go-ethereum/trie/sync.go
Felix Lange 2cd7a0395d trie: fix regression that linked all downloaded nodes together
The trie sync code links subtries using pointers into node structs.
Since commit 40cdcf1183 nodes are no longer copied when unpacking from
an interface value, causing all nodes to get linked up as the sync
progresses. Fix it by breaking the pointer chain with an explicit copy.
2016-10-15 00:42:52 +02:00

294 lines
9.3 KiB
Go

// Copyright 2015 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 (
"errors"
"fmt"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/ethdb"
"gopkg.in/karalabe/cookiejar.v2/collections/prque"
)
// ErrNotRequested is returned by the trie sync when it's requested to process a
// node it did not request.
var ErrNotRequested = errors.New("not requested")
// request represents a scheduled or already in-flight state retrieval request.
type request struct {
hash common.Hash // Hash of the node data content to retrieve
data []byte // Data content of the node, cached until all subtrees complete
object *node // Target node to populate with retrieved data (hashnode originally)
parents []*request // Parent state nodes referencing this entry (notify all upon completion)
depth int // Depth level within the trie the node is located to prioritise DFS
deps int // Number of dependencies before allowed to commit this node
callback TrieSyncLeafCallback // Callback to invoke if a leaf node it reached on this branch
}
// SyncResult is a simple list to return missing nodes along with their request
// hashes.
type SyncResult struct {
Hash common.Hash // Hash of the originally unknown trie node
Data []byte // Data content of the retrieved node
}
// TrieSyncLeafCallback is a callback type invoked when a trie sync reaches a
// leaf node. It's used by state syncing to check if the leaf node requires some
// further data syncing.
type TrieSyncLeafCallback func(leaf []byte, parent common.Hash) error
// TrieSync is the main state trie synchronisation scheduler, which provides yet
// unknown trie hashes to retrieve, accepts node data associated with said hashes
// and reconstructs the trie step by step until all is done.
type TrieSync struct {
database ethdb.Database // State database for storing all the assembled node data
requests map[common.Hash]*request // Pending requests pertaining to a key hash
queue *prque.Prque // Priority queue with the pending requests
}
// NewTrieSync creates a new trie data download scheduler.
func NewTrieSync(root common.Hash, database ethdb.Database, callback TrieSyncLeafCallback) *TrieSync {
ts := &TrieSync{
database: database,
requests: make(map[common.Hash]*request),
queue: prque.New(),
}
ts.AddSubTrie(root, 0, common.Hash{}, callback)
return ts
}
// AddSubTrie registers a new trie to the sync code, rooted at the designated parent.
func (s *TrieSync) AddSubTrie(root common.Hash, depth int, parent common.Hash, callback TrieSyncLeafCallback) {
// Short circuit if the trie is empty or already known
if root == emptyRoot {
return
}
key := root.Bytes()
blob, _ := s.database.Get(key)
if local, err := decodeNode(key, blob); local != nil && err == nil {
return
}
// Assemble the new sub-trie sync request
node := node(hashNode(root.Bytes()))
req := &request{
object: &node,
hash: root,
depth: depth,
callback: callback,
}
// If this sub-trie has a designated parent, link them together
if parent != (common.Hash{}) {
ancestor := s.requests[parent]
if ancestor == nil {
panic(fmt.Sprintf("sub-trie ancestor not found: %x", parent))
}
ancestor.deps++
req.parents = append(req.parents, ancestor)
}
s.schedule(req)
}
// AddRawEntry schedules the direct retrieval of a state entry that should not be
// interpreted as a trie node, but rather accepted and stored into the database
// as is. This method's goal is to support misc state metadata retrievals (e.g.
