Official Go implementation of the Ethereum protocol
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go-ethereum/trie/committer.go

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5.7 KiB

// 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 (
"fmt"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/trie/trienode"
)
// committer is the tool used for the trie Commit operation. The committer will
// capture all dirty nodes during the commit process and keep them cached in
// insertion order.
type committer struct {
nodes *trienode.NodeSet
tracer *tracer
collectLeaf bool
}
// newCommitter creates a new committer or picks one from the pool.
func newCommitter(nodeset *trienode.NodeSet, tracer *tracer, collectLeaf bool) *committer {
return &committer{
nodes: nodeset,
tracer: tracer,
collectLeaf: collectLeaf,
}
}
// Commit collapses a node down into a hash node.
func (c *committer) Commit(n node) hashNode {
return c.commit(nil, n).(hashNode)
}
// commit collapses a node down into a hash node and returns it.
func (c *committer) commit(path []byte, n node) node {
// if this path is clean, use available cached data
hash, dirty := n.cache()
if hash != nil && !dirty {
return hash
}
// Commit children, then parent, and remove the dirty flag.
switch cn := n.(type) {
case *shortNode:
// Commit child
collapsed := cn.copy()
// If the child is fullNode, recursively commit,
// otherwise it can only be hashNode or valueNode.
if _, ok := cn.Val.(*fullNode); ok {
collapsed.Val = c.commit(append(path, cn.Key...), cn.Val)
}
// The key needs to be copied, since we're adding it to the
// modified nodeset.
collapsed.Key = hexToCompact(cn.Key)
hashedNode := c.store(path, collapsed)
if hn, ok := hashedNode.(hashNode); ok {
return hn
}
return collapsed
case *fullNode:
hashedKids := c.commitChildren(path, cn)
collapsed := cn.copy()
collapsed.Children = hashedKids
hashedNode := c.store(path, collapsed)
if hn, ok := hashedNode.(hashNode); ok {
return hn
}
return collapsed
case hashNode:
return cn
default:
// nil, valuenode shouldn't be committed
panic(fmt.Sprintf("%T: invalid node: %v", n, n))
}
}
// commitChildren commits the children of the given fullnode
func (c *committer) commitChildren(path []byte, n *fullNode) [17]node {
var children [17]node
for i := 0; i < 16; i++ {
child := n.Children[i]
if child == nil {
continue
}
// If it's the hashed child, save the hash value directly.
// Note: it's impossible that the child in range [0, 15]
// is a valueNode.
if hn, ok := child.(hashNode); ok {
children[i] = hn
continue
}
// Commit the child recursively and store the "hashed" value.
// Note the returned node can be some embedded nodes, so it's
// possible the type is not hashNode.
children[i] = c.commit(append(path, byte(i)), child)
}
// For the 17th child, it's possible the type is valuenode.
if n.Children[16] != nil {
children[16] = n.Children[16]
}
return children
}
// store hashes the node n and adds it to the modified nodeset. If leaf collection
// is enabled, leaf nodes will be tracked in the modified nodeset as well.
func (c *committer) store(path []byte, n node) node {
// Larger nodes are replaced by their hash and stored in the database.
var hash, _ = n.cache()
// This was not generated - must be a small node stored in the parent.
// In theory, we should check if the node is leaf here (embedded node
// usually is leaf node). But small value (less than 32bytes) is not
// our target (leaves in account trie only).
if hash == nil {
// The node is embedded in its parent, in other words, this node
// will not be stored in the database independently, mark it as
// deleted only if the node was existent in database before.
_, ok := c.tracer.accessList[string(path)]
if ok {
c.nodes.AddNode(path, trienode.NewDeleted())
}
return n
}
// Collect the dirty node to nodeset for return.
nhash := common.BytesToHash(hash)
c.nodes.AddNode(path, trienode.New(nhash, nodeToBytes(n)))
// Collect the corresponding leaf node if it's required. We don't check
// full node since it's impossible to store value in fullNode. The key
// length of leaves should be exactly same.
if c.collectLeaf {
if sn, ok := n.(*shortNode); ok {
if val, ok := sn.Val.(valueNode); ok {
c.nodes.AddLeaf(nhash, val)
}
}
}
return hash
}
// mptResolver the children resolver in merkle-patricia-tree.
type mptResolver struct{}
// ForEach implements childResolver, decodes the provided node and
// traverses the children inside.
func (resolver mptResolver) ForEach(node []byte, onChild func(common.Hash)) {
forGatherChildren(mustDecodeNodeUnsafe(nil, node), onChild)
}
// forGatherChildren traverses the node hierarchy and invokes the callback
// for all the hashnode children.
func forGatherChildren(n node, onChild func(hash common.Hash)) {
switch n := n.(type) {
case *shortNode:
forGatherChildren(n.Val, onChild)
case *fullNode:
for i := 0; i < 16; i++ {
forGatherChildren(n.Children[i], onChild)
}
case hashNode:
onChild(common.BytesToHash(n))
case valueNode, nil:
default:
panic(fmt.Sprintf("unknown node type: %T", n))
}
}