// 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 .
// Package downloader contains the manual full chain synchronisation.
package downloader
import (
"crypto/rand"
"errors"
"fmt"
"math"
"math/big"
"strings"
"sync"
"sync/atomic"
"time"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/ethdb"
"github.com/ethereum/go-ethereum/event"
"github.com/ethereum/go-ethereum/logger"
"github.com/ethereum/go-ethereum/logger/glog"
"github.com/rcrowley/go-metrics"
)
var (
MaxHashFetch = 512 // Amount of hashes to be fetched per retrieval request
MaxBlockFetch = 128 // Amount of blocks to be fetched per retrieval request
MaxHeaderFetch = 192 // Amount of block headers to be fetched per retrieval request
MaxBodyFetch = 128 // Amount of block bodies to be fetched per retrieval request
MaxReceiptFetch = 256 // Amount of transaction receipts to allow fetching per request
MaxStateFetch = 384 // Amount of node state values to allow fetching per request
hashTTL = 5 * time.Second // [eth/61] Time it takes for a hash request to time out
blockSoftTTL = 3 * time.Second // [eth/61] Request completion threshold for increasing or decreasing a peer's bandwidth
blockHardTTL = 3 * blockSoftTTL // [eth/61] Maximum time allowance before a block request is considered expired
headerTTL = 5 * time.Second // [eth/62] Time it takes for a header request to time out
bodySoftTTL = 3 * time.Second // [eth/62] Request completion threshold for increasing or decreasing a peer's bandwidth
bodyHardTTL = 3 * bodySoftTTL // [eth/62] Maximum time allowance before a block body request is considered expired
receiptSoftTTL = 3 * time.Second // [eth/63] Request completion threshold for increasing or decreasing a peer's bandwidth
receiptHardTTL = 3 * receiptSoftTTL // [eth/63] Maximum time allowance before a receipt request is considered expired
stateSoftTTL = 2 * time.Second // [eth/63] Request completion threshold for increasing or decreasing a peer's bandwidth
stateHardTTL = 3 * stateSoftTTL // [eth/63] Maximum time allowance before a node data request is considered expired
maxQueuedHashes = 256 * 1024 // [eth/61] Maximum number of hashes to queue for import (DOS protection)
maxQueuedHeaders = 256 * 1024 // [eth/62] Maximum number of headers to queue for import (DOS protection)
maxQueuedStates = 256 * 1024 // [eth/63] Maximum number of state requests to queue (DOS protection)
maxResultsProcess = 256 // Number of download results to import at once into the chain
fsHeaderCheckFrequency = 100 // Verification frequency of the downloaded headers during fast sync
fsHeaderSafetyNet = 2048 // Number of headers to discard in case a chain violation is detected
fsHeaderForceVerify = 24 // Number of headers to verify before and after the pivot to accept it
fsPivotInterval = 512 // Number of headers out of which to randomize the pivot point
fsMinFullBlocks = 1024 // Number of blocks to retrieve fully even in fast sync
)
var (
errBusy = errors.New("busy")
errUnknownPeer = errors.New("peer is unknown or unhealthy")
errBadPeer = errors.New("action from bad peer ignored")
errStallingPeer = errors.New("peer is stalling")
errNoPeers = errors.New("no peers to keep download active")
errTimeout = errors.New("timeout")
errEmptyHashSet = errors.New("empty hash set by peer")
errEmptyHeaderSet = errors.New("empty header set by peer")
errPeersUnavailable = errors.New("no peers available or all tried for download")
errAlreadyInPool = errors.New("hash already in pool")
errInvalidChain = errors.New("retrieved hash chain is invalid")
errInvalidBlock = errors.New("retrieved block is invalid")
errInvalidBody = errors.New("retrieved block body is invalid")
errInvalidReceipt = errors.New("retrieved receipt is invalid")
errCancelHashFetch = errors.New("hash download canceled (requested)")
errCancelBlockFetch = errors.New("block download canceled (requested)")
errCancelHeaderFetch = errors.New("block header download canceled (requested)")
errCancelBodyFetch = errors.New("block body download canceled (requested)")
errCancelReceiptFetch = errors.New("receipt download canceled (requested)")
errCancelStateFetch = errors.New("state data download canceled (requested)")
errCancelProcessing = errors.New("processing canceled (requested)")
errNoSyncActive = errors.New("no sync active")
)
type Downloader struct {
mode SyncMode // Synchronisation mode defining the strategy used (per sync cycle)
noFast bool // Flag to disable fast syncing in case of a security error
mux *event.TypeMux // Event multiplexer to announce sync operation events
queue *queue // Scheduler for selecting the hashes to download
peers *peerSet // Set of active peers from which download can proceed
interrupt int32 // Atomic boolean to signal termination
// Statistics
syncStatsChainOrigin uint64 // Origin block number where syncing started at
syncStatsChainHeight uint64 // Highest block number known when syncing started
syncStatsStateTotal uint64 // Total number of node state entries known so far
syncStatsStateDone uint64 // Number of state trie entries already pulled
syncStatsLock sync.RWMutex // Lock protecting the sync stats fields
// Callbacks
hasHeader headerCheckFn // Checks if a header is present in the chain
hasBlock blockCheckFn // Checks if a block is present in the chain
getHeader headerRetrievalFn // Retrieves a header from the chain
getBlock blockRetrievalFn // Retrieves a block from the chain
headHeader headHeaderRetrievalFn // Retrieves the head header from the chain
headBlock headBlockRetrievalFn // Retrieves the head block from the chain
headFastBlock headFastBlockRetrievalFn // Retrieves the head fast-sync block from the chain
commitHeadBlock headBlockCommitterFn // Commits a manually assembled block as the chain head
getTd tdRetrievalFn // Retrieves the TD of a block from the chain
insertHeaders headerChainInsertFn // Injects a batch of headers into the chain
insertBlocks blockChainInsertFn // Injects a batch of blocks into the chain
insertReceipts receiptChainInsertFn // Injects a batch of blocks and their receipts into the chain
rollback chainRollbackFn // Removes a batch of recently added chain links
dropPeer peerDropFn // Drops a peer for misbehaving
// Status
synchroniseMock func(id string, hash common.Hash) error // Replacement for synchronise during testing
synchronising int32
notified int32
// Channels
newPeerCh chan *peer
hashCh chan dataPack // [eth/61] Channel receiving inbound hashes
blockCh chan dataPack // [eth/61] Channel receiving inbound blocks
headerCh chan dataPack // [eth/62] Channel receiving inbound block headers
bodyCh chan dataPack // [eth/62] Channel receiving inbound block bodies
receiptCh chan dataPack // [eth/63] Channel receiving inbound receipts
stateCh chan dataPack // [eth/63] Channel receiving inbound node state data
blockWakeCh chan bool // [eth/61] Channel to signal the block fetcher of new tasks
bodyWakeCh chan bool // [eth/62] Channel to signal the block body fetcher of new tasks
receiptWakeCh chan bool // [eth/63] Channel to signal the receipt fetcher of new tasks
stateWakeCh chan bool // [eth/63] Channel to signal the state fetcher of new tasks
cancelCh chan struct{} // Channel to cancel mid-flight syncs
cancelLock sync.RWMutex // Lock to protect the cancel channel in delivers
// Testing hooks
syncInitHook func(uint64, uint64) // Method to call upon initiating a new sync run
bodyFetchHook func([]*types.Header) // Method to call upon starting a block body fetch
receiptFetchHook func([]*types.Header) // Method to call upon starting a receipt fetch
chainInsertHook func([]*fetchResult) // Method to call upon inserting a chain of blocks (possibly in multiple invocations)
}
// New creates a new downloader to fetch hashes and blocks from remote peers.
