plugeth/eth/sync.go
Péter Szilágyi c10a0a62c3
eth: request id dispatcher and direct req/reply APIs (#23576)
* eth: request ID based message dispatcher

* eth: fix dispatcher cancellation, rework fetchers idleness tracker

* eth/downloader: drop peers who refuse to serve advertised chains
2021-11-26 13:26:03 +02:00

259 lines
8.7 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 eth
import (
"math/big"
"sync/atomic"
"time"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core/rawdb"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/eth/downloader"
"github.com/ethereum/go-ethereum/eth/protocols/eth"
"github.com/ethereum/go-ethereum/log"
)
const (
forceSyncCycle = 10 * time.Second // Time interval to force syncs, even if few peers are available
defaultMinSyncPeers = 5 // Amount of peers desired to start syncing
)
// syncTransactions starts sending all currently pending transactions to the given peer.
func (h *handler) syncTransactions(p *eth.Peer) {
// Assemble the set of transaction to broadcast or announce to the remote
// peer. Fun fact, this is quite an expensive operation as it needs to sort
// the transactions if the sorting is not cached yet. However, with a random
// order, insertions could overflow the non-executable queues and get dropped.
//
// TODO(karalabe): Figure out if we could get away with random order somehow
var txs types.Transactions
pending := h.txpool.Pending(false)
for _, batch := range pending {
txs = append(txs, batch...)
}
if len(txs) == 0 {
return
}
// The eth/65 protocol introduces proper transaction announcements, so instead
// of dripping transactions across multiple peers, just send the entire list as
// an announcement and let the remote side decide what they need (likely nothing).
hashes := make([]common.Hash, len(txs))
for i, tx := range txs {
hashes[i] = tx.Hash()
}
p.AsyncSendPooledTransactionHashes(hashes)
}
// chainSyncer coordinates blockchain sync components.
type chainSyncer struct {
handler *handler
force *time.Timer
forced bool // true when force timer fired
peerEventCh chan struct{}
doneCh chan error // non-nil when sync is running
}
// chainSyncOp is a scheduled sync operation.
type chainSyncOp struct {
mode downloader.SyncMode
peer *eth.Peer
td *big.Int
head common.Hash
}
// newChainSyncer creates a chainSyncer.
func newChainSyncer(handler *handler) *chainSyncer {
return &chainSyncer{
handler: handler,
peerEventCh: make(chan struct{}),
}
}
// handlePeerEvent notifies the syncer about a change in the peer set.
// This is called for new peers and every time a peer announces a new
// chain head.
func (cs *chainSyncer) handlePeerEvent(peer *eth.Peer) bool {
select {
case cs.peerEventCh <- struct{}{}:
return true
case <-cs.handler.quitSync:
return false
}
}
// loop runs in its own goroutine and launches the sync when necessary.
func (cs *chainSyncer) loop() {
defer cs.handler.wg.Done()
cs.handler.blockFetcher.Start()
cs.handler.txFetcher.Start()
defer cs.handler.blockFetcher.Stop()
defer cs.handler.txFetcher.Stop()
defer cs.handler.downloader.Terminate()
// The force timer lowers the peer count threshold down to one when it fires.
// This ensures we'll always start sync even if there aren't enough peers.
cs.force = time.NewTimer(forceSyncCycle)
defer cs.force.Stop()
for {
if op := cs.nextSyncOp(); op != nil {
cs.startSync(op)
}
select {
case <-cs.peerEventCh:
// Peer information changed, recheck.
case <-cs.doneCh:
cs.doneCh = nil
cs.force.Reset(forceSyncCycle)
cs.forced = false
case <-cs.force.C:
cs.forced = true
case <-cs.handler.quitSync:
// Disable all insertion on the blockchain. This needs to happen before
// terminating the downloader because the downloader waits for blockchain
// inserts, and these can take a long time to finish.
cs.handler.chain.StopInsert()
cs.handler.downloader.Terminate()
if cs.doneCh != nil {
<-cs.doneCh
}
return
}
}
}
// nextSyncOp determines whether sync is required at this time.
func (cs *chainSyncer) nextSyncOp() *chainSyncOp {
if cs.doneCh != nil {
return nil // Sync already running.
}
