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

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// 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"
"sync"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/common/prque"
"github.com/ethereum/go-ethereum/core/rawdb"
"github.com/ethereum/go-ethereum/ethdb"
"github.com/ethereum/go-ethereum/log"
)
// 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")
// ErrAlreadyProcessed is returned by the trie sync when it's requested to process a
// node it already processed previously.
var ErrAlreadyProcessed = errors.New("already processed")
// maxFetchesPerDepth is the maximum number of pending trie nodes per depth. The
// role of this value is to limit the number of trie nodes that get expanded in
// memory if the node was configured with a significant number of peers.
const maxFetchesPerDepth = 16384
// SyncPath is a path tuple identifying a particular trie node either in a single
// trie (account) or a layered trie (account -> storage).
//
// Content wise the tuple either has 1 element if it addresses a node in a single
// trie or 2 elements if it addresses a node in a stacked trie.
//
// To support aiming arbitrary trie nodes, the path needs to support odd nibble
// lengths. To avoid transferring expanded hex form over the network, the last
// part of the tuple (which needs to index into the middle of a trie) is compact
// encoded. In case of a 2-tuple, the first item is always 32 bytes so that is
// simple binary encoded.
//
// Examples:
// - Path 0x9 -> {0x19}
// - Path 0x99 -> {0x0099}
// - Path 0x01234567890123456789012345678901012345678901234567890123456789019 -> {0x0123456789012345678901234567890101234567890123456789012345678901, 0x19}
// - Path 0x012345678901234567890123456789010123456789012345678901234567890199 -> {0x0123456789012345678901234567890101234567890123456789012345678901, 0x0099}
type SyncPath [][]byte
// NewSyncPath converts an expanded trie path from nibble form into a compact
// version that can be sent over the network.
func NewSyncPath(path []byte) SyncPath {
// If the hash is from the account trie, append a single item, if it
// is from a storage trie, append a tuple. Note, the length 64 is
// clashing between account leaf and storage root. It's fine though
// because having a trie node at 64 depth means a hash collision was
// found and we're long dead.
if len(path) < 64 {
return SyncPath{hexToCompact(path)}
}
return SyncPath{hexToKeybytes(path[:64]), hexToCompact(path[64:])}
}
// LeafCallback is a callback type invoked when a trie operation reaches a leaf
// node.
//
// The keys is a path tuple identifying a particular trie node either in a single
// trie (account) or a layered trie (account -> storage). Each key in the tuple
// is in the raw format(32 bytes).
//
// The path is a composite hexary path identifying the trie node. All the key
// bytes are converted to the hexary nibbles and composited with the parent path
// if the trie node is in a layered trie.
//
// It's used by state sync and commit to allow handling external references
// between account and storage tries. And also it's used in the state healing
// for extracting the raw states(leaf nodes) with corresponding paths.
type LeafCallback func(keys [][]byte, path []byte, leaf []byte, parent common.Hash, parentPath []byte) error
// nodeRequest represents a scheduled or already in-flight trie node retrieval request.
type nodeRequest struct {
hash common.Hash // Hash of the trie node to retrieve
path []byte // Merkle path leading to this node for prioritization
data []byte // Data content of the node, cached until all subtrees complete
parent *nodeRequest // Parent state node referencing this entry
deps int // Number of dependencies before allowed to commit this node
callback LeafCallback // Callback to invoke if a leaf node it reached on this branch
}
// codeRequest represents a scheduled or already in-flight bytecode retrieval request.
type codeRequest struct {
hash common.Hash // Hash of the contract bytecode to retrieve
path []byte // Merkle path leading to this node for prioritization
data []byte // Data content of the node, cached until all subtrees complete
parents []*nodeRequest // Parent state nodes referencing this entry (notify all upon completion)
}
// NodeSyncResult is a response with requested trie node along with its node path.
type NodeSyncResult struct {
Path string // Path of the originally unknown trie node
Data []byte // Data content of the retrieved trie node
}
// CodeSyncResult is a response with requested bytecode along with its hash.
type CodeSyncResult struct {
Hash common.Hash // Hash the originally unknown bytecode
Data []byte // Data content of the retrieved bytecode
}
// syncMemBatch is an in-memory buffer of successfully downloaded but not yet
// persisted data items.
type syncMemBatch struct {
nodes map[string][]byte // In-memory membatch of recently completed nodes
hashes map[string]common.Hash // Hashes of recently completed nodes
codes map[common.Hash][]byte // In-memory membatch of recently completed codes
size uint64 // Estimated batch-size of in-memory data.