func New(stateDb ethdb.Database, mux *event.TypeMux, hasHeader headerCheckFn, hasBlock blockCheckFn, getHeader headerRetrievalFn,
getBlock blockRetrievalFn, headHeader headHeaderRetrievalFn, headBlock headBlockRetrievalFn, headFastBlock headFastBlockRetrievalFn,
commitHeadBlock headBlockCommitterFn, getTd tdRetrievalFn, insertHeaders headerChainInsertFn, insertBlocks blockChainInsertFn,
insertReceipts receiptChainInsertFn, rollback chainRollbackFn, dropPeer peerDropFn) *Downloader {
return &Downloader{
mode: FullSync,
mux: mux,
queue: newQueue(stateDb),
peers: newPeerSet(),
hasHeader: hasHeader,
hasBlock: hasBlock,
getHeader: getHeader,
getBlock: getBlock,
headHeader: headHeader,
headBlock: headBlock,
headFastBlock: headFastBlock,
commitHeadBlock: commitHeadBlock,
getTd: getTd,
insertHeaders: insertHeaders,
insertBlocks: insertBlocks,
insertReceipts: insertReceipts,
rollback: rollback,
dropPeer: dropPeer,
newPeerCh: make(chan *peer, 1),
hashCh: make(chan dataPack, 1),
blockCh: make(chan dataPack, 1),
headerCh: make(chan dataPack, 1),
bodyCh: make(chan dataPack, 1),
receiptCh: make(chan dataPack, 1),
stateCh: make(chan dataPack, 1),
blockWakeCh: make(chan bool, 1),
bodyWakeCh: make(chan bool, 1),
receiptWakeCh: make(chan bool, 1),
stateWakeCh: make(chan bool, 1),
}
}
// Progress retrieves the synchronisation boundaries, specifically the origin
// block where synchronisation started at (may have failed/suspended); the block
// or header sync is currently at; and the latest known block which the sync targets.
func (d *Downloader) Progress() (uint64, uint64, uint64) {
d.syncStatsLock.RLock()
defer d.syncStatsLock.RUnlock()
current := uint64(0)
switch d.mode {
case FullSync:
current = d.headBlock().NumberU64()
case FastSync:
current = d.headFastBlock().NumberU64()
case LightSync:
current = d.headHeader().Number.Uint64()
}
return d.syncStatsChainOrigin, current, d.syncStatsChainHeight
}
// Synchronising returns whether the downloader is currently retrieving blocks.
func (d *Downloader) Synchronising() bool {
return atomic.LoadInt32(&d.synchronising) > 0
}
// RegisterPeer injects a new download peer into the set of block source to be
// used for fetching hashes and blocks from.
func (d *Downloader) RegisterPeer(id string, version int, head common.Hash,
getRelHashes relativeHashFetcherFn, getAbsHashes absoluteHashFetcherFn, getBlocks blockFetcherFn, // eth/61 callbacks, remove when upgrading
getRelHeaders relativeHeaderFetcherFn, getAbsHeaders absoluteHeaderFetcherFn, getBlockBodies blockBodyFetcherFn,
getReceipts receiptFetcherFn, getNodeData stateFetcherFn) error {
glog.V(logger.Detail).Infoln("Registering peer", id)
if err := d.peers.Register(newPeer(id, version, head, getRelHashes, getAbsHashes, getBlocks, getRelHeaders, getAbsHeaders, getBlockBodies, getReceipts, getNodeData)); err != nil {
glog.V(logger.Error).Infoln("Register failed:", err)
return err
}
return nil
}
// UnregisterPeer remove a peer from the known list, preventing any action from
// the specified peer. An effort is also made to return any pending fetches into
// the queue.
func (d *Downloader) UnregisterPeer(id string) error {
glog.V(logger.Detail).Infoln("Unregistering peer", id)
if err := d.peers.Unregister(id); err != nil {
glog.V(logger.Error).Infoln("Unregister failed:", err)
return err
}
d.queue.Revoke(id)
return nil
}
// Synchronise tries to sync up our local block chain with a remote peer, both
// adding various sanity checks as well as wrapping it with various log entries.
func (d *Downloader) Synchronise(id string, head common.Hash, td *big.Int, mode SyncMode) error {
glog.V(logger.Detail).Infof("Attempting synchronisation: %v, head [%x…], TD %v", id, head[:4], td)
err := d.synchronise(id, head, td, mode)
switch err {
case nil:
glog.V(logger.Detail).Infof("Synchronisation completed")
case errBusy:
glog.V(logger.Detail).Infof("Synchronisation already in progress")
case errTimeout, errBadPeer, errStallingPeer, errEmptyHashSet, errEmptyHeaderSet, errPeersUnavailable, errInvalidChain:
glog.V(logger.Debug).Infof("Removing peer %v: %v", id, err)
d.dropPeer(id)
default:
glog.V(logger.Warn).Infof("Synchronisation failed: %v", err)
}
return err
}
// synchronise will select the peer and use it for synchronising. If an empty string is given
// it will use the best peer possible and synchronize if it's TD is higher than our own. If any of the
// checks fail an error will be returned. This method is synchronous
func (d *Downloader) synchronise(id string, hash common.Hash, td *big.Int, mode SyncMode) error {
// Mock out the synchonisation if testing
if d.synchroniseMock != nil {
return d.synchroniseMock(id, hash)
}
// Make sure only one goroutine is ever allowed past this point at once
if !atomic.CompareAndSwapInt32(&d.synchronising, 0, 1) {
return errBusy
}
defer atomic.StoreInt32(&d.synchronising, 0)
// Post a user notification of the sync (only once per session)
if atomic.CompareAndSwapInt32(&d.notified, 0, 1) {
glog.V(logger.Info).Infoln("Block synchronisation started")
}
// Reset the queue, peer set and wake channels to clean any internal leftover state
d.queue.Reset()
d.peers.Reset()
for _, ch := range []chan bool{d.blockWakeCh, d.bodyWakeCh, d.receiptWakeCh, d.stateWakeCh} {
select {
case <-ch:
default:
}
}
// Reset and ephemeral sync statistics
d.syncStatsLock.Lock()
d.syncStatsStateTotal = 0
d.syncStatsStateDone = 0
d.syncStatsLock.Unlock()
// Create cancel channel for aborting mid-flight
d.cancelLock.Lock()
d.cancelCh = make(chan struct{})
d.cancelLock.Unlock()
// Set the requested sync mode, unless it's forbidden
d.mode = mode
if d.mode == FastSync && d.noFast {
d.mode = FullSync
}
// Retrieve the origin peer and initiate the downloading process
p := d.peers.Peer(id)
if p == nil {
return errUnknownPeer
}
return d.syncWithPeer(p, hash, td)
}
// syncWithPeer starts a block synchronization based on the hash chain from the
// specified peer and head hash.
