280 lines
10 KiB
Go
280 lines
10 KiB
Go
// Copyright 2015 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package eth
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import (
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"errors"
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"math/big"
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"time"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/core/rawdb"
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"github.com/ethereum/go-ethereum/core/types"
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"github.com/ethereum/go-ethereum/eth/downloader"
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"github.com/ethereum/go-ethereum/eth/protocols/eth"
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"github.com/ethereum/go-ethereum/log"
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)
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const (
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forceSyncCycle = 10 * time.Second // Time interval to force syncs, even if few peers are available
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defaultMinSyncPeers = 5 // Amount of peers desired to start syncing
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)
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// syncTransactions starts sending all currently pending transactions to the given peer.
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func (h *handler) syncTransactions(p *eth.Peer) {
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// Assemble the set of transaction to broadcast or announce to the remote
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// peer. Fun fact, this is quite an expensive operation as it needs to sort
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// the transactions if the sorting is not cached yet. However, with a random
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// order, insertions could overflow the non-executable queues and get dropped.
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//
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// TODO(karalabe): Figure out if we could get away with random order somehow
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var txs types.Transactions
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pending := h.txpool.Pending(false)
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for _, batch := range pending {
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txs = append(txs, batch...)
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}
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if len(txs) == 0 {
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return
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}
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// The eth/65 protocol introduces proper transaction announcements, so instead
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// of dripping transactions across multiple peers, just send the entire list as
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// an announcement and let the remote side decide what they need (likely nothing).
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hashes := make([]common.Hash, len(txs))
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for i, tx := range txs {
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hashes[i] = tx.Hash()
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}
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p.AsyncSendPooledTransactionHashes(hashes)
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}
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// chainSyncer coordinates blockchain sync components.
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type chainSyncer struct {
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handler *handler
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force *time.Timer
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forced bool // true when force timer fired
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warned time.Time
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peerEventCh chan struct{}
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doneCh chan error // non-nil when sync is running
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}
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// chainSyncOp is a scheduled sync operation.
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type chainSyncOp struct {
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mode downloader.SyncMode
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peer *eth.Peer
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td *big.Int
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head common.Hash
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}
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// newChainSyncer creates a chainSyncer.
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func newChainSyncer(handler *handler) *chainSyncer {
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return &chainSyncer{
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handler: handler,
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peerEventCh: make(chan struct{}),
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}
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}
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// handlePeerEvent notifies the syncer about a change in the peer set.
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// This is called for new peers and every time a peer announces a new
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// chain head.
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func (cs *chainSyncer) handlePeerEvent() bool {
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select {
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case cs.peerEventCh <- struct{}{}:
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return true
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case <-cs.handler.quitSync:
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return false
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}
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}
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// loop runs in its own goroutine and launches the sync when necessary.
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func (cs *chainSyncer) loop() {
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defer cs.handler.wg.Done()
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cs.handler.blockFetcher.Start()
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cs.handler.txFetcher.Start()
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defer cs.handler.blockFetcher.Stop()
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defer cs.handler.txFetcher.Stop()
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defer cs.handler.downloader.Terminate()
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// The force timer lowers the peer count threshold down to one when it fires.
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// This ensures we'll always start sync even if there aren't enough peers.
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cs.force = time.NewTimer(forceSyncCycle)
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defer cs.force.Stop()
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for {
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if op := cs.nextSyncOp(); op != nil {
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cs.startSync(op)
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}
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select {
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case <-cs.peerEventCh:
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// Peer information changed, recheck.
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case err := <-cs.doneCh:
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cs.doneCh = nil
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cs.force.Reset(forceSyncCycle)
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cs.forced = false
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// If we've reached the merge transition but no beacon client is available, or
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// it has not yet switched us over, keep warning the user that their infra is
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// potentially flaky.
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if errors.Is(err, downloader.ErrMergeTransition) && time.Since(cs.warned) > 10*time.Second {
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log.Warn("Local chain is post-merge, waiting for beacon client sync switch-over...")
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cs.warned = time.Now()
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}
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case <-cs.force.C:
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cs.forced = true
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case <-cs.handler.quitSync:
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// Disable all insertion on the blockchain. This needs to happen before
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// terminating the downloader because the downloader waits for blockchain
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// inserts, and these can take a long time to finish.
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cs.handler.chain.StopInsert()
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cs.handler.downloader.Terminate()
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if cs.doneCh != nil {
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<-cs.doneCh
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}
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return
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}
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}
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}
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// nextSyncOp determines whether sync is required at this time.
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func (cs *chainSyncer) nextSyncOp() *chainSyncOp {
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if cs.doneCh != nil {
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return nil // Sync already running
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}
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// If a beacon client once took over control, disable the entire legacy sync
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// path from here on end. Note, there is a slight "race" between reaching TTD
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// and the beacon client taking over. The downloader will enforce that nothing
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// above the first TTD will be delivered to the chain for import.
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//
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// An alternative would be to check the local chain for exceeding the TTD and
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// avoid triggering a sync in that case, but that could also miss sibling or
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// other family TTD block being accepted.
