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

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7.3 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"
)
// leaf represents a trie leaf node
type leaf struct {
blob []byte // raw blob of leaf
parent common.Hash // the hash of parent node
}
// 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 *NodeSet
tracer *tracer
collectLeaf bool
}
// newCommitter creates a new committer or picks one from the pool.
func newCommitter(owner common.Hash, tracer *tracer, collectLeaf bool) *committer {
return &committer{
nodes: NewNodeSet(owner),
tracer: tracer,
collectLeaf: collectLeaf,
}
}
// Commit collapses a node down into a hash node and returns it along with
// the modified nodeset.
func (c *committer) Commit(n node) (hashNode, *NodeSet, error) {
h, err := c.commit(nil, n)
if err != nil {
return nil, nil, err
}
// Some nodes can be deleted from trie which can't be captured by committer
// itself. Iterate all deleted nodes tracked by tracer and marked them as
// deleted only if they are present in database previously.
for _, path := range c.tracer.deleteList() {
// There are a few possibilities for this scenario(the node is deleted
// but not present in database previously), for example the node was
// embedded in the parent and now deleted from the trie. In this case
// it's noop from database's perspective.
val := c.tracer.getPrev(path)
if len(val) == 0 {
continue
}
c.nodes.markDeleted(path, val)
}
return h.(hashNode), c.nodes, nil
}
// commit collapses a node down into a hash node and returns it.
func (c *committer) commit(path []byte, n node) (node, error) {
// if this path is clean, use available cached data
hash, dirty := n.cache()
if hash != nil && !dirty {
return hash, nil
}
// 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 {
childV, err := c.commit(append(path, cn.Key...), cn.Val)
if err != nil {
return nil, err
}
collapsed.Val = childV
}
// 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, nil
}
// The short node now is embedded in its parent. Mark the node as
// deleted if it's present in database previously. It's equivalent
// as deletion from database's perspective.
if prev := c.tracer.getPrev(path); len(prev) != 0 {
c.nodes.markDeleted(path, prev)
}
return collapsed, nil
case *fullNode:
hashedKids, err := c.commitChildren(path, cn)
if err != nil {
return nil, err
}
collapsed := cn.copy()
collapsed.Children = hashedKids
hashedNode := c.store(path, collapsed)
if hn, ok := hashedNode.(hashNode); ok {
return hn, nil
}
// The full node now is embedded in its parent. Mark the node as
// deleted if it's present in database previously. It's equivalent
// as deletion from database's perspective.
if prev := c.tracer.getPrev(path); len(prev) != 0 {
c.nodes.markDeleted(path, prev)
}
return collapsed, nil
case hashNode:
return cn, nil
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, error) {
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.
hashed, err := c.commit(append(path, byte(i)), child)
if err != nil {
return children, err
}
children[i] = hashed
}
// For the 17th child, it's possible the type is valuenode.
if n.Children[16] != nil {
children[16] = n.Children[16]
}
return children, nil
}
// 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 {
return n
}
// We have the hash already, estimate the RLP encoding-size of the node.
// The size is used for mem tracking, does not need to be exact
var (
size = estimateSize(n)
nhash = common.BytesToHash(hash)
mnode = &memoryNode{
hash: nhash,
node: simplifyNode(n),
size: uint16(size),
}
)
// Collect the dirty node to nodeset for return.
c.nodes.markUpdated(path, mnode, c.tracer.getPrev(path))
// 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(&leaf{blob: val, parent: nhash})
}
}
}
return hash
}
// estimateSize estimates the size of an rlp-encoded node, without actually
// rlp-encoding it (zero allocs). This method has been experimentally tried, and with a trie
// with 1000 leaves, the only errors above 1% are on small shortnodes, where this
// method overestimates by 2 or 3 bytes (e.g. 37 instead of 35)
func estimateSize(n node) int {
switch n := n.(type) {
case *shortNode:
// A short node contains a compacted key, and a value.
return 3 + len(n.Key) + estimateSize(n.Val)
case *fullNode:
// A full node contains up to 16 hashes (some nils), and a key
s := 3
for i := 0; i < 16; i++ {
if child := n.Children[i]; child != nil {
s += estimateSize(child)
} else {
s++
}
}
return s
case valueNode:
return 1 + len(n)
case hashNode:
return 1 + len(n)
default:
panic(fmt.Sprintf("node type %T", n))
}
}