func (d *Downloader) syncWithPeer(p *peer, hash common.Hash, td *big.Int) (err error) {
d.mux.Post(StartEvent{})
defer func() {
// reset on error
if err != nil {
d.mux.Post(FailedEvent{err})
} else {
d.mux.Post(DoneEvent{})
}
}()
glog.V(logger.Debug).Infof("Synchronising with the network using: %s [eth/%d]", p.id, p.version)
defer func(start time.Time) {
glog.V(logger.Debug).Infof("Synchronisation terminated after %v", time.Since(start))
}(time.Now())
switch {
case p.version == 61:
// Look up the sync boundaries: the common ancestor and the target block
latest, err := d.fetchHeight61(p)
if err != nil {
return err
}
origin, err := d.findAncestor61(p)
if err != nil {
return err
}
d.syncStatsLock.Lock()
if d.syncStatsChainHeight <= origin || d.syncStatsChainOrigin > origin {
d.syncStatsChainOrigin = origin
}
d.syncStatsChainHeight = latest
d.syncStatsLock.Unlock()
// Initiate the sync using a concurrent hash and block retrieval algorithm
d.queue.Prepare(origin+1, d.mode, 0)
if d.syncInitHook != nil {
d.syncInitHook(origin, latest)
}
return d.spawnSync(
func() error { return d.fetchHashes61(p, td, origin+1) },
func() error { return d.fetchBlocks61(origin + 1) },
)
case p.version >= 62:
// Look up the sync boundaries: the common ancestor and the target block
latest, err := d.fetchHeight(p)
if err != nil {
return err
}
origin, err := d.findAncestor(p)
if err != nil {
return err
}
d.syncStatsLock.Lock()
if d.syncStatsChainHeight <= origin || d.syncStatsChainOrigin > origin {
d.syncStatsChainOrigin = origin
}
d.syncStatsChainHeight = latest
d.syncStatsLock.Unlock()
// Initiate the sync using a concurrent header and content retrieval algorithm
pivot := uint64(0)
switch d.mode {
case LightSync:
pivot = latest
case FastSync:
// Calculate the new fast/slow sync pivot point
pivotOffset, err := rand.Int(rand.Reader, big.NewInt(int64(fsPivotInterval)))
if err != nil {
panic(fmt.Sprintf("Failed to access crypto random source: %v", err))
}
if latest > uint64(fsMinFullBlocks)+pivotOffset.Uint64() {
pivot = latest - uint64(fsMinFullBlocks) - pivotOffset.Uint64()
}
// If the point is below the origin, move origin back to ensure state download
if pivot < origin {
if pivot > 0 {
origin = pivot - 1
} else {
origin = 0
}
}
glog.V(logger.Debug).Infof("Fast syncing until pivot block #%d", pivot)
}
d.queue.Prepare(origin+1, d.mode, pivot)
if d.syncInitHook != nil {
d.syncInitHook(origin, latest)
}
return d.spawnSync(
func() error { return d.fetchHeaders(p, td, origin+1) }, // Headers are always retrieved
func() error { return d.fetchBodies(origin + 1) }, // Bodies are retrieved during normal and fast sync
func() error { return d.fetchReceipts(origin + 1) }, // Receipts are retrieved during fast sync
func() error { return d.fetchNodeData() }, // Node state data is retrieved during fast sync
)
default:
// Something very wrong, stop right here
glog.V(logger.Error).Infof("Unsupported eth protocol: %d", p.version)
return errBadPeer
}
}
// spawnSync runs d.process and all given fetcher functions to completion in
// separate goroutines, returning the first error that appears.
func (d *Downloader) spawnSync(fetchers ...func() error) error {
var wg sync.WaitGroup
errc := make(chan error, len(fetchers)+1)
wg.Add(len(fetchers) + 1)
go func() { defer wg.Done(); errc <- d.process() }()
for _, fn := range fetchers {
fn := fn
go func() { defer wg.Done(); errc <- fn() }()
}
// Wait for the first error, then terminate the others.
var err error
for i := 0; i < len(fetchers)+1; i++ {
if i == len(fetchers) {
// Close the queue when all fetchers have exited.
// This will cause the block processor to end when
// it has processed the queue.
d.queue.Close()
}
if err = <-errc; err != nil {
break
}
}
d.queue.Close()
d.cancel()
wg.Wait()
return err
}
// cancel cancels all of the operations and resets the queue. It returns true
// if the cancel operation was completed.
func (d *Downloader) cancel() {
// Close the current cancel channel
d.cancelLock.Lock()
if d.cancelCh != nil {
select {
case <-d.cancelCh:
// Channel was already closed
default:
close(d.cancelCh)
}
}
d.cancelLock.Unlock()
}
// Terminate interrupts the downloader, canceling all pending operations.
// The downloader cannot be reused after calling Terminate.
func (d *Downloader) Terminate() {
atomic.StoreInt32(&d.interrupt, 1)
d.cancel()
}
// fetchHeight61 retrieves the head block of the remote peer to aid in estimating
// the total time a pending synchronisation would take.
func (d *Downloader) fetchHeight61(p *peer) (uint64, error) {
glog.V(logger.Debug).Infof("%v: retrieving remote chain height", p)
// Request the advertised remote head block and wait for the response
go p.getBlocks([]common.Hash{p.head})
timeout := time.After(blockSoftTTL)
for {
select {
case <-d.cancelCh:
return 0, errCancelBlockFetch
case <-d.headerCh:
// Out of bounds eth/62 block headers received, ignore them
case <-d.bodyCh:
// Out of bounds eth/62 block bodies received, ignore them
case <-d.hashCh:
// Out of bounds hashes received, ignore them
case packet := <-d.blockCh:
// Discard anything not from the origin peer
if packet.PeerId() != p.id {
glog.V(logger.Debug).Infof("Received blocks from incorrect peer(%s)", packet.PeerId())
break
}
// Make sure the peer actually gave something valid
blocks := packet.(*blockPack).blocks
if len(blocks) != 1 {
glog.V(logger.Debug).Infof("%v: invalid number of head blocks: %d != 1", p, len(blocks))
return 0, errBadPeer
}
return blocks[0].NumberU64(), nil
case <-timeout:
glog.V(logger.Debug).Infof("%v: head block timeout", p)
return 0, errTimeout
}
}
}
// findAncestor61 tries to locate the common ancestor block of the local chain and
// a remote peers blockchain. In the general case when our node was in sync and
// on the correct chain, checking the top N blocks should already get us a match.
// In the rare scenario when we ended up on a long reorganization (i.e. none of
// the head blocks match), we do a binary search to find the common ancestor.