// Disable the td based sync trigger after the transition
if cs.handler.merger.TDDReached() {
return nil
}
// Ensure we're at minimum peer count.
minPeers := defaultMinSyncPeers
if cs.forced {
minPeers = 1
} else if minPeers > cs.handler.maxPeers {
minPeers = cs.handler.maxPeers
}
if cs.handler.peers.len() < minPeers {
return nil
}
// We have enough peers, check TD
peer := cs.handler.peers.peerWithHighestTD()
if peer == nil {
return nil
}
mode, ourTD := cs.modeAndLocalHead()
op := peerToSyncOp(mode, peer)
if op.td.Cmp(ourTD) <= 0 {
return nil // We're in sync.
}
return op
}
func peerToSyncOp(mode downloader.SyncMode, p *eth.Peer) *chainSyncOp {
peerHead, peerTD := p.Head()
return &chainSyncOp{mode: mode, peer: p, td: peerTD, head: peerHead}
}
func (cs *chainSyncer) modeAndLocalHead() (downloader.SyncMode, *big.Int) {
// If we're in snap sync mode, return that directly
if atomic.LoadUint32(&cs.handler.snapSync) == 1 {
block := cs.handler.chain.CurrentFastBlock()
td := cs.handler.chain.GetTd(block.Hash(), block.NumberU64())
return downloader.SnapSync, td
}
// We are probably in full sync, but we might have rewound to before the
// snap sync pivot, check if we should reenable
if pivot := rawdb.ReadLastPivotNumber(cs.handler.database); pivot != nil {
if head := cs.handler.chain.CurrentBlock(); head.NumberU64() < *pivot {
block := cs.handler.chain.CurrentFastBlock()
td := cs.handler.chain.GetTd(block.Hash(), block.NumberU64())
return downloader.SnapSync, td
}
}
// Nope, we're really full syncing
head := cs.handler.chain.CurrentBlock()
td := cs.handler.chain.GetTd(head.Hash(), head.NumberU64())
return downloader.FullSync, td
}
// startSync launches doSync in a new goroutine.
func (cs *chainSyncer) startSync(op *chainSyncOp) {
cs.doneCh = make(chan error, 1)
go func() { cs.doneCh <- cs.handler.doSync(op) }()
}
// doSync synchronizes the local blockchain with a remote peer.
func (h *handler) doSync(op *chainSyncOp) error {
if op.mode == downloader.SnapSync {
// Before launch the snap sync, we have to ensure user uses the same
// txlookup limit.
// The main concern here is: during the snap sync Geth won't index the
// block(generate tx indices) before the HEAD-limit. But if user changes
// the limit in the next snap sync(e.g. user kill Geth manually and
// restart) then it will be hard for Geth to figure out the oldest block
// has been indexed. So here for the user-experience wise, it's non-optimal
// that user can't change limit during the snap sync. If changed, Geth
// will just blindly use the original one.
limit := h.chain.TxLookupLimit()
if stored := rawdb.ReadFastTxLookupLimit(h.database); stored == nil {
rawdb.WriteFastTxLookupLimit(h.database, limit)
} else if *stored != limit {
h.chain.SetTxLookupLimit(*stored)
log.Warn("Update txLookup limit", "provided", limit, "updated", *stored)
}
}
// Run the sync cycle, and disable snap sync if we're past the pivot block
err := h.downloader.Synchronise(op.peer.ID(), op.head, op.td, op.mode)
if err != nil {
return err
}
if atomic.LoadUint32(&h.snapSync) == 1 {
log.Info("Snap sync complete, auto disabling")
atomic.StoreUint32(&h.snapSync, 0)
}
// If we've successfully finished a sync cycle and passed any required checkpoint,
// enable accepting transactions from the network.
head := h.chain.CurrentBlock()
if head.NumberU64() >= h.checkpointNumber {
// Checkpoint passed, sanity check the timestamp to have a fallback mechanism
// for non-checkpointed (number = 0) private networks.
if head.Time() >= uint64(time.Now().AddDate(0, -1, 0).Unix()) {
atomic.StoreUint32(&h.acceptTxs, 1)
}
}
if head.NumberU64() > 0 {
// We've completed a sync cycle, notify all peers of new state. This path is
// essential in star-topology networks where a gateway node needs to notify
// all its out-of-date peers of the availability of a new block. This failure
// scenario will most often crop up in private and hackathon networks with
// degenerate connectivity, but it should be healthy for the mainnet too to
// more reliably update peers or the local TD state.
h.BroadcastBlock(head, false)
}
return nil
}