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if cs.handler.chain.Config().TerminalTotalDifficultyPassed || cs.handler.merger.TDDReached() {
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return nil
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}
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// Ensure we're at minimum peer count.
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minPeers := defaultMinSyncPeers
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if cs.forced {
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minPeers = 1
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} else if minPeers > cs.handler.maxPeers {
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minPeers = cs.handler.maxPeers
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}
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if cs.handler.peers.len() < minPeers {
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return nil
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}
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// We have enough peers, pick the one with the highest TD, but avoid going
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// over the terminal total difficulty. Above that we expect the consensus
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// clients to direct the chain head to sync to.
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peer := cs.handler.peers.peerWithHighestTD()
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if peer == nil {
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return nil
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}
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mode, ourTD := cs.modeAndLocalHead()
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op := peerToSyncOp(mode, peer)
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if op.td.Cmp(ourTD) <= 0 {
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// We seem to be in sync according to the legacy rules. In the merge
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// world, it can also mean we're stuck on the merge block, waiting for
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// a beacon client. In the latter case, notify the user.
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if ttd := cs.handler.chain.Config().TerminalTotalDifficulty; ttd != nil && ourTD.Cmp(ttd) >= 0 && time.Since(cs.warned) > 10*time.Second {
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log.Warn("Local chain is post-merge, waiting for beacon client sync switch-over...")
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cs.warned = time.Now()
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}
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return nil // We're in sync
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}
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return op
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}
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func peerToSyncOp(mode downloader.SyncMode, p *eth.Peer) *chainSyncOp {
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peerHead, peerTD := p.Head()
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return &chainSyncOp{mode: mode, peer: p, td: peerTD, head: peerHead}
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}
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func (cs *chainSyncer) modeAndLocalHead() (downloader.SyncMode, *big.Int) {
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// If we're in snap sync mode, return that directly
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if cs.handler.snapSync.Load() {
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block := cs.handler.chain.CurrentSnapBlock()
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td := cs.handler.chain.GetTd(block.Hash(), block.Number.Uint64())
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return downloader.SnapSync, td
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}
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// We are probably in full sync, but we might have rewound to before the
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// snap sync pivot, check if we should reenable
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if pivot := rawdb.ReadLastPivotNumber(cs.handler.database); pivot != nil {
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if head := cs.handler.chain.CurrentBlock(); head.Number.Uint64() < *pivot {
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block := cs.handler.chain.CurrentSnapBlock()
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td := cs.handler.chain.GetTd(block.Hash(), block.Number.Uint64())
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return downloader.SnapSync, td
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}
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}
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// Nope, we're really full syncing
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head := cs.handler.chain.CurrentBlock()
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td := cs.handler.chain.GetTd(head.Hash(), head.Number.Uint64())
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return downloader.FullSync, td
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}
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// startSync launches doSync in a new goroutine.
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func (cs *chainSyncer) startSync(op *chainSyncOp) {
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cs.doneCh = make(chan error, 1)
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go func() { cs.doneCh <- cs.handler.doSync(op) }()
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}
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// doSync synchronizes the local blockchain with a remote peer.
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func (h *handler) doSync(op *chainSyncOp) error {
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if op.mode == downloader.SnapSync {
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// Before launch the snap sync, we have to ensure user uses the same
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// txlookup limit.
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// The main concern here is: during the snap sync Geth won't index the
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// block(generate tx indices) before the HEAD-limit. But if user changes
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// the limit in the next snap sync(e.g. user kill Geth manually and
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// restart) then it will be hard for Geth to figure out the oldest block
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// has been indexed. So here for the user-experience wise, it's non-optimal
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// that user can't change limit during the snap sync. If changed, Geth
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// will just blindly use the original one.
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limit := h.chain.TxLookupLimit()
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if stored := rawdb.ReadFastTxLookupLimit(h.database); stored == nil {
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rawdb.WriteFastTxLookupLimit(h.database, limit)
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} else if *stored != limit {
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h.chain.SetTxLookupLimit(*stored)
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log.Warn("Update txLookup limit", "provided", limit, "updated", *stored)
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}
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}
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// Run the sync cycle, and disable snap sync if we're past the pivot block
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err := h.downloader.LegacySync(op.peer.ID(), op.head, op.td, h.chain.Config().TerminalTotalDifficulty, op.mode)
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if err != nil {
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return err
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}
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if h.snapSync.Load() {
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log.Info("Snap sync complete, auto disabling")
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h.snapSync.Store(false)
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}
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// If we've successfully finished a sync cycle, enable accepting transactions
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// from the network.
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h.acceptTxs.Store(true)
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head := h.chain.CurrentBlock()
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if head.Number.Uint64() > 0 {
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// We've completed a sync cycle, notify all peers of new state. This path is
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// essential in star-topology networks where a gateway node needs to notify
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// all its out-of-date peers of the availability of a new block. This failure
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// scenario will most often crop up in private and hackathon networks with
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// degenerate connectivity, but it should be healthy for the mainnet too to
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// more reliably update peers or the local TD state.
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if block := h.chain.GetBlock(head.Hash(), head.Number.Uint64()); block != nil {
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h.BroadcastBlock(block, false)
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}
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}
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return nil
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}
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