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package eth
import (
"math/rand"
"time"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/logger"
"github.com/ethereum/go-ethereum/logger/glog"
"github.com/ethereum/go-ethereum/p2p/discover"
)
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
// This is the target size for the packs of transactions sent by txsyncLoop.
// A pack can get larger than this if a single transactions exceeds this size.
txsyncPackSize = 100 * 1024
)
type txsync struct {
p *peer
txs []*types.Transaction
}
// syncTransactions starts sending all currently pending transactions to the given peer.
func (pm *ProtocolManager) syncTransactions(p *peer) {
txs := pm.txpool.GetTransactions()
if len(txs) == 0 {
return
}
select {
case pm.txsyncCh <- &txsync{p, txs}:
case <-pm.quitSync:
}
}
// txsyncLoop takes care of the initial transaction sync for each new
// connection. When a new peer appears, we relay all currently pending
// transactions. In order to minimise egress bandwidth usage, we send
// the transactions in small packs to one peer at a time.
func (pm *ProtocolManager) txsyncLoop() {
var (
pending = make(map[discover.NodeID]*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) {
// Fill pack with transactions up to the target size.
size := common.StorageSize(0)
pack.p = s.p
pack.txs = pack.txs[:0]
for i := 0; i < len(s.txs) && size < txsyncPackSize; i++ {
pack.txs = append(pack.txs, s.txs[i])
size += s.txs[i].Size()
}
// Remove the transactions that will be sent.
s.txs = s.txs[:copy(s.txs, s.txs[len(pack.txs):])]
if len(s.txs) == 0 {
delete(pending, s.p.ID())
}
// Send the pack in the background.
glog.V(logger.Detail).Infof("%v: sending %d transactions (%v)", s.p.Peer, len(pack.txs), size)
sending = true
go func() { done <- pack.p.SendTransactions(pack.txs) }()
}
// pick chooses the next pending sync.
pick := func() *txsync {
if len(pending) == 0 {
return nil
}
n := rand.Intn(len(pending)) + 1
for _, s := range pending {
if n--; n == 0 {
return s
}
}
return nil
}
for {
select {
case s := <-pm.txsyncCh:
pending[s.p.ID()] = s
if !sending {
send(s)
}
case err := <-done:
sending = false
// Stop tracking peers that cause send failures.
if err != nil {
glog.V(logger.Debug).Infof("%v: tx send failed: %v", pack.p.Peer, err)
delete(pending, pack.p.ID())
}
// Schedule the next send.
if s := pick(); s != nil {
send(s)
}
case <-pm.quitSync:
return
}
}
}
// 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.fetcher.Start()
defer pm.fetcher.Stop()
defer pm.downloader.Terminate()
// Wait for different events to fire synchronisation operations
forceSync := time.Tick(forceSyncCycle)
for {
select {
case <-pm.newPeerCh:
// Make sure we have peers to select from, then sync
if pm.peers.Len() < minDesiredPeerCount {
break
}
go pm.synchronise(pm.peers.BestPeer())
case <-forceSync:
// Force a sync even if not enough peers are present
go pm.synchronise(pm.peers.BestPeer())
case <-pm.quitSync:
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
}
// Make sure the peer's TD is higher than our own. If not drop.
if peer.Td().Cmp(pm.chainman.Td()) <= 0 {
return
}
// Otherwise try to sync with the downloader
pm.downloader.Synchronise(peer.id, peer.Head())
}
|