}
// newSyncMemBatch allocates a new memory-buffer for not-yet persisted trie nodes.
func newSyncMemBatch() *syncMemBatch {
return &syncMemBatch{
nodes: make(map[string][]byte),
hashes: make(map[string]common.Hash),
codes: make(map[common.Hash][]byte),
}
}
// hasNode reports the trie node with specific path is already cached.
func (batch *syncMemBatch) hasNode(path []byte) bool {
_, ok := batch.nodes[string(path)]
return ok
}
// hasCode reports the contract code with specific hash is already cached.
func (batch *syncMemBatch) hasCode(hash common.Hash) bool {
_, ok := batch.codes[hash]
return ok
}
// Sync 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 Sync struct {
scheme string // Node scheme descriptor used in database.
database ethdb.KeyValueReader // Persistent database to check for existing entries
membatch *syncMemBatch // Memory buffer to avoid frequent database writes
nodeReqs map[string]*nodeRequest // Pending requests pertaining to a trie node path
codeReqs map[common.Hash]*codeRequest // Pending requests pertaining to a code hash
queue *prque.Prque // Priority queue with the pending requests
fetches map[int]int // Number of active fetches per trie node depth
}
// NewSync creates a new trie data download scheduler.
func NewSync(root common.Hash, database ethdb.KeyValueReader, callback LeafCallback, scheme string) *Sync {
ts := &Sync{
scheme: scheme,
database: database,
membatch: newSyncMemBatch(),
nodeReqs: make(map[string]*nodeRequest),
codeReqs: make(map[common.Hash]*codeRequest),
queue: prque.New(nil),
fetches: make(map[int]int),
}
ts.AddSubTrie(root, nil, common.Hash{}, nil, callback)
return ts
}
// AddSubTrie registers a new trie to the sync code, rooted at the designated
// parent for completion tracking. The given path is a unique node path in
// hex format and contain all the parent path if it's layered trie node.
func (s *Sync) AddSubTrie(root common.Hash, path []byte, parent common.Hash, parentPath []byte, callback LeafCallback) {
// Short circuit if the trie is empty or already known
if root == emptyRoot {
return
}
if s.membatch.hasNode(path) {
return
}
owner, inner := ResolvePath(path)
if rawdb.HasTrieNode(s.database, owner, inner, root, s.scheme) {
return
}
// Assemble the new sub-trie sync request
req := &nodeRequest{
hash: root,
path: path,
callback: callback,
}
// If this sub-trie has a designated parent, link them together
if parent != (common.Hash{}) {
ancestor := s.nodeReqs[string(parentPath)]
if ancestor == nil {
panic(fmt.Sprintf("sub-trie ancestor not found: %x", parent))
}
ancestor.deps++
req.parent = ancestor
}
s.scheduleNodeRequest(req)
}
// AddCodeEntry schedules the direct retrieval of a contract code that should not
// be interpreted as a trie node, but rather accepted and stored into the database
// as is.
func (s *Sync) AddCodeEntry(hash common.Hash, path []byte, parent common.Hash, parentPath []byte) {
// Short circuit if the entry is empty or already known
if hash == emptyState {
return
}
if s.membatch.hasCode(hash) {
return
}
// If database says duplicate, the blob is present for sure.
// Note we only check the existence with new code scheme, snap
// sync is expected to run with a fresh new node. Even there
// exists the code with legacy format, fetch and store with
// new scheme anyway.
if rawdb.HasCodeWithPrefix(s.database, hash) {
return
}
// Assemble the new sub-trie sync request
req := &codeRequest{
path: path,
hash: hash,
}
// If this sub-trie has a designated parent, link them together
if parent != (common.Hash{}) {
ancestor := s.nodeReqs[string(parentPath)] // the parent of codereq can ONLY be nodereq
if ancestor == nil {
panic(fmt.Sprintf("raw-entry ancestor not found: %x", parent))
}
ancestor.deps++
req.parents = append(req.parents, ancestor)
}
s.scheduleCodeRequest(req)
}
// Missing retrieves the known missing nodes from the trie for retrieval. To aid
// both eth/6x style fast sync and snap/1x style state sync, the paths of trie
// nodes are returned too, as well as separate hash list for codes.
