131 lines
4.3 KiB
Go
131 lines
4.3 KiB
Go
// Copyright 2022 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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"github.com/ethereum/go-ethereum/common"
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)
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// tracer tracks the changes of trie nodes. During the trie operations,
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// some nodes can be deleted from the trie, while these deleted nodes
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// won't be captured by trie.Hasher or trie.Committer. Thus, these deleted
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// nodes won't be removed from the disk at all. Tracer is an auxiliary tool
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// used to track all insert and delete operations of trie and capture all
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// deleted nodes eventually.
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//
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// The changed nodes can be mainly divided into two categories: the leaf
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// node and intermediate node. The former is inserted/deleted by callers
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// while the latter is inserted/deleted in order to follow the rule of trie.
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// This tool can track all of them no matter the node is embedded in its
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// parent or not, but valueNode is never tracked.
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//
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// Besides, it's also used for recording the original value of the nodes
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// when they are resolved from the disk. The pre-value of the nodes will
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// be used to construct trie history in the future.
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//
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// Note tracer is not thread-safe, callers should be responsible for handling
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// the concurrency issues by themselves.
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type tracer struct {
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inserts map[string]struct{}
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deletes map[string]struct{}
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accessList map[string][]byte
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}
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// newTracer initializes the tracer for capturing trie changes.
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func newTracer() *tracer {
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return &tracer{
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inserts: make(map[string]struct{}),
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deletes: make(map[string]struct{}),
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accessList: make(map[string][]byte),
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}
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}
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// onRead tracks the newly loaded trie node and caches the rlp-encoded
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// blob internally. Don't change the value outside of function since
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// it's not deep-copied.
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func (t *tracer) onRead(path []byte, val []byte) {
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t.accessList[string(path)] = val
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}
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// onInsert tracks the newly inserted trie node. If it's already
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// in the deletion set (resurrected node), then just wipe it from
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// the deletion set as it's "untouched".
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func (t *tracer) onInsert(path []byte) {
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if _, present := t.deletes[string(path)]; present {
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delete(t.deletes, string(path))
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return
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}
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t.inserts[string(path)] = struct{}{}
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}
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// onDelete tracks the newly deleted trie node. If it's already
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// in the addition set, then just wipe it from the addition set
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// as it's untouched.
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func (t *tracer) onDelete(path []byte) {
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if _, present := t.inserts[string(path)]; present {
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delete(t.inserts, string(path))
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return
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}
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t.deletes[string(path)] = struct{}{}
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}
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// reset clears the content tracked by tracer.
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func (t *tracer) reset() {
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t.inserts = make(map[string]struct{})
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t.deletes = make(map[string]struct{})
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t.accessList = make(map[string][]byte)
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}
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// copy returns a deep copied tracer instance.
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func (t *tracer) copy() *tracer {
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var (
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inserts = make(map[string]struct{})
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deletes = make(map[string]struct{})
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accessList = make(map[string][]byte)
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)
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for path := range t.inserts {
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inserts[path] = struct{}{}
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}
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for path := range t.deletes {
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deletes[path] = struct{}{}
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}
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for path, blob := range t.accessList {
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accessList[path] = common.CopyBytes(blob)
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}
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return &tracer{
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inserts: inserts,
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deletes: deletes,
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accessList: accessList,
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}
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}
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// deletedNodes returns a list of node paths which are deleted from the trie.
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func (t *tracer) deletedNodes() []string {
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var paths []string
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for path := range t.deletes {
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// It's possible a few deleted nodes were embedded
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// in their parent before, the deletions can be no
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// effect by deleting nothing, filter them out.
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_, ok := t.accessList[path]
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if !ok {
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continue
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}
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paths = append(paths, path)
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}
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return paths
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}
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