func (d *Downloader) findAncestor61(p *peer) (uint64, error) {
glog.V(logger.Debug).Infof("%v: looking for common ancestor", p)
// Request out head blocks to short circuit ancestor location
head := d.headBlock().NumberU64()
from := int64(head) - int64(MaxHashFetch) + 1
if from < 0 {
from = 0
}
go p.getAbsHashes(uint64(from), MaxHashFetch)
// Wait for the remote response to the head fetch
number, hash := uint64(0), common.Hash{}
timeout := time.After(hashTTL)
for finished := false; !finished; {
select {
case <-d.cancelCh:
return 0, errCancelHashFetch
case packet := <-d.hashCh:
// Discard anything not from the origin peer
if packet.PeerId() != p.id {
glog.V(logger.Debug).Infof("Received hashes from incorrect peer(%s)", packet.PeerId())
break
}
// Make sure the peer actually gave something valid
hashes := packet.(*hashPack).hashes
if len(hashes) == 0 {
glog.V(logger.Debug).Infof("%v: empty head hash set", p)
return 0, errEmptyHashSet
}
// Check if a common ancestor was found
finished = true
for i := len(hashes) - 1; i >= 0; i-- {
if d.hasBlock(hashes[i]) {
number, hash = uint64(from)+uint64(i), hashes[i]
break
}
}
case <-d.blockCh:
// Out of bounds blocks received, ignore them
case <-d.headerCh:
// Out of bounds eth/62 block headers received, ignore them
case <-d.bodyCh:
// Out of bounds eth/62 block bodies received, ignore them
case <-timeout:
glog.V(logger.Debug).Infof("%v: head hash timeout", p)
return 0, errTimeout
}
}
// If the head fetch already found an ancestor, return
if !common.EmptyHash(hash) {
glog.V(logger.Debug).Infof("%v: common ancestor: #%d [%x…]", p, number, hash[:4])
return number, nil
}
// Ancestor not found, we need to binary search over our chain
start, end := uint64(0), head
for start+1 < end {
// Split our chain interval in two, and request the hash to cross check
check := (start + end) / 2
timeout := time.After(hashTTL)
go p.getAbsHashes(uint64(check), 1)
// Wait until a reply arrives to this request
for arrived := false; !arrived; {
select {
case <-d.cancelCh:
return 0, errCancelHashFetch
case packet := <-d.hashCh:
// Discard anything not from the origin peer
if packet.PeerId() != p.id {
glog.V(logger.Debug).Infof("Received hashes from incorrect peer(%s)", packet.PeerId())
break
}
// Make sure the peer actually gave something valid
hashes := packet.(*hashPack).hashes
if len(hashes) != 1 {
glog.V(logger.Debug).Infof("%v: invalid search hash set (%d)", p, len(hashes))
return 0, errBadPeer
}
arrived = true
// Modify the search interval based on the response
block := d.getBlock(hashes[0])
if block == nil {
end = check
break
}
if block.NumberU64() != check {
glog.V(logger.Debug).Infof("%v: non requested hash #%d [%x…], instead of #%d", p, block.NumberU64(), block.Hash().Bytes()[:4], check)
return 0, errBadPeer
}
start = check
case <-d.blockCh:
// Out of bounds blocks received, ignore them
case <-d.headerCh:
// Out of bounds eth/62 block headers received, ignore them
case <-d.bodyCh:
// Out of bounds eth/62 block bodies received, ignore them
case <-timeout:
glog.V(logger.Debug).Infof("%v: search hash timeout", p)
return 0, errTimeout
}
}
}
return start, nil
}
// fetchHashes61 keeps retrieving hashes from the requested number, until no more
// are returned, potentially throttling on the way.
func (d *Downloader) fetchHashes61(p *peer, td *big.Int, from uint64) error {
glog.V(logger.Debug).Infof("%v: downloading hashes from #%d", p, from)
// Create a timeout timer, and the associated hash fetcher
request := time.Now() // time of the last fetch request
timeout := time.NewTimer(0) // timer to dump a non-responsive active peer
<-timeout.C // timeout channel should be initially empty
defer timeout.Stop()
getHashes := func(from uint64) {
glog.V(logger.Detail).Infof("%v: fetching %d hashes from #%d", p, MaxHashFetch, from)
go p.getAbsHashes(from, MaxHashFetch)
request = time.Now()
timeout.Reset(hashTTL)
}
// Start pulling hashes, until all are exhausted
getHashes(from)
gotHashes := false
for {
select {
case <-d.cancelCh:
return errCancelHashFetch
case <-d.headerCh:
// Out of bounds eth/62 block headers received, ignore them
case <-d.bodyCh:
// Out of bounds eth/62 block bodies received, ignore them
case packet := <-d.hashCh:
// Make sure the active peer is giving us the hashes
if packet.PeerId() != p.id {
glog.V(logger.Debug).Infof("Received hashes from incorrect peer(%s)", packet.PeerId())
break
}
hashReqTimer.UpdateSince(request)
timeout.Stop()
// If no more hashes are inbound, notify the block fetcher and return
if packet.Items() == 0 {
glog.V(logger.Debug).Infof("%v: no available hashes", p)
select {
case d.blockWakeCh <- false:
case <-d.cancelCh:
}
// If no hashes were retrieved at all, the peer violated it's TD promise that it had a
// better chain compared to ours. The only exception is if it's promised blocks were
// already imported by other means (e.g. fecher):
//
// R , L : Both at block 10
// R: Mine block 11, and propagate it to L
// L: Queue block 11 for import
// L: Notice that R's head and TD increased compared to ours, start sync
// L: Import of block 11 finishes
// L: Sync begins, and finds common ancestor at 11
// L: Request new hashes up from 11 (R's TD was higher, it must have something)
// R: Nothing to give
if !gotHashes && td.Cmp(d.getTd(d.headBlock().Hash())) > 0 {
return errStallingPeer
}
return nil
}
gotHashes = true
hashes := packet.(*hashPack).hashes
// Otherwise insert all the new hashes, aborting in case of junk
glog.V(logger.Detail).Infof("%v: scheduling %d hashes from #%d", p, len(hashes), from)
inserts := d.queue.Schedule61(hashes, true)
if len(inserts) != len(hashes) {
glog.V(logger.Debug).Infof("%v: stale hashes", p)
return errBadPeer
}
// Notify the block fetcher of new hashes, but stop if queue is full
if d.queue.PendingBlocks() < maxQueuedHashes {
// We still have hashes to fetch, send continuation wake signal (potential)
select {
case d.blockWakeCh <- true:
default:
}
} else {
// Hash limit reached, send a termination wake signal (enforced)
select {
case d.blockWakeCh <- false:
case <-d.cancelCh:
}
return nil
}
// Queue not yet full, fetch the next batch
from += uint64(len(hashes))
getHashes(from)
case <-timeout.C:
glog.V(logger.Debug).Infof("%v: hash request timed out", p)
hashTimeoutMeter.Mark(1)
return errTimeout
}
}
}
// fetchBlocks61 iteratively downloads the scheduled hashes, taking any available
// peers, reserving a chunk of blocks for each, waiting for delivery and also
// periodically checking for timeouts.
func (d *Downloader) fetchBlocks61(from uint64) error {
glog.V(logger.Debug).Infof("Downloading blocks from #%d", from)
defer glog.V(logger.Debug).Infof("Block download terminated")
// Create a timeout timer for scheduling expiration tasks
ticker := time.NewTicker(100 * time.Millisecond)
defer ticker.Stop()
update := make(chan struct{}, 1)
// Fetch blocks until the hash fetcher's done
finished := false
for {
select {
case <-d.cancelCh:
return errCancelBlockFetch
case <-d.headerCh:
// Out of bounds eth/62 block headers received, ignore them
case <-d.bodyCh:
// Out of bounds eth/62 block bodies received, ignore them
case packet := <-d.blockCh:
// If the peer was previously banned and failed to deliver it's pack
// in a reasonable time frame, ignore it's message.
if peer := d.peers.Peer(packet.PeerId()); peer != nil {
// Deliver the received chunk of blocks, and demote in case of errors
blocks := packet.(*blockPack).blocks
err := d.queue.DeliverBlocks(peer.id, blocks)
switch err {
case nil:
// If no blocks were delivered, demote the peer (need the delivery above)
if len(blocks) == 0 {
peer.Demote()
peer.SetBlocksIdle()
glog.V(logger.Detail).Infof("%s: no blocks delivered", peer)
break
}
// All was successful, promote the peer and potentially start processing
peer.Promote()
peer.SetBlocksIdle()
glog.V(logger.Detail).Infof("%s: delivered %d blocks", peer, len(blocks))
case errInvalidChain:
// The hash chain is invalid (blocks are not ordered properly), abort
return err
case errNoFetchesPending:
// Peer probably timed out with its delivery but came through
// in the end, demote, but allow to to pull from this peer.
peer.Demote()
peer.SetBlocksIdle()
glog.V(logger.Detail).Infof("%s: out of bound delivery", peer)
case errStaleDelivery:
// Delivered something completely else than requested, usually
// caused by a timeout and delivery during a new sync cycle.