func (s *Sync) Missing(max int) ([]string, []common.Hash, []common.Hash) {
var (
nodePaths []string
nodeHashes []common.Hash
codeHashes []common.Hash
)
for !s.queue.Empty() && (max == 0 || len(nodeHashes)+len(codeHashes) < max) {
// Retrieve the next item in line
item, prio := s.queue.Peek()
// If we have too many already-pending tasks for this depth, throttle
depth := int(prio >> 56)
if s.fetches[depth] > maxFetchesPerDepth {
break
}
// Item is allowed to be scheduled, add it to the task list
s.queue.Pop()
s.fetches[depth]++
switch item := item.(type) {
case common.Hash:
codeHashes = append(codeHashes, item)
case string:
req, ok := s.nodeReqs[item]
if !ok {
log.Error("Missing node request", "path", item)
continue // System very wrong, shouldn't happen
}
nodePaths = append(nodePaths, item)
nodeHashes = append(nodeHashes, req.hash)
}
}
return nodePaths, nodeHashes, codeHashes
}
// ProcessCode injects the received data for requested item. Note it can
// happpen that the single response commits two pending requests(e.g.
// there are two requests one for code and one for node but the hash
// is same). In this case the second response for the same hash will
// be treated as "non-requested" item or "already-processed" item but
// there is no downside.
func (s *Sync) ProcessCode(result CodeSyncResult) error {
// If the code was not requested or it's already processed, bail out
req := s.codeReqs[result.Hash]
if req == nil {
return ErrNotRequested
}
if req.data != nil {
return ErrAlreadyProcessed
}
req.data = result.Data
return s.commitCodeRequest(req)
}
// ProcessNode injects the received data for requested item. Note it can
// happen that the single response commits two pending requests(e.g.
// there are two requests one for code and one for node but the hash
// is same). In this case the second response for the same hash will
// be treated as "non-requested" item or "already-processed" item but
// there is no downside.
func (s *Sync) ProcessNode(result NodeSyncResult) error {
// If the trie node was not requested or it's already processed, bail out
req := s.nodeReqs[result.Path]
if req == nil {
return ErrNotRequested
}
if req.data != nil {
return ErrAlreadyProcessed
}
// Decode the node data content and update the request
node, err := decodeNode(req.hash.Bytes(), result.Data)
if err != nil {
return err
}
req.data = result.Data
// Create and schedule a request for all the children nodes
requests, err := s.children(req, node)
if err != nil {
return err
}
if len(requests) == 0 && req.deps == 0 {
s.commitNodeRequest(req)
} else {
req.deps += len(requests)
for _, child := range requests {
s.scheduleNodeRequest(child)
}
}
return nil
}
// Commit flushes the data stored in the internal membatch out to persistent
// storage, returning any occurred error.
func (s *Sync) Commit(dbw ethdb.Batch) error {
// Dump the membatch into a database dbw
for path, value := range s.membatch.nodes {
owner, inner := ResolvePath([]byte(path))
rawdb.WriteTrieNode(dbw, owner, inner, s.membatch.hashes[path], value, s.scheme)
}
for hash, value := range s.membatch.codes {
rawdb.WriteCode(dbw, hash, value)
}
// Drop the membatch data and return
s.membatch = newSyncMemBatch()
return nil
}
// MemSize returns an estimated size (in bytes) of the data held in the membatch.
func (s *Sync) MemSize() uint64 {
return s.membatch.size
}
// Pending returns the number of state entries currently pending for download.
func (s *Sync) Pending() int {
return len(s.nodeReqs) + len(s.codeReqs)
}
// 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 *Sync) scheduleNodeRequest(req *nodeRequest) {
s.nodeReqs[string(req.path)] = req
// Schedule the request for future retrieval. This queue is shared
// by both node requests and code requests.
prio := int64(len(req.path)) << 56 // depth >= 128 will never happen, storage leaves will be included in their parents
for i := 0; i < 14 && i < len(req.path); i++ {
prio |= int64(15-req.path[i]) << (52 - i*4) // 15-nibble => lexicographic order
}
s.queue.Push(string(req.path), prio)
}
// 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 *Sync) scheduleCodeRequest(req *codeRequest) {
// If we're already requesting this node, add a new reference and stop
if old, ok := s.codeReqs[req.hash]; ok {
old.parents = append(old.parents, req.parents...)
return
}
s.codeReqs[req.hash] = req
// Schedule the request for future retrieval. This queue is shared
// by both node requests and code requests.