// contract code).
func (s *TrieSync) AddRawEntry(hash common.Hash, depth int, parent common.Hash) {
// Short circuit if the entry is empty or already known
if hash == emptyState {
return
}
if blob, _ := s.database.Get(hash.Bytes()); blob != nil {
return
}
// Assemble the new sub-trie sync request
req := &request{
hash: hash,
depth: depth,
}
// If this sub-trie has a designated parent, link them together
if parent != (common.Hash{}) {
ancestor := s.requests[parent]
if ancestor == nil {
panic(fmt.Sprintf("raw-entry ancestor not found: %x", parent))
}
ancestor.deps++
req.parents = append(req.parents, ancestor)
}
s.schedule(req)
}
// Missing retrieves the known missing nodes from the trie for retrieval.
func (s *TrieSync) Missing(max int) []common.Hash {
requests := []common.Hash{}
for !s.queue.Empty() && (max == 0 || len(requests) < max) {
requests = append(requests, s.queue.PopItem().(common.Hash))
}
return requests
}
// Process injects a batch of retrieved trie nodes data.
func (s *TrieSync) Process(results []SyncResult) (int, error) {
for i, item := range results {
// If the item was not requested, bail out
request := s.requests[item.Hash]
if request == nil {
return i, ErrNotRequested
}
// If the item is a raw entry request, commit directly
if request.object == nil {
request.data = item.Data
s.commit(request, nil)
continue
}
// Decode the node data content and update the request
node, err := decodeNode(item.Hash[:], item.Data)
if err != nil {
return i, err
}
*request.object = node
request.data = item.Data
// Create and schedule a request for all the children nodes
requests, err := s.children(request)
if err != nil {
return i, err
}
if len(requests) == 0 && request.deps == 0 {
s.commit(request, nil)
continue
}
request.deps += len(requests)
for _, child := range requests {
s.schedule(child)
}
}
return 0, nil
}
// Pending returns the number of state entries currently pending for download.
func (s *TrieSync) Pending() int {
return len(s.requests)
}
// schedule inserts a new state retrieval request into the fetch queue. If there
// is already a pending request for this node, the new request will be discarded
// and only a parent reference added to the old one.
func (s *TrieSync) schedule(req *request) {
// If we're already requesting this node, add a new reference and stop
if old, ok := s.requests[req.hash]; ok {
old.parents = append(old.parents, req.parents...)
return
}
// Schedule the request for future retrieval
s.queue.Push(req.hash, float32(req.depth))
s.requests[req.hash] = req
}
// children retrieves all the missing children of a state trie entry for future
// retrieval scheduling.
func (s *TrieSync) children(req *request) ([]*request, error) {
// Gather all the children of the node, irrelevant whether known or not
type child struct {
node *node
depth int
}
children := []child{}
switch node := (*req.object).(type) {
case *shortNode:
node = node.copy() // Prevents linking all downloaded nodes together.
children = []child{{
node: &node.Val,
depth: req.depth + len(node.Key),
}}
case *fullNode:
node = node.copy()
for i := 0; i < 17; i++ {
if node.Children[i] != nil {
children = append(children, child{
node: &node.Children[i],
depth: req.depth + 1,
})
}
}
default:
panic(fmt.Sprintf("unknown node: %+v", node))
}
// Iterate over the children, and request all unknown ones
requests := make([]*request, 0, len(children))
for _, child := range children {
// Notify any external watcher of a new key/value node
if req.callback != nil {
if node, ok := (*child.node).(valueNode); ok {
if err := req.callback(node, req.hash); err != nil {
return nil, err
}
}
}
// If the child references another node, resolve or schedule
if node, ok := (*child.node).(hashNode); ok {
// Try to resolve the node from the local database
blob, _ := s.database.Get(node)
if local, err := decodeNode(node[:], blob); local != nil && err == nil {
*child.node = local
continue
}
// Locally unknown node, schedule for retrieval
requests = append(requests, &request{
object: child.node,
hash: common.BytesToHash(node),
parents: []*request{req},
depth: child.depth,
callback: req.callback,
})
}
}
return requests, nil
}
// commit finalizes a retrieval request and stores it into the database. If any
// of the referencing parent requests complete due to this commit, they are also
// committed themselves.
func (s *TrieSync) commit(req *request, batch ethdb.Batch) (err error) {
// Create a new batch if none was specified
if batch == nil {
batch = s.database.NewBatch()
defer func() {
err = batch.Write()
}()
}
// Write the node content to disk
if err := batch.Put(req.hash[:], req.data); err != nil {
return err
}
delete(s.requests, req.hash)
// Check all parents for completion
for _, parent := range req.parents {
parent.deps--
if parent.deps == 0 {
if err := s.commit(parent, batch); err != nil {
return err
}
}
}
return nil
}