// Don't set it to idle as the original request should still be
// in flight.
peer.Demote()
glog.V(logger.Detail).Infof("%s: stale delivery", peer)
default:
// Peer did something semi-useful, demote but keep it around
peer.Demote()
peer.SetBlocksIdle()
glog.V(logger.Detail).Infof("%s: delivery partially failed: %v", peer, err)
}
}
// Blocks arrived, try to update the progress
select {
case update <- struct{}{}:
default:
}
case cont := <-d.blockWakeCh:
// The hash fetcher sent a continuation flag, check if it's done
if !cont {
finished = true
}
// Hashes arrive, try to update the progress
select {
case update <- struct{}{}:
default:
}
case <-ticker.C:
// Sanity check update the progress
select {
case update <- struct{}{}:
default:
}
case <-update:
// Short circuit if we lost all our peers
if d.peers.Len() == 0 {
return errNoPeers
}
// Check for block request timeouts and demote the responsible peers
for _, pid := range d.queue.ExpireBlocks(blockHardTTL) {
if peer := d.peers.Peer(pid); peer != nil {
peer.Demote()
glog.V(logger.Detail).Infof("%s: block delivery timeout", peer)
}
}
// If there's nothing more to fetch, wait or terminate
if d.queue.PendingBlocks() == 0 {
if !d.queue.InFlightBlocks() && finished {
glog.V(logger.Debug).Infof("Block fetching completed")
return nil
}
break
}
// Send a download request to all idle peers, until throttled
throttled := false
idles, total := d.peers.BlockIdlePeers()
for _, peer := range idles {
// Short circuit if throttling activated
if d.queue.ShouldThrottleBlocks() {
throttled = true
break
}
// Reserve a chunk of hashes for a peer. A nil can mean either that
// no more hashes are available, or that the peer is known not to
// have them.
request := d.queue.ReserveBlocks(peer, peer.BlockCapacity())
if request == nil {
continue
}
if glog.V(logger.Detail) {
glog.Infof("%s: requesting %d blocks", peer, len(request.Hashes))
}
// Fetch the chunk and make sure any errors return the hashes to the queue
if err := peer.Fetch61(request); err != nil {
// Although we could try and make an attempt to fix this, this error really
// means that we've double allocated a fetch task to a peer. If that is the
// case, the internal state of the downloader and the queue is very wrong so
// better hard crash and note the error instead of silently accumulating into
// a much bigger issue.
panic(fmt.Sprintf("%v: fetch assignment failed, hard panic", peer))
d.queue.CancelBlocks(request) // noop for now
}
}
// Make sure that we have peers available for fetching. If all peers have been tried
// and all failed throw an error
if !throttled && !d.queue.InFlightBlocks() && len(idles) == total {
return errPeersUnavailable
}
}
}
}
// fetchHeight retrieves the head header of the remote peer to aid in estimating
// the total time a pending synchronisation would take.
func (d *Downloader) fetchHeight(p *peer) (uint64, error) {
glog.V(logger.Debug).Infof("%v: retrieving remote chain height", p)
// Request the advertised remote head block and wait for the response
go p.getRelHeaders(p.head, 1, 0, false)
timeout := time.After(headerTTL)
for {
select {
case <-d.cancelCh:
return 0, errCancelBlockFetch
case packet := <-d.headerCh:
// Discard anything not from the origin peer
if packet.PeerId() != p.id {
glog.V(logger.Debug).Infof("Received headers from incorrect peer(%s)", packet.PeerId())
break
}
// Make sure the peer actually gave something valid
headers := packet.(*headerPack).headers
if len(headers) != 1 {
glog.V(logger.Debug).Infof("%v: invalid number of head headers: %d != 1", p, len(headers))
return 0, errBadPeer
}
return headers[0].Number.Uint64(), nil
case <-d.bodyCh:
// Out of bounds block bodies received, ignore them
case <-d.hashCh:
// Out of bounds eth/61 hashes received, ignore them
case <-d.blockCh:
// Out of bounds eth/61 blocks received, ignore them
case <-timeout:
glog.V(logger.Debug).Infof("%v: head header timeout", p)
return 0, errTimeout
}
}
}
// findAncestor tries to locate the common ancestor link of the local chain and
// a remote peers blockchain. In the general case when our node was in sync and
// on the correct chain, checking the top N links should already get us a match.
// In the rare scenario when we ended up on a long reorganization (i.e. none of
// the head links match), we do a binary search to find the common ancestor.
func (d *Downloader) findAncestor(p *peer) (uint64, error) {
glog.V(logger.Debug).Infof("%v: looking for common ancestor", p)
// Request our head headers to short circuit ancestor location
head := d.headHeader().Number.Uint64()
if d.mode == FullSync {
head = d.headBlock().NumberU64()
} else if d.mode == FastSync {
head = d.headFastBlock().NumberU64()
}
from := int64(head) - int64(MaxHeaderFetch) + 1
if from < 0 {
from = 0
}
go p.getAbsHeaders(uint64(from), MaxHeaderFetch, 0, false)
// Wait for the remote response to the head fetch
number, hash := uint64(0), common.Hash{}
timeout := time.After(hashTTL)
for finished := false; !finished; {
select {
case <-d.cancelCh:
return 0, errCancelHashFetch
case packet := <-d.headerCh:
// Discard anything not from the origin peer
if packet.PeerId() != p.id {
glog.V(logger.Debug).Infof("Received headers from incorrect peer(%s)", packet.PeerId())
break
}
// Make sure the peer actually gave something valid
headers := packet.(*headerPack).headers
if len(headers) == 0 {
glog.V(logger.Debug).Infof("%v: empty head header set", p)
return 0, errEmptyHeaderSet
}
// Check if a common ancestor was found
finished = true
for i := len(headers) - 1; i >= 0; i-- {
if (d.mode != LightSync && d.hasBlock(headers[i].Hash())) || (d.mode == LightSync && d.hasHeader(headers[i].Hash())) {
number, hash = headers[i].Number.Uint64(), headers[i].Hash()
break
}
}
case <-d.bodyCh:
// Out of bounds block bodies received, ignore them
case <-d.hashCh:
// Out of bounds eth/61 hashes received, ignore them
case <-d.blockCh:
// Out of bounds eth/61 blocks received, ignore them
case <-timeout:
glog.V(logger.Debug).Infof("%v: head header timeout", p)
return 0, errTimeout
}
}
// If the head fetch already found an ancestor, return
if !common.EmptyHash(hash) {
glog.V(logger.Debug).Infof("%v: common ancestor: #%d [%x…]", p, number, hash[:4])
return number, nil
}
// Ancestor not found, we need to binary search over our chain
start, end := uint64(0), head
for start+1 < end {
// Split our chain interval in two, and request the hash to cross check
check := (start + end) / 2
timeout := time.After(hashTTL)
go p.getAbsHeaders(uint64(check), 1, 0, false)
// Wait until a reply arrives to this request
for arrived := false; !arrived; {
select {
case <-d.cancelCh:
return 0, errCancelHashFetch
case packer := <-d.headerCh:
// Discard anything not from the origin peer
if packer.PeerId() != p.id {
glog.V(logger.Debug).Infof("Received headers from incorrect peer(%s)", packer.PeerId())
break
}
// Make sure the peer actually gave something valid
headers := packer.(*headerPack).headers
if len(headers) != 1 {
glog.V(logger.Debug).Infof("%v: invalid search header set (%d)", p, len(headers))
return 0, errBadPeer
}
arrived = true
// Modify the search interval based on the response
if (d.mode == FullSync && !d.hasBlock(headers[0].Hash())) || (d.mode != FullSync && !d.hasHeader(headers[0].Hash())) {
end = check
break
}
header := d.getHeader(headers[0].Hash()) // Independent of sync mode, header surely exists
if header.Number.Uint64() != check {
glog.V(logger.Debug).Infof("%v: non requested header #%d [%x…], instead of #%d", p, header.Number, header.Hash().Bytes()[:4], check)
return 0, errBadPeer
}
start = check
case <-d.bodyCh:
// Out of bounds block bodies received, ignore them
case <-d.hashCh:
// Out of bounds eth/61 hashes received, ignore them
case <-d.blockCh:
// Out of bounds eth/61 blocks received, ignore them
case <-timeout:
glog.V(logger.Debug).Infof("%v: search header timeout", p)
return 0, errTimeout
}
}
}
return start, nil
}
// fetchHeaders keeps retrieving headers from the requested number, until no more
// are returned, potentially throttling on the way.