prio := int64(len(req.path)) << 56 // depth >= 128 will never happen, storage leaves will be included in their parents
for i := 0; i < 14 && i < len(req.path); i++ {
prio |= int64(15-req.path[i]) << (52 - i*4) // 15-nibble => lexicographic order
}
s.queue.Push(req.hash, prio)
}
// children retrieves all the missing children of a state trie entry for future
// retrieval scheduling.
func (s *Sync) children(req *nodeRequest, object node) ([]*nodeRequest, error) {
// Gather all the children of the node, irrelevant whether known or not
type childNode struct {
path []byte
node node
}
var children []childNode
switch node := (object).(type) {
case *shortNode:
key := node.Key
if hasTerm(key) {
key = key[:len(key)-1]
}
children = []childNode{{
node: node.Val,
path: append(append([]byte(nil), req.path...), key...),
}}
case *fullNode:
for i := 0; i < 17; i++ {
if node.Children[i] != nil {
children = append(children, childNode{
node: node.Children[i],
path: append(append([]byte(nil), req.path...), byte(i)),
})
}
}
default:
panic(fmt.Sprintf("unknown node: %+v", node))
}
// Iterate over the children, and request all unknown ones
var (
missing = make(chan *nodeRequest, len(children))
pending sync.WaitGroup
)
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 {
var paths [][]byte
if len(child.path) == 2*common.HashLength {
paths = append(paths, hexToKeybytes(child.path))
} else if len(child.path) == 4*common.HashLength {
paths = append(paths, hexToKeybytes(child.path[:2*common.HashLength]))
paths = append(paths, hexToKeybytes(child.path[2*common.HashLength:]))
}
if err := req.callback(paths, child.path, node, req.hash, req.path); 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
if s.membatch.hasNode(child.path) {
continue
}
// Check the presence of children concurrently
pending.Add(1)
go func(child childNode) {
defer pending.Done()
// If database says duplicate, then at least the trie node is present
// and we hold the assumption that it's NOT legacy contract code.
var (
chash = common.BytesToHash(node)
owner, inner = ResolvePath(child.path)
)
if rawdb.HasTrieNode(s.database, owner, inner, chash, s.scheme) {
return
}
// Locally unknown node, schedule for retrieval
missing <- &nodeRequest{
path: child.path,
hash: chash,
parent: req,
callback: req.callback,
}
}(child)
}
}
pending.Wait()
requests := make([]*nodeRequest, 0, len(children))
for done := false; !done; {
select {
case miss := <-missing:
requests = append(requests, miss)
default:
done = true
}
}
return requests, nil
}
// commit finalizes a retrieval request and stores it into the membatch. If any
// of the referencing parent requests complete due to this commit, they are also
// committed themselves.
func (s *Sync) commitNodeRequest(req *nodeRequest) error {
// Write the node content to the membatch
s.membatch.nodes[string(req.path)] = req.data
s.membatch.hashes[string(req.path)] = req.hash
// The size tracking refers to the db-batch, not the in-memory data.
// Therefore, we ignore the req.path, and account only for the hash+data
// which eventually is written to db.
s.membatch.size += common.HashLength + uint64(len(req.data))
delete(s.nodeReqs, string(req.path))
s.fetches[len(req.path)]--
// Check parent for completion
if req.parent != nil {
req.parent.deps--
if req.parent.deps == 0 {
if err := s.commitNodeRequest(req.parent); err != nil {
return err
}
}
}
return nil
}
// commit finalizes a retrieval request and stores it into the membatch. If any
// of the referencing parent requests complete due to this commit, they are also
// committed themselves.
func (s *Sync) commitCodeRequest(req *codeRequest) error {
// Write the node content to the membatch
s.membatch.codes[req.hash] = req.data
s.membatch.size += common.HashLength + uint64(len(req.data))
delete(s.codeReqs, req.hash)
s.fetches[len(req.path)]--
// Check all parents for completion
for _, parent := range req.parents {
parent.deps--
if parent.deps == 0 {
if err := s.commitNodeRequest(parent); err != nil {
return err
}
}
}
return nil
}
// ResolvePath resolves the provided composite node path by separating the
// path in account trie if it's existent.
func ResolvePath(path []byte) (common.Hash, []byte) {
var owner common.Hash
if len(path) >= 2*common.HashLength {
owner = common.BytesToHash(hexToKeybytes(path[:2*common.HashLength]))
path = path[2*common.HashLength:]
}
return owner, path
}