collapsed, cached := n.copy(), n.copy()
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collapsed.Key = compactEncode(n.Key)
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cached.Key = common.CopyBytes(n.Key)
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if _, ok := n.Val.(valueNode); !ok {
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collapsed.Val, cached.Val, err = h.hash(n.Val, db, false)
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if err != nil {
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return original, original, err
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}
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}
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if collapsed.Val == nil {
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collapsed.Val = valueNode(nil) // Ensure that nil children are encoded as empty strings.
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}
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return collapsed, cached, nil
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case *fullNode:
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// Hash the full node's children, caching the newly hashed subtrees
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collapsed, cached := n.copy(), n.copy()
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for i := 0; i < 16; i++ {
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if n.Children[i] != nil {
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collapsed.Children[i], cached.Children[i], err = h.hash(n.Children[i], db, false)
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if err != nil {
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return original, original, err
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}
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} else {
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collapsed.Children[i] = valueNode(nil) // Ensure that nil children are encoded as empty strings.
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}
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}
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cached.Children[16] = n.Children[16]
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if collapsed.Children[16] == nil {
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collapsed.Children[16] = valueNode(nil)
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}
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return collapsed, cached, nil
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default:
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// Value and hash nodes don't have children so they're left as were
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return n, original, nil
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}
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}
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func (h *hasher) store(n node, db DatabaseWriter, force bool) (node, error) {
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// Don't store hashes or empty nodes.
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if _, isHash := n.(hashNode); n == nil || isHash {
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return n, nil
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}
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// Generate the RLP encoding of the node
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h.tmp.Reset()
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if err := rlp.Encode(h.tmp, n); err != nil {
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panic("encode error: " + err.Error())
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}
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if h.tmp.Len() < 32 && !force {
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return n, nil // Nodes smaller than 32 bytes are stored inside their parent
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}
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// Larger nodes are replaced by their hash and stored in the database.
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hash, _ := n.cache()
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if hash == nil {
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h.sha.Reset()
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h.sha.Write(h.tmp.Bytes())
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hash = hashNode(h.sha.Sum(nil))
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}
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if db != nil {
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return hash, db.Put(hash, h.tmp.Bytes())
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}
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return hash, nil
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}
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