//
// The queue parameter can be used to switch between queuing headers for block
// body download too, or directly import as pure header chains.
func (d *Downloader) fetchHeaders(p *peer, td *big.Int, from uint64) error {
glog.V(logger.Debug).Infof("%v: downloading headers from #%d", p, from)
defer glog.V(logger.Debug).Infof("%v: header download terminated", p)
// Calculate the pivoting point for switching from fast to slow sync
pivot := d.queue.FastSyncPivot()
// Keep a count of uncertain headers to roll back
rollback := []*types.Header{}
defer func() {
if len(rollback) > 0 {
// Flatten the headers and roll them back
hashes := make([]common.Hash, len(rollback))
for i, header := range rollback {
hashes[i] = header.Hash()
}
lh, lfb, lb := d.headHeader().Number, d.headFastBlock().Number(), d.headBlock().Number()
d.rollback(hashes)
glog.V(logger.Warn).Infof("Rolled back %d headers (LH: %d->%d, FB: %d->%d, LB: %d->%d)",
len(hashes), lh, d.headHeader().Number, lfb, d.headFastBlock().Number(), lb, d.headBlock().Number())
// If we're already past the pivot point, this could be an attack, disable fast sync
if rollback[len(rollback)-1].Number.Uint64() > pivot {
d.noFast = true
}
}
}()
// Create a timeout timer, and the associated hash fetcher
request := time.Now() // time of the last fetch request
timeout := time.NewTimer(0) // timer to dump a non-responsive active peer
<-timeout.C // timeout channel should be initially empty
defer timeout.Stop()
getHeaders := func(from uint64) {
glog.V(logger.Detail).Infof("%v: fetching %d headers from #%d", p, MaxHeaderFetch, from)
go p.getAbsHeaders(from, MaxHeaderFetch, 0, false)
request = time.Now()
timeout.Reset(headerTTL)
}
// Start pulling headers, until all are exhausted
getHeaders(from)
gotHeaders := false
for {
select {
case <-d.cancelCh:
return errCancelHeaderFetch
case <-d.hashCh:
// Out of bounds eth/61 hashes received, ignore them
case <-d.blockCh:
// Out of bounds eth/61 blocks received, ignore them
case packet := <-d.headerCh:
// Make sure the active peer is giving us the headers
if packet.PeerId() != p.id {
glog.V(logger.Debug).Infof("Received headers from incorrect peer (%s)", packet.PeerId())
break
}
headerReqTimer.UpdateSince(request)
timeout.Stop()
// If no more headers are inbound, notify the content fetchers and return
if packet.Items() == 0 {
glog.V(logger.Debug).Infof("%v: no available headers", p)
for _, ch := range []chan bool{d.bodyWakeCh, d.receiptWakeCh, d.stateWakeCh} {
select {
case ch <- false:
case <-d.cancelCh:
}
}
// If no headers were retrieved at all, the peer violated it's TD promise that it had a
// better chain compared to ours. The only exception is if it's promised blocks were
// already imported by other means (e.g. fecher):
//
// R , L : Both at block 10
// R: Mine block 11, and propagate it to L
// L: Queue block 11 for import
// L: Notice that R's head and TD increased compared to ours, start sync
// L: Import of block 11 finishes
// L: Sync begins, and finds common ancestor at 11
// L: Request new headers up from 11 (R's TD was higher, it must have something)
// R: Nothing to give
if !gotHeaders && td.Cmp(d.getTd(d.headBlock().Hash())) > 0 {
return errStallingPeer
}
// If fast or light syncing, ensure promised headers are indeed delivered. This is
// needed to detect scenarios where an attacker feeds a bad pivot and then bails out
// of delivering the post-pivot blocks that would flag the invalid content.
//
// This check cannot be executed "as is" for full imports, since blocks may still be
// queued for processing when the header download completes. However, as long as the
// peer gave us something useful, we're already happy/progressed (above check).
if d.mode == FastSync || d.mode == LightSync {
if td.Cmp(d.getTd(d.headHeader().Hash())) > 0 {
return errStallingPeer
}
}
rollback = nil
return nil
}
gotHeaders = true
headers := packet.(*headerPack).headers
// Otherwise insert all the new headers, aborting in case of junk
glog.V(logger.Detail).Infof("%v: schedule %d headers from #%d", p, len(headers), from)
if d.mode == FastSync || d.mode == LightSync {
// Collect the yet unknown headers to mark them as uncertain
unknown := make([]*types.Header, 0, len(headers))
for _, header := range headers {
if !d.hasHeader(header.Hash()) {
unknown = append(unknown, header)
}
}
// If we're importing pure headers, verify based on their recentness
frequency := fsHeaderCheckFrequency
if headers[len(headers)-1].Number.Uint64()+uint64(fsHeaderForceVerify) > pivot {
frequency = 1
}
if n, err := d.insertHeaders(headers, frequency); err != nil {
glog.V(logger.Debug).Infof("%v: invalid header #%d [%x…]: %v", p, headers[n].Number, headers[n].Hash().Bytes()[:4], err)
return errInvalidChain
}
// All verifications passed, store newly found uncertain headers
rollback = append(rollback, unknown...)
if len(rollback) > fsHeaderSafetyNet {
rollback = append(rollback[:0], rollback[len(rollback)-fsHeaderSafetyNet:]...)
}
}
if d.mode == FullSync || d.mode == FastSync {
inserts := d.queue.Schedule(headers, from)
if len(inserts) != len(headers) {
glog.V(logger.Debug).Infof("%v: stale headers", p)
return errBadPeer
}
}
// Notify the content fetchers of new headers, but stop if queue is full
cont := d.queue.PendingBlocks() < maxQueuedHeaders || d.queue.PendingReceipts() < maxQueuedHeaders
for _, ch := range []chan bool{d.bodyWakeCh, d.receiptWakeCh, d.stateWakeCh} {
if cont {
// We still have headers to fetch, send continuation wake signal (potential)
select {
case ch <- true:
default:
}
} else {
// Header limit reached, send a termination wake signal (enforced)
select {
case ch <- false:
case <-d.cancelCh:
}
return nil
}
}
// Queue not yet full, fetch the next batch
from += uint64(len(headers))
getHeaders(from)
case <-timeout.C:
// Header retrieval timed out, consider the peer bad and drop
glog.V(logger.Debug).Infof("%v: header request timed out", p)
headerTimeoutMeter.Mark(1)
d.dropPeer(p.id)
// Finish the sync gracefully instead of dumping the gathered data though
for _, ch := range []chan bool{d.bodyWakeCh, d.receiptWakeCh, d.stateWakeCh} {
select {
case ch <- false:
case <-d.cancelCh:
}
}
return nil
}
}
}
// fetchBodies iteratively downloads the scheduled block bodies, taking any
// available peers, reserving a chunk of blocks for each, waiting for delivery
// and also periodically checking for timeouts.
