plugeth/eth/sync.go

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package eth
import (
"math"
"time"
"github.com/ethereum/go-ethereum/eth/downloader"
"github.com/ethereum/go-ethereum/logger"
"github.com/ethereum/go-ethereum/logger/glog"
)
// Sync contains all synchronisation code for the eth protocol
func (pm *ProtocolManager) update() {
// itimer is used to determine when to start ignoring `minDesiredPeerCount`
itimer := time.NewTimer(peerCountTimeout)
// btimer is used for picking of blocks from the downloader
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btimer := time.Tick(blockProcTimer)
for {
select {
case <-pm.newPeerCh:
// Meet the `minDesiredPeerCount` before we select our best peer
if len(pm.peers) < minDesiredPeerCount {
break
}
// Find the best peer
peer := getBestPeer(pm.peers)
if peer == nil {
glog.V(logger.Debug).Infoln("Sync attempt cancelled. No peers available")
}
itimer.Stop()
go pm.synchronize(peer)
case <-itimer.C:
// The timer will make sure that the downloader keeps an active state
// in which it attempts to always check the network for highest td peers
// Either select the peer or restart the timer if no peers could
// be selected.
if peer := getBestPeer(pm.peers); peer != nil {
go pm.synchronize(peer)
} else {
itimer.Reset(5 * time.Second)
}
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case <-btimer:
go pm.processBlocks()
case <-pm.quitSync:
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return
}
}
}
// processBlocks will attempt to reconstruct a chain by checking the first item and check if it's
// a known parent. The first block in the chain may be unknown during downloading. When the
// downloader isn't downloading blocks will be dropped with an unknown parent until either it
// has depleted the list or found a known parent.
func (pm *ProtocolManager) processBlocks() error {
pm.wg.Add(1)
defer pm.wg.Done()
blocks := pm.downloader.TakeBlocks()
if len(blocks) == 0 {
return nil
}
glog.V(logger.Debug).Infof("Inserting chain with %d blocks (#%v - #%v)\n", len(blocks), blocks[0].Number(), blocks[len(blocks)-1].Number())
for len(blocks) != 0 && !pm.quit {
max := int(math.Min(float64(len(blocks)), float64(blockProcAmount)))
_, err := pm.chainman.InsertChain(blocks[:max])
if err != nil {
return err
}
blocks = blocks[max:]
}
return nil
}
func (pm *ProtocolManager) synchronize(peer *peer) {
// Make sure the peer's TD is higher than our own. If not drop.
if peer.td.Cmp(pm.chainman.Td()) <= 0 {
return
}
// FIXME if we have the hash in our chain and the TD of the peer is
// much higher than ours, something is wrong with us or the peer.
// Check if the hash is on our own chain
if pm.chainman.HasBlock(peer.recentHash) {
return
}
// Get the hashes from the peer (synchronously)
err := pm.downloader.Synchronize(peer.id, peer.recentHash)
if err != nil && err == downloader.ErrBadPeer {
glog.V(logger.Debug).Infoln("removed peer from peer set due to bad action")
pm.removePeer(peer)
} else if err != nil {
// handle error
glog.V(logger.Detail).Infoln("error downloading:", err)
}
}