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eth: improve shutdown synchronization (#20695)

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* eth: improve shutdown synchronization

Most goroutines started by eth.Ethereum didn't have any shutdown sync at
all, which lead to weird error messages when quitting the client.

This change improves the clean shutdown path by stopping all internal
components in dependency order and waiting for them to actually be
stopped before shutdown is considered done. In particular, we now stop
everything related to peers before stopping 'resident' parts such as
core.BlockChain.

* eth: rewrite sync controller

* eth: remove sync start debug message

* eth: notify chainSyncer about new peers after handshake

* eth: move downloader.Cancel call into chainSyncer

* eth: make post-sync block broadcast synchronous

* eth: add comments

* core: change blockchain stop message

* eth: change closeBloomHandler channel type
This commit is contained in:
Felix Lange
2020-03-27 14:03:20 +01:00
committed by GitHub
parent d7851e6359
commit d6c5f2417c
8 changed files with 213 additions and 138 deletions
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182
eth/sync.go
View File

@@ -17,6 +17,7 @@
package eth
import (
"math/big"
"math/rand"
"sync/atomic"
"time"
@@ -30,9 +31,9 @@ import (
const (
forceSyncCycle = 10 * time.Second // Time interval to force syncs, even if few peers are available
minDesiredPeerCount = 5 // Amount of peers desired to start syncing
defaultMinSyncPeers = 5 // Amount of peers desired to start syncing
// This is the target size for the packs of transactions sent by txsyncLoop.
// This is the target size for the packs of transactions sent by txsyncLoop64.
// A pack can get larger than this if a single transactions exceeds this size.
txsyncPackSize = 100 * 1024
)
@@ -81,12 +82,15 @@ func (pm *ProtocolManager) syncTransactions(p *peer) {
// transactions. In order to minimise egress bandwidth usage, we send
// the transactions in small packs to one peer at a time.
func (pm *ProtocolManager) txsyncLoop64() {
defer pm.wg.Done()
var (
pending = make(map[enode.ID]*txsync)
sending = false // whether a send is active
pack = new(txsync) // the pack that is being sent
done = make(chan error, 1) // result of the send
)
// send starts a sending a pack of transactions from the sync.
send := func(s *txsync) {
if s.p.version >= eth65 {
@@ -149,73 +153,148 @@ func (pm *ProtocolManager) txsyncLoop64() {
}
}
// syncer is responsible for periodically synchronising with the network, both
// downloading hashes and blocks as well as handling the announcement handler.
func (pm *ProtocolManager) syncer() {
// Start and ensure cleanup of sync mechanisms
pm.blockFetcher.Start()
pm.txFetcher.Start()
defer pm.blockFetcher.Stop()
defer pm.txFetcher.Stop()
defer pm.downloader.Terminate()
// chainSyncer coordinates blockchain sync components.
type chainSyncer struct {
pm *ProtocolManager
force *time.Timer
forced bool // true when force timer fired
peerEventCh chan struct{}
doneCh chan error // non-nil when sync is running
}
// Wait for different events to fire synchronisation operations
forceSync := time.NewTicker(forceSyncCycle)
defer forceSync.Stop()
// chainSyncOp is a scheduled sync operation.
type chainSyncOp struct {
mode downloader.SyncMode
peer *peer
td *big.Int
head common.Hash
}
// newChainSyncer creates a chainSyncer.
func newChainSyncer(pm *ProtocolManager) *chainSyncer {
return &chainSyncer{
pm: pm,
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(p *peer) bool {
select {
case cs.peerEventCh <- struct{}{}:
return true
case <-cs.pm.quitSync:
return false
}
}
// loop runs in its own goroutine and launches the sync when necessary.
func (cs *chainSyncer) loop() {
defer cs.pm.wg.Done()
cs.pm.blockFetcher.Start()
cs.pm.txFetcher.Start()
defer cs.pm.blockFetcher.Stop()
defer cs.pm.txFetcher.Stop()
defer cs.pm.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 <-pm.newPeerCh:
// Make sure we have peers to select from, then sync
if pm.peers.Len() < minDesiredPeerCount {
break
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.pm.quitSync:
if cs.doneCh != nil {
cs.pm.downloader.Cancel()
<-cs.doneCh
}
go pm.synchronise(pm.peers.BestPeer())
case <-forceSync.C:
// Force a sync even if not enough peers are present
go pm.synchronise(pm.peers.BestPeer())
case <-pm.noMorePeers:
return
}
}
}
// synchronise tries to sync up our local block chain with a remote peer.
func (pm *ProtocolManager) synchronise(peer *peer) {
// Short circuit if no peers are available
if peer == nil {
return
// nextSyncOp determines whether sync is required at this time.
func (cs *chainSyncer) nextSyncOp() *chainSyncOp {
if cs.doneCh != nil {
return nil // Sync already running.
}
// Make sure the peer's TD is higher than our own
currentHeader := pm.blockchain.CurrentHeader()
td := pm.blockchain.GetTd(currentHeader.Hash(), currentHeader.Number.Uint64())
pHead, pTd := peer.Head()
if pTd.Cmp(td) <= 0 {
return
// Ensure we're at mininum peer count.
minPeers := defaultMinSyncPeers
if cs.forced {
minPeers = 1
} else if minPeers > cs.pm.maxPeers {
minPeers = cs.pm.maxPeers
}
// Otherwise try to sync with the downloader
mode := downloader.FullSync
if atomic.LoadUint32(&pm.fastSync) == 1 {
// Fast sync was explicitly requested, and explicitly granted
mode = downloader.FastSync
if cs.pm.peers.Len() < minPeers {
return nil
}
if mode == downloader.FastSync {
// Make sure the peer's total difficulty we are synchronizing is higher.
if pm.blockchain.GetTdByHash(pm.blockchain.CurrentFastBlock().Hash()).Cmp(pTd) >= 0 {
return
}
// We have enough peers, check TD.
peer := cs.pm.peers.BestPeer()
if peer == nil {
return nil
}
// Run the sync cycle, and disable fast sync if we've went past the pivot block
if err := pm.downloader.Synchronise(peer.id, pHead, pTd, mode); err != nil {
return
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 *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 atomic.LoadUint32(&cs.pm.fastSync) == 1 {
block := cs.pm.blockchain.CurrentFastBlock()
td := cs.pm.blockchain.GetTdByHash(block.Hash())
return downloader.FastSync, td
} else {
head := cs.pm.blockchain.CurrentHeader()
td := cs.pm.blockchain.GetTd(head.Hash(), head.Number.Uint64())
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.pm.doSync(op) }()
}
// doSync synchronizes the local blockchain with a remote peer.
func (pm *ProtocolManager) doSync(op *chainSyncOp) error {
// Run the sync cycle, and disable fast sync if we're past the pivot block
err := pm.downloader.Synchronise(op.peer.id, op.head, op.td, op.mode)
if err != nil {
return err
}
if atomic.LoadUint32(&pm.fastSync) == 1 {
log.Info("Fast sync complete, auto disabling")
atomic.StoreUint32(&pm.fastSync, 0)
}
// If we've successfully finished a sync cycle and passed any required checkpoint,
// enable accepting transactions from the network.
head := pm.blockchain.CurrentBlock()
@@ -226,6 +305,7 @@ func (pm *ProtocolManager) synchronise(peer *peer) {
atomic.StoreUint32(&pm.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
@@ -233,6 +313,8 @@ func (pm *ProtocolManager) synchronise(peer *peer) {
// 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.
go pm.BroadcastBlock(head, false)
pm.BroadcastBlock(head, false)
}
return nil
}