func (d *Downloader) fetchBodies(from uint64) error {
glog.V(logger.Debug).Infof("Downloading block bodies from #%d", from)
var (
deliver = func(packet dataPack) error {
pack := packet.(*bodyPack)
return d.queue.DeliverBodies(pack.peerId, pack.transactions, pack.uncles)
}
expire = func() []string { return d.queue.ExpireBodies(bodyHardTTL) }
fetch = func(p *peer, req *fetchRequest) error { return p.FetchBodies(req) }
capacity = func(p *peer) int { return p.BlockCapacity() }
setIdle = func(p *peer) { p.SetBodiesIdle() }
)
err := d.fetchParts(errCancelBodyFetch, d.bodyCh, deliver, d.bodyWakeCh, expire,
d.queue.PendingBlocks, d.queue.InFlightBlocks, d.queue.ShouldThrottleBlocks, d.queue.ReserveBodies,
d.bodyFetchHook, fetch, d.queue.CancelBodies, capacity, d.peers.BodyIdlePeers, setIdle, "Body")
glog.V(logger.Debug).Infof("Block body download terminated: %v", err)
return err
}
// fetchReceipts iteratively downloads the scheduled block receipts, taking any
// available peers, reserving a chunk of receipts for each, waiting for delivery
// and also periodically checking for timeouts.
func (d *Downloader) fetchReceipts(from uint64) error {
glog.V(logger.Debug).Infof("Downloading receipts from #%d", from)
var (
deliver = func(packet dataPack) error {
pack := packet.(*receiptPack)
return d.queue.DeliverReceipts(pack.peerId, pack.receipts)
}
expire = func() []string { return d.queue.ExpireReceipts(receiptHardTTL) }
fetch = func(p *peer, req *fetchRequest) error { return p.FetchReceipts(req) }
capacity = func(p *peer) int { return p.ReceiptCapacity() }
setIdle = func(p *peer) { p.SetReceiptsIdle() }
)
err := d.fetchParts(errCancelReceiptFetch, d.receiptCh, deliver, d.receiptWakeCh, expire,
d.queue.PendingReceipts, d.queue.InFlightReceipts, d.queue.ShouldThrottleReceipts, d.queue.ReserveReceipts,
d.receiptFetchHook, fetch, d.queue.CancelReceipts, capacity, d.peers.ReceiptIdlePeers, setIdle, "Receipt")
glog.V(logger.Debug).Infof("Receipt download terminated: %v", err)
return err
}
// fetchNodeData iteratively downloads the scheduled state trie nodes, taking any
// available peers, reserving a chunk of nodes for each, waiting for delivery and
// also periodically checking for timeouts.
func (d *Downloader) fetchNodeData() error {
glog.V(logger.Debug).Infof("Downloading node state data")
var (
deliver = func(packet dataPack) error {
start := time.Now()
return d.queue.DeliverNodeData(packet.PeerId(), packet.(*statePack).states, func(err error, delivered int) {
if err != nil {
// If the node data processing failed, the root hash is very wrong, abort
glog.V(logger.Error).Infof("peer %d: state processing failed: %v", packet.PeerId(), err)
d.cancel()
return
}
// Processing succeeded, notify state fetcher of continuation
if d.queue.PendingNodeData() > 0 {
select {
case d.stateWakeCh <- true:
default:
}
}
// Log a message to the user and return
d.syncStatsLock.Lock()
defer d.syncStatsLock.Unlock()
d.syncStatsStateDone += uint64(delivered)
glog.V(logger.Info).Infof("imported %d state entries in %v: processed %d in total", delivered, time.Since(start), d.syncStatsStateDone)
})
}
expire = func() []string { return d.queue.ExpireNodeData(stateHardTTL) }
throttle = func() bool { return false }
reserve = func(p *peer, count int) (*fetchRequest, bool, error) {
return d.queue.ReserveNodeData(p, count), false, nil
}
fetch = func(p *peer, req *fetchRequest) error { return p.FetchNodeData(req) }
capacity = func(p *peer) int { return p.NodeDataCapacity() }
setIdle = func(p *peer) { p.SetNodeDataIdle() }
)
err := d.fetchParts(errCancelStateFetch, d.stateCh, deliver, d.stateWakeCh, expire,
d.queue.PendingNodeData, d.queue.InFlightNodeData, throttle, reserve, nil, fetch,
d.queue.CancelNodeData, capacity, d.peers.NodeDataIdlePeers, setIdle, "State")
glog.V(logger.Debug).Infof("Node state data download terminated: %v", err)
return err
}
// fetchParts iteratively downloads scheduled block parts, taking any available
// peers, reserving a chunk of fetch requests for each, waiting for delivery and
// also periodically checking for timeouts.
func (d *Downloader) fetchParts(errCancel error, deliveryCh chan dataPack, deliver func(packet dataPack) error, wakeCh chan bool,
expire func() []string, pending func() int, inFlight func() bool, throttle func() bool, reserve func(*peer, int) (*fetchRequest, bool, error),
fetchHook func([]*types.Header), fetch func(*peer, *fetchRequest) error, cancel func(*fetchRequest), capacity func(*peer) int,
idle func() ([]*peer, int), setIdle func(*peer), kind string) error {
// Create a ticker to detect expired retrieval tasks
ticker := time.NewTicker(100 * time.Millisecond)
defer ticker.Stop()
update := make(chan struct{}, 1)
// Prepare the queue and fetch block parts until the block header fetcher's done
finished := false
for {
select {
case <-d.cancelCh:
return errCancel
case <-d.hashCh:
// Out of bounds eth/61 hashes received, ignore them
case <-d.blockCh:
// Out of bounds eth/61 blocks received, ignore them
case packet := <-deliveryCh:
// If the peer was previously banned and failed to deliver it's pack
// in a reasonable time frame, ignore it's message.
if peer := d.peers.Peer(packet.PeerId()); peer != nil {
// Deliver the received chunk of data, and demote in case of errors
switch err := deliver(packet); err {
case nil:
// If no blocks were delivered, demote the peer (need the delivery above to clean internal queue!)
if packet.Items() == 0 {
peer.Demote()
setIdle(peer)
glog.V(logger.Detail).Infof("%s: no %s delivered", peer, strings.ToLower(kind))
break
}
// All was successful, promote the peer and potentially start processing
peer.Promote()
setIdle(peer)
glog.V(logger.Detail).Infof("%s: delivered %s %s(s)", peer, packet.Stats(), strings.ToLower(kind))
case errInvalidChain:
// The hash chain is invalid (blocks are not ordered properly), abort
return err
case errNoFetchesPending:
// Peer probably timed out with its delivery but came through
// in the end, demote, but allow to to pull from this peer.
peer.Demote()
setIdle(peer)
glog.V(logger.Detail).Infof("%s: out of bound %s delivery", peer, strings.ToLower(kind))
case errStaleDelivery:
// Delivered something completely else than requested, usually
// caused by a timeout and delivery during a new sync cycle.
// Don't set it to idle as the original request should still be
// in flight.
peer.Demote()
glog.V(logger.Detail).Infof("%s: %s stale delivery", peer, strings.ToLower(kind))
default:
// Peer did something semi-useful, demote but keep it around
peer.Demote()
setIdle(peer)
glog.V(logger.Detail).Infof("%s: %s delivery partially failed: %v", peer, strings.ToLower(kind), err)
}
}
// Blocks assembled, try to update the progress
select {
case update <- struct{}{}:
default:
}
case cont := <-wakeCh:
// The header fetcher sent a continuation flag, check if it's done
if !cont {
finished = true
}
// Headers arrive, try to update the progress
select {
case update <- struct{}{}:
default:
}
case <-ticker.C:
// Sanity check update the progress
select {
case update <- struct{}{}:
default:
}
case <-update:
// Short circuit if we lost all our peers
if d.peers.Len() == 0 {
return errNoPeers
}
// Check for fetch request timeouts and demote the responsible peers
for _, pid := range expire() {
if peer := d.peers.Peer(pid); peer != nil {
peer.Demote()
setIdle(peer)
glog.V(logger.Detail).Infof("%s: %s delivery timeout", peer, strings.ToLower(kind))
}
}
// If there's nothing more to fetch, wait or terminate
if pending() == 0 {
if !inFlight() && finished {
glog.V(logger.Debug).Infof("%s fetching completed", kind)
return nil
}
break
}
// Send a download request to all idle peers, until throttled
progressed, throttled, running := false, false, inFlight()
idles, total := idle()
for _, peer := range idles {
// Short circuit if throttling activated
if throttle() {
throttled = true
break
}
// Reserve a chunk of fetches for a peer. A nil can mean either that
// no more headers are available, or that the peer is known not to
// have them.
request, progress, err := reserve(peer, capacity(peer))
if err != nil {
return err
}
if progress {
progressed = true
}
if request == nil {
continue
}
if glog.V(logger.Detail) {
if len(request.Headers) > 0 {
glog.Infof("%s: requesting %d %s(s), first at #%d", peer, len(request.Headers), strings.ToLower(kind), request.Headers[0].Number)
} else {
glog.Infof("%s: requesting %d %s(s)", peer, len(request.Hashes), strings.ToLower(kind))
}
}
// Fetch the chunk and make sure any errors return the hashes to the queue
if fetchHook != nil {
fetchHook(request.Headers)
}
if err := fetch(peer, request); err != nil {
// Although we could try and make an attempt to fix this, this error really
// means that we've double allocated a fetch task to a peer. If that is the
// case, the internal state of the downloader and the queue is very wrong so
// better hard crash and note the error instead of silently accumulating into
// a much bigger issue.
panic(fmt.Sprintf("%v: %s fetch assignment failed, hard panic", peer, strings.ToLower(kind)))
cancel(request) // noop for now
}
running = true
}
// Make sure that we have peers available for fetching. If all peers have been tried
// and all failed throw an error
if !progressed && !throttled && !running && len(idles) == total && pending() > 0 {
return errPeersUnavailable
}
}
}
}
// process takes fetch results from the queue and tries to import them into the
// chain. The type of import operation will depend on the result contents.
func (d *Downloader) process() error {
pivot := d.queue.FastSyncPivot()
for {
results := d.queue.WaitResults()
if len(results) == 0 {
return nil // queue empty
}
if d.chainInsertHook != nil {
d.chainInsertHook(results)
}
// Actually import the blocks
if glog.V(logger.Debug) {
first, last := results[0].Header, results[len(results)-1].Header
glog.Infof("Inserting chain with %d items (#%d [%x…] - #%d [%x…])", len(results), first.Number, first.Hash().Bytes()[:4], last.Number, last.Hash().Bytes()[:4])
}
for len(results) != 0 {
// Check for any termination requests
if atomic.LoadInt32(&d.interrupt) == 1 {
return errCancelProcessing
}
// Retrieve the a batch of results to import
var (
blocks = make([]*types.Block, 0, maxResultsProcess)
receipts = make([]types.Receipts, 0, maxResultsProcess)
)
items := int(math.Min(float64(len(results)), float64(maxResultsProcess)))
for _, result := range results[:items] {
switch {
case d.mode == FullSync:
blocks = append(blocks, types.NewBlockWithHeader(result.Header).WithBody(result.Transactions, result.Uncles))
case d.mode == FastSync:
blocks = append(blocks, types.NewBlockWithHeader(result.Header).WithBody(result.Transactions, result.Uncles))
if result.Header.Number.Uint64() <= pivot {
receipts = append(receipts, result.Receipts)
}
}
}
// Try to process the results, aborting if there's an error
var (
err error
index int
)
switch {
case len(receipts) > 0:
index, err = d.insertReceipts(blocks, receipts)
if err == nil && blocks[len(blocks)-1].NumberU64() == pivot {
glog.V(logger.Debug).Infof("Committing block #%d [%x…] as the new head", blocks[len(blocks)-1].Number(), blocks[len(blocks)-1].Hash().Bytes()[:4])
index, err = len(blocks)-1, d.commitHeadBlock(blocks[len(blocks)-1].Hash())
}
default:
index, err = d.insertBlocks(blocks)
}
if err != nil {
glog.V(logger.Debug).Infof("Result #%d [%x…] processing failed: %v", results[index].Header.Number, results[index].Header.Hash().Bytes()[:4], err)
return err
}
// Shift the results to the next batch
results = results[items:]
}
}
}
// DeliverHashes injects a new batch of hashes received from a remote node into
// the download schedule. This is usually invoked through the BlockHashesMsg by
// the protocol handler.
func (d *Downloader) DeliverHashes(id string, hashes []common.Hash) (err error) {
return d.deliver(id, d.hashCh, &hashPack{id, hashes}, hashInMeter, hashDropMeter)
}
// DeliverBlocks injects a new batch of blocks received from a remote node.
// This is usually invoked through the BlocksMsg by the protocol handler.
func (d *Downloader) DeliverBlocks(id string, blocks []*types.Block) (err error) {
return d.deliver(id, d.blockCh, &blockPack{id, blocks}, blockInMeter, blockDropMeter)
}
// DeliverHeaders injects a new batch of blck headers received from a remote
// node into the download schedule.
func (d *Downloader) DeliverHeaders(id string, headers []*types.Header) (err error) {
return d.deliver(id, d.headerCh, &headerPack{id, headers}, headerInMeter, headerDropMeter)
}
// DeliverBodies injects a new batch of block bodies received from a remote node.
func (d *Downloader) DeliverBodies(id string, transactions [][]*types.Transaction, uncles [][]*types.Header) (err error) {
return d.deliver(id, d.bodyCh, &bodyPack{id, transactions, uncles}, bodyInMeter, bodyDropMeter)
}
// DeliverReceipts injects a new batch of receipts received from a remote node.
func (d *Downloader) DeliverReceipts(id string, receipts [][]*types.Receipt) (err error) {
return d.deliver(id, d.receiptCh, &receiptPack{id, receipts}, receiptInMeter, receiptDropMeter)
}
// DeliverNodeData injects a new batch of node state data received from a remote node.
func (d *Downloader) DeliverNodeData(id string, data [][]byte) (err error) {
return d.deliver(id, d.stateCh, &statePack{id, data}, stateInMeter, stateDropMeter)
}
// deliver injects a new batch of data received from a remote node.
func (d *Downloader) deliver(id string, destCh chan dataPack, packet dataPack, inMeter, dropMeter metrics.Meter) (err error) {
// Update the delivery metrics for both good and failed deliveries
inMeter.Mark(int64(packet.Items()))
defer func() {
if err != nil {
dropMeter.Mark(int64(packet.Items()))
}
}()
// Deliver or abort if the sync is canceled while queuing
d.cancelLock.RLock()
cancel := d.cancelCh
d.cancelLock.RUnlock()
if cancel == nil {
return errNoSyncActive
}
select {
case destCh <- packet:
return nil
case <-cancel:
return errNoSyncActive
}
}